Bearing arrangement

Abstract

In a bearing device in which an outer ring (6) and a housing (2) have mutually fitted cylindrical fitting surfaces (15, 16), two or more retreat surfaces (17) are formed at intervals in the circumferential direction of the outer ring (6), and the retreat surfaces (17) extend over the entire width in the axial direction of the fitting surface (16) in a manner that the fitting surface (16) is interrupted in the circumferential direction.

Description

Technical Field

[0001] The present invention relates to a bearing assembly in which a rolling bearing supporting radial load is assembled between a shaft and a housing. Background Technology

[0002] Typically, the shaft of a car's transmission is supported by a rolling bearing embedded in a housing. This rolling bearing has an inner ring that fits into the outer circumference of the shaft, an outer ring that is coaxially arranged radially outside the inner ring, and a plurality of rolling elements assembled between the inner and outer rings.

[0003] Here, in the rolling bearings supporting the shaft of the transmission, to facilitate the assembly of the rolling bearing relative to the housing, the outer ring is typically fitted with a clearance fit to the housing. That is, the dimensional tolerance is set in such a way that the outer diameter of the cylindrical mating surface of the outer ring is always smaller than the inner diameter of the cylindrical mating surface of the inner circumference of the housing.

[0004] On the other hand, when the outer ring is fitted with a clearance fit to the housing, if the shaft is rotated while a radial load is applied to the inner ring from the shaft, the outer ring will often gradually rotate relative to the housing (creep phenomenon).

[0005] One known mechanism of this peristaltic phenomenon is as follows: If a radial load is applied to the inner ring from the shaft, this radial load is transmitted to the outer ring via the rolling elements, causing the outer ring to deform into a wave pattern. If the inner ring rotates in this state, the rolling elements move circumferentially while rolling, thus causing the wave pattern of the outer ring to also move circumferentially, forming a traveling wave. Furthermore, this traveling wave causes minute slippage between the mating surfaces of the outer ring's outer circumference and the inner circumference of the housing. This minute slippage accumulates, thereby producing the peristaltic phenomenon.

[0006] Similarly, when the shaft clearance is fitted to the inner ring, creep often occurs between the inner ring and the shaft.

[0007] To suppress this peristaltic phenomenon, the inventors of this application have already proposed Patent Document 1. Figure 1 The bearing assembly shown has a shaft, a housing surrounding the shaft, and a rolling bearing that supports radial loads between the shaft and the housing. The outer ring of the rolling bearing has a clearance fit with the housing. Furthermore, to suppress creep between the outer ring and the housing, a recessed surface is formed at one location on the outer periphery of the outer ring, causing the cylindrical mating surface of the outer ring to be circumferentially discontinuous.

[0008] The bearing assembly has a relief surface formed on the outer periphery of the outer ring that breaks the cylindrical mating surface in the circumferential direction. Therefore, through this relief surface, the deformation of the outer ring waveform can be cut off and transmitted to the housing as a traveling wave, thereby suppressing the creep phenomenon.

[0009] For example, when a horizontally configured shaft is supported by rolling bearings and rotates with a vertically downward radial load applied to the inner ring, the area corresponding to the specified central angle of less than 180° between the cylindrical mating surface of the housing and the outer ring and the vertically downward side of the shaft becomes the load application area.

[0010] Furthermore, when a rolling bearing is assembled with the outer circumference of the outer ring recessed at the load application area, the outer circumference of the outer ring and the inner circumference of the housing are not in contact in the load application area. Therefore, the deformation of the outer ring's waveform as a traveling wave can be cut off and transmitted to the housing, thereby suppressing creep. On the other hand, when a rolling bearing is assembled with the outer circumference of the outer ring recessed at a region away from the load application area (e.g., the vertical upper side of the shaft in the cylindrical mating surface of the housing and the outer ring), shortly after assembly, the outer circumference of the outer ring and the inner circumference of the housing come into contact in the load application area on the vertical lower side of the shaft. As a result, the deformation of the outer ring's waveform is transmitted to the housing as a traveling wave. Although creep is temporarily generated, the outer ring gradually rotates due to this creep. As a result, after the outer circumference recessed reaches the load application area, the outer circumference of the outer ring and the inner circumference of the housing become non-contact in the load application area. Therefore, the deformation of the outer ring's waveform as a traveling wave can be cut off and transmitted to the housing, so the outer ring does not rotate further, and the creep phenomenon subsides.

