FR3057305A1 - MOTORIZATION ASSEMBLY WITH RANKINE LOOP - Google Patents

Abstract

The invention relates to an engine assembly comprising: - an internal combustion engine (1) equipped with a cooling circuit for receiving a cooling liquid, - a loop (10) of Rankine using a working fluid and comprising means heat exchange (11, 11 ') between the working fluid and the coolant of the cooling circuit using this cooling circuit as a hot source, and expansion means (12, 12') capable of transforming the energy from the expansion of the working fluid into mechanical energy, characterized in that the expansion means (12, 12 ') and the heat exchange means (11, 11') are connected fluidically so that the thermodynamic cycle of at least a portion of the working fluid of the Rankine loop (10) comprises an evaporation step followed by a first superheating, followed by a first expansion, followed by a second superheat, followed by a second expansion .

Description

Holder (s): PEUGEOT CITROEN AUTOMOBILES SA Société anonyme.

Extension request (s)

Agent (s): PEUGEOT CITROEN AUTOMOBILES SA Public limited company.

(04) RANKINE LOOP MOTORIZATION ASSEMBLY.

FR 3 057 305 - A1 (57) The invention relates to a motor assembly comprising:

- an internal combustion engine (1) equipped with a cooling circuit intended to receive a coolant,

a Rankine loop (10) using a working fluid and comprising heat exchange means (11, 11 d between the working fluid and the coolant of the cooling circuit using this cooling circuit as a hot source, and expansion means (12, 12 d capable of transforming energy from the expansion of the working fluid into mechanical energy, characterized in that the expansion means (12.12 d and the heat exchange means (11 , 11 j are fluidly connected so that the thermodynamic cycle of at least part of the working fluid of the Rankine loop (10) comprises an evaporation step followed by a first overheating, followed by a first expansion, followed by a second overheat, followed by a second trigger.

RANKINE LOOP MOTORIZATION ASSEMBLY

The present invention relates to the field of internal combustion engines comprising a device for recovering thermal energy, more particularly implementing a Rankine cycle.

Economic pressure (fuel prices) and environmental pressure (regulation of polluting emissions and greenhouse gases) guide the current trend towards the development of traction chains with constantly improving efficiency.

Hybrid-electric vehicles provide a first response. They include at least:

- an electric motor-type machine arranged in the vehicle so as to provide torque to at least one set of wheels and capable of causing the vehicle to move for a minimum duration and / or distance outside the heat engine in order to inhibit any polluting emission or to increase the performance of the heat engine by adding additional torque or mechanical power,

- And a traction energy store, in the form of super-capacities or a high-tension traction battery made up of at least one module bringing together an arrangement of cells associated in series and / or in parallel compared to the others, whatever the technology: Li-ion, Ni-MH, Ni-Cd families, ...

In the area of thermal engines also, for example of the internal combustion type, research is constantly developing towards improving efficiency. However, according to the current state of the art, in their most favorable conditions of use, the efficiency of such engines rarely exceeds 40 to 45%. Thus, in general and at the most efficient operating points, the total energy contained in the fuel is distributed between, approximately and in order of magnitude:

- 30% at the wheels, to move the vehicle;

- 35% by thermal losses in the cooling system and by convection and radiation;

- 35% in exhaust gases.

This status describes the distribution of energy flows over the most efficient operating points. In real use, only 10 to 20% of the total energy contained in the fuel reaches the wheels; it can even be 0%, for example when the vehicle is stopped with its engine running at idle speed.

Following the example of documents FR2868809B1 or also FR3028885A1, ways of improvement have been developed to improve the efficiency of the heat engine, in particular by using the implementation of thermodynamic cycles (Stirling, Ericsson, Rankine in particular) converting the heat contained in exhaust gases in mechanical or thermal energy.

The implementation of the Rankine thermodynamic cycle with exhaust gases as a hot source has the advantage, known to those skilled in the art, of high exergy. Such an implementation, with the exhaust gases as a hot source, however poses many constraints.

Indeed, the use of exhaust gases as a hot source of the Rankine cycle is not as relevant for auto-ignition engines (ex: Diesel) and for hybrid-electric powertrains (ex: in the case where the engine is stopped or when the engine is used on operating points with better efficiency) than for spark ignition engines (ex: indirect or direct injection of petrol, LPG, etc.) , due to a lower exhaust gas temperature.

In addition, the use of exhaust gases as a hot source of the Rankine cycle is in competition with the priming of pollution control devices and the reduction of pollutant emissions: the evaporator is thus arranged downstream of the pollution control devices and is therefore subject to lower gas temperatures, therefore reducing the potential for energy recovery.

In addition, the use of exhaust gases as a hot source of the Rankine cycle is less suitable for operation in the field of the particular motor vehicle than in that of stationary use, heavy goods vehicles or locomotives for example. : the usage cycles are much more transient and with operating points mainly in areas of partial load and low load, therefore with lower temperature and exergy levels available on the exhaust gases.

In the case of the use of exhaust gases as a hot source of the Rankine cycle again, the temperature and pressure levels in the Rankine loop all the more constrain the design, the dimensioning of the associated components: evaporator, condenser , turbine, etc. and therefore the cost of the system.

Finally, the use of exhaust gases as a hot source of the Rankine cycle requires the installation of the evaporator on the exhaust line, which then constitutes an additional exhaust backpressure and degrades d 'As much the intrinsic efficiency of the heat engine, leading to the implementation of a short-circuit pipe and a short-circuit valve of the evaporator by the exhaust gases. The use of exhaust gases as a hot source of the Rankine cycle also requires the flow of working fluid in the underbody environment from the environment under the hood and at the front of the vehicle and generates the risk of flammability. -due to the nature of the Rankine fluid and the temperatures and pressures induced.

Therefore, the problem underlying the invention is to improve the recovery of thermal energy on a heat engine by a Rankine loop while eliminating the problems due to the use of exhaust gases as that hot spring of the Rankine cycle.

To achieve this objective, there is provided according to the invention a motor assembly comprising:

- an internal combustion engine equipped with a cooling circuit intended to receive a coolant,

a Rankine loop using a working fluid and comprising means for heat exchange between the working fluid and the coolant of the cooling circuit using this cooling circuit as a hot source, and expansion means capable of transforming the energy coming from the expansion of the working fluid into mechanical energy, characterized in that the expansion means and the heat exchange means are fluidly connected so that the thermodynamic cycle of at least part of the working fluid the Rankine loop includes an evaporation step followed by a first overheating, followed by a first expansion, followed by a second overheating, followed by a second expansion.

The technical effect is to improve the recovery of the energy contained in the heat transfer circuit, certainly at an exergy level (taking into account the temperature level) lower than in the exhaust gases (yet then at a level substantially identical) but is more available and less dependent on the engine load level due to the thermal capacity levels used

Various additional characteristics can be provided, alone or in combination:

As a variant, the evaporation and superheating stages are carried out through a single exchanger with separate dual circulation of working fluid, which saves resources.

In another variant, the evaporation and the first superheat take place through a first heat exchanger and the second superheat through a second heat exchanger, the first and the second heat exchanger being arranged at different locations in the cooling circuit. This variant makes it possible, for example, to place the first exchanger at a point on the cooling circuit which is warmer than for the second exchanger.

As a variant, the evaporation and the first superheating take place through a heat exchanger arranged fluidly, relative to the direction of circulation of the coolant within the cooling circuit, downstream of an exchanger for cooling the exhaust gases. recirculated to the engine intake, to take advantage of the higher coolant temperature at the outlet of the recirculated exhaust gas heat exchanger.

As a variant, the first expansion and the second expansion are carried out by common expansion means, which saves resources.

