Thermal management system and vehicle

Abstract

The invention relates to a thermal management system for a vehicle, the thermal management system (1) comprising a first coolant circuit (2) for a battery (7) for driving the vehicle and a second coolant circuit (3) for driving an electric motor (13) of the vehicle. The two coolant circuits (2, 3) can be operated in series or in parallel with each other by means of a multi-way valve (9). The thermal management system (1) further comprises an oil cooling circuit (5) for auxiliary cooling of the electric motor (13), wherein the oil cooling circuit (5) is thermally connected to the second coolant circuit (3) via a heat exchanger (20). In addition, a vehicle having such a thermal management system is proposed.

Description

Technical Field

[0001] The present invention relates to a thermal management system for a vehicle and also to a vehicle having such a thermal management system. Background Art

[0002] A vehicle is to be understood as any type of vehicle which comprises a battery to be temperature-controlled and an electric motor or electrical machine (E-Motor) to be temperature-controlled for driving the vehicle. The battery can be air-cooled and / or coolant- or cooling liquid-cooled or water-cooled. The electric motor is coolant- or cooling liquid- or water-cooled. It can be a partially electric or fully electric vehicle, but in particular a passenger car and / or a commercial vehicle.

[0003] EP 2 392 486 B1 discloses a thermal management system having a first coolant circuit for regulating the temperature of a battery and a second coolant circuit for regulating the temperature of an electric motor and power electronics. Summary of the invention

[0004] The invention is based on the object of improving such a thermal management system.

[0005] This object is achieved by a heat management system as claimed in claim 1. Furthermore, a vehicle having such a heat management system is proposed and claimed (see claim 9). Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0006] The present invention provides a thermal management system for a vehicle, wherein the thermal management system has a first coolant circuit for driving a battery of the vehicle and a second coolant circuit for driving an electric motor or an electrical machine of the vehicle.

[0007] The two coolant circuits can be operated in series with one another by means of the multi-way valve in a first mode of the system and in a first valve position of the multi-way valve or in parallel with one another in a second mode of the system and in a second valve position of the multi-way valve.

[0008] In one embodiment, the two coolant circuits can alternatively also be operated in a third mode of the system and in a third valve position of the multi-way valve, in which the multi-way valve assumes an intermediate position in which the coolant flows of the two coolant circuits mix with one another as desired.

[0009] In this on-demand mixing, waste heat or heat loss from the motor coolant circuit is advantageously output to the battery coolant circuit without subjecting the system to sudden transient behavior, which occurs when switching between the series connection mode and the parallel connection mode and manifests itself in the form of sudden temperature and pressure changes. In addition, frequent switching between the series mode and the parallel mode can be avoided during non-steady-state (transient) driving, in which the motor heats up quickly. This on-demand mixing thus improves the temperature control of the motor coolant circuit and the battery coolant circuit.

[0010] In this case, the thermal management system also comprises an oil cooling circuit for auxiliary cooling of the electric motor, wherein the oil cooling circuit is thermally connected to the second coolant circuit via a heat exchanger, for example in the form of a plate heat exchanger.

[0011] In addition to the coolant of the motor cooling circuit cooling the motor, the oil cools the motor by absorbing the waste heat of the stator and rotor of the motor and conveying it to the motor cooling circuit via a heat exchanger. In this case, the oil also lubricates the bearings of the rotor shaft.

[0012] Such a coolant is to be understood here as a mixture of water and a cooling additive. The coolant here not only has the task of absorbing and transporting the waste heat. The cooling additive should also protect the water from freezing, protect the two coolant circuits from corrosion, lubricate the movable parts in the two coolant circuits and protect the plastic and / or rubber elements in the two coolant circuits from melting.

[0013] In another embodiment, the heat exchanger is arranged fluidically in parallel with the coolant-cooled stator of the electric motor. In this case, a first feed line can extend from a node of the second coolant circuit upstream of the stator to the heat exchanger, and a second feed line can extend from the heat exchanger to a node of the second coolant circuit downstream of the stator.

