Variable Valve Actuation Device Hydraulic Pressure Control
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Solution Overview
Problem
Existing variable valve actuation mechanisms for internal combustion engines face instability and noise issues when switching between valve rest and operating states, particularly due to uncontrolled hydraulic pressure and potential wedging or abrupt closure of engine valves.
Innovation Solution
A variable valve actuation device with a switching member and valve rest chamber, where communication between the valve rest passage and chamber is controlled to prevent unstable transitions, using a switching pin and compression coil spring for smooth state changes, and a valve operating chamber for enhanced responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hydraulic pressure is commonly controlled for multiple cylinders, then the control system is simplified, but the valve lifter may experience unstable transitions and noise when switching between valve rest state and operating state
Solution Approach 1:
The hydraulic pressure control system is segmented by providing separate hydraulic passages for each cylinder (first hydraulic passage for first cylinder, second hydraulic passage for second cylinder). This allows independent control of hydraulic pressure in each cylinder, enabling stable valve lifter transitions without compromising system simplicity, thus resolving the contradiction between device complexity and reliability.
2Productivity
If hydraulic pressure is switched while valve lifter is moving, then the valve rest state and operating state can be changed, but the slide pin may not move stably causing abrupt valve closure or wedging
Solution Approach 1:
The system performs preliminary action by controlling hydraulic pressure to move the slide pin to the appropriate position (first position for valve opening, second position for valve closing) before the valve lifter completes its movement. This ensures the slide pin is already in the correct position when the valve lifter arrives, preventing unstable transitions, abrupt closure, or wedging, thus resolving the contradiction between productivity and reliability.
3Productivity
If the valve lifter moves upward or downward under compressive load during pressure switching, then state changes occur, but noises may be generated and component durability may be adversely affected
Solution Approach 1:
The system performs preliminary action by advancing the slide pin position change before the valve lifter completes its movement under compressive load. The slide pin is positioned in advance to match the valve lifter's position, ensuring smooth engagement or disengagement without impact, noise, or component damage, thus resolving the contradiction between productivity and harmful factors.
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 stable and noise-free switching between valve rest and operating states, improving durability and operational smoothness by controlling the transition process and maintaining hydraulic pressure consistency.
Implementation Method 1
a switching member (53) provided in the valve lifter so as to be movable under hydraulic pressure between a valve operating position where the switching member engages an end surface of the valve stem
Implementation Method 2
using a switching pin and compression coil spring for smooth state changes
Data Source
AI summary
A variable valve actuation device includes a plurality of valve lifter. Each valve lifter slidable in a lifter support hole between an upper position and a lower position. A valve rest recess communicating with a valve rest chamber opens out at an outer circumferential surface of the valve lifter, and a valve rest supply port of a valve rest passage opens out at an inner circumferential surface of the lifter support hole in such a positional relationship that the valve rest passage and the valve rest chamber communicate with each other when the valve lifter is at the upper position, and continue to communicate with each other until the valve lifter has moved downward to a shut-off position located at a prescribed part of a down stroke from the upper position. The communication between the valve rest passage and the valve rest chamber shut off at the shut-off position.