Oil supply apparatus for engine provided with two-stage relief valve

Abstract

Provided is an oil supply apparatus for an engine provided with a two-stage relief valve, in which a sufficient amount of working fluid is supplied in proportion to an engine speed in a low speed range where sufficient lubrication is not performed and a flow rate of the working fluid is reduced in a medium and high speed range where smooth lubrication is performed to reduce a rotational load applied to a crankshaft, capable of reducing an engine load to decrease fuel consumption to improve fuel efficiency as well as improving a lubrication operation through supply of an appropriate flow rate.

1 . An oil supply apparatus for an engine provided with a two-stage relief valve, comprising:
 an oil pump housing ( 100 ) having an inlet side ( 110 ) and an outlet side ( 120 ) configured to enable entry and exit of a working fluid;   a rotor ( 200 ) mounted in the oil pump housing ( 100 ) and driven in proportion to an engine speed;   a relief valve ( 300 ) operated by a pressure of the working fluid between the inlet side ( 110 ) and the outlet side ( 120 ); and   first and second flow paths ( 400 ,  500 ) formed between the inlet side ( 110 ) and the relief valve ( 300 ),   wherein the relief valve ( 300 ) is elastically supported and opened in a sequence from a low speed, a medium speed, a medium/high speed, and a high speed in proportion to the engine speed, and a working fluid amount of the outlet side ( 120 ) is returned to the inlet side ( 110 ) through the first or second flow path ( 400  or  500 ) in proportion to the engine speed at the medium speed and the high speed.   
     
     
         2 . The oil supply apparatus according to  claim 1 , wherein the relief valve ( 300 ) blocks the first and second flow paths ( 400 ,  500 ) regardless of the working fluid pressure of the outlet side ( 120 ) when the rotor ( 200 ) is rotated at the low speed,
 is opened by a hydraulic pressure of the outlet side ( 120 ) to return a portion of the working fluid of the outlet side ( 120 ) to the inlet side ( 110 ) through the second flow path ( 500 ) when the rotor ( 200 ) is rotated at the medium speed,   is further opened by the hydraulic pressure of the outlet side ( 120 ) to block the first and second flow paths ( 400 ,  500 ) when the rotor ( 200 ) is rotated at the medium/high speed, and   is opened by the hydraulic pressure of the outlet side ( 120 ) to return a portion of the working fluid of the outlet side ( 120 ) to the inlet side ( 110 ) through the first flow path ( 400 ) when the rotor ( 200 ) is rotated at the high speed.   
     
     
         3 . The oil supply apparatus according to  claim 1  or  2 , wherein the relief valve ( 300 ) comprises:
 a valve housing ( 310 ) having both ends connected to branch pipes ( 111 ,  121 ) branched from the inlet side ( 110 ) and the outlet side ( 120 ), respectively; 
 a valve body ( 320 ) having a fluid path hole ( 321 ) to communicate the outlet side ( 120 ) with the second flow path ( 500 ) at the medium speed, and installed in the valve housing ( 310 ) to communicate the outlet side ( 120 ) with the first flow path ( 400 ) at the high speed; and 
 an elastic spring ( 330 ) mounted in the valve housing ( 310 ) to provide a recovering force to the valve body ( 320 ) operated by the working fluid pressure introduced from the outlet side ( 120 ).