Sealing arrangement for a rolling bearing and rolling bearing with such a sealing arrangement

Abstract

The invention relates to a sealing arrangement (1) of a rolling bearing (2, 3) of a pedal crankshaft (31) of an electrically driven two-wheeler, wherein a first angle ring (4) for fastening to the bearing outer ring (6) and a second angle ring (5) for fastening to the bearing inner ring (7) are arranged in such a way that they delimit an annular sealing space (16) in the form of an annular sealing cassette (17), and an axial dynamic seal (18) is arranged in the sealing space (16), and two radial sealing gaps (22, 23) are formed between the angle rings (4, 5), wherein the sealing cassette (17) has a radial height (h) corresponding to the distance between the outer diameter of the first angle ring (4) and the inner diameter of the second angle ring (5) of less than 3.2 mm and an axial width (b) corresponding to the axial distance between the mutually facing axial outer sides (21, 24) of the angle rings (4, 5) is less than 1.6 mm.

Description

The invention relates to a sealing arrangement for a rolling bearing. The invention further relates to a rolling bearing with such a sealing arrangement. The invention further relates to a pedal bearing arrangement for supporting a pedal crankshaft of an electrically drivable two-wheeler having at least one such rolling bearing.DE 10 2015 216 168 B3 discloses a bottom bracket arrangement for a bicycle. There are provided rolling bearings arranged axially spaced apart from one another, which are fastened to the bicycle frame in each case by rolling bearing outer rings. A pedal shaft is inserted into the rolling bearing inner rings. Towards an end face of the rolling bearing, an additional outer sealing ring disk is arranged between the rolling bearing outer ring and the rolling bearing inner ring.The object of the invention is therefore to propose a sealing arrangement, a rolling bearing and a bottom bracket bearing arrangement of the aforementioned type, which ensure a high degree of sealing with a small installation space requirement and are simple to mount.The object is achieved by the features of claim 1 and alternatively by the features of claims 7 or 10. Further advantageous and claimed embodiments are evident from the respective dependent claims, the description and the drawings.Thus, a sealing arrangement for a rolling bearing is proposed, wherein a first angle ring for fastening to the bearing outer ring and a second angle ring for fastening to the bearing inner ring are arranged in such a way that they delimit an annular sealing space in the form of an annular sealing cassette and an axial dynamic seal is arranged in the sealing space and two radial sealing gaps are formed between the angle rings. The sealing cassette has a radial structural height corresponding to the distance between the outer diameter of the first angle ring and the inner diameter of the second angle ring of less than 3.2 mm and an axial structural width corresponding to the axial distance of the mutually remote axial outer sides of the angle rings of less than 1.6 mm.The double labyrinth effect at the very narrow sealing gaps achieves a high degree of sealing. In addition, the sealing space delimited by the sealing cassette is protected from direct contact by water under spray and pressurized conditions, with the result that the dynamic seal arranged in the sealing space ensures a high additional seal. Accordingly, the proposed seal arrangement forms a high-performance seal as a cassette seal, which, owing to its small overall height and width, requires a particularly small installation space requirement and enables use in a thin-ring bearing. In addition, the sealing cassette can be easily mounted, in particular by pressing, with the outer diameter of the first angle ring on the inner diameter of the bearing outer ring and with the inner diameter of the second angle ring on the outer diameter of the bearing inner ring.The sealing effect can preferably be further increased in that the radial sealing gaps each have a reduced radial gap dimension of 0.3 mm or less than 0.3 mm.In a preferred embodiment of the invention, the sealing cassette can be fastened particularly easily, preferably by pressing, with the outer diameter of an axial limb of the first angle ring extending in the axial direction on the inner diameter of the bearing outer ring and with the inner diameter of an axial limb of the second angle ring extending in the axial direction on the outer diameter of the bearing inner ring.In a next development of the invention, a first radial sealing gap is provided between the axial limb of the first angle ring and the free end of the radially outwardly extending radial limb of the second angle ring. Preferably, a second radial sealing gap is formed between the free end of a radially inwardly extending radial leg of the first angle ring and the axial leg of the second angle ring. In this way, at the first sealing gap, the sealing cassette can be sealed on the outside to the environment and the penetration of dirt and splash and pressurized water into the sealing space can be prevented. At the second radial sealing