EP4029131A1

EP4029131A1 - Power electronics module having a sealing sheathing attached via an adhesion agent, electrical drive machine and production method

Info

Publication number: EP4029131A1
Application number: EP20767720.4A
Authority: EP
Inventors: Andreas Ruppert
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2019-09-10
Filing date: 2020-08-25
Publication date: 2022-07-20
Also published as: US20220329126A1; WO2021047722A1; DE102019124229A1; CN114287100A

Abstract

The invention relates to a power electronics module (1) for an electrical drive machine (10) of a motor vehicle (2a, 2b, 2c), comprising multiple bus bars (2a, 2b, 2c) and a potting element (3) supporting the bus bars (2a, 2b, 2c) such that they are spaced apart and electrically insulated from one another, wherein each bus bar (2a, 2b, 2c) is exposed in a first connection region (4) and a second connection region (5), opposite the first connection region (4), for further contact with the environment of the potting element (3), wherein the bus bars (2a, 2b, 2c) are provided with a sealing sheathing (9), applied separately to the potting element (3), on a longitudinal section (8) between the two connection regions (4, 5) arranged in a common recess (6) in the potting element (3) made from a plastic material, with said sealing sheathing (9) being adhered to the bus bar (2a, 2b, 2c) via a layer of adhesion agent (7). The invention also relates to an electrical drive machine (10) comprising said power electronics module (1), as well as a method of a power electronics module (1).

Description

Power electronics module with attached via an adhesion promoter

Dichtunqsummantelunq; electric prime mover; as well as manufacturing processes

The invention relates to a power electronics module for an electric drive machine of a purely electrically or hybrid-powered motor vehicle, such as a car, truck, bus or other commercial vehicle, with several busbars such as a potting body that supports the busbars apart and electrically isolated from one another, with each busbar on a first connection area and a second connection area opposite the first connection area for further contact to the surroundings of the potting body. The invention also relates to an electric drive machine with this power electronics module and a method for producing this power electronics module.

A power electronics module 1 known in principle from the prior art is shown in FIG. 9. This power electronics module 1 has several busbars 2 which are arranged in a potting body 3 and enclosed by this potting body 3. The power electronics module 1 is arranged in its drive machine installed state with one part in a dry space and with another part in a wet space of a housing of the electric drive machine sealed from the dry space. To seal the wet room compared to the dry room, a circumferential device 15 is arranged on the potting body 3 in a gap area between a receiving hole in the housing and an outside of the potting body 3.

However, it has been found to be a disadvantage of these designs known from the prior art that, despite the seal arranged on the outside, a liquid can penetrate from the wet area into the interior of the power electronics module over a certain operating time. Due to the prevailing capillary forces, there is a constant entry of liquid into the gaps between the busbars and the potting body. This leads to, that liquid can even enter the drying room after it has penetrated the power electronics module. This effect is reinforced by the strongly fluctuating ambient temperatures, since busbars and potting bodies have different coefficients of thermal expansion.

It is therefore an object of the present invention to eliminate the disadvantages known from the prior art and, in particular, an between a dryer. And to provide a power electronics module that can be used in a wet room of an electric drive machine and that causes a more reliable sealing of these rooms over the service life of the electric drive machine.

This is achieved according to the invention in that the busbars are each provided on a longitudinal section between their two connection areas, arranged in a common recess of the composite body cast from a (first) plastic material, with a sealing jacket applied separately to the potting body, which sealing jacket has a Adhesion promoter layer adheres to the busbar.

As a result, an inner seal is made available within the power electronics module in a compact and easy-to-manufacture manner, which prevents a liquid transported by capillary forces from passing from a wet area into a dry area of the electric drive machine during operation. The power electronics module is therefore designed to implement a more durable electric drive machine.

Further advantageous designs are claimed with the subclaims and explained in more detail below.

Accordingly, it is furthermore advantageous if the busbars are surface-activated in the longitudinal section surrounded by the adhesion promoter layer. This further increases the adhesive force between the sealing jacket / the adhesive layer and the busbar. It is also advantageous if three busbars are provided, each of which is arranged with its longitudinal section within the recess (and is furthermore coupled to the sealing jacket in the usual way via an adhesion promoter layer). This enables the power electronics module to have a compact design.

If the recess is formed as a through hole penetrating the potting body, its production can be implemented particularly easily in conventional casting processes, preferably injection molding processes.

In addition, it is advantageous if the through hole is closed by a cover at its end region which is spaced apart from the busbars. This further simplifies the manufacture of the sealing jacket.

