Fuel pump, in-cylinder direct injection type internal combustion engine using the same and surface treatment method

A fuel pump, comprising, inside a housing, a shaft transmitting rotation from outside, a swash plate converting rotation of said shaft into a swinging motion and a plunger reciprocated in a cylinder by the swinging motion of said swash plate through a slipper, and pressurizing fuel and supplying the fuel to a fuel injection valve of a vehicle engine, wherein a surface-hardened layer comprising one of a nitride layer, a carburized and quenched layer and a carbonitrided layer, and a metal compound layer formed on said surface-hardened layer and having a higher corrosion resistance to the fuel than the surface-hardened layer is formed on at least one of sliding surfaces of said plunger and cylinder, contacting with each other and sliding.

A fuel pump, comprising, inside a housing, a swash plate rotating through a shaft transmitting rotation from outside, a swing plate swinging by rotation of said swash plate and a plunger reciprocating in a cylinder through a slipper by rotation of said swing plate, and pressurizing fuel and supplying the fuel to a fuel injection valve of a vehicle engine, wherein a surface-hardened layer comprising one of a nitride layer, a carburized and quenched layer and a carbonitrided layer, and a metal compound layer formed on said surface-hardened layer and having a higher corrosion resistance to the fuel than the surface-hardened layer is formed on at least one of sliding surfaces of said plunger and cylinder, contacting with each other and sliding.

A fuel pump pressurizing and supplying fuel to a fuel injection valve of a vehicle engine, wherein a surface-hardened layer comprising one of a nitride layer, a carburized and quenched layer and a carbonitrided layer, and a metal compound layer formed on said surface-hardened layer and having a higher corrosion resistance to the fuel than the surface-hardened layer is formed on at least one of sliding surfaces contacting with each other and sliding through lubrication oil.

A fuel pump pressurizing and supplying fuel to a fuel injection valve of a vehicle engine, wherein a surface-hardened layer comprising one of a nitride layer formed by nitriding and then diffusion treatment and a carbonitrided layer, and a metal compound layer formed on said surface-hardened layer and having a higher corrosion resistance to the fuel than the surface-hardened layer are formed on at least one of sliding surfaces contacting with each other and sliding through the fuel.

A fuel pump pressurizing and supplying fuel to a fuel injection valve of a vehicle engine, wherein a surface-hardened layer comprising Fe4N and CrN, and a metal compound layer formed on said surface-hardened layer and having a higher corrosion resistance to the fuel than the surface-hardened layer are formed on at least one of sliding surfaces made of one of stainless steel and alloy tool steel and contacting with each other to slide through the fuel.

A fuel pump pressurizing and supplying fuel to a fuel injection valve of a vehicle engine, wherein a surface-hardened layer comprising a carbonitrided layer of martensite structure, and a metal compound layer formed on said surface-hardened layer and having a higher corrosion resistance to the fuel than the surface-hardened layer are formed on at least one of sliding surfaces made of one selected from stainless steel and alloy tool steel and contacting with each other to slide through the fuel.

A surface treatment method for a fuel pump pressurizing and supplying fuel to a fuel injection valve of a vehicle engine, comprising the steps:

• forming a surface-hardened layer having martensite structure on at least one of sliding surfaces made of one selected from stainless steel and alloy tool steel and contacting with each other and sliding through the fuel, by carburizing and quenching;
• and then
• forming a metal compound layer of higher corrosion resistance to the fuel than said surface-hardened layer on said surface-hardened layer by a PVD method.