Engine Valve Anti-Freezing Control for Reliable Cold Starts

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Solution Overview

Problem

Condensed water in internal combustion engines can freeze in the gap between the valve face and valve seat, leading to misfires and reduced engine startability due to incomplete valve closure or blocked gas passages.

Innovation Solution

A control device with an electronic control unit that executes anti-freezing operations by fully closing or opening valves with a lift amount of 1 mm or more, based on temperature and condensed water amount, to prevent freezing by either squashing or dripping condensed water away from the valve seat.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the valve is opened with a small degree of opening, then the condensed water is accumulated between the valve face and valve seat by surface tension, but if the valve is fully opened, the condensed water can drip down into the cylinder

Engineering Contradiction:

Improvevalve closure completenessVSAvoidcondensed water freezing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control device performs preliminary action by detecting condensed water accumulation before freezing occurs and proactively opening the valve to a predetermined lift amount to drain the water, preventing the harmful freezing effect before it can damage the valve closure

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The valve opening degree is made dynamic rather than fixed - the control device adjusts the valve lift amount based on detected conditions (condensed water presence and temperature), transitioning between fully closed, partially opened for drainage, and fully open states to optimize both sealing and water removal

Inventive Principle:

Principle #15Dynamics

2Reliability

If the valve is fully closed to ensure complete sealing, then valve closure completeness is improved, but condensed water accumulates in the gap between valve face and valve seat

Engineering Contradiction:

Improvevalve closure completenessVSAvoidcondensed water freezing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device changes the valve operating parameter (opening degree) from a fixed fully-closed state to a dynamic state where it opens to a predetermined lift amount when condensed water is detected, allowing water drainage while maintaining reliable closure during normal operation

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If the valve is opened with a lift amount of 1 mm or more, then the surface tension acting on condensed water is weakened and water drips down, but energy consumption increases due to frequent valve operations

Engineering Contradiction:

Improvecondensed water freezingVSAvoidenergy consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

Instead of continuous operation, the control device uses periodic action by operating the valve only when necessary - detecting condensed water accumulation and temperature conditions, then opening the valve to drain water, and returning to fully closed state, thereby reducing unnecessary energy consumption while maintaining effectiveness

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system uses self-service by leveraging the engine's own operating conditions (intake strokes, exhaust strokes, temperature changes) to naturally facilitate water drainage when the valve is opened, rather than requiring additional energy-intensive active heating or forcing mechanisms

Inventive Principle:

Principle #25Self-service

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

Effectively prevents condensed water from freezing, ensuring complete valve closure and maintaining engine functionality by removing accumulated water before it freezes, thereby enhancing startability and reducing energy consumption.

Implementation Method 1

When the intake valve or the exhaust valve is opened with a halfway degree of opening, the condensed water is accumulated between a valve face and a valve seat by the action of the surface tension of the condensed water.

Methodology Applied

Scientific EffectSurface tension: Surface Tension

Data Source

PatentEP3388655B1Control device for internal combustion engine

Publication Date: 2025.09.24 TOYOTA JIDOSHA KK

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AI summary

In a control device (30) for an engine (2), the engine (2) includes combustion chambers (6; 6L, 6R), ports (8; 8L, 8R, 10; 10L, 10R) connected to the combustion chambers (6; 6L, 6R), and valves (12; 12L, 12R, 14; 14L, 14R) that open and close areas between the combustion chambers (6; 6L, 6R) and the ports (8; 8L, 8R, 10; 10L, 10R). The control device (30) includes an electronic control unit that is configured to execute an anti-freezing operation of performing control to fully close the valves (12; 12L, 12R, 14; 14L, 14R) or make the valves (12; 12L, 12R, 14; 14L, 14R) be in a state of being opened with a lift amount of 1 mm or more, in a case where temperatures around the valves (12; 12L, 12R, 14; 14L, 14R) are lowered to a predetermined temperature range after the engine (2) is stopped, or in a case where an outside air temperature when the engine (2) is stopped is equal to or lower than a predetermined temperature. The predetermined temperature range is a temperature range in which an upper limit value is lower than 10°C, and the predetermined temperature is lower than 5°C.