Speed ​​reduction or speed increase device

Abstract

Provided is a deceleration device that can suppress the occurrence of unevenness in output torque. A deceleration device (10) causes a first face gear (1) to be inclined so as to engage a second face gear (2), and causes the first face gear (1) to swing such that an engaging portion moves in a circumferential direction. The deceleration device (10) is also provided with a ball spline part (3) that supports the first face gear (1) in a manner allowing inclination. The ball spline part (3) comprises an outer ring (4), an inner ring (6), a ball (5) that can roll along a ball groove (4a) of the outer ring (4) and a ball groove (6a) of the inner ring (6), and a holder (7) having formed therein a pocket (7a) into which the ball (5) is inserted, and the ball spline part (3) allows displacement in the axial direction of the first face gear (1).

Description

【Technical Field】 【0001】 The present invention relates to a speed reduction or speed increase device. 【Background Art】 【0002】 As this type of speed reduction device, the speed reduction devices described in Patent Document 1 or Patent Document 2 are known. In this speed reduction device, the first face gear is inclined to mesh with the second face gear, and the first face gear is swung so that the meshing portion moves in the circumferential direction (the swing of the first face gear is also called a precession motion). 【0003】 In the speed reduction device described in Patent Document 1, the first face gear is connected to the input shaft. The second face gear is connected to the output shaft. The first face gear is swingably supported by the spline portion and its rotation is restricted by the spline portion. When the input shaft is rotated, the first face gear swings, the second face gear rotates at a speed reduced by the difference in the number of teeth from the first face gear, and the speed-reduced rotation of the second face gear is taken out to the output shaft (see Patent Document 1, FIG. 1). 【0004】 In the speed reduction device described in Patent Document 2, the first face gear is connected to the input shaft. The second face gear is fixed to the housing. The first face gear is swingably supported by the spline portion provided on the output shaft. When the input shaft is rotated, the first face gear swings, the first face gear rotates at a speed reduced by the difference in the number of teeth from the second face gear, and the speed-reduced rotation of the first face gear is taken out to the output shaft through the spline portion (see Patent Document 2, FIG. 8). 【Prior Art Documents】 【Patent Documents】 【0005】 【Patent Document 1】 Japanese Patent Laid-Open No. 57-15140 【Patent Document 2】 Japanese Patent Laid-Open No. 51-126467 【Summary of the Invention】 [Problems that the invention aims to solve] 【0006】 However, the reduction gears described in Patent Documents 1 and 2 have a problem in that, due to machining errors and wear of the first face gear and the second face gear, the first face gear and the second face gear cannot be kept meshed, resulting in uneven output torque. 【0007】 The first invention was made in view of the above-mentioned problems, and its first objective is to provide a speed reduction or speed increase device that can suppress the occurrence of unevenness in output torque. 【0008】 Incidentally, this type of reduction gear is desirable to be incorporated into small spaces, such as the joint structure of a robot. 【0009】 The second invention was made in view of the above-mentioned problems, and its second objective is to provide a reduction or speed increase device that can be miniaturized. 【0010】 Furthermore, in conventional speed reducers, the first face gear and the inner ring of the spline section are separate components, and they are connected using fastening members. As a result, the coaxial accuracy between the first face gear and the inner ring of the spline section may be low. In this case, it is not possible to accurately precess the first face gear. 【0011】 The third invention was made in view of the above-mentioned problems, and its third objective is to provide a reduction or speed increase device that can improve the coaxial accuracy between the first face gear and the inner ring of the spline section. [Means for solving the problem] 【0012】 To solve the first problem described above, the first invention provides a reduction or acceleration device that tilts a first face gear so as to mesh with a second face gear, and oscillates the first face gear so as to move the meshing portion in the circumferential direction, wherein the device includes a ball spline section that supports the first face gear so as to be tiltable, the ball spline section comprising an outer ring, an inner ring, balls that can roll along the ball grooves of the outer ring and the ball grooves of the inner ring, and a retainer in which pockets into which the balls are incorporated are formed, and a motion conversion section that allows axial displacement of the first face gear and converts the rotational motion of an input section into the precessional motion of the first face gear is disposed between the housing and the first face gear. The ball grooves of the outer ring and inner ring of the ball spline portion extend in a straight line. It is a speed reduction or acceleration device. 【0013】 To solve the second problem described above, the second invention provides a reduction or speed increase device that tilts a first face gear so as to mesh with a second face gear, and oscillates the first face gear so as to move the meshing portion in the circumferential direction, comprising: a ball spline section that supports the first face gear so as to be tiltable and transmits the rotation of the first face gear to an output section; and a bearing section that rotatably supports the output section, wherein the ball spline section comprises an outer ring, an inner ring, and balls that can roll along the ball grooves of the outer ring and the ball grooves of the inner ring; the bearing section comprises an outer ring with rolling element grooves extending in the circumferential direction formed on its inner surface, an inner ring with rolling element grooves extending in the circumferential direction formed on its outer surface, and rolling elements that can roll along the rolling element grooves of the outer ring and the rolling element grooves of the inner ring, wherein the outer ring of the ball spline section and the inner ring of the bearing section are integrally formed. Multiple teeth are arranged on the surface of the first face gear that faces the second face gear. Formed in a radial pattern, the second face gear has multiple surfaces facing the first face gear. The teeth are formed radially, and the teeth of the first face gear and the teeth of the second face gear are directly Fits well It is a speed reduction or acceleration device. 