JP2022127926A - Differential speed reducer - Google Patents

Abstract

To provide a differential speed reducer which enables improvement of rigidity.SOLUTION: A differential speed reducer 1 includes a reaction force plate 30 which converts sun-and-planet motion of an external gear 2 into rotational motion which is coaxial with a center axis C0. A reinforcement plate 40 which overlaps with at least one of second slide parts 34a, 34b or third slide parts 34c, 34d when viewed from a direction of the center axis C0 is integrally fastened to a side surface of the reaction force plate 30 to reduce strain of the reaction force plate 30 caused when torque is exerted on an area between input and output sides of the differential speed reducer 1 and thereby improve rigidity of the differential speed reducer 1.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a differential speed reducer capable of increasing rigidity.

Conventionally, in Patent Document 1, an input shaft provided with an internal gear and two eccentric portions whose eccentric directions are shifted by 180 degrees from each other, and an external input shaft arranged at each eccentric portion and internally fitted to the internal gear Disclosed is a gear transmission including a tooth gear, an output body arranged on the outer side of each external gear in the axial direction, and a cross-shaped conversion body arranged between the output body and the external gear. It is

Each output has a stop with a guide, which slides in a lateral guideway of the converter and is laterally free with respect to the axis of rotation of the output. Each external gear also has a stop with a guide, which slides in a longitudinal guideway of the converter and is longitudinally free with respect to the axis of rotation of the output. ing. In other words, the converter performs the same function as a so-called universal joint that converts the eccentric rotary motion of the external gear into rotary motion about the axis of the output body.

Japanese Patent Publication No. 9-508957

In the gear transmission of Patent Document 1, since the converting body is a thin plate, the converting body has a great influence on the rigidity of the gear transmission. That is, when torque is applied between the input and output of the gear transmission, the conversion body is distorted and the rigidity of the entire gear transmission is lowered. Although it is possible to increase the rigidity by increasing the thickness of the converter, the overall thickness of the gear transmission is increased accordingly, and the weight is also increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a differential speed reducer capable of reducing the distortion of a converting body and increasing the rigidity thereof with a simple structure.

In order to achieve this object, the differential speed reducer according to claim 1 includes an internal gear, and is arranged so as to pass through the internal gear coaxially with the internal gear. an input shaft having an eccentric portion that is eccentric at the bottom; an external gear that is mounted on the eccentric portion, internally contacts and meshes with the internal gear, and has a first sliding portion; and having a second sliding portion slidable with the first sliding portion via a first sliding member, the planetary motion of the external gear being rotated coaxially with the central axis. A plate having a conversion member for conversion and a fourth sliding portion disposed outside the conversion member and slidable with a third sliding portion provided on the conversion member via a second sliding member and a reinforcing member arranged at a position overlapping at least one of the second sliding portion and the third sliding portion when viewed from the central axis direction and fixed to a side surface of the conversion member. It is characterized by
Moreover, the differential speed reducer according to claim 2 is the differential speed reducer according to claim 1, and further characterized in that the reinforcing member has a hollow disk shape.
Further, the differential speed reducer according to claim 3 is the differential speed reducer according to claim 1 or 2, wherein the reinforcing member is made of a material different from that of the conversion member. It is characterized.
Further, the differential speed reducer according to claim 4 is the differential speed reducer according to any one of claims 1 to 3, and further, the reinforcing member and the conversion member are fastened by countersunk screws. It is characterized by being

According to the differential speed reducer of claim 1, the distortion of the conversion member can be reduced by the reinforcing member fixed to the side surface of the conversion member. In particular, by increasing the strength near the second sliding portion or the third sliding portion, the rigidity of the differential speed reducer can be effectively increased.
Further, according to the differential speed reducer of claim 2, since the reinforcing member is disc-shaped, it is difficult to be distorted in the circumferential direction. Therefore, the rigidity of the differential speed reducer can be further increased. In addition, it is easy to manufacture the reinforcing member.
Further, according to the differential speed reducer of claim 3, since the material of the reinforcing member is different from that of the conversion member, it is possible to use an inexpensive material for the reinforcing member. For example, the processing cost of the reinforcing member can be reduced by using a material that can be mass-produced at low cost by metal press processing or the like.
Moreover, according to the differential reduction gear of Claim 4, the reinforcement member and the conversion member are fastened by the countersunk screw. Therefore, the reinforcing member and the conversion member are not displaced in the circumferential direction due to the tapered shape of the countersunk screw head, and the rigidity of the differential speed reducer can be further increased.

