Deep groove ball bearing

Abstract

To provide a deep groove ball bearing capable of securing the strength of a retainer while inhibiting heating.SOLUTION: A deep groove ball bearing 1 comprises: an inner race 2, which is an inner member; an outer race 3, which is an outer member; a plurality of balls 4 interposed between these inner and outer races 2, 3; and a waveform retainer 5 that retains these balls 4. A band width h, which is the radial-direction dimension of the waveform retainer 5, is set to be from 30% to 44%, inclusive, of a diameter BD of the balls 4. Limiting the upper limit value of the band width h to 44% or less of the ball diameter has the effect of allowing grease to flow easily and the effect of decreasing the stirring force of the grease, thereby inhibiting a temperature increase of the deep groove ball bearing 1 during a rapid acceleration rotation. Since the lower limit value of the band width h is set to at least 30% of the ball diameter, the movement of the balls 4 stabilizes, and it is possible to satisfy the required retainer strength.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a deep groove ball bearing used, for example, in an electric motor which is a main drive source of a railway vehicle.

Background Art

[0002] In a deep groove ball bearing provided with a metal wave-shaped cage, a technique of performing shot peening on the pocket surface of the cage has been proposed (Patent Document 1). By performing shot peening on the pocket surface, a deep groove ball bearing having excellent wear resistance and capable of reducing heat generation has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Deep groove ball bearings are used in a wide range of applications. When this deep groove ball bearing is used, for example, in an electric motor which is a main drive source of a railway vehicle, rapid acceleration rotation frequently occurs, so the deep groove ball bearing may generate more heat.

[0005] An object of the present invention is to provide a deep groove ball bearing capable of suppressing heat generation and ensuring the strength of the cage.

Means for Solving the Problems

[0006] The deep groove ball bearing of the present invention comprises an inner member and an outer member, raceway surfaces formed on the outer circumferential surface of the inner member and the inner circumferential surface of the outer member, a plurality of balls interposed between the raceway surfaces, and a corrugated retainer that holds the plurality of balls. The corrugated retainer is formed by axially combining two annular retaining plates, each having a hemispherical bulge arranged along the circumferential direction and a flat portion connecting adjacent hemispherical bulges in the circumferential direction. The annular retaining plates have rivet holes formed for connecting the axially overlapping flat portions with rivets, the diameter of the rivet holes being 25% to 35% of the band width h, which is the radial dimension of the corrugated retainer, and the band width h, which is the radial dimension of the corrugated retainer, being 30% to 44% of the diameter of the balls.

[0007] By limiting the upper limit of the corrugated cage width h to 44% or less of the ball diameter, (1) the clearance between the corrugated cage and the balls becomes larger than in typical deep groove ball bearings. This allows lubricants such as grease to easily enter and exit the space between the corrugated cage and the balls during bearing operation. (2) The area of ​​the corrugated cage in contact with the lubricant is reduced, which can reduce the agitation force of the lubricant adhering to the inner and outer members. The effect of allowing the lubricant to flow easily (1) and the effect of reducing the agitation force of the lubricant (2) can suppress the temperature rise of deep groove ball bearings during rapid acceleration. By setting the lower limit of the waveform holder's bandwidth h to 30% or more of the ball diameter, the ball's movement is stabilized, and the required holder strength can be met.

[0008] The bandwidth h of the corrugated retainer may be set to 30% or more and 40% or less of the diameter of the ball. By limiting the upper limit of the bandwidth h to 40% or less of the ball diameter, heat generation in the bearing can be suppressed, and the amount of retainer material can be reduced, thereby lowering manufacturing costs.

[0009] The corrugated retainer is made up of two annular retaining plates arranged in the circumferential direction, each having a hemispherical bulge and a flat section connecting adjacent hemispherical bulges in the circumferential direction. The diameter of the rivet holes for connecting the axially overlapping flat sections may be set to 25% or more and 35% or less of the band width h. In this case, the strength of the retainer can be more reliably ensured. If the diameter of the rivet holes exceeds 35% of the band width h, the radial dimension of the retainer at the rivet-connected portion becomes smaller, which is undesirable in terms of the strength of the retainer. If the diameter of the rivet holes is less than 25% of the band width h, the rivets become small in diameter and may not be able to withstand the connection between the flat sections.

