JP2022028232A - Differential reducer and crank shaft - Google Patents

Abstract

To provide a differential reducer which enables reduction of processing costs, and to provide a crank shaft.SOLUTION: A differential reducer includes: an internal gear 4; an input shaft 6 which is disposed coaxially with the internal gear 4 so as to penetrate through the internal gear 4 and has an eccentric part 22 which is eccentrically arranged relative to a center axis C0; and an external gear 3 which is installed on the eccentric part 22 and inscribed with the internal gear 4 to engage therewith. On one end surface 24a of the input shaft 6, through holes 26 are formed unevenly distributed to the side of an eccentric direction of the eccentric part 22. Bolt holes 25 are formed at positions avoiding the through holes 26 on the end surface 24a. An inner diameter D1 of the through hole 26 is equivalent to an inner diameter D2 of a prepared hole of the bolt hole 25. Thus, the through hole 26 and the prepared hole of the bolt hole 25 can be processed with the same tool to reduce processing costs.SELECTED DRAWING: Figure 1

Description

The present invention relates to a differential speed reducer and a crankshaft that can reduce processing costs.

Conventionally, Patent Document 1 discloses a differential speed reducer in which a plurality of through holes are formed as lightening portions on the end surface of a support portion that supports a crankshaft to improve the deviation of the rotational balance.

Japanese Unexamined Patent Publication No. 2020-45962

When a through hole is provided as a lightening as in the differential speed reducer of Patent Document 1, conventionally, it is common to efficiently improve the deviation of the rotational balance by providing a hole as large as possible to reduce the weight on the eccentric side. Met. However, in the lightening shape as disclosed in Patent Document 1, it takes time and effort to process.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a differential speed reducer and a crankshaft that can realize a rotation balancing structure at low cost.

In order to achieve this object, the differential speed reducer according to claim 1 is arranged so as to penetrate the internal gear in coaxial with the internal gear and the internal gear, and on its own central axis. An input shaft having an eccentric portion eccentric with respect to a certain input central axis, and an external gear that is externally attached to the eccentric portion and meshes with the internal gear inwardly with the internal gear are provided. On at least one end face, a plurality of lightening holes are formed at positions biased toward the eccentric direction of the eccentric portion, and a plurality of bolt holes are formed at positions on the end face that avoid the lightening holes. The inner diameter of the lightening hole is equal to the inner diameter of the prepared hole of the bolt hole.
The differential speed reducer according to claim 2 is the differential speed reducer according to claim 1, and the lightening hole penetrates the input shaft in the direction of the input center axis. It is characterized by.
The crankshaft according to claim 3 is a crankshaft having an eccentric portion, and at least one end surface of the crankshaft has a plurality of lightening holes at positions biased toward the eccentric direction of the eccentric portion. It is formed, and a plurality of bolt holes are formed at positions on the end surface avoiding the lightening hole, and the inner diameter of the lightening hole is equal to the inner diameter of the pilot hole of the bolt hole. Is.
The crankshaft according to claim 4 is the crankshaft according to claim 3, and further, the lightening hole is characterized in that it penetrates the crankshaft in the axial direction. ..

According to the differential speed reducer according to claim 1, when the lightening hole is machined, the same tool as the tool for drilling the pilot hole of the bolt hole can be used. Therefore, the number of tool changes during machining of the input shaft can be reduced, and the machining cost can be reduced. In the past, in order to enhance the effect of rotational balancing of the differential speed reducer, it was natural to make the lightening hole as large as possible, but in the present invention, the idea of not making the lightening hole large is changed. It is possible to reduce the processing cost.
Further, according to the differential speed reducer according to claim 2, the rotational balance can be further improved by penetrating the lightening hole.
Further, according to the crankshaft according to claim 3, when the lightening hole is machined, the same tool as the tool for drilling the pilot hole of the bolt hole can be used. Therefore, the number of tool changes during the machining of the crankshaft can be reduced, and the machining cost can be reduced. In the past, it was natural to machine the lightening hole as large as possible in order to enhance the effect of balancing the rotation of the crankshaft. Can be reduced.
Further, according to the crankshaft according to claim 4, the rotational balance can be further improved by penetrating the lightening hole.

