WO2004079194A2

WO2004079194A2 - Hydraulic pump and hydraulic system comprising said pump

Info

Publication number: WO2004079194A2
Application number: PCT/FR2004/000461
Authority: WO
Inventors: Pierre Bignon
Original assignee: Pierre Bignon
Priority date: 2003-02-28
Filing date: 2004-02-27
Publication date: 2004-09-16
Also published as: FR2851796A1; FR2851796B3; WO2004079194A3

Abstract

The invention relates to a hydraulic pump and to a hydraulic system comprising said pump. A pumping piston (21) is displaced in a pumping cylinder (20) by a drive piston (20) moved in a drive cylinder (27) by a liquid (10) having a high thermal dilation coefficient and which is contained in a closed area comprised of a drive chamber (29) of the drive cylinder (27) by means of a tubular arrangement (32) which exchanges heat alternatively with a hot source (4) and a cold source (5) or which permanently exchanges heat with a hot source by repeated replacement therein of the liquid having a high dilation coefficient which is thus heated by the liquid of the same nature which is externally cooled and by means of a hydraulic link duct (31) between the drive chamber (29) and the tubular arrangement (32). The invention can be used to produce hydraulic power from natural heat sources or recovered heat sources or others.

Description

Hydraulic pump and hydraulic installation comprising such a pump

The present invention relates to a hydraulic pump of the type comprising, in at least one copy:

- a pumping cylinder and a pumping piston mounted to slide in the pumping cylinder and delimiting there a sealed pumping chamber,

means of hydraulic connection between a reservoir of hydraulic liquid and the pumping chamber, comprising non-return means passing towards the pumping chamber,

- hydraulic connection means between the pumping chamber and means consuming hydraulic fluid, comprising non-return means passing towards the consuming means, and - motor means for animating the pumping piston with an alternating sliding movement in the pumping cylinder.

It is more particularly interested in the possibility of motorizing such a pump under conditions in which, for reasons of implantation, for example in isolated or desert areas, the use of an electric or thermal motor for this purpose is excluded. or when such a use is voluntarily excluded for the sake of economy or ecology, whatever the nature and the intended use of the hydraulic fluid pumped by means of this pump. In this regard, the term "hydraulic" should be considered here in its broadest sense, the pumped liquid is not limited to water and can be, for example, oil or fuel.

To meet such conditions or such a choice, the present invention provides a pump of the type indicated in the preamble, characterized in that the driving means comprise: a driving cylinder and a driving piston mounted to slide in the driving cylinder and delimiting therein a sealed driving chamber, kinematic connection means between the driving piston and the pumping piston, so that an increase in volume of the driving chamber corresponds to a reduction in volume of the pumping chamber and vice versa,

- a hydraulic connection pipe between the driving chamber and a tubular heat exchange bundle, forming with the pipe and with the driving chamber a closed enclosure, - a liquid with a high coefficient of thermal expansion, enclosed in said closed enclosure and filling that - this, and

- means for placing the liquid with a high coefficient of thermal expansion in a heat exchange relationship alternately:

With a hot source, while it is enclosed in said enclosure and under conditions such that it remains in the liquid state, by placing the tubular bundle in heat exchange relation with said hot source, and

• with a cold source. A person skilled in the art will readily understand that each time an exposure of the liquid with a high thermal coefficient to the cold, whether outside the tube bundle or inside it, follows an exposure of a certain quantity of this liquid, thus initially cold, to heat while it is enclosed in the enclosure constituted by the tubular bundle, placed in heat exchange relation with the hot source, the driving chamber and the connecting pipe hydraulic between them, this quantity of liquid with a high coefficient of thermal expansion expands, that is to say undergoes an increase in volume which can then only be compensated for by a displacement of the driving piston in the direction of an increase in volume of the driving chamber. Since the hydraulic fluid with a high coefficient of thermal expansion remains in the liquid phase, this results in the application, to the working piston, of a pressure very much greater than that which the gaseous phase can exert of a fluid passing alternately in the gaseous phase and in the liquid phase, which opens the way to direct applications of such a pressure of the hydraulic fluid pumped in technical fields requiring it to be brought to particularly high pressures, certain examples of such applications emerge from the following description . Admittedly, one can thus obtain only a comparatively reduced stroke of the driving piston but the gain in pressure, in comparison with the pressure which one can obtain by means of a fluid changing phase, is sufficiently high so that the we can, at the cost of reducing this pressure between the liquid hydraulics with a high coefficient of thermal expansion and the hydraulic fluid pumped, giving a pump according to the invention applications in technical fields in which it is desired rather to favor the flow rate of pumped hydraulic fluid, certain examples of such applications also being apparent from the following from the description.

A person skilled in the art will readily understand that such a pump according to the invention makes it possible to solve the problems associated with the exploitation of thermodynamic solar cold, either by direct linear compression of jack to jack, or by replacing the electric motor generally chosen for drive the compressor of a refrigeration machine by a hydraulic motor, thus constituting the means consuming hydraulic fluid, which in particular makes it possible to use solar energy, as a hot source, to produce cold in an air conditioning installation , whose energy demand is higher when there is a lot of sun, that is to say precisely at times when we can have more solar energy.

However, the power of a hydraulic motor thus supplied by a pump according to the invention can also be used to assist a heat engine by using the thermal energy of the exhaust gases or the coolant of this engine. In such an application, the heat of the exhaust gases or of the coolant of the heat engine is converted into hydraulic pressure by the pump according to the invention, and the hydraulic motor driven by this pressure makes it possible to lighten the load of the engine and allowing it to consume less fuel pollutant or, in the case of a refrigerated vehicle, to ^'operate the compressor thereof. The application on a boat can be interesting because the cold source can then be in the flotation water.

A hydraulic motor powered by a pump according to the invention can also control a generator in the presence of geothermal resources, or in any place of heat production such as the food industry, for example for the production of cold necessary for the preservation of food at the end of production lines, or even near nuclear power plants, which produce a lot of recyclable hot water before being evacuated to rivers.

The hydraulic energy supplied by the pump according to the invention can also be used to directly drive the piston of a compressor in an air conditioning system, or to bring the fuel used to supply an engine to the required pressure. thermal, in particular with common rail.

These application examples are however in no way limiting and, in particular, provision can also be made to use a hydraulic pump according to the invention for carrying out underground pumps in order to supply, for example, irrigation installations, or again to practice cutting parts with pressurized water. In general, as an example of a hot spring, mention may be made of solar radiation, exhaust gases and cooling circuits of heat engines or condensers, industrial discharges, geothermal energy, air having undergone adiabatic heating following a violent compression, electric heating, and, as examples of cold source, one can quote the ambient air, if necessary forced by a ventilator, running water, compressed air having undergone a rapid expansion, the heating circuits of an evaporator, these examples being in no way limiting.

It will be observed that the hot or cold sources necessary to operate the pump according to the invention when it is intended to supply energy to a refrigerating machine or a heat pump can be borrowed in part from these machines, since the condenser and the the above-mentioned evaporator can respectively form an integral part of the refrigerating machine or the heat pump, which makes it possible, in particularly hot or particularly cold countries, to operate such a refrigerating machine or such a heat pump with little or no d non-renewable energy, allowing almost free energy production from air conditioning.

