JP2697517B2 - Intake port structure of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake port structure for an internal combustion engine which is particularly suitable for a stratified combustion internal combustion engine.

[0002]

2. Description of the Related Art In recent years, in order to increase the area of an intake passage of a combustion chamber of an engine without increasing the size of an intake valve, an internal combustion engine having a siamese-type intake port which is divided into two and flows into one combustion chamber. Is being used. In such an internal combustion engine, generally, an air-fuel mixture flows into a combustion chamber from two intake port portions.

[0003]

By the way, in the above-mentioned internal combustion engine, usually, an intake valve is provided at each of the openings of the two intake port portions to the combustion chamber, and the intake valve is provided in the intake port. Of the stem is arranged.
For this reason, a part of the flow of the intake air may hit the valve stem and be disturbed, and in consideration of the intake efficiency, the disturbance of the intake flow by the valve stem is a problem.

[0004] In addition, the turbulence of the intake air flow has become a very serious problem in a stratified combustion internal combustion engine which is being developed in recent years. Here, the stratified combustion internal combustion engine will be described.
For example, by generating a vertical swirling flow in a cylinder as shown in FIGS. 14 and 15, a so-called tumble flow F (Fa, Fm), it is intended to efficiently burn fuel.

FIGS. 14 and 15 show the structure of one cylinder of a two-intake port type internal combustion engine which generates such tumble flows Fa and Fm. In the drawings, reference numeral 22 denotes a cylinder block, and FIG. Is a cylinder bore, 26 is a piston, 28 is a cylinder head, and 30 is a combustion chamber. Reference numeral 34 denotes a pent roof formed on the upper wall portion of the combustion chamber 30. Reference numerals 40 'and 42' denote intake passages provided two by two in each cylinder.
An intake valve 58 is installed in each of the intake ports 44 'of 2'.

The pent roof 34 has a plurality of intake passages 40 ',
The intake passages 40 ', 42' are provided with slopes so that the intake air flow from the intake passages 40 ', 42' can be guided downward along the inner wall surface of the cylinder bore 24 on the extension axis of each intake passage 40 ', 42'.
Is also assisted by the guidance of the pent roof 34 and proceeds in the tumble flow directions as indicated by arrows Fa and Fm, respectively.

Further, in order to promote the tumble flow, the shape of the intake port 44 'is important.
4, the intake port 44 'is formed as a straight straight port as shown in FIG. 15, or the intake port 44' is narrowed as shown in FIG. 18 to rectify the flow. . In FIGS. 14 and 18, reference numerals 40F and 42F indicate normal intake ports that are not straight ports.

The cross section of the intake port 44 'is generally formed in a circular shape as shown in FIG. 16, but is formed in an elliptical shape or an oblong shape as shown in FIG. May be formed. Also, in this example,
As shown in FIG. 15, the injector 12 is provided only in one intake passage 42 ′, and the ignition plug 11 is arranged near the intake valve 58 in the intake passage 42 ′ equipped with the injector 12. Therefore, this spark plug 11
, A mixture of the fuel injected from the injector 12 and the intake air flows into the combustion chamber 30 through the intake passage 42 'and the intake port 44' to form a tumble flow Fm of the mixture. . Also, the intake passage 40 '
From the intake port 44 ', only air flows into the combustion chamber 30 to form a tumble flow Fa of this air.

As a result, a stratified tumble flow of the tumble flow Fm of the air-fuel mixture and the tumble flow Fa of the air is formed in the combustion chamber 30. The tumble flow generated in this way is effective in increasing the flame propagation speed and the combustion stability. Experimental data on the heat generation amount Q, the in-cylinder pressure P, and the heat generation rate dQ are shown, for example, in FIG. "Tumble flow" (when a tumble flow is generated) compared to "Standard" (a general case where no tumble flow is generated)
It can be seen that the heat generation amount Q, the in-cylinder pressure P, and the heat generation rate dQ have smaller cycle fluctuations, and the combustion stability is better.

In the drawings, reference numeral 47 denotes an exhaust port communicating with the exhaust passage 60, and 59 denotes an exhaust valve. In such a stratified combustion internal combustion engine, it is desired to feed the intake air into the combustion chamber without disturbing the intake air as much as possible so as to be advantageous for stratification and tumble flow of the intake air. The present invention has been made in view of the above-described problem, and has been made to allow an intake air flow from an intake port to smoothly flow into a fuel chamber without being disturbed.
An object of the present invention is to provide an intake port structure for an internal combustion engine.

[0011]

According to the first aspect of the present invention, there is provided an intake port structure for an internal combustion engine according to the present invention, wherein the intake port is divided into two parts having two combustion chamber openings respectively opened and closed by two intake valves. equipped with a port, the intake port
The intake air flow from the air becomes a tumble flow in the combustion chamber
In internal combustion engine formed as, in the combustion chamber top
In the flow direction while rectifying the intake flow, at a position along a streamline including the ignition means disposed in the central portion and the valve stem upstream of the intake valve stem in each of the above intake port portions, Are respectively arranged so as to be bisected along the
A central passage on the ignition means side and the central side in the air port portion;
A flow straightening member which is divided into side passages on both sides of the passage;
Equipped with a fuel injection means for injecting fuel into the side passage, intake
The central passage and the side passages of the air port are in full operation of the engine.
The cross-sectional area of the passage is unchanged throughout the state .

