FR3057298A1 - 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, this cooling circuit comprising an inner part of said engine (1) between an inlet (E2) motor and an output (S2) engine, and a line (7) direct return of coolant to the input (E2) engine, - a Rankine loop using a working fluid and comprising a heat exchanger (11). ) between the working fluid and the coolant of the cooling circuit using this cooling circuit as a hot source, characterized in that the cooling circuit comprises a loop of coolant to heat exchanger (11) said hot fluidically connected to: - An output (S62) of the pipe (7), located closer to the output (S2) engine, - an inlet (E72) in the pipe (7).

Description

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

Extension request (s)

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

£> 4 / RANKINE LOOP MOTORIZATION KIT.

FR 3 057 298 - A1

The invention relates to a motor assembly comprising:

an internal combustion engine (1) equipped with a cooling circuit intended to receive a coolant, this cooling circuit comprising an internal part of said engine (1) between an engine inlet (E2) and an outlet (S2) engine, and a pipe (7) for direct return of coolant to the engine inlet (E2),

- a Rankine loop using a working fluid and comprising an exchanger (11) between the working fluid and the coolant of the cooling circuit using this cooling circuit as a hot source, characterized in that the cooling circuit comprises a coolant loop to exchanger (11) said to be hot, fluidly connected to:

- an outlet (S62) from the pipe (7), located closest to the engine outlet (S2),

- an inlet (E72) in the pipeline (7).

S4

E1®

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, thus contributing to the implementation of a short-circuit conduit 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, this coolant circuit comprising an internal part of said engine between an engine inlet and an engine outlet, and a pipe for direct return of coolant towards the motor input,

- a Rankine loop using a working fluid and comprising an exchanger between the working fluid and the coolant of the cooling circuit using this cooling circuit as a hot source, characterized in that the cooling circuit comprises a liquid loop cooling to said hot exchanger fluidly connected to:

- an outlet from the pipeline, located as close as possible to the engine outlet,

- an entry in the pipeline.

The technical effect is to recover 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 substantially identical energy level ) but is, by the levels of thermal capacities 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 gases recirculated through the recirculated exhaust gas cooling means.

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

Advantageously, the Rankine loop is arranged so as to be able to switch between the mode where the exchanger uses the cooling circuit of the heat engine as a hot source and a so-called heat pump mode where this same exchanger uses the cooling circuit of the heat engine. as a cold source.

Advantageously, the cooling circuit of the thermal engine comprises a device for distributing the flow rates of coolant integrated into the pipeline comprising an inlet for liquid from the pipeline, the outlet from the pipeline to the exchanger and another outlet in the pipeline to the engine inlet, the device comprising a first means for controlling the opening of the outlet towards the engine inlet and a second means for controlling the opening of the outlet towards the exchanger.

Advantageously, the first and / or the second opening control means are a thermostatic actuator, preferably of the piloted type, or a solenoid valve.

Advantageously, the first opening control means is also a pressostatic actuator designed to open said outlet if the pressure of the coolant upstream of the actuator, relative to the direction of circulation of the liquid, exceeds a determined threshold.

Advantageously, the first and the second opening control means are designed so that:

- for a coolant temperature below a temperature threshold for which it is judged that the heat transferable through the exchanger is too low to take advantage of the Rankine loop, the first opening control means prevents circulation the circulation of coolant in the return pipe to the engine inlet and the second opening control means prevents the circulation of coolant through the exchanger,

- for a coolant temperature above this temperature threshold, the first opening control means prevents circulation of the coolant circulation in the return line to the engine inlet and the second control means d opening allows circulation of coolant through the exchanger.

Advantageously, the cooling circuit comprises a loop comprising a radiator and a thermostat designed to authorize the circulation of the coolant in the loop comprising this radiator when the temperature of the coolant is above a temperature threshold for regulating the engine, the 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 being lower than the engine regulation temperature threshold.

Advantageously, the engine assembly is designed so as to choose to activate the Rankine loop in the mode where the exchanger uses the cooling circuit as a hot source when the coolant temperature is above the temperature threshold for which it is considered that the heat transferable through the exchanger is too low to take advantage of the Rankine loop.

Advantageously, the motor assembly is designed so as to choose to activate the Rankine loop in the heat pump mode when the coolant temperature is below the engine regulation temperature threshold and to allow the circulation of liquid. cooling through the exchanger by the second opening control means.

The invention also relates to a vehicle equipped with an engine assembly according to any of the variants described above.

