Oil seal

Abstract

The oil seal (101) includes a seal portion (10) formed in an annular shape and fitted onto the outer peripheral surface (3o) of the rotating body (3), an annular spring (20), and an annular body (30) that is separate from the seal portion (10) and fitted onto the inner peripheral surface (2i) of the non-rotating body (2). The seal portion (10) has an inner surface (11), an outer surface (12), and an inner peripheral contact surface (13) that contacts the outer peripheral surface (3o). The annular body (30) has a facing portion (31) that faces the inner peripheral surface (2i), and a cover (32) that covers the outer surface (12). The spring (20) is fitted into the seal portion (10), and a groove (14) is formed in the seal portion (10) that narrows toward the rotating body (3). A spring (20) fitted in the groove (14) presses the inner peripheral contact surface (13) against the rotating body (3) and presses the outer surface (12) against the cover (32).

Description

[Technical field]

[0001] The present disclosure relates to oil seals. [Background technology]

[0002] Patent Document 1 describes an oil seal having a seal portion formed by integrally molding a rubber-like elastic material with a metal ring. This seal portion has an outer circumferential seal portion fitted to the inner circumferential surface of the non-rotating body, a seal lip extending from the flange of the metal ring toward the sealed fluid side and abutting against the outer circumferential surface of the rotating body, and a dust lip extending from the flange of the metal ring to the opposite side to the seal lip and abutting against the outer circumferential surface of the rotating body. The seal lip is tightened to the rotating body by an annular spring built into the oil seal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-57729 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the oil seal described in Patent Document 1, a metal ring is inserted into the sealing portion, so when the sealing portion wears out, the entire oil seal must be replaced. In addition, this oil seal has a complex integrated shape and a complex structure.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has an object to provide an oil seal that is simple in structure and allows easy replacement of worn parts. [Means for solving the problem]

[0006] In order to achieve the above object, the oil seal according to the present disclosure comprises: An oil seal provided between an inner circumferential surface of an open non-rotating body and an outer circumferential surface of a rotating body that rotates relative to the non-rotating body, a seal portion that is fitted to the outer circumferential surface of the rotating body and is formed in an annular shape from an elastic resin; an annular spring that presses the seal portion against the rotating body; an annular body that is separate from the seal portion and is fitted onto the inner circumferential surface of the non-rotating body, the seal portion has an inner surface located on a side of an object to be sealed, an outer surface located opposite the inner surface, and an inner peripheral contact surface that contacts the outer peripheral surface of the rotating body, the annular body has a facing portion facing the inner circumferential surface of the non-rotating body and a cover covering the outer surface of the seal portion, The seal portion has a groove in which the spring is fitted and whose width narrows toward the rotor, The spring fitted in the groove presses the inner peripheral contact surface of the seal portion against the rotating body, and presses the outer surface of the seal portion against the cover. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide an oil seal that allows easy replacement of worn parts and has a simple structure. [Brief description of the drawings]

[0008] [Figure 1] FIG. 3 is a cross-sectional view of the oil seal according to the first embodiment of the present disclosure, and is an enlarged view of part A in FIG. 2. [Diagram 2] FIG. 2 is a cross-sectional view of an oil seal and a bearing according to the first embodiment. [Diagram 3] 1 is a cross-sectional view of a reducer to which an oil seal according to a first embodiment is applied. [Figure 4] FIG. 4 is a cross-sectional view of an oil seal according to a second embodiment of the present disclosure. [Diagram 5] FIG. 4 is a cross-sectional view of an oil seal according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the present disclosure will be described with reference to the drawings.

[0010] (First embodiment) As shown in Fig. 1, an oil seal 101 according to the first embodiment is provided between an inner peripheral surface 2i of an open non-rotating body 2 and an outer peripheral surface 3o of a rotating body 3 that rotates relative to the non-rotating body 2. For example, as shown in Fig. 2, the non-rotating body 2 constitutes an outer ring of a bearing 1, and the rotating body 3 constitutes an inner ring of the bearing 1. Fig. 1 is an enlarged view of a portion A in Fig. 2. The rotating body 3 is rotatable around an axis line AX shown in Fig. 3.

[0011] The bearing 1 is, for example, a cross roller bearing, and is a component of a reducer. Although various well-known configurations can be applied to the reducer, a reducer 200 shown in Fig. 3 will be briefly described as an example.

