Oil seal

Abstract

An oil seal (101) comprises a seal part (10) that is fitted to the outer peripheral surface (3o) of a rotary body (3) and is formed in an annular shape, an annular spring (20), and an annular body (30) that is separate from the seal part (10) and is fitted into the inner peripheral surface (2i) of a non-rotary body (2). The seal part (10) has an inner surface (11), an outer surface (12), and an inner peripheral contact surface (13) that comes into contact with the outer peripheral surface (3o). The annular body (30) has a facing part (31) that faces the inner peripheral surface (2i), and a cover (32) that covers the outer surface (12). A spring (20) is fitted to the seal part (10), and a groove (14) that becomes narrower toward the rotary body (3) is formed. The spring (20) fitted into the groove (14) causes the inner peripheral contact surface (13) to be pressed against the rotary body (3) and causes the outer surface (12) to be pressed against the cover (32).

Description

Oil seal

[0001] The present disclosure relates to an oil seal.

[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 a 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 from 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.

[0003] JP 2012-57729 A

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

[0005] The present disclosure has been made in consideration of the above-described circumstances, and aims to provide an oil seal that allows easy replacement of worn parts and has a simple structure.

[0006] In order to achieve the above object, the oil seal of the present disclosure is an oil seal provided between the inner peripheral surface of an open non-rotating body and the outer peripheral surface of a rotating body that rotates relative to the non-rotating body, and comprises: a seal portion that is fitted to the outer peripheral surface of the rotating body and is formed in an annular shape from an elastic resin; an annular spring that presses the seal portion toward the rotating body; and an annular body that is separate from the seal portion and is fitted to the inner peripheral surface of the non-rotating body, wherein the seal portion has an inner surface located on the side of the 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, and the annular body has an opposing portion that faces the inner peripheral surface of the non-rotating body and a cover that covers the outer surface of the seal portion, and a groove into which the spring is fitted and whose width narrows toward the rotating body is formed in the seal portion, and 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.

[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.

[0008] Fig. 3 is a cross-sectional view of an oil seal according to a first embodiment of the present disclosure, and is an enlarged view of part A in Fig. 2. Fig. 4 is a cross-sectional view of an oil seal and a bearing according to the first embodiment. Fig. 5 is a cross-sectional view of a reducer to which the oil seal according to the first embodiment is applied. Fig. 6 is a cross-sectional view of an oil seal according to a second embodiment of the present disclosure. Fig. 7 is a cross-sectional view of an oil seal according to a third embodiment of the present disclosure.

[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 the outer ring of a bearing 1, and the rotating body 3 constitutes the inner ring of the bearing 1. Fig. 1 is an enlarged view of part A in Fig. 2. The rotating body 3 is rotatable about 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] (Reduction Gear 200) The reduction gear 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 indicating a cross section of a portion of the configuration has been omitted for ease of viewing. In the following description, the circumferential direction centered on the axis line AX may be simply referred to as the "circumferential direction," the radial direction centered on the axis line AX may be simply referred to as the "radial direction," and the direction in which the axis line AX extends may be simply referred to as the "axial direction."

[0014] The wave generator 210 includes a cam 211 that rotates about an axis AX in response to a rotational input, and an annular wave bearing 212 provided on the outer peripheral 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 greater) 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 section 230 is formed into a flexible cylindrical shape 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 bent at a position corresponding to a pole of the cam 211 to mesh with the rigid internal gear 220. The flexible internal gear 232 bends in response to the flexible external gear 231 being bent by the wave generator 210, and meshes with the rigid external gear 240. The rigid external gear 240 is formed into a ring shape and has rigidity from a known material such as metal.

[0016] A speed ratio occurs between the cam 211 and the flex portion 230 depending on 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 of 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 occurs between the flex portion 230 and the rigid external gear 240 depending on the difference in the number of teeth. In any case, the reducer 200 decelerates the rigid external gear 240 relative to the rotational input based on the relationship between the numbers 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] The non-rotating body 2 (outer ring) of the bearing 1 is fixed directly or indirectly to the rigid internal gear 220. On the other hand, the rotating body 3 (inner ring) of the bearing 1 is fixed to the 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) As shown in Figures 1 and 2, the oil seal 101 is provided inside a recess formed across the boundary between the non-rotating body 2 (outer ring) and the rotating body 3 (inner ring) of the bearing 1. This recess is formed in an annular shape when viewed in 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 onto 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 or grease, is labeled "In," and the side exposed to the atmosphere is labeled "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 in 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 into 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 expands in the axial direction.

[0022] The annular body 30 has an annular shape when viewed in the axial direction, and is fitted onto 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 plastic or the like as long as it can ensure rigidity. 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 that faces the inner circumferential surface 2i of the non-rotating body 2, and a cover 32 that covers the outer surface 12 of the seal portion 10. The integral 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 around 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 also prevents wear between the annular body 30 and the non-rotating body 2.

[0026] Here, a seal is formed between the fitting portion 40 formed on the opposing portion 31 of the annular body 30 and the inner circumferential surface 2i of the non-rotating body 2. In the first embodiment, the seal member 10 is press-fit into the rotating body 3 and rotates together with the rotating body 3. Therefore, a seal is formed between the inner circumferential contact surface 13 and the outer circumferential surface 3o of the rotating body 3. When the rotating body 3 rotates, the seal member 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 member 10, allowing the outer surface 12 to slide against the annular body 30 with low friction as the rotating body 3 rotates. While allowing the seal member 10 to slide against the annular body 30, the outer surface 12 is pressed against the cover 32 as described above, providing a good seal between the outer surface 12 and the cover 32. This concludes the description of the first embodiment.

