Ball bearing

Abstract

Provided is a ball bearing capable of preventing vibration of a cage while preventing deformation of the cage in a harmonic gear device. A ball bearing (1) is provided with: a deformable inner ring (2); a deformable outer ring (3) provided on the outside of the inner ring (2); a plurality of spherical rolling bodies (4) provided between the inner ring (2) and the outer ring (3); and a cage (5) in which a plurality of pockets (10) for accommodating the plurality of rolling bodies (4) are provided at intervals in the circumferential direction. Each of the plurality of pockets (10) has: a pocket surface (11) extending around a pocket axis (x1) extending in a radial direction; and a flange section (20) that protrudes from the pocket surface (11) toward the pocket axis (x1). The pocket surface (11) accommodates the rolling elements (4) with a gap therebetween, and the flange section (20) is in contact with at least the rolling elements (4) located at the short-diameter (rb) position of the inner ring (2) from the inside in the radial direction.

Description

Technical Field

[0001] The present invention relates to ball bearings. Background Art

[0002] As a speed reducer, a harmonic gear device that can obtain a high reduction ratio is known. One type of harmonic gear device has an elliptical wave generator on its outer peripheral surface. The wave generator has an elliptical cam and a ball bearing provided on the outer peripheral surface of the elliptical cam. The inner and outer rings of the ball bearing are deformable, and the outer peripheral surfaces of the inner and outer rings are deformed in the radial direction corresponding to the elliptical shape of the outer peripheral surface of the elliptical cam as the elliptical cam rotates, thereby performing harmonic motion.

[0003] Through this harmonic motion, the rotation space between the inner ring and the outer ring moves radially when viewed from a fixed position in the circumferential direction. That is, at the position of the long axis of the elliptical cam, the rotation space is located at the radially outermost side, and at the position of the short axis of the elliptical cam, the rotation space is located at the radially innermost side. On the other hand, the retainer of the ball bearing is an annular rigid member. Therefore, when the retainer is supported (guided) by the spherical rolling element, the retainer will deform. Due to this deformation, the retainer is sometimes damaged. In order to prevent this damage, in the ball bearing of the existing harmonic gear device, the retainer is not supported by the rolling element, and the rolling element is accommodated in a manner with a large gap relative to the retainer. The retainer of such a ball bearing can move relative to the rolling element, so vibration will be generated (for example, refer to patent document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Publication No. 6-103060 Summary of the invention

[0007] Problems to be solved by the invention

[0008] As described above, the ball bearing of the conventional wave gear device requires a structure capable of preventing the cage from being deformed and preventing the cage from being vibrated.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a ball bearing capable of preventing deformation of a cage and vibration of a cage in a wave gear device.

[0010] Solutions for solving problems

[0011] In order to achieve the above-mentioned purpose, the ball bearing of the present invention comprises: a deformable inner ring; a deformable outer ring, which is arranged on the outside of the inner ring; a plurality of spherical rolling elements, which are arranged between the inner ring and the outer ring; and a retaining frame, which is provided with a plurality of pockets spaced apart in the circumferential direction to respectively accommodate the plurality of rolling elements, wherein the plurality of pockets each have: a pocket surface, which is a surface extending around an axis extending in the radial direction; and a flange portion, which is a portion protruding from the pocket surface toward the axis side, the pocket surface accommodating the rolling elements across a gap, the flange portion contacts the rolling elements at least at the position of the short diameter of the inner ring from the radial inside, or the flange portion contacts the rolling elements at least at the position of the long diameter of the inner ring from the radial outside.

[0012] Effects of the Invention

[0013] According to the ball bearing of the present invention, it is possible to prevent the deformation of the cage and the vibration of the cage in the wave gear device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a partial cross-sectional view of the ball bearing according to the first embodiment of the present invention.

[0015] Figure 2 It means that there is Figure 1 A diagram showing an example of a ball bearing harmonic gearing device.

[0016] Figure 3 yes Figure 1 A partial perspective view of the cage in the ball bearing shown.

[0017] Figure 4 It is a magnified representation Figure 3 Figure 2 shows a pocket of a cage.

[0018] Figure 5 is along relative to Figure 4 A sectional view of the cage on a section of line AA where the pocket axis extends in the radial direction.

[0019] Figure 6 is an enlarged representation of Figure 1 A diagram showing the vicinity of a rolling element at the position of the minor diameter of the inner ring of a ball bearing.

[0020] Figure 7 It is enlarged to show Figure 1 A view showing the vicinity of a rolling element located at the position of the minor axis of the inner ring in the ball bearing shown.

[0021] Figure 8 It is enlarged to show Figure 1 A view showing the vicinity of a rolling element located at the position of the major axis of the inner ring in the ball bearing shown.

[0022] Fig. 9 It is a diagram for showing a modified example of the flange portion of the ball bearing according to the first embodiment of the present invention.

[0023] Fig.10 It is a diagram for showing another modified example of the flange portion of the ball bearing according to the first embodiment of the present invention.

[0024] Fig.11 It is a partial cross-sectional view of a ball bearing according to a second embodiment of the present invention.

[0025] Fig.12 It is a magnified representation Fig.11 A diagram of a cage pocket in a ball bearing is shown.

[0026] Fig.13 It is along Fig.12 A sectional view of the retainer on a section of line DD extending in the radial direction of the pocket.

[0027] Fig.14 It is enlarged to show Fig.11 A view showing the vicinity of a rolling element located at the position of the major diameter of the inner ring in the ball bearing shown.

[0028] Fig.15 It is enlarged to show Fig.11 A view showing the vicinity of a rolling element located at the position of the major diameter of the inner ring in the ball bearing shown.

[0029] Fig.16 It is enlarged to show Fig.11 A view showing the vicinity of a rolling element located at a position of the minor diameter of the inner ring in the ball bearing shown.

[0030] Fig.17 It is a diagram showing a modified example of the flange portion of the ball bearing according to the second embodiment of the present invention.

[0031] Fig.18 It is a diagram showing another modified example of the flange portion of the ball bearing according to the second embodiment of the present invention.

[0032] Fig.19 This is an enlarged view showing the vicinity of a rolling element and a pocket located at the position of the minor diameter of a ball bearing according to a third embodiment of the present invention in a wave gear device.

[0033] Fig. 20 is along relative to Fig.19 The illustrated embodiment is a cross-sectional view of the cage and rolling elements on a cross section of a line GG where the pocket axes extend in the radial direction.

[0034] Fig.21This is a diagram showing an enlarged view of the rolling element and the vicinity of the pocket located at the position of the major diameter of the ball bearing in the fourth embodiment of the present invention in the strain wave gear device.

[0035] Fig. 22 is along relative to Fig.21 The illustrated embodiment is a cross-sectional view of the cage and rolling elements on a cross section of a line HH where the pocket axes extend in the radial direction. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0037] Figure 1 FIG. 1 is a partial cross-sectional view of a ball bearing 1 according to a first embodiment of the present invention. Figure 1 In FIG. 1 , the ball bearing 1 is shown in a form in which it is assembled in an elliptical cam 102 of a harmonic gear device 100 described later. The ball bearing 1 is a ball bearing having the following components: a deformable inner ring 2; a deformable outer ring 3 provided outside the inner ring 2; a plurality of spherical rolling elements 4 provided between the inner ring 2 and the outer ring 3; and a retainer 5 having a plurality of pockets 10 provided at intervals in the circumferential direction to accommodate the plurality of rolling elements 4, respectively. Each of the plurality of pockets 10 has a pocket surface 11, which is a surface extending around a pocket axis x1 extending in the radial direction; and a flange portion 20, which is a portion protruding from the pocket surface 11 toward the pocket axis x1 side. The pocket surface 11 accommodates the rolling element 4 with a gap therebetween, and the flange portion 20 contacts the rolling element 4 at least at the position of the short diameter rb of the inner ring 2 from the radial inner side, or contacts the rolling element 4 at least at the position of the long diameter ra of the inner ring 2 from the radial outer side. The ball bearing 1 will be described in detail below. It should be noted that in Figure 1 In the figure, the ball bearing 1 is shown in a state where the inner ring 2 and the outer ring 3 are cut away and the retainer 5 and the rolling elements 4 are fully presented when viewed from the front. In addition, in the figure, no reference numerals are given to all the rolling elements 4, and similarly, no reference numerals are given to all the pockets 10. Similarly, in the figure, no reference numerals are given to all the multiple components, and reference numerals are omitted as appropriate.