[0011] Patent Document 1: Japanese Patent Application Publication No. 2020-45987

[0012] Although the inventors of this application believe that, as in Patent Document 1 Figure 1 In the case where only one relief surface is provided on the outer circumference of the outer ring of the rolling bearing, as described above, creep can be suppressed regardless of whether the relief surface of the outer circumference of the rolling bearing assembled into the outer ring is located in the load application area or in a region away from the load application area, and regardless of its assembly orientation. However, it has been known that there are actually situations where creep cannot be suppressed. Moreover, after investigating the cause, it was clarified that creep cannot be suppressed when the load application area of ​​the rolling bearing changes.

[0013] That is, the direction of the radial load applied to the rolling bearing is not constant and can vary continuously. Typically, there are cases where the load applied to the rolling bearing is a rotating load (where the direction of the radial load applied to the rolling bearing rotates). In this case, the load application area of ​​the rolling bearing is constantly shifting, therefore, as in Patent Document 1... Figure 1In a rolling bearing with only one relief surface on the outer circumference of the outer ring, as the load-bearing area moves, when the load-bearing area overlaps with the relief surface, the deformation of the outer ring's waveform is cut off and transmitted to the housing as a traveling wave. However, while the load-bearing area is away from the relief surface, the deformation of the outer ring's waveform is transmitted to the housing as a traveling wave, resulting in creep. Moreover, even if the relief surface on the outer circumference of the outer ring moves to any position due to this creep, the load-bearing area continues to move, and therefore, the creep does not subside. In other words, in cases where a rotating load is applied to a rolling bearing and the load-bearing area of ​​the rolling bearing is constantly moving, as in Patent Document 1... Figure 1 Therefore, it can be seen that if a relief surface is provided on the outer circumference of the outer ring of the rolling bearing, the creep phenomenon cannot be suppressed. Summary of the Invention

[0014] The problem to be solved by the present invention is to provide a bearing device that can effectively suppress creep even when the direction of the radial load applied to the rolling bearing changes.

[0015] To address the aforementioned issues, the present invention provides a bearing device with the following structure.

[0016] A bearing device comprising:

[0017] axis;

[0018] A housing that surrounds the outer periphery of the aforementioned shaft; and

[0019] A rolling bearing that supports radial loads between the shaft and the housing.

[0020] The aforementioned rolling bearing has raceways that are clearance-fitted with either the aforementioned shaft or the aforementioned housing, i.e., the target component.

[0021] The aforementioned collar and the aforementioned object component have mutually fitting cylindrical mating surfaces.

[0022] The bearing device described above is characterized in that,

[0023] One of the aforementioned collar and the aforementioned object component has two or more recessed surfaces spaced apart circumferentially, the recessed surfaces extending across the entire axial width of the mating surface in such a way that the mating surface of the component is circumferentially disconnected.

[0024] Accordingly, two or more relief surfaces are formed circumferentially spaced apart in one of the components of the race and the object component for which the race is clearance fitted. Therefore, even if the direction of the radial load applied to the rolling bearing changes, such as when a rotating load is applied to the rolling bearing, the deformation of the race's waveform is difficult to be transmitted to the object component as a traveling wave, thereby effectively suppressing creep.

[0025] The aforementioned relief surface can be formed on the aforementioned collar. That is, two or more relief surfaces can be formed circumferentially on the aforementioned collar, and the relief surface extends throughout the entire axial width of the aforementioned mating surface in such a way that the aforementioned mating surface of the aforementioned collar is interrupted in the circumferential direction.

[0026] Furthermore, the aforementioned object component can be the aforementioned housing, and the aforementioned ring can be an outer ring. That is, the following structure can be adopted: the aforementioned rolling bearing has an outer ring that is clearance-fitted with the aforementioned housing, the aforementioned outer ring and the aforementioned housing have mutually fitting cylindrical mating surfaces, and the aforementioned outer ring has two or more recessed surfaces spaced apart circumferentially, the recessed surfaces extending throughout the entire axial width of the mating surfaces in a manner that breaks the aforementioned mating surfaces of the outer ring in the circumferential direction.

