WO2018069587A1

WO2018069587A1 - Drive unit with rankine loop

Info

Publication number: WO2018069587A1
Application number: PCT/FR2017/052371
Authority: WO
Inventors: Ludovic Lefebvre; Mouad Diny
Original assignee: Psa Automobiles Sa
Priority date: 2016-10-11
Filing date: 2017-09-07
Publication date: 2018-04-19
Also published as: FR3057299B1; FR3057299A1

Abstract

The invention relates to a drive unit which comprises: an engine (1) provided with a liquid cooling circuit, a Rankine loop using a working fluid with an exchanger (11) between the fluid and the liquid as a heat source, means for cooling recirculated exhaust gases from the engine including a liquid inlet (E5) connected to the outlet of the inner circuit (2), and a liquid outlet (S5) connected to the liquid inlet (E11) of the exchanger (11), characterised in that the circuit comprises a thermostatic device (6) comprising: an inlet (E6) for liquid from the liquid outlet (S5) of the exchanger (5) for cooling recirculated exhaust gases, a first outlet (S61) connected to the liquid inlet (E11) of the exchanger (11), and a second outlet (S62) connected to an inlet (E7) of a pipe (7) for returning liquid to the engine (1).

Description

MOTORIZATION ASSEMBLY WITH RANKINE LOOP

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

Economic (fuel price) and environmental (pollutant and greenhouse gas) pressures are driving the current trend towards the development of ever-improving performance chains.

Hybrid-electric vehicles provide a first answer. 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 period and / or a distance away from the heat engine in order to inhibit any pollutant emission or to increase the performance of the engine by providing additional torque or mechanical power,

and a tensile energy storer, in the form of super-capacitors or a high-voltage traction battery consisting of at least one module gathering an array of cells associated in series and / or in parallel with each other; compared to others, whatever the technology: families Li-ion, Ni-MH, Ni-Cd, ...

In the field of thermal engines also, for example of internal combustion type, research is developing constantly to improve performance. 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 on the operating points of greater efficiency, the total energy contained in the fuel is distributed between approximately and in order of magnitude:

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

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

- 35% in the exhaust. This status describes the distribution of energy flows on the operating points of best performance. In actual 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 while its engine is running at idle speed.

With the example of FR2868809B1, FR3028885A1 or US2015 / 377180A1, improvement ways 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 the exhaust gases into mechanical or thermal energy. The implementation of the Rankine thermodynamic cycle with the 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 (eg Diesel) and for hybrid-electric powertrains (eg in the case where the combustion engine is stopped or when the combustion engine is used on operating points with better efficiency) than for spark-ignition engines (eg indirect or direct fuel injection, LPG, etc.) because of a lower exhaust gas temperature.

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

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 weight or locomotives, for example : the cycles of use are much more transient and with points of operation mostly in areas of partial load and low load, therefore with temperature and exergy levels available on the lower exhaust gases. In the case of the use of the exhaust gases as a hot source of the Rankine cycle again, the temperature and pressure levels in the Rankine loop constrain all the design and sizing of the associated components: evaporator, condenser , turbine, etc. and therefore the cost of the system.

Finally, the use of the 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 back-pressure and degrades the engine. the intrinsic efficiency of the engine, thus contributing to the implementation of a short-circuit conduit and a valve of short circuit of the evaporator by the exhaust gas. The use of the exhaust gas as a hot source of the Rankine cycle also requires the passage of the working fluid in the underbody environment from the hood environment and the front of the vehicle and generates the risk of ignition flammability. 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 avoiding the problems due to the use of the exhaust gases as that hot source of the Rankine cycle.

To achieve this objective, it is provided according to the invention an engine assembly motorization assembly comprising:

an internal combustion engine (1) equipped with a cooling circuit for receiving a cooling liquid, a part (2) of this cooling circuit being internal to said engine (1),

a Rankine loop using a working fluid and comprising a heat exchanger (11) said to be hot between the working fluid and the coolant of the cooling circuit as a hot source,

recirculated exhaust gas cooling means of the engine comprising an inlet (E5) of coolant connected to the outlet of the internal circuit (2) and a coolant outlet (S5) connected to the inlet (E1) 1) coolant of the heat exchanger (1 1) hot.

characterized in that the cooling circuit comprises a thermostatic device comprising:

a coolant inlet from the recirculated exhaust gas heat exchanger coolant outlet. a first outlet fluidly connected to the coolant inlet of the so-called hot exchanger,

- A second output fluidly connected to an inlet of a return line of the coolant to the engine.

