Vibration isolation structure

Abstract

The present invention provides a vibration-damping structure that suppresses vibrations caused by the bearing while also suppressing the misalignment of the bearing's rotation center relative to the center of the bore. [Solution] A vibration damping structure 12 comprising: a bearing 40 having a shaft 20 extending along an axis XC, an inner ring 42 fitted with the shaft 20, and an outer ring 44 positioned radially outward from the inner ring 42; a support 30 supporting the bearing 40, having an outer surface 30a facing axially, a hole 32 having a hole wall 34a that opens on the outer surface 30a and fits with the outer ring 44, and a recess 50 that is concave with respect to the hole wall 34a of the hole 32 and opens axially; and a vibration damping member 60 positioned between the recess 50 and the outer ring 44 and in contact with only a part of the outer ring 44 when viewed from the axial direction.

Description

Technical Field

[0001] The present invention relates to a vibration isolation structure.

Background Art

[0002] A bearing device around a drive shaft of an automobile or the like, in which an elastic body (elastomer) is provided around a rolling bearing, is known (for example, Patent Document 1). The drive shaft transmits power from a power device or a transmission to a wheel tire. The power device includes, for example, a motor or an internal combustion engine. In such a bearing device, the elastic body provided around the rolling bearing functions as a vibration damping member that attenuates vibrations caused by the rotation of the rolling bearing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a vibration isolation member made of an elastomer is arranged so as to surround the outer periphery of a bearing fitted in a hole portion, there is a risk that the amount of deviation of the rotation center of the bearing with respect to the center of the hole portion increases.

[0005] The present disclosure aims to provide a vibration isolation structure capable of suppressing vibrations caused by a bearing and suppressing the deviation of the rotation center of the bearing with respect to the center of the hole portion.

Means for Solving the Problems

[0006] An aspect of the present disclosure includes a shaft body extending along an axis, a rolling bearing, an inner ring that fits with the shaft body, an outer ring that is arranged radially outside the inner ring, and a rolling bearing having the above, A support for the aforementioned rolling bearing, The outer surface facing the axial direction, The aforementioned outer surface has a hole that is open and has a first peripheral wall that fits with the outer ring, The recess of the hole is concave with respect to the first peripheral wall and opens in the axial direction, A support having, A vibration-damping member is positioned between the recess and the outer ring, and contacts only a portion of the outer ring when viewed from the axial direction. It is a vibration-damping structure that has [the following characteristics]. [Effects of the Invention]

[0007] According to this disclosure, it is possible to suppress vibrations caused by the bearing while suppressing the displacement of the bearing's rotation center relative to the center of the bore. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view of the vibration isolation structure according to the embodiment. [Figure 2] This is a cross-sectional view of a vibration-damping structure according to an embodiment. [Figure 3] This is a front view of a modified vibration isolation structure. [Figure 4] This is a front view of a modified vibration isolation structure. [Modes for carrying out the invention]

[0009] The embodiments relating to this disclosure will be described below with reference to the drawings. The scale of the drawings is not necessarily accurate, and some features may be exaggerated or omitted. The vibration isolation structure described herein is applicable to a structure (not shown) around a rotating shaft in an automobile or the like. The rotating shaft is, for example, a drive shaft located around a power unit or transmission. The power unit includes, for example, a motor or an internal combustion engine.

[0010] In the following explanation, the direction along the axial direction of a rolling bearing is called the X direction. The direction toward the bottom surface of a recessed fitting that opens axially is called the -X direction. The direction opposite to the -X direction is called the +X direction. The vertical direction (up and down direction) when a rolling bearing is positioned so that the X direction is parallel to the horizontal direction is called the Y direction. The direction vertically upward in this case is called the +Y direction. The direction vertically downward in this case is called the -Y direction. The direction perpendicular to the X and Y directions in this case is called the Z direction. The direction away from the central axis of the rolling bearing is called the radially outward direction. The direction toward the central axis of the rolling bearing is called the radially inward direction.

[0011] As shown in Figures 1 and 2, the structure 10 according to this embodiment includes a shaft 20, a bearing 40, a support 30, and a vibration-damping member 60. The shaft 20, bearing 40, support 30, and vibration-damping member 60 constitute a vibration-damping structure 12.

