WO2023152701A1 - Multi-temperature double-acting piston - Google Patents

Abstract

The invention relates to a multi-temperature double-acting piston (201), which comprises a peripheral sealing ring (220), a lower hot crown (226) and/or an upper hot crown (232), and translates in a cold cylinder (204) of a heat engine (202) which has a lower yoke (213) and an upper yoke (214), said piston (201) comprising a central piston pin (210), the lower piston rod (211) of which passes through the lower yoke (213) to be connected to power transmission means (205) housed in a transmission housing (206), and the upper piston rod (212) of which passes through the upper yoke (214) in order to open into a cooling and piston lubrication chamber (217), wherein a lubrication-cooling gallery (227) arranged in said pin (210) places said chamber (217) in communication with said housing (206) via an internal piston volume (228).

Description

Description

Title of the invention: DOUBLE-ACTING MULTI-TEMPERATURE PISTON

[1] The present invention relates to a multi-temperature double-acting piston, said piston being particularly suitable for reciprocating engines implementing the regenerative Brayton thermodynamic cycle with pistons rather than with centrifugal compressors and turbines.

[2] Regenerative Brayton cycle engines generally comprise separate organs dedicated to each of the phases of said cycle, said phases taking place continuously and simultaneously in said organs, unlike reciprocating internal combustion engines using the Beau de Rochas cycle, Miller, Atkinson or Diesel whose phases are carried out successively in one and the same cylinder.

[3] Consequently, regenerative Brayton cycle engines comprise at least one compressor, at least one regenerative exchanger, at least one burner operating continuously or an internal or external heat source, and at least one expansion valve,

[4] Entrusting each phase of a thermodynamic cycle to a dedicated body has various advantages. In particular, the temperature of the internal walls of each said member can remain very close to that of the gases during said phase.

[5] For example, the temperature of the internal walls of the compressor of a regenerative Brayton cycle engine can be kept as low as possible, which helps to minimize the work of compression and to maximize the total thermodynamic efficiency of said engine.

[6] Conversely, the internal walls of the expansion valve of the said engine being in contact with the hot gases coming from the burner, their temperature must be high and in all cases maintained as close as possible to the average temperature of the said gases between the beginning and end of their relaxation.

[7] Despite these advantages, the maximum thermodynamic efficiency of engines with centrifugal compressors and regenerative Brayton cycle turbines is in practice hardly higher than that of conventional spark-ignition engines, and at best, comparable to that of engines Fast diesels. [8] In all cases, said efficiency remains lower than that of slow two-stroke diesel engines of several tens of megawatts used for example for naval propulsion or stationary electricity production.

[9] In addition, motors with centrifugal compressors and regenerative Brayton cycle turbines are poorly suited to low power, and can only operate over a restricted power range outside of which their efficiency drops drastically.

[10] This is why motors with centrifugal compressors and regenerative Brayton cycle turbines are mainly used in applications where efficiency is not the only objective, and which require, for example, a specific and specific power high, low noise and vibration emissions, long life, or low maintenance.

[1 1 ] This is the case, for example, of certain military ships equipped, for example, with the engine with centrifugal compressors and regenerative Brayton cycle turbines "Rolls-Royce WR-21", whose efficiency hardly exceeds forty percent however, that of the slow two-stroke Diesel engines fitted to certain ships exceeds fifty percent.

[12] This is also the case for certain generating sets most often operating in cogeneration of electricity and heat, such as the "T100" micro-turbine from the "Turbec" company, or the "C65" micro-turbine from the "Capstone" company, whose electrical efficiencies are only around twenty-eight to thirty percent, but which require little maintenance while offering very long lifespans.

[13] The advantage of these turbine engines is that their turbine can withstand temperatures of the order of one thousand three hundred degrees Celsius. However, their total thermodynamic efficiency remains limited by that of the centrifugal compressors and turbines which constitute them, the efficiency of said compressors and said turbines hardly exceeding eighty percent over a relatively narrow operating range.

[14] Taking into account the above, it would be particularly interesting to be able to replace the centrifugal compressors and turbines of cycle engines from Brayton to regeneration by volumetric piston machines whose efficiency is notoriously higher.

[15] This is for example the subject of patent No. US4653269 of March 31, 1987, where the expansion turbine ordinarily found on regenerative Brayton cycle turbine engines is replaced by a volumetric piston expansion cylinder.

[16] However, calculations show that if the internal walls of said volumetric expansion valve are cooled and maintained, for example, around one hundred degrees Celsius, like reciprocating engines produced and marketed on a large scale, the thermodynamic efficiency of a cycle engine regenerative Brayton fuel cannot exceed that of an automotive diesel engine.

[17] For a regenerated Brayton cycle engine with a volumetric expander to deliver very high thermodynamic efficiencies, it is essential that the internal walls of its expander are maintained at a temperature close to the average temperature of the gases expanded in said expander.

[18] For example, if the hot gases are introduced into the regulator at a temperature of one thousand three hundred degrees Celsius and are expelled from said regulator at the end of expansion at a temperature of six hundred degrees Celsius, the internal walls of said regulator must maintained at approximately nine hundred and fifty degrees Celsius.

[19] The problem is that at such a temperature, it is impossible to keep a film of oil on the walls of the regulator cylinder to lubricate any sealing ring that a regulator piston would have. moving in said cylinder.

[20] Indeed, from about one hundred and sixty degrees Celsius, the film of oil on the cylinder begins to coke, then burns above two hundred and fifty degrees Celsius.

[21] Producing a regenerative Brayton cycle engine with high thermodynamic efficiency therefore faces a double impasse.

[22] Indeed, either said engine is made up of centrifugal compressors and high-temperature resistant turbines, but in this case, the modest efficiency of these components does not allow it to exceed a total efficiency equivalent to that of an automobile diesel, or it is made up of a volumetric piston pressure reducer which, to be sealed, requires a piston provided with a segmentation sliding on a film of oil formed on the surface of a cylinder, the latter in front for this to remain at a temperature not exceeding approximately one hundred and twenty degrees Celsius, which also does not allow the total efficiency of said motor to be competitive.

[23] In this context, it would be advantageous to be able to combine the ability of turbines to operate at high temperature with that of volumetric piston machines to expand gases at high efficiency.

[24] It is for this purpose that the thermal transfer-expansion and regeneration engine according to patent WO2016120560 published on August 4, 2016 and belonging to the applicant comprises non-contact piston sealing means consisting of a continuous inflatable perforated ring which, when subjected to a certain internal pressure, swells and comes within a few micrometers of the regulator cylinder with which it cooperates without touching said cylinder, this while allowing compressed air to leak via calibrated orifices which cross right through in its radial thickness.

[25] The fluid cushion sealing device which has just been described was also the subject of patent No. FR 3032252 issued on May 25, 2018 and belonging to the applicant. This device makes it possible to achieve contactless sealing and therefore to no longer use oil to lubricate a segment operating by contact, and therefore to cooperate with a hot expansion cylinder, maintained at a temperature of several hundred degrees. Celsius.

[26] In this context, it therefore becomes effectively possible to use a volumetric piston expander to produce a regenerative Brayton cycle engine, and to maximize the efficiency of said engine to greatly exceed that of diesel cycle engines.

[27] Indeed, calculations and simulations show that the thermodynamic efficiency of a Brayton cycle engine with volumetric regeneration with pistons can reach or even exceed seventy percent, which in practice can lead to the production of engines whose the energy efficiency at the brake exceeds sixty percent after deducting the inevitable thermal and mechanical irreversibility due to the very constitution of said motors.

[28] The problem encountered with the fluid cushion sealing device of patent No. FR 3032252 is that the temperature of the cylinder is still excessive for the available materials of which the perforated continuous ring can be made.

[29] Indeed, for the efficiency of a Brayton cycle engine with volumetric regeneration with pistons to be significantly higher than that of existing Diesel engines, the gases must be introduced into its regulator at a temperature of the order of one thousand three hundred degrees Celsius, under a pressure of around twenty bars.

[30] It follows from these operational conditions that the temperature of the internal walls of the regulator stabilizes around nine hundred and fifty degrees Celsius.

[31] Since the perforated continuous ring according to patent No. FR 3032252 is close to the cylinder with which it cooperates by only a few microns, in practice, said ring adopts the temperature of approximately nine hundred and fifty degrees Celsius of said cylinder.

[32] However, no material can both make it possible to manufacture said ring and withstand such a temperature.

[33] Even a superalloy such as "Udimet 720", used in particular in aeronautics and the space industry and known for its resistance to extreme temperatures, cannot withstand such a temperature without being subject to creep and while being subjected to swelling stress imposed by the perforated continuous ring of the fluid cushion sealing device according to patent No. FR 3032252.

[34] It is in particular for this reason and to use more common materials than high-temperature resistant ceramics that the regenerative cooling system according to patent No. EP 3585993 published on April 7, 2021 and belonging to the applicant provides for lowering the temperature of the internal walls of the regulator and in particular of the cylinder to practical values of the order of seven hundred degrees Celsius. [35] For example, the "Udimet 720" superalloy resists creep at a temperature of seven hundred degrees Celsius if subjected to a stress not exceeding two hundred and thirty mega Pascals.

[36] The regenerative cooling system according to patent No. EP 3585993 provides a cooling enclosure which envelops the expander while a gas circulation space is left between said enclosure and said expander in which the gases flowing out of the expander itself -even at a temperature between five hundred and six hundred degrees Celsius.

[37] Thus, according to the regenerative cooling system according to patent No. EP 3585993, the exhaust gases from the expander maintain the temperature of the internal walls of the expander at a temperature of the order of seven hundred degrees Celsius, while the The heat exported by said gases is essentially recovered to be reintroduced into the cycle by the regeneration heat exchanger which comprises the reciprocating engine with regenerative Brayton cycle piston.

[38] In this context, the fluid cushion sealing device of patent No. FR 3032252 can be used with a continuous perforated ring, for example made of “Udimet 720” superalloy.

[39] However, in return for this possibility, the cylinder and cylinder heads of the regenerative Brayton cycle piston reciprocating engine must be made of materials with a high nickel content such as "Niresist" cast iron which, because of the high volatility and high price of nickel represents an economic disadvantage.

[40] In all cases, we note that the temperature of the regulator remains at least six hundred degrees Celsius higher than that of the rest of the engine and in particular, of the mobile coupling and of the transmission casing in which said said coupling.

[41] Advantageously, the differential expansions which result from this temperature difference can in particular be managed by the double-acting expander cylinder with adaptive support, the subject of patent No. EP3350433 issued on August 7, 2019 and belonging to the applicant. [42] Said support allows an isotropic or anisotropic expansion of the expansion cylinder which is very different from that of the transmission casing on which it is fixed, this without compromising either the operation of said cylinder or that of the piston which evolves in said cylinder.

[43] Said support also keeps the piston centered in the cylinder, transmits the axial forces resulting from the expansion of the gases to the transmission casing, and limits heat transfer from the expander cylinder to said casing.

[44] On reading the foregoing, it is understood that no configuration is at this stage fully satisfactory which makes it possible to produce a regenerative Brayton cycle piston reciprocating engine in the best possible conditions.

[45] Indeed, the fluid cushion sealing device must be supplied with compressed air by a compressor which consumes part of the work available on the shaft of the regenerative Brayton cycle piston reciprocating engine, to the detriment of the its total return.

[46] This in fact reduces the final energy efficiency of said motor, all the more so if the latter operates at low power because the quantity of compressed air to be supplied to the fluid cushion sealing device is almost constant, whatever regardless of engine speed and load.

[47] Furthermore, to guarantee long-lasting operation of the fluid cushion sealing device, it is necessary to use the regenerative cooling system according to patent No. EP 3585993, but said system is not energy neutral.

[48] Indeed, said cooling system makes the path of the gases expelled from the expander tortuous and induces pressure drops which reduce the total efficiency of the reciprocating engine with regenerative Brayton cycle piston.

