Engine Braking Control for Downhill Kinetic Energy Management

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Solution Overview

Problem

During extended downhill driving, vehicles with automatic transmissions select high gears to optimize fuel economy, resulting in low engine braking, leading to increased brake wear and potential degradation of braking performance due to frequent brake usage.

Innovation Solution

A method and system that determine the change in kinetic energy of a vehicle over a period, compare it to the energy output from the drivetrain, and initiate a downshift or activate electric machine braking when the kinetic energy exceeds the energy output, thereby increasing engine braking to reduce brake usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the control unit selects a high gear to optimize fuel economy during downhill driving, then fuel economy is improved, but engine braking is reduced

Engineering Contradiction:

Improvefuel economyVSAvoidengine braking

Core Design Contradiction:

Use of energy by moving objectVSForce

Solution Approach 1:

The transmission gear selection is made dynamic rather than static. The system continuously monitors kinetic energy changes and drivetrain energy output, adjusting gear selection in real-time based on whether the vehicle is coasting downhill. This allows the system to switch between high gear (for fuel economy) and lower gear (for engine braking) depending on current driving conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control unit implements a feedback mechanism by continuously comparing the change in kinetic energy to the drivetrain energy output. When the kinetic energy change exceeds the energy output (indicating coasting), the system responds by selecting a lower gear to increase engine braking. This closed-loop control ensures fuel economy is optimized when possible while providing adequate engine braking when needed.

Inventive Principle:

Principle #23Feedback

2Speed

If the driver relies on vehicle brakes to decelerate during extended downhill descent, then deceleration performance is maintained, but brake wear increases

Engineering Contradiction:

Improvedeceleration capabilityVSAvoidbrake pad wear

Core Design Contradiction:

SpeedVSLoss of substance

Solution Approach 1:

The system converts the normally wasted kinetic energy during coasting into useful engine braking force. By detecting when the vehicle is downhill and coasting (kinetic energy increase exceeds drivetrain energy output), the system uses the engine's compression resistance to provide deceleration, thereby reducing reliance on friction brakes and preventing brake pad wear while maintaining deceleration capability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Speed

If the driver relies on vehicle brakes during extended downhill descent, then deceleration is achieved, but braking performance degrades

Engineering Contradiction:

Improvedeceleration capabilityVSAvoidbraking performance

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system takes preliminary action by proactively engaging engine braking before the brakes are needed. By continuously monitoring energy parameters and preemptively selecting appropriate gears to provide engine braking, the system prevents brake overheating and performance degradation before they occur, rather than reacting after damage has been done.

Inventive Principle:

Principle #10Preliminary action

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 approach reduces brake wear and maintains braking performance by utilizing engine braking to decelerate the vehicle during downhill descents, lowering brake pad temperatures and extending their lifespan.

Implementation Method 1

the term 'engine braking' refers to when the retarding forces within an engine are used to slow a vehicle down

Methodology Applied

Scientific EffectEngine braking: Friction

Implementation Method 2

determining the energy output from a drivetrain of the vehicle over the said period

Methodology Applied

Scientific EffectEnergy transmission: Mechanical Force

Data Source

PatentUS10246096B2Method and system for increasing engine braking

Publication Date: 2019.04.02 FORD GLOBAL TECH LLC

AI summary

A method of increasing engine braking of an engine for a vehicle, the method including: determining the change in kinetic energy of the vehicle over a period; determining the energy output from a drivetrain of the vehicle over the period; comparing the change in kinetic energy to the energy output; and increasing the engine braking of the vehicle when the change in kinetic energy is greater than the energy output over the period.