[0012] The shaft 20 is cylindrical, extending uniformly along axis XC, as shown in Figure 2. Axis XC is a virtual centerline along the X-axis direction. Axis XC extends horizontally. The shaft 20 has side portions 22. The shaft 20 is connected to a drive unit (not shown), which includes a motor and / or a transmission. The shaft 20 is rotatable around axis XC by the drive unit. The shaft 20 is positioned in a predetermined position relative to a bearing 40 or support 30 (described later) by known positioning means (not shown). The shaft 20 is formed from, for example, steel for mechanical structures.

[0013] The bearing 40 is a rolling bearing provided around the shaft 20. The rolling bearing according to this disclosure is a radial bearing. The bearing 40 is a ball bearing. The rolling bearing according to this disclosure is not limited to a ball bearing as long as it is a radial bearing. The bearing 40 may be a roller bearing. The bearing 40 may be a tapered roller bearing or an angular contact ball bearing. The bearing 40 is positioned and supported inside the hole 32 of the support body 30, which will be described later. The bearing 40 has a plurality of rolling elements 40a, an inner ring 41, and an outer ring 44. The rolling elements 40a of the bearing 40, which is a ball bearing, are spherical. As shown in FIG. 1, the plurality of rolling elements 40a are arranged annularly around the shaft body 20 along the rolling surfaces 43 and 47 of the inner ring 41 and the outer ring 44, which will be described later.

[0014] The inner ring 41 is annular and fits with the shaft body 20. The inner ring 41 is disposed between the rolling element 40a and the shaft body 20. The inner ring 41 has an inner diameter portion 41a, an inner end face 42, and a first rolling surface 43. The inner diameter portion 41a is cylindrical and faces the radially inner side of the annular inner ring 41. The inner diameter portion 41a fits with the side surface portion 22 of the shaft body 20. Thereby, the inner ring 41 can rotate integrally with the shaft body 20 around the axis XC. As shown in FIG. 2, the inner end face 42 extends radially outward from the ends on both axial sides of the inner diameter portion 41a. The inner end face 42 has an inner end face 42a and an inner end face 42b. The inner end face 42a faces the +X side. The inner end face 42b faces the -X side. The first rolling surface 43 is formed radially outside the inner diameter portion 41a and is annular facing the radially outside. In the bearing 40, which is a ball bearing, the first rolling surface 43 is substantially semi-circular along the surface of the spherical rolling element 40a in the cross-sectional view shown in FIG. 2.

[0015] The outer ring 44 is annular and is disposed radially outside the inner ring 41 with the rolling element 40a interposed therebetween. The outer ring 44 is disposed between the rolling element 40a and the support 30. The outer ring 44 does not contact the inner ring 41. The outer ring 44 has an outer diameter portion 44a, an outer end face 45, and a second rolling surface 47. The outer diameter portion 44a is cylindrical and faces the radially outer side of the annular outer ring 44. The outer diameter portion 44a fits with the hole portion 32 of the support 30. The outer end face 45 extends radially inward from the ends on both axial sides of the outer diameter portion 44a. The outer end face 45 has an outer end face 45a and an outer end face 45b. The outer end face 45a faces the +X side. The outer end face 45b faces the -X side. The second rolling surface 47 is formed radially inward of the outer diameter portion 44a and is an annular shape facing radially inward. In the bearing 40 which is a ball bearing, the second rolling surface 47 is substantially semi-circular along the surface of the rolling element 40a which is spherical in a cross-sectional view shown in FIG. 1.

[0016] The rolling element 40a, the inner ring 41, and the outer ring 44 are formed of, for example, carbon steel for machine structures. The bearing 40 is assembled with an internal clearance formed between the rolling element 40a, the inner ring 41, and the outer ring 44.

[0017] The support 30 supports the shaft body 20 via the bearing 40. The support 30 is formed of, for example, steel material for machine structures. The support 30 has an outer surface 30a, a hole portion 32, and a recess 50. The outer surface 30a faces the +X direction.

