Drive unit with tolerance compensation

Abstract

The invention relates to a drive unit (16, 20) for a motor vehicle drive, comprising an inverter housing (17, 21) in which an inverter (4) can be arranged, at least one electric motor-gearbox housing (18) in which a drive unit can be arranged, and at least one heat exchanger (1) which is fluidically connected to the inverter (4) and the drive unit, wherein the inverter housing (17, 21) as well as the electric motor-gearbox housing (18) each have a connection surface (41, 42) which, with the interposition of sealing rings (36, 39), are designed to abut a heat exchanger flange surface (40) of the at least one heat exchanger (1). The connection surface (41) of the inverter housing (17, 21) is offset relative to the connection surface (42) of the at least one electric motor gearbox housing (18).

Description

[0001] The invention relates to a drive unit for a motor vehicle drive with an inverter housing in which an inverter or a double inverter can be arranged or is arranged, at least one electric machine transmission housing in which an electric machine and / or a transmission can be arranged or is arranged, and at least one heat exchanger which is provided to be fluidically connected to the inverter and the electric machine and / or the transmission.

[0002] In electric drive units that use oil-cooled electric motors and water-cooled inverters, and particularly in so-called twin drive units that use two oil-cooled electric motors and a water-cooled double inverter arranged between the two electric motors, the inverter or double inverter is centrally water-cooled, for example with water / glycol, and the water cooling circuit is routed to a heat exchanger after the inverter or double inverter. The heat exchanger cools the electric motor and the gearbox. Cooling oil flows through the heat exchanger, which then flows into a stator of the electric motor and then into the gearbox to cool and lubricate it. In twin drive units, the water cooling circuit is split between two heat exchangers (i.e. one heat exchanger per electric motor) so that the water flows through the heat exchangers separately on the water side.After the heat exchanger, the water circuits of the two heat exchangers are combined and fed to the vehicle at a central collection point.

[0003] Thus, the water cooling circuit is located in the inverter housing, while the oil cooling circuit is located in the electric motor / transmission housing. This means that the heat exchanger spans two different housings and must be reliably sealed at its respective transfer points.

[0004] In the current state of the art, the fluid connection / sealing to the heat exchanger can be achieved, in particular, via an axially sealing O-ring connection (from the rear) or via a hose connection (via a clamp / hose or a quick connector, etc.), for example using a clamp and hose or a quick connector (from the rear). However, the axially sealing O-ring connection can only be used if sufficient installation space is available for its robust design (axial seal with a large cord thickness) on the corresponding (housing) side or on both sides. When assembling on two separately manufactured housing components, in this case the inverter housing and the electric motor gearbox housing, which are only connected, in particular screwed, to one another at a later stage in the assembly process, sufficiently precise positioning of the axial sealing surface on the two housing components cannot always be guaranteed.This is because, despite pre-positioning the two housing components using centering pins, the respective manufacturing tolerances on the two housing components add up and therefore do not meet the requirements. In addition, joint machining is not possible because it would be too cost-intensive and entails the risk of contamination of the inverter by conductive metallic particles, or because the housing is already equipped with dirt-sensitive components at this point. In such applications, the basic premise is to use the largest possible cross-sectional area on all axially sealing O-rings so that they can better compensate for axial gaps due to varying degrees of compression (due to temperature, tolerance influences, etc.). However, due to installation space constraints, the oil and water side connections cannot usually be realized with corresponding O-rings with a larger cross-sectional area.Due to space constraints, no other arrangement of the heat exchanger at vehicle level is possible and therefore a design solution is required to create appropriate tolerance compensation.

[0005] The object of the invention is therefore to avoid or at least mitigate the disadvantages of the prior art. In particular, a drive unit is to be provided in which the sealing of the respective connections can be ensured.

[0006] This object is achieved by a drive unit for a motor vehicle drive with an inverter housing, at least one electric motor transmission housing and at least one heat exchanger, with the features of patent claim 1, namely that a connection surface of the inverter housing, which is designed to engage a heat exchanger flange surface, is offset relative to a connection surface of the at least one electric motor transmission housing, which is designed to engage the heat exchanger flange surface.