【0014】 To solve the third problem described above, the third invention provides a reduction or speed increase device that tilts a first face gear so as to mesh with a second face gear, and oscillates the first face gear so as to move the meshing portion in the circumferential direction, wherein the first face gear is supported so as to be tiltable, and the ball spline portion comprises an outer ring, an inner ring, balls that can roll along the ball grooves of the outer ring and the ball grooves of the inner ring, and a retainer in which pockets into which the balls are incorporated are formed, wherein the first face gear and the inner ring of the ball spline portion are integrally formed. The retainer is formed with notches that allow the protrusions between the ball grooves of the inner ring to pass through, so that the axis of the retainer and the axis of the inner ring can be inserted into the retainer with the axis of the inner ring aligned. It is a speed reduction or acceleration device. [Effects of the Invention] 【0015】 According to the first invention, since the ball spline portion allows axial displacement of the first face gear, the first face gear and the second face gear can continue to mesh even if there are machining errors or wear, thereby suppressing unevenness in output torque. 【0016】 According to the second invention, since the outer ring of the ball spline section and the inner ring of the bearing section are formed integrally, the reduction or speed increase device can be miniaturized. 【0017】 According to the third invention, the coaxial accuracy between the first face gear and the inner ring of the ball spline section can be improved. [Brief explanation of the drawing] 【0018】 [Figure 1] This is a cross-sectional view along the axis of the reduction gear of the first embodiment of the present invention. [Figure 2] This is an exploded perspective view of a reduction gear according to the first embodiment of the present invention (Figure 2(a) is a perspective view from the output side, and Figure 2(b) is a perspective view from the input side). [Figure 3] This is a cross-sectional view along the axis of a reduction gear according to a second embodiment of the present invention. [Figure 4]It is an exploded perspective view of the speed reducer according to the second embodiment of the present invention (FIG. 4(a) is a perspective view seen from the output part side, and FIG. 4(b) is a perspective view seen from the input part side). [Figure 5] It is a cross-sectional view along the axis of the speed reducer according to the third embodiment of the present invention. [Figure 6] FIG. 6(a) shows an exploded perspective view of the ball spline part of the speed reducer according to the third embodiment of the present invention, and FIG. 6(b) shows an exploded perspective view of the ball spline part of the speed reducer according to the second embodiment of the present invention. [Figure 7] It is an enlarged view of the retainer of the speed reducer according to the third embodiment of the present invention. [Figure 8] It is an assembly process diagram of the ball spline part of the speed reducer according to the second embodiment of the present invention. [Figure 9] It is an assembly process diagram of the ball spline part of the speed reducer according to the third embodiment of the present invention. [Figure 10] It is an assembly process diagram of the speed reducer according to the third embodiment of the present invention (a view showing only the inner ring by cutting the gear part of the first face gear). [Figure 11] It is a view showing a modified example of the ball spline part of the speed reducer according to the third embodiment of the present invention (FIG. 11(b) is a front view, and FIG. 11(a) is a cross-sectional view taken along line A-A of FIG. 11(b)). [Figure 12] It is an exploded perspective view of the ball spline part of the modified example. [Figure 13] It is an assembly process diagram of the ball spline part of the modified example. 【Embodiments for Carrying Out the Invention】 【0019】 Hereinafter, the speed reducer according to the embodiment of the present invention will be described based on the accompanying drawings. However, the speed reducer of the present invention can be embodied in various forms and is not limited to the embodiments described in this specification. This embodiment is provided with the intention of enabling those skilled in the art to fully understand the invention by sufficiently disclosing the specification. (First Embodiment) 【0020】 Figure 1 is a cross-sectional view of a reduction gear 10 according to a first embodiment of the present invention. 1 is a first face gear, 2 is a second face gear, and 3 is a ball spline section that supports the first face gear 1 in a tiltable manner. 【0021】 8a is the input unit, 9 is the motion conversion unit that converts the rotational motion of the input unit 8a into the oscillation of the first face gear 1 (hereinafter referred to as precession), and 15a is the output unit. Precession is the motion in which the axis 1c of the first face gear 1 traces a conical surface with its apex at the joint center O of the ball spline unit 3 (the intersection point of the plane containing the centers of the multiple balls 5 of the ball spline unit 3 and the axis 10a of the reduction device 10). In the first embodiment, the ball spline unit 3 allows the first face gear 1 to precess and restricts the first face gear 1 from rotating around the axis 10a of the reduction device 10. When the input unit 8a is rotated, the first face gear 1 precesses, and the second face gear 2 rotates at a reduced speed by the difference in the number of teeth between it and the first face gear 1. The reduced rotation of the second face gear 2 is taken out by the output unit 15a. 【0022】 If the number of teeth of the first face gear 1 is Z1 and the number of teeth of the second face gear 2 is Z2, the reduction ratio A of the reduction device 10 is expressed by the following formula. A = (Z1 - Z2) / Z2 【0023】 The configuration of each part of the reduction gear 10 will be explained below with reference to the exploded perspective view in Figure 2. Figure 2(a) is an exploded perspective view seen from the output section 15a side, and Figure 2(b) is an exploded perspective view seen from the input section 8a side. 