[0038] The ball bearing of the present invention is applicable to a harmonic gear device and is used in the harmonic gear device. Figure 21 is a diagram showing a harmonic gear device 100 as an example of a harmonic gear device provided with a ball bearing 1. The ball bearing 1 constitutes a part of a wave generator 101 of the harmonic gear device 100. In the wave generator 101, an elliptical cam 102 is embedded in the inner ring 2 of the ball bearing 1. The wave generator 101 is embedded in a cup-shaped flexible gear 103, and the flexible gear 103 is embedded in a rigid gear 104. In the harmonic gear device 100, the cam 102 rotates, and the inner ring 2 of the ball bearing 1 rotates together with the cam 102. As the elliptical inner ring 2 rotates, each part of the outer peripheral side of the outer ring 3 is deformed in the radial direction via the rolling element 4, and at least the part of the outer ring 3 located on the major axis comes into contact with the flexible gear 103, and the outer peripheral surface of the flexible gear 103 performs harmonic motion. The teeth 103a located in the long axis direction of the flexible gear 103 performing the harmonic motion mesh with the teeth 104a of the rigid gear 104. According to the difference between the number of teeth 103a of the flexible gear 103 and the number of teeth 104a of the rigid gear 104, the rigid gear 104 rotates relative to the flexible gear 103. In addition, the flexible gear 103 or the rigid gear 104 rotates at a reduced speed relative to the rotation of the cam 102.

[0039] The inner ring 2 of the ball bearing 1 has the same shape as the inner ring of the conventionally known ball bearing used in the harmonic gear device, and is a cylindrical or substantially cylindrical member having a flexible or elastic shape with the axis x as the central axis or substantially the central axis. When the elliptical cam 102 is embedded in the inner ring 2, as shown in FIG. Figure 1 As shown in FIG. 1 , the inner ring 2 is deformed into an elliptical cylinder or a substantially elliptical cylinder with the axis x as the central axis or a substantially central axis. In the inner ring 2 in which the elliptical cam 102 is embedded, the surface of the inner ring 2 facing radially outward, i.e., the outer peripheral surface 2a, is an elliptical cylinder surface or a substantially elliptical cylinder surface with the axis x as the central axis or a substantially central axis. Figure 1 As shown, the cross section of the outer peripheral surface 2a perpendicular to the axis x describes an ellipse or a substantially ellipse having a major axis xa and a minor axis xb with a major diameter ra and a minor diameter rb. It should be noted that the axis x is the axis of the ball bearing 1.

[0040] The outer ring 3 has the same shape as the outer ring of the conventionally known ball bearing used in the harmonic gear device. Figure 1 As shown in FIG. 1 , it is a cylindrical flexible or elastic member around the axis x. Figure 1 As shown, the outer ring 3 has a shape similar to that of the inner ring 2 in the ball bearing 1. However, track grooves (not shown) are formed in the inner ring 2 and the outer ring 3, respectively, and the inner ring 2 and the outer ring 3 are not similar in the track grooves.

[0041] like Figure 1As shown, the retainer 5 is a rigid member in the shape of an annulus or a substantially annular ring with the axis x as the central axis or the approximate central axis. The retainer 5 is made of resin, for example. It should be noted that the retainer 5 is not limited to being made of resin, and can also be made of other materials. As described above, the retainer 5 has a plurality of pockets 10, and each pocket 10 accommodates a rolling element 4. It should be noted that the ball bearing 1 has an odd number of rolling elements 4, and in the example shown in the figure, the ball bearing 1 has 23 rolling elements 4. Each pocket 10 extends along the pocket axis x1 extending in a radial direction orthogonal to the axis x, and passes through the retainer 5 between the inner peripheral surface 5a and the outer peripheral surface 5b of the retainer 5. It should be noted that the inner peripheral surface 5a is the surface of the retainer 5 facing radially inward, and the outer peripheral surface 5b is the surface of the retainer 5 facing radially outward. The radius of the inner circumferential surface 5 a of the retainer 5 is larger than the major diameter of the outer circumferential surface 2 a of the inner ring 2 , and the radius of the outer circumferential surface 5 b of the retainer 5 is smaller than the minor diameter of the inner circumferential surface 3 a of the outer ring 3 in the ball bearing 1 .

[0042] Figure 3 is a partial stereogram of the retaining frame 5, Figure 4 is an enlarged view showing the pocket 10 of the cage 5. Figure 5 is along relative to Figure 4 A cross-sectional view of the cage 5 on the cross section of the line AA extending in the radial direction along the pocket axis x1. It should be noted that: Figure 4 1 represents the pocket 10 when viewed from the outer peripheral surface 5b side toward the inner peripheral surface 5a side in the pocket axis x1 direction. Figure 3 , 4 As shown, the retainer 5 has a plurality of claws 5c extending along the axis x. The claws 5c are formed at intervals in the circumferential direction around the axis x, and each pocket 10 is formed between the claws 5c adjacent to each other in the circumferential direction. The ends (top ends 5d) of the claws 5c adjacent to each other in the circumferential direction on one side of the axis x direction are not connected, forming a gap, and each pocket 10 is open on one side of the axis x direction. Figure 4 As shown, between the top ends 5d of the claws 5c adjacent to each other in the circumferential direction, the surface (open surface 5e) of the top ends 5d facing the circumferential direction forms an open portion 5f for opening the pocket 10. The open surface 5e is connected to the pocket surface 11 and the flange 20 on the other side of the axis x direction.

[0043] like Figure 3 As shown, the pocket axis x1 of each pocket 10 extends parallel or substantially parallel to the radial direction, for example, and the plurality of pockets 10 are arranged at equal or substantially equal angular intervals around the axis x1. In addition, the pocket surface 11 of each pocket 10 can accommodate the rolling element 4 with a gap in the radial direction (hereinafter also referred to as the pocket radial direction) orthogonal to the pocket axis x1, and the radius r1 (refer to Figure 4) is larger than the radius of the rolling element 4. The pocket surface 11 is, for example, a conical surface, a cylindrical surface, or a portion of a substantially cylindrical surface with the pocket axis x1 as the center axis or the approximate center axis. The pocket surface 11 may also be a conical surface, a cylindrical surface, or a portion of a substantially cylindrical surface extending along a line passing through the axis x or a point near the pocket axis x1 and close to the pocket axis x1. The pocket surface 11 can accommodate the rolling element 4 with a gap in the entire range in the direction of the pocket axis x1, for example Figure 5 As shown, the radius r1 of the pocket surface 11 is the same over the entire range in the direction of the pocket axis x1 (r1a=r1b), or increases in diameter from the flange 20 side toward the outer peripheral surface 5b side in the direction of the pocket axis x1 (r1b>r1a). It should be noted that the radius r1a is the radius r1 of the pocket surface 11 at the end on the flange 20 side, and the radius r1b is the radius r1 of the pocket surface 11 at the end on the outer peripheral surface 5b side. In the connection portions 10a and 10b where the pocket surface 11 and the pair of open surfaces 5e are connected respectively, the rolling element 4 accommodated in the pocket 10 does not protrude from the pocket 10 in the direction of the axis x, for example, the interval between the connection portions 10a and 10b is smaller than the diameter of the rolling element 4.

[0044] like Figure 4 , Figure 5 As shown, the flange portion 20 of each pocket 10 is a portion extending around the pocket axis x1 that protrudes further inward than the pocket surface 11 in the pocket radial direction. In this embodiment, it has a form of contacting the rolling element 4 located at least at the position of the short diameter rb of the inner ring 2 from the inside in the radial direction. It should be noted that Figure 1 As shown, the rolling element 4 located at the position of the short diameter rb of the inner ring 2 refers to the rolling element 4 that contacts the position of the short diameter rb of the outer peripheral surface 2a of the inner ring 2 in the ball bearing 1, and is the rolling element 4 whose center is located on the short axis xb of the inner ring 2. The flange portion 20 is, for example, in a form that prevents the pocket 10 from moving relative to the rolling element 4 when contacting the rolling element 4 located at the position of the short diameter rb of the inner ring 2 from the inner side in the radial direction, so that the retainer 5 is supported by the rolling element 4. It should be noted that the pocket 10 cannot move relative to the rolling element 4 means that the position of the rolling element 4 in the pocket 10 does not change, and the relative movement of the pocket 10 with respect to the rolling element 4 does not include the rotation of the rolling element 4.

[0045] For example Figure 5 As shown, the radius (radius r2) of the flange portion 20 on the cross section (cross section B) perpendicular to the pocket axis x1 at a predetermined radial position (position p1) in the radial direction (in the direction of the pocket axis x1) of the ball bearing 1 within the range (range s1) on the pocket axis x1 of the flange portion 20 and the radius (radius r3) of the rolling element 4 on the cross section (cross section C) perpendicular to the minor axis xb at a predetermined radial position p1 on the minor axis xb of the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 (refer to Figure 6) are the same or approximately the same value. It should be noted that, Figure 6 This is an enlarged view showing the vicinity of the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 of the ball bearing 1 . Figure 6 The cage 5 is omitted. In addition, the cross section B and the cross section C are the same cross section in the ball bearing 1.

[0046] Specifically, for example Figure 5 As shown, the flange portion 20 is disposed adjacent to the pocket surface 11 in the radial direction of the ball bearing 1 and is disposed only at the inner end of the pocket 10 in the pocket axis x1 direction. Figure 5 As shown, the flange portion 20 has an inclined surface 21, which is a surface extending around the pocket axis x1 and expanding in diameter toward the side in the direction of contact with the rolling element 4 (radial outer side of the ball bearing 1) in the pocket axis x1 direction. In addition, the flange portion 20, for example, protrudes continuously along the pocket surface 11 around the pocket axis x1. Specifically, for example Figure 4 As shown, the flange portion 20 extends along a circular ring or a substantially circular ring extending around the pocket axis x1 between the open surfaces 5e of each of the pair of claw portions 5c, extending longer than a semicircle. Figure 5 As shown, the shapes of the cross sections perpendicular to the extending direction of the flange portion 20 are the same or substantially the same.

