JPS5941630A - Spark-ignited internal-combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spark-ignition internal combustion engine, and more particularly to a spark-ignition internal combustion engine that injects fuel into the intake passage of each cylinder.

Conventionally, in a 4-cylinder or 6-cylinder engine, fuel was injected from the injection nozzle into the intake passage of each cylinder at the same time in synchronization with the ignition timing of a specific cylinder, but the period from the injection timing to the intake stroke in each cylinder Since there is a difference in the injected fuel, there is a difference in the residence time of the injected fuel in the intake passage, and the properties of the air-fuel mixture taken into the combustion chamber are different. In particular, this difference in air-fuel mixture properties becomes noticeable during lean combustion, resulting in different combustion conditions for each cylinder, which poses a problem of deteriorating engine stability and fuel efficiency.

Therefore, in recent years, “Nissan FJ20 engine 1982
As described in the 2015 Maintenance Manual (published by Nissan Motor Co., Ltd.), so-called sequential injection is performed, in which the injection timing is set independently for each cylinder.

As shown in FIG. 1, this sequential injection is performed by a control unit 3 based on signals from an air flow meter 1, a crank angle sensor 2 with a built-in distributor, etc.
calculates the fuel injection amount and injection timing for each cylinder, and the control unit 3 controls the injection nozzle 4 installed in each cylinder.
The fuel is injected into the intake passage 5 based on the injection signal from the inlet. That is, the control unit 3 determines the cylinder based on the cylinder detection signal (180° signal) from the crank angle sensor 2, and detects the crank angle signal (180° signal) from the crank angle sensor 2.
The injection timing is calculated based on the 1° signal) and an injection pulse signal is output for each cylinder at a position 10° after the bottom dead center of the exhaust stroke.

The pulse width of this injection pulse signal determines the injection amount, but
This pulse width is determined by the control unit 3 calculating the most suitable injection amount for the engine condition based on the intake air amount signal from the airflow meter 1 and the engine rotation speed signal (1 degree signal) from the crank angle sensor 2. be done.

As shown in Fig. 2, the injection pulse signal calculated in this way is output to the injection nozzle 4 installed in each cylinder, and the intake pulse signal is output to the injection nozzle 4 installed in each cylinder, and the intake pulse signal is Fuel is injected into the channel 5 from the injection nozzle 4. In this way, by performing sequential injection, the air-fuel mixture properties in each cylinder are made uniform, thereby improving engine stability and fuel efficiency.

However, in such conventional spark-ignition internal combustion engines, sequential injection was performed in which fuel was injected into the intake passage at a position 10° after the bottom dead center of the exhaust stroke for each cylinder, so the inside of the intake pipe was The residence time of the injected fuel becomes longer and the air-fuel mixture sucked into the combustion chamber is dispersed uniformly within the combustion chamber, making it impossible to stratify the air-fuel mixture around the spark plug. Therefore, there is a problem in that it becomes difficult to ensure the stability of ignition and initial combustion, especially when performing lean combustion.

This invention was made by focusing on these conventional problems, and in a spark ignition internal combustion engine, the upstream side of the throttle valve in the intake path and the vicinity of the intake valve on the downstream side are connected for each cylinder. A control valve that forms a communicating sub-intake passage, directs the downstream opening of the sub-intake passage toward the combustion chamber G approximately parallel to the intake valve umbrella, and changes the cross-sectional area of the sub-intake passage in accordance with the operating state. It is an object of the present invention to solve the above-mentioned problems by providing a fuel injection nozzle for each cylinder and injecting fuel near the bottom dead center of the intake stroke for each cylinder.

The present invention will be explained below based on the drawings.

Figure 3.4 is a diagram showing an embodiment of these inventions.

