Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
  • F01P7/00—Controlling of coolant flow
  • F01P7/14—Controlling of coolant flow the coolant being liquid
  • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control
  • F01P7/165—Controlling of coolant flow the coolant being liquid by thermostatic control characterised by systems with two or more loops
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
  • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
  • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
  • F02M26/23—Layout, e.g. schematics
  • F02M26/28—Layout, e.g. schematics with liquid-cooled heat exchangers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
  • F02B29/04—Cooling of air intake supply
  • F02B29/0406—Layout of the intake air cooling or coolant circuit
  • F02B29/0437—Liquid cooled heat exchangers
  • F02B29/0443—Layout of the coolant or refrigerant circuit

Definitions

• the present invention relates to the cooling of motor vehicle powertrains, comprising a heat engine and various organs that should be maintained at a suitable operating temperature.
• the thermal power to be removed by the radiator to maintain the temperature level is significantly greater than that which can evacuate a radiator operating at a higher temperature. This results in a difficulty of design of the cooling system and a difficulty of integration of these various elements in the vehicle.
• the conventional cooling circuit of a thermal engine generally comprises a circulation pump mechanically driven by the engine itself and a heater constituted by a heat exchanger that heats the passenger compartment of the vehicle.
• a thermostatic valve is generally provided to communicate the cooling circuit of the heat engine with another circuit comprising an additional radiator.
• an expansion vessel in the form of a hermetically sealed jar, through which the coolant passes.
• a hermetically sealed jar allows the expansion of the water used as heat transfer fluid by maintaining a certain volume of compressible air inside. It also keeps the entire cooling system under pressure, in order to avoid any risk of cavitation of the circulation pump driven by the motor. It is preferable to mount such an expansion tank downstream of the thermostatic valve and in parallel with the engine cooling circuit so as to limit as much as possible the volume of coolant to be heated, which makes it possible to reduce the energy required for operation of the assembly by decreasing the temperature rise time of the heat engine. To ensure two temperature levels for the heat transfer fluid, it has already been proposed in some applications, cooling systems having two cooling circuits, either independent or with common parts.
• French patent application 2,815,402 describes a cooling system of this type for a hybrid-propulsion vehicle comprising a heat engine and at least one electric motor.
• the system allows the heat engine to be cooled to a first temperature level, and the electric motor and its control unit to a second temperature level lower than the first level.
• the described system comprises a radiator subdivided into several compartments.
• the cooling system includes a main circuit and a secondary circuit which is a bypass of the main circuit. One of the radiator compartments is part of the secondary circuit.
• the secondary compartment used in this system is completely dedicated to the secondary circuit.
• the main circuit is not connected to the cooling circuit of the engine, for example during the cold start phase when the thermostatic valve is still closed, it would be interesting to use a larger area exchange of the radiator to lower the temperature of the heat transfer fluid flowing in the secondary circuit.
• the subject of the present invention is the production of such a cooling system which makes it possible to define two temperature levels for cooling two distinct sets of powertrain members, in particular in the case where the circuit comprises a mounted expansion tank. downstream of the thermostatic valve.
• the present invention also aims to make it easier to install the various cooling radiators on the front of a vehicle while increasing the efficiency of cooling.
• the invention also relates to a cooling system which allows to easily cool the gearbox of the motor vehicle without generating significant pressure drop and without substantially increasing the volume of the heat transfer fluid required.
• a thermal motor vehicle power train cooling system includes a main circuit capable of being traversed by a heat transfer fluid to cool a first set of powertrain members to a first temperature level and a heat transfer fluid.
• secondary circuit that can be traversed by a coolant to cool a second set of powertrain members to a second temperature level, lower than the first level.
• a main radiator is part of the main circuit and a secondary radiator is part of the secondary circuit.
• a first thermostatic or controlled valve for example electrically, is mounted in the main circuit downstream of the heat engine so as to isolate the main radiator when the temperature of the coolant is lower than a first threshold.
• An expansion vessel is mounted in the main circuit downstream of the thermostatic valve to degas the coolant.
