Camshaft Lubrication Structure for Variable Valve Timing

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Solution Overview

Problem

The lubrication of a camshaft with variable valve timing is insufficient at the initial stage of cold starting or engine idling, leading to potential damage from the sprocket load due to inadequate lubrication, causing adherence issues.

Innovation Solution

The proposed lubrication structure includes an advance hole, a retard hole, and a divergence flow passage or hole in the camshaft and cylinder head, which ensures that the lubrication film is maintained by supplying oil from the retard hole to the counter bore and slip surfaces, preventing film breakdown under sprocket load during cold starting or idling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the advance hole is formed in the camshaft body near the sprocket to supply oil for lubrication, then the camshaft can be lubricated during normal operation, but insufficient lubrication occurs at the initial stage of cold starting or engine idling due to inadequate oil pressure

Engineering Contradiction:

Improvelubrication reliabilityVSAvoidoil supply quantity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent introduces a divergence flow passage that diverts oil flow from the retard hole to the counter bore and slip surface before the main load is applied. This preliminary oil supply action ensures that the lubrication film is formed in advance, preventing adherence when the sprocket load is applied during cold starting or idling conditions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The divergence flow passage acts as an intermediary pathway that redirects oil flow from the retard hole to the counter bore and slip surface. This intermediary structure ensures that oil is supplied to the critical lubrication areas even when the main oil pressure is insufficient during cold starting or idling operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If the lubrication film is broken by sprocket load during cold starting or idling, then the camshaft journal may be damaged, but providing sufficient lubrication prevents adherence and damage

Engineering Contradiction:

Improvecamshaft journal strengthVSAvoidadherence damage

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The divergence flow passage provides preliminary oil supply to the counter bore and slip surface before the sprocket load is applied. This ensures that the lubrication film is already formed and protective, preventing the harmful adherence effect that would otherwise damage the camshaft journal during cold starting or idling.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a cushioning lubrication film in advance through the divergence flow passage, which protects the camshaft journal from the harmful effects of sprocket load during cold starting or idling. This beforehand lubrication prevents the adherence damage that would occur without the protective film.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If oil pressure is insufficient during cold starting or idling, then lubrication is inadequate, but the divergence flow passage ensures continuous lubrication film formation

Engineering Contradiction:

Improvelubrication continuityVSAvoidoil pressure

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The divergence flow passage serves as an intermediary oil delivery pathway that operates independently of the main oil pressure system. It redirects oil from the retard hole to the counter bore and slip surface, ensuring continuous lubrication film formation even when overall oil pressure is insufficient during cold starting or idling conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution provides sufficient lubrication to the camshaft at initial stages, preventing damage and adherence by ensuring continuous lubrication film formation, even when oil pressure is insufficient, thus maintaining engine performance and preventing camshaft journal damage.

Implementation Method 1

supplying oil from the retard hole to the counter bore and slip surfaces, preventing film breakdown under sprocket load

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS7322327B1Lubrication structure of camshaft with variable valve timing

Publication Date: 2008.01.29 HYUNDAI MOTOR CO LTD

AI summary

A lubrication structure for a camshaft with variable valve timing includes an advance hole, which includes an advance flow passage formed in a camshaft body. An end of the camshaft is attached to a continuously variable valve timing. A retard hole, which includes a retard flow passage, is formed in the camshaft body and spaced horizontally from the advance hole. A divergence flow passage has an end that surface-contacts the camshaft and is extended to communicate with the retard hole at an upper surface of a mounting part of a cylinder head. The other end of the divergence flow passage communicates with the slip surface on which the camshaft lays via a counter bore, so as to prevent lubrication film from being broken by load of the sprocket at an engine idle state or at an initial stage of cold starting.