CN111509920A

CN111509920A - Contact device, electric motor and method for contacting busbars with one another in an electric motor

Info

Publication number: CN111509920A
Application number: CN202010074140.9A
Authority: CN
Inventors: N.威廉; J.亨策; B.科伊佩尔; D.洛伊德斯; S.戈杰斯
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2019-01-22
Filing date: 2020-01-22
Publication date: 2020-08-07
Anticipated expiration: 2040-01-22
Also published as: DE102019200751A1; CN111509920B

Abstract

The invention relates to a contact device (10) for contacting a first busbar (30) and a second busbar (31) in an electric motor (50) of a motor vehicle, wherein the contact device (10) has a screw (20) and is designed for partially guiding a first opening (32) of the first busbar (30) and a second opening (33) of the second busbar (31). The screw is a double-threaded screw (20) with a first thread (21) and a second thread (22). A bearing sleeve (11) of the contact device (10) is provided for making contact with the first busbar (30) and is arranged on the double-threaded screw (20). The clamping block (12) of the contact device (10) is arranged with a third thread (13) below the bearing sleeve (11) in the direction of the first busbar (30), wherein the third thread (13) is in engagement with the first thread (21) or the second thread (22).

Description

Contact device, electric motor and method for contacting busbars with one another in an electric motor

Technical Field

The invention relates to a contact device for contacting a first busbar and a second busbar in an electric motor (or electric motor), which is also referred to as an Elektromotor, of a motor vehicle, wherein the contact device has a screw and is designed to be partially guided through a first opening of the first busbar and a second opening of the second busbar. The invention further relates to an electric motor of a motor vehicle having a first busbar, at least one second busbar and a contact device for contacting the first busbar and the second busbar. The invention further relates to a method for contacting a first bus bar with at least one second bus bar in an electric motor of a motor vehicle.

Background

An example of an application area in which bus bars, that is to say electrically conductive conductor bars, are connected to one another is an electric motor. In an electric motor, the busbars of the stator are correspondingly connected to busbars of a current source (or called power supply, stromqelle). In the case of a three-phase alternating current motor of a motor vehicle, for example, the phases U, V and W are formed by means of bus bars.

In the case of an internally known contact device for contacting a first bus bar and a second bus bar in an electric motor, a screw is guided from above through openings of the first and second bus bars which overlap one another. The screw is screwed into the thread of the clamping block arranged below the openings overlapping each other. A bearing sleeve is arranged on the clamping block, which is provided for making contact with the first busbar. Due to the tolerances that occur, assembly gaps can form between the bearing sleeve and the first busbar. If the mounting gap is not closed, permanent electrically conductive contact between the first busbar and the second busbar cannot be ensured. However, when the assembly gap is closed by the screw being further tightened, mechanical stress is introduced into the bus bar. This makes the bus bar more susceptible to mechanical loads than it has been due to its high rigidity. When mechanical stresses in the busbar are additionally built up by closing the assembly gap, material fatigue is possible until the busbar breaks. Such mechanical loads occur in the case of electric motors due to the vibrations that occur. A break in one of the bus bars may lead to a malfunction of the electric motor.

One solution to this problem is the measurement of the assembly gap and the insertion of a suitable spacing compensation element into the assembly gap. However, this solution is time consuming and cost intensive.

Furthermore, the problem at the contact point of the bus bars is that in electrical devices such as electric motors, there is often only a very small available installation space. The assembly and contacting of the bus bars must be carried out in a minimum space, which additionally makes the contacting of the bus bars difficult.

DE 102012024160 a1 relates to a coupling device for electrically coupling an electric motor arranged in a housing to a coupling housing. The electrical conductors in this housing are screwed to one another by means of ports configured as screws, wherein the screws engage into threads arranged at the bottom of the coupling housing. The mechanical stresses built into the bus bar by tightening the screws can lead to fractures and thus to failure of the electric machine in the event of a vibration load on the electric machine.

DE 102011081896 a1 relates to an electric motor with a stator in the form of a circular ring, a motor housing and a coupling device by means of which the coupling conductors of the stator can be introduced into a connecting space (verschaltungsum) of the coupling device. In this connection space, the connection conductor can be connected to the energy source conductor. For connecting the energy source conductor to the coupling conductor, a contact element is proposed, which is designed as a threaded sleeve according to DE 102011080250 a 1. Even in the case of the tightening device shown here, undesirable mechanical stresses occur in the busbar.