[0012] (Reducer 200) The reducer 200 is configured as a wave gear device, and includes a wave generator 210, a rigid internal gear 220, a flex portion 230, a rigid external gear 240, a bearing 1, and an oil seal 101.

[0013] In each drawing, hatching showing a cross section of a part of the configuration is omitted for ease of viewing. In the following description, the circumferential direction about the axis line AX is simply referred to as the "circumferential direction," the radial direction about the axis line AX is simply referred to as the "radial direction," and the direction in which the axis line AX extends is simply referred to as the "axial direction."

[0014] The wave generator 210 includes a cam 211 that rotates about an axis line AX in response to a rotational input, and an annular wave bearing 212 provided on the outer circumferential surface of the cam 211. The cam 211 is formed on the outer periphery of a hollow shaft, and has N poles (N is an integer of 2 or more) that are equally spaced in the circumferential direction. For example, the cam 211 is elliptical and has two poles. The rigid internal gear 220 is formed to have rigidity from a known material such as metal, and surrounds the wave bearing 212.

[0015] The flex portion 230 is formed into a cylindrical shape having flexibility from a metal material such as special steel, and includes a flexible external gear 231 and a flexible internal gear 232. The flexible external gear 231 is fitted onto the outer periphery of the wave bearing 212, and is deflected at a position corresponding to the pole of the cam 211 to mesh with the rigid internal gear 220. The flexible internal gear 232 is deflected in response to the flexible external gear 231 being deflected by the wave generator 210, and meshes with the rigid external gear 240. The rigid external gear 240 is formed into an annular shape having rigidity from a known material such as metal.

[0016] A speed ratio is generated between the cam 211 and the flex portion 230 according to the difference in the number of teeth between the flexible external gear 231 and the rigid internal gear 220. On the other hand, the number of teeth between the flexible internal gear 232 and the rigid external gear 240 may be the same or different. When there is a difference in the number of teeth between the flexible internal gear 232 and the rigid external gear 240, a speed ratio is generated between the flex portion 230 and the rigid external gear 240 according to the difference in the number of teeth. In any case, the reducer 200 decelerates the rigid external gear 240 with respect to the rotation input based on the relationship between the number of teeth of the rigid internal gear 220, the flexible external gear 231, the flexible internal gear 232, and the rigid external gear 240.

[0017] A non-rotating body 2 (outer ring) of the bearing 1 is directly or indirectly fixed to a rigid internal gear 220. On the other hand, a rotating body 3 (inner ring) of the bearing 1 is fixed to a rigid external gear 240. The rotating body 3, which rotates together with the rigid external gear 240, is connected to an output target (not shown).

[0018] (Oil Seal 101) 1 and 2, the oil seal 101 is provided inside a recess formed across the boundary between a non-rotating body 2 (outer ring) and a rotating body 3 (inner ring) of a bearing 1. This recess is formed in an annular shape when viewed from the axial direction. The oil seal 101 includes a seal portion 10, a spring 20, an annular body 30, and a fitting portion 40.

[0019] The seal portion 10 is fitted to the outer peripheral surface 3o of the rotating body 3 and is formed into a ring shape from an elastic resin. The seal portion 10 is formed from a well-known elastomer such as NBR (Nitrile Butadiene Rubber). As shown in Fig. 1, the seal portion 10 has an inner surface 11 located on the side of the object to be sealed, an outer surface 12 located opposite the inner surface, and an inner peripheral contact surface 13 that contacts the outer peripheral surface 3o of the rotating body 3. In Fig. 1, the side to be sealed, such as oil, grease, etc., is marked as "In" and the side to the atmosphere is marked as "Out" (the same applies to Figs. 4 and 5 described below).

[0020] A spring 20 is fitted between the inner surface 11 and the outer surface 12 of the seal portion 10, and a groove 14 is formed whose width narrows toward the rotating body 3. The groove 14 is formed around the entire circumference of the seal portion 10, and is V-shaped in cross section.

[0021] The spring 20 is a garter spring that is configured in an annular shape when viewed from the axial direction and surrounds the entire circumference of the seal portion 10. The spring 20 tightens the seal portion 10 to the rotating body 3. In other words, the spring 20 presses the seal portion 10 toward the rotating body 3. The spring 20 fitted in the groove 14 of the seal portion 10 presses the inner peripheral contact surface 13 of the seal portion 10 against the rotating body 3 (specifically, the outer periphery 3o of the rotating body 3), and the seal portion 10 is expanded in the axial direction.

