Denso Corporation

Toshio Nishimura

Akira Ito

Takayoshi Honda

Atsushi Ito

Takamasa Oguri

Hirokazu Tsuji

Hirotaka Kunibe

Yoshiyasu Futamura

Tokutada Takahashi

Shoukichi Hosoe

Takeshi Akiyoshi

An injection controller has a voltage applicator that applies a voltage to a driving coil of an injection valve. After a voltage is applied to the driving coil with a peak current for opening the injection valve, the voltage applicator applies a power supply voltage to the driving coil in an ON-OFF manner, to supply the driving coil with a less-than-peak current. A comparator detects whether a terminal voltage at a terminal of the coil is less than a predetermined threshold voltage. Upon detecting that the terminal voltage is less than the threshold voltage, a discharge switch applies a boosted voltage to the driving coil.

Injection controller

An injection control unit includes a constant-current control unit executing a constant current control to control a current of a coil to be in a predetermined current range lower than a peak current by allowing or interrupting a first voltage applied to the coil after the peak current starting to open an injector is applied to the coil driving the injector, and a high-voltage applying control unit applying a second voltage higher than the first voltage to the coil in a case where a condition that the current of the coil becomes lower than the predetermined current range is met when the constant-current control unit executes the constant current control.

Injection control unit

A fuel injection controller has terminals which can be connected to the coil of the fuel injector. A first valve-open control portion supplies the valve-opening voltage to the terminals for opening the fuel injector. The first valve-open control portion stops supplying the electric supply to the coil before the fuel injector is positioned at a full-open position. Before the fuel injector is fully closed, a small injection quantity can be obtained. A demagnetization portion forms a demagnetization circuit for demagnetizing the magnetism remaining in the coil. A normal-injection portion controls the fuel injector at full-open position.

Fuel injection controller

In a fuel injection control apparatus, an injector is driven to open its valve by supplying a coil of the injector with a current during a high-level period of a power supply command signal outputted from a microcomputer. A valve-closing time of the injector is detected based on a coil current, which decreases from a fall time of the power supply command signal. By comparing the coil current with plural equally-divided comparison threshold values by comparators, times are detected when the coil current decreases to the comparison threshold values, respectively. The valve-closing time is detected based on time differences among the detected times.

Fuel injection control apparatus

An electromagnetic-valve controller includes a control switch, a control portion regulating a supply current supplied to the electromagnetic valve by controlling a drive of the control switch and controlling to open or close the electromagnetic valve, and a current detection portion detecting the supply current. The control portion controls the drive of the control switch based on a detection result of the current detection portion. The control portion controls the drive of the control switch by using a first pulse signal having a duty ratio that is variable, in a closed period. The control portion controls the drive of the control switch by using a second pulse signal maintaining the supply current to be constant so as to maintain the electromagnetic valve to be in the fully closed state, in a closed-state maintaining period.

Electromagnetic-valve controller

A fuel injection controller is provided with a detection control portion which detects a valve-opening time. The detection control portion supplies the low valve-opening voltage to the fuel injector from a low voltage supply. An electric current flowing through a coil is gradually increased. When the fuel injector is fully opened, an inflection point appears on a waveform of an electric current. A valve-open detecting portion detects the inflection point and identifies a valve-opening time. A correction-amount computing portion computes a correction amount of a fuel injection quantity due to an error of the valve-opening time. In a succeeding fuel injection, the correction portion corrects an electric supply period. As a result, the error of the fuel injection quantity due to an error of valve-opening time is corrected.

A fuel injection controller includes a transistor downstream of a coil of a fuel injector, two transistors applying a source voltage to an upstream of the coil, a diode refluxing an electric current to the coil from a ground, and a Zener diode provided to promptly consume the counter electromotive force generated in the coil when one of the transistors is turned OFF and the transistor is turned OFF, after an injector-drive-period of the fuel injector is terminated. When a microcomputer measures an injector current 'I' decreasing from a time of the termination of an injector-drive-period, a drive control circuit delays an OFF time of the transistor relative to a time of a termination of an injector-drive-period, whereby the injector current 'I' decreases gradually.

A first judgment circuit and a second judgment circuit are adapted to set a judging signal high when a judgment data sent from a microprocessor indicates failure. The high level judging signal triggers a forced idle command connected to a motor driver, to be high level whereby the motor is forcibly suspended. Subsequently, when a reset command is accidentally transmitted by the microprocessor due to an unexpected fault, a first judging signal from the first judgment circuit is reset to low level. However, a second judging signal from the second judgment circuit remains high level. As a result, the forced idle command stays high level.

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Anjo, Japan

Toshio Nishimura