KR20230115985A - bearing device - Google Patents

Abstract

In a bearing device having cylindrical fitting surfaces 15 and 16 in which the outer ring 6 and the housing 2 fit with each other, the outer ring 6 has the fitting surface 16 so as to be divided in the circumferential direction ( 16), two or more clearance surfaces 17 extending over the entire width in the axial direction are formed at intervals in the circumferential direction.

Description

bearing device

The present invention relates to a bearing device incorporating a rolling bearing for supporting a radial load between a shaft and a housing.

BACKGROUND OF THE INVENTION [0002] In general, a transmission shaft of an automobile is supported by a rolling bearing fitted to a housing. This rolling bearing has an inner ring fitted to the outer circumference of a shaft, an outer ring coaxially disposed outside the inner ring in a radial direction, and a plurality of rolling elements inserted between the inner ring and the outer ring.

Here, in the rolling bearing supporting the transmission shaft, the outer ring is usually loosely fitted to the housing in order to facilitate the assembly work of the rolling bearing to the housing. That is, the dimensional tolerance is set such that the outer diameter of the cylindrical fitting surface of the outer circumference of the outer ring is always smaller than the inner diameter of the cylindrical fitting surface of the inner circumference of the housing.

On the other hand, when the outer ring is loosely fitted to the housing and the shaft is rotated while a radial load is applied to the inner ring from the shaft, a phenomenon in which the outer ring gradually rotates relative to the housing (creep phenomenon) may occur.

As one of the mechanisms of this creep phenomenon, the following is known. That is, when a radial load is applied from the shaft to the inner ring, the radial load is transmitted to the outer ring through the rolling elements, and the outer ring is deformed in a wave shape. When the inner ring rotates in this state, since the rolling element moves in the circumferential direction while rolling, the wave deformation of the outer ring also moves in the circumferential direction, and the deformation of the outer ring forms a traveling wave. Then, the traveling wave causes a slight slippage between the mating surface of the outer circumference of the outer ring and the mating surface of the inner circumference of the housing, and the creep phenomenon occurs as the minute slippage is accumulated.

Similarly, even when the shaft is loosely fitted to the inner ring, a creep phenomenon may occur between the inner ring and the shaft.

In order to suppress this creep phenomenon, the inventor of this application has already proposed the bearing device shown in FIG. 1 of patent document 1. This bearing device has a shaft, a housing surrounding the outer periphery of the shaft, and a rolling bearing supporting a radial load between the shaft and the housing. The outer ring of the rolling bearing is loosely fitted into the housing. Then, in order to suppress the occurrence of creep between the outer ring and the housing, a relief surface is formed at one point on the outer circumference of the outer ring to divide the cylindrical fitting surface of the outer circumference of the outer ring in the circumferential direction.

In this bearing device, since a clearance surface that divides the cylindrical fitting surface in the circumferential direction is formed on the outer circumference of the outer ring, the clearance surface can block the wave deformation of the outer ring from being transmitted to the housing as a traveling wave, Creep phenomenon can be suppressed.

For example, when a horizontally arranged shaft is supported by rolling bearings and the shaft rotates in a state where a vertically downward radial load is applied from the shaft to the inner ring, 180° of the cylindrical fitting surface between the housing and the outer ring is 180° vertically lower than the shaft. A range corresponding to a predetermined central angle less than or equal to becomes a load bearing region.

And, when the rolling bearing is assembled so that the clearance surface of the outer ring of the outer ring is located in this load bearing region, since the outer ring of the outer ring and the inner circle of the housing are not in contact in the load bearing region, the wave deformation of the outer ring is transmitted to the housing as a traveling wave. transmission can be blocked, and the creep phenomenon is suppressed. On the other hand, when a rolling bearing is assembled so that the clearance surface of the outer ring of the outer ring is located in an area deviating from the load bearing area (for example, the range on the vertically upper side of the shaft among the cylindrical fitting surfaces of the housing and the outer ring), immediately after assembly, the shaft is vertically In the lower load bearing area, the outer circumference of the outer ring and the inner periphery of the housing contact, and the wave deformation of the outer ring is transmitted to the housing as a traveling wave, causing a creep phenomenon to occur once, but the creep phenomenon causes the outer ring to rotate gradually, After the clearance surface of the outer ring of the outer ring reaches the load bearing region, the outer ring of the outer ring and the inner circle of the housing are in no contact in the load bearing region, so that the wave deformation of the outer ring is prevented from being transmitted to the housing as a traveling wave. does not rotate further, and the creep phenomenon is solved.

