FR3070479B1 - THERMO-ACOUSTIC SYSTEM - Google Patents

Abstract

The invention relates to a thermoacoustic system 1 comprising a chamber 3 enclosing a fluid 9 and in which a source 2 of sound waves, a phase-shifter and a thermoacoustic device 4 are arranged, said thermo-acoustic device 4 acoustic signal 4 being between said source 2 and said phase-shifter 5, characterized in that said source 2 of sound waves comprises a rigid plate 16 driven in bidirectional translations by a driving device 17 and generating said sound waves propagating in said fluid 9 and passing through said thermoacoustic device 4.

Description

THERMO-ACOUSTIC SYSTEM

The invention relates to a thermo-acoustic system for tempering heat transfer fluids of a group of air conditioning and / or refrigeration vehicle type automotive.

[0002] Thermo-acoustic systems make it possible to transform sound waves into hot or cold sources.

[0003] Air conditioning and / or refrigeration units with a thermoacoustic system are one of the alternatives to standard compression processes using gas, used to cool a passenger compartment.

These systems have certain advantages such as a relatively simple implementation (no need for precisely machined systems), the absence of refrigerant gas with a harmful greenhouse effect or annoying side effects (flammability, harmfulness, risks). related to pressure), the removal of lubricants and refrigerants.

It is even known to use a compact thermo-acoustic system with a loudspeaker as a source of sound waves towards a thermo-acoustic device coupled to a second speaker for phase shifting certain waves, for refrigerate as described in the publication "Analysis of a Coaxial, Compact Thermoacoustic Heat-Pump" of Poignand, G., Podkovskiy, A., Penelet, G., Lotton, P., Bruneau, M., in 2013.

But when thermo-acoustic systems include a speaker as a source for generating acoustic waves, the device is electromagnetic technology, and the device is often specific. These sources are not ideal for achieving a stable wave in a large pressure range and fixed frequency. There is oversized electromagnetic element that generates a very significant weight and a prohibitive cost for industrial or automotive use.

Furthermore, it is known from document FR2890413 an arrangement of a thermo-acoustic system in a combustion engine of a vehicle avoiding using a speaker as a source of acoustic waves in a thermo-acoustic device. - acoustic. The thermo-acoustic system comprises a generally cylindrical enclosure housing a thermo-acoustic device. The thermoacoustic device comprises a thermoacoustic cell, battery or "stack" which quickly leads the heat from the rear face to the front face. The enclosure is connected in branch of an air intake duct or exhaust gas engine. The membrane 40 is immovably fixed to the duct sealingly closing the enclosure. To act as a speaker diaphragm, it is flexible which makes it able to reflect the pressure variations of the conduit. The membrane is excited on its rear face by a wave 02 emitted by the intake air or the vehicle exhaust gas, which generates on the front face of the membrane, the acoustic wave 01 at the origin of the thermo-acoustic phenomenon explained in this same document, in the thermo-acoustic system. The acoustic wave 01 results from the operation of the engine. But the engine can be stopped, and generate no gas or air intake. However it remains desirable to be able to cool or cool the cabin despite these stops. The control of this acoustic wave is unsatisfactory with regard to these needs. Also, it is desired to have a source of stable acoustic wave generation easy to control and without weighing down the vehicle.

According to the invention, these problems are solved by proposing a thermoacoustic system provided with a thermo-acoustic device and where the sound waves are generated by the oscillation of a plate whose translational and bidirectional movement is controlled by a drive device.

More specifically, the invention therefore relates to a thermo-acoustic system comprising a chamber enclosing a fluid and in which are arranged a sound wave source, a wave phase shifter and a thermo-acoustic device, said thermo-acoustic device. acoustic signal being between said source and said phase-shifter, the sound wave source of which comprises a rigid plate driven in bidirectional translations by a drive device so as to generate sound waves propagating through the fluid and the thermo-thermal device. acoustic. The drive device operates independently of the engine. The driving device can be mechanical or hydraulic. The system no longer requires costly and risky sound source elements, the system can operate on demand regardless of the powertrain's operating status. The system makes it possible to obtain sound waves in a stable and regular manner (no comparison).

Preferably, the invention relates to a system the frequency range of oscillations of the plate is between 1 Hz and 100 Hz. These frequencies make it possible to obtain regular waves which have a good power of transformation in the device. thermoacoustic.