gap, the rolling bearing can be further sealed off from the bearing interior, so that the rolling bearing is sealed off from the environment by a double labyrinth effect. In addition, the radial leg of the second angle ring can at the same time form a centrifugal disk, by means of which dirt and water can be centrifuged off by centrifugal force action by rotation.The dynamic seal can be integrated in a simple manner in a space-saving manner into the sealing space of the sealing cassette, preferably as a sealing lip which, starting from the radial limb of the first angle ring, extends in axial sealing contact with an axial sealing surface on the radial limb of the second angle ring.For simple fastening of the dynamic seal to the radial leg of the first angle ring, the free end of the latter is offset with reduced wall thickness on the axial sides in a tapering manner, so that the dynamic seal can be fastened on both axial sides of the free end in a manner which saves particularly space and is firmly connected thereto, preferably as an elastomer seal by vulcanizing or injection molding on said free end.The object according to the invention is also achieved by a rolling bearing having a sealing arrangement described above. It is provided here that the sealing arrangement is arranged with a sealing cassette for sealing the radial bearing gap formed between the bearing rings. This achieves the advantages already mentioned above.In addition, the rolling bearing can be implemented in a simple manner as a thin-ring bearing with a small axial bearing overall width and a small radial overall height with a sealing cassette as a one-sided high-performance seal to the environment.The axial bearing width is preferably 7 mm or is less than 7 mm.The rolling bearing preferably has a radial overall height as a radial distance between the inner diameter of the bearing inner ring and the outer diameter of the bearing outer ring of 13 mm or less than 13 mm.Preferably, for further saving installation space, the bearing inner ring is designed with a reduced radial wall thickness of less than 1.2 mm in the region of the fastening of the sealing cassette.Alternatively, it is conceivable to design the bearing outer ring in the region of the fastening of the sealing cassette with a reduced radial wall thickness of less than 1.2 mm.In a further preferred embodiment of the proposed rolling bearing, a sealing ring for sealing the bearing seat on a stationary component, in particular a housing, is arranged on the outer diameter of the bearing outer ring in a radial depression, and the bearing outer ring is designed with a radial wall thickness of less than 1.2 mm in the region of the depression. Preferably, the depression with the sealing ring is arranged in a central region situated between the axial ends of the bearing outer ring at the level of the rolling body raceway formed on the inner diameter of the bearing outer ring.Consequently, the rolling bearing can be designed with an additional seal on the bearing outer ring for sealing off the bearing seat of the rolling bearing without requiring additional installation space.In a further particularly space-saving advantageous manner, balls having a reduced ball diameter of 3.5 mm or less than 3.5 mm are provided as rolling bodies.It is furthermore particularly advantageous if a rolling body cage for guiding the rolling bodies is arranged in such a way that a smallest possible radial gap with a gap width of 0.5 mm or less than 0.5 mm is established between the rolling body cage with respect to the inner diameter of the bearing outer ring and with respect to the outer diameter of the bearing inner ring. As a result, a shielding effect is achieved on the axial inner side of the rolling bearing facing the interior to be sealed, in order to avoid the penetration of dirt particles from the interior. At the same time, the escape of grease from the rolling bearing can be avoided.The rolling bearing described above can be configured with further features from the description of the seal arrangement described at the beginning.The object according to the invention is also achieved, in addition, by a bottom bracket bearing arrangement for supporting a crank shaft of an electrically drivable two-wheeler, having at least one rolling bearing described above. This achieves the advantages already mentioned above. The bottom bracket bearing arrangement can be designed with further features from the description of the rolling bearing described above and the sealing arrangement described at the beginning.Further claimed features of the invention will become apparent from the following description and from the drawings, on the basis of which the present invention is explained further. The following are shown: FIG. 1 shows a sealing arrangement according to the invention for a rolling bearing, FIG. 2 shows an enlarged detail from FIG. 1, FIG. 3 shows a sectional view of the rolling bearing with the sealing arrangement, FIG. 4 shows a perspective view of the rolling bearing with the sealing arrangement, FIG. 5 shows a bottom bracket arrangement according to the invention for an electrically drivable two-wheeler, FIG. 6 shows a perspective