[0022] The annular body 30 has an annular shape when viewed from the axial direction, and is fitted into the inner peripheral surface 2i of the non-rotating body 2. For example, the annular body 30 is formed by metal press processing. Note that the annular body 30 is not limited to metal, and may be made of engineering plastics or the like as long as the rigidity can be ensured. The annular body 30 is separate from the seal portion 10, that is, it is separable from the seal portion 10.

[0023] 1, the annular body 30 has a facing portion 31 facing the inner circumferential surface 2i of the non-rotating body 2, and a cover 32 covering the outer surface 12 of the seal portion 10. The integrated shape of the facing portion 31 and the cover 32 forms an L-shape in cross section as shown in FIG.

[0024] As described above, the seal portion 10 is expanded in the axial direction by the spring 20 fitted in the groove 14 of the seal portion 10. As a result, the outer surface 12 of the seal portion 10 is pressed against the cover 32, and the inner surface 11 is pressed against the rotating body 3 in the axial direction.

[0025] The fitting portion 40 is provided by lining or coating on the facing portion 31 of the annular body 30, and comes into contact with the inner circumferential surface 2i of the non-rotating body 2. In other words, the annular body 30 is fitted into the inner circumferential surface 2i via the fitting portion 40. The fitting portion 40 is made of rubber, resin, or the like, and is provided over the entire circumference of the facing portion 31. The fitting portion 40 makes it easier to fix the annular body 30 to the inner circumferential surface 2i of the non-rotating body 2, and can prevent wear between the annular body 30 and the non-rotating body 2.

[0026] Here, the fitting portion 40 provided on the facing portion 31 of the annular body 30 and the inner circumferential surface 2i of the non-rotating body 2 are sealed. In the first embodiment, the seal portion 10 is press-fitted into the rotating body 3 and rotates together with the rotating body 3. Therefore, the inner circumferential contact surface 13 and the outer circumferential surface 3o of the rotating body 3 are sealed. When the rotating body 3 rotates, the seal portion 10 slides against the annular body 30 fixed to the non-rotating body 2. A lubricant is filled between the cover 32 of the annular body 30 and the outer surface 12 of the seal portion 10, and when the rotating body 3 rotates, the outer surface 12 can slide against the annular body 30 with low friction. In this way, while allowing the seal portion 10 to slide against the annular body 30, as described above, the outer surface 12 is pressed against the cover 32, so that the outer surface 12 and the cover 32 are well sealed. This concludes the description of the first embodiment.

[0027] From here on, similarly to the oil seal 101 according to the first embodiment, oil seals according to other embodiments that can be applied to the bearing 1 and the reducer 200 will be described. In the following, the same reference numerals as in the first embodiment are used for configurations similar to those in the first embodiment, and differences from the first embodiment will be mainly described.

[0028] Second embodiment 4, an oil seal 102 according to the second embodiment includes a seal portion 10, a spring 20, an annular body 30, and a fitting portion 40. The annular body 30 of the second embodiment has a plate 33 in addition to an opposing portion 31 and a cover 32.

[0029] The plate 33 covers the inner surface 11 of the seal portion 10 and is made of metal. The plate 33 comes into axial contact with a recess provided in the non-rotating body 2. Note that a resin layer may be formed by lining or coating on the portion of the plate 33 that comes into contact with the recess.

[0030] The facing portion 31, the cover 32, and the plate 33 constituting the annular body 30 of the second embodiment are substantially U-shaped in cross section. The plate 33 may be integral with the facing portion 31 and the cover 32, or may be a separate body. Furthermore, the plate 33 is not limited to being made of metal, and may be made of engineering plastic or the like, as long as it is possible to ensure rigidity.

[0031] As described above, the seal portion 10 is expanded in the axial direction by the spring 20 fitted in the groove 14 of the seal portion 10. As a result, the outer surface 12 of the seal portion 10 is pressed against the cover 32, and the inner surface 11 is pressed against the plate 33.