As a variant, the first expansion and the second expansion are carried out by separate expansion means, which makes it possible to more finely adapt the expansion means to the thermodynamic conditions of the working fluid.

As a variant, the Rankine loop comprises valves and means for controlling these valves, these valves being arranged so that in a first mode of operation, the means of heat exchange between the working fluid and the coolant of the thermal engine cooling circuit use this cooling circuit as a hot source, and in a second operating mode, the heat exchange means between the working fluid and the coolant of the thermal engine cooling circuit use this cooling circuit cooling as a cold source.

As a variant, the Rankine loop comprises a valve and means for controlling this valve, this valve being arranged so that in a first operating mode, the circulation of the working fluid in the heat exchange means for the second overheating is authorized and in a second mode of operation, this circulation is prohibited.

The invention also relates to a vehicle, characterized in that it is equipped with a motorization assembly according to any of the variants previously described.

Other particularities and advantages will appear on reading the description below of a particular embodiment, without limitation of the invention, made with reference to the figures in which:

- Figure 1 is a schematic representation of a first embodiment of the invention, for a first operating state.

- Figure 2 is an enlarged view of the coolant distribution device and its arrangement in the first operating state.

FIG. 3 shows a variant of the device for distributing the cooling liquid of FIG. 2.

- Figure 4 is a schematic representation of the first embodiment of the invention for a second operating state.

- Figure 5 is an enlarged view of the coolant distribution device and its arrangement in the second operating state.

- Figure 6 is a schematic representation of the first embodiment of the invention for a third operating state.

- Figure 7 is a schematic representation of the Rankine cycle in the Temperature / Entropy field according to the invention.

- Figure 8 is a schematic representation of another embodiment of the invention.

- Figures 9 and 10 are a schematic representation of a variant of the embodiment shown in Figure 8 with a reversible Rankine loop.

- Figures 11 and 12 are a schematic representation of a variant of reversible Rankine loop according to the invention.

- Figures 13 and 14 are a schematic representation of another variant of reversible Rankine loop according to the invention.

- Figures 15 and 16 are a schematic representation of another variant of reversible Rankine loop according to the invention.

Figure 1 shows a first embodiment of the motor assembly of the invention.

The engine assembly includes a heat engine 1. The heat engine 1 can be for example an internal combustion engine with positive ignition or an internal combustion engine with compression ignition. Such an engine assembly preferably equips a vehicle, in particular a motor vehicle, to allow movement thereof, but may also be suitable for a stationary installation.

The heat engine 1 is provided with a cooling circuit inside which a coolant circulates, such as a mixture of water and mono-ethylene glycol for example.

The cooling circuit includes an internal circuit for circulating the coolant inside the engine. The cooling circuit is intended to take the calories generated by the heat engine and to evacuate them to maintain the heat engine at an acceptable operating temperature.

The inputs and outputs of the various members arranged in the cooling circuit are defined relative to the direction of circulation of the coolant.

The heat engine 1 is connected at the output S2 of the internal circuit 2 to an input E31 of a box 3 for the outlet of the coolant. The box 3 is intended to distribute the coolant inside various branches of the cooling circuit.

The housing 3 comprises a first outlet S31 of coolant fluidly connected, by means for example of a pipe, to an inlet E4 of an air heater 4 and to an inlet E5 of an exchanger 5, also designated EGR exchanger, of cooling of the recirculated exhaust gases towards the engine intake 1. The air heater 4 and the EGR exchanger 5 are fluidly arranged in parallel with each other at the outlet of the heat engine 1. The air heater 4 is crossed by an internal and / or external air flow which is intended to be delivered inside a passenger compartment of the motor vehicle to heat an air present inside the passenger compartment. The fan heater 4 is preferably housed inside a vehicle heating installation. The recirculated exhaust gases can be taken upstream or downstream from exhaust gas depollution devices (recirculation of high pressure exhaust gases called EGR HP or recirculation of low pressure exhaust gases called EGR BP according to that the sampling is respectively upstream or downstream of the pollution control devices, the upstream and downstream direction being defined here relative to the direction of circulation of the exhaust gases). As a variant, the EGR exchanger 5 can be supplemented or replaced by an exhaust manifold integrated into the cylinder head or by a passage of exhaust gases recirculated internally from the heat engine 1, for example within the cylinder head.

The housing 3 includes a second coolant outlet S32 fluidly connected, for example by means of a pipe 7 to an inlet E8 of a coolant pump. The coolant pump 8 comprises an outlet S8 connected to an input E2 of the internal circuit 2 to the heat engine 1. The pipe 7 is a pipe for direct return of coolant to the internal circuit 2 of the engine 1 via the pump 8 ( classically designated by-pass in English). Line 7 ensures a minimum flow within the heat engine 1 which would be dissatisfied with the circulation of coolant within only the air heater 4 and EGR exchanger 5.

The box 3 comprises a third outlet S33 of coolant fluidly connected, by means for example of a pipe, to an inlet E9 of a radiator 9. The radiator 9 is crossed by an external air flow to cool the liquid cooling inside the radiator 9. The radiator is preferably housed inside a front facade of the motor vehicle to facilitate a heat exchange between the external air flow and the coolant inside the radiator 9. The housing 3 also includes a thermostat 19, which can be controlled and whose function is to distribute the coolant as a function of its temperature to the outputs S32, S33.

The radiator 9 comprises an outlet S9 for coolant fluidly connected to a second inlet E32 of the housing 3. This second inlet E32 is fluidly connected, for example by an internal conduit within the housing 3, to the second outlet S32 for liquid case cooling 3.

The cooling circuit also comprises a first thermostatic device 6 comprising an inlet E6 of coolant fluidly connected, by means for example of a pipe, to an outlet S5 of the EGR exchanger 5. The thermostatic device 6 also comprises a first outlet, S61, and a second outlet, S62, for coolant. The thermostatic device 6 distributes the coolant as a function of its temperature to the outputs S61 and / or S62.

The inlet E6 of the thermostatic device 6 for coolant is fluidly connected, by means of for example a pipe, to the outlet S5 of the exchanger 5 EGR. The second outlet, S62 is fluidly connected to an inlet E71 of the pipe 7. The outlet S4 of the air heater joins the fluid connection from the second outlet S62 to the pipe 7.

The motorization assembly of the invention also includes an energy recovery device implementing a Rankine cycle. This energy recovery device comprises a heat exchange loop 10 inside which a working fluid circulates.

A heat exchanger 11 is arranged in the heat exchange loop 10, in thermal contact with the engine cooling circuit 1 as a hot source so as to capture the calories conveyed by the coolant to transfer them to the working fluid. This heat exchanger 11 is said to be hot because it is connected to the hot source. This heat exchanger 11 preferably constitutes, according to a first operating mode of the heat exchange loop 10, an evaporator for the working fluid, so that the latter passes from a liquid state at the inlet of the heat exchanger 11 to a vapor state at the outlet of the heat exchanger 11.

This heat exchanger 11 called hot comprises an inlet E11 of coolant fluidly connected to the first outlet, S61, of the thermostatic device 6. This heat exchanger 11 further comprises an outlet S11 of coolant fluidly connected to an inlet E72 of the pipe. 7 connecting the housing 3 to the pump 8.

Furthermore, the first outlet, S61, of the thermostatic device 6 is connected to the inlet E11 of the exchanger 11 while the second outlet, S62 is fluidly connected to an inlet E71 of the pipe 7. The outlet S4 of the unit heater joins the fluid connection from the second outlet S62 to the inlet E71 in line 7.

