Electrolytic corrosion-resistant bearing

Abstract

This invention provides a corrosion-resistant bearing that enables both ease of installation into a housing and reduction of radial displacement of the shaft. [Solution] The corrosion-resistant bearing 10 includes an inner ring 11, an outer ring 12, a plurality of rolling elements, and an annular corrosion-resistant member 15 attached to the outer ring 12. The corrosion-resistant member 15 includes a core metal 20 fitted to the outer ring 12, and an insulating covering member 30 that covers the outer circumferential surface of the core metal 20. The core metal 20 has a cylindrical first large-diameter portion 21 that fits tightly to the axial center of the outer ring 12, a cylindrical small-diameter portion 23 with a smaller outer diameter than the first large-diameter portion 21, and a stepped portion 24 located on the first axial side of the small-diameter portion 23, between the small-diameter portion 23 and the first large-diameter portion 21. The covering member 30 has a protruding portion 32 that protrudes toward the housing 7 and is in close contact with the housing 7. The protruding portion 32 is located in a range that spans the stepped portion 24 in the axial direction.

Description

Technical Field

[0001] The present invention relates to an electric corrosion preventive bearing.

Background Art

[0002] For example, in a rolling bearing used in an electric device such as a motor, a potential difference may occur between an inner ring and an outer ring. When a potential difference occurs, an electric current flows through the rolling elements inside the rolling bearing, and there is a risk of electric corrosion occurring on the raceway surfaces of the inner ring and the outer ring. When electric corrosion occurs on the raceway surface, abnormal noise may occur during rotation, peeling of the raceway surface may occur starting from the location where electric corrosion has occurred, and the bearing life may be reduced.

[0003] In order to prevent electric corrosion, a bearing having an electric corrosion preventive member that covers the outer peripheral surface of the outer ring has been proposed (for example, see Patent Document 1). The electric corrosion preventive member has a metal core attached to the outer ring and an insulating covering member that covers the metal core.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] FIG. 11 is a cross-sectional view of a conventional electric corrosion preventive bearing. The electric corrosion preventive bearing 90 has an inner ring 91, an outer ring 92, a plurality of rolling elements 93, and an electric corrosion preventive member 94 attached to the outer ring 92 and covering the outer peripheral surface of the outer ring 92. The electric corrosion preventive member 94 has a metal core 95 fitted and attached to the outer ring 92 and an insulating covering member 96 that covers the metal core 95. In order to mount the electric corrosion preventive bearing 90 on the inner peripheral surface 991 of the housing 99, the electric corrosion preventive bearing 90 is axially approached to the housing 99 and press-fitted. Figure 12 is a cross-sectional view showing a part of a conventional anti-corrosion bearing, illustrating how the anti-corrosion member 94 is press-fitted into the housing 99.

[0006] The corrosion-resistant bearing 90 shown in Figure 11 receives a radial load from the shaft 98. To minimize the radial displacement of the shaft 98, it is desirable that the covering member 96, made of rubber or the like, be thin. However, if the covering member 96 is thin, when the corrosion-resistant member 94 is press-fitted into the housing 99 (see Figure 12), the amount of elastic deformation of the covering member 96 is small, which may make press-fitting difficult. Also, if the covering member 96 is thin, there is a possibility that the adhesive between the core metal 95 and the covering member 96 may peel off during press-fitting.

[0007] In the invention disclosed in Patent Document 1, as shown in Figure 13, the covering member 96 has a protrusion 97 that protrudes toward the housing 99. The protrusion 97 makes the covering member 96 thicker, increases the amount of elastic deformation, and facilitates the mounting of the corrosion-preventive bearing to the housing 99. However, as the covering member 96 becomes thicker, it can be elastically deformed significantly in the radial direction. Therefore, when a radial load is applied to the corrosion-preventing bearing 90, the radial displacement of the shaft 98 increases.

[0008] Regarding the corrosion-resistant bearing 90 described above, the ease of mounting to the housing 99 and the reduction of radial displacement of the shaft 98 have conventionally been inversely related. Therefore, the present invention aims to provide a corrosion-resistant bearing that enables both ease of mounting to a housing and reduction of radial displacement of the shaft. [Means for solving the problem]

[0009] The corrosion-resistant bearing of the present invention comprises an inner ring, an outer ring, a plurality of rolling elements, and an annular corrosion-resistant member attached to the outer ring and covering at least the outer surface of the outer ring, wherein the corrosion-resistant member is in contact with the housing. The electrolytic corrosion prevention member comprises a core metal that is fitted and attached to the outer ring, and an insulating covering member that covers the outer surface of the core metal. The core metal has a cylindrical large-diameter portion that fits tightly into the axial center of the outer ring, a cylindrical small-diameter portion with a smaller outer diameter than the large-diameter portion, and a stepped portion located on the first axial side of the small-diameter portion, between the small-diameter portion and the large-diameter portion. The covering member has a protruding portion that extends toward the housing and is in close contact with the housing, and the protruding portion is located in a range that spans the stepped portion in the axial direction.

[0010] The corrosion-resistant bearing of the present invention comprises an inner ring, an outer ring, a plurality of rolling elements, and an annular corrosion-resistant member attached to the inner ring and covering at least the inner circumferential surface of the inner ring, wherein the corrosion-resistant member is in contact with the shaft. The electrolytic corrosion prevention member comprises a core metal that is fitted and attached to the inner ring, and an insulating covering member that covers the inner circumferential surface of the core metal. The core metal has a cylindrical small-diameter portion that fits tightly into the axial center of the inner ring, a cylindrical large-diameter portion with a larger inner diameter than the small-diameter portion, and a stepped portion located on the first axial side of the large-diameter portion, between the large-diameter portion and the small-diameter portion. The covering member has a projection that protrudes toward the shaft and is in close contact with the shaft, and the projection is located in a range that spans the stepped portion in the axial direction. [Effects of the Invention]