[0047] As mentioned above, Figure 5 As shown, the projection range of the inclined surface 21 onto the pocket axis x1 in the pocket radial direction is range s1, and the radius of the cross section B at the radial position p1 within range s1 is radius r2. Figure 6 As shown, the radius r3 at the cross section C at the radial position p1 on the minor axis xb of the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 is the same or substantially the same value as the radius r2 at the inclined surface 21 of the flange portion 20. Therefore, as described later Figure 7 As shown, the radius r2 portion of the inclined surface 21 of the flange portion 20 contacts the radius r3 portion of the circumferential surface of the rolling element 4 located at the position of the short diameter rb of the inner ring 2 from the inside in the radial direction of the ball bearing 1. The position p1 is located, for example, inside the center of the width of the pocket 10 in the direction of the pocket axis x1. It should be noted that, as Figure 5 , Figure 6 As shown, the radius of the ball bearing 1 at the radial position p1 is rp1.

[0048] The inclined surface 21 of the flange portion 20 is, for example, Figure 5As shown, it is a conical surface that draws a straight line or a substantially straight line on a cross section including the pocket axis x1. The inclined surface 21 is not limited to such a conical surface, and as described above, it can also be a surface of other shapes as long as it is a surface that contacts the rolling element 4 located at least at the position of the short diameter rb of the inner ring 2 from the inside in the radial direction of the ball bearing 1 at the position of the radius r2 at the radial position p1. For example, the inclined surface 21 can be a surface that draws a circular arc or an arc convex to the side of the pocket axis x1 on a cross section including the pocket axis x1, or a surface that draws a circular arc or an arc concave to the opposite side of the pocket axis x1, or a surface that draws other curves. In addition, the inclined surface 21 can also be a surface that draws a line composed of a curve and a straight line on a cross section including the pocket axis x1.

[0049] In addition, if Figure 5 As shown, each pocket 10 may also have a relief portion 12 on the inner side in the direction of the pocket axis x1 of the flange portion 20. The relief portion 12 extends between the inner end (inner end 21a) of the inclined surface 21 of the flange portion 20 in the direction of the pocket axis x1 and the inner peripheral surface 5a of the retainer 5, and is, for example, a conical surface, a cylindrical surface, or a part of a substantially cylindrical surface with the pocket axis x1 as the center axis or the approximate center axis. The form of the relief portion 12 is not limited to this form. Like the pocket surface 11, the relief portion 12 may also be, for example, a part of a conical surface, a cylindrical surface, or a substantially cylindrical surface extending along a line passing through the axis x or a point near the pocket axis x1.

[0050] Next, the operation of the ball bearing 1 having the above-described structure will be described. Figure 7 FIG. 1 is an enlarged view showing the vicinity of the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 in the ball bearing 1. Figure 8 This is an enlarged view showing the vicinity of the rolling element 4 located at the position of the major diameter ra of the inner ring 2 in the ball bearing 1.

[0051] In the harmonic gear device 100, when the cam 102 rotates, the inner ring 2 rotates around the axis x together with the rotation of the cam 102, and the retainer 5 rotates around the axis x together with the plurality of rolling elements 4 as the inner ring 2 rotates. The outer peripheral surface 2a of the inner ring 2 is elliptical, and each rolling element 4 describes an elliptical orbit centered on the axis x. The position of each rolling element 4 at the short diameter rb of the inner ring 2 is closest to the axis x in the radial direction. Then, the radial position of each rolling element 4 moves away from the axis x as it approaches the position of the long diameter ra, and the position of each rolling element 4 at the long diameter ra of the inner ring 2 is farthest from the axis x in the radial direction. Furthermore, the radial position of each rolling element 4 approaches the axis x as it approaches the position of the short diameter rb. The rolling element 4 repeatedly moves radially in this way while orbiting the outer peripheral surface 2a of the inner ring 2.

[0052] On the other hand, the retainer 5 is a rigid member in an annular shape, and each pocket 10 of the retainer 5 describes a circular orbit centered on the axis x. That is, the radial distance of each pocket 10 of the retainer 5 from the axis x remains constant or substantially constant as the retainer 5 rotates, and is fixed. Therefore, each rolling element 4 on the outer peripheral surface 2a of the inner ring 2 moves relative to the pocket 10 in the pocket 10 in which it is accommodated, in the direction of the pocket axis x1. The position of each rolling element 4 at the short diameter rb of the inner ring 2 moves relative to the pocket 10 in the direction of the pocket axis x1 to the innermost side, and the position of the long diameter ra of the inner ring 2 moves relative to the pocket 10 in the direction of the pocket axis x1 to the outermost side.

[0053] like Figure 7 As shown, the rolling element 4 located at the position of the short diameter rb of the inner ring 2, which has moved most relatively to the inner side in the direction of the pocket axis x1 relative to the pocket 10, contacts the inclined surface 21 of the flange portion 20 of the pocket 10. Specifically, the portion of the radius r2 of the inclined surface 21 on the cross section B (C) at the position p1 radially away from the axis x by the radius rp1 contacts the portion of the radius r3 of the rolling element 4 on the cross section C (B) at the position p1 radially away from the axis x by the radius rp1. Due to the contact between the flange portion 20 and the rolling element 4, the retainer 5 is supported by the rolling element 4 and cannot move relatively to the outer side in the pocket radial direction and the radial direction of the ball bearing 1 relative to the rolling element 4.

[0054] like Figure 7 As shown, when the rolling element 4 is located on the track of the rolling element 4, the position of the short diameter rb of the inner ring 2 on one side (at Figure 1 When the rolling element 4 is not located at the position of the minor diameter rb of the inner ring 2 on the other side of the track of the rolling element 4 (in Figure 1 However, the two rolling elements 4 are located at the position of the short diameter rb of the inner ring 2 on the other side of the track of the rolling element 4 (at Figure 1 The two rolling elements 4 or one of the two rolling elements 4 plays the same role as the rolling element 4 located at the position of the short diameter rb of the inner ring 2. As described above, the retainer 5 is moved to the other side in the direction of the short axis xb (in the left side). Figure 1 The movement of the Figure 1 The position on the minor axis xb of the roller 4 is limited by contact with the roller 4, but the other side in the direction of the minor axis xb (on the right side) Figure 1 The relative movement of the left side (in the figure) is actually affected by the Figure 1The movement of the retainer 5 in the ball bearing 1 is restricted by at least one of the two rolling elements 4 located near the position of the minor axis xb of the inner ring 2 (left side in the figure). Therefore, the movement of the retainer 5 in the ball bearing 1 is restricted by the contact between the one rolling element 4 located at the position of the minor axis rb of the inner ring 2 and the one or two rolling elements 4 located near the position of the minor axis rb of the inner ring 2 and the flange portions 20 of the one pocket 10 located on the minor axis xb of the inner ring 2 and the one or two pockets 10 located near the minor axis xb of the inner ring 2. In this way, the movement of the retainer 5 in the ball bearing 1 is restricted by the contact between the two or three rolling elements 4 that move to the position of the minor axis rb of the inner ring 2 and the two or three flange portions 20 that move to the minor axis xb ...

[0055] On the other hand, when the rolling element 4 located at the position of the short diameter rb of the inner ring 2 moves from the position of the short diameter rb to the position of the long diameter ra as the inner ring 2 rotates, the contact between the moved rolling element 4 and the flange portion 20 of the pocket 10 accommodating the rolling element 4 is eliminated, and the support of the retaining frame 5 by the rolling element 4 is eliminated.

[0056] As described above, the position of each rolling element 4 at the major diameter ra of the inner ring 2 is relatively moved toward the outermost side in the direction of the pocket axis x1 relative to the pocket 10 that accommodates it. Figure 8 As shown, the rolling element 4 located at the position of the major diameter ra of the inner ring 2 moves to a position farthest from the inclined surface 21 of the flange portion 20 of the pocket 10.

[0057] Thus, in the ball bearing 1, the retainer 5 is supported only by the rolling elements 4 located near the minor diameter rb of the inner ring 2. Therefore, when the ball bearing 1 is used to rotate, the generation of a force that deforms the retainer 5 can be suppressed. Figure 7 As shown, at the portion of radius r2 of the inclined surface 21 and the portion of radius r3 of the rolling element 4 on the cross section B (C) at the position p1 of the same radius rp1, the flange 20 contacts the rolling element 4. Therefore, no force that deforms the retainer 5 is generated due to the contact between the flange 20 and the rolling element 4. Therefore, in the ball bearing 1, the retainer 5 does not deform in the use state.

