FR2478763A1 - HYDRAULIC ENERGY DISSIPATOR - Google Patents

Abstract

HYDRAULIC DISSIPATOR OF THE ENERGY OF A MOVING MASS, IN WHICH A PISTON LINKS TO THE MOVING MASS FORCES A LIQUID TO PASS FROM ONE WORKING CHAMBER TO ANOTHER THROUGH A STRANGLE PASSAGE WHERE IT IS LAMINATED, WITH TRANSFORMATION D 'MECHANICAL ENERGY IN HEAT. THE DEVICE IS ENTIRELY FILLED WITH LIQUID, AND INCLUDES AN AUXILIARY CHAMBER 11 WITH ELASTIC WALLS KEEPING IT UNDER PRESSURE; THE AUXILIARY CHAMBER COMMUNICATES WITH AT LEAST ONE WORKING CHAMBER 10-12 BY A TARED VALVE SYSTEM ALLOWING FREE PASSAGE FROM THE AUXILIARY CHAMBER TO THE WORK CHAMBER AND THE REVERSE PASSAGE ONLY UNDER THE EFFECT OF A STRONG PRESSURE GENERATED IN THE WORK ROOM. THE INVENTION APPLIES TO LOW AMPLITUDE OSCILLATION DAMBERS, AND IN PARTICULAR TO RAILWAY ROLLING STOCK.

Description

4. 2478763

  The subject of the present invention is a hydraulic dissipator

  energy supply able to function instantly at the first request.

  quotation, even after a fixed period of unlimited duration, on

  races even very reduced, and that in all positions.

  Such devices can find applications in various fields, in particular in building safety devices, industrial installations, port, railway, in shock buffers, structures exposed to exceptional or unexpected movements,

  as well as in dampers of movements of oscillations and vibra-

  small amplitudes, such as rolling stock on rails. It is known that known damping devices,

  which dissipate mechanical energy into heat by rolling oil

  born by a piston through strangled passages, do not meet in

  same time all the necessary characteristics; mistreated their specialist

  extreme use, they often still remain effective and

insufficient reliability.

  Their main drawbacks generally result from the

  simultaneous presence of oil and ambient air in the various chambers

  working hours, which causes, at standstill or at too low ampli-

  studies of the movements, a defusing of the device by the lowering of the oil level, generator of the phenomenon of cavitation. In addition, the continuous agitation of the apparatus causes abundant formation of an emulsion which in the long run alters the quality of the oil. Finally, the presence of air or other gases normally dissolved in the oil at atmospheric pressure also causes their release during the suction of the piston,

  the phenomenon of cavitation which prevents the damping of small movements.

  Operation in horizontal position or close to the horizontal is completely impossible without the addition of an additional oil tank

at sufficiently high level.

  The present invention makes it possible to avoid these disadvantages, and applies to a hydraulic dissipator of the energy of a mass in motion, of the type constituted by a cylinder containing a liquid and separated into two working chambers by a piston connected to the mass in motion, where the movement of the piston generates, depending on the direction of the movement, a pressure

2 2478763

  in one of the two working chambers, thereby forcing some of the liquid to pass into the other chamber through strangulated passages

  where it is laminated with transformation of mechanical energy into heat.

  According to the invention, the device is completely filled with liquid, and at least one of the working chambers communicates with an auxiliary chamber integrated into the apparatus, also completely filled with liquid, and at least one elastic wall maintaining a minimum pressure. in the auxiliary room, communication between the room

  auxiliary and the working chamber or chambers being

  a calibrated check valve leaving a free passage of the intermediate chamber to the working chamber and allowing the reverse passage only under the effect of a higher pressure generated

  by the piston in the working chamber.