The technical effect is to recover the energy contained in the heat transport circuit, certainly at a level of exergy (taking into account the temperature level) lower than in the exhaust gases (yet then at a substantially identical energy level ) but is, by the thermal capacity levels implemented, more available and less dependent on the load level of the engine while also allowing a transmission to the working fluid of the Rankine loop of the calories dissipated by the exhaust gas recirculated through the recirculated exhaust gas cooling means. Various additional features may be provided, alone or in combinations:

Advantageously, the thermostatic device is designed so that:

for a coolant temperature below a temperature threshold for which it is judged that the heat transferable through the so-called hot exchanger is too low to take advantage of the Rankine loop, the thermostatic device prevents the flow of liquid from cooling through the so-called hot exchanger by closing its first outlet and allowing the circulation of coolant in the return line by opening its second outlet,

- For a coolant temperature above this temperature threshold, the thermostatic device prevents the circulation of coolant in the return pipe by closing its second outlet and allows the circulation of coolant through the so-called hot exchanger by opening his first exit.

Advantageously, the cooling circuit comprises a loop comprising a radiator and a thermostat designed to allow the circulation of the cooling liquid in the loop comprising this radiator when the temperature of the coolant is greater than a control temperature threshold of the engine, the temperature threshold for which it is judged that heat transferable through the so-called hot exchanger is too low to take advantage of the Rankine loop being below the engine control temperature threshold. Advantageously, the motor assembly comprises a heater comprising a coolant inlet connected to the outlet of the internal circuit and a coolant outlet connected to the coolant inlet of the so-called hot exchanger, the heater and said hot exchanger being connected in parallel or series in this order, relative to the direction of circulation of the coolant, in the cooling circuit.

Advantageously, the thermostatic device is an electrically controlled thermostat or an electrically controlled solenoid valve as a function of the temperature of the coolant, the heater and the recirculated exhaust gas cooling means.

Advantageously, the drive assembly comprises a second cooling circuit for receiving a coolant, independent of the engine cooling circuit, and the Rankine loop comprises a so-called cold exchanger between the working fluid and the coolant of this engine. second cooling circuit as a cold source. Advantageously, the drive assembly comprises a turbocharger and a cooler of the compressed air by the turbocharger, this cooler being disposed in parallel with the so-called cold exchanger in the second cooling circuit.

Advantageously, the recirculated exhaust gas cooling means of the engine comprises a passage of the exhaust gas recirculated internally of the internal combustion engine and / or is integrated wholly or partly into an exhaust manifold integrated into a cylinder head. this engine.

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

Other features and advantages will appear on reading the following description of a particular embodiment, not limiting of the invention, 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 a schematic representation of the first embodiment of the invention for a second operating state.

- Figure 3 is a schematic representation of the first embodiment of the invention for a third operating state.

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

- Figure 5 is a schematic representation of the second embodiment of the invention in the second operating state.

- Figure 6 is a schematic representation of the second embodiment of the invention in the third state of operation.

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

The motor assembly includes a heat engine 1. The heat engine 1 may for example be a spark ignition internal combustion engine or a compression ignition internal combustion engine. Such an engine assembly preferably equips a vehicle, in particular an automobile, 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 circulates a cooling liquid, such as a mixture of water and mono-ethylene glycol, for example.