[0058] Due to manufacturing errors, assembly errors, etc., when the position of the flange portion 20 that contacts the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 is the position of the radius of the inclined surface 21 on the cross section at a position radially outward from the position of the radius rp1, a force that deforms the cage 5 toward the axis x side is generated at the position of the minor axis xb in the cage 5. Due to this force, when the cage 5 is deformed, the cage 5 is bent at the position of the major axis xa, and its curvature becomes larger, and the circumferential spacing of the pockets 10 on the major axis xa becomes narrower. In particular, the circumferential width at the position of the inclined surface 21 of the flange portion 20 located on the radial inner side becomes narrower. On the other hand, as described above, the rolling element 4 located at the position of the major diameter ra of the inner ring 2 moves relatively to the outermost side in the direction of the pocket axis x1 relative to the pocket 10 that accommodates it, and moves to the position farthest from the inclined surface 21 of the flange portion 20 of the pocket 10. Therefore, even if the retainer 5 is deformed due to the contact between the rolling element 4 on the minor axis xb and the flange portion 20 as described above, the pocket 10 on the major axis xa can be prevented from pressing the rolling element 5, thereby preventing the retainer 5 from further deforming and damaging it.

[0059] Furthermore, when the ball bearing 1 is in use, the retainer 5 does not contact the inner ring 2 and the outer ring 3, which can prevent an increase in the torque resistance of the ball bearing 1. In addition, at this point, deformation of the retainer 5 in use is avoided or suppressed, and damage to the retainer 5 is avoided or suppressed.

[0060] As described above, the flange 20 of the pocket 10 of the ball bearing 1 can restrict the movement of the cage 5 in the ball bearing 1, and can prevent or reduce the vibration of the cage 5 in the ball bearing 1. In addition, the pocket 10 of the ball bearing 1 can suppress the deformation of the cage 5.

[0061] As described above, when the rolling element 4 is located at the position of the minor diameter rb of the inner ring 2 on one side of the track of the rolling element 4, the two rolling elements 4 located near the position of the minor diameter rb of the inner ring 2 on the other side of the track of the rolling element 4 function substantially in the same manner as the rolling element 4 located at the position of the minor diameter rb of the inner ring 2, but it may be configured that at least one of the two rolling elements 4 located near the position of the minor diameter rb of the inner ring 2 on the other side of the track of the rolling element 4 functions in the same manner as the rolling element 4 located at the position of the minor diameter rb of the inner ring 2. Specifically, at least one of the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 on one side of the track of the rolling element 4 and the two rolling elements 4 located near the position of the minor diameter rb of the inner ring 2 on the other side of the track of the rolling element 4 may contact the flange portion 20 of the pocket 10.

[0062] As described above, according to the ball bearing 1 of the first embodiment of the present invention, it is possible to prevent the vibration of the cage 5 while preventing the deformation of the cage 5 in the wave gear device 100 .

[0063] Next, a modification of the flange portion 20 of the ball bearing 1 according to the first embodiment of the present invention described above will be described. Fig. 9 1 is a diagram showing a modified example of the flange portion 20 of the ball bearing 1, and is an enlarged diagram showing the vicinity of the rolling element 4 located at the position of the short diameter rb of the inner ring 2 of the ball bearing 1. Fig. 9 As shown, the flange portion 20 of the ball bearing 1 may also have a step surface 22 instead of the above-mentioned inclined surface 21. The step surface 22 includes: an annular surface 22a, which is an annular surface around the pocket axis x1 extending from the inner end of the pocket surface 11 in the pocket axis x1 direction toward the inner side of the pocket radial direction; and a cylindrical surface 22b, which extends from the inner end of the annular surface 22a in the pocket radial direction toward the inner side of the pocket axis x1 direction to the inner peripheral surface 5a and extends along the pocket axis x1.

[0064] The annular surface 22a is a surface extending along a plane orthogonal to the pocket axis x1. Fig. 9 As shown, it is a surface that is parallel or approximately parallel to a plane that is orthogonal to the pocket axis x1, and is a toroidal surface or a portion of an approximately toroidal surface with the pocket axis x1 as the center axis or the approximately center axis. In addition, the cylindrical surface 22b is a portion of the cylindrical surface extending along the pocket axis x1, for example, a portion of a conical surface, a cylindrical surface, or an approximately cylindrical surface with the pocket axis x1 as the center axis or the approximately center axis. The cylindrical surface 22b can also be, for example, a portion of a conical surface, a cylindrical surface, or an approximately cylindrical surface extending along a line that passes through the axis x or a point near the pocket axis x1. The annular surface 22a and the cylindrical surface 22b extend continuously between the connecting portion 10a and the connecting portion 10b (refer to Figure 4 ).

[0065] The connection portion 22c, which is the portion where the annular surface 22a and the cylindrical surface 22b are connected, is located on the cross section B at the position p1 of the radius rp1 described above, and extends on a ring centered on the pocket axis x1. The radius of the pocket radial direction of the connection portion 22c is the radius r2. Therefore, the step surface 22 of the flange portion 20 contacts the rolling element 4 at least at the position of the short diameter rb of the inner ring 2 in the connection portion 22c, similarly to the inclined surface 21 of the flange portion 20 described above, and the retainer 5 is supported. Therefore, the step surface 22 of the flange portion 20 of this modified example also functions in the same manner as the inclined surface 21 of the flange portion 20 described above.

[0066] Next, other modified examples of the flange portion 20 of the ball bearing 1 according to the first embodiment of the present invention described above will be described. Fig.10 FIG. 2 is a diagram showing another modified example of the flange portion 20 of the ball bearing 1, showing the pocket 10 when viewed from the outer peripheral surface 5b side toward the inner peripheral surface 5a side in the pocket axis x1 direction. Fig.10As shown, the flange portion 20 may also protrude discontinuously along the pocket surface 11 around the pocket axis x1. Fig.10 As shown, the flange portion 20 may also be a member formed by arranging a plurality of flange pieces 20a at intervals around the pocket axis x1. The shape of the cross section of each flange piece 20a including the pocket axis x1 is similar to the shape of the cross section of the flange portion 20 including the pocket axis x1 (see Figure 5 , Fig. 9 ) is the same. In addition, the inclined surface 21 or the stepped surface 22 of each flange portion piece 20a is the same as the flange portion 20 (refer to Figure 4 ) overlaps the inclined surface 21 or the stepped surface 22 at the corresponding position. It should be noted that the number of flange pieces 20a is not limited to the number shown in the figure.

[0067] Next, a ball bearing 6 according to a second embodiment of the present invention will be described. The ball bearing 6 according to the second embodiment of the present invention has a retainer 7 that is different from the retainer 5 of the ball bearing 1 according to the first embodiment of the present invention described above. The retainer 7 of the ball bearing 6 is different from the retainer 5 described above in that it has a pocket 13 that is different from the pocket 10 of the ball bearing 1. Hereinafter, for the ball bearing 6, for the same structure as the ball bearing 1 described above or for the structure having the same function, the same reference numerals as those of the ball bearing 1 are given and the description thereof is omitted, and the structure different from the ball bearing 1 is described.

[0068] Fig.11 FIG. 2 is a partial cross-sectional view of a ball bearing 6 according to a second embodiment of the present invention. Fig.11 In the figure, the ball bearing 6 is shown with the inner ring 2, the outer ring 3 and the retainer 7 cut away when viewed from the front. Fig.12 is an enlarged view showing the pocket 13 of the cage 7. Fig.13 It is along Fig.12 A cross-sectional view of the pocket hole at the cross section of the line D-D extending in the radial direction. It should be noted that Fig.11 In the middle, the ball bearing 6 and Figure 1 Similarly, it is shown in the form of being mounted on the elliptical cam 102 of the harmonic gear device 100. Fig.12 The pocket 13 is shown when the pocket 13 is viewed from the inner peripheral surface 5 a side toward the outer peripheral surface 5 b side in the pocket axis x1 direction.

[0069] like Figure 11 to Figure 13 As shown in FIG. 1 , each pocket 13 of the cage 7 of the ball bearing 6 has a flange portion 23 for supporting the cage 7, similar to the flange portion 20 of the pocket 10 described above. Unlike the flange portion 20 described above, the flange portion 23 contacts the rolling element 4 located at least at the position of the major diameter ra of the inner ring 2 from the outside in the radial direction. Fig.11As shown, the rolling element 4 located at the position of the major axis ra of the inner ring 2 refers to the rolling element 4 that contacts the position of the major axis ra of the outer peripheral surface 2a of the inner ring 2 in the ball bearing 6, and is the rolling element 4 whose center is located on the major axis xa of the inner ring 2.

[0070] like Fig.11 As shown, in the retainer 7 of the ball bearing 6, a plurality of pockets 13 are formed between the claws 5c adjacent to each other in the circumferential direction, similarly to the plurality of pockets 10 in the retainer 5 described above. Each pocket 13 extends along the pocket axis x1, and penetrates the retainer 7 between the inner peripheral surface 5a and the outer peripheral surface 5b of the retainer 7. In addition, the pocket axis x1 of each pocket 13 extends, for example, parallel or substantially parallel to the radial direction, and the plurality of pockets 13 are arranged, for example, at equal angular intervals or substantially equal angular intervals around the axis x.