[0007] The invention accordingly relates to a drive unit for a motor vehicle drive, comprising an inverter housing in which an inverter such as a single inverter or a double inverter can be or is arranged, at least one electric motor transmission housing in which a drive unit such as an electric motor with or without a transmission can be or is arranged, and at least one heat exchanger which is provided to be fluidly connected to the inverter and the drive unit, wherein the inverter housing and the electric motor transmission housing each have a connection surface which, with the interposition of sealing rings, is designed to bear against a heat exchanger flange surface of the at least one heat exchanger. According to the invention, the connection surface of the inverter housing is offset relative to the connection surface of the at least one electric motor transmission housing.In other words, the at least one heat exchanger spans a portion of the at least one electric motor transmission housing and a portion of the inverter housing. The connecting surfaces of these housings are arranged at different distances from the heat exchanger, meaning that the connecting surfaces of the electric motor transmission housing and the inverter housing are each offset relative to one another. Alternatively, a stepped heat exchanger can be designed, but this impairs the manufacture or design of the drive unit. Alternatively, the inverter housing and the electric motor transmission housing can be machined together, but this requires additional processing and complicates handling.

[0008] For the sake of clarity, it should be added that the inverter housing may contain an electrical inverter with its own housing that houses the electronic components provided by the inverter.

[0009] This arrangement of the housing halves with a relative offset to each other has the advantage that a summation of tolerances across both housing halves of the drive unit in the area of ​​the interface to the heat exchanger can be compensated.

[0010] Advantageous embodiments are the subject of the subclaims and are explained in more detail below.

[0011] According to a preferred embodiment, in the operating state of the drive unit, the connection surface of the inverter housing lies almost flush with the heat exchanger flange surface, and the connection surface of the at least one electric motor transmission housing is offset from the heat exchanger flange surface. This means that the connection surface of the housing half of the at least one electric motor transmission housing is spaced from the heat exchanger flange surface at a greater distance than the connection surface of the housing half of the inverter housing. Thus, a housing offset exists between the connection surface of the at least one electric motor transmission housing and the heat exchanger flange surface.

[0012] In a further advantageous embodiment, the at least one heat exchanger has a water connection for connection to water channels of the inverter and an oil connection for connection to oil channels of the drive unit, wherein the water connection and the oil connection each have a connection interface for sealingly connecting to the associated water channels or oil channels.

[0013] According to a further preferred aspect of the invention, the sealing rings, preferably in the form of O-rings, are arranged at the connection interfaces for fluidic, in particular axial, sealing. This means that the respective O-rings are arranged axially between the two components to be sealed together and surround the fluid channel to be sealed. Thus, the components to be connected are axially adjacent to one another during this axial sealing. With the help of these axial seals via the O-rings / sealing rings, compensation for axial offsets between the connection surfaces of the housing parts is possible.

[0014] According to a preferred embodiment, the offset between the connection surfaces of the inverter housing and the at least one electric motor transmission housing with respect to the heat exchanger flange surface is bridged via the sealing rings.

[0015] According to a further advantageous embodiment, the sealing rings on the electric motor side have larger cord thicknesses than the sealing rings on the inverter side. In other words, the sealing rings of the connection interfaces on the electric motor side have larger cross-sectional diameters than the sealing rings of the inverter side connection interfaces. A special form of sealing with axially sealing sealing rings with small cord thicknesses and axially sealing sealing rings with large cord thicknesses thus serves to compensate for tolerances. In the inverter housing, in which only sealing rings with small cord thicknesses can be integrated due to installation space constraints, the theoretical tolerance zero line for the common flange surface is set and achieved via targeted dimensional chain tolerancing of the housings (of the inverter and the at least one electric motor orgearbox) to each other, any step change in the axial sealing surface that may arise due to manufacturing influences is directed specifically to the sealing ring in the at least one electric motor housing with the sealing rings with the larger cord thicknesses, i.e. the sealing rings with the larger cord thicknesses compensate for the gap caused by the offset. The housing offset is on the side with the larger / thicker sealing rings, since the larger cord thickness of these sealing rings means that more tolerances can be accommodated. The offset is dimensioned to accommodate coarse tolerances. This also ensures a cost reduction for the heat exchanger component, since no projections are required for sealing, e.g. in the form of cylindrical tubes on the flange plate of the heat exchanger. The inferior alternative solution of using sealing rings with large cord thicknesses at all connection interfaces would entail an undesirable increase in installation space.

