JPS5828548A - Electronically controlled fuel injector for multicylinder internal-conbustion engine - Google Patents

Abstract

PURPOSE:To keep appropriate the distribution of fuel to an engine in which a jet port of small diameter is provided in each intake port to cause turbulent flow by strong inducement, by dividing the cylinders of the engine into two groups and operating the fuel injection valves of each group in ignition order. CONSTITUTION:In a four-cylinder engine, intake throttle valves 40a-40d are provided in intake passages 14 ramified from a surge tank 12 to the cylinders, jet ports 44a-44d of small diameter are opened in intake ports 24 and fuel injection valves 34a-34d are installed downstream to the intake throttle valves. The injection valves 34a-34d are divided into two groups, one of which includes those 34a, 34d for the first and the fourth cylinders and the other of which includes those 34b, 34c for the second and the third cylinders. The injection valves 34a, 34d, 34b, 34c of the two groups are operated in prescribed ignition order by an electronic controller 26 and an injection valve drive circuit 62.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply technology for a spark-ignition internal combustion engine, and more particularly to an electronically controlled fuel injection system for a multi-cylinder internal combustion engine.

Fuel supply methods for spark ignition internal combustion engines can be roughly divided into two types: a method using a carburetor and a method using a fuel injection valve. The latter is a relatively recently developed technology that has been attracting attention in recent years from various viewpoints including exhaust gas countermeasures.

In other words, the main advantage of the fuel injection method for spark ignition internal combustion engines is that by providing one fuel injection valve for each intake boat in each cylinder, each injection valve injects the same amount of fuel. Uniform fuel delivery to each combustion chamber eliminates the fuel distribution problems inherent in carburetor systems, resulting in the engine running with a leaner combustion mixture. HC.

It is possible to reduce the generation of harmful unburned organisms such as CO. There are two types of operating methods for the Bonito injection valve: a continuous injection method in which fuel is continuously injected from the injection valve force 1, and a pulse injection method in which fuel is injected intermittently. The latter method uses an electromagnetic fuel injection valve that is opened and closed by a solenoid, which is typically energized by injection commands in the form of pulses from an electronic control unit containing a microcomputer. This system is called an electronically controlled fuel injection system (IF I), and the technology to which the present invention is directed also belongs to this system.In the conventional electronically controlled fuel injection system, the fuel injection timing is All fuel injection valves inject fuel at the same time (simultaneous injection method), and the number of injections is once or twice per each operating cycle of the engine.

On the other hand, in today's engines, whether fuel-injected or carburetor-based, the intake port profile is generally relatively large in diameter to maximize power output during high-load, high-speed operation. Designed to have a straight shape with low ventilation resistance. However, when the intake port is shaped like this, sufficient turbulence is not generated in the air-fuel mixture sucked into the combustion chamber during low-speed, low-load operation and low-speed, high-load operation, which increases the flame propagation speed. I can't. Methods for generating strong turbulence in the intake air-fuel mixture during low-speed, low-load operation include creating a helical intake port or using a shroud valve to forcefully generate a swirling flow in the combustion chamber. However, these methods have the problem of decreasing charging efficiency during high-speed, high-load operation due to increased ventilation resistance to the intake air mixture flow.Therefore, in carburetor type engines, the intake manifold is installed downstream of the main intake throttle valve. In addition to providing four second intake throttle valves in each intake passage in each branch pipe,
A small-diameter jet port that opens into the intake port of each cylinder near the intake valve is provided for each cylinder, and the jet boats are communicated with each other through a common communication pipe, so that the cylinders consisting of the intake valves are connected to each other during low-speed operation of the engine. When the stroke begins, intake air is induced from the intake ports of other cylinders that are not in the intake stroke, and air is jetted from the jet boat to the intake boats of the cylinders that are in the intake stroke, creating strong turbulence in the combustion chamber. ,
It has been proposed that this method improves combustion during low-speed operation while ensuring output during high-speed operation (Japanese Patent Laid-Open No. 55
-25547). For convenience, this method will be abbreviated as the tension-induced turbulent flow generation method hereinafter.

