FR2858268A1 - Heat energy management system for motor vehicle, has valves movable between closed and open positions in which heat radiator is part of high temperature circuit and is part of low temperature circuit for cooling condenser, respectively - Google Patents

Abstract

The system has a high temperature circuit (12) with a heat radiator (26), and a low temperature circuit (14), where the circuits use same heat transfer fluid. Two valves (44, 46) interposed between the circuits are movable between a closed position in which the radiator is part of the circuit (12) and an open position in which the radiator is a part of the circuit (14) for cooling a condenser (32) of the circuit (14). The radiator is used to heat a cab interior of a motor vehicle, and the condenser is connected to an air-conditioning system of the vehicle.

Description

Thermal energy management system, two circuits

  The invention relates to a system for managing the thermal energy of a motor vehicle.

  It more particularly relates to a system of this type, comprising a high temperature circuit for the circulation of a coolant and on which are mounted at least one high temperature heat exchanger and a heating radiator for heating the heat transfer fluid. interior, and a low temperature circuit for the circulation of a coolant 15 and on which are mounted at least one low temperature heat exchanger and a condenser connected to an air conditioning circuit.

  Systems of this type have already been proposed which comprise two circuits, one at high temperature and the other at low temperature, each traversed by a heat-transfer fluid, generally water added with an antifreeze such as ethylene glycol. The high temperature circuit is used more particularly for cooling the engine of the vehicle, in which the coolant circulates at a temperature generally between 85 ° C. and 100 ° C. This high temperature circuit also comprises the heating radiator, also called " air heater ", used for heating the passenger compartment.

  In contrast, in the low temperature circuit, the heat transfer fluid must be at a lower temperature, for example of the order of 40-60 C since the condenser must be cooled to a lower temperature. In the near future, it is envisaged to cool the air-conditioning condenser with a coolant, such as cold water, and not with air as in conventional air-conditioning circuits. Thus, in the case of an air-conditioning, in which the condenser is cooled by a cold heat-transfer liquid, such as cold water, the use of a low-temperature heat exchanger is imperative. It is therefore necessary to produce this cold heat transfer fluid using the maximum heat exchange area.

  In systems of the aforementioned type, the high temperature circuit and the low temperature circuit are independent and each traversed by a heat transfer fluid.

  Therefore, the only solution to increase the heat exchange area allocated to the low temperature circuit is to increase the heat exchange surface of the heat exchanger at low temperature.

  However, such an increase is difficult given the congestion constraints related to the vehicle.

  The object of the invention is in particular to overcome the aforementioned drawbacks.

  It is in particular an object of the invention to propose a system for managing the thermal energy of a motor vehicle, of the type defined above, in which the heat exchange surface allocated to the circuit at low temperature can be increased, and this without increasing the overall congestion of the system.

  To this end, the invention proposes a management system of the type defined above, in which the high temperature circuit and the low temperature circuit use the same heat transfer fluid, and in which switching means are interposed between the high temperature circuit. and the low temperature circuit and are arranged to be selectively placed, either in a first position in which the heating radiator is part of the high temperature circuit to serve as a heating radiator, or in a second position in which the radiator of Heating is part of the low temperature circuit for cooling the condenser.

  Thus, in the first position, the heating radiator 5 performs its usual function of heating radiator of the passenger compartment.

  In contrast, in the second position, the heating radiator is integrated in the circuit at low temperature and 10 then constitutes a heat exchanger capable of producing a cold heat transfer liquid, which improves the air conditioning performance.

  Indeed, in the latter case, the heat transfer fluid of the low temperature circuit is cooled not only in the low temperature heat exchanger, but also in the heating radiator, then acting as a cooling radiator, which allows to increase the heat exchange surface.

  Thus, the heating radiator which, by definition, is not used in the air conditioning phase of the vehicle, is then used for other purposes to cool the coolant used to cool the condenser. In the invention, the switching means advantageously comprise valve means interposed between the high temperature circuit and the low temperature circuit.

  In an advantageous embodiment, these switching means comprise a first three-way valve placed upstream of the heating radiator with respect to the direction of circulation of the heat transfer fluid in the high temperature circuit or the low temperature circuit and a second three-way valve placed downstream of the heating radiator with respect to the direction of circulation of the coolant in the high temperature circuit or the low temperature circuit.