According to a second aspect of the present invention, the rectifying member is constituted by a partition wall, and a thickness of the partition wall at an end near the valve stem is substantially equal to or larger than a diameter of the valve stem. The rectifying member may be configured by a partition wall, and the thickness of the partition wall at the end near the valve stem may be smaller than the diameter of the valve stem. May be set to be substantially equal to or slightly smaller than the diameter.

[0013] Further, the thickness of the partition wall may be made thinner toward the upstream end .

[0014]

In the intake port structure for an internal combustion engine according to the first aspect of the present invention, when each intake valve of the intake port is opened, the intake air enters the combustion chamber from the two combustion chamber openings provided with these intake valves. Flows into the combustion chamber
Forms a tumble flow . At this time, the rectifying member disposed at a position along the streamline including the valve stem upstream of the stem of the intake valve in each intake port portion rectifies the intake flow along the flow direction while rectifying the intake flow. Center
It is divided into a side passage and a side passage, and flows into the combustion chamber. Therefore, the intake air flow from the central passage in the combustion chamber
And the intake air flow from the side passage
Form a bull flow. The fuel injection means
The combustion chamber by the intake air flow from the central passage.
The laminar tumble flow formed in the central part of the
A fuel-rich mixture layer with a high fuel concentration
The fuel-lean mixture, which contains almost no fuel,
Is an air layer). And layered tumble flow
The fuel-rich mixture layer is located at the center of the top of the combustion chamber.
Flows into the vicinity, and is ignited by ignition means
The fire ensures that the fuel / fuel mixture is rich
And proper stratified combustion is realized. In particular, the intake
The central passage and the side passages of the port are in the full operating state of the engine;
The passage cross-sectional area is configured to be constant over
Regardless of the condition, the intake air flow from the central passage and the side passage
The intake air flow from the air is always surely separated into layers and a tumble flow
To ensure proper stratified combustion at all times
Can.

Further, the rectifying member is constituted by a partition wall, and a thickness of the partition wall at an end near the valve stem is substantially equal to or larger than a diameter of the valve stem. When set to be slightly larger, rectification of the intake flow near the valve stem is promoted. Further, the rectifying member is constituted by a partition wall, and a thickness of the partition wall at an end near the valve stem is substantially equal to or slightly smaller than a diameter of the valve stem. When set so that the intake air flow near the valve stem is rectified,
The intake flow rate in the intake port is secured.

Further, when the thickness of the partition wall is made thinner toward the upstream end portion, rectification of the intake air flow in the vicinity of the valve stem is promoted. Is done .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 12 show an embodiment of an intake port structure of an internal combustion engine of the present invention, and FIG. FIG. 2 is a schematic top view showing the configuration of the main part thereof, as viewed from the direction indicated by the arrow A in FIG. 1, and FIG. 3 is a schematic partial cross-sectional view showing the configuration, taken along the line CC in FIG. FIG. 4 is a schematic partial cross-sectional view showing the configuration, and is a BB cross-sectional view in FIG. 3, FIG. 5 is a schematic view showing the configuration, and FIG. 6 is a modified example of the intake port structure and the partition. [(A) is a schematic configuration viewed from above the cylinder in the cylinder axis direction, (B) is a schematic configuration viewed from the side of the cylinder, (C) is a direction D in (B). Arrow view),
FIG. 7 is a schematic diagram showing another modification of the partition having the intake port structure (a diagram corresponding to FIG. 5), FIG. 8 is a schematic diagram showing the fuel injection variation, and FIGS. it is a graph for explaining.

As shown in FIG. 1, a combustion chamber 30 is formed in each cylinder of the internal combustion engine by being surrounded by a cylinder bore 24, a piston 26 and a cylinder head 28 formed in a cylinder block 22. Each cylinder of the internal combustion engine is configured as a four-valve internal combustion engine having two intake valves and two exhaust valves, and an intake port 46 is led into the combustion chamber 30. The intake port 46 is a siamese port that is divided into two intake port portions 46A and 46B by a port partition (intake port branch portion) 46C on the way, and the combustion chamber of each intake port 46A and 46B. An intake valve 58 is installed in each of the openings. The exhaust port 47 is also a siamese port, and two exhaust ports 47 are provided in the combustion chamber 30.
Parts A and 47B are also guided, and exhaust valves (not shown) are provided.

As shown in FIGS. 1, 2 and 5,
Each intake port portion (hereinafter, this intake port portion is also simply referred to as an intake port) 46A, 46B is connected to an intake passage (intake manifold) (not shown). Also, in the figure, 1A and 1B are the intake ports 46A,
The axis of 46B (the center line of the upper and lower ends and the left and right ends) is shown. The exhaust ports 47A and 47B merge on the downstream side and are connected to a common exhaust passage (not shown).

In the vicinity of the branch portion 46C of the intake ports 46A and 46B, an injector 12 as a fuel injection means described later is mounted.
Thus, the fuel is injected into the intake ports 46A and 46B. In this embodiment, each of the intake ports 46A and 46B is formed as a straight straight port substantially parallel to each other. Therefore, the axial lines 1A and 1B of the intake ports 46A and 46B are two straight lines substantially parallel to each other as shown in FIGS. Therefore, on the downstream side from the vicinity of the branch portion 46C of the intake ports 46A, 46B, the intake ports 46A, 46B are formed substantially parallel to each other, and the respective intake ports 46A, 46B are formed.
The intake air from B is shown in FIG.
The fuel flows into the combustion chamber 30 in a state substantially parallel to each other.

The intake ports 46A and 46B are not limited to those substantially parallel to each other, but may be, for example, those shown in FIG. In FIG. 6A, the degree of bending of one intake port 46B is shown, but the other intake port 46A is also formed in line symmetry with this. That is, the intake ports 46A, 46B
However, it is formed so as to slightly spread from the branch portion 46C toward the intake valve 58.