Patent Document 1: Japanese Unexamined Patent Publication No. 2020-45987

The inventor of the present application, as described in FIG. 1 of Patent Document 1, when only one point is provided on the outer circumference of the outer ring of the rolling bearing, as described above, the clearance surface of the outer ring of the rolling bearing is in the load bearing area. It was thought that the creep phenomenon could be suppressed regardless of the assembly direction even if the outer ring was assembled so that the clearance surface of the outer ring was located in a region where the clearance surface of the outer circumference of the outer ring was deviated from the load bearing region. It was found that there were cases that were not suppressed. Then, as a result of investigating and examining the cause, it was found that the creep phenomenon was not suppressed when the load bearing region of the rolling bearing fluctuated.

That is, there are cases where the direction of the radial load applied to the rolling bearing is not constant and fluctuates all the time. Typically, this is the case where the load applied to the rolling bearing is a rotational load (when the direction of the radial load applied to the rolling bearing rotates). In this case, since the load bearing area of the rolling bearing always moves, as shown in FIG. When the load bearing area overlaps the position of the clearance surface, the wave deformation of the outer ring can be blocked from being transmitted to the housing as a traveling wave, but while the load bearing area is out of the position of the clearance surface, the wave deformation of the outer ring acts as a traveling wave. It is transmitted to the housing, and a creep phenomenon occurs. In addition, since the load bearing area always moves no matter what position the clearance surface of the outer periphery of the outer ring moves due to this creep phenomenon, the creep phenomenon is not resolved after all. That is, when the load bearing region of the rolling bearing always moves, such as when a rotational load is applied to the rolling bearing, a clearance surface at one point is provided on the outer circumference of the outer ring of the rolling bearing, as shown in FIG. , it was found that the creep phenomenon could not be suppressed.

An object to be solved by the present invention is to provide a bearing device capable of effectively suppressing creep even when the direction of a radial load applied to a rolling bearing fluctuates.

In order to solve the above-mentioned subject, in this invention, the bearing apparatus of the following structures is provided.

axis,

A housing surrounding the outer circumference of the shaft;

A rolling bearing supporting a radial load between the shaft and the housing,

The rolling bearing has a roller rig loosely fitted with a mating member that is either one of the shaft and the housing,

In the bearing device, the bearing ring and the mating member have cylindrical fitting surfaces that fit with each other,

On one member of the bearing ring and the mating member, two or more clearance surfaces are formed at intervals in the circumferential direction, extending over the full axial width of the fitting surface so as to divide the fitting surface of the member in the circumferential direction, A bearing device characterized in that there is.

In this way, since two or more clearance surfaces are formed at intervals in the circumferential direction on one member of the ring and the mating member to which the ring is loosely fitted, as in the case where a rotational load is applied to the rolling bearing, Even when the direction of the radial load applied to the rolling bearing fluctuates, the corrugated deformation of the bearing ring is not easily transmitted to the mating member as a traveling wave, and the creep phenomenon can be effectively suppressed.

The clearance surface may be formed on the bearing ring. That is, two or more clearance surfaces may be formed on the raceway at intervals in the circumferential direction, extending over the full axial width of the engagement surface so as to divide the engagement surface of the raceway in the circumferential direction.

Further, a configuration in which the mating member is the housing and the bearing ring is an outer ring can be adopted. That is, the rolling bearing has an outer ring that is loosely fitted with the housing, the outer ring and the housing have cylindrical fitting surfaces that fit with each other, and the outer ring has the fitting surfaces of the outer ring divided in the circumferential direction. A configuration in which two or more clearance surfaces extending over the full width of the fitting surface in the axial direction are formed at intervals in the circumferential direction can be employed.