[0071] like Figure 11 to Figure 13 As shown, each pocket 13 has a pocket surface 14 which is the same as the pocket surface 11 of the above-mentioned pocket 10. The radius r1 of the pocket surface 14 (see Fig.12 ) is larger than the radius of the rolling element 4. The pocket surface 14 is, for example, a conical surface, a cylindrical surface, or a portion of a substantially cylindrical surface with the pocket axis x1 as the center axis or the approximate center axis. The pocket surface 14 may also be a conical surface, a cylindrical surface, or a portion of a substantially cylindrical surface extending along a line passing through the axis x or a point near the pocket axis x1. The pocket surface 14 can accommodate the rolling element 4 with a gap in the entire range in the direction of the pocket axis x1, for example Fig.13 As shown, the radius r1 of the pocket surface 14 is the same in the entire range in the direction of the pocket axis x1 (r1a=r1c), or increases in diameter from the flange portion 23 side toward the inner peripheral surface 5a side in the direction of the pocket axis x1 (r1c>r1a). It should be noted that the radius r1a is the radius r1 of the pocket surface 14 on the flange portion 23 side, and the radius r1c is the radius r1 of the pocket surface 14 on the inner peripheral surface 5a side. Fig.13 As shown, the flange portion 23 of each pocket 13 is a portion extending around the pocket axis x1 that protrudes inwardly in the pocket radial direction more than the pocket surface 14. The flange portion 23 is, for example, in a form that prevents the pocket 13 from moving relative to the rolling element 4 when it contacts the rolling element 4 located at the position of the major axis ra of the inner ring 2 from the outside in the radial direction, so that the retainer 7 is supported by the rolling element 4.

[0072] For example Fig.13As shown, the radius (radius r4) of the flange portion 23 on the cross section (cross section E) perpendicular to the pocket axis x1 at a predetermined radial position (position p2) in the radial direction (in the direction of the pocket axis x1) of the ball bearing 6 within the range (range s2) on the pocket axis x1 of the flange portion 23 and the radius (radius r5) of the rolling element 4 on the cross section (cross section F) perpendicular to the major axis xa at a predetermined radial position p2 on the major axis xa of the rolling element 4 located at the position of the major axis ra of the inner ring 2 (refer to Fig.14 ) are the same or approximately the same value. It should be noted that, Fig.14 This is an enlarged view showing the vicinity of the rolling element 4 located at the position of the major diameter ra of the inner ring 2 of the ball bearing 6. Fig.14 The cage 7 is omitted. In addition, the cross section E and the cross section F are the same cross section in the ball bearing 6.

[0073] Specifically, for example Fig.13 As shown, the flange portion 23 is disposed adjacent to the pocket surface 14 on the outside in the radial direction of the ball bearing 6 relative to the pocket surface 14, and is disposed only at the end portion of the pocket 13 on the outside in the pocket axis x1 direction. Fig.13 As shown, the flange portion 23 has an inclined surface 24, which is a surface extending around the pocket axis x1 and expanding in diameter toward the side in the direction of contact with the rolling element 4 (radial inner side of the ball bearing 6) in the pocket axis x1 direction. In addition, the flange portion 23 protrudes continuously along the pocket surface 14 around the pocket axis x1. Specifically, for example Fig.12 , Fig.13 As shown, the flange portion 23 extends along a circular ring or a substantially circular ring extending around the pocket axis x1 between the respective open faces 5e of the pair of claw portions 5c, extending longer than a semicircle. Fig.13 As shown, the shapes of the cross sections perpendicular to the extending direction of the flange portion 23 are the same or substantially the same.

[0074] As mentioned above, Fig.13 As shown, the projection range of the inclined surface 24 onto the pocket axis x1 in the pocket radial direction is range s2, and the radius at the cross section E at the radial position p2 within range s2 is radius r4. Fig.14 As shown, the radius r5 at the cross section F at the radial position p2 on the major axis xa of the rolling element 4 located at the position of the major axis ra of the inner ring 2 is the same or substantially the same value as the radius r4 at the inclined surface 24 of the flange portion 23. Therefore, as described later Fig.15 As shown, the radius r4 portion of the inclined surface 24 of the flange portion 23 contacts the radius r5 portion of the circumferential surface of the rolling element 4 located at the position of the major diameter ra of the inner ring 2 from the outside in the radial direction of the ball bearing 6. The position p2 is located, for example, outside the center of the width of the pocket 13 in the direction of the pocket axis x1. It should be noted that, as Fig.13 , Fig.14 As shown, the radius of the ball bearing 6 at the radial position p2 is rp2.

[0075] The inclined surface 24 of the flange portion 23 may be, for example, Fig.13 As shown, it is a conical surface that draws a straight line or a substantially straight line on a cross section including the pocket axis x1. The inclined surface 24 is not limited to such a conical surface, and as described above, it can also be a surface of other shapes as long as it is a surface that contacts the rolling element 4 located at least at the position of the major diameter ra of the inner ring 2 from the outside in the radial direction of the ball bearing 6 at the position of the radius r4 of the radial position p2. For example, the inclined surface 24 can be a surface that draws a circular arc or an arc convex to the side of the pocket axis x1 on a cross section including the pocket axis x1, or a surface that draws a circular arc or an arc concave to the opposite side of the pocket axis x1, or a surface that draws other curves. In addition, the inclined surface 24 can also be a surface that draws a line composed of a curve and a straight line on a cross section including the pocket axis x1.

[0076] In addition, if Fig.13 As shown, each pocket 13 may also have a relief portion 15 on the outside in the pocket axis x1 direction of the flange portion 23. The relief portion 15 extends between the end (outer end 24a) of the inclined surface 24 of the flange portion 23 on the outside in the pocket axis x1 direction and the outer peripheral surface 5b of the retainer 7, and is, for example, a conical surface, a cylindrical surface, or a part of a substantially cylindrical surface with the pocket axis x1 as the center axis or the approximate center axis. The form of the relief portion 15 is not limited to this form. Like the pocket surface 14, the relief portion 15 may also be, for example, a conical surface, a circumferential surface, or a part of a substantially cylindrical surface extending along a line passing through the axis x or a point near the pocket axis x1.

[0077] Next, the operation of the ball bearing 6 having the above-described structure will be described. Fig.15 FIG. 1 is an enlarged view showing the vicinity of the rolling element 4 located at the position of the major diameter ra of the inner ring 2 in the ball bearing 6. Fig.16 This is an enlarged view showing the vicinity of the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 in the ball bearing 6 .

[0078] Similar to the rotation of the ball bearing 1 described above, in the harmonic gear device 100, when the inner ring 2 rotates around the axis x together with the rotation of the cam 102, and the retainer 7 rotates around the axis x together with the plurality of rolling elements 4, each rolling element 4 on the outer peripheral surface 2a of the inner ring 2 moves relative to the pocket 13 in the pocket 13 in which the rolling element 4 is accommodated, in the pocket 13 in the direction of the pocket axis x1. Each rolling element 4 moves relative to the innermost side relative to the pocket 13 in the direction of the pocket axis x1 at the position of the short diameter rb of the inner ring 2, and moves relative to the innermost side relative to the pocket 13 in the direction of the pocket axis x1 at the position of the long diameter ra of the inner ring 2.

[0079] like Fig.15 As shown, the rolling element 4 located at the position of the major diameter ra of the inner ring 2, which has moved relatively to the outermost side in the direction of the pocket axis x1 relative to the pocket 13, contacts the inclined surface 24 of the flange portion 23 of the pocket 13. Specifically, the portion of the radius r4 of the inclined surface 24 on the cross section E (F) at the position p2 radially away from the axis x by the radius rp2 contacts the portion of the radius r5 of the rolling element 4 on the cross section F (E) at the position p2 radially away from the axis x by the radius rp2. Due to the contact between the flange portion 23 and the rolling element 4, the retainer 7 is supported by the rolling element 4 and cannot move relatively to the inner side of the pocket radial direction and the radial direction of the ball bearing 6 relative to the rolling element 4.

[0080] like Fig.15 As shown, when the rolling element 4 is located on the track of the rolling element 4, the position of the long diameter ra of the inner ring 2 on one side (at Fig.11 When the rolling element 4 is not located at the position of the major diameter ra of the inner ring 2 on the other side of the track of the rolling element 4 (in Fig.11 However, the two rolling elements 4 are located at the position of the major diameter ra of the inner ring 2 on the other side of the track of the rolling element 4 (at Fig.11 The two rolling elements 4 or one of the two rolling elements 4 plays the same role as the rolling element 4 located at the position of the long axis ra of the inner ring 2. As described above, the retainer 7 is on one side in the direction of the long axis xa (in the Fig.11 The relative movement of the Fig.11 The position on the long axis xa (in the upper side) is limited by the contact of the rolling element 4, but to one side in the long axis xa direction (in Fig.11 The relative movement of the upper side (in the middle) is actually affected by the other side (in Fig.11 The movement of the retainer 7 in the ball bearing 6 is restricted by at least one of the two rolling elements 4 located near the position of the long axis xa of the inner ring 2 (the lower side in the figure). Therefore, the movement of the retainer 7 in the ball bearing 6 is restricted by the contact between the one rolling element 4 located at the position of the long axis ra of the inner ring 2 and the one or two rolling elements 4 located near the position of the long axis ra of the inner ring 2 and the flanges 23 of the one pocket 13 located on the long axis xa of the inner ring 2 and the one or two pockets 13 located near the long axis xa of the inner ring 2. In this way, the movement of the retainer 7 in the ball bearing 6 is restricted by the contact between the two or three rolling elements 4 that move to the position of the long axis ra of the inner ring 2 and the two or three flanges 23 that move to the long axis xa ...