So that the thermal expansion and thermal contraction of alternating high thermal expansion coefficient to allow liquid to develop a power as great as ^possible, it preferably selects such a liquid having a coefficient of thermal expansion of at least 1/1000 per ° C, and for example a liquid chosen from a group comprising anhydrous alcohol and fuel oil. These examples are however in no way limiting as soon as the chosen liquid makes it possible to develop, by its expansion, an energy high enough to be usable, if necessary by coupling in parallel several pumps according to the invention, that is to say by connecting in parallel the corresponding hydraulic connection means, comprising the corresponding return means, respectively between the reservoir and the pumping chambers and between the pumping chambers and the consuming means, it being understood that, moreover, depending on the applications envisaged for the pump, the drive chamber and the drive piston may have a smaller cross-section than that of the pumping chamber and the pumping piston.

In other applications, however, the driving chamber and the driving piston may have a cross section identical to, or even greater than, that of the pumping chamber and the pumping piston. Thus, in applications aimed at the production of high pressures, for example for fuel injection or cutting with water under high pressure, the driving chamber and the driving piston preferably have a cross section greater than that of the pumping and pumping piston.

According to a particularly economical embodiment, provision is preferably made for the driving piston and the pumping piston to be constituted by two stages of the same differential piston and for the driving chamber and the pumping chamber to be constituted by two chambers, mutually aligned and separated from each other by the differential piston, of the same cylinder constituting the engine cylinder and the pumping cylinder. It will be observed that the connection of several pumps according to the invention in parallel, accompanied by a phase shift between the different pumps, allows the hydraulic pressure obtained to be smoothed to a certain extent when this is desired. However, for this purpose, in addition or as a replacement, it is also possible to provide that the consumer means comprise a hydraulic pressure accumulator, interposed between them and the hydraulic connection means between the pumping chamber and them, which makes it possible to supply the means themselves consuming hydraulic energy at a substantially constant pressure despite the reciprocating movement of the or each pumping piston.

The pumping chamber, the corresponding hydraulic connection means, comprising the corresponding non-return means, the reservoir and the consumer means constitute in some applications an open circuit, as is the case when the hydraulic pump according to the invention is used to draw some water. However, in all the applications in which this is possible, and in particular when the pump according to the invention is intended to supply a hydraulic motor, it is preferable for the pumping chamber, the corresponding hydraulic connection means, comprising the anti- corresponding return, the tank and the consuming means, including the possible hydraulic pressure accumulator, constitute a closed circuit in which, thus, fully controls the nature and cleanliness of the hydraulic fluid.

The means for placing the liquid with a high coefficient of thermal expansion in heat exchange relation alternately with a hot source, while it is enclosed in said enclosure and under conditions such that it remains in the liquid state, by placing the tube bundle in heat exchange relationship with said hot source, and with a cold source can be in various forms, from which a person skilled in the art will choose the most suitable depending on the application envisaged for the present invention.

In one embodiment, these means comprise means for placing the tube bundle in heat exchange relation alternately with a hot source and with a cold source.

The hydraulic fluid with a high coefficient of thermal expansion then remains permanently enclosed in the closed enclosure constituted by the driving chamber, the tubular bundle and the connecting pipe between them, in order to undergo an alternation of thermal expansions and thermal contractions or withdrawals. , accompanied by alternating thrusts and pulls applied to the working piston by this liquid. The action of the latter on the driving piston, in the direction of traction, can advantageously be assisted by elastic return means of the driving piston. Various means can be chosen to place the tube bundle in heat exchange relationship alternately with the hot source and with the cold source and, in particular, provide a fixed tubular bundle on which, alternatively, a flow of a coolant, liquid or gaseous, from the cold source and a flow of a heat transfer fluid, liquid or gaseous, from the hot source.

However, the use of such an alternating flow slows down the operating cycle of the pump according to the invention, and the alternating presence of a hot, liquid or gaseous heat transfer fluid and a cold, liquid or gaseous heat transfer fluid, in the same enclosure causes significant energy losses, and it is preferred to make the means for placing the tube bundle in heat exchange relation alternately with the hot source and with the cold source in a form comprising: a divided tank by a horizontal partition, thermally insulating, in a lower chamber and an upper chamber, - means for circulation of a heat transfer fluid, chosen from a group comprising liquids and gases, between the lower chamber and the cold source, means circulation of a heat transfer fluid, chosen from a group comprising liquids and gases, between the upper chamber and the hot source, and

- Means for moving back and forth vertically, inside the tank, the tube bundle, comprising at least one copy of a vertical tube freely passing through the partition through a corresponding orifice, between a high position, in which he bathes in the upper chamber, and a low position, in which it bathes in the lower chamber.

In a particularly simple manner, the means for moving the tubular bundle back and forth vertically comprise a hydraulic cylinder and controlled distributor means for supplying the cylinder with hydraulic liquid, which advantageously comes from the reservoir in the case where the pumping, the corresponding hydraulic connection means, comprising the corresponding non-return means, the reservoir and the consuming means, including the possible hydraulic pressure accumulator, constitute a closed circuit in which the hydraulic fluid in the reservoir retains sufficient pressure to be so used.

Of course, other means could also be used for this purpose without departing from the scope of the present invention.

In another embodiment of the means for placing the liquid with a high coefficient of thermal expansion in heat exchange relation alternately with a hot source and with a cold source, these means comprise means for placing the tubular bundle in permanent relation of heat exchange with the hot source and means for repetitively replacing, in the tubular bundle, liquid with a high coefficient of thermal expansion thus heated by liquid with a high coefficient of thermal expansion previously placed in heat exchange relationship with the cold source. The operation of this embodiment is quite similar to that of the above embodiment, in which the tube bundle is placed in heat exchange relationship alternately with the hot source and with the cold source.

Indeed, it is again while it is enclosed in the enclosure constituted by the tubular bundle, the driving chamber and the pipe which connects them that the liquid with a high coefficient of thermal expansion, previously exposed to cold, undergoes a heating and expands, in a way that can only be compensated by a movement of the driving piston in the direction of an increase in the volume of the driving chamber. Subsequent replacement of the liquid with a high coefficient of thermal expansion thus reheated by similar cooler liquid makes it possible to replace the tube bundle in conditions similar to those of temporary exposure to the cold source.

In a particularly simple manner, the means for repetitively replacing the liquid with a high coefficient of thermal expansion in the tube bundle comprise a circuit of liquid with a high coefficient of thermal expansion outside the tube bundle, comprising means for heat exchange with the cold source, connected in series with the tube bundle and means for, alternatively, fluidly connecting the heat exchange means to one zone of the tube bundle by opening another zone of the latter to a discharge of liquid with a high coefficient of thermal expansion, and close said zones of the tube bundle, these means can be constituted for example by controlled valves opening and closing simultaneously, at least approximately, as a function of the pressure of the liquid with a high coefficient of thermal expansion in said closed enclosure. Said outlet is preferably connected to a reservoir of liquid with a high coefficient of thermal expansion, connected in series with the heat exchange means with the cold source.