Preferably, the invention relates to a system whose fluid is argon under an absolute pressure of 1 to 50 bar. The system requires a fluid that is not harmful compared to the fluids used for the air conditioning and / or refrigeration units. Argon is used for example under an absolute pressure of 1 to 50 bar, preferably at pressures between 20 and 40 bar to increase the non-accessible pressure at atmospheric pressure.

Preferably, the invention relates to a system whose rigid plate is made of material reinforced with carbon fibers. The plate combines high resistance to pressure and a great lightness.

Preferably, the invention relates to a system of which said drive device comprises a single-acting annular jack provided with one side of the plate, return springs and the other side of the plate, a drive mechanism of the plate, said springs or the drive mechanism translating the plate. This training device has a great simplicity of actuating the movement of the plate only on the side of the drive mechanism while requiring few parts.

Preferably, the invention relates to a system whose drive mechanism comprises thrust cylinders or thrust balls. The thrust cylinders or thrust balls can be sized to withstand the very high pressures of the system.

Preferably, the invention relates to a system of which said drive device comprises a double-acting annular cylinder. The drive device can in this case be controlled on both sides of the plate for better control of the oscillation.

Preferably, the invention relates to a system whose phase shifter comprises a wall made mobile by a driving device, driven in bidirectional translations and causing the phase shift of the sound waves. It is possible to replace the speaker of the phase shifter by a movable wall having all the advantages described for the plate of the sound source.

Preferably, the invention relates to a thermo-acoustic assembly which comprises two systems positioned facing each other symmetrically so that they share at least one of their elements. constitutive. For the application to a refrigeration and / or air conditioning unit, it is necessary to have a total power of 5 kW which is obtained by doubling the 2.5 kW power systems and to optimize the whole in term mass and energy consumed, it is wise to share the sound source for two thermo-acoustic systems. It is also advantageous according to the need to provide to share the moving wall of the phase shifter.

Preferably, the invention relates to a vehicle equipped with a system or provided with an assembly, the driving device of which is powered by an onboard network of the vehicle or a network of an electric traction machine. of the vehicle. The system or assembly can exploit the resources in terms of electrical energy already present in the vehicle.

The invention is described in more detail below and with reference to the figures schematically showing these preferred embodiments and implantation.

Figure 1 shows a thermo-acoustic system according to a preferred embodiment of the invention.

Figure 2 shows a thermo-acoustic system with a drive mechanism according to a first preferred embodiment of the invention.

Figure 3 shows the thermo-acoustic system with a drive mechanism according to a second embodiment of the invention.

Figure 4 shows the thermo-acoustic system with a drive mechanism according to a third embodiment of the invention.

Figure 5 shows a thermo-acoustic assembly with two thermoacoustic systems according to a preferred embodiment of the invention.

Figure 6 shows a first implementation in a vehicle of a thermo-acoustic system according to a preferred embodiment of the invention.

Figure 7 shows a second implementation in a vehicle of a thermo-acoustic system according to another preferred embodiment of the invention.

FIG. 8 shows the coupling of a thermo-acoustic system to the heat-transfer circuits of a vehicle according to a preferred embodiment of the invention.

Figure 1 schematically shows a thermo-acoustic system 1 with a source 2 of sound waves emitting in a chamber 3 which are arranged a thermo-acoustic device 4 joined with a phase shifter 5 in the form of speaker 5. L enclosure 3, the thermoacoustic device 4 and the phase shifter 5 cooperate to form a resonator.

A tubular housing 6 with a rectilinear longitudinal axis has at one of its ends: an opening 7 and at the opposite end: a bottom 8. The opening 7 of the housing 6 is hermetically closed by the source 2 of sound waves emitted towards the thermo-acoustic device 4, while the speaker 5 is close to the bottom 8. The thermo-acoustic device 4 and the speaker 5 are coaxial with respect to the housing 6.

The enclosure 3 is delimited by the housing 6 closed by the source 2 of sound waves. The enclosure 3 contains a fluid 9.

The thermo-acoustic device 4 includes a first exchanger 10 itself attached to a thermo-acoustic stack 11, itself contiguous to a second exchanger 12. The exchangers 10 and 12 are connected to the heat transfer circuits 13 of the group of refrigeration and / or air conditioning not shown in this figure 1.

