JPH05321678A - Intake port structure for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an intake port structure of an internal combustion engine, and an object thereof is to promote stratification of a tumble flow in a cylinder so that a stable lean combustion state can be maintained. .. [Structure] An intake port 46 having two combustion chamber openings opened and closed by two intake valves 58, 58 is provided, and an intake flow from the intake port 46 becomes a tumble flow in the combustion chamber 30. In the internal combustion engine, the combustion chamber 30
Ignition means 11 arranged in the central portion of the top portion, two partition walls 21, 21 partitioning the inside of the intake port 46 into a central passage 4 and side passages 5 on both sides thereof along the intake streamline direction,
The fuel injection means 12 is disposed on the upper surface of the intake port 46 or in the vicinity thereof and injects fuel toward the lower side of the central passage 4.
And are provided to configure.

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 of an internal combustion engine, and in particular, an intake flow from an intake port having a combustion chamber opening opened and closed by two intake valves is stratified in the combustion chamber. The present invention relates to an intake port structure of an internal combustion engine configured so as to have a fixed tumble flow.

[0002]

2. Description of the Related Art In recent years, in order to increase the intake passage area of a combustion chamber of an engine without increasing the size of an intake valve, an internal combustion engine provided with two intake port passages in one combustion chamber has come to be used. ing. In such an internal combustion engine, 2
One intake port passage is formed by branching from one intake port, and the air-fuel mixture flows into the combustion chamber from each of these two intake port passages (hereinafter, such an internal combustion engine will be referred to as two intake air passages). Port-type internal combustion engine).

Further, as means for improving the combustion of the internal combustion engine, in the intake stroke, a so-called tumble flow F (F), which is a vertical swirling flow in the cylinder as shown in FIGS.
It is effective to generate a, Fm). For example, FIGS. 22 and 23 show the structure of one cylinder of a two-intake-port internal combustion engine that generates such tumble flows Fa and Fm. In the drawings, reference numeral 22 is a cylinder block, 24 is a cylinder bore, and 26 is a cylinder bore. 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 of the combustion chamber 30.
Reference numerals 0'and 42 'denote intake port passage portions (hereinafter referred to as intake port portions) that are provided in each cylinder by branching from the intake port 44'.
Each intake valve 58 is installed.

The pent roof 34 includes the intake port portions 4
The intake flow from 0 ', 42' is supplied to each intake passage 40 ', 4'.
2'is provided with an inclined surface which can be guided downward along the inner wall surface of the cylinder bore 24 on the extension axis, and the intake air flow from the intake port portions 40 ', 42' is supplied to the pent roof 34 '.
With the help of the guides, the heads proceed in the tumble flow directions indicated by arrows Fa and Fm, respectively.

Further, in order to promote the tumble flow, the shape of the intake port 44 'is important, and in general, as shown in FIG.
2, the intake port 44 'is formed as a straight straight port as shown in FIG. 23, or the intake port 44' is throttled as shown in FIG. 26 so as to rectify the flow. .. 22 and 26, reference numerals 40F and 42F represent normal intake ports that are not straight ports.

The cross-sectional shape of the intake port 44 'is generally formed in a circular shape as shown in FIG. 24. However, in addition to being formed in an elliptical shape or an oval shape as shown in FIG. It may be formed in. Also, in this example,
As shown in FIG. 23, the injector 12 is provided only in one of the intake passages 42 ′, and the spark plug 11 is arranged in the vicinity of the intake valve 58 of the intake passage 42 ′ equipped with this injector 12. Therefore, this spark plug 11
A mixture of fuel injected from the injector 12 and intake air flows into the combustion chamber 30 through the intake passage 42 ′ and the intake port 44 ′ in the vicinity of the above, and a tumble flow Fm of this mixture is formed. .. Further, only the air is supplied from the intake port 44 'of the intake port portion 40' to the combustion chamber 3
0, a tumble flow Fa of this air is formed.

