shaft sealing arrangement

Abstract

The invention relates to a shaft sealing arrangement (100) for sealing a shaft (80) against a housing (90), comprising a shaft seal (10) rigidly connected to the housing (90), an outer shell (12), and a sealing lip (14) connected to the outer shell (12), which is directed radially outwards at an axial end directed towards an interior (91) of the housing (90), wherein a circumferential spring element (18) is arranged between the outer shell (12) and the sealing lip (14), which bears against the sealing lip (14), and wherein a sealing lip limiting element (20) is arranged between the outer shell (12) and the spring element (18). According to the invention, the sealing lip limiting element (20) is connected directly or indirectly to the outer shell (12).

Description

[0001] The invention relates to a shaft sealing arrangement for sealing a shaft against a housing.

[0002] Conventional spring-loaded sealing rings in motor vehicles often leak when installed in the intended direction when a vacuum is applied. This is due to the lifting of the sealing lip. Reversing the sealing ring would resolve this problem, but this would increase the contact pressure of the sealing lip, leading to increased wear and higher friction losses. Furthermore, the function of a dust lip, which protects against external influences, is no longer fulfilled.

[0003] EP 3 032 148 B1 discloses an axial shaft seal for sealing a shaft against a housing, comprising a stiffening section and a sealing element connected to the stiffening section, said sealing element having a sealing lip configured for sealing interaction with a radially extending counter-rotating element connectable to the shaft. In the assembled state, sealing contact exists exclusively between an end region of the sealing lip and the radial counter-rotating element. On the side facing the counter-rotating element, a plurality of channels are arranged around the circumference of the sealing lip, or alternatively on the counter-rotating surface, in which channels a pressure buildup is caused when the shaft rotates.

[0004] From US 37 46 351 A a shaft sealing unit is known, comprising a housing element with a mounting flange portion for mounting the shaft sealing unit in a machine and an elastic sealing element with a sealing lip for sealing a region of a shaft relative to the machine, wherein the sealing element has a circumferentially extending, radially acting annular spring, and wherein the housing element has a spring holding portion which extends substantially axially and is spaced radially from the annular spring when the shaft is installed.

[0005] From DE 10 2013 200 216 A1 a radial shaft seal is known with a sealing lip which extends in the circumferential direction and is encompassed by a worm spring, wherein the worm spring rests against a retaining lip.

[0006] An object of the invention is to provide an improved shaft sealing arrangement for sealing a shaft against a housing.

[0007] The above-mentioned problem is solved by the features of the independent claim.

[0008] Advantageous embodiments and advantages of the invention emerge from the further claims, the description and the drawing.

[0009] The invention is based on a shaft sealing arrangement for sealing a shaft against a housing, comprising a shaft sealing ring firmly connected to the housing, comprising an outer casing and a sealing lip connected to the outer casing, which is directed radially outward at an axial end directed toward an interior of the housing. A circumferential spring element is arranged between the outer casing and the sealing lip, which rests against the sealing lip. A sealing lip limiting element is arranged between the outer casing and the spring element.

[0010] According to the invention, the sealing lip limiting element is connected directly or indirectly to the outer casing.

[0011] In particular, the sealing lip limiting element can be firmly connected directly or indirectly to the outer casing.

[0012] In the proposed shaft sealing arrangement, the inclusion of a radial sealing lip limiting element prevents the sealing lip from lifting due to negative pressure in the interior of the housing. This keeps the designed preload constant. If an overpressure develops in the interior of the housing, however, the sealing lip is pressed somewhat more tightly, but its sealing effect and function are not lost.

[0013] The sealing lip limiting element can be positioned directly against the outer casing. Alternatively, it is also possible for the sealing lip limiting element to be arranged indirectly on the outer casing, for example, by being connected to the outer casing via a stiffening element.

[0014] This one-piece concept, with a sealing lip limiting element integrated into the shaft sealing assembly, is more cost-effective and advantageously enables faster and more tolerance-friendly assembly. Furthermore, the shaft sealing assembly exhibits a lower risk of functional failure due to a lack of preload. In the presence of negative pressure in the housing, there is no increase in friction loss.

[0015] The proposed shaft sealing arrangement can be advantageously used in an electric drive train for driving a predominantly or exclusively electrically powered vehicle.

[0016] Furthermore, the shaft sealing arrangement can be used advantageously in other applications in which a shaft must be sealed against an interior space containing the medium to be sealed, which may have a variable pressure.

[0017] According to an advantageous embodiment of the shaft sealing arrangement, a sealing surface of the sealing lip can extend radially inward and interact directly with a surface of the shaft as a sealing partner. The shaft sealing arrangement enables a simple design of the overall assembly and thus reduces the susceptibility to errors due to the use of series tolerances or tolerances arising over service life due to wear.

[0018] According to an advantageous embodiment of the shaft sealing arrangement, the spring element can be designed as a spiral spring. Such a spring element can promote uniform pressing of the sealing lip against the shaft to be sealed.