[49] In addition, the heat extracted from the internal walls of the expander by the regenerative cooling system is reintroduced into the Brayton cycle upstream of a burner or a hot source by a regenerative heat exchanger whose efficiency is not is not a hundred percent. [50] Part of the heat extracted from the internal walls of the expander is therefore lost, and the power passing through the exchanger increases due to the presence of said cooling system.

[51] In addition, the mass power of the regenerative Brayton cycle piston reciprocating engine is significantly reduced by the regenerative cooling system according to patent No. EP 3585993, which involves revising the sizing of said engine upwards to meet the power objectives of the application for which it is intended.

[52] It is also noted that the development of the fluid cushion sealing device of patent No. FR 3032252 remains complex, particularly to ensure its proper functioning in the context of non-stationary applications subject to shocks and vibes.

[53] This is why, without excluding any other application in any field whatsoever, the reciprocating heat engine with hot cylinder head and cold cylinder according to the invention is, among other things, intended to produce reciprocating Brayton cycle piston engines at regeneration whose mainly hot expansion valve limits heat losses, and this, while ensuring a robust and durable seal between the piston and the cylinder of said expansion valve.

[54] In the field of application of reciprocating piston heat engines in general and heat engines in particular, the invention results in a multi-temperature double-acting piston:

• Whose piston caps are kept at high temperature so as to limit the cooling of the hot gases in contact with them;

• Whose sealing with the cylinder with which it cooperates can be achieved by means of cast iron or steel segments such as those included in conventional internal combustion engines with spark ignition or Diesel cycle;

• Which no longer uses the fluid cushion sealing device covered by patent No. FR 3032252 and therefore no longer requires that the engine which receives it be equipped with a regenerative cooling system such as that described in patent No. EP 3585993, said engine therefore no longer undergoing the loss of power and efficiency linked to the use of a compressor supplying said sealing device, nor the additional pressure losses at the exhaust of the expander linked to a more tortuous path of the gases, nor the heat losses due to the less than "one" efficiency of the regeneration heat exchanger, nor the specific engine power losses associated with this configuration.

[55] Consequently, the multi-temperature double-acting piston according to the invention makes it possible to prevent the engine that houses it from being manufactured with materials with a high nickel content such as "Niresist" cast iron, the cylinder of said engine which can be made of cast iron at low cost such as that ordinarily used to make the cylinder casings of automobile diesel engines, and said engine which can comprise hot cylinder heads operating at high temperature made of silicon carbide, a high-strength material high temperature mechanics, plentiful and cheap.

[56] As an advantage induced by the multi-temperature double-acting piston according to the invention, the lower density of the silicon carbide which it allows the use to produce the hot cylinder heads of the engine which houses it on the one hand, and the absence of a regenerative cooling system on the other hand, lead to a lower weight and a lower total heat capacity of said engine.

[57] This promotes a rapid rise in temperature of said engine by reducing the energy required to reach its operating temperature, and leads to lower energy consumption of said engine, particularly when the latter is applied to road transport, rail, or sea.

[58] It is understood that the multi-temperature double-acting piston according to the invention can be applied, in addition to heat engines in general stationary or mobile and with internal or external combustion, to any other application similar in concept and in principle. which could advantageously take advantage of the particular characteristics and functionalities of said piston according to the invention.

[59] The other features of the present invention have been described in the description and in the secondary claims depending directly or indirectly from the main claim. [60] The multi-temperature double-acting piston capable of translating in a cold cylinder arranged in a cooled cylinder block that includes a heat engine, said piston being directly or indirectly connected by power transmission means housed in a transmission casing to at least at least one rotating or reciprocating power output shaft while said piston forms a lower variable volume chamber with the cold cylinder and a lower cylinder head which is positioned between said piston and the transmission housing, said piston simultaneously forming a variable volume chamber upper with said cylinder and an upper cylinder head, said chambers, containing a working gas, comprise

• A central piston pin approximately coaxial with the cold cylinder and of which a first end forms a lower piston rod which passes right through the lower cylinder head via a lower rod orifice which cooperates with lower rod sealing means to open in the transmission casing and to be directly or indirectly connected to the power transmission means by piston fixing means, while the second end of said pin forms an upper piston rod which passes right through the upper cylinder head via an upper rod orifice which cooperates with upper rod sealing means to open into a piston cooling and lubrication chamber connected to a source of lubricant-coolant fluid, the latter introducing a lubricant-coolant fluid into said chamber;

• A peripheral sealing ring whose outer diameter is substantially smaller than the inner diameter of the cold cylinder, said ring comprising piston sealing means which are in contact with said cylinder to achieve a seal with the latter;

• A lower radial connection disc which radially connects the central piston pin with the peripheral sealing ring on the side of the lower variable volume chamber, and an upper radial connection disc which radially connects the central piston pin with the peripheral sealing ring on the side of the upper variable volume chamber, the space left between said discs, the peripheral sealing ring and the central piston pin forming an internal volume of the piston;

• A lubrication-cooling gallery arranged mainly axially in the central piston pin and in one or more sections, said gallery communicating on the one hand, the piston cooling and lubrication chamber with the internal piston volume, and on the other hand, said volume with the interior of the transmission casing;

• At least one peripheral ring lubrication orifice which places the internal volume of the piston in communication with the outer peripheral face of the peripheral sealing ring, said orifice emerging axially from said face between at least two sealing means of plunger;

• Guide means which bear directly or indirectly on or close to the power transmission means and/or the cold cylinder and/or the lower cylinder head and/or the upper cylinder head, said means directly or indirectly retaining the peripheral sealing ring centered in the cold cylinder;

• A lower hot cap interposed between the lower radial connection disc and the lower variable-volume chamber and/or an upper hot cap interposed between the upper radial connection disc and the upper variable-volume chamber;

• Cap pressing means which directly or indirectly hold the lower hot dome pressed against the peripheral sealing ring and/or on the lower radial connection disc, and/or which directly or indirectly hold the upper hot dome pressed against said ring and/or on the upper radial connection disc, said means leaving said caps free to expand relative to said ring and/or said discs;

Cap centering means which locate the lower hot cap and/or the upper hot cap with respect to the peripheral sealing ring. [61] The multi-temperature double-acting piston according to the invention comprises a lower hot cap and/or an upper hot cap which are wholly or partly made of a material resistant to high temperatures.

[62] The multi-temperature double-acting piston according to the invention comprises a material resistant to high temperatures which is mainly made of silicon carbide.

[63] The multi-temperature double-acting piston according to the invention comprises thermal insulation means and/or cap sealing means which are interposed either between the lower hot cap and the peripheral sealing ring and/or or the lower radial connection disk, either between the upper hot cap and said ring and/or the upper radial connection disk, or both.

[64] The multi-temperature double-acting piston according to the invention comprises thermal insulation means and/or cap sealing means which are interposed either between the lower hot cap and the central piston pin, or between the upper hot cap and said pin, or both.

[65] The multi-temperature double-acting piston according to the invention comprises thermal insulation means which consist of at least one insulating ring made of a material with low thermal conductivity.

[66] The multi-temperature double-acting piston according to the invention comprises a material with low thermal conductivity which consists mainly of zirconium oxide.

[67] The multi-temperature double-acting piston according to the invention comprises an insulating ring which is held directly or indirectly in contact with the central piston pin and/or the peripheral sealing ring and/or the lower hot cap and/ or the lower radial connection disc and/or the upper hot cap and/or the upper radial connection disc via at least one small surface contact edge.

[68] The multi-temperature double-acting piston according to the invention comprises an insulating ring which is held directly or indirectly in contact with the central piston pin and/or the peripheral sealing ring and/or the cap lower hot plate and/or the lower radial connection disk and/or the upper hot cap and/or the upper radial connection disk via at least one insulating ring seal which is gastight from work.

[69] The multi-temperature double-acting piston according to the invention comprises cap pressing means which directly or indirectly hold the lower hot cap pressed against the peripheral sealing ring and/or on the lower radial connecting disc, which are formed of an outer coaxial lower spindle tube which envelops the central piston spindle, said tube bearing on the one hand, on the lower hot cap in the vicinity of said spindle, and on the other hand, on the transmission means power.

[70] The multi-temperature double-acting piston according to the invention comprises cap pressing means which directly or indirectly hold the upper hot cap pressed against the peripheral sealing ring and/or on the upper radial connecting disc, which are formed of an outer coaxial upper pin tube which envelops the central piston pin, said tube bearing on the one hand, on the upper hot cap in the vicinity of said pin, and on the other hand, on a rod stop upper arranged directly or indirectly on the upper piston rod in the vicinity of its end which opens into the piston cooling and lubrication chamber.

[71] The multi-temperature double-acting piston according to the invention comprises some or all of the ends of an outer coaxial pin lower tube and/or an outer coaxial upper pin tube which receive a tube spring via of which said tubes bear respectively on the lower hot cap and on the power transmission means and/or on the upper hot cap and on the upper rod stop.

[72] The multi-temperature double-acting piston according to the invention comprises a lower hot cap and/or an upper hot cap which has a concave conical cap surface by means of which said cap is held flat by the pressing means of cap on a circular peripheral contact edge which is directly or indirectly attached to the peripheral sealing ring and/or to the periphery of the connecting disc lower radial and/or of the periphery of the upper radial connecting disc, the angle of the concave cone formed by said surface being such that when said surface slides on said edge due to the difference between the thermal expansion of said cap and that of the assembly formed by the peripheral sealing ring, the lower radial connection disk, the upper radial connection disk and the central piston pin, the axial distance which separates the bearing point from the cap plating means on said cap of the peripheral sealing ring remains approximately constant all other things being equal, while the concave conical surface of the cap and the circular peripheral contact edge form the cap centering means.

[73] The multi-temperature double-acting piston according to the invention comprises piston fixing means which consist of a double-acting piston axial screw which firstly comprises a piston screw body which is housed in a piston screw tunnel which crosses right through the central piston pin in the direction of its length, said screw comprising on the one hand, a piston screw head which bears at the end of the upper piston rod which opens into the piston cooling and lubrication chamber, and on the other hand, a piston screw thread which is screwed into the power transmission means.

[74] The multi-temperature double-acting piston according to the invention comprises a piston screw tunnel which forms at least part of the lubrication-cooling gallery, the lubricating-cooling fluid being able to circulate between the piston screw body and the internal wall of said tunnel, the latter forming with said body a first section which goes from the piston cooling and lubrication chamber to the internal piston volume, and a second section which goes from said volume inside the transmission casing.

[75] The multi-temperature double-acting piston according to the invention comprises guide means which consist of a barrel-shaped skirt which is arranged on the outer periphery of the peripheral sealing ring and which rests on the cold cylinder.

[76] The multi-temperature double-acting piston according to the invention comprises a lubrication-cooling gallery which opens into the internal volume of piston via a small axial play left between, on the one hand, a fluid distribution disc which is housed in said volume and, on the other hand, the upper radial connection disc, said distribution disc being approximately parallel to said radial connection disc and forming on the one hand, a seal with the central pin of the piston, and ending on the other hand, radially in the vicinity of the internal wall of the peripheral sealing ring, the cooling-lubricating fluid coming from the chamber piston cooling and lubrication that can exit at said vicinity.

[77] The multi-temperature double-acting piston according to the invention comprises a central piston pin which comprises, inside the internal volume of the piston and in the vicinity of the lower radial connecting disc, a fluid recirculation collar which, when the central piston pin moves in the direction of the lower cylinder head, rejects radially and in the direction of the inner wall of the peripheral sealing ring the lubricant-cooling fluid which has accumulated in said volume and on the surface of said disk.

[78] The multi-temperature double-acting piston according to the invention comprises a lower radial connection disc which has a hollow shape at its connection with the central piston pin, said shape constituting an overflow reservoir which can store lubricating-cooling fluid, while at least one overflow orifice which communicates with the interior of the transmission casing via the lubrication-cooling gallery fixes the maximum level of said reservoir.

