Strain Sensor on Frame for Load Torque Measurement
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Solution Overview
Problem
Existing methods for determining load torque in counterbalanced industrial trucks are complex and prone to inaccuracies due to non-linear effects like friction and parasitic forces, making them unsuitable for series production and increasing the risk of tipping during load handling.
Innovation Solution
A strain sensor is attached to a longitudinally oriented frame section of the industrial truck, which primarily transmits longitudinal forces, allowing for accurate measurement of load torque by minimizing interference from driving maneuvers and focusing on tensile and compressive forces generated by the load, with the sensor position optimized to eliminate shear loads and parasitic forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are attached to load forks or tilt cylinders to determine load torque, then measurement coverage is improved, but device complexity and susceptibility to non-linear effects increase
Solution Approach 1:
The patent extracts the measurement function from complex locations (load forks, tilt cylinders, rear axle) and relocates it to a simple longitudinal frame member that only experiences longitudinal forces. This removes the need for complex multi-component measurement systems and eliminates parasitic forces from shear and lateral loads.
Solution Approach 2:
The patent applies local quality by selecting a specific location on the frame (longitudinal member) that has unique properties - it only transmits longitudinal forces. This local structural characteristic ensures that the strain sensor measures only the desired longitudinal component of load torque without interference from other force components.
2Measurement precision
If multiple force transducers are used to measure vertical forces and calculate load torque, then measurement completeness is improved, but ease of manufacture decreases
Solution Approach 1:
The patent merges the measurement function into a single strain sensor attached to the frame's longitudinal member, combining what would otherwise require multiple separate force transducers and complex calculation systems. This single-point measurement approach dramatically simplifies manufacturing while maintaining measurement accuracy.
Solution Approach 2:
The frame's longitudinal member serves dual purposes: it structurally transmits longitudinal forces and simultaneously provides the measurement platform for the strain sensor. The structure itself enables the measurement function without requiring additional complex components or assembly steps.
3Measurement precision
If wheel load sensors are used to determine longitudinal tilting forces, then measurement capability is improved, but reliability decreases due to friction and parasitic forces
Solution Approach 1:
The patent selects a specific local position on the frame where only longitudinal forces act on the structural member. This local structural characteristic ensures that the strain sensor measures purely longitudinal stresses without contamination from shear forces, friction, or parasitic loads that affect other measurement locations.
Solution Approach 2:
The patent converts the frame's structural function (transmitting longitudinal forces) into a measurement advantage. By placing the sensor on a member that naturally carries only longitudinal loads, the design eliminates the harmful effects of friction and parasitic forces that plague other measurement approaches, turning the frame's load-path characteristics into a reliability benefit.
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
This approach enables a simple, reliable measurement of load torque, reducing the risk of tipping by providing accurate data for operational adjustments such as reducing vehicle speed or mast inclination, thus enhancing safety and operational stability during load handling.
Implementation Method 1
a strain sensor is attached to the frame section, e.g. a strain gauge
Data Source
Figure 1~2
AI summary
The counterweight forklift truck (10) includes a device for determination of load torque on a load receiving unit which is arranged at the front side of the front axle (24). A counterweight (28) is arranged in the rear axle (26). The front axle and the counterweight are formed as a single unit and are mounted on a frame in which a strain sensor (36) such as a strain gauge is mounted.