This may be the case, in particular, in applications in which the liquid with a high coefficient of thermal expansion consists of the hydraulic liquid to be pumped itself, for example fuel in the application of a pump according to the invention to the supply of a heat engine, in which case a single tank is used to supply the tube bundle, that is to say the driving chamber, and the pumping chamber. The use of a differential piston to constitute on one side the driving piston and on the other the pumping piston is then particularly appropriate, since possible leaks, along this piston, between the driving chamber and the chamber of pumping remain without consequence on the nature of the hydraulic fluid pumped, and can be compensated for each repetitive replacement of the same liquid, as a liquid with high coefficient of thermal expansion, inside the tube bundle.

Insofar as, as it is deduced from the above, a pump according to the invention generally does not only serve to supply energy to the consuming means but can cooperate with them in a more complete manner, the present invention also extends to a installation comprising a hydraulic pump according to the invention, associated with a hydraulic fluid reservoir and with means consuming hydraulic fluid, in particular chosen, by way of nonlimiting example, from a group comprising hydraulic motors and compressors driven hydraulically , in particular as components of air conditioning systems for living quarters or for the interior of a vehicle, or for the refrigerated transport of goods, and devices for injecting or spraying liquid under high pressure, in particular as components for installations for supplying combustion engines with fuel, such as supplies by common rail, often designated by the expression in English-language "common rail", or installations for cutting with water under high pressure.

Other characteristics and advantages of the various aspects of the present invention will emerge from the description below, relating to three nonlimiting examples, as well as from the appended drawings which accompany the present invention.

FIG. 1 schematically illustrates an installation implementing a hydraulic pump according to the invention, comprising three pumping pistons and used for the supply, in hydraulic fluid circulating in closed circuit, of a hydraulic motor such as a gear motor .

It is understood, however, that a pump according to the invention could also include a single pumping piston, or any other desired number of pumping pistons, and have applications other than supplying a hydraulic motor with hydraulic fluid, as indicated above.

Thus, FIG. 2 schematically illustrates an installation implementing a hydraulic pump according to the invention comprising a single pumping piston and used for the supply of hydraulic liquid to the compressor of a cabin air conditioning installation of a combustion engine vehicle , at the pressure and flow required to drive this compressor. Likewise, FIG. 3 schematically illustrates an installation implementing a hydraulic pump according to the invention for supplying fuel, at the required pressure and flow rate, to a common fuel injection rail under high pressure. a heat engine, the coolant or exhaust gases of which are used as heat transfer fluid for passing through the tubular bundles of the heat exchanger of the pump according to the invention.

Reference will first be made to FIG. 1, where the hydraulic pump according to the invention has been designated by 45, which comprises, in the same body not shown or in separate respective bodies also not shown, three cylinders not stepped referenced, each group, aligned along the same longitudinal axis, a driving cylinder 27 and a pumping cylinder 20 which has a greater cross section, and preferably much greater, for example in a ratio of 10 to 1, than that of the driving cylinder 27. In each of these cylinders 27 and 20 is mounted in the longitudinal sliding a transverse piston of respectively corresponding section, namely a driving piston 28 delimiting inside the driving cylinder 27 a driving chamber 29 and a pumping piston 21 delimiting in the pumping cylinder 20 a pumping chamber 22. The two pistons 28 and 21 thus associated are rigidly linked together by means shown diagrammatically at 30, for example due to an embodiment in the form of two stages of the same differential piston separating from one another the chambers 29 and 22, mutually aligned, so that at the longitudinal sliding of the differential piston in one direction corresponds to an increase in volume of one of these chambers and a simultaneous reduction in the volume of the other chamber, and vice versa. Preferably, means are provided for resiliently returning the differential piston to a position corresponding to a minimum volume of the driving chamber 29; these means have been illustrated in FIG. 1 in the form of a helical spring 61 working under compression, housed coaxially with the piston in each pumping chamber 22, respectively. Such longitudinal sliding of the differential piston, grouping the driving piston 28 and the pumping piston 21, are caused in accordance with the present invention by means of a liquid 10 with a high coefficient of thermal expansion, for example at least equal to 1 in 1000 by degree Celsius, such as anhydrous alcohol or fuel oil, filling a closed enclosure of which the motor chamber 29 is a part and which is introduced or extracted therefrom by motor means 26 which are characteristic of the present invention and will be described later, to animate the driving piston 28 and, with it, the pumping piston 21 with a movement alternating longitudinal sliding in the respective cylinder 27, 20, so as to cause, by the alternating variations in volume of the pumping chamber

22 which result therefrom, the pumping of a hydraulic liquid 11 which, depending on the applications, may be of a different nature.

Thus, in the illustrated application in which it is a question of supplying a hydraulic motor 7, the liquid 11 advantageously consists of a hydraulic oil of known type whereas, in other applications, it could be water, as would be the case for example in an application for raising water for irrigation purposes or in an application for cutting water parts, or a fuel in an application for water supply of very high pressure fuel to a common rail thermal engine, these examples being in no way limiting.

In the example illustrated, the hydraulic fluid 11 evolves in a closed circuit comprising: - a reservoir 6 maintained at a pressure higher than atmospheric pressure and for example of the order of 2 bars, which will be considered as low pressure in comparison with the other pressures used, as will emerge from the following description, - a pipe 23 for hydraulic connection between the tank 6 and the pumping chamber 22, this pipe

23 comprising a non-return valve 24 passing towards the pumping chamber 22,

- This pumping chamber 22, - a pipe 25 going from this pumping chamber 22 to the hydraulic motor 7, this pipe 25 comprising a non-return valve 16 passing towards the hydraulic motor 7,

- a hydraulic accumulator 8 which is preferably provided and which is interposed in the line 25 between the non-return valve 16 and the hydraulic motor 7 and is brought to a pressure higher than that of the tank 6 and considered as average in comparison with the other pressures implemented by the device, and for example of the order of 200 bars, - an unreferenced pipe returning the hydraulic motor 7 to the tank 6, comprising a non-return valve 46 passing towards this tank 6 and, between the non-return valve 46 and the tank 6, a pressure limiter 13 set to the low pressure which it is desired to have in the tank 6, namely 2 bars in the digital example chosen.

Another pressure relief valve 12, set to the medium pressure which it is desired to have in the accumulator 8, namely 200 bars in this digital example, is provided in a bypass starting from the pipe 25 between the non-return valve 16 and the pressure accumulator 8 and terminating between the non-return valve 46 and the pressure limiter 13.

Naturally, in an application of the pump according to the invention 45 to an elevation of water for example for irrigation purposes, the reservoir 6 could be constituted for example by the groundwater or by a tarpaulin and the pipe 25 could be '' open freely during use, without pressure accumulator 8 or return to the water table or tarpaulin serving as a reservoir 6. Line 25 could also open freely for use in other applications, such as water cutting and fuel injection.

When, as illustrated, the pump 45 according to the invention comprises several pumping chambers 22, these are connected in parallel, by means of respective non-return valves 16 and 24 and respective branches of the lines 23 and 25 between the reservoir 6 and the pressure accumulator 8 or, in the absence of the latter, the means consuming hydraulic fluid 11, here constituted by the hydraulic motor 7.

