Cooling system with at least one displacement pump and vehicle with the cooling system

Abstract

A cooling system 2 for an electric or hybrid vehicle 1 is proposed, comprising at least one coolant circuit 3 for tempering at least one drive component 5, 6, 7 and / or a vehicle cabin 8 of the vehicle 1, wherein a coolant pump 10 is provided in the coolant circuit 3 for conveying a coolant through the coolant circuit 3, wherein the coolant pump 10 is designed as a positive displacement pump 11.

Description

[0001] The invention relates to a cooling system for an electric or hybrid vehicle having the features of the preamble of claim 1. Furthermore, the invention relates to a vehicle having the cooling system.

[0002] Purely electric or hybrid-powered vehicles with one or more electric motors are known. These are supplied with electrical energy from an energy storage system, particularly a drive battery, via power electronics. In this case, heat energy is generated in the high-voltage components of the power electronics and the energy storage system, as well as in the electric motor, which is dissipated via one or more cooling circuits.

[0003] The document DE 10 2021 132 679 A1 discloses a BEV with a thermal management system, comprising an external coolant circuit with a coupling heat exchanger and a radiator for dissipating heat to the environment and an electric motor for propulsion, and comprising an internal coolant circuit with a traction battery and an interior heat exchanger, wherein a 4-way valve and a 3-way valve connect the internal coolant circuit to the external coolant circuit.

[0004] The object of the invention is to create a cooling system of the type mentioned above, which is characterized by a compact design and reliable cooling.

[0005] This object is achieved according to the invention by a cooling system having the features of claim 1 and an electric or hybrid vehicle having the features of claim 15. Advantageous embodiments emerge from the subclaims, the drawings and / or the description.

[0006] The subject matter of the invention is a cooling system which is designed and / or suitable for an electric or hybrid vehicle. In particular, the cooling system serves to regulate the temperature of temperature-critical drive components of a drive train of the vehicle. Alternatively or optionally additionally, the cooling system serves to regulate the temperature of a vehicle cabin of the vehicle. For this purpose, the cooling system has at least or exactly one coolant circuit which is designed and / or suitable for controlling the temperature of at least or exactly one drive component of the vehicle and / or the vehicle cabin. In particular, the coolant circuit is operatively connected to the drive component and / or the vehicle cabin in such a way that heat can be dissipated via the coolant circuit for cooling and / or heat can be supplied via the coolant circuit for heating. In other words, temperature control within the meaning of the invention is to be understood as heating and / or cooling.In other words, the at least one drive component and / or the vehicle cabin is heated, cooled, or kept at a constant temperature during temperature control. For this purpose, the coolant circuit can be used directly to temperature control the at least one drive component and / or the vehicle cabin. Alternatively, however, the coolant circuit can also be thermally coupled indirectly via another coolant or oil circuit for temperature control of the drive component and / or another coolant or refrigerant circuit for temperature control of the vehicle cabin. In particular, the waste heat of at least one drive component can be used to temperature control another drive component and / or the vehicle cabin by means of the coolant circuit.

[0007] A coolant pump is provided in the coolant circuit, which is designed and / or suitable for conveying a coolant through the coolant circuit. The coolant is preferably a water-based coolant. The coolant pump can be designed as an electrically operated coolant pump. The cooling system preferably has a control unit designed to control and / or regulate the coolant pump as needed. The cooling system preferably has at least or precisely one detection unit for detecting an operating parameter, in particular a temperature, of the drive component and / or the vehicle cabin, wherein the control unit is designed to control and / or regulate the coolant pump based on the operating parameter.

[0008] Within the scope of the invention, it is proposed that the coolant pump is designed as a positive displacement pump. In particular, a positive displacement pump is understood to be a pump that operates according to the principle of volume displacement. For this reason, positive displacement pumps are also referred to as volumetric pumps. For this purpose, the positive displacement pump captures a limited amount of coolant and conveys it from a suction side to a pressure side. In other words, the coolant is sucked in on the suction side by a vacuum and pushed out or displaced again on the pressure side by pressure. In particular, the positive displacement pump is designed to generate an at least approximately constant volume flow regardless of the pressure and / or to convey a volume flow proportional to the speed.