The loudspeaker 5 which is implanted towards the bottom 8 of the housing 6, has a membrane 14 facing the opening 7 of the housing 6. The wave emitting membrane 14 faces the first heat exchanger 10 cold. At the first exchanger 10 succeeds in the direction of the opening 7, the thermo-acoustic stack 11 and the second heat exchanger 12. The second exchanger 12 faces the opening 7. The speaker 5 corrects the phase shift of these waves emitted by the source 2 of sound waves passing through the thermoacoustic device 4.

These waves from the acoustic source 2 will produce through the thermo-acoustic device 4, heat exchange that will be transferred into the heat transfer circuits 13 of the air conditioning and / or refrigeration group defined as in the state of the art. 'art.

The source 2 of sound waves is present in a tubular housing 15 of a diameter greater than that of the housing 6. This housing 15 is coaxial with the housing 6. The wave source 2 comprises a plate 16 for move in the housing 15 and in the chamber 3 under the influence of the driving device 17 in operation, the driving device 17 being partly inside and outside the housing 15 and / or the housing 6, of the enclosure 3.

The plate 16 is circular, rigid and movable. It moves in the housing 15 bi-directionally by translation along an axis parallel to the axis of the chamber 3. The plate 16 oscillates between two extreme positions. Thanks to the not shown fastening means of the plate 16 with the housing 15, those of the housing 15 with the housing 6, and thanks to the plate 16, all ensuring the sealing of the thermo-acoustic system 1 relative to the outside of the thermo-acoustic system 1, the acoustic source 2 in the housing 15 closes the opening 7 of the housing 6.

The disc of the plate 16 is on one side in contact with the fluid 9 contained in the chamber 3 and on the other side with the ambient fluid outside the thermo-acoustic system 1.

The drive device 17 moving the plate 16 is shown schematically in Figure 1 partially outside the housing 15, the housing 6 and the enclosure 3.

Thus the sound waves produced by the displacement of the plate 16 in the fluid 9 of the chamber 3, through the thermo-acoustic device 4 and are out of phase by the speaker 5. This generates pressure variations and temperature in the exchangers 10 and 12 which pass them through the heat transfer circuits 13.

To fix ideas, to obtain a cooling capacity of 2500 Watt output thermo-acoustic device 4 for a variation of 50 ° C with a cold temperature of 5 ° C in the first exchanger 10 and therefore 55 ° C in the second exchanger 12, it is necessary to have a frequency of 41 Hz of generation of sound waves.

In this design, the fluid 9 chosen in the resonator of the thermoacoustic system 1 is argon whose thermal characteristics make it possible to intensify the heat transfer, and whose density makes it possible to intensify the sound energy (which is also allowed by the high pressure targeted). This fluid is argon at an absolute pressure of between 1 and 50 bar. Advantageously, this fluid is used at a pressure of 20 to 40 bar to maximize the sound pressure (300dB approximately) to levels that are not accessible at atmospheric pressure.

So, the dimensions are as follows. The enclosure 3 has a length of 16 cm and an inside diameter of 37 cm. The thermoacoustic device 4 occupies a cylinder with a diameter of 33 cm and a length of 16 cm. The flow rate of the thermoacoustic device 4 is 0.13 m 3 / s. The cylindrical heat exchangers 10 and 12 have a diameter of 32.7 cm and a length of 1.2 cm. They include parallel steel plates spaced 1 mm from each other with a porosity of 60%. The acoustic displacement in the exchangers 10 and 12 is of the order of 1 cm.

The regenerator of the thermo-acoustic stack 11 is a cylindrical 32.7 cm diameter and 4 cm long, made of stainless steel fabric with a porosity of 0.74%. The thickness of the 41 Hz thermal boundary layer is 84 μm.

The temperature measured between the first heat exchanger 10 and the thermoacoustic stack 11 is -11 ° C while the temperature measured between the second heat exchanger 12 and the thermo-acoustic stack 11 is 96 ° C.

The speaker 5 has 5.1 cm diameter. It has a nominal power of 60 W. Its resistance is 7.2 ohms. Its inductance is 0.34 mH. Its strength factor is 2.56 N.A'1. Its moving mass is 1.02 e 03 Kg. Its compliance is 3.9 e 04 m.N'1. The mechanical losses can be 0.14 N.S.rrv1. Its mass is 0.113 Kg. Its overall size is 0.1 L. The loudspeaker 5 provides a pressure / velocity phase shift of -84 °.