In this embodiment, another heat exchanger 11 ′ is disposed in the heat exchange loop 10, in thermal contact with the cooling circuit of the engine 1 as a hot source so as to capture the calories conveyed by the coolant for transfer them to the working fluid. This other heat exchanger 11 'is also said to be hot because it is also connected to the hot source and preferably constitutes, according to a first operating mode of the heat exchange loop 10, a superheater for the working fluid, so that the latter enters and leaves the heat exchanger 11 ′ in the vapor state.

This other heat exchanger 11 ′ called hot comprises an inlet E11 ′ of coolant fluidly connected to an outlet, S62 ′ of the pipe 7. This heat exchanger 11 also comprises an outlet S11 ′ of coolant also connected fluidly to the input E72 of the pipe 7 connecting the box 3 to the pump 8.

The heat exchange loop 10 also comprises a compressor or a pump 14 for increasing the pressure of the working fluid and for circulating the fluid inside the heat exchange loop 10.

From the compressor 14, in the direction of circulation of the working fluid, the heat exchange loop 10 comprises the exchanger 11 in which the working fluid captures calories from the engine cooling circuit, a first expansion member 12, also designated turbine or regulator, able to transform energy from the expansion of the working fluid into mechanical energy. Inside the expansion member 12 the fluid undergoes a first expansion which lowers the temperature and the pressure of the working fluid.

From the first expansion member 12, the heat exchange loop 10 then comprises the exchanger 11 'in which the working fluid captures calories from the engine cooling circuit, a second expansion member 12', inside from which the fluid undergoes a second expansion which lowers the temperature and the pressure of the working fluid.

The mechanical energy thus produced from the thermal energy released by the expansion of the working fluid can then be either communicated directly by at least one disengageable pinion gear, at the output of the crankshaft of the thermal engine, or preferably transformed by an electric energy generator or alternator,

- stored in a high voltage traction battery or a 48V battery of a hybrid-electric vehicle

- or used to facilitate or assist the generation of electrical energy at the level of an alternator of a conventional or micro-hybridized powertrain (for example of the automatic stop and restart type still called "stop & start" in English ) where the alternator is usually driven by the engine.

From the second expansion member 12 ’, the heat exchange loop 10 then comprises a heat exchanger 13 said to be cold because it is thermally connected to a cold source. This heat exchanger 13 preferably constitutes, according to a first mode of operation of the heat exchange loop 10, a condenser 13 inside which the working fluid condenses by yielding its heat at substantially constant pressure to the cold source.

The heat exchanger 13, said to be cold, of the heat exchange loop 10 describing a Rankine cycle is thermally connected to a second cooling circuit, independent of the cooling circuit of the engine 1, inside which a coolant circulates, such as a mixture of water and mono-ethylene glycol for example. This second cooling circuit comprises a pump 15, a radiator 16. The radiator 16 is crossed by an external air flow to cool the coolant inside the radiator 16. The radiator is preferably housed inside d '' a front panel of the motor vehicle to facilitate heat exchange between the external air flow and the coolant inside the radiator 16, and preferably upstream or in parallel with the radiator 9 taking into account the direction of circulation of the external air flow from the external environment at the front of the vehicle to the environment of the vehicle engine bonnet. In this variant, the cold exchanger 13 is an indirect or water type condenser. It can then include in particular:

- a working fluid reservoir, which stores the quantity of non-circulating working fluid and separates the gaseous minority phase from the majority liquid phase of the working fluid leaving the condenser,

- a sub-cooler, subjected to a flow of coolant from the second cooling circuit and which provides heat exchange between the working fluid and the coolant in the second circuit, to bring the working fluid to a temperature below its condensation temperature. This arrangement makes it possible to guarantee that the working fluid is completely in the liquid phase at the inlet of the pump or of the compressor 14 in order to be free of any risk of cavitation which may cause deterioration or ruin of the pump or the compressor 14.

The radiator 16 comprises an outlet S16 of coolant fluidly connected to the pump 15 which is itself connected to an inlet E13 of coolant which includes the cold exchanger 13. The cold exchanger 13 also includes an outlet S13 for coolant.

The engine may also include a turbocharger 17 and a charge air cooler 18 for cooling the intake air at the outlet of the turbocharger 17 and before it enters the combustion chambers of the engine 1.

The charge air cooler 18 is connected to the second cooling circuit preferably in parallel with the cold exchanger 13 so as not to add up their pressure drops.

The second cooling circuit also alternatively ensures the cooling of the EGR gases (in this case, the EGR exchanger 5 is then placed on this second circuit) and / or of a part of the turbocharger 17 (for example the turbine casing ) and / or at least one electrical or electronic component of the traction chain of a hybrid electric vehicle (electric motor or generator, power electronics, charger, high voltage traction battery, etc.).

In a variant, the cold exchanger 13 is a direct or air type condenser, preferably housed inside a front facade of the motor vehicle to facilitate a heat exchange between the external air flow and the work inside the cold exchanger 13, and preferably upstream or in parallel of the radiator 9 taking into account the direction of circulation of the external air flow.

The cooling circuit comprises yet another device 6 ′ for distributing the flow of coolant, of which FIG. 2 presents an enlarged schematic view of an embodiment. Preferably, this device 6 ′ for distributing the coolant flow rate is integrated into the coolant return pipe 7 at the inlet E8 of the pump 8 from the second outlet S32 of the housing 3.

This device 6 ′ for distributing flow comprises an inlet E6 ’for coolant fluidly connected, as close as possible to the case 3 for the outlet of the coolant, more precisely to its second outlet S32.

This 6 ’flow distribution device comprises a first outlet S61’, and a second outlet, S62 ’, for coolant. As detailed below, the device 6 ’has the function of distributing the coolant coming from the box 3 to the outputs S61’ and / or S62 ’.

Relative to the direction of circulation of the coolant in the return line 7, the inlet E71 is downstream of the inlet E72, which is itself downstream of the outlets S61 ’and S62’.

In order to optimize the ratio between the flow of coolant through the exchanger 11 'and the flow of coolant through the pipe 7 by creating a variable pressure drop, mainly depending on the temperature of the coolant in the pipe 7, the device 6 'for distributing the coolant flow comprises a first thermostatic actuator 6a' for controlling the flow of coolant through the first outlet S61 'and a second thermostatic actuator 6b' for controlling the coolant flow through the second outlet S62 '. The first and second thermostatic actuators 6a ', 6b' each have a thermosensitive element, 6a3 ', 6b3' respectively irrigated by the coolant and implanted so as to minimize their impact on the section of coolant passage through the device 6 '.

The operation is as follows:

In the configuration illustrated in FIG. 1, the heat engine 1 is in transient thermal regime, in a first phase of temperature rise.

When the circulation of the coolant within the heat engine 1 is established (because it can be temporarily cut off, either at the level of the pump 8, or at the level of the housing 3, to accelerate the rise in temperature of the heat engine 1), it takes place within the internal circuit 2 of the heat engine 1 then leads to input E31 of the housing 3. The heat engine 1 has not yet reached its regulation temperature and its thermostat 19 closes the output S33. Preferably, for acceptable operation of the engine 1, the regulation temperature, corresponding to the temperature of the coolant causing the thermostat 19 to start to open, is preferably between 75 and 105 ° C.

In this configuration, the temperature of the coolant irrigating the heat-sensitive elements 6a3 and 6b3 of the device 6 'and the heat-sensitive element of the coolant flow distribution device 6 is less than a predefined threshold, Sr, for which it is judged that the temperature and the heat transferable through the exchangers 11 and 11 'are too low to take advantage of the Rankine loop and priority is given to the rise in temperature of the heat engine 1 and to the heating of the passenger compartment, via the 'air heater 4. Concerning the second thermostatic device 6', the first thermostatic actuator 6a 'closes the first outlet S61' and the second thermostatic actuator 6b 'closes the second outlet S62'. In practice, the first S61 outlet is never completely sealed. The predefined threshold, Sr, is lower than the regulation temperature of the heat engine 1 and preferably between 40 and 70 ° C.