[0010] A notch may be provided on the inner or outer diameter edge of the pocket portion of the corrugated cage. In this case, during bearing operation, the grease accumulated in the stationary space is supplied to the raceway surface from the notch by centrifugal force. In other words, a portion of the grease that would otherwise remain in the stationary space is drawn off by the notch, causing the grease base oil to separate and be supplied sequentially from the notch to the inside of the cage, the ball surface, and the raceway surface. This suppresses heat generation in the deep groove ball bearing. Because a notch is provided in the pocket portion, the grease shear resistance between the ball and the pocket portion is reduced, resulting in lower torque and lower heat generation in the deep groove ball bearing.

[0011] At the start of operation, the presence of the notches increases the amount of grease adhering to the surface of the balls, making it easier for the grease to be discharged from the moving space to the stationary space. This reduces the break-in time for the grease. The stationary space refers to the space within the bearing space that the balls and cage do not pass through when the bearing rotates.

[0012] The radial distance IP from the inner diameter of the corrugated retainer to the diameter of the retainer pitch circle and the radial distance OP from the outer diameter of the corrugated retainer to the diameter of the retainer pitch circle may be such that IP ≥ OP when the inner member of the deep groove ball bearing rotates, and OP ≥ IP when the outer member of the deep groove ball bearing rotates.

[0013] In the case of an inner member rotation type: The rotation of the inner member causes grease to be ejected radially outward, and grease accumulates on the inner circumferential surface of the outer member. Therefore, when the radial distance OP is smaller than the radial distance IP, i.e., IP ≥ OP, the amount of grease accumulated on the inner circumferential surface of the outer member and the agitation volume of the outer diameter of the corrugated cage are reduced, making it less likely for the deep groove ball bearing to overheat. In the case of an outer member rotation type: Since grease accumulates on the outer surface of the inner member, if the radial distance IP is smaller than the radial distance OP, i.e., OP ≥ IP, the agitation volume is reduced, and the temperature rise of the deep groove ball bearing can be suppressed. [Effects of the Invention]

[0014] In the deep groove ball bearing of the present invention, the diameter of the rivet holes in the corrugated cage is set to 25% to 35% of the band width h, which is the radial dimension of the corrugated cage, and the band width h is set to 30% to 44% of the diameter of the balls, thereby suppressing heat generation and ensuring the strength of the cage. [Brief explanation of the drawing]

[0015] [Figure 1] This is a longitudinal cross-sectional view of a deep groove ball bearing according to the first embodiment of the present invention. [Figure 2] This is a perspective view of the annular retaining plate in the corrugated retainer of the deep groove ball bearing. [Figure 3] This is a horizontal cross-sectional view of the main part of the waveform holder. [Figure 4] This is an enlarged view of section IV in Figure 1. [Figure 5A] This is a front view of an annular retaining plate in a corrugated retainer for a deep groove ball bearing according to a second embodiment of the present invention. [Figure 5B] This is a front view of an annular retaining plate in a corrugated retainer for a deep groove ball bearing according to a third embodiment of the present invention. [Figure 6A] This is a longitudinal cross-sectional view of the main part of a deep groove ball bearing according to a fourth embodiment of the present invention. [Figure 6B] This is a longitudinal cross-sectional view of the main part of a deep groove ball bearing according to a fifth embodiment of the present invention. [Modes for carrying out the invention]

[0016] [First Embodiment] A deep groove ball bearing according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. In this specification, the deep groove ball bearing may be simply referred to as a bearing. [Schematic Configuration of Deep Groove Ball Bearing] FIG. 1 is a longitudinal sectional view of a deep groove ball bearing 1 according to an embodiment, seen by cutting it with a virtual plane passing through the bearing axis and the ball center. The deep groove ball bearing 1 is used, for example, in an electric motor or the like which is the main driving source of a railway vehicle. However, the deep groove ball bearing 1 can also be applied to uses other than the electric motor. The deep groove ball bearing 1 shown in FIG. 1 includes an inner ring 2 which is an inner member, an outer ring 3 which is an outer member, balls 4, and a wave-shaped cage 5. A plurality of balls 4 interposed between the raceway surfaces 2a and 3a of the inner and outer rings 2 and 3 are held by the wave-shaped cage 5 at regular intervals in the circumferential direction. A lubricant such as grease is enclosed in the bearing space between the inner and outer rings 2 and 3. The inner and outer rings 2 and 3 and the balls 4 are made of, for example, high-carbon chromium bearing steel such as SUJ2 or martensitic stainless steel. However, it is not limited to these steels. A seal member (not shown) for closing the bearing space may be attached to the outer ring 3.

