SM-A20758-A/3 7. References
62 2020-10-06
・Pressure control diagram
◼ EVD-1000
The EVD-1000 series includes the pilot control section described above and a booster section for
improving the flow characteristics. The booster section includes air supply and exhaust valves and a
diaphragm for opening and closing them. The exhaust valve is connected to the diaphragm. The lower
chamber of the diaphragm has the same pressure as the controlled pressure. The upper chamber
controls the pilot pressure by PWM-driving the solenoid valve. This difference in pressure moves the
diaphragm up and down to open and close the valve.
The EVD-1000 series senses the controlled pressure with a pressure sensor to constantly adjust the
pilot pressure as follows for high-precision pressure control:
When the set pressure is lower than the controlled pressure, that is, the controlled pressure is to be
boosted, the pilot pressure is controlled to achieve the following state:
Upper chamber pressure (pilot pressure) > Lower chamber pressure (controlled pressure)
When the set pressure is higher than the controlled pressure, that is, the controlled pressure is to be
reduced, the pilot pressure is controlled to achieve the following state:
Upper chamber pressure (pilot pressure) > Lower chamber pressure (controlled pressure)
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