Fuel injection system for internal combustion engines

Claim 1

A fuel injection system for internal combustion engines having a variable rate of fuel supply in dependence on the r.p.m., comprising, a fuel injection pump having a cylinder and a pump piston in said cylinder delimiting therewith a work chamber, a first bypass for said work chamber, a reciprocable control member for interrupting the delivery of said pump at least at maximum r.p.m. by opening up said first bypass during the pressure stroke of the said pump piston, an auxiliary pump for operation in synchronism with said injection pump and supplying pressure liquid to said control member during the pressure stroke thereof, means for exerting a return force on said control member, a stop for limiting the return stroke of said control member and defining a fixed initial position therefor, a throttle channel having a controllable restriction therein and connected to receive a portion of the liquid displaced during the return stroke of said control member, thereby to decelerate said return stroke, whereby said control member upon the attaining of a predetermined r.p.m. and at a certain value of the crosssectional area of said restriction is subjected to a fluid abutment and does not return to said initial position, a second bypass connected with said work chamber and means on said control member for controlling said second bypass, a slide valve driven in synchronism with said injection pump and said auxiliary pump for controlling said second bypass, characterized by a dimensioning of said system, whereby said second bypass (33) is opened up by said control member (14) before said first bypass (16), said second bypass (33) in the absence of a fluid abutment being closed by said slide valve (2) before being opened by said control member (14) and in the presence of said fluid abutment being opened by said control member (14) for increasing levels of said fluid abutment at an increasingly earlier time relative to the earlier closing thereof by said slide valve (2), a throttling restriction (35) being provided in said second bypass (33).