sectional view of the bottom bracket arrangement.The figures show various views of a sealing arrangement 1 according to the invention for a rolling bearing 2, 3 and of a rolling bearing 2, 3 according to the invention with such a sealing arrangement 1 by way of example. The figures furthermore show, by way of example, a pedal bearing arrangement according to the invention for mounting a pedal crankshaft 31 of an electrically drivable two-wheeler, in particular a so-called e-bike or a so-called pedelec.According to FIG. 1, the sealing arrangement 1 has two metallic angle rings 4, 5 embodied in sheet metal. As shown in FIGS. 1 and 2, it is arranged in a rolling bearing 2, 3 with a radial bearing gap S formed between the outer and inner rings 6, 7 to seal it from the environment. The outer and inner rings 6, 7 are arranged coaxially to the bearing axis 28.The angle rings 4, 5 are each formed with two legs 8, 9 and 10, 11 which are each arranged at right angles to one another in cross section in L shape. For fastening to the bearing outer ring 6, a first angle ring 4 has an axial leg 6 extending with a free end 12 in the axially outer direction and a radial leg 9 extending with a free end 13 in the radially inner direction. For fastening to the bearing inner ring 7, a second angle ring 5 has an axial leg 6 extending with a free end 14 in the axially inner direction and a radial leg 9 extending with a free end 15 in the radially inner direction.The angle rings 4, 5 are arranged in such a way that their legs 8, 9 and 10, 11 delimit between them an annular sealing space 16 in the form of an annular sealing cassette 17. The sealing cassette 17 is thus axially pressed in with the outer diameter on the outer circumference of the axial limb 8 of the first angle ring 4 on the inner diameter thus on the inner circumference of a bearing shoulder 19 of the bearing outer ring 6 and with the inner diameter thus on the inner circumference of the axial limb 10 of the second angle ring 5 on the outer diameter thus on the outer circumference of a bearing shoulder 20 of the bearing inner ring 7.With the axial outer side 21 of the radial leg 11 of the second angle ring 5 facing the environment, it forms a centrifugal disk, by means of which dirt and water can be centrifuged off from the environment during rotation by the centrifugal forces that are generated.The angle rings 4, 5 form two radial sealing gaps 22, 23 with respect to one another. A first radial sealing gap 22 is formed between the axial leg 8 of the first angle ring 4 and the free end 15 of the radial leg 11 of the second angle ring 5. A second radial sealing gap 23 is formed between the free end 13 of the radial leg 9 of the first angle ring 4 and the axial leg 10 of the second angle ring 5. The first sealing gap 22 seals the sealing cassette 17 on the outside to the environment and prevents dirt and splash and pressurized water from entering the sealing space. The second radial sealing gap 23 seals the rolling bearing 2 further toward the bearing interior, so that the rolling bearing 2, 3 is additionally sealed from the environment by a double labyrinth effect.An axial dynamic seal 18 is arranged in the sealing space 16 delimited by the sealing cassette 17. This sealing lip is preferably formed as an axial sealing lip made of elastomer, which, starting from the radial limb 9 of the first angle ring 4, extends in axial sealing contact with an axial sealing surface 25 in the sealing space 16 on the axial inner side of the radial limb 11 of the second angle ring 5. Preferably, for sealing contact of the sealing lip 18, the sealing surface 25 is designed with a special surface for reduced contact friction.The free end 13 of the radial leg 8 of the first angle ring 4 is set down with reduced wall thickness d on the axial sides 24, 32 in a tapering manner, so that the sealing lip 18 on the free end 13 is attached fixedly connected to it, preferably vulcanized on or injection molded on, on both axial sides in a manner saving installation space.The sealing cassette 17 has a radial structural height h corresponding to the radial distance between the outer diameter of the axial limb 8 of the first angle ring 4 and the inner diameter of the axial limb 10 of the second angle ring 5 of less than 3.2 mm.Furthermore, the sealing cassette 17 is designed with an axial overall width b corresponding to the axial distance between the axial outer sides 21, 24 of the radial legs 9, 11 of the angle rings 4, 5 facing away from the sealing space 16, respectively, of less than 1.6 mm. In this way, the sealing arrangement 1 forms a high-performance seal as a cassette seal with a particularly low installation space requirement.The rolling bearing 2, 3 is preferably designed as a grooved ball bearing, as shown in FIGS. 1, 3 and 4. It is arranged with the inner diameter of the bearing inner ring 7 on the outer diameter of a shaft 29, preferably of a pedal crank shaft of a two-wheeler, as illustrated in FIGS. 4 and 5, connected thereto in a rotationally fixed manner. The rolling bearing 2, 3 is designed as a thin-ring bearing with a bearing overall width B preferably of 7 mm or less than 7 mm, measured between the axial end faces