Thermal management system and method for operating such a thermal management system

Abstract

The invention relates to a thermal management system in an electrically powered vehicle, the vehicle axle of which has at least one wet-running multi-disk brake or clutch (5, 7) acting on the vehicle axle, by means of which brake actuation, for example for vehicle braking, can be carried out, wherein the multi-disk brake or clutch (5, 7) is connected in a coolant / lubricant circuit (K) in which the coolant can be circulated to cool the multi-disk brake or clutch (5, 7). According to the invention, the coolant / lubricant circuit (K) has a heat exchanger (30) that can be thermally coupled to a heating circuit (H). Waste heat generated by the multi-disk brake or clutch (5, 7) can be dissipated via the heat exchanger (30).

Description

The invention relates to a thermal management system according to the preamble of claim 1 and to a method for operating such a thermal management system according to the preamble of claim 9.An electrically operated vehicle can have at least one vehicle axle on which the vehicle wheels are not braked with conventional dry-running disc brakes or dry brakes, but rather with at least one wet-running multi-disc brake. If, therefore, the electric machine of the vehicle is not capable of recuperation or is only partially capable of recuperation, then the multi-disk brake can at least partially or completely take over the braking task. For example, the multi-disk brake can effect a vehicle braking as a function of a current recuperation capability.In a vehicle of the generic type, the wet-running multi-disk brake is integrated together with the electric machine and the final drive in a cooling / lubricant circuit in which oil flows through the multi-disk brake during the vehicle brake for cooling purposes.The problem with the vehicle of the generic type is that, owing to the high efficiency of the electric machine, there is a lack of heat sources for tempering, for example, the vehicle interior, a pulse inverter and / or a traction battery. This shortcoming is compensated in the prior art by appropriately dimensioned electric auxiliary heaters. However, this takes place at the expense of the efficiency and the range of the vehicle.DE 10 2009 026 985 A1 discloses an arrangement for cooling and / or lubricating at least one disk pack of a multi-disk clutch or of a multi-disk brake of a vehicle. The arrangement has a pump for providing a coolant and / or lubricant flow, the volume flow of which can be varied at least as a function of the actuation of the multiplate clutch or of the multiplate brake. The volume flow can be electronically controlled as required by means of a control device.WO 2020 / 245021 A1 discloses a multi-disk brake for a motor vehicle, which has two multi-disk devices and an actuating device for brake actuation and / or brake release of the multi-disk devices and an electric drive for translatory actuation (expansion) of the actuating device, such as in particular of the ramp unit. In the event of spreading, the disk devices are prestressed in a dosed manner by the actuating device and produce a desired frictional engagement. A correspondingly reversed actuation of the actuating device enables a correspondingly dosed brake release.The object of the invention is to provide a thermal management system and a method for operating such a thermal management system, in which the heating requirement of a vehicle consumer can be met more efficiently in comparison with the prior art.The object is achieved by the features of claim 1 or claim 9. Preferred developments of the invention are disclosed in the dependent claims.The invention relates to a thermal management system in an electrically operated vehicle. Its vehicle axle can have at least one wet-running multi-disk brake or multi-disk clutch acting on the vehicle axle. With the aid of the multi-disk brake or the multi-disk clutch, a brake actuation can be carried out, for example for a vehicle braking system. The multi-disk brake or multi-disk clutch is connected in a coolant / lubricant circuit in which coolant / lubricant can be circulated for cooling the multi-disk brake / clutch during the brake actuation. In addition, the vehicle has a heating circuit through which coolant flows. When the heating demand is required, at least one vehicle load, for example a traction battery, a pulse inverter and / or vehicle interior, can be heated with the aid of the heating circuit. According to the characterizing part of claim 1, a heat exchanger that can be thermally coupled to the heating circuit is connected in the cooling / lubricant circuit. In this way, the waste heat generated during the brake actuation of the multi-plate brake / clutch can be used for heating the vehicle consumer.The multi-disk brake can be actuated by a corresponding actuator. The multi-disk brake actuator is preferably not hydraulically, but rather electrically controllable with a brake signal.When a brake actuation, in particular a vehicle braking system, is present, the control unit can actuate actuating elements in the coolant / lubricant circuit in order to activate the latter. By way of example, a circulation pump and / or a control valve act as control elements, with which the cooling / lubricant flow in the cooling / lubricant circuit can be controlled in order to cool the disk brake or in order to remove the waste heat from the disk brake.In the presence of such a brake actuation, the control device can not only activate the cooling / lubricant circuit; in addition, the control device can also activate the heating circuit by appropriate actuation of control elements in order to transfer the disk brake waste heat from the cooling / lubricant circuit. As such, the consumer