[0018] The hole portion 32 is a cylindrical shape penetrating the support 30 in the X direction. The hole portion 32 has a large diameter portion 34, a small diameter portion 35, and a step surface 36. The large diameter portion 34 is a cylindrical hole opening at the outer surface 30a. The large diameter portion 34 fits with the outer diameter portion 44a of the bearing 40. The large diameter portion 34 is an example of a fitting portion. The support 30 supports the bearing 40 at the large diameter portion 34 of the hole portion 32. The large diameter portion 34 has a hole wall 34a. The hole wall 34a is the cylindrical surface of the large diameter portion 34. The hole wall 34a faces radially inward. The hole wall 34a opens at the outer surface 30a. The hole wall 34a fits with the outer diameter portion 44a of the bearing 40. The hole wall 34a is an example of a first peripheral wall. The small diameter portion 35 is a cylindrical hole formed on the side farther from the outer surface 30a than the large diameter portion 34. The small diameter portion 35 opens at a step surface 36 described later. The small diameter portion 35 is concentric with the large diameter portion 34. The diameter of the small diameter portion 35 is larger than the diameter of the shaft body 20 and smaller than the diameter of the large diameter portion 34. The small diameter portion 35 opens the inner end surface 42b of the bearing 40 fitted to the large diameter portion 34. The stepped surface 36 is planar, connecting the large-diameter portion 34 and the small-diameter portion 35. That is, the stepped surface 36 is provided between the large-diameter portion 34 and the small-diameter portion 35. The stepped surface 36 faces the +X side. When the bearing 40 is positioned in the hole portion 32, the stepped surface 36 faces the outer end face 45b of the outer ring 44. The stepped surface 36 is an example of the first opposing portion. In the vibration isolation structure 12 of the structure 10, the stepped surface 36 overlaps only with the outer end face 45 in the axial direction. That is, the stepped surface 36 does not face the inner end face 42b of the inner ring 41.

[0019] As shown in Figure 1, the recess 50 is provided on the +Y side of the large diameter portion 34 and is groove-shaped, concave to the hole wall 34a. As shown in Figure 2, the recess 50 opens on the outer surface 30a. That is, the recess 50 opens in the +X direction. The recess 50 is provided on a part of the opening edge of the large diameter portion 34. The recess 50 is concave to the outer surface 30a. As shown in Figures 1 and 2, the recess 50 has a groove bottom 52, a pair of groove walls 55, and a groove depth 56. The groove bottom 52 faces radially inward. That is, the groove bottom 52 faces the outer ring 44 side of the bearing 40. The groove bottom 52 is an example of a second peripheral wall. In the embodiment, the groove bottom 52 is arc-shaped in a front view from the axial direction, as shown in Figure 1. In the cross-sectional view shown in Figure 2, the groove bottom 52 of the embodiment is inclined linearly such that the length between the groove bottom 52 and the axis XC increases as it moves in the -X direction. That is, the length between the groove bottom 52 and the axis XC increases as it moves away from the outer surface 30a. The groove bottom 52 is in contact with the outward-facing surface 62 of the vibration-damping member 60, which will be described later. As shown in Figure 1, the pair of groove walls 55 connect the ends on both sides of the groove bottom 52 as viewed from the axial direction to the hole wall 34a of the large diameter portion 34. The pair of groove walls 55 in this embodiment extend in the -Y direction from the edges on both sides of the groove bottom 52 in the Z direction. The pair of groove walls 55 in this embodiment face each other in the Z direction. The pair of groove walls 55 each face and contact the pair of side surfaces 65 of the vibration-damping member 60. The groove depth 56 is the -X side end of the recess 50. The groove depth 56 faces the +X direction. The groove depth 56 is in contact with the first thrust surface 66 of the vibration damping member 60. The groove depth 56 is an example of a second opposing portion. The groove depth 56 is substantially flush with the stepped surface 36.