[0014] In a further specific embodiment, the oil cooling circuit comprises a monitoring system having at least one pressure sensor for monitoring the oil flow generated by means of the oil pump.

[0015] The monitoring system also has a rotational speed sensor, which is arranged on the oil pump and can be used to determine the delivered volume and mass flow.

[0016] In another embodiment, the monitoring system further comprises an additional pressure sensor. At the same time, the rotation speed sensor may also be provided.

[0017] In this case, the at least one pressure sensor or the two pressure sensors can be arranged upstream of the heat exchanger and downstream of the oil pump.

[0018] The proposed sensor redundancy makes it possible to determine the plausibility of a detected pressure or a pressure measurement value or to check the plausibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is described in detail below with reference to the accompanying drawings. Other advantageous improvements of the present invention are derived from the dependent claims and the following description of preferred embodiments. The accompanying drawings show:

[0020] Figure 1 The thermal management system of the first embodiment is shown.

[0021] Figure 2 Shows Figure 1 The thermal management system shown in FIG. 1 and the oil cooling circuit of the first embodiment,

[0022] Figure 3 Shows Figure 1 The thermal management system shown in FIG. 1 and the oil cooling circuit of the second embodiment,

[0023] Figure 4 Shows Figure 1 The thermal management system shown in FIG. 1 and the oil cooling circuit of the third embodiment,

[0024] Figure 5 The oil pressure curves corresponding to the different stages of the oil cooling circuit are shown.

[0025] Figure 6 shows a first flow chart corresponding to the proposed monitoring of the oil cooling circuit during a pressure build-up phase,

[0026] Figure 7 shows a second flow chart corresponding to the proposed monitoring of the oil cooling circuit in an operating phase, and

[0027] Figure 8 A third flow chart corresponding to the proposed monitoring of the oil cooling circuit during the decompression phase is shown. DETAILED DESCRIPTION

[0028] Figure 1The thermal management system 1 of the vehicle in FIG. 1 shows a first coolant circuit 2 for driving the battery 7 of the vehicle and a second coolant circuit 3 for driving the electric motor 13 of the vehicle, as well as a refrigerant circuit 4 of the air conditioning system, but they are not explained in detail below. The vehicle here can be a battery electric vehicle (BEV), a hybrid electric vehicle (HEV) or a fuel cell electric vehicle (FCEV). The three cooling circuits 2, 3, 4 intersect with each other to a certain extent. In the two coolant circuits 2, 3, the corresponding coolant is transported by means of respective electric pumps 8, 10.

[0029] Such a coolant is understood here to be a mixture of water and a cooling additive. The coolant here not only has the task of absorbing and transporting the waste heat. The cooling additive should also protect the water from freezing, protect the two coolant circuits from corrosion, lubricate the movable parts in the two coolant circuits and protect the plastic and / or rubber elements in the two coolant circuits from melting.

[0030] The electric motor 13 and the power electronics 12 are to be operated at a coolant temperature or cooling water temperature of approximately 80° C. to a maximum of 85° C. The coolant has a temperature of approximately 55° C. at the input to the power electronics 12 and approximately 65° C. at the input to the electric motor 13 . At the output of the electric motor 13 , the coolant then has a temperature of approximately 80° C. to a maximum of 85° C.

[0031] In contrast, the battery 7 or the battery cells should be operated in a coolant temperature window or cooling water temperature window between approximately 20° C. and approximately 40° C., since this ensures an optimal operating temperature range for the battery 7. The temperature of the battery 7 or the individual battery cells themselves can easily exceed the temperature threshold of approximately 40° C. The two coolant circuits 2, 3 must be able to absorb heat and release heat. The battery coolant circuit 2 is connected via a heat exchanger 6 (also called a cooler, see Figure 1 ) dissipates heat relative to the refrigerant circuit 4, while the motor coolant circuit 3 can dissipate heat relative to the surrounding environment via a radiator or cooler 17 and dissipate heat relative to the battery coolant circuit 2 via a multi-way valve 9 (also called Coolant Flow Control Valve (coolant flow control valve), abbreviated as CFCV) to be described below, wherein the multi-way valve 9 forms an interface between the battery coolant circuit 2 and the motor coolant circuit 3 and the interface occupies a corresponding valve position for this purpose, so that the coolant flows of the two coolant circuits 2, 3 can be mixed with each other as required.