As a result, a stratified tumble flow of the tumble flow Fm of the air-fuel mixture and the tumble flow Fa of air is formed in the combustion chamber 30. The tumble flow (tumble swirl) thus generated is effective in increasing the flame propagation speed and combustion stability, and when the experimental data on the heat generation amount Q, the in-cylinder pressure P, and the heat generation rate dQ is shown, for example, FIG. 27
The heat generation amount Q, the in-cylinder pressure P, and the heat generation rate dQ of the tumble swirl (when the tumble flow is generated) are higher than those of the standard (a general case where the tumble flow is not particularly generated). It can be seen that the cycle fluctuation is small and the combustion stability is good.

Therefore, the engine can be operated in a stable state even when the fuel concentration of the air-fuel mixture is low, that is, during so-called lean combustion. In the figure, reference numeral 47 is an exhaust port communicating with the exhaust passage 60, and 59 is an exhaust valve.

[0009]

By the way, in the two-intake-port internal combustion engine in which such tumble flows Fa and Fm are generated, the spark plug 11 is equidistant from the centers of the two intake valves 58 and 58. When located (for example, the central portion of the top of the combustion chamber), a tumble flow having a rich air-fuel mixture is formed in the combustion chamber 30 near the spark plug 11 (that is, near the center of the combustion chamber 30) to stratify the intake air. Need to be converted. Also, by stratifying the intake air flow in this manner, it is desired to rectify the intake air flow and promote the formation of the tumble flow. However, if the two intake port portions 40 ', 42' are arranged in parallel, it is difficult to stratify the air-fuel mixture sucked from both the intake valves 58, 58, and the engine is not burned during lean combustion. However, there is a problem that the combustion state cannot be kept stable.

The present invention was devised in view of the above-mentioned problems, and promotes stratification of the tumble flow of the intake air in the cylinder and increases the air-fuel ratio of the tumble flow on the ignition means side of the combustion chamber. An object of the present invention is to provide an intake port structure for an internal combustion engine in which the air-fuel ratio of the tumble flows on both sides is made thin so that a stable lean combustion state can be maintained even with a mixture of fuel in an amount smaller than the theoretical air-fuel ratio. ..

[0011]

Therefore, an intake port structure for an internal combustion engine according to the present invention according to claim 1 has an intake port having two combustion chamber openings which are opened and closed by two intake valves, respectively. In an internal combustion engine configured such that an intake air flow from the intake port becomes a tumble flow in a combustion chamber, an ignition means disposed in a central portion of the combustion chamber top and an inner wall on a lower surface side in the intake port. 2 extending in the direction of the intake streamline to divide the inside of the intake port into a central passage on the ignition means side and side passages on both sides thereof.
Two partition walls and a fuel injection unit that is disposed on the upper surface of the intake port or in the vicinity thereof and injects fuel toward the lower side of the central passage in the intake port are provided.

The intake port structure for an internal combustion engine according to a second aspect of the present invention is the same as the structure according to the first aspect.
It is characterized in that the partition wall is extended from the lower surface side inner wall of the intake port to reach the upper surface side inner wall. In addition, in the intake port structure for an internal combustion engine according to a third aspect of the present invention, in addition to the configuration according to the first aspect, a space is provided between the partition wall and the inner wall of the intake port upper surface side. It has a feature.

[0013]

In the intake port structure for an internal combustion engine according to the present invention as set forth in claim 1, intake air is sent into the combustion chamber from an intake port having two combustion chamber openings opened and closed by two intake valves, and tumbles. A stream is formed. At this time, in the intake port, the partition wall divides the internal intake air into the central passage on the ignition means side and the lateral passages on both sides thereof. Also,
The fuel is injected downward from the upper surface side of the central passage by the fuel injection means and mixed with the intake flow.

Since only the air-fuel mixture flows into the center side passage and only the air flows into the side passage due to the partition wall, the intake air flowing into the combustion chamber has a relatively high fuel concentration. And a tumble flow of air are formed on both sides of the tumble flow. In such a structure, the combustion state is reliably stabilized by forming a tumble flow of a relatively rich mixture on the side of the ignition means, while forming a lean mixture in the combustion chamber as a whole.