[0020] The vibration-damping member 60 is positioned between the recess 50 of the support 30 and the outer ring 44 of the bearing 40. In the vibration-damping structure 12 of this embodiment, a single vibration-damping member 60 is positioned. As shown in Figure 1, the vibration-damping member 60 contacts only a portion of the outer ring 44 in a front view from the axial direction. By contacting the outer ring 44, the vibration-damping member 60 suppresses the transmission of vibrations caused by the rotation of the bearing 40 to the support 30. As shown in Figures 1 and 2, the vibration-damping member 60 has an outward-facing surface 62, an inward-facing surface 63, a pair of side surfaces 65, a first thrust surface 66, and a second thrust surface 67. The outward-facing surface 62 faces radially outward. The outward-facing surface 62 follows the groove bottom 52 of the recess 50. In this embodiment, the outward-facing surface 62 is arc-shaped in a front view taken from the axial direction, as shown in Figure 1. In the cross-sectional view shown in Figure 2, the outward-facing surface 62 is linearly inclined such that the length between the outward-facing surface 62 and the axis XC increases as it moves in the -X direction. The outward-facing surface 62 is in contact with the groove bottom 52 of the recess 50. The outward-facing surface 62 is an example of the outer periphery. The inward-facing surface 63 faces radially inward. The inward-facing surface 63 is aligned with the outer diameter portion 44a of the bearing 40. In this embodiment, the inward-facing surface 63 is arc-shaped when viewed from the axial direction, as shown in Figure 1. The inward-facing surface 63 is in contact with the outer diameter portion 44a of the bearing 40. The pair of side surfaces 65 connect the ends on both sides of the outward-facing surface 62 and the inward-facing surface 63 as viewed from the axial direction, as shown in Figure 1. In this embodiment, the pair of side surfaces 65 each face in the Z direction. The pair of side surfaces 65 each face and contact the pair of groove walls 55 of the recess 50. The first thrust surface 66 faces the -X side. As shown in Figure 2, the first thrust surface 66 connects the -X-side ends of the outward-facing surface 62 and the inward-facing surface 63. The first thrust surface 66 is in contact with the depth 56 of the groove of the recess 50. The second thrust surface 67 faces the +X side. The second thrust surface 67 connects the +X-side ends of the outward-facing surface 62 and the inward-facing surface 63.

[0021] The vibration-damping member 60 is formed of an elastomer. The elastomer is preferably, for example, EPDM (ethylene propylene diene rubber), acrylic rubber (ACM), nitrile rubber (NBR), or fluororubber (FKM).

[0022] The vibration-damping member 60 positioned in the recess 50 overlaps the outer ring 44 of the bearing 40 in the radial direction in the cross-sectional view shown in Figure 2. That is, the axial position of the vibration-damping member 60 overlaps with the entire outer ring 44 (length in the X direction). However, the axial position of the vibration-damping member 60 according to this disclosure does not necessarily have to overlap with the entire outer ring 44.

[0023] The vibration-damping member 60 positioned in the recess 50 has an overlap with respect to the outer ring 44 of the bearing 40. However, the vibration-damping member 60 according to this disclosure does not necessarily have to have an overlap with respect to the outer ring 44 of the bearing 40.

[0024] The vibration-damping member 60 undergoes elastic deformation upon contact with the bearing 40. At this time, the vibration-damping member 60 applies an elastic force to the outer ring 44 of the bearing 40 due to the elastic deformation. In this embodiment, the vibration-damping member 60 applies an elastic force directed in the -Y direction only to the outer ring 44. That is, the resultant force of the elastic forces applied from the vibration-damping member 60 acts vertically downward on the outer ring 44 of the bearing 40.

[0025] (Mechanism of Action and Effects) Next, the operation and effects of the vibration-damping structure 12 of the embodiment will be described. The dimensional accuracy of articles formed from elastomers, such as the vibration-damping member 60, is generally worse than that of the bearing 40 and the support 30. Furthermore, articles formed from elastomers undergo elastic deformation when assembled into a vibration-damping structure. The rate of dimensional change due to elastic deformation of articles formed from elastomers is greater than that of the bearing 40 and the support 30. Therefore, when the outer ring 44 of the bearing 40 is surrounded circumferentially by the vibration-damping member and assembled into the hole of the support, there is a risk that the amount of displacement of the rotation center of the bearing 40 relative to the center of the hole will increase. On the other hand, the vibration-damping member 60 of the vibration-damping structure 12 contacts only a portion of the outer ring 44 when viewed from the axial direction. At this time, the outer diameter portion 44a of the outer ring 44 further fits and contacts the hole wall 34a of the hole 32. Therefore, the amount of displacement of the rotation center of the bearing 40 due to contact with the vibration-damping member 60 is smaller than when the vibration-damping member surrounds the outer ring 44 in the circumferential direction. Thus, the vibration-damping structure 12 having the vibration-damping member 60 can suppress vibrations caused by the bearing 40 while suppressing the displacement of the rotation center of the bearing 40 relative to the center of the hole 32.

