Creep-resistant bearing

Abstract

The objective is to provide a creep-resistant bearing that can reduce fretting wear while suppressing the occurrence of creep. [Solution] The creep-resistant bearing (bearing 100) according to the present invention comprises an outer ring 110, an inner ring 120, rolling elements (balls 130) that roll between the outer ring 110 and the inner ring 120, and a sleeve 140 that is fitted onto the outer circumferential surface 112 of the outer ring 110 (which is the fixed ring) or the inner circumferential surface 122 of the inner ring 120 (which is the fixed ring) when one of the outer ring 110 or the inner ring 120 is the fixed ring. The sleeve 140 has thick-walled portions 142 that contact the fixed ring at both axial ends and a thin-walled portion 144 that does not contact the fixed ring in the axial center, and a hollow portion 150 is formed between the thin-walled portion 144 and the fixed ring when the sleeve 140 is fitted onto the fixed ring.

Description

Technical Field

[0001] The present invention relates to a creep-resistant bearing.

Background Art

[0002] In the case of a bearing having a structure in which it is fitted into a housing and a shaft is inserted into the inner ring of the bearing so that the inner ring rotates together with the shaft, outer ring creep may occur. As an example, when a load is applied to the bearing, the outer ring raceway portion is distorted by the rolling element load within the load zone. This distortion also affects the outer diameter of the outer ring, and the distortion of the outer diameter surface of the outer ring propagates in the moving direction of the rolling elements along with the revolution motion of the rolling elements. Such distortion propagation causes the outer ring to move relative to the housing, which is so-called outer ring distortion creep.

[0003] For example, Patent Document 1 discloses "a rolling bearing including an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a cage for holding the plurality of rolling elements, wherein one of the inner ring and the outer ring is a rotating ring and the other is a fixed ring".

[0004] The rolling bearing of Patent Document 1 is described as follows: "An annular groove for creep suppression is formed on the fitting surface with the mating member to which the fixed ring is attached. The annular groove has a groove bottom portion and a pair of tapered surface portions extending from both axial sides of the groove bottom portion toward the fitting surface side and widening the groove width as they go. The cross-sectional shape of the tapered surface portion in the cross-section including the bearing center line is a linear shape inclined with respect to the fitting surface." According to Patent Document 1, "it is possible to relieve the local increase in the contact surface pressure caused by the contact between the fixed ring and the mating member, and even if creep occurs in the fixed ring, wear is less likely to progress."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In the configuration described in Patent Document 1, the surface pressure at the edge of the annular groove increases, leading to increased fretting wear. Furthermore, in a configuration where an annular groove is provided on the outer ring (or inner ring) as in Patent Document 1, the rigidity of the outer ring (or inner ring) decreases, resulting in a reduction in bearing life due to raceway deformation.

[0007] In view of these problems, the present invention aims to provide a creep-resistant bearing that can reduce fretting wear while suppressing the occurrence of creep. [Means for solving the problem]

[0008] To solve the above problems, a typical configuration of the creep-resistant bearing according to the present invention comprises an outer ring, an inner ring, rolling elements that roll between the outer ring and the inner ring, and a sleeve that is fitted to the outer circumferential surface of the outer ring which is the fixed ring or the inner circumferential surface of the inner ring which is the fixed ring when one of the outer ring or the inner ring is a fixed ring and the other is a rotating ring, wherein the sleeve has thick-walled portions that abut against the fixed ring at both axial ends and a thin-walled portion that does not abut against the fixed ring at the axial center, and a hollow portion is formed between the thin-walled portion and the fixed ring when the sleeve is fitted onto the fixed ring.

[0009] It is preferable that multiple grooves extending in the axial direction are arranged on the mating surface between the thickened portion and the fixed ring.

[0010] It is preferable that the surface of the thin-walled portion on the fixed wheel side has a rounded shape.

[0011] The thin-walled section described above should ideally be curved so that its center is raised. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a creep-resistant bearing that can reduce fretting wear while suppressing the occurrence of creep. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram illustrating the creep-resistant bearing according to this embodiment. [Figure 2] This is a perspective view of the sleeve. [Figure 3] This diagram illustrates other shapes of sleeves. [Figure 4] This diagram illustrates the bearing of this embodiment fitted into the housing. [Figure 5] This diagram illustrates other shapes of sleeves. [Figure 6] This diagram illustrates a creep-resistant bearing according to another embodiment. [Modes for carrying out the invention]

[0014] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely examples to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0015] Figure 1 is a diagram illustrating a creep-resistant bearing (hereinafter referred to as bearing 100) according to this embodiment. As shown in Figure 1, the bearing 100 of this embodiment comprises an outer ring 110, an inner ring 120, and balls 130 which are rolling elements that roll between them.

