Rolling bearings

Abstract

A rolling bearing comprises: an outer ring (2) as a fixed ring; an inner ring (4) as a rotating ring; and a rolling element (6) between the outer ring (2) and the inner ring (4); a mating surface (2a) for mating with an object component is provided on the radially opposite side of the outer ring (2) to the raceway surface; two annular grooves (10) for mounting an elastic component (11); and a recessed portion (9) adjacent to the annular groove (10) and having a bottom surface (9a) with an outer diameter smaller than that of the mating surface (2a).

Description

Technical Field

[0001] The invention relates to rolling bearings. Background Art

[0002] A shaft of a transmission of an automobile is rotatably supported by a rolling bearing.

[0003] In recent years, in order to save fuel, the automobile transmission has been miniaturized and lightweight, so there is a trend to make the rings of the rolling bearings or the housing of the transmission thin. Therefore, depending on the specifications and load conditions of the rolling bearings, there is a possibility that the fixed ring of the rolling bearings creeps relative to the housing.

[0004] In order to suppress the occurrence of creep, there is known a rolling bearing in which O-rings are mounted in circumferential grooves formed on both axial sides of the outer peripheral surface of a stationary ring (see Patent Document 1).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-215061

[0006] However, in the rolling bearing of Patent Document 1, in order to suppress the occurrence of creep, there is a tendency to install an O-ring with a larger diameter. Therefore, it is necessary to increase the wall thickness of the fixing ring. As a result, it is difficult to achieve both creep suppression and miniaturization of the rolling bearing. Summary of the invention

[0007] Therefore, an object of the present invention is to provide a rolling bearing capable of achieving both creep suppression and miniaturization.

[0008] In order to solve the above-mentioned problems, the present invention can adopt the following structure: the rolling bearing comprises: a fixed ring; a rotating ring rotating relative to the above-mentioned fixed ring; and a rolling element between the above-mentioned fixed ring and the above-mentioned rotating ring, and on the radially opposite side of the raceway surface in the above-mentioned fixed ring, there are provided: a fitting surface that fits into the object part; at least one annular groove for installing the elastic part; and a recessed portion adjacent to the above-mentioned annular groove and having a bottom surface with an outer diameter smaller than that of the above-mentioned fitting surface.

[0009] According to the present invention, it is possible to provide a rolling bearing that can achieve both creep suppression and downsizing. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional view showing a rolling bearing according to a first embodiment of the present invention.

[0011] Figure 2 It is an enlarged cross-sectional view showing a main part of a rolling bearing according to a first embodiment of the present invention.

[0012] Figure 3 It is a cross-sectional view showing a state where the rolling bearing according to the first embodiment of the present invention is fitted into a housing.

[0013] Figure 4 It is a cross-sectional view showing a rolling bearing according to a second embodiment of the present invention.

[0014] Figure 5 It is an enlarged cross-sectional view showing a main part of a rolling bearing according to a second embodiment of the present invention.

[0015] Figure 6 It is a cross-sectional view showing a state where a rolling bearing according to a second embodiment of the present invention is fitted into a housing.

[0016] Figure 7 It is an enlarged cross-sectional view showing an example of a transmission including a rolling bearing according to the present invention. DETAILED DESCRIPTION

[0017] based on Figure 1 to Figure 3 A rolling bearing 1 according to a first embodiment of the present invention will be described. The rolling bearing 1 according to this embodiment is used, for example, in a transmission of an automobile as described later. Thus, the rolling bearing 1 is a rolling bearing for an automobile. Figure 1 As shown, the rolling bearing 1 is a ball bearing and includes an outer ring 2 , an inner ring 4 arranged radially inward of the outer ring 2 , a plurality of balls 6 that are rolling elements interposed between the outer ring 2 and the inner ring 4 , and a cage 7 .

[0018] The ball bearing 1 is of an inner ring rotating type in which the outer ring 2 is a fixed ring and the inner ring 4 is a rotating ring that rotates relative to the outer ring 2. Alternatively, the ball bearing 1 may be of an outer ring rotating type in which the outer ring 2 is a rotating ring.