It is a central vertical sectional view of the differential speed reducer in embodiment of this invention. It is an exploded perspective view of the differential speed reducer in embodiment of this invention. It is the figure which looked at the input axis from the axial direction. It is sectional drawing which follows the AA line of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a central vertical sectional view of the differential speed reducer 1 according to the embodiment of the present invention. FIG. 2 is an exploded perspective view of the differential speed reducer 1 according to the embodiment of the present invention. The differential speed reducer 1 of the present invention is used, for example, for a joint portion of an industrial robot.

The differential speed reducer 1 is an eccentric swing type speed reducer in which the external gear 3 rotates eccentrically while meshing with the internal gear 4. The differential speed reducer 1 includes an external gear 3, an internal gear 4, a case 5, and an input shaft 6.

The case 5 is arranged on the input side (right side in FIG. 1) of the cylindrical main case 7 and the main case 7, and is mainly sandwiched between the backing plate 8 having substantially the same outer shape as the main case 7 and the backing plate 8. The case cover 9 is arranged on the opposite side of the case 7 and has substantially the same outer shape as the main case 7 and the patch plate 8, and the main case 7, the patch plate 8, and the case cover 9 are contacted from the case cover 9 side. It is integrally connected by a plurality of bolts 10, 10 ... That penetrate the plate 8 and are screwed into the main case 7. In the main case 7, the raceway surface of the cross roller 11 is formed on the inner peripheral surface. That is, the main case 7 also serves as the outer ring of the cross roller bearing 12. Further, in the main case 7, the backing plate 8, and the case cover 9, a plurality of through holes 13 are formed at positions avoiding the plurality of bolts 10, 10, ....

A cylindrical internal gear 4 is arranged inside the main case 7 in the radial direction. The external gear 3 has a number of teeth slightly smaller than the number of teeth of the internal gear 4, and is inscribed in the internal gear 4 at an eccentric position. The raceway surface of the cross roller 11 is formed on the outer peripheral surface of the internal gear 4, and is rotatably supported with respect to the main case 7 via the cross roller 11. The cross roller 11 is arranged at a position overlapping the internal teeth on the radial outer side of the internal gear 4 when viewed from a direction perpendicular to the central axis C0. That is, the internal gear 4 also serves as the inner ring of the cross roller bearing 12. In the internal gear 4, a plurality of bolt holes 14 are formed on the end surface on the output side (left side in FIG. 1). Either the case 5 (through hole 13) or the internal gear 4 (bolt hole 14) is set as the fixed side, and the other side is set as the output side and is connected to the other side device. On the inner peripheral surface of the internal gear 4, no internal teeth are formed on the portion on the bolt hole 14 side, and the disk-shaped bearing housing 15 is fixed by press fitting.

A hollow cylindrical input shaft 6 is arranged inside the external gear 3. The input shaft 6 has a cylindrical shape provided with a circular hollow portion 16 centered on the central shaft C0 in order to pass wiring, a drive shaft, and the like. The central axis C0 of the input shaft 6 is coaxial with the axis of the internal gear 4.

Support portions 21 for arranging ball bearings 20 are formed at both ends of the input shaft 6. The input shaft 6 is rotatably supported on the inner peripheral surfaces of the case cover 9 and the bearing housing 15 via two ball bearings 20, 20. An eccentric portion 22 having a cylindrical surface having a larger outer diameter than the support portion 21 is formed between the support portions 21 and 21 on the input shaft 6 with the eccentric shaft C1 offset by the eccentric amount δ1 from the central shaft C0 as the center. Has been done.

A single external gear 3 is rotatably supported on the radial outer side of the eccentric portion 22 via a plurality of needle rollers 23 having a circular cross-sectional shape arranged over the entire circumference in the circumferential direction. ing. A needle bearing that supports the external gear 3 is formed by integrating all the needle rollers 23. That is, the eccentric portion 22 also serves as a raceway surface as an inner ring of the needle bearing. Each needle roller 23 faces in the same direction as the central axis C0, and the axial length of each needle roller 23 is substantially the same as the axial length of the eccentric portion 22. The axial movement of each needle roller 23 is restricted by the side surface of the outer ring of the ball bearing 20.

A plurality of bolt holes 25 are formed on the end surface 24a on the input side of the input shaft 6. FIG. 3 is a view of only the input shaft 6 as viewed from the end surface 24a on the input side. The bolt holes 25 are formed at four locations at equal intervals on the circumference, and have a shape in which a drive shaft (not shown) can be connected.