Further, as in the intake port structure for an internal combustion engine according to the second aspect of the present invention, even when the partition wall is formed from the inner wall on the lower surface side to the inner wall on the upper surface side of the intake port, The layer and the air layer are completely separated and flow into the combustion chamber. Further, as described above, since the fuel is injected from the upper surface side of the intake port toward the lower side of the intake port, as in the intake port structure of the internal combustion engine according to the present invention as set forth in claim 3, the partition wall and the intake Even when a space is provided between the upper surface of the port and the upper surface of the port, the partition wall stratifies the tumble flow of the mixture layer and the air layer in the combustion chamber.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 6 show an intake port structure of an internal combustion engine as a first embodiment of the present invention, and FIG. 2 is a schematic top view showing the structure thereof and is a view taken in the direction of arrow A in FIG. 1, and FIG. 3 is a schematic partial cross-sectional view showing the structure thereof, which is CC in FIG. Sectional drawing, FIG. 4 is a schematic partial sectional view showing the structure thereof, and is a sectional view taken along the line BB in FIG. 3, FIG. 5 is a schematic view showing its action, and FIGS. 7 to 10 are schematic diagrams showing variations of the injection method, and graphs for explaining the action and effect, respectively.

As shown in FIG. 1, in each cylinder of the internal combustion engine having the intake port structure of the first embodiment, a cylinder bore 24 formed in a cylinder block 22 and a piston 2 are provided.
6 and the cylinder head 28 are encircled and bent to form a combustion chamber 30, and the intake port 46 is provided in the combustion chamber 30.
Has been led. The intake port 46 is a Siamese port divided into two intake port portions 46A and 46B by a port partition wall (intake port branch portion) 46C on the way.
An intake valve 58 is installed at each combustion chamber opening of 6B. The exhaust port 47 is also a siamese port, and the two exhaust ports 47A and 47B are also introduced into the combustion chamber 30, and exhaust valves (not shown) are installed in each.

Each intake port portion (hereinafter, this intake port portion is also simply referred to as an intake port) 46A,
46B is communicatively connected to an intake passage (intake manifold) not shown. In addition, reference numerals 1A and 1B in the figure indicate the respective axial center lines of the intake ports 46A and 46B. Also, the exhaust ports 47A and 47B merge at the downstream side,
It is also connected to the common exhaust passage 47.

An injector 12 as fuel injection means, which will be described later, is attached to the intake ports 46A and 46B in the vicinity of the branch portion 46C.
Thus, the fuel is injected into the intake ports 46A and 46B. Further, in this embodiment, in the downstream side from the vicinity of the branch portion 46C of the intake ports 46A and 46B,
The intake ports 46A and 46B are formed in parallel with each other. As a result, the intake air from the intake ports 46A and 46B flows into the combustion chamber 30 in parallel with each other.

Further, the axial center lines 1A and 1B of the intake ports 46A and 46B are two straight lines which are parallel to each other as shown in FIGS. 2, 3 and 5. That is, the intake ports 46A and 46B are formed as straight straight ports that are parallel to each other. Furthermore, the cross-sectional shape of this straight port is, as shown in FIG.
A half portion of A, 46B on the tumble flow side (that is, an upper half portion of the intake ports 46A, 46B through which the main component flow forming the tumble flow flows) 46A-1, 46B-1 blocks the other half portion (that is, the tumble flow). Intake port 4 through which such a component flow flows
6A, 46B lower half portions) 46A-2, 46B-2 are wider, and the intake flow center F1 of the intake ports 46A, 46B is on the tumble flow side (that is, the intake ports 46A, 46B).
It is eccentric to the upper half of B (46A-1, 46B-1). As a result, the intake flow from the intake ports 46A and 46B easily forms a tumble flow in the combustion chamber 30. In this first embodiment, the intake ports 46A, 46
B is formed to have a cross section of a substantially inverted triangle as shown in FIG.

