Nested Actuator Design for High Torque in Compact Space

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Solution Overview

Problem

Conventional actuators face challenges in achieving high output while maintaining a compact size, particularly when a motor is arranged inside a flex spline, limiting their ability to generate significant torque.

Innovation Solution

The actuator design incorporates a motor with a cylindrical rotor and a wave gear reducer, where the input shaft is coaxial with the motor shaft and nested within the rotor, allowing for efficient arrangement and increased output without increasing size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the motor is arranged inside the flex spline, then the actuator size is reduced, but the motor size is limited and high output cannot be realized

Engineering Contradiction:

Improveactuator sizeVSAvoidoutput

Core Design Contradiction:

Volume of moving objectVSPower

Solution Approach 1:

The patent applies nesting by placing the input shaft of the wave gear reducer inside the rotor of the motor, creating a nested configuration where one component is positioned within the space of another. This allows the motor to be larger for high output while keeping the overall actuator compact, resolving the contradiction between actuator size and motor output capability

Inventive Principle:

Principle #7Nested doll (Nesting)

2Device complexity

If the motor is arranged inside the flex spline, then the actuator structure is compact, but only small motors can be used

Engineering Contradiction:

Improveactuator structureVSAvoidmotor size selection

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

Instead of placing the motor inside the reducer as in conventional designs, the patent inverts the arrangement by placing the input shaft inside the motor rotor. This inversion allows larger motors to be used while maintaining compact overall dimensions, expanding motor size selection flexibility without increasing actuator complexity

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11264865B2Actuator

Publication Date: 2022.03.01 SONY GROUP CORP

AI summary

An actuator capable of realizing a high output with a compact size is proposed. An actuator provided with a motor including a cylindrical rotor, and a reducer including an input shaft coaxial with a rotational shaft of the motor and nested in the rotor. The reducer has a cylindrical shape, the reducer further includes an output shaft coaxial with the rotational shaft of the motor, the motor further includes a stator, and the actuator is further provided with a casing which supports the reducer and the stator.