Cooling system for a drive unit of a hybrid or electric vehicle and drive unit with such a cooling system

Abstract

A cooling system (115) for a drive unit (100) of a hybrid or electric vehicle (105), comprising a reservoir (120) configured to receive and supply fluid of a first coolant circuit, which was pumped from a sump (130) into an interior (135) of a housing (140) of the reservoir (120) by means of a pump (125), wherein at least one coolant line (180) of a second coolant circuit is provided on and / or in the housing (140), which is configured to carry coolant from a power electronics unit (175) to a heat exchanger (185).

Description

[0001] The present invention relates to a cooling system for a drive device of a hybrid or electric vehicle and to a drive device with such a cooling system.

[0002] Hybrid or electric vehicles powered by an electric axle typically have an electric motor, power electronics, and optionally a transmission, which are cooled via a heat exchanger. A cooling system for the electric axle may include at least a first coolant circuit, which is typically designed to cool a transmission and a rotor of an electric motor of the hybrid or electric vehicle. A second coolant circuit may be provided, which is designed to cool the power electronics and the stator of the electric motor of the hybrid or electric vehicle. The power electronics are typically actively cooled by plate coolers.A plate cooler is a special type of heat exchanger that usually consists of wave-shaped profiled plates, whereby the plates are assembled in such a way that the medium to be heated and then the heat-emitting medium flows in the successive spaces between them.

[0003] DE 10 2018 213 394 A1 discloses a cooling device for an electric axle, comprising a first coolant circuit designed to cool a transmission and a rotor of an electric machine of the hybrid or electric vehicle, and a second coolant circuit designed to cool an inverter of an electric axle and a stator of the electric machine of the hybrid or electric vehicle. At least one temperature sensor is provided, which is configured to detect a temperature of the transmission, a temperature of the rotor of the electric machine of the hybrid or electric vehicle, a temperature of the inverter of the electric axle, or a temperature of the stator of the electric machine of the hybrid or electric vehicle. Furthermore, a pump arrangement driven by an electric machine is provided, having a first pump and a second pump connected by a common shaft.The first pump is configured to generate a coolant volume flow of the first coolant circuit, and the second pump is configured to generate a coolant volume flow of the second coolant circuit. The electric machine can be controlled using the temperature detected by the at least one temperature sensor.

[0004] One object of the invention is to provide a cooling system for a drive device with improved cooling performance. The invention achieves this object by means of the subject matter of the independent claims. Subclaims specify preferred embodiments.

[0005] A cooling system according to the invention for a drive device of a hybrid or electric vehicle comprises a storage device configured to receive and provide fluid from a first coolant circuit, which has been pumped from a sump into an interior space of a housing of the storage device, wherein at least one coolant line of a second coolant circuit is provided on and / or in the housing, which is configured to conduct coolant from power electronics to a heat exchanger. The interior space is at least partially spatially delimited by the housing of the storage device, wherein the interior space is designed such that a sufficient quantity of fluid can be received in the storage device and kept available, for example, to supply thermal consumers or other components.

[0006] The pump is part of a hydraulic system, preferably designed as a vane pump and driven at least indirectly by an electric motor to draw the fluid of the first coolant circuit from the sump and pump it into the storage device. The storage device is, in particular, a dry-sump storage container, also called a bunker or reservoir. If the fluid of the first coolant circuit is oil, the storage device is also to be understood as an oil tank.

[0007] The fluid can be fed from the storage device to at least one further pump of a hydraulic system for cooling or lubricating thermal consumers or other components of a motor vehicle. In other words, the thermal consumers or the other components are fed from the storage device. The further pump can be designed so that it can be driven jointly by the aforementioned electric motor, together with the pump that pumps fluid from the sump into the storage device. Thus, the at least two pumps can be operatively connected to a common drive shaft. Alternatively, the further pump can be driven by a separate electric motor. After the thermal consumers or components have been supplied with fluid from the first coolant circuit, the fluid is returned to the sump by suitable means and in a manner known in principle, from where the fluid can be pumped again into the storage device.

[0008] The reservoir is formed by the housing, which can be constructed in one or more parts. The material of the reservoir or housing can be adapted to the requirements of the cooling system. It is conceivable to construct the housing from a light metal to reduce the overall weight of the vehicle. The reservoir is preferably manufactured by casting.

[0009] By pumping fluid from the sump into the storage device, a required fluid level is always maintained in the storage device or in the interior of the housing in order to ensure a sufficient supply to the thermal consumers at all times.