First, to explain the structure, numeral 11 is a cylinder block in which a cylinder hole 12 is formed, and a piston 13 is slidably inserted into the cylinder hole 12. A cylinder head 14 is fixed to the upper end of the cylinder block 11, and the cylinder block 11, piston 13, and cylinder head 14 define a combustion chamber 15. The cylinder head 14 has an exhaust passage 17 that communicates with the combustion chamber 15 via an exhaust valve 16, and an exhaust passage 17 that communicates with the combustion chamber 15 via an intake valve 16.
An intake passage 19 communicating with the combustion chamber 15 is formed, and a spark plug 20 (see FIG. 4) is installed so as to protrude substantially into the center of the combustion chamber 15. In addition, the cylinder head 14
An intake pipe 22 in which an intake passage 21 communicating with the intake passage 19 is formed is fixed to the intake passage 19, and a throttle valve 23 is installed within the intake passage 21.

A sub-intake passage 24 is formed in the cylinder head I4 and the intake pipe 22, which communicates the upstream side of the throttle valve 23 with the vicinity of the intake valve 18 on the downstream side. As shown by the middle arrow, the intake valve 18
When the engine is lifted, the intake air from the sub-intake passage 24 reaches the intake valve 18.
It is oriented so as to penetrate between the umbrella portion and the valve seat portion of the cylinder head 14 to form a horizontal swirl within the combustion chamber 15 . That is, the downstream opening of the sub-intake passage 24 is oriented toward the combustion chamber 15 substantially parallel to the umbrella portion of the intake valve 18 . Further, the sub-intake passage 24 is provided with a control valve 25, and the control valve 25 controls the sub-intake passage 24 depending on the operating state.
The intake air amount is controlled by changing the cross-sectional area of 4. That is, the control valve δ is the valve 2 fixed to the diaphragm 26.
7 is a diaphragm spring 2 compressed inside the negative pressure chamber side.
9 and the negative pressure introduced into the negative chamber 28, the sub-intake passage 24 is moved to change the passage cross-sectional area of the sub-intake passage 24. The negative pressure in the negative pressure chamber 28 is created by a negative pressure control solenoid valve (hereinafter referred to as a VCM valve) 30. VCM valve 30
consists of a constant pressure valve part 31 and a solenoid valve part 32,
A negative pressure chamber 34 is defined in the constant pressure valve section 31 by a diaphragm 33 . A throttle valve 23 is provided in the negative pressure chamber 34.
Negative pressure from the intake path 2I on the downstream side is introduced, and the negative pressure chamber 3
When the negative pressure in the chamber 4 reaches a predetermined negative pressure (for example, -120 mmHg) or less, the section A closes and the negative pressure chamber 34 is maintained at a constant negative pressure. The solenoid valve 32 is provided with a solenoid valve 36 that is activated by a signal from the control unit 35, and when an OFF signal is manually input from the control unit 35, part B is closed and the negative pressure passage 37
The negative pressure in the negative pressure chamber 34 is introduced to. When an ON signal is input from the control unit 35, section B is opened and the pressure in the intake passage 21 upstream of the throttle valve 23 is guided to the negative pressure passage 37. The negative pressure chamber 28 of the control valve 25 is connected to one side of the negative pressure passage 37, and an exhaust gas recirculation control valve (not shown) is connected to the other side of the negative pressure passage 37.

On the other hand, the intake pipe 22 has an intake passage 1 extending toward the intake valve 18.
An injection nozzle 38 for injecting fuel is attached in the inside of the fuel injection device 9 , and the injection nozzle 38 injects fuel in response to an injection pulse signal from the control unit 35 . The control unit 35 includes a water temperature sensor 39, an air flow meter 40, a throttle valve switch 41.02 and a sensor 4.
2. The driving state is determined based on the signals from the neutral switch 43 and the vehicle speed sensor 44, and the VCM valve 3 is
It outputs ON and OFF signals to 0, and also calculates the fuel injection amount and injection timing for each cylinder based on signals from the crank angle sensor 45 built into the distributor, and installs an injection pulse signal for each cylinder. Output to the injection nozzle 3B. Here, the water temperature sensor 39 is attached to an outlet portion of the water jacket, etc., and outputs a signal corresponding to the cooling water temperature. The air flow meter 40 detects the amount of intake air, and the throttle valve switch 41 detects when the throttle valve 23 is fully closed. 02 sensor 42 detects the oxygen concentration in exhaust gas, and neutral switch 43 detects the neutral position of the transmission.

