JPS5840648B2 - Internal combustion engine intake system - Google Patents

Description

[Detailed description of the invention] The present invention relates to an intake system for an internal combustion engine.

BACKGROUND OF THE INVENTION Conventionally, a helical intake port is used, particularly in diesel engines, which is composed of an almost straight inlet passage and a spiral part in order to generate a strong swirling flow in a combustion chamber during an intake stroke.

However, applying such a helical intake port to a gasoline engine and making slight changes to the helical intake port for a diesel engine to generate the necessary swirling flow in the combustion chamber during low-speed engine operation will not work. Since the operating speed is much higher than that of the diesel AJ, the flow resistance of the air-fuel mixture flowing through the helical intake port becomes large, which causes the problem of reduced charging efficiency during engine high-speed, high-load operation. .

Furthermore, when the flow rate of the air-fuel mixture flowing through the intake port is slow, such as when the engine is running at low speed and low load, even if the intake port is formed into a helical shape, the fuel will not be sufficiently atomized and mixed, resulting in There is a problem in that stable combustion cannot be obtained because the air-fuel ratio of the air-fuel mixture supplied into the combustion chamber fluctuates.

In particular, in gasoline-injected internal combustion engines that inject fuel into the intake port, the combustion material is injected into the intake port in the form of droplets, so the fuel is atomized within the intake port during low-speed, low-load engine operation. It is necessary to promote stable combustion.

The present invention allows air or mixture to be blown out during low-load engine operation into a helical intake port with a new shape that does not reduce filling efficiency during engine high-speed, high-load operation. An object of the present invention is to provide an intake device that promotes atomization of fuel and generates a strong swirling flow inside a combustion chamber.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to Figure 1, 1 is the engine body, 2a+2b, 2c
, 2d are the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder, 3 is an intake valve, 4 is a helical intake port, 5 is an exhaust valve, and 6 is an exhaust port, respectively.

Referring to FIG. 2, which is a cross-sectional view taken along the line ■-■ in FIG. 10 is a combustion chamber formed between the piston 8 and the cylinder head 9, and 11 is a spark plug.

As shown in FIGS. 1 and 2, the cylinder head 9
An intake manifold 13 having four manifold branch pipes 12 is fixed to the intake manifold 13 , and each of these manifold branch pipes 12 is connected to a corresponding intake port 4 .

Note that each manifold branch pipe 12 has a corresponding intake port 4.
A fuel injection valve 14 for injecting fuel inward is attached.

Air is introduced into the intake manifold 13 through an air introduction pipe 15, and an air flow make 16 for measuring the amount of incoming air and a throttle valve 17 connected to an accelerator pedal (not shown) are provided in the air introduction pipe 15. .

The air flow meter 16 is connected to an electronic control circuit for fuel injection amount control (not shown), and fuel proportional to the amount of intake air is injected from the fuel injection valve 14 based on the output signal of the air flow meter 16.

As shown in FIGS. 1 and 2, a common communication passage 18 extending in the longitudinal direction of the engine body 1 is formed below each manifold branch pipe 12, and this common communication passage 18 connects to the intake port of each cylinder. Four communication branches 19 leading into the interior of the 4 are branched.

Each of these communication branches 19 opens on the lower wall surface of the manifold branch pipe 12, as shown in FIG. Directed towards the top wall.

- The central part of the common communication passage 18 is connected to the air introduction pipe 15 upstream of the throttle valve 17 via an air supply pipe 21 and an idle adjustment screw 22.

When the engine is idling or operating at a low load close to idling, most of the air is supplied into each intake port 4 from the communication branch pipe 19 via the air supply pipe 21 and the common communication passage 18.

At this time, as shown in FIG. 2, since the cross-sectional area of the communication branch 19 is small, air flows from the communication branch 19 to the intake port 4 at high velocity.
It will erupt inside.

On the other hand, when the throttle valve 17 opens, most of the air is supplied into each intake port 4 via the intake manifold 13.

4 to 7 schematically show the shape of the helical intake port 4 shown in FIG. 1. FIG.

As shown in FIG. 5, the helical intake port 4 is composed of an inlet passage section A and a spiral section B, in which the intake port axis a is slightly curved.

The opening end of the inlet passage section A is formed in a rectangular shape as shown in FIG. be done.

As shown in FIG. 2, the axis of the intake valve 3 is inclined with respect to the cylinder axis, and the force input passage A extends substantially horizontally.

