HEAT PUMP ARRANGEMENT FOR A HYBRID OR ELECTRIC VEHICLE

Description

Field of the invention

[0001] The present invention relates to a heat pump arrangement for a thermal management system of a hybrid or electric vehicle comprising a refrigerant circuit with a flow path for a refrigerant, a compressor, a high-pressure refrigerant heat exchanger integrated into a high-temperature latent heat storage device, an expansion element and a low-pressure refrigerant heat exchanger integrated into a low-temperature latent heat storage device. State of the art

[0002] The continuous development of hybrid or electric vehicles also includes the area of thermal management of such vehicles.

[0003] According to current technology, hybrid or electric vehicles require up to one-third of their energy storage capacity during winter operation to heat the passenger compartment and condition the energy storage device, in most cases a battery. Since an electric motor as the prime mover only provides minimal waste heat, a conventional electric heating resistor is often used in the simplest case to heat the passenger compartment. This drastically reduces the vehicle's range. A similar problem arises in summer when using a conventional air conditioning system in a hybrid or electric vehicle.

[0004] Various solutions already exist to address these problems and thus achieve optimized thermal management of the vehicle. One possibility, for example, is the use of a heat pump for heating. The air conditioning system often also covers this operating mode through additional heat exchangers, valves, and parallel refrigerant branches. Heat can be harnessed from various sources. An ambient heat pump, for example, can provide significantly more energy-efficient heating and cooling than a purely electric heater. However, these heat pumps only operate effectively at ambient temperatures above -5°C. Waste heat pumps are less dependent on the ambient temperature but also have problems in cold-start scenarios. Both variants, however, increase system complexity and thus also costs.

[0005] Latent heat storage, also called phase change storage, is already occasionally used in the thermal systems of hybrid and electric vehicles, but the required size and mass of the latent heat storage in current applications represent obstacles to further adoption.

[0006] For example, DE 10 2019 105 035 A1 discloses a heat pump arrangement that operates with two heat exchangers, each connected to a thermal storage unit in the form of a phase changer. This arrangement is used to cool and / or heat a vehicle.

[0007] For example, document DE 10 2017 120 195 A1 discloses a controllable, reversibly operable temperature regulation system for heating and cooling vehicles, comprising a refrigerant circuit with at least one first heat accumulator containing a phase-change material and at least one second heat accumulator containing a phase-change material. Furthermore, the refrigerant circuit comprises at least one first heat exchanger and at least one second heat exchanger.

[0008] For example, WO 2018 / 050139 A1 discloses a heating system for an at least partially electrically powered vehicle, wherein the heating system comprises at least one heat accumulator and at least one heating device with at least one heat exchanger. The at least one heating device is at least thermally coupled to the at least one heat accumulator.

[0009] DE 20 2010 007 146 U1, for example, describes an electric vehicle having a passenger compartment, a temperature control device for temperature control of the passenger compartment, and at least one first and at least one second latent heat accumulator, each having a storage medium, wherein the temperature control device has a heat pump with a warm side and a cold side, wherein the storage medium of the first latent heat accumulator is connected to the cold side in a heat-transferring manner for cooling the storage medium of the first latent heat accumulator, and wherein the storage medium of the second latent heat accumulator is connected to the warm side in a heat-transferring manner for heating the storage medium of the second latent heat accumulator. Summary of the invention

[0010] It is an object of the invention to provide an alternative heat pump arrangement for a thermal management system of a hybrid or electric vehicle, which is characterized on the one hand by energy-efficient operation and on the other hand by a performance-, installation space- and cost-optimized design.

[0011] This need can be met by the subject matter of the present invention according to independent claim 1. Advantageous embodiments of the present invention are described in the dependent claims.

[0012] The heat pump arrangement according to the invention is intended to be used in particular in a hybrid or electric vehicle, but it can also be used in any other common vehicle.

[0013] According to the present invention, the heat pump assembly comprises a refrigerant circuit. The refrigerant circuit has a flow path for a refrigerant, a compressor, a high-pressure refrigerant heat exchanger, an expansion element, and a low-pressure refrigerant heat exchanger.