[0026] The distance between the groove bottom 52 of the recess 50 and the outward-facing surface 62 of the vibration-damping member 60 and the axis XC increases as it moves away from the outer surface 30a. Therefore, the vibration-damping structure 12 can prevent the vibration-damping member 60, which is positioned between the recess 50 and the bearing 40, from falling out of the recess 50.

[0027] The axial position of the vibration-damping member 60 overlaps with the entire outer ring 44. That is, the contact area of ​​the vibration-damping member 60 with the outer ring 44 is larger than in the case where the vibration-damping member overlaps with only a part of the outer ring 44 in the axial direction. Therefore, the vibration-damping structure 12 can effectively suppress the transmission of vibrations from the bearing 40 to the support 30.

[0028] The vibration-damping member 60 positioned in the recess 50 has a tolerance for contact with the outer ring 44 of the bearing 40. In this case, the vibration-damping performance of the vibration-damping member 60 with respect to the bearing 40 is improved. Therefore, the vibration-damping structure 12 can more effectively suppress the transmission of vibrations from the bearing 40 to the support 30.

[0029] The bearing 40 is fitted to the shaft 20 with its end faces 42 and 45 oriented horizontally. At this time, due to the action of gravity, an imbalance occurs in the internal clearance of the bearing 40 between the vertically upper side and the vertically lower side. This increases the amount of displacement of the rotation center of the bearing 40. The resultant force of the elastic forces applied by the vibration-damping member 60 to the outer ring 44 of the bearing 40 acts in a vertically downward direction. At this time, the resultant force of the elastic forces presses the outer ring vertically downward so as to reduce the internal gap on the vertically upward side of the bearing 40. As a result, the amount of displacement of the rotation center of the bearing 40 decreases as the bias in the internal gap of the bearing 40 between the vertically upward and vertically downward sides decreases. Therefore, the vibration-damping structure 12 can suppress the displacement of the rotation center of the bearing 40 that is fitted with the shaft body 20 that extends in the horizontal direction.

[0030] As described above, an embodiment of the present invention has been explained as an example, but the present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements are possible within the scope of the technical idea of ​​the present invention.

[0031] In the vibration isolation structure 12 of the embodiment, a single vibration isolation member 60 is provided. However, the vibration isolation structure of this disclosure may have multiple vibration isolation members, as shown in the vibration isolation structures 212 and 312 in Figures 3 and 4. A vibration isolation structure having multiple vibration isolation members can more effectively suppress the transmission of vibrations from the bearing 40 to the support 30. In a vibration-damping structure having multiple vibration-damping members, it is preferable that the resultant force of the elastic forces applied to the outer ring 44 of the bearing 40 by the vibration-damping members acts in a vertically downward direction.

[0032] The vibration isolation structure 212 shown in Figure 3 has two vibration isolation members 60. Specifically, the support body 230 of the vibration isolation structure 212 has a recess 250 provided on the -Y side of the large diameter portion 34, compared to the support body 30 of the vibration isolation structure 12. The recess 250 has a structure in which the recess 50 is mirrored in the Y direction around the axis XC. The two vibration isolation members 60 are positioned between the outer ring 44 of the bearing 40 and the two recesses 50 and 250, respectively.

[0033] The vibration isolation structure 312 shown in Figure 4 has 12 vibration isolation members 360. Specifically, the support 330 of the vibration isolation structure 312 has 12 recesses 350 instead of the recesses 50 of the support 30. As shown in Figure 4, the recesses 350 are semicircular and groove-shaped, concave relative to the hole wall 34a of the support 330 when viewed from the axial direction. The 12 recesses 350 are arranged around the opening edge of the large diameter portion 34 at equal intervals from each other in the circumferential direction. The vibration-damping member 360 is semicircular in a front view from the axial direction. The 12 vibration-damping members 360 are positioned between the outer ring 44 of the bearing 40 and each of the 12 recesses 350.

