Double ring oil seal

Abstract

This invention provides a double-ring oil seal that reduces the frequency of maintenance by allowing adjustment of the grease supply to the lip portion. [Solution] The outer sealing member 16 and the inner sealing member 22 form a grease-retaining space S2 that communicates with the sealing space S1 through a communication hole h, and the grease-retaining space S2 is filled with grease. As a result, grease is supplied from the grease-retaining space S2 to the sealing space S1 through the communication hole h, so that the decrease and loss of grease in the sealing space S1 is suppressed. Therefore, wear of the side lip 20a and the generation of abnormal noise are suppressed, and the rust prevention ability of the oil seal 10 and shaft 14 is improved, and the frequency of maintenance can be reduced.

Description

Technical Field

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[0001] The present invention relates to a structure for improving the maintainability of an oil seal.

Background Art

[0002] An oil seal provided with an outer seal member provided in a gap between a rotating body and a non-rotating body to prevent intrusion from the outside and an inner seal member to prevent leakage from the inside is known. In the oil seal, lubricating oil (grease) is held in a seal space formed by being surrounded by the outer seal member, the inner seal member, and the seal target surface of the rotating body, and a sliding close contact portion (hereinafter referred to as a lip portion) provided on the seal surface of the seal member is maintained. A technique for maintaining the sealing performance is disclosed. For example, the shaft seal for refrigerant described in Patent Document 1 is such an example.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the case where the space for holding the lubricating oil (grease) is a space formed by being surrounded by the outer seal member, the inner seal member, and the seal target surface of the rotating body as in Patent Document 1, when the seal member suddenly shifts, the grease flows out to the outside, and due to the decrease and disappearance of the grease, there is a risk of wear and abnormal noise generation in the lip portion provided on the seal member, and there is a problem that the maintenance frequency of grease replenishment for that purpose increases.

[0005] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a double-ring oil seal capable of reducing the maintenance frequency by enabling adjustment of the grease supply to the lip portion. [Means for solving the problem]

[0006] The gist of the present invention is a double ring oil seal provided in the gap between a non-rotating body and a rotating body, forming a sealing space surrounded by an outer sealing member, an inner sealing member, and the sealing surface of the rotating body, (b) the outer sealing member and the inner sealing member form a grease holding space that communicates with the sealing space through a communication hole, and (c) the grease holding space is filled with grease. [Effects of the Invention]

[0007] According to the present invention, the outer sealing member and the inner sealing member form a grease-retaining space that communicates with the sealing space through a communication hole, and the grease-retaining space is filled with grease. As a result, grease is supplied from the grease-retaining space to the sealing space through the communication hole, thereby preventing the decrease and loss of grease in the sealing space. Therefore, wear of the lip portion of the sealing member and the generation of abnormal noise can be suppressed, and the rust prevention ability of the double-ring oil seal and the rotating body can be improved, making it possible to provide a double-ring oil seal that requires less maintenance.

[0008] Preferably, the communication hole is equipped with a supply adjustment valve that adjusts the amount of grease supplied from the grease retention space. As a result, the supply adjustment valve ensures that grease is properly supplied to the seal space, thus providing a double-ring oil seal that requires less maintenance.

[0009] Preferably, the grease retention space is provided with a grease replenishment hole that communicates with the outer circumferential surface of the inner sealing member. As a result, grease is replenished into the grease retention space through the grease replenishment hole, which reduces the frequency of maintenance and improves maintainability.

[0010] Preferably, the grease replenishment hole is equipped with a backflow prevention valve to prevent grease from flowing out of the grease replenishment hole. This eliminates the need for a grease nipple or cover to seal the grease replenishment hole.

[0011] Preferably, the supply amount adjustment valve and the backflow prevention valve provided in the grease replenishment hole are provided together. This makes it possible to provide a double-ring oil seal that reduces the frequency of maintenance and improves maintainability. [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view illustrating an example of an oil seal to which the present invention is applied. [Figure 2] This is a cross-sectional view of an oil seal corresponding to another embodiment of the present invention. [Figure 3] This is a cross-sectional view of an oil seal corresponding to another embodiment of the present invention. [Figure 4] This is a cross-sectional view of an oil seal corresponding to another embodiment of the present invention. [Figure 5] This is a cross-sectional view of an oil seal corresponding to another embodiment of the present invention. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily depicted accurately. [Examples]

[0014] Figure 1 is a cross-sectional view illustrating an example of an oil seal to which the present invention is applied. In Figure 1, the shaft 14, which is a rotating body, has its right half omitted with respect to its axis of rotation CL. The oil seal 10 is provided to prevent the outflow of oil filled in the internal space sealed by the housing 12, which is a non-rotating body, and to prevent foreign matter from entering the housing 12 from the outside. In Figure 1, the outer circumference (left side of the paper) of the housing 12 corresponds to the outside, and the inner circumference (right side of the paper) corresponds to the internal space.