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 an enlarged view of the coolant distribution device and its arrangement in the third operating state.

- Figures 8 and 9 are a schematic representation of a reversible Rankine loop.

Figure 1 shows an 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 housing 3 for the outlet of the coolant. The housing 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. The air heater 4 is crossed 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 fan heater 4 is preferably housed inside a vehicle heating installation. The air heater comprises an outlet S4 of coolant fluidly connected, by means for example of a pipe, to an inlet E5 of an exchanger 5, also designated EGR exchanger, for cooling the exhaust gases recirculated to the intake of the engine 1. In this embodiment, the air heater 4 and the EGR exchanger 5 are in series in this order. 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 of the internal combustion engine, for example within the cylinder head.

The housing 3 comprises a second outlet S32 of coolant fluidly connected, by means for example 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 EGR exchanger 5 includes an outlet S5 fluidly connected, for example by means of a pipe, to an inlet E71 of the pipe 7 connecting the housing 3 to the pump 8.

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 coolant inside the radiator 9. The radiator is preferably housed inside a front panel of the motor vehicle to facilitate an exchange of heat between the external air flow and the coolant inside the radiator 9. The box 3 also includes a thermostat 19, which can be controlled and whose function is to distribute the coolant according to its temperature to 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 engine 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 an evaporator for the working fluid, so 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 11, in a direction of flow of the fluid inside the heat exchange loop 10, the latter also comprises:

- An expansion member 12, also designated turbine or regulator, capable of transforming energy from the expansion of the working fluid into mechanical energy. Inside the expansion member 12 the fluid undergoes an expansion which lowers the temperature and the pressure of the working fluid.

- A heat exchanger 13 called cold because it is thermally connected to a cold source. This heat exchanger 13 preferably constitutes 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 to increase the pressure of the working fluid and to circulate 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 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 power 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.

The cooling circuit of the engine 1 also includes a loop of coolant towards the exchanger 11 called hot with:

an output S62 of the return pipe 7, as close as possible to the second output S32 of the housing 3, therefore of the motor output S2,

- an input E72 in the return line 7.

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 outlet S62.

The cooling circuit also comprises a device 6 for distributing the flow rate of coolant, FIG. 2 of which shows an enlarged schematic view of an embodiment. Preferably, this device 6 for distributing the coolant flow rate is integrated into the return pipe 7.

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

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

The so-called hot heat exchanger 11 comprises an inlet E11 for coolant fluidly connected to the second outlet, S62, of the device 6 for distributing the coolant flow rate. The heat exchanger 11 also includes an outlet S11 for coolant fluidly connected to the inlet E72 of the pipe 7 connecting the housing 3 to the pump 8.

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.

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 flow of coolant 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 flow of coolant through the second output 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 mode, 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 for distributing the coolant flow is less than a predefined threshold, Sr, for which it is judged that the temperature and the heat transferable to through the exchanger 11 are too weak 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. The Rankine loop is therefore deactivated : the fluid pump or compressor 14 and the expansion member 12 are inoperative here. 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 temperature rise phase, 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 thermostat 19 being closed, the coolant at the engine outlet goes, through the outlet S31 of the housing 3, to the air heater 4 and the EGR exchanger 5 before being reintroduced through the inlet E71 in the pipe 7 for be sucked in by the inlet E8 of the water pump 8 and be discharged from it 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, relatively in the direction of flow 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 coolant may not be sufficient for the pressure in the cooling circuit to remain below a safety threshold, in the long term not to affect the reliability of the circuit and to avoid a risk of leakage. 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 a spring reminder, not shown, which can also be calibrated as a function of the ratio of coolant flow rate 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 goes down again, 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 cooling liquid irrigating the thermosensitive element 6a3 of the actuator 6a having been able to increase meanwhile, it may therefore be that it is not 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 finished and the temperature and heat transferable through the hot exchanger 11 are now sufficient to take advantage of the Rankine loop: the Rankine loop is then activated and the pump 14 and the expansion member 12 now operate.

In this second 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 being still insufficient to cause its start opening and opening a larger passage for the fluid to 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 outlet 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 turbine 12. This arrangement makes it possible to overcome heat losses through the air heater 4.

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 inlet 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 FIG. 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, causing maximum 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.

