Engine High-Speed Starting With Cylinder Decompression Control

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Solution Overview

Problem

Engine starting events in vehicles with engine stop-start and engine-off coasting features face inefficiencies due to energy penalties, combustion instability, and increased emissions and noise, which existing technologies have not adequately addressed.

Innovation Solution

A system utilizing a motor/generator and electronically controllable clutch to accelerate the engine to a high-speed starting speed with fueling stopped and a cylinder decompression mechanism activated, followed by resuming fueling upon achieving the high-speed starting conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If traditional engine starting is used, then the engine can be started, but energy consumption increases due to overcoming inertia, friction, compression losses, and pumping losses

Engineering Contradiction:

Improveenergy consumptionVSAvoidstarting capability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system performs preliminary action by pre-rotating the engine to a high speed (e.g., 3000-6000 RPM) before the actual starting event using the motor/generator. This preliminary rotation stores kinetic energy in the rotating mass, which is then available to overcome compression and friction losses during the actual start, thereby reducing the energy penalty during the critical starting phase.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the traditional mechanical starting system (starter motor directly cranking the engine from idle speed) with an electrically-driven system (motor/generator) that can rapidly accelerate the engine to high speed. This substitution allows for more precise control over the starting process and enables the engine to skip the low-speed unstable region, reducing energy losses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-generated harmful factors

If traditional engine starting is used, then the engine can be started, but combustion instability occurs increasing emissions and noise

Engineering Contradiction:

Improveemissions and noiseVSAvoidcombustion stability

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The system applies the skipping principle by rapidly accelerating the engine through the unstable low-speed rotation region and directly establishing operation at a higher, more stable speed range. By using the motor/generator to quickly bring the engine up to speed and immediately initiating fuel injection and combustion at this higher speed, the system skips the problematic intermediate speed range where combustion instability, misfires, and incomplete combustion typically occur, thereby reducing emissions and noise.

Inventive Principle:

Principle #21Skipping (Rushing through)

3Use of energy by moving object

If engine stop-start features are implemented, then fuel efficiency improves during idle, but the number of engine start events increases compounding the energy penalty

Engineering Contradiction:

Improvefuel efficiency during idleVSAvoidcumulative energy penalty from frequent starts

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The system maintains a preliminary rotational state by keeping the engine rotating at a low but non-zero speed or by using the motor/generator to quickly re-rotate the engine to high speed after each stop event. This preliminary action ensures that the engine is never completely stationary, thereby minimizing the cumulative energy penalty associated with frequent start-stop cycles while still achieving fuel efficiency during extended idle periods.

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 energy consumption, minimizes emissions, and enhances engine starting efficiency by leveraging a hybrid powertrain system with a traction motor and clutch control to achieve rapid and stable engine startup.

Implementation Method 1

A motor/generator and electronically controllable clutch are used to accelerate the engine to a high-speed starting speed

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

accelerating the engine to a high-speed starting speed with fueling of the engine stopped and a cylinder decompression mechanism activated

Methodology Applied

Scientific EffectMechanical decompression:

Data Source

PatentUS12448929B2Apparatuses, methods, and systems including engine high-speed starting capability

Publication Date: 2025.10.21 CUMMINS INC

AI summary

A method of operating a vehicle including an engine includes suspending operation of the engine during operation of the vehicle including stopping fueling of the engine. The method includes accelerating the engine to a high-speed starting speed with fueling of the engine stopped and a cylinder decompression mechanism activated, the high-speed starting speed being greater than an idle speed of the engine. The method includes resuming operation of the engine including deactivating the cylinder decompression mechanism at the high-speed starting speed and thereafter restarting fueling of the engine.