[0027] The aforementioned yielding surfaces are preferably provided at equal intervals of 3 to 6 along the outer periphery of the outer ring.

[0028] If three or more relief surfaces are provided at equal intervals along the circumference of the outer ring, even if the direction of the radial load applied to the rolling bearing changes, causing the load application area to constantly shift, a certain relief surface can always maintain its state within the load application area, thereby effectively suppressing creep. Furthermore, by reducing the number of relief surfaces provided at equal intervals along the circumference of the outer ring to six or fewer, the circumferential length of each relief surface can be ensured, thus effectively cutting off the deformation of the outer ring's waveform as a traveling wave transmitted to the housing.

[0029] The aforementioned yielding surface can also take the shape of a planar shape or a concave arc shape, but it is preferred to take the shape of a convex arc-shaped curved surface formed at a position that is radially inward than the radial position of the aforementioned mating surface of the outer ring.

[0030] Accordingly, compared with the case where a planar shape or a concave arc shape is used as the relief surface formed on the outer periphery of the outer ring, the reduction in radial wall thickness of the outer ring caused by the formation of the relief surface can be suppressed, thereby suppressing the deflection of the outer ring when a radial load is applied.

[0031] Preferably, the two ends of the recessed surface in the circumferential direction are smoothly connected to the aforementioned mating surface of the outer ring.

[0032] Accordingly, since the outer ring's recessed surface is smoothly connected to the mating surface, it is possible to prevent the connection between the outer ring's recessed surface and the mating surface from attacking the mating surface of the housing and thus generating excessive surface pressure.

[0033] Preferably, the aforementioned relief surface is formed such that even when the maximum radial load is applied to the aforementioned rolling bearing, the aforementioned relief surface does not contact the aforementioned mating surface of the aforementioned housing, and a radial clearance is ensured between the two.

[0034] Therefore, even when a large radial load is applied to the rolling bearing, creep can be reliably suppressed.

[0035] The bearing device of the present invention has two or more relief surfaces spaced circumferentially apart in one of the rings and the component to which the rings are clearance-fitted. Therefore, even when the direction of the radial load applied to the rolling bearing changes, as in the case where a rotational load is applied to a rolling bearing, the deformation of the ring waveform is difficult to be transmitted to the housing as a traveling wave, thereby effectively suppressing creep. Attached Figure Description

[0036] Figure 1 This is a partial cross-sectional view showing the bearing device according to an embodiment of the present invention.

[0037] Figure 2 It is along Figure 1 A sectional view along line II-II.

[0038] Figure 3 It means from Figure 1 A partial sectional view of the outer ring of the bearing assembly shown.

[0039] Figure 4 yes Figure 3 A magnified view of the area near the yielding surface.

[0040] Figure 5 It means to Figure 1 The diagram shows a rolling bearing subjected to a vertically upward radial load.

[0041] Figure 6 This indicates the direction of the radial load applied to the rolling bearing from... Figure 5 The diagram shows the orientation after rotation.

[0042] Figure 7 This is a cross-sectional view showing a bearing device according to another embodiment of the present invention. Detailed Implementation

[0043] Figure 1 , Figure 2This describes a bearing assembly according to an embodiment of the present invention. The bearing assembly has a shaft 1, a housing 2 surrounding the outer periphery of the shaft 1, and a rolling bearing 3 supporting radial loads between the shaft 1 and the housing 2.

[0044] Shaft 1 is a rotating shaft that receives rotation from a rotational drive source (such as an automobile engine) not shown in the figure. On the other hand, housing 2 is a non-rotating fixed component. A cylindrical housing bore 4 is formed in housing 2, and a rolling bearing 3 is assembled in housing bore 4.

[0045] The rolling bearing 3 has: an inner ring (inner race) 5, which fits into the outer periphery of the shaft 1; an outer ring (outer race) 6, which is coaxially arranged radially outward of the inner ring 5; a plurality of rolling elements 7, which are assembled circumferentially spaced between the inner ring 5 and the outer ring 6; and a retainer 8, which maintains the circumferential spacing of the plurality of rolling elements 7. The rolling elements 7 are spheres.

