FR2815299A1 - COOLING SYSTEM AND METHOD FOR A HYBRID PROPULSION VEHICLE - Google Patents

Abstract

Cooling system for a hybrid propulsion vehicle, comprising a heat transfer fluid capable of cooling the thermal 1 and electric motors 2, a radiator 6 for cooling the heat transfer fluid, a first pipe 7 between said radiator 6 and the heat engine 1 and a second pipe 8 between said heat engine 1 and said radiator 6 in the direction of flow of the heat transfer fluid, and a bypass pipe 15 comprising a first branch 17 connected to the first pipe 7 and a second branch 18 connected to a pipe upstream of the engine thermal, said bypass line 15 being able to cool the electric motor 2.

Description

Cooling system and method for a hybrid powered vehicle.

  The present invention relates to a cooling system

  for hybrid propulsion vehicle.

  Hybrid powered vehicles generally include a heat engine, one or two electric motors, an electric voltage generator, and an electronic power converter assembly which either powers the electric motor (s) or charges the batteries, all of which need to be cooled. in order to operate under the conditions for which they are intended. We are looking to take advantage of this dual engine to minimize consumption and

  polluting emissions, so as to remain below the authorized levels.

  It has been found that the ranges of flow rate and temperature of the coolant are very different for an electric motor and for a heat engine. The coolant of an electric motor has a flow rate of the order of 100 to 500 l / hour at a temperature of 50 to 70. The coolant of a heat engine has a flow which can be twenty times higher, at a temperature of the order of 100 to maximum. These differences in flow and temperature make it difficult to use a single circuit and a single radiator operating under optimal conditions in all the situations encountered.

  for a hybrid powered vehicle.

  Document FR 2 748 428 describes a cooling system for a hybrid propulsion vehicle comprising a heat engine and an electric motor, comprising a heat transfer liquid circulating in the engines and in a radiator and means so that, the heat engine being at stop and the electric motor being running, the heat transfer liquid circulates in a first part of the radiator only, and so that, with the two engines running, the heat transfer liquid circulates

in both parts of the radiator.

  However, it is generally necessary to provide an electric pump for circulating the coolant in the electric motor. Electric pumps are either very expensive or last for

insufficient life.

  The present invention proposes to overcome the limitations of conventional techniques by proposing a cooling system that operates optimally in all cases and makes it possible to

  reduce energy consumption and polluting emissions.

  The present invention proposes to reduce the operating time of a coolant circulation pump.

in the electric motor.

  The present invention proposes to maintain the electric motor

  and low temperature power electronics.

  The cooling system, according to one aspect of the invention, is intended for a hybrid propulsion vehicle comprising a heat engine and at least one electric motor. The system is of the type comprising a heat transfer fluid capable of cooling the thermal and electric motors, a radiator comprising a plurality of cooling channels and capable of cooling the heat transfer liquid by heat exchange with a stream of air, a first pipe between said radiator and the heat engine in the direction of flow of the heat transfer fluid and a second pipe between said heat engine and said radiator in the direction of flow of the heat transfer fluid. The system comprises a bypass line comprising a first branch connected to the first line and a second branch connected to a line upstream of the heat engine, said bypass line

  being able to cool the electric motor.

  Preferably, the first branch goes through the motor

  electric and an electronic power unit of the electric motor.

  In one embodiment of the invention, the first branch

  is equipped with a heat transfer fluid circulation pump.

  In one embodiment of the invention, said pump

  circulation of the heat transfer fluid is driven by the electric motor.

  In another embodiment of the invention, said heat transfer fluid circulation pump is driven independently of the

electric motor.

  Preferably, the bypass line includes a third

  branch connected to the second pipe.

  In one embodiment of the invention, the second branch is connected to an outlet pipe of a heating radiator of a

vehicle interior.

  Preferably, the bypass line comprises a fourth branch connected to the output of the upstream heat engine

a thermostat.

  Advantageously, the branches of the bypass pipe are

  connected to each other by a multi-way valve.

  In one embodiment of the invention, a thermostat is

  integrated into said multi-way valve.

  In one embodiment of the invention, the multi-way valve

  includes a rotating control core.

  The invention also relates to a vehicle comprising a

  cooling system as above.