Vehicle speed sensor 44 detects the traveling speed of the vehicle. Further, the crank angle sensor 45 includes a rotor plate 46 fixed to the rotor shaft of the distributor, and a detection sensor 47 made of a light emitting and light receiving diode arranged to sandwich the rotor plate 46. 46 has cylinder detection (180° signal)
slits (4 slits for 4 cylinders) 48 and slits (360 slits) for crank angle detection (1° signal)
49 is formed. Therefore, when the engine rotates, the rotor plate 46 rotates, light from the light emitting diode is intermittently projected onto the light receiving diode, and the detection sensor 47 outputs a pulse signal indicating a cylinder signal and a crank angle signal to the control unit 35. be done.

Next, the action will be explained.

First, the operation of the control valve 5 will be explained.

During low-speed operation, the control valve 25 acts to narrow down the cross-sectional area of the sub-intake passage U during low-load operation, and acts to increase the cross-sectional area during high-load operation. That is,
During low-speed operation, the throttle valve 23 is throttled, and the negative pressure in the intake passage 21 downstream of the throttle valve 23 is large. At this time, if the control unit 35 determines that it is in a low load operating state from the intake air amount signal from the air flow meter 40, the vehicle speed signal from the vehicle speed sensor 44, etc., the control unit 35 outputs an ON signal to the VCM valve 30. Throttle valve 23 to control valve 25
Negative pressure in the intake passage 21 on the downstream side is introduced. Therefore, the control valve 25 narrows the cross-sectional area of the sub-intake passage 24 and
Reduce the amount of air inhaled. At this time, as described above, since the throttle valve 23 is in the fully closed state, the intake air introduced into the combustion chamber 15 is the intake air introduced from the auxiliary intake passage 24 except for the intake air leaking from the throttle valve 23. Therefore, a strong horizontal swirl is formed in the combustion chamber 15 by the intake air introduced from the sub-intake passage 24. When the control unit 35 determines that the operation is transitioning to high load operation, the control unit 35 shortens the output time of the ON signal to the VCM valve 30 so that the control valve 25 narrows the cross-sectional area of the sub-intake passage 24. The amount of intake air is increased by decreasing the amount of air. When the load further increases, the control valve 25 fully opens the auxiliary intake passage 24, and when the amount of intake air is insufficient, the throttle valve 25
will be opened. Therefore, a strong horizontal swirl is formed in the combustion chamber 15 by the intake air from the sub-intake passage 24 . In this way, during low speed operation, the control valve 2
The cross-sectional area of the auxiliary intake passage 24 is changed according to the load size and the operating state), and the swirl ratio (intake swirl speed divided by the crankshaft rotation speed) is created in the intake air amount and combustion chamber 15. At the same time, a strong horizontal swirl is formed within the combustion chamber 5.

Also, during high speed operation, the throttle valve 23
Since the combustion chamber 15 is wide open, a large amount of intake air is introduced into the combustion chamber 15 from the intake passage 19, and a strong swirl is formed. Therefore, intake air from the sub-intake passage 24 is suppressed.

Next, fuel injection will be explained.

Here, a case of a 4-cylinder 4-cycle engine will be explained. When the engine rotates, the crank angle sensor 45
A cylinder detection signal and a crank angle signal are inputted to the control unit 35. As shown in the flowchart of FIG. 5, the control unit 35 first performs cylinder discrimination and stroke discrimination. In other words, the cylinder detection signal determines the specific timing of the first cylinder (such as compression top dead center).
It also determines the timing of other cylinders. Next, the injection timing (near the bottom dead center of the intake stroke) is determined based on the crank angle signal.

