Carburettor for a spark ignition engine

摘要

Carburettor for a spark ignition engine having a nozzle needle which can be adjusted in an operation-dependent manner and having a pressure probe in the carburettor pipe. An engine speed measuring circuit (23) which evaluates gear pulses which are synchronous with the crank shaft rotation, provides a digital engine speed value for each rotation of the crank shaft. The technical problem of the invention consists in setting the nozzle needle as a function of the load state and/or working state of the internal combustion engine. The engine speed value is present on an input rail of an address memory (26) in which needle set values for the nozzle needle are stored. The measured value of the pressure probe (28) is present in digital form at selection inputs (27) of the address memory (26). A digital-to-analog converter (31) converts the digital needle set values, available at the output of the address memory as a function of the engine speed value and the pressure measuring value, into analog values. An engine (13) is coupled on its output shaft (12) to a sliding sheath (9) on which the nozzle needle (8) is seated. The output shaft (12) of the engine (13) is coupled via a spur wheel gear to a rotary potentiometer (17) which outputs an analog actual signal for the position of the nozzle needle (8). A comparator circuit (32) compares the output value of the rotary potentiometer as actual value and the analog needle set value and outputs a control signal for the engine. <IMAGE>