[0016] In a further advantageous embodiment of the invention, the offset between the connecting surfaces of the inverter housing and the electric motor transmission housing relative to the heat exchanger flange surface is fixed via at least one locating pin that couples the inverter housing and the electric motor transmission housing to each other. This means that the relative arrangement of the inverter housing and the electric motor transmission housing to each other is adjusted via the locating pin, which is why the ultimately resulting offset of these connecting surfaces relative to each other is fixed via the locating pin.

[0017] According to a preferred embodiment, the at least one heat exchanger or the at least one electric motor transmission housing has a contact element that bridges the offset during assembly or when screwing the heat exchanger to the electric motor transmission housing. The contact element advantageously prevents any possible tilting of the heat exchanger with respect to the electric motor transmission housing, since the distance or the housing offset is (temporarily) bridged during the assembly process.

[0018] According to a further preferred aspect of the invention, the drive unit comprises a (double) inverter housing in which a double inverter can be arranged, a first electric motor transmission housing in which a first electric motor and / or a first transmission can be arranged or is arranged, a second electric motor transmission housing in which a second electric motor and / or a second transmission can be arranged or is arranged, and two heat exchangers. One of the two heat exchangers is arranged partially in the inverter housing and partially in the first electric motor transmission housing, and the other of the two heat exchangers is arranged partially in the inverter housing and partially in the second electric motor transmission housing. Thus, the drive unit in this embodiment is designed as a twin drive unit.Here, too, it should be explained that two electronic components designed as inverters can be used in the (double) inverter housing, which in turn can have one or two separate housings.

[0019] According to a preferred embodiment, the two heat exchangers are arranged such that the respective water connection is arranged in the inverter housing and the oil connection is arranged in the first electric motor transmission housing or the second electric motor transmission housing.

[0020] The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description and / or figures. In particular, it should be noted that the figures and in particular the proportionalities shown are only schematic. Identical features are referenced with the same reference numerals. Furthermore, it should be noted that the features of the individual embodiments can be interchanged and occur in a specific combination.

[0021] The present invention and two advantageous embodiments are described below with reference to the figures. They show: Fig. 1 a perspective view of a heat exchanger of the drive unit according to the invention according to a first advantageous embodiment, Fig. 2 a section of a perspective view of a drive unit according to the invention according to the first advantageous embodiment, Fig. 3 a schematic representation of the drive unit according to the invention according to a second advantageous embodiment, Fig. 4 an isometric view of an electric motor transmission housing of the drive unit according to the invention according to the first advantageous embodiment, Fig. 5 an isometric view of an inverter housing of the drive unit according to the invention according to the first advantageous embodiment, and Fig. 6 a section of a schematic longitudinal sectional view through the drive unit according to the invention according to the second advantageous embodiment.

[0022] The figures are merely schematic and serve solely to clarify the invention. The same elements are designated by the same reference numerals.

[0023] Fig. 1 shows a heat exchanger 1 for a motor vehicle drive. The heat exchanger 1 has a water connection 2 for connecting to water channels 3 of an inverter 4. The heat exchanger 1 also has an oil connection 5 for connecting to oil channels 6 of an electric motor 7 and / or a transmission 8. The water connection 2 has two connection interfaces 9, 10 for sealed connection to the associated water channels 3. One of the two connection interfaces 9, 10 serves as a water inlet 9 and the other of the two connection interfaces 9, 10 serves as a water outlet 10. The oil connection has two connection interfaces 11, 12 for sealed connection to the associated oil channels 6. One of the two connection interfaces 11, 12 serves as an oil inlet 11 and the other of the two connection interfaces 11, 12 serves as an oil outlet 12.

