Fluid control device

Abstract

In a fluid control device, a valve body is prevented from being pressed forcefully against a valve seat or the like, and an excessive load is prevented from acting on a motor. A flow rate adjustment device includes a first engagement portion, and a second engagement portion that is capable of moving relative to the first engagement portion and transmitting and receiving rotary force. The flow rate adjustment device includes a valve body that adjusts an opening of a flow passage, and a rod that is coupled to the valve body. The flow rate adjustment device further includes a male screw portion and a female screw portion that are intermeshed so as to be fed relative to each other in the axial direction, a projecting portion that restricts movement of the second engagement portion, and a first cylinder that restricts movement of the rod.

What is claimed is: 
     
         1 . A fluid control device comprising:
 a motor having a drive shaft;   a first engagement portion provided on the drive shaft;   a second engagement portion configured to move relative to the first engagement portion in an axial direction of the drive shaft and receive a rotary force from the first engagement portion;   a valve main body having a flow passage for a fluid and a valve seat portion;   a valve body provided to face the valve seat portion in order to adjust an opening of the flow passage;   a moving member coupled to the valve body of which movement in the axial direction is permitted and of which rotation about the drive shaft is restricted;   an elastic member configured to exert a force on the moving member in a direction for causing the valve body to approach the valve seat portion;   a first restricting portion configured to restrict movement of the second engagement portion to the side of the valve seat portion beyond a first restriction position; and   a second restricting portion configured to restrict movement of the moving member to the side of the valve seat portion beyond a second restricting position,   wherein the second engagement portion and the moving member are screwed together such that the second engagement portion and the moving member move relative to each other in the axial direction when rotated relative to each other.   
     
     
         2 . The fluid control device according to  claim 1 , wherein the second restricting portion is provided with a spacer for adjusting the second restriction position, and
 in a condition where movement of the moving member is restricted by the second restricting portion, a gap is formed between the valve seat portion and the valve body.   
     
     
         3 . The fluid control device according to  claim 2 , further comprising a cylinder configured to guide movement of the moving member in the axial direction,
 wherein an insertion port into which the spacer is inserted from outside is formed in the cylinder.   
     
     
         4 . The fluid control device according to  claim 1 , wherein one of the first engagement portion and the second engagement portion includes a rectangular parallelepiped-shaped insertion portion,
 the other of the first engagement portion and the second engagement portion includes a recessed portion into which the insertion portion is inserted in the axial direction, and   outside surfaces of the insertion portion and inside surfaces of the recessed portion are mutually parallel and fitted together with a gap between the surfaces.   
     
     
         5 . The fluid control device according to  claim 1 , wherein the motor is a stepping motor configured to rotate in synchronization with pulse power. 
     
     
         6 . The fluid control device according to  claim 2 , wherein one of the first engagement portion and the second engagement portion includes a rectangular parallelepiped-shaped insertion portion,
 the other of the first engagement portion and the second engagement portion includes a recessed portion into which the insertion portion is inserted in the axial direction, and   outside surfaces of the insertion portion and inside surfaces of the recessed portion are mutually parallel and fitted together with a gap between the surfaces.   
     
     
         7 . The fluid control device according to  claim 3 , wherein one of the first engagement portion and the second engagement portion includes a rectangular parallelepiped-shaped insertion portion,
 the other of the first engagement portion and the second engagement portion includes a recessed portion into which the insertion portion is inserted in the axial direction, and   outside surfaces of the insertion portion and inside surfaces of the recessed portion are mutually parallel and fitted together with a gap between the surfaces.   
     
     
         8 . The fluid control device according to  claim 2 , wherein the motor is a stepping motor configured to rotate in synchronization with pulse power. 
     
     
         9 . The fluid control device according to  claim 3 , wherein the motor is a stepping motor configured to rotate in synchronization with pulse power. 
     
     
         10 . The fluid control device according to  claim 4 , wherein the motor is a stepping motor configured to rotate in synchronization with pulse power.