[79] The multi-temperature double-acting piston according to the invention comprises a fluid nozzle fed by the source of lubricant-coolant fluid which opens into the piston cooling and lubrication chamber to inject a jet of fluid therein.

[80] The multi-temperature double-acting piston according to the invention comprises a fluid nozzle which injects a jet of lubricating-cooling fluid into an axial screw reservoir which is arranged axially in the piston screw head, said reservoir communicating with the lubrication-cooling gallery via at least one radial duct connecting tank-gallery. [81] The multi-temperature double-acting piston according to the invention comprises a screw check valve which is housed in the axial screw of the double-acting piston, said valve allowing the lubricant-cooling fluid to flow from the axial screw reservoir to the lubrication-cooling gallery, but not the reverse.

[82] The multi-temperature double-acting piston according to the invention comprises a piston cooling and lubrication chamber which is connected to a source of air by an air inlet check valve which lets in air from forcing fluid into said chamber without letting it out, while said chamber is connected to an air tank by a pressure relief valve which allows fluid forcing air to flow from said chamber to said tank when the pressure of said air in said chamber reaches a certain value.

[83] The multi-temperature double-acting piston according to the invention comprises a reflective screen which is interposed between the lower hot cap and the lower radial connection disc to which part of the peripheral sealing ring and/or , between the upper hot dome and the upper radial connecting disc to which part of said ring can be added.

[84] The multi-temperature double-acting piston according to the invention comprises thermal insulation means which consist of a cellular or fibrous insulating material which occupies all or part of the space between the lower hot cap and the lower radial connection and/or between the upper hot cap and the upper radial connection disc.

[85] The multi-temperature double-acting piston according to the invention comprises at least a first radial space left between the outer coaxial upper pin tube and the central piston pin, at least a second radial space left between the outer coaxial lower tube of pin and the piston center pin, and a plurality of radial spaces left between the piston screw body and the internal wall of the piston screw tunnel which form at least part of the lubrication-cooling gallery, the lubricating-cooling fluid being able to circulate successively in said spaces to go from the piston cooling and lubrication chamber to the internal piston volume, then from said volume inside the transmission casing. [86] The multi-temperature double-acting piston according to the invention comprises lower rod sealing means and/or upper rod sealing means which consist of an extendable continuous ring which is directly or indirectly integral with the housing -cooled cylinder, and whose inside diameter is substantially smaller than the outside diameter of the lower piston rod or of the upper piston rod that it encloses.

[87] The multi-temperature double-acting piston according to the invention comprises an extensible continuous ring which is connected to a ring plate by a ring tube of small radial thickness, said ring, said plate and said ring being made in a one and the same piece of matter.

[88] The multi-temperature double-acting piston according to the invention comprises a continuous extensible ring which is axially clamped between two ring rings by an axial ring compression spring.

[89] The description which will follow with regard to the appended drawings and given by way of non-limiting examples will make it possible to better understand the invention, the characteristics which it presents, and the advantages which it is likely to provide:

[90] [Fig. 1] is a three-dimensional view of a heat engine as it may be provided to receive the multi-temperature double-acting piston according to the invention, said engine forming an expansion valve which makes it possible, for example, to implement a thermodynamic cycle of Regenerative baritone.

[91] [Fig. 2] is a three-dimensional cross-sectional view of the multi-temperature double-acting piston according to the invention, housed in the heat engine shown in FIG. 1, said engine also being represented in three-dimensional cross-section.

[92] [Fig. 3] is a sectional view of the multi-temperature double-acting piston according to the invention, housed in the heat engine shown in FIG. 1, said engine also being shown in section.

[93] [Fig. 4] is a three-dimensional sectional view of the multi-temperature double-acting piston according to the invention, said piston being connected to the power transmission means by a double-acting piston axial screw while the cap plating means consist in particular of an external coaxial lower spindle tube and an external coaxial upper spindle tube.

[94] [Fig. 5] is an exploded three-dimensional view of the multi-temperature double-acting piston according to the invention and according to its particular configuration shown in figures 2 to 5.

[95] [Fig. 6] is a close-up cross-sectional view of the multi-temperature double-acting piston according to the invention placed in the context of the engine shown in FIG. 1, said view showing in particular how said piston is connected to the power transmission means, and how the lower hot cap is held pressed against the peripheral sealing ring by an outer coaxial lower pin tube via insulating rings.

[96] [Fig. 7] is a close-up cross-sectional view of the multi-temperature double-acting piston according to the invention placed in the context of the engine shown in FIG. 1, said view showing in particular how the upper piston rod opens into the cooling and lubrication chamber piston, and how the upper hot cap is held pressed against the peripheral sealing ring by an external coaxial upper pin tube via insulating rings.

[97] [Fig. 8] is a cross-sectional view of the multi-temperature double-acting piston according to the invention as shown in FIGS. 2 to 7, said view showing how a lubricating-cooling fluid can circulate from an axial screw reservoir to the interior of the transmission casing to successively cool the upper radial connection disc, the peripheral sealing ring and the lower radial connection disc, this while cooling and lubricating the piston sealing means and the barrel skirt that said ring, said means and said skirt being kept in contact with the cold cylinder.

[98] [Fig. 9] is a sectional view of the multi-temperature double-acting piston according to the invention as shown in FIG. 8, said view showing in particular how the lubricating-cooling fluid can recirculate inside the internal volume of the piston to complete the cooling of the mechanically welded assembly formed by the peripheral sealing ring, the lower radial connection disc, the upper radial connection disc and the central piston pin, and to supply peripheral ring lubrication orifices that the peripheral sealing ring comprises.

[99] [Fig. 10] is a close-up schematic sectional view of the multi-temperature double-acting piston according to the invention and according to the particular configuration of said piston as shown in FIGS. 2 to 9, said view showing the position and dimensions of the lower and upper hot caps by relative to the mechanically welded assembly and to the insulating ring when said caps are cold.

[100] [Fig. 11] is a close-up schematic sectional view of the multi-temperature double-acting piston according to the invention and according to the particular configuration of said piston as shown in FIGS. 2 to 9, said view showing the position and dimensions of the lower and upper hot caps by relative to the mechanically welded assembly and to the insulating ring when said caps are hot.

[101] [Fig. 12] is a three-dimensional view framed on the piston cooling and lubrication chamber of the multi-temperature double-acting piston according to the invention, said view showing in particular the air intake non-return valve and the pressure limiting valve which are both connected inside the transmission case which here acts as an air source and air cover.

[102] [Fig. 13] is a sectional view of a variant of the multi-temperature double-acting piston according to the invention in which part of the lubrication-cooling gallery is formed by a radial space left between, on the one hand, the outer coaxial upper tube spindle and the lower outer coaxial spindle tube and on the other hand, the central piston spindle, while a reflective screen and a cellular or fibrous insulating material are interposed between the lower and upper hot caps and the radial connecting disc lower and upper facing said caps.

[103] [Fig. 14] is a close-up sectional view of the upper rod sealing means of the multi-temperature double-acting piston according to the invention, said means being constituted by an extendable continuous ring connected to a ring plate by a ring tube thin radial thickness. [104] [Fig. 15] is a close-up sectional view of the upper rod sealing means of the multi-temperature double-acting piston according to the invention, said means being constituted by an axially extensible continuous ring sandwiched between two ring rings by a compression spring ring axial.

[105] DESCRIPTION OF THE INVENTION:

[106] Figures 1 to 12 show the multi-temperature double-acting piston 201 according to the invention, various details of its components, its variants, and its accessories.

[107] As shown in Figures 2, 3, 6 and 7, the multi-temperature double-acting piston 201 can translate in a cold cylinder 204 arranged in a cooled cylinder block 203 that includes a heat engine 202, said piston 201 being directly or indirectly connected by power transmission means 205 housed in a transmission casing 206 to at least one rotary or reciprocating power output shaft 207 .

[108] As clearly seen in Figure 7, said piston 201 forms a lower variable volume chamber 208 with the cold cylinder 204 and a lower cylinder head 213 which is positioned between said piston 201 and the transmission housing 206, said piston 201 simultaneously forming an upper variable volume chamber 209 with said cylinder 204 and an upper cylinder head 214, said chambers 208, 209 containing a working gas 240.

[109] As illustrated in Figures 2 to 5 and in Figures 8 and 9, the multi-temperature double-acting piston 201 according to the invention comprises a central piston pin 210 approximately coaxial with the cold cylinder 204 and of which a first end forms a lower rod piston 211 which crosses right through the lower cylinder head 213 via a lower rod orifice 215 which cooperates with lower rod sealing means 280 to open into the transmission casing 206 and to be directly or indirectly connected to the means of power transmission 205 by piston fixing means 231 .

[110] The second end of said pin 210 forms an upper piston rod 212 which passes right through the upper cylinder head 214 via an upper rod orifice 216 which cooperates with upper rod sealing means 281 for emerge into a cooling chamber and piston lubricator 217 connected to a source of lubricating-cooling fluid 218, the latter introducing a lubricating-cooling fluid 257 into said chamber 217.

[111] It is noted that the lower rod sealing means 280 and the upper rod sealing means 281 can be respectively in contact with the lower piston rod 211 and with the upper piston rod 212 either directly or indirectly via an outer coaxial lower tube of spindle 243 and an outer coaxial upper spindle tube 248, respectively, as illustrated in Figures 2, 3, 6, 7, 14 and 15.

[112] Note in Figures 2 to 11 that the multi-temperature double-acting piston 201 according to the invention comprises a peripheral sealing ring 220 whose outer diameter is substantially smaller than the inner diameter of the cold cylinder 204.

[113] It is noted in said figures that the peripheral sealing ring 220 comprises piston sealing means 221, for example consisting of compression rings 222 of cast iron or steel such as those ordinarily found on the pistons of automobile engines conventional, said means 221 being in contact with said cylinder 204 to achieve a seal with the latter.

[114] It is seen very clearly in Figure 4 that the multi-temperature double-acting piston 201 according to the invention also comprises a lower radial connecting disc 224 which radially connects the central piston pin 210 with the peripheral sealing ring 220 of the side of the lower variable volume chamber 208, and an upper radial connection disc 225 which radially connects the central piston pin 210 with the peripheral sealing ring 220 on the side of the upper variable volume chamber 209, the space left between said discs 224, 225, the peripheral sealing ring 220 and the central piston pin 210 forming an internal piston volume 228.

[115] It will be noted that the lower radial connection disk 224 and/or the upper radial connection disk 225 can be a simple metal disk, a cone, a dome or a frustosphere, or be of any non-ribbed geometry or ribbed to give said discs 224, 225 great rigidity. [116] It is also noted that as an alternative embodiment of the multi-temperature double-acting piston 201 according to the invention, the lower radial connecting disc 224 can be connected inside the internal volume of the piston 228 to the connecting disc upper radial 225 by stays, spokes, fins or by any other mechanical connection which secures said discs 224, 225 so that they constitute a rigid assembly.

[117] It will also be noted that the lower radial connecting disc 224 and/or the upper radial connecting disc 225 can preferably be secured to the central piston pin 210 and/or the peripheral sealing ring 220 by welding. by friction, by electron beam or by arc welding, or not any type of welding or assembly known to those skilled in the art.

[118] It is noted in Figures 8 and 9 that the multi-temperature double-acting piston 201 according to the invention comprises a lubrication-cooling gallery 227 which is arranged mainly axially in the central piston pin 210 and in one or more sections, said gallery 227 communicating on the one hand, the piston cooling and lubrication chamber 217 with the internal volume of the piston 228, and on the other hand, said volume 228 with the interior of the transmission casing 206.

[119] In Figures 10 and 11, it can be seen very clearly that the multi-temperature double-acting piston 201 according to the invention comprises at least one peripheral ring lubrication orifice 229 which places the internal volume of the piston 228 in communication with the outer peripheral face of peripheral sealing ring 220, said orifice 229 emerging axially from said face between at least two piston sealing means 221 .

