JPS5828547A - Electronically controlled fuel injection equipment in multi-cylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent fuel from deterioration of its distribution and improve the performance by actuating fuel injection valves in each air cylinder in compliance with ignition sequence of each air cylinder, in an engine which has adopted an induced turbulence genrating system equipped with small diameter of jet ports in the air inlet port. CONSTITUTION:In a four-cylinder engine, air inlet throttle valves 40a-40d are respectively provided in air inlet paths 15a-15d to each air cylinder branched from a surge tank 14, small diameter of jet ports 44a-44d which have their opening into an air inlet port 24, and fuel injection valves 34a-34d are installed on the downstream side of the throttle valves 40a-40d. And, each fuel injection valve 34a-34d is actuated in compliance with the determined ignition sequence by means of an injection valve driving circuit 56. And said driving circuit 56 determines the injection rate by means of air flow rate signals from an air-flow meter 18 and ignition signals, and it is controlled by means of an electronic control unit 26 to give fuel injection commande signals as output.

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 systems for spark ignition internal combustion engines can be roughly divided into two types: a system using a carburetor and a system 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 solvent injection valve for each intake port of each cylinder, each injection valve injects the same amount of fuel. This equalizes the amount of fuel delivered to each combustion chamber, solving the fuel distribution problems inherent in carburetor systems and allowing the engine to run with a leaner combustion mixture. Allows you to drive I(C.

It is possible to reduce the generation of harmful unburned organisms such as CO. There are two types of operating methods for fuel injection valves: a continuous injection method in which fuel is continuously injected from the injector, and a pulse injection method in which fuel is injected intermittently. In the latter method, a single magnetic fuel injection valve is used that is opened and closed by a solenoid, and this solenoid is generally excited by injection commands in the form of pulses from an electronic control unit containing a microcomputer. . Such a method is called an electronically controlled fuel injection method (EFI), and the technology to which the present invention is directed also belongs to this. In conventional electronically controlled fuel injection systems, the fuel injection timing is set at the same time for all fuel injection valves, that is, the fuel is injected all at once (simultaneous injection system), and the number of injections depends on each engine operation. Once or twice per cycle.

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. It is designed to have a straight shape with low ventilation resistance. However, when the intake boat is shaped like this, sufficient turbulence is not generated in the 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. As a method of generating strong turbulence in the intake air-fuel mixture during low-speed, low-load operation, there is a method of forcibly generating a swirling flow in the combustion chamber by making the intake boat into a helical shape or using a shroud valve. However, these methods have the problem that the charging efficiency during high-speed, high-load operation decreases because the ventilation resistance to the intake air mixture increases. Therefore, in a carburetor type engine, an intake throttle valve of ji2 should be individually installed in each intake passage in each branch pipe of the intake manifold downstream of the main intake throttle valve, and the intake port of each cylinder should be installed near the intake valve. A small-diameter jet port with a gate opening is provided for each cylinder, and the jet ports are communicated with each other through a common communication pipe, so that when the cylinder is in the intake stroke during low-speed operation of the engine, other ports that are not in the intake stroke are Intake air is induced from the intake boat of the cylinder, and the air is jetted from the jet port to the intake boat of the cylinder in the intake stroke to generate strong turbulence in the combustion chamber, thereby improving End during low-speed operation. It is proposed to secure output during high-speed operation while doing so←
JP-A-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 port is located downstream of the main throttle valve of the carburetor, and a homogeneous air-fuel mixture is formed in the carburetor. Therefore, even if the air-fuel mixture is divided into each jet port, the fuel distribution between the cylinders will not deteriorate. However, when a 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, resulting in combustion caused by the induced turbulence. There was a problem in that the improvement effect was offset by the variation in air-fuel ratio between cylinders, resulting in an increase in engine torque variation.

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 enables the engine to operate with a leaner combustion mixture. The aim is to improve fuel efficiency and reduce harmful exhaust gas components.

According to the present invention, the deterioration in fuel distribution is caused by fuel injected simultaneously at a certain time and staying in the intake ports of each cylinder entering the cylinder 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. This proposal proposes a synchronous independent injection system in which the fuel injection valves are operated sequentially according to the ignition order.

Hereinafter, embodiments will be described with reference to the accompanying drawings.