[0011] According to the corrosion-resistant bearing of the present invention, the corrosion-resistant bearing is easy to install, and the amount of radial displacement of the shaft to which the inner ring is attached is suppressed. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a cross-sectional view showing one embodiment of the corrosion-resistant bearing of the present invention. [Figure 2] Figure 2 is a cross-sectional view showing a part of a corrosion-resistant bearing. [Figure 3] Figure 3 is an enlarged cross-sectional view showing the second protrusion and its surrounding area. [Figure 4] Figure 4 is a cross-sectional view showing how the corrosion-resistant bearing is pressed into the housing. [Figure 5]FIG. 5 is a cross-sectional view showing a state where the electric corrosion-preventing bearing is press-fitted into the housing. [Figure 6] FIG. 6 is a cross-sectional view showing a second form of the electric corrosion-preventing bearing. [Figure 7] FIG. 7 is a cross-sectional view showing a part of the electric corrosion-preventing bearing. [Figure 8] FIG. 8 is an enlarged cross-sectional view showing the second protrusion and its surroundings. [Figure 9] FIG. 9 is a cross-sectional view showing a state where a shaft is press-fitted into the electric corrosion-preventing bearing. [Figure 10] FIG. 10 is a cross-sectional view showing a state where a shaft is press-fitted into the electric corrosion-preventing bearing. [Figure 11] FIG. 11 is a cross-sectional view of a conventional electric corrosion-preventing bearing. [Figure 12] FIG. 12 is a cross-sectional view showing a part of a conventional electric corrosion-preventing bearing. [Figure 13] FIG. 13 is a cross-sectional view showing a part of a conventional electric corrosion-preventing bearing.

MODE FOR CARRYING OUT THE INVENTION

[0013] <SUMMARY OF THE EMBODIMENT OF THE PRESENT INVENTION> Hereinafter, the summary of the embodiment of the present invention will be listed and described. (1) The electric corrosion-preventing bearing according to the embodiment of the present invention has an inner ring, an outer ring, a plurality of rolling elements, and an annular electric corrosion-preventing member attached to the outer ring and at least covering the outer peripheral surface of the outer ring, and the electric corrosion-preventing member contacts the housing. The electric corrosion-preventing member has a core metal fitted and attached to the outer ring, and an insulating coating member covering the outer peripheral surface of the core metal. The core metal has a cylindrical large-diameter portion that fits in close contact with the axial center portion of the outer ring, a cylindrical small-diameter portion having an outer diameter smaller than that of the large-diameter portion, and a step portion located on the first axial side of the small-diameter portion and between the small-diameter portion and the large-diameter portion. The coating member has a protrusion that protrudes toward the housing side and is in close contact with the housing, and the protrusion is located in a range straddling the step portion in the axial direction.

[0014] The protruding portion of the covering member is located in a range that straddles the stepped portion of the core metal in the axial direction, and has both a thick portion and a thin portion. When mounting the corrosion-resistant bearing into the housing while moving it axially, the protruding portion slides into contact with the inner circumferential surface of the housing. In the initial stages of mounting, the thicker portion of the protruding portion is easily elastically deformed, making it easy to mount the corrosion-resistant bearing. After mounting, the thinner portion of the protruding portion is interposed between the mandrel and the housing, and the amount of elastic deformation is suppressed by this thin portion. As a result, the radial displacement of the shaft to which the inner ring is attached is suppressed.

[0015] (2) In the corrosion-resistant bearing of (1) above, the protruding portion has a first portion that covers the large diameter portion, a second portion that covers the stepped portion, and a third portion that covers the small diameter portion, wherein the thickness of the third portion is greater than the thickness of the first portion. In the protruding portion, the third portion is the thicker portion, and the first portion is the thinner portion. When mounting the corrosion-resistant bearing to the housing, in the initial stage, the protruding portion is easily elastically deformed at the third portion, making mounting easy. After mounting, the first portion of the protruding portion is interposed between the core metal and the housing, and the amount of elastic deformation is suppressed at this first portion.

[0016] (3) In the corrosion-resistant bearing of (1) or (2) above, the axial second end of the protrusion is located axially second further than the axial second end of the stepped portion. The thickness of the thick portion of the covering member is reliably ensured.

[0017] (4) In the corrosion-resistant bearing of (3) above, the first axial end of the protrusion is located radially outward of the large diameter portion. When a radial load is applied to the inner ring, rolling elements, and outer ring, the load is transmitted to the housing via the large-diameter portion of the mandrel that fits tightly to the outer ring, and the protruding portion located radially outward from the large-diameter portion. The thin portion (first portion) of the protrusion is located radially outward from the large-diameter portion of the mandrel. Elastic deformation is suppressed in the thin portion. As a result, the radial displacement of the shaft to which the inner ring is attached is suppressed.

[0018] (5) In any one of the electrolytic corrosion prevention bearings described in (1) to (4) above, the covering member has a plurality of protrusions provided at intervals in the axial direction. The spaces between the multiple protrusions form recesses. To mount the corrosion-resistant bearing into the housing, a lubricant such as oil is applied to the outer surface of the covering member. In this case, the lubricant accumulates in the recesses, and this lubricant in the recesses facilitates the mounting of the corrosion-resistant bearing into the housing.

[0019] (6) Another embodiment of the present invention provides a corrosion-resistant bearing comprising an inner ring, an outer ring, a plurality of rolling elements, and an annular corrosion-resistant member attached to the inner ring and covering at least the inner circumferential surface of the inner ring, wherein the corrosion-resistant member is in contact with the shaft. The electrolytic corrosion prevention member comprises a core metal that is fitted and attached to the inner ring, and an insulating covering member that covers the inner circumferential surface of the core metal. The core metal has a cylindrical small-diameter portion that fits tightly into the axial center of the inner ring, a cylindrical large-diameter portion with a larger inner diameter than the small-diameter portion, and a stepped portion located on the first axial side of the large-diameter portion, between the large-diameter portion and the small-diameter portion. The covering member has a projection that protrudes toward the shaft and is in close contact with the shaft, and the projection is located in a range that spans the stepped portion in the axial direction.