[0016] Bearings are often used with one being a fixed ring and the other being a rotating ring, and creep occurs in the fixed ring. In the following description, it will be described assuming that the outer ring is the fixed ring fixed to the housing (counterpart member). The case where the inner ring is the fixed ring will be described later using FIG. 6.

[0017] As a feature of the present embodiment, the bearing 100 further includes a sleeve 140 externally fitted to the outer peripheral surface 112 of the outer ring 110. The sleeve 140 is a member in which a pair of thick portions 142 and a thin portion 144 disposed therebetween are integrally formed. The thick portions 142 are disposed at both axial ends and are portions that contact the outer peripheral surface 112 of the outer ring 110. The thin portion 144 is disposed at the central portion in the axial direction and is a portion that does not contact the outer peripheral surface 112 of the outer ring 110.

[0018] The sleeve 140 is a member made of metal or resin. As the metal, for example, SPCC, SUJ2, brass, etc. can be preferably used. As the resin, for example, PPS can be mentioned.

[0019] As shown in FIG. 1, in the bearing 100 of the present embodiment, by externally fitting the sleeve 140 to the outer ring 110, a hollow portion 150 is formed between the thin portion 144 and the outer peripheral surface 112 of the outer ring 110. According to such a configuration, even when distortion occurs on the outer peripheral surface 112 of the outer ring 110 during rotation of the bearing 100, the position where the distortion occurs corresponds to the hollow portion 150 of the sleeve 140, so that the distortion of the outer peripheral surface 112 of the outer ring 110 can be prevented from propagating to the housing (not shown). Therefore, it is possible to suppress the occurrence of creep caused by the propagation of distortion.

[0020] Also, according to the bearing 100 of the present embodiment, the bearing 100 is in surface contact with the housing on the outer peripheral surface 144b of the sleeve 140. That is, the bearing 100 of the present embodiment has a flat contact surface with the housing and no edges. Thereby, the occurrence of fretting wear due to an increase in surface pressure at the edge can be preferably suppressed.

[0021] Furthermore, according to the structure of the bearing 100 of the present embodiment, the above-described effects can be obtained without providing annular grooves in the outer ring, inner ring, etc. as in the prior art. Therefore, compared with the structure in which annular grooves are provided in the outer ring, inner ring, etc., high rigidity can be ensured in the outer ring 110 and the inner ring 120, and thus the bearing 100 can be made to have a longer life. Also, by making the width of the hollow portion 150 wider, anti-creep properties can be obtained regardless of the direction of the load.

[0022] Note that the sleeve 140 may be press-fitted or clearance-fitted to the outer ring 110, but rubber or the like may also be disposed on the inner peripheral surface of the thick-walled portion 142 and fitted. In the case of rubber fitting, the sleeve 140 can be fixed to the outer ring 110, and it is possible to prevent follow-up creep and distortion creep caused by the movement of the sleeve 140.

[0023] Furthermore, in order to suppress wear between the sleeve 140 and the housing, the sleeve 140 may be provided with a coating that reduces friction. For example, it is preferable to form a solid lubricant film containing fluorine. When coating the outer peripheral surface 112 of the outer ring 110, it is necessary to perform masking so that the coating liquid does not adhere to other than the outer peripheral surface. However, since the sleeve 140 can be coated entirely, the coating liquid can be applied without masking, and the work is easy.

[0024] Figure 2 is a perspective view of the sleeve 140. As shown in Figure 2, in the inner peripheral surface 142a (the fitting surface between the sleeve 140 and the outer ring 110) of the thick-walled portion 142 of the sleeve 140, a plurality of grooves 146 extending in the axial direction are arranged. According to such a structure, the propagation of distortion from the outer ring 110 to the sleeve 140 can be cut, and the effect of preventing creep can be enhanced.

[0025] Figure 3 is a diagram illustrating another shape of the sleeve. From Figure 3 onwards, for elements common to the components of the bearing 100 in Figure 1, the same reference numerals are used and the description is omitted. The bearing 100 in Figure 3 includes a sleeve 240 in place of the sleeve 140 in Figure 1.

[0026] The sleeve 240 is a component integrally molded from a pair of thick-walled portions 242 and a thin-walled portion 244 positioned between them. The thick-walled portions 242 are located at both ends in the axial direction and are the parts that abut against the outer circumferential surface 112 of the outer ring 110. The thin-walled portion 244 is located in the axial center and is the part that does not abut against the outer circumferential surface 112 of the outer ring 110.

[0027] In Figure 1, the sleeve 140 has a flat inner surface 144a of the thin-walled portion 144 (the cross-sectional shape of the hollow portion 150 is rectangular), whereas in Figure 3, the sleeve 240 has a rounded shape, or curved surface, on the inner surface 244a of the thin-walled portion 244 (the surface on the outer ring 110 side, which is the fixed ring). With this configuration, it is possible to obtain the same effect as when using the sleeve 140 in Figure 1.

