Crankshaft Load Cell Structure for Accurate Radial Force Sensing
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Solution Overview
Problem
Existing technologies lack an effective method to accurately measure radial forces acting on a crankshaft, which is crucial for determining torque and supporting bearings in transmission systems, especially in electric bicycles and internal combustion engines.
Innovation Solution
A load cell design featuring a cylindrical receiving sleeve, a fastening ring with axial support areas and measuring regions connected via strain sensors, allowing for the measurement of radial forces and decoupling axial forces, enabling precise torque calculation and improved bearing support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a load cell is designed to measure radial forces on a crankshaft, then measurement precision is improved, but device complexity increases due to the need for separate measuring regions and axial support areas
Solution Approach 1:
The load cell is divided into distinct functional regions: measuring regions with strain sensors for radial force measurement, and axial support areas for axial force bearing. This segmentation allows each region to be optimized for its specific function, improving measurement precision while maintaining manageable complexity through clear functional separation.
Solution Approach 2:
Different regions of the load cell are given different structural properties: the measuring regions are designed with strain-sensitive characteristics and equipped with strain sensors, while the axial support areas are designed to bear axial loads. This local differentiation enables precise radial force measurement without requiring the entire structure to be complex.
2Measurement precision
If strain sensors are mounted in measuring regions to detect radial forces, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The load cell is designed with pre-formed measuring regions that have predetermined strain characteristics. The strain sensors are mounted in these pre-designed locations during manufacturing, which establishes the measurement geometry early in the production process. This preliminary structuring reduces the precision requirements for subsequent assembly operations.
3Ease of manufacture
If axial support areas are separated from measuring regions by radial slots, then ease of manufacture is improved, but device complexity increases due to additional structural features
Solution Approach 1:
Radial slots are introduced to physically separate the axial support areas from the measuring regions. This segmentation serves dual purposes: it simplifies manufacturing by allowing independent fabrication or assembly of different regions, and it clearly defines the functional boundaries between axial load-bearing zones and radial force measurement zones.
Solution Approach 2:
The radial slots act as intermediary elements that connect the axial support areas to the measuring regions while maintaining their functional separation. These slots allow the structure to be manufactured in parts and assembled together, easing manufacturing complexity while the slots themselves become part of the load transmission path.
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 load cell enables accurate measurement of radial forces, facilitating precise torque determination and enhanced bearing support, reducing friction losses and improving measurement accuracy while being compact and efficient.
Implementation Method 1
Strain sensors are mounted in at least two of the measuring regions, for example as glued strain gauges. The measuring regions are provided for receiving radial forces of the receiving sleeve, which are transmitted from the ring of the bearing to the measuring regions.
Data Source
AI summary
A load cell for determining a radial force acting on a crankshaft includes a receiving sleeve for receiving a ring of a bearing; a fastening ring for attaching the load cell in a transmission housing; axial support areas provided on the fastening ring for axially supporting the ring of the bearing; and measuring regions for receiving radial forces of the receiving sleeve and which connect the receiving sleeve with the fastening ring, wherein strain sensors are attached to at least two of the measuring regions; and wherein the measuring regions comprise measuring lugs formed as angle brackets.