[0020] The protruding portion of the covering member is located in a range that straddles the stepped portion of the core metal in the axial direction, and has both a thick portion and a thin portion. When mounting the corrosion-resistant bearing onto a shaft while moving it axially, the protruding portion slides into contact with the outer surface of the shaft. In the initial stages of mounting, the thicker portion of the protruding portion is easily elastically deformed, making it easy to mount the corrosion-resistant bearing. After mounting, the thinner portion of the protruding portion is interposed between the mandrel and the shaft, and the amount of elastic deformation is suppressed by this thin portion. As a result, the radial displacement of the shaft to which the inner ring is attached is suppressed.

[0021] (7) In the corrosion-resistant bearing of (6) above, the protruding portion has a first portion that covers the small diameter portion, a second portion that covers the stepped portion, and a third portion that covers the large diameter portion, wherein the thickness of the third portion is greater than the thickness of the first portion. In the protruding portion, the third portion is the thicker portion, and the first portion is the thinner portion. When mounting the corrosion-resistant bearing onto the shaft, in the initial stage, the protruding portion is easily elastically deformed at the third portion, making mounting easy. After mounting, the first portion of the protruding portion is interposed between the core metal and the shaft, and the amount of elastic deformation is suppressed at this first portion.

[0022] (8) In the corrosion-resistant bearing of (6) or (7) above, the axial second end of the protrusion is located axially second further than the axial second end of the stepped portion. The thickness of the thick portion of the covering member is reliably ensured.

[0023] (9) In the corrosion-resistant bearing of (8) above, the axial first end of the protrusion is located radially inward of the small diameter portion. When a radial load is applied to the inner ring, rolling elements, and outer ring, the load is transmitted to the shaft via the small-diameter portion of the mandrel that fits tightly to the inner ring, and the protrusion located radially inward of that small-diameter portion. The thin portion (first portion) of the protrusion is located radially inward of the small-diameter portion of the core. The amount of elastic deformation is suppressed in the thin portion. As a result, the amount of radial displacement of the shaft is suppressed.

[0024] (10) In any one of the electrolytic corrosion prevention bearings described in (6) to (9) above, the covering member has a plurality of protrusions provided at intervals in the axial direction. The spaces between the multiple protrusions form recesses. To mount the corrosion-resistant bearing onto the shaft, a lubricant such as oil is applied to the inner surface of the covering member. In this case, the lubricant accumulates in the recesses, and this lubricant in the recesses facilitates the mounting of the corrosion-resistant bearing onto the shaft.

[0025] <Details of Embodiments of the Invention> [Overall configuration of the corrosion-resistant bearing] Figure 1 is a cross-sectional view showing one embodiment of the corrosion-resistant bearing of the present invention. The corrosion-resistant bearing 10 shown in Figure 1 is a rolling bearing and has an inner ring 11, an outer ring 12, a plurality of rolling elements, and an annular cage 14 that holds the plurality of rolling elements. The rolling elements in this embodiment are balls 13. The corrosion-resistant bearing 10 has an annular corrosion-resistant member 15. The corrosion-resistant member 15 is attached to the outer ring 12, which is a raceway ring. When attached to the outer ring 12, the corrosion-resistant member 15 covers the cylindrical outer surface 16 of the outer ring 12 and also covers the side surface 17 of the outer ring 12.

[0026] The corrosion-resistant bearing 10 is attached to the housing 7 by press-fitting the outer ring 12, to which the corrosion-resistant member 15 is fitted, onto the inner circumferential surface 701 of the housing 7. The corrosion-resistant member 15 is in contact with the housing 7. The housing 7 is the mating member to which the corrosion-resistant bearing 10 is attached. The corrosion-resistant bearing 10 rotatably supports the shaft 8 relative to the housing 7.

[0027] Multiple balls 13 are arranged between a cylindrical inner ring 11 and a cylindrical outer ring 12, and the central axis of the inner ring 11 and the central axis of the outer ring 12 coincide. This central axis becomes the central axis C of the corrosion-resistant bearing 10. The direction along the central axis C and the direction parallel to the central axis C are defined as the axial direction of the corrosion-resistant bearing 10. The direction perpendicular to the central axis C is defined as the radial direction of the corrosion-resistant bearing 10. The direction along the circle centered on the central axis C is defined as the circumferential direction of the corrosion-resistant bearing 10. In each figure, including Figure 1, the right side is the "first axial side," and the left side is the "second axial side."

[0028] The inner ring 11 has a raceway surface on which the ball 13 rolls and makes contact. The raceway surface of the inner ring 11 is a circumferential groove 41 with a concave arc cross-section. The outer ring 12 has a raceway surface on which the ball 13 rolls and makes contact. The raceway surface of the outer ring 12 is a circumferential groove 42 with a concave arc cross-section. The outer circumferential surface 16 of the outer ring 12 has a first outer circumferential surface 161 with a larger outer diameter, a second outer circumferential surface 162 with a smaller outer diameter than the first outer circumferential surface 161, and a third outer circumferential surface 163 located between the first outer circumferential surface 161 and the second outer circumferential surface 162. The third outer circumferential surface 163 is an inclined surface that widens in diameter toward the first axial direction.

[0029] [Electrolytic corrosion prevention member 15] The electrolytic corrosion prevention member 15 has a core metal 20 and a covering member 30. Figure 2 is a cross-sectional view showing a part of the electrolytic corrosion prevention bearing 10. The mandrel 20 is fitted and attached to the outer ring 12. The mandrel 20 has a cylindrical portion 201 located radially outward from the outer ring 12 and an annular portion 202 located on the second axial side of the outer ring 12. The cylindrical portion 201 has a first large diameter portion 21, a second large diameter portion 22, a small diameter portion 23, and a stepped portion 24.

