Sealing device with grounding element

Abstract

The invention relates to a sealing device for sealing a first region against a second region filled with oil on a rotating component, comprising: a sealing ring made of an elastic material, which sealing ring has a first sealing flange, a second sealing flange and a connecting region, the connecting region connects the first sealing flange with the second sealing flange and has a front side facing the second region; a grounding element arranged on the rear side of the connection region and provided for electrically connecting the rotating member with the housing member; and a gap seal arranged in the axial direction between a sealing contact portion of the first sealing flange on the rotating member and the grounding element, the gap seal being arranged to maintain a gap with the rotating member, in order to ensure oil-resistant protection of the grounding element on one hand, and to prevent oil contamination on the other hand. On the other hand, oil or oil mist is supplied to the grounding element in a determined manner according to the gap height of the gap, so that contact lubrication is realized between the grounding element and the rotating component under the condition that the electrical characteristics of the grounding element are not functionally limited.

Description

Technical Field

[0001] The invention relates to a sealing device with a grounding element for sealing a first area, in particular the environment, from a second product area filled with oil, and to an electrical device having such a sealing device. Background Art

[0002] Sealing devices are known from the prior art in different designs. Such sealing devices are used, for example, in rotating electric machines with oil lubrication and oil cooling, in which the machine housing must be sealed on the shaft relative to the surrounding environment. Here, the rotating shaft must be electrically connected to the fixed component. Here, for example, DE102013000982A1 proposes that a sealing ring and a front seal made of a conductive material are provided to the sealing device, wherein an anti-fouling lip that abuts against the rotating component and forms a gap is provided between the front seal and the sealing ring in the axial direction. The task of the anti-fouling lip is to prevent dust and particles from reaching the sealing area from the outside in the direction of the sealing area on the sealing ring and thus entering the oil-filled area. This design has been verified in principle, but the problem is that the service life of the grounding element is short. The reason for the short service life is that the seal allows a very small amount of oil to pass, such as evaporated gap fluid. This will be absorbed by the grounding element and hinder electrical connection. Summary of the invention

[0003] It is therefore an object of the present invention to provide a sealing device with a grounding element and an electrical device which have an improved functionality and service life while being structurally simple and capable of being produced in a simple and economical manner.

[0004] This object is achieved by a sealing device having the features of claim 1 and an electrical device having the features of claim 15 , the dependent claims indicating preferred developments of the invention.

[0005] The sealing device according to the invention for sealing a first area with an oil-filled second product area of ​​a rotating component, having the features of claim 1, has the advantage that the grounding element has a significantly longer service life than in the prior art. Here, the grounding element is made, for example, of an electrically conductive nonwoven material. In addition, a gap seal is provided in the axial direction between an elastic sealing ring that is sealed in a contacting manner on a rotating component, such as, for example, a shaft, and the grounding element, the gap seal having a gap with a certain radial gap height, the gap seal ensuring protection of the grounding element from oil contamination, but nevertheless allowing a certain amount of oil or oil mist to penetrate from the elastic sealing ring in the direction of the grounding element. The radial gap height is preferably constant in the axial direction. If too much oil or oil mist reaches the grounding element, the electrical properties of the grounding element may be limited and thus the electrical grounding function of the grounding element may be affected. As a result, the oil or oil mist that passes through the elastic sealing ring in the direction of the first area to be sealed can always be used to extend the service life of the grounding element in an unexpected manner to a certain extent. In this case, the gap seal ensures that no excess oil or oil mist reaches the grounding element in the direction of the grounding element and could adversely affect its conductive properties, but that there is a slight contact lubrication with oil between the grounding element and the rotating component.