[0032] The heat dissipation of the battery coolant circuit 2 can also be carried out via a radiator or cooler 17 when the multi-way valve 9 is in a corresponding valve position. However, since the battery coolant should not exceed a temperature of 40° C., heat dissipation via the radiator 17 is usually insufficient, so that the heat must be discharged via the heat exchanger 6. In the motor coolant circuit 3, in addition to cooling the motor 13 and the power electronics 12, the charging device (also called charger) 11 must also be cooled. For regulating the coolant circuits 2 and 3, temperature sensors (not shown) are respectively provided. In addition, a resistance heater (not shown) is also provided in the battery coolant circuit 2 to be able to supply electrical heat for a short time.

[0033] The thermal management system 1 can be operated in different modes by means of the multi-way valve 9. The multi-way valve 9 is part of a so-called actuator unit (also called cooling water valve unit, cooling water control valve unit or cooling water regulating valve unit), which itself also includes a drive unit with an electric servomotor and a control unit for controlling the electric servomotor.

[0034] With regard to these modes, reference is made to German patent application document 10 2019 210 577.7 for its full content, which explains this in detail.

[0035] In a first mode of the system (Use Case 1, UC1 for short = 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. In this case, on the part of the multi-way valve 9, the coolant flows from the coolant circuit 3 into the coolant circuit 2 via the inlet or input a and the outlet or output c and finally flows from the coolant circuit 2 back into the coolant circuit 3 via the inlet or input d and the outlet or output b.

[0036] This series connection allows the battery coolant circuit 2 to be heated up quickly by utilizing the waste heat of the electric motor 13 and the power electronics 12. The electric motor coolant circuit 3 thus also has the function of a heating circuit.

[0037] In the second mode of the system (Use Case 2, UC2 for short = parallel circuit P with overheat protection) and in the 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 separated from each other in terms of fluid. This separation protects the battery 7 from overheating.

[0038] Furthermore, a third mode of the system is proposed (Use Case 3, abbreviated as UC3 = mixed mode M with selective heat recovery), in which the multi-way valve 9 is switched to an intermediate position, i.e. the third valve position, in which the coolant flows of the two coolant circuits 2, 3 are mixed with one another as required.

[0039] By means of such a mixed mode, it is possible to control more precisely not only the coolant temperature of the battery coolant circuit 2, but also the coolant temperature of the motor coolant circuit 13. Advantageously, high pressure and temperature jumps / 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 does not occur.

[0040] In the embodiments presented herein (see e.g. Figure 1 ), the multi-way valve 9 is designed in the form of a 5 / 3-way valve. Here, the 5 / 3-way valve must also be considered from Figure 1 The inlet or input end e extends out of the plane of the motor 13, which in turn is fluidly connected to the node 14 (or its outlet a') downstream of the motor 13 via a bypass path 16, wherein both the bypass path 16 and a path 15 with a radiator 17 extending in parallel with the bypass path extend from the node 14. The radiator path 15 fluidly connects the node 14 (or its outlet c') to the inlet or input end a of the 5 / 3-way valve.

[0041] Instead of the 5 / 3-way valve, a multi-way valve designed as a 4 / 2-way valve can also be used, via which the previously described system modes and valve positions can also be set or controlled. Here, in the coolant circuit 3, downstream of the electric motor 13 - instead of the previously described node - another multi-way valve designed as a 3 / 2-way valve is provided, which is fluidically connected to the inlet or input a of the 4 / 2-way valve.