[0081] On the other hand, when the rolling element 4 located at the position of the long diameter ra of the inner ring 2 moves from the position of the long diameter ra to the position of the short diameter rb as the inner ring 2 rotates, the contact between the moved rolling element 4 and the flange portion 23 of the pocket 13 accommodating the rolling element 4 is eliminated, and the support of the rolling element 4 to the retaining frame 7 is eliminated.

[0082] As described above, the position of each rolling element 4 at the short diameter rb of the inner ring 2 is relatively moved to the innermost side in the pocket 13 that accommodates it in the pocket axis x1 direction. Fig.16 As shown, the rolling element 4 located at the position of the short diameter rb of the inner ring 2 moves to a position farthest from the inclined surface 24 of the flange portion 23 of the pocket 13 .

[0083] Thus, in the ball bearing 6, the retainer 7 is supported only by the rolling element 4 located near the major diameter ra of the inner ring 2. Therefore, when the ball bearing 6 is in use, the generation of a force that deforms the retainer 7 can be suppressed. Fig.14 As shown, at the portion of the radius r4 of the inclined surface 24 and the portion of the radius r5 of the rolling element 4 on the cross section E (F) at the position p2 of the same radius rp2, the flange portion 23 contacts the rolling element 4. Therefore, no force that deforms the retainer 7 is generated due to the contact between the flange portion 23 and the rolling element 4. Therefore, in the ball bearing 6, the retainer 7 does not deform in the use state.

[0084] Due to manufacturing errors, assembly errors, etc., when the position of the flange portion 23 that contacts the rolling element 4 located at the position of the major diameter ra of the inner ring 2 is the position of the radius of the inclined surface 24 on the cross section at a position radially inner than the position of the radius rp2, a force that deforms the retainer 7 toward the axis x side is generated at the position of the major axis xa in the retainer 7. Due to this force, when the retainer 7 is deformed, the retainer 7 is bent at the position of the minor axis xb, and its curvature becomes larger, and the circumferential spacing of the pockets 13 on the minor axis xb becomes narrower. In particular, the circumferential width of the pocket surface 14 located on the radial inner side becomes narrower. On the other hand, as described above, the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 moves relatively to the innermost side in the direction of the pocket axis x1 relative to the pocket 13 that accommodates it. Therefore, even if the retainer 7 is deformed due to the contact between the rolling element 4 on the major axis xa and the flange portion 23 as described above, the radius of the cylindrical portion 14 of the pocket 13 can be adjusted to avoid or suppress the pocket 13 on the minor axis xb from pressing the rolling element 7. By this adjustment, further deformation of the retainer 7 can be avoided or suppressed, and damage to the retainer 7 can be avoided or suppressed.

[0085] Furthermore, when the ball bearing 6 is in use, the retainer 7 does not contact the inner ring 2 and the outer ring 3, which can prevent an increase in the torque resistance of the ball bearing 6. In addition, at this point, deformation of the retainer 7 in use is avoided or suppressed, and damage to the retainer 7 is avoided or suppressed.

[0086] As described above, flange 23 of pocket 13 of ball bearing 6 can restrict movement of retainer 7 in ball bearing 6, thereby preventing or reducing vibration of retainer 7 in ball bearing 6. In addition, pocket 13 of ball bearing 6 can suppress deformation of retainer 7.

[0087] As described above, when the rolling element 4 is located at the position of the major diameter ra of the inner ring 2 on one side of the track of the rolling element 4, the two rolling elements 4 located near the position of the major diameter ra of the inner ring 2 on the other side of the track of the rolling element 4 function substantially in the same manner as the rolling element 4 located at the position of the major diameter ra of the inner ring 2, but it may be configured that at least one of the two rolling elements 4 located near the position of the major diameter ra of the inner ring 2 on the other side of the track of the rolling element 4 functions in the same manner as the rolling element 4 located at the position of the major diameter ra of the inner ring 2. Specifically, at least one of the rolling element 4 located at the position of the major diameter ra of the inner ring 2 on one side of the track of the rolling element 4 and the two rolling elements 4 located near the position of the major diameter ra of the inner ring 2 on the other side of the track of the rolling element 4 may contact the flange portion 23 of the pocket 13.

[0088] As described above, according to the ball bearing 6 of the second embodiment of the present invention, it is possible to prevent the vibration of the cage 7 while preventing the deformation of the cage 7 in the wave gear device 100 .

[0089] Next, a modification of the flange portion 23 of the ball bearing 6 according to the second embodiment of the present invention described above will be described. Fig.17 2 is a diagram showing a modified example of the flange portion 23 of the ball bearing 6, and is an enlarged diagram showing the vicinity of the rolling element 4 located at the position of the major diameter ra of the inner ring 2 of the ball bearing 6. Fig.17 As shown, the flange portion 23 of the ball bearing 6 may have a step surface 25 instead of the above-mentioned inclined surface 24. The step surface 25 includes: an annular surface 25a, which is an annular surface around the pocket axis x1 extending from the end of the pocket surface 14 on the outside in the pocket axis x1 direction toward the inside in the pocket radial direction; and a cylindrical surface 25b, which extends from the end of the annular surface 25a on the inside in the pocket radial direction to the outside in the pocket axis x1 direction to the outer peripheral surface 5b and extends along the pocket axis x1.

[0090] The annular surface 25a is a surface extending along a plane orthogonal to the pocket axis x1. Fig.17As shown, it is a surface that is parallel or approximately parallel to a plane that is orthogonal to the pocket axis x1, and is a toroidal surface or a portion of an approximately toroidal surface with the pocket axis x1 as the center axis or the approximately center axis. In addition, the cylindrical surface 25b is a portion of a cylindrical surface extending along the pocket axis x1, for example, a portion of a conical surface, a cylindrical surface, or an approximately cylindrical surface with the pocket axis x1 as the center axis or the approximately center axis. The cylindrical surface 25b may also be, for example, a portion of a conical surface, a cylindrical surface, or an approximately cylindrical surface extending along a line that passes through the axis x or a point near the pocket axis x1. The annular surface 25a and the cylindrical surface 25b extend continuously between the connecting portion 10a and the connecting portion 10b (refer to Fig.12 ).

[0091] The connection portion 25c, which is the portion where the annular surface 25a and the cylindrical surface 25b are connected, is located on the cross section E at the position p2 of the radius rp2 described above, and extends on a ring centered on the pocket axis x1. The radius of the pocket radial direction of the connection portion 25c is the radius r4. Therefore, the step surface 25 of the flange portion 23, in the connection portion 25c, contacts the rolling element 4 at least at the position of the major axis ra of the inner ring 2, similarly to the inclined surface 24 of the flange portion 23 described above, and the retainer 7 is supported. Therefore, the step surface 25 of the flange portion 23 of this modified example also functions in the same manner as the inclined surface 24 of the flange portion 23 described above.

[0092] Next, another modified example of the flange portion 23 of the ball bearing 6 according to the second embodiment of the present invention described above will be described. Fig.18 FIG. 2 is a diagram showing another modified example of the flange portion 23 of the ball bearing 6, showing the pocket 13 when viewed from the inner peripheral surface 5a side toward the outer peripheral surface 5b side in the pocket axis x1 direction. Fig.18 As shown, the flange portion 23 may also protrude discontinuously along the pocket surface 14 around the pocket axis x1. Fig.18 As shown, the flange portion 23 may also be a member formed by arranging a plurality of flange pieces 23a at intervals around the pocket axis x1. The shape of the cross section of each flange piece 23a including the pocket axis x1 is similar to the shape of the cross section of the flange portion 23 including the pocket axis x1 (see Fig.13 , Fig.17 ) is the same. In addition, the inclined surface 24 or the stepped surface 25 of each flange portion piece 23a is the same as the flange portion 23 (refer to Fig.12 ) overlaps the inclined surface 24 or the stepped surface 25 at the corresponding position. It should be noted that the number of flange pieces 23a is not limited to the number shown in the figure.

[0093] Next, a ball bearing 1A according to a third embodiment of the present invention will be described. The ball bearing 1A according to the third embodiment of the present invention has a retainer 5A that is different from the retainer 5 of the ball bearing 1 according to the first embodiment of the present invention described above. The retainer 5A of the ball bearing 1A is different from the retainer 5 described above in that it has a pocket 16 that is different from the pocket 10 of the ball bearing 1. Hereinafter, for the ball bearing 1A, for the same structure as the above-mentioned ball bearing 1 or for the structure having the same function, the same reference numeral as that of the ball bearing 1 is marked and the description thereof is omitted, and the structure different from the ball bearing 1 will be described.