Further, the two intake ports 46A and 46B may be obliquely connected to the combustion chamber 30 while being substantially parallel to each other. In other words, as shown in FIG. 6A, when a plurality of cylinders are arranged in a line, the surface 9 in the column direction (a line L connecting the centers of the two intake valves 58, 58 in a plan view) (Parallel to this), both intake ports 46A, 46B are connected to the combustion chamber 30 without being orthogonal to each other.

In any case, the intake ports 46A, 46B
The shape and arrangement direction of the intake ports 46A and 46B are not strictly limited as long as they do not hinder the formation of the laminar tumble flow due to the intake flow from the intake port. Then, as shown in FIG. 4, the cross-sectional shape of such a straight port is the tumble flow side half of the intake ports 46A, 46B (ie, the upper half of the intake ports 46A, 46B through which the main component flow forming the tumble flow flows). Parts) 46A-1, 46B-
1 is the other half (i.e., the lower half of the intake ports 46A and 46B through which the component flows that block the tumble flow) 46
A-2, 46B-2, the width of which is wider than that of A-2, 46B-2.
B-1). Thereby, the intake port 4
The intake air flows from 6A and 46B easily form a tumble flow in combustion chamber 30. Then, in the actual施例this, the intake ports 46A, 46B are formed to have a cross section of generally inverted triangular as shown in FIG. In addition,
Reference numerals 21 and 21 shown in FIG.
A partition wall serving as a rectifying member that divides A and 46B into two, which will be described in detail later.

Further, as shown in FIG. 1, a recess 35 is formed on the top surface of the piston 26 so that a space is secured between the cylinder head 28 and the piston 26 when the piston 26 reaches the top dead center. Are formed. Also, this recess 35
, A protruding portion 39 which is higher than the recess 35 is provided, and a slope 37 is formed in the protruding portion 39 so as to smoothly connect from the recess 35.

The recess 35 is formed below the exhaust valve (not shown) (below the opening of the combustion chamber of the exhaust port), and the raised portion 39 is formed below the intake valves 58, 58. As a result, as shown in FIG.
A, 46B, tumble flow side half 46A-1, 46B-1
The intake air flows Fa and Fm flow from the recess 35 to the bulge 39 through the slope 37 to form a tumble flow.

As shown in FIGS. 1 and 5, a spark plug 11 as ignition means is provided at the center of the top above the combustion chamber 30, and the intake ports 46A, 4
6B on the reference plane 3. Here, the reference plane 3 is an imaginary plane located substantially at the center of both the intake ports 46A and 46B. Meanwhile, as shown in FIGS. 1 to 5, a partition 21 as a rectifying member is provided in each of the intake ports 46A and 46B so as to bisect the inside of each of the intake ports 46A and 46B in the left-right direction. In each of the intake ports 46A and 46B, a passage on the reference surface 3 side (spark plug side) of the intake air flow (that is,
A side passage) 4 and a passage (ie, a side passage) 5 outside the reference surface 3 (on the side opposite to the ignition plug) are bisected along the flow direction of the intake air. That is, each of the intake ports 46A, 46B
The partition wall 21 allows the spark plug side passage (ignition means side passage) 4 and the anti-spark plug side passage (anti-ignition means side passage) 5.
And are separated into

As shown in FIG. 2, the partition wall 21 is formed along the stream line 45 of the intake air flow flowing into the valve stem 57 on the upstream side of the stem portion (valve stem) 57. I have. Here, since the valve stem 57 is disposed on the center line 45A of the streamline 45 of the intake flow, the partition wall 21 is disposed on the centerline 45A of the streamline 45 of the intake flow. .

The center line 45A of the streamline 45 is along the axis 1A, 1B of the intake ports 46A, 46B.
Here, the partition 21 is provided with the intake ports 46A, 46B.
Along the axial lines 1A and 1B of FIG. 1, and extends from near the disposition position of the injector 12 to the downstream side. Further, since the intake ports 46A and 46B are substantially parallel to each other, these partition walls 21 and 21 are also disposed substantially parallel to each other.

As shown in FIG. 3, the partition 21 is formed from the upper wall surface 8 to the lower wall surface 7 of the intake ports 46A, 46B.
Downstream of the intake valve 58 along the axis 2 of the intake valve 58
Is extended to the vicinity of the umbrella portion 56 of the umbrella. However, the partition 21
Are formed so as not to come into contact with the umbrella portion 56 and the valve stem 57 of the intake valve 58 so as to secure an appropriate clearance therebetween, so that the operation of the intake valve 58 is not affected at all. .

The partition 21 is provided with an intake port 46.
A, 46B so as to completely separate the intake air flow into the spark plug side passage 4 and the non-spark plug side passage 5.
6 (46A, 46B) extending from the upstream end. Therefore, in the intake ports 46A and 46B, the intake air flow is branched into the spark plug side passage 4 and the non-spark plug side passage 5 by the partition wall 21 and is separated from each other while being rectified. The gas flows into the combustion chamber 30 without being disturbed.
With such a partition 21, the flow of the intake air is reduced by the combustion chamber 30.
As shown in FIG. 5, when the air flows smoothly into the air-fuel mixture layer Fm and the air-only layers Fa and Fa, the air-fuel mixture layer Fm and the air-only layers Fa and Fa are mixed.
(A total of three flows of the ignition plug side passage 4 and the anti-spark plug side passage 5 on both sides thereof), that is, a tumble flow is formed in a layered state. I have. Thus, the present internal combustion engine is configured as a stratified combustion internal combustion engine.