By the way, when applying the forcibly induced turbulence generation method to an engine with a conventional carburetor, the jet boat is located downstream of the main throttle valve of the carburetor, and a homogeneous air-fuel mixture is formed in the carburetor. , even if the air-fuel mixture is divided into each jet boat, the fuel distribution between the cylinders will not deteriorate. However, when the fuel injection method that simultaneously injects fuel into each branch pipe of the intake manifold or each intake boat is combined with the above-mentioned forced turbulence generation method, the fuel distribution between the cylinders deteriorates and the induced turbulence 6
There was a problem in that the combustion improvement effect caused by this was canceled out by the fluctuations in the air-fuel ratio between cylinders, resulting in an increase in engine torque fluctuations.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a fuel supply device that does not cause deterioration in fuel distribution even when an electronically controlled fuel injection system is combined with the above-mentioned forcibly induced turbulent flow generation method. This ensures output during high-speed, high-load operation, prevents torque fluctuations during low-speed, low-load operation, and low-speed, high-load operation, and allows the engine to be operated with a leaner 4B mixture. The purpose of this is to improve fuel efficiency and lower harmful exhaust gas components.

According to the present invention, the deterioration of fuel distribution is caused by fuel injected simultaneously at a certain time and staying in the intake ports of each cylinder flowing through the jet port and the communication pipe when the cylinder enters the intake stroke. This is based on the knowledge that this is due to the fact that the amount of fuel sucked into that cylinder gradually decreases as a result of the amount of fuel sucked into the other cylinders that subsequently enter the intake stroke, and the present invention aims to prevent such a situation. The fuel injection valves of each cylinder are divided into two groups, a group belonging to odd-numbered cylinders and a group belonging to even-numbered cylinders, and the fuel injection valves of each group are operated at predetermined ignition timing intervals according to the ignition order. We propose a group injection system.

Embodiments will now be described with reference to the accompanying drawings.

FIG. 1 is a diagram showing the overall layout of an engine equipped with the electronically controlled fuel injection system of the present invention, and FIG.
FIG. The figure shows a four-cylinder engine, and as is well known, a cylinder head 6 with a valve train and intake/exhaust ports is mounted on a cylinder block 4 that forms cylinder bores 2a to 2d. A combustion chamber 10 is formed between a piston 8 and a cylinder head 6 that reciprocate therein. A surge tank 12 with an intake manifold is attached to the side of the cylinder head 6, Q. This surge tank 12 is integrally equipped with four intake manifold branch pipes 14 extending from the main body toward each intake port.

Intake air is led to the surge tank 14 through an air cleaner 16, an air 70-meter 18 for measuring the intake air flow rate, and a throttle bore 22 equipped with a throttle valve 20. From there, it is introduced into the cylinder head 6 via the intake manifold 12. 26 is a well-known electronic control unit (ECU) with a built-in microcomputer.
), air 70 - intake air amount signal from meter 18, air 7
An intake temperature signal from the intake temperature sensor 28 provided on the 0-meter, a signal from the throttle body sensor 3o provided on the throttle body 22, a signal from the cooling water temperature sensor 32, and a signal from the engine rotation sensor (not shown). This is for inputting signals, etc. 7, calculating the amount of solvent injection, and outputting an injection command signal. Fuel injection valves 34a to 34d are installed in the intake manifold branch pipe 14 for each cylinder. Each fuel injection valve 34 is supplied with fuel from a fuel pump (not shown) via a fuel hose 36 and a delivery pipe 38. The fuel injection valve 34 is a well-known electromagnetic injection valve having a solenoid, and injects fuel toward the intake boat 24 in response to an injection command signal from the electronic control unit 26.

Each intake manifold branch pipe 14 has a second intake throttle valve 4.
0a to 40d are provided, and these link mechanisms 42#
It is now linked to this.

