Sealing element

Abstract

The invention relates to a sealing element (1) for producing an electrically conductive connection between a first mechanical element (2) and a second mechanical element (3), comprising at least one sealing disc (4) and a support ring (5), said support ring (5) comprising an axial flange (14) and a radial flange (13), said sealing disc (4) being formed from an electrically conductive non-woven fabric, the sealing disc (4) is fixed between the support ring (5) and the second mechanical element (3) at least in a portion along the axial flange (14) by a clamping connection.

Description

TECHNICAL FIELD

[0001] The invention relates to a sealing element for producing an electrically conductive connection between a first mechanical element and a second mechanical element, comprising at least one sealing disc and a support ring, wherein the sealing disc is made of an electrically conductive nonwoven fabric. BACKGROUND

[0002] German patent DE 10 2013 000 982 A1 discloses a sealing element comprising a sealing ring with at least one dynamically stressed sealing lip and a buffer sealing element. The buffer sealing element is arranged in axial spacing adjacent to the sealing lip and is composed of an electrically conductive material. The sealing lip and the buffer sealing element surround the surface to be sealed of the first mechanical element in a sealing manner. The first mechanical element is arranged in radial spacing adjacent to the second mechanical element. The sealing ring and the buffer sealing element are arranged in the gap formed by the radial spacing. The first mechanical element and the second mechanical element are connected together in an electrically conductive manner by the buffer sealing element. For this purpose, the buffer sealing element is adjacent to and in contact with the first mechanical element and the second mechanical element. The buffer sealing element is formed as a potential equalization ring and is composed of an electrically conductive nonwoven fabric impregnated with PTFE.

[0003] The buffer sealing element enables a potential equalization between the two mechanical elements and prevents mechanical damage that can occur when different sized potentials of the mechanical elements are equalized by electrical breakdown. Electrical breakdown can cause material to be removed from the mechanical elements at relatively low electrical charges and cause a change in the microstructure of the material in the area where the electrical breakdown occurred.

[0004] German patent DE 10 2014 010 269 A1 discloses another buffer sealing element. The buffer sealing element comprises a circular ring-shaped disc composed of an electrically conductive and gas-permeable material and a support body, the ring-shaped disc being formed separately and connected to the support body. The support body is formed by a sealing ring.

[0005] In the previously known sealing element, the electrically conductive sealing element is fixed in an integral bond along the end face of the radial flange of the sealing ring. SUMMARY

[0006] It is an object of the invention to provide a sealing element of the type mentioned in the technical field that can be produced in a simple and cost-effective manner.

[0007] This object is achieved by the features of claim 1. The dependent claims relate to preferred embodiments.

[0008] To achieve this object, the sealing element comprises at least one sealing disc and a support ring, the support ring comprising an axial flange and a radial flange, the sealing disc being formed from an electrically conductive nonwoven fabric and being fixed between the support ring and the second mechanical element at least in sections along the axial flange by a clamping connection. The clamping connection of the sealing disc and the support ring can be formed in a particularly simple manner. In particular, a pretreatment step of the support ring and / or the sealing disc, which is required in most cases for the connection of the sealing disc to the support ring in an integral bond, can be omitted. The sealing disc is formed from an electrically conductive material and is positioned relative to the support ring in such a way that a clamping connection which fixes the sealing disc in position is produced.

[0009] According to the application, the sealing disc extends at least along the axial flange section of the support ring. In this embodiment, the sealing disc is pressed not only in the axial direction but also in the radial direction. Depending on the design of the support ring, the sealing disc can be pressed directly against the inner wall of the second mechanical element. Preferably, the sealing disc is in direct contact with the second mechanical element in order to produce a relatively large contact surface for the electrical contact.

