DE102019207241A1 - Device for the electrically conductive connection between a shaft and a housing - Google Patents

Abstract

Device (X) for the electrically conductive connection between a shaft (W) and a housing (GG) in which the shaft (W) is rotatably mounted, comprising an electrically conductive holding element (X1, X1b) and one on the holding element (X1, X1b) ) attached, electrically conductive contact element (X2), wherein the contact element (X2) is set up to establish an electrically conductive connection between the shaft (W) and the holding element (X1, X1b), wherein the holding element (X1, X1b) is set up to establish an electrically conductive connection between the contact element (X2) and the housing (GG), the retaining element (X1, X1b) being attached to the housing (GG) by means of a snap ring (SP), as well as a drive train unit (G) for a motor vehicle with a such device (X).

Description

The invention relates to a device for the electrically conductive connection between a shaft and a housing. The invention also relates to a drive train unit for a motor vehicle with such a device.

The patent application DE 102 49 770 A1 describes a device which comprises a shaft rotatably mounted in a housing. The housing and the shaft are in an electrically conductive connection via a component, namely via a sliding connection. The component can comprise a discharge ring which does not rotate with the shaft and which has a sliding contact with the shaft in the region of its smallest diameter. However, it is not clear from this document how this component is attached.

The patent application DE 10 2016 010 926 A1 describes various configurations of a shaft grounding ring between a shaft and a housing. For fastening, it is proposed to fasten the shaft earthing ring to the housing with a press fit. Alternatively, it is suggested to use transversely protruding brackets for fastening, or to screw the shaft earthing ring.

The fastening of the shaft earthing ring by means of a press fit is viewed as disadvantageous, since this makes it difficult to dismantle it. There is also the risk of damaging the housing during assembly and disassembly.

It is therefore the object of the invention to provide an improved fastening for such a device.

The object is achieved by the features of patent claim 1. Advantageous embodiments result from the dependent patent claims, the description and the figures.

To achieve the object, a device for an electrically conductive connection between a shaft and a housing is proposed. The shaft is rotatably mounted in the housing, for example by means of one or more roller and / or slide bearings. As a result of the storage, there is usually no reliable electrically conductive connection between the shaft and the housing, since a lubricant in the bearings often has electrically insulating properties.

The device comprises an electrically conductive holding element and an electrically conductive contact element attached thereto. The contact element is set up to produce an electrically conductive connection between the shaft and the holding element. This can be done in various ways, for example by means of brushes or by means of a grinding surface. For the electrically conductive friction pairing required, for example, carbon or an electrically conductive PTFE element on the one hand and steel on the other hand can be used. The holding element is set up to produce an electrically conductive connection between the contact element and the housing. An electrically conductive slip ring can be applied to the shaft, on the circumference of which the contact element slides. Alternatively, an electrically conductive layer can be applied to the shaft by means of cold gas spraying, so that a separate slip ring can be omitted.

According to the invention it is now provided that the holding element is fastened to the housing by means of a snap ring. Such a construction enables non-destructive disassembly and easy assembly.

The snap ring is preferably designed as a conical snap ring. The active surfaces of such a “conical” snap ring are not parallel to one another, but rather form an angle to one another so that the two active surfaces intersect. The complementary active surfaces on the housing enclose the same or at least a similar angle. By using such a snap ring, the holding element is pressed against a corresponding contact surface of the housing, so that an electrically conductive contact between the housing and the holding element can be reliably ensured (provided the materials involved are suitable). In addition, such a construction can be implemented in a particularly space-saving manner.

The contact surface is preferably formed by an annular surface, the center of which is arranged coaxially to the axis of rotation of the shaft. The contact surface preferably extends in the radial direction with respect to the axis of rotation of the shaft.

According to one possible embodiment, the holding element is connected to the housing via an electrically conductive connecting element. Such a configuration is particularly advantageous when a mere surface contact between the housing and the holding element does not ensure high electrical conductivity, for example in the case of a housing made of aluminum. Because of the aluminum oxide layer on the surface of the housing, the contact resistance can be too high to ensure a safe and reliable electrically conductive connection. A housing-side end of the connecting element has a shape by means of which a secure electrically conductive contact between the connecting element and the housing can be produced, in particular to damage and penetrate the aluminum oxide layer. For example, thorns can be provided for this purpose, or a geometry such as on a serrated lock washer.