  In a first embodiment of the invention, the condenser is in the form of a single heat exchanger.

  In this case, it is advantageous that, in the second position in which the heating radiator is part of the low temperature circuit, the condenser is connected in series after the heating radiator, so that a same flow of heat transfer fluid passes through successively the low temperature heat exchanger, the heating radiator and the condenser.

  In another embodiment of the invention, the condenser is constructed as a main condenser and an additional condenser.

  In this case, it is advantageous for the main condenser and the additional condenser to be mounted respectively on a first circulation branch and on a second circulation branch, both of which are derived from the low temperature heat exchanger and arranged in parallel.

  In addition, it is advantageous whereas, in the second aforementioned position, the second circulation branch 25 also contains the heating radiator so that a same flow of heat transfer fluid passes successively through the heating radiator and the additional condenser in this second branch of circulation.

Two variants are envisaged.

  In a first variant, the first branch of circulation and the second branch of circulation come from the same outlet of the heat exchanger at low temperature and are therefore fed by the same temperature level of the coolant.

  In a second variant, the first circulation branch and the second circulation branch are respectively from a first outlet and a second outlet of the low temperature heat exchanger providing two different temperature levels of the heat transfer fluid, the second output being at a lower temperature than the first output.

  Other complementary and / or alternative features of the invention are as follows: the high temperature circuit and the low temperature circuit comprise respective circulation pumps; the high temperature circuit comprises a thermostatic valve placed at the outlet of the engine for directing the heat transfer fluid either towards the high temperature heat exchanger or towards a bypass; the heat-transfer fluid is water added with an anti-gel; the first position of the switching means corresponds to a heating or dehumidification mode, whereas the second position of the switching means corresponds to an air conditioning or air conditioning mode with reheating.

  In the description which follows, given solely by way of example, reference is made to the appended drawings, in which: FIG. 1A is a diagram of a system for managing the thermal energy of a motor vehicle, according to a first embodiment of the invention, in a first position; FIG. 1B is a diagram similar to FIG. 1A in a second use position; FIGS. 2A and 2B are views similar to FIGS. 1A and 1B for a management system according to a second embodiment; FIGS. 3A and 3B are views similar to FIGS. 1A and 1B for a management system according to a third embodiment of the invention; FIG. 4 is an Enthalpy / Pressure graph illustrating the saturation curve of a refrigerant and the air conditioning cycle in the case of a conventional air-cooled condenser; and FIG. 5 is a similar graph illustrating the saturation curve of a refrigerant and the air-conditioning cycle in the case of condensers according to the invention.

  FIG. 1A is an overall view of a heating and air-conditioning device of the passenger compartment of a vehicle powered by a heat engine 10. The device of the invention constitutes a management system that makes it possible to manage the thermal energy released by the engine 10. It comprises a high temperature circuit designated by the general reference 12 and a low temperature circuit designated by the general reference 14. These two circuits form two loops interconnected and traversed by the same heat transfer fluid, preferably water added with an antifreeze, such as ethylene glycol.

  The high temperature circuit 12 comprises the motor 10, a circulation pump 16 for circulating the coolant in the circuit, a thermostat or a thermostatic valve 18 placed at the outlet of the motor for circulating the fluid, or in a line 20 comprising A heat exchanger 22 is the main radiator of the vehicle, which serves to cool the engine 10. The circuit 12 further comprises a heating radiator , also called air heater, used for heating the cabin.

  The high temperature circuit may include other heat exchangers, for example an oil cooler, an exhaust gas cooler, and the like. The low temperature circuit 14 comprises a circulation pump 28, a heat exchanger 30 and a condenser 32 forming part of an air conditioning circuit designated as a whole by the reference 34. This circuit 34 is traversed by a refrigerant under the action of a compressor 36 placed upstream of the condenser 32. The refrigerant passes successively through the condenser 32, a tank 38 (also called "bottle"), an expander 40, an evaporator 42, before returning to the compressor 36 The operation of this air conditioning circuit will not be described in detail, as it is a conventional circuit.

  In contrast, the condenser 32 is here cooled by the coolant, typically water added with antifreeze, instead of being cooled by a flow of air, as in conventional air conditioning circuits.

  The coolant flow rate in the high temperature circuit 12 is about 10 times greater than the flow rate of the same fluid in the low temperature circuit 14.

