Transfer Case Clutch Control for Four-Wheel Drive Backlash Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional four-wheel drive vehicles experience backlash-induced jolting vibrations, known as 'clunk,' due to torque changes and differences in angular rotation between the front and rear driveshafts, leading to an uncomfortable ride for drivers and passengers.

Innovation Solution

A system that utilizes sensors to detect rotational parameters and determine torque reversals, sending command signals to engage or disengage a clutch pack in the transfer case to synchronize the front and rear driveshafts, thereby reducing backlash.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If torque changes occur during throttle level changes or transmission gear shifts, then power transmission is achieved, but backlash-induced jolting vibrations occur at gear interfaces

Engineering Contradiction:

Improvepower transmissionVSAvoidbacklash-induced jolting vibrations

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The system detects torque reversals using rotational parameters from sensors and proactively engages the clutch pack before the backlash-induced clunk occurs. By initiating clutch engagement responsive to determined torque reversal conditions, the system prevents the harmful vibration rather than reacting to it after occurrence.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The clutch pack serves as an intermediary mechanism between the power train and drive shafts. It temporarily absorbs and manages the torque changes during reversal events, preventing direct impact between gear teeth and eliminating the clunk while maintaining power transmission capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the front and rear driveshafts have different angular rotation changes, then four-wheel drive operation is maintained, but the duration of backlash-induced clunk is extended

Engineering Contradiction:

Improvefour-wheel drive operationVSAvoidduration of backlash-induced clunk

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of moving object

Solution Approach 1:

The system continuously monitors rotational parameters from sensors on both front and rear driveshafts, compares their rotational states, and detects when torque reversal conditions exist. This feedback loop enables real-time detection and response to differential rotation changes, allowing the clutch control system to engage at the optimal moment to minimize clunk duration while maintaining four-wheel drive adaptability.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7341541B2Method to reduce backlash in a drive train

Publication Date: 2008.03.11 FCA US LLC

AI summary

A method to reduce backlash in a drive train of a four-wheel drive vehicle, the method including receiving rotational parameters from sensors in the four-wheel drive vehicle, determining a torque reversal in the drive train based on the received rotational parameters and sending a command signal to initiate engagement of a clutch pack in a transfer case of the drive train responsive to the determination.