[0019] In this embodiment, the direction along the bearing center axis of the ball bearing 1 is called the "axial direction", the direction orthogonal to the bearing center axis of the ball bearing 1 is called the "radial direction", and the circumferential direction around the bearing center axis of the ball bearing 1 is called the "circumferential direction".

[0020] The outer ring 2 has a raceway surface 3 on its inner circumference for rolling of the balls 6. The raceway surface 3 can contact the balls 6 at a nominal contact angle of 0° over the entire circumference.

[0021] The outer ring 2 has a fitting surface 2a, a recess 9, and at least one (here, multiple) annular groove 10 on its outer periphery, i.e., on the side opposite to the raceway surface 3 in the radial direction. The fitting surface 2a is provided on both axial sides of the outer peripheral surface of the outer ring 2. The fitting surface 2a is a cylindrical surface. A chamfered portion is provided between the fitting surface 2a and the axial end surface of the outer ring 2.

[0022] The housing H (for example, a transmission housing of an automobile) as a counterpart is fitted on the fitting surface 2a. The outer ring 2 and the housing H are loosely fitted. During operation, the fitting surface 2a of the outer ring 2 contacts the housing H due to a radial load applied to the ball bearing 1.

[0023] like Figure 2 As shown, the recess 9 is arranged at a position where the axial position overlaps with the raceway surface 3. The recess 9 is arranged at the axial center of the outer peripheral surface of the outer ring 2. The recess 9 has a cylindrical bottom surface 9a. The outer diameter of the bottom surface 9a is smaller than the outer diameter of the fitting surface 2a. The axial length of the bottom surface 9a is longer than the axial length of the fitting surface 2a. The axial end edge of the bottom surface 9a is located axially outside the axial end edge of the raceway surface 3.

[0024] In the present embodiment, the depth a1 of the recess 9 is such that it cannot contact the housing H fitted to the fitting surface 2a during operation. In the present embodiment, when the outer diameter dimension of the fitting surface 2a of the outer ring 2 is set to d1 and the outer diameter dimension of the bottom surface 9a is set to d2, the depth a1 of the recess 9 is calculated by (d1-d2) / 2.

[0025] Table 1 shows the evaluation results of the wear resistance of the bottom surface 9a and the miniaturization of the ball bearing 1 when the depth a1 of the recessed portion 9 was changed. In Table 1, "○" means good, and "×" means poor.

[0026] [Table 1]

[0027] a1(mm) Wear-resistant Miniaturization Comprehensive evaluation Comparative Example 1 0.04 × ○ × Example 1 0.05 ○ ○ ○ Example 2 0.10 ○ ○ ○ Example 3 0.20 ○ ○ ○ Example 4 0.30 ○ ○ ○ Example 5 0.40 ○ ○ ○ Example 6 0.50 ○ ○ ○ Comparative Example 2 0.60 ○ × ×

[0028] According to Table 1, if the depth a1 of the recess 9 is less than 0.05 mm, the bottom surface 9a contacts the housing H during operation, causing wear on the bottom surface 9a. If the depth a1 of the recess 9 is greater than 0.5 mm, it is known that in order to reduce the strain of the outer ring 2 continuously generated by the rolling element load during the operation of the ball bearing 1, it is necessary to ensure a large wall thickness between the bottom surface 9a and the raceway surface 3, making it difficult to achieve miniaturization of the ball bearing 1. Therefore, it is known that as a comprehensive evaluation, the depth a1 of the recess 9 is optimal when it satisfies 0.05 mm ≤ a1 ≤ 0.50 mm.

[0029] The recessed portion 9 is adjacent to the annular groove 10. Two annular grooves 10 are provided on the outer peripheral surface of the outer ring 2. The annular grooves 10 are provided axially outside the recessed portion 9. Each annular groove 10 is provided between the recessed portion 9 and the fitting surface 2a. The annular groove 10 has a groove bottom surface 10a. The groove bottom surface 10a is a cylindrical surface. The groove depth c1 of the annular groove 10 is greater than the depth a1 of the recessed portion 9 relative to the fitting surface 2a.

