Oil seal unit

Abstract

This invention provides a technology that allows the load acting on a dust lip to be easily set within a predetermined range. [Solution] The oil seal unit seals the gap between a first member and a second member that is rotatable relative to the first member. The oil seal unit comprises a dust lip that extends annularly along the gap and has a fixed end fixed to the first member and a free end located on the second member side, and a disc spring positioned between the free end of the dust lip and the second member. The free end of the dust lip and the disc spring are configured to be slidable.

Description

Technical Field

[0001] The technology disclosed in this specification relates to an oil seal unit.

Background Art

[0002] Patent Document 1 discloses an oil seal unit that seals a gap between a first member and a second member rotatable relative to the first member. This oil seal unit includes a dust lip that extends annularly along the gap.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the oil seal unit of Patent Document 1, the fixed end of the dust lip is fixed to the first member, and the free end of the dust lip abuts against the second member. In the oil seal unit, it is necessary to ensure the sealing performance by the dust lip and suppress excessive wear of the free end of the dust lip. For this purpose, it is necessary to install the oil seal unit so that the load acting on the dust lip is within a predetermined range. However, in the oil seal unit of Patent Document 1, the width of the displacement of the dust lip corresponding to the predetermined range is narrow, and it is difficult to set the load acting on the dust lip within the predetermined range.

[0005] This specification provides a technology that can easily set the load acting on the dust lip within a predetermined range.

Means for Solving the Problems

[0006] The technology disclosed herein is embodied in a first embodiment in an oil seal unit for sealing a gap between a first member and a second member rotatable relative to the first member. The oil seal unit may comprise a dust lip extending annularly along the gap and having a fixed end fixed to the first member and a free end located on the second member side, and a disc spring disposed between the free end of the dust lip and the second member. The free end of the dust lip and the disc spring may be configured to slide.

[0007] In the above configuration, a disc spring is placed between the dust lip and the second member. That is, the dust lip and the disc spring are connected in series between the first member and the second member. In this case, a combined load characteristic is obtained by combining the load characteristics of the dust lip and the load characteristics of the disc spring. In the combined load characteristic, the range of displacement corresponding to a predetermined range is larger than the range of displacement in the load characteristics of the dust lip alone. Therefore, the load acting on the dust lip can be easily set to a predetermined range.

[0008] In a second embodiment, in the first embodiment, the dust lip and the disc spring may be aligned along an axial direction parallel to the axis of rotation of the second member relative to the first member.

[0009] In a third embodiment, in the second embodiment, the outer edge of the disc spring may be provided with a notch that is recessed radially inward.

[0010] According to the above configuration, as the second member rotates, foreign matter can be discharged radially outward through the notch.

[0011] In a fourth embodiment, in the third embodiment, the oil seal unit may further include a cover member fixed to the second member and supporting the disc spring. The cover member may be provided with a projection that engages with the notch.

[0012] With the above configuration, the cover member and the disc spring rotate together. Therefore, relative sliding can be easily generated between the disc spring and the dust lip.

[0013] In a fifth embodiment, in the first or fourth embodiment, the oil seal unit may further include a cover member fixed to the second member and supporting the disc spring. The cover member may be provided with a groove extending radially outward from the position of the notch of the disc spring.

[0014] According to the above configuration, in a configuration in which the oil seal unit is equipped with a cover member, as the second member rotates, foreign matter can be discharged radially outward through the notch and groove. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram of the oil seal unit 2. [Figure 2] This is a view of the disc spring 26 and cover member 28 of the oil seal unit 2 from the other side in the axial direction AD. [Figure 3] This is an enlarged view of part III in Figure 2. [Figure 4] This is a schematic diagram of the comparative example oil seal unit 202. [Figure 5] This figure shows the load characteristics of the comparative example oil seal unit 202. [Figure 6] This figure shows the load characteristics in the oil seal unit 2. [Figure 7] This is a schematic diagram of the oil seal unit 302 according to the first modified example. [Modes for carrying out the invention]

