Crankshaft Load Cell Structure for Precise Radial Force Sensing
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Solution Overview
Problem
Current technologies lack an effective method to accurately measure radial forces acting on a crankshaft, which is crucial for determining torque and ensuring proper support in transmission systems, especially in electric bicycles and internal combustion engines.
Innovation Solution
A load cell design featuring a cylindrical receiving sleeve with measuring regions connected to a fastening ring via axial support areas, equipped with strain sensors to measure radial forces, allowing for the calculation of torque and precise force determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bearing is directly mounted in a transmission housing without a load cell, then the device complexity is reduced, but the measurement precision of radial forces is lost
Solution Approach 1:
The load cell is designed as a nested structure where the receiving sleeve receives the bearing outer ring, and the fastening ring is connected to the receiving sleeve via measuring regions. This nested arrangement allows the load cell to be integrated into the transmission housing without requiring separate mounting structures, thereby reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The load cell serves multiple functions: it provides radial support for the bearing, measures radial forces through strain sensors, and transfers axial forces through the fastening ring. By combining these functions into a single component, the invention eliminates the need for separate support and measurement devices, reducing device complexity while achieving precise force measurement.
2Measurement precision
If strain sensors are mounted on measuring regions, then the measurement precision of radial forces is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The measuring regions are designed with specific local geometries (such as angle brackets with radial and axial regions) that are optimized for strain distribution. This localized optimization allows strain sensors to be mounted on surfaces with controlled deformation characteristics, reducing the overall manufacturing precision requirements while maintaining high measurement precision at the sensor locations.
Solution Approach 2:
The load cell structure includes parameters such as the angle of the measuring lugs (approximately 90 degrees between radial and axial regions) and the dimensions of the measuring regions that can be adjusted to optimize strain distribution. By carefully selecting these parameters, the invention achieves uniform strain distribution that is easier to manufacture while maintaining high measurement precision.
3Reliability
If axial support areas are separated from measuring regions by radial slots, then the reliability of force measurement is improved, but the device complexity increases
Solution Approach 1:
The load cell is segmented into distinct functional regions: axial support areas separated from measuring regions by radial slots, and the circumferential slot separating the receiving sleeve from the fastening ring. This segmentation ensures that axial forces and radial forces are measured independently without interference, improving measurement reliability. The slots are simple geometric features that do not significantly increase device complexity.
4Measurement precision
If measuring regions are designed as angle brackets with radial and axial regions, then the measurement precision is improved, but the manufacturing complexity increases
Solution Approach 1:
The angle bracket measuring lugs are designed with standard parameters such as 90-degree angles between radial and axial regions, and consistent thicknesses. These standardized parameters simplify the manufacturing process while ensuring controlled deformation characteristics for accurate strain measurement. The geometry is optimized to produce uniform strain distribution that is easy to manufacture with conventional machining processes.
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 torque calculation and improved force distribution, reducing friction losses and enhancing the accuracy of force measurements in transmission systems.
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 having a receiving sleeve for receiving a bearing ring and a fastening ring for attaching the load cell in a transmission housing. Axial support areas are provided on the fastening ring for axially supporting the outer ring of the first bearing. Moreover, measuring regions for receiving radial forces of the receiving sleeve are provided which connect the receiving sleeve with the fastening ring. Strain sensors are attached to at least two of the measuring regions.