It should be noted that the partition wall 21 supplies at least the fuel injected from the injector 12 to each of the intake ports 46A, 46B.
It is only necessary to hold the spark plug side passage 4 inside so as not to flow out to the anti-spark plug side passage 5. Therefore, the partition 21 is not necessarily connected to the intake ports 46A, 46B.
1, 2, 5, 6, 7
As shown by a dashed line in the drawing, the intake ports 46A and 46B may be provided from the upstream intermediate portion to the downstream side. Figure 1
2 and the modified example shown in FIG. 6B are examples in which the upstream end of the partition 21 is provided on the downstream side of the injection port of the injector 12, and the example shown in FIG. In the modification shown in FIG. 7, the upstream end of the partition 21 is connected to the injector 1.
This is an example provided at a position corresponding to the second injection port.

The partition walls 2 shown in FIGS.
In the first modification, the intake ports 46A and 46B slightly spread from the branch portion 46C toward the intake valve 58, and accordingly, the partition walls 21 are not parallel to each other. However, also in this case, the partition 21
It is disposed on the upstream side of the valve stem 57, along the streamline 45 of the intake flow to be flown into the valve stem 57, and exactly on the center line 45A of the streamline 45 of the intake flow. Therefore, while the intake air flow is rectified by the partition wall 21 and is kept separated from the ignition plug side passage 4 and the anti-ignition plug side passage 5, the flow is not disturbed by the valve stem 57 and is stratified. The formation of the tumble flow is promoted.

By the way, the valve stem 57 itself has a resistance to the intake air flow in the vicinity of the valve stem 57, whereas the partition 21 has a function of reducing this resistance. In order to reduce the resistance at the valve stem 57, it is generally considered that the vicinity of the valve stem 57 at the rear end of the partition 21 is slightly thicker than the outer diameter of the valve stem 57. However, the intake ports 46A, 46
In B, the intake port 46 corresponds to the sectional area of the partition 21.
Since the cross-sectional areas of A and 46B are reduced, it is conceivable that the flow coefficient of the intake ports 46A and 46B is reduced according to the thickness of the partition wall 21 and the engine full-opening performance is reduced. Therefore, in order to secure a flow coefficient, it is desirable to reduce the cross-sectional area of the partition 21 as much as possible.

Therefore, in this embodiment, the valve stem 5
The thickness of the partition 21 is set to be substantially the same as or smaller than the outer diameter of the valve stem 57 in order to achieve both the reduction of the resistance at 7 and the reduction of the flow coefficient. Of course, if importance is placed on reducing the resistance at the valve stem 57, the thickness of the partition 21 may be set slightly larger than the outer diameter of the valve stem 57, and the intake ports 46A, 46B
In order to secure the flow coefficient of the above, the thickness of the partition 21 may be set slightly smaller than the outer diameter of the valve stem 57.

In addition, the upstream end 21 of the partition 21 of this embodiment
A and the downstream end 21B are both formed in a substantially cylindrical convex curved surface so that a rectifying effect of the intake air flow can be obtained. The reason why the upstream end 21A and the downstream end 21B are formed in this way is to aim at the effect of reducing the fluid resistance by rectifying the intake air flow and to consider the efficiency in manufacturing the partition 21. In other words, when each end 21A, 21B is formed into a convex curved surface, for example, when casting the intake port 46, the mold (core) corresponding to each end 21A, 21B can be easily removed. Casting can be performed easily and reliably. In this embodiment, such easiness of manufacture is also taken into consideration.

The shape of the upstream end 21A is not limited to such a cylindrical surface, but may be a curved surface protruding at an acute angle or a wedge shape protruding at an acute angle. Can be expected sufficiently, and various types other than this embodiment can be considered. Also, the downstream end 21B may be of various other types, such as a shape close to a simple planar shape, and is substantially aligned with the surface of the valve stem 57 as in a modified example shown in FIGS. 6A and 6C. It is conceivable that the intake air flow is formed into a concave curved surface as described above. In this case, the smooth flow of the intake air from the downstream end 21B of the partition 21 into the valve stem 57 is further promoted.

In any case, it is desirable to set the distance between the downstream end 21B and the valve stem 57 based on the fluid theory so as to be appropriate for the shape. In this embodiment, the inner wall and the outer wall of the partition 21 are set substantially parallel to each other. However, as shown in FIG. Then, it is formed as thin as possible. Conversely, as the valve stem 57 approaches the downstream valve stem 57, the valve stem 5 gradually decreases.
7 may be formed so as to have a thickness substantially equal to the diameter of 7. Also in this way, the flow of the intake air can smoothly flow into the combustion chamber 30 without being disturbed by the valve stem 57.

In the example shown in FIG. 7, the maximum width portion of the partition 21 is not located near the downstream end 21B, but at the downstream end 21B.
It is provided slightly upstream from B and has a shape close to a streamline as a whole.
It is also conceivable to form it near the downstream end 21B. Also,
Also in this case, the maximum thickness of the partition 21 is adjusted by the valve stem 57.
The thickness of the partition 21 is set to be slightly larger than the outer diameter of the valve stem 57, and the intake ports 46A, 46B The thickness of the partition 21 may be set to be slightly smaller than the outer diameter of the valve stem 57 in order to secure the flow coefficient of the valve stem 57.