[0030] An annular elastic member 11 is mounted in the annular groove 10 with a predetermined interference. The elastic member 11 is an O-ring. The material of the elastic member 11 is, for example, nitrile rubber, acrylic rubber, fluororubber, silicone rubber, or the like.

[0031] The elastic member 11 partially protrudes radially from the fitting surface 2a by a protrusion amount b1 when installed in the annular groove 10. When the fitting surface 2a of the outer ring 2 is fitted into the housing H, the elastic member 11 is compressed radially by the housing H. In addition, the cross-sectional shape of the elastic member 11 is not limited to a circle, and may be a polygon or a V-shape.

[0032] Table 2 shows the evaluation results of creep resistance of the bottom surface 9a and assemblability of the bearing 1 when the compression amount X of the elastic member 11 based on the housing H is changed relative to the diameter D1 of the elastic member 11. In Table 2, "◎" means extremely good, "○" means good, and "×" means poor.

[0033] [Table 2]

[0034] X / D1(%) Creep resistance Assembling Comprehensive evaluation Comparative Example 1 3 × ◎ × Example 1 5 ○ ◎ ○ Example 2 10 ○ ○ ○ Example 3 15 ○ ○ ○ Example 4 20 ◎ ○ ○ Comparative Example 2 25 ◎ × × Comparative Example 3 30 ◎ × ×

[0035] According to Table 2, if the compression amount X is less than 5% relative to the diameter D1 of the elastic member 11, when the outer ring 2 is fitted into the housing H, the restoring force and the pressing force generated by the elastic deformation of the elastic member 11 become small, and the generation of creep cannot be suppressed. If the compression amount X is greater than 20% relative to the diameter D1 of the elastic member 11, it is known that the fitting of the housing H and the outer ring 2 becomes difficult, and the assembly performance deteriorates.

[0036] Therefore, it can be seen that as a comprehensive evaluation, the protrusion amount b1 of the elastic member 11 from the fitting surface 2a is set to the maximum based on the compression amount X of the housing H, and it is best to set it to 5 to 20% relative to the diameter D1 which is the radial thickness of the elastic member 11. In addition, the diameter D1 of the elastic member 11 means the diameter when it is installed in the annular groove 10 and is not compressed by the housing H.

[0037] The inner ring 4 has a raceway surface 5 on its outer periphery for rolling balls 6. The raceway surface 5 can contact the balls 6 at a nominal contact angle of 0° over the entire circumference.

[0038] The inner ring 4 has a fitting surface 4 a on its inner circumference. A rotating shaft S (for example, a rotating shaft provided in a transmission of an automobile) as a counterpart member fits into the fitting surface 4 a. The balls 6 are held by a retainer 7 .

[0039] When the ball bearing 1 is running, if the rolling element load acts on the raceway surface 3 of the outer ring 2, the bottom surface 9a of the recessed portion 9 on the radially opposite side of the raceway surface 3 is deformed in a wave-like manner. When the ball bearing 1 rotates, the ball 6 also revolves, so the wave-like deformation of the bottom surface 9a occurs in the circumferential direction.

[0040] In the present embodiment, the depth a1 of the recessed portion 9 is such that the recessed portion 9 does not come into contact with the housing H during operation. Therefore, a radial gap is left between the housing H and the bottom surface 9 a of the recessed portion 9 .

[0041] If a radial gap is left, as described above, the bottom surface 9a of the recessed portion 9 of the outer ring 2 is in a non-contact state with the housing H even if it is deformed in a wave-like manner, thereby preventing the wave-like deformation from acting as a traveling wave causing the outer ring 2 to creep.

[0042] Thus, when the ball bearing 1 is in operation, the only part of the outer ring 2 that contacts the housing H is the fitting surface 2a. Therefore, the occurrence of creep can be suppressed only in the contact portion between the housing H and the fitting surface 2a by the friction force of the elastic member 11 compressed by the housing H. Therefore, the friction force of the elastic member 11 can be reduced compared to a conventional ball bearing that does not have the recessed portion 9.

