Nippondenso Co., Ltd.

Nippon Soken, Inc.

Kunio Makita

Masahiro Sato

Tadashi Hattori

Minoru Nishida

Yoshiki Ueno

Masaaki Kurii

A rotational position detecting apparatus includes a rotating member magnetized to induce a large number of magnetic poles on the periphery thereof except at a portion indicative of a rotational reference position, and a pair of magnetically sensitive elements for detecting the magnetic flux from the magnetic poles so as to generate rotational angle signals and reference position signals. The pair of magnetically sensitive elements are positioned side by side such that their output signals generated in response to the magnetic flux from the magnetic poles are different in phase by half the period, and the difference between the outputs of the magnetically sensitive elements is obtained by a differential circuit whose output has an amplitude which is two times the amplitude of the outputs of the magnetically sensitive elements. The magnetic poles on the periphery of the rotating member are dropped out at the reference position in such a manner that the output AC component of the respective magnetically sensitive elements is dropped out at the reference position in a point symmetrical manner on both sides of the zero level of the AC component, thus stably supplying the rotational angle signals and the reference position signals.

Rotational position detecting apparatus

A single sensor is located close to a ring gear on the periphery of which teeth are disposed equiangularly except at an angular reference position. When the ring gear rotates, the sensor generates output signals, with the period of the output pulse which corresponds to the reference position being larger than that of the other output pulses which correspond to the angular positions. A capacitor is charged during half of each the periods of the output pulses, so that the reference position can be discriminated by comparing the amplitude of the charged voltage or the discharging period of the capacitor with a predetermined value.

Rotational position detector

This invention discloses a rotational position detecting apparatus for an internal combustion engine for detecting the rotational position of a crank shaft of the engine. The apparatus comprises a rotating disk driven by the engine and giving a large number of angular information signals and also a rotating disk having one reference information on the periphery thereof, an angle sensor for detecting the angular informations on the disk, a rotational reference sensor for detecting the reference information on the disk, waveform reshaping circuits for reshaping the output signals of said both sensors, and an electric circuit for determining the angular position and the reference position from the outputs of said waveform reshaping circuits, wherein a logical product of the reshaped output of the angle sensor and the reshaped output of the reference sensor is implemented, and the time of either one of the rise or fall of an output signal of the logical product is set to be an angular position, while the other one is set to be a reference position.

The angle through which the crankshaft of an engine rotates within any given time is proportional to the rotational speed of the engine. Consequently, where the ignition system is of the type in which the integrated value of an integrator circuit or the count value of a counter circuit is varied so as to control the spark advance, if the rate of increase or decrease of the integrated value or the count value within a portion of the increasing or decreasing time is made different from that within the remaining portion of the time, the integrated value or the count value is directly affected by the engine rotational speed. In other words, the spark advance is directly controlled by the factor of the engine rotational speed, thus ensuring satisfactory response characteristic and accuracy for the ignition system.

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Chiryu, Japan

Kunio Makita