In this first phase of temperature rise, the first thermostatic device 6 disposed at the outlet of the exchanger 5 EGR closes the first outlet S61 to prevent the circulation of the coolant in the exchanger 11 said to be hot, but leaves the second outlet S62 opened. The coolant having passed through the exchanger 5 EGR is directed by the second outlet S62 of the thermostatic device 6 towards the inlet E71 of the pipe 7 and the inlet E8 of the water pump 8.

In this configuration, the Rankine loop is then deactivated: the fluid pump or compressor 14 and the expansion member 12 are inoperative here.

The thermostat 19 being closed, the coolant at the engine outlet goes, via the outlet S31 of the housing 3, to the air heater 4 and the EGR exchanger 5 before being reintroduced via the inlet E71 in the pipe 7 and , by the outputs S34 and S32 of the housing 3, through the pipe 7 via the second thermostatic device 6 ', before being sucked in by the inlet E8 of the water pump 8 and being discharged therefrom at the inlet E2 of the heat engine 1.

However, if the speed of rotation of the heat engine 1 or the pressure of the coolant leaving the heat engine 1 at the inlet E6 'of the device 6' for distributing the coolant flow upstream of the first actuator 6a ', relative to the direction of circulation of the liquid, exceeds a first predefined threshold of speed or a predefined threshold of given pressure, while the first actuator 6a' closes the first outlet S61 ', the minimum passage section then still available to the liquid cooling may not be sufficient for the pressure in the cooling circuit to remain below a safety threshold so that, in the long term, the reliability of the circuit is not impaired and a risk of leakage is avoided. To remedy this risk, provision can therefore be made for the first actuator 6a 'to also be pressostatic, so that if the pressure of the coolant upstream of the first actuator 6a', relative to the direction of circulation of the liquid, exceeds a determined threshold , Sp, the first output S61 'opens. The first predefined threshold of rotation speed of the engine 1, Sn1, is preferably greater than 3000 rev / min respectively for an auto-ignition engine and 4000 rev / min for a spark-ignition engine and / or the predefined pressure threshold, Sp, is preferably greater than 2.2 bar relative to atmospheric pressure.

As shown in Figure 3, the valve 6a1 'of the first actuator 6a is not integral with its axis 6a2' and can therefore open under the action of the pressure of coolant acting on it, compressing it a return spring, not shown, which can also be calibrated as a function of the coolant flow rate ratio between the bushings of the pipe 7 and of the exchanger 11 '.

According to this embodiment, the valve 6a1 ’of the first actuator 6a is both thermostatic and pressostatic: it opens according to the most severe condition between the temperature of the coolant and its pressure, causing maximum opening. In the example presented in FIG. 3, if the pressure decreases below the determined threshold Sp, for example because the rotation speed of the motor 1 drops again below the predefined threshold Sn1 of rotation speed of the motor 1, then the valve 6a1 returns to the position controlled by the position of the axis 6a2 'of the first actuator 6a as a function of the temperature of the coolant. The temperature of the coolant irrigating the thermosensitive element 6a3 'of the actuator 6a' may have meanwhile varied, so it may not be exactly the position initially occupied by the valve 6a1 'before the appearance of the pressure condition.

The exchanger 13, said cold of the Rankine loop, is irrigated by the coolant of the second cooling circuit if the associated pump 15 is activated. A possible alternative proposes to bypass the circulation of coolant in the second cooling circuit and therefore within the exchanger 13 said cold, useless since the Rankine loop is then deactivated. This circulation of coolant within the heat exchanger 13 said cold then inoperative however allows by conduction to put it at an already favorable temperature in order to guarantee a rapid availability of the cold source.

FIG. 4 shows the first embodiment in a second operating phase in which the heat engine 1 is still in transient thermal regime, in a second temperature rise phase.

In this second phase, the heat engine has not yet reached its regulation temperature and its thermostat 19 keeps the output S33 closed.

However, in this second phase, the convergence phase of cabin thermal comfort in heating mode is complete and the temperature and heat transferable through the hot exchangers 11 and 1T are now sufficient to take advantage of the Rankine loop: the Rankine loop is then activated and the pump 14 and the expansion members 12 and 12 'now function.

The temperature of the coolant irrigating the thermosensitive element of the thermostatic device 6 being greater than the predefined threshold, Sr, the thermostatic device 6 disposed at the outlet of the exchanger 5 EGR closes the second outlet S62 to prevent the direct return of the coolant towards the pipe 7, but opens the first outlet S61 to allow the passage of the coolant in the exchanger 11.

The coolant having passed through the exchanger 5 EGR is directed by the first outlet S61 of the thermostatic device 6 the exchanger 11, which it crosses before joining the pipe 7 (via its inlet E72) and the inlet of the pump 8. On passing through the exchanger 11, the coolant gives up calories to the working fluid of the Rankine loop, thereby increasing the temperature before expansion through the first expansion member 12.

This series arrangement of the 5 EGR exchanger and the exchanger 11, in this order taking into account the direction of circulation of the coolant at the engine outlet, and in parallel with the air heater 4, makes it possible to transmit to the working fluid from the Rankine loop, the calories dissipated by the recirculated exhaust gases on passing through the 5 EGR exchanger while overcoming thermal losses through the air heater 4.

Preferably, the thermostatic devices 6 and 6 'are of the piloted type: an electrical element controlled by a vehicle computer is integrated into the thermostatic devices 6 and 6', and makes it possible to cause them to open at a different coolant temperature. of their passive opening start thresholds. The actuation of the thermostatic devices 6 and 6 ’are implemented by a control law recorded in a memory space of the computer, depending in particular on the temperature of the coolant leaving the heat engine and the 5 EGR exchanger. As an alternative, the thermostatic devices 6 and 6 'can each be replaced by an actuator of the on / off or proportional solenoid valve type, for example with solenoid.

Still in this second operating phase, as shown in FIG. 5, the temperature of the coolant irrigating the thermosensitive element 6b3 'of the second actuator 6b' of the device 6 'being greater than the predefined threshold, Sr, the second actuator 6b' opens the second outlet S62 'to allow the passage of the coolant to the exchanger 11', but the first actuator 6a 'leaves the first outlet S61' closed to prevent the passage of the coolant, the temperature of the coolant which irrigates it still being insufficient to cause its opening to open and to open a larger passage for the fluid towards the pump 8. The coolant leaving the housing 3 is then preferably directed towards the exchanger 11 ′, the second actuator 6b 'then opening the second output S62'.

When passing through the exchanger 11 ', the coolant at the engine outlet transfers calories through the exchanger 11' to the working fluid of the Rankine loop, thereby increasing the temperature before expansion through the second turbine. 12 '.

While the coolant flow distribution device 6 'occupies the configuration described in FIG. 5, more particularly while the first actuator 6a' closes the first outlet S61 ', if the coolant pressure at the input E6 'of the device 6' and more particularly at the output S61 'upstream of the first actuator 6a', exceeds a second predefined speed threshold, Sn2, or exceeds the predefined pressure threshold Sp, then the first output S61 ' opens. As illustrated in Figure 3, the valve 6a1 'of the first actuator 6a is both thermostatic and pressostatic and opens according to the most severe condition between the temperature of the coolant and its pressure, which causes the greatest opening . The second predefined threshold of rotation speed of engine 1, Sn2, is greater than the first predefined threshold of rotation speed of engine 1, Sn1, and preferably greater than 3300 rpm respectively for a self-igniting engine and 4800 rpm min for a spark ignition engine.