1 is a central vertical cross-sectional view of a differential speed reducer that is an embodiment of the present invention; FIG. It is an exploded perspective view of a differential speed reducer. FIG. 4 is a front view of the differential speed reducer from which the bracket and the reinforcing plate are removed; It is a front view of the state where the bracket was removed from the differential speed reducer.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a central longitudinal sectional view of the differential speed reducer 1. FIG. FIG. 2 is an exploded perspective view of the differential speed reducer 1. FIG. The differential speed reducer 1 of this embodiment is used, for example, in joints of industrial robots.

The differential speed reducer 1 is an eccentric oscillation type speed reducer in which an external gear 2 meshes with an internal gear 3 and rotates eccentrically. The differential speed reducer 1 includes an external gear 2 , an internal gear 3 , a case 4 and an input shaft 5 .

The case 4 includes a cylindrical main case 6, an input side (right side in FIG. 1) of the main case 6, and a contact plate 7 having substantially the same circular outer shape as the main case 6, and a contact plate 7 sandwiched therebetween. is arranged on the side opposite to the main case 6, and is composed of a bracket 8 whose outer shape is substantially the same as the main case 6 and the support plate 7, and the main case 6, the support plate 7, and the bracket 8 are located on the bracket 8 side. are integrally fastened by a plurality of bolts 9, 9 . The main case 6 has a raceway surface for the cross rollers 11 formed on its inner peripheral surface. That is, the main case 6 also serves as the outer ring of the cross roller bearing 12 . A plurality of through holes 13 are formed in the main case 6, the contact plate 7, and the bracket 8 at positions avoiding the plurality of bolts 9, 9, . . .

A cylindrical internal gear 3 is arranged radially inside the main case 6 . The internal gear 3 has a track surface of a cross roller 11 formed on its outer peripheral surface, and is rotatably supported on the main case 6 via the cross roller 11 . The cross roller 11 is arranged radially outside the internal gear 3 at a position overlapping the internal teeth when viewed in a direction perpendicular to the central axis C0. That is, the internal gear 3 also serves as the inner ring of the cross roller bearing 12 . An output portion 15 having a plurality of bolt holes 14 is formed on the end face of the internal gear 3 on the output side (left side in FIG. 1). Either one of the case 4 (through hole 13) or the output portion 15 (bolt hole 14) is used as a fixed side, and the other is used as an output side to be connected to the counterpart device.

No internal teeth are formed on the inner peripheral surface of the internal gear 3 on the output portion 15 side, and a disc-shaped bearing housing 16 is fixed by press fitting. An annular recessed groove 17 centered on the central axis C0 is formed over the entire circumference of the input-side end surface of the internal gear 3 at a position facing a reaction plate 30, which will be described later.

A hollow cylindrical input shaft 5 is arranged inside the external gear 2 . The input shaft 5 has a cylindrical shape provided with a circular hollow portion 18 centered on the central axis C0 for passing wiring, a drive shaft, and the like. A central axis C0 of the input shaft 5 is coaxial with the axis of the internal gear 3 .

At both ends of the input shaft 5, support portions 21 for disposing the first ball bearing 20a and the second ball bearing 20b are formed. The input shaft 5 is rotatably supported on the inner peripheral surface of the bracket 8 via a first ball bearing 20a, and rotatably supported on the inner peripheral surface of the bearing housing 16 via a second ball bearing 20b. ing. Between the support portions 21, 21 of the input shaft 5, an eccentric portion 22 having a cylindrical surface with an outer diameter larger than that of the support portion 21 is formed around an eccentric axis C1 offset from the central axis C0 by an amount of eccentricity δ1. It is

A single external gear 2 is rotatably supported on the radially outer side of the eccentric portion 22 via a plurality of needle rollers 23 each having a circular cross section and arranged along the entire circumference in the circumferential direction. ing. A needle bearing that supports the external gear 2 is formed by combining 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 is arranged facing the same direction as the central axis C0, and the axial length of each needle roller 23 is substantially the same as the axial width of the eccentric portion 22 . Axial movement of each needle roller 23 is restricted by the side surfaces of the first ball bearing 20a and the second ball bearing 20b.