[0010] In the section of the sealing disc which is fixed between the support ring and the second mechanical element, the sealing disc is compressed by between 5% and 50% of the initial thickness. Preferably, the compression is between 10% and 30% of the initial thickness. The term "initial thickness" is to be understood as meaning the thickness of the sealing disc in the uninstalled state. The sealing disc is compressed as a result of the clamping connection, so that the thickness of the sealing disc is reduced. In this respect, the thickness of the sealing disc in the clamped section is between 70% and 90% of the initial thickness. This compression produces a secure clamping connection which prevents the sealing disc from becoming detached from the sealing element. Furthermore, the surface of the sealing disc is in close contact with the wall of the support ring and the second mechanical element, so that the electrical conductivity between the sealing disc and the second mechanical element is improved.

[0011] In order to increase the local clamping force, the support ring can be provided with a pressing profile. This pressing profile can be formed, for example, in the manner of a circumferential bead which projects on the outer circumference side of the axial flange. Alternatively, it is also possible to provide a circumferential protrusion along the axial flange.

[0012] It is also possible to provide a pressing element in the region of the clamped sealing disc. The pressing element can be formed by an O-ring. The pressing element can be arranged between the sealing disc and the support ring or between the sealing disc and the second mechanical element. The sealing disc is compressed to a greater extent in the region of the pressing element, which facilitates an improved clamping effect.

[0013] The sealing disc can be fixed between the sealing ring and the second mechanical element. In this embodiment, the second mechanical element preferably comprises a step with a radial shoulder. The support ring is preferably L-shaped and comprises a radial flange and an axial flange. The axial flange is arranged on the outer circumferential side of the radial flange. In this embodiment, a clamping connection is formed between the radial shoulder of the second mechanical element and the support ring. The sealing disc is clamped between the sealing ring and the second mechanical element.

[0014] Preferably, the sealing disc extends along the radial flange and at least partially along the axial flange of the support ring. In this case, the sealing disc connects the first mechanical element and the second mechanical element. In this case, it is not necessary to design the support ring in an electrically conductive manner. The sealing disc is biased radially against the first mechanical element, wherein the sealing disc protrudes partially in the axial direction after installation. As a result, an electrically conductive connection is formed between the sealing disc and the first mechanical element.

[0015] In this embodiment, the electrically conductive connection of the sealing disc and the second mechanical element is produced by the clamping connection directly pressing the sealing disc against the second mechanical element or against the radial shoulder of the second mechanical element.

[0016] The axial flange of the support ring can comprise a step, so that the part of the axial flange associated with the radial flange has a smaller diameter than the part associated with the free end. The reduction in cross-section creates a space for accommodating the sealing disc. The accommodation space prevents excessive compression of the sealing disc. The sealing disc is pressed by the step, so that the thickness of the sealing disc in the region of the step is reduced by 10% to 30% compared to the initial thickness of the sealing disc. At the same time, the free end of the axial flange directly abuts against the second mechanical element, so that forces can be transmitted directly between the support ring and the second mechanical element and the sealing disc is placed in the force diversion path.

[0017] The support ring can comprise an inner ring and an outer ring, wherein the sealing disc is fixed between the inner ring and the outer ring. In this embodiment, a clamping connection is produced between the inner ring and the outer ring. The advantage is that the sealing element and the sealing disc can be formed together as a pre-assembled unit. In this embodiment, the outer ring is formed at least in an electrically conductive manner. In this embodiment, the sealing disc is compressed between the inner ring and the outer ring. Preferably, the sealing disc, the inner ring and the outer ring are configured such that the sealing disc is compressed in the clamping region by between 10% and 30% of the initial thickness of the sealing disc.

[0018] The inner ring and the outer ring each comprise a radial flange and an axial flange, wherein the outer diameter of the axial flange of the inner ring substantially corresponds to the inner diameter of the axial flange of the outer ring. From the support ring, the sealing disc extends radially inwards and elastically abuts against the outer circumferential side of the first mechanical element in a sealing manner. The sealing disc protrudes in the axial direction opposite the extension of the axial flange of the support ring.

[0019] The free end of the axial flange of the outer ring can be bent radially inwards and at least partially cover the axial flange of the inner ring. Thus, the inner ring can be prevented from separating from the outer ring.