It is preferable that the clearance surfaces are provided in a range of 3 or more and 6 or less at equal intervals in the circumferential direction on the outer circumference of the outer ring.

If three or more clearance surfaces are provided at equal intervals in the circumferential direction on the outer circumference of the outer ring, even if the direction of the radial load applied to the rolling bearing fluctuates and the load application area always moves, the load is always applied. It is possible to maintain a state in which one of the clearance surfaces enters the region, so that the creep phenomenon can be effectively suppressed. In addition, since the circumferential length of the clearance surface per one can be secured by setting the number of clearance surfaces at equal intervals in the circumferential direction on the outer circumference of the outer ring to 6 or less, the wave deformation of the outer ring affects the housing as a traveling wave. transmission can be effectively blocked.

The clearance surface may be of a flat shape or a concave arc shape, but it is preferable to use a convex arc shape curved surface formed so as to pass radially inward from the radial position of the fitting surface of the outer ring.

In this way, the reduction in the thickness in the radial direction of the outer ring due to the formation of the clearance surface can be suppressed compared to the case of adopting a flat or concave arc shape as the clearance surface formed on the outer circumference of the outer ring, It is possible to suppress bending of the outer ring when a radial load is applied.

It is preferable to adopt a configuration in which both ends of the clearance surface in the circumferential direction are smoothly connected to the fitting surface of the outer ring.

In this way, since the clearance surface of the outer ring is smoothly connected to the fitting surface, excessive surface pressure can be prevented from being generated when the connection portion between the clearance surface of the outer ring and the fitting surface attacks the fitting surface of the housing. .

It is preferable that the clearance surface is formed such that a radial gap is secured between the clearance surface and the fitting surface of the housing without contact even when a maximum radial load is applied to the rolling bearing.

In this way, even when the radial load applied to the rolling bearing is large, it is possible to reliably suppress the creep phenomenon.

In the bearing device of the present invention, since two or more clearance surfaces are formed at intervals in the circumferential direction on one of the bearing rings and the mating member to which the bearing rings are loosely fitted, when a rotational load is applied to the rolling bearing. As such, even when the direction of the radial load applied to the rolling bearing fluctuates, the wave deformation of the raceway is not easily transmitted to the housing as a traveling wave, and the creep phenomenon can be effectively suppressed.

1 is a partial cross-sectional view showing a bearing device according to an embodiment of the present invention.
Figure 2 is a cross-sectional view taken along line II-II of Figure 1;
Fig. 3 is a partial sectional view showing an outer ring taken out of the bearing device shown in Fig. 1;
Fig. 4 is an enlarged view of the vicinity of the relief surface of Fig. 3;
5 is a view showing a state in which a vertically upward radial load is applied to the rolling bearing shown in FIG. 1;
Fig. 6 is a view showing a state in which the direction of the radial load applied to the rolling bearing is rotated from the direction shown in Fig. 5;
7 is a cross-sectional view showing a bearing device according to another embodiment of the present invention.

1 and 2 show a bearing device according to an embodiment of the present invention. This bearing device has a shaft 1, a housing 2 surrounding the outer periphery of the shaft 1, and a rolling bearing 3 supporting a radial load between the shaft 1 and the housing 2. .

Shaft 1 is a rotation shaft to which rotation is input from a rotation drive source (such as an automobile engine) not shown. On the other hand, the housing 2 is a non-rotating fixed member. A cylindrical housing hole 4 is formed in the housing 2, and a rolling bearing 3 is inserted into the housing hole 4.

The rolling bearing 3 includes an inner ring (inner raceway ring) 5 fitted to the outer circumference of the shaft 1 and an outer ring (outer raceway ring) 6 coaxially arranged radially outside of the inner ring 5. ), a plurality of rolling elements 7 inserted at intervals in the circumferential direction between the inner race 5 and the outer race 6, and a retainer 8 maintaining a circumferential distance between the plurality of rolling elements 7 ) has The rolling element 7 is a bead.