Further, in this embodiment, in order to secure the flow coefficient, the intake ports 46A and 46B are connected to the upper half 4 having a substantially inverted triangular cross section as shown by the hatched portion 13 in FIGS.
6A-1 and 46B-1 are enlarged substantially by the sectional area of the partition wall 21. As a result, a decrease in the cross-sectional area of the intake ports 46A and 46B due to the cross-sectional area of the partition 21 is offset, and the flow coefficient when the engine is fully opened is secured.

By the way, as shown in FIGS. 1 and 5, the injector 12 as the above-described fuel injection means is provided between the two intake ports 46A and 46B in the upper portion near the branch portion 46C of the two intake ports 46A and 46B. Are arranged along the reference plane (center plane) 3 of the intake air flow. Then, the fuel is injected toward the lower surface downstream of the intake ports 46A and 46B. Reference numeral 6 in FIGS. 2, 3, and 5 denotes an injector injection axis, which indicates the injection direction of the injector 12.

That is, as shown by the injector injection axis 6, the injector 12 is connected to the intake ports 46A, 4A.
Fuel is injected obliquely downward on the downstream side of the intake ports 46A, 46B from the upper side between 6B.
Therefore, the injected fuel is supplied to each intake port 46A,
While being guided by the partition walls 21 and 21 of the intake port 46B, the ignition plug side passages (that is, the central
The air is smoothly sucked into the combustion chamber 30 through the passages 4, and only the air flows through the anti-spark plug side passages 5 on both sides of the ignition plug.

As an injection variation of the injector 12, the branch portion 4 of the two intake ports 46A and 46B is provided.
Types shown in FIGS. 8A to 8D can be considered according to the shape of 6C. (A) is for injecting fuel toward the branch portion 46C of the siamese type intake ports 46A and 46B. After the fuel is positively collided with the branch portion 46C,
The diffused fuel is caused to flow to the ignition plug side passage 4 in the intake ports 46A and 46B. The branch portion 46C of the intake ports 46A, 46B is connected to the injector 12
Has a surface substantially perpendicular to the injection direction of the fuel, and the fuel that has collided with this surface is diffused.

Next, (b) shows a type in which an injector 12 having two fuel injection holes is used. The flow of the two fuels injected from each fuel injection hole is determined by each of the intake ports 46A and 46B. Directly flows into the ignition plug side passage 4 of the fuel cell. In this case, the intake port 4
The branch portion 46C of 6A, 46B is formed in a curved surface shape to reduce the intake resistance of the intake flow.

As shown in (c), the fuel is directly injected into the ignition plug side passage 4 by using the injector 12 having one fuel injection hole so that the fuel does not adhere to the partition walls 21 and 21. A type that is designed to be used is also conceivable.
In this case, the branch portion 46C of the intake ports 46A and 46B is formed at an acute angle so that the fuel is smoothly taken in along with the intake.

(D) is of the type in which the fuel is actively injected toward the wide angle up to each of the partition walls 21 and 21, contrary to the above (c). In this case, the branch portion 46C of the intake ports 46A and 46B is rounded in a curved shape as in the above (b) in order to reduce the resistance. In this embodiment, any of the above-described injection variations is used.

The above (a) to (d) show the injection variations of the injector 12, and the arrangement position of the injector 12 and the injection axis 6 are all the same. Since the intake port structure of the internal combustion engine as one embodiment of the present invention is configured as described above, the intake air is mixed with the fuel injected by the injector 12, and is mixed with the intake ports 46A and 46B. After flowing into the combustion chamber 30 and being compressed and expanded (exploded) in the combustion chamber 30, it is discharged from each of the exhaust ports 47A and 47B to an exhaust passage (not shown).

In each of the intake ports 46A and 46B, the intake flow component in the tumble flow side half portions 46A-1 and 46B-1 is much larger than the intake flow component in the other half portions 46A-2 and 46B-2. Become a lot. And the tumble flow side half portions 46A-1, 46 of the intake ports 46A, 46B.
The intake flow component entering the combustion chamber 30 from B-1 is a component of a flow that forms a tumble flow, and the intake port 46A,
The combustion chamber 30 from the other half 46A-2, 46B-2 of 46B.
Since the intake flow component that enters the inside is a component that blocks the tumble flow, the intensity of the tumble flow is increased due to the flow rate imbalance described above. In particular, the intake ports 46A, 4
Since the overall flow path cross-sectional area of 6B is reduced, the tumble flow can be enhanced while the flow rate (flow velocity) of the intake flow in the entire intake port is kept constant.

At this time, at the time of intake, each intake port 4
In 6A and 46B, the partition 21 divides the intake air flow into an inner part and an outer part. The injector 12 injects fuel toward the inner passage 4 partitioned by the partition 21 of each of the intake ports 46A and 46B, so that the fuel flows through the central passage 4 partitioned by the partition 21 of the intake ports 46A and 46B. In this passage 4, fuel and air are mixed. On the other hand, only air is sent to the outer passage 5, and as shown in FIG. 1, a fuel-rich mixture layer Fm is formed in the vicinity of the ignition plug 11 at the center of the combustion chamber 30, and on both sides thereof. Forms an air layer Fa.

In particular, since the intake ports 46A, 46B and the partition 21 provided therein are arranged substantially in parallel, as shown in FIG. 5, the intake ports 46A, 46B
A layer Fm of the air-fuel mixture flowing into the combustion chamber 30 from the center side passage 4 of FIG. 1 and a layer Fa of air flowing into the combustion chamber 30 from the outer passage 5 partitioned by the partition 21 are separated even in the combustion chamber 30. And is layered.

