WO2012073596A1

WO2012073596A1 - Gear transmission

Info

Publication number: WO2012073596A1
Application number: PCT/JP2011/073251
Authority: WO
Inventors: 隆成瀬
Original assignee: ナブテスコ株式会社
Priority date: 2010-12-01
Filing date: 2011-10-07
Publication date: 2012-06-07
Also published as: JP2012117609A

Abstract

Provided is a gear transmission which has a through hole and reduces friction between a cable passing through the through hole and an inner surface of the through hole. A gear transmission (100) is provided with cases (21, 25) and an output shaft (16), one end of the output shaft in the direction of a rotational axis is exposed from the case (21), and the other end is covered with the case (25). A through hole (12) passing through the output shaft and the case (25) along the rotational axis is formed. The gear transmission has a first pipe (14) and a second pipe (34) which are coaxially arranged in the through hole. The first pipe is mounted on the output shaft, and the second pipe is mounted on the case. The first pipe has one end which reaches one of openings of the through hole and the other end which is terminated in the through hole. The second pipe has one end which reaches the other of the openings of the through hole and the other end which is terminated in the through hole.

Description

Gear transmission

This application claims priority based on Japanese Patent Application No. 2010-267991 filed on Dec. 1, 2010. The entire contents of that application are incorporated herein by reference. The present invention relates to a gear transmission.

A gear transmission having a through-hole penetrating the entire apparatus along the rotation axis is known. A typical example of a gear transmission having such a through-hole is an eccentric rotation type gear transmission in which a gear ratio between an internal gear and an external gear meshing with the internal gear mainly determines a reduction ratio. The through hole is provided mainly for passing a power cable and a signal cable. One end of the output shaft of the gear transmission is exposed and the other end is covered with a case. One end of the output shaft is exposed for mounting the driven member. The through hole passes through the output shaft and the case. One end of the through hole opens in the output shaft, and the other end opens in the case of the gear transmission.

When the output shaft rotates, there is a risk that the cable passing through the through hole will rub against the inner surface of the through hole. If the cable is rubbed badly, the cable may be damaged. A gear transmission for reducing the friction between the cable and the inner surface of the through hole is disclosed in Japanese Patent Publication No. 2009-115274 (hereinafter referred to as Patent Document 1). In the gear transmission disclosed in Patent Document 1, a freely rotatable cylinder is disposed in the through hole. In the gear transmission of Patent Document 1, the carrier that is rotatably supported by the case corresponds to the output shaft.

In the following description, it is assumed that the case is fixed. However, it should be noted that the technique disclosed in this specification can be applied to a case where the output shaft is fixed to another machine and the case rotates.

Since the cable passing through the through hole is fixed to the case on one side and fixed to the driven member on the other side, the cable may be twisted in the through hole as the output shaft rotates. If it does so, even if the cylinder which can rotate freely is arrange | positioned in a through-hole, there exists a possibility that a cylinder and a cable may rub. The technology disclosed in this specification provides a gear transmission that effectively reduces friction between a cable passing through a through hole and the inner surface of the through hole.

One aspect of the gear transmission disclosed in this specification is as follows. The gear transmission includes an output shaft supported by a case. One end of the output shaft in the rotation axis direction is exposed from the case, and the other end is covered by the case. A through-hole penetrating the output shaft and the case is formed along the rotation axis. The gear transmission further includes two pipes (a first pipe and a second pipe) arranged coaxially in the through hole. The first pipe is attached to the output shaft, and the second pipe is attached to the case. One end of the first pipe reaches one opening of the through hole, and the other end terminates in the through hole. One end of the second pipe reaches the other opening of the through hole, and the other end terminates in the through hole. One opening of the through hole corresponds to the output shaft side opening, and the other opening of the through hole corresponds to the case side opening. A cable is passed through the first pipe and the second pipe.

