Harmonic Drive Systems Inc.

Nissan Motor Company Limited

Hitachi Automotive Systems, Ltd.

Harminic Drive Systems Inc.

Jun Handa

Yoshihide Kiyosawa

Hiroaki Kimura

Noboru Takizawa

Sotaro Miyake

Xin Yue Zhang

XinYue Zhang

Yoshiaki Tanaka

Ryosuke Hiyoshi

Yoshihiko Yamada

Kishiro Nagai

Junichiro Onigata

Nozomu Tanioka

Hideo Yasue

Kazumasa Furuta

Yu Nakagawa

In a strain wave gearing, both of a pulley for transmitting rotation in a direction orthogonal to a rotation central axis and an output shaft are arranged on an axial-direction first side relative to a cup-shaped externally toothed gear. The input shaft, which transmits input rotation from the pulley to the wave generator, functions as a support shaft for both the pulley and the wave generator and is supported at both ends by the first and second bearings. A mechanism for transmitting rotation from the pulley to the wave generator, and a mechanism for supporting the rotation-transmitting mechanism, can be made compact, and support strength can also be ensured.

Strain wave gearing

A strain wave gearing has three components and a temporary-fixing jig, three components being an internally toothed gear, a cup-shaped externally toothed gear, and a wave generator. The temporary-fixing jig is securely fastened to an output shaft fixed to the externally toothed gear by a temporary-fixing bolt and is securely fastened to an input shaft fixed to a cam plate of the wave generator by a temporary-fixing bolt. The temporary-fixing jig engages with the output shaft and the input shaft and maintains the three components in an assembled state. There is no need for an operation for adjusting the positions of the three components in an operation for attaching the strain wave gearing to a motor. After the strain wave gearing has been attached to the motor, the temporary-fixing jig is removed from the strain wave gearing, wherefore less space is required for installation.

Speed reducer

In a rotation transmission mechanism that transmits the rotational driving force of a motor to a load-side member via a speed reducer, a strain wave gearing is used as the speed reducer, and the allowable load torque of members in the powertrain other than the strain wave gearing is greater than a predetermined upper-limit load torque. The allowable load torque of the strain wave gearing is dictated by the ratcheting torque, which is set so as not to exceed the upper-limit load torque. In an overload state, ratcheting is generated in the strain wave gearing, so that the strain wave gearing functions as a mechanical fuse. Other power transmission members can be protected from an overload state without adding a separate member such as a torque limiter.

Rotation transmission mechanism provided with strain wave gearing

An externally toothed gear of a dual-type strain wave gearing is provided with first and second external teeth having different teeth numbers, and a gap formed between these teeth as a cutter clearance area for tooth cutters. Where L1 is the maximum width of the gap, t1 is a depth from the tooth top land of the first external teeth to the deepest part of the gap, h1 is the tooth depth of the first external teeth, t2 is a depth from the tooth top land of the second external teeth to the deepest part, and h2 is the tooth depth of the second external teeth, any one of the following conditions 1 to 3 is satisfied:1=0.1&#x2212;0.351=0.91&#x2212;1.31, and2=0.32&#x2212;0.92&#x2003;&#x2003;Condition 1:1=0.1&#x2212;0.351=0.31&#x2212;0.91, and2=0.92&#x2212;1.32&#x2003;&#x2003;Condition 2:1=0.1&#x2212;0.351=0.31&#x2212;0.91, and2=0.32&#x2212;0.92&#x2003;&#x2003;Condition 3: It is possible to obtain a dual-type strain wave gearing in which wear resistance and tooth bottom fatigue strength are increased.

Dual-type strain wave gearing

An externally toothed gear of a dual-type strain wave gearing is provided with first and second external teeth having different teeth numbers, and a gap formed between these teeth as a cutter clearance area for tooth cutters. The maximum width Lof the gap is 0.1 to 0.3 times the width L of the externally toothed gear. The depth from the tooth top land of the first external teeth to the deepest part of the gap is 0.9 to 1.3 times the depth of the first external teeth, and the depth from the tooth top land of the second external teeth to the deepest part of the gap is 0.9 to 1.3 times the depth of the second external teeth. The tooth bottom fatigue strength of the externally toothed gear provided with differing numbers of first and second external teeth is increased.

