A grounding ring and a component including such a grounding ring

Abstract

A ground ring, comprising a substantially circular-ring-shaped hub (1) and at least two sliding contacts (4.1, 4.2, …), the sliding contacts being arranged on the outside of the hub (1) in a radial direction (2) and extending in a circumferential direction (3), in the state of the ground ring determined by manufacturing, the sliding contacts being arranged adjacent to each other in the circumferential direction (3) with a spacing (5) and defining a circumferential gap (8) with their sides (6, 7) facing each other in the circumferential direction (3), wherein during normal use of the ground ring, the circumferential gap (8) is substantially eliminated by the sides (6, 7) facing each other but not overlapping each other.

Description

Field of the Invention

[0001] The present invention relates to a ground ring and an assembly including such a ground ring. Background Art

[0002] A ground ring and an assembly including such a ground ring are disclosed by DE 10 2018 105 376 A1.

[0003] The ground ring is configured as a front seal for a sealing ring and is made of a conductive material that, during its normal use, abuts against the surface of a first machine element to be grounded. A second machine element, which is also made of a conductive material and is concentrically arranged with the first machine element, is grounded to a defined ground potential, wherein the first machine element and the second machine element are conductively connected through the ground ring.

[0004] A seal is disclosed by DE 10 2013 000 982 A1, which includes a sealing ring having at least one dynamically stressed sealing lip and a front seal configured as a ground ring. The front seal is arranged adjacent to the sealing lip at an axial distance and is made of a conductive material. The sealing lip and the front seal sealingly surround the surface to be sealed of a first machine element to be sealed, wherein the first machine element is arranged adjacent to a second machine element at a radial distance. The sealing ring and the front seal are arranged in a gap formed by the radial distance. The second machine element is grounded to a defined ground potential, wherein the first machine element and the second machine element are respectively abutted against by the front seal and are thereby conductively connected to each other.

[0005] The front seal is configured as a potential compensation ring and is made of, for example, a conductive non-woven fabric impregnated with PTFE. Thus, mechanical damage to mechanical elements caused by voltage breakdown is excluded.

[0006] In the absence of potential compensation, different potentials of machine elements are compensated by voltage breakdown, which may cause mechanical damage to the machine elements to be sealed relative to each other. The closer the machine elements with different potentials are distributed adjacent to each other, the greater the possibility of such voltage breakdown. Voltage breakdown can cause material erosion on the mechanical elements with relatively low charges, thereby changing the material structure in the region where voltage breakdown occurs.

[0007] Another front seal is disclosed by DE 10 2014 010 269 A1. The front seal includes a disk that is substantially circularly configured and made of a conductive and breathable material, and a carrier, wherein the disk (with respect to the carrier) is configured as a separately manufactured part and is connected to the carrier.

[0008] The carrier can be formed by a sealing ring.

[0009] The front seal not only takes on the task of potential compensation, but also the task of preventing impurities from the surrounding environment from advancing towards the sealing lip of the sealing ring. The front seal is a decoupling bridge. In this context, "decoupling" is understood to mean, for example, that the sealing function of the sealing ring combined with the front seal is decoupled from the function of the bridge (i.e., the function of avoiding voltage breakdown and causing potential compensation between machine elements).

[0010] An axial earthing ring is disclosed by WO 2017 / 148586 A1, which is used to conduct induced voltage or charge from a first machine element, preferably a shaft, into a second machine element. The axial earthing ring has an annular housing made of a conductive material, which is conductively connected to one machine element and conductively connected to at least one conducting-out element. The conducting-out element is also made of a conductive material and is conductively connected to another machine element. The conducting-out element is a disc-shaped conducting-out body that extends over at least a part of its circumference. Summary of the Invention

[0011] The main object of the present invention is to further improve the earthing ring such that the entire circumference of the machine element that is substantially in contact with the sliding contact is used for contact via the sliding contact, and thereby compensate for the different potentials of the machine elements conductively connected by the earthing ring. Voltage breakdown between the machine elements should be effectively prevented.

[0012] In addition, the earthing ring should be able to be manufactured in an inexpensive and process-reliable manner in terms of economy and manufacturing technology.