[0016] The oil seal unit 2 will be described with reference to Figures 1 to 3. The oil seal unit 2 seals the gap S between a first member 100 and a second member 102 that is rotatable relative to the first member 100. For example, the first member 100 and the second member 102 are a motor housing and a motor shaft, respectively. In this specification, a cylindrical coordinate system consisting of an axial direction AD, a radial direction RD, and a circumferential direction CD (see Figure 2) is defined with reference to the rotation axis A of the second member 102. The axial direction AD is the direction parallel to the rotation axis A, and its coordinate axis is defined on the rotation axis A. The radial direction RD is the direction perpendicular to the axial direction AD, and is defined by a coordinate axis with the rotation axis A as the origin. The circumferential direction CD in Figure 2 is the direction perpendicular to the axial direction AD and the radial direction RD, and is defined by a coordinate axis that revolves around the rotation axis A.

[0017] The second member 102 in Figure 1 comprises a first shaft portion 110, a second shaft portion 112, and a third shaft portion 114. The first shaft portion 110, the second shaft portion 112, and the third shaft portion 114 extend along the axial direction AD. The second shaft portion 112 extends from one end of the first shaft portion 110 along the axial direction AD to one side of the axial direction AD. One side of the axial direction AD is to the right in Figure 1. The outer diameter of the second shaft portion 112 is larger than the outer diameter of the first shaft portion 110. The third shaft portion 114 extends from one end of the second shaft portion 112 along the axial direction AD to one side of the axial direction AD. The outer diameter of the third shaft portion 114 is larger than the outer diameter of the second shaft portion 112.

[0018] The oil seal unit 2 includes a first seal portion 20 and a core metal 22. Although it is an example, the first seal portion 20 is made of an elastic body such as synthetic rubber. The first seal portion 20 and the core metal 22 extend annularly. The first seal portion 20 includes a first annular portion 30, a first cylindrical portion 32, a second annular portion 34, a seal lip portion 36, and a first dust lip 38. The outer end of the first annular portion 30 in the radial direction RD abuts against the first member 100. Hereinafter, the outside and the inside in the radial direction RD will be simply described as "outside" and "inside", respectively. The inner end of the first annular portion 30 is located outside the outer peripheral end of the first shaft portion 110 of the second member 102. The first cylindrical portion 32 extends from the inner end of the first annular portion 30 to one side in the axial direction AD. The end of the first cylindrical portion 32 on one side in the axial direction AD is located on the other side in the axial direction AD than the end of the first shaft portion 110 on one side in the axial direction AD. The other side in the axial direction AD is the left side in FIG. 1. The second annular portion 34 extends inward from the end of the first cylindrical portion 32 on one side in the axial direction AD. The inner end of the second annular portion 34 is located outside the outer end of the first shaft portion 110. A seal lip portion 36 and a first dust lip 38 are connected to the inner end of the second annular portion 34. The seal lip portion 36 extends from the inner end of the second annular portion 34 to the other side in the axial direction AD. The seal lip portion 36 has a tip portion 36A that abuts against the outer periphery of the first shaft portion 110. An annular spring 40 is provided at the tip portion 36A. The first dust lip 38 extends from the inner end of the second annular portion 34 to one side and inward in the axial direction AD. The first dust lip 38 has a tip portion 38A that abuts against the outer periphery of the first shaft portion 110.

[0019] The core metal 22 comprises a second cylindrical portion 50, a third annular portion 52, a third cylindrical portion 54, a fourth annular portion 56, a fourth cylindrical portion 58, and a fifth annular portion 60. The core metal 22 is made of metal. The third annular portion 52 and the third cylindrical portion 54 abut against one side surface of the first member 100 in the axial direction AD, and against the inner surface of the first member 100, respectively. The second cylindrical portion 50 extends from the outer end of the third annular portion 52 to one side in the axial direction AD. The third cylindrical portion 54 extends from the inner end of the third annular portion 52 to the other side in the axial direction AD. The fourth annular portion 56, the fourth cylindrical portion 58, and the fifth annular portion 60 have shapes corresponding to the first annular portion 30, the first cylindrical portion 32, and the second annular portion 34 of the first seal portion 20, respectively. The fourth annular portion 56 and the fifth annular portion 60 are in contact with one side of the axial direction AD of the first annular portion 30 and the second annular portion 34, respectively. The fourth cylindrical portion 58 is in contact with the outer surface of the first cylindrical portion 32.

