Relief valve

Abstract

A gap 11 between a flange 4 A of a ball support member 4 and the inner circumferential surface of a sleeve member 7 functions as an orifice for restricting an oil flow downstream of a seat hole ( 6 B). The movement of the ball support member 4 is stabilized, pressure is generated in a chamber 9 downstream of a seat hole 6 B, and the override characteristics of the relief valve 1 are improved.

What is claimed is:  
     
         1 . A relief valve, comprising: 
 a valve seat comprising a seat hole;    a ball which opens and closes the seat hole from the downstream side;    a movable member which supports the ball from the downstream side;    a housing part which houses the movable member; and    an orifice formed downstream of the seat hole which damps the vibration of the movable member and suppresses chattering by restricting an oil flow.    
     
     
         2 . The relief valve as defined in  claim 1 , wherein the orifice is a gap between the movable member and the inner circumferential surface of the housing part.  
     
     
         3 . The relief valve as defined in  claim 2 , wherein: 
 the movable member further comprises a flange of circular cross-section;    the orifice is a gap between the flange and the inner circumferential surface of the housing part; and    the width of the gap in the radial direction is less than {fraction (1/20)} of the inner diameter of the housing part.    
     
     
         4 . The relief valve as defined in  claim 1 , wherein: 
 the movable member slides on the inner circumferential surface of the housing part; and    the orifice is grooves formed on either one of the outer circumferential surface of the movable member, and the inner circumferential surface of the housing part.    
     
     
         5 . The relief valve as defined in  claim 1 , wherein: 
 the movable member slides on the inner circumferential surface of the housing part; and    the orifice is a throughhole through which the movable member passes.    
     
     
         6 . The relief valve as defined in  claim 5 , wherein the relief valve comprises a return spring disposed on the movable member; 
 depressions are formed in the movable member on the side where the return spring is installed; and    the throughhole opens onto the depressions.    
     
     
         7 . The relief valve as defined in  claim 1 , further comprising: 
 a return spring disposed on the movable member;    a spring chamber housing the return spring downstream of the seat hole; and    a second orifice between the spring chamber and a tank port.    
     
     
         8 . The relief valve as defined in  claim 1 , further comprising: 
 a third orifice upstream of the seat hole.    
     
     
         9 . A flowrate control valve which controls the flowrate supplied from a pump to a load circuit comprising a relief valve, the relief valve comprising: 
 a valve seat having a seat hole;    a ball which opens and closes the seat hole from the downstream side; a movable member which supports the ball from the downstream side;    a housing part which houses the movable member; and    an orifice formed downstream of the seat hole which damps the vibration of the movable member  4  and suppresses chattering by restricting an oil flow, wherein:    the relief valve opens when the pressure on the load circuit side rises, and part of the fluid from the pump is discharged to a tank port.    
     
     
         10 . The flowrate control valve as defined in  claim 9 , wherein the orifice is a gap between the movable member and the inner circumferential surface of the housing part.  
     
     
         11 . The flowrate control valve as defined in  claim 10 , wherein: 
 the movable member further comprises a flange of circular cross-section;    the orifice is a gap between the flange and the inner circumferential surface of the housing part; and    the width of the gap in the radial direction is less than {fraction (1/20)} of the inner diameter of the housing part.    
     
     
         12 . The flowrate control valve as defined in  claim 9 , wherein: 
 the movable member slides on the inner circumferential surface of the housing part; and    the orifice is grooves formed on either one of the outer circumferential surface of the movable member, and the inner circumferential surface of the housing part.    
     
     
         13 . The flowrate control valve as defined in  claim 9 , wherein: 
 the movable member slides on the inner circumferential surface of the housing part; and    the orifice is a throughhole through which the movable member passes.    
     
     
         14 . The flowrate control valve as defined in  claim 13 , wherein the relief valve comprises a return spring disposed on the movable member; 
 a depression is formed in the movable member on the side where the return spring is installed; and    the throughhole opens onto the depression.    
     
     
         15 . The flowrate control valve as defined in  claim 9 , further comprising: 
 a return spring disposed in the movable member;    a spring chamber housing the return spring downstream of the seat hole, and a second orifice between the spring chamber and the tank port.    
     
     
         16 . The flowrate control valve as defined in  claim 9 , further comprising: 
 a third orifice upstream of the seat hole.    
     
     
         17 . The flowrate control valve as defined in any of claims  9  through  16 , comprising: 
 a spool;  
 a supply chamber formed on one side of the spool;  
 a flowrate control valve chamber formed on the other side of the spool; and  
 a flowrate control spring provided in the flowrate control spring chamber which pushes the spool in the direction of the supply chamber, wherein:  
 a pump pressure is led to the supply chamber;  
 oil is supplied from the supply chamber to a supply port to the load circuit via a supply orifice;  
 the pressure downstream of the supply orifice is led to the flowrate control valve chamber via at least one orifice or throat,  
 when the spool retracts in the direction of the flowrate control spring chamber, the supply chamber communicates with the tank port,  
 the relief valve is built into the spool from the side of the flowrate control spring chamber, and  
 when the relief valve opens, the flowrate control spring chamber communicates with the tank port.