[0043] The frictional force of the elastic member 11 can be reduced by reducing the radial size (diameter D1) of the elastic member 11 for ensuring the frictional force. Therefore, the depth c1 of the annular groove 10 in the outer ring 2 can be reduced by providing the recessed portion 9 .

[0044] This is because if the depth c1 of the annular groove 10 is reduced, it is not necessary to increase the thickness of the outer ring 2. It is possible to achieve both creep suppression and miniaturization of the ball bearing 1.

[0045] Next, Figures 4 to 6 The rolling bearing of the second embodiment of the present invention is shown. The rolling bearing 21 of this embodiment is different from the first embodiment in that the rolling bearing is a tapered roller bearing. In addition, the differences from the first embodiment are described below, and the same components as the first embodiment are marked with the same reference numerals.

[0046] The tapered roller bearing 21 includes an outer ring 22 , an inner ring 24 arranged radially inward of the outer ring 22 , a plurality of tapered rollers 26 that are rolling elements interposed between the outer ring 22 and the inner ring 24 , and a cage 27 that holds the tapered rollers 26 .

[0047] The tapered roller bearing 21 is of an inner ring rotating type in which the outer ring 22 is a fixed ring and the inner ring 24 is a rotating ring that rotates relative to the outer ring 22 .

[0048] The outer ring 22 has a raceway surface 23 on its inner periphery for rolling of the tapered roller 26. The outer ring 22 has a fitting surface 22a, a recess 9 and an annular groove 10 on its outer periphery, i.e., on the radially opposite side to the raceway surface 23. The fitting surface 22a is provided on both axial sides of the outer peripheral surface of the outer ring 22. During operation, the fitting surface 22a of the outer ring 22 contacts the housing H due to the radial load applied to the tapered roller bearing 21.

[0049] The axial width dimension of the recessed portion 9 is smaller than the roller length of the tapered roller 26. The recessed portion 9 is located axially inward of both end surfaces of the tapered roller 26.

[0050] like Figure 5As shown, the depth a2 of the recess 9 is a size that prevents it from contacting the housing H engaged with the engaging surface 22a during operation. In the present embodiment, when the outer diameter dimension of the engaging surface 22a of the outer ring 22 is set to d3 and the outer diameter dimension of the bottom surface 9a is set to d4, it is calculated using (d3-d4) / 2 and is set to 0.05 to 0.50 mm.

[0051] The annular groove 10 is arranged axially outside the recess 9 and at the end (one end) on the axial back side. The annular groove 10 is formed to have a depth in the radial direction, and the groove depth c2 of the annular groove 10 relative to the fitting surface 22a is greater than the depth a2 of the recess 9 relative to the fitting surface 22a.

[0052] The elastic member 11 partially protrudes in the radial direction from the fitting surface 22a by a protrusion amount b2 when installed in the annular groove 10. The protrusion amount b2 of the elastic member 11 from the fitting surface 22a is set to the maximum based on the compression amount X of the housing H, and is set to 5 to 20% relative to the diameter D2 which is the thickness of the elastic member 11 in the radial direction.

[0053] The inner ring 24 has a raceway surface 25 on which the tapered rollers 26 roll, a small flange 24a located on the smaller diameter side (one axial side) of the raceway surface 25, and a large flange 24b located on the larger diameter side (the other axial side) of the raceway surface 25 on its outer periphery.

[0054] The inner ring 24 has a fitting surface 24c extending in the circumferential direction on the inner peripheral side. A rotating shaft S (for example, a rotating shaft provided in a transmission of an automobile) as a counterpart member is fitted into the fitting surface 24c.

[0055] The tapered roller bearing 21 of the second embodiment is configured as described above. The tapered roller bearing 21 has a radial recess 9 formed on the fitting surface 22a of the outer ring 22, and the recess 9 is provided on the radially opposite side of the raceway surface 23. The depth a2 of the recess 9 is such that it cannot contact the housing H fitted on the fitting surface 22a during operation.