Further, as shown in FIG.
A recess 35 is formed on the top surface of the so as to secure a space between the cylinder head 28 and the piston 26 when the piston 26 reaches the top dead center. And piston 2
The top surface of 6 is also provided with a raised portion 39, which is raised more than the recess 35, close to the recess 35. This ridge 3
9 is a slope 3 formed between the raised portion 39 and the recess 35.
7 connects gently to the recess 35.

The recess 35 is formed below an exhaust valve (not shown), and the raised portion 39 has intake valves 58, 5
It is formed below 8. Therefore, as shown in FIG. 1, the tumble flow side half portion 4 of the intake ports 46A and 46B.
6A-1, 46B-1 intake air flows Fa, Fm
Is designed to reach the ridge 39 from the recess 35 through the slope 37, thereby promoting the formation of the tumble flow.

Further, as shown in FIGS. 1 and 5, a spark plug 11 as an ignition means is arranged in the central portion of the upper portion of the combustion chamber 30 and the intake ports 46A, 4 are provided.
It is located on the reference plane 3 between 6B. The reference plane 3 is a virtual plane located at the center of both intake ports 46A and 46B. By the way, as shown in FIGS. 1 to 3 and 5, partition walls 21 are provided in the intake ports 46A and 46B so as to divide the intake ports 46A and 46B into left and right directions, respectively. In each of the intake ports 46A, 46B, a passage 4 on the reference surface 3 side of the intake flow (a central passage on the spark plug side) and a passage outside the reference surface 3 (side passages on both sides of the central passage). 5 is divided into two parts along the flow direction of intake air.

As shown in FIGS. 2 and 3, the partition wall 21 is formed substantially vertically along the axial center lines 1A and 1B of the intake ports 46A and 46B, and from the vicinity of the position where the injector 12 is disposed. It is extended over the downstream side. Also,
These partition walls 21 and 21 are arranged substantially parallel to each other, and the intake valve 5 is provided downstream of the intake ports 46A and 46B.
8 extends along the axis 2 of the intake valve 58 to the vicinity of the stem portion 57 and the umbrella portion 56 of the intake valve 58. In addition, the partition wall 21 does not come into contact with the umbrella portion 56 and the stem portion 57 of the intake valve 58,
They are formed so as to secure an appropriate clearance with them, and have no influence on the operation of the intake valve 58.

In the first embodiment, the partition wall 21 is formed from the inner wall 8 on the upper surface side to the inner wall 7 on the lower surface side of the intake ports 46A, 46B.
The inside of 6B is divided into a central passage 4 and a side passage 5. As a result, the intake ports 46A, 46B
The flow that has branched into the central passage 4 and the lateral passage 5 inside flows into the combustion chamber 30 while being separated from each other while being rectified by the partition wall 21. Therefore, due to the partition wall 21 as described above, when the flow of the intake air flows into the combustion chamber 30, as shown in FIG. 5, the layer Fm of the air-fuel mixture in which the fuel is mixed with the air and the layer F of the air only are mixed.
a, Fa (three flows of the central passage 4 and the lateral passages 5 on both sides thereof) are separated, that is, they are formed into a tumble flow in a stratified state. There is. Therefore, the present internal combustion engine is configured as a layered combustion internal combustion engine.

Further, in the intake ports 46A and 46B,
Since the sectional areas of the intake ports 46A and 46B are reduced by the sectional integration of the partition wall 21, it is conceivable that the flow coefficient of the intake ports 46A and 46B is reduced and the engine full-open performance is reduced. Therefore, the intake ports 46A, 46B
As shown by the hatched portion 13 in FIGS. 2 and 4, the upper half portions 46A-1 and 46B-1 of the cross section of the substantially inverted triangle are made sufficiently large to cancel this cross-section integration, and the engine is fully opened. It is designed to secure the flow coefficient at the time.