connected in the heating circuit can be supplied with the waste heat in order to cover its heating requirement.In the embodiment set forth above, the multi-disk brake is used in a dual function both for vehicle braking and as a heating element in order to at least partially cover the heating requirement of a vehicle consumer.Alternatively, in the embodiment described below, the multi-disk brake can be used exclusively as a heating element without at the same time also initiating a vehicle braking. In this embodiment, the control unit can be assigned an evaluation unit which determines the presence of a heating requirement of the consumer. If such a heating requirement is present, the control device can start a heating mode. In the heating mode, during the driving operation, both the multi-disk brake actuator is actuated with an electrical brake signal and an electric machine acting as a drive unit is actuated with an additional drive torque. In this case, the electric machine travels against the brake-operated multi-disk brake in order to generate waste heat in the multi-disk brake, which waste heat is intended to at least partially cover the heating requirement of the consumer. The brake signal and the additional drive torque are preferably matched to one another in such a way that no vehicle braking is perceived by the vehicle occupant.In the heating mode set forth above, the control device additionally controls actuating elements, in particular a circulation pump and / or a control valve, in the heating circuit in order to activate the latter. In this way, the waste heat generated by the multi-disk brake can be transferred with high efficiency to the consumer.An exemplary embodiment of the invention is described below with reference to the attached figures.The following are shown: FIGS. 1 to 3 each show different representations, on the basis of which the thermal management system according to the invention is illustrated.In FIG. 1, an electrified vehicle axle, such as a vehicle rear axle, is shown as a two-track vehicle, which has an electric machine EM and a transmission 3. The electric machine EM is connected to a high-voltage battery 4 (FIG. 3 ). In the vehicle axle, conventional vehicle wheel brakes (i.e., dry running disc or drum brakes) are omitted. Instead of such conventional vehicle wheel brakes, the vehicle axle has a central multi-disk brake 5, described later, and multi-disk clutches 7. The central disk brake 5 brings about a vehicle braking as an alternative or in addition to the disk clutches 7.The electric machine EM is connected via its rotor shaft 9 with the interposition of a countershaft stage 11 to the input side of an axle differential 15. Its output sides are in driving connection with the vehicle wheels. In FIG. 1, the electric machine EM is installed in the vehicle axle in transverse installation. Accordingly, the rotor shaft 9 and the output shafts 17, 18 are axially parallel to each other, which lead from the output sides of the differential shaft 15 to the vehicle wheels. Likewise, the disk clutches 7 installed in the vehicle axis and the disk brake 5 are oriented axially parallel to one another in the vehicle transverse direction y.The vehicle axle has, as viewed in the vehicle transverse direction y, on each vehicle side, a superposition transmission 19 by means of which the electric machine EM can be connected directly to one of the output shafts 17, 18 while bridging the axle differential 15. With the aid of the two superposition transmissions 19, the electric machine EM can therefore drive directly to the vehicle wheels via load paths, bypassing the axle differential 15, in order to carry out torque vectoring.The countershaft stage 11 is in driving connection with an input-side axle differential gearwheel 21, and the axle differential gearwheel 21 is connected to a rotating differential housing 25 in a rotationally fixed manner. According to FIG. 1, the axle differential 15 in the vehicle transverse direction y drives in a 50 / 50 distribution on both sides onto the two output shafts 17, 18 leading to the vehicle wheels.The two superposition gears 19 are embodied in mirror images with respect to a vehicle central longitudinal plane which passes through the axle differential 15. Thus, each of the two superposition gears 19 has a transmission stage 28, which is designed in the manner of a planetary gear (but without an external ring gear), which has a sun gear 47, which is on the outside of the vehicle as viewed in the transverse direction y of the vehicle and is seated on the output shaft 17, 18 in a rotationally fixed manner, and a sun gear 29, which is on the inside of the vehicle and is arranged rotatably on the output shaft 17, 18 as a loose gear. The sun wheel 29 on the inside of the vehicle is in mesh with planetary wheels 41 on the inside of the vehicle, each of which is arranged on a carrier shaft 43 in a rotationally fixed manner. Each of the carrier shafts 43 has an external planetary gear 45 which meshes with the external sun gear 47.The sun wheel 29 (i.e. the loose gearwheel) on the inside of the vehicle is seated together with an inner disk carrier 31 of the multi-disk clutch 7 on a hollow shaft through which the output shaft 17, 18 leads. The inner disk carrier 31 of the multiplate clutch 7 interacts via a disk pack with an outer disk carrier 39 which is connected to the differential housing 25 in a rotationally fixed manner. The disk set situated between the outer disk carrier 39 and the inner disk carrier 31 can be pressurized via a disk clutch actuator 49 in order to actuate the disk clutch 7 up to a predefined clutch degree. The multiplate clutch 7 can be shifted under load and controlled with slip.The disk brake 5 consists of an inner disk carrier 59 and an outer