The first side wall surface 2 of the force inlet passage section A away from the spiral axis
6 is arranged substantially vertically, and this first side wall 26 smoothly connects to the side wall surface 27 of the spiral portion B that curves around the spiral axis.

As shown in FIG. 7 or 10, this side wall surface 27 bulges out more than the cylindrical outlet portion 25 due to the external force, and furthermore, this peripheral wall surface 27 has a distance R between the side wall surface 27 and the spiral axis. The force is approximately constant, but gradually decreases in the direction of the spiral shown by arrow C, and is formed to be approximately equal to the radius D/2 of the cylindrical outlet portion 25 at the spiral end E. .

- The upper side wall surface 28a of the force second side wall surface 28 near the inlet passage section A of the force and spiral axis is formed as a downwardly oriented inclined surface, and the width of this inclined side wall section 28a increases as it approaches the spiral section B. Accordingly, the second side wall surface 28 is widened, and the entire second side wall surface 28 at the connection portion between the inlet passage section A and the spiral section B is formed as an inclined wall surface facing downward, as shown in FIG.

Therefore, the cross-sectional shape of the inlet passage part A is approximately trapezoidal at the connection part between the inlet passage part A and the spiral part B.

The upper half of the second side wall 28 is the intake port 4 in FIG.
The lower half of the second side wall surface 28 is connected to the side wall surface 27 of the spiral portion B at the spiral end E of the spiral portion B.

As shown in FIG. 2, the upper wall surface 30 of the inlet passage section A extends almost horizontally from the open end of the inlet passage section A toward the spiral section B, and then the upper wall surface 31 of the spiral section B extends in the spiral direction C (the spiral direction C). Figure 5)
The inclined upper wall surface 31 then connects to the second side wall surface 28 of the inlet passage section A.

As described above, since the width of the inclined side wall 28a of the entrance passage A is formed to gradually widen toward the spiral part B, the width of the earth wall surface 30 of the entrance passage A approaches the spiral part B. As mentioned above, the spiral part B gradually becomes narrower.
The distance R between the side wall surface 27 of the spiral portion B and the spiral axis is approximately constant at the beginning, but gradually decreases in the spiral direction C. Therefore, the width of the upper wall surface 31 of the spiral portion B tends toward the spiral direction C. It gradually becomes narrower.

Therefore, the upper wall surface 30 of the inlet passage section A extends almost horizontally while becoming narrower in width toward the spiral section B, and then the soil wall surface 31 of the spiral section B, which is smoothly connected to this upper wall surface 30, extends toward the spiral section B. The width becomes further narrower as it descends in the spiral direction C.

As shown in FIG. 2, the lower wall surface 32 of the inlet passage A is approximately parallel to the upper wall surface 30 and extends approximately horizontally toward the spiral MB, and then, as shown in FIG. 2, a smooth curved wall surface 33
It is connected to the cylindrical outlet section 25 through the cylindrical outlet section 25 .

As can be seen from FIG. 5, the width of the lower wall surface 32 is the spiral part B.
It gradually narrows as it gets closer to .

When the engine is idling or operating at a low load similar to idling, most of the air is released into the intake port 4 of the cylinder during the intake stroke via the air supply pipe 21 and the common communication passage 18, as described above. The water is ejected from the communication branch 19 at high speed.

The air blown out from the communication branch 19 is indicated by the arrow Z in FIG.
As shown in , the intake port 4 moves forward toward the upper wall surface 30 at high speed, but at this time, the flow path is deflected toward the first side wall surface 26 side by the inclined side wall surface portion 28 a. It will move forward along the wall surface 30.

As mentioned above, the earth wall surface 30.3 is facing the direction of air movement.
1 becomes gradually narrower, and therefore the flow path of the ejected air formed along the upper wall surface 30, 31 becomes gradually narrower, so that the flow velocity of the ejected air is increased.

Furthermore, since the upper wall surface 31 is descending in the spiral direction C, the ejected air flow along the earthen wall 111i1r30.31 is given a downward force.

In this way, a swirling flow that descends while swirling is generated within the spiral portion B.

On the other hand, the fuel droplets injected from the fuel injection valve 14 into the intake port 4 are torn off and atomized by the powerful swirling flow of the jetted air generated in the intake port 4, thus atomizing the fuel. and the mixing of fuel and air is promoted.

The strong swirling flow generated by the speed-increasing effect of the ejected air then swirls smoothly along the inner wall surface of the cylindrical outlet portion 25 without receiving any side resistance, thereby creating a strong rotation around the spiral axis. A swirling flow is formed within the cylindrical outlet portion 25.

