Pilot-Controlled Flow Rate Valve for Low-Power Pressure Isolation
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Solution Overview
Problem
Existing electrically-driven flow rate control valves require high electric power to maintain valve position due to increased driving force needed as fluid pressure rises, and suffer from positional accuracy fluctuations due to spring and actuator hysteresis, leading to increased power consumption.
Innovation Solution
The design incorporates a sub valve body controlled by an electric motor, with first and second flow rate adjusting mechanisms in communication passages to manage fluid pressure, preventing high pressure from directly affecting the sub valve body and allowing precise positioning, thus reducing the need for high driving forces and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve body is kept at a predetermined position by a driving force generated by an electric motor, then the valve position is maintained, but a large electric power is required when fluid pressure rises
Solution Approach 1:
A pilot valve element is introduced as an intermediary component that controls the main valve body indirectly. The pilot valve element responds to fluid pressure changes and controls the flow of pilot fluid, which in turn actuates the main valve body. This intermediary mechanism allows the main valve to respond to pressure changes automatically without requiring proportional electric power increases.
Solution Approach 2:
The invention utilizes hydraulic principles by employing pilot fluid pressure to control the main valve body position. The pilot fluid system translates small pressure changes into proportional main valve positioning, replacing the need for direct electric motor force proportional to fluid pressure. This hydraulic amplification mechanism efficiently controls high-pressure fluid flow with minimal electric power.
2Ease of operation
If the position of the pilot valve element is controlled by the first disk spring and the actuator, then the valve can operate, but the positional accuracy of the valve element tends to fluctuate due to hysteresis
Solution Approach 1:
The pilot valve element positioning incorporates a feedback mechanism where the actual position of the pilot valve element influences the pilot fluid pressure, which in turn adjusts the main valve body position. This feedback loop compensates for hysteresis effects in the disk spring and actuator, maintaining positional accuracy by continuously adjusting based on actual system state rather than relying solely on open-loop actuator commands.
3Reliability
If the valve is closed and oil pressure directly acts on the pilot valve element, then the valve closes, but the actuator requires a large driving force which increases electric power consumption
Solution Approach 1:
The pilot valve element serves as an intermediary that isolates the actuator from direct exposure to high main valve closing pressures. Instead of the actuator directly opposing high oil pressure on the main valve, it controls pilot fluid pressure that indirectly actuates the main valve. This pressure isolation significantly reduces the driving force required from the actuator while maintaining reliable valve closing function.
Data Source
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AI summary
Provided is an electrically-driven flow rate control valve capable of controlling a flow rate of a fluid flowing between two inlet/outlet ports, restraining a high pressure of the fluid from being applied to a sub valve body connected to an electric motor. The flow rate control valve has a casing, a raising/lowering drive device, a supply-switching valve, a main valve body, a valve-closing spring. When the electric motor of the raising/lowering drive device moves the sub valve body upward, oil of a back pressure chamber is discharged from a discharge oil passage through a sub valve body communication port and a sub valve body oil passage to open the main valve body. When the main valve body is closed, a pressure of the back pressure chamber is inhibited from being directly applied to a lower end face of the sub valve body.