It is therefore particularly advantageous if the sealing jacket is implemented directly with a filling that is cast into the recess (consisting of a second plastic material).

In addition, it is expedient if a seal running around the potting body is accommodated on an outside of the potting body, on a side of the recess facing the second connection areas. This results in a space-saving relative arrangement between the inner seal and the outer seal.

Furthermore, the invention relates to an electric drive machine for a motor vehicle, with a housing, the housing having a wet space accommodating a stator and a dry space sealed relative to the wet space, and with a power electronics module according to the invention according to at least one of the previously described embodiments, wherein the first connection areas of the busbars are arranged in the dry room and the second connection areas of the busbars, which are further connected to windings of the stator, are arranged in the wet room. In addition, the invention relates to a method for producing a power electronics module for an electrical drive machine of a motor vehicle, wherein in a first step a plurality of busbars are encapsulated by a first plastic material (preferably in an injection molding process) in such a way that the busbars form one potting body after curing first plastic materials are kept as spaced apart and electrically insulated from one another and are each arranged with a longitudinal section within a recess of the potting body exposed to the environment, in a second step (after step a), ie after the potting body has completely cured, an adhesion promoter layer is applied to the longitudinal section of each busbar and, in a third step, a second plastic material is poured into the recess, so that the second plastic material, after it has hardened, acts as a sealing jacket over the adhesive Layer adheres to the longitudinal portion of each bus bar.

In other words, an oil-tightness of a high-voltage component is guaranteed according to the invention. In addition to a common (outer) seal between the power electronics (power electronics module) and the E-Drive / electric drive (electric drive machine), a small chamber (recess) is cast into the plastic housing (potting body), through which chamber the copper rails (busbars) between the electric motor (stator) and the electronics run through. The copper bars are treated with an adhesion promoter (/ primer) to increase their adhesion. The chamber is then filled with a cast component sealing jacket.

The invention will now be explained in more detail below with reference to figures.

Show it:

1 shows a side view of a power electronics module according to the invention according to a preferred exemplary embodiment, in which, in addition to an outer seal accommodated on the outside of a potting body, a recess can be seen within which a sealing casing surrounding a plurality of busbars is shown transparently, Fig. 2 is a perspective detailed view of the sealing casing (shown transparently) receiving recess from the outside,

FIG. 3 shows a perspective illustration of the entire power electronics module according to FIG. 1,

4 shows a perspective illustration of a partially sectioned electrical drive machine with the power electronics module according to the invention according to FIGS. 1 to 3, whereby in addition to a wet room, a dry room which is sealed off relative to this wet room can be clearly seen,

FIG. 5 shows a view from below of the power electronics module according to FIG. 1, wherein a cover closing off the recess towards an underside can be seen,

6 shows a perspective detailed view of the underside already shown in FIG. 5 with an exploded view of the cover and the sealing casing of the rest of the potting body,

7 shows a partially transparent illustration of the power electronics module shown from the bottom according to FIG. 5,

FIG. 8 shows a partially transparent illustration of the power electronics module shown from the top according to FIG. 1, as well as

9 is a perspective view of a power electronics module known from the prior art.

The figures are only of a schematic nature and are used exclusively for understanding the invention. The same elements are provided with the same reference numerals.

A power electronics module 1 according to the invention is shown in isolation with FIGS. 1, 3, 5, 7 and 8 can be recognized. The power electronics module 1, as can also be seen in FIG. 4, is used in its preferred area of application in an electric drive machine 10 of a motor vehicle. The electric drive machine 10 is implemented in the usual way as an electric motor having a stator 17 and a rotor, not shown here for the sake of clarity. The electric drive machine 10 is preferably used to drive a hybrid motor vehicle, more preferably to drive a purely electrically driven motor vehicle. The electric drive machine 10 is thus preferably integrated in a hybrid module (drive module with clutches) or an e-axis (electric drive axle unit).

As can also be seen in FIG. 4, the electric drive machine 10 is at least its stator 17 implemented directly / directly liquid-cooled. The electric drive machine 10 accordingly has a wet space 18 that accommodates the stator 17 and a drying space 19 which is sealed off relative to this wet space 18. Wet space 18 and dry space 19 form sub-spaces within a common housing 16 of the electric drive machine 10. In the dry space 19, further electronic components are then typically arranged that are not surrounded by a cooling liquid flowing through the wet space 18 during operation. The power electronics module 1 according to the invention is now designed as a connecting element between the windings 21 of the stator 17 and the electronic components not shown closer for the sake of clarity.