On the other hand, it is independently of one another that the drive chambers 29 form part of a respective closed enclosure filled with hydraulic liquid 10 with a high coefficient of thermal expansion, serving as the working fluid, the differential pistons each consisting of a driving piston 28 and a pumping piston 21 which can thus be controlled in synchronism, as illustrated for the two lower differential pistons, or in phase opposition, as illustrated for the two differential pistons superiors, or according to any desired sequencing according to the envisaged application, as a person skilled in the art will readily understand.

The closed enclosure to which each of the motor chambers 29 respectively belongs is further constituted by a respective tubular bundle 32 of heat exchange, an embodiment of which will be detailed below, and by a respective pipe 31 for hydraulic connection between this heat exchanger 32 and the driving chamber 29. In this pipe 31 is interposed a pressure limiter 9 adjusted to a comparatively high pressure, for example of 2000 bars, the liquid with a high coefficient of thermal expansion present in the closed enclosure constituted by the chamber 29, the pipe 31 and the corresponding heat exchanger 32 respectively can be brought to even higher pressures, depending on which the materials of these different components must be chosen. Thus, by way of nonlimiting example, it is possible to choose, for producing the heat exchanger 32, beryllium copper or certain molybdenum alloys, which have both sufficient mechanical strength and good thermal conductivity; the pipe 31, at least partially flexible for reasons which will appear later, must also be made of a material capable of withstanding the pressures brought into play in the liquid 10 with a high coefficient of thermal expansion. According to the preferred embodiment which has been illustrated, each heat exchanger 32 consists of a bundle of vertical tubes, for example with a length of 700 mm for an inside diameter of 2 mm and an outside diameter of 6 mm, by example at the rate of 12 rows of 20 tubes 43 closed at their lower end and communicating with each other, at their upper end, by a manifold into which the pipe 31 opens and which also ensures the mutual mechanical connection of the tubes 43. Each of the bundles heat exchange tubular 32 thus formed is placed inside of a respective tank 33, divided by a horizontal thermally insulating partition 34, pierced with as many orifices 44 as there are tubes 43, so that each tube 43 passes right through the partition 44 by an orifice 44 respectively , under conditions suitable for ensuring as good a seal as possible between the partition 34 and each tube 43.

The partition 34 subdivides the corresponding tank 33 into a lower chamber 35 and into an upper chamber 36 containing a respective heat transfer liquid 41, 42 which may be of the same nature, and for example be water.

The lower chamber 35 or, when several are provided, as is the case in the example illustrated, the different lower chambers 35, in parallel, are connected, by a pipe 37 for the arrival of heat transfer liquid and by a pipe 38 for starting the heat transfer liquid, to a cold source 5 which may be of any of the aforementioned types, or of another type, and which makes it possible to circulate the heat transfer liquid 41, which is comparatively cold, in the chamber lower 35. Similarly, the upper chamber 36 or, when several are provided, each of the upper chambers 36, in parallel, is connected to a hot source 4 by an inlet pipe 39 and a departure pipe 40, which makes it possible to circulate the comparatively hot heat transfer liquid 42 in the or each upper chamber 36. The hot source 4 can be of any of the aforementioned types, or else of a different type. In order to place each tube bundle 32 alternately in heat exchange relation with the cold heat transfer fluid 41 and with the hot heat transfer fluid 42, means are provided for moving each tube bundle 32, here independently of one another, back and forth vertically inside the tank 33 respectively corresponding, between a high position, in which this tubular bundle 32 bathes almost entirely in the hot liquid 42 inside the upper chamber 36, only the lower ends of the tubes 43 still being engaged in the orifices 44 of the partition 34, as c 'is the case of the tubular bundle 32 illustrated on the left of the figure, and a low position, illustrated with regard to the two tubular bundles situated on the right of the figure, in which the tubular bundles 32 are almost entirely immersed in the heat transfer liquid 41 to 1 inside the lower chamber 35, only the collector, suitably thermally insulated, then being placed above the partition 34. The two beams x tubulars 32 illustrated in the right part of the figure, thus placed in contact with the coolant 41 cold, correspond to the driving chambers 29, having their minimum volume, of the two lower cylinders while the tubular bundle 32 located on the left of the figure, immersed in the hot heat transfer liquid 42, corresponds to the motor chamber 29, having its maximum volume, of the upper cylinder.

To move thus back and forth vertically each of the tubular bundles 32 inside the tank 33 respectively corresponding, between the high position and the low position, cylinders 15 are provided, each of which is associated with one, respective, beams tubular 32 and is disposed above the corresponding tray 33.

Each of the jacks 15 is vertical and internally comprises a horizontal piston 52 connected to the collector of the tube bundle 32 respectively corresponding by a vertical rod 50.

Inside each cylinder 15, the corresponding piston 52 separates two chambers 53, 54 each of which is connected, by a respective pipe 48, 49, to a hydraulic distributor 14 making it possible to introduce in a controlled manner, alternately inside of chamber 54 and inside chamber 53 of each jack 15, leaving the other chamber thereof to the exhaust, a hydraulic fluid which may be different from hydraulic fluid 11, in particular when the conditions d application of the pump according to the invention 45 do not allow the fluid 11 to be used to supply the jacks 15, but which, in the example illustrated, is constituted by this fluid 11, brought to the distributor 14, from the reservoir 6 , by a pipe 47 for example connected to one of the pipes 23, between the tank 6 and the corresponding non-return valve 24.

The dispenser 14, the embodiment and control of which falls within the normal abilities of a person skilled in the art, can be programmed to cause in-phase, in-phase opposition or with a determined phase shift back and forth movements. vertical of the different tubular heat exchange bundles 32 inside the tanks 33 to cause thermal expansion and alternating thermal contractions of the liquid 10 with a high coefficient of thermal expansion in the different tubes of each tube bundle 32, depending on whether this tube bundle is immersed in the hot liquid 42 or in the cold liquid 41, which respectively causes the supply of the corresponding chambers 29 with hydraulic liquid 10, that is to say say the increase in the volume of these chambers 29 to the detriment of that of the chambers 22 which expel the hydraulic fluid 11 towards the pressure accumulator 8 and the hydraulic motor 7 then, in return, towards the reservoir 6 in the case of the illustrated application, and a reduction in volume of the corresponding chambers 29 with the increase in the volume of the corresponding chambers 22, which causes the suction of hydraulic fluid 11 from the reservoir 6, the alternation of these suction and backflow causing the desired pumping effect.

The changes of state of the distributor 14, for this purpose, can advantageously be brought about, automatically, under the control of end-of-travel detectors excited by the arrival of each tube bundle 32 respectively in the high position and in the low position, by the fluid 11 itself when this fluid is used to supply the cylinders 15. Other means can however be used for this purpose, it being understood that preferably means which will be chosen, such as those which have just been described, draw their energy from the installation itself, that is to say ensure that it has autonomy of operation.