While the coolant flow distribution device 6 occupies the configuration described in FIG. 5, more particularly while the second actuator 6b opens the second outlet S62 to allow the passage of the coolant to the exchanger 11, the opening of the outlet 61 by the pressostatic valve 6a1 under the appearance of the coolant pressure condition at the outlet S61 upstream of the first actuator 6a, then greater than the predefined pressure threshold Sp, can then reduce the share of the flow coolant sent from the pipe 7 to the exchanger 11 through the outlet S62 of the device 6 while the position of the valve of the second actuator 6b has remained stable.

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 cooling liquid irrigating the thermosensitive element 6a3 of the actuator 6a having been able to increase meanwhile, 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 heater 4 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 box 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 of the housing 3 towards 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 towards the radiator 9 the entire flow of coolant from the heat engine 1 which has not been directed, by the design of the housing 3, to the air heater circuit 4. The internal channel 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 towards the pipe 7 and the pump 8.

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 from the box 3 to the return pipe 7 and keeps the temperature of the coolant at the inlet E6 of the bypass practically constant in the pipe 7 at the two actuators 6a, 6b.

As shown in FIG. 7, as soon as the temperature of the cooling liquid irrigating the thermosensitive element 6b3 of the second actuator 6b of the device 6 reaches in this third phase a temperature higher than the regulation temperature, the first actuator 6a opens larger, for example as the temperature of the coolant at the heat-sensitive element 6a3 increases, the first outlet S61 to allow the passage of the coolant, the temperature of the coolant which irrigates the heat-sensitive element 6a3 being sufficient to cause the opening of the first actuator 6a and to open a larger passage for the fluid towards the pump 8. The second actuator 6b keeps the second outlet S62 open to allow the passage of the coolant from the pipe 7 to the exchanger 11, since the temperature of the coolant supplying the thermosen element sible 6b3 of the second actuator 6b of the device 6 is then greater than the predefined threshold Sr, itself being lower than the regulation temperature of the heat engine 1.

In order to better adapt its opening start temperature and its travel, the second thermostatic actuator 6b is of the piloted type: an electric element controlled by a vehicle computer is integrated into the thermostatic actuator 6b and makes it possible to cause it to opening at a coolant temperature different from its passive opening start threshold. The electrical actuation of the thermostatic actuator 6b is implemented by a control law recorded in a memory space of the computer, in particular as a function of the temperature of the coolant leaving the heat engine 1, of the engine rotation speed , the degree of opening of the thermostat 19 of the engine 1, the speed of the vehicle and the degree of activation of the motor-fan unit ensuring a complementary flow of outside air through the radiator 9.

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. at the output S2 of the engine 1, and more particularly at a temperature of coolant at the input E6 of the device 6 for distributing the flow of coolant, the highest possible, in particular taking into account the reliability of the heat engine 1. A such an arrangement makes it possible to increase the pressure and the temperature of the working fluid in the Rankine loop at the outlet of the exchanger 11: the heat of the coolant of the heat engine 1 is then transferred through the exchanger 11 to the working fluid of the Rankine loop at a higher temperature and the efficiency of the Rankine cycle is 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 proportion of the flow of liquid sent to the exchanger 11, for example while the device 6 for distributing the flow of coolant occupies the configuration described in FIG. 5 and that the second actuator 6b opens the second outlet S62 to authorize the passage of the coolant to the exchanger 11. This larger opening would be judiciously compensated for by a larger opening of the valve of the second actuator 6b, by setting in consequently the opening start temperatures and the opening strokes of the two actuators 6a, 6b in order to maintain the balance hydraulic ibre 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 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.

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

FIGS. 8 and 9 show a variant of a reversible Rankine loop, that is to say in which, in a first conventional configuration described in FIG. 8: The heat 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 a second configuration called "heat pump" described in Figure 9:

The heat exchanger 11 has the engine cooling circuit as a cold source while the heat exchanger 13 has the second cooling circuit as a hot source.

To this end, the heat exchange loop 10 is appropriately arranged, as illustrated in FIG. 8 or 9, 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 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.

More precisely in conventional mode (figure 8):

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

- The three-way valve V2 communicates the working fluid outlet Sf 11 of the exchanger 11 with the inlet 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.

In “heat pump” mode (figure 9), the circulation of the working fluid is reversed. However, keeping the same references for the inputs / outputs of the exchangers 11, as those of FIG. 8:

- 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, Sf11 of the exchanger 11,

- The four-way distributor valve V3 communicates the output of the compressor 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.

