| 摘要 |
A fluid flow control valve uses a servo valve to control the pressure in a main diaphragm chamber defined by a main diaphragm. The main diaphragm carries a main valve element that assumes either a low flow or a high flow position relative to a valve seat depending on which of two states the servo valve is in. When the servo valve is in the one of the two states creating the low flow position of the main valve element, the main diaphragm chamber pressure is regulated by a pressure divider comprising two flow restrictors in series connection between the inlet and outlet chambers of the valve. When in the other of the two states, the servo valve disables the pressure divider and allows the main diaphragm chamber pressure to reach the outlet pressure. The disclosure shows two versions of the invention. One version of the valve enters its low flow state when the servo valve is closed, and the other when its servo valve is open.
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