[0013] According to the present invention, this object is achieved by the earthing ring according to claim 1 and the assembly according to claim 11.

[0014] Claims that directly or indirectly refer to claim 1 relate to advantageous design solutions of the earthing ring, and claims that directly or indirectly refer to claim 11 relate to advantageous design solutions of the assembly.

[0015] To achieve this object, an earthing ring is provided, which includes a substantially circular-ring-shaped hub and at least two sliding contacts that are arranged radially outside the hub and extend in the circumferential direction. In the state of the earthing ring determined by manufacturing, the sliding contacts are arranged adjacent to each other at a spacing in the circumferential direction and define a circumferential gap with their sides facing each other in the circumferential direction, wherein during the normal use of the earthing ring, the circumferential gap is substantially eliminated (bridged) by the sides facing each other but not overlapping each other.

[0016] The sliding contact portion of the grounding ring according to the invention provides for external contact in the radial direction. In principle, the grounding ring according to the invention is implemented during its normal use in a component having a first machine element and a second machine element, wherein the grounding ring and the two machine elements are each made of a conductive material. The first machine element, formed for example by a shaft or an axle, is surrounded on the outer peripheral side by the second machine element at a radial spacing, and the second machine element is formed by a housing that surrounds the shaft or axle at a radial spacing, wherein the grounding ring for external contact is arranged in the gap formed by the spacing. The two machine elements are conductively connected to each other through the grounding ring. Thus, during normal use, the grounding ring provides potential compensation between the machine elements and thus prevents voltage breakdown.

[0017] In the state determined by manufacturing, the grounding ring basically has the shape of an annular disk, which includes an annular hub on the inner side in the radial direction and sliding contacts arranged adjacent to each other in the circumferential direction with a circumferential gap on the outer side in the radial direction.

[0018] During normal use, i.e., in the state where the grounding ring is installed, an overlap between the machine element against which the sliding contact abuts and the sliding contact is necessary in order to always ensure conductive contact, and to ensure conductive contact even when the machine element and the sliding contact are not arranged precisely concentrically with each other and / or when there is an imbalance in the machine element and / or the sliding contact during normal use.

[0019] Due to this necessary overlap, the sliding contacts must be squeezed to a smaller diameter from their state determined by manufacturing for normal use, so slitting between the individual sliding contacts is inevitable. Without slitting, the outer circumference would be compressed during installation of the grounding ring into the component and wrinkles would be generated in the circumferential direction.

[0020] However, the design according to slitting causes inevitable notches, and usually the entire circumference of the adjacent machine element can no longer be in abutting contact with the sliding contacts.

[0021] If a part of the inner circumference of the machine element is not in abutting contact with the sliding contacts, the effectiveness of the potential compensation is impaired, such that although there is a grounding ring in the component, an undesired voltage breakdown may occur between the machine elements.

[0022] To prevent this, it is stipulated in the earthing ring according to the invention that the circumferential gap is substantially eliminated (überbrückt) during normal use of the earthing ring by sides that face each other and do not overlap with each other. This earthing ring which makes external contact in the radial direction has the advantage that almost the entire inner circumference of the machine element adjacent to the sliding contact on the radially outer peripheral side abuts against the sliding contact. The almost full circumferential contact with the inner circumference of the machine element radially adjacent to the sliding contact gives the best possible potential compensation and maximum safety against voltage breakdown and damage to the machine element.

[0023] During normal use, the overlap of sliding contacts arranged adjacent to each other circumferentially would also be disadvantageous, since the overlapping sides of adjacent sliding contacts prevent complete contact with the adjacent machine element.

[0024] According to an advantageous design, it can be provided that the number of sliding contacts is from 4 to 50.

[0025] More preferably, the number is from 8 to 12.

[0026] With this number of sliding contacts, a good compromise is achieved between the low-cost manufacturability of the earthing ring and the good adaptability of the sliding contacts to the inner diameter of the machine element surrounding the sliding contacts on the outer peripheral side. The circumferential gap is substantially eliminated by the facing sides of adjacent sliding contacts, and the sides of adjacent sliding contacts do not unfavorably overlap in the circumferential direction.