  The invention also provides a cooling method for a hybrid propulsion vehicle comprising a heat engine and at least one electric motor cooled by the circulation of a heat transfer fluid in said engines, a heat exchange means, a first pipe between said means heat exchange and the heat engine in the direction of flow of the heat transfer fluid and a second pipe between said heat engine and said heat exchange means in the direction of flow of the heat transfer fluid, process in which, the heat transfer fluid in a bypass line connected firstly to the first line and secondly to a line upstream of the heat engine, for

cool the electric motor.

  Cooling is thus carried out in series, the heat transfer fluid passing through the bypass pipe then passing into the heat engine, which is preferable in the event of a high temperature.

  outlet of the heat exchange medium.

  Advantageously, the flow of heat transfer fluid in the bypass line is varied as a function of the temperature at the outlet of the

heat exchange medium.

  In one embodiment of the invention, if the temperature of the heat transfer fluid is insufficient to cause the opening of a thermostat disposed at the outlet of the heat engine, the heat transfer fluid is circulated in the bypass line connected thirdly to the second line, to cool the electric motor by

  the absence of circulation of heat transfer fluid in the heat engine.

  This operating mode can also be adopted when the engine

thermal is stopped.

  In one embodiment of the invention, in the event of a temperature of the heat transfer fluid significantly lower than the opening temperature of a thermostat disposed at the outlet of the heat engine, the heat transfer fluid is circulated in the connected bypass pipe of fourth leaves at the outlet of the heat engine upstream of the thermostat, to cool the electric motor while warming up the heat engine. It is thus possible to obtain a faster rise in temperature of the heat engine when it starts and to reduce the formation

of polluting elements.

  This operating mode can also be adopted when the heat engine is stopped, if the pump associated with the heat engine is electrically driven or if said pump can be bypassed. We

  can thus preheat the engine.

  The invention will be better understood and other advantages

  will appear on reading the detailed description of some modes of

  embodiment taken by way of nonlimiting examples and illustrated by the appended drawings, in which: - Figure 1 is a schematic view of a cooling system according to a first embodiment of the invention; - Figure 2 is a schematic view in axial section of an example of a multi-way valve; - Figure 3 is a schematic cross-sectional view of the multi-way valve of Figure 2; - Figure 4 is a schematic cross-sectional view of a multi-way valve integrated into a thermostat; and - Figure 5 is a schematic view of another mode of

  realization of the cooling system.

  To simplify our description, the term "electric motor"

  defines all the machines that convert electrical energy into mechanical energy, or mechanical energy into electrical energy, and the term "power electronics" defines all the electronics that convert alternating current into direct current, direct current in alternating current, high voltage current in low voltage current, or alternatively low voltage current in high voltage current. As can be seen in Figure 1, the cooling system is associated with a heat engine 1 and an electric motor 2 provided with an electronic power unit 3. This electronic power unit 3 is generally placed before the electric motor 2 because its operating temperature is lower than the electric motor. There is also a heating radiator 4 for heating the passenger compartment of the vehicle in which the cooling system is installed, as well as an exchanger 5 for cooling any fluid, for example lubricating oil, oil gearbox, ... or any other body, for example a

turbocharger bearing, ...

  The cooling system includes a radiator 6, the

  outlet is connected to a pipe 7 and the inlet of which is connected to a pipe 8.

  Line 7 is connected to a pump 9, the output of which is connected to the heat engine 1. The pump 9 can be driven by the heat engine 1 or by an electric motor which is dedicated to it and which has not been shown. The output of the motor 1 is provided with a thermostat 10, itself connected to the pipe 8. The radiator 6 is generally provided with a fan 1 1

  motorized, capable of accelerating the flow of air through said radiator 6.

  The cooling system comprises a temperature sensor 12 disposed at the outlet of the engine 1, immediately upstream of the thermostat 10, a temperature sensor 13 mounted on the pipe 7 at the outlet of the radiator 6, and a control unit 14 receiving information temperature from the sensors 12 and 13. The connection between the control unit 14 and the sensors 12 and 13 can be carried out by dedicated electrical wires or via a communication bus. The input of the heating radiator 4 is connected to an output of the heat engine 1 and the output of the radiator 4 is connected to the pipe 7. Likewise, the input of the exchanger 5 is connected to an output of the heat engine

  1 and its output is connected to line 7.