[0094] The pocket 16 of the retainer 5A has a flange portion 26 that contacts the rolling element 4 located at least at the position of the minor diameter rb of the inner ring 2 from the radial inner side, as does the flange portion 20 of the pocket 10 described above. When the flange portion 26 contacts the rolling element 4 located at least at the position of the minor diameter rb of the inner ring 2, the rolling element 4 cannot move relative to the pocket 16, and the retainer 5A is supported by the rolling element 4. More specifically, when the flange portion 26 contacts the rolling element 4 located at least at the position of the minor diameter rb of the inner ring 2, the pocket 16 cannot move relative to the rolling element 4 together with the pocket surface 11 of the pocket 16, and the retainer 5A is supported by the rolling element 4.

[0095] Fig.19 1 is an enlarged view showing the vicinity of the rolling element 4 and the pocket 16 located at the position of the short diameter rb of the ball bearing 1A in the wave gear device 100. Fig. 20 is along relative to Fig.19 A cross-sectional view of a cross section of a line G-G extending in the radial direction along the pocket axis x1. It should be noted that: Fig.19 The rolling element 4 and the pocket 16 are shown when viewed from the outer peripheral surface 5b side toward the inner peripheral surface 5a side in the pocket axis x1 direction.

[0096] like Fig.19 , Fig. 20 As shown, the flange portion 26, like the flange portion 20 in the first embodiment of the present invention, protrudes from the pocket surface 11 to the inner side of the pocket radial direction, is adjacent to the inner side of the cylinder portion 11 in the pocket axis x1 direction, and is only provided at the inner end of the pocket 16 in the pocket axis x1 direction. In addition, the flange portion 26, like the flange portion 20 described above, extends continuously along the pocket surface 11 around the pocket axis x1. However, as Fig.19As shown, the flange portion 26 does not extend to the connection portion 10a and the connection portion 10b. In addition, the flange portion 26 has an inclined surface 27 similarly to the flange portion 20. The inclined surface 27 has a shape that contacts the rolling element 4 located at least at the position of the short diameter rb of the inner ring 2 from the radial inside, similarly to the inclined surface 21, but unlike the inclined surface 21, has a shape that contacts the rolling element 4 with the pocket surface 11 when contacting the rolling element 4. It should be noted that the inclined surface 27 may contact the rolling element 4 located at least at the position of the short diameter rb of the inner ring 2 over the entire surface, or may contact the rolling element 4 located at least at the position of the short diameter rb of the inner ring 2 over a portion. In addition, the pocket surface 11 contacts the rolling element 4 located at least at the position of the short diameter rb of the inner ring 2 over a portion.

[0097] In the ball bearing 1A in the wave gear device 100, the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 on one side on the track of the rolling element 4 contacts the inclined surface 27 of the flange 26 and the pocket surface 11 in the pocket 16 that accommodates the rolling element 4. In addition, at least one of the two rolling elements 4 near the position of the minor diameter rb of the inner ring 2 on the other side on the track of the rolling element 4 contacts the inclined surface 27 of the flange 26 and the pocket surface 11 in a substantially similar manner to the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 on one side. Therefore, as in the case of the ball bearing 1 described above, the rolling element 4 located near the position of the minor diameter rb is substantially unable to move relative to the pocket 16, and the cage 5A is supported by the rolling element 4 and is unable to move relative to the rolling element 4 in the pocket radial direction and in the radial direction outward of the ball bearing 1A. Thus, the movement of the retainer 5A in the ball bearing 1A is restricted by the contact between at least one of the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 and the flange 26 and the pocket surface 11 of one pocket 16 located on the minor axis xb of the inner ring 2 and one or two pockets 16 located near the minor axis xb of the inner ring 2. In this way, the movement of the retainer 5A in the ball bearing 1A is restricted by the contact between the flange 26 and the pocket surface 11 of the two or three rolling elements 4 that move successively to the position of the minor diameter rb of the inner ring 2 and the minor axis rb of the inner ring 2 and the flange 26 and the pocket surface 11 of the two or three pockets 16 that move successively to the position of the minor diameter rb of the inner ring 2 and the minor axis xb of the inner ring 2.

[0098] On the other hand, when the rolling element 4 located at the position of the short diameter rb of the inner ring 2 moves from the position of the short diameter rb to the position of the long diameter ra as the inner ring 2 rotates, the contact between the moved rolling element 4 and the flange portion 26 of the pocket 16 accommodating the rolling element and the pocket surface 11 is eliminated, and the support of the rolling element 4 to the retaining frame 5A is eliminated.

[0099] As described above, the flange 26 and the pocket surface 11 of the ball bearing 1A function in the same manner as the flange 20 of the ball bearing 1, and the ball bearing 1A achieves the same function and effect as the ball bearing 1. Specifically, the flange 26 and the pocket surface 11 of the pocket 16 can restrict the movement of the retainer 5A in the ball bearing 1A, and can prevent or reduce the vibration of the retainer 5A in the ball bearing 1A. In addition, the pocket 16 of the ball bearing 1A can suppress the deformation of the retainer 5A.

[0100] As described above, when the rolling element 4 is located at the position of the minor diameter rb of the inner ring 2 on one side of the track of the rolling element 4, the two rolling elements 4 located near the position of the minor diameter rb of the inner ring 2 on the other side of the track of the rolling element 4 function substantially in the same manner as the rolling element 4 located at the position of the minor diameter rb of the inner ring 2, but it may be configured that at least one of the two rolling elements 4 located near the position of the minor diameter rb of the inner ring 2 on the other side of the track of the rolling element 4 functions in the same manner as the rolling element 4 located at the position of the minor diameter rb of the inner ring 2. Specifically, at least one of the rolling element 4 located at the position of the minor diameter rb of the inner ring 2 on one side of the track of the rolling element 4 and the two rolling elements 4 located near the position of the minor diameter rb of the inner ring 2 on the other side of the track of the rolling element 4 may contact the flange portion 26 of the pocket 16 and the pocket surface 11.

[0101] As described above, according to the ball bearing 1A of the third embodiment of the present invention, it is possible to prevent the vibration of the retainer 5A while preventing the deformation of the retainer 5A in the wave gear device 100 .

[0102] It should be noted that the flange portion 26 can be deformed in the same manner as the flange portion 20 of the ball bearing 1 according to the first embodiment of the present invention. Fig. 9 As shown in FIG. 2 , the flange portion 26 may have a stepped surface similar to the stepped surface 22 instead of the inclined surface 27. Fig.10 As shown, the collar portion 26 may also protrude discontinuously along the pocket surface 11 around the pocket axis x1 .

[0103] Next, a ball bearing 6A according to a fourth embodiment of the present invention will be described. The ball bearing 6A according to the fourth embodiment of the present invention has a retainer 7A that is different from the retainer 7 of the ball bearing 6 according to the second embodiment of the present invention described above. The retainer 7A of the ball bearing 6A is different from the retainer 7 described above in that it has a pocket 17 that is different from the pocket 13 of the ball bearing 6. Hereinafter, for the ball bearing 6A, for the same structure as the above-mentioned ball bearing 6 or for the structure having the same function, the same reference numeral as that of the ball bearing 6 is marked and the description thereof is omitted, and the structure different from the ball bearing 6 is described.

[0104] The pocket 17 of the retainer 7A has a flange portion 28 that contacts the rolling element 4 located at least at the position of the major diameter ra of the inner ring 2 from the radial outside, as does the flange portion 23 of the pocket 13 described above. When the flange portion 28 contacts the rolling element 4 located at least at the position of the major diameter ra of the inner ring 2, the rolling element 4 cannot move relative to the pocket 17, and the retainer 7A is supported by the rolling element 4. More specifically, when the flange portion 28 contacts the rolling element 4 located at least at the position of the major diameter ra of the inner ring 2, the pocket 17 cannot move relative to the rolling element 4 together with the pocket surface 14 of the pocket 17, and the retainer 7A is supported by the rolling element 4.

[0105] Fig.21 1 is an enlarged view showing the rolling element 4 and the vicinity of the pocket 17 located at the position of the major diameter ra of the ball bearing 6A in the wave gear device 100. Fig. 22 is along relative to Fig.21 A cross-sectional view of a cross section of a line H-H extending in the radial direction along the pocket axis x1. It should be noted that: Fig.21 The rolling element 4 and the pocket 17 are shown when viewed from the inner peripheral surface 5 a side toward the outer peripheral surface 5 b side in the pocket axis x1 direction.