[0010] In one exemplary embodiment, the at least one coolant line of the second coolant circuit extends at least partially through the interior of the housing, in such a way that at least a portion of the outer circumferential surface of the at least one coolant line is always in contact with the fluid in the interior of the housing. In this sense, in one exemplary embodiment, the at least one coolant line is substantially tubular and is guided at least partially through the interior of the housing, wherein the at least one coolant line is at least partially surrounded by the fluid of the first coolant circuit located in the interior of the housing. The coolant guided in the coolant line can thus absorb heat from the fluid present in the storage device and / or flowing in.

[0011] The first coolant circuit is designed to cool a transmission and a rotor of an electric motor of the hybrid or electric vehicle. The first coolant circuit also serves as a lubricant circuit, particularly when transmission components, such as gears, shafts, or bearing elements, are lubricated by the first coolant circuit.

[0012] The second coolant circuit is designed to cool the power electronics of the hybrid or electric vehicle and a stator of the electric machine of the hybrid or electric vehicle. The power electronics is part of a power module of the electric machine of the hybrid or electric vehicle and is designed to operate, i.e., to control and regulate, the electric machine. The power electronics can include an inverter or the like, which is cooled by the second coolant circuit.

[0013] The at least one coolant line can be configured in the form of a channel, a hose, a tube, or the like. Preferably, the at least one coolant line is made of a material that enables the best possible heat transfer between the coolant of the second coolant circuit and the fluid of the first coolant circuit located in the storage device, such as copper or aluminum. Suitable coolants include water or other known coolants. Thus, when water is used as the coolant, the fluid of the first coolant circuit is water-cooled.

[0014] The at least one coolant line is designed to be connected upstream to a plate cooler of the power electronics. After cooling the power electronics, the coolant is guided via the at least one coolant line to the heat exchanger, where the fluid, which is heated by the operation of the drive device, is cooled.

[0015] The heat exchanger and its size depend on the required cooling capacity. As the coolant flows through the storage device, the fluid inside the housing can release heat or be cooled, allowing the heat exchanger to be reduced in size compared to conventional solutions.

[0016] It is conceivable that the at least one coolant line is routed through the interior of the housing via the shortest possible route from one side wall of the housing to an opposite side wall. However, it is also possible to design the at least one coolant line with windings in order to increase the extent of the at least one coolant line through the interior of the housing. The extent of the coolant line can be selected, in particular, depending on the arrangement of the power electronics, the storage device, and / or the heat exchanger on the vehicle.

[0017] One or more coolant lines can be routed at least partially through the interior of the housing. Accordingly, everything described for the at least one coolant line is to be understood and applied analogously to other coolant lines that are also arranged at least partially in the storage device. Due to the coolant being routed through the storage device, the fluid of the first coolant circuit can dissipate some of its heat in the storage device.

[0018] An access line of the first coolant circuit is preferably arranged on the storage device and is designed to fluidically connect the interior of the housing with the pump. The fluid of the first coolant circuit is guided to the pump into the interior of the housing via the access line. The access line is therefore to be understood as the inlet of the storage device. The access line can be a simple opening or mouth in the housing of the storage device, which opens into the interior of the housing at a top or bottom side or at a side wall of the housing. Alternatively, the access line can be a pipe or hose that extends at least partially through the interior of the housing and guides the fluid in the desired manner and to a desired location.

[0019] In one exemplary embodiment, the access line is positioned and aligned relative to the at least one coolant line in such a way that a volume flow of the first coolant circuit is directed toward the at least one coolant line. In other words, the fluid of the first coolant circuit is directed and conveyed directly toward the at least one coolant line via the access line, such that the volume flow essentially directly impacts the at least one coolant line, thereby creating a turbulent flow on and around the at least one coolant line. This results in improved heat transfer. Thus, precise positioning and alignment of the access line on the housing and in the interior of the housing creates a turbulent environment around the at least one coolant line.

[0020] In an alternative exemplary embodiment, the access line is configured to accommodate at least a longitudinal section of the at least one coolant line, wherein an inner diameter of the access line is larger than an outer diameter of the at least one coolant line, at least in the region accommodating the at least one coolant line. Thus, a double-walled pipe section is realized over at least part of the longitudinal extent of the at least one coolant line, in which the at least one coolant line is surrounded by the fluid of the first coolant circuit within the access line, and in which the fluid of the first coolant circuit conducted through the access line is first guided along the at least one coolant line before subsequently entering the interior of the housing of the storage device. Consequently, cooling of the fluid already occurs within the access line.The access line has an inlet or inlet and an outlet or outlet, with the inlet facing the pump and the outlet facing the interior of the housing.