[0027] The circumferential gap can have a radial extension of 2 mm to 20 mm. A large radial extension of the circumferential gap is meaningful when the first and second machine elements respectively have large diameters.

[0028] According to a first design, it can be stipulated that in the as-manufactured state of the earthing ring, the circumferential gap is defined as substantially U-shaped. Such a U-shaped defined circumferential gap can be manufactured particularly simply and at low cost. However, the bridging of the circumferential gap is only possible to a limited extent.

[0029] According to a technically better second design, it can be stipulated that in the as-manufactured state of the earthing ring, the circumferential gap is defined as substantially V-shaped. This V-shaped definition of the circumferential gap is advantageous in several respects. In the state where the earthing ring is installed, the circumferential gap can be substantially completely bridged, and the facing sides of adjacent sliding contacts do not overlap. This ensures particularly good, virtually continuous contact with the machine element surrounding the sliding contacts on the outer peripheral side.

[0030] Furthermore, it is advantageous that the sliding contact has a particularly good and strong resetting action due to the circumferential gap defined in a V-shape, since the base of the sliding contact is relatively wide and the sliding contact is fixed to the hub by means of this base.

[0031] The pressing force of the sliding contact on the inner circumference of the radially adjacent adjoining machine element is increased by the wide base. Thereby, even during a long service life, loosening is prevented and the sliding contact always abuts against the adjoining machine element with a constant pre-tensioning force.

[0032] As already mentioned above, the sliding contact can have a base on the side facing the hub in the radial direction and a free end on the side opposite thereto in the radial direction, wherein the base has a first width in the circumferential direction, wherein the free end has a second width in the circumferential direction, and wherein the first width is greater than the second width.

[0033] Preferably, the ratio of the first width to the second width is from 1.25 to 1.5. In the case of this ratio, the circumferential gap can be eliminated as much as possible by the mutually facing sides of the adjacent sliding contacts, such that the contact surface of the sliding contact with the inner peripheral surface of the machine element surrounding the earthing ring is particularly large. Furthermore, in the case of this ratio, the sliding contact has a sufficiently large resetting force during its normal use in the installed state, so as to provide reliable contact and thus reliable potential compensation in all operating states of the assembly including the earthing ring.

[0034] The hub and the sliding contact can merge into one another integrally, be constructed of the same material and consist of an electrically conductive material.

[0035] The electrically conductive material can be a metallic material. Electrically conductive metallic materials are mostly inexpensive and are available in a wide variety of specifications. Furthermore, it is easy to process them into an earthing ring, at low cost and with reliable technology.

[0036] As already explained previously, the earthing ring of the assembly and the two machine elements are each made of an electrically conductive material, wherein the first machine element is surrounded by the second machine element at a radial spacing, and the earthing ring is arranged in the gap formed by this spacing. The earthing ring is torsion-resistant and is conductively connected to the first machine element, and is conductively and rotatably in contact with the second machine element and abuts against the inside under an elastic pre-tensioning force in the radial direction, wherein the second machine element surrounds the first machine element on the outer peripheral side. By means of the earthing ring, the two machine elements are conductively connected to one another; the earthing ring ensures potential compensation between the two machine elements.

[0037] The sliding contact can be assigned to the second machine element, which has a radially external covering that is from 1 mm to 6 mm.

[0038] The sliding contact can be assigned to a first machine element which has a radially inner covering with a thickness of 0.2 mm to 1.2 mm.

[0039] The above-mentioned covering ensures a particularly reliable and good potential compensation between the machine elements via the ground ring.

[0040] Depending on the assembly direction of the ground ring, the bending direction of the sliding contact in the radial direction on the outside of the second machine element can be implemented in two axial directions.

[0041] The ground ring is preferably connected to the first machine element in a form-fitting and / or force-fitting manner. This results in a torsion-resistant connection that can be manufactured simply and inexpensively.

[0042] Generally, there is the possibility that the ground ring and the first machine element rotate together and the sliding contact of the ground ring thus bears on the inner circumference of the stationary second machine element. There is also the possibility that the second machine element rotates around the first machine element and the ground ring.

