JPH0486363A - Internal combustion engine - Google Patents

Abstract

PURPOSE:To strengthen the turning flow in a cylinder in the case of refluxing a large quantity of exhaust gas and sufficiently mix the exhaust gas to obtain satisfactory combustion by reducing the opening of an intake control valve as the opening of an exhaust gas recirculation control valve is increased. CONSTITUTION:Two intake ports, or a straight port 1 and a helical port 2 are connected to each cylinder, and these ports are connected to an intake manifold 4 through a valve body 3. When a large quantity of exhaust gas is refluxed at the time of low load operation (the opening of an EGR control valve 18 is large), an intake control valve 10 is closed. Thus, a new air and the exhaust gas are entered into a combustion chamber 11 only from the helical port 2 to generate a strong turning flow in the combustion chamber 11. At the time of high load operation, the EGR control valve 18 is closed as EGR is not required. As a large quantity of new air is required at this time, the intake control valve 10 is full opened to enter the new air from the straight port 1 and the helical port 2 into the combustion chamber 11.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to internal combustion engines.

[Conventional technology]

In Jika@52-135920, a throttle valve is provided in a single intake passage, and an exhaust gas recirculation (hereinafter referred to as rBGRJ) passage is connected to the intake passage where this throttle valve is located. An internal combustion engine is disclosed in which the opening degree of an intake passage is increased in accordance with an increase in load, and the opening degree of an EGR passage is also controlled.

[Problem to be solved by the invention]

However, in this internal combustion engine, the exhaust gas recirculated through the EGR passage and fresh air are insufficiently mixed, so
There is a problem in that when a large amount of exhaust gas is recirculated into the intake passage, combustion becomes unstable.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a first intake passage for generating a swirling flow in the cylinder, and a swirling flow that is stronger than the swirling flow generated by the first intake passage and has an opposite direction. A second intake passage for generating a swirling flow in the cylinder is connected to a single cylinder, and the first intake passage is provided with an intake control valve for controlling the opening degree of the first intake passage. , an exhaust gas recirculation passage is connected to the second intake passage, and the exhaust gas recirculation passage is provided with an exhaust gas recirculation control valve for controlling the opening degree of the exhaust gas recirculation passage. As the opening degree of the control valve increases, the opening degree of the intake control valve is decreased.

[For production]

As the opening degree of the exhaust gas recirculation control valve increases, the opening degree of the intake control valve is decreased. A large amount of exhaust gas is recirculated to the second intake passage in accordance with an increase in the opening degree of the exhaust gas recirculation control valve. On the other hand, as the opening degree of the intake control valve decreases, the amount of air flowing into the cylinder from the first intake passage decreases.
The swirling flow inside the cylinder caused by the intake passage is strengthened.

〔Example〕

FIG. 1 shows a schematic plan view of a direct injection internal combustion engine. 1st
Referring to the figure, two intake ports are connected to each cylinder, 1 being a straight port and 2 being a helical port. The straight port 1 and the helical port 2 are connected to an intake manifold 4 via a valve body 3. A heat insulating gasket 5.6 is arranged between the straight port 1 and the helical port 2 and the valve body 3 and between the intake manifold 4 and the valve body 3. The inside of the valve body 3 is partitioned by a partition wall 7 into a straight port connection part 8 and a helical port connection part 9. An intake control valve 10 is disposed within the straight port connection portion 8, and this intake control valve 10 controls the opening degree of the straight port 1. Intake control valve 1
When the valve 0 is closed, fresh air flows into the combustion chamber 11 only through the helical port 2, so that a strong swirling flow similar to that shown in FIG. 1 is generated in the combustion chamber 11. On the other hand, when the intake control valve 10 is opened, the straight port 1
Since air also flows in from the helical port 2, a counterclockwise swirling flow is generated in the combustion chamber 11, and the clockwise swirling flow generated by the flow from the helical port 2 is weakened.

As for the swirling flow generated in the combustion chamber 11, the clockwise swirling flow generated by the flow from the helical port 2 is stronger than the counterclockwise swirling flow generated by the flow from the straight port 1, and the intake control valve 10 is fully opened. The clockwise swirl flow is at its weakest when . By controlling the opening degree of the intake control valve 100 in this manner, the strength of the swirling flow within the combustion chamber 11 can be controlled.

FIG. 2 shows a sectional view of the internal combustion engine of FIG.

Referring to FIG. 2, 12 is a cylinder block, 13 is a piston, and 14 is a cylinder head. Combustion chamber 1
1 is defined within the cylinder block 12 by the top surface of the piston 13 and the bottom surface of the cylinder head 14.