As shown in FIG. 2, on the outer periphery of the inner ring 5, the inner ring raceway groove 9, in which the rolling element 7 comes into rolling contact, and the inner ring shoulder portion located on both sides of the inner ring raceway groove 9 in the axial direction (10) is formed. Also formed on the inner circumference of the outer ring 6 are outer ring raceway grooves 11 in which the rolling elements 7 come into rolling contact, and outer ring shoulders 12 located on both sides of the outer ring raceway grooves 11 in the axial direction. Both the inner ring raceway groove 9 and the outer ring raceway groove 11 are arcuate grooves in cross section.

The inner ring 5 is tightly fitted to the outer periphery of the shaft 1. That is, the inner ring 5 has a cylindrical fitting surface 13 formed on the inner circumference of the inner ring 5, and the shaft 1 has a cylindrical fitting surface 14 formed on the outer circumference of the shaft 1, The fitting surface 13 of the inner ring 5 and the fitting surface 14 of the shaft 1 are fitted with a fastening margin. Here, in the state before attaching the inner ring 5 to the outer circumference of the shaft 1, the inner diameter of the fitting surface 13 on the inner circumference of the inner ring 5 is the smaller than the outer diameter.

The outer ring 6 is loosely fitted into the housing hole 4 of the housing 2. That is, the housing 2 has a cylindrical fitting surface 15 formed on the inner periphery of the housing hole 4, and the outer ring 6 has a cylindrical fitting surface 16 formed on the outer periphery 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 (annular minute gap). Here, in the state before the outer ring 6 is fitted into the housing hole 4, the outer diameter of the fitting surface 16 on the outer circumference of the outer ring 6 is the smaller than the inner diameter

As shown in FIG. 3, on the outer periphery of the outer ring 6, a clearance surface 17 extending over the entire width of the fitting surface 16 in the axial direction is provided in the circumferential direction so as to divide the fitting surface 16 in the circumferential direction. Two or more (three at 120° intervals in the drawing) are formed at intervals. It is preferable that the clearance surface 17 is provided in a range of 3 or more and 6 or less at equal intervals in the circumferential direction on the outer circumference of the outer ring 6.

As shown in FIG. 2 , a radial gap 18 is formed between the clearance surface 17 of the outer ring 6 and the fitting surface 15 of the housing 2 . The radial gap 18 has a thin crescent shape. The radial dimension of the radial gap 18 gradually decreases from the circumferential center of the radial gap 18 toward both ends in the circumferential direction, and the radial dimension at the circumferential center of the radial gap 18 is the outer ring. It is larger than the radial dimension of the gap (annular minute gap) set between the fitting surface 16 of (6) and the fitting surface 15 of the housing 2. The radial gap 18 is a space in which no member exists.

As shown in FIG. 4, the clearance surface 17 is a convex arc-shaped curved surface formed to pass radially inside the radial position of the fitting surface 16 of the outer ring 6 (the position of the dotted-dashed line in the drawing). am. Both ends of the clearance surface 17 in the circumferential direction are connected to the fitting surface 16 smoothly. That is, both ends of the clearance surface 17 in the circumferential direction have a shape having the outline of a curve (eg, arc curve, logarithmic curve, etc.) having a greater curvature than the central portion of the circumferential direction of the clearance surface 17, Both ends of the clearance surface 17 in the circumferential direction are connected to the fitting surface 16 smoothly so that no edge is formed at the boundary between the clearance surface 17 and the fitting surface 16 .

The radial depth δ of the clearance surface 17 relative to the radial position of the fitting surface 16 of the outer ring 6 (the position of the dotted-dashed line in the drawing) is the maximum radial load applied to the rolling bearing 3. Even in this case, the clearance surface 17 and the fitting surface 15 of the housing 2 do not contact, and a radial gap 18 (see FIG. 2) is formed between the clearance surface 17 and the fitting surface 15. It is formed to a size that is secured. The maximum radial load is, for example, the basic positive radial load rating. The basic positive radial load rating is the relationship between the rolling element 7 and the outer ring raceway groove 11 that receive the maximum load when the rolling element 7 is a ball and a positive radial load is applied to the rolling bearing 3. It is a positive radial load at which the contact stress at the center of the contact portion becomes 4.2 GPa.