The connecting element can, for example, have a flexible band. Such a configuration facilitates the assembly of the device, since, due to the flexibility of the band, the holding element does not have to be precisely aligned with the housing. In addition, the space required for such a belt is very small.

A sheet metal strip is preferably provided at the end of the connecting element on the housing side. The connecting element can be attached to the housing in a simple manner by means of a screw via the sheet metal strip. The shape for damaging and penetrating the aluminum oxide layer can be formed on the sheet metal strip.

According to a preferred embodiment, a tab is formed on the holding element to which the connecting element is attached. The electrically conductive connection between tab and connecting element can be established, for example, by riveting, soldering or crimping.

A clearance for the tab is preferably provided on the holding element. The positioning of the device relative to the housing is facilitated by the release. In the area of the clearance, the holding element also has an axially oriented projection which additionally facilitates positioning. The axially aligned projection can be achieved, for example, by locally bending the holding element.

The axially oriented projection is preferably arranged and oriented in such a way that direct contact between the snap ring and the connecting element is prevented. This can prevent the connecting element from being damaged by twisting the snap ring.

According to a preferred embodiment, at least one protective element is attached to the holding element. The at least one protective element is designed to protect the electrically conductive contact point between the contact element and the shaft against external influences. The at least one protective element can be formed from an elastomer element, for example, or by a fleece. According to one possible embodiment, a total of two protective elements can be provided, the electrically conductive contact point between the contact element and the shaft being between the two protective elements.

The device described above can be part of a drive train unit for a motor vehicle, so that the device provides an electrically conductive connection between a shaft of the drive train unit and a housing of the drive train unit. The drive train unit can be, for example, an electric axle drive, or an automated transmission or an automatic transmission.

The device which provides the electrically conductive connection between the shaft and the housing is preferably arranged directly adjacent to a radial shaft sealing ring. The fastening of the device by means of the snap ring is particularly suitable for such a configuration, since loading of the radial shaft sealing ring can thus be avoided in a simple manner when the device is installed.

The shaft is preferably formed by an input shaft or by an output shaft of the drive train unit. The drive train unit can have an electrical machine which is set up to drive the shaft. The drive train unit can have a gear set and several shifting elements which are used to form several gear ratios between the input shaft and the output shaft.

• 1 und 2 je einen Antriebsstrang für ein Kraftfahrzeug;
• 3 ein erstes Ausführungsbeispiel der erfindungsgemäßen Vorrichtung;
• 4 ein zweites Ausführungsbeispiel der erfindungsgemäßen Vorrichtung; sowie
• 5 bis 7 verschiedene Ansichten eines dritten Ausführungsbeispiels der erfindungsgemäßen Vorrichtung.

Embodiments of the invention are described in detail below. Show it:

• 1 and 2 one drive train each for a motor vehicle;
• 3 a first embodiment of the device according to the invention;
• 4th a second embodiment of the device according to the invention; as
• 5 to 7th different views of a third embodiment of the device according to the invention.

1 shows schematically a drive train for a motor vehicle. The drive train has an internal combustion engine VM on, its output with an input shaft GW1 a transmission G connected is. The gear G forms a drive train unit of the drive train. An output shaft GW2 of the transmission G is with a differential gear AG connected. The differential gear AG is set up to work on the output shaft GW2 applied power to drive wheels DW of the motor vehicle. The gear G has a wheel set RS on which together with in 1 Shifting elements, not shown, are set up for this purpose with different transmission ratios between the input shaft GW1 and the output shaft GW2 to provide. The wheelset RS is of a housing GG enclosed, which is also one with the input shaft GW1 connected electric machine EM houses. The electric machine EM the input shaft is set up for this GW1 to drive.

The gear G can be one or more devices X exhibit. The devices X are provided for an electrically conductive connection between the input shaft GW1 , or the output shaft GW2 one hand and the housing GG on the other hand to provide. In 1 are the devices X shown only schematically; Embodiments of the devices X are in 3 to 7th described in detail.

2 shows schematically a drive train for a motor vehicle which, in contrast to FIG 1 The embodiment shown is a purely electric drive train. The drive train has a drive train unit G on. The powertrain unit G has an electrical machine EM on which is set up a wave W. to drive. The wave W. is with a differential gear AG connected. The differential gear AG is set up to be attached to the shaft W. applied power to drive wheels DW of the motor vehicle.

