Heat pump and method for managing such a heat pump

Abstract

Heat pump and this method for managing such a heat pump. The invention relates to a heat pump (1) of a heating, ventilation and air conditioning device (3) of a motor vehicle, said device comprising a heat exchanger (5) and an air heater (7), said heat pump comprising: - a closed circuit for the flow of a refrigerant fluid (11), - a heat exchanger (13) mounted in a front panel of said vehicle, - a compressor (15), mounted at the outlet of said heat exchanger (13). According to the invention, said heat pump comprises a solenoid valve (19) comprising an inlet connected to the outlet of said compressor and two outlets alternately or simultaneously supplying said heat exchanger (5) and an additional water circuit (21) supplying said air heater (7). The invention also relates to a method for managing such a heat pump. Figure 4

Description

Title of the invention: Heat pump and method for managing such a heat pump Technical field

[0001] The invention relates to the field of thermal management of a motor vehicle passenger compartment, more precisely to the field of heating the passenger compartment by a heat pump device.

[0002] More particularly, the invention relates to a heat pump and a method for managing such a heat pump. Prior art

[0003] The autonomy of electric motor vehicles is one of the most important factors in the commercial success of this type of vehicle and for their acceptance on the market.

[0004] Battery electric motor vehicles (BEVs) typically include a traction battery powering the motor vehicle's electric motor. The only electrical energy available to the motor vehicle is that stored in the traction battery.

[0005] In order to improve the capacity of the traction batteries of electric motor vehicles, a solution aimed at increasing the size of the traction batteries is very penalizing, because this would make the motor vehicle more bulky, increase its mass and considerably increase its cost price.

[0006] A known alternative is to limit the energy consumption of traction batteries. To do this, one solution is to control the energy consumption caused by the operation of the heating, ventilation and air conditioning device, a device frequently referred to by the acronym "HVAC" (an acronym for "Heating, Ventilation and Air-Conditioning").

[0007] The HVAC is supplied with air via a heat pump.

[0008] A first heat pump architecture known from the prior art is a so-called direct heat pump.

[0009] In such a direct architecture, the refrigerant that runs through the heat pump circuit is the only thermal medium between the outside air and the air in the passenger compartment. The compressor heats the high-pressure, high-temperature refrigerant that runs through the heat pump circuit and this fluid is directly injected into an exchanger that is present in the vehicle's HVAC and which will directly heat the air. The fluid thus directly heats the air in the passenger compartment via an exchanger.

[0010] In heating mode, the refrigerant takes heat from the outside air and then transmits it directly to the air blown into the passenger compartment.

[0011] In air conditioning mode, the refrigerant takes heat from the air in the passenger compartment and then transmits it directly to the outside air.

[0012] In such a direct heat pump, the number of heat exchanges is limited, which makes it possible to obtain a very rapid rise in temperature of the blown air intended for heating the passenger compartment. Thus, the direct heat pump makes it possible to limit losses and therefore to obtain optimal operating performance.

[0013] However, variations in compressor operation have a direct impact on the stability of the heat pump.

[0014] Also, variations in vehicle speed generate changes in air speeds at the air inlet of the direct heat pump.

[0015] Thus, such a direct heat pump is unstable, which impacts comfort within the passenger compartment.

[0016] A second heat pump architecture known from the prior art is a so-called indirect heat pump.

[0017] In an indirect heat pump, the refrigerant is no longer the only thermal medium between the outside air and the air in the passenger compartment as was the case for a direct heat pump.

[0018] An additional water circuit is located between the compressor and the HVAC. The HVAC includes an air heater supplied with water by the additional water circuit.

[0019] Thus, in heating mode, instead of directly heating the passenger compartment via the HVAC exchanger, the heat pump circuit first supplies the water circuit, which then supplies the HVAC air heater.

[0020] The air conditioning mode operates in the same way as the direct architecture, i.e. without the intermediary of the additional water circuit.

