Fuel injection device

Abstract

A fuel injection device includes an injection hole for injecting fuel therethrough, a needle movable between a first position to open the injection hole and a second position to close the injection hole, and a back-pressure chamber. The fuel injection device further includes a two-way solenoid valve for opening and closing a flow passage between the back-pressure chamber and a drain side so as to change a pressure in the back-pressure chamber. The needle is movable between the first and second positions depending on the pressure in the back-pressure chamber. A first flow restrictor and a second flow restrictor are provided in a flow passage, which introduces high-pressure fuel into the back-pressure chamber, so as to restrict a flow of the high-pressure fuel passing therethrough. The first and second flow restrictors may be arranged in series to each other. In this case, one of the first and second flow restrictors works as a flow restrictor to restrict the fuel flow passing therethrough only when the needle moves to the first position. The first and second flow restrictors may also be arranged in parallel with each other. In this case, one of the first and second flow restrictors is closed when the needle moves to the first position. In this fashion, the wasteful release of the high-pressure fuel toward the drain side during the fuel injection is effectively prevented while ensuring a quick response for stopping the fuel injection.

Dependencies are inferred from the claim text.