【0024】 As shown in Figure 2(a), the first face gear 1 is formed in an annular shape. Multiple teeth 1a are formed radially on the surface of the first face gear 1 facing the second face gear 2. As shown in Figure 1, the apex of the conical surface 1d on which the tooth traces of the first face gear 1 are formed coincides with the joint center O of the ball spline section 3. 【0025】 As shown in Figure 2(b), the second face gear 2 is also formed in an annular shape. Multiple teeth 2a are formed radially on the surface of the second face gear 2 facing the first face gear 1. The number of teeth of the second face gear 2 is different from the number of teeth of the first face gear 1. As shown in Figure 1, the apex of the conical surface 2d on which the tooth traces of the second face gear 2 are formed coincides with the joint center O of the ball spline section 3. 【0026】 As shown in Figure 1, the ball spline section 3 allows angular displacement of the first face gear 1, as well as axial displacement of the first face gear 1 (in the direction of the axis 10a of the reduction gear 10). The ball spline section 3 comprises an outer ring 4, an inner ring 6, balls 5 that can roll along the ball grooves 4a of the outer ring 4 and the ball grooves 6a of the inner ring 6, and a retainer 7 in which pockets 7a into which the balls 5 are incorporated are formed. 【0027】 The outer ring 4 is cylindrical and integrally formed with the housing. A flange 4b ​​having a through hole 4c for fastening to the outer ring 17 of the bearing portion 16 is integrally formed on the outer ring 4. Multiple ball grooves 4a (see Figure 2(a)) extending in the axial direction are formed on the cylindrical inner surface 4d of the outer ring 4 (see Figure 2(a)). The ball grooves 4a of the outer ring 4 are formed linearly parallel to the axial direction so that the first face gear 1 can be displaced in the axial direction. 【0028】 As shown in Figure 1, the inner ring 6, which is fitted inside the outer ring 4, is fastened to the first face gear 1. The inner ring 6 has a screw hole 6b (see Figure 2(a)) for fastening the first face gear 1. The inner ring 6 has a spherical outer surface 6c (see Figure 2(a)), and a ball groove 6a (see Figure 2(a)) extending in the axial direction is formed on the spherical outer surface 6c. The ball groove 6a of the inner ring 6 is formed linearly parallel to the axial direction. A ball track is formed between the ball groove 4a of the outer ring 4 and the ball groove 6a of the inner ring 6. Note that at least a portion of the ball grooves 4a, 6a of the outer ring 4 and / or the inner ring 6 may be formed linearly parallel to the axial direction to allow axial displacement of the first face gear 1. 【0029】 A retainer 7 is incorporated between the outer ring 4 and the inner ring 6. Pockets 7a are formed in the retainer 7 at positions facing the ball track. A ball 5 is incorporated into each pocket 7a. The ball 5 is capable of rolling along the ball track. 【0030】 The retainer 7 contacts the inner surface of the outer ring 4 and the outer surface of the inner ring 6, and is guided by the inner surface of the outer ring 4 and the outer surface of the inner ring 6. A partial spherical surface 7b is formed on the outer surface of the retainer 7 that contacts the cylindrical inner surface 4d of the outer ring 4. A partial spherical surface 7c is formed on the inner surface of the retainer 7 that contacts the spherical outer surface 6c of the inner ring 6. The curvature centers O1 of the partial spherical surface 7b and O2 of the partial spherical surface 7c are offset by equidistant distances in the axial direction to the left and right with respect to the joint center O of the ball spline portion 3. Therefore, when the inner ring 6 fastened to the first face gear 1 tilts together with the first face gear 1, the balls 5 are positioned on the bisector of the tilt angle of the inner ring 6. 【0031】 The motion conversion unit 9 converts the rotational motion of the input unit 8a into the precessional motion of the first face gear 1. The motion conversion unit 9 comprises an inclined cam 8b, a plurality of first rolling elements 11 interposed between the inclined cam 8b and the first face gear 1, and a plurality of second rolling elements 13 interposed between the inclined cam 8b and a ring 14 fixed to the housing 19. The inclined cam 8b is formed integrally with the input unit 8a. The first rolling elements 11 and the second rolling elements 13 are held by retainers 21 and 22 (see Figure 2(a)). The motion conversion unit 9 is positioned between the housing 19 and the first face gear 1. 【0032】 As shown in Figure 1, the output section 15a is rotatably supported by the bearing section 16. The rolling elements 18 of the bearing section 16 are rollers, and the bearing section 16 is, for example, a cross-roller bearing. Balls may also be used for the rolling elements 18 of the bearing section 16. A flange 17a having a through hole 17c for fastening to the outer ring 4 of the ball spline section 3, which functions as a housing, is integrally formed on the outer ring 17 of the bearing section 16. The output section 15a is integrally formed on the inner ring 15b of the bearing section 16. The output section 15a is hollow. A bearing section 20 that rotatably supports the input section 8a is incorporated into the output section 15a. 【0033】 The configuration of the reduction gear 10 of the first embodiment has been described above. The reduction gear 10 of the first embodiment provides the following effects. 【0034】 Since the ball spline section 3 allows for axial displacement of the first face gear 1, the first face gear 1 and the second face gear 2 can continue to mesh even if there are machining errors or wear, thereby suppressing unevenness in output torque. 【0035】 Since the retainer 7 of the ball spline section 3 holds the ball 5, it is possible to prevent the ball 5 from getting stuck and suppress the occurrence of unevenness in the output torque. 【0036】 Since the curvature center O1 of the partial spherical surface 7b formed on the outer surface of the retainer 7 of the ball spline section 3 and the curvature center O2 of the partial spherical surface 7c formed on the inner surface of the retainer 7 are offset to the left and right in the axial direction with respect to the joint center O of the ball spline section 3, the ball 5 can be displaced along the line bisector of the inclination angle of the inner ring 6. (Second embodiment) 【0037】 Figure 3 is a cross-sectional view of a reduction gear 40 according to a second embodiment of the present invention. 