DE 102016222611 a1 relates to a device for connecting the wires of a stator of an electric machine. The device has a positioning means for positioning the electrical conductors of the stator wiring. The positioning element has an insertion opening through which the electrical conductor can be inserted into the positioning element when the device is placed on the stator.

A further known solution for the contacting of the bus bars is an electrically conductive, elastic connection, which is arranged between the bus bars. These connectors have the disadvantage that they require more installation space due to their flexibility and may require additional insulating material, which makes the mounting of the elastic connector costly and expensive.

An elastic connection for rigid strip conductors made of corrugated laminated copper strips is known from DE 1842353U. The copper strip is corrugated in one portion and straight in one portion. The corrugations of adjacent copper strips are moved relative to each other in the longitudinal direction of the copper strips.

DE 102014201191 a1 discloses a power coupling unit for an electric motor of a vehicle having an electrically conductive bus bar element which is arranged between a switching ring of a stator and two rigidly connected ends of an energy unit. The bus bar element has a flexible intermediate element between two rigid connection ends and a plastic jacket at the connection ends.

Disclosure of Invention

It is therefore an object of the present invention to reduce the above-mentioned disadvantages in the prior art. In particular, it is an object of the invention to provide a contact arrangement for an electric motor of a motor vehicle, which makes possible a reliable, fast and cost-effective contacting of a bus bar in the electric motor. The invention also has the object of providing an electric motor of a motor vehicle having at least one such contact device and proposing a simple, rapid and cost-effective method for contacting a first busbar and a second busbar.

The above object is achieved by the objects of the patent claims. In particular, one object is achieved by a contact arrangement according to claim 1. These objects are furthermore achieved by an electric motor according to claim 9 and a method for contacting a first bus bar with at least one second bus bar according to claim 10. Further advantages and details of the invention emerge from the dependent claims, the description and the drawings. The features and details described in connection with the electric motor according to the invention and with the method according to the invention are obviously also applicable in connection with the contact device according to the invention and correspondingly vice versa, so that the disclosure with respect to the various inventive aspects is always made or can be referred to one another.

According to a first aspect of the invention, the object is achieved by a contact device for contacting a first busbar with a second busbar in an electric motor of a motor vehicle, wherein the contact device has a screw and is designed for being partially guided through a first opening of the first busbar and a second opening of the second busbar, wherein (a) the screw is a double-threaded screw with a first thread and a second thread, (b) a bearing bush of the contact device is arranged at the double-threaded screw, which is provided for contacting the first busbar, and (c) a clamping piece of the contact device is arranged with a third thread below the bearing bush in the direction of the first busbar, wherein the third thread is in engagement with the first thread or the second thread.

With the contact arrangement according to the invention, it is possible to bring the first busbar into contact with the bearing sleeve in such a way that no assembly gap is formed. This is achieved via the first and second threads of the double-threaded screw, wherein one of the threads is provided for fixing the double-threaded screw at the clamping block and one of the threads is provided for fastening the second bus bar at the first bus bar. Commercially available parts can be used as components of the contact device, so that the contact device can be manufactured at low cost. The contacting of the bus bars by means of the contact device can be done in several steps and is very reliable.

In particular, at least two bus bars can be brought into contact with one another with the contact device according to the invention. It is then possible to bring more than two, in particular three, four, five or more, bus bars into contact with one another. It is likewise possible for at least two, in particular exactly three, double-threaded screws to provide the clamping block with at least two, in particular exactly three, third threads and to bring every second or multiple bus bars into contact with one another by means of in each case one of the double-threaded screws. Contact here means a contact that can be electrically conductive, so that an electric current can flow between the bus bars that are contacted.

These openings can be configured, for example, as bores through the bus bars. These openings can be surrounded, in particular, over the entire surface by the material of the bus bar. The openings may have a substantially circular cross-section. The fact that these openings of the bus bars overlap one another means that these openings at least partially cover one another, so that the contact device, in particular with its screws, can be guided through the openings that overlap one another. The openings preferably overlap one another mostly and completely, particularly preferably approximately completely, when measured at the opening cross section, so that the cross section of at least one opening completely overlaps the cross section of another opening.