In general, a person skilled in the art will easily understand that, just as the illustrated and described application of a pump according to the invention 45 does not constitute that a nonlimiting example, the constitution of this same pump 45 as well as that of its motor means 26 could know many variants, in particular according to the chosen application, without departing from the scope of the present invention .

Thus, FIG. 2 illustrates the application of a hydraulic pump 55 according to the invention to the supply, with hydraulic fluid 56 such as hydraulic oil, of the compressor 57 or 58 of an air conditioning installation of the passenger compartment of a thermal engine vehicle, at a pressure and a flow required to drive this compressor either directly, if this compressor is produced in the form of a cylinder 57 for compressing a refrigerant 59, or indirectly , namely by means of a traditional hydraulic motor 60 driving a compressor itself 58.

The pump 55 is in every way similar to the pump 45 described with reference to FIG. 1, so that the same reference numerals have been kept to designate the different components.

However, unlike the pump 45 described with reference to FIG. 1, this pump 55 comprises a single pumping piston 21 and a single driving piston 28, rigidly coupled, as shown schematically at 30, for example in the form a differential piston, the part constituting the pumping piston 21 has a cross section greater than its part constituting the driving piston 28. The pumping piston 21 and the driving piston 28 delimit respectively, in a pumping cylinder 20 and in a cylinder motor 27, of corresponding respective section, a sealed pumping chamber 22 and a sealed motor chamber 29, the volumes of which vary in opposite directions when the pistons 21 and 28 move in unison, in one direction or the other. The chamber 22 houses means for elastic biasing of the pumping piston 21 to a position corresponding to a maximum volume of this pumping chamber 22, that is to say also for elastic biasing of the driving piston 28 to a position of minimum volume of the driving chamber 29, these elastic return means being illustrated in the form of a helical spring 61 housed coaxially with the piston 21 in the chamber 22.

This chamber 22 is connected, by a “go” circuit 62, comprising a non-return valve 63 passing from the chamber 22 to this go circuit 62, or to the hydraulic motor 60, in a non-detailed manner but easily deducible from the description of the Figure 1, either to a chamber 64 of the compressor cylinder 57 and, in parallel, to a hydraulic motor 65 for driving a ventilation turbine. The outward circuit 62 includes a buffer accumulator 71 connected in bypass between the non-return valve 63 and either the hydraulic motor 60 or the chamber 64 of the compressor cylinder 57 and the hydraulic motor 65.

The chamber 64 is delimited, inside a body 66 of the jack 67, by a piston 67 delimiting, opposite to the chamber 64 in the body 66, a chamber 68 for receiving and compressing the fluid refrigerant 59. By way of nonlimiting example, in the example illustrated, the piston 67 has a uniform section and the two chambers 64 and 68 have the same section, so that the pressure communicated by the pumping piston 21 to the hydraulic fluid 56 is fully transmitted to the refrigerant 59. The chamber 68 is itself connected to a circuit (not shown, traditional), for the evolution of the refrigerant 59.

Not shown but easily conceivable by a person skilled in the art, the chamber 64 of the compressor cylinder 57 and the hydraulic motor 65, or the hydraulic motor 60, are also connected to the chamber 22 of the pump 55 by a "return" circuit. 69 comparable to that which has been described with reference to FIG. 1 and comprising in particular, like this one, a hydraulic fluid reservoir 56, not shown, and a non-return valve 70 passing towards the chamber 22. Like the driving chambers 29 of the pump according to the invention 45 described with reference to FIG. 1, the driving chamber 29 of the pump 55 is connected by a pipe 72 to a tubular bundle 73 with which this pipe 72 and the driving chamber 29 constitute, this time no longer permanently but temporarily, repetitively, a closed enclosure filled with a hydraulic liquid 10 with a high coefficient of thermal expansion, such as alcohol or fuel oil.

More specifically, in this example, the tube bundle 73 comprises a multitude of tubes 74 for example rectilinear, mutually parallel, having two ends at each of which they are connected to the corresponding ends of the other tubes 74 by a respective manifold 75, 76 connected elsewhere. , by a respective orifice 77, 78, to a respective piloted valve 79, 80 opening opposite to the corresponding orifice 77, 78 in a respective pipe 83, 84.

The two valves 79 and 80 are controlled by a pressure relief valve 85 to which they are connected, in common, by a respective pipe or control line 81 and 82 and which is interposed in a pipe 86 leading from the manifold 75 to the pipe 72 which , thus, is permanently connected to this collector 75.

At their mutual connection, lines 72 and 86 are connected, by means of a non-return valve 87 passing from this connection, to a line 88 comprising a pressure accumulator 89 in bypass and leading to another controlled valve 90 via a pipe or steering line 91 derived from pipe 82.

This valve 90 communicates, in a controlled manner, the pipe 88 with a pipe 92 leading to a chamber 93 delimited in a sealed manner, inside a cylinder body 94, by a piston 95 rigidly connected, by a rod 96, to a piston 97 having a section larger than that of the piston 95 and mounted meanwhile to the sealed sliding inside a pump body 98 in which this piston 97 separates one from the other a chamber 99 suction and a liquid discharge chamber 100 with a high coefficient of thermal expansion 10. The chambers 99 and 100 are arranged respectively on the same side of the piston 97 as the piston 95 and on the opposite side, so that the respective volumes chambers 99 and 93 vary in the same direction, opposite to the direction of variation of the volume of chamber 100, when the piston 95 and 97 move unison. Elastic means, illustrated in the form of a helical spring 101 disposed inside the delivery chamber 100, coaxially with the piston 97, urge this piston 97 and, with it, the piston 95, in the direction of a reduction in volume of chambers 93 and 99, that is to say also of an increase in volume of chamber 100.

Inside the piston 96 are mounted several non-return valves 102 passing in a direction from the chamber 99 towards the chamber 100 but closed in the opposite direction.

The discharge chamber 100 is permanently connected to the valve controlled 80 by the pipe 84 while the suction chamber 99 is connected, by means of a non-return valve 103 passing towards it, to a pipe 104 connected , where appropriate by means of a buffer tank 157 of liquid 10, at an outlet 105 of a heat exchanger 106 furthermore having an inlet 107 connected by line 83 to the piloted valve 79.

Line 84, chambers 99 and 100, non-return valve 103, line 104, heat exchanger 106 and line 83 thus constitute a circuit external to the tube bundle 73, and this circuit, closed, is filled with the liquid 10 with a high coefficient of thermal expansion serving to animate the pump 55 with a pumping movement possibly with the exception of the buffer tank 157 which can be opened to the open air.

In this application of the invention, the tubular bundle 73 is permanently exposed to a hot source, shown diagrammatically at 108 and constituted by the exhaust gas from the vehicle's heat engine, while the heat exchanger 106 is permanently exposed to a cold source, shown diagrammatically at 153 and constituted for example by ambient air, possibly driven by a fan 109.

In this case, it is by repetitively replacing the liquid 10 with a high coefficient of thermal expansion which, for a period of time, has been enclosed in the circuit comprising the tubular bundles 73 and the driving chamber 29 of the pump 55, by closing the valves 79, 80, and has undergone heating by heat exchange with the exhaust gases 108 inside the tube bundle 73, by liquid of the same kind coming from the heat exchanger 106, c ' that is to say comparatively cold, by the action of the piston 97 and thanks to the opening of the valves 79 and 80, before closing again of the latter, that one causes the alternations of thermal expansions and thermal withdrawals of the liquid with a high coefficient of thermal expansion, driving the driving piston 27.