This swirling mixture then flows into the combustion chamber 10 through the gap formed between the intake valve 3 and its valve seat, generating a strong swirling flow within the combustion chamber 10.

As described above, since the atomization and mixing of the fuel injected from the fuel injection valve 14 is promoted and a strong swirling flow is generated within the combustion chamber 10, the combustion speed is greatly increased, thus achieving stable idling. It is possible to secure driving.

On the other hand, when the throttle valve 17 opens, most of the air is supplied into each intake port 4 via the intake manifold 13.

A portion of the air sent into the intake port 4 is transferred to the upper wall surface 30.
．． 31, the remaining air collides with the inclined side wall 28a of the inlet passage A and is given a downward force, and as a result moves along the smooth curved wall surface 33 without turning to the cylindrical outlet 25. flow inside.

By providing the inclined side wall portion 28a in this way, a portion of the air sent into the inlet passage A does not swirl like air flowing through a normal intake port, but forms a cylindrical shape along the smooth curved wall surface 33. Since it flows into the outlet portion 25, the inflow resistance becomes small, and thus it is possible to prevent a decrease in filling efficiency during high-speed, high-load operation.

Another embodiment is shown in FIG.

Referring to FIG. 11, the central part of the common communication passage 18 is connected to the air introduction pipe 15 between the throttle valve 17 and the air flow meter 16 via an air supply pipe 35, and the sub-throttle valve is connected to the air supply pipe 35. 36 are provided.

FIG. 12 shows the opening relationship between the throttle valve 17 and the sub-throttle valve 36.

In FIG. 12, the vertical axis P shows the throttle valve opening, and the horizontal axis shows the amount of depression of the accelerator pedal.

Note that the curve S indicates the opening degree of the sub-throttle valve 36, and the curve T indicates the opening degree of the throttle valve 17.

As shown in FIG. 12, when the accelerator pedal is depressed, the sub-throttle valve 36 remains closed while the throttle valve 17 remains fully closed.
It can be seen that when the sub-throttle valve 36 is gradually opened and the sub-throttle valve 36 is almost fully opened, the throttle valve 17 is gradually opened while the sub-throttle valve 36 is kept fully open.

Note that the throttle valve 17 and the sub-throttle valve 36 are
They are connected to each other by a link mechanism (not shown) so as to have the opening relationship shown in FIG.

As is clear from FIG. 12, in this embodiment, during low load operation, all the air is supplied to the air supply pipe 35 and the common communication path 18.
is supplied into the intake port 4 from the communication branch 19 via
In this way, atomization and mixing of fuel during low-load operation is promoted, and a strong swirling flow can be generated within the combustion chamber 10.

- During high power and high load operation, the throttle valve 17 opens, so most of the air is supplied into the intake port 4 through the intake manifold branch pipe 12 with low flow resistance, thus ensuring high filling efficiency. be able to.

13 and 14 show another embodiment.

In this embodiment, the common communication path 18 is connected only to each intake port 4 via each communication branch pipe 19.

Additionally, a second throttle valve 40 is added to the throttle valve 17.
is provided within each manifold branch 12.

Each of these second throttle valves 40 is fixed to a common throttle shaft 41, and this common throttle shaft 41 is arranged in a model recess 42 formed on the bottom inner wall surface of the manifold branch pipe 12.

The throttle valve 17 and the second throttle valve 40 are connected to each other via a link mechanism (not shown) so that the second throttle valve 40 opens as the throttle valve 17 opens.

When the ignition order is, for example, 1-3-4-2 in a four-cylinder internal combustion engine as shown in FIG. 13, if the first cylinder 2a is in the intake stroke, the third cylinder 2c is in the exhaust stroke.

Normally, at the end of the exhaust stroke, there is a valve polymerization period when both the intake valve 3 and the exhaust valve 5 open, but during this valve polymerization period at the end of the exhaust stroke, relatively high pressure burnt gas flows into the combustion chamber of the No. 3 cylinder. 10
The air is blown back from the inside into the intake port 4 of the third cylinder, thereby creating a positive pressure inside the intake port 4 of the third cylinder.

-When the No. 3 cylinder 2c is at the end of its exhaust stroke, a large negative pressure is generated in the intake port 4 of the No. 1 cylinder 2a.
Therefore, at this time, the burned gas or air in the intake port 4 of the third cylinder 2c is forced into the common communication passage 18 via the communication branch 19 that opens to the intake port 4 of the third cylinder 2c,
Next, this pushed-in burned gas or air flows into the first cylinder 2.
1 through a communication branch 19 opening into the intake port 4 of a.
It will be ejected at high speed into the intake port 4 of the number cylinder 2a.