[0021] The inlet and outlet of the inlet line are preferably arranged with respect to the flow direction of the coolant through the at least one coolant line such that the fluid flows opposite to the coolant. This realizes a countercurrent process, which further improves heat transfer.

[0022] In a further development of the invention, the access line is arranged coaxially with the at least one coolant line, at least in the area accommodating the at least one coolant line. If both the access line and the at least one coolant line have a circular cross-section, the section of the at least one coolant line that passes through the access line is evenly surrounded on all sides by fluid from the first coolant circuit, thus achieving uniform heat transfer between the fluid and the coolant.

[0023] The invention includes the technical teaching that the at least one coolant line has elevations, depressions, projections, and / or recesses on a side facing the fluid of the first coolant circuit, so that a contact surface with the fluid of the first coolant circuit in the interior of the housing is enlarged. By increasing the contact surface of the at least one coolant line, the heat transfer between the fluid of the first coolant circuit and the coolant of the second coolant circuit is improved, whereby the heat exchanger and / or the plate cooler can be designed slimmer or smaller.In one embodiment, the at least one coolant line has cooling ribs, cooling fins and / or cooling fins on its surface which comes into contact with the fluid of the first coolant circuit, which serve to enlarge the surface of the at least one coolant line, thereby improving the cooling effect.

[0024] The elevations, depressions, projections, and / or recesses can be part of the at least one coolant line or can be designed as a separate component, wherein the component is in any case connected to the at least one coolant line in a heat-transfer manner. The projections can be designed as heat sinks, for example in the form of so-called "pin-fin" bodies, which are arranged on the side of the at least one coolant line facing the fluid of the first coolant circuit.

[0025] In a further embodiment, the at least one coolant line is designed as a through-opening, bore, and / or recess in the housing of the storage device. The at least one coolant line can therefore be designed, for example, in the form of a bore in the housing of the storage device. In this case, too, the fluid of the first coolant circuit can transfer heat to the coolant through the coolant guide on the housing. Such a design of the at least one coolant line is particularly easy to implement if the housing is manufactured by casting.

[0026] A drive device according to the invention for a hybrid or electric vehicle comprises a cooling system as described herein. The drive device can, in particular, comprise an electric drive axle or an electric drive train for an axle of the hybrid or electric vehicle. The drive device can comprise an electric machine and an optional transmission to provide torque for driving at least one drive wheel of the hybrid or electric vehicle. In addition to the electric machine, an electric control device can also be included, which in one embodiment can also be cooled by means of coolant from the second coolant circuit. The drive device can further comprise an energy storage device that supplies the electric machine with electrical energy.

[0027] The invention will now be described in more detail with reference to the accompanying figures, in which: Fig. 1 shows a drive device according to the invention in a motor vehicle with a cooling system according to the invention according to a first embodiment; Fig. 2a a longitudinal sectional view of a storage device of the cooling system according to the invention according to Fig. 1; Fig. 2b a cross-sectional view of the storage device of the cooling system according to the invention according to Fig. 1 and Fig. 2a; Fig. 3a a longitudinal sectional view of the storage device of the cooling system according to the invention according to a second embodiment; Fig. 3b a cross-sectional view of the storage device of the cooling system according to the invention according to Fig. 3a; and Fig. 4 shows a cross-sectional view of the storage device of the cooling system according to the invention according to a third embodiment.

[0028] Fig. 1 shows a drive device 100 according to the invention in a vehicle according to the invention, which can be designed as an electric or hybrid vehicle 105. Depending on the design of the vehicle, it can be driven either purely electrically or partially electrically and partially by an internal combustion engine. The drive device 100 is configured to drive at least one drive wheel 110 of the electric vehicle 105. For this purpose, an electric machine (not shown here) can be provided, which is supplied with electrical energy from an electrical energy storage device. A transmission (also not shown here) can also be provided to convert mechanical energy to the drive wheel 110. Optionally, the transmission is configured to be driven by a further drive machine (not shown), for example a reciprocating piston engine, so that the vehicle is designed as a hybrid vehicle.Furthermore, a differential (not shown here) can be provided to distribute the drive power to both drive wheels 110 of the vehicle shown in . Fig. 1 shown axis.

