Lockup Clutch Release Control for Brake Deceleration Consistency
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Solution Overview
Problem
Conventional lockup disengagement control devices in automatic transmissions face challenges in setting an appropriate lockup release vehicle speed, leading to variations in vehicle behavior during brake deceleration, which can be difficult to manage and require extensive parameter tuning.
Innovation Solution
A lockup disengagement control device that senses the initial deceleration when the brake is operated from OFF to ON and sets a higher lockup release vehicle speed based on the absolute value of this deceleration, disengaging the lockup clutch when the vehicle speed reaches or falls below this set speed during brake deceleration, thereby controlling vehicle behavior within acceptable limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed lockup release vehicle speed is set, then the control logic is simple, but the vehicle behavior varies significantly during brake deceleration
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed lockup release vehicle speed to a dynamic, variable lockup release vehicle speed that adapts to different deceleration conditions. The control section calculates the lockup release vehicle speed based on the relationship between vehicle speed and deceleration magnitude, allowing the system to adjust the release timing according to actual driving conditions. This resolves the contradiction by making the control logic adaptive rather than static, improving vehicle behavior consistency without excessive complexity.
2Reliability
If the lockup release vehicle speed is set higher to suppress vehicle behavior variation, then vehicle behavior consistency improves, but the lockup clutch engages more frequently increasing complexity
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the lockup release vehicle speed parameter based on deceleration magnitude rather than using a fixed value. The control section calculates appropriate release speeds by considering the relationship between vehicle speed and deceleration, changing the parameter adaptively to suppress vehicle behavior variation. This resolves the contradiction by using intelligent parameter adjustment rather than simply increasing the fixed speed threshold, avoiding excessive clutch engagement while maintaining consistency.
3Reliability
If extensive parameter tuning is performed to optimize lockup release timing, then vehicle behavior consistency improves, but development time and cost increase
Solution Approach 1:
The patent applies self-service by enabling the control system to automatically calculate and adjust the lockup release vehicle speed based on real-time deceleration measurements. Rather than requiring extensive manual parameter tuning and checking, the system serves itself by computing appropriate release speeds dynamically using the relationship between vehicle speed and deceleration magnitude. This resolves the contradiction by replacing time-consuming manual optimization with automated real-time calculation.
Data Source
AI summary
A lockup disengagement control device for an automatic transmission including a torque converter including a lockup clutch, and a lockup control section, the lockup disengagement control device includes: when a brake is operated from a brake OFF to a brake ON during a coast traveling in an engagement state of the lockup clutch, the lockup control section being configured to sense an initial deceleration by the brake ON operation, and to set a lockup release vehicle speed to be higher as an absolute value of the initial deceleration is greater, and when a vehicle speed is sensed to be equal to or smaller than the set lockup release vehicle speed in a middle of a brake deceleration scene by the brake ON operation, the lockup control section being configured to disengage the lockup clutch.