Abstract: A variable power drivetrain engine control system for a heavy duty vehicle such as a tractor/trailer combination or truck is disclosed. The engine control system provides higher output capability for the engine of the vehicle in accordance with certain detected conditions. If the vehicle speed falls a predetermined DELTA miles/hour below a LEARNED SPEED of the vehicle, the engine is enabled to operate at a higher power output capability until the vehicle resumes the LEARNED SPEED. Further, high output capability is enabled when the vehicle deceleration is in excess of a predetermined deceleration rate. Again, the high output capability is disabled once the vehicle retains the LEARNED SPEED velocity. The quantity DELTA can be variable with respect to actual vehicle speed to provide more responsive operation of the variable power drivetrain system thereby providing improved responsiveness to road conditions in accordance with relative vehicle speed.

Abstract: A circuit is described for energizing an electromagnetically operated fuel injector from an unregulated voltage source in response to an injection command pulse. The injector pull-in current is provided by directly coupling the unregulated voltage across the injector upon the initiation of the injection command pulse. The injector current is thereafter reduced to a lower hold-in value. The circuit is voltage compensated by a pair of timers the first of which compensates for the voltage dependent injector pull-in time by adjusting the time that the unregulated voltage is directly applied across the injector as a function of the value of the unregulated voltage to insure that the injector is energized for all values of the unregulated voltage while minimizing the time period that the unregulated voltage is directly coupled across the fuel injector.

Abstract: An apparatus for providing an output digital signal when the magnitude of a monitored parameter is within a critical range. An oscillator repeatedly charges each of first and second capacitors to a predetermined voltage level. A monitoring resistor is parallel coupled with the first capacitor and has a resistance progressively changing with the magnitude of the parameter to define a rate of discharge of the first capacitor, between repeated chargings, determined by the parameter. A reference resistor is parallel coupled with the second capacitor and has a resistance equal to the resistance of the monitoring resistor when the magnitude of the monitored parameter is at the threshold of the critical range and defines a first reference rate of discharge of the second capacitor between repeated chargings. The voltages across the first and second capacitors are monitored by respective threshold detectors, each of which provides an output when the voltage across the respective capacitor exceeds a specified level.

Abstract: An apparatus for providing a warning when the magnitude of a monitored parameter, such as vehicle fuel level, is within a critical range. A charge pump repeatedly charges a variable capacitor having a capacitance progressively changing with the magnitude of the monitored parameter and a reference capacitor having a capacitance equal to the capacitance of the variable capacitor when the magnitude of the monitored parameter is at the threshold of the critical range. After each charge, the two capacitors are discharged at a controlled rate with their voltage charge being monitored by threshold detectors, each of which provides an output when the voltage across the respective capacitor exceeds a specified level.