Further, as described above, it is desirable that the partition wall 21 has its sectional area as small as possible in order to secure the flow coefficient, and therefore the partition wall 21 is formed so as to be as thin as possible. In this embodiment, as shown in FIG. 2, is the thickness of the partition wall 21 equal to the diameter of the valve stem 57?
Or, it is a little thinner than this. As a result, while ensuring the intake flow rate of the intake port 46, the valve stem 5
It is possible to reduce the intake resistance due to 7, and the intake air smoothly flows into the combustion chamber 30.

In FIG. 5, a modified example of the partition wall 21 is shown. In this way, the partition wall 21 is formed as thin as possible on the upstream side of the valve stem 57 and gradually becomes closer to the valve stem 57. The valve stem 57 may be formed to have a thickness substantially equal to the diameter of the valve stem 57.
As a result, the flow of the intake air flow in the vicinity of the valve stem 57 can be further adjusted.

In the modification shown in FIG. 5, the partition wall 2
Although the upstream end of 1 is formed in the middle of the intake port 46, this partition wall 21 divides the air-fuel mixture into air into the central passage 4 and the lateral passage 5 to remove the fuel injected from the injector 12. It suffices if diffusion to the side passages 5 can be prevented, and the partition walls 2
As shown in FIG. 5, the upstream end of 1 does not necessarily have to extend to the upstream end of the intake port 46.

By the way, as shown in FIGS. 1 and 5, the injector 12 as the above-mentioned fuel injection means is disposed in the upper part of the two intake ports 46A, 46B near the branch portion 46C. Further, the injector 12 is a reference plane (center plane) of the intake flow between the two intake ports 46A and 46B.
The intake ports 46A and 46B are arranged along
The fuel is to be injected toward the lower surface of the downstream side. Reference numeral 6 in FIGS. 2, 3 and 5 is an injector injection axis line, which indicates the injection direction of the injector 12.

That is, as shown by the injector injection axis 6, the injector 12 has the intake ports 46A, 4A.
The fuel is injected from the upper side between 6B toward the lower downstream side of the intake ports 46A and 46B. Then, the fuel injected below this intake port 46A,
The partition walls 21 and 21 provided in 46B allow the intake air to be taken into the combustion chamber 30 through the center side passage 4 in the intake ports 46A and 46B, and the side passages 5 on both sides on the spark plug side. , Only air flows.

As the injection variation of the injector 12, the types shown in FIGS. 6 (a) to 6 (d) can be considered. (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 diffused fuel is made to flow into the central passage 4 in the intake ports 46A and 46B. The branch portion 4 of the intake ports 46A and 46B
6C has a surface that is substantially orthogonal to the injection direction of the injector 12, and diffuses fuel that has collided with this surface.

Next, (b) is of a type that uses an injector 12 having two fuel injection holes, and the two fuel flows injected from the respective fuel injection holes are respectively the intake ports 46A and 46B. It directly flows into the central side passage 4. In this case, the intake port 46A,
The branch portion 46C of 46B is formed into a curved surface to reduce the suction resistance of the suction flow.

Further, as shown in (c), the injector 12 having a single fuel injection hole is used to inject fuel directly into the central passage 4 so that fuel does not adhere to the partition walls 21 and 21. It is also possible to use a type that does this. In this case, the branch portions 46C of the intake ports 46A and 46B are formed in an acute angle so that the fuel is smoothly taken in with the intake air.

Contrary to (c) described above, (d) is a type in which fuel is positively injected toward the wide angle up to the respective partition walls 21 and 21. In this case, the branch portions 46C of the intake ports 46A and 46B are rounded in a curved shape in the same manner as (b) above in order to reduce resistance. Then, in this embodiment, any of the injection variations described above is used.