[0020] The inner ring can be provided with a conical cross-section at the portion of the axial flange associated with the radial flange. The receiving space in which the sealing disc can extend is produced by this conical cross-section. In this embodiment, the sealing disc can extend along the radial flanges of the inner and outer rings, but also along the axial flange portions of the inner and outer rings.

[0021] The support ring can comprise at least one intermediate ring, wherein a first sealing disc is fixed between the inner ring and the intermediate ring and at least one second sealing disc is fixed between the intermediate ring and the outer ring. According to the design, a plurality of intermediate rings can be provided, wherein in each case a sealing disc is arranged between the inner ring, the individual intermediate ring and the outer ring. The sealing discs can be made of mutually different materials.

[0022] The sealing discs fixed between the inner ring, the intermediate ring and the outer ring are biased radially against the first mechanical element and protrude in the axial direction. At least one of the two sealing discs is designed in an electrically conductive manner. Likewise, the outer ring is electrically conductive. Furthermore, the inner ring and / or the intermediate ring can also be electrically conductive.

[0023] In a preferred embodiment, one sealing disc can be electrically conductive and the second sealing disc has a soft-magnetic filling to serve as an electromagnetic barrier that shields against interfering electromagnetic waves. Alternatively, it is also possible for the inner ring or the intermediate ring to have such a soft-magnetic filling. In this respect, the embodiment of the sealing element with two sealing discs allows an electrically conductive connection between the first mechanical element and the second mechanical element to be produced and also shields against interfering electromagnetic waves. Due to the provision of a plurality of sealing discs, the sealing effect is also improved.

[0024] In this embodiment, it is also possible for the axial flange of the outer ring to be flattened inwards at its free end and thus to cover the axial flange of the inner ring, whereby the sealing disc and the intermediate ring are clamped between the inner ring and the outer ring, wherein the inner ring is locked on the outer ring in a form-fit manner.

[0025] A radial shaft sealing ring can be arranged on the inner ring. This is preferably fixed on the radially inner free end of the radial flange of the inner ring.

[0026] Alternatively, an elastomer track can be provided on the inner ring. From this elastomer track, the radial shaft sealing ring can be formed. Furthermore, the elastomer track can cover the end face of the radial flange associated with the outer ring and the surface of the axial flange associated with the second mechanical element. In the region of the axial flange, the elastomer track forms a static seal. The elastomer track clamps the sealing disc between the inner ring and the outer ring. From the elastomer track, a receptacle can be formed in which the sealing disc can be arranged. Thus, excessive compression of the sealing disc is prevented.

[0027] The sealing disc can comprise electrically conductive particles. The electrically conductive particles provide the electrical conductivity of the sealing disc. Preferably, the electrically conductive particles are formed as fibers, wherein electrically conductive fibers having a length of at least 10 mm are used in a particularly preferred manner. Such relatively long fibers can allow a direct transfer of the electric current, so that the sealing disc has a relatively low electrical resistance. Furthermore, preferably, the fibers can be in direct contact with the first and second mechanical elements.

[0028] The sealing disc formed from the nonwoven fabric is preferably saturated with the PTFE dispersion. Thus, the nonwoven fabric is stabilized in comparison to the first mechanical element, and the coefficient of friction is reduced. Thus, the service life of the sealing element is prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0029] Some embodiments of the sealing element according to the application will be explained in more detail below with the aid of the drawings. These drawings show in each case schematically:

[0030] Figure 1 a cross-sectional view of a sealing element having a support ring with an inner ring and an outer ring is shown;

[0031] Figure 2 a sealing element having a form-fit connection of an inner ring and an outer ring is shown; Figure 1

[0032] Figure 3 a sealing element having an intermediate ring and two sealing discs is shown;

[0033] Figure 4 a cross-sectional view of a sealing element, wherein the sealing disc is clamped between the support ring and the housing is shown;