  According to a particular embodiment of the invention, the auxiliary chamber is formed in the thickness of the piston which is then in two parts each delimiting one of the working chambers and

  enclosing the auxiliary chamber, each of the two piston portions

  carrying at least one valve allowing the free passage of the liquid alone

  of the auxiliary chamber to the working chamber concerned, and at least one throttled passage with a calibrated valve allowing the passage with laminate from the working chamber to the auxiliary chamber, and

  from there to the other working room.

  According to another particular embodiment of the invention,

  the auxiliary chamber is an outer annular chamber

  - 25 ment the working cylinder, and communicates with one of the chambers of

  working by the valve system arranged on the fixed bottom thereof.

  The invention will be better understood by reference to the description

  following three particular embodiments, given as

  example and shown in the accompanying drawings.

  FIG. 1 is an axial section of a heat sink in horizontal position, provided with a piston in two parts, with a device for compensating for changes in the thermal volume of the volume.

liquid.

  FIG. 2 shows a variant, two-part piston plow, with a device which also compensates the variation

  the volume of liquid due to the movements of the piston ring.

  Fig. 3 shows a piston variant in one

  parts and external auxiliary chamber.

  3 24P7v 3 According to Figure 1, the energy sink consists of a cylinder 1, closed at one of its ends sealingly by a bottom 2, with a tubular nozzle 3, and a fastener 4. A rod 5 carrying a piston in two parts 7 and 8, is extended by another s-9-th of the same diameter. Between the two half-pistons 7 and 8, which share the space in three chambers 10 - 11 and 12, there is a flexible and flexible O-ring 13, of rubber for example, clamped on a sleeve 14, and filled with air or other gas under pressure. This pressure can be supplied from the outside, by means of an appropriate connection via the channel 15, by loosening the needle screw 16; this pressure can also be created during assembly, by screwing the bottom 17 which, provided with the seals 18 and 19, expels a part of the liquid in the chamber 11, reducing the volume of the casing 13 and thus compressing the air it contains. One or more valves 20, loaded by springs 21, open passages constricted to the liquid contained in the chamber 10 when the rod 5 is pulled to the left along the arrow fl. One or

  several valves 22, held by very weak springs 23, close

  during this movement, open easily when the movement reverses to let free passage to the liquid. The half-piston 8 is lined with

  valves and similar valves 24 and 25, suitably adjusted.

  The operation of this sink is as follows. When a force is applied to the fastener 6 in the direction of extension according to the arrow fl, the liquid of the chamber 10 can escape only to the chamber 11, by pushing the valve 20 against its spring 21, which opens up a restricted passage according to the calibration of the spring 21. It is this calibration which determines, by the pressure loss that it causes, the pressure

  in the chamber 10, that is, the reaction or resistance of the dissipation

  according to the race and the speed of the movement.

  From the chamber 11 the liquid then passes freely into the chamber 12, through the valve 25, the two chambers being then at the

  same reduced pressure which is that of rest. In the opposite direction, in

  pressure according to the arrow f2, it is the liquid contained in the chamber 12 which is laminated through the valve 24 of the half-piston 8, to the chamber 11 first and then, without resistance through the valve 22, to the chamber 10. Thus the auxiliary chamber 11 between the chambers and 12, is still at the low initial pressure, without undergoing the strong pressures generated by the working faces of the two half-pistons

  7 and 8 limiting the two working chambers 10 and 12. The envelope

  that 13 filled with air under a low pressure but greater than the pressure

4 2478763

  therefore suffers only small variations due to the

  calorific expansion of the liquid, as a result of its own heating

  by the work and under the effect of the variation of the ambient temperature. The casing 13 constitutes an elastic wall for the auxiliary chamber 11, which makes it possible to permanently maintain the chamber 11 full of liquid under slight pressure, and thereby also the chambers

  10 and 12. As a result, the dissipator can function effectively

  at all times, in all positions even at the smallest displacements and without risk of cavitation or defusing and that whatever the quantity and the quality of the gases dissolved at the origin in the liquid. The heatsink of Figure 2 also consists of a cylinder

  25 tightly closed at its ends by a bottom 27 and a counter

  piston 28, in which slides a tife hollow 29. The rod carries a

  two-piece piston 30 and 31, which divide the cylinder 26 into two chambers

  working rollers 32 and 34 and an intermediate auxiliary chamber 33.

