Torque Sensor Strain Body for Accurate Center Axis Detection
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Solution Overview
Problem
Conventional speed reducers with electric motors face difficulties in detecting torque around the center axis, as existing sensor configurations are designed to measure strains at the peripheral parts of the bearing, making it challenging to accurately detect loads applied to the output part.
Innovation Solution
A speed reducer design incorporating a hollow shaft, a tubular casing, a fixed part, an electric motor, a speed reduction mechanism, and a torque sensor with an elastically deformable strain body featuring an annular outer and inner ring, and strain sensors, which are connected to the casing and fixed part, allowing for the detection of torque around the center axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is mounted on the peripheral part of the bearing to detect strains, then the structure is simple and easy to manufacture, but it is difficult to detect torque around the center axis accurately
Solution Approach 1:
The patent transitions from detecting strains at the peripheral part of the bearing (2D surface measurement) to detecting strains at multiple positions including the center axis (3D volumetric measurement). The strain sensors are arranged at the outer peripheral surface, inner peripheral surface, and end surfaces of the bearing, enabling comprehensive torque detection around the center axis by measuring strain distribution in three-dimensional space.
Solution Approach 2:
The bearing is divided into multiple measurement zones with strain sensors placed at different locations: outer peripheral surface, inner peripheral surface, and end surfaces. This segmentation allows the system to capture strain variations across different regions of the bearing, enabling accurate torque detection by analyzing the combined data from all sensor positions.
2Measurement precision
If strain sensors are placed only at the outer peripheral surface of the bearing, then the device complexity is low, but the measurement precision for torque around the center axis is insufficient
Solution Approach 1:
The patent extends the measurement from the outer peripheral surface (2D) to include the inner peripheral surface and end surfaces (3D). This multi-dimensional sensor arrangement captures the complete strain distribution within the bearing, enabling accurate torque measurement around the center axis by analyzing strain variations across all three surfaces.
Solution Approach 2:
The bearing structure serves multiple functions: it supports rotational motion and simultaneously acts as a strain measurement platform at multiple locations. By placing strain sensors at the outer peripheral surface, inner peripheral surface, and end surfaces, the bearing becomes a multi-functional component that both supports mechanical operation and enables comprehensive torque detection.
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
Enables accurate detection of loads, including torque, applied to the output part by utilizing the torque sensor's strain body and sensors, effectively addressing the limitations of existing sensor configurations.
Implementation Method 1
a torque sensor which includes an elastically deformable strain body having an annular outer ring and an annular inner ring
Implementation Method 2
a plurality of strain sensors, and each of the plurality of strain sensors is at least partially located in the radial direction between the outer ring and the inner ring
Data Source
AI summary
This speed reducer with an electric motor has: a hollow shaft; a casing fixed to the hollow shaft; a fixed part that is relatively stationary with respect to the casing; an electric motor; a speed reduction mechanism; an output part; and a torque sensor that is connected to the casing and the fixed part. The torque sensor has an elastically deformable strain body that has an annular outer ring and an annular inner ring and a plurality of strain sensors. The outer ring and the inner ring are respectively located at an end portion on the radial outside and the radial inside of the torque sensor and is connected to one of the casing and the fixed part. Each of the plurality of strain sensors is at least partially located in a radial direction between the outer ring and the inner ring.