[0024] The connection interfaces 9, 10 of the water connection 2 are designed such that sealing occurs axially, and the connection interfaces 11, 12 of the oil connection 5 are designed such that sealing occurs radially. The axial sealing is achieved in particular via O-rings (not shown here). The axial sealing is achieved in particular via sealing nozzles and O-rings (not shown here). The connection interfaces 9, 10 of the water connection 2 and the connection interfaces 11, 12 of the oil connection 5 are each designed identically, i.e. the same sealing concept (axial / radial) is used.

[0025] The heat exchanger 1 has a base plate 13 with fastening openings 14 for attachment to a housing component of the motor vehicle drive. The fastening openings 14 are arranged in the region of fastening tabs 15. The fastening openings 14 are arranged closer to the connection interfaces 9, 10 of the water connection 2 than to the connection interfaces 11, 12 of the oil connection 5. In particular, the connection interfaces 9, 10 of the water connection 2 are arranged between the fastening openings 14. This allows a maximum axial preload to be applied to the base plate 13 in the region of the connection interfaces 9, 10 of the water connection 2.

[0026] Fig. Figure 2 shows the heat exchanger 1 mounted in a drive unit 16 according to a first advantageous embodiment. The drive unit 16 has an inverter housing 17, in which the inverter 4 can be arranged, and an electric motor transmission housing 18, in which the electric motor 7 and / or the transmission 8 can be arranged, wherein the inverter housing 17 and the electric motor transmission housing 18 are connected to one another via a housing flange 19. The heat exchanger 1 is arranged partially in the inverter housing 17 and partially in the electric motor transmission housing 18. The heat exchanger 1 is arranged such that the water connection 2 is located in the inverter housing 17 and the oil connection 5 is located in the electric motor transmission housing 18.

[0027] Fig. 3 shows a drive unit 20 according to a second advantageous embodiment, in particular in the form of a twin drive unit 20, for a motor vehicle drive. The twin drive unit 20 has a double inverter housing 21 in which a double inverter 22 can be arranged, a first electric motor transmission housing 23 in which a first drive unit such as a first electric motor 24 and / or a first transmission 25 can be arranged, and a second electric motor transmission housing 26 in which a second drive unit such as a second electric motor 27 and / or a second transmission 28 can be arranged, wherein the double inverter housing 21 and the first electric motor transmission housing 23 are connected to one another via a first housing flange 29 and the double inverter housing 21 and the second electric motor transmission housing 26 are connected to one another via a second housing flange 30. In addition, the twin drive unit 20 has two heat exchangers 1.One of the two heat exchangers 1 is arranged partially in the double inverter housing 21 and partially in the first electric motor transmission housing 23, and the other of the two heat exchangers 1 is arranged partially in the double inverter housing 21 and partially in the second electric motor transmission housing 26. The two heat exchangers 1 are arranged such that the respective water connection 2 is located in the double inverter housing 21 and the oil connection 5 is located in the first electric motor transmission housing 23 or the second electric motor transmission housing 26.

[0028] Fig. 4 shows an isometric view of an electric motor transmission housing 18 of the drive unit 16 according to the invention, according to the first advantageous embodiment. The electric motor transmission housing 18 has a cuboidal box shape with an open front (in this view) as well as four side walls and a rear wall. The front is designed to accommodate an electric motor 7 and / or a transmission 8. In addition, the electric motor transmission housing 18 has a circumferential flange surface with through holes or blind holes for connecting an inverter housing 17. Furthermore, two circular oil connections 5 are arranged on one of the side walls of the electric motor transmission housing 18.The flange surface has a bore at a corner point, which is approximately at the junction of the upper side wall (shown in this view) and the side wall which is arranged opposite the side wall with the oil connections 5, for receiving a dowel pin as the electric motor transmission housing reference point 31. The bore shown in . Fig. The dashed line shown in Figure 4 represents a horizontal oil connection distance 32, i.e. the horizontal distance between the oil connections 5 and a theoretical vertical which intersects the electric motor transmission housing reference point 31.