The above-mentioned (a) to (d) show injection variations of the injector 12, and the disposition position of the injector 12 and the injection axis 6 are the same. Since the intake port structure of the internal combustion engine as the first embodiment of the present invention is configured as described above, the intake air is mixed with the fuel injected by the injector 12 and the intake ports 46A, 46B are mixed. Flows into the combustion chamber 30, is compressed and expanded (explosed) in the combustion chamber 30, and is then discharged from the exhaust ports 47A and 47B.

In each of the intake ports 46A and 46B, the intake flow component from the tumble flow side half portions 46A-1 and 46B-1 is more than the intake flow component from the other half portions 46A-2 and 46B-2. Becomes significantly stronger. That is, the intake port 4
6A, 46B tumble flow side half portions 46A-1, 46B-
The intake flow component from 1 is the component of the flow forming the tumble flow, and the other half part 46A- of the intake ports 46A, 46B.
Since the intake flow component from 2, 46B-2 is a component that blocks the tumble flow, the above flow rate imbalance does not reduce the overall flow passage cross-sectional area of the intake ports 46A, 46B,
That is, the strength of the tumble flow can be increased while keeping the flow rate (flow velocity) of the intake flow in the entire intake port constant.

At this time, at the time of intake, the intake port 46
Only air is sent to the outside passage 5 partitioned by the partition walls 21 of A and 46B, while fuel is supplied to the intake ports 46A and 4B.
Since it is sent only to the passage 4 on the central side partitioned by the partition wall 21 of 6B, the fuel and air are stratified, and as shown in FIG. 1, the spark plug 11 is provided with a layer Fm of a rich fuel mixture. An air layer Fa is formed on both sides of the air layer.

This is because the intake ports 46A, 46B and the partition walls 21 provided therein are arranged substantially parallel to each other, so that the intake ports 46A, 46, as shown in FIG.
Also in the combustion chamber 30, the layer Fm of the air-fuel mixture flowing into the combustion chamber 30 from the central passage 4 of B and the layer Fa of the air flowing into the combustion chamber 30 from the side passage 5 partitioned by the partition wall 21 are separated. ， It is layered.

As a result, even if the air-fuel mixture containing less fuel is sent to the entire combustion chamber 30, a sufficient amount of fuel for ignition is sent to the vicinity of the spark plug 11. Then, since the air-fuel mixture in which the fuel is mixed flows near the ignition plug 11, the engine can be operated with the air-fuel mixture in an amount smaller than the stoichiometric air-fuel ratio without deteriorating the ignitability. Also,
By promoting stratification of the intake flow in this manner, the formation of the tumble flow in the combustion chamber 30 is also strengthened. That is, the intake air flow is branched into the central passage 4 and the side passages 5 of the intake ports 46A and 46B, and the branched intake air flows into the combustion chamber 30 while maintaining the parallel state.
The intake flow is rectified and the tumble flow is easily formed.

Further, as shown in the graph of FIG. 7, by providing 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. Here, the horizontal axis of the graph of FIG. 7 is the air-fuel ratio (A / F), and the vertical axis is the NOx emission amount and Pi (illustrated average effective pressure) fluctuation rate. Further, the line a and the line c are
The characteristic of the engine in which the partition wall 21 is provided in the intake port is shown and the line b
And the line d show the characteristics of an engine having a normal tumble flow intake port without the partition wall 21. Lines a and b relate to NOx emission, and lines c and d relate to Pi fluctuation rate.

First, the lines a and b show the relationship between the A / F and the NOx emission amount, but as shown in this figure, in the engine provided with the partition wall 21 (see the line a). The NOx emission peaks on the lean (thin) side where the A / F value is leaner than in the engine using the normal tumble flow (see line b). Lines c and d show the relationship between A / F and Pi fluctuation rate. Here, the Pi fluctuation rate serves as a guide for judging the combustion stability of the engine. If the Pi fluctuation rate is too low, the combustion of the engine is not stable, and an uncomfortable operating state accompanied by torque fluctuations occurs. .. The reference line e in the figure is the Pi fluctuation rate of the combustion stability limit that can generally be operated without discomfort.

