Gate valve capable of enhancing accuracy in operation

A gate valve comprising:

• a valve base including a valve port, a shaft hole, a receiving chamber, a first piston trough, and a second piston trough, an axial direction of the shaft hole being vertical to an opening direction of the valve port, the receiving chamber being located between the valve port and the shaft hole, the first piston trough being arranged adjacent to the shaft hole and an axial direction of the first piston trough being vertical to the opening direction of the valve port, the second piston trough being arranged adjacent to the receiving chamber and an axial direction of the second piston trough being vertical to the opening direction of the valve port, the valve base further including a fluid gateway, a fluid inlet, a fluid outlet, a first flow channel communicating with the fluid gateway, a second flow channel communicating with the first flow channel, a third flow channel communicating with the first flow channel, a fourth flow channel communicating with the third flow channel, a fifth flow channel communicating with the fourth flow channel and the fluid outlet, a sixth flow channel communicating with the fluid inlet, and a seventh flow channel communicating with the sixth flow channel, wherein each of the first flow channel, the second flow channel, the third flow channel, the fourth flow channel, the fifth flow channel, the sixth flow channel, and the seventh flow channel is configured for passage of a fluid;
• a first piston unit including a first piston, a first piston shaft, and a transmission base, the first piston being movably disposed in the first piston trough of the valve base, one end of the first piston and one end wall of the first piston trough forming a first chamber communicating the second flow channel, such that the first piston is driven by the fluid entering the first chamber to move towards the valve port along the axial direction of the first piston trough, an outer surface of the first piston and a periphery wall of the first piston trough forming a second chamber communicating with the seventh flow channel, such that the first piston is driven by the fluid entering the second chamber to move away from the valve port along the axial direction of the first piston trough, the first piston shaft being partially exposed outside the receiving chamber and having one end thereof connected with the first piston, such that the first piston shaft is driven by the first piston to move reciprocatedly along the axial direction of the first piston trough, the transmission base being disposed in the receiving chamber of the valve base in a way that the transmission base is movable along the axial direction of the first piston trough and connected with the first piston shaft in a way that the transmission base is movable along the axial direction of the second piston trough, such that the transmission base is driven by the first piston shaft to move reciprocatedly along the axial direction of the first piston trough;
• a second piston unit including a second piston shaft and a second piston, the second piston shaft being inserted into the transmission base and allowing the transmission base to move along the axial direction of the first piston trough, the second piston being movably disposed in the second piston trough of the valve base and connected with the second piston trough, two end surfaces of the second piston and two end walls of the second piston trough forming a third chamber communicating with the fourth flow channel and a fourth chamber communicating with the sixth flow channel, respectively, such that the second piston is driven by the fluid entering the third chamber to push the transmission base through the second piston shaft away from the first piston shaft along the axial direction of the second piston trough, and driven by the fluid entering the fourth chamber to push the transmission base through the second piston shaft towards the first piston shaft along the axial direction of the second piston trough;
• a valve door unit including a pivot base, a driving shaft, and a valve door, the pivot base being movably disposed in the shaft hole of the valve base, the driving shaft being fixed to the transmission base and having one end thereof penetrating into the shaft hole of the valve base and pivoted to the pivot base, such that the driving shaft is moved synchronously with the transmission base, the valve door being connected with the driving shaft, such that the valve door is moved through an axial movement of the driving shaft between a first position where the valve port is opened and a second position where the valve port is covered, and moved through a pivot movement of the driving shaft between the second position and a third position where the valve port is sealed;
• and
• a flow channel switch disposed in at least one of a junction of the third and fourth flow channels and a junction of the sixth and seventh flow channels, and allowing the fluid to pass through when turned on.