The cooling circuit comprises an internal circuit for circulating the coolant inside the engine. The cooling circuit is intended to take the calories generated by the engine and to evacuate them to maintain the 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 flow of the coolant. The heat engine 1 is connected at the output S2 of the internal circuit 2 to an inlet E31 of a casing 3 for the outlet of the cooling liquid. The housing 3 is intended to distribute the cooling liquid inside various branches of the cooling circuit. The housing 3 comprises a first outlet S31 of coolant fluidically connected, for example by means of a pipe, to an inlet E4 of a heater 4. The heater 4 is traversed by an internal air flow and / or external which is intended to be delivered inside a passenger compartment of the motor vehicle to heat an air present inside the passenger compartment. The heater 4 is preferably housed inside a heating system of the vehicle. The heater comprises an outlet S4 of coolant fluidically connected, for example by means of a pipe, to an inlet E5 of an exchanger 5, also called EGR exchanger, cooling the exhaust gas recirculated to the inlet of the engine 1. In this embodiment, the heater 4 and the EGR exchanger 5 are in series in this order. The recirculated exhaust gases can be taken either upstream or downstream of exhaust gas cleaning devices (high pressure exhaust gas recirculation, known as HP EGR or low pressure exhaust gas recirculation, called BP EGR according to that the sampling is respectively upstream or downstream of the pollution control organs, the upstream and downstream direction being defined here relative to the direction of circulation of the exhaust gas). Alternatively, the EGR exchanger 5 can be supplemented or replaced by an exhaust manifold integrated with the cylinder head or by a passage of the exhaust gas recirculated internally of the engine, for example within the cylinder head. The cooling circuit further comprises a thermostatic device 6 comprising an inlet E6 of coolant fluidically connected, for example by means 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 output, S62, of coolant. The thermostatic device 6 distributes the coolant according to its temperature to the outputs S61 and / or S62.

The housing 3 comprises a second outlet S32 of coolant fluidically connected, for example by means of a pipe 7 to an inlet E8 of a coolant pump. The coolant pump 8 comprises an output S8 connected to an input E2 of the internal circuit 2 to the heat engine 1. Line 7 is a line for direct return of coolant to the internal circuit 2 of the engine 1 via the pump 8 (typically designated bypass in English). The line 7 ensures a minimum flow rate within the heat engine 1 which would be dissatisfied by the circulation of coolant within the only heater 4 and EGR exchanger 5. The housing 3 comprises a third outlet S33 of coolant fluidically connected , for example by means of a pipe, at an inlet E9 of a radiator 9. The radiator 9 is traversed by an external air flow to cool the cooling liquid inside the radiator 9. The radiator is preferentially 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 further comprises a thermostat 19, which can be piloted and whose function is to distribute the coolant according to its temperature to the outputs S32, S33. The radiator 9 comprises an outlet S9 of coolant fluidically 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 of liquid 3. The motorization assembly of the invention further comprises an energy recovery device implementing a Rankine cycle. This energy recovery device comprises a heat exchange loop 10 inside which circulates a working fluid. A heat exchanger 1 1 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 carried by the coolant to transfer them to the working fluid. This heat exchanger 1 1 is said to be hot because it is connected to the hot source. This heat exchanger 1 1 preferably constitutes an evaporator for the working fluid, such that the latter changes from a liquid state at the inlet of the heat exchanger 11 to a vapor state at the outlet of the heat exchanger 11. .

From the heat exchanger 1 1, in a flow direction of the fluid inside the heat exchange loop 10, it further comprises:

- An expansion member 12, also called turbine or expander, capable of converting energy from the expansion of the working fluid into mechanical energy. Inside the expansion member 12 the fluid undergoes a relaxation that lowers the temperature and pressure of the working fluid. - A heat exchanger 13 said cold because it is thermally connected to a cold source. This heat exchanger 13 is preferably a condenser 13 inside which the working fluid condenses by yielding its heat at substantially constant pressure to the cold source, and

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.

The mechanical energy thus produced from the thermal energy released by the expansion of the working fluid can then be directly communicated by at least one disengageable gear gear, at the output of the crankshaft of the heat engine, or preferably converted by a generator or alternator in electrical energy

- 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 an alternator of a conventional or micro-hybridized traction chain (for example of the stop and start type). where the alternator is usually driven by the engine.

The so-called hot heat exchanger 1 1 comprises an inlet E 1 1 of cooling liquid fluidly connected to the first outlet S61 of the thermostatic device 6. The heat exchanger 1 1 is thus fluidly connected to the cooling circuit of the heat engine 1. the air heater branch of this circuit, at the outlet of the EGR exchanger 5 which is associated in series with it via the first output S61 of the thermostatic device 6. The heat exchanger 1 1 also comprises an outlet S1 1 of liquid from cooling fluidically connected to an inlet E7 of the pipe 7 connecting the housing 3 to the pump 8.

