THERMAL MANAGEMENT SYSTEM AND VEHICLE

Description

[0001] The invention relates to a thermal management system for a vehicle. The invention further relates to a vehicle with such a thermal management system.

[0002] A vehicle is defined as any type of vehicle that includes a battery that requires temperature control and an electric motor or e-motor that powers the vehicle. The battery can be air-cooled and / or coolant-, coolant-, or water-cooled. The electric motor, on the other hand, can be either oil-cooled or both coolant-, coolant-, or water-cooled and oil-cooled. This can be a partially electric or fully electric vehicle, but in particular, passenger cars and / or commercial vehicles.

[0003] From EP 2392486 B1 a thermal management system is known which has a first coolant circuit for controlling the temperature of a battery and a second coolant circuit for controlling the temperature of an electric motor and power electronics.

[0004] A vehicle diagnostic system for a front cooling unit is known from DE 102017107384 A1.

[0005] A system for monitoring a gas container is known from DE 102018002072 A1.

[0006] From DE 102017006366 A1 an oil cooling circuit for cooling an electric motor of a vehicle is known.

[0007] One object underlying the invention is to improve such a thermal management system.

[0008] This object is achieved by a thermal management system protected according to claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

[0009] The invention will be explained in detail below with reference to the figures. Further advantageous developments of the invention will become apparent from the dependent claims and the following description of preferred embodiments. These are shown in: Fig. 1a thermal management system in a proposed first embodiment, Fig. 2which in Fig. 1 shown thermal management system in conjunction with an oil cooling circuit in a first embodiment, Fig. 3 in Fig. 1 shown thermal management system in conjunction with an oil cooling circuit in a second embodiment, Fig. 4 in Fig. 1 shown thermal management system in connection with an oil cooling circuit in a third embodiment, Fig. 5 oil pressure curves corresponding to different phases of the oil cooling circuit, Fig. 6 a first flow diagram corresponding to a proposed monitoring of the oil cooling circuit in a pressure build-up phase, Fig. 7 a second flow diagram corresponding to a proposed monitoring of the oil cooling circuit in an operating phase and Fig. 8 a third flow diagram corresponding to a proposed monitoring of the oil cooling circuit in a pressure reduction phase.

[0010] The thermal management system 1 of a vehicle according to Fig. 1 illustrates a first coolant circuit 2 for a battery 7 and a second coolant circuit 3 for an electric motor 13 for driving the vehicle, as well as a refrigerant circuit 4 of an air conditioning system, which will not be discussed in more detail below. The vehicle can be a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), or a fuel cell electric vehicle (FCEV). These three cooling circuits 2, 3, 4 merge with one another to a certain extent. In the two coolant circuits 2, 3, the respective cooling liquid is pumped by means of a separate electric pump 8, 10.

[0011] Such a coolant is a mixture of water and a cooling additive. The coolant's function is not only to absorb and transport waste heat. The cooling additive also protects the water from freezing, protects the two coolant circuits from corrosion, lubricates the moving parts in both coolant circuits, and protects plastic and / or rubber elements in both coolant circuits from dissolving.

[0012] The electric motor 13 and power electronics 12 are intended to operate at a coolant or cooling water temperature of approximately 80 to a maximum of 85°C. The coolant has a temperature of approximately 55°C at the inlet to the power electronics 12 and a temperature of approximately 65°C at the inlet to the electric motor 13. At the outlet of the electric motor 13, the coolant then has a temperature of approximately 80 to a maximum of 85°C.

[0013] The battery 7 or the battery cells, however, should be operated in a coolant or cooling water temperature window between approximately 20°C and approximately 40°C, as this ensures an optimal operating temperature range for the battery 7. The temperature of the battery 7 or the individual battery cells themselves can certainly exceed the temperature threshold of approximately 40°C. Both coolant circuits 2, 3 must be able to both absorb and release heat. While the battery coolant circuit 2 has a heat exchanger 6 (also called a chiller; see Fig. 1 ) is cooled compared to the coolant circuit 4, the electric motor coolant circuit 3 can be cooled compared to the environment via a radiator or cooler 17 and compared to the battery coolant circuit 2 via a multi-way valve 9 described below (also called Coolant Flow Control Valve, in short: CFCV), wherein the multi-way valve 9 represents an interface between the battery coolant circuit 2 and the electric motor coolant circuit 3 and which assumes a corresponding valve position so that the coolant flows of the two coolant circuits 2, 3 can mix with one another as required.