As shown in this figure, in the engine provided with the partition wall 21 (see line c), the normal tumble flow is used for 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 existing engine (see line d)
The engine can be operated at F, and the NOx emission amount at this time can be significantly reduced. That is, it is shown 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, with this structure, it is possible to realize an engine which has extremely low fuel consumption and emits almost no NOx. Further, as shown in FIGS. 8 and 9, by sufficiently increasing the upper half portions 46A-1 and 46B-1 of the substantially inverted triangular cross section of the intake ports 46A and 46B, the flow coefficient at the time of fully opening the engine is secured. can do.

That is, FIG. 8 shows the relationship between the port cross-sectional area and the average tumble ratio and 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. Further, in FIG. 8, □ indicates the average flow coefficient of an engine having a normal tumble flow intake port, and ■ indicates an upper half portion 46A-1, 46B- of the cross section of the intake ports 46A, 46B. 1 shows the average flow coefficient of an engine having an intake port of which 1 is sufficiently large.

∘ indicates the average tumble ratio of an engine equipped with a normal tumble flow intake port,
● indicates the upper half 46A of the intake port 46A, 46B cross section
It shows the average tumble ratio of an engine having an intake port in which -1,46B-1 is sufficiently large. Then, in the intake ports 46A and 46B of the present invention, the upper half portion 46A
As shown in the figure, both the average tumble ratio and the average flow coefficient can be improved by sufficiently increasing -1, 46B-1 to secure the port cross-sectional area.

As a result, the relationship between the tumble ratio and the flow coefficient becomes as shown in FIG. Further, in FIG. 9, the symbol Δ indicates an engine using a conventional tumble flow, and the symbol ∘ indicates a partition wall 21, but this partition wall 21 allows the intake port 4 to be installed.
6A, 46B, the cross-sectional area of the engine is reduced, ★ indicates the engine with this structure and intake ports 46A, 46B
The upper half portions 46A-1 and 46B-1 of the cross section are sufficiently large.

That is, as shown in FIG. 9, if the partition wall 21 is provided only in the intake ports 46A and 46B, the flow coefficient will be reduced even if the stratification of the intake flow is promoted, and the full-open performance may be degraded. Be done. Here, as shown by *
Upper half portion 46A- of the cross section of the intake ports 46A and 46B
By making 1,46B-1 sufficiently large, the tumble ratio and the flow coefficient can be improved. Therefore, by providing the partition wall 21, the intake ports 46A, 4
The reduction in the cross-sectional area of 6B can be compensated for, and the fully open performance of the engine can be secured.

FIG. 10 shows the rotational speed, torque and 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.
FIG. 4 is a graph showing the characteristics of an engine having a conventional intake port structure. First, lines a and b show the relationship between the rotational speed and torque of the engine, but there is almost no difference between these two curves, and the engine with this structure operates with a leaner mixture than before. However, it shows that the torque equivalent to that of the conventional engine is realized.

The lines c and d show the relationship between the engine speed and the output. These lines c and d are used.
Similar to the above-mentioned torque characteristics, there is almost no difference in the above and, and it is shown that the output can be obtained with the conventional engine even if the air-fuel mixture is operated leaner than the conventional one. Therefore, as shown in FIG. 10, in the engine having the present structure, even if the partition walls 21 and 21 are provided in the intake ports 46A and 46B by increasing the tumble ratio and the flow coefficient of the intake ports 46A and 46B, It is possible to realize an internal combustion engine with torque and output characteristics equivalent to those of the engine.

As described above, the partition walls 21 and 21 are provided at the intake ports 46A and 46B, and the intake ports 46A and 4B are provided.
Upper half part 46A-1, 46B of the cross section of the substantially inverted triangle of 6B
By making -1 sufficiently large, it is possible to maintain a stable combustion state with a leaner air-fuel mixture than the conventional internal combustion engine without lowering both torque and output compared with the conventional internal combustion engine, and reduce NOx. be able to. At the same time, fuel efficiency can be improved.