If the pressure decreases below the determined threshold Sp, then the valve 6a1 ’returns to the position controlled by the position of the axis 6a2’ of the first actuator 6a as a function of the temperature of the coolant. The temperature of the coolant irrigating the thermosensitive element 6a3 'of the actuator 6a having been able to vary in the meantime, it may therefore be that it is not exactly the position initially occupied by the valve 6a1' before the appearance of the pressure condition.

FIG. 6 shows the first embodiment for a third operating phase in which the heat engine 1 is in established thermal regime. In this third phase, the heat engine 1 has reached its regulation temperature and its thermostat 19 is in regulation (half-open) or in full opening.

At low opening, the thermostat 19 directs a small part of the coolant flow from the heat engine 1 to the radiator 9. The housing 3 is designed so that the flow of coolant from the heat engine 1 directed to the circuit unit heater 4 and exchanger 5 EGR is independent of the position of thermostat 19 for a given engine speed. The rest of the coolant flow from the heat engine 1 is therefore directed via the internal path S34 of the housing 3 towards the second outlet S32 and the pipe 7 and the pump 8.

As the opening of the thermostat 19 increases, the internal path S34 from the housing 3 to the pipe 7 closes: consequently, the proportion of coolant coming from the radiator 9 in the pipe 7 increases. Conversely, as the thermostat 19 closes, the internal path S34 from the box 3 to the pipe 7 reopens: the proportion of coolant from the radiator 9 in the pipe 7 then decreases accordingly.

When fully open, the thermostat 19 directs the entire coolant flow from the heat engine 1 and not having been directed, by the design of the housing 3, towards the air heater 4, the exchanger 5, towards the radiator 9. EGR and through the thermostatic device 6. The internal path S34 of the box 3 is then completely closed and the entire flow of coolant from the radiator 9 is directed through the second outlet S32 of the box 3 in the pipe 7 through the thermostatic device 6 'to the pump 8.

In this third operating phase, the temperature of the coolant entering the thermostatic devices 6 and 6 'is such that they direct the coolant passing through them respectively through the hot exchangers 11 and 11'. Consequently, when the thermostat 19 is fully open, the coolant coming from the radiator 9 arrives at the input E6 ′ of the thermostatic device 6 ′, therefore at a temperature lower than that of the coolant at the outlet S2 from the directed heat engine 1, via the output S31 of the housing 3, through the exchanger 5 EGR and at the input of the thermostatic device 6. The exchanger 11 is thus traversed, in this third operating phase, by the coolant coming from the output S2 of the heat engine 1 and having undergone no other heat exchange, while the coolant arriving at inlet E6 'of the thermostatic device 6', while being entirely coming from the outlet S9 of the radiator 9, may have at least temporarily a temperature irrigating the heat-sensitive elements 6a3 'and 6b3' below the threshold Sr and thus cause, by closing the outlet S62 ’Of the thermostatic device 6’, the cut off of the coolant flow through the exchanger 11 ’.

During the first opening of the thermostat 19 of the engine 1 after the temperature rise phase of the heat engine from a cold start, a large volume of cold liquid contained in the loop of the cooling circuit comprising the radiator 9, since it has no not yet exchanged calories with the heat engine 1 since its thermostat 19 was previously closed, arrives at input E32 of the box 3, upstream of the pipe 7 for engine cooling return: this flow of cold coolant, however limited since the thermostat 19 of the engine is then slightly open, mixes with the flow of hot liquid at the engine outlet using the internal path S34 of the box 3 towards the return pipe 7 and keeps the temperature of the coolant at the inlet E6 'of the bypass substantially constant practiced in the pipe 7 at the level of the two actuators 6a ', 6b'.

Thus, the thermostatic device 6 'keeps the first outputs S61' and second output S62 'open, preferably without the need to activate the electrical supply: a portion of the coolant at the input E6' of the thermostatic device 6 'crosses via the outlet S62' the exchanger 11 'and transfers its heat to it, while the other portion of the coolant at the inlet E6' crosses the thermostatic device 6 'via the outlet S61' and arrives at the inlet E8 of the pump 8.

For its part, the thermostatic device 6 keeps the first outlet S61 open and the second outlet S62 closed, preferably without the need to activate the electrical supply: the coolant at the engine outlet passes through the 5 EGR exchanger before irrigating the exchanger 11 and giving it heat.

Preferably, the thermostat 19 of the engine 1 is of the controlled thermostat type or as an alternative, the device ensuring the thermal regulation of the engine 1 is thus designed, in both cases so as to favor the operation of the engine 1 at a coolant temperature. as high as possible, in particular taking into account the reliability of the heat engine 1. Thus, the temperature of the coolant leaving the heat engine 1 and entering the heat exchangers 11 and 11 ′, then higher for example by the action of the thermostat 19 controlled and, as regards the heat exchanger 11, the recovery in the coolant of the heat engine 1 of the calories of the exhaust gases recirculated through the exchanger 5 EGR, makes it possible to increase the pressure and the temperature of the working fluid in the Rankine loop at the exchangers 11 'and especially 11: the heat of the coolant of the heat engine 1 is then transferred through exchangers 11 and 11 ’to the working fluid of the Rankine loop at a higher temperature and the efficiency of the Rankine cycle is thereby increased.

Furthermore, the larger opening of the outlet S61 'through the pipe 7, linked to the opening of the first actuator 6a' by the temperature of the coolant at the heat-sensitive element 6a3 '(thermostatic opening) and / or by the coolant pressure at the valve 6a1 '(pressostatic opening), can reduce the part of the liquid flow sent to the exchanger 11', for example while the device 6 'for distributing the liquid flow the cooling system occupies the configuration described in FIG. 5 and that the second actuator 6b 'opens the second outlet S62' to allow the passage of the coolant to the exchanger 11 '. This larger opening is judiciously compensated for by a larger opening of the valve of the second actuator 6b ', by consequently setting the opening start temperatures and the opening strokes of the two actuators 6a', 6b 'in order to maintain the hydraulic balance of the entire bypass insensitive to the intermediate positions (during opening) of these two actuators 6a ', 6b'. In order to better control this hydraulic balance, it is also possible to provide, as for the second actuator 6b ’, a first actuator 6a’ of the controlled thermostat type.

In the case of actuators 6a 'and 6b' of the controlled thermostats type, their electrical supplies are deactivated, preferably independently of one another, as soon as the temperature of the coolant irrigating their respective heat-sensitive elements 6a3 ' and 6b3 'is sufficient to ensure only the full opening of the valve 6a1' of the actuator 6a 'or of the valve of the actuator 6b', without it being necessary to activate the power supply.

As an alternative, the actuators 6a ’, 6b’ of the flow distribution device 6 ’can, each and independently of one another, be replaced by an actuator of the solenoid on / off or proportional type, for example with solenoid. The computer then controls the electrical actuation of the device 6 ′ for distributing the coolant flow rate, or alternatively of the solenoid valve.

With this arrangement of heat exchange loop 10, the efficiency of the Rankine loop is increased by taking advantage of the increase in efficiency as the evaporation pressure increases and while being freed from excessive humidity at the turbine at the end of expansion. Indeed, as illustrated in Figure 7 in a temperature-entropy diagram, in operation, the Rankine cycle consists of the following stages:

A => B: The pump or compressor 14 circulates the working fluid in the liquid state and increases the pressure; it is ideally a reversible adiabatic and isentropic process. The fluid remains in the liquid state therefore the energy consumption of the pump is relatively low. The condensation of Rankine fluid reduces the pressure at the outlet of the turbine and the energy required by the pump 14 represents a very small part of the energy available to the turbines 12 and 12 ’.