In the above gear transmission, one end of the through hole is opened in the output shaft, and the other end is opened in the case. A first pipe that rotates together with the opening is arranged in the opening on the output shaft side, and a second pipe that rotates together with the case is arranged in the opening on the case side. On the other hand, the cable does not move relative to the case near the opening on the case side. In the vicinity of the opening on the output shaft side, the cable rotates with the output shaft. Near any opening, the cable and pipe rotate together, so the cable is unlikely to rub against the edge of the opening.

In another aspect of the gear transmission disclosed in this specification, the first pipe and the second pipe partially overlap each other in the through hole, and a seal is provided between the first pipe and the second pipe at the overlapped portion. The material is attached. In the gear transmission device having such a structure, the cable is completely covered and protected by the first and second pipes. Moreover, the sealing material protects the cable from the lubricant in the gear transmission. For example, an oil seal or a labyrinth seal can be applied to the seal material.

A typical example of a gear transmission disclosed in this specification is an eccentric rotation type in which an internal gear is formed inside a case, and an external gear that meshes with the internal gear is supported on an output shaft so as to be eccentrically rotatable. It is a gear transmission. In such a gear transmission, the output shaft that supports the external gear is generally called a carrier. The technology disclosed in this specification is an internal gear eccentric rotation type gear transmission in which the internal gear is supported by the case so as to be eccentrically swingable, and the external gear is also supported by the case so as to be rotatable. Note that it is also possible to apply to a device.

It is sectional drawing of the gear transmission of an Example.

The gear transmission 100 according to the embodiment is a type of gear transmission in which an internal gear is formed inside a case and an external gear rotates eccentrically. Hereinafter, for the sake of simplicity, the gear transmission 100 is simply referred to as the transmission 100. The transmission device 100 is used for a joint of a robot, for example. The case (second case 25) is fixed to the base 23 of the robot, and the arm 17 (driven member) is fixed to the carrier 16 that is an output shaft. The transmission device 100 has a through hole 12 that penetrates the entire transmission device 100 along its rotation axis C1. The through hole 12 is provided mainly for passing the cable 31 from the base of the robot to the arm. The cable 31 is connected from the arm 17 to a driving unit of another arm at the tip or a tool at the tip of the arm, and supplies power or transmits a signal.

First, the structure of the gear group inside the transmission device 100 will be described, and then the structure around the through hole 12 which is the main feature of the transmission device 100 will be described.

The case of the transmission device 100 is divided into a first case 21 and a second case 25. Both are fastened by

bolts

24 and 45. The first case 21 surrounds the carrier 16. The carrier 16 will be described later. An internal gear 47 is formed inside the first case 21. The internal gear 47 is configured by a large number of pins arranged along the circumferential direction on the cylindrical inner surface of the first case 21. Although described in detail later, the second case 25 also plays a role of supporting a motor (not shown).

The first case 21 supports the carrier 16 via an angular bearing 22. The carrier 16 corresponds to the output shaft of the transmission device 100, and one end thereof (the left end in FIG. 1) is exposed. The arm 17 (driven member) is attached to the exposed end. The other end (right end in FIG. 1) of the carrier 16 is covered with the second case 25.

The carrier 16 supports the crankshaft 52 via a taper bearing 53. The crankshaft 52 extends parallel to the rotation axis C1. Two eccentric bodies 51 are fixed near the center of the crankshaft 52, and a spur gear 44 is fixed to one end of the crankshaft 52. Each of the two eccentric bodies 51 supports each of the two external gears 46 via the roller bearing 54. The two external gears 46 mesh with the internal gear 47. When the eccentric body 51 rotates together with the crankshaft 52, the external gear 46 rotates eccentrically while meshing with the internal gear 47. When the external gear 46 goes around the inner circumference of the internal gear 47, the external gear 46 rotates according to the number of teeth difference from the internal gear 47. The carrier 16 rotates with the external gear 46. The gear ratio of the transmission 100 is determined mainly by the difference in the number of teeth between the internal gear 47 and the external gear 46. However, the gear ratio throughout the transmission apparatus 100 also depends on the gear ratios of other gear groups included in the transmission apparatus 100.