31 is a first face gear, and 32 is a second face gear. 33 is a ball spline section that supports the first face gear 31 so as to be tiltable and transmits the rotation of the first face gear 31 to the output section 45a. 46 is a bearing section that rotatably supports the output section 45a. 【0038】 38 is an input unit, and 39 is a motion conversion unit that converts the rotational motion of the input unit 38 into the precessional motion of the first face gear 31. In the second embodiment, the second face gear 32 is fixed to the housing 49. The output unit 45a is connected to the first face gear 31 via the ball spline unit 33. 【0039】 When the input unit 38 is rotated, the first face gear 31 precesses, and the first face gear 31 rotates at a reduced speed by the difference in the number of teeth between it and the second face gear 32. The reduced rotation of the first face gear 31 is taken out to the output unit 45a via the ball spline unit 33. 【0040】 If the number of teeth of the first face gear 31 is Z1 and the number of teeth of the second face gear 32 is Z2, the reduction ratio A of the reduction gear is expressed by the following formula. A = (Z2 - Z1) / Z1 【0041】 The configuration of each part of the reduction gear 40 will be explained below with reference to the exploded perspective view in Figure 4. Figure 4(a) is an exploded perspective view seen from the output section 45a side, and Figure 4(b) is an exploded perspective view seen from the input section 38 side. 【0042】 As shown in Figure 4(a), the first face gear 31 is annular. Multiple teeth 31a are formed radially on the surface of the first face gear 31 facing the second face gear 32. As shown in Figure 3, the apex of the conical surface 31d on which the tooth traces of the first face gear 31 are formed coincides with the joint center O of the ball spline portion 33. The teeth 31a of the first face gear 31 are inclined such that the apex of the conical surface 31d is closer in the axial direction to the bearing portion 46 than the tooth surface of the first face gear 31. That is, the teeth 31a of the first face gear 31 in the second embodiment are inclined in the opposite direction to the teeth 1a of the first face gear 1 in the first embodiment. 【0043】 The first face gear 31 has a protruding serration portion 31b (see Figure 4(a)) for attaching the inner ring of the ball spline portion 33. Numerous grooves extending in the axial direction are formed on the outer surface of the serration portion 31b. 【0044】 As shown in Figure 4(b), the second face gear 32 is annular. Multiple teeth 32a are formed radially on the surface of the second face gear 32 facing the first face gear 31. The number of teeth of the second face gear 32 is different from the number of teeth of the first face gear 31. As shown in Figure 3, the apex of the conical surface 32d on which the tooth traces of the second face gear 32 are formed coincides with the joint center O of the ball spline portion 33. The teeth 32a of the second face gear 32 are inclined such that the apex of the conical surface 32d is axially closer to the bearing portion 46 than the tooth surface of the second face gear 32. That is, the teeth 32a of the second face gear 32 in the second embodiment are inclined in the opposite direction to the teeth 2a of the second face gear 2 in the first embodiment. 【0045】 As shown in Figure 3, the ball spline portion 33 allows for angular displacement of the first face gear 31, as well as axial displacement of the first face gear 31. 【0046】 The ball spline section 33 comprises an outer ring 45c, an inner ring 36, balls 35 that can roll along the ball grooves 45d of the outer ring 45c and the ball grooves 36a of the inner ring 36, and a retainer 37 in which pockets 37a (see Figure 4(a)) into which the balls 35 are incorporated are formed. 【0047】 The outer ring 45c is cylindrical and is formed integrally with the inner ring 45b of the bearing portion 46. Multiple ball grooves 45d extending in the axial direction are formed on the cylindrical inner surface 45e of the outer ring 45c (see Figure 4(a)). 【0048】 The inner ring 36, which is incorporated inside the outer ring 45c, is fitted into the serrated portion 31b of the first face gear 31. A serrated portion 36b (see Figure 4(a)) consisting of a plurality of grooves extending in the axial direction is formed on the inner surface of the inner ring 36. A plurality of ball grooves 36a extending in the axial direction are formed on the spherical outer surface 36c of the inner ring 36. A ball track is formed between the ball groove 45d of the outer ring 45c and the ball groove 36a of the inner ring 36. At least a portion of the ball grooves 45d, 36a of the outer ring 45c and / or the inner ring 36 may be formed linearly parallel to the axial direction to allow axial displacement of the first face gear 31. 【0049】 A cage 37 is incorporated between the outer ring 45c and the inner ring 36. Pockets 37a are formed in the cage 37 at positions facing the ball track. A ball 35 is incorporated into each pocket 37a. The balls 35 are capable of rolling along the ball track. 【0050】 The retainer 37 is in contact with the inner surface of the outer ring 45c and the outer surface of the inner ring 36, and is also guided by the inner surface of the outer ring 45c and the outer surface of the inner ring 36. 【0051】 The configuration of the ball groove 45d formed on the cylindrical inner surface 45e of the outer ring 45c, the ball groove 36a formed on the spherical outer surface 36c of the inner ring 36, and the partial spherical surfaces 37b and 37c formed on the outer and inner surfaces of the retainer 37 is substantially the same as that of the first embodiment. 【0052】 The curvature center O1 of the partial spherical surface 37b on the outer surface of the retainer 37 and the curvature center O2 of the partial spherical surface 37c on the inner surface of the retainer 37 are offset by an equal distance to the left and right in the axial direction with respect to the joint center O of the ball spline section 33. Therefore, when the inner ring 36 attached to the first face gear 31 tilts together with the first face gear 31, the ball 35 is displaced along the bisector of the tilt angle of the inner ring 36, and constant speed rotation is transmitted between the first face gear 31 and the output section 45a. 