[0021] The HVAC used in an electric vehicle with an indirect heat pump may be identical to that used in a thermal vehicle, the HVAC of a thermal vehicle comprising an air heater. Thus, in comparison with the HVAC used in an electric vehicle with a direct heat pump, no adaptation of the HVAC is necessary, which is not the case for the HVAC used in an electric vehicle with a direct heat pump, such an HVAC not comprising an air heater.

[0022] Such an indirect heat pump also has better stability in terms of the temperature of the blown air since it benefits from the inertia necessary to heat the intermediate water circuit.

[0023] On the other hand, taking into account the fact that the air is heated by means of the water circuit itself heated by the refrigerant fluid itself heated by the compressor, thermal losses inherent in heat exchanges generate sub-optimal performance, particularly during the convergence phase towards a set temperature.

[0024] The temperature rise of the blown air intended for heating the passenger compartment is thus slower, compared with a direct heat pump.

[0025] The indirect heat pump therefore offers less efficiency than a direct heat pump.

[0026] In order to optimize the energy consumption of a vehicle, in particular when the vehicle is electric, there is a need to propose a heat pump architecture allowing both rapid activation with optimum efficiency for optimization of electrical consumption during vehicle start-ups and the possibility of having stable heating power during steady-state driving phases. Statement of the invention

[0027] The present invention aims to overcome the aforementioned drawbacks, and to do so relates to a heat pump for a heating, ventilation and air conditioning device of a motor vehicle, said heating, ventilation and air conditioning device comprising a heat exchanger, capable of generating heat, and an air heater, capable of being supplied with water, said heat pump comprising: - a closed circuit for the flow of a refrigerant fluid, - a heat exchanger mounted in a front panel of said motor vehicle and capable of admitting air from outside the motor vehicle, - a compressor, mounted at the outlet of said heat exchanger, capable of sucking in and compressing said refrigerant, said heat pump being characterized in that it comprises a solenoid valve comprising an inlet connected to the outlet of said compressor and two outlets alternately or simultaneously supplying said heat exchanger of said heating, ventilation and air conditioning device and an additional water circuit supplying said air heater.

[0028] Thus, when the user operates the heat pump in heating mode, the solenoid valve only supplies the heat exchanger of said heating, ventilation and air conditioning device, so that the heat pump operates in direct mode as long as the duration of use of the heat pump is less than a predetermined threshold value.

[0029] In this way, for a short journey, the heat pump according to the invention makes it possible to restrict the thermal exchanges in the circuit of the heat pump, which makes it possible to obtain a very rapid rise in temperature of the blown air intended for heating the passenger compartment, which makes it possible to obtain optimum efficiency of the heat pump. heat and therefore optimize the vehicle's electrical consumption.

[0030] If the user continues to use the heat pump beyond the predetermined threshold value, the solenoid valve only supplies the additional water circuit supplying the air heater, so that the heat pump according to the invention operates in indirect mode.

[0031] Thus, when the operating time of the heat pump is greater than the predetermined threshold value, the indirect mode of the heat pump is preferred, this mode offering, in comparison with the direct mode, better stability at the level of the temperature of the blown air insofar as one benefits from the inertia necessary to heat the additional water circuit supplying the HVAC air heater.

[0032] According to optional characteristics of the heat pump according to the invention: - said solenoid valve is controlled by suitable software means for: operating said heat pump in direct mode as long as the duration of use of said heat pump is less than a predetermined threshold value, said direct mode being obtained by positioning said solenoid valve so as to supply only said heat exchanger of said heating, ventilation and air conditioning device, operating said heat pump in indirect mode when the duration of use of said heat pump is greater than said predetermined threshold value, said indirect mode being obtained by positioning said solenoid valve so as to supply only said water circuit supplying said air heater, - said software means is adapted to operate said heat pump in hybrid mode after operation of said heat pump in direct mode and before operation of said heat pump in indirect mode, said hybrid mode being obtained by positioning said solenoid valve so as to simultaneously supply said heat exchanger of said heating, ventilation and air conditioning device and said water circuit supplying said air heater.