A double-threaded screw in the sense of the present invention is a screw with a first thread and a second thread. In particular, the first thread and the second thread are separate from each other. In other words, the first thread and the second thread do not transform into each other. The double-threaded screw may in particular be a double-threaded screw without a screw head. The double-threaded screw is dimensioned in particular such that its cross-sectional area and/or its diameter is smaller than the cross-sectional area and/or diameter of the opening. In particular, no contact of the double-threaded screw with the bus bar is established. However, the electrically conductive contact between the double-threaded screw and the bus bar can be established via other parts of the contact device, for example a bearing sleeve, in which the bearing sleeve is of metallic design and contacts the double-threaded screw directly or indirectly via further metallic components.

The clamping block can be fixed at one or more components, for example at a housing part in the interior space of the electric motor or at one or more bus bars. Preferably, the clamping block is made of an electrically insulating material. Preferably, the bearing sleeve has a through hole without threads.

In a preferred embodiment of the invention, the first thread is opposite to the second thread configuration. That is, the first or second threads are left-hand threads and the respective other of the first and second threads is right-hand threads. Due to the different rotational directions of the first thread and the second thread, these threads can be brought into engagement with the corresponding other threads without force-technically influencing one another. In particular, in the case of an engagement at the first or second thread of a double-thread screw, it is thereby prevented particularly reliably that a force is exerted on the respective other thread of the double-thread screw which is in engagement with the third thread of the clamping block, since this can loosen the bearing bush from the first busbar and can form a mounting gap.

In a further preferred embodiment of the invention, a disk (or washer, Scheibe) is arranged between the bearing bush and the clamping block at the double-threaded screw, which disk is designed to fix the bearing bush. The disk can be designed as a separate component or integrally, in particular monolithically, with the double-threaded screw. The disk can also be formed integrally and monolithically with the bearing sleeve. The disk and the bearing sleeve can however also be composed of different materials. The disk may separate the first and second threads from one another. Via this disk, a bearing sleeve can be arranged at the double-threaded screw. The disk makes it possible to fix the bearing bush relative to the first busbar in the direction of the first busbar. This means that the bearing bush does not have to be arranged directly on the double-threaded screw itself, in particular does not have to have its own thread with which the first or second thread of the double-threaded screw is brought into engagement. Alternatively, however, it is possible for the bearing sleeve to have its own thread and to be brought into engagement with the first thread or the second thread of the double-thread screw or to be formed integrally with the double-thread screw.

According to a further preferred embodiment of the invention, the first thread and/or the second thread is/are configured as an external thread and/or the third thread is configured as an internal thread. This makes it possible to secure a double-threaded screw particularly easily in the clamping piece. Furthermore, it is possible to use a low-cost double-threaded screw with two external threads in the contact device.

In a further preferred embodiment of the invention, the contact device has a tool receptacle which can be brought into engagement with the first tool in such a way that the bearing sleeve is brought into contact with the first busbar by actuating the first tool. In particular, the double-threaded screw of the contact device has a tool receptacle. In particular, the tool receiving portion is arranged at one of the two ends of the double-threaded screw. It is thereby achieved that the contact device is guided partially through the first opening of the first bus bar and the second opening of the second bus bar by simple means (otherwise known as a device, i.e. misttel). The tool holder can be configured in particular as a driven profile, for example a groove, a cross-groove, an inner hexagon or an outer hexagon. The first tool with which the driving contour can be brought into engagement can accordingly be a screwdriver corresponding to the driving contour.

According to a further embodiment of the invention, the double-thread screw has a threaded shaft with a fourth thread configured as an external thread, which is or can be brought into engagement with the first thread or the second thread, wherein the first thread or the second thread brought into engagement with the fourth thread is configured as an internal thread. The threaded rod is thus part of a double-threaded screw. It is thereby also possible to achieve that the contact device is partially guided through the first opening of the first busbar and the second opening of the second busbar with simple means. In particular, the tool receiver of the double-threaded screw is arranged at the threaded rod, in particular at one end of the threaded rod.