For this purpose, the triggering of the pressure limiter 85 causes the opening of the piloted valves 79 and 80 which open the closed enclosure composed by the tubular bundle 73, the lines 86 and 72 and the motor chamber 29 of the pump 55; by the same action, the piloted valve 90 allows the passage of the liquid 10 under pressure contained in the accumulator 89, and a joint movement of the pistons 95 and 96 in the direction of a suction, from the tank 157, a liquid from the heat exchanger 106 and a discharge to the tubular exchanger 73 of an amount of this liquid 10, the energy of which due to expansion will cause, as soon as the valves 79, 80 and 90 are closed, the motor piston 28 slides in the direction of reducing the volume of the pumping chamber 22 and a discharge of hydraulic fluid 56 to the compressor cylinder 57 and the hydraulic motor 65 or to the hydraulic motor 60, the return movement of the pistons 21 and 28 then being facilitated by the spring 22 and that of the pistons 97 and 95 caused by the spring 101. A person skilled in the art will readily understand that by varying the proportion between the respective sections of the pumping piston 21 and the driving piston 28, as well as between those of the pumping chamber 22 and the driving chamber 29, it is possible to introduce any gear or multiplication ratio desired between the pressure of the liquid with a high coefficient of thermal expansion, such as 10, supplying the motor chamber 29, and the pumped liquid, such as 56, supplied by the pump chamber age 22 in use, namely for example the compressor 57 and the hydraulic motor 65 or the hydraulic motor 60 if reference is made to the example illustrated in FIG. 2.

When, as described with reference to this FIG. 2, and as also described with reference to FIG. 1, the cross section of the pumping piston 21 is greater than that of the driving piston 28, the pressure of the liquid pumped hydraulics, such as oil 56, is lower than that of the liquid with a high coefficient of thermal expansion animating the driving piston 28. The adoption of identical sections for the driving piston and for the pumping piston would cause a identity between the respective pressures of the hydraulic fluid pumped and the liquid with a high coefficient of thermal expansion serving as a motor.

The choice, for the section of the pumping piston 21, of a value lower than that of the driving piston 28 leads, on the contrary, to an increase in pressure, in the sense that the pressure of the hydraulic fluid pumped is higher than that of the liquid with a high coefficient of thermal expansion serving as a motor. This could be the case in an installation, moreover, in every respect conforming to that which has been described with reference to FIG. 2, for communicating to the refrigerant 59, by means of the compressor cylinder 57, pressures very much greater than those at which generally carries refrigerants, and for example pressures of the order of 120 to 140 bars. This would make it possible to use as refrigerant fluids such as C0 ₂ , which are much less harmful to the environment than the most frequently used refrigerants.

This is also the case in the example illustrated in Figure 3, which will now be referred to.

In this case, the hydraulic pump according to the invention 110, used to supply fuel 151 under high pressure to a common rail 152 for supplying a heat engine, comprises, for example in the same body, a cylinder of pumping 20 and an engine cylinder 27 placed coaxially, in the extension of one another, as described above, but it is now the engine cylinder 27 which has a larger section than that of the cylinder pumping 20. Correlatively, the driving piston 28 has a cross section greater than that of the pumping piston 21, these two pistons remaining rigidly connected, with respect to joint sliding in the respective cylinder, being constituted for example by two stages of the same piston stage, as shown diagrammatically at 30 in FIG. 3, as in FIG. 1.

Opposite one another, the two pistons 21 and 28 delimit in a sealed manner, in the corresponding cylinder 20, 27, a chamber 22, 29 which constitutes respectively a pumping chamber and a driving chamber.

Elastic return means, illustrated in the form of a helical spring 123 disposed inside the engine cylinder 27, opposite the driving chamber 29 relative to the engine piston 28, ensure a joint return of the pistons 21 and 28 in a position corresponding to a minimum volume of the drive chamber 29 and to a maximum volume of the pumping chamber 22. In this case, it is the same liquid 151, namely a fuel such as fuel oil, which constitutes both the hydraulic fluid pumped and the liquid with a high coefficient of thermal expansion used to cause pumping. This fuel 151 is received in a traditional tank 111, and it is connected by a line 112 to the pumping chamber 22, in which this line 112 opens by a non-return valve 113 passing towards this room 22. In the room 22 opens also a pipe 114 leading to the injection manifold 152 of the vehicle engine, which line 114 is connected to the pumping chamber 22 by means of a non-return valve 115 passing in the direction of this line 114 and immediately after which opens into the line 114 a pressure accumulator 116 thus placed in derivation on this pipe 114. These pipes 112 and 114 can be compared, respectively, with the pipes of the circuits 69 and 62 described with reference to FIG. 2, or even with the pipes 23 and 25 described with reference to FIG. 1.

Deriving from the line 112, between the tank 111 and the non-return valve 113, there is another line 117 which is comparable in every way to the line 104 described with reference to FIG. 2 and, like this, leading to a chamber suction 119, at any point comparable to the chamber 99, by means of a non-return valve 118 passing towards this chamber 119 and at all points comparable to the non-return valve 103.

The suction chamber 119 is arranged, inside a pump body 120 at any point comparable to the pump body 98, by subdivision of the interior of this pump body by means of a delivery piston and suction 121 at any point comparable to the piston 97 and, in particular, comprising like the latter 155 non-return valves passing from the suction chamber 119 to a discharge chamber 122 disposed opposite the piston 121 by relative to the suction chamber 119 and in every respect comparable to the discharge chamber 100. The piston 121 is rigidly connected, on the side of the suction chamber 119, to a rod 124, of lower section, constituting a piston at any point comparable to the piston 95, and sealingly closing a chamber 127 disposed opposite the piston 121 relative to this rod 124, inside a cylinder body which merges here with the pump body 120, just as the jack body 94 can merge with the pump body 98.

However, the rod 124 has a tubular shape so as to delimit a coaxial passage 158 which, at one end for securing the rod 124 with the piston 121, opens opposite one of the non-return valves 155 thereof. , on the side of the chamber 119. At the opposite end of the rod 124, towards the chamber 127, this passage 158 opens out by means of a valve having a head 126 housed in the chamber 127 and having a section smaller than that of this chamber 127 and of the piston constituted by the rod 124. A spring 159, working under compression between the rod 124 and the head of the valve 126, tends to keep the latter spaced from the rod 124, that is to say that is, to keep the passage 158 open towards the chamber 127; however, pressure applied to the valve head 126, towards the rod 124, makes it possible to close the passage 158 at this end of the latter. The chamber 127 is connected, by a pipe 128 at all points similar to the pipe 92, to a piloted valve 129 at all points comparable to the piloted valve 90, the piloting of this valve 129 being effected by connection of the latter, by a line or control line 130 at any point comparable to line 91, to a pressure limiter 131 at any point comparable to pressure limiter 85 and, like this, inserted in series in a line 132 leading to the driving chamber 29 of the pump 110 and coming from a manifold 133 at any point comparable to the manifold 75. However, in this case, between this manifold 133 and the pipe 132 comprising the pressure limiter 131 is interposed a non-return valve 134 passing from the manifold 133 to the pressure limiter 131 and the pipe 132. This manifold 133 is also connected to the controlled valve 129 by a pipe 135 at any point comparable to line 88 and, in particular, including like the latter a secondary accumulator 136 intended to facilitate the operation of the piston 121, by action on the piston 126 inside the chamber 127, and a check valve -return 137, at any point comparable to the non-return valve 87, between the connection of this accumulator 136 in bypass and the connection to the manifold 133, namely more precisely at the connection of e the pipe 135 with this manifold 133 in the example illustrated, this non-return valve 137 passing in a direction going from the manifold 133 towards the pipe 135.