[0042] With regard to this alternative design solution, reference is also made to German patent application document 10 2019 210577.7 for its full content, which explains this in detail.

[0043] The thermal management system 1 further comprises an oil cooling system 5a having an oil cooling circuit 5 (see Figure 2 , Figure 3 , Figure 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. In addition to a part of the heat exchanger 20, the oil cooling circuit 5 also includes a rotor 27 of the electric motor 13 and a transmission mechanism or a reduction and / or transmission gear 26, for example in the form of a three-stage transmission mechanism, which together with the electric motor 13 (or the stator 13 ′ and the rotor 27) forms a motor-transmission mechanism-drive unit. The oil cooling circuit 5 also includes an oil pump 23, an oil filter 24 fluidically connected upstream of the oil pump 23, and two temperature sensors 25, 28 (see Figure 2 , Figure 3 , Figure 4 ).

[0044] In contrast, the stator 13 ′ of the electric motor 13 is surrounded by the coolant circuit 3 , that is, the stator 13 ′ is cooled by the coolant or water.

[0045] The waste heat of the electric motor 13 or the stator 13' and the rotor 27 absorbed by the oil cooling circuit 5 is supplied to the coolant circuit 3 via the heat exchanger 20. In this case, the heat exchanger 20 is arranged fluidically parallel to the coolant or water-cooled stator 13'.

[0046] In this case, a first supply line 18 leads from a node of the coolant circuit 3 upstream of the stator 13 ′ to the heat exchanger 20 , and a second supply line 19 leads from the heat exchanger 20 to the node 14 downstream of the stator 13 ′.

[0047] The oil, which is also used for lubricating and cooling the transmission 26, is conveyed to at least one outlet of the rotor 27 via the shaft of the rotor 27. From this outlet, the oil is thrown under the action of centrifugal force toward the windings of the stator 13', where it is distributed on the rotor 27 and also reaches two bearing locations of the rotor shaft. The oil finally flows into and is received in an oil sump mounted on the stator 13'. The oil pump 23 draws the oil from the oil sump and conveys it.

[0048] In addition to the cooling fluid of the motor coolant circuit, the oil also cools the electric motor 13 by absorbing waste heat from the stator 13 ′ and the rotor 27 and simultaneously lubricates the bearing points of the rotor shaft.

[0049] The oil cooling circuit 5 also includes a monitoring system for monitoring the oil flow. The monitoring system preferably includes a pressure sensor 21 upstream of the heat exchanger 20 and downstream of the oil pump 23. In a first embodiment, the monitoring system also includes a rotation speed sensor 22', which is arranged on the oil pump 23 for detecting the pump speed (see Figure 2 ). In the second embodiment, an additional pressure sensor 22 is advantageously provided instead of the rotation speed sensor 22', so that the pressure difference can be determined with the aid of the detected pressure. By using two pressure sensors 21, 22, the costs of such a monitoring system can be significantly reduced. It is recommended that the two pressure sensors 21, 22 are preferably provided upstream of the heat exchanger 20 and downstream of the oil pump 23. Figure 3 In, with Figure 2 In contrast, the two pressure sensors 21 , 22 are integrated components of sensor module 20 a .

[0050] Figure 5 The pressure curve corresponding to the oil flow in the oil cooling circuit 5 detected by means of the two pressure sensors 21 , 22 is shown in three consecutive phases, namely:

[0051] During the pressure buildup phase (Phase I),

[0052] During the operation phase (Phase II) after the pressure build-up phase, and

[0053] • In the decompression phase (phase III) immediately following the operating phase.

[0054] In order to monitor the oil flow, a pressure difference between two pressure curves is determined for the individual phases I to III. These pressure difference values ​​are then compared with a predeterminable phase-based comparison value (also called a threshold value or reference value) for the pressure difference value for fault detection, wherein an error is detected when the comparison value exceeds the threshold value.