[0014] The battery coolant circuit 2 can also be cooled via the radiator or cooler 17 if the multi-way valve 9 is set accordingly. However, since the battery coolant should not exceed a temperature of 40 °C, heat dissipation via the radiator 17 is usually not sufficient, so heat must be dissipated via the heat exchanger 6. In the electric motor coolant circuit 3, in addition to the electric motor 13 and the power electronics 12, a charging device 11 (also called a charger) must also be cooled. A temperature sensor (not shown) is provided for each of the coolant circuits 2 and 3. A resistance heater (not shown) is also provided in the battery coolant circuit 2 to enable the temporary supply of electrical heat.

[0015] The multi-way valve 9 allows the thermal management system 1 to be operated in different modes. The multi-way valve 9 is part of a so-called actuator unit—also called a cooling water valve unit, cooling water control valve unit, or cooling water regulating valve unit—which, as such, also includes a drive unit with an electric actuator and a control unit for controlling the electric actuator.

[0016] For the sake of completeness, reference is made to the German patent application with the file number 10 2019 210 577.7, which discusses these modes in detail.

[0017] In a first mode of the system (Use Case 1, abbreviated: UC1 = series connection R with maximum heat recovery) and in a first valve position of the multi-way valve 9, the coolant circuit 2 can be connected in series with the coolant circuit 3. With respect to the multi-way valve 9, coolant flows from the coolant circuit 3 into the coolant circuit 2 via an inlet or inlet a and an outlet or outlet c, and finally from the coolant circuit 2 back into the coolant circuit 3 via an inlet or inlet d and an outlet or outlet b.

[0018] This series connection causes rapid heating of the battery coolant circuit 2 by utilizing the waste heat of the electric motor 13 and the power electronics 12. The electric motor coolant circuit 3 thus also functions as a heating circuit.

[0019] In a second system mode (Use Case 2, abbreviated: UC2 = parallel connection P with overheating protection) and in a second valve position of the multi-way valve 9, the coolant circuit 2 can be connected in parallel with the coolant circuit 3, so that the two coolant circuits 2, 3 are fluidically separated from each other. This separation protects the battery 7 from overheating.

[0020] In addition, a third mode of the system (Use Case 3, in short: UC3 = mixed mode M with selective heat recovery) is also proposed, in which the multi-way valve 9 is switched to an intermediate position - ie a third valve position - in which the coolant flows of the two coolant circuits 2, 3 mix with each other as required.

[0021] Such a mixed mode allows both the coolant temperature of the battery coolant circuit 2 and the coolant temperature of the electric motor coolant circuit 13 to be controlled more precisely. Advantageously, large pressure and temperature jumps in the two coolant circuits 2, 3 are avoided, since frequent switching between the series connection mode R and the parallel connection mode P is avoided.

[0022] In the version proposed here (see e.g. Fig. 1 ) the multi-way valve 9 is designed as a 5 / 3-way valve. It is also necessary to consider a valve from the plane of the Fig. 1 Imagine a protruding inlet or inlet e of the 5 / 3-way valve, which as such is fluidically connected via a bypass path 16 to a node 14 (or its outflow a I< ) downstream of the electric motor 13, wherein both the bypass path 16 and a parallel path 15 with a radiator 17 originate from the node 14. The radiator path 15 fluidically connects the node 14 (or its outflow c I< ) to the inlet or inlet a of the 5 / 3-way valve.

