Abstract: To supervise operational effectiveness of catalytic reactors included in exhaust emission detoxification systems, an oxygen sensor is located downstream of the reactor to determine oxygen content in the exhaust gases from the internal combustion engine, the oxygen sensor comprising an ion conductive solid electrolyte forming an ion concentration chain and having catalytically inactive contacts, connected to a detection circuit which provides an output signal in dependence on a signal from the sensor, the output signal operating an alarm, or a transducer which interferes with proper engine operation to force the operator to have the reactor repaired. Preferably, two ion conductive chains are used, in a single sensor, or in two sensors, one being exposed to exhaust gases upstream of the catalytic reactor and the other downstream of the catalytic reactor, the output signals being provided to a differentially connected operational amplifier, to balance out extraneous influences.

Abstract: The inlet and outlet ends of a catalytic reactor are instrumented with oxygen sensors. A change of the fuel-air concentration of the combustible mixture is indicated by a jump in the output voltage of the sensors; the voltage of the inlet sensor changes before that of the outlet sensor and the greater the time difference between these changes, the higher is the catalytic activity of the reactor. When a repeatable and constant engine condition is reached, the fuel-air mixture is abruptly changed and an electronic circuit enables a logical circuit which controls a signal lamp. If, during a predetermined time interval, the outlet sensor also changes its output voltage, indicating a time difference which is too short, the warning signal is energized and the operator is alerted to the insufficient level of reactor activity.

Abstract: To supervise operational effectiveness of catalytic reactors included in exhaust emission detoxification systems, an oxygen sensor is located downstream of the reactor to determine oxygen content in the exhaust gases from the internal combustion engine, the oxygen sensor comprising an ion conductive solid electrolyte forming an ion concentration chain and having catalytically inactive contacts, connected to a detection circuit which provides an output signal in dependence on a signal from the sensor, the output signal operating an alarm, or a transducer which interferes with proper engine operation to force the operator to have the reactor repaired. Preferably, two ion conductive chains are used, in a single sensor, or in two sensors, one being exposed to exhaust gases upstream of the catalytic reactor and the other downstream of the catalytic reactor, the output signals being provided to a differentially connected operational amplifier, to balance out extraneous influences.

Abstract: Clock pulses are multiplied by a ratio less than 1 of which the numerator is controlled by a reversible counter. The multiplier output pulses initiate new countdown cycles of a second counter beginning with the clock pulse following the onset of an input frequency pulse and ending with the clock pulse following the onset of the next input frequency pulse. The state of the count at the end of the cycle determines whether the reversible counter will be left unchanged, advanced, or counted back and hence, whether the multiplier output frequency will be left unchanged, increased or reduced. The initial countdown value of the second counter is provided by a long term store which determines the frequency multiplication ratio. The circuit is usable to multiply a variable input frequency in a vehicle brake anti-lock system.