  According to the invention, the circuits 12 and 14 use the same heat transfer fluid and are mutually connected by switching means comprising two three-way valves which are common to the high temperature circuit 12 and the low temperature circuit 14. first valve 44 is placed upstream of the heating radiator 26, while a second valve 46 is placed downstream of this heating radiator. The terms "upstream" and "downstream" refer to the direction of circulation of the heat transfer fluid in one or other of the circuits 12 and 14.

  The valve 44 (upstream valve) comprises two inlet channels, one of which is connected to a pipe 48 issuing from the thermostatic valve 18 and the other to a pipe 50 issuing from the low temperature heat exchanger 30. these two input channels are respectively connected to the high temperature circuit and the low temperature circuit. The valve 44 also comprises an outlet channel connected to the heating radiator 26.

  The valve 46 (downstream valve) comprises an inlet channel connected to the pipe 50, an inlet channel connected by a pipe 52 to the outlet of the heating radiator 26, and an outlet channel connected to the condenser 32 via a pipe 54.

  In the position of Figure 1A, the inlet channel of the valve 44 which is connected to the pipe 50 is closed and the inlet channel of the valve 46 which is connected to the pipe 52 is also closed. As a result, the heating radiator 26 is integrated in the high-temperature circuit 12. At the output of the engine, a part of the coolant goes to the heating radiator 26, while another part goes either to the bypass 24, or to the radiator 22 at high temperature, depending on the position of the valve 18. The heat transfer fluid circulates in the circuit at high temperature in the direction indicated by the small arrows.

  The low temperature circuit 14 is isolated from the high temperature circuit and the coolant passes successively through the low temperature exchanger 30 and the condenser 32, the latter being realized as a single heat exchanger. The heat transfer fluid circulates in the circuit at low temperature in the direction indicated by the large arrows.

  In this first position, the heating radiator 26 performs its usual function of heating the passenger compartment.

  The device is then used in heating mode. It is also possible to operate simultaneously the air conditioning circuit 34 and to cool the condenser 32 by the coolant circulating in the low temperature circuit 14.

  Indeed, it may be advantageous to dehumidify the air 5 before sending it into the heating radiator and direct it to the passenger compartment. Thus, the system can also operate in dehumidification mode in the position shown in Figure 1A.

  In the position of FIG. 1B, the inlet of the valve 44 connected to the pipe 48 is closed and, likewise, the inlet of the valve 46 connected to the pipe 50 is closed. As a result, the heating radiator 26 is integrated with the low temperature circuit 14.

  The heat transfer fluid circulates in the high temperature circuit 12 as represented by the small arrows. In this case, the heat transfer fluid from the engine block is distributed only between the bypass 24 and the pipe 20 leading to the high temperature heat exchanger 22.

  On the other hand, in the low temperature circuit 14, the coolant circulates, under the action of the pump 28, successively through the heat exchanger 30 at low temperature, the heating radiator 26 and the condenser 32. As a result, the heating radiator 26 here performs a different function, namely a cooling function. Therefore, the coolant for cooling the condenser has a greater heat exchange area, namely that resulting from the low temperature heat exchanger 30 and that of the heating radiator 26, allowing to further lower the temperature of the coolant used to cool the condenser 32.

  For example, the heat transfer fluid leaving the heating radiator 26 sees its temperature lower, for example 5. Thus, the heat transfer fluid entering the condenser is at a lower temperature than in the case where the heating radiator is not integrated in the circuit, so that the performance of the air conditioning circuit 34 is better.

  Reference is now made to FIGS. 2A and 2B. This embodiment is similar to that of FIGS. 1A and 1B, with the difference that the condenser is designed as a main condenser 32-1 and an additional condenser 32-2. The main condenser and the additional condenser 10 are mounted respectively on a first circulation branch 56 and on a second circulation branch 58 both coming from the low temperature heat exchanger 30, these two branches 56 and 58 being arranged in parallel. In the example, the branches 56 and 58 come from the same outlet 60 of the low-temperature heat exchanger 30 and are therefore supplied with the same temperature level of the coolant. The branch 56 leads directly to the main condenser 32-1, while the branch 58 leads to the additional condenser 32-2 directly 20 (position of Figure 2A), or indirectly via the heating radiator 26 (position of Figure 2B) .