[0023] Instead of the aforementioned 5 / 3-way valve, a multi-way valve in the form of a 4 / 2-way valve could also be used, via which the previously described system modes and valve positions can also be set or controlled. In this case, in the coolant circuit 3 downstream of the electric motor 13 - instead of the previously mentioned node - another multi-way valve in the form of a 3 / 2-way valve is provided, which is fluidically connected to the inlet or inlet a of the 4 / 2-way valve.

[0024] For the sake of completeness, reference is also made to the German patent application with the file number 10 2019 210 577.7, which discusses this alternative design in detail.

[0025] The thermal management system 1 further comprises an oil cooling system 5a with an oil cooling circuit 5 (cf. Fig. 2, Fig. 3 , Fig. 4 ) for additional cooling of the electric motor 13. The oil cooling circuit 5 is thermally connected to the coolant circuit 3 by means of a heat exchanger 20. The oil cooling circuit 5 comprises, in addition to part of the heat exchanger 20, the rotor 27 of the electric motor 13 and a gearbox or reduction and / or transmission gear 26, e.g. in the form of a three-stage gearbox, which forms an electric motor-gear drive unit with the electric motor 13 (or stator 13 I< and rotor 27). The oil cooling circuit 5 further comprises an oil pump 23, an oil filter 24 fluidically connected upstream of the oil pump 23 and two temperature sensors 25, 28 (cf. Fig. 2, Fig. 3 , Fig. 4 ).

[0026] The stator 13 I< of the electric motor 13, however, is encompassed by the coolant circuit 3, i.e. the stator 13 I< is coolant- or water-cooled.

[0027] The waste heat of the electric motor 13—or stator 13 I< and rotor 27—absorbed by the oil cooling circuit 5 is fed to the coolant circuit 3 via the heat exchanger 20. The heat exchanger 20 is arranged fluidically parallel to the coolant- or water-cooled stator 13 I<.

[0028] A first supply line 18 leads from a node of the coolant circuit 3 upstream of the stator 13 I< to the heat exchanger 20 and a second supply line 19 from the heat exchanger 20 to the said node 14 downstream of the stator 13 I< .

[0029] An oil, which is also used for lubrication and cooling of the gear 26, is pumped through a shaft of the rotor 27 to at least one outlet point of the rotor 27. From this outlet point, the oil is thrown against the windings of the stator 13 by centrifugal force, distributing the oil over the rotor 27 and also reaching the two bearing points of the rotor shaft. The oil finally flows into an oil pan attached to the stator 13, which collects it. The oil pump 23 draws the oil from the oil pan and pumps it.

[0030] The oil cools the electric motor 13 in addition to the cooling liquid of the electric motor coolant circuit by absorbing the waste heat of the stator 13 I< and the rotor 27, and at the same time lubricates the aforementioned bearing points of the rotor shaft.

[0031] The oil cooling circuit 5 also includes a monitoring system for monitoring the oil flow. The monitoring system includes a pressure sensor 21. According to the invention, an additional pressure sensor 22 is proposed to be able to determine pressure differences using detected pressures. By using the two pressure sensors 21, 22, the costs of such a monitoring system can be significantly reduced. It is proposed that the two pressure sensors 21, 22 be arranged preferably upstream of the heat exchanger 20 and downstream of the oil pump 23. Fig. 3 The two pressure sensors 21, 22 are in contrast to Fig. 2 integral part of a sensor module 20a.

[0032] Fig. 5 illustrates pressure curves recorded by the two pressure sensors 21, 22 corresponding to the oil flow in the oil cooling circuit 5 in three successive phases, namely: in a pressure build-up phase (Phase I), in an operating phase (Phase II) which follows the pressure build-up phase, and in a pressure reduction phase (Phase III) which follows the operating phase.

[0033] To monitor the oil flow, the individual phases I to III Pressure difference values ​​between the two pressure curves are determined. These pressure difference values ​​are then compared with a predefined, phase-specific comparison value—also called a threshold or reference value—for the pressure difference to check for errors. An error is detected if the comparison value is exceeded.

[0034] Even before the oil pump 23 and thus the oil cooling circuit 5 is put into operation or activated - ie before the pressure build-up phase (Phase I) is initiated - it is suggested to check for an electrical fault in the monitoring system (or sensor fault), e.g. a short circuit or cable break (see steps P1_1 to P1_7 in Fig. 6 ).