[0009] The invention is based on the finding that centrifugal pumps are generally used in vehicle cooling circuits. In order to ensure that the coolant is circulated by a centrifugal pump, the line cross-sections must be sufficiently large to keep the pressure drop as low as possible. This leads to larger fill volumes and thus to increased weight and installation space requirements. In addition, the volumetric efficiency of the circular pump decreases disproportionately with increasing pressure until the surge limit is reached and the efficiency is 0%, i.e. the volumetric flow comes to a standstill. A compromise must therefore be found between volumetric flow and pressure requirement. This is complex and associated with restrictions, particularly when components to be cooled are integrated in different ways. An additional "booster" pump must also be installed to ensure that the coolant is pumped even at high volumetric flows.

[0010] The advantage of the invention is that by using a positive displacement pump, the line cross-sections can be reduced compared to conventional cooling systems with centrifugal pumps, whereby the fill volume of the coolant circuit can be reduced by up to 40%. For example, this can be achieved if, instead of a conventional line diameter of 16 mm, a reduced line diameter of less than 14 mm, preferably less than 13 mm, is provided. Although this causes a disproportionate increase in pressure loss, the absolute power requirement in the 99% operating conditions is generally negligible, since the low volume flows mean that the pressure losses are low in absolute terms. The use of volumetric positive displacement pumps also enables a higher pressure difference across the pump, whereby a high volume flow can be ensured through higher pressure. If high volume flows are required, e.g.To ensure the cooling performance of the components, the power requirement increases significantly, but the time spent in these operating states is often negligible. With positive displacement pumps, the flow rate is almost proportional to the speed, so different resistances only lead to corresponding pressure level differences.

[0011] In one specific embodiment, the coolant pumped by the positive displacement pump is a water-glycol mixture. In other words, a mixture of water and glycol, preferably ethylene glycol, is used as the coolant. To prevent overheating and wear of the positive displacement pump, the coolant must have a certain lubricating effect. The use of glycol, especially ethylene glycol, can significantly improve the lubricating properties of the coolant and, in addition, prevent the coolant circuit from freezing at low outside temperatures and when the vehicle is idle.

[0012] In a more specific embodiment, the water-glycol mixture contains at least 50 vol.% water and / or at least 50 vol.% glycol. Preferably, the water-glycol mixture contains less than 50 vol.% water and / or more than 50 vol.% glycol. Simply put, the glycol content is greater than or equal to the water content. Thus, a coolant with sufficient lubricating properties for delivery by a positive displacement pump is proposed.

[0013] In a further development, at least or exactly one pressure relief valve is provided in the coolant circuit in order to limit a fluid pressure generated on the pressure side of the positive displacement pump, taking into account the pressure load capacity of individual components provided on the pressure side. In particular, the pressure relief valve is designed to automatically throttle and / or regulate the volume flow on the pressure side as a function of the fluid pressure. For this purpose, the pressure relief valve is preferably arranged on the pressure side or, in terms of flow, downstream of the positive displacement pump. The pressure relief valve can be designed as a passive, in particular pressure-controlled valve. For example, the pressure relief valve can be designed as a ball valve, plate valve, or cone valve with or without spring loading. In particular, the pressure relief valve is arranged fluidically upstream of the most pressure-sensitive component.Alternatively, or optionally in addition, each pressure-sensitive component is assigned a separate pressure relief valve. Alternatively, or optionally in addition, the most pressure-sensitive component is arranged at the end of the coolant circuit. When using a positive displacement pump, the fluid pressure on the pressure side must be limited, taking into account the pressure load capacity of one or more pressure-sensitive components of the cooling circuit, such as heat exchangers. By using a pressure relief valve, a maximum pressure on the pressure side can be easily limited or adjusted.