The second output, S62, of the thermostatic device 6 is also fluidly connected to the inlet E7 of the pipe 7.

The so-called cold heat exchanger 13 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 circulates a cooling liquid, 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 traversed by an external air flow to cool the cooling liquid inside the radiator 16. The radiator is preferably housed at the interior of a front facade of the motor vehicle to facilitate a heat exchange between the external air flow and the coolant inside the radiator 16, and preferably upstream or in parallel of the radiator 9 account-held the direction of flow of the external air flow from the outside environment to the front of the vehicle to the environment of the under-bonnet of the vehicle. In this variant, the cold exchanger 13 is a condenser of indirect or water type. It may then comprise in particular: a reservoir of working fluid, 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 subcooler, subjected to a coolant flow rate of the second cooling circuit and which ensures a heat exchange between the working fluid and the cooling liquid of the second circuit, in order to bring the working fluid to a temperature below its condensation temperature. This arrangement makes it possible to guarantee that the working fluid is totally in the liquid phase at the inlet of the pump or of the compressor 14 in order to overcome any risk of cavitation which can cause the deterioration or the 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 coolant that includes the exchanger 13 cold. The cold exchanger 13 further comprises an outlet S13 of coolant.

The engine may further comprise 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 their pressure drops.

In a variant, the cold exchanger 13 is a direct or air type condenser, preferentially housed inside a front facade of the motor vehicle to facilitate a heat exchange between the external air flow and the fluid. working inside the exchanger 13 cold, and preferably upstream or in parallel with the radiator 9 given the direction of flow of the external air flow.

The operation is as follows: In the configuration illustrated in FIG. 1, the heat engine 1 is in a 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 transiently cut off, either at the level of the pump 8, or at the level of the housing 3, to accelerate the temperature rise of the heat engine 1), it takes place within the internal circuit 2 of the heat engine 1 and then opens at the input E31 of the housing 3. thermal engine 1 has not yet reached its regulation temperature and its thermostat 19 closes the output S33. Preferably, for an acceptable operation of the engine 1, the control temperature, corresponding to the temperature of the coolant causing a start of opening of the thermostat 19, is preferably between 75 and 105 ° C. With the thermostat 19 closed, the engine output coolant flows through the outlet S31 of the housing 3 to the heater 4 and the EGR exchanger 5 and through the outlet S32 of the housing 3 through the pipe 7 before being sucked by the inlet E8 of the water pump 8 and to be discharged at the inlet E2 of the heat engine 1. The temperature of the coolant irrigating the thermosensitive element of the thermostatic device 6 is less than a predefined threshold, Sr, for which it is judged that the temperature and heat transferable through the exchanger 11 are too low to take advantage of the Rankine loop and the priority is given to the temperature rise of the heat engine 1 and the heating of the cabin, via the heater 4. The preset threshold, Sr, is lower than the control temperature and preferably between 40 and 70 ° C.

The thermostatic device 6 disposed at the outlet of the exchanger 5 EGR closes the first outlet S61 to prevent the circulation of the cooling liquid in the exchanger 11, said to be hot, but leaves the second outlet S62 open.

The coolant having passed through the exchanger 5 EGR is directed by the second outlet S62 of the thermostatic device 6 to the pipe 7 and the inlet of the water pump 8. The Rankine loop is then deactivated: the fluid pump or compressor 14 and the detent 12 are here inoperative.

The so-called cold exchanger 13 of the Rankine loop is irrigated by the coolant of the second cooling circuit if the associated pump 15 is activated. An alternative possible to dispense with the circulation of coolant in the second cooling circuit and therefore within the exchanger 13 said cold, unnecessary since the Rankine loop is then disabled. This flow of coolant within the exchanger 13 said cold then inoperative however allows conduction to put it at a temperature already conducive to ensure rapid availability of the cold source.

FIG. 2 shows the first embodiment in a second operating phase in which the heat engine 1 is always in a transient thermal regime, in a second phase of temperature rise.