  In the chamber 33 is a hollow ring 35, of elastic material, such as rubber for example, filled with air or other * -az under low pressure. A pin 36, integral with the bottom 27, slides sealingly in the hollow rod 29. The half-pistons 30 and 31 are provided respectively with valves 37, 38 and valves 39 - 40 similar

  and performing the same functions as those in Figure 1.

  The operation of this sink is similar to that of

  the first variant, but the ring 35 has an additional effect here.

  Indeed, when the apparatus is compressed according to the arrow f3, the liquid expelled from the chamber 34 can not pass entirely into the chamber 32 because it only increases by a smaller volume because

  the difference in diameter of rods 29 and 36.

  The excess volume of liquid must be able to find its place in the auxiliary chamber 33, compressing the hollow ring 35

  which takes the form 351 with increasing its internal pressure.

  In the case of a pull on the rod 29, in the direction of the arrow f4, it is the opposite that occurs. The hollow ring 35 inflates under the effect of its internal pressure and flushes the complementary liquid from the chamber 33, through the valve 40, to the chamber 34, the

  volume increases faster than decreases that of room 32.

  In this variant the hollow ring 35 not only makes it possible to compensate for variations in the volume of liquid due to variations in internal and ambient temperatures, but also those due to the movements

  of the stem. Thus work rooms 32 and 34 are still

  naked full and ready to work in all cases and all positions. Pin 36 which serves only to reduce the volume of liquid to be compensated, could be suppressed in certain cases, for example if the movements are of low amplitude, or if the efforts to be damped are

  weak and reduce the diameter of the rod 29.

  The dissipator represented by FIG. 3 comprises a cylinder 41, in which a single piston 42, fixed on a rod 43, moves and which divides the inside of the cylinder 41 into two working chambers 44 and 45. An outer tube 46 of larger diameter, forms with the cylinder 41 an annular space. An elastic envelope, for example of rubber, is fixed in a sealed manner, by its upper edge 48 on the cylinder 41,

  and by its lower edge 49 to the tube 46, forming two annular chambers

  50 and 51. The bottom 52 which closes both the tube 46 and the cylinder 41, communicates the working chamber 44 with the auxiliary chamber 51 through a high-strength valve 53 and, in the opposite direction, through valves 54 consisting of a washer held by a very

  weak spring. A counter-piston 55 sealingly closes the chamber 45.

  It is provided with a screw 56 which can be used for air evacuation and liquid filling during assembly. The piston 42 comprises, on each

  two or more faces, one or more valves 57 and 58, loaded suitably with

  by the tried-and-tested springs, which

  cedeentes, the respective resistances of the dissipator in extension and in compression. The elastic envelope 47 is preformed so as to tend to give the auxiliary chamber 51 a minimum volume as shown in phantom in the lower part of the figure, which would correspond to

  at the maximum high position of the piston 42. In case of deformation of the

  veloppe, its elasticity will tend to make him return to his original form.

  If necessary, to increase its elasticity, an armament

by metal springs.

  During a compressive force, the piston 42 descends and forces a portion of the liquid from the chamber 44 to the chamber 45, with laminaSe at the passage of the valve 58 and the throttled orifice that it discovers. But the volume driven from the chamber 44 is greater than the increase in volume of the chamber 45 because of the penetration of the rod 45, so that a portion of the liquid must pass into the chamber 51, forcing the opening valve 53; the elastic envelope 47 is distended and takes the form 47 '. The pressure generated by the elasticity of the envelope 47, which is exerted on the equivalent of the section of the rod 43, naturally adds its resistance to those given by the valves 58 and 53. In the opposite direction, an effort traction on the head 43 produces a compression of the liquid in the chamber 45 and a passage of liquid in the flesh 44 with rolling through the constricted opening offered by the valve 57. To compensate for the withdrawal of the rod 43, a complementary quantity of liquid passes from the chamber 51 to the chamber 44 by the valve 54. This complementary liquid is not sucked up, but pushed by the contraction of the elastic envelope 47, hence a permanent filling

  two working chambers 44 and 45 without depression or cavitation.