  The cooling system further comprises a bypass line referenced 15 as a whole and provided with several branches, and a multi-way valve 16 to which said branches are connected. More specifically, a first branch 17 is connected, on the one hand to the pipe 7 downstream of the temperature sensor 13 and, on the other hand to the multi-way valve 16. The branch 17 passes through the electric motor 2 and through the electronic power unit 3. The circulation of the cooling fluid in said branch 17 makes it possible to maintain the electric motor 2 and the electronic power unit 3 at a normal operating temperature, if possible sufficiently low so that common industrial components , both electric and electronic,

  can be used in the construction of these elements.

  There is also an electric pump 21 arranged on the branch 7, controlled by the control unit 14 and circulating the cooling fluid in said branch 17. A second branch 18 is connected at one end to the first pipe 7 to proximity to the

  pump 9 and at the opposite end to the multi-way valve 16.

  A third branch 19 is connected, on the one hand to the pipe 8 and, on the other hand to the multi-way valve 16. A fourth branch 20 is connected, on the one hand to an output of the heat engine 1 upstream of the

  thermostat 10 and, on the other hand to the multi-way valve 16. The multi-way valve

  tracks 16 is suitable for connecting the branches 17 and 18 by closing off the branches 19 and 20, for connecting the branches 17 and 19 by closing the other branches and for connecting the branches 17 and 20 by closing the other branches , and this on order of the unit

  control 14 to which it is connected.

  In other words, the multi-way valve 16, which is here four-way, has the function of ensuring the selective passage of the cooling fluid between the branch 17 and one of the other three branches 18,

19 or 20.

  The operation of the cooling system is as follows. If the water temperature as measured by the sensor 12 is less than a predetermined temperature Tcl and which is less than or equal to the total opening temperature of the thermostat 10, generally between 83 and 89 C, the multi valve channels 16 connects branches 17 and 20 and allows the fluid from branch 20 to pass

  towards branch 17, when the heat engine 1 is in operation.

  Indeed, the cooling fluid which is in the heat engine 1 is subjected to a high pressure due to the pump 9, pressure higher than that prevailing in the branch 17, the pump 21 being

kept stationary.

  In this state, which is that of an operation at the start of the heat engine 1 or at very low load, no energy is consumed by the pump 21 which is stopped. The heat released by the operation of the electric motor 2 and of the electronic power unit 3 makes it possible to increase the temperature of the heat engine 1 and therefore to reduce the duration of its rise in temperature, which results in the reduction of the quantity of polluting elements generated by the combustion of the heat engine 1. Keeping the pump 21 at a standstill reduces its overall operating time and therefore allows a lifetime

overall longer.

  If the sensor 12 indicates a water temperature greater than or equal to the temperature Tcl but less than the total opening temperature of the thermostat 10, the multi-way valve 16 puts branches 17 and 19 into communication. The pump 21 is put on running at low speed, for example with a low supply voltage U1. The electric motor 2 and the electronic power unit 3 are then cooled by means of the radiator 6, the heat exchange capacity of which is much greater, for example by a factor of the order of 3 to 5, than the heat capable to be

  released by the electric motor 2 and the electronic power unit 3.

  Line 8, radiator 6 and line 7 being dimensioned for the high flow rates of coolant required by the heat engine 1, the pressure drops are low. The energy consumed by the

  pump 21 is therefore also weak. Its wear is also.

  If the sensor 12 indicates a water temperature greater than or equal to the temperature Tot, the multi-way valve 16 communicates the branches 17 and 18. The pump 21 is started. In other words, part of the output flow rate of the radiator 6 is derived by the branches 17 and 18. The electric motor 2 and the electronic power unit 3 are cooled by coolant output from the radiator 6, and therefore

at low temperature.

  In addition, it can be provided that if the temperature sensor 13 at the outlet of the radiator 6 indicates a coolant temperature below a predetermined temperature Tc2, the pump 21 operates at low flow rate, for example with the low supply U1 , and on the other hand if the sensor 13 indicates a temperature higher than the temperature Tc2, the pump 21 operates at high flow rate, for example supplied by a voltage U2 greater than U1 to obtain a higher flow rate

  strong in branch 17. It will be understood that Tc2 is greater than Tot.

