Torque Sensor Layout Around a Reduction Gear for Shorter Drives
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Solution Overview
Problem
Existing driving mechanisms incorporating a rotation motor, reduction gear, and torque sensor are difficult to downsize due to increased axial length, particularly when a reduction gear is used to adjust motor torque.
Innovation Solution
A torque sensor is configured to detect reaction torque on a reduction gear by using a force receiver, frame, and beams disposed around the reduction gear case, with strain measurement parts to measure beam strains, allowing for a compact design that does not hinder the connection between the reduction gear's output shaft and operation member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the torque sensor is disposed in series between the rotation motor and the operation member, then the motor torque can be detected accurately, but the axial length of the driving mechanism is increased
Solution Approach 1:
The torque sensor is repositioned from a series arrangement (axial direction) to a parallel arrangement around the output shaft. The force receiver and frame are disposed circumferentially around the output shaft, with beams extending radially, transforming the measurement geometry from axial to radial/d circumferential dimensions. This allows torque detection without increasing axial length.
Solution Approach 2:
The torque sensor components (force receiver, frame, beams) are arranged concentrically around the output shaft, with the force receiver surrounding the shaft, the frame surrounding the force receiver, and beams connecting them radially. This nested circular arrangement fits within the existing axial footprint while enabling torque measurement through circumferential strain detection.
2Adaptability or versatility
If the reduction gear is interposed in series between the rotation motor and the torque sensor, then the motor torque can be adjusted to desired magnitude, but the axial length of the driving mechanism is further increased
Solution Approach 1:
The torque sensor is integrated with the reduction gear assembly by positioning the force receiver and frame around the output shaft of the reduction gear. The beams connect the force receiver to the frame within the same radial space, merging the torque sensing function with the existing gear housing structure rather than adding separate axial components.
3Force
If the motor plate, mounting plate, and open ring are disposed to surround the output shaft, then the reaction torque can be received, but the output shaft length must be larger than the torque sensor axial length
Solution Approach 1:
The force transmission path is changed from axial to radial. The beams extend radially from the force receiver to the frame, and strain gauges measure radial/ circumferential strain rather than axial strain. This radial measurement approach eliminates the need for extended axial shaft length while maintaining force reception capability.
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
The configuration reduces the axial length of the driving mechanism, simplifies the torque sensor's structure, and enables accurate detection of output torque, thereby downsizing the mechanism while maintaining operational efficiency.
Implementation Method 1
a strain measurement part that is provided to at least one beam of the plurality of beams and that is configured to measure a strain of the at least one beam
Data Source
AI summary
To reduce a length in an axial direction of a driving mechanism including a rotation motor, a reduction gear, and a torque sensor to downsize the driving mechanism. A force receiver (32) fixed between a motor case (16) and a reduction gear case (22) is disposed outside the reduction gear case (22) so as to surround the reduction gear case (22). A frame (36) fixed to an attachment part (26) is disposed outside the reduction gear case (22) so as to surround the reduction gear case (22). A plurality of beams (40) are disposed around the reduction gear case (22) so as to be spaced from each other. A strain measurement part (42) is provided to at least one of the beams (40).