Further, the input shaft 6 is formed with a plurality of circular through holes 26 from the end surface 24a on the input side to the end surface 24b on the output side. Each through hole 26 is circular, and is formed at eight positions on the eccentric direction side (upper side in FIG. 3) of the eccentric portion 22 with respect to the central axis C0 at positions avoiding the bolt holes 25. The through hole 26 is not formed on the side opposite to the eccentric direction of the eccentric portion 22 (lower side in FIG. 3) with respect to the central axis C0. The through hole 26 penetrates the inside of the support portion 21 and the eccentric portion 22. The through hole 26 functions as a lightening portion, and can improve the deviation of the rotational balance due to the eccentricity of the input shaft 6 and the external gear 3 when the differential speed reducer 1 is driven.

The inner diameter D1 of the through hole 26 is equal to the inner diameter D2 of the prepared hole of the bolt hole 25. In the present embodiment, the size of the bolt hole 25 is M3, and the inner diameter D1 of the through hole 26 and the inner diameter D2 of the prepared hole of the bolt hole 25 are both 2.5 mm.

FIG. 4 is a cross-sectional view taken along the line AA of FIG. 1 and shows a state in which the case cover 9 is removed from the differential speed reducer 1.

Two contact blocks 30a and 30b are integrally formed with the external gear 3 on the side surface of the external gear 3 on the input side. First sliding portions 31a and 31b are formed on both side surfaces of the contact blocks 30a and 30b, respectively. The contact blocks 30a and 30b are formed so that the first sliding portions 31a and 31b are parallel to each other.

A conversion member 32 is arranged inside the backing plate 8 in the radial direction. The conversion member 32 has a plate shape and is slightly thicker than the backing plate 8. The conversion member 32 has a disk shape, and two notches 33a and 33b formed at positions 180 degrees symmetrical with each other on the inner peripheral side and two notches 33c formed at positions 180 degrees symmetrical with each other on the outer peripheral side. , 33d and. One pair of notches 33a and 33b has second sliding portions 34a and 34b parallel to the side surfaces on both sides, respectively. Further, the other pair of notches 33c and 33d have third sliding portions 34c and 34d parallel to the side surfaces on both sides, respectively. One pair of notches 33a and 33b and the other pair of notches 33c and 33d are formed so that the second sliding portions 34a and 34b and the third sliding portions 34c and 34d are orthogonal to each other. ing. Two first needle rollers 35a having a circular cross section are arranged between the first sliding portions 31a and 31b and the second sliding portions 34a and 34b, and one pair of notches is provided. The 33a and 33b are slidable with the first sliding portions 31a and 31b of the contact blocks 30a and 30b via the first needle roller 35a. The conversion member 32 is slidable with respect to the external gear 3 in the direction of the second sliding portions 34a and 34b (lateral direction in FIG. 4) by the first needle roller 35a.

An opening 36 larger than the conversion member 32 is formed on the inner peripheral surface of the backing plate 8, and a fourth sliding portion parallel to the third sliding portions 34c and 34d is formed on the inner peripheral surface of the opening 36. The protrusions 38a and 38b provided with the portions 37a and 37b are formed toward the inner peripheral direction. Two second needle rollers 35b having the same shape as the first needle roller 35a are arranged between the third sliding portions 34c and 34d and the fourth sliding portions 37a and 37b. The conversion member 32 can slide in the direction of the third sliding portions 34c and 34d (vertical direction in FIG. 4) with respect to the contact plate 8 via the second needle roller 35b.

An oil seal 40 is arranged on the output side of the cross roller bearing 12 between the main case 7 and the internal gear 4. A concave groove 41 is formed on the end surface of the backing plate 8 on the output side in the radial direction from the opening 36 over the entire circumference, and an O-ring 42 is arranged in the concave groove 41. Further, a concave groove 43 is formed on the end surface of the case cover 9 on the output side over the entire circumference, and an O-ring 44 is arranged in the concave groove 43.

