Subpressure limiter for a fuel injection system

Claim 1

A subpressure limiter for a fuel injection system of a mixture compressing, externally ignited internal combustion engine having a suction tube containing an arbitrarily actuatable throttle valve in which an apportioned fuel quantity is injected into the suction tube, the suction tube including suction tube sections upstream and downstream of the flap of the throttle valve wherein the improvement comprises, a bypass for interconnecting said upstream and downstream sections of said suction tube, a subpressure limiter for varying the cross-sectional area of said bypass, said subpressure limiter including a pressure-dependent control element that responds to the subpressure prevailing within the suction tube section downstream of the throttle valve during an overrunning operation, said pressure-dependent control element comprising a control valve, a pre-control capsule, including a pressure-responsive capsule in the form of an evacuated elastic hollow body arranged to actuate said control valve and a chamber connected to said suction tube section downstream of said throttle valve in which said hollow body is confined, a bypass control capsule associated with said control valve, said bypass control capsule comprising a housing provided with first and second chambers and an intermediate diaphragm, the first of said chambers connected to a first line in communication with said suction tube section upstream of the throttle valve, said last named chamber also connected to a second line in communication with said suction tube downstream of said throttle valve, valve means associated with said diaphragm arranged to close said second line, throttling means providing for communication between said first and second chambers and spring means in said second chamber serving to bias said valve means in a closing direction.