Pump device and pump system

Abstract

To provide a pump device capable of limiting discharge of a fluid when the operation is stopped. A pump device ( 3 ) includes a casing ( 10 ), a movable member ( 30 ), a suction valve ( 41 ), a discharge valve ( 42 ), and a valve mechanism ( 50 ). The casing ( 10 ) includes a suction port ( 101 ), a discharge port ( 102 ), and a pump chamber ( 100 ). The movable member ( 30 ) is movable within the casing ( 10 ) and alternately performs suction and discharge of a fluid into and from the pump chamber ( 100 ). The discharge valve ( 42 ) is attached between the pump chamber ( 100 ) and the discharge port ( 102 ) and permits the fluid having a first pressure or higher to flow. The valve mechanism ( 50 ) is attached to the casing ( 10 ) and limits a flow of the fluid having a second pressure or lower.

1 . A pump device, comprising:
 a casing including
 a suction port, a discharge port, and a pump chamber that can communicate with the suction port and the discharge port; 
   a movable member that is movable within the casing and alternately performs suction of a fluid into the pump chamber and discharge of the fluid from the pump chamber;   a first valve that is attached between the suction port and the pump chamber and permits the fluid to flow from the suction port to the pump chamber;   a second valve that is attached between the pump chamber and the discharge port and permits the fluid to flow from the pump chamber to the discharge port in a case where the fluid of the pump chamber has a first pressure or higher; and   a third valve that is attached to the casing and limits a flow of the fluid toward the discharge port from the suction port in a case where the fluid between the suction port and the discharge port has a second pressure or lower, the second pressure being higher than the first pressure.   
     
     
         2 . The pump device according to  claim 1 , wherein the third valve is disposed closer to the discharge port side than the second valve. 
     
     
         3 . The pump device according to  claim 2 , wherein
 the third valve includes a valve member that continuously changes the degree of opening in accordance with a pressure equal to or higher than the first pressure and equal to or lower than the second pressure.   
     
     
         4 . The pump device according to  claim 3 , wherein the valve member is an umbrella valve. 
     
     
         5 . The pump device according to  claim 2 , wherein
 the casing further includes a space portion obtained by expanding a part of a flow path that communicates between the second valve and the third valve.   
     
     
         6 . The pump device according to  claim 1 , wherein
 the movable member includes a diaphragm that is deformable and partitions the pump chamber.   
     
     
         7 . A pump system, comprising:
 a pump device including
 a casing including
 a suction port that communicates with a pressure source, a discharge port that communicates with a process unit, and a pump chamber that can communicate with the suction port and the discharge port, 
 
 a movable member that is movable within the casing and alternately performs suction of a fluid into the pump chamber and discharge of the fluid from the pump chamber, 
 a first valve that is attached between the suction port and the pump chamber and permits the fluid to flow toward the pump chamber from the suction port, 
 a second valve that is attached between the pump chamber and the discharge port and permits the fluid having a first pressure or higher to flow toward the discharge port from the pump chamber, and 
 a third valve that is attached to the casing and limits a flow of the fluid having a second pressure or lower to flow toward the discharge port from the suction port, the second pressure being higher than the first pressure; 
   a pressure source that is connected to the suction port and supplies the fluid having the second pressure or lower to the pump device; and   a process unit that is connected to the discharge port and processes the fluid discharged from the pump device.   
     
     
         8 . The pump system according to  claim 7 , wherein
 the third valve includes a valve member that blocks the flow of the fluid having the second pressure or lower.   
     
     
         9 . The pump system according to  claim 7 , wherein
 the third valve includes a valve member that continuously changes the degree of opening in accordance with a pressure equal to or higher than the first pressure and equal to or lower than the second pressure.