Fuel injection system and timing advance device therefor

Abstract

A hydraulic advance device for selectively transmitting applied forces to a fuel injector of an internal combustion engine. The device is operative to select a normal or advanced timing of the fuel injection. An outer cylindrical body (66) is mounted in the upper end of a fuel injector adapter. An inner body (108) is slidably received in an outer body and a reaction member (103) and pressure responsive plunger (117) are slidably received in a bore formed in the inner body. The plunger and the bore cooperate to define a fluid chamber (128). A one-way valve (132) in the chamber permits fluid above a predetermined pressure applied during the advanced stage of the fuel injection cycle to enter the chamber which prevents movement of the plunger relative to the inner body member. At pressures below a predetermined value and during the normal phase of the fuel injection cycle, the plunger and reaction member first move relative to the inner body a predetermined amount during which time no movement is transferred to the inner body thus delaying fuel injection relative to advance phase fuel injection.