[0014] In one specific embodiment, the at least one pressure relief valve is fluidly connected to a suction side of the positive displacement pump via a pressure relief line. In other words, the pressure relief line serves to return excess coolant from the pressure side to the suction side. In principle, the pressure relief line can be connected directly to a suction line of the coolant circuit. However, the pressure relief line is preferably connected indirectly, preferably via an expansion tank, to the suction line of the coolant circuit. This ensures a sufficient amount of coolant on the suction side and thus adequate lubrication of the positive displacement pump. In simple terms, dry running of the positive displacement pump is prevented.

[0015] In a further specific embodiment, an expansion tank is provided in the coolant circuit, which is fluidly connected to the suction side of the positive displacement pump via a compensation line, wherein the overpressure line opens into the expansion tank. In particular, the expansion tank serves to compensate for volume fluctuations of the coolant carried in the coolant circuit. In particular, several, preferably all, overpressure lines of the pressure relief valves provided in the coolant circuit open into the expansion tank. The expansion tank can be designed either as an open container, for example a pan, or a closed container, for example a tank. This ensures a continuous coolant supply to the positive displacement pump and compensates for volume fluctuations in a simple manner.

[0016] In a further specific embodiment, it is provided that the positive displacement pump has a pump housing having a suction-side inlet and a pressure-side outlet, in which at least or exactly one displacement body is arranged, wherein the pump housing and / or the displacement body has a self-lubricating material at least in one contact area. A displacement body is the part of the positive displacement pump which is moved, preferably rotated, within the pump housing to displace or convey the coolant. The contact area is the area in which the displacement body is in mechanical contact with the pump housing and / or several, preferably two, displacement bodies are in mechanical contact with one another. In principle, a self-lubricating material can be either a material with a low coefficient of friction, such as ceramic, or a material with an embedded solid lubricant, such as polyurethane.B. graphite. The pump housing and / or the displacement body can be made of the self-lubricating material or coated with the self-lubricating material. Due to a lack of lubricating effect of the coolant, the positive displacement pump can be exposed to overheating and excessive wear at higher speeds, especially during full-load operation, which can lead to damage to the positive displacement pump. The self-lubrication of the components in the contact area can reduce wear, especially during full-load operation of the positive displacement pump, and also improve friction and thus the efficiency of the pump. This can enable a long service life for the pump.

[0017] In a specific implementation, the positive displacement pump is designed as a gear pump or a vane pump. In particular, a positive displacement pump designed as a gear pump has two displacement bodies designed as gears. The gear pump is preferably designed as an external gear pump, an internal gear pump, also called a sickle cell pump, or a gear ring pump, also called a gerotor pump. Gear pumps are preferably characterized by uniform delivery of the coolant and a cost-effective and robust design. In particular, a positive displacement pump designed as a vane pump, also called a rotary vane pump, has a displacement body designed as a rotor, which is arranged eccentrically in the pump housing and has one or more radially displaceable rotary vanes. Vane pumps are preferably characterized by low volume flow pulsation and a cost-effective design.

[0018] In a specific implementation, it is provided that the at least one drive component to be temperature-controlled is at least thermally coupled to the coolant circuit. In particular, the drive component can be thermally connected to the coolant circuit via a heat exchanger provided in the coolant circuit. Alternatively, however, the coolant can also flow directly through or around the drive component. For this purpose, the drive component can have one or more cooling channels for the coolant. This enables particularly simple and space-saving cooling of the drive component.

[0019] In a specific embodiment, it is provided that the drive component is designed as an electronics unit, preferably power electronics and / or charging electronics, and / or a drive unit, preferably a drive motor and / or a transmission, and / or an energy storage device of the electric vehicle. In particular, the power electronics transmits the traction energy from the energy storage device, in particular a traction battery, to the drive motor and in the process converts the current from direct current into alternating current. Preferably, the drive motor is designed as an electric machine and the transmission as a transmission gear. Particularly preferably, the coolant circuit is designed as a drive cooling circuit, which is designed to dissipate the heat loss generated in the mechanical and electronic drive components of the drive train during operation and the charging process.By connecting one or more of the drive components to the coolant circuit, efficient cooling and / or heating can be achieved.