Fig. 1 is a diagram showing the overall layout of an engine incorporating the electronically controlled fuel injection system of the present invention, and Fig. 2 is a diagram showing the I-1 of Fig. 1.
FIG. The figure shows a four-cylinder engine, and as is well known, a cylinder head 6 equipped with a valve train and intake and exhaust ports is mounted on a cylinder block 4 that has cylinder bores 21 to 2d. A combustion chamber 10 is formed between a piston 8 and a cylinder head 6 that reciprocate therein. An intake manifold 12 and a surge tank 14 are fixed to the side surface of the cylinder head 6 in this order.
The intake air consists of two branch pipes 15a to 15m, an air cleaner 16 for intake air, and an air 70 for measuring the intake air flow rate.
- It is led to the surge tank 14 through a slot JL'7'-22 with a meter 18 and a throttle valve 2o, and from there it passes through an intake manifold 12 and an intake port 24 formed in the cylinder head 6 into the combustion chamber. 10
It is designed to be inhaled. Reference numeral 26 denotes a well-known electronic control unit (ECU) with a built-in micro combinator, which receives the intake air amount signal from the air flow meter 1B, the intake temperature signal from the intake air temperature sensor 28 provided in the air flow meter, and the signal from the throttle position sensor 30. , a signal from the cooling water temperature sensor 32, a signal from an engine rotation speed sensor (not shown), etc. are inputted to calculate the fuel injection amount and output a fuel injection command signal. Each solvent injection valve 34 is supplied with fuel from a fuel pump (not shown) through a fuel hose 36 and a delivery pipe 3B.The fuel injection valve 34 is a known electromagnetic injection valve having a solenoid, and The fuel is injected toward the intake port 24 in response to an injection command signal from the intake port 24.

Each intake manifold branch pipe 15 has a droplet 2 intake throttle valve 40.
a to 40d are provided, which are linked by a common shaft 42. For example, eight shafts 42 are linked to an accelerator pedal (not shown), and rotate the second throttle valve 40 to open the branch pipe 1 during low-load operation of the engine.
The main air passage within 5 can be substantially blocked. On the other hand, in the cylinder head 6, small-diameter jet bows 44a to 44d are formed approximately parallel to the intake boat 24 for each cylinder. As is clear from the cross section shown in FIG. 2 and the dotted line in FIG. When air is injected from these jet ports 44, strong turbulent flow is generated within the furnace. Each jet port 4
4 communicate with each other through a longitudinally extending communication passage 48 (see FIG. 2) formed in the base 13 of the intake manifold 12. Because of such a groove bottom, when the engine enters the intake stroke when the second throttles 4P40a to 40d are fully closed during low-speed engine operation, the jet boat 44 of that cylinder has the communication passage 48 and Air-fuel mixture is induced from the intake boat of the other cylinder via the jet boat of the other cylinder that is not in the intake stroke, and is ejected from the jet port to the intake boat of the cylinder that is in the intake stroke. Therefore, strong turbulence occurs in the combustion chamber of that cylinder. This relationship is the same when the other cylinders sequentially enter their intake strokes. At the bottom of Figure 111, the reference number 50 indicates a distributor, and its rotating shaft has a type 1 ignition pulse generation rotor with eight protrusions and a cylinder discrimination rotor with one protrusion. , distributor 5
0 housing includes an ignition pulse detection sensor 52 and a cylinder discrimination sensor 5 at positions corresponding to each rotor Iζ.
4 is installed.

According to the present invention, each of the fuel injection valves 34a to 34d is operated sequentially according to the firing order by an injection valve drive circuit 56.6 FIG. 3 is a block diagram of an electronically controlled fuel injection system including this injection valve drive circuit 56. In the figure, the distributor 50
The ignition pulse detection sensor 52 (see FIG. 1) is connected to the electronic control unit 26 and one input terminal of the shift register 62 via a waveform shaper 582 and a flip 70 knob 60. On the other hand, Dis) IJ beater 50
The cylinder discrimination sensor 54 provided in the shift register 62 is connected to the other input terminal of the shift register 62 via another waveform shaper 64. The fuel injection command signal output section of the electronic control unit 26 and the output section of the shift register 62 are connected to an AND gate 66.
They are connected to input sections a to 66d, respectively. Each A
ND gates 66a-66d are connected to the bases of transistors 681-68d via resistors. The collectors of the transistors 681 to 68d are connected to the power supply via the solenoids 70a to 7(l) of each fuel injection valve, and the emitters are grounded. 7°C corresponds to the No. 2 cylinder, 7°C corresponds to the No. 3 cylinder, and 70dj'! corresponds to the No. 4 cylinder.

