Variable Diameter Rotor Valve Timing Control
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Solution Overview
Problem
Existing valve timing control devices face challenges in ensuring adequate pressure-receiving surface areas for vanes while enlarging the relative-rotation angle of the rotor relative to the housing, leading to deteriorated conversion responsiveness.
Innovation Solution
A valve timing control apparatus with a cylindrical housing and a vane rotor featuring large and small diameter portions, along with an axially-slidable locking mechanism, to enhance pressure-receiving surface areas and rotary motion restriction, allowing for increased relative-rotation speed and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outside diameter of the rotor is expanded to ensure accommodation bores for lock pins, then the lock mechanism can be implemented, but the radial length of vanes is limited, reducing pressure-receiving surface areas and deteriorating conversion responsiveness
Solution Approach 1:
The rotor is designed with large-diameter portions and small-diameter portions at different circumferential locations. The large-diameter portions provide space for accommodation bores for lock pins, while the small-diameter portions allow vanes to extend radially outward, maximizing pressure-receiving surface areas. This local differentiation resolves the contradiction by providing different radial dimensions at different locations rather than using a uniform rotor diameter.
2Reliability
If the outside diameter of the rotor is expanded to accommodate lock pins, then the lock mechanism can be implemented, but the outside diameter of the housing also has to be expanded, increasing system size
Solution Approach 1:
The rotor's non-uniform diameter design allows lock pins to be accommodated in large-diameter portions without requiring the entire rotor and housing to be expanded. The housing maintains a compact overall size while the localized large-diameter portions of the rotor provide the necessary space for lock mechanism components.
3Length of stationary object
If the radial length of vanes is limited due to rotor diameter constraints, then the rotor can maintain a compact size, but pressure-receiving surface areas are reduced, deteriorating conversion responsiveness
Solution Approach 1:
The vanes are designed with varying radial lengths corresponding to the rotor's large-diameter and small-diameter portions. In regions where the rotor has small-diameter portions, vanes extend further radially outward, maximizing pressure-receiving surface areas. This localized variation in vane length allows the system to maintain compact overall dimensions while providing sufficient pressure-receiving area for responsive operation.
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 increases the relative-rotation speed and responsiveness of the camshaft to the crankshaft, improving valve timing control while maintaining a balanced rotor and reducing system complexity.
Implementation Method 1
phase-advance and phase-retard hydraulic chambers
Implementation Method 2
hydraulically-operated vane member equipped variable valve timing control devices
Data Source
AI summary
In a valve timing control apparatus, phase-retard and phase-advance hydraulic chambers are defined among a plurality of shoes formed in a housing and a plurality of vanes formed integral with a rotor fixed to a camshaft. The rotor has a large-diameter portion formed between a first group of adjacent vanes and a small-diameter portion formed between a second group of adjacent vanes. The innermost end of a shoe of the shoes, opposed to the outer peripheral surface of the small-diameter portion, is configured to protrude radially inward rather than the innermost end of a shoe of the shoes, opposed to the outer peripheral surface of the large-diameter portion. A lock pin is located in the large-diameter portion of the rotor, whereas a lock hole, with which the lock pin slides into and out of engagement, is located in the inner face of a sprocket.