[0020] In a further development, it is provided that at least one temperature control unit is present in the coolant circuit, which is designed and / or suitable for temperature control of the drive component and / or the vehicle cabin. In particular, the temperature control unit is designed as a heat pump or an air conditioning system. For this purpose, the temperature control unit preferably has a refrigerant circuit which is thermally coupled to the coolant circuit, preferably via a heat exchanger. In particular, waste heat from the coolant circuit can be used by the temperature control unit for temperature control. Optionally, the temperature control unit can be used to support heat dissipation from the drive components. For example, the coolant circuit can be thermally coupled to an evaporator and / or condenser of the heat pump or the air conditioning system. As a result, the thermal energy of the coolant circuit can be efficiently used by the temperature control unit to temperature control the vehicle cabin orone or more drive components are used.

[0021] In a further embodiment, the cooling system has a further coolant circuit which is designed and / or suitable for dissipating heat from the coolant circuit to an external environment. For this purpose, a heat sink for dissipating heat to the external environment and a further coolant pump for conveying the coolant or a further coolant through the coolant circuit are provided in the further coolant circuit, wherein the first coolant circuit and the at least one further coolant circuit are at least thermally coupled to one another. In principle, the two coolant circuits can be separated from one another in terms of flow or fluid technology. Alternatively, however, the two coolant circuits can also be connected to one another in terms of flow or fluid technology, such that the two coolant circuits contain the same coolant. The heat sink is preferably designed as a radiator or cooler.In particular, the cooling system has precisely two coolant circuits. Optionally, the cooling system can have a further coolant circuit, which is provided for dissipating heat from a lubrication and / or cooling oil system of the transmission and / or an internal combustion engine.

[0022] In a more specific embodiment, the additional coolant pump is designed as an additional positive displacement pump. Preferably, the additional positive displacement pump is structurally identical to the positive displacement pump or is designed as previously described. Preferably, the coolant pumped by the additional positive displacement pump is a water-glycol mixture. This also allows the line diameters of the additional cooling circuit to be reduced, thus saving additional space and weight.

[0023] In a further specification, it is provided that the coolant circuit and the additional coolant circuit are fluidly connected and / or connectable to one another via a multi-way valve to form a thermal management system. In particular, the multi-way valve serves to control heat flows of the two cooling circuits by directing the fluid flows in different directions or assigning them to different circuits. Preferably, the multi-way valve forms an interface between the coolant circuits, wherein the volume flows of the two coolant circuits can be mixed as required by changing the valve position. In particular, the multi-way valve is designed as a 4-way valve. This proposes a particularly efficient cooling system that can interconnect the coolant circuits accordingly depending on the heating or cooling requirements.

[0024] Another subject of the invention relates to an electric or hybrid vehicle with the cooling system as described above. The vehicle preferably comprises the drive unit, the electronics unit, and the energy storage device as the drive components, as well as the vehicle cabin.

[0025] Further features, advantages, and effects of the invention will become apparent from the following description of preferred embodiments. In the following: Fig. 1 a vehicle with two coolant circuits as an embodiment of the invention.

[0026] Fig. Figure 1 shows a highly schematic representation of a vehicle 1, only schematically indicated, with a cooling system 2 comprising two coolant circuits 3, 4. The vehicle 1 is designed, for example, as an electric vehicle.

[0027] The vehicle 1 has a drive unit 5, comprising an electric motor, reduction gear, bearings, etc., an electronics unit 6, comprising an inverter, DC / DC converter, DC-AC converter, etc., and an energy storage device 7, in particular a traction battery, as drive components to be temperature-controlled. For this purpose, the drive components 5, 6, 7 are thermally coupled to the coolant circuit 3.

[0028] Furthermore, the vehicle 1 has a vehicle cabin 8 to be temperature-controlled, which is thermally coupled to the coolant circuit 3 via a temperature control unit 9. The temperature control unit 9 can be designed as a heat exchanger or air conditioning system with its own coolant circuit (not shown). The temperature control unit 9 serves to temperature-control the vehicle cabin 8 and, optionally, additionally to temperature-control one or more of the drive components 5, 6, 7. Temperature control here refers to heating, cooling, or maintaining a constant temperature.

