Compact Actuator Layout for High Torque and Short Axial Length
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Solution Overview
Problem
Existing actuators for robots face challenges in achieving high precision and torque while maintaining a compact and lightweight design, often resulting in low efficiency and increased inertia, which complicates precise movement.
Innovation Solution
The design incorporates a motor with a housing and two torque transfer devices, one with a drive member and another with an output member, where the torque ratio of the output device is smaller than or equal to the input device, allowing for a compact actuator arrangement with a cylindrical volume that includes the motor and torque transfer devices, and optionally uses pulley-based systems to enhance torque conversion without increasing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a motor and gear box arrangement is used to increase torque, then torque output is improved, but the axial extent of the actuator becomes large
Solution Approach 1:
The patent combines the motor and gear box into a single integrated actuator unit, merging previously separate components (motor, first torque transfer device, output torque transfer device) into one compact assembly. This integration allows the torque multiplication function to be achieved without increasing axial extent, as the gear mechanisms are arranged concentrically around the motor shaft.
Solution Approach 2:
The patent transitions from a linear axial arrangement to a radial/concentric arrangement by placing the first and output torque transfer devices around the motor shaft in different radial dimensions. This dimensional reorganization allows multiple torque transfer stages to coexist without increasing the axial length, effectively packing the gear box components into the radial space around the motor.
2Ease of manufacture
If the gear box is designed and built separately from the motor, then manufacturing is simplified, but the overall actuator arrangement becomes large
Solution Approach 1:
The patent merges the separately manufactured motor and gear box components into a single integrated actuator assembly. The motor housing forms part of the actuator housing, and the drive shaft connects directly to the first torque transfer device, creating a unified structure that reduces overall volume while maintaining manufacturing feasibility through modular component integration.
3Force
If high torque is achieved through traditional actuator design, then force output is improved, but inertia increases which reduces precision
Solution Approach 1:
The patent segments the torque transfer function into two distinct devices: a first torque transfer device for initial torque multiplication and an output torque transfer device for further torque conversion. This segmentation allows each device to be optimized for its specific torque ratio, achieving high overall torque output while minimizing the inertia of individual components compared to a single large gear box.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables a compact actuator with high torque conversion ratio and precision, reducing the axial extent and allowing integration within robotic arms, while maintaining a compact and efficient design.
Implementation Method 1
a first torque transfer device comprising a first drive member on the drive shaft and a first driven member on a second shaft, the first drive member being arranged to transfer torque to the first driven member
Implementation Method 2
an output torque transfer device comprising an output drive member on the second shaft and an output driven member, the output drive member being arranged to transfer torque to the output driven member
Data Source
AI summary
An actuator comprising: a motor comprising a housing and a drive shaft, the motor arranged to rotate the drive shaft relative to the housing about a drive shaft axis; a first torque transfer device comprising a first drive member on the drive shaft and a first driven member on a second shaft, the first drive member being arranged to transfer torque to the first driven member, such that the first torque transfer device is arranged to transfer torque from the drive shaft to the second shaft, the second shaft being rotatable about a second shaft axis spaced from the drive shaft axis; and an output torque transfer device comprising an output drive member on the second shaft and an output driven member, the output drive member being arranged to transfer torque to the output driven member, such that the output driven member rotates about an output axis; wherein a torque ratio of the output torque transfer device is smaller than or equal to a torque ratio of the first torque transfer device.