The acoustic pressure of the acoustic source 2 is 2.7.105 Pa for a ratio of 7% with the static pressure of the sound waves. The plate 16 has a diameter of 32 cm. The stroke of the plate 16 is 5.8 mm, the displacement frequency is 41 Hz. The cooling capacity supplied by this thermo-acoustic system 1 is 2500 W. The acoustic power is 1815 W.

The drive device 17 comprises a power source 18 placed outside the enclosure 3 and / or the housing 15, connected to the drive mechanism 19 of the plate 16 and a control system not shown for controlling the energy source 18. The control system controls the energy source 18 which supplies power to the drive mechanism 19. The drive mechanism 19 operates so that it drives the plate 16 in order to produce the desired waves in the enclosure 3.

The rigid plate 16 must be made of material reinforced with carbon fibers is made with a method to combine lightness and rigidity. The rigid plate combines high resistance to pressure and a great lightness. Indeed, it is subjected to pressures of 2.3 tons, almost equivalent to those suffered by a heat engine piston, but without the thermal stresses.

Figures 2 and following show different embodiments of a thermo-acoustic system 1 with a drive device 17 meeting the above conditions.

Figure 2 shows a thermo-acoustic system 1 incorporating the same elements as those of Figure 1 and detailing a drive device 17 according to a preferred embodiment of the invention.

The drive device 17 comprises a power source 18 which is an electric motor 20 which sets the drive mechanism 19 in an indirect manner.

The drive mechanism 19 of the plate 16 is a single-acting annular jack 21. Thus on the side of the housing 6, the plate 16 is held by a ring 22 equipped with jacks 23 thrust. The ring 22 occupies the entire periphery of the plate 16. While on the side of the housing 15, the plate 16 is held on its periphery by return springs 24. The jacks 23 thrust of the ring 22 are interconnected by a groove 25. The single-acting annular jack 21 comprises the springs 24 and the ring 22 of thrust cylinders 23.

The electric motor 20 supplies a hydroelectric pump 26 which, through a distribution circuit 27, distributes the pressure required to pressurize the thrust cylinders 23 of the ring gear 22.

With the hydroelectric pump 26 which operates continuously, the high pressure reserve 28 supplies the high pressure valve 29 which flows into the groove 25 if the high pressure valve 29 is open. The thrust cylinders 23 of the crown 22 are filled. The ring 22 then pushes the plate 16 towards the bottom of the housing 15. The plate 16 translates to meet the springs 24 of return. Once the springs 24 return under maximum stress, the plate 16 is in its final position abuts on these springs 24 and the high pressure valve 29 closes.

When the low pressure valve 30 opens, the thrust cylinders 23 of the ring 22 are empty in the low pressure reserve 31 in connection with the pump 26 hydroelectric. The return springs 24 are expanded again by pushing the plate 16 towards the bottom 8 of the enclosure 3. The plate 16 translates in the opposite direction to its first described movement towards the base 8 towards its initial position. The springs 24 return the plate 16 to its initial position closest to the bottom 8 of the chamber 3. The valves 29 and 30 may be solenoid valves or distributors.

The pressure supply of the thrust cylinders 23, properly controlled allows for the movement of the rigid plate 16 corresponding to the desired acoustics. This translational movement generates waves that propagate in one second in the chamber 3 where they come into interaction with the thermo-acoustic device 4 whose hot heat exchanger 12 is connected to the hot coolant circuit of the air conditioning and / or refrigeration unit of the vehicle and whose cold exchanger 10 is connected to the cold heat transfer circuit of the air conditioning and / or refrigeration unit of the vehicle.

In a preferred embodiment of the invention for a frequency of 41 Hz, a valve control is required every 25 ms. This amounts to an admission 2400 times / min which is the order of magnitude managed in the automotive field. If the ring 22 of thrust cylinders 23 has a drive surface of 55 cm3 for a diameter of 35 cm for a width of 5 mm, the required pressure is 41 bar. Each displacement requires 32.34 cm3 of fluid 9, a required flow rate of 4657 L / h and a 12.5 cm3 compressor at 6250 rpm.

By adjusting the size of the ring 22, it is possible to optimize the pressure / flow ratio. In this embodiment, the pressures are around 1600 bar for a flow rate close to 120 L / h and a 1.3 cm2 surface cylinder.

For a ring 22 of thrust cylinders 23 in the form of large surface piston, that is to say 5 mm circular groove for example over the entire circumference of the annular jack 21 with a diameter of 33 cm, pressures remain moderate of the order of 43 bar and the high flow rates 4395 L / h. The pressures and flow rate of this embodiment are in the order of magnitude of those of the automatic transmission hydraulic systems.