[0106] like Fig.21 , Fig. 22 As shown, the flange portion 28, like the flange portion 23 in the second embodiment of the present invention, protrudes from the pocket surface 14 to the inner side of the pocket radial direction, is adjacent to the outer side of the cylinder portion 14 in the pocket axis x1 direction, and is only provided at the outer end of the pocket 17 in the pocket axis x1 direction. In addition, the flange portion 28, like the flange portion 23 described above, extends continuously along the pocket surface 14 around the pocket axis x1. However, as Fig.21 As shown, the flange portion 28 does not extend to the connection portion 10a and the connection portion 10b. In addition, the flange portion 27 has an inclined surface 29 in the same manner as the flange portion 23. The inclined surface 29 has a shape that contacts the rolling element 4 located at least at the position of the long diameter ra of the inner ring 2 from the radial outside, similarly to the inclined surface 24, but unlike the inclined surface 24, has a shape that contacts the rolling element 4 with the pocket surface 14 when contacting the rolling element 4. It should be noted that the inclined surface 29 may contact the rolling element 4 located at least at the position of the long diameter ra of the inner ring 2 over the entire surface, or may contact the rolling element 4 located at least at the position of the long diameter ra of the inner ring 2 over a portion. In addition, the pocket surface 14 contacts the rolling element 4 located at least at the position of the long diameter ra of the inner ring 2 over a portion.

[0107] In the ball bearing 6A in the harmonic gear device 100, the rolling element 4 located at the position of the major diameter ra of the inner ring 2 on one side on the track of the rolling element 4 contacts the inclined surface 29 of the flange 28 and the pocket surface 14 in the pocket 17 that accommodates the rolling element 4. In addition, at least one of the two rolling elements 4 near the position of the major diameter ra of the inner ring 2 on the other side on the track of the rolling element 4 contacts the inclined surface 29 of the flange 28 and the pocket surface 14 in substantially the same manner as the rolling element 4 located at the position of the major diameter ra of the inner ring 2 on one side. Therefore, similarly to the case of the ball bearing 6 described above, the rolling element 4 located near the position of the major diameter ra is substantially unable to move relative to the pocket 17, and the cage 7A is supported by the rolling element 4 and is unable to move relative to the rolling element 4 in the pocket radial direction and inward in the radial direction of the ball bearing 6A. Thus, the movement of the retainer 7A in the ball bearing 6A is restricted by the contact between at least one of the rolling element 4 located at the position of the major axis ra of the inner ring 2 and the flange 28 and the pocket surface 14 of one pocket 17 located on the major axis xa of the inner ring 2 and one or two pockets 17 located near the major axis xa of the inner ring 2. In this way, the movement of the retainer 7A in the ball bearing 6A is restricted by the contact between the flange 28 and the pocket surface 14 of the two or three rolling elements 4 that move successively to the position of the major axis ra of the inner ring 2 and the flange 28 of the two or three pockets 17 that move successively to the major axis xa of the inner ring 2 and the pocket surface 14.

[0108] On the other hand, when the rolling element 4 located at the position of the long diameter ra of the inner ring 2 moves from the position of the long diameter ra to the position of the short diameter rb as the inner ring 2 rotates, the contact between the moved rolling element 4 and the flange portion 28 of the pocket 17 accommodating the rolling element 4 and the pocket surface 14 is eliminated, and the support of the rolling element 4 to the retaining frame 7A is eliminated.

[0109] As described above, the flange 28 and the pocket surface 14 of the ball bearing 6A function in the same manner as the flange 26 of the ball bearing 6, and the ball bearing 6A achieves the same function and effect as the ball bearing 6. Specifically, the flange 28 and the pocket surface 14 of the pocket 17 can restrict the movement of the retainer 7A in the ball bearing 6A, and can prevent or reduce the vibration of the retainer 7A in the ball bearing 6A. In addition, the pocket 17 of the ball bearing 6A can suppress the deformation of the retainer 7A.

[0110] As described above, when the rolling element 4 is located at the position of the major diameter ra of the inner ring 2 on one side of the track of the rolling element 4, the two rolling elements 4 located near the position of the major diameter ra of the inner ring 2 on the other side of the track of the rolling element 4 function substantially in the same manner as the rolling element 4 located at the position of the major diameter ra of the inner ring 2, but it may be configured that at least one of the two rolling elements 4 located near the position of the major diameter ra of the inner ring 2 on the other side of the track of the rolling element 4 functions in the same manner as the rolling element 4 located at the position of the major diameter ra of the inner ring 2. Specifically, at least one of the rolling element 4 located at the position of the major diameter ra of the inner ring 2 on one side of the track of the rolling element 4 and the two rolling elements 4 located near the position of the major diameter ra of the inner ring 2 on the other side of the track of the rolling element 4 may contact the flange portion 28 of the pocket 17 and the pocket surface 14.

[0111] As described above, according to the ball bearing 6A of the fourth embodiment of the present invention, it is possible to prevent the vibration of the retainer 7A while preventing the deformation of the retainer 7A in the wave gear device 100 .

[0112] It should be noted that the flange portion 27 can be deformed in the same manner as the flange portion 23 of the ball bearing 6 according to the second embodiment of the present invention. Fig.17 As shown in FIG. 2 , the flange portion 28 may have a stepped surface similar to the stepped surface 25 instead of the inclined surface 29. Fig.18 As shown, the collar portion 28 may also protrude discontinuously along the pocket surface 14 around the pocket axis x1 .

[0113] The above is a description of the embodiments of the present invention, but the present invention is not limited to the ball bearings 1, 1A, 6, 6A of the embodiments of the present invention, and includes all schemes included in the concept of the present invention and the claims. In addition, the various structures can be appropriately and selectively combined to achieve at least part of the above-mentioned subjects and effects. For example, the shape, material, configuration, size, etc. of each structure in the above-mentioned embodiments can also be appropriately changed according to the specific use scheme of the present invention.

[0114] Marking Description

[0115] 1, 1A, 6, 6A: ball bearing; 2: inner ring; 2a: outer peripheral surface; 3: outer ring; 3a: inner peripheral surface; 4: rolling element; 5, 5A, 7, 7A: cage; 5a: inner peripheral surface; 5b: outer peripheral surface; 5c: claw; 5d: top end; 5e: open surface; 5f: open part; 10, 13, 16, 17: pocket; 10a, 10b: connecting part; 11, 14: pocket surface; 12, 15: retreat part; 20, 23, 26, 28: flange; 21, 24, 27, 29: inclined surface; 21a: inner side end; 22, 25: step surface; 22a, 25a: annular surface; 22b, 25b: cylinder surface; 22c, 25c: connecting part; 20a, 23a: flange piece; 24a: outer end; 100: harmonic gear device; 101: wave generator; 102: cam; 103: flexible gear; 103a: tooth; 104: rigid gear; 104a: tooth; A, B, C, E, F: cross section; p1, p2: position; r1, r1a, r1b, r1c, r2, r3, r4, r5, rp1, rp2: radius; ra: major diameter; rb: minor diameter; s1, s2: range; x: axis; x1: pocket axis; xa: major axis; xb: minor axis.

Claims

1. A ball bearing, comprising: a deformable inner ring; a deformable outer ring disposed outside the inner ring; a plurality of spherical rolling elements disposed between the inner ring and the outer ring; and a retaining frame having a plurality of pockets spaced apart in the circumferential direction for accommodating the plurality of rolling elements, wherein: Each of the plurality of pockets has: a pocket surface, which is a surface extending around an axis extending in a radial direction; and a flange portion, which is a portion protruding from the pocket surface toward the axis side. The pocket surface accommodates the rolling element with a gap therebetween. The flange portion contacts the rolling element at least at a position of a short diameter of the inner ring from the radial inner side, or the flange portion contacts the rolling element at least at a position of a long diameter of the inner ring from the radial outer side.

2. The ball bearing according to claim 1, wherein: The flange portion prevents the pocket from moving relative to the rolling element during the contact.

3. The ball bearing according to claim 1, wherein: During the contact, the flange portion, together with the pocket surface, prevents the pocket from moving relative to the rolling element.

4. The ball bearing according to claim 2, wherein: In the ball bearing having the flange portion that contacts the rolling element at least at a position of a short diameter of the inner ring from the radial inside, The radius of the flange portion on a cross section perpendicular to the axis at a specified radial position within the range on the axis of the flange portion is the same value as the radius of the rolling element on a cross section perpendicular to the short axis at a specified radial position on the short axis of the rolling element located at the position of the short diameter of the inner ring.

5. The ball bearing according to claim 2, wherein: In the ball bearing having the flange portion that contacts the rolling element at least at a position of the major diameter of the inner ring from the radially outer side, The radius of the flange portion on a cross section perpendicular to the axis at a specified radial position within the range of the axis of the flange portion is the same value as the radius of the rolling body on a cross section perpendicular to the major axis at a specified radial position on the major axis of the rolling body located at the position of the major diameter of the inner ring.

6. The ball bearing according to any one of claims 1 to 3, wherein: In each of the pockets, the flange portion is disposed adjacent to the pocket surface on the radially inner side.

7. The ball bearing according to any one of claims 1 to 3, wherein: In each of the pockets, the flange portion is disposed adjacent to the pocket surface on the radially outer side.

8. The ball bearing according to any one of claims 1 to 5, wherein: The flange portion has a surface extending around the axis and having a diameter increasing toward a side in a direction in which the flange portion contacts the rolling element in the axial direction.

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