Vehicle Powertrain Backlash Control via Multi-Tiered Torque Strategy
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Solution Overview
Problem
Existing systems face challenges in controlling backlash in vehicle powertrains due to uncertainties in operational parameters, leading to unacceptably slow tip-in responses and rough transitions, as adjustments to driveline torque control can result in decreased backlash transition rates.
Innovation Solution
A method and system that employ a multi-tiered torque control strategy, using a first control strategy after a backlash predictor and before the actual backlash, followed by a second control strategy to reduce torque request levels below the highest level achieved during the first strategy, ensuring smooth transitions through the backlash region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If adjustments are made to driveline torque control to manage backlash, then the smoothness of backlash transition is improved, but the tip-in response speed deteriorates
Solution Approach 1:
The system detects a lash zone predictor signal before the actual backlash occurs and pre-adjusts the torque request in anticipation of the upcoming backlash event. This preliminary action allows the system to prepare for the backlash transition in advance, enabling smoother transitions without sacrificing response speed when the actual backlash occurs.
Solution Approach 2:
The control system dynamically adjusts the torque request based on real-time detection of backlash conditions and predictor signals. The torque control strategy changes continuously depending on whether the system is in a normal operating state or approaching a backlash event, allowing optimal performance across different operating conditions.
2Stability of the object's composition
If torque request level is reduced to decrease backlash transition rate, then the smoothness of transition is improved, but the response time deteriorates
Solution Approach 1:
By detecting the lash zone predictor signal in advance, the system performs torque adjustments before the backlash actually occurs. This preliminary action compresses the effective transition time by preparing the system in advance, so that when the actual backlash occurs, the transition is both smooth and rapid.
Solution Approach 2:
The system identifies and accelerates through the critical backlash transition phase by using the predictor signal to trigger targeted torque adjustments that quickly move the driveline through the backlash region, minimizing the time spent in the unstable transition state while maintaining smoothness.
Data Source
AI summary
A system and method for controlling backlash in a vehicle powertrain includes the step of controlling a torque request of the powertrain with a first control strategy after an occurrence of a backlash predictor and before an occurrence of a backlash. Another step may be employed whereby the torque request is controlled with a second control strategy after the first control strategy and before the occurrence of the backlash such that a torque request level is below a highest torque request level obtained during the first control-strategy.