[0019] A radial distance between an outer peripheral surface of the spring element and an inner peripheral surface of the sealing lip limiting element corresponds, in a relaxed initial state, to a radial oversize of the sealing lip for a preload between the sealing lip and the shaft in an installed state. Thus, the radial distance can advantageously be approximately equal to the radial oversize of the sealing lip, enabling reliable sealing of the shaft.

[0020] According to an advantageous embodiment of the shaft sealing arrangement, a stiffening element can be arranged radially within the outer casing, wherein the sealing lip limiting element can be arranged radially within the stiffening element. In particular, the stiffening element can be embedded at least partially in the outer casing. The stiffening element can enable stable mounting of the sealing lip limiting element in the shaft sealing ring.

[0021] According to an advantageous embodiment of the shaft sealing arrangement, the sealing lip can be connected to the stiffening element in a radially inward direction. This allows the sealing lip to maintain a stable position during assembly of the shaft sealing ring.

[0022] According to an advantageous embodiment of the shaft sealing arrangement, the sealing lip limiting element can be pressed into the stiffening element. In this way, the sealing lip limiting element can be stably held in the shaft sealing ring.

[0023] According to an advantageous embodiment of the shaft sealing arrangement, the sealing lip can have a dust lip extending radially inward. The dust lip can advantageously protect against external environmental influences.

[0024] According to an advantageous embodiment of the shaft sealing arrangement, the sealing lip limiting element can have at least one pressure equalization opening, in particular a plurality, in particular at least four, pressure equalization openings arranged in a radial section of the sealing lip limiting element. Pressure equalization openings in the radial sealing lip limiting element can advantageously ensure a homogeneous pressure distribution on the inside of the sealing lip and thus enable the drainage of, for example, oil.

[0025] According to an advantageous embodiment of the shaft sealing arrangement, the pressure equalization openings can be evenly distributed over a circumference of the sealing lip limiting element. In particular, the pressure equalization openings can be arranged symmetrically on the circumference of the sealing lip limiting element. This allows for favorable pressure equalization through the sealing lip limiting element.

[0026] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an exemplary embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0027] Showing: Fig. 1 a plan view of a shaft sealing arrangement for sealing a shaft against a housing, according to an embodiment of the invention, in the initial state; Fig. 2 a plan view of the shaft sealing arrangement in the installed state; and Fig. 3 a longitudinal section through the shaft sealing arrangement in the initial state; Fig. 4 a longitudinal section through the shaft sealing arrangement in the installed state.

[0028] In the figures, identical or similar components are numbered with the same reference numerals. The figures show only examples and are not to be understood as limiting.

[0029] Fig. 1 shows a plan view of a shaft sealing arrangement 100 for sealing a shaft 80 against a housing 90, according to an embodiment of the invention, in the initial state 1, while in Fig. 2 the shaft sealing arrangement 100 is shown in the installed state 2 on the shaft 80.

[0030] Fig. 3 shows a longitudinal section through the shaft sealing arrangement 100 in the initial state 1, while in Fig. 4 the shaft sealing arrangement 100 is shown in installed state 2 with the shaft 80 adjacent.

[0031] The shaft sealing arrangement 100 has a shaft sealing ring 10 that is firmly connected to the housing 90. The shaft sealing ring 10 comprises an outer casing 12 and a sealing lip 14 that is connected to the outer casing 12 and that is directed radially outward at an axial end directed toward an interior space 91 of the housing 90. A circumferential spring element 18, in the Fig. 3 and Fig. 4, is arranged between the outer casing 12 and the sealing lip 14. The spring element 18, which can be a spiral spring, for example, rests against the sealing lip 14.

[0032] The outer shell 12 with the sealing lip 14 can preferably be made of rubber such as a fluororubber monomer (FKM).

[0033] A sealing lip limiting element 20 is arranged between the outer casing 12 and the spring element 18. The sealing lip limiting element 20 is connected directly or indirectly to the outer casing 12, in particular fixedly.

[0034] The sealing lip limiting element 20 can be made of a metal, preferably steel.

[0035] In the illustrated embodiment, a stiffening element 30 is arranged radially within the outer shell 12, and the sealing lip limiting element 20 is arranged radially within the stiffening element 30. The sealing lip limiting element 20 can, for example, be pressed into the stiffening element 30.

[0036] The stiffening element 30 can be made of a metal, preferably steel.

[0037] The stiffening element 30 can be embedded at least in part in the outer shell 12, for example, cast in during the manufacture of the outer shell.

[0038] The sealing lip 14 is connected to the stiffening element 30 in the radial inward direction.

[0039] As in the Fig. 3 and Fig. 4, a sealing surface 16 of the sealing lip 14 extends in a radial direction inwards and interacts directly with a surface 82 of the shaft 80 as a sealing partner.

