JPH0245027B2 - - Google Patents

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 in spark-ignition internal combustion engines is that one fuel injection valve is provided for each intake port of each cylinder, and each injection valve injects the same amount of fuel into each combustion chamber. This eliminates the fuel distribution problems inherent in carburetor systems, allowing the engine to run with a leaner combustion mixture. to
It is possible to reduce the generation of harmful unburned organisms such as HC and 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 system, an electromagnetic fuel injection valve is used which is opened and closed by a solenoid, which is energized by injection commands in the form of pulses from an electronic control unit, typically 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 and has a straight vent to maximize power output during high-load, high-speed operation. Designed to have a low resistance shape. 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 of 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 forcibly generate a swirling flow within the combustion chamber. However, these methods have a problem in 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, a second intake throttle valve is individually provided in each intake passage in each branch pipe of the intake manifold downstream of the main intake throttle valve, and a second intake throttle valve is individually provided in each intake passage in each branch pipe of the intake manifold, and a second intake throttle valve is installed in each intake port of each cylinder near the intake valve. Each cylinder is provided with a small-diameter jet port that opens into the cylinder, and the jet ports are communicated with each other through a common communication pipe, so that when a certain cylinder enters the intake stroke during low-speed operation of the engine, the jet port enters the intake stroke. Intake air is induced from the intake ports of other cylinders that are currently in the intake stroke, and the air is jetted from the jet ports to the intake ports of the cylinders that are in the intake stroke, thereby generating strong turbulence in the combustion chamber, thereby causing a strong turbulent flow during low-speed operation. It has been proposed to secure output during high-speed operation while improving combustion of the engine (Japanese Patent Laid-Open No. 55-25547). For convenience, this method will be abbreviated as the forcible attraction turbulence generation method hereinafter.

By the way, when applying the above forced 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. , 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 individual intake ports is combined with the above-mentioned forced turbulence generation method, the fuel distribution between the cylinders deteriorates and the induced turbulence There was a problem in that the combustion improvement effect was attenuated by the fluctuations in the air-fuel ratio between cylinders, resulting in increased 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 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 above deterioration in fuel distribution is caused by fuel that is injected simultaneously at a certain time and remains in the intake port of each cylinder, and when a certain cylinder enters the intake stroke, it circulates through the jet port and the communication pipe. 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, the amount of fuel sucked into the other cylinders that subsequently enter the intake stroke sequentially, and the present invention aims to prevent such a situation. , 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 port that opens into the intake port of each cylinder near the intake valve is provided for each cylinder. and the jet ports are communicated with each other through a common communication pipe, so that when a certain cylinder enters the intake stroke during low-speed operation of the engine with the second intake throttle valve substantially fully closed, the second intake throttle valve is substantially fully closed. Intake air is induced from the intake ports of other cylinders that are not in the intake stroke, and the intake air is jetted from the jet port to the intake ports of the cylinders that are in the intake stroke, and further, the second intake air in the intake ports of each cylinder is A fuel injection valve is provided for each cylinder so as to open between the throttle valve and the opening of the jet port, and the fuel injection valves of each cylinder are divided into two groups each having half the number of cylinders. The present invention proposes an electronically controlled fuel injection system for a multi-cylinder internal combustion engine, characterized in that a group of fuel injection valves is configured to operate at predetermined ignition timing intervals according to the ignition order.