[0030] The first large-diameter portion 21 is cylindrical. The inner diameter of the first large-diameter portion 21 is smaller than the outer diameter of the axial center portion 121 of the outer ring 12 (outer diameter of the first outer peripheral surface 161). The first large-diameter portion 21 fits tightly to the axial center portion 121 of the outer ring 12. The second large-diameter portion 22 is cylindrical. The second large-diameter portion 22 is located on the first axial side of the first large-diameter portion 21. The inner diameter of the second large-diameter portion 22 is larger than the outer diameter of the first outer peripheral surface 161 of the outer ring 12. A gap e1 is provided between the second large-diameter portion 22 and the first outer peripheral surface 161 of the outer ring 12. The small-diameter portion 23 is cylindrical. The small-diameter portion 23 is located second axially from the first large-diameter portion 21. The small-diameter portion 23 has a smaller outer diameter than the first large-diameter portion 21. The inner diameter of the small-diameter portion 23 is larger than the outer diameter of the second outer circumferential surface 162 of the outer ring 12. A gap e2 is provided between the small-diameter portion 23 and the second outer circumferential surface 162 of the outer ring 12.

[0031] The stepped portion 24 is located between the small diameter portion 23 and the first large diameter portion 21. In other words, the stepped portion 24 is located on the first axial side of the small diameter portion 23. The stepped portion 24 is a short portion in the axial direction and has an inclined shape (tapered shape) that widens toward the first axial side. A gap e3 is provided between the stepped portion 24 and the outer circumferential surface 16 (third outer circumferential surface 163) of the outer ring 12. In this embodiment, the thickness (radial dimension) of the first large-diameter portion 21, the second large-diameter portion 22, and the small-diameter portion 23 is all the same "t1". The stepped portion 24 may also have the same thickness t1, but since the core metal 20 is formed by plastic deformation, the stepped portion 24 may have a different thickness from t1.

[0032] The covering member 30 covers the outer circumferential surface 29 of the core metal 20. The covering member 30 is made of rubber and is elastic and electrically insulating. The covering member 30 is formed by vulcanization molding. The covering member 30 is molded using the core metal 20 as an insert in the mold. The covering member 30 has a cylindrical portion 301 that covers the cylindrical portion 201 of the core metal 20 from the radially outer side. The covering member 30 has an annular portion 302 that covers the annular portion 202 of the core metal 20 from the axial second side.

[0033] The covering member 30 has a first end portion 34 that covers the second large diameter portion 22 of the core metal 20 from the first axial side. The inner circumferential surface of the first end portion 34 on the outer ring 12 side and the inner circumferential surface of the second large diameter portion 22 of the core metal 20 are located along the same virtual cylindrical plane centered on the central axis C (see Figure 1). In other words, the inner circumferential surface of the end portion 34 and the inner circumferential surface of the second large diameter portion 22 are flush.

[0034] The covering member 30 has protrusions (31, 32) that project toward the housing 7. In this embodiment, the covering member 30 has a first protrusion 31 on the axial first side and a second protrusion 32 on the axial second side. Each of the protrusions 31 and 32 is a portion of the cylindrical portion 301 of the covering member 30 that projects radially outward. Each of the protrusions 31 and 32 is in close contact with the inner circumferential surface 701 of the housing 7. Each of the protrusions 31 and 32 is continuous in the circumferential direction and is cylindrical. A recess 33 is formed between the first protrusion 31 and the second protrusion 32.

[0035] The first projection 31 is located in a range that spans the small stepped portion (first stepped portion) 25 connecting the first large diameter portion 21 and the second large diameter portion 22 of the core metal 20 in the axial direction. The outer circumferential surface 311 of the first projection 31 has a shape that follows a cylindrical surface centered on the central axis C (see Figure 1). The second projection 32 is located in a range that spans the large step portion (second step portion) 24 connecting the first large diameter portion 21 and the small diameter portion 23 of the core metal 20 in the axial direction. The outer circumferential surface 321 of the second projection 32 has a shape that follows a cylindrical surface centered on the central axis C (see Figure 1). The outer diameter of the outer surface 311 of the first projection 31 and the outer diameter of the outer surface 321 of the second projection 32 are the same.

[0036] Figure 3 is an enlarged cross-sectional view showing the second projection 32 and its surrounding area. The second projection 32 has a first portion 36 that covers the first large-diameter portion 21 of the core metal 20, a second portion 37 that covers the stepped portion 24, and a third portion 38 that covers the small-diameter portion 23. The outer circumferential surfaces of the first portion 36, the second portion 37, and the third portion 38 are located along the same virtual cylindrical surface K1 centered on the central axis C (see Figure 1).

[0037] The first axial side of the first portion 36 is the recess 33. The covering member 30 has a second end portion 35 on the second axial side. The second end portion 35 has a smaller outer diameter than the third portion 38. Therefore, the second projection 32 has an inclined portion 39 located between the second end portion 35 and the third portion 38. The outer circumferential surface 391 of the inclined portion 39 is an inclined surface that decreases in diameter toward the second axial side. The outer circumferential surface (inclined surface) 391 of the inclined portion 39 connects the outer circumferential surface 351 of the second end portion 35 and the outer circumferential surface 381 of the third portion 38. Figure 3 shows the boundaries between the first part 36 and the second part 37, the boundary between the second part 37 and the third part 38, the boundary between the third part 38 and the inclined portion 39, and the boundary between the inclined portion 39 and the second end portion 35, each indicated by dashed lines.

[0038] As described above, the second projection 32 is located in a range that straddles the stepped portion 24 of the core metal 20 in the axial direction. For this reason, the second projection 32 has a thick portion and a thin portion in the radial direction. Specifically, the third portion 38 is the thick portion, and the first portion 36 is the thin portion. The thickness t38 of the third portion 38 is greater than the thickness t36 of the first portion 36 (t38 > t36).

[0039] The axial second end P1 of the second projection 32 is located axially second further than the axial second end Q1 of the second step portion 24 of the core metal 20. Note that end P1 is the position on the outer circumferential surface 321 of the second projection 32, and end Q1 is the position on the outer circumferential surface of the second step portion 24. The first axial end P2 of the second projection 32 is located radially outward from the first large-diameter portion 21 of the core metal 20. In other words, end P2 is located further axially to the first side than the first axial end Q2 of the second stepped portion 24. Note that end P2 is located on the outer circumferential surface 321 of the second projection 32.