[120] The multi-temperature double-acting piston 201 according to the invention also comprises guide means 230 particularly visible in FIG. 4, said means 230 bearing directly or indirectly on or near the power transmission means 205 and/or the cold cylinder 204 and/or of the lower cylinder head 213 and/or of the upper cylinder head 214, said means 230 directly or indirectly retaining the peripheral sealing ring 220 centered in the cold cylinder 204. [121] Particularly in Figure 7, it is noted that the multi-temperature double-acting piston 201 according to the invention comprises a lower hot cap 226 interposed between the lower radial connecting disc 224 and the lower variable volume chamber 208 and / or a cap upper heater 232 interposed between the upper radial connecting disc 225 and the upper variable volume chamber 209;

[122] The multi-temperature double-acting piston 201 according to the invention also comprises cap pressing means 234, which all appear in FIGS. 2 to 5 and in FIGS. 8 and 9, and which directly or indirectly hold the lower hot cap 226 pressed on the peripheral sealing ring 220 and/or on the lower radial connection disk 224, and/or which directly or indirectly hold the upper hot cap 232 pressed on said ring 220 and/or on the upper radial connection disk 225, said means 234 leaving said caps 226, 232 free to expand relative to said ring 220 and/or to said discs 224, 225.

[123] Finally, the multi-temperature double-acting piston 201 according to the invention comprises cap centering means 235 - for example shown in FIG. 7 - which locate the lower hot cap 226 and/or the upper hot cap 232 with respect to the peripheral sealing ring 220.

[124] It will be noted that according to an alternative embodiment of the multi-temperature double-acting piston 201 according to the invention, the lower hot cap 226 and/or the upper hot cap 232 may be wholly or partly made of a material resistant to high temperatures 275 such as silicon carbide 276 and its various variants, whether or not combined with other materials.

[125] As another variant shown in Figures 2 to 11, thermal insulation means 233 and / or cap sealing means 239 can be interposed either between the lower hot cap 226 and the peripheral ring seal 220 and/or the lower radial connecting disc 224, either between the upper hot cap 232 and said ring 220 and/or the upper radial connecting disc 225, or both, said means 233, 239 possibly forming part integral to said caps 226, 232 and/or said discs 224, 225. [126] In Figures 4 to 9, it has also been shown that thermal insulation means 233 and/or cap sealing means 239 can be interposed either between the lower hot cap 226 and the central piston pin 210 , either between the upper hot cap 232 and said spindle 210, or both, said means 233, 239 possibly forming an integral part of said caps 226, 232 and/or of said spindle 210.

[127] Wherever they are located, the thermal insulation means 233 can consist of at least one insulating ring 236 made of a low thermal conductivity material 237 such as zirconium oxide 238 and its various variants , whether or not combined with other materials, or such as quartz.

[128] As a non-limiting alternative, the insulating ring 236 can also be made of quartz whose thermal conductivity is also low, and whose low modulus of elasticity gives it a great ability to adapt to the geometry of the components with which it is in contact and cooperates.

[129] It will be noted that the insulating ring 236 can be maintained directly or indirectly in contact with the central piston pin 210 and/or the peripheral sealing ring 220 and/or the lower hot cap 226 and/or the disc of lower radial connection 224 and/or the upper hot cap 232 and/or the upper radial connection disc 225 via at least one small surface contact edge 241 .

[130] It will be noted in Figures 10 and 11 that advantageously, the insulating ring 236 may include a de-stiffening groove 291 which gives it more flexibility and which ensures a more homogeneous and better distributed contact between said ring 236 and the part 210, 220, 226, 224, 232, 225 with which said ring 236 cooperates.

[131] According to a particular configuration of the multi-temperature double-acting piston 201, the insulating ring 236 can also be kept directly or indirectly in contact with the central piston pin 210 and/or the peripheral sealing ring 220 and/or the lower hot cap 226 and/or the lower radial connection disc 224 and/or the upper hot cap 232 and/or the upper radial connection disc 225 via at least one insulating ring seal 242 which is tight to working gas 240. [132] It is noted that the insulating ring seal 242 may for example comprise several metal sheets like the cylinder head gaskets that modern automobile internal combustion heat engines have, or be made of materials resistant to high temperatures such as "Therma-pur" developed by the company "Garlock".

[133] As seen in Figures 2 to 9, the cap plating means 234 which directly or indirectly hold the lower hot cap 226 pressed against the peripheral sealing ring 220 and / or on the lower radial connecting disc 224, can be formed from an outer coaxial lower tube of spindle 243 which envelops the central piston spindle 210, said tube 243 bearing on the one hand, on the lower hot cap 226 in the vicinity of said spindle 210, and of on the other hand, on the power transmission means 205 which may for example consist of a stock 244 which translates in a stock cylinder 293, said stock 244 being articulated around the foot of a connecting rod 245 which is itself articulated around a crank 246 arranged on a crankshaft 247, the latter forming the power output shaft 207.

[134] It is also seen in Figures 2 to 5 and in Figures 7 to 9 that the cap pressing means 234 which directly or indirectly hold the upper hot cap 232 pressed against the peripheral sealing ring 220 and/or on the upper radial connecting disc 225, can be formed of an outer coaxial upper pin tube 248 which envelops the central piston pin 210, said tube 248 bearing on the one hand, on the upper hot cap 232 in the vicinity of said pin 210, and on the other hand, on an upper rod stop 249 provided directly or indirectly on the upper piston rod 212 near its end which opens into the piston cooling and lubrication chamber 217.

[135] As clearly seen in FIG. 4, some or all of the ends of the pin outer coaxial lower tube 243 and/or the pin outer coaxial upper tube 248 can receive a tube spring 250 through which said tubes 243, 248 bear respectively on the lower hot cap 226 and on the power transmission means 205 and/or on the upper hot cap 232 and on the upper rod stop 249, the tube spring 250 advantageously being made up of a stack of “Belleville” washers known per se.

[136] Figures 10 and 1 1 illustrate that according to a particular configuration of the multi-temperature double-acting piston 201 according to the invention, the lower hot cap 226 and / or the upper hot cap 232 can advantageously have a concave conical surface of cap 251 by means of which said cap 226, 232 is held flat by the cap pressing means 234 on a circular peripheral contact edge 252 which is directly or indirectly integral with the peripheral sealing ring 220 and/or the periphery of the lower radial connecting disc 224 and/or the periphery of the upper radial connecting disc 225.

[137] According to said configuration, the angle of the concave cone formed by the concave conical surface of cap 251 is such that when said surface 251 slides on said edge 252 due to the difference between the thermal expansion of said cap 226, 232 and that of the assembly formed by the peripheral sealing ring 220, the lower radial connection disc 224, the upper radial connection disc 225 and the central piston pin 210, the axial distance which separates the fulcrum cap plating means 234 on said cap 226, 232 of the peripheral sealing ring 220 remains approximately constant all other things being equal, while the concave conical surface of the cap 251 and the circular peripheral contact edge 252 form the cap centering means 235.

[138] Note that this particular configuration of the multi-temperature double-acting piston 201 according to the invention allows the force to which the cap pressing means 234 are subjected - which are outside the image in FIGS. 10 and 11 but actually present - remains approximately constant regardless of the difference between the thermal expansion of said cap 226, 232 and that of the mechanically welded assembly 289 formed by the peripheral sealing ring 220, the lower radial connecting disc 224 , upper radial link disc 225 and piston center pin 210. [139] In addition, said configuration makes it possible to limit the volumetric ratio variation of the thermal engine 202 as a function of its temperature, particularly during the cold start phases of said engine 202.

[140] Note that advantageously and as a variant not shown, the circular peripheral contact edge 252 could advantageously have a spherical contact with the concave conical surface of the cap 251 .

[141] In Figures 2 to 9, it has been shown that the piston fixing means 231 can consist of a double-acting piston axial screw 219 which firstly comprises a piston screw body 255 which is housed in a piston screw tunnel 256 which passes right through the central piston pin 210 in the direction of its length, said screw 219 comprising on the one hand, a piston screw head 253 which bears at the end of the upper piston rod 212 which opens into the piston cooling and lubrication chamber 217, and on the other hand, a piston screw thread 254 which is screwed into the power transmission means 205.

[142] According to an alternative embodiment of the multi-temperature double-acting piston 201 according to the invention, a screw-nut assembly can replace the piston screw head 253 which can moreover be replaced by any other type of fixing which will appear from obvious to those skilled in the art.

[143] As clearly seen in Figures 8 and 9, the piston screw tunnel 256 can advantageously form at least part of the lubrication-cooling gallery 227, the lubricant-cooling fluid 257 being able to circulate between the screw body piston 255 and the internal wall of said tunnel 256, the latter forming with said body 255 a first section which goes from the piston cooling and lubrication chamber 217 to the piston internal volume 228, and a second section which goes from said volume 228 inside the transmission case 206, the piston screw body 255 being able to include screw sealing bulges 258 to separate the piston screw tunnel 256 into sections, said bulges 258 being able for these purposes to have a sealing gasket bulge sealing 259.

[144] As clearly illustrated in Figure 4, the guide means 230 may consist of a barrel skirt 260 which is arranged on the periphery external of the peripheral sealing ring 220 and which rests on the cold cylinder 204, said skirt 260 having a convergent shape which promotes the establishment of a hydrodynamic lubrication regime between itself and the cold cylinder 204 with which she cooperates.

[145] It is obvious in Figures 10 and 11 that the barrel skirt 260 can advantageously be positioned between two compression rings 222 and adjoin an oil scraper ring 278.

[146] Figure 8 illustrates that the lubrication-cooling gallery 227 can open into the internal volume of piston 228 via a small axial play left between on the one hand, a fluid distribution disc 261 which is housed in said volume 228 and on the other hand, the upper radial connection disk 225, said distribution disk 261 being approximately parallel to said radial connection disk 225 and forming on the one hand, a seal with the central piston pin 210, and ending on the other part, radially in the vicinity of the inner wall of the peripheral sealing ring 220, the cooling-lubricating fluid 257 coming from the piston cooling and lubrication chamber 217 being able to exit at the level of said vicinity, for example via weirs distribution 290, orifices or slots of any kind whatsoever arranged on the periphery of the fluid distribution disk 261 .

[147] As clearly illustrated in Figure 9, according to a particular variant of the multi-temperature double-acting piston 201 according to the invention, the central piston pin 210 may comprise, inside the internal volume of the piston 228 and in the vicinity of the lower radial connection disc 224, a fluid recirculation flange 262 which, when the central piston pin 210 moves in the direction of the lower cylinder head 213, rejects radially and in the direction of the internal wall of the peripheral ring of sealing 220 the lubricating-cooling fluid 257 which has accumulated in said volume 228 and on the surface of said disc 224, said flange 262 possibly comprising flange channels 263 which form radial jets of lubricating-cooling fluid 257 which are uniformly distributed over three hundred and sixty degrees.

[148] Particularly in Figure 8, it is noted that the lower radial connecting disc 224 can advantageously have the shape of a hollow 294 at the level of its connection with the central piston pin 210, said form 294 constituting an overflow reservoir 264 which can store lubricating-cooling fluid 257, while at least one overflow orifice 265 which communicates with the inside the transmission casing 206 via the lubrication-cooling gallery 227 fixes the maximum level of said tank 264 so that at each acceleration towards the upper cylinder head 214 of the multi-temperature double-acting piston 201 according to the invention, the level of the lubricating-cooling fluid 257 contained in said reservoir 264 does not exceed that of the overflow orifice 265, said excess fluid 257 being expelled inside the transmission housing 206.

[149] In Figure 7, it is noted that a fluid nozzle 266 fed by the source of lubricant-cooling fluid 218 can open into the piston cooling and lubrication chamber 217 to inject therein a jet of fluid 267 which is shown in figures 8 and 9.

