EP2216612B2 - Storage device comprising turbulating means - Google Patents

Description

The present invention relates to the field of air conditioning loops cooperating with a ventilation, heating and / or air conditioning installation of a motor vehicle. It relates to a storage device participating in such a loop, better known under the name of bottle or accumulator. It also relates to an air conditioning loop comprising such a storage device.

A motor vehicle is commonly equipped with a ventilation, heating and / or air conditioning installation to regulate the aerothermal parameters of the air contained inside the passenger compartment of the vehicle. Such an installation cooperates with an air conditioning loop to cool an air flow prior to the delivery of the latter inside the passenger compartment. Said loop comprises a plurality of elements or components inside which circulates successively, that is to say in series, a component, such as a subcritical fluid, HF01234YF in particular with which is mixed a known lubricant for example. under the reference IS0100PAG or IS0200PAG. The index 100 or 200 qualifies the grade and therefore the viscosity of the lubricant and PAG stands for PolyAlkylene Glycol. For example, ISO 100 corresponds to a kinematic viscosity close to 100mm ² / s or cSt at 40 ° C, measured according to the international standard ISO. The component and lubricant mixture forms the refrigerant fluid which circulates in the air conditioning loop. The components are at least a compressor, a condenser, an expansion device, an evaporator and an accumulator or a bottle. The function of the lubricant is mainly to lubricate the internal parts of the compressor.

The refrigerant circulates from the compressor to the condenser, then through a bottle when the loop is fitted with one (instead of an accumulator), then to the expansion device, then through the evaporator, then to an accumulator when the loop is fitted with one (instead of the bottle), to return to the compressor.

The compressor is intended to receive the refrigerant fluid in the gaseous state and to compress it to bring it to high pressure and high temperature. The condenser is able to cool the compressed refrigerant fluid, at relatively constant pressure, by releasing heat to its environment. The expansion device is able to lower the pressure of the refrigerant fluid leaving the condenser by bringing it to the liquid state. The evaporator is itself suitable for passing the refrigerant fluid arriving in the liquid state from the expansion device to the gaseous state, at relatively constant pressure, by taking heat from an air flow. flowing through the evaporator. The vaporized refrigerant fluid is then sucked by the compressor.

The accumulator or the bottle performs a function of storing a circulating charge of refrigerant fluid according to the conditions of use of the air conditioning loop. The accumulator also performs a function of separation between a gaseous phase and a liquid phase of the refrigerant fluid leaving the evaporator.

Such an accumulator is known from the document FR-A-1415421 and document EP-A-1967800 .

In general, the accumulator consists of an enclosure delimiting an internal volume used in part as a zone for accumulating the refrigerant fluid. Thus, the refrigerant in the liquid state accumulates by gravity in the storage or accumulation zone.

In order not to damage the compressor, it is necessary that the percentage of oil in the refrigerant fluid is at least equal to the needs of the compressor, these needs being known as the oil return rate. The oil return rate for a fixed-displacement compressor or for a variable-displacement compressor is generally of the order of 5%.

However, the miscibility of the HFO1234YF component and the 100PAG or 200PAG oil is variable depending on the temperature of the refrigerant. There are situations where the refrigerant fluid reaches a high temperature, in particular 40 ° C. at the condenser outlet, which greatly lowers the level of lubricant-component miscibility to fall below the compressor oil return rate. In other words, there is a risk that the compressor will receive less oil than necessary for its correct operation, which at a minimum will reduce its service life and at a maximum will cause immediate breakage of the latter. One solution to solve this problem is the use of another component such as a fluorinated compound known under the reference R134a, however R134a has a very negative impact on the terrestrial greenhouse effect, which is not the case of component HF01234YF.

The aim of the present invention is therefore to solve the problem of miscibility mentioned above by simple means, the installation of which in the heart of an air conditioning loop does not disturb the thermal performance of said loop.

The subject of the invention is therefore a device for storing a refrigerant fluid capable of circulating in an air conditioning loop having the characteristics of claim 1.

According to a first characteristic of the invention, the means intended to cause turbulence takes the form of a pipe which channels the refrigerant fluid coming from an inlet chamber to the storage zone. This tubing is in the form of a conduit which concentrates the refrigerant fluid in a jet.