[0017] [Wave-shaped Cage 5] The wave-shaped cage 5 is a wave-shaped cage in which two annular retaining plates 5a, 5a having hemispherical bulging portions 6 (FIG. 2) arranged at predetermined intervals along the circumferential direction are combined in the axial direction. The wave-shaped cage may be simply referred to as a cage. Each annular retaining plate 5a shown in FIG. 2 has a hemispherical bulging portion 6 arranged along the circumferential direction and a flat portion ⑦ connecting the hemispherical bulging portions 6 adjacent in the circumferential direction.

[0018] As shown in FIG. 3, in the state where these annular retaining plates 5a, 5a are combined, the flat portions 7 are overlapped in the axial direction, and these flat portions 7, 7 are connected by a rivet Rb. Opposing hemispherical bulging portions 6 form ring-shaped pocket portions 8, and balls 4 are held in each pocket portion 8. Each annular retaining plate 5a in FIG. 2 is, for example, a press-worked product of a strip steel of cold-rolled steel. The diameter of the rivet hole Rh for connecting the flat portions 7 to each other with a rivet Rb (FIG. 3) is set to be 25% or more and 35% or less of the strip width h described later.

[0019] <Regarding band width h> The band width h, which is the radial dimension of the corrugated cage 5 (Figure 1), is set to 30% to 44% of the diameter BD of the ball 4, preferably 30% to 40% of the diameter BD of the ball 4, as shown in Figure 1. By narrowly limiting the upper limit of the band width h to 44% or less of the diameter BD of the ball 4, the clearance δ between the corrugated cage 5 and the ball 4, as shown in Figure 4, becomes larger than that of a typical deep groove ball bearing. The clearance δ refers to the radial gap between the side edges of the pocket portion 8 and the ball 4. By setting the lower limit of the band width h to 30% or more of the diameter BD of the ball 4, the movement of the ball 4 is stabilized, and the necessary cage strength can be satisfied.

[0020] There are three types of methods to narrow the bandwidth h: (1) increasing the inner diameter of the waveform retainer 5 (retainer inner diameter), (2) decreasing the outer diameter of the waveform retainer 5 (retainer outer diameter), or (3) increasing the inner diameter of the retainer and decreasing the outer diameter of the retainer.

[0021] <Exam> In this study, rapid acceleration tests were conducted on deep groove ball bearings (designation number: 6311) equipped with corrugated steel retainers in each of the four embodiments (Examples 1-4) where the band width h was narrowed, and with corrugated retainers in the comparative example where the band width was not narrowed.

[0022] <Test Conditions> Lubrication method: Grease lubrication for railway vehicle traction motors (Grease quantity: 40g) Radial load: 160 kgf Rotational speed: The rotational speed was set to the inner ring rotation, and both rapid acceleration rotation and a constant rotational speed were assumed to correspond to the rotational speed equivalent to the actual operating conditions of the main motor. Temperature: The temperature of the fixed outer ring or the housing on which the outer ring is installed was measured using a temperature sensor, etc., and the temperature rise was recorded.

[0023] <Test Data> [Table 1] The ratio of the band width of each example to the band width of the comparative example is the value obtained by dividing the band width of each example by the band width of the comparative example. For example, in Example 1, the ratio of 0.99 is obtained by dividing the band width of Example 1 (9.05) by the band width of the comparative example (9.1) and rounding to the third decimal place.

[0024] <Test Results> The following was revealed from the test: Examples 1-4 demonstrate that the temperature rise of the bearing can be suppressed by reducing the width of the cage band compared to the comparative example. • In Example 3, where the outer diameter of the cage is reduced for a bearing with an inner ring rotation, the temperature rise of the bearing can be suppressed more effectively than in Example 2, where the inner diameter of the cage is increased. The most effective was the deep groove ball bearing of Example 4, which enlarges the inner diameter of the cage and reduces the outer diameter of the cage.