[0029] The coolant circuit 3 has a coolant pump 10 designed as a positive displacement pump 11, which is provided for conveying a coolant in the coolant circuit 3. The positive displacement pump 11 has a pump housing 12, which is connected on the inlet side to a suction line 13 and on the outlet side to a pressure line 14, and in which at least one displacement body (not shown) is arranged. The displacement body is moved, preferably rotated, in the pump housing 12 in order to suck the coolant from the suction line 13 using a vacuum and to force it into the pressure line 14 using pressure. For example, the positive displacement pump can be designed as a gerotor, gear, sickle cell, vane cell, or impeller pump.

[0030] The coolant is a water-based cooling liquid, for example a water-glycol mixture. Depending on the mixing ratio of the water-glycol mixture, the lubricating effect of the coolant may not be sufficient, particularly at higher speed ranges of the positive displacement pump 11. Therefore, the pump housing 12 and / or the displacement body are formed from or coated with a self-lubricating material at least in one contact area, or the material pairing ensures comparable properties. This can reduce friction in the contact area or, in the event of mechanical wear, create mixed friction through a solid lubricant present in the material. For example, the self-lubricating material can be a ceramic or a graphite-containing plastic.

[0031] On the pressure side of the positive displacement pump 11, the electronics unit 6, the drive unit 5, the energy storage unit 7, and the temperature control unit 9 are arranged fluidically one behind the other and are each thermally coupled to the coolant circuit 3, so that heat is dissipated along a flow path by the coolant. For example, the waste heat from the electronics unit 6 and the drive unit 5 can be used to control the temperature of the energy storage unit 7 and / or by the temperature control unit 9 to control the temperature of the vehicle cabin 8.

[0032] Furthermore, a heat sink 15 for dissipating heat to the outside environment and a further coolant pump 16 designed as a further positive displacement pump 17 are provided in the further coolant circuit 4. The further coolant circuit 4 serves to dissipate heat from the coolant circuit 3 to the outside environment via the heat sink 15, wherein the heat sink 15 is designed, for example, as a radiator. For this purpose, the two coolant circuits 3, 4 are thermally coupled via a heat exchanger 18, only schematically indicated, or fluidically via a multi-way valve 19, only schematically indicated, to form a thermal management system. With a thermal coupling of the two coolant circuits 3, 4, a further coolant, preferably a water-glycol mixture, is pumped by the further positive displacement pump 17 in the further coolant circuit 4. Alternatively, the two coolant circuits 3, 4 comprise the same coolant when fluidically coupled.For example, the two positive displacement pumps 11, 17 are of identical design.

[0033] The coolant circuits 3, 4 each have at least one pressure relief valve 20a, 20b, 20c, each of which limits a maximum fluid pressure on the pressure side of the respective positive displacement pump 11, 17. The use of a positive displacement pump 11, 17 can result in high fluid pressures on the pressure side when coolant is required, e.g., during full-load operation. These pressures must be limited taking into account the pressure load capacity of the drive components 5, 6, 7, the temperature control unit 9, and the heat sink 15. For this purpose, a first pressure relief valve 20a can be assigned to the drive components 5, 6, 7, a second pressure relief valve 20b to the temperature control unit 9, and a third pressure relief valve 20b to the heat sink 15, via which the fluid pressures can be adjusted independently of one another according to the pressure load capacity of the individual components. For example, the pressure relief valves 20a, 20b, 20c are each designed as a passive, pressure-controlled valve.