of the rolling bearing 2 as denoted in FIG. 1.The sealing cassette 17 is fastened with the outer diameter of the axial limb 8 of the first angle ring 4 to the inner diameter of the bearing shoulder 19 of the bearing outer ring 6 and with the inner diameter of the axial limb 10 of the second angle ring 5 to the outer diameter of the bearing shoulder 20 of the bearing inner ring 7, preferably in the press fit.To accommodate the sealing cassette 17, the bearing inner ring 7 is designed with a reduced radial wall thickness W of less than 1.2 mm in the region of the bearing shoulder 20. For this purpose, the bearing shoulder 20 is offset radially inward at the outer diameter toward the free outer axial edge, for example as a puncture.On the outer diameter of the bearing outer ring 6, a sealing ring 27 is arranged in a radial depression 26 designed as a groove, as an O-ring for the radial sealing of the bearing seat on a stationary component, which is not shown. In this case, in the region of the depression 26, the bearing outer ring 6 is designed with a reduced radial wall thickness L of less than 1.2 mm. The depression 26 with the sealing ring 27 is preferably arranged in a central region situated between the axial ends of the bearing outer ring 6 at the level of the rolling body raceway 27 formed on the inner diameter of the bearing outer ring 6. Consequently, the rolling bearing 2, 3 can be designed with an additional seal 27 for sealing the bearing seat without requiring additional installation space.The bearing inner ring 7 is preferably fastened in a press fit on a shaft 29, preferably a pedal crank shaft of the two-wheeler, as shown in FIGS. 4 and 5. At the same time, the seal between the bearing inner ring 7 and the shaft 29 is achieved at the press fit.For further reduction of installation space, the ball diameter D of the rolling bodies 28 is reduced. The ball diameter D is preferably 3.5 mm or is less than 3.5 mm.Accordingly, the rolling bearing 2, 3 can be designed as a thin-ring bearing with a small bearing overall width B and a small radial overall height H and with the sealing arrangement 1 with the sealing cassette 17 as a one-sided high-performance seal for sealing off from the environment. The radial structural height H of the rolling bearing 2, 3 corresponding to the radial distance between the inner diameter of the bearing inner ring 7 and the outer diameter of the bearing outer ring 6 is preferably 13 mm or is less than 13 mm.The rolling element cage 35 for guiding the rolling elements 28 is designed in such a way that in each case the smallest possible radial gap S 1 is established with respect to the inner diameter of the bearing outer ring 6 and with respect to the outer diameter of the bearing inner ring 7. In this case, the radial gaps S 1 each preferably have a gap width of 0.5 mm or less than 0.5 mm in an ideal coaxial arrangement of the rolling body cage 35 with respect to the bearing outer ring 6 and the bearing inner ring 7. Consequently, on the axial inner side of the roller bearing 2, 3 facing the interior to be sealed, a shielding effect is achieved to prevent dirt particles from entering the interior, in particular from engine and transmission abrasion. At the same time, the escape of grease from the rolling bearing 2, 3 is avoided.FIGS. 4 and 5 show the proposed bottom bracket arrangement, for example, in the installed position on an electrically drivable two-wheeler, in particular an e-bike or a pedelec. In FIG. 4, the bottom bracket arrangement is accommodated with a housing 34, a bottom bracket in the form of two rolling bearings 2, 3 described above, an electric motor, not shown, and a transmission, not shown. The housing 34 is connected to a support frame 35 of the two-wheeler, for example a bicycle frame. A pedal crank shaft 31 is arranged transversely to the longitudinal axis of the two-wheeler and is guided with its axial ends through the housing 34. It is connected at its axial ends to a pedal crank 36, 37 of the two-wheeler, respectively. The output at the pedal crankshaft 31 is effected via a drive wheel 38 designed as a sprocket.FIG. 5 shows the bottom bracket arrangement in a sectional partial view. The pedal crankshaft 31 is mounted at its axial end portions in the housing 34 via a respective rolling bearing 2, 3 described above. For this purpose, the bearing outer ring 6 of the respective rolling bearing 2, 3 is supported with the outer diameter on the inner diameter of a bearing seat 39 formed on the inner side of the housing 34.The two-wheeler can be driven both via the cranks 36, 37 (FIG. 4 ) and the crank shaft 31 and via the electric motor.The housing 34 is sealed from the environment. At the passage of the pedal crankshaft 31, it is sealed off from the environment by the rolling bearings 2, 3 with the proposed sealing arrangement 1 described above. As a result, the roller bearings 2, 3, the electric motor and the transmission are protected in the housing 34 from moisture and dirt particles from the environment.List of reference characters1 Sealing arrangement 2 Rolling bearing 3 Rolling bearing 4 First angle ring 5 Second angle ring 6 Bearing outer ring 7 Bearing inner ring 8 Axial limb