[0029] The electric or hybrid vehicle 105 also comprises a cooling system 115 according to the invention, which is Fig. 2a to 4 will be described in more detail below using three different embodiments. The cooling system 115 can be part of a hydraulic system for cooling and lubricating thermal consumers (not shown) of the electric vehicle 105, which, however, will not be discussed in detail here.

[0030] The cooling system 115 comprises a storage device 120 configured to receive and provide fluid from a first coolant circuit. The fluid can be pumped from a sump 130, here an oil sump, into an interior 135 of a housing 140 of the storage device 120 by means of a pump 125 of the hydraulic system, designed as a vane pump, in order to provide a sufficient amount of fluid for cooling or lubricating components at all times during operation. The storage device 120 can also be part of the hydraulic system and provides fluid that can be fed to at least one further pump 145 in order to supply the components with fluid, i.e., coolant and / or lubricant. Oil is preferred as the fluid within the meaning of the invention.

[0031] The pump 125 and the further pump 145 are operatively connected via a common shaft 150 to an electric motor 155, which drives the two pumps 125, 145.

[0032] The housing 140 is shown here with a base element 160 and side walls 165, 170, with the housing 140 being shown open at the top. Of course, it is conceivable to provide a cover element (not shown) so that the housing 140 spatially delimits an interior space 135 on all sides. The housing 140 is a cast component produced by casting.

[0033] The cooling system 115 comprises a second coolant circuit, which is at least configured to cool a power electronics unit 175 of the drive device 100, in particular a plate cooler of a power module. The power electronics unit 175 is fluidically connected to a heat exchanger 185 via a tubular coolant line 180 of the second coolant circuit. In the examples according to Fig. 1 to Fig. 3b only a single coolant line 180 is shown as an example, although it is of course conceivable to arrange and design further coolant lines - not shown here - in an analogous manner, cf. Fig. 4. Everything stated here and below regarding coolant line 180 is analogously applicable to other coolant lines.

[0034] In a first embodiment according to Fig. 1 to Fig. 2b, the coolant line 180 extends substantially horizontally between the two opposite side walls 165, 170 of the housing 140, wherein coolant in the illustration according to Fig. 1 and Fig. 2a flows in the coolant line 180 from right to left according to the arrow shown and is guided through the housing 140 below the fluid level 200 prevailing in the interior 135 of the housing 140. Thus, the coolant line 180 is arranged in the housing 140, wherein the fluid level 200 within the housing 140 is always selected such that the coolant line 180 is completely surrounded by fluid 205 in the interior 135 of the housing 140.

[0035] In the Fig. The cross-sectional view of the storage device 120 shown in Figure 2b shows an access line 210 that conducts the fluid delivered by the pump 125 to the storage device 120. The access line 210 of the first coolant circuit is designed to fluidically connect the interior 135 of the housing 140 to the pump 125. The access line 210 is positioned and aligned with respect to the tubular coolant line 180 such that the volume flow of the first coolant circuit delivered by the pump 125 is directed toward the coolant line 180 and thus generates turbulence on and around the coolant line 180 during delivery into the storage device 120, thereby improving the heat transfer between the fluid 205 of the first coolant circuit and the coolant of the second coolant circuit.Accordingly, the cooling effect is improved by the system proposed here, allowing the heat exchanger 180 and / or the plate cooler of the power electronics 175 to be reduced in size compared to known cooling concepts. This also allows existing fillings of the storage device to be easily utilized or optimized to create a turbulent environment around the coolant supply.

[0036] The Fig. 3a and Fig. 3b show a second embodiment of the cooling system 115, wherein only the differences from the first embodiment according to Fig. 1 to Fig. 2b is discussed.

[0037] The access line 210 is designed here such that the longitudinal section of the coolant line 180 arranged between the side walls 165, 170 is received therein and arranged coaxially therewith. Here, an outer diameter of the tubular coolant line 180 is selected to be smaller than an inner diameter of the access line 210, so that an annular gap is formed between the coolant line 180 and the access line 210, through which the fluid of the first coolant circuit flows following the arrows from an access 300, which is in the Fig. 3a and Fig. 3b, to an output 305, which is in Fig. 3a, before the fluid 205 enters the interior 135 of the housing 140. The arrows in the access line 210, which are directed essentially to the right, and the opposite arrow pointing to the left in the coolant line 180 are intended to illustrate that the coolant of the second coolant circuit and the fluid of the first coolant circuit are guided countercurrently to one another, thereby reducing the required cooling capacity at the heat exchanger 185. Thus, this example implements a double-walled coolant guide.

