Torque Sensor Outer Tube Deformable Part Geometry
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Solution Overview
Problem
Existing torque sensing devices for electric assisted bicycles face errors in torque signal measurement due to small deformation, which affects accuracy.
Innovation Solution
A torque sensing device with a transmission mechanism featuring a crankshaft, an outer tube with deformable parts, and strain gauges that measure deformation accurately by converting it into torque data, ensuring precise measurements through a processing unit connected to the strain gauges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque sensor with strain gauge is used to measure torque on the BB rotating shaft, then torque sensing capability is achieved, but measurement precision deteriorates when deformation is small
Solution Approach 1:
The outer tube is nested around the crankshaft, creating a concentric structure where the outer tube deformable part surrounds the crankshaft. This nesting arrangement allows the outer tube to capture and amplify the deformation caused by torque applied to the crankshaft, improving measurement precision while maintaining reliability under small deformation conditions.
Solution Approach 2:
The patent changes the geometric parameters of the outer tube, specifically creating a deformable part with a circumferential extension less than 180 degrees between first and second sides. This parameter modification optimizes the deformation characteristics of the outer tube, enhancing its ability to accurately sense torque while preventing signal loss under small deformation conditions.
2Measurement precision
If the outer tube deformable part extends circumferentially around the crankshaft, then torque deformation is captured, but structural complexity increases
Solution Approach 1:
The outer tube is segmented into distinct parts: a main tube part and a deformable part with specific geometric features. The deformable part is further defined by its circumferential extension creating first and second sides, forming an included angle less than 180 degrees. This segmentation allows each part to perform its specific function while simplifying the overall structure compared to a fully circumferential deformable section.
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 solution provides accurate and reliable torque data measurement by stabilizing deformation and limiting it within a reasonable range, enhancing the precision of torque sensing in electric assisted bicycles.
Implementation Method 1
The first strain gauge is attached to the first deformable part
Data Source
AI summary
A torque sensing device comprises a torque sensor and a transmission mechanism. The torque sensor includes an outer tube and a first strain gauge. The outer tube has a main tube part and a first deformable part. The main tube part is connected to and surrounds a crankshaft of the transmission mechanism. The first deformable part is connected to the main tube part. The first deformable part extends circumferentially around the crankshaft between a first and a second side. The first deformable part has a first included angle defined between a first line extending through a center of the crankshaft and a first side and a second line extending through the center of the crankshaft and a second side. The first included angle is less than 180 degrees. The first strain gauge is attached to the first deformable part.