The link mechanism 42 is linked to the output shaft of a diaphragm device 46 controlled by a control valve 44 disclosed in, for example, Japanese Patent Application Laid-Open No. 55-75531. The main air passage in the branch pipe 14 can be substantially blocked by the cylinder head 6. On the other hand, small-diameter jet ports 48s to 48d are formed for each cylinder in the cylinder head 6, approximately parallel to the intake boat 24. There is.

As is clear from the cross section shown in FIG. 11E2 and the dotted line in FIG. When air is injected from these jet boats 48, strong turbulence is generated within the combustion chamber. As is clear from FIG. 2, each jet boat 48 is connected to a communication passage 52 extending in the longitudinal direction formed at the bottom of the surge tank 12 with an intake manifold.
are connected to each other. With this configuration, when the second throttle valves 40a to 40d are fully closed during low-speed operation of the engine and the cylinder consisting of the number 2 enters the intake stroke, the jet boat 48 of that cylinder is provided with a communication passage. 52 and the jet boats of other cylinders that are not in the intake stroke, the air-fuel mixture is induced from the intake boats of the other cylinders and is ejected from the jet boats to the intake boats of the cylinders that are in the intake stroke.

Therefore, strong turbulence occurs in the melting chamber gate of that cylinder. This relationship holds true even when the other cylinders sequentially enter their intake strokes. The distributor indicated by reference number 56 at the bottom of FIG. 1 has a star-shaped ignition pulse generation rotor with four protrusions and a cylinder discrimination rotor with one protrusion attached to its rotating shaft. dis) IJ
An ignition pulse detection sensor 582 and a cylinder discrimination sensor 60 are installed in the housing of the computer 56 at positions corresponding to the respective rotors.

According to the present invention, each of the fuel injection valves 34a to 34d is divided into two groups: a group belonging to odd-numbered cylinders and a group belonging to even-numbered cylinders.

That is, the fuel injection valve 34 & of the first cylinder counting from the front of the engine, that is, the right side of FIG. Fuel injection valve 34b.

Let 34@ be group I. These two groups of injection valves are operated by the injection valve drive circuit 62 at predetermined ignition timing intervals according to the ignition order.

Diagram 3 is a block diagram of the electronically controlled fuel injection system including this injection valve drive circuit 62.
The ignition pulse detection sensor 58 (see figure gI) is connected to the electronic control unit 26J6 and one input terminal of the shift register 68 via a waveform shaper 64 and a flip-flop 66.

On the other hand, the cylinder discrimination sensor 60 provided in the distributor 56 is connected to the shift register 68 via another waveform shaper 7o.
is connected to the other input terminal of

The fuel injection command signal output section of the electronic control unit 26 and the output section of the shift register 68 are an AND game) 72.72
' is connected to the input section of '. Each AND'7'-door 2.72' is connected to transistor 74.74' via a resistor.
connected to the base of. Each transistor 74.74
The collector of ' is the solenoid 76~76 of each fuel injector.
It is connected to the power supply via d, and its emitter is grounded. S, solenoid 76a is connected to the g1 cylinder, 76b is connected to the second cylinder, 76 is connected to the 3rd cylinder, and 76d is connected to the 4th cylinder.
# Corresponds to each cylinder's fuel injector.

Next, the operation of this electronically controlled fuel injection system will be explained with reference to the drawings from FIG. 4 onwards. As the ignition pulse generation rotor of the distributor 56 rotates in conjunction with the crankshaft of the engine, the ignition pulse detection sensor 58 outputs an electrical signal. This electrical signal is shaped by a waveform shaper 64 to obtain the pulse signal shown in FIG. 4(a). This pulse signal is 7
Divide the frequency by lip 70 and knob 66! 4. Obtain the pulse signal shown in FIG. 4(b) and input it to one terminal of the shift register 68. A signal from the cylinder discrimination sensor 60 is input as a shift pulse to the other terminal of the shift register. Therefore, the pulse signals in Figure 4(b) are sequentially shifted to the right, and the shift register 68 outputs a pulse signal corresponding to either Figure 4(e) or (d) to each AND gate 72, 72'. Output a signal. On the other hand, as is well known, the electronic control unit 26 determines the injection amount pipe based on the signal from the air 7 meter 18 and the ignition signal number, and directs the signal from the air 7 meter 18 to the ignition signal number and directs it to the The fuel injection command signal is output.

