JPS5820932A - Fuel injection controller - Google Patents

Abstract

PURPOSE:To accomplish a favorable combustion balance between cylinders, by injecting fuel by a signal of closing an ignition switch for the first cylinder. CONSTITUTION:When the fuel is injected synchronously with the ignition of the first cylinder, the intake condition largely differs between three cylinders, that is, the intake valve of the first cylinder being in the combustion stroke is closed, the intake valve of the second cyliner being in the intake stroke is opened, and the intake valve of the third cylinder being in the exhaust stroke is closed. Since the intake valve of the third cylinder is open at the time of fuel injection, injecting the fuel at the moment the piston is lowered to a position in proximity to the bottom dead center results in that the intake condition of the third cylinder approaches those of the other cylinders since the intake action of the third cylinder has been weakened even though the intake valve is stil opened. Accordingly, when the fuel is injected at the time of closing the ignition switch for the first cylinder, the intake condition of the third cylinder approaches to those of the other cylinders, a favorable combustion balance is attained between the cylinders, and smooth rotation can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control device suitable for a live cylinder engine.

Fuel injection devices that inject fuel into the intake pipe generally use a simultaneous method at every revolution to simplify the control system for the amount of fuel injection.
For example, in a 6-cylinder engine, half of the amount required for combustion in the gold cylinder is injected in one revolution of the engine, and the remaining half is injected in the next revolution, and the injection timing is determined by the ignition signal. In the case of a 6-cylinder engine, as shown in Figure 1 (person), there is a method that synchronizes the frequency with the ignition signal, which has 3 pulses per engine revolution, and divides it by b to generate the injection timing signal. A lot is taken. Even in the case of a four-cylinder engine, since the injection timing signal is obtained by dividing the ignition signal, which has two pulses per revolution of the engine, by one, simultaneous injection can be easily carried out at every revolution.

However, in the case of a three-cylinder engine, as shown in Figure 1 (B), the ignition signal has two pulses and one pulse per engine revolution.
Since the pulses are repeated alternately, unlike 6-cylinder engines and 4-cylinder engines, the injection timing signal can be obtained by synchronizing with the branched wave of the ignition signal, and the fuel injection cannot be performed once per revolution, but rather in 2 revolutions. The frequency of the ignition signal, which has three pulses, is divided by b, and fuel is injected once every two revolutions.

In other words, in a 3-cylinder engine, 3
The entire amount of fuel for each cylinder is injected.

For this reason, in a three-cylinder engine, the amount of injection per injection is large, and it is important to know whether each cylinder is in the intake, compression, explosion, or exhaust stroke at the injection timing, and especially whether the intake valve is open or not. Conditions were very different, and fuel distribution among the three cylinders was unstable. Therefore, the air-fuel ratio increases due to overabsorption,
This led to an increase in unburned hydrocarbons (HO).

An object of the present invention is to provide a fuel injection control device that can stabilize fuel distribution among three cylinders and improve combustion balance to obtain smooth engine rotation and improve exhaust gas (HO) characteristics. There is a particular thing.

In order to achieve the above object, the fuel injection control device ii according to the present invention provides a fuel injection control device ii for every two rotations of the engine. In a three-cylinder engine in which the third and second cylinders are ignited in this order, the closing point of the ignition point corresponding to the ignition of the first cylinder, which opens and closes in synchronization with the engine rotation, is detected and It is configured to inject city fuel.

According to the above structure, the object of the present invention can be completely achieved.

The present invention will be described in more detail below with reference to the drawings and in comparison with conventional examples.

FIG. 2 is a diagram showing the injection timing and the timing between the intake valves of each cylinder. In Figure 2, the vertical axis (1), (3), and (2) $1 indicate the h9 ignition order for the 1st cylinder, 3rd cylinder, and @2 cylinder, respectively, and the horizontal axis indicates the crank angle, and the TH top dead end. point,
B is the bottom dead center.

