JP2006077833A - Rolling ball type differential reduction gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling ball type differential reduction gear with a plurality of rolling balls held between the opposed faces of a pair of plates for meshing with annular toothed portions formed on the opposed faces, respectively, having a higher degree of freedom in setting a reduction ratio while reducing its cost by giving a certain degree of freedom to the positions of the rolling balls between the pair of plates. <P>SOLUTION: On both plates 7, 8; 7, 9, circular recessed portions 23, 24; 28, 29 are provided with mutually offset axial lines C2, C1 as centers. On the inner periphery sides of one recessed portions 23, 28, annular toothed portions 21, 26 are formed along an epicycloid curve with their cross section shaped as quarter circles. On the outer periphery sides of the other recessed portions 24, 29, annular toothed portions 22, 27 are formed along a hypocycloid curve. Lines L1-L4 connecting the centers of the rolling balls 10, 11 to contact points of the rolling balls 10, 11 with the annular toothed portions 21, 22; 26, 27 obliquely intersecting the axial lines C2, C1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  According to the present invention, a pair of plates each having an annular tooth portion along an epicycloid curve and a hypocycloid curve centered on axes offset from each other are respectively formed on opposing surfaces, and meshed with the annular tooth portion. The present invention relates to a rolling ball type differential speed reducer comprising at least a plurality of rolling balls sandwiched between the two plates.

Such rolling ball type differential reduction gears are already known from, for example, Patent Document 1 and Patent Document 2.
JP-A-5-231490 Japanese Patent No. 2966536

  In the rolling ball type speed reducer disclosed in Patent Documents 1 and 2, the annular tooth portion is formed as an annular groove having a semicircular cross section with the inner and outer circumferences along the epicycloid curve and the hypocycloid curve, The position of the rolling ball between the pair of plates is strictly determined, and the dimensional accuracy and mounting position accuracy of each component must be increased, which inevitably increases the cost. Further, in the above-described conventional one, the difference in the number of teeth of the annular tooth portions corresponding to each other is limited to “2”, and the degree of freedom in setting the reduction ratio is limited.

  The present invention has been made in view of such circumstances. The present invention has been made to reduce the cost by allowing a certain degree of freedom to the position of the rolling ball between the pair of plates and to freely set the reduction ratio. An object of the present invention is to provide a rolling ball type speed reducer having an increased degree.

  In order to achieve the above object, the present invention provides a pair of plates each having an annular tooth portion along an epicycloid curve and a hypocycloid curve centering on mutually offset axes, respectively, and the annular A rolling ball type differential reduction gear comprising at least a plurality of rolling balls sandwiched between the plates so as to mesh with a tooth portion, wherein the plates are centered on axes that are offset from each other. Circular recesses are provided, and an annular tooth portion along the epicycloid curve is formed on the inner peripheral side of one concave portion with a quadrangular cross-sectional shape, and the hypocycloid curve is formed on the outer peripheral side of the other concave portion. And a straight line connecting the center of the rolling balls and the point of contact of the rolling balls with the annular tooth portion is the axis. Characterized in that it is set so as to intersect obliquely to.

  According to the above configuration of the present invention, the annular tooth portion having the quadrangular cross section is formed on the inner peripheral side of the circular concave portion on one plate side and on the outer peripheral side of the circular concave portion on the other plate side, respectively. Since the rolling ball passes through the center thereof and contacts the annular tooth portion on a straight line that obliquely intersects with the axis of both plates, the rolling ball has an outer circumferential side or inner circumferential surface within the circular recess. Although it is limited to the side, it can exist freely to some extent, and although the backlash slightly increases, it is possible to set the single unit dimensional accuracy and mounting position accuracy of each part relatively low, and the cost The difference in the number of teeth between the two annular teeth can be set to “2” or more by allowing a decrease in the meshing rate between the rolling balls and the annular teeth. Ratio setting It is possible to increase the degree of freedom of.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 3 show an embodiment of the present invention, FIG. 1 is a longitudinal sectional view of a rolling ball type speed reducer, and FIG. 2 is a cross-sectional view of FIG. 1 2-2 with the first retainer omitted. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1 with the second retainer omitted.

