High-Pressure Fuel Pump

A high-pressure fuel pump comprising:

• a pump housing formed with a recess;
• a cylinder combined with the pump housing to define the recess as a pressurizing chamber;
• and
• a plunger sliding against the cylinder to pressurize fluid in the pressurizing chamber;
• wherein reciprocation of the plunger pressurizes fuel sucked into the pressurizing chamber and discharges the fuel from the pressurizing chamber;
• wherein the high-pressure fuel pump includes:
• a seal member attached to an outer circumferential surface of the piston plunger, the outer circumferential surface being located on a side opposite the pressurizing chamber;
• and
• a holder housing the seal member;
• wherein the holder includes an outer cylindrical surface portion fitted to an attachment fitting hole of an engine block of an internal combustion engine, and
• an inner cylindrical surface portion housing the seal member;
• and
• wherein the holder is provided with a cylindrical fitting portion fitted to an outer circumference of the cylinder,
• the outer cylindrical surface portion, the inner cylindrical surface portion and the cylindrical fitting portion are formed in a single piece resulting from machining one and the same member, and an outer circumferential surface of the cylinder and an inner circumferential surface of the pump housing are configured so as not to contact to each other.

A high-pressure fuel pump comprising:

• a pump housing formed with a recess;
• a cylinder combined with the pump housing to define the recess as a pressurizing chamber;
• a plunger sliding against the cylinder to pressurize fluid in the pressurizing chamber;
• wherein reciprocation of the plunger pressurizes fuel sucked into the pressurizing chamber and discharges the fuel from the pressurizing chamber;
• wherein the high-pressure pump includes a seal member attached to an outer circumferential surface of the piston plunger, the outer circumferential surface being located on a side opposite the pressurizing chamber;
• and
• a holder housing the seal member;
• wherein the holder includes an outer cylindrical surface portion fitted to an attachment fitting hole of an engine block of an internal combustion engine, and
• an inner cylindrical surface portion housing the seal member;
• and
• wherein the outer cylindrical surface portion and the inner cylindrical surface portion are formed of respective cylindrical surfaces, axial centers of the cylindrical surfaces coinciding with a central axis of an insertion hole of the piston plunger formed in the cylinder, and an outer circumferential surface of the cylinder and an inner circumferential surface of the pump housing are configured so as not to contact to each other.