B => C => C ’: the exchanger 11 evaporates the working fluid. It is ideally an isobaric process. In order to guarantee that the fluid leaving the exchanger 11 is completely in the vapor phase and that the future expansion will be completely in the vapor phase, in particular to prevent the formation of droplets within the turbine 12 due to the condensation of the fluid work, it ensures overheating (C => Cj of the working fluid in the vapor state. Indeed, these droplets, driven by a high speed, could damage the turbine 12 by erosion.

C ’=> D: the first turbine or first regulator 12, crossed by the working fluid then in the vapor state, recovers mechanical work and first expands the working fluid in the vapor state. It is ideally a reversible adiabatic and isentropic expansion which lowers the temperature and pressure of the working fluid in the vapor state to point D. Point D is advantageously positioned so that the fluid of working remains in the vapor state, in the vicinity of the curve, Pvs, of saturated vapor pressure of the working fluid, while maximizing the temperature difference with point C '.

D => C ”: the working fluid undergoes in the exchanger 11’ a second phase of overheating, without changing state between D and C ”. It is ideally an isobaric process. The point C "is substantially the intersection of the isobar passing through D with the isotherm passing through C", because it is admitted here that it will not be possible to bring the working fluid to a temperature higher than C ".

C ”=> D’: the second turbine or second regulator 12 ’is traversed by the working fluid and recovers mechanical work by completely relaxing the working fluid, according to a reversible expansion ideally also adiabatic and isentropic.

D ’=> A: The fluid condenses on passing through the exchanger 13 thermally connected to the cold source. It yields its heat at constant pressure and returns to its liquid state.

The real loop differs from the ideal cycle explained above because of the irreversibilities induced by the components: compression and expansion not completely isentropic, friction of the working fluid generating pressure drop, processes not completely adiabatic and isothermal (imperfect efficiency of heat exchangers 11, 11 'and 13, heat exchanges with the environment under the hood), etc.

Compared to a Rankine cycle with a single evaporation, the area inside the curve described by the Rankine cycle thus modified increases and therefore the net work done by this cycle also. In addition, the efficiency of the cycle also increases thanks to the increase in the average temperature at which the heat from the heat transfer circuit is transferred to the working fluid. In this example, evaporation and double overheating as well as double expansion are carried out, each of the detents succeeding overheating. As an alternative, a triple, quadruple overheating, associated with a triple, quadruple, expansion, etc. may be provided following evaporation. without changing the scope of the present invention. Those skilled in the art will however note the impacts in terms of installation and system cost that an excessive multiplication of the number of overheats - detents generates.

FIG. 8 presents a variant of the embodiment presented in FIG. 1. This embodiment differs from that presented in FIG. 1 in that a three-way valve 20, controlled by the computer, is placed in the exchange loop 10 thermal between the two turbines 12 and 12 ', with a track connected to the outlet of the first turbine 12, another connected to the line leading to the inlet of the exchanger 11' and another track connected to the inlet of the second turbine 12 '.

In a first operating position, this valve 20 directs the working fluid coming from the first turbine 12 directly to the second turbine 12 ’. In this position, in the event that the temperature of the exchanger 11 ′ is deemed insufficient, the valve 20 makes it possible to short-circuit it and to place the two turbines 12, 12 ′ directly in series with each other, without intermediate heat exchange with the coolant passing through the exchanger 11 'then insufficiently hot or animated with a too low flow rate or when the actuator 6b' closes the outlet S62 'of the second thermostatic device 6'. It is then advantageous to pass the working fluid through the heat exchanger 11 only, with the hottest cooling fluid.

In its second operating position, this valve 20 directs the working fluid coming from the first turbine 12 through the exchanger 11 'to the second turbine 12'. In this position, the heat exchange loop 10 described in FIG. 8 allows the Rankine cycle described in FIG. 7 to be ensured.

FIGS. 9 and 10 show a variant of the previous embodiment in which the Rankine loop 10 is reversible, that is to say in which:

In a first conventional configuration described in FIG. 9, the exchangers 11 and 11 'have the engine cooling circuit as a hot source, while the exchanger 13 has the second cooling circuit as a cold source.

In a second configuration called "heat pump" described in FIG. 10, the exchanger 11 has the cooling circuit of the engine as a cold source while the exchanger 13 has the second cooling circuit as a hot source. According to this configuration, the heat exchange loop 10 transfers the calories absorbed to the second cooling circuit and to the outside air to the cooling circuit of the heat engine 1.

For this purpose, the heat exchange loop 10 is suitably arranged, as illustrated in FIG. 9 or 10, using two valves V1, V2 three-way and a distributor valve V3 four-way so that the direction of the circulation of the working fluid in a part of the heat exchange loop 10 can be reversed depending on the position adopted by the valves V1, V2 and V3. The valves V1, V2 and V3 can be actuated independently or by a common actuator, not shown.

One track of the valve V1 is connected to the outlet of the second turbine 12 ', another track is connected to the working fluid inlet, Ef13 of the exchanger 13, another track is connected to the inlet of the first turbine 12.

One track of valve V2 is connected to the outlet of the second turbine 12 ', another track is connected to the inlet of the first turbine 12, another track is connected to the outlet of working fluid, Sf 11 of l exchanger 11.

One channel of the valve V3 is connected to the outlet of the pump 14, another channel is connected to the working fluid inlet Et 11 of the exchanger 11, another track is connected to the working fluid outlet Sf13 of the exchanger 13, another channel is connected to the inlet of the pump 14.

More specifically in conventional mode (Figure 9):

- The three-way valve V1 puts the output of the second turbine 12 'in communication with the working fluid inlet, And 13 of the exchanger 13, and condemns the communication with the inlet of the first turbine 12;

- The three-way valve V2 places the working fluid outlet Sf 11 of the exchanger 11 in communication with the inlet of the first turbine 12, and blocks communication with the outlet of the second turbine 12 ’;

- The four-way distributor valve V3 communicates the output of the compressor 14 with the working fluid inlet, Ef 11, of the exchanger 11 as well as the working fluid outlet, Sf 13, of the exchanger 13 with the input of compressor 14.

Thus, in the conventional mode, the working fluid compressed by the pump 14 (point B in FIG. 7) passes through, by the position taken by the distributor valve V3, the exchanger 11 then hot source, within which it undergoes evaporation and a first overheating (step B => C 'in FIG. 7) before passing through the position taken by the valve V2, the first turbine 12 and undergoing a first expansion there (step C' => D). The valve 20 authorizes the working fluid to pass through the exchanger 11 ′ to undergo a second overheating there (step D => C ”) then pass through the second turbine 12 ′ to undergo a second expansion there (step C” => Dj. The positions taken by the valves V1 and V2 then direct the working fluid at the inlet Ef13 of the exchanger 13 to be condensed there (step D '=> A). The distributor valve V3 then directs the working fluid from the outlet Sf13 from the exchanger 13 to the inlet of the pump 14 to undergo compression there (step A => B).

In “heat pump” mode (FIG. 10), the circulation of the working fluid is reversed in part of the loop 10. However, keeping the same references for the inputs / outputs of the exchangers 11, 13 as those of FIG. 9 :

- The three-way valve V1 communicates the input Ef13 of the exchanger 13 with the input of the first turbine 12;

- The three-way valve V2 communicates the output of the second turbine 12 'with the output, Sf11 of the exchanger 11, and blocks communication with the input of the first turbine 12;

- The four-way distributor valve V3 communicates the output of the compressor 14 with the output Sf 13 of the exchanger 13 as well as the input Ef11 of the exchanger 11 with the input of the compressor 14.

