Denso Corporation

Shinichi Maeda

Hiroyuki Ban

Junichi Nagata

Kiyoshi Yamamoto

Masahiro Kitagawa

Satoru Kawamoto

Hirokazu Itakura

Hiroyuki Kawabata

A constant voltage circuit robust to the input voltage lowering is disclosed. The invention is applied to a constant voltage circuit fed with an input voltage through first and second power conductors for transferring the input voltage to a load as an output voltage through an output transistor. An inventive constant voltage circuit is provided with a substitute circuit, responsive to a detection of the lowing of the input voltage to a predetermined voltage, for providing a substitute output path that is connected in parallel with the output transistor. Doing this minimize the degree of lowering of the second voltage due to the lowering of said first voltage. The output transistor may be nay of NPN and PNP transistors and P-type and N-type MOS FETs.

Constant voltage circuit with a substitute circuit in case of input voltage lowering

In an electromagnetic injector control apparatus for an engine, a capacitor is connected to a power supply and a solenoid of an injector for accumulating electric charge at a voltage higher than that of the power supply. A driving circuit controls transistors to supply energy from the power supply to the solenoid during an operation period of the solenoid. The driving circuit also controls a transistor so that a timing to start supplying the accumulated energy from the capacitor to the solenoid is delayed from a timing to start the operation of the solenoid as the voltage of the capacitor increases. Thus, the accumulated energy is used to speed up the operating response of the solenoid. The supply of the accumulated energy to the solenoid is stopped when a current flowing in the solenoid reaches a predetermined cut-off level. The capacitor is set to retain an offset of at least a predetermined quantity to be left therein when energy of a counter-electromotive force of the solenoid is recovered at the end of operation of the solenoid.

Electromagnetic load control apparatus having variable drive-starting energy supply

In a driving apparatus for piezo-stacks, a controller repeats switching operation for turning switching elements on/off to thereby attain a determined piezo-actuator voltage. An abnormality detecting circuit determines abnormality of the piezo-stacks by comparing the number of times of charging and the number of times of discharging, or charging/discharging time periods at this occasion with those at normal time.

Driving apparatus for piezo-actuator having abnormality detecting function

Growing community of inventors

Hekinan, Japan

Shinichi Maeda