of the first angle ring 9 Radial limb of the first angle ring 10 Axial limb of the second angle ring 11 Radial limb of the second angle ring 12 Free end of the axial limb of the first angle ring 13 Free end of the radial limb of the first angle ring 14 Free end of the axial limb of the second angle ring 15 Free end of the radial limb of the second angle ring 16 Sealing space 17 Sealing cassette 18 Dynamic seal, sealing lip 19 Bearing shoulder of the bearing outer ring 20 Bearing shoulder of the bearing inner ring 21 Axial outer side 22 Radial sealing gap 23 Radial sealing gap 24 Axial outer side 25 Axial sealing surface 26 Radial depression, groove on the outer diameter of the bearing outer ring 27 Sealing ring, Seal 28 Bearing axis 29 Rolling element raceway 30 Rolling element, ball 31 Shaft, crank shaft 32 Axial inner side of the radial limb of the first angle ring 33 Rolling element cage 34 Stationary component, housing 35 Supporting frame, bicycle frame 36 Crank 37 Crank 38 Drive wheel 39 Bearing seat S Radial bearing gap d Reduced wall thickness of the radial limb of the first angle ring h Radial structural height of the sealing cassette b Axial structural width of the sealing cassette B Axial bearing structural width W Reduced radial wall thickness of the bearing inner ring L Reduced radial wall thickness of the bearing outer ring D Ball diameter of the rolling elements H Radial structural height S 1 Radial gapReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2015 216 168 B3

[0002]

Claims

Sealing arrangement (1) for a rolling bearing (2, 3), characterized in that a first angle ring (4) for fastening to the bearing outer ring (6) and a second angle ring (5) for fastening to the bearing inner ring (7) are arranged in such a way that they delimit an annular sealing space (16) in the form of an annular sealing cassette (17) and an axial dynamic seal (18) is arranged in the sealing space (16) and two radial sealing gaps (22, 23) are formed between the angle rings (4, 5), wherein the sealing cassette (17) has a radial installation height (h) corresponding to the distance between the outer diameter of the first angle ring (4) and the inner diameter of the second angle ring (5) of less than 3.2 mm and an axial installation width (b) corresponding to the axial distance of the mutually remote axial outer sides (21, 24) of the angle rings (4, 5) of less than 1.6 mm.Sealing arrangement according to Claim 1, characterized in that the radial sealing gaps (22, 23) each have a radial gap dimension of 0.3 mm or less than 0.3 mm.Sealing arrangement according to either of Claims 1 and 2, characterized in that the sealing cassette (17) can be pressed in for fastening purposes with the outer diameter of an axial limb (8) of the first angle ring (4) which extends in the axial direction on the inner diameter of the bearing outer ring (6) and with the inner diameter of an axial limb (10) of the second angle ring (5) which extends in the axial direction on the outer diameter of the bearing inner ring (6).Sealing arrangement according to claim 3, characterised in that a first radial sealing gap (22) is formed between the axial leg (8) of the first angle ring (4) and the free end (15) of the radially outwardly extending radial leg (11) of the second angle ring (5) and a second radial sealing gap (23) is formed between the free end (13) of a radially inwardly extending radial leg (9) of the first angle ring (4) and the axial leg (10) of the second angle ring (5).Sealing arrangement according to Claim 4, characterized in that a sealing lip is provided as dynamic seal (18), which sealing lip extends starting from the radial limb (9) of the first angle ring (4) in axial sealing contact with an axial sealing surface (25) on the radial limb (11) of the second angle ring (5).Sealing arrangement according to claim 5, characterised in that the free end (13) of the radial limb (9) of the first angle ring (4) with reduced wall thickness () is set down in a tapering manner on the axial sides (24, 32) and the dynamic seal (18) is firmly connected to the free end (13) on both axial sides (24, 32) thereof.Rolling bearing (2, 3) having a sealing arrangement according to one of Claims 1 to 6, wherein the sealing arrangement (1) is arranged with a sealing cassette (17) for sealing off a radial bearing gap (S) formed between the bearing rings (6, 7).Rolling bearing (2, 3) according to Claim 7, characterized in that the bearing inner ring (7) is designed in the region of the sealing cassette (17) with a reduced radial wall thickness (W) of less than 1.2 mm.Rolling bearing (2, 3) according to either of Claims 7 and 8, characterized in that a sealing ring (27) for sealing the bearing seat (39) on a stationary component (39) is arranged on the outer diameter of the bearing outer ring (6) in a radial depression (26), and the bearing outer ring (6) is designed in the region of the depression (26) with a radial wall thickness (L) of less than 1.2 mm.Bottom bracket arrangement for mounting a crank shaft (31) of an electrically drivable two-wheeler, having at least one rolling bearing (2, 3) according to one of Claims 7 to 9.

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