The further basic design of the power electronics module 1 can be seen particularly well in FIG. 3. The power electronics module 1 has a potting body 3, which can be seen from the outside, in the form of a plastic housing. The potting body 3 is molded around several, here three, busbars 2a, 2b, 2c and then cured so that it receives the busbars 2a, 2b, 2c at a distance from one another and electrically decoupled from one another. Each busbar 2a, 2b, 2c is exposed on the part of a first connection area 4 in the drying room 19 to the surroundings of the power electronics module 1. A second connection area 5 of the respective busbar 2a, 2b, 2c opposite the respective first connection area 4 is exposed to the area of the potting body 3 arranged in the wet room 18 and connected to the windings 21 of the Stator 17 further connected. Between the connection areas 4, 5, each busbar 2a, 2b, 2c is completely encased in plastic material.

A seal 15 is arranged between the two connection areas 4, 5 on an outer side 14 of the casting body 3 in an annular groove. This acting as the outer seal of the power electronics module 1 seal 15 serves immediacy for sealing a gap 22 formed between the housing 16 of the electrical drive machine 10 and the potting body 3 (FIG. 4). As can be seen, this seal 15 is designed with an essentially circular cross section in the sense of an O-ring. In addition, the seal 15 has in a circumferential area an anti-rotation nose 20 which is positively received in the potting body 3. This results in a reliable sealing of the dry space 19 relative to the wet space 18 by the power electronics module 1.

In order to optimize the inner tightness of the power electronics module 1, a sealing jacket 9 is implemented in a recess 6 of the Vergusskör pers 3 in accordance with the invention. As can be seen in detail in this regard in FIG. 2, the busbars 2a, 2b, 2c are surrounded by this sealing jacket 9 in a restricted longitudinal section 8 between each of the first and second connection areas 4, 5. The sealing jacket 9 is realized as a (second) plastic material that is produced / cast separately from the (first) plastic material of the potting body 3. During production, a recess 6 in the form of a through hole 11 is initially kept free in a first step during casting of the potting body 3, through which recess 6 the busbars 2a, 2b, 2c extend with their longitudinal section 8.

According to the invention, the sealing jacket 9 is fastened to the longitudinal section 8 via an adhesion promoter layer 7 on the outer surface of the respective busbar 2a, 2b, 2c. In a second step of the manufacturing method according to the invention, an adhesion promoter layer 7 is thus applied to the respective longitudinal section 8 of the busbars 2a, 2b, 2c. Previously, the surface of the longitudinal section 8 was preferably surface-activated. Afterwards, in a third step, the second plastic material, which forms the sealing jacket 9 in the cured state, is filled into the recess 6 until the longitudinal sections 8 are completely surrounded by the sealing jacket 9. As shown in FIGS. 5 and 6, a cover 13 is used on an underside of the potting body 3 to close the recess 6. The cover 13 is positioned on an end region 12 of the recess 6 spaced from the busbars 2a, 2b, 2c. Thus, the up device casing 9 is implemented as an inner seal of the power electronics module 1.

As furthermore in FIGS. 7 and 8, the individual busbars 2a, 2b, 2c extend between their connection areas 4, 5 continuously and completely isolated from one another within the potting body 3. While each first connection area 4 is shaped as a plug receptacle, every second connection area 5 is provided with two pins. The first busbar 2a runs essentially parallel to the second busbar 2b; the third busbar 2c runs essentially parallel to the first busbar 2a and the third busbar 2c.

In other words, in the present application, a high-voltage terminal (power electronics module 1) is used to contact two interfaces. One interface is to the power electronics, the other to the electric machine 10. The area of the power electronics is also called the dry room and the area of the electric machine 10 is called the wet room, since this is actively cooled with a corresponding oil. Both rooms are sealed from the outside via a separate seal 15.

The present system is a high-voltage terminal 1, which consists of copper bars 2a, 2b, 2c, which are overmolded with a corresponding plastic.

The inventive solution consists in using an additional potting compound (Dichtungsum casing 9) in order to generate an additional barrier for the oil creeping along. First, the busbars 2a, 2b, 2c are treated with a so-called primer (adhesion promoter layer 7) in order to increase the adhesion of the potting compound 9 to the copper-plastic connection. In a further process step, the potting agent is filled in and cured under temperature. The now created 3-part The compound made of potting plastic-copper is much more oil-tight than the original system.

In FIG. 3 it can be clearly seen that an additional potting chamber 6 has now been introduced behind the seal 15 in the drying space 19. This potting chamber 6 is used as described above to generate a barrier for the oil creeping along.