In the differential speed reducer 1 configured as described above, the input shaft 6 is rotated by the power of a drive source (not shown), so that the eccentric portion 22 moves eccentrically and the external gear 3 is inscribed in the internal gear 4. Eccentricity and rotation movement in this state. Therefore, the contact blocks 30a and 30b also eccentric and rotate, but the contact blocks 30a and 30b slide in the direction (lateral direction) of the second sliding portions 34a and 34b with respect to the conversion member 32. Since the conversion member 32 is arranged so as to slide in the direction (longitudinal direction) of the third sliding portions 34c and 34d with respect to the backing plate 8, each sliding portion slides. While the power is transmitted, only the rotation component of the external gear 3 is taken out via the conversion member 32, and the internal gear 4 rotates relative to the case 5. That is, the conversion member 32 has the same function as a so-called universal joint that converts the eccentric rotational movement of the external gear 3 into a rotational movement about the central axis C0. Further, the backing plate 8 functions as a carrier that extracts a rotational motion that rotates relative to the internal gear 4 from the planetary motion of the external gear 3. At this time, the lubricant filled in the differential speed reducer 1 is sealed by the oil seal 40, the O-ring 42, and the O-ring 44.

As described above, according to the above embodiment, since the inner diameter D1 of the through hole 26 and the inner diameter D2 of the prepared hole of the bolt hole 25 are equal, the through hole 26 and the prepared hole of the bolt hole 25 are machined with the same tool. Can be done. Therefore, the number of tool changes during machining of the input shaft 6 can be reduced, and the machining cost can be reduced.

Further, the through hole 26 penetrates from one end surface 24a of the input shaft 6 toward the other end surface 24b. Therefore, the rotational balance can be further improved.

Although the present embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. An example of changes that can be made to the above embodiment will be described below.

For example, in the present embodiment, the input shaft 6 has a hollow shape and has a cylindrical shape provided with a circular hollow portion 16 centered on the central shaft C0, but the hollow portion does not have to be circular and wiring. It may have a shape necessary for passing a drive shaft or the like. Further, the hollow portion may be provided with a step or the like. Further, the bolt holes 25 may be provided not only on one end face 24a but also on the other end face 24b. Further, in the present embodiment, the first needle roller 35a is arranged between the first sliding portions 31a and 31b and the second sliding portions 34a and 34b, and the third sliding portions 34c and 34d and the third sliding portions 34c and 34d are arranged. Although the second needle roller 35b is arranged between the sliding portions 37a and 37b, a sliding bearing may be arranged instead of the needle roller. Further, although the through hole 26 is provided as a lightening hole in the present embodiment, it may be a blind hole instead of a through hole. Further, the blind holes may be provided on the end faces 24a and 24b on both sides. Further, the lightening hole may be provided coaxially with the bolt hole 25 on the end surface 24b on the opposite side of the bolt hole 25.

[Correspondence of Configuration between the Present Invention and the Embodiment]
The input shaft 6 of the present embodiment is an example of the crankshaft of the present invention. The through hole 26 of the present embodiment is an example of a lightening hole of the present invention. The central axis C0 of the present embodiment is an example of the input central axis of the present invention.

1 Differential reducer 3 External gear 4 Internal gear 6 Input shaft 20 Ball bearing 22 Eccentric part 24a, 24b End face 25 Bolt hole 26 Through hole C0 Central shaft C1 Eccentric shaft D1 Inner diameter of through hole D2 Bolt hole pilot hole Inner diameter

Claims (4)

With internal gears,
An input shaft that is coaxial with the internal gear and is arranged so as to penetrate the internal gear and has an eccentric portion that is eccentric to the input central axis that is its own central axis.
An external gear that is externally attached to the eccentric portion and meshes with the internal gear inwardly.
Equipped with
On at least one end surface of the input shaft, a plurality of lightening holes are formed at positions biased toward the eccentric direction of the eccentric portion.
A plurality of bolt holes are formed on the end face at positions avoiding the lightening holes.
A differential speed reducer characterized in that the inner diameter of the lightening hole is equal to the inner diameter of the prepared hole of the bolt hole. The differential speed reducer according to claim 1, wherein the lightening hole penetrates the input shaft in the direction of the input center axis. A crankshaft with an eccentric part
On at least one end surface of the crankshaft, a plurality of lightening holes are formed at positions biased toward the eccentric direction of the eccentric portion.
A plurality of bolt holes are formed on the end face at positions avoiding the lightening holes.
A crankshaft characterized in that the inner diameter of the lightening hole is equal to the inner diameter of the prepared hole of the bolt hole. The crankshaft according to claim 3, wherein the lightening hole penetrates the crankshaft in the axial direction.

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