disk carrier 61 with an intermediate disk set. The inner disk carrier 59 is arranged on the differential housing 25 in a rotationally fixed manner, while the outer disk carrier 61 is connected to the transmission housing wall 55 in a rotationally fixed manner. The disk set located between the outer disk carrier 61 and the inner disk carrier 59 can be pressurized by means of an annular piston, not shown. This can be adjusted by a horizontal stroke by means of an electromechanical multi-disk brake actuator 51 in order to actuate the multi-disk brake 5.FIG. 2 shows a coolant / lubricant supply system in which the disk clutches 7, the superposition gearing 19, the disk brake 5 and the electric machine EM are connected in a coolant / lubricant circuit K. For cooling / lubrication, the above-mentioned components 5, 7, 19, EM of the vehicle axle are flowed through by oil, which collects in a sump 20 and is guided from there via a suction line 22 to the suction side of a circulation pump 24 of the cooling / lubricant circuit K. From the delivery side of the circulation pump 24, a pressure line 26 leads to the components 5, 7, 19, EM of the vehicle axle.As can be further seen from FIG. 2, a heat exchanger 30 is connected in the pressure line 26 of the cooling / lubricant circuit K, which heat exchanger can be thermally coupled to a heating circuit H. The heating circuit H can be flown through by coolant, in particular water. In FIG. 2, the electric machine EM and a pulse inverter PWR are connected by way of example in the heating circuit H. Alternatively and / or additionally, according to the circuit diagram from FIG. 3, a refrigerant circuit 32 of a vehicle air conditioning system 34, the traction battery 4 and the pulse inverter PWR can be connected in parallel one behind the other in the heating circuit H.The heating circuit H in FIG. 3 has a main line 35 which, together with the heat exchanger 30, forms a closed circuit. Three sub-lines 36, 37, 38 branch off from the main line 35 in parallel connection. In each of these branch lines 36, 37, 38 a shut-off valve 40 is arranged. The first partial line 36 is thermally coupled by means of a heat exchanger 42 to the refrigerant circuit 32 of the vehicle air conditioning system 34, by means of which a vehicle interior I can be temperature controlled. The second partial line 37 is coupled to a cooling circuit of the traction battery 4 by means of a heat exchanger 44, while the third partial line 38 is thermally coupled to the cooling circuit of the pulse inverter PWR by means of a heat exchanger 46.The thermal management system also has a control unit 48 (FIG. 3 ), with which all the control elements 24, 40, 54 of the cooling / lubricant circuit K and of the heating circuit H can be controlled. An evaluation unit 50 is assigned to the control unit 48, which is in signal connection with temperature sensors 52. With the aid of these, the current temperatures θ I, θ B, θ P in the vehicle interior I, in the traction battery 4 and in the pulse inverter PWR can be determined. In the evaluation unit 50, the current temperatures θ I, θ B, θ P are compared with corresponding setpoint values. From the comparison, the evaluation unit 50 determines whether a heating requirement is present for the vehicle air conditioning system 34, for the traction battery 4 and / or for the pulse inverter PWR. If such a heating requirement is present, the evaluation unit 50 passes a corresponding heating requirement signal S I, S B, S P to the control unit 48.Based on such a heating demand signal S I, S B, S P the controller 48 starts a heating mode. In the heating mode, during the driving operation of the vehicle, the multi-disk brake actuator 51 (FIG. 1 ) is actuated with a brake signal B and the electric machine EM is actuated with an additional drive torque M. In this way, the electric machine EM is driven against the actuated multi-disk brake 5 in order to generate waste heat. The brake signal B or the braking force resulting therefrom and the additional drive torque M are matched to one another such that no vehicle braking is perceived by the vehicle occupant.At the same time, in the heating mode, the control unit 48 also actuates the circulation pumps 24, 54 and the shut-off valves 40 in the heating circuit H and in the coolant / lubricant circuit H, K. In this way, the waste heat generated by the multi-disk brake 5 is transmitted to the respective consumer I, 4 and / or PWR, in order to at least partially cover its heating requirement.LIST OF REFERENCE CHARACTERS:3 Transmission 4 Traction battery or high-voltage battery 5 Multi-plate brake 7 Multi-plate clutch 9 Rotor shaft 11 Countershaft 15 Axle differential 17, 18 Output shafts 19 Superposition transmission 20 Sump 21 Axle differential gearwheel 22 Suction line 24 Circulation pump 25 Differential housing 26 Pressure line 28 Transmission stage 29 Sun wheel 30 Heat exchanger 31 Inner plate carrier of the multi-plate clutch 32 Refrigerant circuit 34 Vehicle air conditioning system 35 Main line 36, 37, 38 branch lines 39 outer disk carrier of the multiplate clutch 40 shut-off valve 41 vehicle-internal planetary gears 42 heat exchanger 43 carrier shaft 44 heat exchanger 45 vehicle-external planetary carrier 46 heat exchanger 47 vehicle-external sun gear 48 control unit 49 multiplate clutch actuator 50 evaluation unit 51 multiplate brake actuator 52 temperature sensor 54 circulation pump 55 transmission housing wall 59 inner disk carrier of the brake 61 outer disk carrier of the brake θ I interior temperature θ B battery temperature θ P pulse inverter temperature K cooling / lubricant circuit H heating circuit M additional drive torque B brake signal S I, S B, S P heating demand signalReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2009 026 985 A1

