Vehicle Idle Launch Control via Brake-Transmission Coordination

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Solution Overview

Problem

Traditional brake and transmission control systems in vehicles increase fuel consumption when idling by maintaining creep torque, which can cause vehicles to roll backward on uphill grades, and existing solutions that release the transmission clutch to neutral may not effectively manage this issue.

Innovation Solution

A vehicle control system that integrates a braking system and transmission controller communicating via CAN, where the braking system maintains wheel brake torque using Hill Start Assist and the transmission controller releases a clutch to enter a neutral idle mode based on estimated powertrain torque, reducing engine load and preventing roll-back.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the transmission clutch is released to put the gearbox into neutral state, then fuel consumption during idle is reduced, but the vehicle may roll backwards on uphill grades

Engineering Contradiction:

Improvefuel consumptionVSAvoidvehicle roll-back

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The brake controller applies wheel brake torque in advance before the vehicle actually rolls backward, when the transmission is still in gear. This preliminary braking action holds the vehicle stationary during the transition to neutral idle mode, preventing roll-back while allowing the clutch to be released for fuel savings.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The braking system acts as an intermediary between the transmission system and the vehicle motion. By maintaining brake torque during the clutch release transition, the braking system mediates the conflict between reducing engine load (by disengaging transmission) and preventing vehicle roll-back, enabling both goals to be achieved simultaneously.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the transmission remains engaged in Drive mode, then the vehicle is prevented from rolling backwards through creep torque, but fuel consumption increases during idle

Engineering Contradiction:

Improvevehicle roll-back preventionVSAvoidfuel consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

Instead of relying on creep torque from an engaged transmission, the system applies preliminary brake torque to hold the vehicle stationary before releasing the clutch. This allows the transmission to be disengaged for fuel savings while the brake provides the necessary hold force to prevent roll-back.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system replaces the mechanical creep torque mechanism (transmission engaged in Drive mode) with a braking mechanism (wheel brake torque application). This substitution allows the transmission to be disengaged, eliminating the mechanical load on the engine during idle while still preventing vehicle roll-back through brake force.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Use of energy by moving object

If the clutch is released to enter neutral idle mode, then engine load is reduced, but the interval between brake release and clutch re-engagement creates a vulnerability period

Engineering Contradiction:

Improveengine loadVSAvoidvehicle stability during transition

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The brake controller applies wheel brake torque in advance during the clutch release transition, creating a safety buffer before the vehicle becomes vulnerable. This preliminary braking action ensures the vehicle remains held stationary throughout the entire transition period, eliminating the reliability vulnerability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The braking system provides a cushioning force during the clutch release transition, compensating for the temporary loss of drivetrain connection. By applying brake torque beforehand and maintaining it through the transition, the system cushions against any potential vehicle movement, ensuring stable and reliable operation throughout the neutral idle mode transition.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS9944288B1Vehicle idle and launch control

Publication Date: 2018.04.17 FORD GLOBAL TECH LLC

AI summary

A transmission controller implements a neutral idle feature to reduce fuel consumption. A brake controller implements a Hill Start Assist feature to prevent roll-back when a vehicle is launching on an uphill grade. The transmission controller and the brake controller communicate to implement these features in a synergistic manner. Within certain road grade ranges, the transmission requests Hill Start Assist before activating neutral idle and does not activate neutral idle until it receives confirmation that Hill Start Assist is active. The transmission controller provides a powertrain torque estimate to the brake controller which the brake controller uses to determine when to release the brakes during an assisted start.