Thus, in the “heat pump” mode, the working fluid compressed by the pump 14 passes through the position taken by the distributing valve V3, the exchanger 13 then hot source, within which it absorbs heat before cross, by the position taken by the valve V1, the first turbine 12 and undergo a first expansion there. The valve 20 then closed authorizes the working fluid to pass through the second turbine 12 ’to undergo a second expansion there: the two turbines 12 and 12’ are thus associated in series with one another. The positions taken by the valves V1 and V2 then direct the working fluid at the outlet Sf 11 of the exchanger 11 to be condensed there. The distributor valve V3 then directs the working fluid from the inlet Ef11 of the exchanger 11 to the inlet of the pump 14 to undergo compression there.

While the heat engine 1 is in transient thermal regime, in the first or second phase of operation, as illustrated in FIGS. 1 and 4, the “heat pump” mode of the Rankine loop illustrated in FIG. 10 makes it possible to transfer the heat pumped by the Rankine loop to the external environment and to the second cooling circuit to the coolant at input E2 of the heat engine 1. The Rankine loop then adopts a configuration such that its hot source is the second cooling circuit and the external environment while its cold source is then the cooling circuit of the heat engine 1. The Rankine loop is then activated and the pump 14 and the expansion members 12, 12 'operate. At the same time, the device 6 for distributing the coolant flow equipping the engine cooling return pipe 7 occupies the configuration illustrated in FIG. 5: in particular, the second actuator 6b, which in this case must be a controlled thermostat or a solenoid valve, is forced into the open position by electrical control. The configuration of the Rankine loop and of the cooling circuit of the heat engine 1 introduces additional calories to the coolant at the outlet of the exchanger 11, which then fulfills the role of condenser, at the inlet E2 of the heat engine 1. This configuration accelerates thus the temperature rise of the heat engine 1. This configuration is implemented in a given range of temperatures of the outside air and of the coolant at the outlet S2 of the heat engine 1. When it becomes energetically more irrelevant to pump via the Rankine loop the heat losses from the second cooling circuit and from the external environment, the Rankine loop switches from heat pump mode (illustrated in Figure 10) to conventional mode (illustrated in Figure 9), in particular by adapting the position valves V1, V2, V3 located on the Rankine loop.

FIGS. 11 and 12 show another architecture of a reversible heat exchange loop 10, respectively in the conventional mode and in the heat pump mode. In this architecture, the evaporation and the overheating are in the conventional mode (FIG. 11) carried out within the same exchanger, for example, the exchanger 11, where the circulation of the working fluid is split and is carried out by example against the current of the circulation carrying out the first evaporation.

In the conventional mode, the exchanger 11 has the engine cooling circuit as a hot source, while the exchanger 13 has the second cooling circuit as a cold source. In the second so-called "heat pump" configuration, the exchanger 11 has the engine cooling circuit as a cold source, while the exchanger 13 has the second cooling circuit as a hot source.

In this architecture:

One track of the valve V1 is connected to the outlet of the second turbine 12 ', another track is connected to the working fluid inlet, Ef13 of the exchanger 13, another track is connected to the inlet of the first turbine 12.

One track of valve V2 is connected to the outlet of the second turbine 12 ', another track is connected to the inlet of the first turbine 12, another track is connected to the outlet of working fluid, Sf 11 of l exchanger 11.

One channel of the valve V3 is connected to the outlet of the pump 14, another channel is connected to the working fluid inlet Et 11 of the exchanger 11, another track is connected to the working fluid outlet Sf13 of the exchanger 13, another channel is connected to the inlet of the pump 14.

The on-off valve 20 is a four-way valve, with a path connected to the outlet of the first turbine 12, a path connected to the inlet of the second turbine 12 ', a path connected to a second inlet Ef11b of working in the exchanger 11 and a channel connected to a second outlet Sf 11 b of working fluid in the exchanger 11.

More specifically, the thicker lines representing the portions of the circuit in which working fluid circulates, in conventional mode (FIG. 11):

- The three-way valve V1 puts the output of the second turbine 12 'in communication with the working fluid inlet, And 13 of the exchanger 13, and condemns the communication with the inlet of the first turbine 12;

- The three-way valve V2 communicates the working fluid outlet Sf 11 of the exchanger 11 with the inlet of the first turbine 12 and condemns the communication with the outlet of the second turbine 12 ’;

- The four-way distributor valve V3 communicates the output of the compressor 14 with the working fluid inlet, Et 11, of the exchanger 11 as well as the working fluid outlet, Sf 13, of the exchanger 13 with the input of compressor 14.

the valve 20 places the output of the first turbine 12 in communication with the second inlet Ef11b of working fluid in the exchanger 11 to produce the second overheating and places the second outlet Sf11b of working fluid in communication with the inlet of the second turbine 12 '.

In “heat pump” mode (FIG. 12), the circulation of the working fluid is reversed in part of the loop 10. However, keeping the same references for the inputs / outputs of the exchangers 11, 13 as those in the figure. 11:

- The three-way valve V1 communicates the input Ef13 of the exchanger 13 with the input of the first turbine 12,

- The three-way valve V2 communicates the output of the second turbine 12 'with the first output, Sf11 of the exchanger 11, and blocks communication with the input of the first turbine 12;

- The four-way distributor valve V3 communicates the output of the compressor 14 with the output Sf 13 of the exchanger 13 as well as the input Ef11 of the exchanger 11 with the input of the compressor 14.

the valve 20 puts the output of the first turbine 12 into communication with the input of the second turbine 12 ', which are then associated in series, and condemns the second passage of the working fluid through the exchanger 11, from the outlet of the first turbine 12 and the second inlet Ef11b of the exchanger 11, towards the inlet of the second turbine 12 'from the second outlet Sf 11b of the exchanger 11.

FIGS. 13 and 14 show another architecture of a reversible heat exchange loop 10, respectively in the conventional mode and in the heat pump mode. In this architecture, the evaporation and the overheating are carried out, in the conventional mode (FIG. 13), in a dedicated exchanger, the evaporation in the exchanger 11 and the second overheating in the exchanger 11 ', while a only turbine 12 is used. The fluid having undergone the second overheating is reintroduced into the same turbine.

In this architecture:

One track of the valve V1 is connected to the outlet of the turbine 12, another track is connected to the working fluid inlet, Ef 13 of the exchanger 13, another track is connected to the inlet of the turbine 12.

One track of the valve V2 is connected to the outlet of the turbine 12, another track is connected to the inlet of the turbine 12, another track is connected to the outlet of working fluid, Sf 11 of the exchanger 11 .

One channel of the valve V3 is connected to the outlet of the pump 14, another channel is connected to the working fluid inlet Ef 11 of the exchanger 11, another track is connected to the working fluid outlet Sf13 of the exchanger 13, another channel is connected to the inlet of the pump 14.

The on-off valve 20 is a two-way valve, with a path connected to the outlet of the turbine 12 upstream of the communication with the valve V1 and a path connected to the inlet of the second exchanger 11 ’.

More specifically, the thicker lines representing the portions of the circuit in which the working fluid circulates, in conventional mode (FIG. 13):

- The three-way valve V1 communicates the outlet of the turbine 12 with the working fluid inlet, Ef 13 of the exchanger 13, and condemns the communication with the inlet of the turbine 12;

- The three-way valve V2 communicates the working fluid outlet Sf 11 of the exchanger 11 with the inlet of the turbine 12 and condemns the communication with the outlet of the turbine 12;

- The four-way distributor valve V3 communicates the output of the compressor 14 with the working fluid inlet, Ef 11, of the exchanger 11 as well as the working fluid outlet, Sf 13, of the exchanger 13 with the input of compressor 14.

