Vehicle Launch Control Torque Modulation

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Solution Overview

Problem

Launch control in vehicles with automatic transmissions is challenging due to difficulty in precisely controlling torque transmission to the driving wheels, whereas dual clutch transmission (DCT) and automated manual transmission (AMT) systems can control clutch torque for precise torque transmission, but require optimized methods for fast acceleration.

Innovation Solution

A vehicle launch control method that adaptively increases clutch torque with decreasing braking pressure, maintains torque levels for specific durations, reduces torque when wheel slip exceeds reference ratios, and increases torque again to reach higher levels, while stopping the launch control when clutch slip meets critical synchronous conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If clutch torque is increased to reach higher torque levels for fast acceleration, then vehicle acceleration speed is improved, but wheel slip ratio increases causing loss of traction control

Engineering Contradiction:

Improvevehicle acceleration speedVSAvoidwheel slip ratio

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The control method continuously monitors wheel slip ratio and adjusts clutch torque accordingly. When wheel slip ratio exceeds the first reference slip ratio, the clutch torque is reduced to bring it back within the acceptable range. When wheel slip ratio is within the acceptable range, clutch torque is increased to maximize acceleration. This closed-loop feedback control resolves the contradiction by dynamically balancing acceleration speed and wheel slip control.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The clutch torque is not maintained at a fixed level but is dynamically adjusted between different reference torque levels based on real-time wheel slip conditions. The system transitions between first reference torque level and second reference torque level to optimize both acceleration performance and traction control, making the system adaptable to changing driving conditions.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If clutch torque is reduced to control wheel slip ratio, then wheel slip control is improved, but vehicle acceleration speed decreases

Engineering Contradiction:

Improvewheel slip ratioVSAvoidvehicle acceleration speed

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The control method employs periodic adjustment of clutch torque between two reference levels. When wheel slip exceeds the threshold, torque is reduced to the second reference level; when wheel slip is controlled within acceptable range, torque is increased to the first reference level. This periodic oscillation between torque levels maintains optimal acceleration while preventing excessive wheel slip.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system changes the clutch torque parameter dynamically based on wheel slip ratio conditions. By switching between different torque levels (first reference torque level and second reference torque level) and different slip ratio thresholds (first reference slip ratio and second reference slip ratio), the system optimizes the balance between acceleration performance and wheel slip control.

Inventive Principle:

Principle #35Parameter changes

3Speed

If clutch torque is maintained at high level for extended duration to maximize acceleration, then acceleration performance is improved, but clutch wear and heat generation increase

Engineering Contradiction:

Improveacceleration performanceVSAvoidclutch engagement duration

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The control method implements periodic modulation of clutch torque rather than continuous high-level engagement. By alternating between first reference torque level and second reference torque level based on wheel slip conditions, the system reduces continuous clutch slip duration, thereby minimizing wear and heat generation while maintaining acceleration performance.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The control method proactively reduces clutch torque when wheel slip approaches excessive levels, preventing prolonged high-slip conditions that would cause excessive wear and heat. This preventive approach cushions against the harmful effects of extended clutch engagement at high torque levels.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11498559B2Launch control method for vehicle

Publication Date: 2022.11.15 HYUNDAI MOTOR CO LTD

AI summary

A launch control method for a vehicle may include a step of increasing clutch torque of a clutch according to a decrease in braking pressure, a step of maintaining a current level of the clutch torque for a first reference duration, a step of gradually reducing the clutch torque within a range which is lower than the first reference torque level and is equal to or greater than a second reference torque level which is lower than the first reference torque level, a step of gradually increasing the clutch torque until the clutch torque reaches a third reference torque level which is higher than the first reference torque level, and a step of bringing the control to a stop when a state in which a clutch slip is less than a predetermined critical synchronous slip is maintained for a predetermined critical synchronization duration or longer than the predetermined critical synchronization duration.