JPH0364625A - Suction device for multi-cylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To produce powerful suction swirling flow and the like by mutually communi cating the combustion chambers of respective cylinders wherein the expansion stroke and the suction stroke take place roughly at the same time, thereby applying combus tion gas at high pressure from the combustion chambers at the expansion stroke side to the combustion chambers at the suction stroke side. CONSTITUTION:The cylinder head 2 of a four cylinder diesel engine 1 is formed with helical type suction ports 4 which are communicated with the combustion chambers of respective cylinder #1 through #4. In this case, the respective combustion chambers 3 of No.1 and No.4 cylinder #1 and #4 are communicated with each other through No.1 communication passage 5. The respective combustion chambers of No.2 and No.3 cylinder #2 and #3 are also communicated with each other through No.2 communi cation passage 6. In addition, fuel is injected from No.1, No.3 No.4 and No.2 cylinder #1, #3, #4 and #2, in that order. When No.1 and No.2 cylinder #1 and #2 are in the expansion stroke respectively, No.4 and No.3 cylinder #4 and #3 are designed to be in the suction stroke respectively. By this constitution, powerful suction swirling flow can be produced with combustion gas put into use.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a technique for improving combustion performance in a multi-cylinder internal combustion engine by strengthening intake swirl flow and intake turbulence in a combustion chamber.

<Prior Art> Conventional examples of this type of intake flow control device include the following (see Japanese Patent Publication No. 57-12016 and Japanese Patent Application Laid-Open No. 60-30424).

That is, a convex portion or a concave portion is formed on the earthen wall or side wall of the helical intake port, thereby creating turbulence in the intake air and increasing the turbulence of the intake air within the combustion chamber.

Furthermore, as shown in Japanese Patent Publication No. 58-9248, by providing a throttle valve in the intake passage near the intake port, the intake air is diverted to one edge of the throttle valve, and the intake ports upstream of the intake valves of each cylinder are connected to each other. There is a system that connects the intake boats of the cylinders in the intake stroke to blow out intake air (mixture) from other cylinders, thereby strengthening the intake swirl flow.

<Problem to be solved by the invention> However, in such a conventional intake device,
The intake swirl flow and intake turbulence are generated by utilizing the intake flow energy and the direction of the intake flow as the piston descends, so the shape of the intake boat is changed to increase the intake swirl flow and intake turbulence. As a result, the intake air filling efficiency decreases, and there is a limit to the strength of the intake air turbulence that can be generated, resulting in the inability to generate strong intake air turbulence that can significantly improve combustion performance.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an intake system for a multi-cylinder internal combustion engine that can significantly increase intake swirl flow and intake turbulence.

<Means for Solving the Problems> For this reason, the present invention provides a communication path that communicates with each other the combustion chambers of cylinders whose expansion stroke and intake stroke are at substantially the same time.

<Operation> Then, high-pressure combustion gas is introduced into the combustion chamber of the cylinder in the intake stroke from the combustion chamber of the cylinder in the expansion stroke, so that the combustion gas generates a strong intake swirl flow and intake air turbulence in the intake air. I made it.

<Example> Embodiments of the present invention will be described below based on the drawings.

1 to 3 show a first embodiment of the present invention.

In the figure, a cylinder throat 2 of a four-cylinder diesel engine 1 is formed with a helical intake port 4 that communicates with the combustion chamber 3 of each cylinder, and these helical intake ports 4 communicate with an intake manifold (not shown) in a straight line. They are each formed of a shaped intake passage and a spiral portion that is connected downstream of the intake passage and communicates with the combustion chamber 3 via an intake valve.

Further, the combustion chamber 3 of the #l cylinder and the combustion chamber 3 of the #4 cylinder are communicated with each other by the first communication passage 5, and the combustion chamber 3 of the #2 cylinder and the combustion chamber 3 of the #4 cylinder are communicated with each other by the first communication passage 5.
A second communication passage 6 communicates with the combustion chamber 3 of the cylinder. The communication portions of the first and second communication passages 5.6 with the combustion chamber 3 are formed to be offset toward the intake port 4 side with respect to the center of the combustion chamber 3 and to face in the tangential direction of the combustion chamber 3. .

Here, the fuel injection order is #1-#3-#4-#2
When the #1 cylinder is in the expansion stroke (intake stroke), the #4 cylinder is in the intake stroke (expansion stroke), and the #4 cylinder is in the intake stroke (expansion stroke).
When the second cylinder is in the expansion stroke (intake stroke), the #3 cylinder is in the intake stroke (expansion stroke).

Note that 7 is a fuel injection nozzle, and 8 is an exhaust port.

