Load Sensor with Deformable Coil Spring for Eccentric Load Protection
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Solution Overview
Problem
Conventional load sensors are large and unsuitable for reducing size, and they fail to accurately measure loads acting in one axial direction, especially when subjected to eccentric loads or impacts, due to their configuration and lack of protection for sensor elements.
Innovation Solution
A load sensor design featuring a pressing shaft, a sensor element with strain gages, and a deformable coil spring as load limiting means, which protects the sensor element from excessive loads and allows accurate measurement by deforming under excessive loads and using a mechanical stopper to prevent further movement, enabling compact size and accurate axial load measurement even when subjected to off-axis forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a detector is arranged at a portion different from the displacement portion, then the load sensor can measure load, but the size of the load sensor becomes large
Solution Approach 1:
The detector is integrated directly at the displacement portion of the pressing shaft, merging the measurement function with the structural component. This eliminates the need for separate detector housing and reduces the overall sensor size while maintaining measurement capability.
Solution Approach 2:
The pressing shaft serves multiple functions: it transmits the load, undergoes displacement that indicates the load magnitude, and houses the detector. This multi-functionality reduces the number of separate components needed, thereby reducing the overall size of the load sensor.
2Reliability
If the pan is configured to be large to handle eccentric load, then the shaft can be made long enough for eccentric load, but the overall size of the load sensor increases
Solution Approach 1:
The pressing shaft is designed with an asymmetric structure where one end has a larger diameter than the other. The first end portion has a larger diameter to provide stability and handle eccentric loads, while the second end portion has a smaller diameter to reduce overall size. This asymmetric design allows the sensor to handle eccentric loads reliably without requiring a uniformly large structure throughout.
3Adaptability or versatility
If coil springs are configured in two stages, then the load sensor can detect load in a wide range, but the entire load sensor becomes large
Solution Approach 1:
The pressing shaft employs a dynamic diameter design where the diameter varies along its length. The first end portion has a larger diameter for handling higher loads or eccentric loads, while the second end portion has a smaller diameter. This dynamic variation in diameter allows the sensor to adapt to different load conditions without requiring a uniformly large structure, thereby reducing overall size while maintaining wide load detection range.
4Device complexity
If no configuration is provided for preventing inclination, then the device is simple, but the load may not be measured accurately when pressed from a direction deviating from the axial direction
Solution Approach 1:
The pressing shaft uses asymmetric diameter design where the first end portion has a larger diameter than the second end portion. This asymmetric structure provides inherent stability against inclination and eccentric loads, as the larger diameter portion resists tilting forces. This allows the sensor to maintain measurement accuracy even when subjected to off-axis forces, without requiring complex additional stabilization mechanisms.
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 enables accurate measurement of axial loads while protecting the sensor element and reducing the overall size of the load sensor, allowing it to function effectively under varying load conditions and extending its lifespan.
Implementation Method 1
a load limiting means configured to be deformable by the load when the load transmitted by the pressing shaft exceeds an allowable measurement range set for the sensor element
Implementation Method 2
a sensor element configured to measure the load being transmitted by the pressing shaft
Data Source
AI summary
There is provided a load sensor including: a pressing shaft configured to transmit a load in an axial direction of the pressing shaft; a sensor element configured to measure the load being transmitted by the pressing shaft; and a load limiting means configured to limit the load applied to the sensor element and protect the sensor element from being applied with excessive load, the load limiting means being configured to be deformable by the load when the load transmitted by the pressing shaft exceeds an allowable measurement range set for the sensor element.