[0033] The invention also relates to a method for managing a heat pump, said heat pump being according to the invention, said method being implemented by software means integrated into said motor vehicle and comprising the following steps aimed at: - operating said heat pump in direct mode as long as the duration of use of said heat pump is less than a predetermined threshold value, said direct mode being obtained by positioning said solenoid valve so as to supply only said heat exchanger of said heating, ventilation and air conditioning device, - operate said heat pump in indirect mode when the duration of use of said heat pump is greater than said predetermined threshold value, said indirect mode being obtained by positioning said solenoid valve so as to supply only said water circuit supplying said air heater.

[0034] According to optional characteristics of the management method according to the invention: - the method comprises an additional step, subsequent to said step aimed at operating said heat pump in direct mode and prior to said step aimed at operating said heat pump in indirect mode, aimed at operating said heat pump in hybrid mode, said hybrid mode being obtained by positioning said solenoid valve so as to simultaneously supply said heat exchanger of said heating, ventilation and air conditioning device and said water circuit supplying said air heater, - said threshold value is determined according to the heat requirement necessary to reach a set temperature in the passenger compartment of said motor vehicle, - said threshold value increases when said heat requirement increases, - the said threshold value is determined according to the outside temperature, - the said threshold value increases when the outside temperature decreases, - in one embodiment, said threshold value is between approximately 5 minutes and approximately 20 minutes. Brief description of the drawings

[0035] Other characteristics, aims and advantages of the invention will appear on reading the detailed description which follows, for the understanding of which reference will be made to the appended drawings in which:

[0036] [Fig-1] is a schematic diagram of a heat pump of a heating, ventilation and air conditioning device of a motor vehicle.

[0037] [Fig.2] illustrates the operation of the heat pump of the invention in direct mode.

[0038] [Fig.3] illustrates the operation of the heat pump of the invention in indirect mode.

[0039] [Fig.4] illustrates the operation of the heat pump of the invention in hybrid mode.

[0040] [Fig.5] shows the steps of the heat pump management method according to the invention.

[0041] [Fig.6] shows an alternative embodiment of the heat pump management method according to the invention. Description of the embodiments

[0042] In the remainder of the description, elements having an identical structure or similar functions are designated by the same reference.

[0043] Reference is made to [Fig.l] showing the operating principle of a heat pump 1 according to the invention.

[0044] The heat pump 1, also called a heat management system, is designed to manage the heat of a heating, ventilation and air conditioning device 3 of a motor vehicle, a device frequently designated by the acronym “HVAC” (English acronym for “Heating Ventilation and Air-Conditioning”).

[0045] The heat pump 1 is adapted to operate either in direct mode, or in indirect mode, or in a hybrid mode in which the heat pump operates in both direct mode and indirect mode.

[0046] To do this, the HVAC 3 used in the context of the present invention and managed by the heat pump 1 comprises a heat exchanger 5, capable of generating heat, frequently referred to by the English expression “heater core”. As will be seen in the remainder of the description, the heat exchanger 5 of the HVAC 3 is used when the heat pump operates in direct mode or in hybrid mode and when the heat pump operates in heating mode.

[0047] The HVAC 3 further comprises a unit heater 7, capable of being supplied with water. The unit heater 7, known to those skilled in the art, is an exchanger which is capable of exchanging heat between a circuit in which hot water circulates and blown air, the blown air being linked to the HVAC blower and heating the passenger compartment of the vehicle. As will be seen in the remainder of the description, the unit heater 7 of the HVAC 3 is used when the heat pump operates in indirect mode or in hybrid mode and when the heat pump operates in heating mode.

[0048] The HVAC 3 also includes an evaporator 9, capable of generating cold, used regardless of the operating mode of the heat pump and when the heat pump is operating in air conditioning mode.

[0049] The heat pump 1 comprises a closed circuit for the flow of a refrigerant fluid 11.

[0050] In the direction of flow of the refrigerant fluid 11, the heat pump 1 comprises a heat exchanger 13 mounted in the front facade of the motor vehicle and capable of admitting air from outside the motor vehicle.