The powertrain unit G has a housing GG on which the electric machine EM houses. The wave W. is in the case GG rotatably mounted. The powertrain unit G can be a device X exhibit. The device X is provided for an electrically conductive connection between the shaft W. one hand and the housing GG on the other hand to provide. In 2 is the device X shown only schematically; Embodiments of the device X are in 3 to 7th described in detail.

In the 1 and 2 The drive trains shown are only to be regarded as examples. The device X could also be used in differently designed drive trains to provide an electrically conductive connection between a shaft and a housing supporting the shaft. The drive train can be used, for example, to drive passenger cars, commercial vehicles or rail vehicles.

3 shows a sectional view of the device X according to a first possible embodiment. The device X comprises an electrically conductive holding element X1 and an electrically conductive contact element attached thereto X2 . The contact element X2 grinds on its inner diameter on an optional slip ring WS , which is part of the shaft W. is. The contact element X2 is designed as a resilient PTFE element. The contact element X2 but could also be designed differently, for example as a carbon brush. The holding element X1 is designed for example as a steel ring. To hold the contact element securely X2 can be an additional retaining element X1b be provided, with a radially outer region of the contact element X2 between the holding element X1 and the additional holding element X1b is clamped.

Through the sliding contact between the slip ring WS the wave W. and the contact element X2 , and by attaching the contact element X2 on the holding element X1 instruct the wave W. , the contact element X2 and the holding element X1 the same electrical potential. As the retaining element X1 on the housing GG is attached, there is thus an electrically conductive contact between the shaft W. and housing GG provided, provided the materials involved are suitable.

The holding element X1 is by means of a conical snap ring SP on the housing GG attached. Due to the conical shape of the snap ring SP becomes the holding element X1 against a contact surface of the housing GG pressed so that the electrically conductive contact between the holding element X1 and housing GG is ensured. The contact surface is formed by an annular surface which extends essentially in the radial direction and whose center is coaxial with the axis of rotation of the shaft W. is arranged.

The device X according to the in 1 illustrated embodiment can have two protective elements X3a , X3b exhibit. The protective elements X3a , X3b are axially on both sides of the contact element X2 arranged, and protect the contact point between contact element X2 and slip ring WS against environmental influences such as dust, chips etc. The protective elements X3a , X3b can for example be formed from a fleece or an elastomer element.

The device X is immediately adjacent to a radial shaft seal D. arranged. The radial shaft seal D. acts between housing GG and wave W. , and seals an interior of the housing GG towards the environment. The device X is located on the outside of the housing GG .

4th shows a sectional view of the device X according to a second possible embodiment. In contrast to the embodiment according to 3 the protective elements are omitted. The device X can therefore be particularly close to the radial shaft seal D. are arranged so that the holding element X1 on a carrier element of the radial shaft seal D. is applied. Such a construction of the device X is especially for applications suitable where the device X is used in an environment protected from the outside.

5 Figure 3 shows a view of the device X according to a third possible embodiment. In this third embodiment the device comprises X additionally a connecting element Y , which for the electrically conductive connection between the holding element X1 and the case GG serves. The connecting element Y has a flexible band which is riveted to a tab XY of the holding element X1 connected is. The flexible band is connected to a sheet metal strip via another riveted connection Y1 connected, which by means of a screw Y2 on the housing GG is attached. A surface of the sheet metal strip on the housing side Y2 has a shape which allows damage to and penetration of a superficial oxide layer of the housing GG is set up.

6th shows a detailed view of the device X according to the in 5 illustrated third embodiment. This clearly shows that on the holding element X1 a release for the tab XY is provided, and that the holding element X1 two axially aligned projections in the area of the clearance XY2 having. The protrusions XY2 are by bending over sections of the retaining element X1 educated. The protrusions XY2 are arranged and aligned so that a rotation of the snap ring SP does not damage the fastener Y can lead.

7th Figure 10 shows a portion of a sectional view of the device X according to the in 5 and 6th illustrated embodiment. This is the spatial course of the flexible band Y clearly visible. By such a course of the tape Y can be the electrically conductive connection between shaft W. (in 7th not visible) and the housing GG through a gap between the housing GG and an adjacent housing GG2 be passed through. In 7th is also the shape of the sheet metal strip on the housing side Y1 indicated which lead to damage and penetration of the surface oxide layer of the housing GG is provided.