[0020] The oil seal unit 2 further comprises a second dust lip 24, a disc spring 26, and a cover member 28. The second dust lip 24, the disc spring 26, and the cover member 28 extend in an annular shape. The second dust lip 24 comprises a fifth cylindrical portion 70, a sixth ring portion 72, and a sixth cylindrical portion 74. The fifth cylindrical portion 70 has a shape corresponding to the second cylindrical portion 50 of the mandrel 22. The fifth cylindrical portion 70 abuts against the inner surface of the second cylindrical portion 50. The sixth ring portion 72 extends inward from the other end of the fifth cylindrical portion 70 in the axial direction AD. The outer end of the sixth ring portion 72 abuts against one side of the third ring portion 52 of the mandrel 22 in the axial direction AD. The sixth cylindrical portion 74 extends from the inner end of the sixth ring portion 72 to one side in the axial direction AD, and then extends to one side and outward in the axial direction AD. The tip 74A of the sixth cylindrical portion 74 is in contact with the disc spring 26. For example, the sixth cylindrical portion 74 of the second dust lip 24 is made of an elastic material such as synthetic rubber. One end of the second dust lip 24 (part of the fifth cylindrical portion 70 and the sixth annular portion 72) is a fixed end fixed to the first member 100. On the other hand, the other end of the second dust lip 24 (the tip 74A of the sixth cylindrical portion 74) is a free end.

[0021] The cover member 28 includes a seventh cylindrical portion 80, a seventh annular portion 82, and an eighth cylindrical portion 84. The seventh annular portion 82 abuts against the surface on the other side in the axial direction AD of the third shaft portion 114 of the second member 102. The seventh cylindrical portion 80 extends from the outer end of the seventh annular portion 82 toward the other side in the axial direction AD. The seventh cylindrical portion 80 is located outside the first seal portion 20, the core metal 22, and the second dust lip 24. The eighth cylindrical portion 84 extends from the inner end of the seventh annular portion 82 toward the other side in the axial direction AD. The eighth cylindrical portion 84 abuts against the outer surface of the second shaft portion 112 of the second member 102. The end portion of the eighth cylindrical portion 84 on the other side in the axial direction AD is located on one side in the axial direction AD with respect to the end portion of the second shaft portion 112 on the other side in the axial direction AD.

[0022] As shown in FIG. 2, the seventh annular portion 82 has a plurality of protrusions 86 protruding toward the other side in the axial direction AD and a plurality of grooves 88 corresponding to the plurality of protrusions 86. The plurality of protrusions 86 and the plurality of grooves 88 are arranged at equal intervals in the circumferential direction CD.

[0023] As shown in FIG. 1, in the axial direction AD, the disc spring 26 is disposed between the second dust lip 24 and the cover member 28. As an example, the disc spring 26 is made of metal, resin, rubber, or the like. In the oil seal unit 2, the portion between the tip 74A of the sixth cylindrical portion 74 of the second dust lip 24 and the disc spring 26 is configured to be slidable. In order to improve the slidability between the tip 74A and the disc spring 26, a surface treatment may be performed on the surface on the other side in the axial direction AD of the disc spring 26, or an additive may be added to the disc spring 26. It can also be said that the disc spring 26 is disposed between the second dust lip 24 and the third shaft portion 114 of the second member 102. As shown in FIG. 2, a plurality of recessed cutouts 26A are provided on the outer peripheral edge of the disc spring 26. The plurality of cutouts 26A are provided at positions corresponding to the plurality of protrusions 86 and the plurality of grooves 88 of the cover member 28. The groove 88 extends outward from the position of the cutout 26A. As shown in FIG. 3, the inner end portion 86A of the protrusion 86 is disposed within the cutout 26A. The end portion 86A is spaced apart from the inner peripheral edge of the cutout 26A in the radial direction RD and the circumferential direction CD.