[0051] The heat exchanger 13 is capable of behaving as an evaporator or as a condenser depending on whether the heat pump 1 operates in heating mode or in air conditioning mode.

[0052] At the outlet of the heat exchanger 13, the heat pump 1 comprises a compressor 15 supplied with electrical energy by an accumulator 17 and capable of sucking in and compressing the refrigerant fluid 11.

[0053] According to the invention, the heat pump 1 comprises a solenoid valve 19 comprising an inlet connected to the outlet of the compressor 15 and two outlets supplying the heat exchanger 5 of the HVAC 3 and / or an additional water circuit 21 supplying the air heater 7 of the HVAC 3.

[0054] Thus, when the solenoid valve 19 supplies the heat exchanger 5 of the HVAC 3, the heat pump 1 operates in direct mode.

[0055] Similarly, when the solenoid valve 19 supplies the water circuit 21 supplying the air heater 7 of the HVAC 3, the heat pump 1 operates in indirect mode.

[0056] Finally, when the solenoid valve 19 supplies both the heat exchanger 5 of the HVAC 3 and the water circuit 21 supplying the air heater 7 of the HVAC 3, the heat pump 1 operates in hybrid mode.

[0057] We refer to [Fig.2] showing the operation of the heat pump 1 in direct mode.

[0058] The dotted line shows the path of the refrigerant in the heat pump 1 when the heat pump 1 operates in direct mode.

[0059] In heating mode, the refrigerant 11 is admitted in the liquid state into the heat exchanger 13 mounted in the front panel of the vehicle at a temperature lower than the temperature outside the vehicle.

[0060] The heat exchanger 13 admits air from outside the vehicle. The outside air admitted into the heat exchanger 13, the temperature of which is lower than the temperature of the refrigerant 11 admitted into the heat exchanger 13, heats the refrigerant 11.

[0061] At the outlet of the heat exchanger 13, which here behaves like an evaporator, the refrigerant 11 is introduced in the gaseous state into the compressor 15.

[0062] The compressor 15 compresses at high pressure and heats the refrigerant 11 to high temperature.

[0063] In this direct mode, the solenoid valve 19 is controlled so that the refrigerant 11 is directly introduced into the heat exchanger 5 of the HVAC 3.

[0064] The heat exchanger 5 of the HVAC 3 heats the air blown into the passenger compartment, represented by the arrow 23.

[0065] The refrigerant 11 is then expanded before being reintroduced in the liquid state into the heat exchanger 13 mounted in the front panel of the vehicle.

[0066] In air conditioning mode, the refrigerant 11 at the outlet of the compressor 15 is sent to the heat exchanger 13 mounted in the front panel of the vehicle. The heat exchanger 13 then behaves like a condenser. At the outlet of the heat exchanger 13, the refrigerant 11 is sent to the evaporator 9 of the HVAC 3. By means of a fan integrated in the HVAC 3, an exchange is created between the outside blown air 23 and the evaporator 9 of the HVAC 3, which allows cooling interior decoration.

[0067] We refer to [Fig.3] showing the operation of the heat pump 1 in indirect mode.

[0068] The dotted line shows the path of the refrigerant in the heat pump 1 when the heat pump 1 operates in indirect mode.

[0069] In heating mode, the refrigerant 11 is admitted in the liquid state into the heat exchanger 13 mounted in the front panel of the vehicle at a temperature lower than the temperature outside the vehicle.

[0070] The heat exchanger 13 admits air from outside the vehicle. The outside air admitted into the heat exchanger 13, the temperature of which is lower than the temperature of the refrigerant 11 admitted into the heat exchanger 13, heats the refrigerant 11.

[0071] At the outlet of the heat exchanger 13, which here behaves like an evaporator, the refrigerant 11 is introduced in the gaseous state into the compressor 15.

[0072] The compressor 15 compresses at high pressure and heats the refrigerant 11 to high temperature.

[0073] In this indirect mode, the solenoid valve 19 is controlled so that the refrigerant fluid 11 is introduced into the additional water circuit 21.

