Vertical self-priming pump

A vertical self-priming pump, comprising

• a pump body, wherein an inner cavity of the pump body is divided into a gas-liquid separation chamber and a liquid storage chamber through a middle partition plate that is provided with an axial inlet opening, and the gas-liquid separation chamber is above the liquid storage chamber;
• a flow guide body is fixed on an upper surface of the middle partition plate;
• the flow guide body is provided with an axial through hole and a radial flow guide hole that is in communication with the axial through hole, and the gas-liquid separation chamber is in communication with the liquid storage chamber through the axial inlet opening and the radial flow guide hole on the flow guide body;
• a motor, which is fixed on the top of the pump body for driving a pump shaft to rotate, and the pump shaft downwardly penetrates into the inner cavity of the pump body, and an impeller that is arranged in the axial through hole of the flow guide body is fixed on a lower end of the pump shaft;
• a backflow gap channel is formed between an outer circumferential surface of the impeller and an inner wall of the axial through hole of the flow guide body;
• a medium backflow blocking device that comprises a static ring and a moving ring which are vertically and oppositely arranged as well as an elastic supporting sleeve;
• the moving ring is embedded on an upper surface of the impeller, and an outer edge of the elastic supporting sleeve extends downwards to form a supporter that is fixed on an upper surface of the flow guide body;
• the static ring is embedded on a lower surface of an elastic supporting ring, and a lower end surface of the static ring protrudes the lower surface of the elastic supporting sleeve, and a gap is formed between a lower end surface of the static ring and an upper end of the moving ring;
• and
• a flow-blocking depressurization plate;
• wherein an upper part of the impeller is in a step axle shape with a top part smaller than a lower part, and the flow-blocking depressurization plate is in a step sleeve shape with top part bigger than the lower part and provided with an axle hole;
• the flow-blocking depressurization plate is vertically sleeved on the impeller with a big-diameter part fixed on the flow guide body;
• a backflow gap channel is formed by the gap between inner wall of the axle hole of the flow-blocking depressurization plate and outer circumferential surface of a small-diameter part of the impeller and a gap between the lower end surface of the flow-blocking depressurization plate and step surface of the impeller.