[0040] The outer diameter D38 of the third portion 38 is larger than the inner diameter D7 of the inner circumferential surface 701 of the housing 7. Therefore, when the corrosion-resistant bearing 10, which has the corrosion-resistant member 15, is mounted on the housing 7, the second projection 32, including the third portion 38, undergoes compressive elastic deformation in the radial direction. The second projection 32, including the third portion 38, is in close contact with the housing 7. Half the difference between the inner diameter D7 and the outer diameter D38 represents the amount of elastic deformation of the second projection 32 (third portion 38), which corresponds to the interference fit of the second projection 32 (third portion 38) with respect to the housing 7. This interference fit is preferably greater than 0 millimeters and less than or equal to 0.1 millimeters.

[0041] The thickness t38 of the third portion 38 is preferably 1.0 mm or more and 1.5 mm or less. If the thickness t38 is too large (exceeds 1.5 mm), it may be necessary to reduce the thickness of the axial second side portion of the outer ring 12, which may result in insufficient thickness. The thickness t36 of the first part 36 is preferably 0.3 mm or more and 0.6 mm or less. If the thickness t36 is too small (less than 0.3 mm), it may be difficult to mold the covering member 30.

[0042] The outer diameter D35 of the second end portion 35 is smaller than the inner diameter D7 of the inner circumferential surface 701 of the housing 7. Therefore, before the corrosion-resistant bearing 10, which has the corrosion-resistant member 15, is press-fitted into the housing 7, the second end portion 35 is inserted with a radial gap between it and the inner circumferential surface 701. The second end portion 35 functions as a guide surface before press-fitting.

[0043] Figures 4 and 5 are cross-sectional views showing how the corrosion-resistant bearing 10 is press-fitted into the housing 7. As shown in Figure 4, when the corrosion-resistant bearing 10 is mounted into the housing 7 while being moved axially, the second projection 32 slides against the inner circumferential surface 701 of the housing 7 while undergoing elastic deformation. In the initial mounting stage shown in Figure 4, the second projection 32 is easily elastically deformed at its thicker third portion 38. In other words, a large amount of elastic deformation in the radial direction is obtained at the third portion 38. For this reason, mounting the corrosion-resistant bearing 10 is easy.

[0044] As the press-fitting process progresses, as shown in Figure 5, the third portion 38 is pushed axially to the first side by the frictional force between it and the inner circumferential surface 701 of the housing 7. The core metal 20 in this embodiment has a stepped portion 24. The second portion 37 of the covering member 30 covers this stepped portion 24. The second portion 37, together with the third portion 38, is also pushed axially to the first side. However, the axial movement of the third portion 38 and the second portion 37 relative to the core metal 20 in the first side is suppressed by the stepped portion 24, which has an inclined shape. Therefore, during press-fitting, the covering member 30 (second protrusion 32) is less likely to shift position relative to the core metal 20. This makes it possible to prevent the adhesive between the core metal 20 and the covering member 30 from peeling off.

[0045] Once the press-fitting is complete and the corrosion-resistant bearing 10 is mounted on the housing 7 (see Figure 2), the first portion 36, which is the thin part of the second projection 32, is interposed between the first large-diameter portion 21 of the core metal 20 and the inner circumferential surface 701 of the housing 7. The corrosion-resistant bearing 10, mounted between the housing 7 and the shaft 8, receives a radial load from the shaft 8. The covering member 30 then undergoes elastic deformation in the radial direction, but the amount of elastic deformation is small in the thin portion of the covering member 30. In other words, the amount of elastic deformation is suppressed by the thin first portion 36. Therefore, the amount of radial displacement of the shaft 8 to which the inner ring 11 is attached is suppressed.

[0046] More specifically, when a radial load is applied to the bearing portion 18, which includes the inner ring 11, the balls 13, and the outer ring 12, the load is transmitted to the housing 7 via the first large-diameter portion 21 of the mandrel 20, which fits tightly to the outer ring 12, and the second projection 32 located radially outward from the first large-diameter portion 21. As described above (see Figure 3), the axial first end P2 of the second projection 32 is located radially outward from the first large-diameter portion 21 of the mandrel 20. In other words, the first portion 36, which is the thin part of the second projection 32, is located radially outward from the first large-diameter portion 21. As a result, the amount of elastic deformation is suppressed in the thin part, and the amount of radial displacement of the shaft 8 is suppressed.

[0047] As described above, the covering member 30 has a plurality of (two) protrusions 31, 32 that protrude toward the housing 7 and are in close contact with the housing 7. These protrusions 31, 32 are spaced apart in the axial direction. The space between the two protrusions 31, 32 forms a recess 33. The recess 33 may or may not be in contact with the inner circumferential surface 701 of the housing 7. To install the corrosion-resistant bearing 10 into the housing 7 by press-fitting, a lubricant such as oil is applied to the outer surface of the covering member 30. In this case, the lubricant is stored in the recess 33. This lubricant in the recess 33 is utilized to facilitate the installation of the corrosion-resistant bearing 10.

[0048] [Second form of the corrosion-resistant bearing 10] In the first embodiment shown in Figure 1, the anti-corrosion member 15 is attached to the outer ring 12. Figure 6 is a cross-sectional view showing the second embodiment of the anti-corrosion bearing 10. In the second embodiment of the anti-corrosion bearing 10, the anti-corrosion member 15 is attached to the inner ring 11.

[0049] The corrosion-resistant bearing 10 shown in Figure 6 is a rolling bearing and comprises an inner ring 11, an outer ring 12, a plurality of rolling elements, and an annular cage 14 that holds the plurality of rolling elements. In this embodiment, the rolling elements are balls 13. The corrosion-resistant bearing 10 has an annular corrosion-resistant member 15. The corrosion-resistant member 15 is attached to the inner ring 11, which is a raceway ring. When attached to the inner ring 11, the corrosion-resistant member 15 covers the cylindrical inner circumferential surface 19 of the inner ring 11 and also covers the side surface 191 of the inner ring 11.