As shown in FIG. 3 , the length of the clearance surface 17 in the circumferential direction 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 clearance surface 17 is, as shown in FIG. 1, when the pitch angle of the rolling elements 7 corresponding to the arrangement interval of adjacent rolling elements 7 is θ , it is preferable to set the pitch angle θ of the rolling elements 7 to 0.5 times or more. Accordingly, it is possible to effectively block the wave deformation of the outer ring 6 from being transmitted to the housing 2 as a traveling wave. Further, the angle α corresponding to the circumferential length of the clearance surface 17 is preferably set to 2.0 times or less (preferably 1.0 times or less) of the pitch angle θ of the rolling elements 7. Thereby, deflection of the outer ring 6 when a radial load is applied can be suppressed.

In this bearing device, since two or more clearance surfaces 17 are formed on the outer ring 6 at intervals in the circumferential direction, as in the case where a rotational load is applied to the rolling bearing 3, the rolling bearing 3 Even when the direction of the radial load applied to ) fluctuates, the wave deformation of the outer ring 6 is not easily transmitted to the housing 2 as a traveling wave, and the creep phenomenon can be effectively suppressed.

That is, as shown in FIG. 5, when a radial load F is applied from the shaft 1 to the inner ring 5, a load bearing region W is created in the direction in which the radial load F is applied. In this load bearing region W, the radial load F applied to the inner ring 5 from the shaft 1 is transmitted to the outer ring 6 via the rolling elements 7 (see FIG. 1), and the outer ring (6) is transformed into a waveform. And, as shown in FIGS. 5 and 6, when the direction of the radial load F applied to the inner ring 5 from the shaft 1 rotates, the radial load F is generated in the direction in which the load is applied. The load bearing area W also moves in the circumferential direction according to the rotation of the radial load F. Here, in the bearing device of this embodiment, since two or more clearance surfaces 17 are formed at intervals in the circumferential direction on the outer ring 6, no matter where the load bearing region W moves to, The load bearing region W tends to overlap the position of the clearance surface 17, and the wave deformation of the outer ring 6 is difficult to transmit to the housing 2 as a traveling wave. Therefore, the creep phenomenon can be suppressed effectively.

It is preferable that three or more clearance surfaces 17 are provided on the outer circumference of the outer ring 6 at equal intervals in the circumferential direction. In this way, even when the direction of the radial load F applied to the rolling bearing 3 fluctuates and the load bearing region W always moves, there is always some margin in the load bearing region W. It is possible to maintain the state in which the surface 17 is retracted, so that the creep phenomenon can be effectively suppressed. It is also possible to install three or more clearance surfaces 17 on the outer circumference of the outer ring 6 in an unequal arrangement. In this case, the clearance surface 17 is set so that at least one clearance surface 17 enters the load bearing area W by the radial load F no matter which direction the radial load F is applied. good to place

In addition, it is preferable that the number of clearance surfaces 17 provided on the outer circumference of the outer ring 6 at equal intervals in the circumferential direction is 6 or less. In this way, since the circumferential length of the clearance surface 17 per one can be secured, it is possible to effectively prevent the wave deformation of the outer ring 6 from being transmitted to the housing 2 as a traveling wave.

As shown in FIG. 4, this bearing device employs a convex arc-shaped curved surface formed so as to pass radially inside the radial position of the fitting surface 16 of the outer ring 6, so that the outer ring 6 ) as the clearance surface 17 formed on the outer periphery, the decrease in the thickness in the radial direction of the outer ring 6 due to the formation of the clearance surface 17 is suppressed compared to the case where a flat or concave arc shape is employed. can do. Therefore, it becomes possible to suppress the bending of the outer ring 6 when the radial load F is applied.

Further, in this bearing device, as shown in FIG. 4 , since both ends of the clearance surface 17 in the circumferential direction are smoothly connected to the fitting surface 16, they fit with the clearance surface 17 of the outer ring 6. When the connecting portion of the face 16 attacks the fitting face 15 of the housing 2, excessive face pressure can be prevented from being generated.