[0074] The water circuit supplies the air heater 7 of the HVAC 3 which heats the air blown into the passenger compartment, represented by the arrow 25. The air is therefore here heated by means of the water circuit 21, the water itself being heated by the refrigerant 11, itself heated by the compressor 15 which has compressed and heated the refrigerant 11.

[0075] The refrigerant 11 is then expanded before being reintroduced in the liquid state into the heat exchanger 13 mounted in the front panel of the vehicle.

[0076] The air conditioning mode is identical to that described for the direct mode.

[0077] We refer to [Fig.4] showing the operation of the heat pump 1 in hybrid mode.

[0078] In hybrid mode, the solenoid valve 19 is controlled so that the refrigerant 11 is introduced both into the heat exchanger 5 of the HVAC 3 and into the additional water circuit 21.

[0079] The air blown into the passenger compartment, represented by arrow 27, is heated both by means of the water circuit 21 and by the heat exchanger 5 of the HVAC 3.

[0080] According to one arrangement of the invention, the solenoid valve 19 is controlled according to the life situations of the motor vehicle by means of a method for managing the heat pump 1 implemented by software means which can be integrated into the motor vehicle.

[0081] For this purpose, the software means is programmed to implement the method of the invention. The software means is for example integrated into a computer of the motor vehicle, for example in the electronic management box known under the name “BSI”, acronym for “Intelligent Servitude Box”.

[0082] Reference is made to [Fig.5] showing the steps of the method for managing the heat pump 1 according to the invention.

[0083] When starting the vehicle, if the user operates the heat pump 1 in heating mode, the method and the heat pump 1 according to the invention are adapted to operate the heat pump 1 in direct mode (step E10) as long as the duration of use of the heat pump 1 is less than a predetermined threshold value.

[0084] Using the heat pump 1 in direct mode makes it possible, for a short journey, to restrict the heat exchanges in the circuit of the heat pump 1, which makes it possible to obtain a very rapid rise in temperature of the blown air intended for heating the passenger compartment, which makes it possible to obtain optimum efficiency of the heat pump 1.

[0085] If the user continues to use the vehicle and the heat pump 1 beyond the predetermined threshold value, the method and the heat pump 1 according to the invention are adapted to operate the heat pump 1 in indirect mode (step E20).

[0086] Thus, when the operating time of the heat pump is greater than the predetermined threshold value, the indirect mode of the heat pump 1 is preferred, this mode offering, in comparison with the direct mode, better stability at the level of the temperature of the blown air insofar as it benefits from the inertia necessary to heat the additional water circuit 21 supplying the air heater 7 of the HVAC 3.

[0087] Reference is made to [Fig.6] showing a variant of the method for managing the heat pump 1 according to the invention.

[0088] The method and the heat pump 1 according to the invention can be adapted to operate the heat pump 1 in hybrid mode (step Eli) after its operation in direct mode and before its operation in indirect mode.

[0089] This makes it possible to gradually reach indirect mode, which further increases the stability of the heat pump 1 and makes the transition from direct mode to indirect mode imperceptible to the user.

[0090] In one embodiment of the invention, the threshold value can be determined as a function of the heat requirement necessary to reach a set temperature in the passenger compartment of the motor vehicle. The threshold value increases when the heat requirement increases. In this way, the duration of use of the heat pump 1 in direct mode increases when the heat requirement increases.

[0091] The heat requirement can be determined as a function of the set temperature defined in the passenger compartment and, for example, as a function of the outside temperature and / or the outside humidity level. More specifically, the threshold value can be determined depending on the outside temperature. The threshold value increases as the outside temperature decreases.

[0092] By way of non-limiting example, the threshold value may be between approximately 5 minutes and approximately 20 minutes.

[0093] For example, if the outside temperature is equal to approximately -20°C, the threshold value is between approximately 15 minutes and approximately 20 minutes, whereas if the outside temperature is equal to approximately 0°C, the threshold value is between approximately 5 minutes and approximately 10 minutes.