In this second phase, the heat engine has not yet reached its control temperature and its thermostat 19 keeps the output S33 closed. However, in this second phase, the convergence phase of the cabin thermal comfort in heating mode is complete and the temperature and heat transferable through the heat exchanger 11 are now sufficient to take advantage of the Rankine loop: the Rankine loop is then activated and the pump 14 and the detent 12 now work.

As the temperature of the coolant irrigating the thermosensitive element of the thermostatic device 6 is 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. to the pipe 7, but leaves the first outlet S61 open to allow the passage of the coolant in the exchanger 1 1 said hot.

The coolant having passed through the exchanger 5 EGR is directed by the first outlet S61 of the thermostatic device 6 to the exchanger 1 1, which it passes through before rejoining the pipe 7 and the inlet of the pump 8. At the crossing the exchanger 1 1, the engine output coolant, having eventually yielded a portion of its calories to the passenger compartment air through the heater 4 and then heated to the crossing of the exchanger 5 EGR and optionally the valve EGR, not shown, transfers calories through the exchanger 1 1 to the working fluid of the Rankine loop, thereby increasing the temperature before expansion through the trigger member 12. This arrangement, where the heater 4, the exchanger 5 EGR and the exchanger 1 1 are arranged in series and in this order in view of the flow direction of the engine output coolant, makes it possible to compensate for the calories dissipated by the recirculated gases the calories possibly lost when passing through the heater 4 and to transmit to the working fluid the calories dissipated by the recycled gases at the crossing of the exchanger 5 EGR. Preferably, the thermostatic device 6 is of piloted type: an electric element controlled by a vehicle computer is integrated with the thermostatic device 6 and makes it possible to cause its opening at a temperature of the coolant different from its start threshold of passive opening. The actuation of the thermostatic device 6 is implemented by a control law stored in a memory space of the computer, depending in particular on the temperature of the coolant at the output of the heat engine, the heater 4 and the heat exchanger 5 EGR. Alternatively, the thermostatic device 6 may be replaced by a solenoid valve actuator on / off or proportional, for example solenoid. The temperature of the coolant at the outlet of the heater 4 is estimated from the temperature of the coolant at the outlet of the engine 1, the rotational speed of the engine 1 and the known input data of the regulating function interior passenger comfort, such as the outside ambient temperature, the speed of rotation of the air blower in the passenger compartment, the position of the air distribution flaps through the air conditioning unit of the vehicle, the inlet air temperatures and at the output of the heater 4 and the set temperature of the air in the passenger compartment. Indeed, in certain situations, in particular when the temperature of the coolant at the output of the heat engine 1 is greater than a given temperature and the heater does not cool or cool the coolant, the temperature of the output coolant of the heater 4 is then very little lower than its temperature output of the engine 1.

Similarly, in the context of the present cooling circuit architecture where the heater 4 and the exchanger 5 EGR are arranged in series and in this order taking into account the flow direction of the engine output coolant, the temperature the coolant at the outlet of the exchanger 5 EGR is estimated from the coolant temperatures at the outlet of the heat engine 1 and the heater 4, the recirculation rate of the recirculated exhaust gas (for example via the 'opening of the recirculated exhaust gas metering valve), the operating point of the engine (rotation speed and load), the inlet temperature downstream and upstream of the recirculated exhaust gas inlet in the intake circuit, for example just upstream of the combustion chambers, and the temperature of the exhaust gas estimated or measured at the place of sampling of the recirculated exhaust gas.

The computer then controls the electrical actuation of the thermostatic device 6, or alternatively the solenoid valve, to allow the passage of the heat exchanger 1 1 through the cooling liquid at the outlet of the heater 4 and the exchanger 5 EGR .

FIG. 3 shows the first embodiment for a third operating phase in which the heat engine 1 is in an established thermal regime. In this third phase, the thermal engine 1 has reached its control temperature and its thermostat 19 is in regulation (open-opening) or in full opening.