For a ring 22 thrust cylinders 23 in the form of five pistons of small area with a diameter of 6 mm, the pressures are high: of the order of 1627 bar and low flow rates 118 L / h.

For a ring 22 thrust cylinders 23 in the form of seven medium-sized pistons with a diameter of 16 mm, the pressures are limited: of the order of 163 bar and the moderate flow 1175 L / h.

The drive mechanism 19 includes all the elements between the plate 16 and a power source 18. Also some of these elements are external to the enclosure 3 and the housing 15, others are in the one and / or the other.

The hydroelectric pump 26 has a power between 1.5 kW and 10 kW depending on whether it is powered with a voltage of 48 volts or all the voltages of an electric vehicle or hybrids between 150 volts and 1000 volts. Preferably, the pump 26 has a power between 2 kW and 4 kW depending on whether it is supplied with a voltage of 48 volts or 200 volts.

FIG. 3 presents a thermoacoustic system 1 as previously presented in FIG. 1 with a drive mechanism 19 that meets the desired characteristics but that differs from those described with reference to FIG. 2, because of the distribution circuit 27 between the annular jack 21 and the energy source 18.

In this embodiment of Figure 3, the annular cylinder 21 is single-acting, it comprises on either side of the plate 16: a ring 22 of thrust cylinders 23 and springs 24 of return. But the ring 22 of thrust cylinders 23 is directly coupled to a piston 32 for pressurizing by a distribution circuit 27. The distribution circuit 27 is mainly outside the chamber 3 and the housing 15. This pressurizing piston 32 is biased by a radial cam 33. This radial cam 33 is obtained from the corrugations present on the rim 34 of a wheel 35. The rim 34 of the wheel 35 has elevated zones distributed every 60 ° which culminate + 5.8 mm with respect to the low zones. distributed every 60 °. This radial cam 33 acts when the wheel 35 is rotated by an electric motor 20 with a power between 2 kW and 4 kW according to a voltage of 48 V or 200 V.

A radial cam revolution 33 represents two translation movements between the extreme positions of the plate 16. When the radial cam 33 rotates at 400 revolutions per minute, this represents 2400 movements per minute, ie a frequency of 41 Hz. The ratio desired drive between the radial cam 33 and the electric motor 20 is 1/10, the ratio is reducing. The speed of the electric motor 20 should be 8000 rev / min which will require a mass of inertia to regulate.

The efficiency between the source 18 of electrical energy and the movement of the plate 16 would be of the order of 72%, distributed between the electric motor 20 and its control at a height of between 0.9% and 0, 96%, the reduction by 0.96% and the hydraulic conversion to 0.8%.

The rigid plate 16 is subjected to pressures of 2.3 tons, almost equivalent to those undergone by a heat engine piston. These pressures also dimension the thrust cylinders 23 and the springs 24 which drive the plate 16 because they undergo peaks of 400 kg.

The pressures for six thrust cylinders 23 of 1 cm in diameter are 400 bar.

For the hydraulic source, it is possible to amplify the pressure and the difference between the low and raised zones of the radial cam 33. The cost of production is low in the context of large-scale and therefore competitive production.

FIG. 4 shows another preferred embodiment of the drive mechanism 19 of the thermo-acoustic system 1 of FIG. 1. The drive mechanism 19 produces an oscillating movement by a direct drive of a source of energy 18 such as an electric motor 20.

The plate 16 is held on the bottom side of the housing 15 by six return springs 24 distributed uniformly and on the side of the housing 6 by a drive mechanism 19 comprising as many thrust balls 36 as springs 24 return either six thrust balls 36. The thrust balls 36 are in contact with a ring 37. The ring 37 is coaxial with the plate 16 by means of bearing bearings 38 regularly distributed between the outer periphery of the ring 37 and the interior of the housing 15.

A first face of the ring 37 serves as an axial cam 39 pushing the balls 36 in an axial direction parallel to the axis of the housing 6 towards the opening 7, and the second face 40 opposite the first face 39, is toothed to be driven by a gear 41 at the end of an electric motor 20. The electric motor 20 has a power of between 1.5 kW and 10 kW depending on whether it is supplied with a voltage of 48 volts or all the voltages of an electric vehicle or hybrids between 150 Volts and 1000 Volts. Preferably, the electric motor 20 has a power between 2 kW and 4 kW depending on whether it is supplied with a voltage of 48 volts or 200 volts. The axial cam 39 is composed of a curvilinear alternation of hollows and elevations. Every 30 °, there is a hollow followed by an elevation. The top of an elevation rises to + 5.8 mm from the lowest point of a trough. When the electric motor 20 is running, it rotates the gear 41 which meshes with the teeth of the toothed face 40 of the ring 37, rotating it.