[0014] There are no inherent restrictions regarding the refrigerant used. Standard refrigerants commonly used in the automotive sector, such as R1234yf, can be used. On the other hand, adaptation to specific operating requirements, such as pressure and temperature levels on the hot and cold sides of the heat pump, is also possible by selecting alternative refrigerants.

[0015] The compressor compresses the refrigerant from a low-pressure level to a high-pressure level. The compressor can be designed in various ways without affecting the basic principle of the invention. Preferably, the compressor is a turbo compressor of any design. The compressor operates at a largely constant, highly optimized operating point, thus achieving increased efficiency compared to conventional systems.

[0016] The high-pressure refrigerant heat exchanger is used to transfer heat from the refrigerant. The high-pressure refrigerant heat exchanger is integrated into a high-temperature latent heat storage unit. The melting point of the high-temperature latent heat storage unit is selected so that, on the one hand, the heat pump arrangement can operate at a highly efficient operating point in coordination with the selected refrigerant and the compressor design, and, on the other hand, the temperature level matches the requirements of a vehicle's thermal management system.

[0017] The expansion element serves to relax the cooled refrigerant to the low pressure level.

[0018] The low-pressure refrigerant heat exchanger is used to absorb heat from the refrigerant and is integrated into a low-temperature latent heat storage unit. The melting point of this low-temperature latent heat storage unit is selected based on the vehicle's thermal management system requirements and the efficient operation of the heat pump system.

[0019] In a heating mode, the high-temperature latent heat storage device is preferably coupled to a heating circuit of a vehicle's thermal management system, via which at least one passenger compartment of the vehicle can be heated. Furthermore, the heat can be used to condition the drive train, energy storage device, or other components of the vehicle. Heat is dissipated from the high-temperature latent heat storage device into a coolant of the heating circuit of the vehicle's thermal management system via a high-temperature coolant heat exchanger, which is also integrated into the high-temperature latent heat storage device. The high-temperature coolant heat exchanger is thermally coupled to the high-pressure refrigerant heat exchanger in the high-temperature latent heat storage device.

[0020] In the heating mode, the low-pressure refrigerant heat exchanger of the heat pump arrangement collects waste heat from the vehicle or heat from the environment.

[0021] In a cooling operating mode, the low-temperature latent heat storage device is preferably coupled to a cooling circuit of the vehicle's thermal management system, via which at least one passenger compartment of the vehicle can be cooled. Furthermore, other cooling requirements of the vehicle, for example, an energy storage device and / or the drive train, are covered via the cooling circuit. The heat absorption by the low-temperature latent heat storage device from a coolant of the cooling circuit of the vehicle's thermal management system takes place via a low-temperature coolant heat exchanger, which is also integrated into the low-temperature latent heat storage device. The low-temperature coolant heat exchanger is thermally coupled to the low-pressure refrigerant heat exchanger in the low-temperature latent heat storage device.

[0022] In the cooling mode, the high-pressure refrigerant heat exchanger releases the excess heat to the environment. In the present inventive embodiment of a heat pump arrangement, a highly efficient compressor can be utilized for the thermal management of a vehicle by combining it with a high-pressure and a low-pressure latent heat storage unit. This achieves constant temperatures on both the high-pressure and low-pressure sides of the compressor, thus enabling operation at a constant, highly efficient operating point of the heat pump arrangement. This increases the efficiency of the heat pump arrangement and thus the thermal management of a vehicle, in particular a hybrid or electric vehicle. In a hybrid or electric vehicle, this means an increase in the range in electric driving mode.

[0023] During partial load operation of the heat pump arrangement according to the invention, the compressor can also be temporarily switched off, but heat and cold can still be extracted from the two latent heat storage units. This enables almost silent, highly energy-efficient operation.

[0024] During full-load operation, the maximum heat and cooling output extracted can temporarily significantly exceed the actual output of the heat pump arrangement due to the buffer effect of the two latent heat storage units, which represents another significant advantage of the system.

[0025] Furthermore, the invention enables a completely modular design of the heat pump arrangement, refrigerant lines and thus also refrigerant filling quantities can be minimized and the integration into overall thermal management systems is greatly simplified.

[0026] By using two latent heat storage units on the high- and low-pressure sides, the compressor, as the central component of the system, can operate at a constant, energy-optimized operating point. This allows for significantly increased efficiencies compared to conventional mobile systems, especially when using a turbo compressor, which can only be used under the boundary condition of a constant operating point.