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

FIG. 1 is a diagram showing the overall arrangement of an engine equipped with an electronically controlled fuel injection system according to the present invention, and FIG. 2 is a sectional view taken along the line taken from FIG. 1. The figure shows a four-cylinder engine, and as is well known, cylinder bore 2a
A cylinder head 6 equipped with a valve train and an intake/exhaust port is mounted on the cylinder block 4 forming the cylinder bore 2, and a cylinder head 6 is provided between the cylinder bore 2, the piston 8 that reciprocates therein, and the cylinder head 6. A combustion chamber 10 is formed. A surge tank 12 with an intake manifold is located on the side of the cylinder head 6.
is installed. 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 12 via an air cleaner 16, an air flow meter 18 for measuring the intake air flow rate, and a throttle body 22 equipped with a throttle valve 20, and from there is formed in the cylinder head 6 via an intake manifold 14. The air is sucked into the combustion chamber 10 through an intake port 24 which has been opened. 26 is a well-known electronic control unit (ECU) with a built-in microcomputer.
The intake air amount signal from the air flow meter 18, the intake temperature signal from the intake temperature sensor 28 provided on the air flow meter, the signal from the throttle position sensor 30 provided on the throttle body 22, the signal from the cooling water temperature sensor 32, and the engine. This is for inputting signals from a rotation sensor (not shown), etc., calculating the fuel injection amount, and outputting a fuel 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 connected to a fuel hose 36 and a delivery pipe 3 from a fuel pump (not shown).
Fuel is supplied via step 8. The fuel injection valve 34 is a known electromagnetic injection valve having a solenoid, and injects fuel toward the intake port 24 in response to an injection command signal from the electronic control unit 26.

Each intake manifold branch pipe 14 is provided with second intake throttle valves 40a to 40d, which are linked by a link mechanism 42. The link mechanism 42 is, for example, disclosed in Japanese Patent Application Laid-Open No. 55-75531.
The second throttle valve 4 is linked to the output shaft of a diaphragm device 46 which is controlled by a control valve 44 as disclosed in .
0 can be rotated to substantially block the main air passage within the branch pipe 14. On the other hand, small diameter jet ports 48a to 48d are formed in the cylinder head 6 approximately parallel to the intake port 24 for each cylinder. As is clear from the cross section shown in FIG. 2 and the dotted line in FIG. 1, these jet ports open near the terminal end of the intake port 24 in a direction substantially tangential to the periphery of the intake valve 50. When air is injected from these jet ports 48, strong turbulence is generated within the combustion chamber. As is clear from FIG. 2, each jet port 48 is connected to a surge tank 12 with an intake manifold.
A communication path 52 extending in the longitudinal direction formed at the bottom of the
are connected to each other by. With such a configuration, the second throttle valve 40 is closed during low-speed operation of the engine.
When a certain cylinder enters the intake stroke when a to 40d are fully closed, the jet port 4 of that cylinder
8, the air-fuel mixture is induced from the intake port of the other cylinder via the communication passage 52 and the jet port of the other cylinder that is not in the intake stroke, and is ejected from the jet port to the intake port of the cylinder that is in the intake stroke. It will be done. Therefore, strong turbulence occurs within the combustion chamber of that cylinder. This relationship holds true even when the other cylinders sequentially enter their intake strokes. At the bottom of FIG. 1, the reference number 56 indicates a distributor, and its rotating shaft has a star-shaped ignition pulse generation rotor with four protrusions and a cylinder discrimination rotor with one protrusion. On the other hand, the data distributor 5
An ignition pulse detection sensor 58 and a cylinder discrimination sensor 60 are installed in the housing 6 at positions corresponding to the respective rotors.

According to the present invention, each fuel injector 34a-34d is configured, for example, by combining odd-numbered cylinders and even-numbered cylinders into one group, and by combining four cylinders into two groups.
into two groups. That is, the fuel injection valve 34a of the first cylinder and the fuel injection valve 34d of the fourth cylinder counted from the front of the engine, that is, from the right side of FIG. The injection valves 34b and 34c are grouped. 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.

FIG. 3 is a block diagram of an electronically controlled fuel injection system including this injection valve drive circuit 62, in which the ignition pulse detection sensor 58 (see FIG. 1) of the distributor 56 is connected via a waveform shaper 64 and a flip-flop 66. It is connected to one input terminal of electronic control unit 26 and shift register 68. On the other hand, the cylinder discrimination sensor 60 provided in the distributor 56 is connected to the other input terminal of the shift register 68 via another waveform shaper 70. The fuel injection command signal output section of the electronic control unit 26 and the output section of the shift register 68 are
They are connected to the inputs of AND gates 72 and 72', respectively. Each AND gate 72, 72' is connected to the base of a transistor 74, 74' via a resistor. The collector of each transistor 74, 74' is connected to a power source via a solenoid 76a-76d of each fuel injection valve, and the emitter is grounded. Note that the solenoid 76a is connected to the No. 1 cylinder.
6b is for the second cylinder, 76c is for the third cylinder,
76d corresponds to the fuel injection valve of No. 4 cylinder.