Like the manifold 75, the manifold 133 is fluidly connected to the corresponding ends of tubes 138, for example rectilinear and mutually parallel, together constituting a tubular heat exchange bundle 139, moreover comprising another manifold 140 fluidly connected to the opposite ends of the tubes 138 and comparable, in this, to the collector 76 of the tube bundle 73. However, the method of connecting the two collectors 133 and 140 to the other components is different from that of the collectors 75 and 76 of the tube bundle 73 described with reference to FIG. 2. In fact, the manifold 133 is permanently fluidly connected to the chamber 122 discharge via non-return valves 141 passing from the discharge chamber 122 to this manifold 133. The manifold 140, meanwhile, has at least one, and preferably two orifices 142 opening, by a check valve respective return 143 piloted by the pressure limiter 131 to which it is connected by a pilot line or line 144 connected in bypass to the pipe 130, between the pressure limiter 131 and the piloted valve 129, and serving in parallel the two valves 143, on a respective pipe 145 leading to an inlet 146 of a heat exchanger 147 at any point comparable to the heat exchanger 106 and, in particular, bathing like this in the ambient air 153, possibly forced by a fan 156. This heat exchanger 147, thus exposed to a cold source constituted by the ambient air, also has an outlet 148 through which a pipe is connected to it 149 back to the tank 111. The hot source is itself constituted, in this example, by the exhaust gases 154 of the heat engine, bathing the tubular bundle 139. For this purpose, the tubular bundle 139 is housed in a cavity leaktight 150 in which the exhaust gases 154 from the heat engine are circulated, perpendicular to the tubes 138, by bringing these exhaust gas 154 in the cavity 150 by means of an inlet nozzle 151 connected to the exhaust manifold, not shown, of the engine block, and by removing these exhaust gases from the cavity 150 by a outlet end piece 152 connected in turn to the exhaust pipe, the end pieces 151 and 152 being arranged in mutually opposite positions relative to the tube bundle 139.

It will be observed that the hot source could also, in this case, be constituted by the liquid of the cooling circuit of the heat engine, in which case the nozzles 151 and 152 would be connected respectively to an outlet of this liquid outside the engine block and to the associated radiator. to the engine, just as this liquid could be used as a hot source in the case of an installation of the type described with reference to FIG. 2.

A skilled person will easily deduce from the description of the installation illustrated in Figure 2, the operation of the installation illustrated in Figure 3, observing that the opening of the piloted valves 129 and 143 under the control of the limiter. pressure 141 is simultaneous, which means that the valve head 126 closes the passage 158 under the effect of the fluid pressure thus suddenly created in the chamber 127, overcompensating the action of the spring 159 suitably calibrated for this purpose, so well that the piston 121 performs a displacement movement of the fluid with a high coefficient of expansion, in this case the fuel 151 itself, placed at room temperature, that is to say comparatively cold, to introduce it into the tubing 138 of the tube bundle 139 when the liquid of the same kind which was there previously and which is heated there by heat exchange with the exhaust gases 154 can escape therefrom, via the manifold 140, towards the 'heat exchanger 147. When, on the other hand, the controlled valves 129 and 143 are closed, the liquid with a high coefficient of thermal expansion, in this case the fuel 151, is enclosed in an enclosure which it fills completely and which is made up by the tubes 138 of the tube bundle 139, the two collectors 133 and 140, the line 135 with its secondary accumulator 136, the line 132 with the pressure limiter 131 and the driving chamber 29 so that, by heating up by heat exchange with the exhaust gases 154, this liquid with a high coefficient of thermal expansion expands under conditions such that this expansion can only be compensated for by an increase in the volume of the chamber m otrice 29, that is to say by a delivery of fuel to the line 114 from the pumping chamber 22, while the piston 121 returns under the action of the spring 101 to a position corresponding to a minimum volume of the suction chamber 119 and at a maximum volume of the discharge chamber 122; the valve head 126, returned to its position for opening the passage 158 by the spring 159, then allows the fuel contained in the chamber 127 to escape to the chamber 122, by means of the corresponding non-return valve 155. The driving piston 28 and the pumping piston 21 return to their positions of minimum volume of the driving chamber 29 and of maximum volume of the pumping chamber 22, in causing the aspiration of fuel therein, under the effect of the spring 123 and the thermal shrinkage of the fuel in the line 132, returning to ambient temperature. Naturally, when using the heat transfer liquid coming from the cooling circuit of the heat engine or the exhaust gases from the latter to cause fuel injection, it is necessary to provide an auxiliary device to cause this injection in period starting the heat engine, that is to say while the coolant thereof is still at room temperature and there is no exhaust gas. Such an auxiliary device can also be used in the event of operation of the heat engine in hot weather, that is to say if the ambient temperature becomes too close to the temperature of the coolant of the heat engine or of the exhaust gases. It can be either a traditional device, connected to the supply line 114 of the ramp 152 in parallel with the pump 110 according to the invention, or an auxiliary device controlled by heating, for example by Joule effect , fuel 151 inside the tube bundle 139 while the valves 129 and 143 are closed. However, the use of a hydraulic pump according to the invention to ensure or assist the pumping of fuel will, even in such a case, considerably increase the energy efficiency of the heat engine by making it possible to use, at least part time, for the injection of fuel an energy which would be lost in other circumstances in which, on the contrary, additional energy should be consumed to cause the injection. The use of such a pump according to the invention will also make it possible to increase the injection pressure of the fuel and, thus, to improve the combustion of the latter.

Naturally, these variants of Figures 2 to 3 are themselves only non-limiting examples, and illustrate the many possibilities of application of the present invention, as well as the many variants of practical implementation thereof.