  First, in FIG. 1, this rolling ball type speed reducer is provided between an input shaft 5 and an output shaft 6 that are arranged coaxially so as to rotate around an axis, and at least a pair of plates 7, 8 facing each other. : 7,9 and a plurality of rolling balls 10, ..., 11 ... sandwiched between the paired plates 7,8: 7,9. In this embodiment, the input and output shafts 5,6 are provided. A disc-shaped input plate 7 connected to the input shaft 5 having a second axis C2 set eccentrically by an eccentric amount e from the first axis C1 which is the first axis C1; A fixed plate 8 which is fixedly disposed oppositely, a disk-shaped output plate 9 which is connected to the output shaft 6 so as not to be relatively rotatable and faces the other surface of the input plate 7, and a ring plate-shaped first retainer. 12 and the input plate 7 and the fixing plate The plurality of first rolling balls 10 sandwiched between the opposing surfaces of the second plate 8 and the plurality of second rolling balls 10 held between the opposing surfaces of the input plate 7 and the output plate 9 held by the ring plate-like second retainer 13. And rolling balls 11.

  The fixed plate 8 constitutes an end wall of the casing 14 having a bottomed cylindrical shape, and a circular opening 15 into which the end of the input shaft 5 is inserted coaxially is formed at the center of the fixed plate 8. Is provided. Further, the end of the input shaft 5 has a concentric cylindrical portion 16a that coaxially surrounds the input shaft 5, and a circular outer periphery centered on a second axis C2 that is eccentric from the axis of the input shaft 5 by an eccentric amount e. A cylindrical member 16 integrally having an eccentric cylindrical portion 16b is coupled by welding or the like, and a ball bearing 17 is interposed between the inner periphery of the opening 15 and the concentric cylindrical portion 16a of the cylindrical member 16.

  The input plate 7 is formed in a ring plate shape centered on the second axis C2, and a ball bearing 18 is interposed between the inner periphery of the input plate 7 and the outer periphery of the eccentric cylindrical portion 16b. That is, the input plate 7 is supported by the eccentric cylindrical portion 16b so as to be able to rotate around the second axis C2.

  The output shaft 6 is coaxially fitted and fixed to the other end portion of the connecting shaft 19 in which one end portion is inserted into the eccentric cylindrical portion 16b so as to face and close to the input shaft 5. The output plate 9 has a cylindrical portion 9a that coaxially surrounds the connecting shaft 19 on the inner periphery, and the cylindrical portion 9a is fixed to the connecting shaft 19 so that the output plate 9 6 is connected to be non-rotatable. In addition, the inner periphery of the eccentric cylindrical portion 16b in the cylindrical member 16 is formed in a circle around the axis of the output shaft 6, and a ball bearing is provided between the outer periphery of the cylindrical portion 9a and the inner periphery of the eccentric cylindrical portion 16b. 20 is interposed.

  Referring also to FIG. 2, a fixed plate 8 is disposed on one surface of the input plate 7 that can rotate around the second axis C <b> 2, and the input plate 7 faces the fixed plate 8. The first annular tooth portion 21 along the epicycloid curve is formed around the second axis C2, and the second annular tooth portion 22 along the hypocycloid curve is formed on the surface of the fixed plate 8 facing the input plate 7. It is formed around the first axis C1.

  A circular first concave portion 23 centered on the second axis C2 is provided on the outer peripheral portion of the surface of the input plate 7 facing the fixed plate 8 so as to open outward. On the inner peripheral side, the first annular tooth portion 21 along the epicycloid curve is formed with a quadrangular cross-sectional shape. In addition, a circular second recess 24 centered on the first axis C1 is provided on the surface of the fixed plate 8 facing the input plate 7, and the hypocycloid curve is formed on the outer peripheral side of the second recess 24. The 2nd annular tooth part 22 to follow is formed so that the cross-sectional shape may be a quarter circle.

  Incidentally, the number of teeth n1 of the first annular tooth portion 21 on the input plate 7 side is, for example, 20 in this embodiment, and the number of teeth n2 of the second annular tooth portion 22 on the fixed plate 8 side is on the input plate 7 side. More than the number n1 of teeth of the first annular tooth portion 21, for example, 22.

