JPH06159203A - Air intake device of engine - Google Patents

Abstract

PURPOSE:To prevent combustion from being deteriorated due to fuel adhering to a partition at a low speed and low load by dividing an air intake port by a partition and generating tumble flow. CONSTITUTION:A partition 20 is formed inside air intake ports 11, 12 to divide them into upper and lower sides so that a tumble port 21 and a by-path port 22 is formed. An injector 23 is disposed on the inlet side of the tumble port 21, a tumble control valve 24 is disposed on the inlet side of the by-path port 22, and a final end part 20b of the partition 20 is cut aslant to form a triangle part. At a low speed and low load, air is taken from only the tumble port 21, and fuel is injected to the air to generate tumble flow by gas flow coming into a cylinder 3. Fuel adhering to the partition 20 by fuel injected from an injector 23 is escaped by the triangle part smoothly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for generating a tumble flow in a cylinder during intake in a four-cycle gasoline engine for a vehicle. More specifically, the intake port is divided by a partition wall to generate a tumble flow. In this method, the elimination of fuel adhering to the partition wall is performed.

[0002]

2. Description of the Related Art In the engine operating region, particularly at low speed and low load, the intake air amount is greatly reduced, resulting in poor combustion, which tends to deteriorate fuel efficiency, emission, and driving performance. Therefore, as a means for improving fuel consumption at low speed and low load, it is effective to generate turbulence in the combustion chamber at the time of ignition and combustion to promote combustion. Therefore, it has been proposed to generate a swirl flow that swirls around the axis in the cylinder during intake, or a tumble flow (vertical swirl) that swirls in the axial direction within the cylinder.

In the case of the swirl flow, it is effective to make the air-fuel mixture uniform, but the use of turbulent flow in the combustion chamber is low. In this respect, in the case of the tumble flow, a large swirling flow including the combustion chamber is always generated, and when the tumble collapses in the latter half of the compression stroke, it is greatly disturbed, and a strong turbulent flow can be generated in the combustion chamber. Expected to contribute directly to promotion. Therefore, it is desired to improve the intake system of the engine to effectively generate a tumble flow in the cylinder during intake at low speed and low load.

Conventionally, as for the intake system of the engine which generates the above-mentioned tumble flow, for example, Japanese Patent Laid-Open No. 230230/1990.
There is a prior art of Japanese Patent Publication. Here, since the intake port of the engine is bent and communicates at a substantially right angle to the axis of the cylinder, the airflow that passes through the upper part of the intake port is directed toward the exhaust port side from the center of the cylinder and introduced into the cylinder. Therefore, the tumble flow can be generated by this air flow. Therefore, a partition is provided inside the intake port to divide it into upper and lower parts, a tumble port in the upper part and a bypass port in the lower part. An injector is arranged on the side of the tumble port, and a tumble control valve is provided on the bypass port so that it can be opened and closed.

Therefore, at low speed and low load, the tumble control valve is closed to intake air only from the tumble port, and fuel is injected into the intake air of the tumble port by an injector to generate a mixture. Then, this mixture is guided by a partition wall and introduced to the exhaust port side, and this gas flow produces a tumble flow that swirls in the axial direction within the cylinder. Also, it is shown that the tumble control valve is opened and a large amount of air is sucked from both ports at the time of high speed and high load where combustion speed is originally high and there is no need to promote combustion.

[0006]

By the way, in the above-mentioned prior art, since the intake port itself of the engine is divided into upper and lower parts by the partition wall, the structure is simplified, and the intake port is improved at high speed and high load. Although there is an advantage that it is possible to prevent the flow coefficient from being lowered by fully opening, the fuel spray from the injector is likely to adhere to the partition wall because the tumble port is formed vertically flat. Then, the fuel spray adhered to the partition wall may grow into droplets as appropriate and intermittently flow into the fuel chamber to deteriorate combustion. This has a problem that it is remarkable in response during cold start or during transient.

The present invention has been made in view of this point, and in a system of dividing a suction port by a partition wall to generate a tumble flow, it is possible to prevent combustion deterioration due to fuel adhering to the partition wall at low speed and low load. To aim.

[0008]

To achieve the above object, the present invention provides a tumble port and a bypass port by dividing the intake port by providing a partition wall inside the intake port, and at the inlet side of the tumble port. An injector is installed, a tumble control valve is installed on the inlet side of the bypass port, and in the intake system that generates a tumble flow in the cylinder by the gas flow when only inhaling from the tumble port, the end of the partition wall is cut off diagonally. It is located immediately before the intake valve.