[0038] According to the third embodiment according to Fig. 4 is intended to illustrate that the coolant line 180 does not necessarily have to be guided as a pipe through the fluid 205 in the interior 135 of the housing 140, but an improvement in the cooling performance can also be achieved if the coolant line 180 is designed as a through-opening, bore and / or recess in the housing 140 of the storage device 120. Furthermore, the superimposed circles or bores 400 in the right side wall 170 of the housing 140 are intended to illustrate that more than one coolant line 180 can be provided. The routing of the access line 210 is analogous to Fig. 2b, with reference to the relevant text passages.

[0039] For all exemplary embodiments, the coolant line 180 can have elevations, depressions, projections, and / or recesses on a side facing the fluid of the first coolant circuit, i.e., here on the outer circumference, so that a surface area of ​​the outer skin of the coolant line 180 containing the fluid 205 of the first coolant circuit is enlarged. In particular, the outer surface area of ​​the coolant line 180 can be enlarged by pin-fin bodies.

[0040] The invention is not limited to the disclosed embodiments. Other embodiments or variations will become apparent to those skilled in the art upon application of the present invention and upon careful analysis of the drawings, the description, and the patent claims. In particular, the illustrated embodiments can be combined with one another to best optimize the cooling performance of the system and thus to design the heat exchanger 185 and / or cooling elements of the power electronics 175 as slim, space-saving, and thus more cost-effectively as possible. Reference symbol 100 drive device 105 electric vehicles 110 drive wheel 115 Cooling system 120 storage facility 125 pump 130 Swamp 135 Interior 140 housings 145 Pump 150 wave 155 electric motor 160 floor element 165 side wall 170 side wall 175 Power Electronics 180 coolant line 185 heat exchangers 200 fluid level 205 Fluid 210 access line 300 access 305 Exit 400 drilling 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 2018 213 394 A1

[0003]

Claims

[1] Cooling system (115) for a drive device (100) of a hybrid or electric vehicle (105), comprising a storage device (120) which is designed to receive and provide fluid of a first coolant circuit which has been conveyed by means of a pump (125) from a sump (130) into an interior space (135) of a housing (140) of the storage device (120), wherein at least one coolant line (180) of a second coolant circuit is provided on and / or in the housing (140), which is designed to conduct coolant from a power electronics unit (175) to a heat exchanger (185). [2] Cooling system (115) according to claim 1, wherein an access line (210) of the first coolant circuit is arranged on the storage device (120), which access line is designed to fluidically connect the interior (135) of the housing (140) to the pump (125). [3] Cooling system (115) according to claim 1 or claim 2, wherein the at least one coolant line (180) is substantially tubular and is guided at least partially through the interior (135) of the housing (140), wherein the at least one coolant line (180) is at least partially surrounded by the fluid of the first coolant circuit located in the interior (135) of the housing (140). [4] Cooling system (115) according to claim 2 in conjunction with claim 3, wherein the access line (210) is positioned and aligned with respect to the at least one coolant line (180) such that a volume flow of the first coolant circuit is directed toward the at least one coolant line (180). [5] Cooling system (115) according to claim 2, wherein the access line (210) is configured to receive at least a longitudinal section of the at least one coolant line (180), wherein an inner diameter of the access line (210) is larger than an outer diameter of the at least one coolant line (180) at least in the region receiving the at least one coolant line (180). [6] Cooling system (115) according to claim 5, wherein the access line (210) is arranged coaxially to the at least one coolant line (180) at least in the region receiving the at least one coolant line (180). [7] Cooling system (115) according to one of the preceding claims, wherein the at least one coolant line (180) has elevations, depressions, projections and / or recesses on a side facing the fluid of the first coolant circuit, so that a contact surface with the fluid of the first coolant circuit in the interior (135) of the housing (140) is enlarged. [8] Cooling system (115) according to claim 1 or claim 2, wherein the at least one coolant line (180) is designed as a through-opening, bore (400) and / or recess in the housing (140) of the storage device (120). [9] Cooling system (115) according to one of the preceding claims, wherein the housing (140) is made by casting. [10] Drive device (100) for a hybrid or electric vehicle (105), comprising a cooling system (115) according to one of the preceding claims.

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