[0046] like Figure 2 As shown, an inner ring raceway groove 9 for rolling contact of the rolling element 7 and inner ring shoulders 10 located on both sides of the inner ring raceway groove 9 in the axial direction are formed on the outer periphery of the inner ring 5. An outer ring raceway groove 11 for rolling contact of the rolling element 7 and outer ring shoulders 12 located on both sides of the outer ring raceway groove 11 in the axial direction are also formed on the inner periphery of the outer ring 6. Both the inner ring raceway groove 9 and the outer ring raceway groove 11 are grooves with a circular arc cross-section.

[0047] The inner ring 5 is interference-fitted with the outer circumference of the shaft 1. That is, the inner ring 5 has a cylindrical mating surface 13 formed on its inner circumference, and the shaft 1 has a cylindrical mating surface 14 formed on its outer circumference. The mating surface 13 of the inner ring 5 and the mating surface 14 of the shaft 1 are mated with an interference fit. Here, before the inner ring 5 is installed on the outer circumference of the shaft 1, the inner diameter of the mating surface 13 of the inner ring 5 is smaller than the outer diameter of the mating surface 14 of the outer circumference of the shaft 1.

[0048] The outer ring 6 is clearance-fitted with the housing hole 4 of the housing 2. That is, the housing 2 has a cylindrical fitting surface 15 formed on the inner circumference of the housing hole 4, and the outer ring 6 has a cylindrical fitting surface 16 formed on the outer circumference of the outer ring 6. The fitting surface 15 of the housing 2 and the fitting surface 16 of the outer ring 6 are fitted with a gap (a small annular gap). Here, before the housing hole 4 is inserted into the outer ring 6, the outer diameter of the fitting surface 16 on the outer circumference of the outer ring 6 is smaller than the inner diameter of the fitting surface 15 on the inner circumference of the housing hole 4.

[0049] like Figure 3 As shown, two or more (three at 120° intervals in the figure) recessed surfaces 17 are formed circumferentially around the outer periphery of the outer ring 6. These recessed surfaces 17 extend across the entire axial width of the mating surface 16 in a manner that breaks the mating surface 16 in the circumferential direction. The recessed surfaces 17 are preferably provided at equal intervals of three to six around the outer periphery of the outer ring 6.

[0050] like Figure 2 As shown, a radial gap 18 is formed between the recessed surface 17 of the outer ring 6 and the mating surface 15 of the housing 2. The radial gap 18 is thin and crescent-shaped. The radial dimension of the radial gap 18 gradually decreases from the circumferential center towards both circumferential ends, such that the radial dimension at the circumferential center of the radial gap 18 is greater than the radial dimension of the gap (annular micro-gap) set between the mating surface 16 of the outer ring 6 and the mating surface 15 of the housing 2. The radial gap 18 is a space in which no components exist.

[0051] like Figure 4 As shown, the recessed surface 17 is formed as a convex arc-shaped curved surface located radially inward of the mating surface 16 of the outer ring 6 (the position indicated by the double-dotted line in the figure). The two ends of the recessed surface 17 in the circumferential direction are smoothly connected to the mating surface 16. That is, the two ends of the recessed surface 17 in the circumferential direction have a profile of a curve (e.g., an arc curve, a logarithmic curve, etc.) with a curvature greater than that of the central portion of the recessed surface 17 in the circumferential direction, so that the two ends of the recessed surface 17 in the circumferential direction are smoothly connected to the mating surface 16 in a manner that no edge is generated at the boundary between the recessed surface 17 and the mating surface 16.

[0052] The radial depth δ of the recessed surface 17 relative to the mating surface 16 of the outer ring 6 (the position of the double-dotted line in the figure) is formed as follows: even when the maximum radial load is applied to the rolling bearing 3, the recessed surface 17 does not contact the mating surface 15 of the housing 2, and a radial clearance 18 is ensured between the recessed surface 17 and the mating surface 15 (see reference). Figure 2 The maximum radial load is, for example, the basic static radial load rating. The basic static radial load rating is the static radial load at the center of the contact portion between the rolling element 7 and the outer ring raceway groove 11, where the rolling element 7 is a ball and a static radial load is applied to the rolling bearing 3, such that the contact stress is 4.2 GPa.