A fuel injection valve 15 for injecting fuel into the combustion chamber 11 is arranged in the cylinder head 14 . straight port 1
A common EGR surge tank 16 for each cylinder is arranged below the helical port 2 (see Figure 1).
. The EGR surge tank 16 is formed integrally with the valve body 3, and the EGR surge tank 16 is connected to the lower surface of the helical connection portion 9 via a connection pipe 17. An EGR control valve 18 is disposed within the connecting pipe 17, and the EGR control valve 18
controls the opening degree of the connecting pipe 17. Therefore, by controlling the opening degree of the EGR control valve 18, the amount of recirculation of exhaust gas can be controlled. The EGR surge tank 16 is connected to an exhaust passage (not shown), and the entire outer surface of the EGR surge tank 16 is covered with a heat insulating material 19.

FIG. 3 shows a control unit for controlling the intake control valve 10 and the EGR control well 18. Referring to FIG. 3, the electronic control unit 30 consists of a digital computer with RO
It includes a read-only memory (M) 32, a random access memory (RAM) 33, a microprocessor (CPU) 34, an input port 35, and an output port 36. The accelerator opening sensor 20 outputs a detection signal according to the accelerator opening A, and the detection signal is sent to the A/D converter 3.
7 to the input port 35. Engine speed N
The output pulse of the rotation speed sensor 21, which generates an output pulse proportional to e, is input to the input boat 35. On the other hand, the output port 36 is connected to the intake control valve 10 and the EGR control valve 18 through corresponding drive circuits 38 and 39, respectively.

When a large amount of exhaust gas is recirculated during low-load operation (when the opening degree of the BGR control well 18 is large), the intake control valve 10 is closed. As a result, fresh air and exhaust gas flow into the combustion chamber 11 only from the helical port 2, and a strong swirling flow is generated within the combustion chamber 11.

Therefore, the exhaust gas mixes well with fresh air to form an air-fuel mixture that facilitates flame propagation. Further, the EGR surge tank 16 and the like are insulated by a heat insulating material 19, so that high-temperature exhaust gas can be circulated into the combustion chamber 11. This reduction increases the temperature of the entire mixture and reduces flame propagation.
7), thereby increasing H
The amount of C generated can be reduced. In this way, stable and good combustion can be obtained. Furthermore, since a large amount of exhaust gas is recirculated, the amount of NOx generated can also be reduced.

On the other hand, during high-load operation, EGR is not necessary;
The R control valve 18 is closed. At this time, since a large amount of fresh air is required, the intake control valve 10 is fully opened and fresh air flows into the combustion chamber 11 from the straight port 1 and the helical port 2. This allows high output to be obtained. When the intake control valve 10 is fully opened, the Calport 2
The swirling flow generated by the flow of fresh air from the straight port 1 is weakened by the swirling flow generated by the flow of fresh air from the straight port 1, and as a result, the swirling flow within the combustion chamber 11 becomes the weakest.

This can prevent the flame from blowing out due to the generation of an unnecessarily strong swirl.

As described above, in this embodiment, the amount of recirculation of exhaust gas is controlled by the EGR control well 18, and the intake control valve 10 is controlled according to the amount of recirculation of exhaust gas so as to create a swirling flow of optimal strength. . That is, as the opening degree of the EGR control well 18 is increased to increase the recirculation amount of exhaust gas, the opening degree of the intake control valve 10 is decreased to increase the strength of the swirling flow.

Figure 4 shows EGR in relation to engine speed and engine load.
rate and swirl ratio. The EGR rate is the ratio of the exhaust gas amount to the total inflow gas amount, and the swirl ratio indicates that the larger the swirl ratio, the stronger the swirling flow. E
Both the GR rate and the swirl ratio become smaller as the engine speed becomes higher or as the engine load becomes higher.

According to this embodiment, the BG at the downstream of the intake manifold 4
Because the R intake or connection pipe 17 is connected to the helical port 2 and because it is insulated by the insulating gasket 5.6, the intake manifold 4 is hardly heated even when a large amount of exhaust gas is recirculated. . Therefore, it is possible to prevent fresh air from being heated by the intake manifold 4 and becoming difficult to enter into the combustion chamber 11.

Also, E which controls the amount of exhaust gas flowing into the combustion chamber 11
Since the GR control valve 18 is located close to the combustion chamber 11, that is, in the vicinity immediately upstream of the helical port 2, the EGR control valve Combustion chamber 1 by 18
The responsiveness of controlling the amount of exhaust gas flowing into the exhaust gas can be improved.

Furthermore, since exhaust gas is supplied to each cylinder via the EGR surge tank 16 common to each cylinder, variations in exhaust gas distribution to each cylinder can be reduced.