As a result, an air-fuel mixture containing less fuel is sent to the entire combustion chamber 30, but a sufficient amount of fuel for ignition is sent to the vicinity of the ignition plug 11. As described above, since the fuel-fuel mixture flows near the ignition plug 11, the engine can be operated with a fuel mixture having a smaller amount than the stoichiometric air-fuel ratio without deteriorating the ignitability. is there.

In particular, as described above, the intake port 46
The partition wall 21 having a thickness substantially the same as or slightly smaller than the outer diameter of the valve stem 57 is disposed upstream of the intake valve 58 along the valve stem 57 in A and 46B.
The intake air flowing into the valve stem 57 is rectified so as not to be disturbed by the valve stem 57, and flows into the combustion chamber 30 smoothly and in a required direction.

In this embodiment, the upstream end 21A of the partition 21
Since both the downstream end 21B and the downstream end 21B are formed in a substantially cylindrical convex curved surface, the flow of the intake air toward the partition 21 and the flow of the intake air from the partition 21 to the valve stem 57 are more smoothly performed. Thus, the rectifying effect is enhanced. As a result,
The stratification of the intake air flow in the combustion chamber 30 is promoted, and the tumble flow is enhanced by promoting the stratification.

By providing the partition walls 21 at the intake ports 46A and 46B to promote stratification of the air-fuel mixture, the engine can be operated with a leaner air-fuel mixture as shown in the graph of FIG. it can. Here, the horizontal axis of the graph of FIG. 9 is the air-fuel ratio (A / F), and the vertical axis is the NOx emission amount and the Pi fluctuation rate (Pi = the indicated mean effective pressure). Lines a and c show the characteristics of the engine provided with the partition 21 at the intake port, and lines b and d show the characteristics of the engine provided with the normal tumble flow intake port without the partition 21. Is shown. Lines a and b relate to NOx emission, and lines c and d relate to the indicated mean effective pressure.

First, the line a and the line b show the relationship between the A / F and the NOx emission amount. As shown in this figure, in the engine provided with the partition 21 (see the line a), The NOx emission peaks on the lean (thinner) side of the A / F value as compared to the engine using the normal tumble flow (see line b). Further, the peak value of the NOx emission amount itself can be reduced. That is, since the stratification of the tumble flow in the combustion chamber 30 is promoted, the A / F at which the emission amount of NOx has a peak value moves to the lean side as compared with the conventional engine.

The lines c and d show the relationship between the A / F and the Pi fluctuation rate. Here, the Pi fluctuation rate is a measure for judging the combustion stability of the engine. If the Pi fluctuation rate is too high, combustion of the engine is not stabilized, and an uncomfortable operation state accompanied by torque fluctuation is caused. . In addition, the reference line e in the figure is a Pi fluctuation rate of the combustion stability limit that can be operated without any discomfort.

As shown in this figure, the engine provided with the partition 21 (see the line c) uses a normal tumble flow against the limit value of the Pi fluctuation rate at which a stable combustion state in the cylinder is obtained. A / on the leaner side than the institution (see line d)
The engine can be operated at F, and the emission of NOx at this time can also be significantly reduced. In other words, it shows that a stable combustion state can be obtained even with a leaner A / F, and the A / F at the combustion limit can be improved.

Therefore, this structure can realize an internal combustion engine that has extremely low fuel consumption and hardly emits NOx. Also, as shown in FIGS. 10 and 11, the upper half portions 46A-1 and 46B-1 of the substantially inverted triangular cross sections of the intake ports 46A and 46B are sufficiently large to secure a flow coefficient when the engine is fully opened. can do.

That is, FIG. 10 shows the relationship between the port cross-sectional area and the average tumble ratio and the average flow coefficient. Here, the line a shows the relationship between the port cross-sectional area and the average tumble ratio, and the line b shows the relationship between the port cross-sectional area and the average flow coefficient. In FIG. 9, the symbols □ indicate the average tumble ratio of the engine having the normal tumble flow intake ports, and the symbol ■ indicates the upper half 4 of the cross section of the intake ports 46A and 46B.
It shows the average tumble ratio of an engine having an intake port having a sufficiently large 6A-1 and 46B-1.

○ indicates the average flow coefficient of the engine provided with the normal tumble flow intake port.
Is the upper half 46A of the cross section of the intake ports 46A and 46B.
It shows the average flow coefficient of an engine having an intake port having a sufficiently large value of 1,46B-1. In the intake ports 46A and 46B of the present invention, the upper half 46A-
Since 1,46B-1 is made sufficiently large to secure the port cross-sectional area, both the average tumble ratio and the average flow coefficient can be improved as shown in the figure.

Thus, the relationship between the tumble ratio and the flow coefficient is as shown in FIG. FIG.
In the figure, the symbol “△” indicates an engine using a conventional tumble flow, the symbol “☆” indicates an engine in which the partition 21 is provided but the cross-sectional area in the intake ports 46A and 46B is reduced by the partition 21. An engine equipped with intake ports 46A, 4
The upper half portions 46A-1 and 46B-1 of the cross section of FIG. 6B are sufficiently enlarged.

In other words, as shown in FIG. 11, simply providing the partition 21 at the intake ports 46A and 46B will reduce the flow coefficient even if the stratification of the intake air flow is promoted, and it is considered that the full opening performance is reduced. Can be Here, as indicated by the ★ mark, the upper half 46A of the cross section of the intake ports 46A, 46B.
By making -1,46B-1 sufficiently large, the tumble ratio and the flow coefficient can be improved. Thus, the intake ports 46A, 4
It is possible to compensate for the decrease in the cross-sectional area of the engine 6B and to ensure the full opening performance of the engine.

