Pump for brake system

Abstract

A pump for a brake system for increasing sealing performance between a piston and a bore as well as motion performance and durability of the piston and facilitating assembling efficiency of the piston. The pump includes a bore formed in a modulator block and connected to a suction port and discharge port, a piston installed in the bore to perform rectilinear reciprocating motions and having an oil flow path to move oil suctioned through the suction port toward the discharge port, an inlet valve to open and close the oil flow path in accordance with the motions of the piston, an outlet valve to selectively allow the discharge of compressed oil, and a fixing unit having a guide member provided around the piston to be coupled to the bore and adapted to guide the motions of the piston and a sealing member provided around the piston to be coupled to the bore and adapted to keep the bore and the piston in an air-tightness state.

1 . A pump for a brake system comprising: 
 a bore formed in a modulator block and connected to a suction port and discharge port;    a piston installed in the bore to perform rectilinear reciprocating motions, the piston comprising an oil flow path to move an oil suctioned through the suction port toward the discharge port;    an inlet valve to open and close the oil flow path in accordance with the motions of the piston and an outlet valve to selectively allow the discharge of the compressed oil; and    a fixing unit comprising a guide member provided around the piston to be coupled to the bore and adapted to guide the motions of the piston and a sealing member provided around the piston to be coupled to the bore and adapted to keep between the bore and the piston in an air-tightness state.    
   
   
       2 . The pump according to  claim 1 , wherein the guide member and sealing member are integrally formed with each other to constitute the fixing unit.  
   
   
       3 . The pump according to  claim 1 , wherein the piston has a protruding portion to be caught by the fixing unit, so as to prevent the piston from extending out of the bore beyond a predetermined length.  
   
   
       4 . The pump according to  claim 1 , wherein the inlet valve comprises a valve seat formed at an end of the oil flow path, a valve opening/closing member to open and close the valve seat, a valve spring to elastically support the valve opening/closing member, and a holder to hold the valve spring at a fixed position, the holder having an end configured to be caught by the fixing unit, so as to prevent the piston from extending out of the bore beyond a predetermined length.  
   
   
       5 . The pump according to  claim 1 , further comprising: 
 a guide bush provided between the piston and the bore to guide the motions of the piston; and    a sliding seal member adapted to slide between the guide bush and the fixing unit, so as to keep between the piston and the bore in an air-tightness state,    wherein the fixing unit is extended from the inlet valve of the piston and adapted to support the sliding seal member to thereby prevent the sliding seal member from sliding beyond a predetermined distance.    
   
   
       6 . The pump according to  claim 1 , further comprising: 
 a valve seat coupled to the piston, the valve seat defining an exit of the oil flow path to be opened and closed by the inlet valve,    wherein the valve seat has a protruding portion to be caught by the fixing unit, so as to prevent the piston from extending out of the bore beyond a predetermined length.    
   
   
       7 . The pump according to  claim 1 , wherein the piston has a stepped portion defined between different outer-diameter portions thereof, and the fixing unit has a holding portion defined between different inner-diameter portions thereof, the stepped portion being caught by the holding portion to prevent the piston from extending out of the bore beyond a predetermined length.