[0050] The corrosion-resistant bearing 10 is attached to the shaft 8 by press-fitting the shaft 8 into the inner circumference of the corrosion-resistant member 15 mounted on the inner ring 11. The corrosion-resistant member 15 is in contact with the shaft 8. The shaft 8 is the mating member to which the corrosion-resistant bearing 10 is attached. The corrosion-resistant bearing 10 rotatably supports the shaft 8 with respect to the housing 7.

[0051] The inner ring 11 has a raceway surface on which the ball 13 rolls and makes contact. The raceway surface of the inner ring 11 is a circumferential groove 41 with a concave arc cross-section. The outer ring 12 has a raceway surface on which the ball 13 rolls and makes contact. The raceway surface of the outer ring 12 is a circumferential groove 42 with a concave arc cross-section. The inner circumferential surface 19 of the inner ring 11 has a first inner circumferential surface 191 with a smaller inner diameter, a second inner circumferential surface 192 with a larger inner diameter than the first inner circumferential surface 191, and a third inner circumferential surface 193 located between the first inner circumferential surface 191 and the second inner circumferential surface 192. The third inner circumferential surface 193 is an inclined surface that decreases in diameter toward the first axial direction.

[0052] [Second form of electrolytic corrosion prevention member 15] The anti-corrosion member 15 has a core metal 120 and a covering member 130. Figure 7 is a cross-sectional view showing a part of the anti-corrosion bearing 10. The mandrel 120 is fitted and attached to the inner ring 11. The mandrel 120 has a cylindrical portion 201 located radially inward of the inner ring 11 and an annular portion 202 located on the second axial side of the inner ring 11. The cylindrical portion 201 has a first small diameter portion 71, a second small diameter portion 72, a large diameter portion 73, and a stepped portion 74.

[0053] The first small-diameter portion 71 is cylindrical. The outer diameter of the first small-diameter portion 71 is larger than the inner diameter of the axial center portion 111 of the inner ring 11 (the inner diameter of the first inner circumferential surface 191). The first small-diameter portion 71 fits tightly into the axial center portion 111 of the inner ring 11. The second small-diameter portion 72 is cylindrical. The second small-diameter portion 72 is located on the first axial side of the first small-diameter portion 71. The outer diameter of the second small-diameter portion 72 is smaller than the inner diameter of the first inner circumferential surface 191 of the inner ring 11. A gap e1 is provided between the second small-diameter portion 72 and the first inner circumferential surface 191 of the inner ring 11. The large-diameter portion 73 is cylindrical. The large-diameter portion 73 is located axially second to the first small-diameter portion 71. The large-diameter portion 73 has a larger inner diameter than the first small-diameter portion 71. The outer diameter of the large-diameter portion 73 is smaller than the inner diameter of the second inner circumferential surface 192 of the inner ring 11. A gap e2 is provided between the large-diameter portion 73 and the second inner circumferential surface 192 of the inner ring 11.

[0054] The stepped portion 74 is located between the large-diameter portion 73 and the first small-diameter portion 71. In other words, the stepped portion 74 is located on the first axial side of the large-diameter portion 73. The stepped portion 74 is a short portion in the axial direction and has an inclined shape (tapered shape) that decreases in diameter toward the first axial side. A gap e3 is provided between the stepped portion 74 and the inner circumferential surface 19 (third inner circumferential surface 193) of the inner ring 11. In this embodiment, the thickness (radial dimension) of the first small-diameter portion 71, the second small-diameter portion 72, and the large-diameter portion 73 are all the same "t1". The stepped portion 74 may also have the same thickness t1, but since the core metal 120 is formed by plastic deformation, the stepped portion 74 may have a different thickness from t1.

[0055] The covering member 130 covers the inner circumferential surface 79 of the core metal 120. The covering member 130 is made of rubber and is elastic and electrically insulating. The covering member 130 is formed by vulcanization molding. The covering member 130 is molded using the core metal 120 as an insert in the mold. The covering member 130 has a cylindrical portion 301 that covers the cylindrical portion 201 of the core metal 120 from the radially inner side. The covering member 130 also has an annular portion 302 that covers the annular portion 202 of the core metal 120 from the axial second side.

[0056] The covering member 130 has a first end portion 84 that covers the second small diameter portion 72 of the core metal 120 from the first axial side. The outer circumferential surface of the first end portion 84 on the inner ring 11 side and the outer circumferential surface of the second small diameter portion 72 of the core metal 120 are located along the same virtual cylindrical plane centered on the central axis C (see Figure 6). In other words, the outer circumferential surface of the end portion 84 and the outer circumferential surface of the second small diameter portion 72 are flush.

[0057] The covering member 130 has protrusions (131, 132) that project toward the shaft 8. In this embodiment, the covering member 130 has a first protrusion 131 on the first axial side and a second protrusion 132 on the second axial side. Each of the protrusions 131 and 132 is a portion of the cylindrical portion 301 of the covering member 130 that projects radially inward. Each of the protrusions 131 and 132 is in close contact with the outer circumferential surface 81 of the shaft 8. Each of the protrusions 131 and 132 is continuous in the circumferential direction and is cylindrical. A recess 133 is formed between the first protrusion 131 and the second protrusion 132.

[0058] The first projection 131 is located in a range that spans the small stepped portion (first stepped portion) 26 connecting the first small diameter portion 71 and the second small diameter portion 72 of the core metal 120 in the axial direction. The inner circumferential surface 312 of the first projection 131 has a shape that follows a cylindrical surface centered on the central axis C (see Figure 6). The second projection 132 is located in a range that spans the large stepped portion (second stepped portion) 74 connecting the first small-diameter portion 71 and the large-diameter portion 73 of the core metal 120 in the axial direction. The inner circumferential surface 322 of the second projection 132 has a shape that follows a cylindrical surface centered on the central axis C (see Figure 6). The inner diameter of the inner circumferential surface 312 of the first projection 131 is the same as the inner diameter of the inner circumferential surface 322 of the second projection 132.