FIG. 12 shows the rotational speed, the torque and the output of the engine. In the figure, lines a and c are graphs showing the characteristics of the engine having this structure, and lines b and d.
Is a graph showing characteristics of an engine having a conventional intake port structure. First, the lines a and b show the relationship between the rotational speed and the torque of the engine. There is almost no difference between the two curves, and the engine equipped with this structure is operated with a leaner mixture than before. This shows that torque equivalent to that of a conventional engine is realized.

Lines c and d show the relationship between the rotational speed of the engine and the output.
As with the torque characteristics described above, there is almost no difference between the two, indicating that the engine and the conventional engine can obtain an output even when operated with a leaner air-fuel mixture. Therefore, as shown in FIG. 12, the engine having this structure can increase the tumble ratio and the flow coefficient of the intake ports 46A and 46B so that the partition walls 21 and 21 are provided in the intake ports 46A and 46B. Thus, an internal combustion engine having the same torque and output characteristics as those of the other engines can be realized.

As described above, the partition walls 21, 21 are provided in the intake ports 46A, 46B, and the intake ports 46A, 46
Upper half portions 46A-1 and 46B of a substantially inverted triangular cross section of 6B
By making -1 sufficiently large, it is possible to maintain a stable combustion state with a mixture leaner than the conventional internal combustion engine without lowering the torque and the output as compared with the conventional internal combustion engine, and reduce NOx. be able to. At the same time, fuel efficiency can be improved.

Also, as in the modification shown in FIG. 6, the intake ports 46A and 46B are connected to the intake valve 5 from the branch portion 46C.
Even if it spreads in eight directions, since the partition wall 21 is disposed just above the center line 45A of the stream line 45 of the intake flow on the upstream side of the valve stem 57, the intake flow is
While flowing into the spark plug-side passage 4 and the anti-spark plug-side passage 5 while being rectified to 1, the flow into the combustion chamber 30 without being disturbed by the valve stem 57 and stratified. In this state, the formation of a tumble flow is promoted.

Further, as in the modification shown in FIG.
By making the thickness 1 thinner toward the upstream side of the valve stem 57, rectification of the intake air flow is further promoted, and the air flows into the combustion chamber 30 without being disturbed by the valve stem 57, and is stratified. In this state, the formation of the tumble flow is further promoted .

[0067]

[0068]

[0069] tail, the structure of the present invention may be any Saiyamizu type for the intake port, exhaust port 47 may be a single port type, not a Saiyamizu type. That is, this structure can be applied to a three-valve internal combustion engine having two intake valves and one exhaust valve in the same manner as described above.

The structure of the present invention can also be applied to an internal combustion engine that does not consider stratification or formation of a tumble flow. In this case, there is an effect that the intake efficiency can be improved.

[0071]

As described above in detail, according to the intake port structure of the internal combustion engine according to the first aspect of the present invention, the internal combustion engine is divided into two parts having two combustion chamber openings which are respectively opened and closed by two intake valves. Equipped with an intake port
The intake air flow from the heat
In the internal combustion engine configured as described above ,
In the flow direction while rectifying the intake air flow, at a position along a streamline including the ignition means disposed in the central portion and the valve stem upstream of the intake valve stem in each of the above intake port portions, Are respectively arranged so as to bisect along the
A center side passage on the ignition means side and the center side passage in the intake port.
A rectifying member that is divided into side passages on both sides of the road;
The simple structure of Ru and a fuel injection means for injecting fuel into passages, can improve intake efficiency becomes smoothly performed so the flow of the intake air flow into the combustion chamber, engine high negative
It is advantageous for securing output during loading, and performs stratified combustion
In this case, there is an advantage that it can greatly contribute to promoting stratification and strengthening the tumble flow. Therefore, a mixture layer with a high fuel concentration
Is collected near the ignition means, and the fuel concentration
By forming a thin air-fuel mixture layer, fuel dilution is
Ignition and stable flammability while maintaining a low air-fuel ratio
Ensures proper stratified combustion, and
Promote fuel economy savings while ensuring
To improve fuel efficiency at low load.
You. In particular, the central passage and the
Since the cross-sectional area of the side passage is configured to be constant, the engine
Regardless of the state, whether the intake flow from the central passage and the side passage
And the intake air flow always separates into layers to form a tumble flow
To ensure proper stratified combustion at all times.
Therefore, for example, stratified combustion is performed at low engine load.
This enables stable combustion while suppressing fuel consumption
become.

The rectifying member is constituted by a partition wall, and the thickness of the partition wall at the end near the stem is substantially equal to or larger than the diameter of the valve stem. When set to be slightly larger, resistance reduction at the valve stem 57 is promoted, and the effect of promoting stratification and the effect of strengthening the tumble flow are great. Further, as described in claim 3, the rectifying member is constituted by a partition, and the thickness of the partition at the end near the stem is substantially equal to or slightly smaller than the diameter of the valve stem. With such a setting, the flow coefficient is secured, and while the maximum output of the engine is sufficiently secured, a certain effect can be obtained with respect to promotion of stratification and enhancement of the tumble flow.

Further, by constituting the partition wall such that the thickness of the partition wall becomes thinner toward the upstream end portion, the reduction of the resistance at the valve stem 57 is promoted and the layered structure is formed. The effect of promoting the liquefaction and the effect of strengthening the tumble flow are great .

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an intake port structure of an internal combustion engine as one embodiment of the present invention.