[0028] Furthermore, by making the inner circumferential surface 244a rounded, the cross-section of the thick-walled portion 242 becomes thicker towards the thin-walled portion 244. This makes it possible to increase the rigidity against loads applied from the outer ring 110, thereby improving the durability of the sleeve.

[0029] Figure 4 illustrates the state in which the bearing 100 of this embodiment is fitted into the housing 104. When the sleeve 140 is fitted to the outer ring 110 shown in Figure 1 using a clearance fit, the sleeve 140 can maintain its shape.

[0030] In contrast, when the bearing 100 is fitted into the housing 104, as shown in Figure 4, the thin-walled portion 144 of the sleeve 140 may deform and bend toward the hollow portion 150, potentially forming a gap G. This would reduce the contact area between the sleeve 140 and the housing 104, increasing the surface pressure and potentially diminishing the aforementioned effect.

[0031] Figure 5 illustrates other shapes of the sleeve. Figure 5(a) illustrates the state in which the bearing 100 is not fitted into the housing 104. Figure 5(b) illustrates the state in which the bearing 100 is fitted into the housing 104.

[0032] The bearing 100 in Figure 5(a) is equipped with a sleeve 340 instead of the sleeve 140 in Figure 1. The sleeve 340 is a component integrally molded from a pair of thick-walled portions 342 and a thin-walled portion 344 positioned between them. The thick-walled portions 342 are located at both ends in the axial direction and are the parts that abut against the outer circumferential surface 112 of the outer ring 110. The thin-walled portion 344 is located in the axial center and is the part that does not abut against the outer circumferential surface 112 of the outer ring 110.

[0033] In Figure 1, the sleeve 140 had a flat outer surface 144b of the thin-walled portion 144. In contrast, the sleeve 340 illustrated in Figure 5(a) has an outer surface 344b of the thin-walled portion 344 that curves outward (away from the outer ring 110) with its center bulging.

[0034] With the above configuration, even if the thin-walled portion 344 bends toward the hollow portion 150 as shown in Figure 5(b), the center C of the outer peripheral surface 344b of the thin-walled portion 344, which is curved outward, will contact the housing 104. Therefore, it is possible to suppress the reduction in the contact area between the sleeve 340 and the housing 104.

[0035] Figure 6 illustrates a creep-resistant bearing (hereinafter referred to as bearing 100A) according to another embodiment. In bearing 100A shown in Figure 6, the shaft 102 does not rotate, and the inner ring 120 is a fixed ring. The outer ring 110 is a rotating ring, and for example, a gear 106 is fitted to it.

[0036] The bearing 100A further comprises a sleeve 140A that is fitted onto the inner circumferential surface 122 of the inner ring 120. The configuration and effects of the sleeve 140A are the same as those of the outer ring sleeve 140 described with reference to Figures 1 to 5.

[0037] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Industrial applicability]

[0038] This invention can be used as a creep-resistant bearing. [Explanation of Symbols]

[0039] 100, 100A…bearing, 102…shaft, 104…housing, 106…gear, 110…outer ring, 112…outer surface, 120…inner ring, 122…inner surface, 130…ball, 140, 140A…sleeve, 142…thick section, 142a…inner surface, 144…thin section, 144a…inner surface, 144b…outer surface, 146…groove, 150…hollow section, 240…sleeve, 242…thick section, 244…thin section, 244a…inner surface, 340…sleeve, 342…thick section, 344…thin section, 344b…outer surface

Claims

1. Outer ring and, Insider, A rolling element that rolls between the outer ring and the inner ring, When one of the outer ring or inner ring is a stationary ring and the other is a rotating ring, a sleeve is fitted to the outer circumferential surface of the stationary outer ring or the inner circumferential surface of the stationary inner ring, Equipped with, The aforementioned sleeve is Thickened portions that contact the fixed ring at both axial ends, A thin-walled portion that does not come into contact with the fixed ring is provided in the axial center, It has, A creep-resistant bearing characterized in that a hollow portion is formed between the thin-walled portion and the fixed ring by fitting the sleeve onto the fixed ring.

2. The creep-resistant bearing according to claim 1, characterized in that a plurality of grooves extending in the axial direction are arranged on the mating surface between the thickened portion and the fixed ring.

3. The creep-resistant bearing according to claim 1, characterized in that the surface of the thin-walled portion on the fixed ring side has a rounded shape.

4. The creep-resistant bearing according to claim 1, characterized in that the thin-walled portion is curved such that the center of the thin-walled portion is raised.

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