According to a second characteristic of the invention, the tubing is directly connected to the inlet tube and takes a semi-cylindrical shape, the free end of said tubing facing the storage zone. The arc formed by the semi-cylindrical shape allows the jet to be directed towards the storage area so as to force the jet of refrigerant fluid to strike the upper layer of the fluid stored in the storage area.

According to another characteristic of the invention, the tubing is separate from the inlet tube, said tubing is carried by a plate which divides the internal volume of the storage device in a sealed manner into an inlet chamber and said storage zone. By distinct is meant the fact that the tubing and the inlet tube are not directly linked to one another.

According to yet another characteristic of the invention, the tubing and the inlet tube are coaxial, the inlet tube passing through an evacuation chamber separated from said storage zone by a plate.

According to yet another characteristic of the invention, the tubing passes through said plate and opens into the storage zone.

The diameter of the tubing is between four and eight millimeters.

The outlet tube communicates with the evacuation chamber and with the plenum chamber. Thus, the refrigerant in the gaseous state is captured in the evacuation chamber and a small amount of refrigerant (component and lubricant) is captured in the plenum chamber.

According to the invention, the device has an element permeable to the refrigerant fluid placed in the internal volume of said device at the border between said storage zone and the plenum chamber.

The permeable element is a grid or a filter.

The invention is also aimed at an air conditioning loop or circuit comprising a storage device comprising any one of the characteristics stated above and in which circulates a refrigerant fluid composed of a mixture between the component and a lubricant, said component being a subcritical fluid known under the reference HF01234YF and the lubricant being an oil known under the reference 100PAG or 200PAG. The use of other lubricants such as POE (Polyol-ester) or a mineral oil is covered by the invention, more particularly in the case where the compressor used by the air conditioning loop is an electric compressor (POE lubricant).

A very first advantage according to the invention lies in maintaining a level of miscibility between a component and a lubricant above the return rate of a compressor to be considered.

Another advantage lies in the possibility of using, as coolant in air conditioning loops, in particular for motor vehicles, a component with a low impact on global warming.

Another not insignificant advantage lies in the fact of mixing this component with a lubricant with proven characteristics and whose cost remains low.

• la figure 1 est un graphique de miscibilité par rapport à la température entre le composé HF01234YF et un lubrifiant,
• la figure 2 est une vue illustrant une boucle de climatisation dans une première variante,
• la figure 3 est une vue schématique d'une boucle de climatisation selon une deuxième variante,
• la figure 4 est une vue schématique d'une première variante de l'invention,
• la figure 5 est une vue similaire à la figure 4 mais illustrant le phénomène,
• la figure 6 est une vue schématique d'un exemple n'appartenant pas à l'invention,
• la figure 7 est une vue schématique d'un exemple n'appartenant pas à l'invention.

Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below by way of indication in relation to the drawings in which:

• the figure 1 is a graph of miscibility versus temperature between the compound HF01234YF and a lubricant,
• the figure 2 is a view illustrating an air conditioning loop in a first variant,
• the figure 3 is a schematic view of an air conditioning loop according to a second variant,
• the figure 4 is a schematic view of a first variant of the invention,
• the figure 5 is a view similar to figure 4 but illustrating the phenomenon,
• the figure 6 is a schematic view of an example not belonging to the invention,
• the figure 7 is a schematic view of an example not belonging to the invention.

The figures serve for the technical understanding of the invention but could of course serve to better define the invention, where appropriate.

The figure 1 illustrates the technical problem. It shows a two-dimensional graph in which the abscissa represents the percentage of lubricant in the refrigerant which evolves from 0% on the left to 50% on the right. The ordinate of this graph represents the temperature of the refrigerant fluid within the loop measured at the inlet of the storage device according to the invention. The curve in black entitled “COMPOUND + LUBRICANT” represents the behavior of a compound and lubricant mixture, for example for the component known by the acronym HF01234YF mixed with an oil or lubricant known under the reference 100PAG. It can be seen that at 30 ° C, the percentage of oil in the refrigerant is 10%, which is greater than the oil return rate value commonly known for a fixed displacement compressor for example, i.e. 5% . It is therefore understood that the refrigerant fluid transports sufficient oil to avoid any damage to the compressor. On the other hand, for operation of the air conditioning loop at high outside temperatures (above 35 ° C) or in traffic jams (slowed down) during which hot air return to the condenser causes an increase in temperature surrounding the latter, the quantity of lubricant present in the refrigerant fluid falls below the oil return rate, which results in deterioration of the internal parts of the compressor and in their breakage.