The ignition timing is 8 rx and 10 degrees before the top dead center of each cylinder, and the ignition signal is divided by b at the conventional fuel injection timing to inject in synchronization with the ignition of the first cylinder. When the injection is synchronized with the ignition of the first cylinder (time point ① in Fig. 2), the intake valves of each cylinder are closed during the combustion stroke for the first cylinder, open during the intake stroke for the third cylinder,
It can be seen that there is a large difference in the intake conditions between the W and 2 cylinders, which are closed during the exhaust stroke, and the To9 and 3 cylinders. Among these, the 3rd cylinder fuel injection timing Kec inlet valve is connected, so even if the intake valve is open, the intake action will be performed to inject fuel when the piston of the 3rd cylinder descends to near the bottom dead center. Since the intake conditions have weakened, the intake conditions can approach those of the other two cylinders.

Therefore, in the present invention, fuel is injected when the ignition point of the first cylinder is closed.

FIG. 3 is a circuit diagram showing an embodiment of a circuit for detecting the point closing point of the first cylinder and controlling injection, and FIG. 4 is a waveform diagram for explaining the operation.

The set input terminal of the set-reset flip-flop 1 (hereinafter referred to as FFI) is connected to the ignition signal of the first cylinder (FIG. 4(C)), and the reset input terminal is connected to the ignition signal of the third cylinder (FIG. 4).
Figure (E) is connected.

Therefore, an output appears at the output terminal of the FFI from the time of ignition of the first cylinder to the time of ignition of the 113th cylinder.

This output and the pulse that appears at the point of point closure (Fig. 4 (B)
)) Connected to Fi and gate 2, the first cylinder,
The point at which the point closes is detected (Fig. 14 (G)). This signal causes the solenoid valve 3 to operate, and the injector 4 injects fuel into the intake pipe.

The inventors of the present invention conducted an experiment on the concentration of unburned hydrocarbons (HC) in the exhaust gas of the third cylinder and the state of combustion by injection at the point open signal and injection at the point open signal according to the present invention. In the case of injection with an open signal, the He concentration is as low as in the case of using a vaporizer, and the combustion state is stable. However, in the case of injection with a point open signal, the He concentration is about twice that of the case with a close signal. The combustion condition was also unstable.

As explained above, according to the present invention, since the injection is performed by the closing signal of the ignition point of the first cylinder, the intake conditions of the third cylinder are close to those of the other 22 cylinders, and the combustion balance among the three cylinders is good. As a result, a smooth rotation state can be obtained. Furthermore, there is no increase in the air-fuel ratio of the third cylinder, making it possible to suppress the He concentration in the exhaust gas.

Various modifications can be made to the embodiments described in detail above within the scope of the present invention. For example, it is also possible to divide the frequency by three using a pulse frequency divider that occurs at the time of closing, and extract only the pulse of the first cylinder.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the ignition signal and the fuel injection timing, and shows the relationship between the ignition signal and the fuel injection timing. The case of a 3-cylinder engine is shown. Fig. 2 is a diagram showing each stroke and injection timing of a three-cylinder engine, Fig. 3 is a circuit diagram showing an example of a circuit that detects the point closing point of the first cylinder and performs injection control, and Fig. 4 shows the operation. FIG. 2 is a waveform diagram for explaining. 1...Set-reset flip-flop 2...
...And gate 3... Solenoid valve T...
...Top dead center B...Bottom dead center Patent applicant Suzuki Motor Co., Ltd. Agent Patent attorney Hisashi Inoro 71 (A') ,,, □57　12- -11 (B) V5 parallel machine-12--]---- Sai2 leap

Claims (2)

[Claims] (1) In a three-cylinder engine in which the first, third, and second cylinders are ignited in this order during two revolutions of the engine, the point corresponding to the ignition point in the first cylinder that opens and closes in synchronization with the engine rotation. A fuel injection control device characterized in that it is configured to detect a closing point and inject fuel once during two rotations of an engine. (2) At the time of the fuel injection, the above! 2. The fuel injection control device according to item 1, wherein the J1 cylinder is in a combustion stroke, the third cylinder is in a compression stroke, and the second cylinder is in an exhaust stroke.