[0053] like Figure 3 As shown, the circumferential length of the yielding surface 17 can be defined by an angle α around the center of the outer ring 6. The angle α corresponding to the circumferential length of the yielding surface 17 is as follows: Figure 1 As shown, when the spacing angle of the rolling elements 7 corresponding to the arrangement interval of the adjacent rolling elements 7 is set to θ, it is preferably set to a value of 0.5 times or more of the spacing angle θ of the rolling elements 7. This effectively cuts off the deformation of the outer ring 6's waveform from being transmitted to the housing 2 as a traveling wave. Furthermore, the angle α corresponding to the circumferential length of the relief surface 17 is preferably set to 2.0 times or less (preferably 1.0 times or less) of the spacing angle θ of the rolling elements 7. This suppresses the deflection of the outer ring 6 when a radial load is applied.

[0054] The bearing assembly has two or more relief surfaces 17 spaced apart circumferentially on the outer ring 6. Therefore, even if the direction of the radial load applied to the rolling bearing 3 changes, as in the case where a rotational load is applied to the rolling bearing 3, the deformation of the waveform of the outer ring 6 is difficult to be transmitted to the housing 2 as a traveling wave, thereby effectively suppressing the creep phenomenon.

[0055] That is, such as Figure 5 As shown, if a radial load F is applied to the inner ring 5 from shaft 1, a load application region W is generated in the direction of the applied radial load F. Within this load application region W, the radial load F applied to the inner ring 5 from shaft 1 passes through the rolling element 7 (see reference 7). Figure 1 This is transmitted to the outer ring 6, causing the outer ring 6 to exhibit a wave-like deformation. Furthermore, as... Figure 5 as well as Figure 6 As shown, when rotating in the direction of the radial load F applied to the inner ring 5 from shaft 1, the load application area W generated in the direction of the applied radial load F also moves circumferentially in accordance with the rotation of the radial load F. Here, in the bearing device of this embodiment, since two or more relief surfaces 17 are formed at circumferential intervals on the outer ring 6, even if the load application area W moves to any position, it is easy for the load application area W to overlap with the position of the relief surface 17, so that the deformation of the waveform of the outer ring 6 is difficult to be transmitted to the housing 2 as a traveling wave. Therefore, creep can be effectively suppressed.

[0056] Preferably, three or more relief surfaces 17 are provided at equal intervals along the circumferential direction on the outer periphery of the outer ring 6. Therefore, even if the direction of the radial load F applied to the rolling bearing 3 changes, causing the load application area W to constantly shift, one relief surface 17 can always remain in the load application area W, thereby effectively suppressing creep. Alternatively, three or more relief surfaces 17 can be arranged at unequal intervals on the outer periphery of the outer ring 6. In this case, regardless of which direction the radial load F is applied, it is sufficient to arrange at least one relief surface 17 in the load application area W of the radial load F.

[0057] Furthermore, the number of recessed surfaces 17 provided at equal intervals along the circumference of the outer ring 6 is preferably six or less. This ensures the circumferential length of each recessed surface 17, thus effectively cutting off the deformation of the outer ring 6's waveform as a traveling wave transmitted to the housing 2.

[0058] like Figure 4As shown, this bearing assembly employs a convex arc-shaped curved surface that is radially inward from the radial position of the mating surface 16 of the outer ring 6. Therefore, compared to using a planar shape or a concave arc-shaped shape as the relief surface 17 formed on the outer periphery of the outer ring 6, the reduction in radial wall thickness of the outer ring 6 due to the formation of the relief surface 17 can be suppressed. Thus, deflection of the outer ring 6 under a radial load F can be suppressed.

[0059] In addition, such as Figure 4 As shown, because the two ends of the relief surface 17 are smoothly connected to the mating surface 16 in the circumferential direction, the bearing device can prevent the connection between the relief surface 17 and the mating surface 16 of the outer ring 6 from attacking the mating surface 15 of the housing 2 and thus generating excessive surface pressure.