[0034] In this embodiment, the length between the groove bottom 52 of the recess 50 and the outward-facing surface 62 of the vibration-damping member 60 and the axis XC increases as it moves away from the outer surface 30a of the support 30. However, the length between the second peripheral wall of the recess and the outer periphery of the vibration-damping member and the axis XC according to this disclosure may be uniform in the axial direction.

[0035] In the vibration isolation structure according to this disclosure, it is preferable that the resultant force of the elastic force applied to the outer ring 44 of the bearing 40 by the vibration isolation member acts in the vertical downward direction. However, in the vibration isolation structure according to this disclosure, the resultant force of the elastic force applied to the outer ring 44 of the bearing 40 by the vibration isolation member does not have to have a vertical component. [Examples]

[0036] To demonstrate the vibration isolation effect of the vibration isolation structure described herein, hammering tests were performed on the structures of the embodiments and comparative examples described herein and evaluated. In the hammering tests, the maximum value of the vibration transmission coefficient to the support, caused by the impact applied to the shaft of each structure by hammering, was measured and evaluated. The structure of the embodiment has the vibration-damping structure 212 described above. The comparative structure lacks the recesses 50, 250 and the two vibration-damping members 60 compared to the structure of the embodiment. In the hammering test described above, when the index of the maximum vibration transmission rate measured in the comparative example was set to 1.0, the index of the maximum vibration transmission rate measured in the embodiment was 0.38. From this evaluation result, it can be confirmed that the structure with the vibration isolation structure of the embodiment has a superior effect on the transmission of vibrations from the rolling bearings to the support compared to the comparative example without vibration isolation members. In other words, the vibration isolation structure of the embodiment can suppress the transmission of vibrations from the shaft body through the rolling bearings to the support. [Explanation of symbols]

[0037] 10 Structure 12. Vibration-damping structure 20 Axis Body 30 Support 32 Hole 34 Large diameter section 34a Hollow wall (an example of the first peripheral wall) 36. Stepped surface (an example of the first opposing part) 40. Bearings (an example of rolling bearings) 40a Rolling element 41 Inner circle 41a Inner diameter part 42 Inner end face 43 First rolling surface 44 Outer ring 44a Outer diameter 45 Outer end face 47 Second rolling surface 50 recesses 52. Bottom of the trench (an example of the second peripheral wall) 56. Inside the groove (an example of the second opposing section) 60 Vibration Isolator 62 Outward-facing surface (an example of the outer periphery)

Claims

1. A shaft extending along the axis, It is a rolling bearing, An inner ring that fits into the aforementioned shaft body, An outer ring is positioned radially outward from the inner ring, A rolling bearing having, A support for the aforementioned rolling bearing, The outer surface facing the axial direction, The aforementioned outer surface has a hole that is open and has a first peripheral wall that fits with the outer ring, The recess of the hole is concave with respect to the first peripheral wall and opens in the axial direction, A support having, A vibration-damping member is positioned between the recess and the outer ring, and contacts only a portion of the outer ring when viewed from the axial direction. A vibration-damping structure having the following characteristics.

2. The recess has a second circumferential wall facing the outer ring side in the radial direction, The vibration-damping member has an outer periphery facing the second peripheral wall, The vibration isolation structure according to claim 1, wherein the length between the second peripheral wall and the outer peripheral portion and the axis increases as it moves away from the outer surface.

3. The hole has a first opposing portion that is in contact with the outer ring in the axial direction, The recess has a second opposing portion that is in contact with the vibration-damping member in the axial direction, and the second opposing portion is substantially flush with the first opposing portion. The vibration isolation structure according to claim 1 or 2, wherein the axial position of the vibration isolation member overlaps with the entire outer ring.

4. The vibration-damping structure according to any one of claims 1 to 3, wherein the vibration-damping member has a tightening allowance with respect to the outer ring.

5. The support has a plurality of recesses, The vibration isolation structure according to any one of claims 1 to 4, further comprising a plurality of vibration isolation members corresponding to a plurality of recesses.

6. The aforementioned shaft body extends horizontally, The vibration-damping member applies an elastic force to the outer ring, The vibration-damping structure according to any one of claims 1 to 5, wherein the resultant force of the elastic forces acts vertically downward on the outer ring.

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