The crankshaft 52 is rotated by a motor (not shown). The torque of the motor is transmitted to the spur gear 44 of the crankshaft 52 via the offset shaft 36, the offset shaft gear 43, and the two-stage gear 28. Next, a motor torque transmission mechanism constituted by the offset shaft 36, the offset shaft gear 43, and the two-stage gear 28 will be described.

The two-stage gear 28 will be described. The two-stage gear 28 has a structure in which a large gear 26 and a small gear 27 are connected in the axial direction. The large gear 26 and the small gear 27 are coaxially fixed to each other. The two-stage gear 28 is disposed coaxially with the rotation axis C <b> 1 of the transmission device 100. One end of the two-stage gear 28 is supported by the second case 25 via a ball bearing 32, and the other end is supported by the carrier 16 via a ball bearing 35. Focusing only on the support structure, the case (the first case 21 and the second case 25) supports the carrier 16 via the angular bearing 22, and the carrier 16 of the two-stage gear 28 via the ball bearing 35 is supported. Supports one end. The other end of the two-stage gear 28 is supported by a case (second case 25) via a ball bearing 32.

The small gear 27 of the two-stage gear 28 meshes with the spur gear 44 of the crankshaft 52, and the large gear 26 meshes with the offset shaft gear 43. The offset shaft gear 43 is fixed to one end of the offset shaft 36. A torque of a motor (not shown) is input from the other end of the offset shaft 36. FIG. 1 shows that a spline 37 is formed at the other end of the offset shaft 36. The spline 37 is provided to transmit the torque of the motor. The offset shaft 36 is supported by the second case 25 via a ball bearing 42. The offset shaft 36 is arranged in parallel to the rotation axis C1 of the transmission device 100 but at a distance. The second case 25 supports an offset shaft 36 and a motor (not shown). The transmission device 100 can replace the offset shaft 36 and the motor by exchanging the second case. That is, the transmission device 100 can replace the second case 25 corresponding to the motor unit without disassembling the carrier 16.

The torque (rotation) of the motor is input to the crankshaft 52 via the offset shaft gear 43, the two-stage gear 28 (the large gear 26 and the small gear 27), and the spur gear 44. That is, the gear ratio between the offset shaft gear 43 and the large gear 26, the gear ratio between the large gear 26 and the small gear 27, and the gear ratio between the small gear 27 and the spur gear 44 also contribute to the overall gear ratio of the transmission 100. . However, as described above, the gear ratio of the transmission 100 is mainly governed by the difference in the number of teeth between the internal gear 47 and the external gear 46.

The torque of the motor reaches the crankshaft 52 through the above path, and is further transmitted to the carrier 16 by the relative rotation of the external gear 46 and the internal gear 47. Thus, the torque (rotation) of the motor is amplified (rotation is reduced) and output from the carrier 16 (output shaft).

Reference numeral 18 indicates an oil seal disposed between the inner peripheral surface of the first case 21 and the outer peripheral surface of the carrier 16. Reference numeral 41 indicates the inner peripheral surface of the second case 25 and the outer peripheral surface of the offset shaft 36. The oil seal arrange | positioned between is shown. These oil seals seal the lubricant in the transmission device 100.

Next, the internal structure of the through hole 12 will be described. The transmission device 100 has a through hole 12 extending along the rotation axis C1. The through hole 12 includes a carrier through hole that penetrates the center of the carrier 16 in the axial direction, and a case through hole adjacent to the carrier through hole. In other words, the carrier through hole penetrating the center of the carrier 16 constitutes a part of the through hole 12, and the case through hole constitutes the remaining part of the through hole 12.