Furthermore, since the EGR surge tank 16 is mounted immediately upstream of the helical port 2, it is easy to mount it on the engine.

FIG. 5 shows a routine for controlling the opening degree of the EGR control well 18. Referring to FIG. 5, first step 50
The engine speed Ne and the fuel injection amount Q are read in. In the case of a direct injection internal combustion engine, combustion is possible without controlling the air-fuel mixture to the stoichiometric air-fuel ratio, so the engine is basically operated with excess air in order to reduce intake throttling loss. Therefore, the output of the direct injection internal combustion engine is controlled by the fuel injection amount Q, and in this embodiment, the fuel injection amount Q is used as the load. The fuel injection amount Q is determined based on the engine speed Ne and the accelerator opening A using the map shown in FIG. 10 in a fuel injection amount control routine (not shown). Next, in step 51, the opening degree of the EGR control valve 18 is determined based on a map of the engine speed Ne and the engine load Q (
(see Figure 6). Then step 5
2, the EGR control valve 1 calculated in step 51
The EGR control valve 18 is driven based on the opening degree of 8.

FIG. 7 shows a routine for controlling the opening degree of the intake control valve 10. Referring to FIG. 7, first, in step 60, the engine speed Ne and the fuel injection amount Q are read. Next, in step 61, the opening degree of the intake control valve 10 is determined by a map of the engine speed Ne and the engine load Q (see FIG. 8).
Calculated based on.

When the EGR valve 18 and the intake control valve 10 are controlled based on the maps shown in FIGS. 6 and 8, the EGR rate and swirl ratio are controlled as shown in FIG. 4. Next, in step 62, the intake control valve 10 is driven based on the opening degree of the intake control valve 10 calculated in step 61. In other words, when the engine load is constant, when the engine speed increases, the swirl ratio decreases as the EGR rate decreases, and when the engine speed is constant, when the engine load increases, the EGR rate decreases.
EGR so that the swirl ratio decreases as the R rate decreases.
The rate and swirl ratio are controlled in conjunction.

FIG. 9 shows an example in which the present invention is applied to a V-type engine.

Referring to FIG. 9, an EGR surge connector 16 common to each cylinder is arranged in a V-shaped space formed between the right cylinder bank RB and the left cylinder bank LB. A valve body 3 is provided at each end of the EGR surge tank 16, and an intake control valve 10 and an EGR control valve 18 are provided in the valve body 3, respectively. As described above, according to this embodiment, the EGR surge tank 16 can be mounted using the V-shaped space, so that the ease of mounting on the engine can be further improved.

Above, an embodiment has been described in which the EGR rate and swirl ratio are controlled in relation to each other by the EGR control valve and the intake control valve. However, if necessary, a throttle valve may be provided upstream of the intake manifold to control the amount of intake air by the throttle valve. The EGR rate may also be controlled in addition.

〔Effect of the invention〕

When a large amount of exhaust gas is recirculated, the swirling flow within the cylinder is strengthened, so that the exhaust gases are sufficiently mixed and good combustion can be achieved.

[Brief explanation of drawings]

Figure 1 is a schematic plan view of the internal combustion engine, and Figure 2 is from ■-■ in Figure 1.
A cross-sectional view taken along the line, Fig. 3 is a diagram showing the control unit, Fig. 4 is a diagram showing the EGR rate and swirl ratio, and Fig. 5 is a diagram showing the EGR rate and swirl ratio.
The figure is a flowchart for controlling the opening degree of the EGR control valve, Figure 6 is a line diagram showing the opening degree of the EGR control valve, Figure 7 is a flowchart for controlling the opening degree of the intake control valve, and Figure 8 is a flowchart for controlling the opening degree of the intake control valve. 9 is a diagram showing the opening of the intake control valve, FIG. 9 is a sectional view of a V-type engine to which the present invention is applied, and FIG. 10 is a diagram showing the relationship between the accelerator opening, the engine speed, and the fuel injection amount. be. 1... Straight boat, 2... Helical port, 10... Intake control valve, 1
8...EGR control valve.

Claims (1)

[Claims] a first intake passage for generating a swirling flow in the cylinder;
A second intake passage is connected to a single cylinder to generate a swirling flow in the cylinder that is stronger than the swirling flow generated by the first intake passage and is in the opposite direction. The intake passage is provided with an intake control valve for controlling the opening degree of the first intake passage, and the second intake passage is connected to an exhaust gas recirculation passage. An exhaust gas recirculation control valve is provided for controlling the opening degree of the exhaust gas recirculation passage, and as the opening degree of the exhaust gas recirculation control valve increases, the opening degree of the intake control valve is decreased. institution.