[0006] According to the invention, this is achieved in that the sealing device has an elastic annular sealing ring made of elastic material, the sealing ring having a first sealing flange and a second sealing flange, the first sealing flange and the second sealing flange being connected to each other by a connecting area extending substantially in the radial direction. The connecting area has a front side oriented in the direction of the oil-filled product area (second area) and a rear side on the opposite side, the rear side being oriented in the direction of the first area. The grounding element is arranged on the rear side of the connecting area and is configured to electrically connect the rotating component to the fixed housing component and thereby ensure potential equalization. The gap seal is arranged in the axial direction between the first sealing flange abutting against the rotating component and the grounding element, so that a first space is formed between the sealing ring and the gap seal to provide a collection space for oil or oil mist from the oil-filled area. The gap seal is thus configured to maintain a determined radial gap with the rotating component so that the discharged oil or oil mist is substantially kept away from the grounding element through the determined gap, and only a small part of the oil or oil mist is supplied to the grounding element through the determined gap. Thus, the main task of the gap seal is to keep oil or oil mist away from the grounding element. Thus, the gap seal can prevent the grounding element from being contaminated with oil, so that no functional limitation of the electrical properties of the grounding element occurs due to oil or oil mist. Nevertheless, a small amount of oil can be present on the grounding element in the contact area of ​​the grounding element and the rotating component, which is limited by the gap seal and does not significantly reduce the conductivity of the grounding element, but can reduce the friction between the grounding element and the rotating component during operation, thereby significantly reducing the wear of the grounding element.

[0007] The grounding element is preferably a conductive nonwoven fabric or a conductive element made of PTFE (polytetrafluoroethylene). Here, the conductive nonwoven fabric more preferably has no absorption properties.

[0008] The grounding element preferably has a substantially C-shaped or inverted C-shaped cross section. Thus, the grounding element can have a large contact surface on both the rotating component and the housing component for electrical contact with these components. Alternatively, the grounding element has an S-shaped or inverted S-shaped cross section.

[0009] The gap seal preferably comprises a disk made of an absorbent nonwoven material, on the inner radius of which the gap of the gap seal is formed. As a result, the gap seal itself can absorb oil, so that if too much oil passes through the sealing ring in the direction of the gap seal, this oil can be absorbed by the nonwoven material of the gap seal. If little or no oil reaches the gap seal in the direction of the gap seal in the operating state, this oil can also be released again. If not enough oil passes through the gap of the gap seal for lubrication on the grounding element, this (absorbed) oil can also be released in the direction of the grounding element.

[0010] The radial gap height of the gap of the gap seal is preferably in the range of 0.01 mm to 0.50 mm, in particular in the range of 0.10 mm to 0.40 mm, and further in particular in the range of 0.20 mm to 0.30 mm. The supply of oil to the grounding element is limited by this selection of the radial gap height. Thus, depending on the application, a larger or smaller gap of the gap seal can be predefined so that there is always a sufficient amount of oil for lubrication on the grounding element, but this amount of oil is so small that it does not adversely affect the electrical properties of the grounding element. It should be noted that the gap seal is preferably also designed so that there is a slight contact between the gap seal and the rotating component, because due to the eccentricity, in this design, a small radial gap between the gap seal and the rotating component is always formed during operation.

[0011] The gap seal is preferably fastened between the grounding element and the rear side of the connection region.

[0012] By means of the adhesive connection and / or the form-fit connection, the grounding element is fastened to the sealing ring in a particularly simple and economical manner. If only the form-fit connection is used, it is advantageous that the grounding element can be easily separated from the sealing ring.

[0013] In order to enable particularly reliable fixing of the grounding element, the sealing device preferably further comprises an electrically conductive metal sheet, with which the grounding element is fixed to the sealing ring.

[0014] According to an alternative design of the present invention, the gap seal comprises an elastomeric ring. The elastomeric ring of the gap seal and the sealing ring are preferably made of the same material and are integrally made.

[0015] According to another preferred design of the present invention, the gap seal comprises a sheet member, and the gap between the gap seal and the rotating component is formed on the inner circumference of the sheet member. The sheet member can be made of a flat material simply by forming. The sheet member more preferably also has a collecting groove facing away from the gap, and dirt particles or granules or the like can be collected in the collecting groove and thus cannot reach the grounding element and will not significantly reduce the conductivity.

[0016] Further preferably, the sheet metal part is L-shaped in cross section, thereby achieving a longer gap of the gap seal in the axial direction.