Similarly, in the remaining cylinders, during the intake stroke, the burnt gas or air sent into the common communication passage 18 from other cylinders is ejected from the communication branch passage 19 into the intake port 4.

As shown in FIGS. 13 and 14, especially during low-load operation, by providing the second throttle valve 40, the pressure inside the intake port 4, which has increased due to the blowback effect, remains positive for a while without being attenuated. Since this can be maintained, burnt gas or air can be ejected from the communication branch 19 into the intake port 4 for a long period of time.

Furthermore, as shown in FIG. 14, in this embodiment, the air flow gap 43 in the second throttle valve 40 during low load operation is
is the upper edge of the second throttle valve 40 and the manifold branch pipe 12.
The second throttle valve 4 is formed between the upper inner wall surfaces of the second throttle valve 4.
The air that has passed through 0 will proceed along the soil wall surface 30, 31 of the intake port 4.

Therefore, during low load operation, a strong swirling flow is generated in the intake port 4 by the burnt gas or air ejected from the communication branch 19 and the air passing through the air circulation gap 43.

FIG. 15 and FIG. 16 show the case where the present invention is applied to an internal combustion engine with a carburetor.

Referring to FIGS. 15 and 16, an intake manifold 46 including a carburetor 45 is fixed to the cylinder head 9, and each manifold branch pipe 47 of the intake manifold 46 is connected to a corresponding intake port 4.

In addition to the carburetor throttle valve 48, a second throttle valve 49 is provided in each manifold branch pipe 47, and each of the second throttle valves 49 is fixed to a common throttle shaft 50.

An arm 51 is fixed to the common throttle shaft 50, and a control rod 53 of a negative pressure diaphragm device 52 is pivotally attached to the tip of the arm 51θ).

The negative pressure diaphragm device 52 has a negative pressure chamber 55 and an atmospheric pressure chamber 56 separated by a diaphragm 54.
A compression spring 57 for pressing the diaphragm is inserted into the diaphragm 5 .

This negative pressure chamber 55 is connected to the throttle valve 4 via a negative pressure conduit 58.
8 downstream of the intake manifold 46.

On the other hand, in this embodiment, the opening 20 of each communication branch 19 is oriented in the axial direction of the inlet passage A of the intake port 4, as shown in FIG.

Further, as shown in FIGS. 15 and 16, the central portion of the common connecting passage 18 is connected to the intake manifold gathering portion 46a via a sub-intake passage 59.

As shown in FIG. 16, during low-load operation with a small opening degree of the carburetor throttle valve 48, the negative pressure in the intake manifold 46 downstream of the carburetor throttle valve 48 is large, and this small negative pressure is applied to the negative pressure diaphragm device. The diaphragm 54 rises against the compression spring 57 in order to enter the negative pressure chamber 55 of 52,
As a result, the second throttle valve 49 assumes the fully closed position as shown in FIG.

On the other hand, when the carburetor throttle valve 48 is wide open and high-load operation is performed, the negative pressure in the negative pressure chamber 55 becomes small, so the diaphragm 54 is lowered by the spring force of the compression spring 57, and as a result, the second throttle Valve 49 is fully opened.

As mentioned above, during low load operation, the second throttle valve 49
is maintained in a fully closed state, the air-fuel mixture formed in the carburetor 45 flows through the sub-intake passage 59 and the common communication passage 18.
The air is ejected from the communication branch 19 into each intake port 4 through the communication branch 19 .

As shown in FIG. 16, since the sub-intake passage 59 and the common communication passage 18 have a relatively small cross-sectional area, the air-fuel mixture flows at a high velocity in these passages 59.18, and as a result, the mixture flows in these passages 59.18 at a high velocity. Fuel vaporization is promoted.

Next, the air-fuel mixture is ejected from the communication branch 19 as shown by the arrow Z, and then advances into the intake port 4 along the intake port upper wall surface 30, thus generating a strong swirling flow inside the intake port 4. do.

As a result, the vaporization of the fuel is further promoted, and the combustion chamber 10
Since a strong swirling flow is generated within the manifold branch pipes 47, the combustion speed is increased, and stable combustion can thus be obtained.9 In this embodiment, a second throttle valve 49 or a The jetting speed of the air-fuel mixture jetting out from each communication branch 19 can be increased.