Therefore, each AND gate 72, 72' is [Fig. 4 (e
)', the signal 111 is output only when the pulses shown in (d) and the pulses shown in (•) in the figure overlap. Triggered by this output signal, the collectors and emitters of the transistors 4 and 74' are brought into conduction, and current flows through the solenoids 76a to 7614 of the fuel injection valves of each group to inject fuel.

When transistor 74 conducts, the group! That is, when the injection valves 34m and 34d of the III and 4 cylinders operate, and when the transistor 74' becomes conductive, the injection valves 34b and 34@ of the group I, that is, the 2nd and 3 cylinders, operate.This state is based on the conventional system. This will be clear from the injection timing chart in FIG. 5, which is shown in comparison with the case.

When the above-mentioned forcibly induced turbulent flow generation method is combined with the conventional electronically controlled fuel injection system, the fuel circulates through the jet boat and the communication passage, so the air-fuel ratio of each cylinder will be as shown in Figure 6 (turtle). There were fluctuations as shown.

In the present invention, the fuel injection valves of each cylinder are divided into two groups, and the fuel injection valves of each group are operated at predetermined ignition timing intervals according to the ignition order, so that the contribution of the air mixture flowing around through the communication pipe is to which cylinder. The same conditions apply. Therefore, the air-fuel ratio of each cylinder becomes uniform as shown in comparison with FIG. 6(b), and torque fluctuation can be minimized during low-load operation.

[Brief explanation of the drawing]

Figure 1 is an overall layout of a 4-cylinder engine equipped with an electronically controlled fuel injection system, Figure 2 is a sectional view taken along line l-■ in Figure 1, and Atsushi 3
Figure 4 is a block diagram of the injection valve drive circuit, Figure 4 is a waveform diagram showing changes in pulse signals over time, Figure 5 is an injection timing chart, and Figure 6 is a graph comparing air-fuel ratio fluctuations. 12...Surge tank with intake manifold, 14.
... Intake manifold branch pipe, 20... Throttle valve, 24... Intake boat, 26... Electronic control unit, 34... Fuel injection valve, 40... Second intake throttle valve, 48...・Jet port, 50...Intake valve, 52・
...Communication path, 62...Injection valve drive circuit, 66...7
Lip-flop, 68...Shift register, 72...
AND gate, 74...Transistor, 76...Injection valve solenoid, Patent applicant: Toyota Motor Corporation Patent agent, Patent attorney: Akira Aomizu, Patent attorney, Kazuyuki Nishidate, Patent attorney, Masayuki Yoshida, Patent attorney, Akiyuki Yamaguchi, 4th v ! J (e) Fig. 5 Ignition order - Ignition order - Fig. 6

Claims (1)

[Claims] A second intake throttle valve is provided in each intake passage downstream of the main intake throttle valve of a multi-cylinder internal combustion engine, and a small-diameter jet boat is provided for each cylinder near the intake throttle valve and opens into the intake boat of each cylinder. The jet ports are connected to each other through a common communication pipe, so that when the cylinder is in the intake stroke during low-speed operation of the engine, intake air is induced from the intake boats of other cylinders that are not in the intake stroke. In an electronically controlled fuel injection device for a multi-cylinder internal combustion engine, which is capable of injecting intake air from the jet port into the intake boat of the cylinder in the intake stroke, the fuel injection valve of each cylinder is connected to a group belonging to an odd-numbered cylinder. and a group belonging to even-numbered cylinders, and the fuel injection valves of each group are operated at predetermined ignition timing intervals according to the ignition order. Fuel injection device.