Valve Timing Controller Asymmetric Spiral Spring Engagement

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Solution Overview

Problem

Existing valve timing controllers face issues with the disengagement and displacement of the inner end of the biasing member due to centrifugal force, leading to deviations in torque characteristics and increased complexity and size.

Innovation Solution

A valve timing controller design featuring a spirally shaped biasing member with its inner end engaged with an engage groove and outer end with an engaging portion, where the most outer imaginary circle is eccentric to the most inner circle by a specified amount, ensuring the inner end remains engaged and resistant to radial displacement, maintaining accurate torque characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a spiral biasing member with large clearance is used, then the biasing member can be engaged with the groove, but the inner end may be disengaged or displaced due to centrifugal force

Engineering Contradiction:

Improveengagement of biasing memberVSAvoidretention of inner end position

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies asymmetry by making the wire cross-section of the spiral biasing member asymmetric (rectangular or elliptical cross-section instead of circular). This asymmetric shape creates different clearance gaps in different directions, with smaller clearance in the radial direction to prevent disengagement and displacement under centrifugal force, while maintaining adequate clearance in other directions for proper engagement and operation.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent applies local quality by varying the clearance characteristics of the biasing member locally. The wire cross-section is designed with different dimensions in different directions (e.g., wider in tangential direction, narrower in radial direction), creating direction-dependent clearance gaps. This allows the biasing member to have appropriate clearance for engagement while preventing radial displacement at critical locations.

Inventive Principle:

Principle #3Local quality

2Reliability

If the outer diameter of the spiral biasing member is increased for engagement, then the biasing member can be engaged with the pin, but the radial size and overall size of the valve timing controller become larger

Engineering Contradiction:

Improveengagement capabilityVSAvoidsize of valve timing controller

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent reduces the overall radial size by using an asymmetric wire cross-section that provides adequate engagement capability only in the necessary direction. The rectangular or elliptical cross-section allows the biasing member to engage properly with the groove and pin while having a smaller outer diameter compared to a circular cross-section with equivalent engagement strength in all directions.

Inventive Principle:

Principle #4Asymmetry

3Reliability

If additional pins are provided for engaging the inner end of the biasing member, then the engagement is more secure, but the number of parts increases

Engineering Contradiction:

Improveengagement securityVSAvoidnumber of parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the engagement function from separate pins and integrates it into the groove structure itself. The asymmetric wire cross-section of the biasing member is designed to engage directly with the groove formed in the boss of the vane rotor, eliminating the need for additional pins while maintaining secure engagement. This reduces the number of parts while achieving the same or better engagement reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

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 restricts disengagement and displacement of the inner end of the biasing member, maintaining high operation accuracy and simplifying the configuration by eliminating the need for additional pins, while reducing the risk of torque characteristic deviations and enhancing fatigue resistance.

Implementation Method 1

The biasing member is spirally shaped by winding a wire and biases the vane rotor in the advance direction or the retard direction relative to the housing

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The vane rotor rotates along with the other of the driving shaft and the driven shaft around a center axis of the cylindrical portion in a retard direction or an advance direction relative to the housing according to a hydraulic pressure in the retard chamber and the advance chamber

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Gradient

Data Source

PatentUS9062573B2Valve timing controller

Publication Date: 2015.06.23 DENSO CORP

AI summary

A valve timing controller has a spiral spring biasing a vane rotor in an advance direction. An inner end and an outer end of the spring are respectively engaged with an engage groove and an engage pin in such a manner that a center of a most inner imaginary circle passing through a center line of the wire is apart from a center of a most outer imaginary circle passing through both the center line of the wire and an engage point between the inner end and the engage groove. The most outer imaginary circle is eccentric to the most inner imaginary circle by a specified amount.