[0055] Even before the oil pump 23 and thus the oil cooling circuit 5 is put into operation or activated, that is, even before the pressure build-up phase (phase I) begins, it is recommended to check the monitoring system for electrical faults (or sensor faults), that is, for example, for short circuits or cable breaks (see Figure 6 Steps P1_1 to P1_7 in FIG.

[0056] For this purpose, it is possible to start from the moment of starting the check (see steps P1_1, Figure 6 ) after the minimum time or debounce time (see step P1_2, Figure 6 ) to ensure that the oil cooling circuit 5 is at rest and the pressure in the oil cooling circuit 5 is reduced. This condition is checked in step P1_3. The signals of the pressure sensors 21, 22 are then recorded discretely at at least one point in time and the pressure difference is determined for this point in time (see steps P1_4, Figure 6 ). This pressure difference is then compared in step P1_5 with a predeterminable first pressure comparison value SW1. If in step P1_6 the pressure difference exceeds the pressure threshold value SW1, this electrical fault (or sensor fault) of the monitoring system can be inferred (see steps P1_7, Figure 6 ). Otherwise, the monitoring system is fault-free.

[0057] In step P1_8, the oil pump 23 and thus the oil cooling circuit 5 are started or activated, whereby the pressure build-up phase (phase I) begins. In this case, during at least one oil pressure stroke of the oil pump 23 (where the oil pump is a positive displacement pump), the signals of the pressure sensors 21, 22 are detected discontinuously (see step P1_8, Figure 6 ).exist Figure 5 This oil pressure stroke during the pressure build-up phase (phase I) is clearly seen in FIG. Then, at least one pressure difference value is determined (see step P1_8, Figure 6 ), and then compares the pressure difference value with a predeterminable second pressure comparison value SW2 (a stage-based comparison value of the pressure difference) (see step P1_9, Figure 6 ). In addition, the time before the oil pressure stroke is reached can also be compared with a predeterminable time comparison value.

[0058] If the determined pressure difference value and, if applicable, the determined time value exceeds the respectively assigned comparison value (see steps P1_10, Figure 6 ), identifying this fault during the pressure build-up phase (Phase I) (see steps P1_11, Figure 6 In other cases, the pressure build-up phase (Phase I) is fault-free (see steps P1_12, Figure 6 ).

[0059] In the operating phase (phase II, see step P2_1, immediately following the pressure build-up phase (phase I), Figure 7 ) starts, the signals of the pressure sensors 21, 22 are detected again discretely, that is to say at at least one point in time, and a pressure difference value is determined from the two sensor signals for this point in time (see step P2_2, Figure 7 This pressure difference value is then compared with a predeterminable third pressure comparison value SW3 (a step-based comparison value of the pressure difference) (see also steps P2_2, Figure 7 ) in order to check for electrical faults in the monitoring system (or sensor faults). If the determined pressure difference exceeds the pressure comparison value SW3 (see step P2_3, Figure 7 ), then such an electrical fault (or sensor fault) of the monitoring system is identified (see step P2_7, Figure 7 ).

[0060] Next, a mean value is formed from the discretely recorded signals of the two pressure sensors 21, 22 (see steps P2_4, Figure 7 ) and this average value or the pressure average value is then compared with a predeterminable fourth pressure comparison value (a phase-based comparison value for the pressure difference) (see steps P2_5, Figure 7 ) in order to check for faults in the operating phase (Phase II). If the pressure mean value exceeds the comparison value in step P2_6, such a fault in the operating phase (Phase II) is identified (see step P2_8, Figure 7 Otherwise, the operation phase (Phase II) is fault-free (see step P2_9, Figure 7 ).

