Variable Valve Timing Torsion Spring Stability

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Solution Overview

Problem

The existing variable valve timing control apparatuses, such as those described in Japanese Patent Provisional Publication No. 2005-180378, face instability in the attitude of the torsion spring due to a smaller angle between the vane rotor and the torsion spring ends, leading to potential instability in the spring force acting on the vane member.

Innovation Solution

The apparatus includes a housing with working fluid chambers, a vane member that divides these chambers, and a torsion spring where one end is retained by the housing and the other end by the vane member, with the angle between the torsion spring ends adjusted to range from one side of 180° to the other, ensuring stability by maintaining the torsion spring in an upright position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the torsion spring is configured with an angle of 120° or less between its ends and the vane rotor, then the spring can be compactly arranged, but the attitude of the torsion spring becomes unstable and it may tip to one side

Engineering Contradiction:

Improvecompact arrangement of torsion springVSAvoidattitude stability of torsion spring

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The patent changes the critical parameter of the torsion spring angle from 120° or less to more than 180°. This parameter change transforms the unstable small-angle configuration into a stable obtuse-angle configuration, where the spring ends are positioned on substantially opposite sides of the vane rotor, preventing the spring from tipping while maintaining compact arrangement.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the torsion spring angle is increased to improve stability, then the attitude stability improves, but the space required for the spring increases

Engineering Contradiction:

Improveattitude stability of torsion springVSAvoidspace occupied by torsion spring

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

The patent positions the torsion spring ends on substantially opposite sides of the vane rotor, creating a balanced, equipotential configuration. This symmetric arrangement distributes forces evenly and prevents lateral tipping, achieving stability without requiring excessive space, as the spring utilizes the available radial space efficiently.

Inventive Principle:

Principle #12Equipotentiality

3Device complexity

If the torsion spring is positioned at a small angle to the vane rotor, then the component layout is simplified, but the spring force cannot act on the vane member with stability

Engineering Contradiction:

Improvecomponent layout complexityVSAvoidreliability of spring force application

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the angular parameter from a small angle (120° or less) to an obtuse angle (more than 180°). This parameter change ensures that the torsion spring exerts reliable, stable force on the vane member while preventing the spring from tipping, thereby maintaining simple component layout without sacrificing reliability.

Inventive Principle:

Principle #35Parameter changes

4Stability of the object's composition

If the torsion spring angle is set to exactly 180°, then the spring achieves maximum stability, but the design flexibility is reduced

Engineering Contradiction:

Improveattitude stability of torsion springVSAvoiddesign flexibility of torsion spring configuration

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent employs asymmetric design by allowing the torsion spring angle to range from more than 180° to a maximum of 270°, rather than fixing it at exactly 180°. This asymmetric range provides design flexibility to accommodate different space constraints and operational requirements while maintaining stability through the obtuse-angle configuration.

Inventive Principle:

Principle #4Asymmetry

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 configuration maintains the torsion spring's attitude in a stable upright position, ensuring consistent spring force application to the vane member and preventing unintended detachment, while reducing component count and complexity.

Implementation Method 1

a torsion spring, one end of which is retained by the housing and the other end of which is retained by the vane member

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9004025B2Variable valve timing control apparatus of internal combustion engine

Publication Date: 2015.04.14 ASTEMO LTD

AI summary

A variable valve timing control apparatus has a housing having a plurality of working fluid chambers, a vane member rotatably housed in the housing and dividing the each working fluid chamber into advance and retard oil chambers, the vane member rotating to a most-advanced angle side and to a most-retarded angle side within a predetermined angle range relative to the housing, and a torsion spring, one end of which is retained by the housing and the other end of which is retained by the vane member. When the vane member rotates to the most-advanced angle side and to the most-retarded angle side, an angle formed by a line connecting the both ends of the torsion spring through an axial center of the vane member ranges from an angle positioned at one side to an angle positioned at the other side of a boundary with 180° being the boundary.