Variable Valve Rocker Arm Switching With Bypass Oil Passage
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Solution Overview
Problem
Existing variable valve devices face issues with smooth switching between coupling and separation states of rocker arms, leading to potential noise generation and reduced durability due to improper synchronization with camshaft phases.
Innovation Solution
A variable valve device with a switching mechanism that includes a hydraulic piston controlled by oil pressure, featuring a first oil passage with an oil groove and a bypass passage to ensure smooth coupling and separation of rocker arms by controlling oil flow through actuation and direct passages, bypassing the oil groove when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the oil groove is used as the only oil passage for controlling the hydraulic piston, then the structure is simplified, but the rocker arm separation becomes unstable and abnormal noises occur due to improper synchronization with camshaft phases
Solution Approach 1:
The single oil groove is segmented into multiple functional oil passages: a first oil passage for supplying oil during coupling, a second oil passage for maintaining coupling state, and a bypass passage for controlled separation. This segmentation allows each passage to be optimized for its specific function, resolving the contradiction between structural simplicity and operational reliability.
Solution Approach 2:
The oil passages are designed to dynamically open and close based on camshaft rotation phase and hydraulic piston position. The second oil passage closes during backward movement to prevent premature separation, while the bypass passage opens to allow controlled oil flow. This dynamic control ensures reliable rocker arm separation synchronized with camshaft phases.
2Reliability
If the second oil passage remains open during backward movement of the hydraulic piston, then oil flow is maintained, but the rocker arms separate prematurely causing abnormal noises
Solution Approach 1:
The second oil passage operates periodically, opening during forward movement to supply oil and closing during backward movement to prevent premature separation. This periodic action is synchronized with the camshaft rotation phase, ensuring that oil flow is maintained when needed while preventing harmful effects during separation phases.
Solution Approach 2:
The bypass passage is designed to open before the second oil passage closes, allowing oil to be redirected through the bypass route in advance. This preliminary action ensures continuous oil flow while preventing the harmful effect of premature rocker arm separation, as the oil can still reach the hydraulic piston through the bypass passage.
3Device complexity
If the oil control valve controls oil pressure to both couple and separate rocker arms, then a single control system is used, but the switching timing is imprecise leading to reduced durability
Solution Approach 1:
The system uses feedback from the camshaft rotation phase and hydraulic piston position to control the opening and closing of different oil passages. The oil control valve receives feedback about the current operational state and adjusts oil flow accordingly, enabling precise switching timing while maintaining a relatively simple control system structure.
Solution Approach 2:
The multiple oil passages act as intermediaries between the single oil control valve and the hydraulic piston. Each passage is controlled to open and close at specific phases, allowing the single control valve to achieve precise timing control through the intermediary passages without requiring multiple control valves.
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 enables stable and durable operation by preventing abnormal noises and improving rocker arm separation, ensuring synchronized valve lift adjustments based on engine speed.
Implementation Method 1
a hydraulic piston configured to be moved forward and backward by the oil pressure such that the plurality of rocker arms are coupled along forward movement of the hydraulic piston, and the plurality of rocker arms are separated along backward movement of the hydraulic piston
Implementation Method 2
A part of the first oil passage is formed by an oil groove through which oil is allowed to pass at a predetermined rotation phase of the camshaft
Data Source
AI summary
A variable valve device changes a valve lift amount in a cylinder head. The device includes: a camshaft having plural cams with different valve lift amounts; plural rocker arms in contact with the plural cams to move a valve; a switching mechanism that couples and separates the rocker arms by oil pressure; and an oil control valve that controls the oil pressure. The switching mechanism includes a hydraulic piston moveable forward and backward to couple and separate the rocker arms. First and second oil passages extend from the oil control valve to the hydraulic piston. The first oil passage includes an oil groove allowing oil to pass at a predetermined rotation phase of the camshaft. The second oil passage is opened and closed during forward and backward movement of the hydraulic piston. A bypass passage is provided for bypassing the oil groove when the second oil passage is closed.