[0043] The current between the ground ring and the first machine element is alternatively achieved by the hub of the ground ring and the first machine element being in direct abutting contact or indirectly in contact via a conductive adhesive, with the ground ring being torsion-resistantly connected to the first machine element.

[0044] Preferably, the first machine element and the ground ring form a pre-assemblable unit which performs a relative rotational movement with respect to the second machine element. Description of the Drawings

[0045] Three embodiments of the ground ring according to the invention are schematically shown in Figure 1a , 1b , 2a, 2b and 3 respectively and will be described in more detail below.

[0046] In Figure 1a the first embodiment of the ground ring is shown in a side view from the right and in the state determined by manufacturing,

[0047] In Figure 1b an exemplary assembly with the ground ring from Figure 1a is shown,

[0048] In Figure 2a the second embodiment of the ground ring is shown in a side view from the right and in the state determined by manufacturing, and

[0049] In Figure 2b an exemplary assembly with the ground ring from Figure 2a is shown.

[0050] In Figure 3A third embodiment of a grounding ring is shown, which is configured as a two-piece and electrically conducts against a first machine element with a radially inner covering portion and against a second machine element with a radially outer covering portion, respectively. Detailed Description

[0051] Figure 1a and 1b A first embodiment of a grounding ring and a component including the grounding ring is shown.

[0052] In Figure 1a a side view from the right shows the grounding ring in its as-manufactured state. The grounding ring includes an annular hub 1 and twelve sliding contacts 4.1, 4.2,..., 4.12 arranged radially outside the hub 1 in the radial direction 2. The sliding contacts 4.1, 4.2,..., 4.12 extend in the circumferential direction 3 and are arranged adjacent to each other in the circumferential direction 3 with a spacing 5. The sides 6, 7 of adjacent sliding contacts 4.1, 4.2,..., 4.12 facing each other in the circumferential direction 3 define a circumferential gap 8, which is defined as substantially V-shaped in the shown embodiment.

[0053] In Figure 1b the grounding ring in Figure 1a is also shown in a view from the right, however, it will be installed in a component according to the present invention during its normal use.

[0054] The grounding ring is torsionally connected to a first machine element 13 by means of its hub 1, and the first machine element 13 is configured as a shaft 15 or an axle 16. In the radial direction, the grounding ring is surrounded on its outer peripheral side by a second machine element 14, which is formed by a housing 17 in the shown embodiment. The grounding ring is arranged in a gap 18 between the first machine element 13 and the second machine element 14.

[0055] The grounding ring and the two machine elements 13, 14 are each made of a conductive material.

[0056] During the assembly of the grounding ring into the gap 18, the outer diameters of the sliding contacts 4.1, 4.2,..., 4.12 are reduced in order to achieve the overlap required to press the sliding contacts 4.1, 4.2,..., 4.12 against the inner circumference of the second machine element 14. Through this overlap, the sliding contacts 4.1, 4.2,..., 4.12 are pressed against the inner circumference of the second machine element 14 under a radial preload force.

[0057] By assembling the grounding ring together with the first machine element 13 into the second machine element 14, the circumferential gap 8 between the sliding contacts 4.1, 4.2, …, 4.12 adjacent to each other is substantially completely closed, such that the inner circumference of the second machine element 14 is actually continuously abutted and contacted by the sliding contacts 4.1, 4.2, …, 4.12 in the circumferential direction. Thereby, particularly effective potential compensation can be achieved.

[0058] As Figure 1a can be seen particularly clearly, the base 9 of the sliding contacts 4.1, 4.2, …, 4.12 is wider on the side facing the hub 1 in the radial direction 2 than the free end 10 opposite to the base 9 in the radial direction 2.

[0059] In the illustrated embodiment, the ratio of the first width 11 of the base 9 to the second width 12 of the free end 10 is approximately 1.3.

[0060] The hub 1 and the sliding contacts 4.1, 4.2, …, 4.12 transition integrally into each other in the illustrated embodiment, are constructed of the same material and are made of a conductive metal material.

