Abstract: A fuel cell system (10) of the present invention has a fuel cell (20) which generates electric power by being supplied with reactive gas, an air compressor (C1) which supplies oxidizing gas to the fuel cell (20), a pressure sensor (P2) which detects the pressure of oxidizing gas, a pressure control valve (C2) which adjusts the pressure of oxidizing gas, and a control device (50) which adjusts the valve opening of the pressure control valve (C2) on the basis of the pressure detected by the pressure sensor (P2). When an abnormality in the pressure sensor (P2) is detected, the control device (50) opens the pressure control valve (C2) so that the valve opening thereof is equal to or larger than a predetermined opening. This arrangement ensures that the cell operation can be continued for a while instead of being immediately stopped in the event of abnormality in the pressure sensor (P2).

Abstract: A fuel cell system (10) of the present invention has a fuel cell (20) which generates electric power by being supplied with reactive gas, an air compressor (C1) which supplies oxidizing gas to the fuel cell (20), a pressure sensor (P2) which detects the pressure of oxidizing gas, a pressure control valve (C2) which adjusts the pressure of oxidizing gas, and a control device (50) which adjusts the valve opening of the pressure control valve (C2) on the basis of the pressure detected by the pressure sensor (P2). When an abnormality in the pressure sensor (P2) is detected, the control device (50) opens the pressure control valve (C2) so that the valve opening thereof is equal to or larger than a predetermined opening. This arrangement ensures that the cell operation can be continued for a while instead of being immediately stopped in the event of abnormality in the pressure sensor (P2).

Abstract: According to the device of the invention, measured values (V.sub.0 ', V') of an output V.sub.A of an opening sensor at two adjusted levels of throttle openings in both idling state and fast idling state and their ideal values (V.sub.0, V) are used. The value V.sub.0 ' in the idling state is subtracted from the output V.sub.A in a driving condition, (V.sub.A -V.sub.0 '), which is then multiplied by the ratio of ideal variation characteristics of the sensor output for a change of the throttle opening to those in the throttle valve product used, {(V-V.sub.0)/(V'-V.sub.0 ')}, to produce a correction signal T.sub.A matching the individual difference. Further, a reference value subtracted from the output V.sub.A in a driving condition is set as T.sub.AMIN which varies with the output V.sub.A, taking the difference of variation characteristics of the sensor output from ideal characteristics into account.

Abstract: An object of the invention is to detect an upper limit of a lean burn zone in an internal combustion engine in each ignition. The lean limit is detected on the basis of the characteristics of the ionic current in a cylinder of the engine immediately after ignition.