[0029] Fig. Figure 5 shows an isometric view of an inverter housing 17 of the drive unit 16 according to the first advantageous embodiment. The inverter housing 17 also has a cuboidal box shape with an open front (in this view) as well as four side walls and a rear wall. The front is designed to accommodate an inverter 4 or a double inverter 22. The inverter housing 17 is complementary to the housing shown in Fig. 4 and also has a circumferential flange surface for mounting the electric motor gear housing 18. Two circular water connections 2 are arranged on one of the side walls of the inverter housing 17 and the flange surface has a dowel pin at a corner point, which is approximately at the junction of the upper side wall (shown in this view) and the side wall which is arranged opposite the side wall with the water connections 5, which is for receiving in the bore representing the electric motor gear housing reference point 31 as the inverter housing reference point 33. The Fig. The dashed line shown in Figure 5 represents a horizontal water connection distance 34, i.e. the horizontal distance between the water connections 2 and a theoretical vertical which intersects the inverter housing reference point 33.

[0030] Fig. Figure 6 shows a section of a schematic longitudinal sectional view through the drive unit 20 according to the invention according to the second advantageous embodiment of a twin drive unit. The illustrated section of the (twin) drive unit 20 shows the inverter housing 17 (located on the right in this view) with a water channel 3 and the (located on the left in this view and in Fig. 3) with an oil channel 6. The inverter housing 17 is connected to the second electric motor transmission housing 26 or flanged thereto. Furthermore, a heat exchanger 1 is arranged on one side, which extends over a part of the inverter housing 17 and over a part of the second electric motor transmission housing 26 and is connected / coupled to them. The connection surface 41 of the inverter housing 17 almost abuts the heat exchanger 1, with the water channel 3 being fluidically sealed by an inverter-side sealing ring 39 with a small / narrow cord thickness, in particular with a maximum cross-sectional diameter of 2.62 mm. In contrast, the connection surface 42 of the second electric motor transmission housing 26 is arranged with a housing offset 35, preferably in a range between -0.1 and 0.3 mm, relative to the heat exchanger flange surface 40.This offset is bridged with an electric motor-side sealing ring 36 with a large cord thickness or a larger cord thickness, preferably with a minimum cross-sectional diameter of 5.33 mm, than the cord thickness of the inverter-side sealing ring 39.

[0031] The sealing by the sealing rings 36, 39 is in the special form axial / axial due to tolerance compensation, i.e. the sealing rings 36, 39 seal the water channel 3 and the oil channel 6 axially. The size ratios of the two sealing rings 36, 39 in Fig. 6 are shown only schematically. Theoretical dimensioning chains or sizes are shown in the form of arrows. The heat exchanger flange surface 40 of the heat exchanger, which faces the inverter housing 17 and the second electric motor gearbox housing 26, forms a theoretical tolerance zero line for the dimensioning. In addition, the horizontal oil connection distance 32, preferably a distance of 354.5 mm (- 0.2 mm), is taken from the Fig. 4 and the groove depth 37, preferably 3.9 mm (+0.1 mm), of the groove for receiving the electric motor-side sealing ring 36 in the second electric motor gearbox housing 26. The groove bottom-flange surface distance 38, preferably in a range between 3.9 mm and 4.2 mm, represents the distance between the groove bottom of the groove in the electric motor gearbox housing 26 and the heat exchanger flange surface 40. Furthermore, the horizontal water connection distance 34, preferably a distance of 354.5 mm ± 0.1 mm, is shown in the Fig.5 shown schematically. List of reference symbols 1 heat exchanger 2 water connections 3 water channel 4 inverters 5 Oil connection 6 Oil channel 7 electric motor 8 gearboxes 9 Connection interface / water inlet 10 Connection interface / water outlet 11 Connection interface / oil inlet 12 Connection interface / oil outlet 13 Base plate 14 Mounting hole 15 Mounting tab 16 Drive unit 17 Inverter housing 18 Electric motor gearbox housing 19 Housing flange 20 (Twin) drive unit 21 (Double) Inverter Housing 22 double inverters 23 first electric motor transmission housing 24 first electric machine 25 first gearbox 26 second electric motor transmission housing 27 second electric motor 28 second gearbox 29 first housing flange 30 second housing flange 31 Electric motor gearbox housing reference point 32 horizontal oil connection distance 33 Inverter housing reference point 34 horizontal water connection distance 35 Case offset 36 E-machine side sealing ring 37 groove depth 38 Groove bottom-flange surface distance 39 Inverter-side sealing ring 40 Heat exchanger flange surface 41 Connection surface of the inverter housing 42 Connection surface of the machine gear housing