[0027] Existing technical solutions use the phase-change materials of latent heat storage exclusively as heat storage devices, which, in order to absorb significant amounts of energy, must be very large and heavy. In the present invention, the phase-change materials of the latent heat storage devices primarily serve the role of buffers, stabilizing the temperature and pressure levels of the compressor and, as a result, can be designed significantly smaller and lighter. Brief description of the drawings

[0028] The invention is described below by way of example with reference to the drawings. Fig. 1 shows a schematic representation of a heat pump arrangement. Fig. 2 shows a schematic representation of a heat pump arrangement according to the invention according to Fig. 1 , wherein the heat pump arrangement is coupled to a heating and a cooling circuit of a thermal management system of a vehicle. Fig. 3 shows a heat pump arrangement according Fig. 2 with active cooling circuit. Fig. 4 shows a heat pump arrangement according Fig. 2 with active heating circuit. Detailed description of the invention

[0029] In Fig. 1 A heat pump arrangement 1 according to the present invention is shown schematically.

[0030] The heat pump assembly 1 is part of a thermal management system of a vehicle, wherein the thermal management system of the vehicle has a heating circuit and a cooling circuit. Both the heating circuit and the cooling circuit include a flow path for a coolant.

[0031] The heat pump assembly 1 comprises a closed refrigerant circuit 2. The refrigerant circuit 2 comprises a flow path for a refrigerant, a compressor 3, a high-pressure refrigerant heat exchanger 4, an expansion element 5, a low-pressure refrigerant heat exchanger 6, and an accumulator / expansion tank 13.

[0032] The high-pressure refrigerant heat exchanger 4 is integrated into a high-temperature latent heat storage unit 10 and functionally forms a condenser.

[0033] The low-pressure refrigerant heat exchanger 6 is integrated into a low-temperature latent heat storage unit 12 and functionally forms an evaporator.

[0034] The accumulator / expansion tank 13 ensures that the compressor 3 is only supplied with refrigerant in the gas phase.

[0035] In the present embodiment, compressor 3 is designed as a turbocompressor, but can be designed as any compressor. Compressor 3 has a low-pressure inlet 7 on the low-pressure side, i.e., the evaporator side, and a high-pressure outlet 8 on the high-pressure side, i.e., the condenser side.

[0036] The expansion element 5 is designed either as an adjustable valve or as a throttle.

[0037] During operation of the heat pump arrangement 1, the compressor 3 draws in low-pressure refrigerant from the accumulator / expansion tank 13 via the low-pressure inlet 7. The refrigerant supplied to the compressor 3 via the low-pressure inlet 7 is compressed by the compressor 3 and thus brought to a high-pressure level. The high-pressure refrigerant is supplied to the high-pressure heat exchanger 4 via the high-pressure outlet 8, where it is cooled while releasing heat to the high-temperature latent heat storage device 10. The refrigerant cooled by the high-pressure refrigerant heat exchanger 4 is expanded to a low-pressure level via the expansion element 5. The refrigerant is then reheated in the low-pressure refrigerant heat exchanger 6 while absorbing heat and is supplied to the accumulator 13.

[0038] In addition to the high-pressure refrigerant heat exchanger 4, a high-temperature coolant heat exchanger 9 is also integrated into the high-temperature latent heat storage unit 10, which is part of the heating circuit of the vehicle's thermal management system.

[0039] In addition to the low-pressure refrigerant heat exchanger 6, a low-temperature coolant heat exchanger 11 is also integrated into the low-temperature latent heat storage unit 12, which is part of the cooling circuit of the vehicle's thermal management system.

[0040] The thermal management system of the vehicle can be cooled via the low-temperature coolant heat exchanger 11 by the low-temperature latent heat storage 12 and heated via the high-temperature coolant heat exchanger 9 by the high-temperature latent heat storage 10.