In low opening, the thermostat 19 directs to the radiator 9 a small portion of the coolant flow from the heat engine 1. The housing 3 is designed so that the flow of coolant from the engine 1 directed towards the circuit heater 4 is independent of the position of the thermostat 19 for a given engine speed. The remainder of the coolant flow from the heat engine 1 is thus directed by the internal channel S34 of the housing 3 to the second outlet S32 and the pipe 7 and the pump 8.

As the opening of the thermostat 19 increases, the internal channel S34 of the housing 3 to the pipe 7 closes: as a result, the proportion of coolant from the radiator 9 in the pipe 7 increases. Conversely, as the thermostat 19 closes, the inner channel S34 of the housing 3 to the pipe 7 reopens: the proportion of coolant from the radiator 9 in the channel 7 then decreases accordingly.

In full opening, the thermostat 19 directs towards the radiator 9 the entire flow of coolant from the heat engine 1 has not been directed, by the design of the housing 3, to the air heater circuit 4. The internal path S34 of case 3 is then completely closed and the entire flow of coolant from the radiator 9 is directed through the second outlet S32 of the housing to the pipe 7 and the pump 8. On its side, the thermostatic device 6 maintains the first output S61 open and the second output S62 closed, preferably without it being necessary to activate the power supply: the engine output coolant directed in the heater 4 passes therethrough and then the exchanger 5 EGR before irrigating the exchanger 1 1 and give up its heat.

The pump 8 draws through its inlet E8 the cooling liquid at the outlet of the pipe 7 and exchangers (radiator 9, heater 4, exchanger EGR 5, exchanger 1 1) and delivers it to the inlet E2 of the heat engine 1.

FIG. 4 now shows a second embodiment of the invention which differs from the first embodiment in that the heater 4 and the exchanger 5 EGR are arranged in parallel at the output of the heat engine 1. FIG. 4 also shows the configuration in which the heat engine 1 is in a transient thermal regime, in the first phase of temperature rise.

In this second embodiment, the inlet E6 of the thermostatic device 6 for cooling liquid is connected fluidly, for example by means of a pipe, to the outlet S5 of the exchanger 5 EGR. The first output, S61, of the thermostatic device 6 is connected to the input E1 1 of the exchanger 1 1 while the second output, S62 is fluidly connected to the pipe 7. The output S4 of the heater joins the fluidic connection from the second exit S62 to the pipeline 7.

As illustrated in FIG. 4, in a transient thermal regime, while the heat engine is in a temperature increase phase and the temperature of the cooling liquid irrigating the thermosensitive element of the thermostatic device 6 is less than the predefined threshold Sr for which it is judged that the temperature and heat transferable through the exchanger 11 are too weak to take advantage of the Rankine loop, the priority is given to the temperature rise of the engine 1 and the heating of the passenger compartment, via the heater 4. The Rankine loop is then disabled: the fluid pump or compressor 14 and the expansion member 12 are here inoperative. The coolant at the outlet of the engine 1 passes through the heater 4 and the exchanger 5 EGR arranged in parallel with each other. The thermostatic device 6 disposed at the outlet of the exchanger 5 EGR keeps the first outlet S61 closed and directs the cooling liquid having passed through the exchanger 5 EGR towards the second outlet S62 towards the duct 7 which leads to the pump 8. exchanger 1 1 is not then traversed by the coolant from the exchanger 5 EGR. FIG. 5 now shows the second embodiment in the second phase of operation in which the heat engine 1 is always in a transient thermal regime, in a second phase of temperature rise. In this second phase, the heat engine has not yet reached its control temperature and its thermostat 19 keeps the output S33 closed.

However, in this second phase, the convergence phase of the cabin thermal comfort in heating mode is complete and the temperature and heat transferable through the heat exchanger 11 are now sufficient to take advantage of the Rankine loop: the Rankine loop is then activated and the pump 14 and the detent 12 now work.

In this second phase, the temperature of the coolant irrigating the thermosensitive element of the thermostatic device 6 being greater than the preset threshold Sr, the thermostatic device 6 disposed at the outlet of the exchanger 5 EGR closes the second outlet S62 to prevent the return of the coolant at the outlet of the exchanger 5 EGR directly to the pipe 7 and leaves the first outlet S61 open to allow the passage of the coolant at the outlet of the exchanger 5 EGR in the exchanger 1 1 said hot.