【0053】 The motion conversion unit 39 converts the rotational motion of the input unit 38 into the precessional motion of the first face gear 31. The motion conversion unit 39 comprises an inclined cam 42, a plurality of first rolling elements 41 interposed between the inclined cam 42 and a ring 34 fixed to the first face gear 31, and a plurality of second rolling elements 43 interposed between the inclined cam 42 and a ring 44 fixed to the housing 49. The first rolling elements 41 and the second rolling elements 43 are held by retainers 71 and 72 (see Figure 4(a)). The motion conversion unit 39 is positioned between the housing 49 and the first face gear 31. A serrated portion 42a (see Figure 4(a)) consisting of a plurality of grooves extending in the axial direction is formed on the inner surface of the inclined cam 42. A serrated portion 38a (see Figure 4(a)) consisting of a plurality of grooves extending in the axial direction is formed on the outer surface of the input unit 38. The input section 38 and the inclined cam 42 are non-rotatably connected via serrated sections 38a and 42a. The input section 38 is formed to be hollow. 【0054】 As shown in Figure 3, the output section 45a is rotatably supported by the bearing section 46. The bearing section 46 comprises an outer ring 47 with circumferentially extending rolling element grooves 47a formed on its inner surface, an inner ring 45b with circumferentially extending rolling element grooves 45b1 formed on its outer surface, and rolling elements 48 that can roll along the rolling element grooves 47a of the outer ring 47 and the rolling element grooves 45b1 of the inner ring 45b. The rolling elements 48 are rollers, and the bearing section 46 is, for example, a cross-roller bearing. Balls may also be used for the rolling elements 48. 【0055】 A flange 47b is integrally formed on the outer ring 47, having a through hole 47c for fastening to the housing 49. The flange 47b protrudes further toward the second face gear 32 than the inner ring 45b. When this flange 47b fits into the recess 32b of the second face gear 32, the bearing portion 46 can be centered. The second face gear 32 is fastened to the housing 49 together with the outer ring 47. 【0056】 The outer ring 45c of the ball spline section 33 is integrally formed on the inner ring 45b of the bearing section 46. The output section 45a is also integrally formed on the inner ring 45b. A seal 54 is provided between the outer ring 47 and the inner ring 45b of the bearing section 46. Multiple screw holes 73 are formed in the output section 45a for attachment to a mating part such as an output shaft. 【0057】 The configuration of the reduction gear 40 of the second embodiment has been described above. The reduction gear 40 of the second embodiment provides the following effects, which are substantially the same as those of the reduction gear of the first embodiment. 【0058】 Since the ball spline section 33 allows for axial displacement of the first face gear 31, the first face gear 31 and the second face gear 32 can continue to mesh even if there are machining errors or wear, thereby suppressing unevenness in output torque. 【0059】 Since the retainer 37 of the ball spline section 33 holds the ball 35, it is possible to prevent the ball 35 from getting stuck and suppress the occurrence of unevenness in the output torque. 【0060】 Since the curvature center O1 of the partial spherical surface 37b formed on the outer surface of the retainer 37 of the ball spline section 33 and the curvature center O2 of the partial spherical surface 37c formed on the inner surface of the retainer 37 are offset to the left and right in the axial direction with respect to the joint center O of the ball spline section 33, the ball 35 is displaced along the line bisector of the inclination angle of the inner ring 36. As a result, constant speed rotation can be transmitted between the first face gear 31 and the output section 45a, and unevenness in the output torque can be suppressed. 【0061】 Furthermore, the reduction gear 40 of the second embodiment provides the following additional effects. 【0062】 Since the outer ring 45c of the ball spline section 33 and the inner ring 45b of the bearing section 46 are formed as a single unit, the number of parts can be reduced, and the reduction gear 40 can be made smaller. 【0063】 Since the output section 45a is integrally formed with the outer ring 45c of the ball spline section 33 and the inner ring 45b of the bearing section 46, the number of parts can be reduced, and the reduction gear 40 can be made smaller. 【0064】 By integrally forming a flange 47b with a through hole 47c for fastening the outer ring 47 to the housing 49 of the reduction gear 40 on the outer ring 47 of the bearing portion 46, the reduction gear 40 can be made smaller. 【0065】 When torque is applied to the input section 38, a reaction force P (see Figure 3) acts on the meshing portion between the first face gear 31 and the second face gear 32. This reaction force P is divided into a radial component P1 and an axial component P2. The radial component P1 is transmitted to the output section 45a via the ball 35 of the ball spline section 33. In this embodiment, the teeth 31a and 32a of the first face gear 31 and the second face gear 32 are inclined such that the apex O of the conical surfaces 31d and 32d on which the tooth traces are formed is axially closer to the bearing section 46 than the tooth surfaces of the first face gear 31 and the second face gear 32. Since the joint center O of the ball spline section 33 and the vertices O of the conical surfaces 31d and 32d coincide, by inclining the teeth 31a and 32a of the first face gear 31 and the second face gear 32 as described above, the balls 35 of the ball spline section 33 can be brought axially closer to the rolling elements 48 of the bearing section 46 (the balls 35 of the ball spline section 33 and the rolling elements 48 of the bearing section 46 can be arranged in a nearly straight line). If the balls 35 of the ball spline section 33 and the rolling elements 48 of the bearing section 46 are separated axially, there is a risk that the output section 45a will oscillate around the bearing section 46 due to the radial force component P1. By bringing the balls 35 of the ball spline section 33 closer axially to the rolling elements 48 of the bearing section 46, the oscillating of the output section 45a can be prevented. (Third embodiment) 【0066】 Figure 5 is a cross-sectional view of a reduction gear 50 according to a third embodiment of the present invention. The reduction gear 50 of the third embodiment, like the reduction gear 40 of the second embodiment, includes a first face gear 31, a second face gear 32, an input unit 38, a motion conversion unit 39, a bearing unit 46, and an output unit 45a. When the input unit 38 is rotated, the first face gear 31 precesses, and the first face gear 31 rotates at a reduced speed by the difference in the number of teeth between it and the second face gear 32. The reduced rotation of the first face gear 31 is taken out by the output unit 45a via the ball spline unit 51. The ball spline unit 51 allows the precession of the first face gear 31 and also allows axial displacement of the first face gear 31. The configuration of the first face gear 31, the second face gear 32, the input unit 38, the motion conversion unit 39, the bearing unit 46, and the output unit 45a is substantially the same as that of the reduction gear 40 of the second embodiment, so the same reference numerals are used and their descriptions are omitted. 