[0041] In Fig. 2 to Fig. 4The integration of a heat pump arrangement 1 into a thermal management system of a vehicle, more precisely an electric vehicle, is shown schematically, wherein the high-pressure refrigerant heat exchanger 4 can be coupled via the high-temperature latent heat storage 10 and the high-temperature coolant heat exchanger 9, and the low-pressure refrigerant heat exchanger 6 can be coupled via the low-temperature latent heat storage 12 and the low-temperature coolant heat exchanger 11, depending on the operating mode, either to a cooling circuit or a heating circuit of the vehicle. Fig. 3 is schematically the function of the heat pump arrangement 1 with active cooling circuit and in Fig. 4 The function of the heat pump arrangement 1 with the heating circuit active is shown schematically.

[0042] A high-pressure side 14 of the heat pump assembly 1 provides warm coolant, and a low-pressure side 15 of the heat pump assembly 1 provides cold coolant. The following components and assemblies must be thermally conditioned on the vehicle side: An electric drive train 17 (engine, power electronics, charger, and, depending on the application, also the transmission) generates waste heat during operation, which must be dissipated by the thermal management system. A battery 18 generates waste heat during operation and charging processes, which must also be compensated for by suitable cooling. For example, during cold start conditions in winter, the battery can also be heated by the thermal management system. A passenger compartment 23 is supplied with warm or cold air via the so-called "HVAC box," which is blown into the interior of the passenger compartment via outlet nozzles. The cooling or heating power required for this is Fig. 2This is achieved via a heat exchanger 20, through which hot or cold coolant can flow as required. Air flows through a radiator 21 in the front of the vehicle, dissipating excess heat from the thermal management system to the environment. Two pumps 22a, 22b provide the coolant mass flow required for operation. An additional air-side electric auxiliary heater 19 in the "HVAC box" is used in the dehumidification mode of the air conditioning system to reheat the air, which has only been cooled in the heat exchanger 20 (to achieve condensation of the humidity), to the desired inflow temperature into the passenger compartment 23. In addition, the electric auxiliary heater 19 provides a "backup" solution for situations in which insufficient heating power is available from the heat pump arrangement 1 in winter, or where a particularly rapid warm-up of the passenger compartment 23 is desired.

[0043] All these heating and cooling requirements are Fig. 2 by the heat pump arrangement 1. The necessary connections between heat sources and heat sinks are represented by a central valve block 16. This contains two 4-way rotary valves V1, V2, which can represent all required operating modes by rotating together, so that a joint control of these 4-way rotary valves V1, V2 is possible via only one actuator. Furthermore, the valve block 16 contains two 3-way valves V3, V4, which Fig. 2 The system branches located to the right can be decoupled from the rest of the thermal management system. Three additional 3-way valves V5, V6, and V7 within the system branches allow individual system components to be bypassed if their flow with coolant is not required or desired.

[0044] Fig. 3now shows the application of the heat pump arrangement 1 for cooling the passenger compartment 23 and the battery 18. The low-pressure side 14 of the heat pump arrangement 1 provides cold coolant, which is fed into the heat exchanger 20 via the valve V2 and a coolant pump 22b. There, the air flowing into the passenger compartment 23 cools down, thus enabling cooling of the passenger compartment 23. The coolant flowing on from this heat exchanger 20 is accordingly slightly warmed up (it has absorbed heat from the air), but is still cool enough to provide cooling for the vehicle's battery 18. The warmed coolant is then fed back to the low-pressure side 15 of the heat pump arrangement 1 via the 3-way valve V4 and the 4-way rotary valve V1, where the absorbed heat is transferred to the circuit of the heat pump arrangement 1, closing the circuit.On the high-pressure side 14 of the heat pump assembly 1, this heat is conducted as hot coolant via the 4-way rotary valve V2 and the coolant pump 22a to the vehicle's radiator 21, where it is dissipated to the environment. The cooled coolant is then used to cool the vehicle's drive train 17 and is then conducted back to the high-pressure side 14 of the heat pump assembly 1 via the 3-way valve V3 and the 4-way rotary valve V1. This completes the cooling system cycle.