[0035] For this purpose, from the time of initiation of this review (see step P1_1, Fig. 6 ) a minimum time or debounce time must elapse (see step P1_2, Fig. 6 ) to ensure that the oil cooling circuit 5 is at a standstill and the pressure within the oil cooling circuit 5 has been reduced. This condition is checked in step P1_3. The signals from the pressure sensors 21, 22 are then discretely recorded at at least one point in time, and a pressure difference value is determined for this point in time (see step P1_4, Fig. 6 ). This pressure difference value is then compared in step P1_5 with a predeterminable first pressure comparison value SW1. If the pressure difference value exceeds the pressure threshold value SW1 in step P1_6, an electrical fault in the monitoring system (or sensor fault) is detected (see step P1_7, Fig. 6 Otherwise, the monitoring system is faultless.

[0036] In step P1_8, the oil pump 23 and thus the oil cooling circuit 5 are started or activated, initiating the pressure build-up phase (phase I). The signals from the pressure sensors 21, 22 are discretely recorded for at least one pressure stroke of the oil pump 23 – which is a positive displacement pump (see step P1_8, Fig. 6 ). Such a pressure stroke during the pressure build-up phase (Phase I) is in Fig. 5 clearly identified. Then at least one pressure difference value is determined (see step P1_8, Fig. 6 ) and the pressure difference value is then compared with a predeterminable, second pressure comparison value SW2 (phase-related comparison value for the pressure difference) (see step P1_9, Fig. 6 ). In addition, the time until the pressure stroke is reached can also be compared with a predefined time comparison value.

[0037] In the event that the determined pressure difference value on the one hand and, if applicable, the determined time value on the other hand, exceed the respectively assigned comparison value (see step P1_10, Fig. 6 ), such an error is detected in the pressure build-up phase (Phase I) (see error output in step P1_11, Fig. 6 Otherwise, the pressure build-up phase (Phase I) is error-free (see step P1_12, Fig. 6 ).

[0038] After initiating the operational phase (Phase II, see step P2_1, Fig. 7 ), which follows the pressure build-up phase (Phase I), the signals of the pressure sensors 21, 22 are again recorded discretely, ie at at least one point in time, and for this point in time a pressure difference value is determined from the two sensor signals (see step P2_2, Fig. 7 ). This pressure difference value is then compared with a predefined, third pressure comparison value SW3 (phase-related comparison value for the pressure difference) (see also step P2_2, Fig. 7 ) to check for an electrical fault in the monitoring system (or sensor fault). If the measured pressure difference value exceeds the pressure comparison value SW3 (see step P2_3, Fig. 7 ), such an electrical fault of the monitoring system (or sensor fault) is detected (see step P2_7, Fig. 7 ).

[0039] Subsequently, an average value is calculated from the discretely recorded signals of the two pressure sensors 21, 22 (see step P2_4, Fig. 7 ) and this mean value or pressure mean value is then compared with a predefined, fourth pressure comparison value (phase-related comparison value for the pressure difference) (see step P2_5, Fig. 7 ) to check for an error in the operating phase (Phase II). If this mean pressure value exceeds the comparison value in step P2_6, such an error in the operating phase (Phase II) is detected (see step P2_8, Fig. 7 Otherwise, an error-free operating phase (Phase II) is present (see step P2_9, Fig. 7 ).

[0040] After deactivation or decommissioning of the oil pump 23 (see step P3_1, Fig. 8 ), with which the pressure reduction phase (Phase III) is initiated, the signals of the pressure sensors 21, 22 are again discretely recorded at least once (see step P3_2, Fig. 8 ). A pressure difference value is then determined for this point in time and this pressure difference value is then compared with a predeterminable, fifth pressure comparison value SW5 (phase-related comparison value for the pressure difference) (see also step P3_2, Fig. 8 ) to check for an electrical fault in the monitoring system (or sensor fault). If this pressure difference value exceeds the pressure comparison value in step P3_3, such an electrical fault in the monitoring system (or sensor fault) is detected (see step P3_4, Fig. 8 Otherwise, the monitoring system is faultless.

