Transfer Case Gear Clash Prevention via Locking Clutch

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Solution Overview

Problem

Gear clash conditions in vehicles with transfer cases, where gear teeth misalignment or failure to engage fully due to transmission drag torque lead to high failure rates of transfer case actuators, necessitating a system to prevent gear clash during engagement and disengagement of auxiliary equipment.

Innovation Solution

A system comprising a transmission, transfer case, and transmission controller with control logic to determine operator inputs, actuate torque transmitting devices, and monitor engagement/disengagement to prevent gear clash, including specific logic for engaging and disengaging auxiliary equipment while controlling torque transfer to avoid gear misalignment and full engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gear teeth are aligned properly for engagement, then auxiliary equipment can be engaged, but transmission drag torque prevents full engagement

Engineering Contradiction:

Improveengagement reliabilityVSAvoidtransmission drag torque

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The system applies a preliminary action by locking the transmission output shaft before auxiliary equipment engagement. The locking clutch is activated to prevent output shaft rotation, creating a stationary reference point that allows gear teeth to align and engage without resistance from transmission drag torque. This preliminary locking action resolves the force contradiction by eliminating the drag torque effect during the engagement process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically controls the transmission output shaft by switching between locked and unlocked states. During engagement, the shaft is locked to eliminate drag torque; during normal operation, the shaft is unlocked to allow free rotation. This dynamic state change enables the system to overcome the force contradiction by adapting the shaft's rotational characteristics to the specific operational phase.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If transmission output shaft is locked for engagement, then gear alignment is achieved, but operator control is reduced

Engineering Contradiction:

Improvegear alignment precisionVSAvoidoperator control

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The system incorporates feedback through sensors that detect the engagement state of auxiliary equipment and the position of the transmission output shaft. This feedback information is fed back to the controller, which automatically adjusts the locking clutch state and notifies the operator of engagement status. The feedback mechanism resolves the contradiction by automating the precision alignment process while keeping the operator informed, eliminating the need for manual trial-and-error engagement attempts.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs self-service by automatically controlling the locking clutch and monitoring engagement status without requiring continuous operator intervention. The controller autonomously manages the locking/unlocking sequence based on sensor feedback, and the system self-monitors to ensure proper engagement. This self-service capability maintains precision alignment while freeing the operator from manual control tasks.

Inventive Principle:

Principle #25Self-service

3Reliability

If multiple control logics are implemented for engagement control, then gear clash is prevented, but system complexity increases

Engineering Contradiction:

Improvegear clash preventionVSAvoidcontrol logic complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system merges multiple control functions into a single integrated controller that manages the locking clutch, monitors engagement status, and coordinates auxiliary equipment operation. Instead of separate control systems for each function, the controller combines gear alignment control, engagement monitoring, and operator interface management into one unified device. This merging approach prevents gear clash through coordinated control while reducing overall system complexity compared to multiple independent control systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The controller exhibits multi-functionality by performing diverse control tasks: managing the locking clutch for gear alignment, monitoring engagement sensors, communicating with the operator interface, and coordinating auxiliary equipment operation. This universal controller handles multiple functions that could otherwise require separate dedicated systems, preventing gear clash through integrated control while minimizing the number of control devices in the system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8335620B2Gear clash logic

Publication Date: 2012.12.18 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A system and method for selectively engaging and disengaging auxiliary equipment to avoid gear clash in a vehicle is disclosed. The system includes a transmission, a transfer case, and a transmission controller. The transmission has a plurality of gears and the transfer case is coupled to the transmission by an output shaft. The controller includes control logic for controlling the engagement and disengagement of the auxiliary equipment. The control logic has a first control logic for determining whether an operator has actuated a selector switch, a second control logic for actuating a torque transmitting device to engage or disengage the auxiliary equipment and avoid gear clash, a third logic for monitoring the engagement or disengagement of the auxiliary equipment, and a fourth control logic determining whether the auxiliary equipment has been engaged or disengaged.