【0067】 Figure 6 is an exploded perspective view comparing the ball spline section 51 of the reduction gear 50 of the third embodiment (Figure 6(a)) with the ball spline section 33 of the reduction gear 40 of the second embodiment (Figure 6(b)). As shown in Figure 6(a), the ball spline section 51 of the reduction gear 50 of the third embodiment comprises an outer ring 45c, an inner ring 52, balls 35 that can roll along the ball grooves 45d of the outer ring 45c and the ball grooves 52b of the inner ring 52, and a retainer 53 in which pockets 53a into which the balls 35 are incorporated are formed. The configuration of the outer ring 45c and the balls 35 is the same as that of the ball spline section 33 of the second embodiment, so the same reference numerals are used and their description is omitted. 【0068】 As shown in Figure 6(a), a plurality of ball grooves 52b extending in the axial direction are formed on the spherical outer surface 52a of the inner ring 52. A ball track is formed between the ball groove 45d of the outer ring 45c and the ball grooves 52b of the inner ring 52. The configuration of the spherical outer surface 52a and ball grooves 52b of the inner ring 52 is the same as that of the inner ring 36 of the ball spline section 33 in the second embodiment. 【0069】 A retainer 53 is incorporated between the outer ring 45c and the inner ring 52. Pockets 53a are formed in the retainer 53 at positions facing the ball track. A ball 35 is incorporated into each pocket 53a. The configuration of the pockets 53a of the retainer 53, the partial spherical surface 53b on the outer surface of the retainer 53, and the partial spherical surface 53c on the inner surface of the retainer 53 is the same as that of the retainer 37 of the ball spline section 33 in the second embodiment. 【0070】 As shown in Figure 6(b), in the ball spline section 33 of the second embodiment, the cylindrical serrated section 31b of the first face gear 31 is press-fitted into the serrated section 36b on the inner surface of the inner ring 36. In contrast, as shown in Figure 6(a), in the ball spline section 51 of the third embodiment, the inner ring 52 is integrally formed with the first face gear 31. 【0071】 Furthermore, as shown in Figure 6(a), in the ball spline section 51 of the third embodiment, the retainer 53 has notches 53d that allow the inner ring 52 to be inserted into the retainer 53 with the axis 53-1 of the retainer 53 and the axis 52-1 of the inner ring 52 aligned, thereby allowing the protrusions (spherical outer surfaces) 52a between the ball grooves 52b of the inner ring 52 to pass through (see also the enlarged view of Figure 7). The notches 53d are formed in conjunction with the pockets 53a. The number of notches 53d is the same as the number of pockets 53a. 【0072】 Figure 8 shows the assembly process diagram for the ball spline section 33 of the second embodiment. Figures 9 and 10 show the assembly process diagram for the ball spline section 51 of the third embodiment. In Figure 10, for clarity, the flange-shaped gear section of the first face gear 31 in Figure 9 has been cut away, and only the inner ring 52 is shown. 【0073】 As shown in Figure 8, in the ball spline section 33 of the second embodiment, the inner ring 36 is inserted into the two notches 37d of the cage 37 with the axis 37-1 of the cage 37 and the axis 36-1 of the inner ring 36 perpendicular to each other, in other words, with the inner ring 36 tilted 90° relative to the cage 37 (S1, S2). Since the inner surface of the cage 37 has an undercut shape, it is necessary to form the notches 37d in order to insert the inner ring 36. Next, the inner ring 36 is rotated 90° inside the cage 37 (S2, S3). Next, the first face gear 31 is press-fitted onto the inner ring 36 (S4). Next, the balls 35 are inserted into the pockets 37a of the cage 37 (S5, S6), and the cage 37 and inner ring 36 are assembled onto the outer ring 45c (S7). This completes the assembly of the ball spline section 33 (S8). 【0074】 In contrast, as shown in Figures 9 and 10, in the ball spline section 51 of the third embodiment, the inner ring 52 is inserted into the cage 53 with the axis 53-1 of the cage 53 aligned with the axis 52-1 of the inner ring 52, and the phase of the projection 52a of the inner ring 52 and the notch 53d of the cage 53 aligned (S1, S2). Next, the cage 53 is rotated 360° / 2N (where N is the number of projections 52a) around its axis 53-1 (S3). At this time, as shown in the upper part of S3 in Figure 10, the pocket 53a of the cage 53 and the ball groove 52b of the inner ring 52 face each other. Then, as shown in the lower part of S3 in Figure 10, the partial spherical surface 53c on the inner surface of the cage 53 and the projection 52a of the inner ring 52 engage. As a result, the cage 53 becomes unable to move axially relative to the inner ring 52. Next, the balls 35 are inserted into the pockets 53a of the retainer 53 (S4, S5). By inserting the balls 35, the rotation of the retainer 53 is prevented, so the retainer 53 rotates in the opposite direction so that the phase of the notch 53d of the retainer 53 and the protrusion 52a of the inner ring 52 are aligned, and the retainer 53 does not fall off the inner ring 52. Next, the retainer 53 and the inner ring 52 are assembled onto the outer ring 45c (S6). This completes the assembly of the ball spline section 51 (S7). (Modified example of the ball spline section of the reduction gear of the third embodiment) 【0075】 Figures 11 and 12 show a modified example 61 of the ball spline section 51 of the reduction gear 50 of the third embodiment. In the ball spline section 51 of the reduction gear 50 of the third embodiment, linear ball grooves 45d and 52b extending in the axial direction are formed in the outer ring 45c and the inner ring 52 in order to allow axial displacement of the inner ring 52 relative to the outer ring 45c. 