[0041] Afterwards, a pressure drop is monitored by triggering a debounce after a predefined time or debounce time (see step P3_5, Fig. 8 ) Regarding the initiation of the pressure reduction phase (Phase III), the two discretely recorded pressures or pressure sensor values ​​are compared with a predefined target value related to the debouncing time (sixth pressure comparison value SW6; phase-related comparison value for the pressure difference) in order to check for an error in the pressure reduction phase (Phase III). If this target value is exceeded (see step P3_7, Fig. 8 ), such an error is detected in the pressure reduction phase (Phase III) (see step P3_8, Fig. 8 Otherwise, the pressure reduction phase (Phase III) is error-free (see step P3_9, Fig. 8 ).

[0042] With regard to the individual phases I, II, and III, it is proposed to record the pressure sensor values, for example, every 10 to 100 ms. The aforementioned phase-related comparison values ​​can vary depending on the phase, ie, be phase-specific.

[0043] Although exemplary embodiments are explained in the foregoing description, it should be noted that numerous modifications are possible within the scope of protection defined only by the appended claims. Furthermore, it should be noted that the exemplary embodiments are merely examples and are not intended to limit the scope of protection, applications, or construction in any way. Rather, the foregoing description provides the person skilled in the art with a guide for implementing at least one exemplary embodiment, whereby various changes, particularly with regard to the function and arrangement of the described components, can be made without departing from the scope of protection (defined ONLY by the appended claims).

Claims

1. Thermal management system for a vehicle having a battery (7), the temperature of which is to be controlled, and an electric motor (13, 13I, 27), the temperature of which is to be controlled, for driving the vehicle, the electric motor (13, 13I, 27) being at least oil-cooled, wherein the thermal management system comprises a monitoring system for monitoring an oil flow produced by means of an oil pump (23) in an oil cooling circuit (5) comprising the electric motor (13, 13I, 27), wherein the monitoring system has a first pressure sensor (21) at a first position in the oil cooling circuit and a second pressure sensor (22) at a second position in the oil cooling circuit, in order to use measured pressures to determine pressure differences and to compare these pressure differences with a predeterminable and phase-related comparison value for the pressure difference and to check for an error, an error being detected if the comparison value is exceeded.

2. Thermal management system (1) according to Claim 1, wherein the stator (13I) of the electric motor (13) is comprised of a coolant circuit (3), whereas the rotor (27) of the electric motor (13) is comprised of the oil cooling circuit (5), the oil cooling circuit (5) being thermally connected to the coolant circuit (3) via a heat exchanger (20).

3. Thermal management system (1) according to Claim 1 or 2, wherein the first pressure sensor (21) and the second pressure sensor (22) are arranged upstream of a / the heat exchanger (20) and downstream of the oil pump (23).

4. Thermal management system (1) according to Claim 2 or 3, wherein the heat exchanger (20) is arranged fluidically in parallel with the coolant-cooled stator (13I) .

5. Thermal management system (1) according to Claim 4, wherein a first supply line (18) is routed from a node of the coolant circuit (3) upstream of the stator (13I) to the heat exchanger (20) and a second supply line (19) is routed from the heat exchanger (20) to a node (18) of the coolant circuit (3) downstream of the stator (13I).

6. Vehicle having a thermal management system (1) according to one of Claims 1 to 5.

7. Use of a first pressure sensor (21) at a first position in an oil cooling circuit (5) and of a second pressure sensor (22) at a second position in the oil cooling circuit (5) for monitoring an oil flow produced by means of the oil pump (23) in an oil cooling circuit (5), comprising an electric motor (13, 13I, 27), of a thermal management system according to one of the preceding Claims 1 to 5, wherein measured pressures are used to determine pressure differences, these pressure differences being compared with a predeterminable and phase-related comparison value for the pressure difference in order to check for an error, an error being detected if the comparison value is exceeded.