Next, the operation of this electronically controlled fuel injection system will be explained with reference to the following drawings. As the ignition pulse generating rotor of the distributor 5o rotates in conjunction with the crankshaft of the engine, the ignition pulse detection sensor 52 outputs an electrical signal. This electric signal is shaped by a waveform shaper 58 to obtain a pulse signal shown in IF5 diagram (a). This pulse signal is frequency-divided by 7 rip 70 lub 60 to obtain the pulse signal shown in FIG. 4(b), which is input to one terminal of the shift register 62. A signal from the cylinder discrimination sensor 54 is input as a shift pulse to the other terminal of the shift register. Therefore, the pulse signals in FIG. 4(b) are sequentially shifted to the right, and the shift register 62 outputs a corresponding pulse signal to each AND gate 66 in any one of FIG. 4(c) to (f). . On the other hand, as is well known, the electronic control unit 26 determines the injection amount based on the signal from the air meter 18 and the ignition signal, and outputs the fuel injection command signal shown in FIG. 4(g) to the AND gate 66. There is. Therefore, each AND gate 66a to 66d corresponds to the IF5 diagram (a) to (f
The signal @11 is output only when the pulse shown in ) and the pulse shown in (g) of the figure overlap. Triggered by this output signal, the collector and emitter of each transistor are brought into conduction, current flows through the solenoids 70a to 704 of the fuel injection valves, and fuel is injected. In Figure 3, there are 8 fuel injector solenoids corresponding to those in the AGL, 3rd, IF4, and 2nd cylinders from the top, and each cylinder is ignited in this order, so the fuel injection is also in the ignition order. Therefore, it will be done accordingly. This state will be clear from the injection timing chart in FIG. 85, which shows a comparison with the conventional method.

When the conventional electronically controlled fuel injection system is combined with the above-mentioned forced attraction turbulence generation method, the fuel circulates through the jet port and the communication passage, so the air-fuel ratio of each cylinder is II! There were fluctuations as shown in Figure 6(a).

The present invention sequentially operates the fuel injection valves of each cylinder according to the ignition order, so that when a cylinder is in its intake stroke, the conditions of the air-fuel mixture coming from the intake port of another cylinder through the jet port and the communication passage are as follows. The same conditions apply to the cylinders. Therefore, the air-fuel ratio of each cylinder becomes uniform as shown in FIG. 6(b), and torque fluctuations can be minimized during low-speed, low-load operation and during low-speed, high-load operation.

[Brief explanation of drawings]

Figure 1 is an overall layout of a four-cylinder engine equipped with an electronically controlled fuel injection system, Figure 2 is a sectional view taken along line 1-■ in Figure 1, and
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...I&fi manifold, 15...Intake manifold branch pipe, 20.・・Throttle valve, 24・
...Intake port, 26...Electronic control unit, 34.
・Fuel injection valve, 40...Second intake throttle valve, 44...Jet port, 48...Communication path, 56...Injection valve drive circuit, 60...7 lip 70 knob, 62...shift register , 66...AND gate, 68...transistor,
70...Fuel injection valve solenoid. Patent Issuer Toyota Motor Corporation Patent Application Agent Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Masayuki Yoshida Akira Yamaguchi Figure 4 (9) --r1-1 "1--F- --Ro u No. 51!i
0 Figure 6 Volume ilF Cylinder number

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 that opens into the intake port of each cylinder is provided for each cylinder near the intake valve. , the jet boats are communicated with each other through a common communication pipe, so that when the three cylinders are on the suction stroke when the engine is running at low speed, intake air is induced from the intake ports of other cylinders that are not on the suction stroke to complete the suction stroke. In an electronically controlled fuel injection device for a multi-cylinder internal combustion engine, the fuel injection valve of each cylinder is configured to inject intake air from the jet boat into the intake port of the cylinder located in the cylinder, and the fuel injection valve of each cylinder is configured to An electronically controlled fuel injection system for a multi-cylinder internal combustion engine, characterized in that the fuel injection system operates sequentially.