[0015] The shaft 14 is inserted through a through hole in the housing 12 and is rotatably supported around the axis of rotation CL via a bearing (not shown). The portion of the shaft 14 that is inserted into the housing 12 is formed in a stepped shape, and its shaft diameter is smaller than the diameter of the inner circumferential surface 12a of the housing 12. Therefore, a gap is formed between the inner circumferential surface 12a and the outer circumferential surface 14a of the shaft 14. In addition, a deflector 14b is provided on the lower surface of the stepped shape of the portion of the shaft 14 that is inserted, in order to suppress the intrusion of foreign matter from the outside. The deflector 14b is formed in a double cylindrical shape with a bottom surface (hereinafter referred to as the deflector bottom surface) 14b1 perpendicular to the axis of rotation CL, and its inner circumferential side is fixed to the shaft 14 by press-fitting or the like, and rotates integrally with the shaft 14. The oil seal 10 is formed in an annular shape and is provided to close the gap between the housing 12 and the shaft 14 (outer circumferential surface 14a and deflector bottom surface 14b1). Furthermore, the housing 12 corresponds to the "non-rotating body" of the present invention, the shaft 14 corresponds to the "rotating body" of the present invention, and the outer peripheral surface 14a and the deflector bottom surface 14b1 correspond to the "sealing surface" of the present invention.

[0016] The oil seal 10 is a double-ring oil seal (double-ring oil seal) comprising an outer sealing member 16 that closes the gap with the bottom surface 14b1 of the deflector and an inner sealing member 22 that closes the gap with the outer peripheral surface 14a.

[0017] The outer seal member 16 is composed of a metal ring 18 formed in an L-shaped cross-section made of a metal material, and an outer seal 20 made of an elastic member such as fluororubber integrally formed with the metal ring 18. The outer seal 20 is integrally provided with a side lip 20a that slidably contacts (sliding contact) the bottom surface 14b1 of the deflector and the tip, preventing the intrusion of foreign matter from the outside.

[0018] The inner seal member 22 is composed of a metal ring 24 with a substantially concave portion formed at the center of the bottom side of an L-shaped cross-section made of a metal material, and an inner seal 26 made of an elastic member such as fluororubber integrally formed with the metal ring 24. The inner seal 26 is integrally provided with a seal lip 26a that slidably contacts (sliding contact) the outer peripheral surface 14a of the shaft 14, and a dust lip 26b. The seal lip 26a is provided to prevent oil from flowing out of the internal space of the housing 12, and a garter spring 30 is attached to the outer peripheral portion. The dust lip 26b is provided to prevent foreign matter from entering the internal space of the housing 12.

[0019] As shown in FIG. 1, by providing the oil seal 10, a seal space S1 surrounded by the outer seal member 16, the inner seal member 22, and the seal target surfaces (outer peripheral surface 14a and deflector bottom surface 14b1) of the shaft 14 is formed. Further, between the outer seal member 16 and the inner seal member 22, a grease holding space S2 is formed along the substantially concave shape of the metal ring 24. Also, on the outer peripheral side (left side of the paper surface) of the grease holding space S2, the metal ring 18 and the metal ring 24 are integrally fastened by a cylindrical portion 28 so as to close the grease holding space S2. That is, the outer seal member 16 and the inner seal member 22 are integrally connected by the cylindrical portion 28. Further, by fitting the fitting surface 22a on the concave outer peripheral side of the inner seal member 22 to the inner peripheral surface 12a of the housing 12 by press-fitting or the like, the oil seal 10 (outer seal member 16 and inner seal member 22) is fixed to the housing 12.

[0020] The grease holding space S2 is filled with grease. Further, on the inner peripheral side (right side in the drawing) of the grease holding space S2, a communication hole h for communicating the seal space S1 and the grease holding space S2 is provided between the outer seal 20 and the inner seal 26, and grease is supplied from the grease holding space S2 to the seal space S1 through the communication hole h. The shape, size, arrangement, number, etc. of the communication hole h are set to suitable values obtained by design or experiment.

[0021] By the way, in the conventional oil seal, in order to suppress wear and abnormal noise of the side lip 20a, grease was applied and held in the seal space S1. However, in the case of the seal space S1, when the side lip 20a suddenly shifts, the grease may flow out to the outside, and wear and abnormal noise generation of the side lip 20a may occur due to the decrease and disappearance of the grease, resulting in a problem of high maintenance frequency for grease replenishment.

[0022] On the other hand, the oil seal 10 of this embodiment is provided with a grease holding space S2 filled with grease, and since grease is supplied from the grease holding space S2 to the seal space S1 through the communication hole h, the decrease and disappearance of the grease in the seal space S1 are suppressed.

[0023] As described above, according to this embodiment, the outer seal member 16 and the inner seal member 22 form a grease holding space S2 communicating with the seal space S1 through the communication hole h, and the grease holding space S2 is filled with grease. As a result, grease is supplied from the grease holding space S2 to the seal space S1 through the communication hole h, so that the decrease and disappearance of the grease in the seal space S1 are suppressed. Therefore, wear and abnormal noise generation of the side lip 20a can be suppressed, and the rust prevention ability of the oil seal 10 and the shaft 14 can be improved, and the maintenance frequency can be reduced.

