Hydrogen Engine Valve Overlap Control for Pre-Ignition

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Solution Overview

Problem

Hydrogen engines are prone to pre-ignition in high load and high revolution ranges due to their higher ignitability compared to gasoline engines, leading to temperature increases in the cylinder.

Innovation Solution

An engine control device adjusts the valve overlap amount by controlling the valve timing of intake and exhaust valves, increasing the overlap when the engine operates in high load and high rotation ranges to suppress pre-ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the engine operates in high load and high revolution range, then power output is improved, but pre-ignition occurs more likely

Engineering Contradiction:

Improvepower outputVSAvoidpre-ignition

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The control device performs preliminary action by increasing the valve overlap amount before pre-ignition can occur. By advancing the intake valve closing timing relative to the exhaust valve opening timing in high load and high revolution ranges, the system proactively reduces cylinder temperature and suppresses pre-ignition before it happens, allowing the engine to safely operate at high power levels

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention applies parameter changes by dynamically adjusting the valve timing parameters based on operating conditions. The control device changes the valve overlap amount according to load and revolution range, modifying the timing parameters to reduce cylinder temperature and prevent pre-ignition while maintaining power output capability

Inventive Principle:

Principle #35Parameter changes

2Temperature

If the valve overlap amount is increased to suppress pre-ignition, then temperature in cylinder is reduced, but scavenging performance may deteriorate

Engineering Contradiction:

Improvecylinder temperatureVSAvoidscavenging performance

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The invention applies dynamics by making the valve overlap amount variable rather than fixed. The control device dynamically adjusts the valve timing based on real-time operating conditions (load and revolution range), increasing overlap when needed to control temperature and reducing it when scavenging performance is prioritized, optimizing both objectives across different operating conditions

Inventive Principle:

Principle #15Dynamics

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

The solution effectively suppresses pre-ignition and reduces temperature in the cylinder, while maintaining efficient scavenging performance and minimizing hydraulic pressure fluctuations in the valve timing adjustment mechanisms.

Implementation Method 1

a valve timing adjustment mechanism that adjusts a timing of opening and closing of the intake valve and an timing of opening and closing of the exhaust valve

Methodology Applied

Scientific EffectValve timing control:

Implementation Method 2

an air-fuel mixture containing air and hydrogen is burned by a discharge of the ignition device

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS12442335B2Engine control device

Publication Date: 2025.10.14 TOYOTA JIDOSHA KK

AI summary

The control device is applied to an engine that uses hydrogen as a fuel. The control device includes a processing circuit that adjusts the valve overlap amount by controlling the valve timing of at least one of the intake valve and the exhaust valve. The processing circuit increases the amount of valve overlap when the engine is operated in the high-load, high-rotation range as compared to the case where it is not.