  Of course, the control unit 14 of the cooling system can control the operation of the fan 1 1 in

  function of the temperature measured by the sensor 13.

  When the heat engine 1 is stopped, the multi-way valve 16 connects the branches 17 and 19. The pump 21 is started at low flow rate, for example supplied by the voltage U1. The radiator 6 then cools the electric motor 2 and the electronic power unit 3, which can operate at the low temperatures which are required by the components of large series, at

  low cost, which one wishes to use.

  Thus, the water temperature at the inlet of the electric motor 2 and of the electronic power unit 3 remains very low in all operating cases. Measurements carried out on a prototype show that even in the case where the heat engine 1 is in operation and where the water temperature at the outlet of the engine is higher than the opening temperature of the thermostat, the temperature at the outlet of the radiator 6 remains below 85 C for 85% of the vehicle usage time. For cases where the temperature measured by the sensor 13 is greater than Tc2, the increase in the flow rate of the pump 21 and / or the triggering of the fan 11 make it possible to maintain this temperature within the desired limits. Thanks to the invention, the pump 21 needs a low power, runs slower and less frequently. In an operating case, the pump 18 is stopped. In two other operating cases where the thermostat is closed, the heat exchange capacity of the radiator 6, dimensioned for the heat losses of the heat engine 1, is largely in excess of the heat losses of the electric motor 2 and of the electronic unit. of power 3 and therefore allows the pump 21 to operate at low flow rate. Finally, the branches 17, 18 and 19 are connected to pipes 7 and 8 of large diameter, which minimizes the

  pressure drop undergone by the fluid driven by the pump 21.

  In Figures 2 and 3, an example of valve 16 is shown. The valve 16 comprises a cylindrical casing 22 and a rotary core 23 which can rotate around the axis 24 under the action of an electric motor 25. At a level called "lower", the casing 22 is provided with a bore into which opens the branch 17. At a level called "upper", offset from the lower level, the housing 22 is provided with three holes in each of which open respectively the branches 18, 19 and 20. The core 23 includes a passage of fluid 26 in the form of a Z and an outer annular cavity 27. The annular cavity 27 is in communication with the branch 17, whatever the angular position of the core 23. The cavity

  annular 27 is in communication with passage 26.

  Alternatively, provision could be made for the fluid passage 26 to be C-shaped or other shapes with a smoother change in the direction of flow to reduce the loss of fluid pressure. By the action of the electric motor 25, the core 23 can be positioned in three angular positions, such that the passage 26 is opposite one of the branches 18, 19 or 20, to respectively authorize the communication of the branches 17 and 18, 17 and 19 or 17 and 20. From any initial state of the core 23, it is possible to pass directly to another state without going through an intermediate state other than a state of total closure. The passage from one state to another is done by a simple

  120 rotation of the core 23 in one direction or the other.

  In FIG. 4, a particularly compact variant is illustrated in which it is proposed to integrate the valve 16 into the thermostat 10. The thermostat 10 comprises a fixing plate 28 on the motor, so that the inlet 29 of the thermostat 10 is connected to a coolant outlet of the heat engine 1 of FIG. 1. The thermostat 10 comprises an outlet 30 intended to be connected to the pipe 8 of FIG. 1, and an outlet 31 provided to be connected to the radiator 4 and to the 'exchanger 5

  of Figure 1. The input 29 and the output 31 are in free communication.

  Between the inlet 29 and the outlet 30, a valve 32 actuated by a spring 33 is provided. At low temperature, lower than Tot, the spring 33 maintains the valve 32 in the closed position, the circulation of coolant

  heat engine 1 to the radiator 6 of FIG. 1 being cut off.

  The valve 32 is fixed to a rod 34, the free end of which is immersed in a mixture of waxes and copper particles enclosed in a small reservoir called "bulb", referenced 35, fixed to the frame of the thermostat 10. The bulb 35 is permanently bathed by the coolant which passes from the heat engine to the outlet 31. At a temperature below Tot, the mixture contained in the bulb 35 is in the solid state. When the temperature of the coolant increases, the mixture contained in the bulb 35 liquefies and expands until pushing the valve 32 and causing the opening of the inlet passage

29 to exit 30.

