Fuel injection device of internal combustion engine

Patent metadata

Field	Value
Publication number	US-10145324-B2
Application number	US-201615074595-A
Country	US
Kind code	B2
Filing date	Mar 18, 2016
Priority date	May 8, 2015
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A step-down circuit is connected to an output of a step-up circuit that steps up a battery voltage, and an output of the step-down circuit is connected to a power supply input terminal of a CPU via an FET. The step-down circuit is normally maintained in an inactive state and, in response to an ignition switch being turned off, the CPU causes the step-down circuit to actuate and a stepped-down voltage (equal to a stabilized voltage) is output from the step-down circuit. The stepped-down voltage is further stepped down to a CPU power supply voltage, and the CPU power supply voltage is supplied to the power supply input terminal of the CPU. This allows the residual charge of the step-up circuit to be dissipated by the step-down circuit and the CPU.

First claim

What is claimed is:

1. A fuel injection device of an internal combustion engine, the fuel injection device comprising:
a fuel injection valve that injects fuel directly into a combustion chamber of the internal combustion engine;
a central processing unit (CPU) configured to control operation of the fuel injection valve;
a battery;
a step-up circuit that is connected to the battery, wherein the step-up circuit is configured to step up a battery output voltage of the battery to output a stepped-up voltage to drive the fuel injection valve; and
a step-down circuit that is connected to an output side of the step-up circuit, wherein the step-down circuit is configured to dissipate residual charge in the step-up circuit when an ignition switch is turned off, and wherein the ignition switch turns on or turns off a first power supply voltage supplied to the CPU.

2. The fuel injection device according to claim 1 ,
wherein the step-down circuit is configured to step down the stepped-up voltage to output a stepped-down voltage, wherein the step-down circuit includes a circuit including the CPU, and
wherein the CPU is configured to use the stepped-down voltage as a second power supply voltage for performing a shutdown process after the ignition switch is turned off.

3. The fuel injection device according to claim 2 , wherein the CPU is configured to actuate the step-down circuit when the internal combustion engine is restarted during an idling-stop operation that temporarily stops the internal combustion engine, and use the stepped-down voltage as the second power supply voltage.

4. The fuel injection device according to claim 2 , further comprising a sensor to detect a temperature of the internal combustion engine,
wherein the CPU is configured to:
actuate the step-down circuit when the internal combustion engine is started at the detected temperature that is lower than a threshold value; and

use the stepped-down voltage as the second power supply voltage.

5. The fuel injection device according to claim 4 , wherein the threshold value is 10 degrees Celsius.

6. A fuel injection method for an internal combustion engine, the method comprising:
injecting fuel, by a fuel injection valve, into a combustion chamber of the internal combustion engine;
controlling, by a central processing unit (CPU), operation of the fuel injection valve;
stepping-up, by a step-up circuit that is connected to a battery, a battery output voltage to output a stepped-up voltage to drive the fuel injection valve; and
dissipating, by a step-down circuit that is connected to an output side of the step-up circuit, a residual charge in the step-up circuit when an ignition switch is turned off, wherein the ignition switch turns on or turns off a first power supply voltage supplied to the CPU.

7. The method according to claim 6 ,
wherein the step-down circuit steps down the stepped-up voltage to output a stepped-down voltage, wherein the step-down circuit includes a circuit including the CPU, and
wherein the CPU uses the stepped-down voltage as a second power supply voltage for performing a shutdown process after the ignition switch is turned off.

8. The method according to claim 7 , further comprising actuating, by the CPU, the step-down circuit when the internal combustion engine is restarted during an idling-stop operation that temporarily stops the internal combustion engine, and using the stepped-down voltage as the second power supply voltage.

9. The method according to claim 7 , further comprising:
detecting, by a sensor, a temperature of the internal combustion engine; and
actuating, by the CPU, the step-down circuit when the internal combustion engine is started at the detected temperature that is lower than a threshold value, and using the stepped-down voltage as the second power supply voltage.

10. The method according to claim 9 , wherein the threshold value is 10 degrees Celsius.

Assignees

• Honda Motor Co Ltd

Inventors

• Kugumiya Yohei
• Kurauchi Atsushi

Classifications

• F02D2200/503

  Battery correction, i.e. corrections as a function of the state of the battery, its output or its type · CPC title

• F02N11/0814

  comprising means for controlling automatic idle-start-stop · CPC title

• F02D2041/2006

  by using a boost capacitor · CPC title

• Y02T10/7005

  Cross-Sectional Technologies · mapped topic

• F02D41/064

  at cold start (F02D41/067 takes precedence) · CPC title