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. 4a. This pulse signal is frequency-divided by a flip-flop 66 to obtain the pulse signal shown in FIG. 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 signal of FIG. 4b is sequentially shifted to the right, and the shift register 68 outputs the corresponding pulse signal of either FIG. 4c or d to each AND gate 72, 72'. On the other hand, the electronic control unit 26 controls the air flow meter 1 as is well known.
The injection amount is determined based on the signal from 8 and the ignition signal, and the fuel injection command signal shown in FIG. 4e is outputted to the AND gates 72 and 72'. Therefore, each AND gate 72, 72' is
A signal of "1" is output only when the pulse shown in FIG. 1 overlaps with the pulse shown in FIG. Triggered by this output signal, the collector and emitter of each transistor 74, 74' are brought into conduction, and current flows through solenoids 76a to 76d of the fuel injection valves of each group to inject fuel. When the transistor 74 is conductive, the injection valves 34 of the group, that is, the first and fourth cylinders
When the injectors a and 34d are activated and the transistor 74' is conductive, the injection valves 34b and 34c of the group, that is, the second and third cylinders are activated. This condition will be clear from the injection timing chart in FIG. 5, which is shown in comparison with the conventional method. Fifth
Figure a shows a conventional system in which fuel is injected to all cylinders at the same time at 360° intervals, but in the illustrated embodiment of the present invention, as shown in Figure 5b, The two groups are operated alternately at 180° intervals, and each fuel injection valve injects half of the fuel injection amount for one cycle at a rate of once per crankshaft revolution.
The fuel is injected separately.

When the above-mentioned forcibly induced turbulent flow generation method is combined with a conventional electronically controlled fuel injection system, the cylinder (fifth
cylinders where the intake stroke occurs within a period of approximately 180° from the start of fuel injection, such as those at crank angles of 180°, 540°, and 900° illustrated in Figure a), and cylinders in which fuel does not circulate (Fig. 5a). As shown in Fig. 6a, the air-fuel ratio with the cylinder whose intake stroke comes approximately 180° or more after the start of fuel injection fluctuated as shown in Figure 6a. . 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 from the air mixture flowing around through the communication pipe is reduced. The conditions are the same for all cylinders. Therefore, the air-fuel ratio of each cylinder is
As shown in comparison with FIG. b, the torque becomes uniform, and torque fluctuations can be minimized during low-load operation.

[Brief explanation of the drawing]

Figure 1 is an overall layout of a four-cylinder engine equipped with an electronically controlled fuel injection system, and Figure 2 is the same as in Figure 1.
Figure 3 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. be. 12...Surge tank with intake manifold, 1
4... Intake manifold branch pipe, 20... Throttle valve, 24... Intake port, 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...Flip-flop, 68...Shift register, 72...AND gate, 74...Transistor, 76...Injection valve solenoid.

Claims (1)

[Claims] 1. 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 port that opens into the intake port of each cylinder near the intake valve is provided for each cylinder. and the jet ports are communicated with each other through a common communication pipe, so that when a certain cylinder enters the intake stroke during low-speed operation of the engine with the second intake throttle valve substantially fully closed, the second intake throttle valve is substantially fully closed. Intake air is induced from the intake ports of other cylinders that are not in the intake stroke, and the intake air is jetted from the jet port to the intake ports of the cylinders that are in the intake stroke, and further, the second intake air in the intake ports of each cylinder is A fuel injection valve is provided for each cylinder so as to open between the throttle valve and the opening of the jet port, and the fuel injection valves of each cylinder are divided into two groups each having half the number of cylinders. An electronically controlled fuel injection system for a multi-cylinder internal combustion engine, characterized in that a group of fuel injection valves is configured to operate at predetermined ignition timing intervals according to the ignition order.