[0034] The two pressure relief valves 20a, 20b of the coolant circuit 3 are each fluidly connected via a pressure relief line 21a, 21b to an equalizing tank 22a, which is fluidly integrated into the suction line 13a, preferably an intake area, via a compensation line 23a to compensate for a coolant volume on the suction side of the positive displacement pump 11. The pressure relief valve 20c of the further coolant circuit 4 is also fluidly connected via a corresponding pressure relief line 21c to a further equalizing tank 22b, which is fluidly integrated into a further suction line 13b, preferably an intake area, via a further compensation line 23b to compensate for a coolant volume on the suction side of the further positive displacement pump 17. Reference symbol 1 vehicle 2 Cooling system 3 Coolant circuit 4 additional coolant circuit 5 Drive unit 6 Electronic unit 7 Energy storage 8 Vehicle cabin 9 Temperature control unit 10 Coolant pump 11 Positive displacement pump 12 pump housing 13a, b suction lines 14a, b pressure lines 15 heat sink 16 additional coolant pumps 17 additional displacement pumps 18 heat exchangers 19 Multi-way valve 20a-c pressure relief valves 21a-c Overpressure lines 22a, b expansion tank 23a, b Compensating lines QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 132 679 A1

[0003]

Claims

[1] Cooling system (2) for an electric or hybrid vehicle (1), - with at least one coolant circuit (3) for tempering at least one drive component (5, 6, 7) and / or a vehicle cabin (8) of the vehicle (1), wherein a coolant pump (10) is provided in the coolant circuit (3) for conveying a coolant through the coolant circuit (3), characterized by that the coolant pump (10) is designed as a positive displacement pump (11). [2] Cooling system (2) according to claim 1, characterized by that the coolant pumped by the positive displacement pump (11) is a water-glycol mixture. [3] Cooling system (2) according to claim 2, characterized by that the water-glycol mixture contains at least 50 vol% glycol. [4] Cooling system (2) according to one of the preceding claims, characterized bythat at least one pressure relief valve (15a, 15b) is provided in the coolant circuit (3) in order to limit a fluid pressure generated on the pressure side of the positive displacement pump (11), taking into account a pressure load capacity of individual components of the coolant circuit (3) provided on the pressure side. [5] Cooling system (2) according to claim 4, characterized by that the at least one pressure relief valve (20a, 20b) is fluidically connected to a suction side of the positive displacement pump (11) via a pressure relief line (21a, 21b). [6] Cooling system (2) according to claim 5, characterized by that an equalizing tank (22a) is provided in the coolant circuit (3), which is fluidically connected to the suction side of the positive displacement pump (11) via an equalizing line (23a), wherein the overpressure line (21b) opens into the equalizing tank (22a). [7] Cooling system (2) according to one of the preceding claims, characterized bythat the positive displacement pump (11) has a pump housing (12) having a suction-side inlet and a pressure-side outlet, in which at least one rotating displacement body is arranged, wherein the pump housing (12) and / or the displacement body has a self-lubricating material at least in one contact area. [8] Cooling system (2) according to one of the preceding claims, characterized by that the positive displacement pump (11) is designed as a gear pump or a vane pump. [9] Cooling system (2) according to one of the preceding claims, characterized by that the at least one drive component (5, 6, 7) to be tempered is thermally coupled to the coolant circuit (3). [10] Cooling system (2) according to claim 9, characterized by that the drive component (5, 6, 7) is designed as an electronic unit (6) and / or a drive unit (5) and / or an energy store (7) of the vehicle (1). [11] Cooling system (2) according to one of the preceding claims, characterized by that the coolant circuit (3) is thermally coupled to a temperature control unit (9) for temperature control of the drive component (5, 6, 7) and / or the vehicle cabin (8). [12] Cooling system (2) according to one of the preceding claims, characterized by a further coolant circuit (4) for dissipating heat from the coolant circuit (3) to an external environment, wherein a heat sink (15) for dissipating heat to the external environment and a further coolant pump (16) for conveying the coolant or a further coolant through the further coolant circuit (4) are provided in the further coolant circuit (4), wherein the coolant circuit (3) and the further coolant circuit (4) are at least thermally coupled to one another. [13] Cooling system (2) according to claim 12, characterized by that the further coolant pump (16) is designed as a further displacement pump (17). [14] Cooling system (2) according to claim 12 or 13, characterized by that the coolant circuit (3) and the further coolant circuit (4) are fluidically connected and / or connectable to one another via a multi-way valve (19) to form a thermal management system. [15] Electric or hybrid vehicle (1) with the cooling system (2) according to one of the preceding claims.

Images