A restraint mechanism for limiting the movement of the flexible external gear of a flat strain wave gearing in the axial direction has a first restraining member installed in a floating state in a first recess and a second restraining member installed in a floating state in a second recess. The restraining member is able to limit the movement of the flexible external gear in the axial direction to a range in which there are no difficulties during actual use. Moreover, compared with when movement of the flexible external gear is limited using members that are disposed at fixed positions, it is possible to reduce the sliding abrasion that occurs between the flexible external gear and the first and second restraining members.

Flat strain wave gearing

A wave generator for a strain wave gearing makes a flexible externally toothed gear to flex into an elliptical shape and mesh with rigid internally toothed gears, and makes meshing positions of the flexible externally toothed gear with the both gears to move in a circumferential direction. On the inner side of a rigid plug of the wave generator, a plug support ring is secured and integrated. The rigid plug is formed from an iron-based material, and the plug support ring is formed from a high-rigidity material that is more rigid than the iron-based material. Since deformation of the rigid plug is suppressed, the wave generator provided with a large hollow part can be obtained.

Wave generator for strain wave gearing

A wave generator of a flat-type strain wave gearing has an insertion member disposed between two wave bearings. The insertion member is pressed into an elliptical outer peripheral surface of a plug and is fixed thereto by an adhesive. An inner ring contact part of the insertion member is in contact with inner rings of the wave bearings from the direction of a center axis. When the flat-type strain wave gearing is in an operating state, the wave bearings can be prevented from moving relative to the plug in the direction of the center axis by means of thrust force acting on the wave bearings.

Strain wave gearing and wave generator

A variable compression ratio mechanism for an internal combustion engine includes a gear reducer that varies an engine compression ratio. The gear reducer includes an input-side member connected to a rotation shaft of the actuator; an output-side member that transmits a reduced rotation of the actuator to the control shaft; a fixed member fixed to a housing of the actuator; and an intermediate member that transmits torque from the input-side member to the output-side member and the fixed member, and has a first gear portion engaged with the fixed member and a second gear portion engaged with the output-side member. A ratio of a number of teeth of the fixed gear portion to a number of teeth of the first gear portion is higher than a ratio of a number of teeth of the output-side gear portion to a number of teeth of the second gear portion.

Variable compression ratio mechanism for internal combustion engine

A variable compression ratio mechanism for an internal combustion engine includes a gear reducer that varies an engine compression ratio. The gear reducer includes an input-side member connected to a rotation shaft of an actuator; an output-side member that transmits a reduced rotation of the actuator to the control shaft; a fixed member fixed to a housing of the actuator; and an intermediate member that transmits torque from the input-side member to the output-side member and the fixed member, and has a first gear portion engaged with the fixed member and a second gear portion engaged with the output-side member. A ratio of a number of teeth of the fixed gear portion to a number of teeth of the first gear portion is lower than a ratio of a number of teeth of the output-side gear portion to a number of teeth of the second gear portion.

A relieving portion is formed between a first external tooth portion and a second external tooth portion in the external teeth of a flexible externally toothed gear of a flat strain wave gearing. The length Lof the relieving portion in the tooth trace direction is within the range of 0.1 to 0.5 of the tooth width L of the external teeth. The maximum relieving amount t from the tooth top land of an external tooth in the relieving portion is 3.3&#xd7;10&#x3c;t/PCD&#x3c;6.3&#xd7;10where the PCT is defined as the pitch circle diameter of the external teeth. The tooth face load distribution of the external tooth in the tooth trace direction can be equalized, and a flat strain wave gearing having a high transmitted-load capacity can be achieved.

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Azumino, Japan

Jun Handa