[0056] During operation, the tapered roller bearing 21 is in a state where a radial gap is left between the housing H and the bottom surface 9a of the recess 9. If this radial gap is left, as described above, the bottom surface 9a of the recess 9 of the outer ring 2 is in a non-contact state where it does not contact the housing H even if it deforms in a wave-like manner, and no creep occurs, similar to the case of the ball bearing 1 of the first embodiment.

[0057] In addition, when the tapered roller bearing 21 is running, the housing H is in contact with only the portion of the fitting surface 22a of the outer ring 22 that is axially outward from the recess 9. In the second embodiment of this state, as in the first embodiment, the friction force of the elastic member 11 can be reduced compared to the conventional structure in which the entire axial width of the fitting surface of the outer ring is in contact with the housing.

[0058] Figure 7 An example of a structure in which a rotating shaft provided in a transmission for an automobile is supported by the rolling bearing of the first embodiment or the second embodiment described above is shown.

[0059] Figure 7 The transmission 30 shown is a multi-stage transmission that changes the speed ratio in stages, and has a rolling bearing A that is embedded in the housing H (part of the transmission) and supports the rotating shaft (such as the input shaft (omitted from the figure) and the output shaft S1) so that it can rotate, and has the rolling bearing of the above-mentioned first embodiment or second embodiment.

[0060] The transmission shown in the figure has: an input shaft for inputting the rotation of the engine; an output shaft S1 provided in parallel with the input shaft; a plurality of gear trains G1 to G4 for transmitting the rotation from the input shaft to the output shaft S1; and a clutch (not shown) installed between each gear train G1 to G4 and the input shaft or the output shaft S1. The transmission is a transmission that changes the speed ratio of the rotation transmitted from the input shaft to the output shaft S1 by selectively engaging the clutch to switch the gear train G1 to G4 used. The rotation of the output shaft S1 is output to the output gear G5, and the rotation of the output gear G5 is transmitted to the differential gear, etc.

[0061] In addition, the transmission applies the splashed or sprayed lubricating oil to the side surfaces of each rolling bearing A by splashing the lubricating oil accompanying the rotation of the gears or by spraying the lubricating oil from a nozzle (not shown) provided inside the housing H.

[0062] When the rolling bearing of the first embodiment or the second embodiment is in operation, a gap is left between the fitting surfaces (2a, 22a) of the housing H and the outer ring (2, 22), and the housing H is in a non-contact state with the bottom surface 9a of the recess 9. Therefore, it is not necessary to retain grease in the recess 9 in advance, and grease-free operation is possible.

[0063] Description of Reference Numerals

[0064] 1…rolling bearing (ball bearing); 2…outer ring; 2a…fitting surface; 3…raceway surface; 4…inner ring; 4a…fitting surface; 5…raceway surface; 6…ball (rolling element); 9…recess; 9a…bottom surface; 10…annular groove; 11…elastic component; 21…rolling bearing (tapered roller bearing); 22…outer ring; 22a…fitting surface; 23…raceway surface; 24…inner ring; 25…raceway surface; 26…tapered roller (rolling element).

Claims

1. A rolling bearing, wherein: have: Fixed ring; a rotating circle that rotates relative to the fixed circle; and A rolling element is disposed between the fixed ring and the rotating ring. The fixed ring is provided with a fitting surface fitted to a target component on the radially opposite side of the raceway surface; at least one annular groove for mounting an elastic component; and a recessed portion adjacent to the annular groove and having a bottom surface with an outer diameter smaller than that of the fitting surface, wherein the fixed ring is an outer ring of the bearing, and the rotating ring is an inner ring of the bearing. The elastic component is an O-ring, and the depth of the recess is set to 0.3-0.5 mm.

2. The rolling bearing according to claim 1, wherein: The elastic member is set to have a thickness in a radial direction of 5 to 20% based on an amount of compression of the counterpart member.

3. The rolling bearing according to claim 1 or 2, wherein: The rolling elements are balls, The at least one annular groove is a plurality of annular grooves, The recessed portion is provided between the plurality of annular grooves.

4. The rolling bearing according to claim 1 or 2, wherein: The rolling elements are tapered rollers.

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