Claims

[1] Drive unit (16, 20) for a motor vehicle drive, with an inverter housing (17, 21) in which an inverter (4) can be arranged, at least one electric motor transmission housing (18) in which a drive unit can be arranged, and at least one heat exchanger (1), wherein the inverter housing (17, 21) and the electric motor transmission housing (18) each have a connection surface (41, 42) which, with the interposition of sealing rings (36, 39), are designed to bear against a heat exchanger flange surface (40) of the at least one heat exchanger (1), characterized by that the connection surface (41) of the inverter housing (17, 21) is offset relative to the connection surface (42) of the at least one electric motor transmission housing (18). [2] Drive unit (16, 20) according to claim 1, characterized byin the operating state of the drive unit (16, 20), the connection surface (41) of the inverter housing (17, 21) almost abuts the heat exchanger flange surface (40) and the connection surface (42) of the at least one electric motor transmission housing (18) is spaced apart from the heat exchanger flange surface (40) by an offset. [3] Drive unit (16, 20) according to claim 1 or 2, characterized by in that the at least one heat exchanger (1) has a water connection (2) for connection to water channels (3) of the inverter (4) and an oil connection (5) for connection to oil channels (6) of the drive unit, wherein the water connection (2) and the oil connection (5) each have a connection interface (9, 10, 11, 12) for sealingly connecting to the associated water channels (3) or oil channels (6). [4] Drive unit (16, 20) according to claim 3, characterized bythat the sealing rings (36, 39), preferably in the form of O-rings, are each arranged at the connection interfaces (9, 10, 11, 12) for fluidic, in particular axial, sealing. [5] Drive unit (16, 20) according to claim 4, characterized by that the offset between the connection surfaces (41, 42) of the inverter housing (17, 21) and the at least one electric motor transmission housing (18) with respect to the heat exchanger flange surface (40) is bridged via the sealing rings (36, 39). [6] Drive unit (16, 20) according to claim 4 or 5, characterized by that the sealing rings (36) on the electric machine side have greater cord thicknesses than the sealing rings (39) on the inverter side. [7] Drive unit (16, 20) according to one of the preceding claims, characterized bythat the offset between the connection surfaces (41, 42) of the inverter housing (17, 21) and the electric motor transmission housing (18) with respect to the heat exchanger flange surface (40) is fixed via at least one dowel pin which couples the inverter housing (17, 21) and the electric motor transmission housing (18) to one another. [8] Drive unit (16, 20) according to one of the preceding claims, characterized by that the at least one heat exchanger (1) or the at least one electric motor transmission housing (18) has a contact element which bridges the offset during assembly of the heat exchanger (1) to the electric motor transmission housing (18). [9] Drive unit (20) according to one of the preceding claims, characterized bythat the drive unit (20) has a (double) inverter housing (21) in which a double inverter (22) can be arranged, a first electric machine transmission housing (23) in which a first electric machine (24) and / or a first transmission (25) can be arranged, a second electric machine transmission housing (26) in which a second electric machine (27) and / or a second transmission (28) can be arranged, and two heat exchangers (1), and one of the two heat exchangers (1) is arranged partly in the inverter housing (21) and partly in the first electric machine transmission housing (23), and the other of the two heat exchangers (1) is arranged partly in the inverter housing (21) and partly in the second electric machine transmission housing (26) is arranged. [10] Drive unit (16) according to claim 9, characterized bythat the two heat exchangers (1) are arranged such that the respective water connection (2) is arranged in the inverter housing (21) and the oil connection (5) is arranged in the first electric machine transmission housing (23) or the second electric machine transmission housing (26).

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