Engine Stop Position Controller Cylinder Timing

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Solution Overview

Problem

Existing engine stop-start systems face challenges in controlling cylinder positions to optimize torque reduction, as the intake amount in compression stroke cylinders can become excessively large compared to expansion stroke cylinders, leading to inefficient engine starting.

Innovation Solution

The system adjusts the intake valve close timing to retard the intake valve close timing of compression stroke cylinders more than expansion stroke cylinders before engine stop, increasing blow-back and reducing intake amount, and adjusts the throttle valve opening to maintain optimal cylinder positions, ensuring suitable starting conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the opening degree of the throttle valve is increased immediately before engine stop to increase the intake amount of the stop-time compression stroke cylinder, then the intake amount of the compression stroke cylinder is increased, but the intake amount becomes excessive and shifts the cylinder position to bottom dead center side from the appropriate position

Engineering Contradiction:

Improveintake amount of compression stroke cylinderVSAvoidcylinder stop position accuracy

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by adjusting the intake valve closing timing (a temporal parameter) to control the intake amount. Specifically, it closes the intake valve of the compression stroke cylinder earlier than that of the expansion stroke cylinder, changing the timing parameter to prevent excessive intake and maintain accurate cylinder stop position.

Inventive Principle:

Principle #35Parameter changes

2Force

If the intake amount of the stop-time compression stroke cylinder is increased to compensate for later intake stroke termination, then the force from intake air to push down the piston is insufficient, but the excessive intake amount pushes the piston to bottom dead center side

Engineering Contradiction:

Improveforce from intake air on pistonVSAvoidpiston position control

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by closing the intake valve of the compression stroke cylinder earlier than that of the expansion stroke cylinder before the engine stop. This advance action prevents excessive intake air from entering the compression stroke cylinder, thereby preventing the piston from being pushed to the bottom dead center side and maintaining the appropriate stop position.

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If the engine is automatically stopped to improve fuel efficiency, then fuel consumption is reduced, but the torque required for engine restart varies according to cylinder position

Engineering Contradiction:

Improvefuel efficiencyVSAvoidtorque required for engine start

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent applies preliminary action by controlling the intake valve closing timing of each cylinder before the engine stop to ensure that the expansion stroke cylinder and compression stroke cylinder are positioned appropriately at engine stop. This advance control ensures that the engine can be restarted with minimized torque requirements, thus resolving the contradiction between fuel efficiency improvement and restart torque variation.

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 effectively reduces the torque required for engine start by maintaining optimal cylinder positions, preventing excessive intake in compression stroke cylinders and ensuring efficient engine restart.

Implementation Method 1

the retarded amount of the intake valve close timing immediately before the stop of the stop-time compression stroke cylinder from the intake bottom dead center is set to be larger than the retarded amount of the intake valve close timing immediately before the stop of the stop-time expansion stroke cylinder from the intake bottom dead center

Methodology Applied

Scientific EffectBlow-back:

Data Source

PatentEP4063642B1Stop position controller for engine, engine system, vehicle, and method of stopping engine

Publication Date: 2024.08.28 MAZDA MOTOR CORP

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AI summary

Intake valve close timing change means that collectively changes intake valve close timing as close timing of plural intake valves 11 and control means that controls each section of an engine E including fuel supply means and the intake valve close timing change means are provided. When a specified engine stop condition is satisfied, fuel cut is performed to stop a fuel supply into a cylinder by the fuel supply means. After the fuel cut, the intake valve close timing change means is controlled such that a retarded amount of intake valve close timing immediately before a stop of a stop-time compression stroke cylinder as a cylinder stopped in a compression stroke from intake bottom dead center is larger than a retarded amount of the intake valve close timing immediately before a stop of a stop-time expansion stroke cylinder as a cylinder stopped in an expansion stroke from the intake bottom dead center.