[0017] According to another preferred design of the present invention, an additional protective lip is also formed on the sealing ring, and the protective lip is arranged in the axial direction between the sealing contact portion between the sealing ring and the rotating component and the gap seal. Another collecting space is formed between the protective lip and the gap seal by the protective lip, and the oil that can enter the collecting space through the sealing contact portion with the rotating component can be contained in the other collecting space, thereby achieving further protection of the grounding element to prevent oil contamination. At this time, the protective lip has another gap relative to the rotating component, and the other gap allows oil to pass from the additionally formed collecting space toward the first space in a certain manner, and the first space now exists between the protective lip and the gap seal. The gap on the gap seal is preferably smaller than the other gap on the protective lip, and the protective lip is preferably formed integrally and from the same material as the sealing ring. The protective lip is preferably made of an elastomeric material at the same time as the manufacturing of the sealing ring.

[0018] The sealing ring is preferably made of a non-conductive material.

[0019] Furthermore, the present invention relates to an electrical device having a sealing device according to the present invention for grounding a rotating component on a housing component. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the accompanying drawings:

[0021] Figure 1 A schematic cross-sectional view showing a sealing device according to a first embodiment of the present invention,

[0022] Figure 2 A schematic cross-sectional view showing a sealing device according to a second embodiment of the present invention,

[0023] Figure 3 A schematic cross-sectional view showing a sealing device according to a third embodiment of the present invention,

[0024] Figure 4 A schematic cross-sectional view showing a sealing device according to a fourth embodiment of the present invention,

[0025] Figure 5 A schematic cross-sectional view showing a sealing device according to a fifth embodiment of the present invention,

[0026] Figure 6 A schematic cross-sectional view showing a sealing device according to a sixth embodiment of the present invention,

[0027] Figure 7 A schematic cross-sectional view showing a sealing device according to a seventh embodiment of the present invention, and

[0028] Figure 8 A schematic cross-sectional view shows a sealing device according to an eighth embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will refer to Figure 1 A sealing device 1 according to a preferred first embodiment of the present invention will be described in detail.

[0030] As Figure 1 As can be seen, the sealing device 1 comprises a sealing ring 2 which is made of an elastic material, preferably an elastomer.

[0031] The sealing ring 2 has an essentially C-shaped cross section with a first sealing bead 21 and a second sealing bead 22. The first sealing bead 21 is connected to the second sealing bead 22 via a connecting region 20 extending essentially in the radial direction.

[0032] The sealing device 1 seals a first region 11, for example an ambient region, from an oil-filled second region 12. The oil-filled second region 12 is, for example, an oil-filled chamber of an electric machine, the oil serving as a cooling medium for components of the electric machine.

[0033] The first sealing bead 21 and the second sealing bead 22 are oriented in the direction of the front side 23 of the sealing ring 2. In this case, the sealing ring 2 seals at a first sealing contact 25 on the rotating component 13, in particular on a shaft.

[0034] The second sealing contact 26 seals on the stationary housing component 14 .

[0035] The sealing ring 2 has a reinforcing sheet 6 for reinforcement, which in particular reinforces the second sealing bead 22. The annular spring 7 serves as a prestressing mechanism for prestressing the second sealing bead 22 so as to achieve a reliable seal at the first sealing contact portion 25.

[0036] In addition, the sealing device 1 further comprises a grounding element 3 for electrical grounding. The grounding element 3 is a member made of a conductive nonwoven material. The grounding element 3 is arranged on the rear side 24 of the connection area 20 and contacts the rotating member 13 at the radial inner end and contacts the fixed housing member 14 at the radial outer end.

[0037] As Figure 1 As can be seen, the grounding element 3 is configured with a substantially inverted C-shaped cross section. At the contact portion 31 with the rotating component, the grounding element 3 forms a kind of lip. At the contact portion 32 with the fixed housing component 14, the grounding element 3 forms a surface contact or alternatively a linear contact with the housing component.

[0038] In the axial direction XX, a gap seal 4 is arranged between the grounding element 3 and the first sealing contact 25 of the sealing ring 2 on the rotating component 13. The gap seal 4 is preferably made of an absorbent nonwoven fabric. Here, the absorbent nonwoven fabric does not have to be electrically conductive.

