High-pressure fuel pump

Abstract

A high-pressure fuel pump comprises a pressurizing chamber for pressurizing fuel, an outlet valve for discharging the fuel pressurized in the pressurizing chamber to an outlet passage, a relief passage for connecting the outlet passage located downstream of the outlet valve and the pressurizing chamber with each other while bypassing the outlet valve. A relief valve device is provided in the relief passage and adapted to open when an internal pressure of the outlet passage becomes higher than that of the pressurizing chamber, thereby providing communication between the outlet passage and the pressurizing chamber. The relief valve includes a relief spring mechanism for pressing a relief valve to a relief valve seat. At least the relief spring mechanism among members of the relief valve device is provided outside the pressurizing chamber in the pump body.

1 . A high-pressure fuel pump comprising: 
 a pressurizing chamber for pressurizing fuel,    an outlet valve for discharging the fuel pressurized in the pressurizing chamber to an outlet passage,    a relief passage for connecting the outlet passage located downstream of the outlet valve and the pressurizing chamber with each other while bypassing the outlet valve, and    a relief valve device provided in the relief passage and adapted to open when an internal pressure of the outlet passage becomes higher than that of the pressurizing chamber, thereby providing communication between the outlet passage and the pressurizing chamber,    wherein the relief valve includes a relief spring mechanism for pressing a relief valve to a relief valve seat, and    wherein at least the relief spring mechanism among members of the relief valve device is provided outside the pressurizing chamber in the pump body.    
     
     
         2 . A high-pressure fuel pump comprising: 
 a pressurizing chamber for pressurizing fuel,    an outlet valve for discharging the fuel pressurized in the pressurizing chamber to an outlet passage,    a relief passage for returning the fuel in the outlet passage located downstream of the outlet valve to the pressurizing chamber when the fuel in the outlet passage abnormally becomes high, and    a relief valve device for opening and closing the relief passage,    wherein the relief valve device comprises a relief valve seat member for receiving the relief valve positioned on the pressurizing chamber-side, a relief spring for producing the pressing force, and a spring force transfer member for transferring the pressing force to the relief valve so that the relief valve is pressed toward the relief valve seat member, and    wherein the relief spring is installed on the outlet side of the high-pressure pump with reference to the relief valve seat member.    
     
     
         3 . The high-pressure fuel pump according to  claim 2 , wherein the pressurizing chamber is formed by a cup-shaped recess formed in a body of the pump and the fuel is pressurized by a plunger and is discharged from the outlet valve, and 
 wherein the plunger is supported by a supporting member fixed to the body of the pump so as to be capable of reciprocating within the pressurizing chamber.    
     
     
         4 . The high-pressure fuel pump according to  claim 2 , wherein the outlet valve has been installed from the pressurizing chamber side.  
     
     
         5 . The high-pressure fuel pump according to  claim 2 , wherein the relief passage is open on a peripheral side face of the pressurizing chamber.  
     
     
         6 . A high-pressure fuel pump according to  claim 2 , wherein the return passage is open to a top surface of the pressurizing chamber.  
     
     
         7 . The high-pressure fuel pump according to  claim 2 , wherein the relief valve device forms an independent unit as an assembly.  
     
     
         8 . The high-pressure fuel pump according to  claim 2 , wherein the relief passage provided with the relief valve device is disposed in a plural number and an outlet of at least one of the plural relief passages is open at an inlet passage to be a low pressure passage in the pump.  
     
     
         9 . The high-pressure fuel pump according to  claim 8 , 
 wherein the plural relief passages comprise a first relief passage whose outlet is open at the pump-inlet passage to be a low fuel pressure passage and a second relief passage whose outlet is open at the pressurizing chamber of the pump to be a high fuel pressure side, and    wherein an operating pressure for operating the relief valve device of the first relief passage is set so as to be higher than that of the second relief passage.    
     
     
         10 . A high-pressure fuel pump comprising: 
 a pressurizing chamber for pressurizing fuel,    a outlet valve for discharging the fuel pressurized in the pressurizing chamber to an outlet passage,    a relief passage connecting the outlet passage of the pump and the pressurizing chamber to each other so that the outlet passage side is an upstream side and the pressurizing chamber side is a downstream side,    a relief valve seat member positioned at outlet side of the relief passage in the vicinity of the of the pressurizing chamber and having a valve seat surface on the downstream side of the relief passage,    a relief valve positioned on the downstream side of the valve seat member to open and close a fuel passage in cooperation with the relief seat surface, the fuel passage being formed in the valve seat member,    a valve rod connected to the valve body and extending to the upstream side of the valve seat member through the fuel passage of the valve seat member, and    a spring member positioned on the upstream side of the valve seat member to pull the valve body to the seat surface through the valve rod.    
     
     
         11 . The high-pressure fuel pump according to  claim 10 , wherein the pressurizing chamber is formed by a cup-shaped recess formed in a body of the pump and the fuel is pressurized by a plunger and is discharged from the outlet valve, and 
 wherein the plunger is supported by a supporting member fixed to the body of the pump so as to be capable of reciprocating within the pressurizing chamber.    
     
     
         12 . The high-pressure fuel pump according to  claim 10 , wherein the outlet valve has been is installed from the pressurizing chamber side.  
     
     
         13 . The high-pressure fuel pump according to  claim 10 , wherein the relief passage is open on a peripheral side face of the pressurizing chamber.  
     
     
         14 . The high-pressure fuel pump according to  claim 10 , wherein the relief passage is open to a top surface of the pressurizing chamber.  
     
     
         15 . The high-pressure fuel pump according to  claim 1 , wherein the valve drive mechanism includes an electromagnetic drive mechanism.