The figure 2 shows a first variant of an air conditioning loop which incorporates the storage device 1 according to the invention. The loop comprises a compressor 2 which may be of fixed displacement, equipped with an electromagnetic clutch which controls the rotation of the compressor. The latter can also be variable displacement, internal or external control. The compressor, which compresses the refrigerant in the gaseous state and raises its temperature, is connected by a pipe to a condenser 3, the latter having the task of cooling the gas flowing through it by exchange. with a flow of air outside the motor vehicle. This condenser 3 has an output connected by a pipe to the input of the storage device 1. In the case of the figure 2 , this storage device is also called a bottle, in particular a dehydrating bottle when the latter is equipped with a dehydration module.

The storage device 1 is connected by an outlet to an expansion member 4, advantageously a calibrated orifice, the function of which is to lower the pressure of the refrigerant fluid (expansion) and thus to lower its temperature. The expansion member 4 is connected to an evaporator 5 where the refrigerant fluid will exchange and cool an air sent into the cabin of the motor vehicle. The air conditioning loop is closed by return of the refrigerant fluid via a pipe connected between the evaporator 5 and an inlet of the compressor 2.

The figure 3 shows a second variant of the air conditioning loop similar to the first variant illustrated on figure 2 except for the following points. The storage device 1 is here an accumulator placed at the outlet of the evaporator 5 and upstream of the inlet of the compressor 2. The expansion member 4 is a thermostatic expansion valve, the control of which is dependent on the temperature of the compressor. refrigerant at the outlet of the evaporator 5.

The figure 4 illustrates the storage device 1 according to a first variant embodiment. This storage device 1 is delimited vis-à-vis the outside by a peripheral wall 6 which is in the form of a tube of circular section closed at its ends by, on one side an upper wall 7 and the other a lower wall 8. The peripheral wall 6, the upper wall 7 and the lower wall 8 surround an internal volume which is divided into an intake chamber 9, a storage zone 10 and a plenum chamber 11.

The inlet chamber 9 is arranged in the upper part of the internal volume and receives the refrigerant in the liquid state when the latter comes from the condenser, that is to say when the storage device 1 is used as a bottle. A plate 12 divides the internal volume in its upper part so as to separate the intake chamber 9 from the storage zone 10. This plate 12 is mounted in the internal volume in a sealed manner on the internal face of the peripheral wall 6, that is to say without communication between the inlet chamber 9 and the storage zone 10 apart from that intended to create or cause turbulence.

The plate 12 has a means 16 intended to cause turbulence in the storage zone 10 which is materialized by an orifice or hole made through the plate 12 and which forms a pipe 13 to allow the circulation of the refrigerant fluid from the chamber of 'admission 9 to the storage area 10. The term tubing covers the hole made in the thickness of the plate 12 and also covers a pipette 14, the free section of which is placed in the extension of the hole so as to channel the flow of fluid refrigerant, these arrangements being grouped together under the expression “means 16 intended to cause turbulence”. In other words, the tubing 13 is materialized by a hole, a pipette 14 or any means 16 of communication between the inlet chamber 9 and the storage zone 10, the open section of which represents less than one tenth of the section. of the peripheral wall 6 taken in line with the plate 12 and which is liable to cause turbulence in the storage chamber so as to mix the lubricant and the component.

In the case shown in figure 4 , the pipette 14 is a hollow circular tubing with an internal diameter of between four and eight millimeters, this range of values offering good performance for causing mixing between lubricant and component within the storage zone. Said pipette 14 is advantageously welded to the plate 12 so as to make its hollow section correspond with the hole made in said plate 12.

