Transmission Neutral Shift for Driveline Clunk Reduction

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Solution Overview

Problem

Frequent engine starting and stopping to conserve fuel during low torque demand conditions can lead to starter degradation and driveline torque disturbances, such as 'clunk', when additional torque is requested, as existing methods either increase starter wear or cause transmission shifts that disrupt vehicle occupants.

Innovation Solution

A driveline operating method that shifts the transmission into neutral when vehicle speed is below a threshold and the brake pedal is applied, and then back into a forward gear as the brake pedal is released, reducing gear impact and allowing immediate torque delivery upon demand, using situational awareness sensors and paddle shifting switches for optimal engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the transmission is shifted into neutral to conserve fuel during low torque demand, then fuel economy is improved, but driveline torque disturbances (clunk) occur when torque is requested

Engineering Contradiction:

Improvefuel economyVSAvoiddriveline torque disturbance

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary action by shifting the transmission back into gear before the driver actually requests torque. The controller monitors brake pedal position and other indicators of impending torque demand, and proactively engages the transmission in advance. This eliminates the harmful clunk by ensuring gear engagement occurs before torque application, rather than simultaneously with it.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from multiple sensors including brake pedal position sensors, accelerator pedal position sensors, and situational awareness sensors to detect when the driver intends to request torque. This feedback information triggers the transmission shift timing, allowing the system to respond to driver intent rather than just actual torque requests.

Inventive Principle:

Principle #23Feedback

2Use of energy by moving object

If the transmission is shifted into neutral from forward gear, then fuel consumption is reduced, but torque delivery delay occurs when engine torque is requested

Engineering Contradiction:

Improvefuel consumptionVSAvoidtorque delivery delay

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The system shifts the transmission back into forward gear in advance of the actual torque request by monitoring indicators such as brake pedal position. This preliminary engagement ensures that when the driver requests torque, the transmission is already in gear and ready to deliver torque immediately, eliminating the delay that would otherwise occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system skips the neutral state temporarily by rapidly shifting back into gear when torque demand is anticipated. This rushing through the neutral state ensures minimal time spent without torque delivery capability while still maintaining fuel savings during the brief transition period.

Inventive Principle:

Principle #21Skipping (Rushing through)

3Use of energy by moving object

If the engine is stopped to conserve fuel during low torque demand, then fuel economy is improved, but starter degradation increases due to frequent starting and stopping

Engineering Contradiction:

Improvefuel economyVSAvoidstarter durability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system performs preliminary transmission engagement before torque demand occurs, which allows for smoother engine restarts when needed. By ensuring the transmission is already in gear before the engine restarts, the system reduces the mechanical shock and stress on the starter motor during engagement, thereby reducing starter degradation over time.

Inventive Principle:

Principle #10Preliminary action

4Speed

If the transmission is shifted back into gear immediately when torque is requested, then torque delivery is immediate, but gear impact and clunk are observed by occupants

Engineering Contradiction:

Improvetorque delivery speedVSAvoidgear impact

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system shifts the transmission into gear in advance of the actual torque request by monitoring driver intent indicators such as brake pedal position and situational awareness sensor data. This preliminary engagement ensures that when torque is requested, the transmission is already in gear, eliminating both the torque delivery delay and the harmful gear impact that would occur with immediate shifting.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system takes preliminary anti-action by engaging the transmission before torque demand occurs, which prevents the harmful effect of gear impact and clunk. By having the transmission already engaged when torque is requested, the system eliminates the sudden gear engagement impact that would otherwise be observed by occupants.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS10518780B2Methods and system for operating a vehicle

Publication Date: 2019.12.31 FORD GLOBAL TECH LLC

AI summary

Systems and methods for reducing perception of transitions from shifting a transmission from neutral to drive are described. In one example, the transmission is shifted from neutral to drive in response to brake pedal motion before the brake pedal is fully released so that timing of pressurizing clutches and engaging a forward gear is advanced to occur while the brake pedal is still applied.