Further, in this bearing device, even when a maximum radial load is applied to the rolling bearing 3, the clearance surface 17 and the fitting surface 15 do not come into contact and a radial clearance 18 is ensured between them. Since the surface 17 is formed, it is possible to reliably suppress the creep phenomenon even when the radial load F applied to the rolling bearing 3 is large.

In the above embodiment, the clearance surface 17 is formed on the outer ring 6 of the outer ring 6 and the housing 2, which fit each other in a loosely fitted relationship, but the clearance surface 17 is provided on the housing 2 instead of the outer ring 6. (17) may be formed. That is, in the housing 2, clearance surfaces 17 extending over the entire axial width of the fitting surface 15 are spaced apart in the circumferential direction so as to divide the fitting surface 15 of the housing 2 in the circumferential direction. A configuration in which two or more are formed may be employed.

Further, in the above embodiment, the rolling bearing 3 to which the outer ring 6 and the housing 2 fit loosely has been described as an example, but in this invention, the inner ring 5 and the shaft 1 are It can also be applied to rolling bearings 3 fitted in a loose fit relationship. In this case, a clearance surface 17 is formed on one of the members of the inner ring 5 and the shaft 1 that fit each other in a loosely fitted relationship.

Specifically, as shown in FIG. 7 , the clearance surface extending over the entire width of the fitting surface 13 in the axial direction to the inner ring 5 so as to divide the fitting surface 13 of the inner ring 5 in the circumferential direction. A configuration in which two or more (three in the drawing) are formed at intervals in the circumferential direction can be adopted. In this way, even when the direction of the radial load F applied to the rolling bearing 3 fluctuates, as in the case where a rotational load is applied to the rolling bearing 3, the wave deformation of the inner ring 5 does not occur. It is not easily transmitted to the shaft 1 as a traveling wave, and thus the creep phenomenon can be effectively suppressed. In addition, on the shaft 1, clearance surfaces 17 extending over the entire width of the fitting surface 14 in the axial direction are provided at intervals in the circumferential direction so as to divide the fitting surface 14 of the shaft 1 in the circumferential direction. A structure in which two or more are formed can also be employed.

It should be thought that the embodiment disclosed this time is an example in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the scope and meaning equivalent to the claims are included.

1: axis 2: housing
3: rolling bearing 5: inner ring (raceway ring)
6: outer ring (guide ring) 13, 14, 15, 16: mating surface
17: clearance surface 18: radial clearance

Claims (7)

As a bearing device,
Axis 1 and
A housing 2 surrounding the outer circumference of the shaft 1;
A rolling bearing (3) supporting a radial load between the shaft (1) and the housing (2)
to provide,
The rolling bearing 3 has a bearing ring loosely fitted with a mating member that is either one of the shaft 1 and the housing 2,
In the bearing device, wherein the bearing ring and the mating member have cylindrical fitting surfaces that fit with each other,
On one member of the bearing ring and the mating member, there are two clearance surfaces 17 spaced apart in the circumferential direction extending over the full axial width of the fitting surface so as to divide the fitting surface of the member in the circumferential direction. A bearing device characterized in that it is formed abnormally. The bearing device according to claim 1, wherein the clearance surface (17) is formed on the bearing ring. 3. The method of claim 2, wherein the mating member is the housing (2),
The bearing device, wherein the bearing ring is an outer ring (6). The bearing device according to claim 3, wherein the clearance surface (17) is provided in a range of 3 or more and 6 or less at equal intervals in the circumferential direction on the outer circumference of the outer ring (6). According to claim 3 or 4, wherein the relief surface (17) is a convex arc-shaped curved surface formed to pass radially inside the radial position of the fitting surface (16) of the outer ring (6). In-bearing device. The bearing device according to any one of claims 3 to 5, wherein both ends of the clearance surface (17) in the circumferential direction are smoothly connected to the fitting surface (16) of the outer ring (6). The clearance surface (17) according to any one of claims 3 to 6, even when a maximum radial load is applied to the rolling bearing (3), the clearance surface (17) and the housing (2) ) is formed so that the radial gap 18 is secured between the fitting surfaces 15 without contact.

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