[0024] Referring to Figures 4 to 6, the load characteristics of the oil seal unit 2 of this embodiment and the load characteristics of the comparative example oil seal unit 202 will be explained. Figure 4 shows the comparative example oil seal unit 202. Figure 5 shows the load characteristics of the second dust lip 24 of the comparative example oil seal unit 202. Figure 6 shows the load characteristics of the second dust lip 24 and the disc spring 26 of the oil seal unit 202 of the embodiment, as well as the combined load characteristics obtained by combining the load characteristics of the second dust lip 24 and the disc spring 26. In Figures 5 and 6, the horizontal axis is displacement D [mm], and the vertical axis is load L [N]. In oil seal units 2 and 202, in order to ensure the sealing performance by the second dust lip 24 and to suppress excessive wear of the tip 74A of the second dust lip 24, it is necessary to install the oil seal units 2 and 202 so that the load acting on the second dust lip 24 is between load L1 and load L2.

[0025] First, let's describe the case where the comparative example oil seal unit 202 is used. As shown in Figure 4, the comparative example oil seal unit 202 has the same configuration as the embodiment oil seal unit 2, except that it does not have a disc spring 26. In the comparative example oil seal unit 202, the tip 74A of the sixth cylindrical portion 74 of the second dust lip 24 abuts against the seventh annular portion 82 of the cover member 28, rather than the disc spring 26.

[0026] As shown in Figure 5, the load characteristics of the second dust lip 24 are linear. That is, in the load characteristics of the second dust lip 24, the displacement D increases as the load L increases. The displacements corresponding to loads L1 and L2 in the load characteristics of the second dust lip 24 are displacements D1 and D2, respectively. As described above, in the comparative example oil seal unit 202, the tip 74A of the second dust lip 24 is in contact with the seventh annular portion 82 of the cover member 28. Therefore, in the configuration of the comparative example, in order to make the load acting on the second dust lip 24 between load L1 and load L2, it is necessary to install the oil seal unit 202 so that the displacement D of the disc spring 26 is between displacement D1 and displacement D2.

[0027] Next, we will describe the case in which the oil seal unit 2 of this embodiment is used. As shown in Figure 6, the load characteristics of the disc spring 26 are nonlinear. Specifically, the load characteristics of the disc spring 26 include a first spring characteristic region C1, a second spring characteristic region C2, and a third spring characteristic region C3. In the first spring characteristic region C1, the displacement D increases as the load L increases. The first spring characteristic region C1 is the region where the displacement D is between 0 (zero) and D3. In the second spring characteristic region C2, the displacement D decreases as the load L increases. The second spring characteristic region C2 is the region where the displacement D is between D3 and D4. In the third spring characteristic region C3, the displacement D increases as the load L increases. The third spring characteristic region C3 is the region where the displacement D is greater than or equal to D4. The load L3 at displacement D3 is the maximum value between displacement D 0 (zero) and D4. The load L4 at displacement D4 is the local minimum value between displacement D (zero) and displacement D4.