[0060] Furthermore, the bearing assembly forms the relief surface 17 in such a way that even when the maximum radial load is applied to the rolling bearing 3, the relief surface 17 and the mating surface 15 do not contact each other, and a radial clearance 18 is ensured between them. Therefore, even when the radial load F applied to the rolling bearing 3 is large, creep can be reliably suppressed.

[0061] In the above embodiment, a relief surface 17 is formed in the outer ring 6 and the outer ring 6 in the housing 2 that are fitted together in a clearance fit. However, a relief surface 17 may also be formed in the housing 2 in addition to the outer ring 6. That is, the following structure may also be adopted: two or more relief surfaces 17 are formed in the housing 2 at circumferential intervals, and the relief surfaces 17 extend throughout the entire axial width of the mating surface 15 in such a way that the mating surface 15 of the housing 2 is interrupted in the circumferential direction.

[0062] Furthermore, in the above embodiment, a rolling bearing 3 in which the outer ring 6 and the housing 2 are fitted with a clearance fit has been described as an example. However, the present invention can also be applied to a rolling bearing 3 in which the inner ring 5 and the shaft 1 are fitted with a clearance fit. In this case, a relief surface 17 is formed on one of the components of the inner ring 5 and the shaft 1 that are fitted with each other with a clearance fit.

[0063] Specifically, such as Figure 7As shown, a structure can be adopted in which two or more (three in the figure) recessed surfaces 17 are formed circumferentially in the inner ring 5, and the recessed surfaces 17 extend across the entire axial width of the mating surface 13 of the inner ring 5 in a manner that breaks the mating surface 13 in the circumferential direction. In this way, even if the direction of the radial load F applied to the rolling bearing 3 changes, as in the case where a rotational load is applied to the rolling bearing 3, the deformation of the waveform of the inner ring 5 is unlikely to be transmitted to the shaft 1 as a traveling wave, thereby effectively suppressing creep. Furthermore, a structure can also be adopted in which two or more recessed surfaces 17 are formed circumferentially in the shaft 1, and the recessed surfaces 17 extend across the entire axial width of the mating surface 14 of the shaft 1 in a manner that breaks the mating surface 14 in the circumferential direction.

[0064] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the invention is shown not by the foregoing description but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

[0065] Explanation of reference numerals in the attached figures

[0066] 1...shaft; 2...housing; 3...rolling bearing; 5...inner ring (coiling ring); 6...outer ring (coiling ring); 13, 14, 15, 16...fitting surface; 17...recessed surface; 18...radial clearance.

Claims

1. A bearing assembly comprising: Axis (1); Housing (2), the housing (2) surrounding the outer periphery of the shaft (1); and A rolling bearing (3) supports radial loads between the shaft (1) and the housing (2). The rolling bearing (3) has a raceway that is clearance-fitted with either the shaft (1) or the housing (2), i.e., the object component. The collar and the object component have interlocking cylindrical mating surfaces. The bearing assembly is characterized in that... One of the ring and the object component has two or more recessed surfaces (17) spaced apart circumferentially, the recessed surfaces (17) extending circumferentially across the entire axial width of the mating surface such that the mating surface of the component is circumferentially interrupted. The yielding surface (17) is formed on the collar. The object component is the housing (2). The ring is the outer ring (6). The yielding surface (17) is a convex arc-shaped curved surface formed at a position radially inward than the radial position of the fitting surface (16) of the outer ring (6).

2. The bearing device according to claim 1, characterized in that, The yielding surfaces (17) are arranged at equal intervals of 3 to 6 along the outer periphery of the outer ring (6).

3. The bearing device according to claim 1 or 2, characterized in that, The two ends of the circumferential direction of the yielding surface (17) are smoothly connected to the fitting surface (16) of the outer ring (6).

4. The bearing device according to claim 1 or 2, characterized in that, The relief surface (17) is formed such that even when the maximum radial load is applied to the rolling bearing (3), the relief surface (17) does not contact the mating surface (15) of the housing (2) and a radial clearance (18) is ensured between them.

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