Variable Valve Rocker-Arm Switching for Noise Reduction
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Solution Overview
Problem
Existing variable valve devices face issues with smooth switching between coupling and separation states of rocker arms due to interference with valve lift, leading to potential noise generation and reduced durability.
Innovation Solution
A variable valve device with a switching mechanism that includes a coupling piston and a separation piston, controlled by an oil control valve, allows for smooth coupling and separation of rocker arms by oil pressure at predetermined phases of the camshaft, avoiding interference with valve lift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rocker arms are coupled and separated during valve lift operation, then switching between different valve lift amounts is achieved, but interference with valve lift causes noise and reduced durability
Solution Approach 1:
The switching mechanism is designed to couple or separate the rocker arms before the valve lift operation begins. By timing the switching action to occur in advance of the valve lift phase, the mechanism avoids interference with the lifting motion, preventing noise and durability issues while maintaining the ability to switch between different valve lift amounts.
2Device complexity
If switching mechanism operates independently of camshaft phase, then结构简单化, but interference with valve lift occurs
Solution Approach 1:
The switching mechanism incorporates a phase detection system that monitors the camshaft rotation phase and provides feedback to control the timing of rocker arm coupling and separation. This feedback mechanism ensures that switching operations are synchronized with the camshaft phase, preventing interference with valve lift while maintaining relatively simple overall structure.
3Adaptability or versatility
If rocker arms switch during valve lift, then variable valve lift function is achieved, but noise generation increases
Solution Approach 1:
The switching mechanism completes the coupling or separation of rocker arms before the valve lift operation commences. By performing the switching action in advance, during a phase when the valve is not being lifted, the mechanism eliminates the source of noise generation while preserving the variable valve lift function through timely switching between different cam profiles.
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 plurality of rocker arms by oil pressure; and an oil control valve that control the oil pressure. The switching mechanism includes a coupling piston and a separation piston that are moved forward and backward by the oil pressure. The plural rocker arms are coupled to one another along forward movement of the coupling piston. The plural rocker arms are separated from one another along forward movement of the separation piston. The oil control valve moves the coupling piston forward at a predetermined rotation phase of the camshaft and moves the separation piston forward at a predetermined rotation phase of the camshaft.