A plenum chamber 11 is provided in the lower part of the storage device 1 and under the storage area 10. This plenum chamber 11 is therefore delimited by the lower wall 8, a part of the peripheral wall 6 and a permeable element 15. refrigerant. The function of the element 15 is to let the refrigerant fluid pass to allow it to leave the device according to the invention while preventing the turbulence present in the storage zone 10 and caused by the means 16 according to the invention from being propagated in plenum chamber 11. In the case of figures 4 and 5 , the element 15 is in the form of a grid secured to the peripheral wall 6. In the case of figures 6 and 7 , element 15 takes the form of a filter.

The storage device according to the first variant comprises a filter 17 which takes place in the inlet chamber 9, above the plate 12. This filter 17 is traversed by the refrigerant in the liquid state.

The device according to the invention also comprises a means for channeling the refrigerant fluid from outside the device to the inlet chamber. This means is an inlet tube 18 which passes through the peripheral wall 6 substantially next to the element 15 and continues by forming a bend at right angles. This inlet tube 18 passes through the plate 12 and the filter 17 to open into the inlet chamber 9 above the filter 17. This arrangement allows the refrigerant to pass through the filter 17 from top to bottom before being injected. in the storage zone 10 by means of the means 16 for causing turbulence.

The storage device 1 also comprises a means for discharging the refrigerant fluid. This means takes for example the form of an outlet tube 19 which passes through the peripheral wall 6 in line with the plenum chamber to put the latter in communication with the rest of the air conditioning loop.

The figure 5 illustrates the operation of the storage device 1 according to the invention. Refrigerant arrives through the inlet tube 18 and flows in the liquid state into the inlet chamber 9. This refrigerant, comprising a component and a lubricant, passes through the filter 17 and accumulates on the plate 12. The fluid refrigerant then passes through the means 16 to be injected or projected into the storage zone 10. The latter is filled with the refrigerant fluid in the liquid state as symbolized by the lines referenced 20.

In the absence of means 16 intended to cause turbulence, the lubricant and the component will separate to form two distinct layers, the lubricant supernatant above the component. The means 16, and in particular the pipette 14, causes a restriction which will increase the speed and the pressure of the refrigerant fluid so as to form a jet symbolized by the arrows referenced 21. This will cause mixing between the lubricant and the component thanks to circulation (arrows 22) in the storage zone 10 and the creation of bubbles 23 in the heart of the mixture. It follows that the stored refrigerant fluid is permanently disturbed which prevents the separation between component and lubricant.

The permeable element 15 blocks this agitation so as to prevent the penetration of bubbles 23 into the plenum chamber 11 and to ensure that only the liquid state of the refrigerant fluid is sent to the outlet tube 19 and then to the control member. relaxation.

The figure 6 illustrates an example of the storage device 1 not belonging to the invention. It is still a bottle version but whose constitution is simplified. Indeed, there is no plate 12 or grid between the storage zone 10 and the plenum chamber 11. The element 15 permeable to the refrigerant fluid here takes the form of the filter 17. The invention therefore requires benefit the positioning of the filter 17 in the internal volume of the storage device, at the border of the storage area 10 and the plenum chamber 11, to give it an additional function, i.e. to prevent the passage of turbulence and / or bubbles in the plenum chamber 11.

The inlet tube 18 ends with the means 16 intended to cause turbulence. In practice, the pipe 13 has a semicircular or arc shape and is connected or connected directly to the end 24 of the inlet tube 18. This arc formed by the pipe 13 makes it possible to direct the flow of refrigerant fluid. to the storage zone 10 so as to perform the mixing or disturbance function according to the invention. It is therefore understood that the free end 25 of the tubing 13 faces the storage zone so as to force the refrigerant fluid so that it strikes the surface of the stored refrigerant fluid, and thus to avoid a separation between component and lubricant.

The filter 17 is then passed through by the refrigerant before it ends up in the plenum chamber 11 to exit the device via the outlet tube 19.

The figure 7 shows an example not belonging to the invention suitable for use with the air conditioning loop of the figure 3 .

The storage device 1 is here an accumulator placed on the air conditioning loop between the evaporator outlet and the compressor inlet. The internal volume of the device is distributed starting from the top of the diagram between an evacuation chamber 26, the storage zone 10 and the plenum chamber 11.

