CN116816819A

CN116816819A - Bearing structure of speed reducer

Info

Publication number: CN116816819A
Application number: CN202310269911.3A
Authority: CN
Inventors: 尾崎圭太朗; 阿部瞬; 富永拓人
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2022-03-28
Filing date: 2023-03-20
Publication date: 2023-09-29
Also published as: JP2023144284A; DE102023107527A1

Abstract

The application aims to provide a bearing structure of a speed reducer, which can inhibit abrasion caused by contact between a flange part and a cylindrical roller. A bearing structure (10) of a speed reducer according to an embodiment comprises an outer ring (2), an inner ring (3), and a plurality of cylindrical rollers (4) disposed between the outer ring (2) and the inner ring (3) in a freely rolling manner, wherein at least one of the outer ring (2) and the inner ring (3) has a collar (5) provided with a rolling surface (56) on which the cylindrical rollers (4) roll and a flange portion (57) on which the cylindrical rollers (4) are restrained from moving in the axial direction, and the rolling surface (56) forms an angle of more than 90 degrees with the flange portion (57).

Description

Bearing structure of speed reducer

The present application claims priority based on japanese patent application No. 2022-051193 filed on 28 of 3 months of 2022. The entire contents of this japanese application are incorporated by reference into the present specification.

Technical Field

The application relates to a bearing structure of a speed reducer.

Background

In a speed reducer, a bearing is known in which a supported member is rotatably supported by a support member. For example, patent document 1 discloses a bearing that rotatably supports a first member and a second member. The bearing includes an outer ring, an inner ring, and a plurality of rollers and retainers disposed therebetween.

Patent document 1: japanese patent application laid-open No. 2019-19962

The inner ring of the bearing described in patent document 1 has a flange portion formed thereon, the flange portion protruding radially outward from the rolling surface and having an outer diameter accommodated in an inner periphery of the seal portion. The flange portion has a claw portion extending in a direction orthogonal to a radial direction of the inner ring. The claw portion is formed over the entire circumference in the circumferential direction of the inner ring. In this bearing, when the outer ring and the inner ring rotate relative to each other, the end surfaces of the rollers rub against the claw portions of the flange portion to wear, and powder such as iron powder is generated. If a large amount of powder is generated in the bearings of the speed reducer, the amount of powder that intrudes into the speed reducer increases, and the surfaces of the internal components including the first and second components are damaged, which results in a problem of deterioration in durability of the speed reducer.

Disclosure of Invention

The present application has been made in view of the above problems, and an object thereof is to provide a bearing structure of a speed reducer capable of suppressing wear caused by contact between a flange portion and a cylindrical roller.

In order to solve the above-described problems, a bearing structure of a speed reducer according to an embodiment of the present application includes an outer ring, an inner ring, and a plurality of cylindrical rollers disposed between the outer ring and the inner ring so as to be freely rotatable, wherein at least one of the outer ring and the inner ring has a rolling surface on which the cylindrical rollers roll and a flange portion that restricts movement of the cylindrical rollers in an axial direction, and the rolling surface forms an angle of more than 90 degrees with the flange portion.

Any combination of the above components or substitution of the components or expressions of the present application with each other in methods, systems, and the like is also effective as an embodiment of the present application.

Drawings

Fig. 1 is a cross-sectional view showing an example of a speed reducer to which a bearing structure according to the embodiment is applied.

Fig. 2 is a view schematically showing a contact portion between a flange portion and a cylindrical roller of the bearing structure of fig. 1.

Fig. 3 is a perspective view showing a flange portion and cylindrical rollers of the bearing structure of the comparative example.

Fig. 4 is a cross-sectional view showing a longitudinal section taken along the line AC-AC of fig. 3 and a longitudinal section taken along the line AD-AD.

Fig. 5 is an enlarged cross-sectional view of the area surrounded by rectangle B of fig. 4.

Fig. 6 is a view schematically showing a contact portion between the flange portion and the cylindrical roller in fig. 5.

Fig. 7 is a schematic view of the contact portion of the cylindrical roller as seen from a viewpoint parallel to the end face of the cylindrical roller of fig. 3.

In the figure: 2-outer ring, 3-inner ring, 4-cylindrical roller, 5-ferrule, 10-bearing structure, 42-end face, 42-axial end face, 44-chamfer portion, 45-convex portion, 52-corner portion, 56-rolling surface, 57-flange portion, 58-front end portion, 90-bearing structure, 100-speed reducer.