[0025] <Effects and Effects> As described above, with the deep groove ball bearing 1 shown in Figure 1, by limiting the upper limit of the width h of the corrugated cage 5 to 44% or less of the diameter BD of the ball 4, (1) the clearance δ (Figure 4) between the corrugated cage 5 and the ball 4 becomes larger than that of a typical deep groove ball bearing. This allows grease to easily enter and exit the space between the corrugated cage 5 and the ball 4 during bearing operation. (2) The area of ​​the corrugated cage 5 that comes into contact with the grease is reduced, which can reduce the stirring force of the grease adhering to the inner and outer rings 2 and 3. The effect of allowing the grease to flow easily (1) and the effect of reducing the agitation force of the grease (2) make it possible to suppress the temperature rise of the deep groove ball bearing 1 during rapid acceleration rotation. By setting the lower limit of the bandwidth h of the waveform holder 5 to 30% or more of the diameter BD of the ball 4, the movement of the ball 4 is stabilized, and the required holder strength can be satisfied.

[0026] By limiting the upper limit of the band width h to 40% or less of the diameter BD of the ball 4, heat generation in the bearing 1 can be suppressed, and the amount of cage material can be reduced, thereby lowering manufacturing costs. The diameter of the rivet hole Rh for connecting the overlapping flat sections 7 in Figure 2 with rivets Rb (Figure 3) is set to be between 25% and 35% of the band width h. In this case, the strength of the retainer can be more reliably ensured. If the diameter of the rivet hole Rh exceeds 35% of the band width h, the radial dimension of the retainer at the rivet connection becomes smaller, which is unfavorable for the strength of the retainer. If the diameter of the rivet hole Rh is less than 25% of the band width h, the rivet becomes too small and may not be able to withstand the connection between the flat sections 7.

[0027] <Regarding other embodiments> In the following description, parts corresponding to matters previously described in each embodiment will be denoted by the same reference numerals, and redundant explanations will be omitted. When only a part of the configuration is described, the other parts of the configuration will be the same as those in the previously described embodiment unless otherwise specified. Identical configurations will produce the same effects. Not only are combinations of the parts specifically described in each embodiment possible, but partial combinations of embodiments are also possible, provided that there are no particular problems with the combination.

[0028] [Second embodiment: Figure 5A (notch on the inner diameter edge)] As shown in Figure 5A, notches 9 may be provided on the inner diameter edge of the pocket portion 8 of the corrugated retainer 5. Specifically, the notches 9 are provided so as to recess the inner diameter edge of each pocket portion 8 toward the outer diameter. The notches 9 have a curved shape that is a concave curved surface when viewed from the axial direction. The notches 9 are formed such that the width h is smallest in the middle of the circumferential direction of the pocket portion 8, and the width h gradually increases along the curved shape as it moves from the middle of the circumferential direction toward both sides of the circumferential direction. These notches 9 may be formed, for example, by machining after punching and forming the steel strip with a press, or they may be formed during the press working process.

[0029] In this configuration, during bearing operation, grease accumulated in the stationary space is supplied to the raceway surface from the notch 9 by centrifugal force. In other words, a portion of the grease that would otherwise remain in the stationary space is drawn off by the notch 9, causing the grease base oil to separate and be supplied sequentially from the notch to the inside of the cage 5, the ball surface, and the raceway surface. This suppresses heat generation in the deep groove ball bearing. Because the notch 9 is provided in the pocket 8, the grease shear resistance between the ball and the pocket 8 is reduced, resulting in lower torque and lower heat generation in the deep groove ball bearing.

[0030] At the start of operation, the presence of the notch 9 increases the amount of grease adhering to the surface of the balls that is scraped off, making it easier for the grease to be discharged from the moving space to the stationary space. This reduces the break-in time for the grease.

[0031] [Third embodiment: Figure 5B (notch on the outer edge)] As shown in Figure 5B, a notch 10 may be provided on the outer diameter edge of the pocket portion 8 of the corrugation holder 5. The notch 10 is provided so as to recess the outer diameter edge of each pocket portion 8 toward the inner diameter. The notch 10 has a curved shape that is a concave curved surface when viewed from the axial direction. It has the same configuration and effects as the second embodiment described above. The notches 9 and 10 on the inner and outer diameter edges may each have multiple concave curved surfaces formed in each pocket portion 8. Furthermore, the notches 9 and 10 are not limited to concave curved surfaces and may be formed in an angular or polygonal shape. Notches 9 and 10 may be provided on both the inner and outer diameter edges.