  The first rolling balls 10 are sandwiched between the input plate 7 and the fixed plate 8 so as to mesh with the first and second annular teeth 21, 22, and the second rolling ball 10. A number smaller than the number of teeth n2 of the annular tooth portion 22 and larger than the number of teeth n1 of the first annular tooth portion 21 on the input plate 7 side, for example, 21 first rolling balls 10 are fixed to the input plate 7. It is sandwiched between the plates 8.

  These first rolling balls 10 are held by a first retainer 12 interposed between the input plate 7 and the fixed plate 8, and the first retainer 12 has first and second axes C1, C2. A first rolling ball is formed in a plurality of first holding holes 25, which are formed in a ring plate shape centering on a third axis C3 disposed therebetween and provided at equal intervals in the circumferential direction in the first retainer 12. 10 are inserted and held.

  Moreover, the straight lines L1 and L2 connecting the centers of the first rolling balls 10 and the contact points of the first rolling balls 10 to the first and second annular teeth 21 and 22 are input plates 7. The axis of the fixed plate 8, that is, the second axis C2, and the first axis C1, which is the axis of the input and output shafts 5 and 6, are set so as to obliquely intersect.

  Referring also to FIG. 3, the input plate 7 that can rotate around the second axis C <b> 2 and the output plate 9 that rotates together with the output shaft 6 are relatively rotated around the offset axes C <b> 2 and C <b> 1. The third annular tooth portion 26 along the epicycloid curve is formed around the second axis C2 on the opposite surface of the input plate 7 to the output plate 9, and the input of the output plate 9 A fourth annular tooth portion 27 along the hypocycloid curve is formed on the surface facing the plate 7 with the first axis C1 as the center.

  A circular third recess 28 centered on the second axis C2 is provided on the outer peripheral portion of the surface of the input plate 7 facing the output plate 9 so as to open outward. On the inner peripheral side, a third annular tooth portion 26 along the epicycloid curve is formed with a quadrangular cross-sectional shape. Further, a circular fourth recess 29 centered on the first axis C1 is provided on the surface of the output plate 9 facing the input plate 7, and the hypocycloid curve is formed on the outer peripheral side of the fourth recess 29. The 4th annular tooth part 27 to follow is formed in the cross-sectional shape as a quarter circle.

  By the way, the number of teeth n3 of the third annular tooth portion 26 on the input plate 7 side is, for example, 18 in this embodiment, and the number of teeth n4 of the fourth annular tooth portion 27 on the output plate 9 side is on the input plate 7 side. More than the number of teeth n3 of the third annular tooth portion 26, for example, 20.

  The second rolling balls 11 are sandwiched between the input plate 7 and the output plate 9 so as to mesh with the third and fourth annular teeth 26, 27, and are arranged on the output plate 9 side. A number smaller than the number of teeth n4 of the annular tooth portion 27 and larger than the number of teeth n3 of the third annular tooth portion 26 on the input plate 7 side, for example, 19 second rolling balls 11. It is sandwiched between the plates 9.

  These second rolling balls 11 are held by a second retainer 13 interposed between the input plate 7 and the output plate 9, and the second retainer 13 is centered on the third axis C3. The second rolling balls 11 are inserted and held in a plurality of second holding holes 30 which are formed in a ring plate shape and are provided in the second retainer 13 at equal intervals in the circumferential direction.

  Moreover, the straight lines L3 and L4 connecting the centers of the second rolling balls 11 and the contact points of the second rolling balls 11 with the third and fourth annular teeth 26 and 27 are input plates 7. The axis of the output plate 9, that is, the second axis C2, and the axis of the input and output shafts 5, 6, that is, the first axis C1, are set so as to obliquely intersect.

  In such a rolling ball type differential speed reducer, when the input shaft 5 rotates around the first axis C1 and the input plate 7 revolves around the first axis C1, the first and second annular teeth 21 , 22, the input plate 7 rotates about the second axis C <b> 2 by the rolling of the first rolling balls 10. Due to the rotation of the input plate 7, the second rolling balls 11 meshed with the third and fourth annular teeth 26, 27 roll, whereby the output plate 9 rotates around the first axis C1. Will be driven.

