A cycle time of pulses converted from an electrical signal generated at a rotational sensor is counted. In determining a cycle of the pulses, either a rising edge or a falling edge of the pulse is selected. As the selection of the either edge affects accuracy of the rotational speed measurement, two modes are proposed. One is suitable for a lower speed range in which either of the rising and falling edges is selected for every pulse monitoring period considering the relative phase position of the pulse and the pulse monitoring period. The other is suitable for a higher speed range in which one fixed edge is utilized. Here the edge is selected depending on the winding direction of the electric wire of the pick-up coil of the rotational sensor and independent of the pulse monitoring period.
An angular velocity sensor for a rotor (2) and method of determining angular velocity in which the position at which event generation means (4) pass sensing means (5) is determined using information from the times at which the event generation means (4) passed the sensing means (5) during at least one previous complete revolution to of the rotor (2). Especially applicable to use of Hall Effect Sensors to detect commutation points of a brushless permanent magnet rotor in an Electric Power Assisted Steering apparatus.
A single integrated circuit operable in either a single chip mode or a host dependent mode. The integrated circuit comprises mode select circuitry for selecting the single chip mode or the host dependent mode, data acquisition circuitry for acquiring signals pertaining to a parameter to be displayed, control circuitry including serial engine circuitry for computing a gage displacement value based on the signals acquired by the data acquisition circuitry and a memory register for storing a gage displacement command, serial circuitry effective when the single chip mode is selected to store the computer gage displacement value in the memory register, and when the host dependent mode is selected to store a remotely generated displacement value in the memory register, signal conversion circuitry for converting the gage displacement command stored in the memory register to air core gage assembly drive commands and providing the same on a serial communication channel, and output circuitry for driving the air core gage assembly in response to the commands received on the serial communication channel.
A method and a device for detecting rotational speed with an inductive sensor in which a sinusoidal potential is induced by a magnet wheel and then fed to a filter with a comparator connected downstream of the filter and therefrom into a square-wave signal that is essentially proportional to the rotational speed of the magnet wheel. This output signal of the comparator is evaluated in a microcomputer. In this evaluation, only the same type of edges of the comparator signal are evaluated, specifically those in which the intervals fluctuate less when considered over a certain time span. The microcomputer here can initially evaluate both types of edges, that is, positive and negative edges, and then use those edges in which smaller fluctuations, that is, interference, are determined for calculating the rotational speed. The microcomputer can also first evaluate only one type of edges and change over to edges of the other type only if the former displays interference above a present value. If the edges of the other type show even greater interference than those of the first type, then the system switches back to the first type. The changeover can be done either in the microcomputer or externally. The external changeover to the type of edge can be done by an external inverter or by reversing the polarity of the sensor output signals by means of a controllable switch.
Apparatus for developing a series of square-wave pulses from an alternating voltage that is generated in the pick-up coil of a variable reluctance sensor that is associated with a slotted wheel that is driven by the crankshaft of an internal combustion engine. The system has an adaptive control which comprises a peak detector, a capacitor and a voltage comparator. The capacitor is charged to a peak voltage that corresponds to the peak value fo the positive half-cycles of the alternating voltage. The comparator is connected to compare the peak voltage and a voltage that corresponds to the magnitude of the positive half-cycles. A diode is connected between the pick-up coil and the peak detector which prevents charging of the capacitor and accordingly prevents adaptive control until the voltage induced in the pick-up coil is high enough to cause the diode to conduct in the forward direction.
A rotational speed detector for an internal combustion engine comprises a waveform processor for eliminating pulses generated within a predetermined period of time after a certain pulse appears and a measuring circuit for measuring a rotational speed based on outputs from the waveform processor. The waveform processor of the rotational speed detector thus eliminates the effects of such an unexpected pulse generated, for example, by the vibration of the ignition coil for the engine. Consequently, the measuring means detects the rotational speed accurately without measuring the unexpected pulse.
