Transmission Neutral Shift Control for Clutch Failure

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Solution Overview

Problem

Automatic transmissions face challenges in detecting clutch failure and preventing inadvertent shifts from neutral to gear states, which can lead to vehicle movement, hardware failures, and other undesirable consequences due to failed-on clutches, especially during neutral-to-neutral shifts.

Innovation Solution

A vehicle controller is programmed to monitor clutch engagement and slip across the torque converter, verifying conditions before shifting between neutral states, and aborting shifts if a failed-on clutch is detected to maintain the transmission in a safe neutral state, thereby preventing torque transmission to the output shaft.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the transmission shifts to a neutral state with fewer engaged clutches, then the transmission response time improves, but the risk of inadvertent gear engagement increases due to failed-on clutches

Engineering Contradiction:

Improvetransmission response timeVSAvoidrisk of inadvertent gear engagement

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The control system performs preliminary monitoring of clutch slip conditions before executing a neutral-to-neutral shift. By detecting failed-on clutches in advance through slip monitoring during the current neutral state, the system can prevent inadvertent gear engagement before it occurs, while still allowing rapid shifts when conditions are safe

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors clutch slip conditions and provides feedback to the control logic. This feedback mechanism allows the controller to detect failed-on clutches and adjust shift timing accordingly, preventing inadvertent gear engagement while maintaining optimal response time when conditions permit

Inventive Principle:

Principle #23Feedback

2Reliability

If the transmission shifts to a neutral state with more engaged clutches, then the reliability against inadvertent gear engagement improves, but the transmission response time increases

Engineering Contradiction:

Improveprotection against inadvertent gear engagementVSAvoidtransmission response time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically selects between different neutral states (first neutral with fewer clutches, second neutral with more clutches) based on real-time clutch health conditions. This dynamic adaptation allows the transmission to optimize between response time and safety margins depending on the detected clutch slip conditions

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If the controller monitors clutch slip and torque converter slip continuously, then the detection precision of clutch failure improves, but the computational complexity increases

Engineering Contradiction:

Improveclutch failure detection precisionVSAvoidcontroller computational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses the existing torque converter slip monitoring infrastructure to indirectly detect clutch failures. By analyzing torque converter slip patterns that indicate clutch lockup conditions, the system achieves accurate clutch failure detection without requiring separate dedicated sensors or complex analysis algorithms for each clutch

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution effectively prevents unintended shifts and ensures the transmission remains in a safe neutral state, reducing the risk of vehicle movement and hardware damage by accurately detecting clutch failures and adjusting clutch engagement strategies during neutral-to-neutral shifts.

Implementation Method 1

A torque converter includes an impeller driven by the engine and a turbine driving the gearbox. Torque is transferred from the impeller to the turbine hydrodynamically.

Methodology Applied

Scientific EffectHydrodynamic torque transfer:

Data Source

PatentUS10295053B2Method and control for operating transmission during clutch failure

Publication Date: 2019.05.21 FORD GLOBAL TECH LLC

AI summary

A vehicle includes a transmission having a first neutral with a first combination of engaged clutches and a second neutral with a second combination of engaged clutches. The second neutral has more engaged clutches than the first neutral. A vehicle controller is programmed to, in response to a request to shift from the first to the second neutral and a failed-on clutch being detected, inhibit the shift to remain in the first neutral.