High-Pressure Fuel Supply Pump

Abstract

A high-pressure fuel supply pump having a fuel relief path for connecting a high-pressure fuel path downstream of a discharge valve for discharging fuel pressurized in a pressurizing chamber to a low-pressure fuel path upstream of an inlet valve or the pressurizing chamber, a check valve being provided in the fuel relief path as a relief valve for allowing the fuel to flow only to the low-pressure fuel path or the pressurizing chamber, wherein an energy attenuating mechanism is provided in a discharge path on a side facing the discharge valve upstream of the relief valve in the fuel relief path so as to prevent an instantaneous pressure rise caused in the discharge path from propagating to the relief valve.

1 . A high-pressure fuel supply pump having a fuel relief path for connecting a high-pressure fuel path downstream of a discharge valve for discharging fuel pressurized in a pressurizing chamber to a low-pressure fuel path upstream of an inlet valve or the pressurizing chamber, a check valve being provided in the fuel relief path as a relief valve for allowing the fuel to flow only to the low-pressure fuel path or the pressurizing chamber, wherein an energy attenuating mechanism is provided in a discharge path on a side facing the discharge valve upstream of the relief valve in the fuel relief path so as to prevent an instantaneous pressure rise caused in the discharge path from propagating to the relief valve. 
     
     
         2 . The high-pressure fuel supply pump according to  claim 1 , wherein an energy attenuating mechanism for reducing energy based on a pressure rise in the discharge path is provided in the relief path, the energy attenuating mechanism acting on the relief valve in a direction to open the relief valve while the discharge valve is in an open operation. 
     
     
         3 . The high-pressure fuel supply pump according to  claim 2 , the energy attenuating mechanism is structured by including a plate having at least one orifice, the plate being disposed on a high-pressure fuel path side near the relief valve. 
     
     
         4 . The high-pressure fuel supply pump according to  claim 2 , wherein the energy attenuating mechanism is structured by including the discharge valve; the discharge valve narrows or blocks the high-pressure path near the relief valve while the discharge valve is in the open operation. 
     
     
         5 . A high-pressure fuel supply pump having a low-pressure inlet path for intaking fuel into a pressurizing chamber, a discharge path for discharging the fuel from the pressurizing chamber, an inlet valve disposed in the inlet path, a discharge valve disposed in the discharge path, a relief path for connecting a side downstream of the discharge valve in the discharge path to a side upstream of the inlet valve in the inlet path or connecting the side downstream of the discharge valve to the pressurizing chamber, the discharge path side being the upstream side and the inlet path side being the downstream side or the discharge path side being the upstream side and the pressurizing chamber side being the downstream side, and a relief valve, disposed in the relief path, for limiting a flow of the fuel to only one direction, from the upstream side to the downstream side, the relief valve being structured so that the relief valve is opened when a differential pressure between an entrance and an exit thereof is raised to or above a predetermined valve opening pressure, wherein an energy attenuating mechanism is provided upstream of the relief valve in the relief path so as to prevent a pressure pulsation caused in the discharge path from acting on the relief valve or reduce the pressure pulsation. 
     
     
         6 . The high-pressure fuel supply pump according to  claim 5 , wherein an orifice is provided near the relief valve in the relief path, as the energy attenuating mechanism. 
     
     
         7 . The high-pressure fuel supply pump according to  claim 5 , wherein a plurality of orifices are provided in parallel near the relief valve in the relief path, as the an energy attenuating mechanism. 
     
     
         8 . The high-pressure fuel supply pump according to  claim 5 , wherein a member having a mesh structure is provided near the relief valve in the relief path, as the an energy attenuating mechanism. 
     
     
         9 . The high-pressure fuel supply pump according to  claim 5 , wherein a path switching mechanism is provided near the relief valve in the relief path, as the an energy attenuating mechanism; the path switching mechanism makes a switchover to enable or disable communication between the relief path and the discharge path. 
     
     
         10 . The high-pressure fuel supply pump according to  claim 9 , wherein the path switching mechanism is structured by including a switching mechanism for disabling the communication between the relief path and the discharge path while the high-pressure fuel supply pump is in a process to discharge high-pressure fuel and enabling the communications in other processes. 
     
     
         11 . The high-pressure fuel supply pump according to  claim 10 , wherein the discharge valve is used as the switching mechanism; the discharge valve narrows or blocks a connection part between the discharge path and the relief path while the discharge valve is in the open operation. 
     
     
         12 . The high-pressure fuel supply pump according to  claim 11 , wherein a connection opening between the relief path and the discharge path is formed on a side of a cylindrical holding part that guides reciprocating motion of the discharge valve; the discharge valve narrows or blocks the connection opening when the discharge valve is open. 
     
     
         13 . The high-pressure fuel supply pump according to  claim 12 , wherein a guiding path is provided on a side of the cylindrical holding part so as to guide the fuel in the pressurizing chamber to the discharge path while the discharge valve in the open operation. 
     
     
         14 . The high-pressure fuel supply pump according to  claim 12 , wherein the cylindrical holding part is fixed to a discharge opening part in the pressurizing chamber; a seat member for the discharge valve is fixed to an end on the pressurizing chamber side of the cylindrical holding part; the discharge valve is pressed against the seat member by a spring held in the cylindrical holding part.