[150] Still in Figures 8 and 9, it can be seen that the fluid nozzle 266 can inject a jet of lubricating-cooling fluid 257 into an axial screw reservoir 267 which is arranged axially in the piston screw head 253, said reservoir 267 communicating with the lubrication-cooling gallery 227 via at least one radial tank-gallery connection duct 268.

[151] Figures 8 and 9 also clearly show that a screw check valve 269 can be housed in the axial screw of the double-acting piston 219, said valve 269 allowing the lubricating-cooling fluid 257 to go from axial screw reservoir 267 towards the lubrication-cooling gallery 227, but not the reverse, so that at each acceleration in the direction of the upper cylinder head 214 of the multi-temperature double-acting piston 201 according to the invention, the lubricating fluid- coolant 257 contained in said tank 267 is forced to enter the lubrication-cooling gallery 227 while when said piston 201 accelerates towards the lower cylinder head 213, said fluid 257 contained in said gallery 227 does not return to said tank 267.

[152] As a variant of the multi-temperature double-acting piston 201 according to the invention, it has been shown in FIG. 12 that the piston cooling and lubrication chamber 217 can be connected to an air source 270 or to a any gas source of any kind by an air inlet check valve 271 which allows fluid forcing air 272 to enter said chamber 217 without leaving it while said chamber 217 is connected to an air reservoir 273 by a pressure relief valve 274 which lets fluid forcing air 272 flow from said chamber 217 to said reservoir 273 when the pressure of said air 272 in said chamber 217 reaches a certain value.

[153] According to this particular configuration of the multi-temperature double-acting piston 201 according to the invention, the pressure which supplies the fluid nozzle

266 in lubricating-cooling fluid 257 is advantageously greater than the opening pressure of the pressure relief valve 274.

[154] We also note in Figure 12 that the altitude of the conduit which connects the piston cooling and lubrication chamber 217 to the pressure relief valve 274 can determine the maximum level of the lubricant-coolant fluid

267 in said chamber 217, said pipe acting as an overflow.

[155] As shown in Figure 13, a reflective screen 295 can be interposed between the lower hot cap 226 and the lower radial connecting disc 224 to which part of the peripheral sealing ring 220 can be added. and/or, between the upper hot cap 232 and the upper radial connecting disc 225 to which part of said ring 220 can be added, said reflective screen 295 returning to the lower hot cap 226 and/or to the upper hot cap 232 the heat emitted, in particular in the form of infrared radiation, by said cap 226, 232.

[156] It has also been shown in FIG. 13 that the thermal insulation means 233 may consist of a cellular or fibrous insulating material 296 which occupies all or part of the space between the lower hot cap 226 and the lower radial connection 224 and/or between the upper hot cap 232 and the upper radial connection disc 225.

[157] Figure 13 also illustrates that at least a first radial space left between the pin outer coaxial upper tube 248 and the piston center pin 210, at least a second radial space left between the pin outer coaxial lower tube 243 and the piston center pin 210, and a plurality of radial spaces left between the piston screw body 255 and the inner wall of the piston screw tunnel 256 may form at least part of the lubrication-cooling gallery 227, the lubricating-cooling fluid 257 being able to circulate successively in said spaces to go from the piston cooling and lubrication chamber 217 to the internal volume of piston 228, then said volume 228 inside the transmission casing 206.

[158] According to this particular configuration of the multi-temperature double-acting piston according to the invention, the outer wall of the upper outer coaxial pin tube 248 and the outer wall of the lower outer coaxial pin tube 243 are always maintained at low temperature, this in order to that a film of lubricating oil which coats the outer wall of said tubes 248, 243 is preserved from any coking or spontaneous combustion by excess temperature, including when the heat engine 202 is stopped after having operated at high temperature, and particularly insofar as an electric pump is provided which forces lubricating-cooling fluid 257 to circulate in the lubrication-cooling gallery 227 after said motor 202 has stopped.

[159] It has been shown in Figures 14 and 15 that the lower rod sealing means 280 and/or the upper rod sealing means 281 may consist of a continuous extensible ring 297 which is directly or indirectly integral with the cooled cylinder block 203, and whose inside diameter is substantially smaller than the outside diameter of the lower piston rod 211 or of the upper piston rod 212 that it encloses.

[160] It is noted that in this case, the radial thickness and the axial thickness of the extensible continuous ring 297 are advantageously low to limit the energy losses produced by the friction of said ring 297 on the lower piston rod 211 and /or the upper piston rod 212.

[161] Figure 14 illustrates that the extensible continuous ring 297 can be connected to a ring plate 298 by a ring tube 299 of small radial thickness, said ring 297, said plate 298 and said ring 297 being made in one and the same piece of material.

[162] It is noted that in this case and advantageously, the ring plate 298 can directly or indirectly move radially and in a sealed manner in the cooled cylinder block 203, and comprise at least one radial ring abutment 303 which limits its eccentricity relative to the lower piston rod 211 or relative to the upper piston rod 212.

[163] Another variant illustrated in Figure 15 provides that the extendable continuous ring 297 can be axially clamped between two ring rings 300 by a ring axial compression spring 301 which can cooperate with a tight ring ring 302 , the two ring rings 300 being able to expose to the lower piston rod 211 or to the upper piston rod 212 a radial ring stop 303 which can come into contact with said rod 211, 212.

[164] OPERATION OF THE INVENTION:

[165] The operation of the multi-temperature double-acting piston 201 according to the invention is easily understood from the view of Figures 1 to 15.

[166] Said piston 201 can be applied to any heat engine 202 running a Beau de Rochas, Miller, Atkinson, Diesel cycle, or any other thermodynamic cycle known to those skilled in the art.

[167] In Figures 1 to 15, the multi-temperature double-acting piston 201 according to the invention has been shown and such that it can be implemented in a heat engine 202 executing a regenerative Brayton cycle which is identical to that executed by the thermal transfer-expansion and regeneration engine according to patent No. WO2016120560.

[168] In this particular context, said piston 201 applies only to the expander 279 of said engine 202, also, the other organs of the latter such as one or more compressors, a burner or a regeneration exchanger necessary for the implementation of the regenerative Brayton cycle, are not shown.

[169] The objective of the multi-temperature double-acting piston 201 according to the invention is to minimize the heat losses of the working gas 240 during the expansion phase of said gas 240 operated during the regeneration Brayton cycle, while ensuring that said piston 201 achieves good sealing with cold cylinder 204 by using only conventional piston sealing means 221, in this case compression rings 222 similar to those fitted to combustion engines in-house automotive products large series, said segments 222 cooperating with an oil scraper segment 278.

[170] Meeting this objective implies in particular that the largest possible part of the outer wall surface of the multi-temperature double-acting piston 201 is maintained at high temperature.

[171] Meeting this objective also requires that the multi-temperature double-acting piston 201 according to the invention achieves good sealing with the lower cylinder head 213 and with the upper cylinder head 214, respectively thanks to lower rod sealing means 280 and to upper rod sealing means 281, said means 280, 281 being formed either of metal cup segments 282 known per se, or of a continuous extensible ring 297 which is directly or indirectly integral with the cooled cylinder block 203 as shown in Figures 14 and 15.

[172] For said objective to be fully achieved, the multi-temperature double-acting piston 201 according to the invention is advantageously applied to a heat engine 202 based on the same said objective and which, as such, limits the losses of heat of the working gas 240 by having the greatest possible part of its internal walls brought to high temperature.

[173] This is why in FIGS. 1 to 3 a heat engine 202 has been shown, the regulator 279 of which receives the multi-temperature double-acting piston 201, said regulator 279 comprising a lower cylinder head 213 and an upper cylinder head 214 whose operating temperature is high - of the order of nine hundred and fifty degrees Celsius - said cylinder heads 213, 214 being made of silicon carbide 276, a material which retains its mechanical characteristics up to temperatures of the order of one thousand four hundred degrees Celsius , and which can be used in an oxidizing medium at these high temperatures.

[174] Only the internal surfaces of said regulator 279 which are in contact both with the working gas 240 and with the piston sealing means 221 are maintained at a temperature of only one hundred degrees Celsius, said temperature remaining compatible with a lubricating-cooling fluid 257 such as lubricating and cooling oil 283, and preventing the latter - in this case motor oil known per se - coking, burning, or degrading prematurely.

[175] As seen in Figures 2 and 3, said surfaces are, in addition to the cold cylinder 204 arranged in a cooled cylinder block 203, part of the peripheral sealing ring 220, part of the lower stem of piston 211 and a part of the upper piston rod 212, these members 220, 204, 211, 212 totaling a surface in contact with the working gas 240 much lower than that totaled by the lower cylinder head 213, the upper cylinder head 214, the lower hot cap 226, and upper hot cap 232.

[176] In Figures 2 and 3 have been shown as an example of particular implementation of the multi-temperature double-acting piston 201 according to the invention the power transmission means 205 which are housed in the transmission casing 206 and which are here provided to transform the reciprocating movements of said piston 201 in the cold cylinder 204 into continuous rotational movement of a crankshaft 247.

[177] Still according to this non-limiting embodiment, the transmission casing 206 and the power transmission means 205 are advantageously maintained at a temperature close to one hundred degrees Celsius, compatible with the lubricating and cooling oil 283.

[178] Note in Figures 2 and 3 that the power transmission means 205 are for example made up of a connecting rod 245 which is connected to the lower piston rod 211 via a butt 244, said connecting rod 34 being articulated around a crank 246 arranged on the crankshaft 247, the latter forming a power output shaft 207.

[179] As clearly seen in Figures 2 to 5 and in Figures 8, 9 and 13, the mechanically welded assembly 289 formed by the peripheral sealing ring 220, the lower radial connection disc 224, the upper radial link 225 and the central piston pin 210 are fixed to the stock 244 by a double-acting piston axial screw 219 whose piston screw body 255 is housed in a piston screw tunnel 256 which passes right through leaves the central piston pin 210 in the direction of its length. [180] The piston screw tunnel 256 here forms a lubrication-cooling gallery 227, the lubrication and cooling oil 283 being able in particular to circulate between the piston screw body 255 and the internal wall of said tunnel 256, the latter forming with said body 255 a first lubrication-cooling gallery section 227 which goes from the piston cooling and lubrication chamber 217 to the piston internal volume 228, and a second section of said gallery 227 which goes from said volume 228 to the inside the transmission case 206.

[181] Advantageously, the piston screw body 255 has screw sealing bulges 258 which seal the piston screw tunnel 256 into two sections by means of bulge seals 259.

[182] As clearly shown in Figures 2 to 5 and Figures 8, 9 and 13, the double-acting piston axial screw 219 also includes a piston screw head 253 which bears at the end of the upper rod piston 212 which faces the piston cooling and lubricating chamber 217, and a piston screw thread 254 which is screwed into the stock 244.

[183] It will be assumed here that the working gas 240 is introduced into the expander 279 via an inlet valve 284 at a temperature of one thousand three hundred degrees Celsius, while the operating equilibrium temperature of the lower cylinder head 213 and of the upper cylinder head 214 which surrounds the cooled cylinder block 203 on the one hand, and that of the lower hot cap 226 and of the upper hot cap 232 which cover the multi-temperature double-acting piston 201 on the other hand, is new -one hundred and fifty degrees Celsius.

[184] It is noted that advantageously and as illustrated in Figures 1 and 2 and Figures 6 and 7, the inlet valve 284 and an exhaust valve 285 through which the working gas 240 is expelled from the regulator 279 after having been relaxed therein are autoclaves, and can each be controlled by a regenerative valve hydraulic actuator as described in patent No. 3071896 dated October 11, 2019 and belonging to the applicant.

[185] Differently from the thermal transfer-expansion and regeneration engine according to patent WO2016120560, of which all the internal walls of the expander are maintained at a high temperature of, for example, nine hundred and fifty degrees Celsius, the internal wall of the cold cylinder 204 of the expansion valve 279 of the thermal engine 202 is here maintained by crankcase-cylinder cooling means 286 at the relatively low temperature of one hundred degrees Celsius, this temperature being given only as a of example.

