Fuel injection system for internal combustion engine

Claim 1

A fuel injection system for an internal combustion engine provided with an intake passage, a cylinder associated with said intake passage and at least one intake valve associated with said cylinder, said fuel injection system including a fuel injector adapted to be disposed upstream of said intake valve, said fuel injector comprising: a housing; a hollow body connected to one end of said housing said hollow body having an end wall formed therein with an injection orifice; a valve member disposed slidably in said body comprising a needle valve of the type that is electromechanically operated; a pintle provided on said valve member for facilitating atomization of liquid fuel, said pintle extending outwardly from said hollow body through said injection orifice with a gap between an outer periphery of said pintle and an inner peripheral surface of said injection orifice to meter fuel to be injected; a sleeve member mounted on said hollow body to cover said injection orifice, said sleeve member defining therein a pintle-receiving space and a plurality of communication apertures adapted to communicate said pintle-receiving space with said intake passage of said engine, the total of the cross-sectional areas of said communication apertures being smaller than the cross-sectional area of said pintle-receiving space, and wherein the ratio of the total of the cross-sectional areas of said communication apertures relative to the cross-sectional area of said gap between said pintle and said injection orifice is not less than 5.5 and wherein each of said communication apertures has a length axially of said pintle and a minimum diameter, the ratio of said length relative to said minimum diameter being less than 2 and at least two of said communication apertures being adapted to be directed to one intake valve when said injector is mounted on said engine.