[0005] WO 2020 / 245021 A1

[0006]

Claims

Thermal management system in an electrically operated vehicle, the vehicle axle of which has at least one wet-running disc brake or clutch (5, 7) which acts on the vehicle axle and by means of which a brake actuation can be carried out, for example for a vehicle braking, wherein the disc brake or clutch (5, 7) is connected in a cooling / lubricant circuit (K), in which cooling / lubricant can be circulated in order to cool the disc brake or clutch (5, 7), characterized in that the cooling / lubricant circuit (K) has a heat exchanger (30) which can be thermally coupled to a heating circuit (H), and in that waste heat generated by the disc brake or clutch (5, 7) can be discharged via the heat exchanger (30).Thermal management system according to Claim 1, characterized in that at least one consumer, for example a traction battery (B), a pulse inverter (PWR) and / or a vehicle interior (I), is connected in the heating circuit (H), and in that the consumer can be heated by means of the heating circuit (H) if a heating requirement (S B, S I, S P) is present, and in that, in particular, the waste heat generated during the brake actuation can be used for heating the consumer (B, PWR, I).Thermal management system according to Claim 1 or 2, characterized in that the multi-disk brake or clutch (5, 7) can be actuated with the aid of an, in particular electromechanical, actuator (51), and in that, in particular, the actuator (51) can be actuated by a control unit (48) with a brake signal (B).Thermal management system according to Claim 3, characterized in that, in the presence of a brake actuation, in particular vehicle braking, the control unit (48) activates the cooling / lubricant circuit (K) in order to cool the disk brake or clutch (5, 7) or in order to remove waste heat from the disk brake or clutch (5, 7).Thermal management system according to Claim 4, characterized in that, in the event of a brake actuation, the control unit (48) activates not only the cooling / lubricant circuit (K) but also the heating circuit (H) in order to transfer waste heat from the cooling / lubricant circuit (K) to the heating circuit (H) and in particular in order to supply the consumer (I, B, PWR) connected in the heating circuit (H) with the waste heat.Thermal management system according to one of the preceding claims, characterized in that the control unit (48) is assigned an evaluation unit (50) which determines the presence of a heating requirement (S B, S I, S P) of the consumer (I, B, PWR), and in that, if a heating requirement (S B, S I, S P) is present, the control unit (48) starts a heating mode in which, during driving operation, both the multi-plate brake or clutch (5, 7) can be actuated with a brake signal or with a braking force (B) and an electric machine (EM) acting as a drive unit can be actuated with an additional drive torque (M), so that the electric machine (EM) travels against the disk brake or clutch (5, 7) to which braking force is applied, in order to generate waste heat.Thermal management system according to Claim 6, characterized in that the braking signal or the braking force (B) and the additional drive torque (M) are matched to one another in such a way that no vehicle braking is perceived by the vehicle occupant.Thermal management system according to Claim 6 or 7, characterized in that, in the heating mode, the control unit (48) actuates actuating elements, in particular a circulation pump (52, 54) and / or a control valve (40), in the heating circuit (H) and in the cooling / lubricant circuit (K) in such a way that the waste heat generated by the multi-disk brake (5) can be transferred to the consumer (I, B, PWR).Method for operating a thermal management system in an electrically operated vehicle, in particular according to one of the preceding claims, wherein the vehicle axle of the vehicle has at least one wet-running disc brake or clutch (5, 7) which acts on the vehicle axle and by means of which a brake actuation, for example for a vehicle braking, is carried out, wherein the disc brake or clutch (5, 7) is switched in a cooling / lubricant circuit (K), in which cooling / lubricant is circulated in order to cool the disc brake or clutch (5, 7), characterized in that the cooling / lubricant circuit (K) has a heat exchanger (30) which can be thermally coupled to a heating circuit (H), and in that waste heat generated by the disc brake or clutch (5, 7) is dissipated via the heat exchanger (30).

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