[0039] The gap seal 4 has an annular shape and is fixed to the sealing ring 2, so that a radial gap 5 exists between the radial inner end of the gap seal 4 and the rotating component 13. Here, the gap height of the gap 5 can be determined by selecting the inner diameter of the gap seal 4.

[0040] A first adhesive connection 8 is formed between grounding element 3 and gap seal 4, so that grounding element 3 is bonded to gap seal 4. A second adhesive connection 9 is provided between gap seal 4 and sealing ring 2, so that annular gap seal 4 is bonded to connection region 20 of sealing ring 2.

[0041] As Figure 1 As can be seen, the gap seal 4 divides an area on the rotating component 13 into a first space 15 between the sealing ring 2 and the gap seal and a second space 16 between the gap seal 4 and the contact element 3 .

[0042] The first space 15 now serves as a collecting space for oil or oil mist, which can pass through the first sealing contact 25 in the direction of the gap seal 4. As a result, the oil or oil mist is kept away from the grounding element 3, so that oil contamination of the grounding element 3 can be avoided and the grounding element 3 retains its electrical properties, in particular its electrical conductivity.

[0043] The gap seal 4 is now arranged to maintain the gap 5 to the rotating component 13, so that the grounding element 3 can also be supplied with oil or oil mist that can enter the first space 15 between the sealing ring 2 and the gap seal 4 via the first sealing contact 25 in a defined manner. In particular, the amount of supply can be defined by selecting the height of the gap 5. As a result, the tribological contact between the grounding element 3 and the rotating component 13 can be supplied with oil to a defined extent, so that the friction between the grounding element 3 and the rotating component 13 is minimized. Here, the amount of oil allowed to pass through by the gap seal is so small that it does not affect the electrical contact properties of the grounding element 3 relative to the rotating component 13.

[0044] Since the gap seal 4 is made of an absorbent nonwoven fabric, excess oil that enters the first space 15 can be absorbed by the gap seal 4 and there is a risk that this excess oil may enter the second space 16 via the gap 5 .

[0045] If during operation an operating situation arises in which oil is conveyed back from the first chamber 15 via the sealing ring 2 into the oil-filled second region 12 , the gap seal 4 can also release the oil again and this oil can be conveyed via the first sealing contact 25 into the second region 12 .

[0046] Depending on the respective operating conditions, it should be noted that the sealing ring 2 can indeed provide a reliable seal on the rotating component 13 during operation, so that no appreciable amount of oil can enter the first space 15 via the first sealing contact 25 .

[0047] However, there is a form of uncontrolled evaporation of gap fluid (oil mist) during operation, which can enter the first space 15 via the first sealing contact 25. However, due to the electrical insulation properties of oil and the deposition of oil components on the rotating components in dynamic contact in the tribological friction contact, if too much evaporated oil can reach the grounding element 3, this leakage, which is usually not noticeable during operation, will affect the electrical connection between the grounding element 3 and the rotating component 13.

[0048] Now, by providing the gap seal 4 with a defined gap 5, the present invention can ensure that only an amount of oil that is not detrimental to the electrical properties of the grounding element 3 can reach the grounding element 3. The oil supplied to the grounding element 3 in a defined amount on the grounding element 3 also provides reduced friction between the grounding element 3 and the rotating component 13, so that the service life of the grounding element 3 can be significantly extended.

[0049] If too much evaporated oil is able to pass through the first sealing contact 25, the gap seal 4 serves as a safety element which can additionally absorb excess oil or excess oil mist. Thus, in addition to the main function of protecting the grounding element 3, the gap seal 4 also has the function of a defined supply of oil to the grounding element 3. Lubricant metering can thus be achieved, so that the grounding element 3 is supplied with just such an amount of oil that no excessive wear occurs on the grounding element 3 at the contact 31 during operation.

[0050] Reference below Figures 2 to 8 Other preferred embodiments of the present invention are described, wherein the same components are denoted by the same reference numerals.