- the valve 20 communicates the outlet of the turbine 12 with the working fluid inlet of the second exchanger 11 ’.

In "heat pump" mode (figure 14), the circulation of the working fluid is reversed. However, keeping the same references for the inputs / outputs of the exchangers 11, 13 as those in FIG. 13:

- The three-way valve V1 communicates the input Ef13 of the exchanger 13 with the input of the first turbine 12,

- The three-way valve V2 communicates the outlet of the turbine 12 with the outlet, Sf 11 of the exchanger 11, and condemns the communication with the inlet of the turbine 12;

- The four-way distributor valve V3 communicates the output of the compressor 14 with the output Sf 13 of the exchanger 13 as well as the input Ef11 of the exchanger 11 with the input of the compressor 14.

- the valve 20 cuts the communication between the outlet of the turbine 12 and the working fluid inlet of the second exchanger 11 ’.

FIGS. 15 and 16 show another architecture of a reversible heat exchange loop 10, respectively in the conventional mode and in the heat pump mode. In this architecture, the evaporation and the overheating are carried out in the conventional mode (FIG. 15) within the same exchanger, for example, the exchanger 11, where the circulation of the working fluid is split and is carried out by example against the current of the circulation carrying out the first evaporation. In this architecture again, a single turbine 12 is used. The fluid having undergone the second overheating is reintroduced into the same turbine.

In this architecture:

One track of valve V1 is connected to the outlet of the turbine 12, another track is connected to the working fluid inlet, And 13 of the exchanger 13, another track is connected to the inlet of the turbine 12.

A channel of the valve V2 is connected to the outlet of the turbine 12, another channel is connected to the inlet of the turbine 12, another channel is connected to the first outlet of working fluid,

Sf 11 of exchanger 11.

One channel of the valve V3 is connected to the outlet of the pump 14, another channel is connected to the first working fluid inlet Et 11 of the exchanger 11, another track is connected to the working fluid outlet Sf 13 of the exchanger 13, another channel is connected to the inlet of the pump 14.

The on-off valve 20 is a two-way valve, with a way connected to the outlet of the turbine 12, upstream of the communication with the valve V1, and a way connected to the second inlet Et 11b of the exchanger 11 .

More specifically, the thicker lines representing the portions of the circuit in which the working fluid circulates, in conventional mode (FIG. 15):

- The three-way valve V1 communicates the outlet of the turbine 12 with the working fluid inlet, And 13 of the exchanger 13, and condemns the communication with the inlet of the turbine 12;

- The three-way valve V2 communicates the first working fluid outlet Sf 11 of the exchanger 11 with the inlet of the turbine 12 and condemns the communication with the outlet of the turbine 12;

- The four-way distributor valve V3 communicates the output of the compressor 14 with the first working fluid inlet Ef 11 of the exchanger 11 as well as the working fluid outlet, Sf 13, of the exchanger 13 with the input of compressor 14;

- the valve 20 communicates the outlet of the turbine 12 with the second inlet Ef 11 b of the working fluid of the exchanger 11.

In this configuration, only part of the working fluid, that circulating in the exchanger 11 having entered via the second inlet Ef11b, undergoes the second overheating before returning to the turbine 12.

In "heat pump" mode (figure 16), the circulation of the working fluid is reversed. However, keeping the same references for the inputs / outputs of the exchangers 11, 13 as those in FIG. 15:

- The three-way valve V1 communicates the inlet Ef13 of the exchanger 13 with the inlet of the turbine 12,

- The three-way valve V2 communicates the outlet of the turbine 12 with the outlet, Sf 11 of the exchanger 11, and condemns the communication with the inlet of the turbine 12;

- The four-way distributor valve V3 communicates the output of the compressor 14 with the output Sf 13 of the exchanger 13 as well as the input Ef11 of the exchanger 11 with the input of the compressor 14;

- the valve 20 cuts the communication between the outlet of the turbine 12 and the second inlet Ef 11 b of the working fluid of the exchanger 11.

Double evaporation makes it possible both to increase the thermal efficiency of the thermodynamic cycle and to overcome reliability problems due for example to the erosion of the blades of the turbine by the impact of liquid droplets animated by a high speed, without resorting to expensive components which resist these difficulties, or additional components (for example, setting up of an overheating of the vapor and / or a subcooling of the liquid).

The engine assembly of the invention provides an architecture which makes it possible to valorize the heat losses in the heat transfer circuit and of recirculated exhaust gases from the internal combustion engine of a conventional or hybrid powertrain while having the advantage not to have an impact on the reduction of polluting emissions and the priming of pollution control devices: the enrichment of their design (grammage in precious metals, approximation of the engine output) is not necessary.

With this architecture, the energy contained in the heat transfer circuit is certainly at an exergy level (taking into account the temperature level) lower than in the exhaust gases but is, by the levels of thermal capacities implemented , more available and less dependent on the load level of the traction chain.

Relative to an architecture with a Rankine loop with the exhaust gases as for hot source, the architecture of the invention presents a more favorable operating safety, a less constrained physical installation and without expensive developments and validations.

This architecture is also adaptable to hybrid-electric powertrains, which allows the components to be shared.

Claims (7)

Claims 1. Motorization set including: - an internal combustion engine (1) equipped with a cooling circuit intended to receive a coolant, a Rankine loop (10) using a working fluid and comprising heat exchange means (11, 11 d between the working fluid and the coolant of the cooling circuit using this cooling circuit as a hot source, and expansion means (12, 12 ') able to transform energy from the expansion of the working fluid into mechanical energy, characterized in that the expansion means (12, 12') and the heat exchange means (11, 11 j are fluidly connected so that the thermodynamic cycle of at least part of the working fluid of the Rankine loop (10) comprises an evaporation step followed by a first overheating, followed by a first trigger, followed by a second overheat, followed by a second trigger. 2. Motor assembly according to claim 1, characterized in that the stages of evaporation and overheating are carried out through a single exchanger (11) with separate dual circulation of working fluid. 3. Motor assembly according to claim 1, characterized in that the evaporation and the first overheating take place through a first heat exchanger (11) and the second overheating through a second heat exchanger (11 d, the first and the second heat exchanger (11, 11 j being arranged at different locations in the cooling circuit. 4. Motorization assembly according to claim 2 or claim 3, characterized in that the evaporation and the first overheating take place through a heat exchanger (11) arranged fluidly, relative to the direction of circulation of the coolant within of the cooling circuit, downstream of a cooling exchanger (5) of the recirculated exhaust gases towards the engine intake (1). 5. Motor assembly according to any one of the preceding claims, characterized in that the first expansion and the second expansion are carried out by common expansion means (12). 6. Motorization assembly according to any one of claims 1 to 4, characterized in that the first expansion and the second expansion are effected by expansion means (12, 12 separate j. Ί. Motorization assembly according to one of the preceding claims, characterized in that the Rankine loop (10) comprises valves (V1, V2, V3) and means for controlling these valves, these valves being arranged so that in a first mode of operation, the heat exchange means (11, 11 d between the 5 working fluid and the coolant of the cooling circuit of the heat engine (1) use this cooling circuit as a hot source, and in a second operating mode, the heat exchange means (11, 11 j between the fluid working fluid and coolant in the engine cooling circuit (1) use this cooling system as a cold source. 10 8. Motor assembly according to one of the preceding claims, characterized in that the Rankine loop (10) comprises a valve (20) and means for controlling this valve, this valve being arranged so that in a first operating mode, the circulation of the working fluid in the heat exchange means for the second overheating is authorized and in a second mode of 15 operation, this circulation is prohibited. 9. Vehicle, characterized in that it is equipped with a motor assembly according to any one of the preceding claims. 1/7 FA " 13