7 090 190

7,090,190 Title:

Flow control valve

Abstract:

There is disclosed a flow control valve which regulates a flow rate by determining a stop position of a piston by contact in an opened state, and which enables remote and high-precision flow rate regulation. In a closed state, an urging force of a return spring acts on a piston, bringing a diaphragm into close contact with a valve seat. In this state, when compressed air is supplied into a pilot chamber, moving the piston, the diaphragm is brought out of contact with the valve seat. Then, the piston comes into contact with a nut and the diaphragm is stopped providing a fixed clearance between the diaphragm and the valve seat. An opened state is established. Of course, the nut can be moved to any desired position by means of a serve motor or the like, so that a position at which the piston comes into contact with the nut can be changed.

Claims:

What is claimed is:

1. A flow control valve comprising: a valve seat; a valve body which is movable into or out of contact with the valve seat; a pilot chamber into which compressed air issupplied, thereby moving the valve body to place the valve in an opened state; a spring which urges the valve body in close contact with the valve seat to place the valve in a closed state; and an electro-pneumatic regulator that controls supply anddischarge of compressed air into or from the pilot chamber, the electro-pneumatic regulator comprising: a proportional intake valve that supplies compressed air into the pilot chamber; a proportional discharge valve that discharges compressed air fromthe pilot chamber; and a passage block internally provided with (i) a supply passage through which a supply source of the compressed air and the pilot chamber are brought into communication by the proportional intake valve; (ii) a discharge passagethrough which the pilot chamber and the outside are brought into communication by the proportional discharge valve, and (iii) a communication passage through which the pilot chamber and the outside are brought into communication not through theproportional discharge valve.

2. The flow control valve according to claim 1, which is used in a semiconductor manufacturing device.

3. The flow control valve according to claim 1, wherein the electro-pneumatic regulator is directly integrally fixed to a cylinder formed with an operation port.

4. A flow control valve comprising: a valve seat; a valve body which is movable into or out of contact with the valve seat; a pilot chamber into which compressed air is supplied, thereby moving the valve body to place the valve in an openedstate; a spring which urges the valve body in close contact with the valve seat to place the valve in a closed state; and an electro-pneumatic regulator that controls supply and discharge of compressed air into or from the pilot chamber, theelectro-pneumatic regulator comprising: a proportional intake valve that supplies compressed air into the pilot chamber; a proportional discharge valve that discharges compressed air from the pilot chamber; and a passage block internally provided with(i) a supply passage through which a supply source of the compressed air and the pilot chamber are brought into communication by the proportional intake valve, (ii) a discharge passage through which the pilot chamber and the outside are brought intocommunication by the proportional discharge valve, and (iii) a communication passage therein with a bleeding mechanism that brings the pilot chamber into slight communication with the outside not through the proportional discharge valve.

5. The flow control valve according to claim 4, which is used in a semiconductor manufacturing device.

6. The flow control valve according to claim 4, wherein the electro-pneumatic regulator is directly integrally fixed to a cylinder formed with an operation port.