  It is expected that the branch 19 of the valve 16 opens directly into the outlet 30 and that the branch 20 opens near the bulb 35, in the space in which it is housed and in which the

  coolant between inlet 29 and outlet 31.

  FIG. 5 shows a cooling system comprising a thermostat 10 and a valve 16 integrated. The branch 18 is connected at its end opposite the valve 16 to the pipe portion 36 connecting the radiator 4 and the pipe 7. It is thus possible to reduce the length of

  branch 18, which is economical.

  It has been assumed above that the pump 21 was driven by an independent electric motor. It is also conceivable that the pump 21 is driven by the electric traction motor 2. This is advantageous for the cost and the service life of the system. Indeed, a conventional electric pump is generally direct current. Compared to a mechanical pump, the electric motor is the main additional cost of an electric pump and generally has a significantly shorter service life than that of the mechanical pump. How the system works

is then the following.

  If the water temperature measured by the sensor 12 is lower than the total opening temperature of the thermostat, the branches 17 and 19 are put into communication. If the water temperature measured by the sensor 12 is greater than or equal to the temperature Tot, and if the vehicle is in electric traction mode, thermal engine 1 stopped, the fluid communication between the branches 17 and 19. If the coolant temperature measured by the sensor 12 becomes greater than or equal to the temperature Tot and if the engine is in

  operation, the valve 16 connects the branches 17 and 18.

  In addition, if the sensor 13 measures a temperature higher than the predetermined temperature Tc2, the fan 11 is started, in particular if the vehicle speed is low, for example less than

  a value between 60 and 80 km / h.

  Note in the case where the pump 21 is driven by the motor 2, the passage of the fluid from 20 to 17, provided in hybrid mode to reduce the use of the pump 21, is no longer necessary, and the valve 16 can

become a 3-way valve.

Claims (11)

  1. Cooling system for a hybrid propulsion vehicle comprising a heat engine (1) and at least one electric motor (2), of the type comprising a heat transfer fluid capable of cooling the heat and electric motors, a radiator (6) comprising a plurality cooling channels and capable of cooling the heat transfer fluid by heat exchange with a stream of air, a first pipe (7) between said radiator and the heat engine in the direction of flow of the heat transfer fluid and a second pipe (8) between said heat engine and said radiator in the direction of flow of the coolant, characterized in that it comprises a bypass pipe (15) comprising a first branch (17) connected to the first pipe and a second branch (18 ) connected to a pipe upstream of the engine, said bypass pipe being able to   cool the electric motor (2).   2. System according to claim 1, characterized in that the first branch passes through an electronic unit (3) of power and the electric motor (2).   3. System according to claim 1 or 2, characterized in that the first branch is equipped with a pump (21) for circulation of the coolant.   4. System according to any one of the claims   previous, characterized in that the bypass line includes   a third branch (19) connected to the second pipe.   5. System according to any one of the claims   above, characterized in that the second branch is connected to an outlet pipe of a radiator (4) for heating a passenger compartment of a vehicle.   6. System according to any one of the claims   above, characterized in that the bypass pipe comprises a fourth branch (20) connected to the output of the engine in upstream of a thermostat (10).   7. System according to any one of the claims   previous, characterized in that the branches of the   bypass are connected together by a multi-way valve (16).   8. System according to claim 7, characterized in that a   thermostat is integrated into said multi-way valve.   9. System according to claim 7 or 8, characterized in that the multi-way valve comprises a rotary control core (23). 10. Vehicle comprising a system according to any one of previous claims.   11. Cooling method for a hybrid propulsion vehicle comprising a heat engine and at least one electric motor cooled by the circulation of a heat transfer fluid in said engines, a heat exchange means, a first pipe between said radiator and the heat engine in the direction of flow of the heat transfer fluid and a second line between said heat engine and said radiator in the direction of flow of the heat transfer fluid, in which the heat transfer fluid is circulated in a bypass line connected first to the first line and secondly to a line upstream of the engine, to cool the electric motor.