The discharge chamber 26 is separated from the storage zone 10 by a plate 27 through which the inlet tube 18 passes. The inlet tube 18 passes through the upper wall 7 then the discharge chamber 26 to be secured by welding or brazing on the plate 27. A space is provided between the peripheral edge of the plate 27 and the internal face of the peripheral wall. 6 so as to allow the refrigerant fluid in the gaseous state to rise in the discharge chamber 26 while preventing the presence of the refrigerant in the liquid state in the storage zone 10.

The inlet tube 18 ends with the pipe 13, these two elements being advantageously co-axial. The pipe 13 causes a jet of refrigerant fluid (in the two-phase or gaseous state) which causes turbulence in the refrigerant fluid stored in the liquid state. This is accompanied by mixing between the component and the lubricant. This mixture is found in the stilling chamber 11 where its behavior stabilizes thanks to the presence of the permeable element, in this case the filter 17.

The outlet tube 19 has a general “U” shape and originates in the discharge chamber 26 where its free end captures the refrigerant fluid in the gaseous state. The outlet tube 19 passes through the plate 27, the storage zone 10 and the filter 17 so as to bathe in the plenum chamber 11. A hole 28 is made in the outlet tube 19 so as to capture a controlled portion of liquid. refrigerant, at this stage a mixture of component and lubricant since the means 16 for causing turbulence has mixed the component and the lubricant. The outlet tube 19 has a 180 ° curve to again cross the filter 17, the storage area 10, the tray 27, the discharge chamber 26 and finally pass through the top wall 7 and connect to the air conditioning loop .

The figure 7 illustrates the phenomenon by the presence of bubbles 23 and of a circulation 22 in the storage zone 10 and the absence of these same bubbles and circulation in the plenum chamber 11.

The invention also covers an air conditioning loop in which the refrigerant fluid circulates, the latter consisting for example of the chemical compound HF01234YF mixed with a lubricant or oil known under the reference 100PAG or 200PAG. Said air conditioning loop comprises within the circuit a storage device as detailed above.

Claims (10)

1. A device (1) for storage of a cooling fluid that can circulate in an air conditioning loop, said device comprising at least one inlet tube (18), an outlet tube (19) and a storage area (10) for the cooling fluid, the cooling fluid being formed of a mixture of a component and a lubricant, characterized in that it comprises mixing means (16) for causing turbulence in the storage area (10) so as to prevent layered stratification of the cooling fluid, a tranquilizing chamber (11) communicating with the outlet tube (19) and an element (15) permeable to the cooling fluid placed in the internal volume of said device at the boundary between said storage area (10) and the tranquilizing chamber (11), wherein the means (16) for causing turbulence take the form of a pipe (13, 14) which channels the cooling fluid from an inlet chamber (9) to the storage area (10).
2. Device according to claim 1, wherein the pipe (13, 14) is directly connected to the inlet tube (18) and assumes a semi-cylindrical shape, the free end (25) of said pipe facing the storage area (10).
3. Device according to claim 1, wherein the pipe (13, 14) is separate from the inlet tube, said pipe is supported by a plate (12) which divides the internal volume of the storage device in sealed manner into said inlet chamber (9) and said storage area (10).
4. Device according to claim 1, wherein the pipe (13, 14) and the inlet tube (18) are coaxial, the inlet tube (18) passing through a discharge chamber (26) separated from said storage area (10) by a plate (27).
5. Device according to claim 4, wherein the pipe (13, 14) passes through said plate (27) and opens into the storage area (10).
6. Device according to any one of the preceding claims, wherein the element (15) permeable to the cooling fluid is a grid.
7. Device according to any one of the preceding claims, wherein the permeable element is a filter (17).
8. Device according to any one of claims 1 to 5, wherein the diameter of the pipe (13, 14) is between four and eight millimetres.
9. Air conditioning loop comprising a storage device according to any one of claims 1 to 8 and a cooling fluid composed of a mixture between a component and a lubricant.
10. Air conditioning loop according to claim 9, wherein the lubricant is a 100PAG or 200PAG oil and the component is a chemical compound HF01234YF.

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