Clutch Shift Control for Wheel Slip Flare Prevention

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing automatic transmission shift control systems struggle to efficiently manage shifts between speed ratios, particularly in conditions of wheel slip, which can lead to flare or tie-up conditions, affecting vehicle performance and controllability.

Innovation Solution

The method involves adjusting shift parameters based on the wheel slip condition, using different sets of parameters for non-wheel-slip and wheel-slip conditions. In wheel-slip conditions, the shift parameters are biased towards tie-up, with increased stroke pressure, delayed off-going clutch release timing, and higher ratio change capacity, to reduce the duration of the torque transfer and inertia phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the off-going clutch is released quickly to complete the shift faster, then the shift duration is reduced, but the speed ratio increases excessively causing flare condition

Engineering Contradiction:

Improveshift durationVSAvoidshift control stability

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The clutch release timing is dynamically adjusted based on detected wheel slip conditions. When wheel slip is detected, the off-going clutch release timing is delayed, allowing the clutch to remain engaged longer to maintain torque transfer stability and prevent flare conditions, while still completing the shift in a timely manner.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the shift parameters (specifically clutch release timing) based on the detected wheel slip condition. By modifying the timing parameter dynamically, the system optimizes the balance between shift speed and flare prevention for the current operating conditions.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the off-going clutch is released slowly to prevent flare, then the shift control stability is improved, but the torque transfer phase duration increases

Engineering Contradiction:

Improveshift control stabilityVSAvoidtorque transfer phase duration

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If wheel torque is increased to maintain traction, then vehicle controllability is improved, but wheel slip increases reducing performance

Engineering Contradiction:

Improvevehicle controllabilityVSAvoidvehicle performance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system uses feedback from wheel slip detection to dynamically adjust shift parameters. When wheel slip is detected during a shift, the controller modifies the clutch release timing and other shift parameters to bias toward tie-up conditions, reducing the likelihood of flare and improving both controllability and performance.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12305751B2Wheel slip flare controller using clutch control

Publication Date: 2025.05.20 FORD GLOBAL TECH LLC

AI summary

A method is proposed to complete a power-on upshift while a vehicle encounters wheel slip conditions such as driving in loose sand. The wheels slip conditions may be detected based on a maximum rate of change of an output shaft exceeding a threshold. In response to the wheel slip conditions, one or more shift parameters may be adjusted to bias the shift toward a tie-up and decrease the chance of a flare. These modified shift parameters may include an increased stroke pressure, a delayed off-going clutch release timing, and an increased ratio change capacity.