At the crossing of the exchanger 1 1, the engine output coolant, heated to the crossing of the exchanger 5 EGR and optionally the recirculated exhaust gas metering valve, yields calories through the exchanger 1 to the working fluid of the Rankine loop, thereby increasing the temperature and pressure before the expansion through the member 12 of relaxation.

This series arrangement of the exchanger 5 EGR and the exchanger 1 1, in this order in view of the direction of circulation of the coolant at the engine output, and in parallel with the heater 4, makes it possible to transmit to the fluid of Rankine loop work the calories dissipated by the recirculated exhaust gas at the crossing of the 5 EGR heat exchanger while avoiding thermal losses through the unit heater 4.

FIG. 6 now shows the second embodiment in the third operating phase in which the heat engine 1 is in an established thermal regime. In this third phase, the thermal engine 1 has reached its control temperature and its thermostat 19 is in regulation (open-opening) or in full opening. In low opening, the thermostat 19 directs to the radiator 9 a small portion of the coolant flow from the engine 1. The housing 3 is designed so that the flow of coolant from the heat engine 1 to the heating circuit 4 is independent of the position of the thermostat 19 for a given engine speed. The remainder of the coolant flow from the heat engine 1 is thus directed by the internal path of the housing 3 to the second outlet S32 and the pipe 7 and the pump 8. As the opening of the thermostat 19 increases, the path internal S34 of the housing 3 to the pipe 7 closes: as a result, the proportion of coolant from the radiator 9 in the pipe 7 increases. Conversely, as the thermostat 19 closes, the inner channel S34 of the housing 3 to the pipe 7 reopens: the proportion of coolant from the radiator 9 in the channel 7 then decreases accordingly.

In full opening, the thermostat 19 directs towards the radiator 9 the entire flow of coolant from the heat engine 1 has not been directed, by the design of the housing 3, to the air heater circuit 4. The internal path S34 of case 3 is then completely closed and the entire flow of coolant from the radiator 9 is directed through the second outlet S32 of the housing to the pipe 7 and the pump 8.

For its part, the thermostatic device 6 keeps the first output S61 open and the second output S62 closed: the engine output coolant directed into the exchanger 5 EGR passes through it before irrigating the exchanger 1 1 and it give up his heat. The coolant at the outlet of the exchanger 1 1 then joins the portion of engine output coolant having passed through the heater 4 upstream of the inlet E7 of the pipe 7.

The pump 8 draws through its inlet E8 the cooling liquid at the outlet of the pipe 7 and exchangers (radiator 9, heater 4, exchanger EGR 5, exchanger 1 1) and delivers it to the inlet E2 of the heat engine 1. In the context of the first and second embodiments of the invention, the thermostat 19 is preferably controlled, for example electrically, or alternatively, the device providing the thermal regulation of the internal combustion engine 1 is designed, in the two cases so as to promote the operation of the heat engine 1 at the highest possible coolant temperature, especially given the reliability of the engine 1. Thus, the temperature of the coolant at the output of the heat engine 1 and at the input of the heat exchanger 1 1, then greater for example by the action of the controlled thermostat 19, and the recovery in the coolant of the engine 1 calories from the exhaust gases recirculated through the exchanger EGR 5, used to increase the pressure and temperature of the working fluid of the Rankine loop at the outlet of the heat exchanger 1 1: the heat of the coolant the heat engine 1 at the input E1 1 of the exchanger 1 1 is yielded to the working fluid of the Rankine loop at a higher temperature and the efficiency of the Rankine cycle is increased.

The motorization unit of the invention proposes an architecture that makes it possible to evaluate the thermal losses in the heat transport circuit and the recirculated exhaust gases of the internal combustion engine of a conventional or hybrid traction chain while having the advantage to have no impact on the reduction of pollutant emissions and the priming of the depollution devices: the enrichment of their design (grammage in precious metals, approximation of the motor output) is not necessary.

