Torque Calibration Actuator Eliminates Stick-Slip Friction
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Solution Overview
Problem
Conventional torque measuring device calibration methods face challenges in achieving high accuracy and compactness due to limitations in generating sufficient reference torque without experiencing the 'stick-slip effect' and transverse forces, which affect the practicality and user-friendliness of the calibration process.
Innovation Solution
The solution involves a reference torque generating device with an actuator that can be actuated without starting static friction, using a drive element with a pressure chamber and elastically deformable components, such as a diaphragm or bellows cylinder, to generate a reference torque without static friction, and a control loop for precise fluid pressure control via pulse width modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pneumatic or hydraulic cylinders are used to generate reference torque, then the device structure is simple, but the stick-slip effect occurs causing measurement inaccuracy
Solution Approach 1:
The patent replaces conventional pneumatic or hydraulic cylinders with a motor-driven mechanical system. The motor (27) drives a drive shaft (23) connected to a lever arm (24), eliminating fluid-based actuation that causes stick-slip effects. This mechanical substitution provides continuous, controlled motion without the static friction problems inherent in pneumatic/hydraulic systems.
Solution Approach 2:
The patent uses a reference torque generation device that replicates the torque measurement function with known accurate parameters. The lever arm length and applied force are precisely controlled and measured, creating a reference standard that copies the ideal torque application scenario without the measurement errors present in conventional systems.
2Force
If a long lever arm is used to generate sufficient torque with pneumatic cylinders, then the required force is reduced, but the device compactness deteriorates
Solution Approach 1:
The motor-driven system provides high force output directly through the drive shaft and lever arm connection, eliminating the need for long lever arms that would be required if using low-force pneumatic cylinders. The motor's inherent high force capability allows for a compact lever arm design.
Solution Approach 2:
The motor-driven drive shaft serves multiple functions: it provides the driving force, transmits torque, and enables precise control of the reference torque application. This multi-functional component replaces the need for separate force generation and transmission mechanisms, allowing compact design.
3Ease of manufacture
If weights are attached to a horizontal lever for calibration, then the calibration method is simple, but transverse forces occur reducing accuracy
Solution Approach 1:
The patent replaces the passive weight-based calibration system with an active motor-driven system. Instead of relying on gravitational force from weights that create transverse loads on the lever, the motor applies force directly along the intended torque axis through the drive shaft, eliminating transverse force errors while maintaining calibration simplicity through automated control.
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 enhances the accuracy and compactness of torque measurement calibration by eliminating the 'stick-slip effect' and allowing for precise control of reference torque, improving the overall calibration process of torque measuring devices on test benches.
Implementation Method 1
a drive element which can be actuated without static friction for generating a reference force
Data Source
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AI summary
The invention relates to an arrangement for calibrating a torque-measuring device (1) of a motor vehicle test bench or engine test bench (2), comprising: a reference torque generating device (3) for generating a reference torque acting about a working axis (4), a reference torque measuring device (5) for measuring the reference torque acting around the work axis (4), and a connecting device (6) for connection or rotary connection of the arrangement to the torque-measuring device (1) and for transmission of the reference torque to the torque-measuring device (1), wherein the reference torque generating device (3) has at least one actuator (8) which can be actuated without static friction on start-up having a drive member (7) which can be actuated without static friction on start-up for generating a reference force.