[0034] Figure 5 a sealing element before installation is shown; Figure 4

[0035] Figure 6 a sealing element having an additional space for accommodating the sealing disc is shown; Figure 5

[0036] Figure 7 a sealing element having a form-fit connection of an inner ring and an outer ring is shown; Figure 6

[0037] Figure 8 a sealing element having a radial shaft sealing ring integrally formed on the inner ring is shown;

[0038] Figure 9 a sealing element having an elastomer track integrally formed on the inner ring is shown. ​​​​Detailed Implementation

[0039] The accompanying drawing illustrates a sealing element 1 for creating a conductive connection between a first mechanical element 2 and a second mechanical element 3. In this embodiment, the first mechanical element 2 is a rotating shaft, and the second mechanical element 3 is a housing. The first mechanical element 2 and the second mechanical element 3 may be components of an electric drive system of a motor vehicle.

[0040] The sealing element 1 includes at least one sealing disc 4 and a support ring 5. The at least one sealing disc 4 is made of a conductive material. In this embodiment, the sealing disc 4 is formed of a non-woven fabric saturated with PTFE and contains conductive particles in the form of metal fibers. Preferably, the conductive particles may be composed of conductive carbon black or metal particles. The sealing disc 4 is fixed to the support ring 5 by a clamping connection.

[0041] exist Figure 1 In one embodiment, the support ring 5 includes an inner ring 6 and an outer ring 7, wherein a sealing disc 4 is fixed between the inner ring 6 and the outer ring 7. In this embodiment, at least the outer ring 7 is formed of a conductive material. Preferably, the inner ring 6 and the outer ring 7 are stamped parts and made of metal. The sealing disc 4 is clamped between the inner ring 6 and the outer ring 7 and fixed in that position. The inner ring 6 and the outer ring 7 each include a radial flange 13 and an axial flange 14, wherein the outer diameter of the axial flange 14 of the inner ring 6 substantially corresponds to the inner diameter of the axial flange 14 of the outer ring 7. This selection of the inner and outer diameters results in a press-fit arrangement, and thus the inner ring 6, the sealing disc 4, and the outer ring 7 are fitted in a constrained manner, one inside the other. In this embodiment, the radial flange of the outer ring 7 abuts against the radial shoulder of the second mechanical element 3.

[0042] Figure 2 It shows Figure 3 An alternative embodiment of the sealing element 1 is shown. In this embodiment, the free end 11 of the axial flange 14 of the outer ring 7 is bent radially inward. For this purpose, after the sealing disc 4 and the inner ring 6 are installed, the free end 11 is flattened inward. Thus, the inner ring 6 is locked in the outer ring 7 in a form-fitting manner. Furthermore, due to the resulting tapered cross-section in the region of the free end 11, the sealing element 1 can be positioned in the second mechanical element 3 such that the free end 11 abuts against the radial shoulder of the second mechanical element 3.

[0043] Figure 3 A sealing element 1 is shown, wherein the support ring 5 includes an intermediate ring 8. A first sealing disc 4' is fixed between the inner ring 6 and the intermediate ring 8, and a second sealing disc 4" is fixed between the intermediate ring 8 and the outer ring 7.

[0044] In this embodiment, at least the outer ring 7 is formed from an electrically conductive material. Preferably, the inner ring 6, the intermediate ring 8 and the outer ring 7 are formed as stamped parts and are made of a metallic material. The two sealing discs 4', 4" are clamped between the inner ring 6 and the intermediate ring 8 and between the intermediate ring 8 and the outer ring 7 and are fixed in this position. The inner ring 6 and the outer ring 7 each comprise a radial flange 13 and an axial flange 14, wherein the outer diameter of the axial flange 14 of the inner ring 6 essentially corresponds to the inner diameter of the axial flange 14 of the outer ring 7. This inner diameter and outer diameter are selected such that a press-fit arrangement is created and thus the inner ring 6, the intermediate ring 8, the sealing discs 4', 4" and the outer ring 7 fit one inside the other in a constraining manner. In this embodiment, the radial flange 13 of the outer ring 7 abuts against a radial shoulder of the second mechanical element 3.