[0028] As shown in Figure 1, in the oil seal unit 2, the tip 74A of the sixth cylindrical portion 74 of the second dust lip 24 abuts against the seventh annular portion 82 of the cover member 28 via the disc spring 26. That is, the second dust lip 24 and the disc spring 26 are connected in series between the first member 100 and the second member 102 (specifically, the cover member 28). In this case, as shown in Figure 6, the load acting on the second dust lip 24 and the disc spring 26 is derived from the combined load characteristic obtained by combining the load characteristics of the second dust lip 24 and the load characteristics of the disc spring 26. The combined load characteristic includes a first combined load characteristic region C11, a second combined load characteristic region C12, and a third combined load characteristic region C13. In the first combined load characteristic region C11, the second combined load characteristic region C12, and the third combined load characteristic region C13, the displacement D increases as the load L increases. The first combined load characteristic region C11 is the region where the displacement D is between 0 (zero) and D5. The second combined load characteristic region C12 is the region where the displacement D is between D5 and D6. The third combined load characteristic region C13 is the region where the displacement D is D6 or greater. The load characteristics in the first combined load characteristic region C11 and the third combined load characteristic region C13 are linear. The slope of the load characteristics in the first combined load characteristic region C11 and the third combined load characteristic region C13 is slightly smaller than the slope of the load characteristics of the second dust lip 24. The load characteristics in the second combined load characteristic region C12 are nonlinear. The slope at each displacement within the second combined load characteristic region C12 is smaller than the slope of the load characteristics in the first combined load characteristic region C11. In the modified example, in the second combined load characteristic region C12 of the combined load characteristics, the displacement D may decrease as the load L increases. In this case, the slope of each displacement within the second combined load characteristic region C12 should be smaller than the slope of the load characteristic in the second spring characteristic region C2.

[0029] The displacements corresponding to loads L1 and L2 in the combined load characteristics are displacements D11 and D12. Therefore, in the configuration of the embodiment, in order to make the load acting on the second dust lip 24 fall between load L1 and load L2, it is necessary to install the oil seal unit 2 so that the displacement D of the second dust lip 24 and the disc spring 26 falls between displacement D11 and displacement D12. As shown in Figures 5 and 6, the first difference between displacement D12 and displacement D11 in the embodiment is greater than the second difference between displacement D2 and displacement D1 in the comparative example. With this configuration, the oil seal unit 2 can be easily installed so that the load acting on the second dust lip 24 falls within the range of load L1 and load L2.

[0030] Furthermore, in this embodiment, the rapid fluctuation of the load acting on the second dust lip 24 is suppressed. Therefore, the generation of abnormal noises that occur in response to rapid fluctuations in the load acting on the second dust lip 24 can be suppressed.

[0031] (Effects of the example) As described above, the oil seal unit 2 seals the gap S between the first member 100 and the second member 102 which is rotatable relative to the first member 100. The oil seal unit 2 includes a second dust lip 24 (an example of a "dust lip") which extends annularly along the gap S and has a fixed end fixed to the first member 100 and a free end (tip 74A) located on the second member 102 side, and a disc spring 26 disposed between the free end of the second dust lip 24 and the second member 102. The free end of the second dust lip 24 and the disc spring 26 are configured to be slidable.

[0032] In the above configuration, a disc spring 26 is positioned between the second dust lip 24 and the second member 102. That is, the second dust lip 24 and the disc spring 26 are connected in series between the first member 100 and the second member 102. In this case, as shown in Figure 6, a combined load characteristic is obtained by combining the load characteristics of the second dust lip 24 and the load characteristics of the disc spring 26. In this combined load characteristic, the range of displacement corresponding to a predetermined range is greater than the range of displacement of the second dust lip 24 alone. Therefore, the load acting on the second dust lip 24 can be easily set to a predetermined range.

[0033] Furthermore, the second dust lip 24 and the disc spring 26 are aligned along the axial direction AD.

[0034] Furthermore, the outer edge of the disc spring 26 is provided with a notch 26A that is recessed inward in the radial direction RD.

[0035] According to the above configuration, as the second member 102 rotates, liquids such as water can be discharged to the outside through the notch 26A.

[0036] Furthermore, the oil seal unit 2 is fixed to the second member 102 and further includes a cover member 28 that supports the disc spring 26. The cover member 28 is provided with a projection 86 that engages with the notch 26A.