In a preferred embodiment of the invention, the screw thread of the nut and the double-threaded screw of the contact device is or can be brought into engagement and is provided for making contact with the second busbar. The nut makes possible a simple contact of the primary bus bar with the secondary bus bar, wherein the primary bus bar is already in contact with the bearing sleeve, so that no assembly gap can be formed.

In a further preferred embodiment of the invention, the first thread is configured as an internal thread and the second thread is configured as an external thread, wherein the first thread and the second thread are arranged coaxially with respect to one another. In other words, a double-threaded screw has a first thread at the inner circumference and a second thread at the outer circumference. A particularly short double-threaded screw can thereby be provided. This is advantageous when the installation space available is very small.

According to a second aspect of the invention, the object is achieved by an electric motor for a motor vehicle having a first busbar, at least one second busbar and a contact device according to the invention, wherein the first busbar is in contact with the second busbar by means of the contact device. Preferably, one of the bus bars is connected to the stator of the electric motor and one of the bus bars is connected to a current source of the electric motor. In particular, the electric motor is a three-phase alternating current motor with three contact devices according to the invention, which correspondingly connect two bus bars (one of which is connected to the stator of the three-phase alternating current motor and one of which is connected to the current source of the three-phase alternating current motor) to one another in order to establish the phases U, V and W of the three-phase alternating current motor. The contact arrangement according to the invention is particularly advantageous in the case of an electric motor in a motor vehicle, since the vibration loads occurring in the electric motor of the motor vehicle are particularly high and the bus bar can become particularly brittle and therefore brittle in the case of low outside temperatures.

According to a third aspect of the invention, the object is achieved by a method for contacting a first busbar and at least one second busbar in an electric motor of a motor vehicle, with the following steps: (a) arranging a first busbar and a second busbar one above the other, wherein the first opening of the first busbar overlaps the second opening of the second busbar, (b) arranging a contact device with a screw below the opening one above the other, wherein the screw is a double-threaded screw with a first thread and a second thread, a bearing sleeve of the contact device is arranged at the double-threaded screw, which is provided for contacting the first busbar, and a clamping block of the contact device is arranged below the bearing sleeve with a third thread in the direction of the first busbar, wherein the third thread is in engagement with the first thread or the second thread, and the contact device has a tool receptacle which can be brought into engagement with a first tool in such a way that the bearing sleeve is brought into contact with the first busbar by actuating the first tool, (c) guiding the first tool through the overlapping openings one above the other and bringing the first tool into engagement with the tool receptacle, (d) operating the first tool such that the bearing sleeve comes into contact with the first bus bar, (e) bringing one of the threads of the nut and of the double-threaded screw of the contact device into engagement, and (f) screwing the nut with the second tool at least until the first bus bar and the second bus bar come into contact with each other.

Drawings

The invention is further explained below with the aid of the attached figures. All features which are evident from the claims, the description or the drawings, including structural details and spatial arrangements, can be essential for the invention both in themselves and in any different combination. Elements having the same function and/or operating principle are provided with the same reference symbols in the figures, respectively. Wherein:

figure 1 shows a diagrammatic representation of the installation of the contact arrangement in a partial view of the inner space of an electric motor,

figure 2 shows a diagrammatic representation of an enclosed contact arrangement not according to the invention in a partial view of the inner space of an electric motor,

figure 3 shows a detailed illustration of one of the enclosed contact arrangements not according to the invention from figure 2,

fig. 4 a-4 h show schematic cross-sectional illustrations of steps of a method according to the invention for contacting a first busbar with a second busbar, using a first embodiment of a contact device according to the invention, and

fig. 5a to 5h show schematic cross-sectional illustrations of steps of a method according to the invention for contacting a first busbar with a second busbar, using a second embodiment of a contact device according to the invention.

List of reference numerals

10 contact device

11 supporting sleeve

12 clamping block

13 third screw thread

14 disc

15 nut

20 screw and double thread screw

21 first thread

22 second thread

23 tool receiving part

24 threaded rod

25 fourth screw thread

30 first bus bar

31 second bus bar

32 first opening

33 second opening

40 first tool

41 second tool

50 electric motor

x assembly gap.