Detailed Description

Hereinafter, preferred embodiments of the present application will be described with reference to the accompanying drawings. In the embodiment and the modification, the same or equivalent constituent elements and components are denoted by the same reference numerals, and overlapping description thereof is omitted as appropriate. Also, in each drawing, the size of the representing components is appropriately enlarged or reduced for ease of understanding. In the drawings, parts of components not essential to the description of the embodiments are omitted.

The terms including the numbers 1 and 2 are used to describe various components, but the terms are only used for the purpose of distinguishing one component from other components, and the components are not limited by the terms.

Embodiment(s)

A structure of a bearing structure 10 (hereinafter, simply referred to as a "bearing structure 10") of a speed reducer according to an embodiment will be described with reference to fig. 1 and 2. Fig. 1 is a cross-sectional view showing an example of a speed reducer 100 to which a bearing structure 10 according to an embodiment of the present application is applied. Hereinafter, for convenience, the right side in the drawing in the direction along the central axis La of the input shaft 81 of the speed reducer 100 will be referred to as the input side, and the left side in the drawing will be referred to as the input opposite side. Fig. 2 is a diagram schematically showing a contact portion between the flange portion 57 of the bearing structure 10 and the cylindrical roller 4. Fig. 2 (a) shows a vertical cross section taken along a vertical plane including the central axis Lb of the cylindrical roller 4, fig. 2 (B) shows an enlarged vertical cross section, and fig. 2 (C) shows a view from the point of view indicated by the arrow S. Hereinafter, the direction along the central axis Lb of the cylindrical roller 4 of the bearing structure 10 is referred to as "axial direction", and the circumferential direction and the radial direction of a circle centered on the central axis Lb are referred to as "circumferential direction" and "radial direction", respectively.

First, the overall structure of the speed reducer 100 to which the bearing structure 10 is applied will be described. The speed reducer 100 is a speed reducer that reduces the rotation input to the input shaft 81 and outputs the rotation from the output member. The speed reducer 100 can employ various speed reducing mechanisms based on known principles. In the example of fig. 1, the speed reducer 100 is a planetary gear type speed reducer having external gears 85, 86 and an internal gear 88 that mesh with each other. The bearing structure 10 can be applied to bearings of portions of the speed reducer 100 disposed between one member and the other member that are rotatable relative to each other. The bearing structure 10 of this example is applied to the annular housing 82 and the main bearings 61, 62 arranged between the wheel carriers 83, 84. The wheel frames 83, 84 are supported on the housing 82 via main bearings 61, 62. One of the housing 82 and the carriers 83 and 84 functions as a fixed member fixed to an external member (not shown) for supporting the speed reducer 100, and the other functions as an output member for outputting rotational power to the driven member (not shown).

The bearing structure 10 will be described. As shown in fig. 1, the bearing structure 10 is an angular contact roller bearing having an outer ring 2, an inner ring 3, a plurality of cylindrical rollers 4, and a retainer 63. The outer ring 2 and the inner ring 3 have rolling surfaces on which the cylindrical rollers 4 roll, respectively. The plurality of cylindrical rollers 4 are arranged between the outer ring 2 and the inner ring 3 so as to be freely rotatable. The retainer 63 holds the plurality of cylindrical rollers 4 at a prescribed position. In this example, the inner ring 3 is integrally formed with the wheel frames 83, 84, and the outer ring 2 is accommodated in the inner peripheral surface of the housing 82.

As shown in fig. 2, at least one of the outer ring 2 and the inner ring 3 (hereinafter, referred to as "cage 5") has a rolling surface 56 on which the cylindrical roller 4 rolls and a flange portion 57 that restricts movement of the cylindrical roller 4 in the axial direction. The flange portion may be provided on the outer ring, but in this example, the flange portion 57 is an annular portion that is provided continuously in the circumferential direction at one end of the rolling surface 56 of the inner ring 3. A corner 52 having an annular concave shape is formed between the rolling surface 56 of the ferrule 5 and the flange 57. In particular, the corner 52 is recessed between the rolling surface 56 and the flange 57 toward the side opposite to the cylindrical roller 4.

The cylindrical roller 4 has an outer peripheral portion 41 and two axial end faces 42 connected to both ends of the outer peripheral portion 41. The axial end face 42 is an end face orthogonal to the axial direction at the center thereof. The outer peripheral portion 41 and the axial end face 42 are connected via an end face corner portion, and a chamfer portion 44 is provided at the end face corner portion. In particular, the chamfer portion 44 is provided so that the outer diameter becomes smaller toward the axially outer side between the axial end face and the outer peripheral face of the cylindrical roller 4. The chamfer 44 may be beveled in shape, but in this example has a circular arc shape.

