Abstract: A fuel injector for an internal combustion engine is provided which includes a valve body, a needle valve, and a hollow nozzle body with a bottom having formed therein spray holes.The needle valve is controlled to be selectively brought into and out of engagement with a valve seat in the valve body to close and open a fuel outlet formed in an end surface of the valve body. The hollow nozzle body is welded to the valve body with the bottom urged into constant engagement with the end surface of the valve body at a given level of pressure which is greater than a maximum fuel injection pressure. This makes it possible to establish the constant engagement of the bottom of the hollow nozzle body with the end surface of the valve body without any clearances even when the maximum fuel injection pressure acts on a portion of the bottom of the hollow nozzle body around the spray holes.

Abstract: A fluid injection nozzle having its components easily positioned and assembled. The fluid injection nozzle comprises: a first plate having a first slit-shaped hole for passing a fluid therethrough; and a second plate superposed on the downstream side of the first plate and having a second hole communicating with a portion of the first hole. A characterizing portion is formed in at least one of the first plate and the second plate at a portion other than the first hole or the second hole for discriminating the upstream and downstream sides.

Abstract: A fluid injection valve in which an orifice plate is produced by defining surfaces of walls forming an orifice on a plate-like basic material by pressing with a punch, forming a protective layer on a surface of the basic material, grinding a surface of the basic material to form an opening portion of the orifice at a predetermined opening value by measuring an amount of light passing through the orifice, and removing the protective layer in a tank filled with weak hydrochloric acid. It is possible to manufacture a fluid injection valve which has excellent fluid injection characteristics and injection quantity adjustment easily and with less expense.