  The heatsink is then able to function effectively at any time and in any position. It is also obvious

  such a heat sink can work also for very small displacements

  ments and that after very long periods of immobilisation, without

  require any boot.

  Of course, the invention is not strictly limited to the embodiments which have been described by way of example, but it also covers embodiments which differ only in terms of features, alternative embodiments or use of equivalent means. It would thus be possible, in place of the rubber casings 13, 35 or 47, to constitute an elastic wall of the chambers

  auxiliaries 11, 33 or 51 by means of sealed metal bellows.

  It would also be possible, in the version of FIG. 3, to use as an auxiliary chamber the entire annular space between the tubes 41 and 46, and by disposing in this annular space one or more

  hollow rings of the kind shown in 35 in FIG.

  In all these variants the auxiliary chamber is always low pressure, and isolated by a valve or a throttling of the high pressures generated in the working chambers during an impact applied to the device. But the permanent pressure in the auxiliary chamber,

  maintained by its elastic wall, ensures the permanent filling

  under slight pressure of the working chambers even in the state of rest the oil is thus constantly isolated from the air and the release of gases

  dissolved is rendered virtually impossible.

E

Claims (6)

  1. Hydraulic heatsink of the energy of a mass in motion, of the type consisting of a cylinder containing a liquid and separated into two working chambers by a piston connected to the mass in motiono the movement of the piston generates, according to the direction of the movement, a pressure in one of the two working chambers, thereby forcing a portion of the liquid to pass into the other chamber through constricted passages where it is laminated with transformation of mechanical energy into heat, characterized in that the device is completely filled with liquid and in that at least one of the working chambers 10-12 communicates with an auxiliary chamber 11 integrated in the apparatus, also completely filled with liquid, and at least one elastic wall 13   maintaining a minimum pressure in the auxiliary chamber, communicating   cation between the auxiliary chamber 11 and the working chamber or chambers 12 being formed by means of a calibrated valve system leaving a free passage of the intermediate chamber to the working chamber, and allowing the reverse passage only under the effect of   higher pressure generated by the piston in the working chamber.   2. Hydraulic heatsink according to claim 1, characterized by   the fact that the elastic walls of the auxiliary chamber are con-   stowed by a flexible envelope 13-35, sealed, inflated with a compressible gas at a pressure at least equal to the minimum pressure at keep in the liquid.   3. Hydraulic heatsink according to claim 1, characterized by   the fact that the elastic walls of the auxiliary chamber are   killed by a waterproof metal bellows.   Hydraulic heatsink according to claim 1, characterized by   the fact that the elastic walls of the auxiliary chamber are con-   formed by a preformed waterproof elastic membrane 47.   5. Hydraulic heatsink according to any one of the claims   preceding, characterized in that the auxiliary chamber is formed   in the very thickness of the piston which is then in two parts 7-8 deli   each one of the working chambers 10-12 and enclosing the auxiliary chamber 11, each of the two piston portions having at least one valve 22 - 25 allowing the free passage of the liquid only from the auxiliary chamber to the working chamber concerned , and   minus a throttled passage with a calibrated damper 20 - 24 allowing the pass- 8 2478763   age with rolling from the working chamber to the auxiliary chamber,   and from there to the other working room.   6. Hydraulic heatsink according to any one of the claims   1 to 4 characterized in that the auxiliary chamber is an annular chafibre 51 surrounding the working cylinder externally, and communicates with one of the working chambers 44 by the system   valves 53-54 disposed on the fixed bottom thereof.