For example, the outer ring 2 and the inner ring 3 may be formed of carburizing steel such as JIS SCM 420. For example, the cylindrical roller 4 may be formed of bearing steel such as the JIS name SUJ 2. For example, the surface hardness of the cylindrical roller 4 may be set to be higher than the surface hardness of the outer ring 2 and the inner ring 3.

First, a bearing structure 90 according to a comparative example will be described with reference to fig. 3 to 7. Fig. 3 to 7 are diagrams schematically showing contact portions between the flange portion 57 of the bearing structure 90 and the cylindrical roller 4. Fig. 3 is a perspective view showing the flange portion 57 of the bearing structure 90 and the cylindrical roller 4. In this figure a cross section of one cylindrical roller 4 is shown. Fig. 4 is a cross-sectional view showing a longitudinal section taken along the line AC-AC of fig. 3 and a longitudinal section taken along the line AD-AD. The AC-AC line section is a section along a vertical plane passing through one of two contact portions C shown in fig. 7 described later. The AD-AD line section is a section along a vertical plane passing through the axial center of the cylindrical roller 4.

Fig. 5 is an enlarged cross-sectional view of the area surrounded by rectangle B of fig. 4. Fig. 6 is a diagram schematically showing the contact portion C between the flange portion 57 and the cylindrical roller 4 in fig. 5. In this figure, the flange 57 shows an outline. Fig. 7 is a schematic view of the flange portion 57 and the contact portion C of the cylindrical roller 4 as viewed from a point of view parallel to the end face of the cylindrical roller 4 of fig. 3, which corresponds to fig. 2 (C). In this figure, the profile of the flange portion 57 and the profile of the cylindrical roller 4 are shown.

The bearing structure 90 of the comparative example was manufactured for comparison in the course of developing the bearing structure 10 of the embodiment. The bearing structure 90 of the comparative example is different from the bearing structure 10 of the embodiment in that the shape of the flange portion 57 and the end surface shape of the cylindrical roller 4 are different, and the other structures are the same, so that the repetitive description thereof is omitted.

As shown in fig. 6, in the bearing structure 90 of the comparative example, the angle θ formed between the rolling surface 56 and the flange portion 57 is set to 90 degrees. The distal end portion 58 of the flange portion 57 is in contact with the axial end face 42 of the cylindrical roller 4. That is, the contact portion C of the axial end face 42 of the cylindrical roller 4 with the flange portion 57 is formed at the distal end portion 58 of the flange portion 57. In the comparative example, as shown in fig. 7, contact portions C are formed at both ends of the axial end face 42, i.e., at two places.

As a result of performing a durability test for a predetermined period of time in a state in which a predetermined load is applied to the main bearings 61 and 62, the reducer 100 having the main bearings 61 and 62 having the bearing structure 90 according to the comparative example was mounted, it was found that the contact portion C (i.e., the distal end portion 58 of the flange portion 57) was worn. This is considered to be because: when the curvature of the contact portion is large, the contact area becomes smaller, the surface pressure becomes higher, and the amount of wear increases, as compared with the case where the curvature is small, and therefore, since the curvature of the distal end portion 58 is large, the contact area of the contact portion C of the comparative example is small, and the amount of wear increases. If the abrasion amount becomes large, the grinding amount increases corresponding to the abrasion amount.

As shown in fig. 1, a part of the ground powder generated by the abrasion of the contact portion C intrudes into the main bearings 61, 62, and another part intrudes into the reduction mechanism including the external gears 85, 86 and the internal gear 88. When the abrasion amount is large, the amount of abrasion powder that intrudes into the reduction gear mechanism increases, and the surfaces of the internal components such as the external gears 85, 86 and the internal gear 88 are damaged, and the durability of the reduction gear decreases. Further, the durability of the main bearings 61, 62 is also reduced by the grinding. Although the abrasion loss of the comparative example is within a practically usable range, it is preferable that the abrasion loss is small from the viewpoint of extending the life of the reduction gear 100.

Next, the bearing structure 10 according to the embodiment will be described with reference to the description of the comparative example. Reference is made to fig. 2. In the embodiment, the angle θ between the rolling surface 56 and the flange 57 is set to be greater than 90 degrees from the viewpoint of reducing the amount of powder generated in comparison with the comparative example. By increasing the angle θ, the distal end portion 58 of the flange portion 57 does not come into contact with the cylindrical roller 4, and the contact portion C moves from the distal end portion 58 of the flange portion 57 to the root side, and the contact area becomes larger than that of the comparative example. By increasing the contact area, the surface pressure is reduced, abrasion is suppressed, and the amount of abrasion powder generated is reduced, as compared with the comparative example.