In the front view / top view according to FIG. 1, the FIV terminal 1 is shown from above. The three busbars 2a, 2b, 2c can be seen. In the rear view / bottom view according to FIG. 5 it can be seen that the base is provided with a cover 13. This is required so that the potting material does not run off during the potting process. Plastic and copper expand differently when exposed to temperature.

The potting itself also has a different coefficient of expansion. By using the primer 7, an adhesive, the potting compound 9 can form an adhesive bond with the copper 2a, 2b, 2c and the plastic 3. In this way, sufficient tightness is generated within the assembly.

The busbars 2a, 2b, 2c are pre-bent accordingly and inserted into an injection molding tool and encapsulated with a suitable material. In this case, as in FIG. 2, an area (potting area) is correspondingly omitted in order to produce an empty chamber 6. This empty chamber 6 is closed on one side with the separate cover 13. This leaves an opening that can be used for the filling process.

4 shows the installation state in the overall system. The sealing interface to the housing 16 is clearly visible. FIGS. 6 to 8 illustrate further representations, such as a transparent view to make the course of the busbars 2a, 2b, 2c more visible, as well as an exploded view. Reference list

1 power electronics module

2a first busbar 2b second busbar

2c third busbar

3 potting bodies

4 first connection area

5 second connection area 6 recess

7 adhesion promoter layer

8 longitudinal section

9 Sealing jacket

10 electric prime mover 11 through hole

12 end area

13 lid

14 outside

15 seal 16 housing

17 stator

18 wet room

19 drying room

20 anti-rotation nose 21 winding

22 gap

Claims

1. Power electronics module (1) for an electric drive machine (10) of a motor vehicle, with several busbars (2a, 2b, 2c) and a potting body (3) which supports the busbars (2a, 2b, 2c) at a distance and electrically insulated from one another, each Busbar (2a, 2b, 2c) is exposed on a first connection area (4) and a second connection area (5) opposite the first connection area (4) for further contact to the surroundings of the potting body (3), characterized in that the Busbars (2a, 2b, 2c) each on a longitudinal section (8) arranged in a common recess (6) of the potting body (3) cast from a plastic material between their two connection areas (4, 5) with a separate connection to the potting body ( 3) applied sealing jacket (9) are provided, which sealing jacket (9) adheres to the busbar (2a, 2b, 2c) via an adhesion promoter layer (7).

2. Power electronics module (1) according to claim 1, characterized in that the busbars (2a, 2b, 2c) are surface-activated in the longitudinal section (8) surrounded by the adhesion promoter layer (7).

3. Power electronics module (1) according to claim 1 or 2, characterized in that three busbars (2a, 2b, 2c) are provided, each of which is arranged with ih rem longitudinal section (8) within the recess (6).

4. Power electronics module (1) according to one of claims 1 to 3, characterized in that the recess (6) is designed as a potting body (3) through penetrating through hole (11).

5. Power electronics module (1) according to claim 4, characterized in that the through hole (11) is closed at its end region (12) spaced apart from the busbars (2a, 2b, 2c) by a cover (13).

6. Power electronics module (1) according to one of claims 1 to 5, characterized in that on an outer side (14) of the potting body (3), on egg ner the second connection areas (5) facing side of the recess (6), a seal (15) extending around the potting body (3) is received.

7. Electric drive machine (10) for a motor vehicle, with a housing (16), wherein the housing (16) has a stator (17) receiving wet space (18) and a relative to the wet space (18) sealed dry space (19 ), and with a power electronics module (1) according to one of claims 1 to 6, wherein the first connection areas (4) of the busbars (2a, 2b, 2c) are arranged in the drying room (19) and the second connection areas (5 ) the busbars (2a, 2b, 2c), which are further connected to windings (21) of the stator (17), are arranged in the wet area (18).

8. A method for producing a power electronics module (1) for an electrical-specific drive machine (10) of a motor vehicle, wherein in a first step a plurality of busbars (2a, 2b, 2c) are encased by a first plastic material in such a way that the busbars (2a, 2b, 2c) after curing of the first plastic material forming a potting body (3) are kept spaced apart and electrically insulated from one another and are each arranged with a longitudinal section (8) within a recess (6) of the potting body (3) exposed to the environment, In a second step, an adhesion promoter layer (7) is applied to the longitudinal section (8) of each busbar (2a, 2b, 2c) and, in a third step, a second plastic material is poured into the recess (6) so that the second Kunststoffma material after its hardening as a sealing jacket (9) over the adhesion mediating layer (7) on the longitudinal section (8) of each busbar (2a, 2b, 2c ) is liable.