According to this configuration, for example, when the #1 cylinder is in the expansion stroke, the #4 cylinder is in the intake stroke as shown in FIG. High-temperature, high-pressure combustion gas is ejected and supplied to 3 through the first communication passage 5. At this time, since the communication part of the first communication passage 5 with the combustion chamber 3 is offset toward the intake port 4 side with respect to the center of the combustion chamber 3 and is formed so as to face in the tangential direction of the combustion chamber 3, the intake port The swirling flow of the intake air A flowing in from 4 and swirling is greatly strengthened by the high-temperature, high-pressure combustion gas, and the turbulence of the intake air is also greatly strengthened. Conversely, when the #1 cylinder is in the intake stroke and the #4 cylinder is in the expansion stroke, combustion gas is introduced from the #4 cylinder to the #3 cylinder. Also,
The same applies to #2 cylinder and #3 cylinder.

By the way, in general, the higher the energy of the intake swirl flow and intake air turbulence obtained in the intake stroke, the higher the combustion rate will be, and this tendency is particularly noticeable in direct injection diesel engines that mix fuel and intake air in the combustion chamber. be.

Therefore, in this embodiment, the combustion period is shortened, and fuel efficiency and smoke emissions can be greatly improved. Furthermore, since the combustion gas is introduced into the combustion chamber 3 during the intake stroke, NOx can also be reduced due to the exhaust gas recirculation effect. Further, it is sufficient to simply provide the first and second communication passages 5 and 6, and the configuration is extremely simple.

In addition, in a cylinder that is in the expansion stroke, a portion of the combustion gas flows out to other cylinders, so a decrease in torque is expected, but this can be avoided by setting the cross-sectional area of the communication passage sufficiently small. Particularly during high-speed operation, torque reduction can be suppressed. Also, for example, when #4 cylinder is in the compression stroke, #1 cylinder
Since the cylinder is on the exhaust stroke, the compressed intake of cylinder #4 is the first
Although it flows into the #1 cylinder through the communication passage 5, the amount of this flow is small and does not affect the drivability of the engine, especially during high-speed operation.

In addition, when only intake turbulence is caused by combustion gas and the intake swirl flow is generated in the swirl part of the intake boat 4, the communication part of the first and second communication passages 5 and 6 with the combustion chamber 3 is connected to the intake port 4. There is no need to offset it to the side.

4 and 5 show a second embodiment of the invention.

Incidentally, the same elements as in the first embodiment are given the same reference numerals as in FIG. 1, and the explanation thereof will be omitted.

In this embodiment, the present invention is applied to a six-cylinder diesel engine, in which the combustion chamber 3 of the #1 cylinder and the combustion chamber 3 of the #6 cylinder are communicated with each other by a first communication passage 11, and the combustion chamber 3 of the #2 cylinder is communicated with the combustion chamber 3 of the #6 cylinder. The combustion chamber 3 of the #5 cylinder communicates with the combustion chamber 3 of the #5 cylinder through a second communication passage 12, and the combustion chamber 3 of the #3 cylinder communicates with the combustion chamber 5 of the #4 cylinder through a third communication passage 13.

Here, the fuel injection order is #1-#5-#3-#6-#2
- As shown in Fig. 5, the intake stroke and expansion stroke of cylinder #1 and cylinder #6 are set at approximately the same time, and the intake stroke and expansion stroke of cylinder #2 and #5 are set at approximately the same time. The expansion stroke is approximately at the same time, and the intake stroke and expansion stroke are approximately at the same time for the #3 and #4 cylinders.

This configuration also provides the same effects as the first embodiment.

FIG. 6 shows a modification of the same as above.

That is, an on-off valve 22 is provided to open and close a communication passage 21 that communicates with the combustion chamber of another cylinder, and the on-off valve 22 is closed by the biasing force of a spring 23 during engine startup or low-speed operation to open the communication passage 21. It is designed to form a closed circuit. This prevents compressed air in the compression stroke from flowing into the cylinder in the exhaust stroke and torque reduction due to combustion gas leakage during engine startup or low-speed operation.

In addition, during operations other than those described above, the actuator 24 opens the on-off valve 22 against the urging force of the spring 23, opens the communication passage 21, and strengthens the intake swirl flow and the turbulence of the intake flow.

<Effects of the Invention> As explained above, the present invention allows the combustion chambers of cylinders whose expansion stroke and intake stroke are at approximately the same time to communicate with each other through a communication passage, thereby reducing intake swirl flow, particularly intake turbulence. Since it can be greatly strengthened by combustion gas, it is possible to improve fuel efficiency, reduce smoke, and reduce NOx with an extremely simple configuration.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention, FIG. 2 is a view taken along the ff-ff arrow shown above, FIG. A configuration diagram showing a second embodiment,
FIG. 5 is a diagram for explaining the effect of the above, and FIG. 6 is a sectional view of a main part showing a modification of the same. 3... Combustion chamber 4... Intake port) 5.11
...First communication path 6.12...Second communication path 1
3...Second communication path

Claims (1)

[Claims] An intake system for a multi-cylinder internal combustion engine, characterized in that a communication passage is provided for communicating the combustion chambers of cylinders whose expansion stroke and intake stroke are at substantially the same time.