[0094] As goes without saying, the present invention is not limited to the embodiments of this heat pump and this method for managing such a heat pump, described above solely as illustrative examples, but on the contrary it embraces all variants involving the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

Claims

Claims

1. Heat pump (1) of a heating, ventilation and air conditioning device (3) of a motor vehicle, said heating, ventilation and air conditioning device (3) comprising a heat exchanger (5), capable of generating heat, and an air heater (7), capable of being supplied with water, said heat pump (1) comprising: - a closed circuit for the flow of a refrigerant fluid (11), - a heat exchanger (13) mounted in a front panel of said motor vehicle and capable of admitting air from outside the motor vehicle, - a compressor (15), mounted at the outlet of said heat exchanger (13) mounted in said front panel of said motor vehicle, capable of sucking and compressing said refrigerant fluid (11),said heat pump (1) being characterized in that it comprises a solenoid valve (19) comprising an inlet connected to the outlet of said compressor (15) and two outlets alternately or simultaneously supplying said heat exchanger (5) of said heating, ventilation and air conditioning device (3) and an additional water circuit (21) supplying said air heater (7).,

2. Heat pump (1) according to claim 1, characterized in that said solenoid valve (19) is controlled by software means adapted to: - operate said heat pump (1) in direct mode as long as the duration of use of said heat pump (1) is less than a predetermined threshold value, said direct mode being obtained by positioning said solenoid valve (19) so as to supply only said heat exchanger (5) of said heating, ventilation and air conditioning device (3), - operate said heat pump (1) in indirect mode when the duration of use of said heat pump (1) is greater than said predetermined threshold value, said indirect mode being obtained by positioning said solenoid valve (19) so as to supply only said water circuit (21) supplying said air heater (7).

3. Heat pump (1) according to claim 2, characterized in that said software means is adapted to operate said heat pump (1) in hybrid mode after operation of said heat pump (1) in direct mode and before operation of said heat pump (1) in indirect mode, said mode hybrid being obtained by positioning said solenoid valve (19) so as to simultaneously supply said heat exchanger (5) of said heating, ventilation and air conditioning device (3) and said water circuit (21) supplying said air heater (7).

4. Method for managing a heat pump (1), said heat pump (1) being according to one of claims 2 or 3, said method being implemented by software means integrated in said motor vehicle and comprising the following steps aimed at: - operating said heat pump (1) in direct mode (step E10) as long as the duration of use of said heat pump (1) is less than a predetermined threshold value, said direct mode being obtained by positioning said solenoid valve (19) so as to supply only said heat exchanger (5) of said heating, ventilation and air conditioning device (3), - operating said heat pump (1) in indirect mode (step E20) when the duration of use of said heat pump (1) is greater than said predetermined threshold value,said indirect mode being obtained by positioning said solenoid valve (19) so as to supply only said water circuit (21) supplying said air heater (7).,

5. Method for managing a heat pump (1) according to claim 4, characterized in that it comprises an additional step, subsequent to said step aimed at operating said heat pump (1) in direct mode (step E10) and prior to said step aimed at operating said heat pump (1) in indirect mode (step E20), aimed at operating said heat pump (1) in hybrid mode (step E11), said hybrid mode being obtained by positioning said solenoid valve (19) so as to simultaneously supply said heat exchanger (5) of said heating, ventilation and air conditioning device (3) and said water circuit (21) supplying said air heater (7).

6. Management method according to one of claims 4 or 5, characterized in that said threshold value is determined as a function of the heat requirement necessary to reach a set temperature in the passenger compartment of said motor vehicle.

7. Management method according to claim 6, characterized in that said threshold value increases when said heat requirement increases.

8. Management method according to one of claims 4 or 5, characterized in that said threshold value is determined as a function of the outside temperature.

9. Management method according to claim 8, characterized in that said threshold value increases when the outside temperature decreases.

10. Management method according to any one of claims 4 to 9, characterized in that said threshold value is between approximately 5 minutes and approximately 20 minutes.

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