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. 9 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 member 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 rise in temperature 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 more energetically relevant to recover via the Rankine loop the thermal losses of the cooling circuit, the Rankine loop switches from the heat pump mode (illustrated in FIG. 9) to the conventional mode (illustrated in FIG. 8), in particular by adapting the position of the valves V1, V2, V3 installed on the Rankine loop.

The motor assembly of the invention provides an architecture which makes it possible to value the heat losses in the heat transfer circuit of the internal combustion engine of a conventional or hybrid traction chain while having the advantage of having no impact. on the reduction of polluting emissions and the priming of depollution organs: 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 (10)

Claims 1. Motorization set including: - an internal combustion engine (1) equipped with a cooling circuit intended to receive a coolant, this cooling circuit comprising an internal part of said engine (1) between an engine inlet (E2) and an outlet (S2) engine, and a pipe (7) for direct return of coolant to the engine inlet (E2), - a Rankine loop using a working fluid and comprising an exchanger (11) between the working fluid and the coolant of the cooling circuit using this cooling circuit as a hot source, characterized in that the cooling circuit comprises a coolant loop to exchanger (11) said to be hot, fluidly connected to: - an outlet (S62) from the pipe (7), located closest to the engine outlet (S2), - an inlet (E72) in the pipeline (7). 2. Motorization assembly according to claim 1, characterized in that the Rankine loop is arranged so as to be able to switch between the mode where the exchanger (11) uses the cooling circuit of the heat engine (1) as a hot source and a so-called heat pump mode where this same exchanger (11) uses the cooling circuit of the heat engine (1) as a cold source. 3. Motorization assembly according to claim 1 or claim 2, characterized in that the cooling circuit of the heat engine (1) comprises a device (6) for distributing the flow rates of coolant integrated into the pipeline (7) comprising an inlet (E6) for liquid from the pipe (7), the outlet (S62) from the pipe (7) to the exchanger (11) and another outlet (S61) in the pipe (7) to the inlet ( E2) of the motor (1), the device (6) comprising a first means for controlling the opening of the outlet (S61) towards the inlet (E2) of the motor (1) and a second means for controlling the opening of the outlet (S62) to the exchanger (11). 4. Motor assembly according to claim 3, characterized in that the first and / or the second opening control means are a thermostatic actuator (6a, 6b), preferably of the piloted type, or a solenoid valve. 5. Motorization assembly according to claim 3 or claim 4, characterized in that the first opening control means is also a pressostatic actuator designed to open said outlet (S61) if the pressure of the coolant upstream of the the actuator, relative to the direction of circulation of the liquid, exceeds a determined threshold (Sp). 6. Motorization assembly according to one of claims 3 to 5, characterized in that the first and second opening control means are designed so that: - for a coolant temperature below a temperature threshold (Sr) for which it is judged that the heat transferable through the exchanger (11) is too low to take advantage of the Rankine loop, the first means of control opening prevents the circulation of coolant in the pipe (7) returning to the inlet (E2) of the engine (1) and the second opening control means prevents the flow of coolant through the exchanger (11), - for a coolant temperature above this temperature threshold (Sr), the first opening control means prevents circulation of coolant circulation in the pipe (7) returning to the inlet (E2) of the engine (1) and the second opening control means authorizes the circulation of coolant through the exchanger (11). 7. Motor assembly according to claim 6, characterized in that the cooling circuit comprises a loop comprising a radiator (9) and a thermostat (19) designed to allow the circulation of the coolant in the loop comprising this radiator (9 ) when the coolant temperature is higher than an engine regulation temperature threshold (1), the temperature threshold (Sr) for which it is judged that the heat transferable through the heat exchanger (11) is hot too low to take advantage of the Rankine loop being below the engine regulation temperature threshold (1). 8. Motorization assembly according to claim 6 or claim 7, characterized in that it is designed so as to choose to activate the Rankine loop in the mode where the exchanger (11) uses the cooling circuit as a source hot when the coolant temperature is above the temperature threshold (Sr) for which it is judged that the heat transferable through the exchanger (11) is too low to take advantage of the Rankine loop. 9. Motorization assembly according to claim 7 and claim 2, characterized in that it is designed so as to choose to activate the Rankine loop in the heat pump mode when the coolant temperature is below the threshold regulating temperature of the engine (1) and authorizing the circulation of coolant through the exchanger (11) by the second opening control means. 10. Vehicle, characterized in that it is equipped with a motor assembly according to any one of the preceding claims. 1/4 S4 E4