[186] In Figures 2 and 3, it has been shown that the crankcase-cylinder cooling means 286 may consist of a cooling chamber 287 which envelops the outer surface of the cold cylinder 204, a heat transfer liquid 288, in the occurrence of water, circulating in said chamber 287.

[187] Thus and as clearly shown in Figures 2 and 3, practically all the internal walls of the expansion valve 279 of the heat engine 202 remain hot like those of the transfer-expansion and regeneration heat engine according to patent WC2016120560, at except for cold cylinder 204.

[188] The remaining hot surfaces are sufficient to obtain from the regenerative Brayton cycle a significantly higher thermodynamic efficiency in practice than that obtained from the Otto and Diesel cycles.

[189] It is noted, which is clearly shown in Figures 10 and 11, that the peripheral sealing ring 220 has a barrel skirt 260, two compression rings 222 and an oil scraper ring 278, these components 260, 222, 278 also being maintained at a temperature of the order of one hundred degrees Celsius, close to that of the cold cylinder 204 with which they cooperate, this in particular to preserve the integrity of the lubricating and cooling oil 283 which forms a film on the inner wall of said cylinder 204.

[190] It is therefore understood that, unlike the thermal engine with transfer-expansion and regeneration according to patent WO2016120560, the piston sealing means 221 no longer here consist of a fluid cushion sealing device according to patent FR 3032252, but of a segmentation comparable to that of conventional automotive internal combustion engines, said means 221 being cooled and lubricated in the same way.

[191] This similarity allows the multi-temperature double-acting piston 201 according to the invention to benefit from more than a century of know-how in the field of internal combustion engine piston segmentation. [192] The particular configuration of said piston 201 and of the regulator 279 of which said piston 201 is a part is justified in that, under the temperature conditions which have just been described, the heat transferred to the cold cylinder 204 by the working gas 240 forms an energy loss comparable or even lower than that induced on the one hand, by the fluid cushion sealing device subject of patent FR 3032252 due to the compression means necessary for its compressed air supply, and on the other hand, by the regenerative cooling system according to patent No. EP 3585993 because of the additional pressure drops at the exhaust that it generates, and the reintroduction into the thermodynamic cycle of the heat extracted from the internal walls of the expander via a heat exchanger regeneration whose yield is less than one.

[193] For proof of the validity of the multi-temperature double-acting piston 201 according to the invention, it is noted that if all the internal walls of the regulator 279 shown in Figures 2 and 3 - including the lower cylinder head 213, the upper cylinder head 214 , the lower hot cap 226 and the upper hot cap 232 - were maintained at only one hundred degrees Celsius like the internal walls of mass-produced automotive internal combustion engines, the specific average heat output at the surface - for example expressed in kilowatts per square meter - transferred by the working gas 240 to the cold cylinder 204, would be much lower than that transferred by said gas 240 to said cylinder heads 213, 214 and to said caps 226, 232.

[194] Indeed, the surface that the cold cylinder 204 exposes to the working gas 240 is small at the start of expansion of said gas 240, then increases as said gas 240 expands and that in parallel, its temperature drops , unlike the lower yoke 213, the upper yoke 214, the lower hot cap 226 and the upper hot cap 232, whose surface exposed to the working gas 240 remains constant.

[195] Thus, assuming that said cylinder heads 213, 214 and said caps 226, 232 are deliberately maintained at one hundred degrees Celsius during expansion, the specific cooling power at the surface would be much lower at the level of the internal walls of the cold cylinder. 204 than at those of said cylinder heads 213, 214 and of said caps 226, 232. [196] In addition, the multi-temperature double-acting piston 201 being, as its name suggests, double-acting, the surface of the cold cylinder 204 relative to that of said cylinder heads 213, 214 and said caps 226, 232 is greatly reduced compared to what said surface would be if said piston 201 were single-acting.

[197] Indeed, the cold cylinder 204 being common to the lower variable volume chamber 208 and to the upper variable volume chamber 209, its surface is here and according to the embodiment of the multitemperature double-acting piston 201 according to l invention shown in Figures 2 and 3, less than thirty percent of the total internal surface of the regulator 279 which is brought into contact with the working gas 240.

[198] It is also observed that at identical maximum power, the heat engine 202 being equipped with the multi-temperature double-acting piston 201 and executing a regenerative Brayton cycle, the internal surface of its cold cylinder 204 is smaller in absolute terms than the internal surface of the cylinder of an Otto cycle or Diesel engine of conventional architecture.

[199] This reduces the relative thermal losses attributable to said cold cylinder 204.

[200] In addition, the maximum temperature reached by the gases in the cylinder of an Otto cycle or conventional diesel engine is of the order of two thousand five hundred degrees Celsius compared to only about one thousand three hundred degrees Celsius. with regard to the heat engine 202 executing a regenerative Brayton cycle shown in FIGS. 1 to 3.

[201] All other things being equal, this lower temperature further reduces the heat losses of the working gas 240 in contact with the cold cylinder 204.

[202] In addition, it will be noted that unlike the lower cylinder head 213, the upper cylinder head 214, the lower hot cap 226 and the upper hot cap 232, the heat engine 202 being equipped with the multi-temperature double-acting piston 201 according to the invention, its cold cylinder 204 is located in a zone of low turbulence of the working gas 240 during the introduction of said gas 240 into the lower variable volume chamber 208 or the upper variable volume chamber 209 via the matching 284 intake, or during the expulsion of said gas 240 from said chambers 208, 209 via their exhaust valve 285.

[203] This low intensity turbulence limits convective forcing and heat transfer by working gas 240 to cold cylinder 204.

[204] It will also be noted that, unlike conventional Otto or Diesel cycle engines, the turbulence of the gases introduced into the regulator 279 does not need to be forced by movements known to those skilled in the art. art under the Anglo-Saxon terms of "tumble", "swirl" or "squish", to promote any combustion whatsoever.

[205] Indeed, insofar as the thermal engine 202 equipped with the multi-temperature double-acting piston 201 according to the invention performs a regenerative Brayton cycle - which is its primary purpose - the combustion or heating of the working gas 240 is carried out by means of a hot source located upstream of the expander 279 and not in said expander 279, said source possibly consisting of a burner, a heat exchanger or even, by way of example, non- limiting, of a solar radiation concentration sensor.

[206] The non-necessity of creating deliberate turbulence to promote combustion therefore further reduces the heat losses of the heat engine 202 equipped with the multi-temperature double-acting piston 201 according to the invention performing a regenerative Brayton cycle compared to those of a conventional Otto or Diesel cycle engine, and this, due to less convective forcing between the working gas 240 and the internal wall of the cold cylinder 204.

[207] This being stated, to benefit from the advantages of the multi-temperature double-acting piston 201 according to the invention, it is understood that said piston 201 involves cooperating hot parts and cold parts distant from each other by only a few millimeters.

[208] To demonstrate how the multi-temperature double-acting piston 201 according to the invention allows this cooperation of hot parts and cold parts very close to each other, we will assume here that the central piston pin 210, the radial connecting disc lower 224, the upper radial connection disc 225, the peripheral sealing ring 220 as well as the lower outer coaxial spindle tube 243 and the upper outer coaxial spindle tube 248 are made of steel with high mechanical characteristics, while the lower hot cap 226 and the upper hot cap 232 are made of silicon carbide 276.

[209] The cooled cylinder block 203 and the cold cylinder 204 are made of cast iron, while the lower cylinder head 213 and the upper cylinder head 214 are also made of silicon carbide 276.

[210] We will also assume here that the inside diameter of the cold cylinder 204 is two hundred and forty millimeters.

[21 1] The close proximity between the cold parts 210, 224, 225, 220 in steel or those in cast iron 203, 204, and the hot parts 226, 232, reveals a double challenge linked to differential expansions and to the limitation of heat transfers from said hot parts 226, 232, to said cold parts 210, 224, 225, 220, 203, 204.

[212] Take for example the case of the lower hot cap 226 of the multi-temperature double-acting piston 201 according to the invention, according to its particular configuration shown in Figures 2 to 4, in Figures 6 to 1 1, and in Figure 13, the operation of the upper hot cap 232 being identical.

[213] Said cap 226 and the mechanically welded assembly 289 formed by the peripheral sealing ring 220, the lower radial connecting disc 224, the upper radial connecting disc 225 and the central piston pin 210 with which said cap 226, are both manufactured at a temperature of the order of twenty degrees Celsius.

[214] However, in operation, the temperature of the welded assembly 289 stabilizes at approximately one hundred degrees Celsius, while that of the lower hot cap 226 stabilizes at nine hundred and fifty degrees Celsius.

[215] Taking into account the expansion coefficients of the constituent materials of the lower hot cap 226 and of the mechanically welded assembly 289, these temperatures lead to hot diameter differences between that of said cap 226 and that of said assembly 289 closely one millimeter.

[216] Similarly, under the effect of temperature, the total axial length of the lower hot dome 226 also increases by around one millimeter, such a variation of said length can only be absorbed with difficulty by the cap pressing means 234 which must also take up the axial forces generated by the inertia of said cap 226 during accelerations of the multi-temperature double-acting piston 201 according to the invention.

[217] In addition, the close proximity between the lower hot cap 226 and the mechanically welded assembly 289 is likely to promote heat transfers from said cap 226 to said assembly 289, said transfers being detrimental to the thermodynamic efficiency of the heat engine 202 with regenerative Brayton cycle.

[218] The multi-temperature double-acting piston 201 according to the invention meets this dual need, on the one hand, to absorb large expansion differences between various parts kept in contact with each other and operating at very different temperatures, and on the other hand, to limit heat exchanges between said parts.

[219] Indeed, as seen for example in Figure 5, said piston 201 comprises on the one hand, an insulating ring 236 of zirconium oxide 238 or quartz - materials known for their good temperature resistance and their very low thermal conductivity - which is interposed between the lower hot cap 226 and the peripheral sealing ring 220 and on the other hand, an insulating ring 236 made of the same material which is interposed between said cap 226 and the central piston pin 210 .

[220] As seen in Figure 6, advantageously, the outer coaxial lower pin tube 243 which forms the cap plating means 234 rests on the insulating ring 236 which is radially close to the central piston pin 210.

[221] We also note in Figure 6 the tube spring 250 which rests on the butt 244 and which consists of a stack of spring washers "Belleville".

[222] It is also noted that to limit the heat losses detrimental to the performance of the regenerative Brayton cycle heat engine 202 which receives the multi-temperature double-acting piston 201 according to the invention, the insulating ring 236 interposed between the hot cap lower 226 and the peripheral sealing ring 220 is held pressed against said cap 226 by via a small surface contact edge 241 which reduces the section left to the passage of heat.

[223] As can be seen in Figures 10 and 11, thanks to the particular configuration of the multi-temperature double-acting piston 201 according to the invention, the thermal expansion of the lower hot cap 226 has little or no influence on the total length of the assembly constituted by said cap 226 with the peripheral sealing ring 220, so that the cap pressing means 234 which press said cap 226 onto said ring 220 are not overstressed by said expansion.

[224] Indeed, it is noted in Figures 10 and 11 that the lower hot cap 226 has a concave conical cap surface 251 through which said cap 226 is held flat by the cap plating means 234 on an edge circular peripheral contact 252 presented by the insulating ring 236 which is secured to the peripheral sealing ring 220, said edge 252 acting as a small surface contact edge 241 .

[225] The angle of the concave cone formed by the concave conical surface of the cap 251 is calculated so that when said surface 251 slides on the circular edge of peripheral contact 252 due to the difference between the thermal expansion of the hot cap lower 226 and that of the mechanically welded assembly 289, the axial distance which separates the point of support of the lower external coaxial spindle tube 243 on said cap 226 of the peripheral sealing ring 220 remains approximately constant all things being equal Moreover.