[0032] Here, the fitting portion 40 provided on the facing portion 31 of the annular body 30 and the inner peripheral surface 2i of the non-rotating body 2 are sealed. In the second embodiment, the seal portion 10 is press-fitted into the rotating body 3 and rotates together with the rotating body 3. Therefore, the inner peripheral contact surface 13 and the outer peripheral surface 3o of the rotating body 3 are sealed. When the rotating body 3 rotates, the seal portion 10 slides against the annular body 30 fixed to the non-rotating body 2. A lubricant is filled between the cover 32 and the outer surface 12 of the seal portion 10, and between the plate 33 and the inner surface 11 of the seal portion 10, so that when the rotating body 3 rotates, the outer surface 12 and the inner surface 11 can slide against the annular body 30 with low friction. In this way, while allowing the seal portion 10 to slide against the annular body 30, as described above, the outer surface 12 is pressed against the cover 32 and the inner surface 11 is pressed against the plate 33, so that a good seal is formed between the outer surface 12 and the cover 32, and between the inner surface 11 and the plate 33. This concludes the description of the second embodiment.

[0033] Third embodiment 5, an oil seal 103 according to the third embodiment includes a seal portion 10, a spring 20, an annular body 30, and a fitting portion 40. The annular body 30 of the third embodiment has a facing portion 31, a cover 32, and a plate 33, similar to the second embodiment.

[0034] Unlike the first and second embodiments, in the oil seal 103 according to the third embodiment, the rotating body 3 rotates relative to the seal portion 10. That is, the outer peripheral surface 3o of the rotating body 3 slides against the inner peripheral contact surface 13 of the seal portion 10. Therefore, in the third embodiment, a lubricant is filled between the inner peripheral contact surface 13 and the outer peripheral surface 3o of the rotating body 3.

[0035] The seal portion 10 has a recess 13D recessed radially from the inner circumferential contact surface 13, which is provided around the entire circumference of the inner circumferential contact surface 13. This recess 13D can reduce resistance when the rotating body 3 slides against the seal portion 10. In other words, the seal portion 10 according to the third embodiment functions as a seal lip.

[0036] Meanwhile, the seal portion 10 expanded in the axial direction by the spring 20 fitted in the groove 14 is sandwiched between the cover 32 and the plate 33 and fixed to the annular body 30. Therefore, in the third embodiment, no lubricant is filled between the cover 32 and the outer surface 12, and between the plate 33 and the inner surface 11.

[0037] Here, the gap between the fitting portion 40 provided on the facing portion 31 of the annular body 30 and the inner peripheral surface 2i of the non-rotating body 2 is sealed. In addition, in the third embodiment, the gap between the outer surface 12 and the cover 32, and the gap between the inner surface 11 and the plate 33 are sealed. When the rotating body 3 rotates, the outer peripheral surface 3o of the rotating body 3 slides against the inner peripheral contact surface 13 of the seal portion 10. In this way, while allowing the rotating body 3 to slide against the seal portion 10, as described above, the seal portion 10 is fastened to the rotating body 3 by the spring 20, and therefore, a good seal is formed between the inner peripheral contact surface 13 and the rotating body 3. This concludes the description of the third embodiment.

[0038] In the oil seals 101, 102, and 103 described above, the seal portion 10 and the annular body 30 are configured separately. Therefore, when the seal portion 10 wears out, only the seal portion 10 can be replaced.

[0039] In addition, the oil seals 101, 102, and 103 have a simple structure, unlike conventional oil seals in which a metal ring is inserted into the sealing portion. The oil seals 101, 102, and 103, which have a simple structure, are easy to manufacture and easy to assemble.

[0040] Furthermore, conventional oil seals, which have a metal ring inserted into the seal portion, tend to be long in the axial direction due to their structure. On the other hand, oil seals 101, 102, and 103 are constructed by combining parts with simple shapes, so they can be shorter in the axial direction than conventional oil seals. This makes it possible to prevent bearing 1, in which oil seals 101, 102, and 103 are provided, from becoming long and heavy in the axial direction.

[0041] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including the deletion of components) can be made as appropriate within the scope of the present disclosure.

[0042] The bearing 1 is not limited to a cross roller bearing, but may be a roller bearing, a ball bearing, etc. Furthermore, the reducer 200 to which the bearing 1 is applied is not limited to a strain wave gear device, but may be a planetary gear reducer or the like.