With this architecture, the energy contained in the heat transport circuit is certainly at a level of exergy (taking into account the temperature level) lower than in the exhaust gases (yet at a substantially identical energy level) but is , by the thermal capacity levels implemented, more available and less dependent on the load level of the power train. The thermodynamic cycle thus adapted is thus more in line with the cycles of use of the automobile environment (private vehicle, light commercial vehicle, etc.) much more transient and with operating points mostly in partial load zones or low charge.

With respect to an architecture with a Rankine loop with the exhaust gases as for hot source, the architecture of the invention has a more favorable operating reliability, a less constrained physical implementation and without expensive developments and validations.

By avoiding the implementation of an evaporator (exchanger 1 1) on the exhaust line, the engine is spared a back pressure exhaust additional and therefore a source of degradation of its performance and performance, so in particular its specific consumption.

This architecture is also adaptable to hybrid-electric traction chains which allows a pooling of components.

Claims

claims

1. Motorization assembly comprising:

recirculated exhaust gas cooling means of the engine comprising an inlet (E5) of coolant connected to the outlet of the internal circuit (2) and a coolant outlet (S5) connected to the inlet (E1) 1) coolant of the heat exchanger (1 1) hot,

characterized in that the cooling circuit comprises a thermostatic device (6) comprising:

- a coolant inlet (E6) from the recirculated exhaust gas cooler outlet (S5) (S5).

a first outlet (S61) fluidly connected to the inlet (E1 1) of coolant of the exchanger (1 1), said to be hot,

- A second output (S62) fluidly connected to an inlet (E7) of a pipe (7) for returning the coolant to the engine (1).

Motor assembly according to Claim 1, characterized in that the thermostatic device (6) is designed so that:

for a coolant temperature below a temperature threshold (Sr) for which it is judged that the heat transferable through the so-called hot exchanger (1 1) is too low to take advantage of the Rankine loop, the device thermostatic (6) prevents the circulation of coolant through the heat exchanger (1 1) said hot by closing its first outlet (S61) and allows the circulation of coolant in the pipe (7) return by opening its second outlet (S62), - for a coolant temperature above this temperature threshold (Sr), the thermostatic device (6) prevents the circulation of cooling liquid in the return pipe (7) by closing its second outlet ( S62) and allows the flow of coolant through the heat exchanger (1 1) said hot by opening its first outlet (S61).

3. Motorization assembly according to claim 2, characterized in that the cooling circuit comprises a loop comprising a radiator (9) and a thermostat (19) adapted to allow the circulation of the coolant in the loop comprising the radiator (9). ) when the coolant temperature is greater than a motor control temperature threshold (1), the temperature threshold (Sr) for which it is judged that heat transferable through the heat exchanger (1 1) is hot is too weak to take advantage of the Rankine loop being below the engine control temperature threshold (1).

4. Motor assembly according to one of claims 1 to 3, characterized in that it comprises a heater (4) having an inlet (E4) of coolant connected to the output of the internal circuit (2) and an output coolant (S4) connected to the coolant inlet of the heat exchanger (1 1) said hot, the heater (4) and heat exchanger (1 1) said hot being connected in parallel or in series in this order, relative to the direction of circulation of the coolant, in the cooling circuit.

5. Motor assembly according to claim 4, characterized in that the thermostatic device (6) is an electrically controlled thermostat or electrically controlled solenoid valve depending on the temperature of the coolant, the heater (4) and means recirculated exhaust gas cooling.

6. Motorization assembly according to any one of the preceding claims, characterized in that it comprises a second cooling circuit for receiving a coolant, independent of the engine cooling circuit (1), and the Rankine loop comprises an exchanger (13) said cold between the working fluid and the cooling liquid of the second cooling circuit as a cold source.

7. Motorization assembly according to the preceding claim, characterized in that it comprises a turbocharger (17) and a cooler (18) of the compressed air by the turbocharger (17), the cooler (18) being arranged in parallel with the exchanger (13) is cold in the second cooling circuit.

8. Motorization assembly according to any one of the preceding claims, characterized in that the recirculated exhaust gas cooling means of the engine comprises a passage of the exhaust gas recirculated internally of the internal combustion engine (1) and / or is integrated wholly or partly into an exhaust manifold integrated with a cylinder head of this engine (1).

9. Vehicle characterized in that it is equipped with a motorization assembly according to any one of the preceding claims.