List of reference symbols

VM

Internal combustion engine

G

Drive train unit, transmission

EM

Electric machine

RS

Wheelset

GG

casing

W.

wave

WS

Shaft slip ring

GW1

Input shaft

GW2

Output shaft

AG

Differential gear

DW

drive wheel

X

contraption

X1

Retaining element

X1b

Additional holding element

X2

Contact element

SP

Snap ring

X3a

Protective element

X3b

Protective element

D.

Radial shaft seal

Y

Connecting element

Y1

Sheet metal strips

Y2

screw

XY

Tab

XY2

axial projectionGG2 further housing

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 10249770 A1 [0002]
• DE 102016010926 A1 [0003]

Claims (19)

Device (X) for the electrically conductive connection between a shaft (W) and a housing (GG) in which the shaft (W) is rotatably mounted, comprising an electrically conductive holding element (X1, X1b) and one on the holding element (X1, X1b) ) attached, electrically conductive contact element (X2), • wherein the contact element (X2) is set up to establish an electrically conductive connection between the shaft (W) and the holding element (X1, X1b), • wherein the holding element (X1, X1b) is used an electrically conductive connection is established between the contact element (X2) and the housing (GG), characterized in that the retaining element (X1, X1b) is attached to the housing (GG) by means of a snap ring (SP). Device (X) after Claim 1 , characterized in that the snap ring (SP) is designed as a conical snap ring. Device (X) after Claim 2 , characterized in that by means of the conical snap ring (SP) a pretensioning force acting on the holding element (X1, X1b) can be generated, by means of which the holding element (X1, X1b) can be pretensioned against a contact surface of the housing (GG). Device (X) after Claim 3 , characterized in that the contact surface is formed by an annular surface, the center of which is arranged coaxially to an axis of rotation of the shaft (W) Device (X) according to one of the Claims 1 to 4th , characterized in that the holding element (X1, X1b) is connected to the housing (GG) via an electrically conductive connecting element (Y), a housing-side end of the connecting element (Y) having a shape by means of which a secure electrically conductive contact between Connecting element (Y) and housing (GG) can be produced. Device (X) after Claim 5 , characterized in that the connecting element (Y) comprises a flexible band. Device (X) after Claim 5 or 6th , characterized in that a sheet metal strip (Y1) is provided on the housing-side end of the connecting element (Y), which strip can be fastened to the housing (GG) by means of a screw (Y2). Device (X) according to one of the Claims 5 to 7th , characterized in that a tab (XY) is formed on the holding element (X1, X1b) to which the connecting element (Y) is attached. Device (X) after Claim 8 , characterized in that an exposure for the tab (XY) is provided on the holding element (X1, X1b), the holding element (X1, X1b) having at least one axially oriented projection (XY2) in the region of the exposure. Device (X) after Claim 9 , characterized in that the axially aligned projection (XY2) is arranged and aligned in such a way that direct contact between the snap ring (SP) and the connecting element (Y) is prevented. Device (X) according to one of the Claims 1 to 10 , characterized in that at least one protective element (X3a, X3b) is attached to the holding element (X1, X1b) and is designed to protect the electrically conductive contact point between contact element (X2) and shaft (W) against external influences. Device (X) after Claim 11 , characterized in that the at least one protective element (X3a, X3b) is formed by an elastomer element or by a fleece. Device (X) after Claim 11 or Claim 12 , characterized in that two protective elements (X3a, X3b) are provided, the electrically conductive contact point between the contact element (X2) and shaft (W) being arranged between the two protective elements (X3a, X3b). Drive train unit (G) for a motor vehicle, the drive train unit (G) having a housing (GG) with a shaft (W) rotatably mounted therein, characterized by a device (X) for the electrically conductive connection between the shaft (W) and the housing (GG) according to one of the Claims 1 to 13 . Drive train unit (G) Claim 14 , characterized in that the device (X) is arranged immediately adjacent to a radial shaft sealing ring (D) assigned to the shaft (W). Drive train unit (G) Claim 14 or Claim 15 , characterized in that the shaft (W) is formed by an input shaft (GW1) or by an output shaft (GW2) of the drive train unit (G). Drive train unit (G) according to one of the Claims 14 to 16 , characterized in that the drive train unit (G) has an electrical machine (EM) which is set up to drive the shaft (W). Drive train unit (G) according to one of the Claims 14 to 17th , characterized in that the drive train unit (G) has a gear set (RS) and several shifting elements to form several gear ratios. Drive train unit (G) according to one of the Claims 14 to 18th , characterized in that the drive train unit (G) is formed by an automated transmission, an automatic transmission or an electric axle drive.

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