[0009]

Based on the above structure, the tumble control valve is closed, for example, at low speed and low load, and intake is made only from the tumble port,
By injecting fuel into this intake air by an injector, the air-fuel mixture flows into the cylinder via the exhaust port side of the combustion chamber, and this gas flow creates a tumble flow that swirls in the cylinder in the axial direction. . At this time, the fuel spray from the injector adheres to the partition wall and flows down to the end portion thereof, but by obliquely cutting off, the fuel droplets are smoothly released early and the deterioration of combustion does not occur. Also, when the tumble control valve opens at high speed and high load, air is taken in from the tumble port and the bypass port. In this case, the air from the two ports joins immediately before the intake valve and mixes well with the fuel that has accumulated in advance. Flow into the cylinder.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. A two intake valve type engine will be described with reference to FIGS. 1 and 2. Reference numeral 1 denotes an engine body, a piston 4 is reciprocally inserted into a cylinder 3 of a cylinder block 2, and a combustion chamber 6 is provided at the top of the cylinder 3 in a cylinder head 5. In addition, one intake passage 10
From the two intake ports 11 and 12 are bifurcated by a branch wall 13, and these two intake ports 11 and 12 are
Are communicated with one side of the combustion chamber 6, and each intake port 11, 12
Intake valves 14 and 15 are installed to be openable and closable, respectively.

Here, since the intake port is bent and communicated at a substantially right angle to the axis of the cylinder, the air flow passing through the upper part of the intake port is directed toward the exhaust port side from the center of the cylinder. Flows in. Therefore, a tumble flow can be generated in the cylinder by dividing the inside of the intake port by the partition wall and injecting fuel from only the upper part of the partition wall and injecting fuel. Further, considering the mixing with the fuel when inhaling the whole area above and below the partition wall at high speed and high load, it is necessary to connect the ports divided by the partition wall immediately before the intake valve.

Therefore, in the inside of the two intake ports 11 and 12, a plate-shaped partition wall 20 is horizontally installed in the region from the inlet to immediately before the intake valves 14 and 15. The partition wall 20 is shown in FIG.
As described above, the whole is curved along the shape of the port and is formed by bifurcating. The partition wall 20 divides the inside of the intake ports 11 and 12 into upper and lower parts, and a tumble port 21 is formed above the partition wall 20 and a bypass port 22 is formed below the partition wall 20. Further, the end portion 20b of the branch portion 20a of the partition wall 20 is located immediately before the intake valves 14 and 15, and both ports 21 and 22 are communicated immediately before the intake valves.

On the other hand, an injector 23 is arranged above the inlet of the tumble port 21 so as to direct the fuel toward the intake valve side. A tumble control valve 24 is provided at the inlet of the bypass port 22 so as to be opened and closed by an actuator 25. Here, the fuel from the injector 23 is set to a small amount on the basis of the intake air amount, the engine speed, etc. at low speed and low load to be injected during the intake stroke, and at the time of high speed and high load, a large amount of fuel is set and before the intake stroke. Set to fire. Also, the tumble control valve 24
Is controlled by the actuator 25 to close only at low speed and low load.

Further, measures for preventing deterioration of combustion due to fuel adhering to the partition wall 20 will be described. The spray of the fuel adhering to the partition wall 20 grows into droplets in the process of flowing down there and is discharged from the terminal end portion 20b. Can be released smoothly. Therefore, the terminal portion 20b of the partition wall 20
Triangular portions 30 are formed on both inner and outer sides by cutting into a V-shape.

Next, the operation of this embodiment will be described. First, in the intake stroke during engine operation, the intake valves 14 and 15 open and close at a predetermined timing, the piston 4 inside the cylinder 3 reciprocates, and fuel is further injected from the injector 23. Therefore, at low speed and low load such as idling, the tumble control valve 24 is closed by the actuator 25, so that the intake air from the bypass port 22 is cut. For this reason, when the two intake valves 14 and 15 are opened in the intake stroke, only the tumble port 21 is inhaled, fuel is injected into the intake air by the injector 23, and an air-fuel mixture is generated. This air-fuel mixture passes through the combustion chamber 6. Flow into the cylinder 3.

Therefore, the air-fuel mixture in the tumble port 21 is guided to the exhaust port side by being guided by the flow path having a large radius of curvature in the upper portion inside the intake port. Therefore, the flow velocity distribution around the valve is oriented toward the exhaust port side as shown in FIG. Therefore, in the two intake ports 11 and 12, the air-fuel mixture is linearly flown into the cylinder 3 via the exhaust port side while being redirected so as to face the cylinder axis direction. Therefore, the tumble flow T swirling in the cylinder axis direction is efficiently generated in the cylinder 3 and the combustion chamber 6 by this gas flow.

Next, in the compression stroke, the mixture in the cylinder 3 is compressed by the movement of the piston 4, so that the tumble flow T also collapses. When the tumble collapses in the latter half of the compression stroke, the flow of the air-fuel mixture is greatly disturbed and the combustion chamber 6
Creates a strong turbulence inside. When the spark plug 7 in the center of the combustion chamber 6 is ignited there, the air-fuel mixture burns at a high burning speed due to strong turbulence, thus promoting the burning. Therefore, combustion can be performed with a lean air-fuel mixture without sacrificing operating performance, and emissions can be improved by EGR control.

