Double-layer sealing knife gate valve capable of adjusting pressure of valve cavity

The utility model discloses a double-layer sealing knife gate valve with adjustable valve cavity pressure, which comprises a valve body, a gate plate, a valve rod, a valve cavity, a cover plate, a driver, a first sealing layer and a second sealing layer, the gate plate is arranged in a valve body channel, the bottom of the valve cavity is arranged at the upper part of the valve body, and the driver drives the valve rod to drive the gate plate to move up and down in the valve body channel. The first sealing layer is arranged on the contact portion of the lower end of the valve cavity and the gate plate, the second sealing layer is arranged on the contact portion of the upper end of the valve cavity and the valve rod, the valve cavity, the first sealing layer, the second sealing layer and the cover plate define a closed cavity, and a ventilation opening is formed in the cover plate and connected with an air pressure adjusting device through a pipeline. And the pressure in the closed cavity is adjusted. The seco