FIG. 3 is a front view of the differential speed reducer 1 as viewed from the input side of the central axis C0, and shows a state in which the bracket 8 and a later-described reinforcing plate 40 are removed from the differential speed reducer 1. FIG. FIG. 4 is a front view of the differential speed reducer 1 as seen from the input side of the central axis C0, showing a state in which the bracket 8 has been removed from the differential speed reducer 1. FIG. FIG. 4 shows the fixed state of the reinforcing plate 40 .

Four bolt holes 24 are formed in the end face of the input shaft 5 on the input side. The bolt holes 24 are circumferentially formed at equal intervals and have a shape that allows connection of a drive shaft (not shown). Circular through holes 25 are formed at eight locations in the input shaft 5 from the end face on the input side to the output side. Each through hole 25 is circular, and is formed at a position avoiding the bolt hole 24 on the side of the eccentric axis C1 (upper side in FIG. 4) with respect to the central axis C0. The through hole 25 is not formed on the opposite side of the central axis C0 to the eccentric axis C1 (lower side in FIG. 4). The through-hole 25 functions as a lightening portion, and can improve an imbalance in rotation balance caused by the eccentricity of the input shaft 5 and the external gear 2 when the differential speed reducer 1 is driven.

The external gear 2 has a number of teeth slightly smaller than the number of teeth of the internal gear 3 and contacts the internal gear 3 at an eccentric position. Two angular contact blocks 26 a and 26 b are formed integrally with the external gear 2 on the input side surface of the external gear 2 . First sliding portions 27a and 27b are formed on both sides of the external gear 2 in the circumferential direction of the contact blocks 26a and 26b. Each contact block 26a, 26b is formed such that the first sliding portions 27a, 27b are parallel to each other. A plurality of circular recesses 28 are formed in the external gear 2 at positions avoiding the contact blocks 26a and 26b on the side surface (input side) facing the reaction force plate 30, which will be described later. Most of the recesses 28 are formed at positions overlapping the reaction plate 30 when viewed from the direction of the central axis C0. Also, the concave portion 28 is filled with a lubricant.

A thin disk-shaped reaction force plate 30 is arranged radially inside the contact plate 7 . Two cutouts 33a and 33b are formed on the inner peripheral side of the reaction plate 30 at positions symmetrical with each other by 180 degrees. Two notches 33c and 33d are formed. One pair of cutouts 33a and 33b has parallel second sliding portions 34a and 34b on both side surfaces in the circumferential direction, respectively. The other pair of cutouts 33c and 33d has parallel third sliding portions 34c and 34d on both side surfaces in the circumferential direction, respectively. One pair of cutouts 33a and 33b and the other pair of cutouts 33c and 33d are formed so that the second sliding portions 34a and 34b and the third sliding portions 34c and 34d are perpendicular to each other. ing. Between the first sliding portions 27a, 27b and the second sliding portions 34a, 34b, two first needle rollers 35a each having a circular cross section are arranged, and one pair of cutouts is provided. 33a and 33b are slidable with first sliding portions 27a and 27b of contact blocks 26a and 26b via first needle rollers 35a. The reaction plate 30 can slide in the direction of the second sliding portions 34a and 34b (horizontal direction in FIG. 3) with respect to the external gear 2 by means of the first needle rollers 35a. In addition, the external gear 2 and the reaction plate 30 are designed such that their side surfaces slide.

Twelve screw holes 36 are formed in the side surface of the reaction plate 30 . Some of the screw holes 36 are formed at positions sandwiching the cutouts 33a, 33b, 33c, and 33d from both sides. That is, the screw holes 36 are formed near the second sliding portions 34a, 34b and the third sliding portions 34c, 34d.