[0061] In Figure 2a a second embodiment of the grounding ring is shown, in which the circumferential gap 8 between the sliding contacts 4.1, 4.2, …, 4.9 is defined as U-shaped.

[0062] Regarding Figure 1a the V-shaped defined circumferential gap 8 in Figure 2a the U-shaped defined circumferential gap 8 in Figure 1a is less advantageous because the contact surface between the sliding contacts 4.1, 4.2, …, 4.9 and the second machine element 14 is slightly smaller during the normal use of the grounding ring than in the embodiment in

[0063] In Figure 2b the grounding ring in Figure 2a is also shown in a view from the right, however, it will be installed into the component according to the present invention during its normal use.

[0064] Figure 1a And 2a the two grounding rings in

[0065] In Figure 3A third embodiment of the ground ring is shown, which is configured as a two-piece with a radially inner covering part 20 on the first machine element 13 and a radially outer covering part 19 on the second machine element 14, both being conductive. In the embodiment shown here, the radially outer covering part 19 is approximately 5 mm, while in contrast, the radially inner covering part 20 is approximately 1 mm.

[0066] Depending on the size of the diameters of the two machine elements 13 and 14, the circumferential gap 8 in the previously shown embodiment has a radial extension of 2 mm to 20 mm respectively.

Claims

1. A grounding ring, comprising a substantially circular ring-shaped hub (1) and at least two sliding contacts (4.1, 4.2, …), which are arranged on the outside of the hub (1) in the radial direction (2) and extend in the circumferential direction (3). In the state of the grounding ring determined by manufacturing, the sliding contacts are arranged adjacent to each other in the circumferential direction (3) with a spacing (5) and define a circumferential gap (8) with their sides (6, 7) facing each other in the circumferential direction (3), wherein, The sliding contacts (4.1, 4.2, …) have a base (9) on the side facing the hub (1) in the radial direction (2) and a free end (10) on the opposite side in the radial direction (2). The base (9) has a first width (11) in the circumferential direction (3), the free end (10) has a second width (12) in the circumferential direction (3), and the first width (11) is greater than the second width (12).

2. The grounding ring according to claim 1, characterized in that, The number of the sliding contacts (4.1, 4.2, …) is from 4 to 50.

3. The grounding ring according to claim 1 or 2, characterized in that, The number of the sliding contacts (4.1, 4.2, …) is from 8 to 12.

4. The grounding ring according to claim 1, characterized in that, The circumferential gap (8) has a radial extension of 2 mm to 20 mm.

5. The grounding ring according to claim 1, characterized in that, In the state determined by manufacturing of the ground ring, the circumferential gap (8) is defined as being substantially V-shaped.

6. The grounding ring according to claim 1, wherein The ratio of the first width (11) to the second width (12) is from 1.25 to 1.

5.

7. The grounding ring according to claim 1, wherein The hub (1) and the sliding contacts (4.1, 4.2, …) transition into each other integrally, are constructed of the same material and are made of a conductive material.

8. The grounding ring according to claim 7, wherein The conductive material is a metallic material.

9. A component, comprising a ground ring according to any one of claims 1 to 8, and a first machine element (13) and a second machine element (14), wherein the first machine element (13) and the second machine element (14) are each made of a conductive material, wherein, The first machine element (13) is formed by a shaft (15) or an axle (16), and the second machine element (14) is formed by a housing (17) surrounding the shaft (15) or the axle (16) at a radial distance, wherein the ground ring is arranged in a gap (18) formed by the distance.

10. The component according to claim 9, characterized in that, The ground ring is connected to the first machine element (13) against torsional rotation and is rotatable relative to the second machine element (14) and abuts against it in the inner side in the radial direction (2).

11. The component according to claim 9, characterized in that, The sliding contacts (4.1, 4.2, …) are assigned a radially outer covering (19) for the second machine element (14), and the covering (19) is from 1 mm to 6 mm.

12. The component according to claim 9, wherein The sliding contacts (4.1, 4.2, …) are assigned a radially inner covering (20) for the first machine element (13), and the covering (20) is from 0.2 mm to 1.2 mm.

13. The component according to claim 9, wherein The ground ring is connected to the first machine element (13) form-locked and / or force-locked.

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