That is, if the second throttle valve 49 is not provided in the manifold branch pipe 47, for example, during the intake stroke of the first cylinder 2a, the communication branch pipes corresponding to the intake ports 4 of the other cylinders 2b, 2c, and 2d, respectively. The air-fuel mixture blown out from 19 is supplied into the intake port 4 of the No. 1 cylinder 2a through the intake manifold 46, and as a result, the mixture is blown out from the communication branch 19 which opens into the intake port 4 of the No. 1 cylinder 2a. The air volume decreases and thus the speed of the air-fuel mixture emerging from the communication branch 19 decreases.

However, as shown in FIG.
9 in the manifold branch pipe 47, the air-fuel mixture is supplied only from the communication branch pipe 19.
The flow velocity of the air-fuel mixture ejected from the intake port 4 can be increased, and a strong swirling flow can be generated within the intake port 4.

During high-load operation, the second throttle valve 49 is fully opened as described above, so most of the air-fuel mixture formed in the carburetor 45 is supplied into each intake port 4 through the intake manifold 46 with low flow resistance. In this way, high filling efficiency can be ensured during high-speed, high-load operation.

As described above, according to the present invention, air or mixture is distributed along the soil wall surface of the helical intake port during low-load operation into the helical-type intake port, which has a novel structure that does not reduce filling efficiency even during high-speed, high-load operation. Air is ejected at high speed, thereby promoting atomization or vaporization of fuel and generating a strong swirling flow within the combustion chamber.

As a result, the combustion speed during low-load operation increases significantly, making it possible to ensure stable combustion.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an internal combustion engine according to the present invention, and FIG.
Figure 3 is a cross-sectional view taken along line III--III in Figure 2, Figure 4 schematically shows the helical intake port in Figure 2. A perspective view, Figure 5 is a plan view of the helical intake port taken along the arrow ■ in Figure 4, Figure 6 is a side view of the helical intake port taken along the arrow ■ in Figure 4, and Figure 7. is a side view of the helical intake port taken along the arrow ■ in Figure 4, Figure 8 is a sectional view taken along the line ■-■ in Figure 5, and Figure 9 is a cross-sectional view taken along the line ■-■ in Figure 5. Figure 10 is a cross-sectional view taken along the line X- in Figure 5.
11 is a side view of another embodiment, FIG. 12 is a graph showing changes in the opening of the throttle valve and sub-throttle valve of FIG. 11, and FIG. 13 is a diagram of another embodiment. FIG. 14 is a plan view of the embodiment, FIG. 14 is a side sectional view of FIG. 13, FIG. 15 is a plan view of yet another embodiment, and FIG. 16 is a side sectional view of FIG. 15. 3...Intake valve, 4...Helical intake port, 5...Exhaust valve, 10...Combustion chamber, 11...Ignition Stopper, 13.46...
Intake manifold, 14...Fuel injection valve, 16.
...Air crow meter, 17...Throttle valve, 18...Common communication path, 19...
・Communication branch, 21.35... Air supply pipe, 36
・・・・・・Sub-throttle valve, 40.49・・・・・・
2nd throttle valve, 45... carburetor.

Claims (1)

[Claims] 1 is a helical intake port composed of an inlet passage portion extending approximately straight and a spiral portion, wherein the inlet passage portion has a first side wall surface located at a substantially vertical position on a side away from the spiral axis of the spiral portion; , a second side wall surface located on the spiral axis side and facing the first side wall surface and arranged substantially vertically, and a soil wall surface and a lower wall surface extending in a substantially horizontal plane, thereby forming the inlet passage section. In an internal combustion engine equipped with a rectangular-type intake port having a substantially rectangular cross-sectional shape over the entire length, the upper part of the second side wall surface located on the spiral axis side is formed into a downwardly inclined surface, and the inclined surface is The width of the upper wall surface of the inlet passage section is gradually narrowed toward the spiral section by gradually increasing the width as it approaches the spiral section, and the width of the second side wall surface is gradually narrowed toward the spiral section. The cross-sectional shape of the inlet passage in the connection part is formed into a trapezoidal shape in which the width of the upper wall surface is narrower than the width of the lower wall surface, and the soil wall surface of the spiral part is formed in a spiral direction. A common communication passage is provided separately from the intake passage leading to the intake port, and the common communication passage is connected to the intake port of each cylinder through a communication branch, and the communication branch is opened on the lower wall surface of the intake port inlet portion, and the communication branch passage opening is connected to the intake port downstream of the communication branch passage opening so that the air or air-fuel mixture ejected from the communication branch passage opening flows toward the inclined surface. An internal combustion engine intake system directed toward the upper wall.