The support plate 7 has an annular shape, and on its inner peripheral surface, protrusions 38a and 38b having fourth sliding portions 37a and 37b parallel to and facing the third sliding portions 34c and 34d are formed in the inner peripheral direction. is formed so as to protrude toward the Between the third sliding portions 34c, 34d and the fourth sliding portions 37a, 37b, two second needle rollers 35b having the same shape as the first needle rollers 35a are arranged. The reaction plate 30 can slide in the direction of the third sliding portions 34c and 34d (vertical direction in FIG. 3) with respect to the contact plate 7 via the second needle roller 35b.

The recessed groove 17 formed on the side surface of the internal gear 3 is positioned so that at least a portion thereof overlaps with the reaction plate 30, the first needle roller 35a, and the second needle roller 35b when viewed from the direction of the central axis C0. . The concave groove 17 is filled with a lubricant, and has a structure in which the lubricant is easily supplied to the reaction plate 30, the first needle roller 35a, and the second needle roller 35b.

A thin disk-shaped reinforcement plate 40 having substantially the same outer shape as the reaction plate 30 is fixed to a side surface of the reaction plate 30 opposite to the external gear 2 . Twelve through holes are formed in the reinforcement plate 40 at positions corresponding to the screw holes 36 formed in the reaction plate 30 . The reinforcing plate 40 is integrally connected to the reaction plate 30 by countersunk screws 41 fastened to screw holes 36 through respective through holes. The through hole is formed in a tapered shape so as to accommodate the head of the countersunk screw 41 and suppresses the amount of projection of the head of the countersunk screw 41 from the end surface of the reinforcing plate 40 . The reaction plate 30 is arranged so as to overlap the second sliding portions 34a, 34b (notches 33a, 33b) and the third sliding portions 34c, 34d (notches 33c, 33d) when viewed from the direction of the central axis C0. are placed.

In this embodiment, the reaction plate 30 is made of, for example, carbon steel (SC material), chromium molybdenum steel (SCM material), nickel chromium molybdenum steel (SNCM material), high carbon chromium bearing steel (SUJ material), or the like. It is used and adjusted to high strength by heat treatment. On the other hand, the reinforcing plate 40 is made of, for example, a cold-rolled steel plate (SPC material), a stainless steel plate (SUS material), or the like, and is formed by metal press working. Also, if a material with a higher Young's modulus is used for the reinforcing plate 40, a model of a differential speed reducer with increased rigidity can be manufactured.

An oil seal 50 is arranged on the output side of the cross roller bearing 12 between the main case 6 and the internal gear 3 . A groove 51 is formed along the entire periphery radially inward of the through hole 13 in the output-side end face of the contact plate 7 , and an O-ring 52 is arranged in the groove 51 . A groove 53 is formed along the entire periphery radially inward of the through hole 13 in the end face of the output side of the bracket 8, and an O-ring 54 is arranged in the groove 53. .

In the differential speed reducer 1 configured as described above, the input shaft 5 is rotated by the power of the drive source (not shown), so that the eccentric portion 22 is eccentrically moved, and the external gear 2 is inscribed in the internal gear 3. eccentrically and rotationally in the state of As a result, the contact blocks 26a and 26b also move eccentrically and rotate, but the contact blocks 26a and 26b slide relative to the reaction plate 30 in the direction of the second sliding portions 34a and 34b (lateral direction). and the reaction plate 30 is arranged so as to slide in the direction (longitudinal direction) of the third sliding portions 34c and 34d with respect to the contact plate 7, so that each sliding portion slides. By transmitting power while moving, only the rotation component of the external gear 2 is taken out via the reaction plate 30 , and the internal gear 3 rotates relative to the case 4 . In other words, the reaction plate 30 has the same function as a so-called universal joint that converts the eccentric rotational motion of the external gear 2 into rotational motion about the central axis C0. Also, the contact plate 7 functions as a carrier that extracts the rotational motion of the external gear 2 relative to the internal gear 3 from the planetary motion of the external gear 2 . At this time, the lubricant filled in the differential speed reducer 1 is sealed by the oil seal 50 , the O-ring 52 and the O-ring 54 .