• the connections are such that the secondary radiator can also be part of the main circuit in an operating mode of the system.
• the system further comprises an additional radiator mounted in parallel with the main radiator, and a second thermostatic or controlled valve, capable of allowing or preventing the passage of heat transfer fluid from the heat engine to the secondary radiator.
• the cooling of the engine and the various powertrain members is thus considerably improved without disturbing the degassing of the heat transfer fluid.
• this configuration reduces the size of the main radiator which can then be more easily implanted on the front of the vehicle, for example by the additional radiator.
• the reduction of the exchange surface resulting from such reduced dimensions of the main radiator is then compensated, when the need arises, by passing the heat transfer fluid through the secondary radiator of the secondary circuit.
• a third thermostatic or controlled valve may be mounted in a branch between the return branch of the main circuit and the return branch of the secondary circuit so as to eliminate any communication by said bypass when the temperature of the coolant is lower than a second upper threshold at the first threshold.
• the main radiator preferably comprises a main inlet and a main outlet connected directly to the circuit and a secondary outlet connected to the main circuit via a thermostatic or controlled valve, and the additional radiator is mounted between the main inlet and the secondary outlet of the main radiator.
• the first set of powertrain members capable of being cooled by the coolant flowing through the main circuit may for example comprise an additional injector, the engine lubricating oil circuit and the vehicle gearbox.
• the second set of powertrain members capable of being cooled by the coolant flowing through the secondary circuit may for example comprise the partial exhaust gas recirculation (EGR) circuit and a partial exhaust gas recirculation valve. (EGR).
• EGR partial exhaust gas recirculation
• An electric pump is advantageously mounted in the secondary circuit in order to circulate the coolant.
• gearbox oil cooling exchanger mounted at the outlet of the main radiator, so as to cool the gearbox of the vehicle.
• the gearbox oil cooling exchanger can be mounted in a branch of the return branch of the main circuit, equipped with a thermostatic or controlled valve.
• the turbocharger can be mounted in a branch of the main circuit, being associated with an electric pump, to be cooled by the coolant flowing through the main circuit when the engine is stopped. It is advantageous to connect the turbocharger in parallel with the exhaust gas recirculation (EGR) circuit, thereby avoiding the need to provide an electric pump.
• EGR exhaust gas recirculation
• the invention also relates to a method for cooling a motor vehicle power unit using a coolant circulating in a cooling circuit, in which the fluid is also passed through.
• coolant in a main circuit for cooling a first set of powertrain members to a first temperature level
• the main circuit and the secondary circuit can be isolated from the cooling circuit by a thermostatic or controlled valve and the coolant is degassed downstream of the valve.
• Calories are extracted from the coolant by passing it through a main radiator and an additional radiator connected in parallel, and the main circuit is placed in communication with the secondary circuit when it is desired to increase the cooling of the coolant.
• FIG. 1 is a schematic view of a cooling system according to the invention
• FIG. 2 shows the flow of the heat transfer fluid during the cold start phase of the heat engine, the temperature of the coolant being lower than a first threshold
• Figure 3 is a view similar to Figure 2, showing the flow of heat transfer fluid when the temperature thereof has exceeded a first threshold while remaining below a second threshold greater than the first
• Figure 4 is a view similar to Figure 2, illustrating the circulation of the heat transfer fluid when the temperature thereof has exceeded the second threshold
• - Figure 5 is a view similar to Figure 2 showing the flow of heat transfer fluid for maximum cooling
• Figure 6 is a view similar to Figure 5 showing an alternative flow of the heat transfer fluid for maximum cooling
• Figure 7 is a schematic view of a second embodiment of a cooling system according to the invention
• Figure 8 is a schematic view of a third embodiment of a cooling system according to the invention.
• the cooling system for powertrain of a motor vehicle is adapted to the cooling of a heat engine 1 and various associated members.
• the cooling of the engine 1 is obtained firstly by circulation of a coolant such as water, in a cooling circuit 2 comprising a forward branch 2a and a return branch 2b.
• a water pump 3 driven mechanically by the engine 1 circulates the coolant in the cooling circuit 2.
• the circuit 2 comprises a heater 4.
• various members as examples which require a cooling to a temperature level comparable to that of the engine, which level will be called in this description "high level". It is particularly an additional injector that can be mounted for example in the exhaust line of the engine to ensure the regeneration of a particulate filter.
