Abstract: An actuator includes a motor operated by a controller through a pulse width modulation drive signal applied to a drive circuit that drives the motor. The actuator has an output shaft connected to a coupling structure for manipulating a device such as a variable geometry turbine (VGT) or an exhaust gas recirculation (EGR) valve. The device has a range of motion limited by first and second mechanical stops located at opposing low and high ends of the range. The controller learns the location of the mechanical stops during calibration. An external control unit transmits a desired position to the actuator. A protocol allows the external control unit to implicitly request a positioning mode by virtue of what value range the desired position falls into. The controller is configured to limit the drive signal to a non-harmful level when one of the positioning modes calls for pushing the device against one of the stops.

Abstract: An actuator includes a motor operated by a controller through a pulse width modulation drive signal applied to a drive circuit that drives the motor. The actuator has an output shaft connected to a coupling structure for manipulating a device such as a variable geometry turbine (VGT) or an exhaust gas recirculation (EGR) valve. The device has a range of motion limited by first and second mechanical stops located at opposing low and high ends of the range. The controller learns the location of the mechanical stops during calibration. An external control unit transmits a desired position to the actuator. A protocol allows the external control unit to implicitly request a positioning mode by virtue of what value range the desired position falls into. The controller is configured to limit the drive signal to a non-harmful level when one of the positioning modes calls for pushing the device against one of the stops.

Abstract: An actuator includes a motor operated by a controller through a pulse width modulation drive signal applied to a drive circuit that drives the motor. The actuator has an output shaft connected to a coupling structure for manipulating a device such as a variable geometry turbine (VGT) or an exhaust gas recirculation (EGR) valve. The device has a range of motion limited by first and second mechanical stops located at opposing low and high ends of the range. The controller learns the location of the mechanical stops during calibration. An external control unit transmits a desired position to the actuator. A protocol allows the external control unit to implicitly request a positioning mode by virtue of what value range the desired position falls into. The controller is configured to limit the drive signal to a non-harmful level when one of the positioning modes calls for pushing the device against one of the stops.

Abstract: An actuator includes a motor operated by a controller through a pulse width modulation drive signal applied to a drive circuit that drives the motor. The actuator has an output shaft connected to a coupling structure for manipulating a device such as a variable geometry turbine (VGT) or an exhaust gas recirculation (EGR) valve. The device has a range of motion limited by first and second mechanical stops located at opposing low and high ends of the range. The controller learns the location of the mechanical stops during calibration. An external control unit transmits a desired position to the actuator. A protocol allows the external control unit to implicitly request a positioning mode by virtue of what value range the desired position falls into. The controller is configured to limit the drive signal to a non-harmful level when one of the positioning modes calls for pushing the device against one of the stops.

Abstract: A fuel composition sensor provides to a voltage divider comprising sensor and reference capacitors a voltage which oscillates between two voltages at a comparatively low frequency, such as 6 KHz, for lower power dissipation, but which switches fast to produce periodic fast voltage changes across the voltage divider to produce voltage spikes at the junction of the capacitors indicative of the capacitance ratio and thus of fuel composition.

Abstract: A fuel composition sensor for a fuel line carrying a mixture of two fuels provides a fuel composition signal VOUT to an engine control computer having a computer analog reference voltage ECM referenced to a computer ground EGD. The sensor has a sensor analog reference voltage VREF referenced to a sensor ground GND, which may differ from the computer ground EGD. An input isolation amplifier derives the sensor analog reference voltage VREF relative to GND ratiometrically from the computer analog reference voltage ECM referenced to EGD; and an output isolation amplifier derives the fuel composition signal VOUT referenced to EGD ratiometrically from the difference between a fuel composition responsive sensor signal VSIG and its minimum possible value, corresponding to a sensed fuel composition of only one of the fuels, relative to GND. The sensor may comprise a capacitive voltage divider and provide sensor voltage VSIG also having a maximum value corresponding to a sensed fuel composition of only the other fuel.

Abstract: In a fuel composition sensor in which a fast step voltage is applied to a capacitive voltage divider comprising a sensor capacitance and a reference capacitance in series, a padding capacitor is connected in parallel with the sensor capacitor to produce a more linear output across the full range of fuel composition. The value of the padding capacitor is sufficient to produce a capacitance ratio of the voltage divider substantially less than one and, in particular, less than two thirds.

Abstract: An airflow sensor in a flat chip configuration having sensing elements on only one side is subject to causing turbulence in the airflow which has a deleterious effect on the flow signal. The turbulence is diminished or prevented and sensitivity is enhanced by tilting the plane of the sensor a few degrees to the flow direction. Flow in both directions through a passage is measured by bending the passage at the sensor location so that the flow in either direction is inclined to the surface carrying the sensing elements. Flow in both directions through a straight passage is measured by providing the sensor with sensing elements on both sides and mounting the sensor at a tilt so that flow in both directions is inclined to a surface of the sensor.