As described above, according to the differential speed reducer 1 having the above configuration, the distortion of the reaction plate 30 can be reduced by the reinforcement plate 40 fixed to the side surface of the reaction plate 30 . That is, when torque is applied between the input and output of the differential speed reducer 1, the rigidity of the differential speed reducer 1 is can increase

Moreover, since the reinforcement plate 40 is disc-shaped, it is less likely to be distorted in the circumferential direction. Therefore, the rigidity of the differential speed reducer 1 can be further increased. Also, the reinforcing plate 40 can be easily manufactured and manufactured at a low cost.

Further, unlike the material of the reaction plate 30, the reinforcing plate 40 is made of a steel plate. Therefore, the reinforcing plate 40 can be mass-produced at low cost by metal press working or the like.

Further, the reinforcing plate 40 and the reaction plate 30 are fastened with countersunk screws 41 . Since the countersunk screw 41 has a tapered head, the reinforcing plate 40 and the reaction plate 30 are not displaced in the circumferential direction, and the rigidity of the differential speed reducer 1 can be further increased.

As described above, the present embodiment has been described, but the present invention is not limited to the above embodiment, and various modifications are possible. Examples of modifications that can be made to the above embodiment will be described below.

For example, in the present embodiment, the input shaft 5 is hollow and cylindrical with a circular hollow portion 16 centered on the central axis C0, but the input shaft does not have to be hollow. Further, in this embodiment, the first needle rollers 35a are arranged between the first sliding portions 26a, 26b and the second sliding portions 27a, 27b, and the third sliding portions 34c, 34d and the fourth sliding portions 34c, 34d and the fourth sliding portions 34c, 34d. A second needle roller 35b is arranged between the sliding portions 37a and 37b, but a slide bearing may be arranged instead of the needle roller. Further, in this embodiment, the reinforcing plate 40 is a single disc, but a plurality of plates may be prepared and fixed so as to separately cover the notches 33a, 33b, 33c, and 33d.

[Correspondence between configurations of the present invention and the embodiment]
The contact plate 7 of this embodiment is an example of the plate member of the present invention. The reaction force plate 30 of this embodiment is an example of the conversion member of the present invention. The first needle roller 35a of this embodiment is an example of the first sliding member of the present invention. The second needle roller 35b of this embodiment is an example of the second sliding member of the invention. The reinforcing plate 40 of this embodiment is an example of the reinforcing member of the present invention.

Reference Signs List 1 differential speed reducer 2 external gear 3 internal gear 4 case 5 input shaft 7 contact plate 8 bracket 12 cross roller bearing 15 output portion 17 concave groove 22 eccentric portion 26a, 26b contact block 27a, 27b first sliding portion 28 Recess 30 Reaction plate 33a, 33b, 33c, 33d Notch 34a, 34b Second sliding part 34c, 34d Third sliding part 35a First needle roller 35b Second needle roller 36 Screw hole 37a, 37b Fourth sliding Part 40 Reinforcing plate 41 Countersunk screw C0 Central axis C1 Eccentric axis

Claims (4)

an internal gear; and
an input shaft coaxial with the internal gear and disposed so as to pass through the internal gear and having an eccentric portion that is eccentric with respect to a central axis;
an external gear that is mounted on the eccentric portion, internally contacts and meshes with the internal gear, and has a first sliding portion;
a second sliding portion disposed adjacent to the external gear and slidable with the first sliding portion via a first sliding member; a conversion member that converts to rotational motion coaxial with the shaft;
a plate member disposed outside the converting member and having a fourth sliding portion slidable with a third sliding portion provided on the converting member via a second sliding member;
a reinforcing member arranged at a position overlapping at least one of the second sliding portion and the third sliding portion when viewed from the central axis direction and fixed to a side surface of the conversion member. and differential reducer. 2. The differential speed reducer according to claim 1, wherein said reinforcing member has a hollow disk shape. 3. The differential speed reducer according to claim 1, wherein the reinforcing member is made of a material different from that of the converting member. 4. The differential speed reducer according to any one of claims 1 to 3, wherein the reinforcing member and the conversion member are fastened with countersunk screws.

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