The face serving as an axial cam 39 then rotates simultaneously and the elevations come to bear the thrust balls 36. These balls 36 force the movable plate 16 to move towards the springs 24, and until the pressure is released by the path of the raised area of the ring 22 in motion and the arrival of the lower zone. face of the ball 35 thrust. Having no more thrust, the return springs 24 hitherto compressed by the plate 16 during its translation towards the bottom of the housing 15, relax and return the plate 16 to its initial position towards the bottom 8 of the housing 6.

In a preferred embodiment, at each turn of the ring 37, there are six translation movements between the extreme positions of the plate 16, ie with a speed of 400 revolutions per minute, there are 2400 movements which equals a movement at a frequency of 41 Hz.

We choose a belt drive ratio / pinion 1/20 is an engine speed of 8000 revolutions per minute for a ring 22 of 33 cm in diameter and a pinion of 1, 6 cm in diameter.

We choose a motor angle sensor with a precision of 5 ° angle to have a phase shift of +/- 1.6 ° maximum to drive the speaker 5.

An angular sensor of the top dead center type on the ring 37 is to be provided also to check the correct frequency and control accordingly the electric motor 20.

The efficiency between the source 18 of electrical energy and the movement of the plate 16 is of the order of 81% which is distributed between the electric motor 20 and its control at a level of 0.9% to 0.96 % and the linear movement up to 0.9% at 0, 96%.

The cost of production is a little high because the toothed gears are complex to limit vibration but remains competitive in the context of large series of production.

The rigid plate 16 must be made of material reinforced with carbon fibers or made with materials that allow it to provide the necessary rigidity while guaranteeing its lightness against pressures of up to 2.3 tons the equivalent to little near the pressure experienced by a piston engine, without the thermal stresses. This also dimensions the pushers and springs 24 which will animate the plate 16 with a maximum to 400 kg.

FIG. 5 shows a thermo-acoustic assembly 42 with two coaxial thermoacoustic systems 1 which share the same source 2 of sound waves. The elements of the second thermo-acoustic system 1 will be designated with the same reference as in the preceding paragraphs with the suffix ".2", except for those common with the first thermo-acoustic system 1.

The second resonator is positioned symmetrically to the first resonator with respect to the source 2 of sound waves. The second thermoacoustic device 4.2 is implanted in the second chamber 3.2 so that the devices 4 and 4.2 are arranged symmetrically with respect to the plate 16. The second chamber 3.2 contains the same fluid 9 as the first chamber 3, preferentially argon. The concavities of the diaphragms 14 and 14.2 of the loudspeakers 5 and 5.2 charged with phase-shifting the sound waves emitted by the plate 16 in the two resonators, are opposite one another. The exchangers 10.2 and 12.2 of the second thermoacoustic device 4.2 are also connected to the heat transfer circuits 13 of the air conditioning and / or refrigeration unit.

The source 2 of sound waves is common to both thermo-acoustic systems 1 and 1.2 hermetically sealed by the housing 15 containing the plate 16. The drive device 17 making the movable plate 16 is predominantly external to the speakers 3 and 3.2 and housing 15.

The translational movement of the plate 16 in the axial direction of the assembly 42 generates acoustic waves in each of the resonators simultaneously. The exchangers 10.2 and 12.2 of the second thermoacoustic system 1.2 produce equivalent amounts of heat which feed via the heat transfer circuits 13, the air conditioning and / or refrigeration unit. The thermo-acoustic assembly 42 thus formed makes it possible to combine the heat production of the two thermo-acoustic systems 1 and 1.2 from the same source 2 of sound waves, to double the quantity of heat produced for a consumption of energy almost equivalent to a thermo-acoustic system 1 only.

Thus, the thermo-acoustic unit 42 with a double thermo-acoustic system 1 with a cooling capacity of 2.5 kW each, makes it possible to achieve a cooling capacity of 5 kW, which is sufficient for the proper functioning of a group. air conditioning and / or refrigeration of a motor vehicle.