At this time, the injector 23 and the partition wall 20 are arranged relatively close to each other so that fuel spray from the injector 23 adheres to the partition wall 20. And this spray flows down the surface of the partition wall 20, and the terminal part 20b of the branch part 20a.
However, due to the presence of the triangular portions 30 on the inner and outer sides of the terminal end portion 20b, they rapidly gather at the four triangular portions 30 as shown in FIG. 3 to rapidly grow into large droplets A and smoothly from the tip. Drop on. In this way, the fuel spray adhering to the partition wall 20 is dropped from the triangular portion 30 to both sides of the two intake ports 11 and 12 and is released early after the injection, so that the fuel is intermittently burned during the intake stroke. Inflow into the chamber 6 is avoided, and deterioration of combustion does not occur.

At high speed and high load, the tumble control valve 24 is opened by the actuator 25 so that the bypass port 22 also communicates. Therefore, in the intake stroke, the tumble port 21 and the bypass port 2 of the two intake ports 11 and 12
2, a large amount of air is sucked in, the efficiency of air filling is improved, and the output is increased. In this case, a large amount of fuel is injection-controlled by the injector 23 in advance before the intake stroke, so that the fuel temporarily stays immediately before the two intake valves 14 and 15 which are closed. Also, in the intake stroke, the two intake valves 14,
When 15 opens, tumble port 21 and bypass port 2
The air flowing through 2 joins immediately before the two intake valves 14 and 15, and is taken into the cylinder 3 together. Therefore, the fuel staying immediately in front of the two intake valves 14 and 15 both comes into contact with a large amount of air that merges at that location and is mixed well, and thus the air from the two intake ports 11 and 12 to the cylinder 3 is mixed. And fuel promotes mixing and flows in. Therefore, a uniform air-fuel mixture is generated in the cylinder 3 and is satisfactorily combusted.

Another embodiment of the present invention will be described with reference to FIGS. In the second embodiment of FIG. 4, the partition wall 20
A triangular portion 31 is formed on the inner side of the terminal portion 20b. Except for this, the configuration is exactly the same as that described above, and the same parts are designated by the same reference numerals and description thereof is omitted. Therefore, in this embodiment, the fuel droplets adhering to the partition wall 20 smoothly escape to the inside of the two intake ports 11 and 12 by the two triangular portions 31 inside. Further, in this case, the fuel droplets swirl along with the tumble flow T, and the air-fuel mixture in the vicinity of the spark plug is enriched, and thus stable stratified combustion is performed.

In the third embodiment shown in FIG. 5, the triangular portion 32 is formed outside the end portion 20b of the partition wall 20. Therefore, in this embodiment, the fuel droplets attached to the partition wall 20 are
The triangular portion 32 at the location smoothly escapes to the outside of the two intake ports 11 and 12. Further, in this case, the terminal portion 20
Due to the shape of b, the air-fuel mixture from the two intake ports 11 and 12 is further directed to the cylinder center side, and the flow velocity distribution around the valve is also directed to the center. Tumble style T here
Is likely to flow near the center of the cylinder 3 having the largest width, so that the strong tumble flow T is effectively generated near the center of the cylinder.

Although the embodiment of the present invention has been described above, the arrangement of the injector and the tumble control valve may be reversed. It can also be applied to the three intake valve type.

[0023]

As described above, according to the present invention,
In the method of dividing the intake port by the partition wall to generate the tumble flow, the partition wall is configured to smoothly escape the fuel injected from the injector and adhering to it, so that the combustion due to the intermittent inflow of fuel at low speed and low load Can be prevented from worsening. Therefore, the combustion is stabilized, and the effect is particularly great at the cold start and the transient. Since the end part of the partition wall is only obliquely cut to form the triangular part,
The structure is also simple.

In the embodiment in which the triangular portion is formed inside, stratified combustion can be performed by further enriching the air-fuel mixture near the spark plug. Further, in the embodiment in which the triangular portion is formed on the outer side, a strong tumble flow can be further generated near the center of the cylinder to promote combustion.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of an intake device for an engine according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective view of a partition wall.

FIG. 4 is a cross sectional view showing a second embodiment of the present invention.

FIG. 5 is a cross sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

 3 Cylinder 6 Combustion chamber 11,12 Intake port 14,15 Intake valve 20 Partition wall 21 Tumble port 22 Bypass port 23 Injector 24 Tumble control valve 30, 31, 32 Triangular part

Claims (2)

[Claims] 1. A tumble port and a bypass port are formed by providing a partition wall inside the intake port and dividing it into upper and lower parts, an injector is arranged on the inlet side of the tumble port, and a tumble control valve is provided on the inlet side of the bypass port. In the intake system that is arranged and generates a tumble flow in the cylinder by the gas flow when only inhaling from the tumble port, the end portion of the partition wall is cut off obliquely and is located immediately before the intake valve. Inhaler. 2. The end portion of the partition wall is formed with a triangular portion on one or both of the inner side and the outer side so that fuel droplets can be smoothly collected and dropped.
Intake device for the engine described.