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1. An in-vehicle engine control device comprising:
an solenoid valve driving control circuit unit for a plurality of electromagnetic coils for driving solenoid valves in order to sequentially drive the solenoid valves for fuel injection provided in respective cylinders of a multi-cylinder engine; a boosting circuit unit that generates a boosted high voltage for performing rapid excitation on the electromagnetic coils; an arithmetic and control circuit unit that has a microprocessor as a main constituent element; and an injection control circuit unit that performs relay between the microprocessor and the solenoid valve driving control circuit unit, wherein the arithmetic and control circuit unit includes
a multi-channel A/D converter that is operated at low speed, cooperating with the microprocessor;a high-speed A/D converter with a plurality of channels; anda boosting control circuit portion, the microprocessor determines generation moments of valve opening command signals INJn for the electromagnetic coils and a valve opening command generation period Tn on the basis of signal voltages of at least some of an air flow sensor, an accelerator position sensor, and a fuel pressure sensor included in a low-speed analog sensor group, which are input to the multi-channel A/D converter, and operations of a crank angle sensor and an engine speed sensor of an opening and closing sensor group, the boosting circuit unit includes
an inductive element that is intermittently excited by a boosting opening and closing element from an in-vehicle battery;a current detection resistor that is connected in series to the inductive element; anda high-voltage capacitor that is charged by releasing electromagnetic energy stored in the inductive element via a charging diode when an inductive element current Ix proportional to a voltage across both ends of the current detection resistor is input to the arithmetic and control circuit unit, the boosting opening and closing element is controlled so as to be opened and closed in response to a boosting control signal Ex generated by the boosting control circuit portion, and the boosting opening and closing element is opened, a divided voltage of the voltage across both ends of the high-voltage capacitor is input to the arithmetic and control circuit unit as a boosted detection voltage Vx, an analog signal voltage proportional to the inductive element current Ix and the boosted detection voltage Vx is input to the high-speed A/D converter, and data which is digitally converted by the high-speed A/D converter is stored in a current present value register and a voltage present value register, the boosting control circuit portion includes
a higher-side current set register and a higher-side voltage set register that are transmitted from the microprocessor so as to be set;a higher-side current comparator and a higher-side voltage comparator that respectively compare the magnitudes of numerical values stored in the set registers and numerical values stored in the current present value register and voltage present value register; anda logical circuit portion, the logical circuit portion compares a value of a target higher-side current Ix2 stored in the higher-side current set register with a value of the inductive element current Ix transmitted from the boosting circuit unit by the higher-side current comparator, and when the value of the inductive element current Ix is smaller than the value of the target higher-side current Ix2, the logical circuit portion activates the boosting control signal Ex such that the boosting opening and closing element is driven so as to be closed, the logical circuit portion compares a value of a target higher-side voltage Vx2 stored in the higher-side voltage set register with a value of the boosted detection voltage Vx transmitted from the boosting circuit unit by using the higher-side voltage comparator, and when the value of the boosted detection voltage Vx is smaller than the value of the target higher-side voltage Vx2, the logical circuit portion makes the boosting control signal Ex valid such that the boosting opening and closing element is driven so as to be closed, and the arithmetic and control circuit unit is divided into a data processing function of setting numerical values of the target higher-side current Ix2 and the target higher-side voltage Vx2 in the boosting circuit unit by using the microprocessor and converting numerical values of the inductive element current Ix and boosted detection voltage Vx by using the high-speed A/D converter, and a digital logic control function of performing negative feedback control so as to obtain a relationship in which a target value as which the numerical value is set is the same as a monitored present value into which the numerical value is converted, by using the boosting control circuit portion. |