Detailed description of the preferred embodiments

Fig. 1 shows a schematic representation of the installation of a contact arrangement in a partial view of the interior of an electric motor 50 of a motor vehicle. The first bus bar 30 connected with the stator of the electric motor 50 has an opening 32. Above the opening 32, an opening 33 of the second busbar 31 is arranged in an overlapping manner, which is connected to a current source, not shown, of the electric motor 50. By mounting a contact device, not shown, in the inner space of the electric motor 50, the first bus bar 30 and the second bus bar 31 can be contacted with each other so as to establish an electrically conductive contact.

Fig. 2 shows a representation of the contacting of the phases U, V and W in the interior of a three-phase alternating current motor 50 by means of a contacting device not according to the invention. Each two

busbars

30,31 are connected to one another by a contact device.

Fig. 3 is a detailed illustration of the enclosed contact arrangement from fig. 2, which is not according to the invention. The screw 20 with its head is guided from above through the

openings

32,33 of the first busbar 30 and the second busbar 31, which openings are covered in the illustration and overlap one another, and is screwed into the non-visible third thread of the clamping block 12 arranged below the

openings

32,33 that overlap one another. In the case of fixing the bus bars 30,31 between the screw heads of the screws 20 and the bearing sleeve 11 arranged above the clamping block 12, a fitting gap is formed between the first bus bar and the bearing sleeve 11. The assembly gap x can be closed by further turning of the screw 20 into the non-visible internal thread of the clamping block 12. However, in the case of this form of closure of the assembly gap x, it is disadvantageous that mechanical stresses are introduced into the bus bars 30,31, as a result of which the bus bars 30,31 may break under additional mechanical stress.

Fig. 4a to 4h are schematic cross-sectional illustrations of steps of a method according to the invention for contacting a first busbar 30 and a second busbar 31, using a first embodiment of a contact device 10 according to the invention.

Fig. 4a shows that the second busbar 31 is arranged above the first busbar 30 in such a way that the opening 33 of the second busbar 31 overlaps the opening 32 of the first busbar 30. The contact device 10 is arranged below the

openings

32,33 which overlap each other. The contact device 10 has a double-threaded screw 20 with a first thread 21 and a second thread 22. The first thread 21 and the second thread 22 are configured oppositely to each other. The first thread 21 and the second thread 22 are separated from each other, wherein the disc 14 is arranged at the double-thread screw 20 between the first thread 21 and the second thread 22. A support sleeve 11 is arranged on the disk 14. The second thread 22 of the double-thread screw 20 is in engagement with the third thread 13 of the clamping block 12, wherein the second thread 22 is completely accommodated in the third thread 13 and the double-thread screw 20 projects downward from the clamping block 12 in a section in which the second thread 22 is arranged. The clamping block 12 can be fixed at one or more components in the interior of the electric motor 50, for example at one or more housing parts or at one or more bus bars.

Between the bearing sleeve 11 and the primary bus bar there is a fitting gap x, which is closed suitable for establishing a reliable contact of the primary bus bar 30 with the secondary bus bar 31. For this purpose, the double-thread screw 20 has to be guided through the

openings

32,33 that overlap one another with a section having the first thread 21. In this case, the second thread 22 of the double-thread screw 20 has to be rotated out of the third thread 13 of the clamping piece 12, so that the bearing bush 11 is moved in the direction of the first busbar 30.

Fig. 4b shows that the first tool 40 is guided through the

openings

32,33 overlapping one another and brought into engagement with the tool receiver 23 of the double-threaded screw 20. A tool receiving portion 23 is arranged at the end of the double-threaded screw 20, to which the first thread 21 leads. In this case, a tool receiver 23 is arranged on the top side of the double-threaded screw 20. The arrow shown indicates how the second thread 22 is turned out of the third thread 13 when the first tool 40 is actuated, so that the bearing sleeve 11 is moved in the direction of the first busbar.

Fig. 4c shows the final position after actuation of the first tool 40, in which the bearing sleeve 11 touches the first busbar 30.

Fig. 4d shows bringing the nut 15 of the contact device 10 into engagement with the first thread 21 of the double-threaded screw 20. For this purpose, the nut 15 is turned from above onto the first thread 21.

Fig. 4e shows the arrangement of the second tool 41 for tightening the nut 15 on the first thread 21. In this case, the first tool 40 retains its final angular position reached in fig. 4c, so that the double-threaded screw 20 is prevented from being rotated when the nut 15 is tightened.