FIG. 2 is a schematic top view showing a configuration of a main part of an intake port structure of the internal combustion engine as one embodiment of the present invention, and is a view taken in the direction of arrow A in FIG.

FIG. 3 is a schematic partial cross-sectional view showing a configuration of an intake port structure of the internal combustion engine as one embodiment of the present invention, and is a CC cross-sectional view in FIG.

4 is a schematic partial sectional view showing the configuration of an intake port structure of an internal combustion engine as one embodiment of the present invention, and is a sectional view taken along line BB in FIG.

FIG. 5 is a schematic diagram showing a configuration of an intake port structure of an internal combustion engine as one embodiment of the present invention.

FIG. 6 is a schematic diagram showing a configuration of an intake port structure of an internal combustion engine as one embodiment of the present invention, and is a schematic diagram showing an arrangement state of intake ports, and FIG. FIG. 3B is a schematic configuration diagram viewed from the side of the cylinder, FIG. 3C is a schematic configuration diagram viewed from the side of the cylinder, and FIG.

FIG. 7 is a schematic view showing a modified example of the partition wall of the intake port structure of the internal combustion engine as one embodiment of the present invention, and is a view corresponding to FIG.

FIG. 8 is a schematic diagram showing variations of a fuel injection method in an intake port structure of an internal combustion engine as one embodiment of the present invention.

FIG. 9 is a graph showing an operation of an intake port structure of an internal combustion engine as one embodiment of the present invention.

FIG. 10 is a graph showing an operation of an intake port structure of an internal combustion engine as one embodiment of the present invention.

FIG. 11 is a graph showing an operation of an intake port structure of an internal combustion engine as one embodiment of the present invention.

FIG. 12 is a graph showing an operation of an intake port structure of an internal combustion engine as one embodiment of the present invention.

FIG. 13 shows the effect of a tumble flow in a conventional internal combustion engine.
It is a graph which shows a result.

FIG. 14 is a schematic longitudinal sectional view showing a conventional intake port structure of an internal combustion engine together with around a combustion chamber.

FIG. 15 is a schematic perspective view showing a conventional intake port structure of an internal combustion engine together with around a combustion chamber.

FIG. 16 is a schematic cross-sectional view of a surface of the conventional intake port structure of an internal combustion engine which is perpendicular to the flow direction of intake air (D-D in FIG. 14).
FIG.

FIG. 17 is a cross-sectional view (a view corresponding to a cross section taken along the line DD in FIG. 14) showing another example of a schematic cross section of a surface of the conventional intake port structure of the conventional internal combustion engine, which is perpendicular to the flow direction of the intake air. is there.

FIG. 18 is a schematic longitudinal sectional view showing another example of the conventional intake port structure of the internal combustion engine .

[Explanation of symbols]

1A, 1B intake port axial line 2 intake valve axis 3 intake port reference plane 4 reference surface side of the center-side passage reference plane outer (anti-spark plug side) as (spark plug side) passage 5 side passage passage 6 injector Injection axis 7 Lower wall surface of intake port 8 Upper wall surface of intake port 9 Surface in row direction when a plurality of cylinders are arranged in a line 11 Spark plug as ignition means 12 Injector as fuel injection means 13 Intake port hatched portion 21 Rectification downstream end 2 2 a cylinder block 24 bore of the upstream end 21B bulkhead partition walls 21A partition wall as member 25 the cylinder 26 a piston 28 the cylinder head 30 combustion chamber 34 pent roof 35 recess 37 inclined surface 39 raised portions 40 ', 42' intake passage 4 6 intake Port 45 Streamline of intake flow 45A Center of streamline of intake flow 46A, 46B Port portion 46A-1, 46B-1 Upper half of intake port 46A-2, 46B-2 Lower half of intake port 46C Port partition or port branch 47, 47A, 47B Exhaust port 56 Valve head 57 Stem Portion (valve stem) 58 Intake valve 59 Exhaust valve 60 Exhaust passage Fa Tumble flow of air Fm Tumble flow of air-fuel mixture F1 Flow center in intake port L Straight line

Claims (4)

(57) [Claims] An intake port divided into two parts having two combustion chamber openings respectively opened and closed by two intake valves, and an intake flow from each intake port is provided .
In an internal combustion engine configured to form a tumble flow in a combustion chamber, an ignition means provided at a central portion of a top portion of the combustion chamber, and an ignition valve upstream of a stem of an intake valve in each of the intake port portions. the position along the streamlines including a valve stem, so that bisects along the flow direction while rectifying the air flow Niso
Respectively, and the inside of the intake port portion is provided on the ignition means side.
It is divided into a central passage and side passages on both sides of the central passage.
That a rectifying member, and a fuel injection means for injecting fuel into the central side passage Personalization
In addition, the central passage and the side passage of the intake port are all operated by the engine.
An intake port structure for an internal combustion engine, wherein a cross-sectional area of a passage is not changed over a rolling state . 2. The rectifying member is constituted by a partition,
The thickness of the partition at the end near the valve stem is
2. The intake port structure for an internal combustion engine according to claim 1, wherein the diameter is set substantially equal to or slightly larger than the diameter of the valve stem. 3. The rectifying member is constituted by a partition,
The thickness of the partition at the end near the valve stem is
2. The intake port structure for an internal combustion engine according to claim 1, wherein the diameter is set substantially equal to or slightly smaller than the diameter of the valve stem. 4. The intake port structure for an internal combustion engine according to claim 1, wherein the thickness of the partition wall becomes thinner toward the upstream end .