[0045] In this embodiment, the free end 11 of the axial flange 14 of the outer ring 7 is bent radially inwards. To this end, the free end 11 is bent inwards and downwards after the sealing discs 4 and the inner ring 6 have been installed. Thus, the inner ring 6 is locked in the outer ring 7 in a form-fit manner. Furthermore, due to the conical cross-section created thereby in the region of the free end 11, the sealing element 1 can be positioned in the second mechanical element 3 such that the free end 11 abuts against a radial shoulder of the second mechanical element 3.

[0046] The inner ring 6, the intermediate ring 8 and the outer ring 7 are all electrically conductive. Furthermore, at least one sealing disc 4' is electrically conductive. It is also possible for both sealing discs 4', 4" to be designed to be electrically conductive. Alternatively, only one sealing disc 4' is designed to be electrically conductive, while the other sealing disc 4" is formed from a soft magnetic material. In this case, the other sealing disc 4" forms a barrier to prevent electromagnetic radiation interference.

[0047] In the embodiment shown in Figure 4 In this embodiment, the sealing disc 4 is fixed between the support ring 5 and the second mechanical element 3. On the end face, the sealing disc 4 abuts against the radial flange 13 of the support ring 5 and also extends on the outer peripheral side on the axial flange 14 of the support ring 5. A radial shoulder is formed by the second mechanical element 3, i.e. the housing, wherein the sealing disc 4 is clamped between the radial shoulder of the second mechanical element 3 and the support ring 5 after installation and is thereby fixed in position.

[0048] The support ring 5 comprises a step which creates a space 12 for accommodating the sealing disc 4. The step is formed such that the sealing disc 4 is clamped between the support ring 5 and the second mechanical element 3, in this case the housing, wherein the sealing disc 4 is compressed by 20% compared to the initial thickness of the sealing disc 4. Thus, the thickness of the sealing disc 4 in the clamping region is 80% of the initial thickness, which is less than the initial thickness.

[0049] In this embodiment, the sealing disc 4 forms a dynamic seal with respect to the first mechanical element 2 and a static seal with respect to the second mechanical element 3. Furthermore, the sealing disc 4 extends from the first mechanical element 2 to the second mechanical element 3, thus allowing conductive connection solely via the sealing disc 4. In this respect, the support ring 5 need not be made of a conductive material. It is feasible for the support ring 5 to be formed of plastic, preferably an injection-moldable plastic.

[0050] Figure 5 It shows Figure 1 The embodiment of the sealing element 1 before installation is shown. In this embodiment, the sealing disc 4 is positively connected to the end face of the radial flange 13 of the support ring 5, so that the sealing disc 4 and the support ring 5 are constrained together.

[0051] Figure 6 It shows Figure 3 Another alternative embodiment of the sealing element 1 shown. In Figure 6 In one embodiment, the support ring 5 includes an inner ring 6 and an outer ring 7, wherein a sealing disc 4 is fixed between the inner ring 6 and the outer ring 7. In this embodiment, at least the outer ring 7 is formed of a conductive material. Preferably, the inner ring 6 and the outer ring 7 are formed as stamped parts and are made of a metallic material. The sealing disc 4 is clamped between the inner ring 6 and the outer ring 7 and fixed in that position. The inner ring 6 and the outer ring 7 each include a radial flange 13 and an axial flange 14, wherein the outer diameter of the axial flange 14 of the inner ring 6 substantially corresponds to the inner diameter of the axial flange 14 of the outer ring 7. The inner and outer diameters are selected to create a press-fit arrangement, and thus the inner ring 6, the sealing disc 4, and the outer ring 7 are fitted in a constrained manner, one inside the other. In this embodiment, the radial flange 13 of the outer ring 7 abuts against the radial shoulder of the second mechanical element 3. In this embodiment, a tapered cross-section is also formed in the region of the axial flange 14 of the inner ring 6 and adjacent to the radial flange 13 of the inner ring 6. Therefore, a space 12 for accommodating the sealing disc 4 is formed between the inner ring 6 and the outer ring 7.

