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A diaphragm valve is used to perform opening/closing operations to switch between a state where two flow paths 14a and 15a communicate with each other and a state where the flow paths 14a and 14b are blocked from communicating with each other. A diaphragm unit 31 which is disposed in a valve housing

A diaphragm valve is used to perform opening/closing operations to switch between a state where two flow paths 14a and 15a communicate with each other and a state where the flow paths 14a and 14b are blocked from communicating with each other. A diaphragm unit 31 which is disposed in a valve housing 13 has a hollow valve body 32 capable of being reciprocated in the axial direction, the diaphragm unit 31 is formed with a communication flow path 32a through which two flow paths 14a and 14b are communicated with each other. A first diaphragm 34 is provided to one end portion of a hollow valve body 32, and a second diaphragm 36 is provided to the other end of the hollow valve body 32, when the hollow valve body 32 is moved in its axial direction and abuts on a valve seat portion 42, the communication flow path 32a is closed.

대표청구항 ▼

1. A diaphragm valve in which a valve body having a diaphragm is incorporated into a valve housing, and which performs opening and closing operations to switch between a state where a first flow path communicates with a second flow path and a state where the first flow path is blocked from communica

1. A diaphragm valve in which a valve body having a diaphragm is incorporated into a valve housing, and which performs opening and closing operations to switch between a state where a first flow path communicates with a second flow path and a state where the first flow path is blocked from communicating with the second flow path, the diaphragm valve comprising: a hollow valve body which is disposed so as to be capable of performing a reciprocating operation in an axial direction in the valve housing and which is formed with a communication flow path through which the first flow path and the second flow path communicate with each other;a first diaphragm which is provided to one end portion of the hollow valve body, the first diaphragm having a first mounting portion;a second diaphragm which is provided to the other end of the hollow valve body and moved in synchronization with the first diaphragm via the hollow valve body, the second diaphragm having a second mounting portion, wherein the first diaphragm, the second diaphragm and the hollow valve body collectively constitute a diaphragm unit;a case in which the diaphragm unit is accommodated, the case engaging with the first mounting portion of the first diaphragm and the second mounting portion of the second diaphragm so as to keep a distance between the first and second mounting portions constant; anda reciprocating member which is provided to the valve housing and reciprocably movable in the axial direction and coupled with hollow valve body, whereinwhen the hollow valve body is moved by the reciprocating member in a direction parallel to a moving direction of the reciprocating member, the hollow valve body abuts on a valve seat portion provided to the valve housing to close the communication flow path. 2. The diaphragm valve according to claim 1, wherein a valve seat block having the valve seat portion is provided to the valve housing. 3. The diaphragm valve according to claim 1, wherein concave surfaces of the first and second diaphragms are directed outwardly in the axial direction of the hollow valve body, and of the first and second diaphragms to have opposite relationship with each other in concavity and convexity. 4. The diaphragm valve according to claim 1, wherein the reciprocating member is a piston rod provided to a piston which is driven by a fluid pressure, and the piston is mounted in a cylinder chamber separated from a concave portion in which the diaphragm unit is accommodated. 5. The diaphragm valve according to claim 4, wherein the piston is a single-acting type piston. 6. The diaphragm valve according to claim 4, wherein the piston rod is formed into a cylindrical shape, and the piston is formed into an annular shape. 7. The diaphragm valve according to claim 1, wherein a biasing member which applies biasing force in a direction toward the valve seat portion is provided to the hollow valve body, when an opening direction thrust applied to the first diaphragm by fluid in the first flow path is larger than a closing direction thrust as the sum of a biasing force of the biasing member and a thrust applied to the second diaphragm by the pressure of fluid in the second flow path, the hollow valve body is separated from the valve seat portion to open the communication flow path, and when the opening direction thrust is smaller than the closing direction thrust, the hollow valve body abuts on the valve seat portion to close the communication flow path. 8. A diaphragm valve in which a valve body having a diaphragm is incorporated into a valve housing, and which performs opening and closing operations to switch between a state where a first flow path communicates with a second flow path and a state where a first flow path is blocked from communicating with a second flow path, the diaphragm valve comprising: a hollow valve body which is disposed so as to be reciprocally movable in an axial direction in the valve housing, and which is formed with a communication flow path through which the first flow path and the second flow path communicate with each other;a first diaphragm which is provided to one end portion of the hollow valve body;a second diaphragm which is provided to the other end of the hollow valve body and moved in synchronization with the first diaphragm via the hollow valve body;a valve seat block which has a first conical projection projecting into the communication flow path and a second conical projection projecting into the first flow path, and which is provided to the valve housing;a guide member which is attached to the hollow valve body; anda case which is accommodated in the valve housing, and which guides movement of the hollow valve body in the axial direction by guiding movement of the guide member, wherein an outer diameter of the second diaphragm is set to be larger than an outer diameter of the first diaphragm, when an opening direction thrust applied to the first diaphragm by fluid in the first flow path is larger than a closing direction thrust applied to the second diaphragm by fluid in the second flow path, the hollow valve body is separated from the valve seat portion to open the communication flow path, and when the opening direction thrust is smaller than the closing direction thrust, the hollow valve body abuts on the valve seat portion to close the communication flow path.