[0040] As in Fig. 1 and Fig. 2 or in Fig. 3 and Fig. 4 with dashed lines, a radial distance 22 between an outer circumferential surface 19 of the spring element 18 and an inner circumferential surface 23 of the sealing lip limiting element 20 in a relaxed initial state 1 corresponds to a radial oversize 24 of the sealing lip 14 for a preload between the sealing lip 14 and the shaft 80 in an installed state 2. Due to the elasticity of the sealing lip 14, it is sufficient if the radial distance 22 is approximately the same size as the radial oversize 24 of the sealing lip 14.

[0041] The dashed lines are from Fig. 1 after Fig. 2 or from Fig. 3 after Fig. 4 to illustrate the changes of the shaft seal 10 from the initial state 1 to the installed state 2.

[0042] In the longitudinal sections in the Fig. 3 and Fig. 4 also shows the dust lip 26 extending radially inwards, which is part of the sealing lip 14.

[0043] The sealing lip limiting element 20 has four pressure equalization openings 28, which are arranged in a radial section 21 of the sealing lip limiting element 20. The pressure equalization openings 28 are distributed evenly, in particular symmetrically, over the circumference of the sealing lip limiting element 20.

[0044] As shown in the longitudinal section in Fig. As can be seen in Figure 4, when the shaft seal 10 is mounted on the shaft 80, the sealing lip 14 is pressed against the sealing lip limiting element 20 by the spring element 18. The sealing surface 16 of the sealing lip 14 rests against the surface 82 of the shaft 80 and seals reliably. The dust lip 26 prevents dirt from the environment from penetrating the interior 91 of the housing 90.

[0045] The radial sealing lip limiting element 20 thus prevents the sealing lip 14 from lifting due to a negative pressure in the interior 91 of the housing 90. As a result, the designed preload of the sealing lip 14 remains constant. However, if an overpressure develops in the interior 91 of the housing 90, the sealing lip 14 is pressed somewhat more tightly, but does not lose its sealing effect and function. List of reference symbols 1 Initial state 2 Installation condition 10 Shaft seal 12 Outer jacket 14 Sealing lip 16 Sealing surface 18 spring element 19 Outer peripheral surface 20 Sealing lip limiting element 21 radial section 22 radial distance 23 inner circumferential surface 24 radial oversize 26 Dust lip 28 Pressure equalization opening 30 stiffening element 80 wave 82 Surface 90 housings 91 Interior 100 shaft sealing arrangement

Claims

[1] Shaft sealing arrangement (100) for sealing a shaft (80) against a housing (90), with a shaft sealing ring (10) firmly connected to the housing (90), comprising an outer casing (12) and a sealing lip (14) connected to the outer casing (12), which sealing lip is directed radially outwards at an axial end directed towards an interior space (91) of the housing (90), wherein a circumferential spring element (18) is arranged between the outer casing (12) and the sealing lip (14), which rests against the sealing lip (14), wherein a sealing lip limiting element (20) is arranged between the outer casing (12) and the spring element (18), characterized bythat the sealing lip limiting element (20) is connected directly or indirectly to the outer casing (12), that a radial distance (22) between an outer circumferential surface (19) of the spring element (18) and an inner circumferential surface (23) of the sealing lip limiting element (20) in a relaxed initial state (1) corresponds to a radial oversize (24) of the sealing lip (14) for a preload between the sealing lip (14) and the shaft (80) in an installed state (2), and that in the installed state (2) the sealing lip (14) is pressed with the spring element (18) against the sealing lip limiting element (20). [2] Shaft sealing arrangement according to claim 1, wherein a sealing surface (16) of the sealing lip (14) extends inwardly in a radial direction and cooperates directly with a surface (82) of the shaft (80) as a sealing partner. [3] Shaft sealing arrangement according to claim 1 or 2, wherein the spring element (18) is designed as a spiral spring. [4] Shaft sealing arrangement according to one of the preceding claims, wherein a stiffening element (30) is arranged radially inside the outer casing (12), wherein the sealing lip limiting element (20) is arranged radially inside the stiffening element (30), in particular wherein the stiffening element (30) is at least partially embedded in the outer casing (12). [5] Shaft sealing arrangement according to claim 4, wherein the sealing lip (14) is connected to the stiffening element (30) in the radially inward direction. [6] Shaft sealing arrangement according to claim 4 or 5, wherein the sealing lip limiting element (20) is pressed into the stiffening element (30). [7] Shaft sealing arrangement according to one of the preceding claims, wherein the sealing lip (14) has a dust lip (26) extending inwardly in the radial direction. [8] Shaft sealing arrangement according to one of the preceding claims, wherein the sealing lip limiting element (20) has at least one pressure equalization opening (28), in particular a plurality, in particular at least four, pressure equalization openings (28) which are arranged in a radial section (21) of the sealing lip limiting element (20). [9] Shaft sealing arrangement according to claim 8, wherein the pressure equalization openings (28) are evenly distributed over a circumference of the sealing lip limiting element (20), in particular wherein the pressure equalization openings (28) are arranged symmetrically on the circumference of the sealing lip limiting element (20).

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