Relief valve

Abstract

A relief valve includes a cylindrical valve housing attached to an engine body continuously with a relief passage and an outlet provided in an axially intermediate portion thereof. A valve body is slidably fitted to the valve housing so as to allow the relief passage to communicate with the outlet as an oil pressure in the relief passage becomes equal to and exceeds a predetermined oil pressure. A skirt includes an upper end portion fixed to the valve housing above the outlet for guiding oil discharged from the outlet downward. The relief valve exerts a reliable defoaming function in response to an increase in the oil discharged from the outlet and an increase in an ejection pressure thereof while avoiding an increase in the size of the skirt. An annular recessed portion is formed on an outer circumference of the intermediate portion of the valve housing below the outlet.

1 . A relief valve comprising: 
 a cylindrical valve housing attached to an engine body and longitudinally extending continuously with a relief passage for communicating with an ejection port of an oil pump which is provided in the engine body, said cylindrical valve housing being provided with an outlet in an axially intermediate portion thereof;    a valve body slidably fitted relative to the valve housing to allow the relief passage to communicate with the outlet as oil pressure in the relief passage becomes equal to and exceeds a predetermined oil pressure;    a skirt formed in an umbrella shape to surround the valve housing with an upper end portion of the skirt being fixed to the valve housing above the outlet in order to guide oil discharged from the outlet downward; and    an annular recessed portion being formed on an outer circumference of the intermediate portion of the valve housing below the outlet.    
   
   
       2 . The relief valve according to  claim 1 , wherein a lower end of the skirt is disposed at a position corresponding to an intermediate portion of the annular recessed portion.  
   
   
       3 . The relief valve according to  claim 1 , wherein an upper end portion of the valve housing, the upper end portion forming an inlet, is fluid-tightly fitted to the relief passage and a receiving portion for receiving a lower end of the valve housing.  
   
   
       4 . The relief valve according to  claim 2 , wherein an upper end portion of the valve housing, the upper end portion forming an inlet, is fluid-tightly fitted to the relief passage and a receiving portion for receiving a lower end of the valve housing.  
   
   
       5 . The relief valve according to  claim 1 , wherein the skirt is an annular member that extends along the valve housing a predetermined distance for covering the outlet while being spaced apart a predetermined distance therefrom.  
   
   
       6 . The relief valve according to  claim 3 , and further including a sealing ring for providing a fluid-tight fit for the upper portion of the inlet to said relief passage.  
   
   
       7 . The relief valve according to  claim 1 , and further including a biasing means operatively connected to said valve body for normally biasing said valve body to a position for closing said outlet.  
   
   
       8 . The relief valve according to  claim 1 , and further including a stopper pin operatively positioned within said valve housing for limiting the movement of the valve body when the valve body closes the outlet.  
   
   
       9 . The relief valve according to  claim 7 , wherein the outlet is opened when the oil pressure in the relief passage is greater than the biasing force of said biasing means acting on said valve body.  
   
   
       10 . The relief valve according to  claim 1 , wherein the size of the skirt surrounding the outlet is formed for increasing the flow passage area between the outlet and the skirt for ensuring defoaming of the oil.  
   
   
       11 . A relief valve comprising: 
 a valve housing longitudinally extending continuously with a relief passage for communicating with an ejection port of an oil pump, said valve housing being provided with an outlet in an axially intermediate portion thereof;    a valve body slidably fitted relative to the valve housing to allow the relief passage to communicate with the outlet as oil pressure in the relief passage becomes equal to and exceeds a predetermined oil pressure;    a skirt formed to surround the valve housing with an upper end portion of the skirt being fixed to the valve housing above the outlet in order to guide oil discharged from the outlet downwardly; and    an recessed portion being formed on an outer circumference of the intermediate portion of the valve housing below the outlet.    
   
   
       12 . The relief valve according to  claim 11 , wherein a lower end of the skirt is disposed at a position corresponding to an intermediate portion of the annular recessed portion.  
   
   
       13 . The relief valve according to  claim 11 , wherein an upper end portion of the valve housing, the upper end portion forming an inlet, is fluid-tightly fitted to the relief passage and a receiving portion for receiving a lower end of the valve housing.  
   
   
       14 . The relief valve according to  claim 12 , wherein an upper end portion of the valve housing, the upper end portion forming an inlet, is fluid-tightly fitted to the relief passage and a receiving portion for receiving a lower end of the valve housing.  
   
   
       15 . The relief valve according to  claim 11 , wherein the skirt is an annular member that extends along the valve housing a predetermined distance for covering the outlet while being spaced apart a predetermined distance therefrom.  
   
   
       16 . The relief valve according to  claim 13 , and further including a sealing ring for providing a fluid-tight fit for the upper portion of the inlet to said relief passage.  
   
   
       17 . The relief valve according to  claim 11 , and further including a biasing means operatively connected to said valve body for normally biasing said valve body to a position for closing said outlet.  
   
   
       18 . The relief valve according to  claim 11 , and further including a stopper pin operatively positioned within said valve housing for limiting the movement of the valve body when the valve body closes the outlet.  
   
   
       19 . The relief valve according to  claim 17 , wherein the outlet is opened when the oil pressure in the relief passage is greater than the biasing force of said biasing means acting on said valve body.  
   
   
       20 . The relief valve according to  claim 11 , wherein the size of the skirt surrounding the outlet is formed for increasing the flow passage area between the outlet and the skirt for ensuring defoaming of the oil.