  Thus, the reduction ratio ε between the input shaft 5 and the output shaft 6 is ε = 1 − {(n2 × n3) / (n1 × n4)}. In this embodiment, n1 = 20, n2 = 22, Since n3 = 18 and n4 = 20, the reduction ratio ε is 0.01.

  Next, the operation of this embodiment will be described. On the surface of the input plate 7 facing the fixed plate 8 and the output plate 9, circular first and third recesses 23 and 28 centering on the second axis C2 are provided. The first and third annular tooth portions 21 and 26 along the epicycloid curve are provided on the inner peripheral side of the first and third recesses 23 and 28 in a quadrant shape. A circular plate centered on the first axis C1 that is offset from the second axis C2 is formed on the opposing surface of the fixed plate 8 and the output plate 9 to the input plate 7 so as to have a cross section. The second and fourth recesses 24 and 29 are provided, and the second and fourth annular tooth portions 22 and 27 along the hypocycloid curve are arranged on the outer circumferential side of the second and fourth recesses 24 and 29 in a quadrant shape. Have a face Unishi are formed Te. Further, the center of the first rolling balls 10 sandwiched between the input plate 7 and the fixed plate 8 so as to mesh with the first and second annular teeth 23, 24, and the first rolling balls 10 ... The straight lines L1 and L2 connecting the contact points to the first and second annular teeth 21 and 22 are set so as to obliquely intersect the second and first axes C2 and C1, and the third and second The centers of the second rolling balls 11 sandwiched between the input plate 7 and the output plate 9 so as to mesh with the four annular teeth 26, 27, and the first and second of the second rolling balls 11. Straight lines L3 and L4 connecting the contact points to the annular teeth 21 and 22 are set so as to obliquely intersect the second and first axes C2 and C1.

  Therefore, the first and second rolling balls 10..., 11... Are limited to the outer peripheral side or the inner peripheral side in the first and second concave portions 23 and 24 and in the third and fourth concave portions 28 and 29. It is possible for some to exist to some extent. For this reason, although the backlash slightly increases, it is possible to reduce the cost by making it possible to set the single unit dimensional accuracy and mounting position accuracy of each component relatively low. If the reduction of the meshing rate between the first and second rolling balls 10... 11 and the first to fourth annular teeth 21, 22; It is also possible to set the difference in the number of teeth of the parts 21, 22; 26, 27 to “2” or more, and the degree of freedom in setting the reduction ratio can be increased.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

It is a longitudinal cross-sectional view of a rolling ball type reduction gear. It is sectional drawing which follows the 2-2 line | wire of FIG. 1 in the state which abbreviate | omitted the 1st retainer. It is sectional drawing which follows the 3-3 line | wire of FIG. 1 in the state which abbreviate | omitted the 2nd retainer.

Explanation of symbols

7, 8, 9 ... plates 10, 11 ... rolling balls 21, 22, 26, 27 ... annular teeth 23, 24, 28, 29 ... recesses C1, C2 ... axis L1 ~ L4 ... straight line

Claims (1)

  A pair of plates (7,8; 7,7) in which annular tooth portions (21, 22; 26, 27) along an epicycloid curve and a hypocycloid curve centering on mutually offset axes are respectively formed on mutually facing surfaces. 9) and a plurality of rolling balls (10, 11) sandwiched between the plates (7, 8; 7, 9) so as to mesh with the annular teeth (21, 22; 26, 27). In the rolling ball type differential reduction gear including at least, the two plates (7, 8; 7, 9) have circular recesses (23, 23) centered on the axes (C2, C1) that are offset from each other. , 24; 28, 29) are provided, and annular teeth (21, 26) are formed on the inner peripheral side of one of the recesses (23, 28) with the cross-sectional shape being a semicircular shape along the epicycloid curve. The other concave An annular tooth portion (22, 27) along the hypocycloid curve is formed on the outer peripheral side of (24, 29), the center of the rolling ball (10, 11), and the rolling balls (10, 11). The straight lines (L1 to L4) connecting the contact points to the annular tooth portions (21, 22; 26, 27) are set so as to obliquely intersect the axis (C2, C1). A rolling ball type differential speed reducer.

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