  In the position of Figure 2A, the heating radiator 26 is integrated with the high temperature circuit 12, as in the case of Figure 1A. The heat transfer fluid circulates in this circuit 12 as represented by the small arrows. In the low temperature circuit 14, the heat transfer fluid from the low temperature heat exchanger 30 is distributed between the main condenser 32-1 and the additional condenser 32 nel 32-2. The system is used either in heating mode or in dehumidification mode as in the case of Figure 1A.

  The air conditioning circuit 34 benefits from the main condenser and the additional condenser, both of which are traversed by a fluid at the same temperature. In the case of FIG. 2B, the heating radiator 26 is integrated in the low temperature circuit 14, as in the case of FIG. 1B. The radiator 26 is inserted between the heat exchanger 30 at low temperature and the additional condenser 32-2. Thus, the heat transfer fluid leaving the heating radiator 26 has seen its temperature drop, for example 5 C. The heat transfer fluid entering the additional condenser 32-2 is therefore colder than the one entering the main condenser 32. 1, which improves the performance of the air conditioning loop.

  The system shown in Figures 3A and 3B is similar to that of Figures 2A and 2B. It also includes a main condenser 32-1 and an additional condenser 32-2. Unlike the previous embodiment, the branches 56 and 58 come from two different outlets 62 and 64 of the low temperature heat exchanger 30. The outlet 64 which feeds the second leg 58 is at a temperature lower than the temperature. output 62 which feeds the branch 56.

  In the position of FIG. 3A, the heating radiator 26 is integrated in the high temperature circuit 12 and fulfills its usual function of heating the passenger compartment. The heat transfer fluid circulates in the circuit 12 as represented by the small arrows.

  In contrast, in the low temperature circuit 14, the heat transfer fluid circulates as represented by the large arrows. The heat transfer fluid flowing through the additional condenser 32-2 is at a lower temperature than the coolant passing through the main condenser 32-1.

  In the position of Figure 3A, the system can operate either in heating mode or in dehumidification mode.

  In the position of FIG. 3B, the heating radiator is integrated with the low temperature circuit 14. It is then inserted between the low temperature heat exchanger 35 and the additional condenser 32-2. As in the previous embodiments, the heat transfer fluid leaving the heating radiator 26 has seen its temperature drop, for example 5 C. The heat transfer fluid that enters the additional condenser is at a cooler temperature, which improves the performance of the air conditioning loop.

  In the embodiments of FIGS. 2A and 2B, respectively 3A and 3B, the proportion of heat transfer fluid circulating in the main condenser is greater than that circulating in the additional condenser. By way of example, 90% can be in the main condenser and 10% in the additional condenser.

  FIG. 4 is a graph of Enthalpy (abscissa) / Pressure (ordinate) showing the saturation curve of a refrigerant and the condensation cycle in the case of a conventional air-cooled condenser. The air conditioning cycle is materialized by a quadrilateral with a "compression" side on the right, a "condensation" side on the right, a "relaxation" side on the left and an evaporation side on the bottom.

  FIG. 5 is a similar Enthalpy / Pressure graph showing the saturation curve of a refrigerant and three air conditioning cycles corresponding to condensers cooled by a coolant (in the example of water) according to the invention.

  The cycle C1 corresponds to a condenser cooled by water, without the use of the heating radiator 26 as a cooling radiator. It can be seen that the left "expansion" side of the Cl cycle is parallel to the pressure axis and corresponds to an enthalpy El.

  The cycle C2 corresponds to a condenser cooled by water, with the use of the heating radiator 26 as a cooling radiator. The left side "expansion" of the cycle C2 is parallel to the axis of the pressures and corresponds to an enthalpy E2 which is of value less than the enthalpy El of the cycle C1, from which a gain G2 = E1-E2 in performance of air conditioning with respect to the circuit C1.

  The cycle C3 corresponds to a two-stage condenser (main condenser and additional condenser) cooled by water with the use of the heating radiator 26 as a cooling radiator. The left side "expansion" of the cycle C3 is parallel to the pressure axis and corresponds to an enthalpy E3 which is of value less than the enthalpy E2 and of the cycle C2 and therefore less than the enthalpy El of the cycle Cl. This results in a gain G3 = E1-E3 in air conditioning performance with respect to the circuit C1. These comparisons show the gain in performance achieved with the use of the heating radiator as a condenser cooling radiator and the additional increase in gain resulting from the use of a two-stage condenser over a one-way condenser. single floor.