[0061] When the oil pump 23 for starting the decompression phase (phase III) is deactivated or stopped (see steps P3_1, Figure 8 ), the signals of the pressure sensors 21, 22 are again recorded discretely at at least one time point (see steps P3_2, Figure 8). A pressure difference value is then determined for this point in time and then compared with a predeterminable fifth pressure comparison value SW5 (a phase-based comparison value for the pressure difference) (see also steps P3_2, Figure 8 ) in order to check for an electrical fault (or sensor fault) in the monitoring system. If the pressure difference exceeds the pressure comparison value in step P3_3, such an electrical fault (or sensor fault) in the monitoring system is identified (see steps P3_4, Figure 8 ). Otherwise, the monitoring system is fault-free.

[0062] The pressure drop is then monitored by a predeterminable time or debounce time (see step P3_5, Figure 8 ), the two discretely recorded pressures or pressure sensor values ​​are compared with a predeterminable, debounce-time-based target value (sixth pressure comparison value SW6; phase-based comparison value for the pressure difference) in order to detect a fault in the decompression phase (phase III). If this target value is exceeded (see step P3_7, Figure 8 ), then such a fault is identified in the decompression phase (phase III) (see step P3_8, Figure 8 Otherwise, the decompression phase (Phase III) is fault-free (see step P3_9, Figure 8 ).

[0063] For the individual phases I, II, III, it is proposed to record the pressure sensor value, for example, every 10 ms to 100 ms. In this case, the above-mentioned phase-based comparison value can vary based on the phase, that is to say be phase-specific.

[0064] Although exemplary embodiments have been described in the foregoing description, it should be noted that a large number of variants can be derived. It should also be noted that the exemplary embodiments are merely examples and are not intended to limit the scope of protection, the mode of application and the configuration in any way. More specifically, the above description provides guidance for those skilled in the art for implementing at least one exemplary embodiment, while various changes can be made, in particular in the functions and arrangements of the components, without departing from the scope of protection derived from the claims and their equivalent feature combinations.

Claims

1. A thermal management system for a vehicle, the thermal management system (1) having a first coolant circuit (2) for a battery (7) for driving the vehicle and a second coolant circuit (3) for an electric motor (13) for driving the vehicle, wherein: The two coolant circuits (2, 3) can be operated in series with one another by means of a multi-way valve (9) in a first mode of the thermal management system (1) and in a first valve position of the multi-way valve (9) or in parallel with one another in a second mode of the thermal management system (1) and in a second valve position of the multi-way valve (9), wherein the thermal management system (1) further comprises an oil cooling circuit (5) for auxiliary cooling of the electric motor (13), wherein the oil cooling circuit (5) is thermally connected to the second coolant circuit (3) via a heat exchanger (20), and the two coolant circuits (2, 3) can optionally also be operated in parallel with one another in a third mode of the thermal management system (1). and operates in a third valve position of the multi-way valve (9), in which the multi-way valve (9) occupies an intermediate position in which the coolant flows of the two coolant circuits (2, 3) are mixed with one another as required, a heat exchanger (20) is arranged fluidically in parallel with a coolant-cooled stator (13') of an electric motor (13), a first supply line (18) extends from a node of the second coolant circuit (3) upstream of the stator (13') to the heat exchanger (20), and a second supply line (19) extends from the heat exchanger (20) to a node (14) of the second coolant circuit (3) downstream of the stator (13').

2. The thermal management system according to claim 1, wherein: The oil cooling circuit (5) comprises a monitoring system having at least one pressure sensor (21) for monitoring the oil flow generated by means of an oil pump (23).

3. The thermal management system according to claim 2, wherein: The monitoring system also has a rotational speed sensor (22') which is arranged on the oil pump (23).

4. The thermal management system according to claim 2 or 3, wherein: The monitoring system also has an additional pressure sensor (22).

5. The thermal management system according to claim 4, wherein: The at least one pressure sensor (21) is arranged upstream of the heat exchanger (20) and downstream of the oil pump (23).

6. The thermal management system according to claim 5, wherein: Two pressure sensors (21, 22) are arranged upstream of the heat exchanger (20) and downstream of the oil pump (23).

7. A vehicle having a thermal management system (1) according to any one of claims 1 to 6.

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