The results of the experiments, for example, are suggested as follows: when the angle θ between the rolling surface 56 and the flange 57 is in the range of 90.8 ° or more and 91.4 ° or less, the effect of significantly suppressing the occurrence of grinding can be obtained. If the angle θ between the rolling surface 56 and the flange 57 is too large, the cylindrical roller 4 may fall off beyond the flange 57. The following implications may be obtained: when the angle θ is in the range of 95 ° or less, the cylindrical roller 4 can be almost prevented from falling off.

In the embodiment, the chamfer 44 at the corner of the axial end of the outer peripheral portion 41 is larger than that of the comparative example. In particular, the radial width W1 of the chamfer portion 44 at the end face corner of the cylindrical roller 4 is larger than the radial width W2 of the corner portion 52 between the rolling face 56 and the flange portion 57 of the cage 5. Here, the radial width W2 of the corner 52 is a distance (distance in the radial direction of the cylindrical roller 4) between the rolling surface 56 and an intersection point of the inner surface of the flange 57 and the corner 52. The axial width W3 of the chamfer 44 of the cylindrical roller 4 is smaller than the radial width W1 of the chamfer 44. In the example of fig. 2, the radial width W2 of the corner 52 is 0.4mm, the radial width W1 of the chamfer 44 is 0.8mm, and the axial width W3 is 0.4mm. By adopting such a shape of the chamfer portion 44, the contact area of the cylindrical roller 4 and the flange portion 57 is further increased by forming the contact portion C near the end point of the chamfer portion 44 having a small curvature.

In the embodiment, as shown in fig. 2 (C), a convex surface portion 45 having an axial width W4 smaller than the axial width W3 of the chamfer portion 44 is formed on the axial end surface 42 of the cylindrical roller 4. In particular, the convex surface portion 45 has a curved surface shape protruding toward the axially outer side on the axial end surface of the cylindrical roller 4. In this example, the reduction ratio of the outer diameter of the convex portion 45 in the axial direction is smaller than the reduction ratio of the outer diameter of the chamfer portion in the axial direction. In fig. 2 (C), the chamfer portion 44 and the convex portion 45 are emphasized in the axial direction for ease of understanding. In the embodiment, as shown in fig. 2 (C), the contact portion C is formed at one position in the middle of the axial end face 42. Further, since the convex surface portion 45 is provided, the curvature at the contact portion C of the axial end surface 42 becomes further smaller, and the contact area becomes further larger.

In the speed reducer 100 to which the main bearings 61 and 62 having the bearing structure 10 according to the embodiment are attached, as a result of performing a durability test for a predetermined period of time in a state in which a predetermined load is applied to the main bearings 61 and 62, it was found that the amount of wear on the contact portion C was reduced to about half that of the comparative example. This is considered to be due to the increase in contact area of the contact portion C.

In the embodiment, the influence of the machining conditions of the flange 57 on the wear amount was also studied. The 1 st machining condition of the flange 57 is lathe machining, and the arithmetic average roughness Ra of the surface roughness is set to 0.6 μm or less. The 2 nd working condition is grinding, and the arithmetic average roughness Ra of the surface roughness is set to be less than 0.3 μm. The wear amount by the endurance test can be set to a desired value or less under any of the processing conditions, but according to the 2 nd processing condition, the wear amount can be reduced more than the 1 st processing condition. Thus, it can be said that: the 1 st processing condition is preferable in terms of a short processing time, and the 2 nd processing condition is preferable in terms of a small amount of wear. These processing conditions can be used differently depending on the purpose.

In the embodiment, the influence of the surface roughness of the axial end face 42 of the cylindrical roller 4 on the abrasion amount was also studied. The 1 st surface roughness condition of the axial end face 42 is set to 0.15 μm or less in arithmetic average roughness Ra, and the 2 nd surface roughness condition is set to 0.1 μm or less in arithmetic average roughness Ra. The wear amount by the endurance test can be set to a desired value or less under any surface roughness condition, but according to the 2 nd surface roughness condition, the wear amount can be reduced more than the 1 st surface roughness condition. Thus, it can be said that: the 1 st surface roughness condition is preferable in terms of short processing time, and the 2 nd surface roughness condition is preferable in terms of small abrasion loss. These surface roughness conditions can be used differently according to the purpose.

