Poppet Valve Reduction Passage for Stable Stroke at Sonic Flow
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Solution Overview
Problem
The capacity control valve in existing systems experiences variations in valve stroke due to the influence of discharge pressure, leading to offsetting of the valve opening degree from the target value, especially when the fluid flows at a speed close to the speed of sound.
Innovation Solution
A valve design that includes a poppet valve with a valve seat and a valve body, where a flow passage downstream of the poppet valve features a reduction region with a decreasing cross-sectional area, stabilizing the pressure and flow speed to improve controllability and accuracy in valve opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a poppet valve is used to control fluid flow rate by opening and closing between control port and suction port, then the flow rate can be reduced, but the valve stroke varies due to discharge pressure influence, causing the opening degree to offset from target value
Solution Approach 1:
A pressure control chamber is introduced as an intermediary between the discharge port and the poppet valve. This chamber receives high-pressure fluid from the discharge port and uses it to apply a closing force to the poppet valve, counterbalancing the opening force from suction pressure. This mediator mechanism allows precise control of the poppet valve opening degree despite variations in suction pressure or flow rate.
Solution Approach 2:
The invention changes the pressure parameter by introducing a pressure control chamber that maintains a specific pressure level (higher than suction pressure but controlled to be lower than or equal to discharge pressure). By controlling the pressure in this intermediate chamber, the poppet valve's opening degree can be precisely regulated, converting the uncontrolled flow rate variation into a controlled pressure-based actuation mechanism.
2Reliability
If discharge pressure is constantly supplied through an orifice to adjust control pressure, then control pressure can be maintained, but it causes variation in valve stroke and offsets opening degree from target value
Solution Approach 1:
The invention applies different pressure qualities to different parts of the system. The pressure control chamber receives high-pressure fluid from the discharge port specifically for the purpose of applying closing force to the poppet valve, while the suction pressure is allowed to vary naturally to drive the fluid flow. This local differentiation of pressure functions allows the system to maintain control pressure stability while achieving precise valve stroke control.
Solution Approach 2:
The system dynamically balances two opposing forces on the poppet valve: the opening force from suction pressure and the closing force from the pressure control chamber. By making the pressure in the control chamber variable (adjustable between suction pressure and discharge pressure), the system can dynamically compensate for changes in flow conditions, maintaining accurate valve opening degree control under varying operating conditions.
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 valve design enhances controllability by ensuring accurate adjustment of the poppet valve opening degree, reducing variations in valve stroke, and stabilizing fluid pressure, even under varying flow conditions.
Implementation Method 1
a spring that urges the valve body in a direction opposite a direction of driving by the drive source
Implementation Method 2
a flow passage on a downstream side of the poppet valve is provided with a reduction region where a flow passage cross-sectional area tends to decrease toward a downstream side. When a fluid passing through the poppet valve flows at a supersonic speed, the fluid that has passed through the reduction region in the flow passage on the downstream side of the poppet valve decreases in flow speed, and the downstream pressure of the poppet valve increases
Data Source
AI summary
A valve includes a valve housing provided with an inlet port and an outlet port; a valve body configured to be driven by a drive source; a spring that urges the valve body in a direction opposite a direction of driving by the drive source. A valve seat is formed at an edge of a through-flow passage. The valve body and the valve seat forms a poppet valve that controls a flow rate in accordance with a movement of the valve body. A flow passage on a downstream side of the poppet valve is provided with a reduction region where a flow passage cross-sectional area tends to decrease toward a downstream side.