【0076】 In contrast, as shown in Figures 11 and 12, in the modified ball spline section 61, in order to prevent the inner ring 63 from moving axially relative to the outer ring 62, an arc-shaped ball groove 62b is formed on the spherical inner surface 62a of the outer ring 62, and an arc-shaped ball groove 63b is formed on the spherical outer surface 63a of the inner ring 63. In reality, the first face gear 31 is integrally formed on the inner ring 63, but in Figures 11 and 12, only the inner ring 63 is shown for clarity. 【0077】 As shown in Figure 12, the outer ring 62 has a spherical inner surface 62a. Multiple arc-shaped ball grooves 62b are formed in the circumferential direction on the spherical inner surface 62a. The inner ring 63 has a spherical outer surface 63a. Multiple arc-shaped ball grooves 63b are formed in the circumferential direction on the spherical outer surface 63a. As shown in Figure 11(a), the curvature centers a of the arc-shaped ball grooves 62b of the outer ring 62 and the curvature centers b of the arc-shaped ball grooves 63b of the inner ring 63 are offset by an equal distance to the left and right in the axial direction with respect to the joint center O of the ball spline portion 61. 【0078】 As shown in Figure 12, the retainer 64 has a pocket 64a into which the ball 35 is inserted. The outer surface of the retainer 64 has a partial spherical surface 64b that contacts and guides the spherical inner surface 62a of the outer ring 62. The inner surface of the retainer 64 has a partial spherical surface 64c that contacts and guides the spherical outer surface 63a of the inner ring 63. The inner surface of the retainer 64 has a notch 64d that allows the passage of the protrusions (spherical outer surfaces) 63a between the ball grooves 63b of the inner ring 63. The configuration of the pocket 64a, notch 64d, and partial spherical surfaces 64b, 64c of the retainer 64 is the same as that of the retainer 53 of the ball spline section 51 in the third embodiment. 【0079】 As shown in Figure 12, in the modified ball spline section 61, relief grooves 64e are formed on the outer surface of the retainer 64 to allow the passage of the protrusions (spherical inner surfaces) 62a between the ball grooves 62b of the outer ring 62, so that the retainer 64 can be inserted into the outer ring 62 with the axis 64-1 of the retainer 64 and the axis 62-1 of the outer ring 62 aligned. The relief grooves 64e are formed continuously with the pockets 64a and extend along the entire axial length of the retainer 64. The number of relief grooves 64e is the same as the number of pockets 64a. 【0080】 Figure 13 shows the assembly process diagram of a modified ball spline section 61. As shown in S1 and S2 of Figure 13, the cage 64 is inserted into the outer ring 62 with the axis 64-1 of the cage 64 aligned with the axis 62-1 of the outer ring 62, and the phase of the projection 62a of the outer ring 62 aligned with the relief groove 64e of the cage 64. Similarly, the inner ring 63 is inserted into the cage 64 with the axis 64-1 of the cage 64 aligned with the axis 63-1 of the inner ring 63, and the phase of the projection 63a of the inner ring 63 aligned with the notch 64d of the cage 64 (S1 and S2). Next, as shown in S3 of Figure 13, the cage 64 is rotated 360° / 2N (where N is the number of projections 62a) around its axis 64-1 (S3). Next, as shown in S4 of Figure 13, the retainer 64 and the inner ring 63 are tilted, and the ball 35 is inserted into the pocket 64a of the retainer 64 (S4). This completes the assembly of the ball spline section 61. 【0081】 The configuration of the reduction gear 50 of the third embodiment has been described above. The reduction gear 50 of the third embodiment provides substantially the same effects as the reduction gear 40 of the second embodiment, and also provides the following additional effects. 【0082】 Since the first face gear 31 and the inner rings 52 and 63 of the ball spline sections 51 and 61 are integrally formed, the coaxial accuracy between the first face gear 31 and the inner rings 52 and 63 of the ball spline sections 51 and 61 can be improved. As a result, the first face gear 31 can be precisely precessed, and the efficiency of the reduction gear 50 is improved. 【0083】 Since there is no need to form serrations on the first face gear 31 and the inner rings 52 and 63, the hollow holes that can be effectively used as space for wiring and the like can be made larger. 【0084】 Since the process of press-fitting the first face gear 31 into the inner rings 52 and 63 is unnecessary, the assembly of the ball spline sections 51 and 61 becomes easier. 【0085】 The ball spline sections 51 and 61 can be disassembled after assembly. To elaborate on this effect, in the reduction gear 40 of the second embodiment, the first face gear 31 is press-fitted into the inner ring 36, so after assembly, the inner ring 36 cannot be tilted 90° relative to the cage 37, and the inner ring 36 cannot be disassembled from the cage 37. In contrast, in the reduction gear 50 of the third embodiment, the balls 35 can be removed from the cages 53 and 64, and the cages 53 and 64 can be rotated 360° / 2N relative to the inner rings 52 and 63, thereby disassembling the inner rings 52 and 63 from the cages 53 and 64. 【0086】 Furthermore, the present invention is not limited to being embodied in the above embodiments, and can be embodied in other embodiments without changing the gist of the present invention. 【0087】 For example, in the above embodiment, an example of applying the present invention to a speed reduction device was described, but by swapping the input and output sides, the present invention can also be applied to a speed increase device. 【0088】 This specification is based on Japanese Patent Application No. 2021-067556, filed on April 13, 2021. All of its contents are included herein. [Explanation of Symbols] 【0089】 1...First face gear, 2...Second face gear, 3...Ball spline section, 4...Outer ring of the ball spline section, 4a...Ball groove of the outer ring, 5...Ball of the ball spline section, 6...Inner ring of the ball spline section, 6a...Ball groove of the inner ring, 7...Cage, 7a...Pocket of the cage, 7b...Partial spherical surface of the outer surface of the cage, 7c...Partial spherical surface of the inner surface of the cage, 10...Reduction gear, 31...First face gear, 31a...Teeth of the first face gear, 31d...First face 32...Conical surface where the gear teeth traces are taut, 32a...Second face gear, 32d...Teeth of the second face gear, 33...Conical surface where the second face gear teeth traces are taut, 35...Ball of the ball spline section, 36...Inner ring of the ball spline section, 36a...Ball groove of the inner ring, 37...Cage, 37a...Pocket of the cage, 37b...Partial spherical surface of the outer surface of the cage, 37c...Partial spherical surface of the inner