Valve Timing Control Using Mechanical Lock Pin
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Solution Overview
Problem
Existing valve timing control apparatuses for internal combustion engines require hydraulic pressure to maintain valve timing at the retardation angle position during automatic engine stop, necessitating an additional hydraulic pressure source.
Innovation Solution
A valve timing control apparatus that includes a housing with a working oil chamber partitioned into advance and retardation angle hydraulic pressure chambers, a vane member on the camshaft, and lock members to hold the vane member at specific positions without relying on hydraulic pressure, using a phase modification mechanism and lock recess sections to limit the vane member's movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic pressure is used to hold the valve timing at the retardation angle position during automatic engine stop, then the valve timing can be maintained, but an additional hydraulic pressure source is required
Solution Approach 1:
The patent replaces the hydraulic pressure-based timing maintenance system with a mechanical lock pin mechanism. The lock pin physically engages with lock holes in the camshaft to hold the valve timing at the retardation angle position during automatic engine stop, eliminating the need for additional hydraulic pressure sources while maintaining reliable timing control.
2Reliability
If the valve timing is held at the intermediate phase position during engine start, then the engine startability is improved, but the valve timing control requires precise positioning
Solution Approach 1:
The patent divides the camshaft into multiple discrete positioning sections with lock holes at specific angular positions. The lock pin can engage with different lock holes to hold the camshaft at predetermined timing positions (intermediate phase position for engine start, retardation angle position for automatic stop), providing precise positioning through discrete mechanical engagement points rather than continuous hydraulic control.
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
Enables the valve timing to be held at the retardation angle position independently of hydraulic pressure, improving engine startability and reducing vibrations during engine restart, while eliminating the need for an additional hydraulic pressure source.
Implementation Method 1
relatively revolves toward an advance angle side to the housing and toward a retardation angle side to the housing by selectively supplying and exhausting a working oil to and from the advance angle hydraulic pressure chamber and the retardation angle hydraulic pressure chamber
Data Source
AI summary
In a valve timing control apparatus of an internal combustion engine, a first lock member is installed axially movably on either one of a housing and a vane member, a first lock recess section with which the first lock member is engaged when the vane member is relatively revolved at an intermediate phase position between most advance and retardation angle sides is installed on the other of the housing and the vane member, and a third lock recess section is installed at a retardation angle side in a circumferential direction of the housing with respect to the first lock recess section to limit a relative rotary position of the vane member at the most retardation angle side by an engagement of the first lock member with the third lock recess section.