[0043] The non-rotating body 2 and the rotating body 3 to which the oil seals 101, 102, 103 are applied are not limited to being components of the bearing 1, and may be components of various devices. For example, the non-rotating body 2 may be a housing in a transfer device of a vehicle, and the rotating body 3 may be inserted into the housing.

[0044] At least one of the oil seals 101, 102, and 103 described above has the characteristics described in the following supplementary notes.

[0045] (Additional Note) (Appendix 1) An oil seal provided between an inner circumferential surface of an open non-rotating body and an outer circumferential surface of a rotating body that rotates relative to the non-rotating body, a seal portion that is fitted to the outer circumferential surface of the rotating body and is formed in an annular shape from an elastic resin; an annular spring that presses the seal portion against the rotating body; an annular body that is separate from the seal portion and is fitted onto the inner circumferential surface of the non-rotating body, the seal portion has an inner surface located on a side of an object to be sealed, an outer surface located opposite the inner surface, and an inner peripheral contact surface that contacts the outer peripheral surface of the rotating body, the annular body has a facing portion facing the inner circumferential surface of the non-rotating body and a cover covering the outer surface of the seal portion, The seal portion has a groove in which the spring is fitted and whose width narrows toward the rotor, the spring fitted in the groove presses the inner peripheral contact surface of the seal portion against the rotating body, and presses the outer peripheral surface of the seal portion against the cover; Oil seal.

[0046] (Appendix 2) The annular body further includes a plate covering the inner surface of the seal portion, The inner surface of the seal portion is pressed against the plate by the spring fitted in the groove. An oil seal as described in Appendix 1.

[0047] (Appendix 3) The rotor further includes a fitting portion that is provided on the opposing portion by lining or coating and that contacts the inner circumferential surface of the non-rotating body. An oil seal as described in Appendix 1.

[0048] (Appendix 4) The seal portion rotates together with the rotating body, When the rotating body rotates, the seal portion slides against the annular body. 4. An oil seal according to any one of claims 1 to 3.

[0049] (Appendix 5) When the rotating body rotates, the rotating body slides against the seal portion. 4. An oil seal according to any one of claims 1 to 3.

[0050] In the above description, descriptions of well-known technical matters have been omitted as appropriate in order to facilitate understanding of the present disclosure.

[0051] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. The above-described embodiments are for the purpose of explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims, not the embodiments. Various modifications made within the scope of the claims and the scope of the invention equivalent thereto are considered to be within the scope of the present invention. [Explanation of symbols]

[0052] 101, 102, 103...Oil seal 10…Sealing part 11...inner surface, 12...outer surface 13...inner contact surface, 13D...recess, 14...groove 20…Spring 30...Cyclic body 31: opposing portion, 32: cover, 33: plate 40…Fitment part 1...Bearing 2...Non-rotating body, 2i...Inner surface 3...rotating body, 3o...outer periphery 200...Reducer

Claims

1. An oil seal provided between an inner circumferential surface of an open non-rotating body and an outer circumferential surface of a rotating body that rotates relative to the non-rotating body, a seal portion that is fitted to the outer circumferential surface of the rotating body and is formed in an annular shape from an elastic resin; an annular spring that presses the seal portion against the rotating body; an annular body that is separate from the seal portion and is fitted onto the inner circumferential surface of the non-rotating body; the seal portion has an inner surface located on a side of an object to be sealed, an outer surface located opposite the inner surface, and an inner peripheral contact surface that contacts the outer peripheral surface of the rotating body, the annular body has a facing portion facing the inner circumferential surface of the non-rotating body and a cover covering the outer surface of the seal portion, The seal portion has a groove in which the spring is fitted and whose width narrows toward the rotor, the spring fitted in the groove presses the inner peripheral contact surface of the seal portion against the rotating body, and presses the outer peripheral surface of the seal portion against the cover; Oil seal.

2. The annular body further includes a plate covering the inner surface of the seal portion, The inner surface of the seal portion is pressed against the plate by the spring fitted in the groove. The oil seal according to claim 1.

3. The rotor further includes a fitting portion that is provided on the opposing portion by lining or coating and that contacts the inner circumferential surface of the non-rotating body. The oil seal according to claim 1.

4. The seal portion rotates together with the rotating body, When the rotating body rotates, the seal portion slides against the annular body. The oil seal according to any one of claims 1 to 3.

5. When the rotating body rotates, the rotating body slides against the seal portion. The oil seal according to any one of claims 1 to 3.