A first pipe 14 and a second pipe 34 are arranged in the through hole 12. Both the first pipe 14 and the second pipe 34 are disposed coaxially with the rotation axis C1. The first pipe 14 is attached to a through hole (a part of the through hole 12) of the carrier 16 by a set screw 15. One end (the left end in FIG. 1) of the first pipe 14 reaches the left opening of the through hole 12, and the other end terminates inside the through hole 12. The left opening of the through hole 12 corresponds to the opening of the carrier 16. The second pipe 34 is attached to a through hole (a part of the through hole 12) of the second case 25 by a set screw 33. One end (the right end in FIG. 1) of the second pipe 34 reaches the right opening of the through hole 12, and the other end terminates inside the through hole 12. The right opening of the through hole 12 corresponds to the opening of the second case 25.

The first pipe 14 and the second pipe 34 partially overlap in the through hole. The code | symbol 55 of FIG. 1 has shown the duplication part. The oil seal 13 is disposed between the first pipe 14 and the second pipe 34 in the overlapping portion 55. The oil seal 13 seals the lubricant inside the transmission device 100.

The first pipe 14 rotates with the carrier 16, and the second pipe 34 is fixed to the second case 25. That is, the first pipe 14 and the second pipe 34 rotate relative to each other.

In FIG. 1, a cable 31 passing through the through hole 12 is indicated by a virtual line. The cable 31 rotates together with the arm 17 (carrier 16) on the left side in FIG. 1, and is fixed to the base 23 on the right side in FIG. That is, the cable 31 rotates together with the first pipe 14 fixed to the carrier 16 at the left opening of the through hole 12, and the second pipe 34 fixed to the second case 25 at the right opening of the through hole 12. Does not move with. The cable 31 does not rub against the pipe (the first pipe 14 or the second pipe 34) at both ends of the through hole, and is not easily damaged.

Specific and non-limiting specific examples of the present invention have been described in detail with reference to the drawings. This detailed description is intended merely to present those skilled in the art with the details for practicing the preferred embodiments of the present invention and is not intended to limit the scope of the invention. Also, the disclosed additional features and inventions can be used separately from or in conjunction with other features and inventions to provide further improved gear transmissions.

Further, the combinations of features and steps disclosed in the above detailed description are not indispensable when practicing the present invention in the broadest sense, and are only for explaining representative specific examples of the present invention. It is described. Moreover, various features of the representative embodiments described above, as well as various features of those set forth in the independent and dependent claims, are described herein in providing additional and useful embodiments of the invention. They do not have to be combined in the specific examples or in the order listed.

All features described in this specification and / or claims, apart from the configuration of the features described in the examples and / or claims, are individually disclosed as limitations on the original disclosure and claimed specific matters. And are intended to be disclosed independently of each other. Further, all numerical ranges and group or group descriptions are intended to disclose intermediate configurations thereof as a limitation to the original disclosure and claimed subject matter.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. For example, the technology disclosed in this specification or the drawings can be applied to a gear transmission of a type in which an internal gear swings. The gear transmission disclosed in the present specification may be applied to a machine other than a robot.

The technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

Claims

Case and
One end of the rotation axis direction is exposed from the case, the other end is an output shaft covered by the case,
With
A through hole is formed through the output shaft and the case along the rotation axis.
A first pipe that is disposed in the through hole, has one end reaching one opening of the through hole and the other end terminating in the through hole, and is attached to the output shaft;
A second pipe, which is disposed coaxially with the first pipe in the through hole, has one end reaching the other opening of the through hole and the other end terminating in the through hole, is attached to the case. ,
A gear transmission characterized by that.
The first pipe and the second pipe partially overlap each other in the through hole, and a sealing material is attached between the first pipe and the second pipe at the overlapped portion. The gear transmission as described.
The gear transmission according to claim 1 or 2, wherein an internal gear is formed inside the case, and an external gear meshing with the internal gear is supported on the output shaft so as to be eccentrically rotatable.