Vehicle Drivetrain Test Stand Shear Clutch Inertia Decoupling
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Solution Overview
Problem
Conventional dynamometers with high inertia and low dynamic characteristics are inadequate for simulating wheel slip events due to their inability to accelerate and decelerate quickly, necessitating the use of expensive low inertia, high dynamic dynamometers, and continuously slipping clutches generate excessive heat and wear during simulations.
Innovation Solution
Implementing a shear clutch to isolate the inertia of the dynamometer from the drivetrain, with a control system that sets the clutch force equal to the tire force, using a clutch controller to manage torque and speed, and employing a wheel slip model to simulate tire behavior, allowing any dynamometer to be used with a shear clutch to replicate the inertial characteristics of a tire and wheel assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a high inertia, low dynamic dynamometer is used, then the cost is reduced, but the ability to simulate wheel slip events is compromised due to insufficient acceleration and deceleration capability
Solution Approach 1:
The system segments the inertial mass into two separate components: the dynamometer inertia (Idyn) and the simulated wheel inertia (Iwheel). By using a clutch to selectively couple these inertias, the system allows the dynamometer to have high inertia for cost reasons while still achieving the required dynamic response for wheel slip simulation through the controlled engagement of the wheel inertia component.
Solution Approach 2:
The system dynamically adjusts the effective inertial mass by controlling the clutch state. During normal operation, the clutch engages to couple the dynamometer and wheel inertia, creating the desired total inertia for simulation. During rapid acceleration or deceleration events, the clutch can disengage to allow the dynamometer to accelerate independently, providing the necessary dynamic response without requiring the dynamometer itself to have low inertia.
2Productivity
If a clutch is continuously slipped to simulate wheel slip, then the simulation is continuous, but excessive heat and wear are generated
Solution Approach 1:
Instead of continuous clutch slipping, the system uses periodic or intermittent clutch engagement. The clutch is engaged only when torque transmission is required and disengaged during rapid acceleration or deceleration events. This periodic action maintains the simulation capability while dramatically reducing continuous frictional heating and wear that would occur with continuous slipping.
Solution Approach 2:
The clutch acts as an intermediary device that selectively couples or decouples the dynamometer from the wheel inertia. By using the clutch as a mediator rather than continuously slipping, the system achieves the necessary simulation effects through controlled engagement and disengagement, reducing harmful heat and wear generation while maintaining simulation continuity through strategic re-engagement.
Data Source
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AI summary
A test stand may include a clutch operatively arranged with a dynamometer and a flywheel. The test stand may further include a controller configured to control the clutch to decouple a rotating inertia of the dynamometer from a rotating inertia of the flywheel such that the rotating inertia of the flywheel exhibits a desired rotating inertia.