Multi-Range Load Cell for Push and Pull Force Measurement
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Solution Overview
Problem
Conventional force sensors, such as load cells, have limited range capabilities and often cannot accurately measure both push and pull forces, especially in high-pressure scenarios, leading to potential damage and inefficiency in industrial applications.
Innovation Solution
A multi-range load cell design incorporating a body assembly with a protruding member and a sense die, where the Wheatstone bridge circuit generates signals based on force exerted by the protruding member on the sense die, allowing for accurate measurement of both push and pull forces through surface stress monitoring and correlation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional force sensors are used, then the device structure is simple, but the measurement range is limited and cannot accurately measure both push and pull forces
Solution Approach 1:
The load cell is designed to measure both push forces (compression) and pull forces (tension) using a single sensor element. The sense die and Wheatstone bridge circuit are configured to detect stress in both compression and tension, eliminating the need for separate sensors for different force directions and expanding the measurement range while maintaining a relatively simple structure.
2Adaptability or versatility
If beam deflection-type force sensors are used, then the measurement range is wide, but the sensors cannot be operated to measure both push force and pull force
Solution Approach 1:
The sense die is designed with specific local properties including a predetermined curvature and material characteristics that enable it to respond to both compressive and tensile stresses. The Wheatstone bridge circuit is configured with strain gauges positioned to detect stress changes in both directions, allowing the sensor to reliably measure both push and pull forces without requiring multiple separate sensing elements.
3Adaptability or versatility
If silicon die stress sensors are used, then the manufacturing precision is high, but the force ranges are limited and pulling forces cannot be measured
Solution Approach 1:
The load cell employs a composite structure combining a body element (typically metal) with a sense die (silicon or other stress-sensitive material). This composite design allows the sense die to be optimized for stress detection while the body element provides mechanical support and range extension. The Wheatstone bridge circuit is calibrated to account for the composite material properties, enabling accurate measurement of both push and pull forces across extended ranges while maintaining manufacturing precision.
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 design enables efficient and accurate detection of a broad range of forces, from low to high pressures, including both push and pull forces, providing a robust sensor arrangement suitable for various industrial applications.
Implementation Method 1
a sense die attached to the base element and aligned with the protruding member, where a top surface of the sense die supports a Wheatstone bridge circuit configured to generate a signal based at least in part on a force exerted by the protruding member on the sense die
Implementation Method 2
monitoring a surface stress of the sense die caused by the force exerted by the protruding member on the sense die; and correlating the surface stress and/or deflection to a push force or a pull force applied to the body element relative to the base assembly
Data Source
AI summary
The load cell for measuring a force in both push and pull includes a body assembly having a body element defining a measurement chamber with a closed end and an opposite open end, a protruding member positioned within the measurement chamber and extending from the closed end toward the open end. The load cell also includes a base assembly secured at the open end of the body element, including a base element; and a sense die attached to the base element and aligned with the protruding member, where a top surface of the sense die supports a Wheatstone bridge circuit configured to generate a signal based on a force exerted by the protruding member on the sense die. The body element, the protruding member and the base element are integrally formed from a common material which has a CTE close to the CTE of the sense die.