Fig. 4f shows the final position after tightening the nut 15, in which the nut 15 brings the second bus bar 31 into contact with the first bus bar 30. the second tool 41 may for example be a screw wrench (Schraubenschl ü ssel) for the nut 15. the second tool 41 may for example also be brought into engagement with the first tool 40 in such a way that the second tool 41 is operated by means of the first tool 40. in fig. 4g, the arrows shown indicate how the first tool 40 together with the second tool 41 is loosened from the nut 15 and the double-threaded screw 20 of the contact device 10.

Fig. 4h shows the final position after removal of the first tool 40 and the second tool 41 from the contact device 10. The primary bus bar 30 is in contact with the secondary bus bar 31. This contact is secured against mechanical loads from above by the nut 15 and from below by the bearing bush 11 and the disk 14.

Fig. 5a to 5h are schematic cross-sectional illustrations of steps of a method according to the invention for contacting a first busbar 30 and a second busbar 31, using a second embodiment of a contact device 10 according to the invention.

Fig. 5a shows that the second busbar 31 is arranged above the first busbar 30 in such a way that the opening 33 of the second busbar 31 overlaps the opening 32 of the first busbar 30. Below the

openings

32,33, which overlap each other, a contact device 10 is arranged. The contact device 10 has a double-threaded screw 20 with a first thread 21 and a second thread 22. The first thread 21 and the second thread 22 are configured in opposite directions to each other. The first thread 21 and the second thread 22 are arranged coaxially to each other, wherein the second thread 22 is arranged at the outer side of the double-threaded screw 20 and the first thread 21 is arranged at the inner side of the double-threaded screw. The disc 14 is disposed at one end of the double-threaded screw 20. A support sleeve 11 is arranged on the disk 14. The second thread 22 of the double-thread screw 20 is in engagement with the third thread 13 of the clamping block 12, wherein the second thread 22 is completely accommodated in the third thread 13 and the double-thread screw 20 protrudes downward from the clamping block 12. The clamping block 12 can be fixed at one or more components in the interior of the electric motor 50, for example at one or more housing parts or at one or more bus bars. Between the bearing sleeve 11 and the primary busbar 30 there is a fitting gap x, closed which is suitable for establishing the contact of the primary busbar 30 with the secondary busbar 31.

Fig. 5b shows how the threaded rod 24 of the double-threaded screw 20 with the fourth thread 25 configured as an external thread and the tool receiver 23 at the top side of the threaded rod 24 is fed in the direction of the second thread 22 of the double-threaded screw 20 and is guided through the overlapping

openings

32,33 of the bus bars 30, 31.

Fig. 5c shows how the first tool 40 is brought into engagement with the tool receiver 23 of the threaded rod 24 and is actuated by rotation. The threaded rod 24 is thereby brought with its fourth thread 25 into full engagement with the second thread 22, so that the threaded rod 24 is accommodated in the double-threaded screw 20.

Fig. 5d shows how the first tool 40 is further manipulated in order to move the bearing sleeve 11 in the direction of the shown arrow to the first busbar 30, in which the first thread 21 of the double-thread screw 20 is turned out of the third thread 13 of the clamping block 12.

Fig. 5e shows the final position after the actuation of the first tool 40, in which the bearing sleeve 11 contacts the first busbar 30. Fig. 5e furthermore shows the bringing into engagement of the nut 15 of the contact device 10 with the fourth thread 25 of the threaded shank 24 of the double-threaded screw 20. To this end, the nut 15 is mounted from above on the fourth thread 25.

Fig. 5f shows the arrangement of the second tool 41 for tightening the nut 15 on the fourth thread 25.

Fig. 5g shows the final position after tightening the nut 15, in which the nut 15 brings the secondary bus bar 31 into contact with the primary bus bar 30. The arrows indicate that the first tool 40 together with the second tool 41 is loosened from the nut 15 and the double-threaded screw 20 of the contact device 10.

Fig. 5h shows the final position after the first tool 40 and the second tool 41 have been removed from the contact device 10. The primary bus bar 30 is in contact with the secondary bus bar 31. The contact established is secured against mechanical loads from above by the nut 15 and from below by the bearing bush 11 and the disk 14.