Claims

1. Hydraulic pump of the type comprising, in at least one copy:

- a pumping cylinder (20) and a pumping piston (21) slidably mounted in the pumping cylinder

(20) and defining therein a sealed pumping chamber (22), means (23) for hydraulic connection between a reservoir (6, 111) of hydraulic liquid (11, 56, 151) and the pumping chamber (22), comprising non-return means (24, 69, 113) passing towards the pumping chamber (22),

- means (25, 62, 114) for hydraulic connection between the pumping chamber (22) and means (7, 57, 60, 65, 152) consuming hydraulic fluid (11, 151), comprising anti- return (16, 63, 115) passers-by to the consumer means (7), and

- motor means (26) for driving the pumping piston (21) with an alternating sliding movement in the pumping cylinder (20), characterized in that the motor means (26) comprise:

- an engine cylinder (27) and an engine piston (28) slidably mounted in the engine cylinder (27) and delimiting there a sealed motor chamber (29), - means (30) for kinematic connection between the engine piston (28 ) and the pumping piston (21), so that an increase in volume of the driving chamber (29) corresponds to a reduction in volume of the pumping chamber (22) and vice versa, - a pipe (31, 72, 86, 132) for hydraulic connection between the drive chamber (29) and a tubular heat exchange bundle (32, 73, 139), forming with the pipe (31) and with the drive chamber (29) a closed enclosure,

- a liquid (10, 111) ^• with a high coefficient of thermal expansion, enclosed in said closed enclosure and filling it, and means for placing the liquid (10, 111) with high coefficient of thermal expansion in exchange relationship alternately thermal:

• with a hot source (4, 108, 150), while it is enclosed in said enclosure and under conditions such that it remains in the liquid state, by placing the tubular bundle (32, 73, 139) in heat exchange relationship with said hot source (4, 108, 150), and

• and with a cold source (5, 153).

2. Pump according to claim 1, characterized in that the driving chamber (29) and the driving piston (28) have a section chosen from a group comprising the sections respectively lower, identical and higher than that of the pumping chamber (22 ) and the pumping piston (21).

3. Pump according to claim 2, characterized in that the driving piston (28) and the pumping piston

(21) are constituted by two stages of the same differential piston, and the driving chamber (29) and the pumping chamber (22) by two chambers, mutually aligned and separated from each other by the differential piston, of the same cylinder constituting the engine cylinder (27) and the pumping cylinder (20).

4. Pump according to any one of claims 1 to 3, characterized in that the consumer means (7, 57, 60, 65, 152) comprise an accumulator (8, 71, 116) of hydraulic pressure, interposed between them and the hydraulic connection means (25, 62, 114) between the pumping chamber (22) and them.

5. Pump according to any one of claims 1 to 4, characterized in that the pumping chamber (22), the corresponding hydraulic connection means (23, 25), comprising the corresponding non-return means (24, 16) , the reservoir (6) and the consumer means (7) constitute a closed circuit.

6. Pump according to any one of claims 1 to 5, characterized in that the means for placing the liquid (10, 111) with a high coefficient of thermal expansion in heat exchange relationship alternately with a hot source (4, 108 , 150) and with a cold source (5, 153) comprise means for placing the tube bundle (32) in heat exchange relation alternately with the hot source (4) and with the cold source (5).

7. Pump according to claim 6, characterized in that the means for placing the tube bundle

(32) in heat exchange relationship alternately with the hot source (4) and with the cold source (5) comprise:

- A tank (33) divided by a horizontal partition (34), thermally insulating, into a lower chamber (35) and an upper chamber (36), means (37, 38) for circulation of a heat transfer fluid (41) , chosen from a group comprising liquids and gases, between the lower chamber (35) and the cold source (5), - means (39, 40) for circulation of a heat-transfer fluid (42), chosen from a group comprising liquids and gases, between the upper chamber (36) and the hot source (4), and means (14, 15) for moving back and forth vertically, inside the tank (33), the tube bundle (32), comprising at least one copy of a vertical tube (43) freely passing through the partition (34) through a corresponding orifice (44), between a high position, in which it is immersed in the upper chamber, ( 36) and a low position, in which it is immersed in the lower chamber (35).

8. Pump according to claim 7, characterized in that the means (14, 15) for moving the tubular bundle (32) back and forth vertically comprise a hydraulic cylinder (15) and controlled distributor means (14) d 'supply of the cylinder (15) with hydraulic fluid (11).

9. Pump according to claim 8 in its dependency relationship with respect to claim 5, characterized in that the controlled distributor means (14) supply the cylinder (15) with hydraulic liquid (11) from the reservoir (6).

10. Pump according to any one of claims 1 to 5, characterized in that the means for placing the liquid (10, 111) with a high coefficient of thermal expansion in heat exchange relationship alternately with the hot source (4, 108 , 150) and with the cold source (5, 153) comprise means for placing the tube bundle (73, 139) in a permanent heat exchange relationship with the hot source (108, 150) and means for repetitively replacing, in the tubular bundle (73, 139) of liquid (10, 111) with a high coefficient of thermal expansion thus heated by liquid (10, 111) with a high coefficient of thermal expansion previously placed in heat exchange relation with the cold source (153).

11. Pump according to claim 10, characterized in that the means for repetitively replacing the liquid (10, 111) with a high coefficient of thermal expansion comprise a liquid circuit with a high coefficient of thermal expansion outside the tube bundle (73, 139) , comprising heat exchange means (106, 147) with the cold source (153), connected in series with the tube bundle (73, 139) and means for, alternately, fluidly connecting the heat exchange means (106 , 147) to an area (78, 133) of the tube bundle (73, 139) by opening another area (77, 140) thereof to a liquid outlet (10, 111) with a high coefficient of thermal expansion, and closing said zones of the tube bundle (73, 139).

12. Pump according to claim 11, characterized in that said discharge is connected to a reservoir (111, 151) of liquid (10, 111) with a high coefficient of thermal expansion, connected in series with the means (106, 147) d heat exchange with the cold source (153).

13. Pump according to claim 12, characterized in that the liquid (10, 111) with a high coefficient of thermal expansion is constituted by said hydraulic liquid (111) itself.

14. Pump according to any one of claims 1 to 13, characterized in that said coefficient of thermal expansion is at least equal to 1/1000 per ° C.

15. Pump according to claim 14, characterized in that the liquid (10, 111) with a high coefficient of thermal expansion is chosen from a group comprising anhydrous alcohol and fuel oil.

16. Pump according to any one of claims 1 to 15, characterized in that the hot source (4, 108, 150) is chosen from a group comprising solar radiation, exhaust gases and engine cooling circuits air or condensers, the air having undergone heating due to violent compression, industrial discharges, geothermal energy or others.

17. Pump according to one conch of claims 1 to 16, characterized in that the cold source (5, 153) is chosen from a group comprising ambient air, compressed air having undergone a sudden expansion, the waters common, evaporator heating circuits or the like.

18. Hydraulic installation, comprising: - a hydraulic pump,

- a reservoir (6, 111) of hydraulic fluid (11, 56, 151),

- means (7) consuming hydraulic fluid (11, 151), characterized in that the hydraulic pump (45,

55, 110) is in accordance with any one of claims 1 to 17.

19. Hydraulic installation according to claim 13, characterized in that the means (7,

57, 60, 65, 152) consumers of hydraulic fluid

(11, 56, 151 are chosen from a group comprising hydraulic motors and hydraulically driven compressors, in particular as components of air conditioning systems for living spaces or passenger compartments of vehicles, or for the refrigerated transport of goods, and devices for injecting or spraying liquid under high pressure, in particular as components of installations for supplying heat engines with fuel or cutting with water under high pressure.