surface of the cage, 40...Reduction gear, 45a...Output section, 45b...Bearing section 45b1...Rolling element groove of the inner ring of the bearing section, 45c...Outer ring of the ball spline section, 45d...Ball groove of the outer ring of the ball spline section, 46...Bearing section, 47...Outer ring of the bearing section, 47a...Rolling element groove of the outer ring of the bearing section, 47b...Flange, 48...Rolling element, 51...Ball spline section, 52...Inner ring of the ball spline section, 52a...Protrusion of the inner ring, 52b...Ball groove of the inner ring, 52-1...Axis of the inner ring, 53...Cage, 53a...Pocket, 53d...Notch, 53-1...Axis of the retainer, 61...Ball spline section, 62...Outer ring of the ball spline section, 63...Inner ring of the ball spline section, 63a...Protrusion of the inner ring, 63b...Ball groove of the inner ring, 63-1...Axis of the inner ring, 64...Retainer, 64a...Pocket, 64d...Notch, 64-1...Axis of the retainer, O...Joint center of the ball spline section, O1...Center of curvature of the partial sphere formed on the outer surface of the retainer, O2...Center of curvature of the partial sphere formed on the inner surface of the retainer

Claims

[Claim 1] In a speed reduction or acceleration device in which a first face gear is tilted to mesh with a second face gear, and the first face gear is oscillated so that the meshing portion moves in the circumferential direction, The first face gear is provided with a ball spline section that allows it to be tilted, The ball spline portion comprises an outer ring, an inner ring, balls that can roll along the ball grooves of the outer ring and the ball grooves of the inner ring, and a retainer in which pockets are formed into which the balls are incorporated. The axial displacement of the first face gear is permitted, A motion conversion unit is positioned between the housing and the first face gear to convert the rotational motion of the input unit into the precessional motion of the first face gear. A speed reduction or acceleration device in which the ball grooves of the outer ring and the inner ring of the ball spline section extend in a straight line. [Claim 2] The reduction or speed increase device according to claim 1, characterized in that the apex of the conical surface through which the tooth traces of the first face gear and the second face gear are formed coincides with the joint center of the ball spline portion. [Claim 3] The speed reduction or speed increase device according to claim 1 or 2, characterized in that the curvature center of the partial sphere formed on the outer surface of the retainer and the curvature center of the partial sphere formed on the inner surface of the retainer are offset to the left and right in the axial direction with respect to the joint center of the ball spline portion. [Claim 4] The reduction or speed increase device according to claim 1 or 2, characterized in that the motion conversion unit comprises an inclined cam, a plurality of first rolling elements interposed between the inclined cam and a ring fixed to the first face gear, and a plurality of second rolling elements interposed between the inclined cam and a ring fixed to the housing. [Claim 5] In a speed reduction or acceleration device in which a first face gear is tilted to mesh with a second face gear, and the first face gear is oscillated so that the meshing portion moves in the circumferential direction, A ball spline section that supports the first face gear so as to be tiltable and transmits the rotation of the first face gear to the output section, The system includes a bearing that rotatably supports the output section, The ball spline portion comprises an outer ring, an inner ring, and balls that can roll along the ball grooves of the outer ring and the ball grooves of the inner ring. The bearing portion comprises an outer ring having circumferentially extending rolling element grooves on its inner surface, an inner ring having circumferentially extending rolling element grooves on its outer surface, and rolling elements that can roll along the rolling element grooves of the outer ring and the rolling element grooves of the inner ring. The outer ring of the ball spline portion and the inner ring of the bearing portion are formed integrally. Multiple teeth are formed radially on the surface of the first face gear that faces the second face gear. Multiple teeth are formed radially on the surface of the second face gear that faces the first face gear. A speed reduction or speed increase device in which the teeth of the first face gear and the teeth of the second face gear mesh directly. [Claim 6] The reduction or speed increase device according to claim 5, characterized in that the output section is integrally formed with the outer ring of the ball spline section and the inner ring of the bearing section. [Claim 7] The reduction or speed increase device according to claim 5 or 6, characterized in that a flange having a through hole for fastening the outer ring of the bearing portion to the housing of the reduction or speed increase device is integrally formed thereon. [Claim 8] The teeth of the first face gear are inclined such that the apex of the conical surface on which the tooth trace is formed is axially closer to the bearing portion than the tooth surface of the first face gear. The reduction or speed increase device according to claim 5 or 6, characterized in that the teeth of the second face gear are inclined such that the apex of the conical surface on which the tooth traces are formed is closer in the axial direction to the bearing portion than the tooth surface of the second face gear. [Claim 9] In a speed reduction or acceleration device in which a first face gear is tilted to mesh with a second face gear, and the first face gear is oscillated so that the meshing portion moves in the circumferential direction, The first face gear is provided with a ball spline section that allows it to be tilted, The ball spline portion comprises an outer ring, an inner ring, balls that can roll along the ball grooves of the outer ring and the ball grooves of the inner ring, and a retainer in which pockets are formed into which the balls are incorporated. The first face gear and the inner ring of the ball spline portion are integrally formed, A speed reducer or speed increaser having a notch formed in the retainer that allows the inner ring to be inserted into the retainer with the axis of the retainer and the axis of the inner ring aligned, thereby allowing the protrusions between the ball grooves of the inner ring to pass through.

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