FIG. 6 shows a preferred embodiment of a thermoacoustic assembly 42 with a double thermoacoustic system 1 according to the invention powered by the electrical network 43 of voltage 48 Volts of a vehicle 44.

The vehicle 44 has at the front a motor compartment 45 under the hood of a power unit 46 associated with the block 47 comprising the inverter 48 and the electric machine 49 for pulling the vehicle 44 on one side of the vehicle 44 and on the other a battery 50 of voltage 12 volts, and at the rear a storer 51 voltage 48 volts and a converter 52 DC / DC. The converter 52 is connected to the battery 50 by an electrical edge network 53 of voltage 12 Volts and to the storer 51 on the electrical network 43 of the electrical machine 49. The storer 51 is connected to the inverter 48 by the electrical network 43 voltage 48 volts.

The storer 51 and the converter 52 are located in the rear portion 54 of the vehicle 44.

The thermo-acoustic assembly 42 is also located in the engine compartment 45 at the front of the vehicle 44. The housings 6 and 6.2 and the housing 15 of the thermo-acoustic assembly 42 are oriented longitudinally with respect to the vehicle. 44, as the portion of the drive device 17 outside the housing 15. The housings 6 and 6.2 and the housing 15 are in proximity to the voltage battery 50 12 volts. But the drive device 17 is powered by the electrical network 43 of voltage 48 Volts via the inverter 48. The floor of the vehicle 44 have bushings 55 at the rear to allow the routing of the electrical networks 43 and 53 between the rear portion 54 and the engine compartment 45.

The interfaces with the heat transfer circuits 13 are not shown in this figure.

FIG. 7 shows another preferred embodiment of a thermoacoustic set 42 with a double thermoacoustic system 1 in a vehicle 44 as described in FIG. 6.

The thermo-acoustic assembly 42 is implanted in the rear portion 54 of the vehicle 44 between the storer 51 and the bodywork 56, so that the axis of the housings 6 and 6.2 and the housing 15 is parallel to the longitudinal direction. of the vehicle 44. The portion of the drive device 17 outside the housing 15 is slightly offset towards the front of the vehicle 44 relative to the housings 6 and 6.2 and the housing 15. The energy source 18 of the drive device 17 is connected to the storer 51 by the electrical network 43 voltage 48 Volts through the floor of the vehicle 44 via bushings 55 floor.

The volume excluding external exchangers has dimensions less than 25 cm x 25 cm x 40 cm. The mass of the assembly 42 is less than 7 kg which is the mass of the elements of an air conditioner usually providing the expected performance for a vehicle.

FIG. 8 shows the heat interfaces of a thermoacoustic assembly 42 with a double thermoacoustic system 1 according to the embodiment of FIG. 4 in a vehicle 44 as described in FIG. 7.

The thermo-acoustic assembly 42 is located at the front of the vehicle 44 near the battery 50 of voltage 12 V, the longitudinal axis of the housings 6 and 6.2 and the housing 15 is oriented in the longitudinal direction of the vehicle 44. The exchangers 10 and 12 of the first thermoacoustic device 4 foremost towards the front of the vehicle 44, are connected to the heat transfer circuits 13 of the heat exchanger 56 of the front of the vehicle 44. The exchangers 10.2 and 12.2 of the second thermo-acoustic device 4.2 closest to the rear of the vehicle 44 are connected by the heat transfer circuits 13.2 to exchangers 57 of the air conditioning unit. The source 18 of electrical energy is not represented, nor its power supply.

As a variant of the invention, the thermo-acoustic unit 42 with a double thermoacoustic system 1 may have fluids 9 and 9.2 which are identical or different in the two resonators, enclosures 3 and 3.2.

Alternatively, in a thermo-acoustic system 1 with an electrohydraulic pump 26, the annular cylinder 21 could be double-acting, that is to say with a ring 22 of double-acting thrust cylinders 23 to replace the 23 single-acting thrust cylinders and 24-point springs.

In a variant of the invention, in a thermo-acoustic system 1 with an electrohydraulic pump 26, the pump 26 has a power between 1.5 kW and 10 kW depending on whether it is powered with a voltage of 48 volts or all the voltages of an electric vehicle or hybrids between 150 Volts and 1000 Volts. Preferably, the pump 26 has a power between 2 kW and 4 kW depending on whether it is powered on an electrical network 43 of voltage 48 V or 200 V.