Next, features of the bearing structure 10 of the speed reducer having the above-described structure will be described. The bearing structure 10 of the speed reducer of the embodiment includes an outer ring 2, an inner ring 3, and a plurality of cylindrical rollers 4 arranged between the outer ring 2 and the inner ring 3 so as to be freely rotatable, and a cage 5 of at least one of the outer ring 2 and the inner ring 3 includes a rolling surface 56 on which the cylindrical rollers 4 roll and a flange portion 57 which restricts movement of the cylindrical rollers 4 in the axial direction, and the rolling surface 56 forms an angle of more than 90 degrees with the flange portion 57.

According to this structure, the area of the contact portion between the end surface 42 of the cylindrical roller 4 and the flange 57 becomes large, and the occurrence of the grinding can be reduced. Since the occurrence of the grinding is reduced, the amount of the grinding that intrudes into the interior of the speed reducer 100 is reduced, and damage to the internal components of the speed reducer due to the grinding can be reduced, thereby improving the durability of the speed reducer.

The present application has been described above based on the embodiments. These embodiments are examples, and various modifications and variations can be made within the technical scope of the present application, and such modifications and variations are also within the technical scope of the present application, as will be understood by those skilled in the art. Accordingly, the descriptions and drawings in this specification should not be considered as limiting, but rather as illustrative.

(modification)

The following describes modifications. In the drawings and description of the modification, the same or equivalent constituent elements and components as those of the embodiment are denoted by the same reference numerals. The description repeated with the embodiments is omitted appropriately, and the structure different from the embodiments is mainly described.

In the above description, an example in which the bearing structure 10 is applied to the main bearings 61, 62 of the speed reducer 100 is shown, but the present application is not limited thereto. The bearing structure of the present application may be applied to bearings of a speed reducer other than the main bearing, for example, to bearings that support an input shaft of a speed reducer.

In the above description, an example in which the speed reducer 100 to which the bearing structure 10 is applied is a planetary gear type speed reducer is shown, but the present application is not limited thereto. For example, the bearing structure of the present application can be applied to various known speed reducers such as cup-shaped or top hat-shaped flex engagement speed reducers and simple gear speed reducers.

In the above description, the example in which the flange portion 57 of the ferrule 5 is provided to the inner ring 3 is shown, but the present application is not limited to this. The flange portion may be provided on the outer ring, or may be provided on both the inner ring and the outer ring.

In the above description, an example in which the outer ring 2 and the inner ring 3 are formed of the SCM420 and the cylindrical rollers 4 are formed of the SUJ2 is shown, but the present application is not limited thereto. The outer ring, the inner ring, and the cylindrical roller may be formed of any material as long as a desired amount of wear can be achieved.

These modifications can also obtain the same operations and effects as those of the embodiment.

Any combination of the above embodiments and modifications is also effective as an embodiment of the present application. The new embodiment produced by the combination has the effects of both the combined embodiment and the modification.

Claims

1. A bearing structure of a speed reducer is characterized in that,

the rolling bearing comprises an outer ring, an inner ring and a plurality of cylindrical rollers arranged between the outer ring and the inner ring in a rolling manner, wherein at least one of the outer ring and the inner ring is provided with a rolling surface for the cylindrical rollers to roll and a flange part for limiting the cylindrical rollers to move along the axial direction, and the angle between the rolling surface and the flange part is larger than 90 degrees.

2. The bearing structure of a speed reducer according to claim 1, wherein,

the distal end portion of the flange portion is not in contact with the cylindrical roller.

3. The bearing structure of a speed reducer according to claim 1 or 2, wherein,

a chamfer part with the outer diameter decreasing with the direction of the outer side in the axial direction is arranged between the axial end surface and the outer peripheral surface of the cylindrical roller,

a corner portion recessed toward the side opposite to the cylindrical roller is provided between the rolling surface and the flange portion,

the chamfer has a radial width greater than a radial width of the corner.

4. The bearing structure of a speed reducer according to claim 3,

the axial width of the chamfer portion of the cylindrical roller is smaller than the radial width of the chamfer portion.

5. The bearing structure of a speed reducer according to claim 3 or 4,

a convex surface portion having a curved surface shape protruding outward in the axial direction is formed on an axial end surface of the cylindrical roller.

6. The bearing structure of a speed reducer according to claim 5, wherein,

the reduction ratio of the outer diameter of the convex portion in the axial direction is smaller than the reduction ratio of the outer diameter of the chamfer portion in the axial direction.