[0059] Figure 8 is an enlarged cross-sectional view showing the second projection 132 and its surrounding area. The second projection 132 has a first portion 86 that covers the first small diameter portion 71 of the core metal 120, a second portion 87 that covers the stepped portion 74, and a third portion 88 that covers the large diameter portion 73. The inner circumferential surfaces of the first portion 86, the second portion 87, and the third portion 88 are located along the same virtual cylindrical surface K2 centered on the central axis C (see Figure 6).

[0060] The first axial side of the first portion 86 is the recess 133. The covering member 130 has a second end portion 85 on its second axial side. The second end portion 85 has a larger inner diameter than the third portion 88. Therefore, the second projection 132 has an inclined portion 89 located between the second end portion 85 and the third portion 88. The inner circumferential surface 891 of the inclined portion 89 is an inclined surface that widens in diameter toward the second axial side. The inner circumferential surface (inclined surface) 891 of the inclined portion 89 connects the inner circumferential surface 851 of the second end portion 85 and the inner circumferential surface 881 of the third portion 88. Figure 8 shows the boundaries between the first part 86 and the second part 87, the boundary between the second part 87 and the third part 88, the boundary between the third part 88 and the inclined section 89, and the boundary between the inclined section 89 and the second end 85, each indicated by dashed lines.

[0061] As described above, the second projection 132 is located in a range that straddles the stepped portion 74 of the core metal 120 in the axial direction. For this reason, the second projection 132 has a thick portion and a thin portion in the radial direction. Specifically, the third portion 88 is the thick portion, and the first portion 86 is the thin portion. The thickness t88 of the third portion 88 is greater than the thickness t86 of the first portion 86 (t88 > t86).

[0062] The axial second end P1 of the second projection 132 is located axially second further than the axial second end Q1 of the second step portion 74 of the core metal 120. Note that end P1 is located on the inner circumferential surface 322 of the second projection 132, and end Q1 is located on the inner circumferential surface of the second step portion 74. The first axial end P2 of the second projection 132 is located radially inward of the first small-diameter portion 71 of the core metal 120. In other words, end P2 is located further axially to the first side than the first axial end Q2 of the second stepped portion 74. Note that end P2 is located on the inner circumferential surface 322 of the second projection 132.

[0063] The inner diameter D88 of the third portion 88 is smaller than the outer diameter D8 of the outer circumferential surface 81 of the shaft 8. Therefore, when the corrosion-resistant bearing 10, which has the corrosion-resistant member 15, is mounted on the shaft 8, the second projection 132, including the third portion 88, undergoes compressive elastic deformation in the radial direction. The second projection 132, including the third portion 88, is in close contact with the shaft 8. Half the difference between the inner diameter D88 and the outer diameter D8 represents the amount of elastic deformation of the second projection 132 (third portion 88), which corresponds to the interference fit of the second projection 132 (third portion 88) with respect to the shaft 8. This interference fit is preferably greater than 0 millimeters and less than or equal to 0.1 millimeters.

[0064] The thickness t88 of the third portion 88 is preferably 1.0 mm or more and 1.5 mm or less. If the thickness t88 is too large (exceeds 1.5 mm), it may be necessary to reduce the thickness of the axial second side portion of the inner ring 11, which may result in insufficient thickness. The thickness t86 of the first portion 86 is preferably 0.3 mm or more and 0.6 mm or less. If the thickness t86 is too small (less than 0.3 mm), it may be difficult to mold the covering member 130.

[0065] The inner diameter D85 of the second end 85 is larger than the outer diameter D8 of the outer circumferential surface 81 of the shaft 8. Therefore, before the shaft 8 is press-fitted into the corrosion-resistant bearing 10 having the corrosion-resistant member 15, the second end 85 is inserted with a radial gap between it and the outer circumferential surface 81. The second end 85 functions as a guide surface before press-fitting.

[0066] Figures 9 and 10 are cross-sectional views showing the process of pressing the shaft 8 into the corrosion-resistant bearing 10. As shown in Figure 9, when mounting the corrosion-resistant bearing 10 onto the shaft 8 while moving it axially, the second projection 132 slides into contact with the outer circumferential surface 81 of the shaft 8 while undergoing elastic deformation. In the initial mounting stage shown in Figure 9, the second projection 132 is easily elastically deformed at its thicker third portion 88. In other words, a large amount of elastic deformation in the radial direction is obtained at the third portion 88. For this reason, mounting the corrosion-resistant bearing 10 is easy.

[0067] As the press-fitting process progresses, as shown in Figure 10, the third portion 88 is pushed axially to the first side by the frictional force between it and the outer circumferential surface 81 of the shaft 8. The core metal 120 in this embodiment has a stepped portion 74. The second portion 87 of the covering member 130 covers this stepped portion 74. The second portion 87, together with the third portion 88, is also pushed axially to the first side. However, the axial movement of the third portion 88 and the second portion 87 relative to the core metal 120 is suppressed by the stepped portion 74, which has an inclined shape. Therefore, during press-fitting, the covering member 130 (second protrusion 132) is less likely to shift position relative to the core metal 120. This makes it possible to prevent the adhesive between the core metal 120 and the covering member 130 from peeling off.

[0068] Once the press-fitting is complete and the corrosion-resistant bearing 10 is mounted on the shaft 8 (see Figure 7), the first portion 86, which is the thin part of the second projection 132, is interposed between the first small-diameter portion 71 of the core metal 120 and the outer circumferential surface 81 of the shaft 8. The corrosion-resistant bearing 10, mounted between the housing 7 and the shaft 8, receives a radial load from the shaft 8. The covering member 130 then undergoes elastic deformation in the radial direction, but the amount of elastic deformation is small in the thin portion of the covering member 130. In other words, the amount of elastic deformation is suppressed by the thin first portion 86. Therefore, the amount of radial displacement of the shaft 8 to which the inner ring 11 is attached is suppressed.