In a variant of the invention, it is possible to replace the loudspeaker 5 serving as phase shifter 5 by a movable wall. It is possible to replace this movable wall in place of the bottom 8 of the housing 6. It is possible to have a thermo-acoustic assembly 42 with two thermo-acoustic systems 1 and 1.2 which share elements of phase shifters comprising a wall mobile.

Alternatively, the frequency range of the oscillations of the plate 16 is between 1 Hz and 100 Hz.

Alternatively, the thermo-acoustic assembly 42 could supply an air conditioning unit and / or refrigeration and other equipment via the second heat transfer circuits.

As a variant of the embodiment of FIG. 2 with a heat engine vehicle 44, the valves of the pressure reserves of the common rail direct injection system circuit could be pooled with the valves 29 and 30 of the valves. pressure reserves of the drive mechanism 19.

The invention has a thermo-acoustic system 1 whose volume outside heat exchanger is less than that of a conventional air conditioning (25x25x40 cm3) and a cooler (5x20x20 cm3). The weight is less than 7 kg corresponding to the mass of a conventional air conditioning (7 to 8 kg).

The invention thus proposes a thermo-acoustic system 1 offering multiple advantages. The invention described makes it possible to produce an acoustic source 2 of very high power without the weight and cost constraints of electromechanical systems of the speaker type used as source 2 of sound waves. The invention makes it possible to carry out an oscillatory translation movement at a fixed frequency of the order of ten Hz of a rigid plate 16 over a course of a few millimeters. This movement generates pressure waves of several hundreds of thousands of Pascal. The invention generates this oscillatory movement by a mechanism with a rotary type direct drive with an electric motor 20, or indirectly from a hydraulic pump 26. These thermoacoustic systems 1 may not be solely dedicated to air conditioning and include elements the drive device 17 which can be shared with other functions in the vehicle 44 which allows to limit the cost while improving efficiency.

[00104] It is thus possible to have a thermo-acoustic system 1 with a compact architecture easy to implement in the vehicle 44, a mass much lower than the existing which reduces the consumption of the vehicle 44, and with a lower price. The working fluid is readily available and less harmful to the environment than the fluids most commonly used in air conditioning / refrigeration. These acoustic sources are the only ones used for very high powers higher than an order of magnitude of 1 kW without the weight and cost constraints of electromechanical systems of the speaker type 5.

Claims (10)

Claims: 1. A thermoacoustic system (1) comprising a chamber (3) enclosing a fluid (9) and in which are arranged a source (2) of sound waves, a phase-shifter (5) and a thermo-acoustic device (4), said thermo-acoustic device (4) being between said source (2) and said phase-shifter (5), characterized in that said source (2) of sound waves comprises a rigid plate (16) driven in translations bidirectional by a driving device (17) and generating said sound waves propagating in said fluid (9) and passing through said thermoacoustic device (4). 2. System (1) according to claim 1 characterized in that the frequency range of oscillations of the plate (16) is between 1 Hz and 100 Hz. 3. System (1) according to claim 1 or claim 2, characterized in that the fluid (9) is argon under an absolute pressure of 1 to 50 bar. 4. System (1) according to one of claims 1 to 3, characterized in that the plate (16) rigid is made of material reinforced with carbon fibers. 5. System (1) according to one of claims 1 to 4, characterized in that said drive device (17) comprises, on one side of the plate (16), a single-acting annular cylinder (20). provided with return springs (24) and on the other side of the plate (16), a drive mechanism (19) for the plate (16), said springs (24) or the drive mechanism (19) translating the plate (16). 6. System (1) according to claim 5, characterized in that the drive mechanism (20) comprises thrust cylinders (23) or thrust balls (36). 7. System (1) according to one of claims 1 to 4, characterized in that said drive device (17) comprises a double-acting annular cylinder. 8. System (1) according to one of claims 1 to 7, characterized in that the phase shifter (5) comprises a wall made movable by a drive device (17), driven in bidirectional translations and causing the phase shift of the waves sound. 9. A set (42) thermoacoustic characterized in that it comprises two systems (1) and (1.2) according to one of claims 1 to 8 positioned vis-à-vis one another so symmetrical so that they share at least one of their constituent elements. 10. Vehicle (44) with a system (1) according to one of claims 1 to 8 or provided with an assembly (42) according to claim 9 characterized in that the drive device (17) is powered by an onboard network (53) of the vehicle or a network (43) of an electric vehicle traction machine (49) (44).