[0024] Next, another embodiment of the present invention will be described. In the following description, the same reference numerals are given to the parts common to the embodiments, and the description thereof will be omitted.

Embodiment

[0025] Figure 2 is a cross-sectional view of an oil seal 10A corresponding to another embodiment of the present invention. Oil seal 10A is an embodiment in which a supply amount adjustment valve c is provided in the communication hole h of the oil seal 10 of Embodiment 1 described above to adjust the amount of grease supplied from the grease holding space S2 to the sealing space S1. The supply amount adjustment valve c is a valve mechanism that adjusts the appropriate amount of grease supplied according to, for example, the negative pressure in the sealing space S1 or the ambient temperature. For adjusting the amount of grease supplied, a suitable method and setting value determined by design or experiment is predetermined.

[0026] The oil seal 10A configured as described above also provides the same effects as the oil seal 10 of the aforementioned embodiment 1. Furthermore, since the supply amount adjustment valve c ensures that grease is properly supplied to the seal space S1, the frequency of maintenance is reduced. [Examples]

[0027] Figure 3 is a cross-sectional view of an oil seal 40 corresponding to another embodiment of the present invention. The oil seal 40 is an example in which a grease replenishment hole d is provided on the outer circumference side of the grease retention space S2, compared to the oil seal 10 of Embodiment 1 described above. As shown in Figure 3, on the outer circumference side (left side of the paper) of the grease retention space S2, the outer seal member 46 (metal ring 48) and the inner seal member 52 (metal ring 54) are integrally fastened together by a cylindrical portion 58, but a grease replenishment hole d is formed between the outer seal member 46 (metal ring 48) and the inner seal member 52 (metal ring 54), communicating with the outer circumference surface of the inner seal member 52. Also, similar to the oil seal 10 of Embodiment 1, the oil seal 40 (outer seal member 46 and inner seal member 52) is fixed to the housing 12 by press-fitting or the like, the recessed outer fitting surface 52a of the inner seal member 52 into the inner circumference surface 12a of the housing 12.

[0028] Grease is replenished in the grease retention space S2 through the grease replenishment hole d. The grease replenishment hole d is fitted with a device to seal it, such as a grease nipple or a removable or disposable cap. The shape, size, and placement of the grease replenishment hole d are predetermined to optimal values ​​determined through design or experimentation.

[0029] The oil seal 40 configured as described above also provides the same effects as the oil seal 10 in Example 1. Furthermore, since grease is replenished into the grease retention space S2 through the grease replenishment hole d, maintainability can be improved. [Examples]

[0030] Figure 4 is a cross-sectional view of an oil seal 40A corresponding to another embodiment of the present invention. Oil seal 40A is an embodiment in which a backflow prevention valve e is provided in the grease replenishment hole d of the oil seal 40 of Embodiment 3 described above to prevent grease from flowing out of the grease replenishment hole d. The backflow prevention valve e is a valve mechanism that prevents grease from flowing back out of the grease holding space S2 and flowing out of the grease replenishment hole d, and is formed of an elastic material such as fluororubber. The shape, size, and arrangement of the backflow prevention valve e are predetermined to be suitable values ​​determined through design or experimentation.

[0031] The oil seal 40A configured as described above also provides the same effects as the oil seal 40 in the aforementioned embodiment 3. Furthermore, a grease nipple or cover for sealing the grease replenishment hole d is not required. [Examples]

[0032] Figure 5 is a cross-sectional view of an oil seal 40B corresponding to another embodiment of the present invention. Oil seal 40B is an embodiment in which the supply amount control valve c of Embodiment 2 and the backflow prevention valve e of Embodiment 4 are applied simultaneously.

[0033] The oil seal 40B configured as described above also provides the same effects as those in Examples 2 and 4 described above.

[0034] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is also applicable to other embodiments.

[0035] For example, in the above-described embodiments 1 to 5, the outer sealing members 16 and 46 sealed the gap with the deflector bottom surface 14b1. However, they are not limited to the deflector bottom surface 14b1; for example, they may also seal the gap with the outer peripheral surface 14a of the shaft 14 located outside the inner sealing members 22 and 52. The present invention applies to any double-ring oil seal in which a sealing space S1 is formed between the outer sealing member 16 (or 46), the inner sealing member 22 (or 52), and the sealing surface of the shaft 14 (rotating body).

[0036] It should be noted that the above-described embodiment is merely one example, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0037] 10, 10A, 40, 40A, 40B: Oil seal (double ring oil seal) 12: Housing (non-rotating body) 14: Shaft (rotating body) 14a: Outer surface (surface to be sealed) 14b1: Deflector bottom surface (surface to be sealed) 16, 46: Outer sealing member 22, 52: Inner sealing member h: Communication hole S1: Seal space S2: Grease retention space

Claims

[Claim 1] A double ring oil seal provided in the gap between a non-rotating body and a rotating body, forming a sealing space surrounded by an outer sealing member, an inner sealing member, and the sealing surface of the rotating body, The outer sealing member and the inner sealing member form a grease-holding space that communicates with the sealing space through a communication hole. The grease-holding space is filled with grease. A double-ring oil seal characterized by the following features.

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