Vehicle Torque Control During Tip-In Lash Transitions
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Solution Overview
Problem
Existing vehicle control systems experience poor driveability due to transmission or driveline gear lash issues during acceleration following deceleration, leading to clunk and customer dissatisfaction, with rate limiting torque changes reducing clunk but increasing response delay.
Innovation Solution
A system that coordinates throttle and ignition timing adjustments to manage engine torque during driver tip-in, using slower throttle control and faster ignition timing to minimize response delay while reducing clunk, and adjusts based on slipping or non-slipping transmission conditions to manage lash transitions effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If rate limiting torque changes is applied to reduce clunk, then driveability is improved, but response delay increases
Solution Approach 1:
The patent segments the torque control function into two distinct actuators: throttle control for airflow management and ignition timing control for torque generation. This segmentation allows independent optimization of each actuator's response characteristics, enabling clunk reduction through coordinated control while maintaining overall response speed.
Solution Approach 2:
The system performs preliminary action by increasing airflow through throttle control before the lash zone transition occurs. This pre-charging of the intake manifold with airflow ensures that when torque is subsequently increased through ignition timing adjustment after lash transition, the engine can respond more rapidly without experiencing clunk, as the airflow path is already prepared.
2Speed
If coordinated throttle and ignition timing adjustments are made, then torque increase rate is improved after lash transition, but control complexity increases
Solution Approach 1:
The patent implements dynamic control strategies where the throttle and ignition timing adjustments are continuously adapted based on real-time engine operating conditions and lash zone detection. The control system dynamically switches between different torque management modes (rate limiting during lash transition, rapid increase after transition) based on the detected engine state, optimizing torque increase rate while managing complexity through adaptive rather than static control.
Solution Approach 2:
The system employs feedback mechanisms by monitoring engine operating parameters and lash zone transition status to continuously adjust throttle and ignition timing commands. This closed-loop control enables coordinated adjustments that achieve rapid torque increase after lash transition while preventing excessive complexity through systematic feedback-based decision making rather than open-loop complex scheduling.
3Ease of operation
If torque is increased rapidly during driver tip-in, then driver responsiveness is improved, but clunking sensations increase
Solution Approach 1:
The patent introduces airflow management through throttle control as an intermediary mechanism between the driver's torque request and the actual torque delivery. By using airflow increase as an intermediate step that prepares the engine for rapid torque response, the system mediates between driver responsiveness requirements and clunk reduction needs, allowing the airflow to absorb some of the transient effects that would otherwise cause clunking.
Solution Approach 2:
The system exploits parameter changes in engine operating conditions, specifically the relationship between airflow rate and torque generation. By changing the airflow parameter through throttle adjustment before and during torque increase, the system creates favorable conditions for rapid torque delivery without clunk, as the varying airflow parameter enables smoother torque transitions that reduce impact sensations.
Data Source
AI summary
A vehicle control method for a vehicle having powertrain with an internal combustion engine and a transmission having a clutch, the method comprising of transitioning through a lash region of the transmission during clutch slipping conditions in response to a driver tip-in; and during the transition, first retarding ignition timing past maximum torque timing while increasing engine airflow, and then second, advancing ignition timing from the retarded timing while continuing to increase engine airflow.