[0052] Figure 7 The implementation scheme shows Figure 6The illustration shows a variation of the sealing element 1. In this embodiment, the free end 11 of the axial flange 14 of the outer ring 7 is bent radially inward. For this purpose, after installing the sealing disc 4 and the inner ring 6, the free end 11 is flattened inward and downward. Thus, the inner ring 6 is locked in the outer ring 7 in a form-fit manner. Furthermore, due to the resulting tapered cross-section in the region of the free end 11, the sealing element 1 can be positioned within the second mechanical element 3 such that the free end 11 abuts against the radial shoulder of the second mechanical element 3. Additionally, a tapered cross-section is formed in the region of the axial flange 14 of the inner ring 6, adjacent to the radial flange 13 of the inner ring 6. Therefore, a space 12 for accommodating the sealing disc 4 is formed between the inner ring 6 and the outer ring 7.

[0053] Figure 8 It shows Figure 6 A variation of the sealing element 1 is shown. In this embodiment, a radial shaft sealing ring 9 is disposed on the end of the radial flange 13 of the inner ring 6, which is associated with the first mechanical element 2. The radial shaft sealing ring 9 is made of an elastic material and is integrally formed directly onto the inner ring 6. The radial shaft sealing ring 9 includes a sealing lip that is pressed against the first mechanical element 2 by a radially biased annular helical spring.

[0054] Figure 9 It shows Figure 6 Another variation of the sealing element 1 shown. In this embodiment, an elastomeric track 10 is provided on the inner ring 8. The elastomeric track 10 extends along the end face of the inner ring 6 facing the outer ring 7 and extends beyond the radial flange 13 and the axial flange 14. In the region of the axial flange 14, the elastomeric track 10 contacts the second mechanical element 3 and forms a static seal. The elastomeric track 10 forms a cavity on the end face facing the outer ring 7 for receiving the sealing disc 4. The radial axial sealing ring 9 is formed by the elastomeric track 10. The radial axial sealing ring 9 is made of an elastic material and is directly integrally formed on the inner ring 6. The radial axial sealing ring 9 includes a sealing lip that is pressed against the first mechanical element 2 by a radially biased annular helical spring.

Claims

1. A sealing element (1) for generating an conductive connection between a first mechanical element (2) and a second mechanical element (3), comprising at least one sealing disc (4) and a support ring (5), the support ring (5) comprising an axial flange (14) and a radial flange (13), the sealing disc (4) being formed of a conductive nonwoven fabric, and the sealing disc (4) being fixed between the support ring (5) and the second mechanical element (3) by a clamping connection at least in a portion along the axial flange (14), the support ring (5) comprising an inner ring (6) and an outer ring (7), wherein the sealing disc (4) is fixed between the inner ring (6) and the outer ring (7), characterized in that, A radial shaft sealing ring (9) is arranged on the inner ring (6).

2. The sealing element according to claim 1, characterized in that, In the portion of the sealing disc (4) that is fixed between the support ring (5) and the second mechanical element (3), the sealing disc (4) is compressed to an initial thickness of between 5% and 50%.

3. The sealing element according to claim 1, characterized in that, The outer ring (7) is conductive.

4. The sealing element according to any one of claims 1 to 3, characterized in that, The inner ring (6) is conductive.

5. The sealing element according to claim 1, characterized in that, An elastic track (10) is arranged on the inner ring (6).

6. The sealing element according to claim 5, characterized in that, The elastomeric track (10) forms a cavity for the sealing disc (4).

7. The sealing element according to any one of claims 1 to 6, characterized in that, The sealing disc (4) includes conductive particles.

8. The sealing element according to any one of claims 1 to 7, characterized in that, The sealing disc (4) formed of nonwoven fabric contains a PTFE dispersion.

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