JP2004132281A - Fuel injection system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control fuel injection at low cost without increasing the size of a fuel injection system. <P>SOLUTION: A fuel injection system has a crank position detection unit 5 to detect the crank position based on the timing at which the voltage is induced in a power generation coil 1 of a CDI igniter, and allows a fuel injection control unit 6 to determine the fuel injection timing of a fuel injection valve 7 with the crank position detected by the crank position detection unit 5 as a reference. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection device for an internal combustion engine.
[0002]
[Prior art]
For example, a small internal combustion engine used for a mower or a sprayer is provided with an air cleaner for sucking outside air, an intake duct, a throttle valve and an intake port, and a fuel injection for supplying fuel to the intake port. A valve may be provided. This fuel injection valve is, for example, an electromagnetic fuel injection valve that is energized to open when the solenoid is energized, and is shut off when energization is stopped.The fuel injection control unit adjusts the timing to the stroke of each cylinder and uses a dedicated pulse. The valve is opened by being energized by an injection pulse generated by the coil, and the fuel pumped from the fuel pump is injected at a predetermined pressure.
[0003]
An ignition plug is provided in each combustion chamber of the internal combustion engine. By generating fireworks on the ignition plug, a mixture of the fuel and the outside air (air) can be ignited and burned. At this time, exhaust gas is discharged from the combustion chamber to the outside of the combustion chamber via an exhaust port, an exhaust duct, and a muffler. The fuel injection control unit includes a microcomputer, and controls the operation of the fuel injection valve in response to an output signal from the dedicated pulse coil.
[0004]
[Problems to be solved by the invention]
However, in a conventional fuel injection device for an internal combustion engine, it is necessary to generate an injection pulse used for fuel injection control by using a dedicated pulse coil. There is a problem that the installation of the coil causes an increase in size and cost of the device.
[0005]
The present invention solves the above-described conventional problems. In an internal combustion engine having a CDI ignition device, the configuration is increased by using an induced voltage of a power generation coil included in the CDI device. It is an object of the present invention to provide a fuel injection device for an internal combustion engine that can realize fuel injection control of a fuel injection valve without cost and at low cost.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a fuel injection device for an internal combustion engine according to the invention of claim 1 has a crank position detection unit that detects a crank position at a timing when a voltage is induced in a power generation coil of a CDI ignition device. The fuel injection control unit determines the fuel injection timing of the fuel injection valve based on the crank position detected by the crank position detection unit. Thus, fuel injection control can be realized at low cost by using the power generation coil of the existing ignition device without providing a dedicated pulse coil.
[0007]
The fuel injection device for an internal combustion engine according to claim 2 is characterized in that the fuel injection control unit performs a fuel cut to a fuel injection valve at the same time as the ignition timing retard control by the CDI ignition device. Thereby, it is possible to prevent seizure and generation of exhaust gas together with prevention of excessive rotation of the internal combustion engine.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a main part showing an internal combustion engine fuel injection device of the present invention. In FIG. 1, reference numeral 1 denotes a power generation coil of a CDI (Capacitor Discharge Igniter) ignition device; An ignition control unit 4 that controls the supply of an ignition current to the ignition coil 3 is an ignition plug that receives a high-voltage ignition pulse from the ignition coil 3 and generates fireworks.
[0009]
Further, a crank position detecting unit 5 is connected to the power generating coil 1, and the crank position detecting unit 5 determines a fuel injection timing by a fuel injection valve based on the crank position detected by the crank position detecting unit 5. 6 is connected. Reference numeral 7 denotes a fuel injection valve that is driven to open and close in response to the output of the fuel injection control unit 6.
[0010]
The CDI ignition device is configured as shown in FIGS. 2 and 3, for example. The CDI igniter includes a rotor 14 having magnetic poles 12 and 13 disposed with a magnet 11 interposed therebetween, a core 15 disposed opposite to the rotor 14 and wound with a power generation coil 1, and a positive induction coil of the power generation coil 1. An ignition charge / discharge capacitor 17 for charging a voltage via a diode 16 and an ignition control unit 2 for supplying the charge of the ignition charge / discharge capacitor 17 to an ignition coil at a predetermined timing.
[0011]
On the other hand, the induced voltage waveform of the power generation coil 1 of the CDI ignition device is as shown in FIG. 4A, and the generation timing of the induced voltage is about 60 ° before the top dead center (TDC). The timing of the rise of the induced voltage is also the timing at which the intake port of the internal combustion engine opens. If the fuel is injected from the fuel injection valve at this timing, the fuel will not be blown back but will be quickly drawn into the combustion chamber, and the efficiency will be improved. It can be combusted. Note that approximately 30 ° before the top dead center is the ignition position by the ignition plug 4. Therefore, the crank position detecting section 5 detects the generation timing of the voltage waveform of the power generation coil 1 in the CDI ignition device, thereby detecting the crank position (crank angle), that is, opening of the intake port, as shown in FIG. The position is known, whereby the fuel injection control unit 6 determines the fuel injection timing by the fuel injection valve 7 as shown in FIG.
[0012]
In FIG. 4, t1 is the cycle of fuel injection, and the rotation speed of the internal combustion engine can be easily obtained from the number of pulses obtained for each rotation of the rotor 14. t2 is a fuel injection time.
[0013]
Further, the generation timing of the induced voltage of the power generation coil 1 may be different depending on the shape and size of the magnetic poles 12 and 13 and the core 15. In such a case, the fuel injection control unit 6 calculates the crank angle and determines an appropriate injection timing. For example, the start position of the injection time t2 can be delayed with respect to the injection cycle t1 in FIG. 4, or the injection can be performed intermittently instead of every time.
[0014]
Further, when the ignition control unit 2 performs the overspeed prevention operation, by performing the fuel cut on the fuel injection valve 7 under the control of the fuel injection control unit 6, the emission of the exhaust gas can be suppressed. In the case of oil separation and refueling, seizure of the internal combustion engine can be prevented by cutting only the fuel.
[0015]
【The invention's effect】
As described above, according to the present invention, the crank position detecting unit that detects the crank position based on the timing at which the voltage is induced in the power generation coil of the CDI ignition device is provided, and the crank position detected by the crank position detecting unit is used as a reference. And the fuel injection control unit decides the fuel injection timing by the fuel injection valve.Therefore, without using a dedicated pulse coil, the existing power generation coil is used, and the fuel injection control is simple and low cost. Can be realized.
[0016]
In addition, by causing the fuel injection control unit to cut the fuel to the fuel injection valve at the same time as the ignition timing retard control by the CDI ignition device, seizure and emission of exhaust gas can be performed together with the overspeed prevention function of the internal combustion engine. Generation can be effectively suppressed.
[Brief description of the drawings]
FIG. 1 is a block diagram conceptually showing a fuel injection device for an internal combustion engine according to one embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an arrangement relationship between a core and a rotor of the CDI ignition device used in the present invention.
FIG. 3 is a circuit diagram showing a CDI ignition device used in the present invention.
FIG. 4 is a timing chart showing waveforms of voltages and signals in respective blocks in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power generation coil 5 Crank position detection part 6 Fuel injection control part 7 Fuel injection valve

Claims (2)

A crank position detecting unit for detecting a crank position at a timing when a voltage is induced in the power generating coil of the CDI ignition device; and a fuel injection by a fuel injection valve based on the crank position detected by the crank position detecting unit A fuel injection device for an internal combustion engine, comprising: a fuel injection control unit 6 for determining timing. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein a fuel cut to a fuel injection valve 7 is performed by the fuel injection control unit 6 simultaneously with the ignition timing retard control by the CDI ignition device. 3.

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