[226] According to this particular configuration of the multi-temperature double-acting piston 201 according to the invention, the concave conical surface of the cap 251 and the circular peripheral contact edge 252 presented by the insulating ring 236 which is integral with the peripheral ring sealing 220, form the cap centering means 235.

[227] According to said configuration, the axial force to which the lower outer coaxial spindle tube 243 is subjected remains approximately constant regardless of the difference between the thermal expansion of the lower hot cap 226 and that of the mechanically welded assembly 289 , while said cap 226 remains radially always centered with respect to the peripheral sealing ring 220.

[228] Note also that said configuration also makes it possible to limit the volumetric ratio variation of the thermal engine 202 according to its temperature, particularly during the cold start phases of said engine 202.

[229] It will be noted, for example in FIG. 6, that the insulating ring 236 which is interposed between the lower hot cap 226 and the lower outer coaxial spindle tube 243 does not, strictly speaking, have a small surface contact edge. 241 , the radial thickness of said tube 243 constituting in itself said edge 241 .

[230] As clearly shown in Figures 4 and 5 and Figures 8, 11 and 13, a barrel skirt 260 is therefore well arranged on the outer periphery of the peripheral sealing ring 220 so as to rest on the cylinder cold 204, said skirt 260 having a convergent shape which promotes the establishment of a hydrodynamic lubrication regime between itself and said cylinder 204.

[231] In the vicinity of the two axial ends of the peripheral sealing ring 220, we note, particularly clearly in Figures 10 and 11, the two compression rings 222 which form the piston sealing means 221 and which prevent the working gas 240 from passing from the lower variable volume chamber 208 to the upper variable volume chamber 209, and vice versa.

[232] Still in Figures 10 and 11, below the barrel skirt 260, there is the oil scraper segment 278 and the peripheral ring lubrication orifices 229 which open at the rear of said segment 278.

[233] This arrangement allows on the one hand, to bring lubricating and cooling oil 283 to lubricate the barrel skirt 260 and the compression rings 222, and on the other hand, to return any excess of said oil 283 in the internal volume of piston 228.

[234] Figures 8 and 9 show the path of the lubricating and cooling oil 283 through the welded assembly 289. [235] Indeed, said oil 283 coming from a source of lubricant-cooling fluid 218 is here injected into the piston cooling and lubrication chamber 217 by a fluid nozzle 266, the latter projecting a jet of oil lubrication and cooling 283 in an axial screw reservoir 267 which is arranged axially in the piston screw head 253.

[236] The axial screw reservoir 267 makes it possible to store lubricating and cooling oil 283 regardless of the direction of movement of the multi-temperature double-acting piston 201 according to the invention, and to maximize the share of said oil 283 which passes through the internal volume of piston 228 before being expelled into the transmission housing 206.

[237] Indeed, a relatively small part of said oil 283 is used on the one hand, to lubricate the cup segments 282 or the extensible continuous ring 297 which form a seal between the outer coaxial upper spindle tube 248 and the upper cylinder head 214 and on the other hand, to cool said tube 248.

[238] As such, we note in Figure 12 the pressure relief valve 274 which acts as an overflow of the piston cooling and lubrication chamber 217 and which, in cooperation with a non-return valve, allows air intake 271 connected to an air source 270 said valve 271 letting fluid forcing air 272 enter said chamber 217, to slightly pressurize the latter while limiting the level of lubricating and cooling oil 283 that contains said chamber 217.

[239] Indeed, below a certain pressure prevailing in the piston cooling and lubrication chamber 217, the air inlet check valve 271 lets in fluid forcing air 272 in from the air source 270 in said chamber 217, while above a certain said pressure, the pressure relief valve 274 expels fluid forcing air 272 into an air tank 273.

[240] As seen in Figure 12, advantageously, the interior of the transmission casing 206 can form both the air source 270 and the air cover 273.

[241] The slight pressurization of the piston cooling and lubrication chamber 217 by means of a fluid forcing air 272 allows, when the heat engine 202 is running at low speed and the accelerations of the piston at double-acting multi-temperature 201 according to the invention are of low intensity, to force the lubricating and cooling oil 283 to enter the lubrication-cooling gallery 227 which is arranged in the central piston pin 210.

[242] Always for the purpose of maximizing the share of lubricating and cooling oil 283 which passes through the internal volume of piston 228, we note in Figures 7, 8, 9 and 13 the screw check valve 269 which is here positioned at the bottom of the axial screw reservoir 267 so that at each acceleration in the direction of the upper cylinder head 214 of the multi-temperature double-acting piston 201 according to the invention, the lubricating and cooling oil 283 contained in said reservoir 267 is forced to enter the lubrication-cooling gallery 227 via radial ducts connecting tank-gallery 268, whereas when said piston 201 accelerates towards the lower cylinder head 213, said oil 283 contained in said gallery 227 does not return to said tank 267 .

[243] All of these arrangements made at the level of the piston cooling and lubrication chamber 217 and at the level of the piston screw head 253 ensure a circulation of lubricating and cooling oil 283 inside of the mechanically welded assembly 289 to maintain the temperature of the latter at around one hundred degrees Celsius, this while ensuring the barrel skirt 260 and the segments 222, 278 appropriate lubrication.

[244] As seen in Figures 8, 9 and 13, a first section of the lubrication-cooling gallery 227 conveys the lubrication and cooling oil 283 from the piston cooling and lubrication chamber 217 to the internal volume of piston 228, this by first passing through the axial screw reservoir 267, the screw non-return valve 269 and the radial ducts connecting reservoir-gallery 268.

[245] In Figures 8 and 9, it has been shown that the lubricating and cooling oil 283 opens into the internal volume of the piston 228 via a small axial clearance left between a fluid distribution disc 261 and the radial connecting disc upper 225, said distribution disc 261 being mainly parallel to said radial connection disc 225 and forming on the one hand, a seal with the central piston pin 210, and ending on the other hand, radially in the vicinity of the internal wall of the peripheral sealing ring 220, the lubricating and cooling oil 283 coming from the cooling and lubricating chamber of piston 217 able to exit at said vicinity via distribution weirs 290.

[246] The axial proximity between the fluid distribution disc 261 and the upper radial link disc 225 is such that the lubricating and cooling oil 283 is forced to lick the entire internal surface of the link disc upper radial 225 before exiting through the distribution weirs 290.

[247] This particular configuration of the multi-temperature double-acting piston 201 according to the invention makes it possible to maintain the temperature of the upper radial connecting disc 225 close to one hundred degrees Celsius, regardless of the power delivered by the heat engine 202.

[248] It is also noted in Figure 13 that to limit the heat received by the lower radial connection disc 224 and by the upper radial connection disc 225, a reflective screen 295 can advantageously be interposed between the lower hot cap 226 and the lower radial connecting disc 224 and between the upper hot cap 232 and the upper radial connecting disc 225, said reflecting screen 295 returning to the lower hot cap 226 and/or to the upper hot cap 232 the heat emitted, in particular in the form of infrared radiation, said cap 226, 232.

[249] Figure 13 illustrates that in addition to the reflective screen 295, a cellular or fibrous insulating material 296 can occupy all or part of the space between the lower hot cap 226 and the lower radial connecting disc 224 and between the upper hot cap 232 and the upper radial connecting disc 225.

[250] As seen in Figure 8, part of the lubricating and cooling oil 283 leaving the distribution weirs 290 cools the peripheral sealing ring 220 from the inside and supplies the peripheral lubrication orifices of ring 229, so that a little of said oil 283 comes out between the two lips of the oil scraper ring 278, the latter forming, following the back and forth movements operated by the multi-temperature double-acting piston 201 in the cold cylinder 204, a film of lubricating and cooling oil 283 on the surface of said cylinder 204, this while recovering said oil 283 present in excess on said surface.

[251] Note in Figures 8 and 9 that the acceleration forces are used by the multi-temperature double-acting piston 201 according to the invention to force the path of the lubricating and cooling oil 283 so that all the surfaces of the internal volume of piston 228 are uniformly cooled.

[252] As such, we note in Figures 8 and 9 the fluid recirculation collar 262 that comprises the central pin of the piston 210, inside the internal volume of the piston 228 and in the vicinity of the lower radial connecting disc 224 .

[253] At each acceleration in the direction of the lower cylinder head 213 of the multi-temperature double-acting piston 201 according to the invention and as shown in Figure 9, said collar 262 rejects radially and in the direction of the internal wall of the peripheral ring seal 220 of the lubricating and cooling oil 283 which has accumulated in an overflow tank 264 consisting of a recessed shape which the lower radial connecting disc 224 has at the level of its connection with the piston center pin 210.

[254] As shown in Figures 4 to 11, the fluid recirculation flange 262 may advantageously include flange channels 263 which form radial jets of lubricant-coolant fluid 257 so as to ensure that the lubricating and cooling oil 283 is evenly distributed over three hundred and sixty degrees.

[255] Note in Figures 8 and 9 the overflow orifices 265 which emerge from the outer wall of the central piston pin 210 and which communicate with the interior of the transmission casing 206 via the lubrication-cooling gallery 227 .

[256] The axial position of said orifices 265 sets the maximum level of said tank 264 so that at each acceleration towards the upper cylinder head 214 of the multi-temperature double-acting piston 201 according to the invention, the level of lubricating oil and cooling 283 contained in said tank 264 does not exceeds that of said overflow ports 265, said excess oil 283 being expelled inwardly of transmission housing 206.

[257] The possibilities of the multi-temperature double-acting piston 1 according to the invention are not limited to the applications which have just been described and it must also be understood that the preceding description has only been given by way of example and that it in no way limits the field of said invention, which cannot be departed from by replacing the details of execution described by any other equivalent