[0051] Figure 2 A second embodiment of the sealing device 1 is shown. Different from the first embodiment, in the second embodiment, a larger first space 15 and a second space 16 are formed by the geometric shape of the reinforcing sheet 6 so as to collect a larger amount of oil. Figure 2 As shown, the reinforcing plate 6 has a first side leg 6a, a second side leg 6b and a bottom area 6c. As a result, additional space is obtained radially inside the sealing ring 2, so that the first space 15 and the second space 16 can be respectively formed with a large volume. Figure 2 As can be seen, the gap seal 4 is arranged radially inside the two side legs 6a, 6b of the reinforcement plate. The gap seal is made of an absorbent nonwoven material. The grounding element 3 is also made of a nonwoven fabric, but of an electrically conductive nonwoven material that does not have an excessively absorbent function, so that the nonwoven fabric of the grounding element 3 does not absorb too much oil. Figure 2 The radial end region 3a is also shown by dashed lines. Figure 2 As shown in FIG, the shaft 13 is inserted in the assembly direction M, so that the radial end region 3 a of the grounding element is deformed accordingly. As a result, in particular, the radial end region 3 a of the grounding element does not protrude in the direction of the first region 11 .

[0052] exist Figure 3 In the third exemplary embodiment shown in FIG, a positive connection 17 is provided between the gap seal 4 and the sealing ring 2. The sealing ring 2 here has a protruding ring, preferably with an undercut, on which the gap seal 4 is fixed and centered in a positively locking manner. Instead of a circumferential ring, a plurality of individual button-like projections can also be provided on the sealing ring 2. In this case, the grounding element 3 is also fixed to the gap seal 4 by means of a first adhesive connection 8.

[0053] Figure 4 A sealing device 1 according to a fourth embodiment of the invention is shown. As in the third embodiment, a thickening 2a is provided on the back side 24 of the sealing ring, which covers the grounding element 3 and the gap seal 4 in the radial direction. In order to fix the grounding element 3, a metal sheet 18 is provided, which fixes the grounding element 3 and the gap seal 4 on the sealing ring 2. This can also be reinforced by an adhesive connection. Here, the metal sheet 18 provides an electrical connection between the grounding element 3 and the fixed housing component 14. This embodiment requires less non-woven material for the grounding element 3 and the gap seal 4.

[0054] exist Figure 5 In the fifth embodiment shown in , the gap seal 4 includes an elastomeric ring 4a, which defines a gap 5 between the gap seal 4 and the rotating component 13. The elastomeric ring 4a can be a separate component and fixed on the sealing ring 2, or alternatively, the elastomeric ring 4a is integrally formed with the sealing ring 2.

[0055] Figure 6 and 7 The sixth and seventh embodiments of the present invention are shown, in which the gap seal 4 comprises a sheet member 40. Figure 6As can be seen, the sheet element 40 has a substantially L-shaped shape and provides a collecting groove 41. Thus, oil or oil mist can be collected and intercepted in the collecting groove 41 and does not reach the grounding element 3. The sheet element 40 is preferably connected to the sealing ring 2 and the grounding element 3 by an adhesive connection.

[0056] exist Figure 7 The seventh embodiment shown in the figure corresponds substantially to the sixth embodiment, wherein the sheet member 40 further comprises a bent portion 42. Thus, the volume of the first space 15 and the second space 16 can be adjusted in a simple manner according to the application (see Figure 7 ).

[0057] Figure 8 An eighth embodiment of the sealing device is shown which corresponds substantially to the first embodiment. In contrast to the first embodiment, a protective lip 19 is additionally provided in the eighth embodiment. The protective lip 19 is arranged on the sealing ring 2 and forms a further gap 5a together with the rotating component. Figure 8 As can be seen directly, a further collecting space 15a for oil or oil mist is formed by providing the protective lip 19. Thus, a total of three spaces are present in series starting from the first sealing contact 25 to the grounding element 3. The further collecting space 15a is arranged in the axial direction between the first sealing contact 25 and the protective lip 19. The first space 15 is formed in the axial direction between the protective lip 19 and the gap seal 4. The second space 16 is formed in the axial direction between the gap seal 4 and the grounding element 3.