[0069] More specifically, when a radial load is applied to the bearing portion 18, which includes the inner ring 11, the balls 13, and the outer ring 12, the load is transmitted to the shaft 8 via the first small-diameter portion 71 of the mandrel 120, which fits tightly to the inner ring 11, and the second projection 132 located radially inward of the first small-diameter portion 71. As described above (see Figure 8), the axial first end P2 of the second projection 132 is located radially inward of the first small-diameter portion 71 of the mandrel 120. In other words, the first portion 86, which is the thin part of the second projection 132, is located radially inward of the first small-diameter portion 71. As a result, the amount of elastic deformation is suppressed in the thin part, and the amount of radial displacement of the shaft 8 is suppressed.

[0070] As described above, the covering member 130 has a plurality of (two) protrusions 131, 132 that protrude toward the shaft 8 and are in close contact with the shaft 8. These protrusions 131, 132 are spaced apart in the axial direction. The space between the two protrusions 131, 132 forms a recess 133. The recess 133 may or may not be in contact with the outer circumferential surface 81 of the shaft 8. To install the shaft 8 into the corrosion-resistant bearing 10 by press-fitting, a lubricant such as oil is applied to the inner circumferential surface of the covering member 130. In this case, the lubricant is stored in the recess 33. This lubricant in the recess 33 is utilized to facilitate the installation of the corrosion-resistant bearing 10.

[0071] [First form and second form] As described above, the corrosion-resistant bearing 10 of the first embodiment (Figure 1) and the second embodiment (Figure 6) are easy to mount on the housing 7 or shaft 8, and the radial displacement of the shaft 8 is suppressed. In the first and second embodiments described above, the rolling element is a ball 13, but the rolling element of the corrosion-preventing bearing 10 of the present invention may be something other than a ball 13, and may be a roller.

[0072] 〔others〕 The embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments described above and includes all modifications within the scope equivalent to the configurations described in the claims. [Explanation of Symbols]

[0073] 7 Housing 8 axes 10. Corrosion-resistant bearings 11 Inner circle 12 Outer ring 13 Balls (rolling bodies) 15. Electrolytic corrosion prevention material 20 Mandrel 21 First large diameter section (large diameter section) 23 Small diameter section 24 Step section 30 Covering member 32 Second protrusion (protrusion) 33 Recess 36 Part 1 37 Second part 38 Third part 39 Slope 71 First small diameter section (small diameter section) 73 Large diameter section 74 Step part 86 Part 1 87 Second part 88 Third part 89 Slope 111 Axial center of the inner ring 120 Mandrel 121 Axial center of the outer ring 130 Covering member 132 Second protrusion (protrusion) 133 Recess P1 end P2 end Q1 end Q2 end

Claims

1. A corrosion-resistant bearing comprising an inner ring, an outer ring, a plurality of rolling elements, and an annular corrosion-resistant member attached to the outer ring and covering at least the outer surface of the outer ring, wherein the corrosion-resistant member is in contact with the housing, The aforementioned electrolytic corrosion prevention member is A core metal that is fitted and attached to the outer ring, It comprises an insulating covering member that covers the outer surface of the core metal, The aforementioned core metal is A cylindrical large-diameter portion that fits tightly into the axial center of the outer ring, A cylindrical small-diameter portion with an outer diameter smaller than the aforementioned large-diameter portion, The small diameter portion has a stepped portion located on the first axial side of the small diameter portion, between the small diameter portion and the large diameter portion. The covering member is It has a protruding portion that extends toward the housing side and is in close contact with the housing, The aforementioned protrusion is located in a range that spans the stepped portion in the axial direction. Electrolytic corrosion-resistant bearing.

2. The protruding portion has a first portion that covers the large diameter portion, a second portion that covers the stepped portion, and a third portion that covers the small diameter portion. The thickness of the third portion is greater than the thickness of the first portion. The corrosion-resistant bearing according to claim 1.

3. The second axial end of the protrusion is located further axially than the second axial end of the stepped portion. The corrosion-resistant bearing according to claim 1 or claim 2.

4. The first axial end of the protrusion is located radially outward from the large diameter portion. The corrosion-resistant bearing according to claim 3.

5. The covering member has a plurality of protrusions spaced apart in the axial direction, as described in claim 1 or claim 2.

6. A corrosion-resistant bearing comprising an inner ring, an outer ring, a plurality of rolling elements, and an annular corrosion-resistant member attached to the inner ring and covering at least the inner circumferential surface of the inner ring, wherein the corrosion-resistant member is in contact with the shaft, The aforementioned electrolytic corrosion prevention member is A core metal that is fitted and attached to the inner ring, It comprises an insulating covering member that covers the inner circumferential surface of the core metal, The aforementioned core metal is A cylindrical small-diameter portion that fits tightly into the axial center of the inner ring, A cylindrical large-diameter portion with an inner diameter larger than the aforementioned small-diameter portion, The large diameter portion has a stepped portion located on the first axial side of the large diameter portion, between the large diameter portion and the small diameter portion. The covering member is It has a protruding portion that extends outwards from the shaft and is in close contact with the shaft, The aforementioned protrusion is located in a range that spans the stepped portion in the axial direction. Electrolytic corrosion-resistant bearing.

7. The protruding portion has a first portion that covers the small diameter portion, a second portion that covers the stepped portion, and a third portion that covers the large diameter portion. The thickness of the third portion is greater than the thickness of the first portion. The corrosion-resistant bearing according to claim 6.

8. The second axial end of the protrusion is located further axially than the second axial end of the stepped portion. The corrosion-resistant bearing according to claim 6 or claim 7.

9. The first axial end of the protrusion is located radially inward of the small diameter portion. The corrosion-resistant bearing according to claim 8.

10. The covering member has a plurality of protrusions spaced apart in the axial direction, as described in claim 6 or claim 7, for the corrosion-resistant bearing.

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