Claims

Claims [Claim 1] Multi-temperature double-acting piston (201) capable of translating in a cold cylinder (204) arranged in a cooled cylinder block (203) which includes a heat engine (202), said piston (201) being directly or indirectly connected by power transmission means (205) housed in a transmission casing (206) to at least one rotary or reciprocating power output shaft (207), while said piston (201) forms a lower variable volume chamber (208 ) with the cold cylinder (204) and a lower cylinder head (213) which is positioned between said piston (201) and the transmission housing (206), said piston (201) simultaneously forming an upper variable volume chamber (209) with said cylinder (204) and an upper cylinder head (214), said chambers (208, 209) containing a working gas (240), characterized in that it comprises • A central piston pin (210) approximately coaxial with the cold cylinder (204) and a first end of which forms a lower piston rod (211) which passes right through the lower cylinder head (213) via a lower rod orifice ( 215) which cooperates with lower rod sealing means (280) to open into the transmission housing (206) and to be directly or indirectly connected to the power transmission means (205) by piston fixing means ( 231), while the second end of said pin (210) forms an upper piston rod (212) which passes right through the upper cylinder head (214) via an upper rod orifice (216) which cooperates with means of upper rod seal (281) to open into a piston cooling and lubricating chamber (217) connected to a source of lubricating-cooling fluid (218), the latter introducing a lubricating-cooling fluid (257) into said chamber (217); • A peripheral sealing ring (220) whose outer diameter is substantially smaller than the inner diameter of the cold cylinder (204), said ring (220) comprising piston sealing means (221) which are in contact with said cylinder (204) to achieve a seal with the latter; • A lower radial connection disc (224) which radially connects the central piston pin (210) with the peripheral sealing ring (220) on the side of the lower variable volume chamber (208), and a connection disc upper radial (225) which radially connects the central piston pin (210) with the peripheral sealing ring (220) on the side of the upper variable volume chamber (209), the space left between said discs (224, 225), the peripheral sealing ring (220) and the central piston pin (210) forming an internal volume of the piston (228); • A lubrication-cooling gallery (227) arranged mainly axially in the central piston pin (210) and in one or more sections, said gallery (227) communicating on the one hand, the cooling and lubrication chamber of piston (217) with the internal piston volume (228), and on the other hand, said volume (228) with the interior of the transmission casing (206); • At least one peripheral ring lubrication orifice (229) which places the internal volume of the piston (228) in communication with the outer peripheral face of the peripheral sealing ring (220), said orifice (229) emerging axially of said face between at least two piston sealing means (221); • Guide means (230) which bear directly or indirectly on or near the power transmission means (205) and/or the cold cylinder (204) and/or the lower cylinder head (213) and/or the upper cylinder head (214), said means (230) directly or indirectly retaining the peripheral sealing ring (220) centered in the cold cylinder (204); • A lower hot cap (226) interposed between the lower radial connecting disc (224) and the lower variable volume chamber (208) and/or an upper hot cap (232) interposed between the upper radial link disc (225) and the upper variable volume chamber (209); • Cap plating means (234) which directly or indirectly hold the lower hot cap (226) pressed against the peripheral sealing ring (220) and/or against the lower radial connecting disc (224), and/ or which directly or indirectly maintain the upper hot cap (232) pressed against the said ring (220) and/or on the upper radial connecting disc (225), the said means (234) leaving the said caps (226, 232) free to expanding relative to said ring (220) and/or said discs (224, 225); • Cap centering means (235) which locate the lower hot cap (226) and/or the upper hot cap (232) with respect to the peripheral sealing ring (220). [Claim 2] Multi-temperature double-acting piston according to Claim 1, characterized in that the lower hot cap (226) and/or the upper hot cap (232) are wholly or partly made of a material resistant to high temperatures ( 275). [Claim 3] Multi-temperature double-acting piston according to claim 2, characterized in that the high temperature resistant material (275) consists mainly of silicon carbide (276). [Claim 4] Multi-temperature double-acting piston according to Claim 1, characterized in that thermal insulation means (233) and/or cap sealing means (239) are interposed either between the lower hot cap ( 226) and the peripheral sealing ring (220) and/or the lower radial connection disk (224), i.e. between the upper hot cap (232) and said ring (220) and/or the radial connection disk upper (225), or both. [Claim 5] Multi-temperature double-acting piston according to Claim 1, characterized in that thermal insulation means (233) and/or cap sealing means (239) are interposed either between the lower hot cap ( 226) and the central piston pin (210), either between the upper hot cap (232) and said spindle (210), or both. [Claim 6] Multi-temperature double-acting piston according to Claims 4 and 5, characterized in that the thermal insulation means (233) consist of at least one insulating ring (236) made of a material with low thermal conductivity (237). [Claim 7] Multi-temperature double-acting piston according to Claim 6, characterized in that the low thermal conductivity material (237) consists mainly of zirconium oxide (238). [Claim 8] Multi-temperature double-acting piston according to Claim 6, characterized in that the insulating ring (236) is maintained directly or indirectly in contact with the central piston pin (210) and/or the peripheral ring of sealing (220) and/or the lower hot cap (226) and/or the lower radial connection disc (224) and/or the upper hot cap (232) and/or the upper radial connection disc (225) by the between at least one small surface contact edge (241). [Claim 9] Multi-temperature double-acting piston according to Claim 6, characterized in that the insulating ring (236) is held directly or indirectly in contact with the central piston pin (210) and/or the peripheral ring of sealing (220) and/or the lower hot cap (226) and/or the lower radial connection disc (224) and/or the upper hot cap (232) and/or the upper radial connection disc (225) by the between at least one insulating ring seal (242) which is tight to the working gas (240). [Claim 10] Multi-temperature double-acting piston according to Claim 1, characterized in that the cap pressing means (234) which directly or indirectly hold the lower hot cap (226) pressed against the peripheral sealing ring (220 ) and/or on the lower radial connection disc (224), are formed of an outer coaxial lower pin tube (243) which envelops the central piston pin (210), said tube (243) resting on a leaves, on the warm cap lower (226) in the vicinity of said pin (210), and on the other hand, on the power transmission means (205). [Claim 11] Multi-temperature double-acting piston according to Claim 1, characterized in that the cap pressing means (234) which directly or indirectly hold the upper hot cap (232) pressed against the peripheral sealing ring (220 ) and/or on the upper radial connection disc (225), are formed of an outer coaxial upper pin tube (248) which envelops the central piston pin (210), said tube (248) resting on a hand, on the upper hot cap (232) in the vicinity of said pin (210), and on the other hand, on an upper rod stop (249) provided directly or indirectly on the upper piston rod (212) in the vicinity of its end which opens into the piston cooling and lubrication chamber (217). [Claim 12] Multi-temperature double-acting piston according to claims 10 and 11, characterized in that some or all of the ends of the lower outer coaxial spindle tube (243) and/or of the upper outer coaxial spindle tube (248) receive a tube spring (250) by means of which said tubes (243, 248) bear respectively on the lower hot cap (226) and on the power transmission means (205) and/or on the upper hot cap (232 ) and on the upper rod stop (249). [Claim 13] Multi-temperature double-acting piston according to Claim 1, characterized in that the lower hot cap (226) and/or the upper hot cap (232) has a concave conical cap surface (251) via which said cap (226, 232) is held flat by the cap pressing means (234) on a circular peripheral contact edge (252) which is directly or indirectly integral with the peripheral sealing ring (220) and/ or the periphery of the lower radial connecting disc (224) and/or the periphery of the upper radial connecting disc (225), the angle of the concave cone formed by said surface (251) being such that when said surface (251 ) slides on said edge (252) due to the difference between the thermal expansion of said cap (226, 232) and that of the assembly formed by the peripheral sealing ring (220), the lower radial connecting disc (224), the upper radial connecting disc (225) and the central piston pin (210), the axial distance which separates the fulcrum of the cap pressing means (234) on said cap (226, 232) from the peripheral sealing ring (220) remains approximately constant, all other things being equal , while the concave conical surface of the cap (251) and the circular peripheral contact edge (252) form the cap centering means (235). [Claim 14] Multi-temperature double-acting piston according to Claim 1, characterized in that the piston fixing means (231) consist of a double-acting piston axial screw (219) which firstly comprises a body piston screw (255) which is housed in a piston screw tunnel (256) which passes right through the central piston pin (210) in the direction of its length, said screw (219) comprising hand, a piston screw head (253) which rests on the end of the upper piston rod (212) which opens into the piston cooling and lubrication chamber (217), and on the other hand, a piston screw thread (254) which is screwed into the power transmission means (205). [Claim 15] Multi-temperature double-acting piston according to Claim 14, characterized in that the piston screw tunnel (256) forms at least part of the lubrication-cooling gallery (227), the lubricating-cooling fluid (257 ) able to circulate between the piston screw body (255) and the internal wall of said tunnel (256), the latter forming with said body (255) a first section which goes from the piston cooling and lubrication chamber (217) to the internal piston volume (228), and a second section extending from said volume (228) to the interior of the transmission housing (206). [Claim 16] Multi-temperature double-acting piston according to Claim 1, characterized in that the guide means (230) consist of a barrel skirt (260) which is arranged at the periphery external of the peripheral sealing ring (220) and which rests on the cold cylinder (204). [Claim 17] Multi-temperature double-acting piston according to Claim 1, characterized in that the lubrication-cooling gallery (227) opens into the internal volume of the piston (228) via a small axial clearance left between, on the one hand, a fluid distribution disc (261) which is housed in said volume (228) and on the other hand, the upper radial connection disc (225), said distribution disc (261) being approximately parallel to said radial connection disc (225 ) and forming on the one hand, a seal with the central piston pin (210), and ending on the other hand, radially in the vicinity of the inner wall of the peripheral sealing ring (220), the lubricating fluid- coolant (257) from the piston cooling and lubrication chamber (217) being able to exit at said vicinity. [Claim 18] Multi-temperature double-acting piston according to Claim 1, characterized in that the central piston pin (210) comprises, inside the internal volume of the piston (228) and in the vicinity of the lower radial connecting disc ( 224), a fluid recirculation collar (262) which, when the central piston pin (210) moves in the direction of the lower cylinder head (213), rejects radially and in the direction of the internal wall of the peripheral ring of sealing (220) the lubricating-cooling fluid (257) which has accumulated in said volume (228) and on the surface of said disk (224). [Claim 19] Multi-temperature double-acting piston according to Claim 1, characterized in that the lower radial connecting disc (224) has the shape of a hollow (294) at its connection with the central piston pin (210), said form (294) constituting an overflow reservoir (264) which can store lubricant-coolant fluid (257), while at least one overflow port (265) which communicates with the interior of the transmission (206) via the lubrication-cooling gallery (227) sets the maximum level of said tank (264). [Claim 20] Multi-temperature double-acting piston according to claim 1, characterized in that a fluid nozzle (266) fed by the source of lubricating-cooling fluid (218) opens into the piston cooling and lubricating chamber (217) to inject a jet of fluid (267) therein. [Claim 21] Multi-temperature double-acting piston according to Claims 14 and 20, characterized in that the fluid nozzle (266) injects a jet of lubricating-cooling fluid (257) into an axial screw reservoir (267) which is arranged axially in the head of the piston screw (253), said reservoir (267) communicating with the lubrication-cooling gallery (227) via at least one radial duct connecting reservoir-gallery (268). [Claim 22] Multi-temperature double-acting piston according to claim 21, characterized in that a screw check valve (269) is housed in the axial screw of the double-acting piston (219), said valve (269) allowing the lubricating-cooling fluid (257) to go from the axial screw reservoir (267) to the lubricating-cooling gallery (227), but not vice versa. [Claim 23] Multi-temperature double-acting piston according to claim 1, characterized in that the piston cooling and lubrication chamber (217) is connected to an air source (270) by an inlet check valve (271) which lets fluid forcing air (272) into said chamber (217) without letting it out, while said chamber (217) is connected to an air tank (273) by a valve pressure relief valve (274) which allows fluid forcing air (272) to flow from said chamber (217) to said reservoir (273) when the pressure of said air (272) in said chamber (217) reaches a certain value. [Claim 24] Multi-temperature double-acting piston according to Claim 1, characterized in that a reflective screen (295) is interposed between the lower hot cap (226) and the lower radial connecting disc (224) to which can be added part of the peripheral sealing ring (220) and/or, between the upper hot cap (232) and the upper radial connecting disc (225) to which part of said ring (220) can be added [Claim 25] Multi-temperature double-acting piston according to Claim 4, characterized in that the thermal insulation means (233) consist of a cellular or fibrous insulating material (296) which occupies all or part of the space between the lower hot cap (226) and the lower radial connecting disc (224) and/or between the upper hot cap ( 232) and the upper radial connecting disc (225). [Claim 26] A multi-temperature double-acting piston according to claims 10, 11 and 14, characterized in that at least a first radial space left between the outer coaxial pin upper tube (248) and the central piston pin (210) , at least a second radial space left between the pin outer coaxial lower tube (243) and the piston center pin (210), and a plurality of radial spaces left between the piston screw body (255) and the inner wall of the piston screw tunnel (256) form at least part of the lubrication-cooling gallery (227), the lubricating-cooling fluid (257) being able to flow successively in said spaces to go from the piston cooling and lubrication chamber (217) to the piston internal volume (228), then said volume (228) inside the transmission housing (206). [Claim 27] Multi-temperature double-acting piston according to Claim 1, characterized in that the lower rod sealing means (280) and/or the upper rod sealing means (281) consist of a continuous ring expandable (297) which is directly or indirectly integral with the cooled cylinder block (203), and whose inside diameter is substantially smaller than the outside diameter of the lower piston rod (211) or of the upper piston rod (212 ) that it encloses. [Claim 28] Multi-temperature double-acting piston according to Claim 27, characterized in that the continuous extensible ring (297) is connected to a ring plate (298) by a ring tube (299) of small radial thickness , said ring (297), said plate (298) and said ring (297) being made from a single piece of material. [Claim 29] Multi-temperature double-acting piston according to Claim 27, characterized in that the continuous extensible ring (297) is clamped axially between two ring rings (300) by an axial ring compression spring (301) . I