[0045] Fig. 4shows the application for heating the passenger compartment 23 and optionally the battery 18. For this purpose, hot coolant is passed from the high-pressure side 14 of the heat pump arrangement 1 via the 4-way rotary valve V2, now rotated by 90°, and the coolant pump 22b to the heat exchanger 20. There, the coolant transfers heat to the air flowing into the passenger compartment 23, thus heating the latter. The remaining heat in the coolant can then either be used to heat the battery 18, or the battery 18 can be bypassed via the 3-way valve V6 if there is no heating demand. The coolant then flows via the 3-way valve V4 and the 4-way rotary valve V1 and back to the high-pressure side 14 of the heat pump arrangement 1, where new heat is absorbed and the cycle is closed.On the low-pressure side 15 of the heat pump assembly 1, cold coolant flows through the 4-way rotary valve V2 and the coolant pump 22a through the vehicle's drive train 17, where waste heat is absorbed. The thus warmed coolant is returned to the low-pressure side 15 of the heat pump assembly 1 via the 3-way valve V3 and the 4-way rotary valve V1, where this waste heat is transferred to the heat pump assembly 1 and provides the necessary heat input for heating the passenger compartment 23 and the battery 18. Under sufficiently warm ambient conditions, the coolant can also flow through the radiator 21 in this circuit to absorb further heat from the environment and supply it to the heat pump assembly 1. List of reference symbols

[0046] 1 Heat pump arrangement 2 Refrigerant circuit 3 Turbo compressor 4 High-pressure heat exchanger 5 Expansion element 6 Low-pressure heat exchanger 7 Low-pressure inlet 8 High-pressure outlet 9 High-temperature coolant heat exchanger 10 High-temperature latent heat storage 11 Low-temperature coolant heat exchanger 12 Low-temperature latent heat storage 13 Refrigerant expansion tank 14 High-pressure side (of the heat pump arrangement) 15 Low-pressure side (of the heat pump arrangement) 16 Central valve block 17 Drive train 18 Battery 19 Electric auxiliary heater (air side) 20 Heat exchanger 21 Radiator 22a, 22b Pump 23 Passenger compartment V1, V24-way rotary valve V3, V4, V5, V6, V73-way valve

Claims

1. Heat pump assembly (1) for a thermal management system of a hybrid or electric vehicle, comprising a refrigerant circuit (2), wherein the refrigerant circuit (2) - a flow path for a refrigerant, - a compressor (3) for compressing the refrigerant from a low pressure level to a high pressure level, - a high-pressure refrigerant heat exchanger (4) for dissipating heat from the refrigerant, the high-pressure refrigerant heat exchanger (4) being integrated into a high-temperature latent heat accumulator (10), - an expansion element (5) for expanding the cooled refrigerant to the low pressure level and - a low-pressure refrigerant heat exchanger (6) for absorbing heat from the refrigerant, the low-pressure refrigerant heat exchanger (6) being integrated into a low-temperature latent heat accumulator (12), characterized in that the necessary connections between heat sources and heat sinks are represented by a central valve block (16), the central valve block comprising two 4-way rotary valves (V1, V2), which can represent all the required operating modes by joint rotation.

2. Heat pump assembly (1) according to Claim 1, characterized in that the valve block (16) has two 3-way valves (V3, V4), which couple and decouple system branches from the rest of the thermal management system.

3. Heat pump assembly (1) according to Claim 1 or 2, characterized in that three further 3-way valves within the system branches allow bridging of individual system components if it is not necessary or desired for coolant to flow through the system components.

4. Heat pump assembly (1) according to any of the preceding claims, characterized in that the compressor (3) is designed as a turbo compressor.

5. Heat pump assembly (1) according to any of the preceding claims, characterized in that the high-temperature latent heat accumulator (10) is coupled to a heating circuit via which at least one passenger compartment (23) of the vehicle can be heated.

6. Heat pump assembly (1) according to Claim 5, characterized in that the heating circuit has a high-temperature coolant heat exchanger (9) which, in the high-temperature latent heat accumulator (10), is coupled to the high-pressure refrigerant heat exchanger (4).

7. Heat pump assembly (1) according to any of Claims 1 to 6, characterized in that the low-temperature latent heat accumulator (12) is coupled to a cooling circuit via which at least one passenger compartment (23) of the vehicle can be cooled.

8. Heat pump assembly (1) according to Claim 7, characterized in that the cooling circuit has a low-temperature coolant heat exchanger (11) which, in the low-temperature latent heat accumulator (12), is coupled to the low-pressure refrigerant heat exchanger (6).