Abstract: In an internal combustion engine control system, an electronic circuit accepts a non-linear analog signal from a Mass Air Flow (MAF) sensor and converts it to a digital signal by means of a linear or non-linear analog to digital (A/D) converter. The digital signal is then processed by a two-dimensional look-up table which includes corrections for the MAF sensor non-linearity and additional corrections for non-linearity of the A/D converter. This linearized MAF signal is then integrated or averaged to provide air mass per engine event or average mass air flow during an event. This circuit is useful in obtaining better accuracy in fuel management systems that use MAF sensors, particularly if variable valve control is included as part of the control system. The look up table and integrator can be easily implemented in a digital signal processor or microcontroller.

Abstract: The actual lift of a valve is monitored by a lift sensor that is coupled to an electronic valve controller by a lift signal processing circuit, and the electronic valve controller issues a control signal that is calculated to secure as faithful correspondence as possible of this lift signal to a command signal that the electronic valve controller receives from an electronic engine management controller. The processing circuit functions to disclose to the electronic valve controller the actual opening and closing instants of the valve in a manner that amounts to the sensor being precisely re-calibrated each time that it closes.

Abstract: An automatic speed control for a heavy duty vehicle includes a controller which regulates communication between a compressed air source and an air actuated throttle mechanism. The controller generates a control signal which is a function of a speed error signal and the position of the air actuated throttle to regulate the compressed air source. The speed error signal is calculated as the difference between a commanded speed signal and an actual speed signal. To generate the control signal, the error signal and throttle position signal are operated on by different lead-lag transfer functions. These lead-lag terms are thereafter combined with a proportional speed error term to yield the desired control signal. The system further includes a throttle control feature for powering auxiliary equipment when the actual speed signal is zero. Another feature of the control limits the commanded speed signal to a set value when it exceeds a predetermined limit.

Abstract: A hybrid electronic control unit for regulating the air/fuel ratio of an internal combustion engine is disclosed. The electronic control unit is divided into two functionally distinct parts including an analog function generator and a digital function generator. The analog function generator receives analog signals to process efficiently by analog scaling, amplification, multiplication, and division while the digital function generator receives digital and logic inputs to process efficiently by addition, subtraction, and comparison. The analog function generator interfaces with the digital function generator by an analog signal from a D/A converter and other unconverted digital output signals from the digital function generator. Preferably, the analog function generator provides an open loop air/fuel ratio calibration based upon a speed density calculation including special condition corrections to the base calibration.

Abstract: A method and apparatus for controlling the various functions of an internal combustion engine using a program-controlled microprocessor having a memory preprogrammed with various control laws and associated control schedules receives information concerning one or more engine-operating parameters such as manifold pressure, throttle position, engine coolant temperature, air temperature, engine speed or period and the like. These parameters are sensed and then supplied to input circuits for signal conditioning and conversion into digital words usable by the microprocessor. The microprocessor system computes a digital word indicative of a computer-commanded engine control operation and output circuitry responds to predetermined computer-generated commands and to the computed digital command words for converting them to corresponding pulse-width control signals for controlling such engine operations as fuel-injection, ignition timing, proportional and/or on-off EGR control, and the like.

Abstract: A hybrid electronic control unit for regulating the air/fuel ratio of an internal combustion engine is disclosed. The electronic control unit is divided into two functionally distinct parts including an analog function generator and a digital function generator. The analog function generator receives analog signals to process efficiently by analog scaling, amplification, multiplication, and division while the digital function generator receives digital and logic inputs to process efficiently by addition, subtraction, and comparison. The analog function generator interfaces with the digital function generator by an analog signal from a D/A converter and other unconverted digital output signals from the digital function generator. Preferably, the analog function generator provides an open loop air/fuel ratio calibration based upon a speed density calculation including special condition corrections to the base calibration.

Abstract: A single pressure sensor is caused to provide a pressure measurement at two separate pressure regions through the use of a differential pressure switch whose switch over point occurs when the two regions are at a fixed pressure differential or offset. The sensor is connected to sense a first region with a sensor output signal being compared to a signal related to the count in a counter. Upon switch over the counter is actuated to make a signal equal to the sensor output signal. The counter signal, compensated for the offset, is related to the pressure at the second region.