Claims

1. Contact device (10) for contacting a first busbar (30) and a second busbar (31) in an electric motor (50) of a motor vehicle, wherein the contact device (10) has a screw (20) and is designed to be partially guided through a first opening (32) of the first busbar (30) and a second opening (33) of the second busbar (31),

it is characterized in that the preparation method is characterized in that,

(a) the screw is a double-thread screw (20) with a first thread (21) and a second thread (22),

(b) a bearing sleeve (11) of the contact device (10) is arranged at the double-threaded screw (20), the bearing sleeve (11) being provided for making contact with the first busbar (30), and

(c) the clamping block (12) of the contact device (10) is arranged with a third thread (13) below the bearing sleeve (11) in the direction of the first busbar (30), wherein the third thread (13) is in engagement with the first thread (21) or the second thread (22).

2. The contact arrangement (10) according to claim 1, characterized in that the first thread (21) is configured opposite to the second thread (22).

3. The contact arrangement (10) according to claim 1 or 2, characterized in that a disc (14) is arranged between the bearing bush (11) and the clamping block (12) at the double-threaded screw (20), the disc (14) being configured for fixing the bearing bush (11).

4. The contact arrangement (10) according to any one of the preceding claims, characterized in that the first thread (21) and/or the second thread (22) is configured as an external thread and/or the third thread (13) is configured as an internal thread.

5. The contact arrangement (10) according to one of the preceding claims, characterized in that the contact arrangement (10) has a tool receptacle (23) which can be brought into engagement with a first tool (40) in such a way that the bearing sleeve (11) is brought into contact with the first busbar (30) by actuating the first tool (41).

6. The contact arrangement (10) according to any one of the preceding claims, characterised in that the double-thread screw (20) has a threaded shank (24) with a fourth thread (25) configured as an external thread, which is brought or can be brought into engagement with the first thread (21) or the second thread (22), wherein the first thread (21) or the second thread (22) brought or can be brought into engagement with the fourth thread (25) is configured as an internal thread.

7. The contact arrangement (10) according to any one of the preceding claims, characterised in that a nut (15) of the contact arrangement (10) is brought or can be brought into engagement with the threads (21,22,25) of the double-threaded screw (20) and is provided for achieving contact with the second busbar (31).

8. The contact arrangement (10) according to any one of the preceding claims, characterized in that the first thread (21) is configured as an internal thread and the second thread (22) is configured as an external thread, wherein the first thread (21) and the second thread (22) are arranged coaxially to each other.

9. Electric motor (50) for a motor vehicle, having a first busbar (30), at least one second busbar (31) and at least one contact device (10) according to one of the preceding claims, wherein the first busbar (30) is in contact with the second busbar (31) by means of the contact device (10).

10. Method for contacting a first busbar (30) with at least one second busbar (31) in an electric motor of a motor vehicle, with the following steps:

(a) arranging the first and second bus bars (30, 31) one above the other, wherein a first opening (32) of the first bus bar (30) overlaps a second opening (33) of the second bus bar (31),

(b) arranging a contact device (10) with a screw (20) below openings (32,33) lying one above the other, wherein,

-the screw is a double-thread screw (20) with a first thread (21) and a second thread (22),

-a bearing sleeve (11) of the contact device (10) is arranged at the double-threaded screw (20), the bearing sleeve (11) being provided for coming into contact with the first busbar (30),

-the clamping block (12) of the contact device (10) is arranged with a third thread (13) under the bearing bush (11) in a direction towards the first busbar (30), wherein the third thread (13) is in engagement with the first thread (21) or the second thread (22), and

-the contact device (10), in particular the double-threaded screw (20), has a tool receptacle (23) which can be brought into engagement with a first tool (40) in such a way that the bearing sleeve (11) is brought into contact with the first busbar (30) by actuating the first tool (41),

(c) guiding the first tool (40) through openings (32,33) overlapping each other and bringing the first tool (40) into engagement with the tool receptacle (23),

(d) -operating the first tool (40) such that the bearing sleeve (11) comes into contact with the first busbar (30),

(e) bringing a nut (15) of the contact device (10) into engagement with one of the threads (21,22,25) of the double-threaded screw (20), and

(f) -screwing the nut (15) with a second tool (41) at least to the first busbar (30) and the second busbar (31) into contact with each other.