Valve Timing Controller Camshaft Phase Stabilization

Solution Overview

Problem

Existing electric-motor-driven valve timing control systems for internal combustion engines face instability and responsiveness issues during engine starting, particularly with cold starts, due to static friction and undesirable hunting of the phase control system.

Innovation Solution

A controller for the valve timing control apparatus that includes a drive rotary member, an electric motor, a phase converter, and a detection section to synchronize the phase angle of the camshaft with the crankshaft, performing phase-control operations to stabilize the system and enhance responsiveness by adjusting the phase angle before and during engine starting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electric motor is driven from its stopped state during engine starting, then the phase control system can be initiated, but static friction causes time loss and hunting occurs leading to control instability

Engineering Contradiction:

Improvecontrol stabilityVSAvoidtime loss

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The control section performs preliminary phase control by rotating the camshaft to a predetermined phase angle position before the engine starting operation begins. This preliminary positioning of the camshaft ensures that when the electric motor is subsequently driven, it starts from a favorable initial position that reduces the impact of static friction and minimizes hunting, thereby improving control stability while reducing time loss.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the electric motor is driven from its stopped state during engine starting, then the phase control system can be initiated, but hunting occurs leading to control instability

Engineering Contradiction:

Improvecontrol stabilityVSAvoidcontrol responsiveness

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The control section performs preliminary phase control by rotating the camshaft to a predetermined phase angle position before the engine starting operation begins. This preliminary positioning of the camshaft ensures that when the electric motor is subsequently driven, it starts from a favorable initial position that reduces the impact of static friction and minimizes hunting, thereby improving control stability while reducing time loss.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the camshaft phase angle is controlled during engine stopping period to a target phase angle, then control stability is improved, but the phase angle differs from the required phase angle for engine starting

Engineering Contradiction:

Improvecontrol stabilityVSAvoidengine startability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The control section performs preliminary phase control by rotating the camshaft to a predetermined phase angle position before the engine starting operation begins. This preliminary positioning of the camshaft ensures that when the electric motor is subsequently driven, it starts from a favorable initial position that reduces the impact of static friction and minimizes hunting, thereby improving control stability while reducing time loss.

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

The solution ensures improved control responsiveness and stability of the phase-change control system during engine starting, reducing time loss and oscillations, and enhancing the overall engine startability and efficiency.

Implementation Method 1

an electric motor which rotates together with the drive rotary member and to which electric current is supplied via brushes

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a detection section configured to detect a rotational position of the camshaft

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS8868316B2Controller of valve timing control apparatus and valve timing control apparatus of internal combustion engine

Publication Date: 2014.10.21 ASTEMO LTD

AI summary

In a valve timing control apparatus configured to execute phase-control via a phase converter, a controller is configured to control a phase angle of a camshaft relative to a crankshaft during an engine stopping period to a target phase angle differing from a required phase angle suited for an engine operating condition. The controller is further configured to change the phase angle of the camshaft toward the required phase angle during a time period from a point of time when cranking starts to a point of time when detection of a rotational position of the camshaft initiates during an engine restarting period. The controller is still further configured to start feedback-control for the phase angle of the camshaft from the point of time of initiation of detection of the rotational position of the camshaft for bringing the phase angle of the camshaft closer to the required phase angle.