Furthermore, the injection period (injection amount) is determined based on the driving state of the vehicle, such as the engine speed obtained from the crank angle signal and the intake air amount signal from the air flow meter 40. Then, an injection pulse signal having a pulse width corresponding to this injection period is transmitted to the injection pulse signal installed in each cylinder at the injection timing indicated by point a in the stroke diagram of Fig. 6 (near the bottom dead center of the intake stroke). The fuel is output to the nozzle 3B, and the fuel is injected from the injection nozzle 3B so as to ride on the above-mentioned intake air. Near the bottom dead center of the intake stroke, which is the injection timing, the piston 13 is in its upward stroke, and the swirl in the combustion chamber 15 is generated in the horizontal direction without descending. In addition, the intake air from the sub-intake passage 24 is directed toward the combustion chamber 15 in a direction that generates a horizontal swirl.
Therefore, the injected fuel is diffused and mixed into the combustion chamber 15 and is largely dispersed in the upper part of the combustion chamber 15, resulting in so-called stratified combustion. Particularly during low-speed operation, the intake air is mainly from the auxiliary intake passage 24, so the amount of fuel uniformly diffused into the combustion chamber 15 by the intake air from the intake passages 19 and 21 is small, resulting in less efficient stratified combustion. will improve.

Therefore, ignition and initial combustion are stabilized, combustion efficiency can be improved, and fuel efficiency can be improved, and especially in lean burn engines, fuel efficiency can be further improved.

As described above, according to the present invention, there are provided an intake passage that communicates with the combustion chamber via an intake valve and is provided with a throttle valve, an injection nozzle that injects fuel into the intake passage, and an injection nozzle that is introduced into the combustion chamber. A spark ignition internal combustion engine is provided with a spark ignition internal combustion engine that ignites the air-fuel mixture. The downstream opening of the passage is directed toward the combustion chamber approximately parallel to the intake valve umbrella, and a control valve is provided that changes the cross-sectional area of the sub-intake passage depending on the operating condition, and the injection nozzle is arranged for each cylinder. Since the fuel is injected near the bottom dead center of the intake stroke, the swirl ratio and intake air amount can be adjusted according to the operating conditions, and a horizontal swirl can be formed in the combustion chamber. The fuel spray properties can be made uniform, and the fuel can be injected at a time when horizontal swirl is occurring in the combustion chamber. Therefore, it is possible to perform stratified combustion, stabilize ignition and initial combustion, improve combustion efficiency, and improve fuel efficiency. Particularly, it is possible to obtain the effect that fuel efficiency can be further improved in a lean burn operation region.

[Brief explanation of the drawing]

Fig. 1.2 is a diagram showing a conventional spark ignition internal combustion engine, Fig. 1 is a schematic diagram thereof, Fig. 2 is a diagram showing its injection pulse signal, and Figs. 3 to 6 are diagrams showing a spark ignition type internal combustion engine of the present invention. FIG. 3 is a schematic diagram of the internal combustion engine, FIG. 4 is a schematic diagram showing the arrangement of its main intake passage and auxiliary intake passage, and FIG. 5 is a flowchart showing the operation of its control unit. FIG. 6 is an explanatory diagram showing the injection timing in relation to the engine stroke. 15--1--combustion chamber, 18--11--intake valve, 19.21--1 intake path, 20--11-1 spark plug, 23--throttle valve, 24-11 1 sub-intake passage, 25-1 control valve, 5 38--1 injection nozzle. Patent Applicant Nissan Motor Co., Ltd. Representative Patent Attorney Arigagun Part 6

Claims (1)

[Claims] The engine includes an intake passage that communicates with the combustion chamber via an intake valve and is provided with a throttle valve, an injection nozzle that injects fuel into the intake passage, and a spark plug that ignites the air-fuel mixture introduced into the combustion chamber. In the spark-ignition internal combustion engine, a sub-intake passage is formed that communicates the upstream side of the throttle valve of the intake passage with the vicinity of the intake valve on the downstream side, and the downstream opening of the sub-intake passage is arranged approximately parallel to the intake valve umbrella. A control valve is provided that directs the sub-intake passage toward the combustion chamber and changes the cross-sectional area of the sub-intake passage depending on the operating condition, so that the injection nozzle injects fuel near the bottom dead center of the intake stroke for each cylinder. A spark-ignition internal combustion engine featuring: