Wave gear device and hollow rotating actuator

Patent metadata

Field	Value
Publication number	US-9644727-B2
Application number	US-201314135051-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Mar 19, 2013
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

In a wave gear device, the inner race and the boss are fixed together by a laser welded part formed along the entire periphery thereof. The laser welded part also functions as an oil seal for sealing the inner race and the boss. The boss and the inner race are fixed together in a manner that a required axial length is short, and that machining and assembling steps are reduced. Oil seal members are not required to seal the boss and the inner race.

First claim

The invention claimed is:

1. A wave gear device, comprising:
a rigid internally toothed gear;
a flexible externally toothed gear;
a wave generator;
a bearing for rotatably supporting the flexible externally toothed gear on the rigid internally toothed gear;
a first welded part for fixing a rigid boss in the flexible externally toothed gear to an inner race of the bearing, the first welded part being a full-circle welded part in which the boss and the inner race are sealed together in a liquid-tight state;
a first hollow part extending through the wave generator along the device axial direction;
a second hollow part extending along the device axial direction;
a sleeve disposed passing through the first and second hollow parts; and
a second welded part for fixing the sleeve to the boss, the second welded part being a full-circle welded part in which the sleeve and the boss are sealed together in a liquid-tight state, wherein
the boss of the flexible externally toothed gear is mounted on the inner race center through-hole of the inner race so that an end surface of the boss is exposed outside in a device axial direction through the inner race center through-hole;
the first welded part is formed on an external peripheral surface of the boss on the end surface of the boss; and
the second welded part is formed on the end surface of the boss.

2. The wave gear device according to claim 1 , wherein
the first welded part is a laser welded part.

3. A wave gear device, comprising:
a rigid internally toothed gear;
a flexible externally toothed gear;
a wave generator;
a bearing for rotatably supporting the flexible externally toothed gear on the rigid internally toothed gear;
a first welded part for fixing a rigid boss in the flexible externally toothed gear to an inner race of the bearing, the first welded part being a full-circle welded part in which the boss and the inner race are sealed together in a liquid-tight state;
a device housing; and
an inner race center through-hole formed in the inner race of the bearing, wherein:
the rigid internally toothed gear is fixed to an internal periphery of the device housing;
the flexible externally toothed gear is disposed inside the rigid internally toothed gear and is rotatably supported on the device housing via the bearing;
the wave generator is disposed inside the flexible externally toothed gear;
the boss of the flexible externally toothed gear is mounted on the inner race center through-hole of the inner race so that an end surface of the boss is exposed outside in a device axial direction through the inner race center through-hole; and
the first welded part is formed around an entire periphery in a region between an internal peripheral surface of the inner race and an external peripheral surface of the boss on the end surface of the boss; and wherein

the wave gear device further comprising:
a first hollow part extending through the wave generator along the device axial direction;
a second hollow part extending along the device axial direction;
a sleeve disposed passing through the first and second hollow parts; and
a second welded part for fixing the sleeve to the boss, wherein
the second welded part is a full-circle welded part wherein the sleeve and the boss are sealed together in a liquid-tight state, and is formed on the end surface of the boss.

4. A hollow rotating actuator, comprising:
a motor disposed in an actuator rear side; and
a wave gear device disposed in an actuator front side,
the motor and the wave gear device being disposed coaxially, wherein:
the motor has a motor housing and a hollow motor shaft protruding to the actuator front side from a front end plate of the motor housing;
the wave gear device has a device housing fixed to the motor housing, a bearing, a rigid internally toothed gear fixed to an internal periphery of the device housing, a flexible externally toothed gear disposed inside the rigid internally toothed gear and rotatably supported in the device housing via the bearing, and a wave generator disposed inside the flexible externally toothed gear;
the flexible externally toothed gear has a cylindrical barrel part having an open end in a motor side, a diaphragm extending radially inward from an end of the cylindrical barrel part on a side opposite the open end, an annular rigid boss formed in an internal peripheral edge of the diaphragm, and external teeth formed in an external peripheral surface portion of the cylindrical barrel part on a side of the open end;
a shaft distal end of the hollow motor shaft protruding forward from the front end plate extends into the cylindrical barrel part of the flexible externally toothed gear;
the wave generator has a cylindrical rigid plug fixed to an external periphery of the shaft distal end;
the bearing has an outer race fixed to an end of the device housing on the actuator front end side, and an inner race having a center through-hole in which the boss is mounted;
an annular end surface of the inner race on an actuator front end side and an annular end surface of the boss on the actuator front end side are both exposed in the actuator front end side;
a first laser welded part is formed around an entire periphery between an internal peripheral surface of the inner race and an external peripheral surface of the boss in a region on the actuator front end side;
the boss is fixed to the inner race by the first laser welded part; and
the internal peripheral surface of the inner race and the external peripheral surface of the boss are sealed together in a liquid-tight state by the first laser welded part, and wherein

the hollow rotating actuator further comprising:
a sleeve passing through a hollow part of the hollow motor shaft, a hollow part of the boss, and a hollow part of the wave generator, and extending from an actuator front end surface to an actuator rear end surface; and
a second laser welded part, wherein:
an internal peripheral surface of the sleeve defines an actuator hollow part;
the second laser welded part is formed around an entire periphery between an external peripheral surface of a front end part of the sleeve and an internal peripheral surface of the boss, the front end part being exposed in the actuator front end;
the front end part of the sleeve is fixed to an end surface of the boss by the second laser welded part; and
the external peripheral surface of the front end part and the internal peripheral surface of the boss are sealed together in a liquid-tight state by the second laser welded part.

5. The hollow rotating actuator according to claim 4 , further comprising:
a first oil seal for sealing together a rear end part of the sleeve exposed on the actuator rear end side, and the motor housing rear end plate defining the actuator rear end;
a second oil seal for sealing together the front end plate of the motor housing and the hollow motor shaft; and
a third oil seal for sealing together the rigid plug and the boss.

6. The hollow rotating actuator according to claim 5 , further comprising:
an annular outer seal mount attached to an end surface of the boss on the actuator rear end side; and
a cylindrical inside seal mount extending forward in the actuator front end side along an external peripheral surface of the sleeve from an end surface of the rigid plug on the actuator front end side;
the third oil seal being mounted between the outer seal mount and the inner seal mount.

Assignees

• Harmonic Drive Systems

Inventors

• Yajima Yoshikazu

Classifications

• F16H49/001 Primary

  Wave gearings, e.g. harmonic drive transmissions · CPC title

• H02K11/21

  Devices for sensing speed or position, or actuated thereby (specially adapted for machines having non-mechanical commutating devices H02K29/06, H02K29/14) · CPC title

• H02K5/12

  specially adapted for operating in liquid or gas (combined with cooling arrangements H02K9/00) · CPC title

• Y10T74/19642

  Directly cooperating gears · CPC title

• F16H57/029

  characterised by means for sealing the gearboxes, e.g. to improve airtightness · CPC title