[0037] According to the above configuration, the cover member 28 fixed to the second member 102 and the disc spring 26 rotate integrally. Therefore, relative sliding can be easily generated between the disc spring 26 and the second dust lip 24.

[0038] Furthermore, the oil seal unit 2 is fixed to the second member 102 and further includes a cover member 28 that supports the disc spring 26. The cover member 28 is provided with a groove 88 that extends radially outward from the position of the notch 26A of the disc spring 26.

[0039] According to the above configuration, in a configuration in which the oil seal unit 2 is equipped with a cover member 28, liquid such as water can be discharged to the outside through the notch 26A and groove 88 in accordance with the rotation of the second member 102.

[0040] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above.

[0041] (First Modified Example) As shown in Figure 7, the oil seal unit 302 may include a disc spring 326 positioned radially RD between the tip 338A of the first dust lip 338 and the first shaft portion 110 of the second member 102. In this modified example, the first dust lip 338 is an example of a "dust lip".

[0042] (Second variation) The disc spring 26 does not need to have a notch 26A. Also, the cover member 28 does not need to have a protrusion 86 and a plurality of grooves 88.

[0043] (Third Modification) The cover member 28 does not need to be provided with a protrusion 86. In this modification, the materials of each member are selected such that the first friction coefficient μ1 between the disc spring 26 and the cover member 28 is greater than the second friction coefficient μ2 between the second dust lip 24 and the disc spring 26. Additives or surface treatments may also be applied to the second dust lip 24 and / or the disc spring 26 so that the first friction coefficient μ1 is greater than the second friction coefficient μ2.

[0044] (Fourth Modification) The oil seal unit 2 does not need to include a cover member 28. In this modification, the outer end of the disc spring 26 abuts against the third shaft portion 114 of the second member 102. In this modification, the third shaft portion 114 of the second member 102 may be provided with a projection that engages with the notch 26A of the disc spring 26.

[0045] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of Symbols]

[0046] 2: Oil seal unit, 20: First seal part, 22: Core metal, 24: Second dust lip, 26: Disc spring, 26A: Notch, 28: Cover member, 30: First ring part, 32: First cylindrical part, 34: Second ring part, 36: Seal lip part, 36A: Tip part, 38: First dust lip, 38A: Tip part, 40: Spring, 50: Second cylindrical part, 52: Third ring part, 54: Third cylindrical part, 56: Fourth ring part, 58: Fourth cylindrical part, 60: Fifth ring part, 70: Fifth cylindrical section, 72: Sixth annular section, 74: Sixth cylindrical section, 74A: Tip, 80: Seventh cylindrical section, 82: Seventh annular section, 84: Eighth cylindrical section, 86: Protrusion, 86A: End, 88: Groove, 100: First member, 102: Second member, 110: First shaft section, 112: Second shaft section, 114: Third shaft section, 202: Oil seal unit, 302: Oil seal unit, 326: Disc spring, 338: First dust lip, 338A: Tip

Claims

1. An oil seal unit that seals the gap between a first member and a second member rotatable relative to the first member, A dust lip extending in an annular shape along the gap, having a fixed end fixed to the first member and a free end located on the second member side, A disc spring is disposed between the free end of the dust lip and the second member, Equipped with, The free end of the dust lip and the disc spring are configured to be slidable. Oil seal unit.

2. The oil seal unit according to claim 1, wherein the dust lip and the disc spring are arranged along an axial direction parallel to the rotation axis of the second member relative to the first member.

3. The oil seal unit according to claim 2, wherein the outer edge of the disc spring is provided with a notch that is recessed radially inward.

4. The second member is further equipped with a cover member that is fixed to the second member and supports the disc spring, The oil seal unit according to claim 3, wherein the cover member is provided with a protrusion that engages with the notch.

5. The second member is further equipped with a cover member that is fixed to the second member and supports the disc spring, The oil seal unit according to claim 3 or 4, wherein the cover member is provided with a groove extending radially outward from the position of the notch of the disc spring.

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