[0058] Here, the radial gap height of the further gap 5a in the protective lip 19 is greater than the radial gap height of the gap 5 on the gap seal 4. Figure 8 In the embodiment shown in , two gap seals are arranged in series on the rotating component. This achieves a significantly improved interception of oil and oil mist in the direction of the grounding element. The protective lip 19 is made of the same material as the sealing ring 2 and is preferably formed integrally with the sealing ring. This achieves a further improved protection of the grounding element 3 against oil contamination without significantly increasing the production costs of the sealing ring 2.

Claims

1. A sealing device for sealing a first area (11) with a second area (12) filled with oil on a rotating component (13), the sealing device comprising: a sealing ring (2) made of an elastic material, comprising a first sealing bead (21), a second sealing bead (22) and a connecting region (20) which connects the first sealing bead (21) to the second sealing bead (22) and has a front side (23) oriented toward the second region (12), a grounding element (3) which is arranged on the rear side (24) of the connection region (20) and is provided for electrically connecting the rotating component (13) to a fixed housing component (14), and a gap seal (4) arranged in the axial direction (XX) between a sealing contact (25) of the first sealing flange (21) on the rotating component (13) and the grounding element (3), so that a first space (15) is formed between the sealing ring (2) and the gap seal (4) in order to provide a collecting space for oil or oil mist from the oil-filled area (12), - wherein the gap seal (4) is arranged to maintain a gap (5) with the rotating component (13) in order to ensure, on the one hand, protection of the grounding element against oil contamination and, on the other hand, to supply oil or oil mist to the grounding element (3) in a determined manner according to the gap height of the gap (5) in order to achieve contact lubrication between the grounding element (3) and the rotating component (13) without functional restrictions on the electrical properties of the grounding element (3).

2. The sealing device according to claim 1, wherein: The grounding element (3) has a substantially C-shaped cross section or an inverted C-shaped cross section.

3. A sealing device according to any one of the preceding claims, wherein: The gap seal (4) comprises a disk made of an absorbent nonwoven material, on the inner radius of which the gap (5) is formed.

4. A sealing device according to any one of the preceding claims, wherein: An overlap (10) is formed between the grounding element (3) and the gap seal (4) on the inner circumference of the grounding element (3) and is present in the radial direction.

5. A sealing device according to any one of the preceding claims, wherein: The radial gap height of the gap (5) is in the range of 0.01 mm to 0.50 mm.

6. A sealing device according to any one of the preceding claims, wherein: The gap seal (4) is fixed between the grounding element (3) and the back side (24) of the connection region (20).

7. A sealing device according to any one of the preceding claims, wherein: An adhesive bond and / or a form-fitting connection is formed between the grounding element (3) and the gap seal (4) and / or between the gap seal (4) and the sealing ring (2).

8. The sealing device according to any one of the preceding claims, further comprising a metal sheet (18) for fixing the grounding element (3) on the sealing ring (2).

9. A sealing device according to any one of the preceding claims, wherein: The gap seal (4) comprises an elastomeric ring (4a) which is integral with the sealing ring (2) or is fixed to the sealing ring (2) as a separate component.

10. A sealing device according to any one of the preceding claims, wherein: The gap seal (4) further includes a sheet member (40), and the gap (5) with the rotating member (13) is formed on the inner periphery of the sheet member (40).

11. The sealing device according to claim 10, wherein: The sheet element (40) has a collecting groove (41) and / or the sheet element is L-shaped in cross section.

12. A sealing device according to any one of the preceding claims, wherein: A protective lip (19) is formed on the sealing ring (2), and the protective lip is arranged between the sealing contact portion (25) and the gap seal (4) in the axial direction (XX), so that another collecting space (15a) is formed between the protective lip (19) and the gap seal, and another gap (5a) is present between the protective lip (19) and the rotating component.

13. A sealing device according to any one of the preceding claims, wherein: The gap (5) on the gap seal (4) is smaller than the other gap (5a) on the protective lip (19).

14. A sealing device according to any one of the preceding claims, wherein: The sealing ring (2) is made of a non-conductive material.

15. Electrical device, in particular an oil-cooled electric machine, comprising a sealing device according to any of the preceding claims.

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