• This additional injector is cooled by a heat exchanger 5 connected in parallel with the heater 4 in the cooling circuit 2.
• a heat exchanger 6 capable of cooling the lubricating oil of the 1.
• the exchanger 6 is mounted in a branch 7 of the cooling circuit 2 on the return branch 2b thereof.
• a thermostatic valve 8 is mounted in a main circuit 9 which can be traversed by the heat transfer fluid leaving the heat engine 1 when the thermostatic valve 8 is open, that is to say when the temperature of the heat transfer fluid exceeds a first threshold of temperature Ti which corresponds to the lower limit of the level "high".
• the thermostatic valve 8 can be replaced by a controlled valve, for example electrically, associated with a temperature sensor of the coolant, providing a control signal.
• the main circuit 9 comprises a forward branch 9a and a return branch 9b.
• the thermostatic valve 8 is mounted on the forward leg 9a.
• a main radiator 10 and an additional radiator 11 are mounted in the main circuit 9.
• An expansion vessel 12 through which the heat transfer fluid passes is mounted downstream of the thermostatic valve 8.
• a pipe 13 communicating with the forward leg 9a is connected to the inlet 14 of the main radiator 10.
• a pipe 15 stitched on the forward leg 9a is connected to the inlet of the additional radiator 1 1.
• a pipe 16 also stitched on the branch 9a, downstream of the thermostatic valve 8, is connected to the inlet of the expansion vessel 12.
• the expansion vessel 12 allows in particular the degassing of the heat transfer fluid. For this purpose, it comprises a hermetically sealed container, an inlet at the bottom for the coolant and an outlet at the top.
• the output of the additional radiator January 1 is connected by a pipe 17, on the one hand to the return branch 9b of the main circuit 9, by a branch 18 and on the other hand to the output of the main radiator 10.
• the thermostatic valve 19 can also be replaced, like the thermostatic valve 8, by a valve ordered of the same type.
• the outlet 22 of the main radiator 10 is connected to a heat exchanger 23 for cooling the gearbox oil of the motor vehicle.
• the pipe 24 is stitched onto the return branch 9b of the main circuit 9.
• the pipe 25 connected to the outlet of the expansion tank 12 is stitched onto the return leg 9b of the circuit principal 9.
• the cooling system further comprises a secondary cooling circuit 26 with a forward branch 26a and a return branch 26b.
• An electric circulation pump 27 is mounted in the forward leg 26a.
• the heat transfer fluid flowing in the secondary circuit 26 is at a temperature level below the "high" level. We will speak here of "low” level.
• the heat transfer fluid circulated by the pump 27 passes through a first heat exchanger 28 capable of cooling the partial exhaust gas recirculation system (EGR), then a heat exchanger 29 capable of cooling the control valve of the exhaust gas recirculation system EGR.
• a heat exchanger 30 is also provided for cooling the turbocharger of the engine in the illustrated example.
• the heat exchanger 30 is connected in parallel with the heat exchanger 29.
• the secondary circuit 26 comprises a secondary radiator 31 traversed by the heat transfer fluid at the low temperature level.
• a controlled three-way valve 31b is mounted in the return branch 26b of the secondary circuit 26.
• the valve 31b is also connected via a duct 32, directly to the cooling circuit 2, at the output of the engine 1. It is therefore able to implement communicating the heat transfer fluid at high temperature with the secondary circuit 26.
• the valve 31b can be replaced by a thermostatic valve.
• the return branch 26b of the secondary circuit 26 is also connected directly to the return branch 9b of the main circuit 9, via a conduit 33.
• a controlled valve 34 is further mounted in a branch 35 putting the forward branch 26a of the secondary circuit 26 into communication with the return branch 9b of the main circuit 9.
• the valve 34 can be replaced by a thermostatic valve.
• the two valves 19 and 31 which are, in the illustrated example, two-way valves, can be replaced by a single three-way valve.
• the thermostatic valve 8 When the heat engine 1 runs cold, for example at startup, as shown in Figure 2, the thermostatic valve 8 is closed. The heat transfer fluid flows into the cooling circuit 2 driven by the water pump 3. The heater 4 transfers the heat transfer fluid calories to the passenger compartment of the vehicle and the cooling of the additional injector through the exchanger 5, and the cooling of the engine lubricating oil through the exchanger 6.
• the electric pump 27 is in operation and circulates the heat transfer fluid at the "low" temperature level in the secondary circuit 26. This passes through the secondary radiator 31 in the direction of the arrows indicated in FIG. EGR exhaust gas recirculation through the exchangers 28 and 29 as well as the cooling of the turbocharger by the exchanger 30 are effected efficiently since the coolant is well cooled by the secondary radiator 31 while being kept at the "low" level of temperature.
