Wheel-Shaft Dynamometer Torque Sensing With Prestressed Elastic Strip
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Solution Overview
Problem
Dynamometer testing systems face inaccuracies due to unpredictable slipping and friction between vehicle tires and friction rollers, leading to inconsistent measurement results, especially in complex vehicles with multiple power sources and driver assistance systems.
Innovation Solution
A dynamometer test unit with a stator and rotor, connected by an elastic strip under homogenous tensile prestress, measures torque by restraining rotational movement and transferring force between the stator and stator support, using strain gauges to determine torque based on strain measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If friction rollers are used to apply brake torque to drive wheels, then the dynamometer system can be engaged with the vehicle, but slipping and friction between tyres and rollers cause inaccurate and variable test results
Solution Approach 1:
The patent introduces an elastic strip as an intermediary element between the stator and stator support. This elastic strip serves as a mediator that transfers torque while maintaining a consistent mechanical connection, eliminating the slipping and friction issues present in direct friction-based systems. The elastic strip provides a reliable torque transmission path that does not depend on tire-roller friction contact.
Solution Approach 2:
The patent replaces the friction-based mechanical engagement system with an elastic coupling system. Instead of relying on friction between rollers and tires, the system uses an elastic strip to transmit torque from the stator to the stator support. This substitution of the mechanical engagement mechanism eliminates the variability and inaccuracies associated with friction-based measurement.
2Measurement precision
If the elastic strip is firmly secured to transmit torque accurately, then measurement precision improves, but the strip may be subjected to non-uniform stress distribution causing measurement errors
Solution Approach 1:
The patent applies parameter changes by subjecting the elastic strip to a controlled tensile prestress before it is firmly secured to both the stator and stator support. This prestressing modifies the stress state of the elastic strip, ensuring that when torque is applied during testing, the stress distribution remains uniform throughout the strip. The prestress compensates for any potential non-uniform stress distribution that would otherwise occur during firm securing and torque transmission.
3Adaptability or versatility
If complex vehicle transmissions with multiple power sources are tested, then comprehensive functionality can be evaluated, but the testing complexity and difficulty increase significantly
Solution Approach 1:
The patent creates a universal dynamometer test unit that can handle complex vehicle transmissions with multiple power sources through its versatile elastic strip coupling system. The elastic strip-based torque transmission mechanism is adaptable to various configurations and power source arrangements, allowing the same test unit to accommodate different vehicle types and transmission complexities without requiring specialized equipment for each scenario.
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
Provides accurate torque measurements during vehicle testing, including rapid accelerations and complex driving conditions, with reduced temperature-related uncertainties and improved measurement consistency.
Implementation Method 1
the elastic strip being firmly secured in a manner such that it is subjected to homogenous tensile prestress in a longitudinal direction of the elastic strip
Implementation Method 2
subjected to homogenous tensile prestress in a longitudinal direction of the elastic strip
Implementation Method 3
means for measuring torque comprising an elastic strip, wherein the elastic strip connects the stator to the stator support, thereby restraining relative rotational movement between stator and stator support, and configured to transfer force between the stator and stator support
Data Source
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AI summary
The present invention relates to a dynamometer test unit configured for use in a vehicle dynamometer system for dynamometer testing of a vehicle, the dynamometer test unit being configured to be connected to a wheel shaft of a vehicle, the dynamometer test unit comprising a power source having a stator and a rotor and being configured to, during testing, apply torque to a wheel shaft of the vehicle being tested, the power source being carried by a stator support, the stator being journaled in relation to the stator support, the dynamometer test unit further comprising means for measuring torque comprising an elastic strip, wherein the elastic strip connects the stator to the stator support, thereby restraining relative rotational movement between stator and stator support, and configured to transfer force between the stator and stator support, the elastic strip being firmly secured in a manner such that it is subjected to homogenous tensile prestress in a longitudinal direction of the elastic strip.