Preloaded Torsional Biasing Device for VCT Camshaft Positioning

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Solution Overview

Problem

Variable camshaft timing (VCT) devices face inefficiencies when the angular position of the camshaft unintentionally remains advanced or retarded relative to the crankshaft, leading to suboptimal engine performance, and existing solutions either rigidly lock the rotor and stator or lack a mechanism to return the camshaft to a mid-position without locking.

Innovation Solution

A biasing assembly comprising a torsional biasing element and a rigid element, which are angularly displaced from a resting to a pre-loaded position to inhibit movement away from a default mid-position, using a receiving feature to couple the elements and resist rotational forces, allowing the camshaft to return to a mid-position without rigid locking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a VCT device uses a torsional biasing element to return the camshaft to mid-position, then the camshaft can return to default position without rigid locking, but the device complexity increases due to additional components

Engineering Contradiction:

Improvecamshaft return to mid-positionVSAvoidbiasing assembly structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The biasing assembly is nested within the VCT device housing, with the torsional biasing element positioned inside the rotational member assembly. The rigid element is integrated into the housing structure, creating a compact nested configuration that adds the return function without significantly increasing external dimensions or overall complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The rigid element acts as an intermediary component that couples the torsional biasing element to the rotational member. This mediator transfers the biasing force from the torsional element to the camshaft mechanism, enabling the return function while maintaining structural integrity and reducing the complexity of direct connections.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the VCT device rigidly locks the rotor and stator to prevent unintended angular position, then the camshaft position is fixed, but the device loses the ability to return to mid-position dynamically

Engineering Contradiction:

Improvecamshaft position stabilityVSAvoiddynamic position adjustment

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The biasing assembly introduces dynamic characteristics to the VCT device by replacing rigid locking with a spring-based torsional element. This allows the camshaft to dynamically return to the mid-position based on actuator failures or control commands, providing adaptive position control while maintaining stability through the biasing force.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The torsional biasing element changes the mechanical parameter of the system from fixed rigid connection to elastic torsional connection. This parameter change enables the system to transition between locked and returned states, providing both stability when needed and adaptability when the actuator is not functional.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the camshaft angular position varies significantly to improve engine performance, then the range of authority increases, but the risk of unintended advanced or retarded position increases

Engineering Contradiction:

Improveengine performance rangeVSAvoidcamshaft position control

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The torsional biasing element provides preliminary anti-action by pre-loading the system in the mid-position. This pre-biasing creates a restoring force that opposes any unintended angular displacement, automatically counteracting potential position drift before it becomes a problem, thus maintaining reliability across the full range of authority.

Inventive Principle:

Principle #9Preliminary anti-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 biasing assembly effectively maintains the camshaft at a mid-position relative to the crankshaft, ensuring efficient engine operation even when the actuator is not functional, by resisting rotational forces and urging the rotor and stator to return to the default position, thus preventing unintended angular displacement.

Implementation Method 1

a torsional biasing element that is elongated and configured to engage and receive rotational motion from one of a rotor or stator of the VCT device

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10648376B2Preloaded torsional biasing device

Publication Date: 2020.05.12 BORGWARNER INC

AI summary

A biasing assembly used with a VCT device includes a torsional biasing element that is elongated and configured to engage and receive rotational motion from one of a rotor or stator of the VCT device; a rigid element that is configured to engage the other of the rotor of the stator of the VCT device and be inserted within a cavity of a camshaft with the torsional biasing element; a receiving feature that couples the rigid element to the torsional biasing element and inhibits angular movement of the rotor and the stator away from a default angular position, wherein the torsional biasing element and the rigid element are angularly displaced from a resting position to a pre-loaded position when the torsional biasing element and the rigid element engage the rotor and the stator.