[0032] [Fourth embodiment: Figure 6A (inner ring rotating type)] As shown in Figure 6A, a deep groove ball bearing 1A limited to an inner ring rotation type may also be used. Specifically, the radial distance IP from the inner diameter of the corrugated cage 5 to the cage pitch circle diameter PCD and the radial distance OP from the outer diameter of the corrugated cage 5 to the cage pitch circle diameter PCD are set such that IP ≥ OP when the inner ring 2 of the deep groove ball bearing 1A rotates. In the case of an inner ring rotating type, the rotation of the inner ring 2 causes grease to be ejected radially outward, and grease accumulates on the inner surface of the outer ring 3. Therefore, when the radial distance OP is smaller than the radial distance IP, i.e., IP ≥ OP, the amount of grease accumulated on the inner surface of the outer ring 3 and the agitation volume of the outer diameter of the corrugated retainer 5 are reduced, making it less likely for the deep groove ball bearing 1A to overheat.

[0033] [Fifth Embodiment: Figure 6B (Outer Ring Rotating Type)] As shown in Figure 6B, a deep groove ball bearing 1B may be limited to an outer ring rotation type. Specifically, when the outer ring 2 of the deep groove ball bearing 1B rotates, OP ≥ IP. In the case of an outer ring rotating type, grease accumulates on the outer surface of the inner ring 2, so if the radial distance IP is smaller than the radial distance OP, i.e., OP ≥ IP, the stirring volume is reduced, and the temperature rise of the deep groove ball bearing 1B can be suppressed.

[0034] The waveform holder 5 may have two annular holding plates 5a, 5a whose flat portions are connected to each other via engaging claws or the like. Waveform holders are independently traded in the market. These waveform holders are described as follows: A corrugated retainer for a deep groove ball bearing comprising an inner member, an outer member, a plurality of balls interposed between the inner and outer members, and a corrugated retainer that holds these balls, A waveform holder in which the band width h, which is the radial dimension of the waveform holder, is 30% or more and 44% or less of the diameter of the ball.

[0035] The inner member includes, for example, those in which the inner ring and shaft are integrated, and those in which gears are formed on the inner surface of the inner ring, etc. The outer member includes those in which the outer ring and housing are integrated, and those in which gears, flanges, etc. are formed on the outer surface of the outer ring, etc. The term "integrated" means that the raceway and the object are not formed by combining multiple elements, but are formed from a single material, for example by forging, machining, etc., as part of or as a whole of a single object.

[0036] In a deep groove ball bearing, the sealing member (not shown) that closes the bearing space may be provided on only one side. Lubricants other than grease may be used as lubricants for deep groove ball bearings. Deep groove ball bearings can be applied to vehicles other than railway vehicles, industrial machinery, machine tools, robots, conveying machinery, etc.

[0037] While embodiments of the present invention have been described above, the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope of equivalence to the claims are intended to be included. [Explanation of Symbols]

[0038] 1, 1A, 1B... Deep groove ball bearing, 2... Inner ring (internal member), 3... Outer ring (external member), 4... Ball, 5... Corrugated cage, 6... Hemispherical bulge, 7... Flat section, 9, 10... Notch, Rb... Rivet

Claims

1. an inner member and an outer member; a raceway surface formed on an outer circumferential surface of the inner member and an inner circumferential surface of the outer member; A plurality of balls interposed between the raceway surfaces; A deep groove ball bearing including a corrugated cage for holding the plurality of balls, The wave cage is formed by combining in the axial direction two annular retaining plates each having a hemispherical bulge portion disposed along the circumferential direction and a flat portion connecting the hemispherical bulge portions adjacent in the circumferential direction, the annular retaining plate is formed with rivet holes for connecting the flat portions overlapping in the axial direction with rivets, and the diameter of the rivet holes is set to 25% to 35% of a band width h, which is a radial dimension of the corrugated retainer; A deep groove ball bearing in which the band width h is 30% or more and 44% or less of the diameter of the ball.

2. 2. The deep groove ball bearing according to claim 1, wherein the width h of the wave cage is 30% to 40% of the diameter of the balls.

3. 3. The deep groove ball bearing according to claim 1, wherein a notch is provided on an inner diameter edge or an outer diameter edge of the pocket of the wave cage.

4. In the deep groove ball bearing as described in claim 1 or 2, the radial distance IP from the inner diameter of the wavy cage to the cage pitch circle diameter and the radial distance OP from the outer diameter of the wavy cage to the cage pitch circle diameter are such that IP ≧ OP when the inner member of the deep groove ball bearing rotates, and OP ≧ IP when the outer member of the deep groove ball bearing rotates.

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