• the controlled valve 34 is closed to prevent any recirculation upside down in the expansion tank 12, recirculation which could disrupt its operation.
• the heat transfer fluid always enters through the inlet duct 16 of the expansion vessel 12, which enters the lower position in the vessel 12 and leaves through the outlet pipe 25 located in the upper position, in order to ensure the degassing.
• the three-way valve 31b is placed so as to let only the heat transfer fluid from the return branch 26b to the secondary radiator 31. No circulation is allowed in the conduit 32.
• FIG. 3 illustrates the operation of the cooling system when the vehicle is in an intermediate rolling phase, the temperature of the coolant being greater than the first temperature threshold Ti but still less than a second threshold T 2 with T 2 greater than T 1 .
• the thermostatic valve 8 is then partially open.
• the electric pump 27 works and the EGR exhaust gas recirculation system is cooled by passing through the secondary radiator 31.
• the heat transfer fluid also flows into the main circuit 9, which is partially open, and can pass through the expansion vessel 12 from the input pipe 16 to the outlet pipe 25.
• the heat transfer fluid from the forward leg 9a of the circuit 9 also passes through the additional radiator 11 from the pipe 15.
• the fluid having passed through the additional radiator January 1 is mixed again with the heat transfer fluid leaving the main radiator 10.
• the controlled valve 34 is closed and the three-way valve 31b leaves the passage of the heat transfer fluid only from the return branch 26b to the secondary radiator 31 as in the configuration of Figure 2.
• the thermostatic valve 19 As long as the temperature does not exceed a threshold T 2 greater than the first threshold T 1 , the thermostatic valve 19 remains closed. As soon as this second threshold is crossed, the valve 19 opens to increase the permeability of the circuit 9 and therefore the flow of heat transfer fluid through the exchangers. This configuration is illustrated in FIG. 4.
• the three-way valve 31b is controlled so as to change its position, leaving the passage of the coolant to the first one. high level of temperature from the engine 1 to the secondary radiator 31 and prohibiting the return of the coolant at the second low temperature level, coming from the return branch 26b of the secondary circuit 26.
• FIG. 5 This phase is illustrated in FIG. 5.
• the flow rate of the coolant coming from the engine 1 is distributed in the main radiator 10, the additional radiator 11 and the secondary radiator 31.
• the thermostatic valve 19 is open.
• the coolant coming from the return branch 26b of the secondary circuit 26 returns to the return branch 9b of the circuit 9 via the line 33.
• valve 34 is shown closed. In FIG. 6, on the contrary, the only difference is the valve 34 open, which makes a bipass of the exchangers 28 and 29 of the EGR system so as to further increase the flow rate passing through the secondary radiator.
• the thermostatic valve 8 which was open, closes gradually.
• the valve 31 is controlled to return to the position shown in Figure 2.
• the circulation of the heat transfer fluid in the secondary circuit 26 is then identical to that shown in Figure 2.
• the electric water pump 27 operates for a certain time after stopping the engine to allow the turbocharger to be cooled by means of the exchanger 30.
• the controlled valve 34 must be closed in order to prevent any circulation in the opposite direction in the expansion vessel 12. the entire cooling system, the valve 34 is placed in the open position once the circulation pump 27 has stopped.
• the thermostatic valve 8 is preferably also open.
• FIG. 7 differs from the embodiment illustrated in FIG. 1 by the mounting of the heat exchanger 30 adapted to the cooling of the turbocharger on a branch 36 in parallel with the heater 4, the exchanger 5 being also mounted on said branch 36.
• An additional electric water pump 37 is mounted in the branch 36 so as to improve the circulation of the coolant.
• Such a connection makes it possible to increase the flow of coolant passing through the exchanger 30 with respect to the embodiment illustrated in FIG. 1.
• FIG. 8 illustrates another embodiment that differs from the embodiment illustrated in FIG. 1 by mounting the exchanger 23 intended for cooling the gearbox.
• the exchanger 23 is in fact mounted on a bypass 38 of the return branch 9b of the main circuit 9.
• An additional thermostat 39 is mounted between the input and output taps of the branch 38.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Exhaust-Gas Circulating Devices (AREA)
• Cooling, Air Intake And Gas Exhaust, And Fuel Tank Arrangements In Propulsion Units (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=38231380

Family Applications (1)

Country Status (3)

Families Citing this family (5)

Family Cites Families (7)

• 2007
  • 2007-03-26 FR FR0754036A patent/FR2914357B1/fr not_active Expired - Fee Related
• 2008
  • 2008-03-19 EP EP08775721A patent/EP2126308A1/de not_active Withdrawn
  • 2008-03-19 WO PCT/FR2008/050467 patent/WO2008132369A1/fr active Application Filing

Non-Patent Citations (1)

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