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

[0028] 4 , an oil seal 102 according to a 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 includes a plate 33 in addition to a facing 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 that constitute the annular body 30 of the second embodiment are generally U-shaped in cross section. The plate 33 may be integral with the facing portion 31 and the cover 32, or may be separate from them. 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, a seal is formed between the fitting portion 40 provided on the opposing portion 31 of the annular body 30 and the inner circumferential surface 2i of the non-rotating body 2. In the second embodiment, the seal portion 10 is press-fit into the rotating body 3 and rotates together with the rotating body 3. Therefore, a seal is formed between the inner circumferential contact surface 13 and the outer circumferential surface 3o of the rotating body 3. 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. 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 relative to 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, thereby providing a good seal between the outer surface 12 and the cover 32 and between the inner surface 11 and the plate 33. This completes the description of the second embodiment.

[0033] 5, an oil seal 103 according to a 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 includes 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 is provided with a recess 13D that is recessed radially from the inner circumferential contact surface 13, over 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, a seal is formed between the fitting portion 40 formed on the opposing portion 31 of the annular body 30 and the inner circumferential surface 2i of the non-rotating body 2. In addition, in the third embodiment, a seal is formed between the outer surface 12 and the cover 32, and between the inner surface 11 and the plate 33. When the rotating body 3 rotates, the outer circumferential surface 3o of the rotating body 3 slides against the inner circumferential 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 circumferential 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 as separate components. Therefore, when the seal portion 10 wears out, only the seal portion 10 can be replaced.

[0039] Furthermore, unlike conventional oil seals in which a metal ring is inserted into the sealing portion, the oil seals 101, 102, and 103 have a simple structure. The oil seals 101, 102, and 103 with a simple structure are easy to manufacture and 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 from a combination of simple-shaped parts, so they can be shorter in the axial direction than conventional oil seals. This prevents bearing 1, in which oil seals 101, 102, and 103 are installed, from becoming axially long and heavy.

[0041] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including 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, etc.

[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 components of the bearing 1, but 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 features described in the following supplementary notes.

[0045] (Notes) (Note 1) An oil seal provided between an inner peripheral surface of an open non-rotating body and an outer peripheral surface of a rotating body that rotates relative to the non-rotating body, comprising: a seal portion that is fitted to the outer peripheral surface of the rotating body and is formed in an annular shape from an elastic resin; an annular spring that presses the seal portion toward the rotating body; and an annular body that is separate from the seal portion and is fitted to the inner peripheral surface of the non-rotating body, wherein the seal portion has an inner surface located on the 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, and the annular body has an opposing portion that faces the inner peripheral surface of the non-rotating body and a cover that covers the outer surface of the seal portion, and a groove into which the spring is fitted and whose width narrows towards the rotating body is formed in the seal portion, and 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.

[0046] (Supplementary Note 2) The oil seal according to Supplementary Note 1, wherein the annular body further includes a plate covering the inner surface of the seal portion, and the inner surface of the seal portion is pressed against the plate by the spring fitted in the groove.

[0047] (Supplementary Note 3) The oil seal according to Supplementary Note 1, further comprising a fitting portion that is provided on the opposing portion by lining or coating and that comes into contact with the inner circumferential surface of the non-rotating body.

[0048] (Supplementary Note 4) The oil seal according to any one of Supplementary Notes 1 to 3, wherein the seal portion rotates together with the rotating body, and when the rotating body rotates, the seal portion slides relative to the annular body.

[0049] (Supplementary Note 5) The oil seal according to any one of Supplementary Notes 1 to 3, wherein when the rotating body rotates, the rotating body slides relative to the seal portion.

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

[0051] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to illustrate the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not by the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

[0052] DESCRIPTION OF SYMBOLS 101, 102, 103...Oil seal 10...Seal portion 11...Inner surface 12...Outer surface 13...Inner peripheral contact surface 13D...Depression 14...Groove 20...Spring 30...Annular body 31...Facing portion 32...Cover 33...Plate 40...Fitting portion 1...Bearing 2...Non-rotating body 2i...Inner peripheral surface 3...Rotating body 3o...Outer peripheral surface 200...Reduction gear

Claims

1. An oil seal provided between the inner peripheral surface of an open non-rotating body and the outer peripheral surface of a rotating body that rotates relative to the non-rotating body, comprising: a seal portion formed in an annular shape from elastic resin and fitted to the outer peripheral surface of the rotating body; an annular spring that presses the seal portion toward the rotating body; and an annular body that is separate from the seal portion and is fitted to the inner peripheral surface of the non-rotating body, wherein the seal portion has an inner surface located on the side of the 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 an opposing portion that faces the inner peripheral surface of the non-rotating body and a cover that covers the outer surface of the seal portion, wherein the seal portion has a groove into which the spring is fitted and whose width narrows towards the rotating body, and 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.

2. An oil seal as set forth in claim 1, wherein the annular body further has a plate covering the inner surface of the seal portion, and the inner surface of the seal portion is pressed against the plate by the spring fitted in the groove.

3. The oil seal according to claim 1, further comprising a fitting portion that is provided on the opposing portion by lining or coating and that comes into contact with the inner peripheral surface of the non-rotating body.

4. An oil seal according to any one of claims 1 to 3, wherein the seal portion rotates together with the rotating body, and when the rotating body rotates, the seal portion slides against the annular body.

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

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