Detecting ambient air pressure for IC engine of motor vehicle - operating only when opening angle of throttle flap is greater than predetermined angle dependent on rpm of engine

摘要

The air pressure in the intake pipe is measured behind the throttle flap. The measurement and/or transference of the measurement result as a value of the ambient air pressure follows only when the present angle of opening of the throttle flap is greater than an opening angle that is predetermined in relation to the r.p.m. of the i.c. engine. A control appts. uses a microcomputer (31) to control the necessary functions according to a fixed program. The analogue values are fed via a multiplexer (33) and an a-d converter (32), while the pulsed input values or binary signals arrive at the microcomputer via interfaces. USE/ADVANTAGE - Taking into account external air pressure to avoid starting and running problems for motor vehicles having electronics fuel mixt. forming systems. Avoids use of absolute pressure sensor, reducing expense.