  The invention is not limited to the embodiments described above and is capable of alternative embodiments. Thus, the switching means could be replaced by other types of valves.

  The invention finds application to motor vehicles.

Claims (15)

claims   A system for managing the thermal energy of a motor vehicle, comprising: - a high temperature circuit (12) for the circulation of a coolant and on which at least one high temperature heat exchanger is mounted (22) and a heating radiator (26) for heating the passenger compartment, and 10 - a low temperature circuit (14) for the circulation of a coolant and on which are mounted at least one heat exchanger. low temperature (30) and a condenser (32) connected to an air conditioning circuit (34), characterized in that the high temperature circuit (12) and the low temperature circuit (14) use the same heat transfer fluid, and in that switching means (44, 46) are interposed between the high temperature circuit (12) and the low temperature circuit (14) and are arranged to be selectively placed, either in a first position in which the radiator heating (26) made part of the high temperature circuit (12) for use as a heating radiator, or in a second position in which the heating radiator (26) is part of the low temperature circuit (14) for cooling the condenser (32) .   2. System according to claim 1, characterized in that the switching means comprise valve means (44, 46) interposed between the high temperature circuit (12) and the low temperature circuit (14).   3. System according to one of claims 1 and 2, characterized in that the switching means comprise a first three-way valve (44) placed upstream of the heating radiator (26) relative to the direction of flow of the fluid. coolant in the high-temperature circuit (12) or the low-temperature circuit (14), and a second three-way valve (46) placed downstream of the heating radiator (26) with respect to the direction of circulation of the coolant in the high temperature circuit (12) or the low temperature circuit (14).   4. System according to claim 3, characterized in that the first three-way valve (44) comprises two input channels respectively connected to the high temperature circuit (12) and the low temperature circuit (14) and a channel 10 output signal connected to the heating radiator, and in that the second three-way valve (46) comprises two input channels respectively connected to the heating radiator and the low temperature circuit and an output channel connected to the low temperature circuit . 15 5. System according to one of claims 1 to 4, characterized in that the condenser (32) is formed as a single heat exchanger.   6. System according to claim 5, characterized in that, in the second position in which the heating radiator (26) is part of the low temperature circuit (14), the condenser (32) is connected in series after the radiator of heating (26) such that a same coolant flow passes successively through the low temperature heat exchanger (30), the heating radiator (26) and the condenser (32).   7. System according to one of claims 1 to 4, characterized in that the condenser is embodied as a main condenser (32-1) and an additional condenser (32-2).   8. System according to claim 7, characterized in that the main condenser (32-1) and the additional condenser (322) are mounted respectively on a first circulation branch (56) and on a second circulation branch (58). both from the low temperature heat exchanger (30) and arranged in parallel.   9. System according to claim 8, characterized in that, in the second position in which the heating radiator (26) is part of the low temperature circuit (14), the second circulation branch (58) also contains the radiator. heating (26) so that a same flow of heat transfer fluid successively passes through the heating radiator (26) and the additional condenser (32-2) in this second branch of circulation.   10. System according to one of claims 8 and 9, characterized in that the first branch of circulation (56) and the second branch of circulation (58) are from the same outlet (50) of the heat exchanger at low temperature (30) and are fed by the same temperature level of the heat transfer fluid.   11. System according to one of claims 8 and 9, characterized in that the first branch (56) and the second branch (58) are respectively derived from a first outlet (62) and a second output (64) of the low temperature heat exchanger (30) providing two different temperature levels of the coolant, the second output (64) being at a lower temperature than the first output (62). 25 12. System according to one of claims 1 to 11, characterized in that the high temperature circuit (12) and the low temperature circuit (14) comprise respective circulation pumps (16; 28). 30 13. System according to one of claims 1 to 12, characterized in that the high temperature circuit (12) comprises a thermostatic valve (18) placed at the output of the engine (10) for directing the coolant is to the high temperature heat exchanger (22) or to a bypass (24).   14. System according to one of claims 1 to 13, characterized in that the heat transfer fluid is water containing an antifreeze.   15. System according to one of claims 1 to 14, characterized in that the first position of the switching means (44, 46) corresponds to a heating or dehumidification mode, while the second position of the switching means corresponds to an air conditioning or air conditioning mode with reheating.