Further, as shown in FIG. 3, by forming the downstream end of the partition wall 21 on the upstream side of the axis 2 of the intake valve 58, the manufacturing process can be simplified and the manufacturing cost can be reduced. It can be suppressed low. The first embodiment can be similarly applied to a three-valve internal combustion engine having two intake ports 46A and 46B and one exhaust port 47.

Next, an intake port structure for an internal combustion engine as a second embodiment of the present invention will be described. FIG. 11 is a schematic partial sectional view showing the structure thereof, which is shown in FIG. 3 in the first embodiment (FIG. 2). FIG. 9 is a view corresponding to a C-C cross-sectional view in FIG. The second embodiment is different only in the shape of the partition wall 21 in the first embodiment described above, and the other structure is the same as that of the first embodiment described above.

In this second embodiment, as shown in FIG. 11, the partition wall 21A is formed from the upper inner wall 8 to the lower inner wall 7 of the intake ports 46A and 46B.
Particularly, the partition wall 21B is also provided at the tip of the stem portion 57 of the intake valve 58 in the intake ports 46A and 46B. As a result, the central passage 4 and the lateral passage 5 are completely separated. Further, the valve stem 57 of the intake valve 58 is provided so as to vertically penetrate the partition walls 21A and 21B.

As a result, the flow of the intake flow branched into the central passage 4 and the lateral passage 5 in the intake ports 46A and 46B is completely separated until it flows from the intake valve 58 into the combustion chamber 30. Is designed to keep. Due to such partition walls 21A and 21B, this flow is generated in the combustion chamber 3
Even after flowing into 0, the mixture layer Fm and the air layers Fa and F
a and three layers (central side passage 4 and side passages 5 on both sides thereof)
It is possible to maintain a separated state, that is, a layered state. Therefore, the present internal combustion engine is configured as a layered combustion internal combustion engine.

Since the intake port structure for the internal combustion engine as the second embodiment of the present invention is constructed as described above, it is possible to obtain the same effects as in the first embodiment described above, and in addition, Layering can be further promoted. That is,
With a simple structure in which the partition wall 21B is added to the tip of the stem portion 57 of the intake valve 58 along the extension line of the partition wall 21A, the intake air flow branched in the intake ports 46A and 46B is completely separated, and the combustion chamber is separated. Within 30, stratification of the air-fuel mixture can be realized more reliably. Thus, the lean air-fuel mixture can be reliably burned.

Next, the structure of the intake port of the internal combustion engine as the third embodiment of the present invention will be described. FIG. 12 is a schematic partial sectional view showing the structure thereof, and FIG. FIG. 9 is a view corresponding to a C-C cross-sectional view in FIG. Also in the third embodiment, as in the second embodiment,
Only the shapes of the partition walls 21 and 21 in the above-described first embodiment are different, and the other structures are the same as those in the above-described first and second embodiments. The internal combustion engine is also configured as a layered combustion internal combustion engine.

In this embodiment, as shown in FIG. 12, the partition wall 21C is formed in parallel with each other on the lower half side of the intake ports 46A and 46B, and only this lower half is divided in the vertical direction. It has become. Therefore, in the upper half of each intake port 46A, 46B, the central passage 4 and the lateral passage 5 are not partitioned, and the two passages 4, 5 are formed as one passage.

Since the intake port structure for the internal combustion engine as the third embodiment of the present invention is constructed as described above, it is possible to obtain the same effect as that of the first embodiment described above, and the second embodiment. The manufacturing cost can be reduced as in the example.
That is, in this embodiment, as described in the first embodiment,
The injector 12 is disposed in the upper part of the intake passage near the branch portion 46C of the two intake ports 46A, 46B and injects fuel from the upper side of the intake passage toward the lower side of the intake ports 46A, 46B. Therefore, the partition wall 21C provided in the intake ports 46A and 46B partitions only the lower half side, so that the intake air can be sufficiently stratified. By omitting the upper half portion of the partition wall 21C of the second embodiment, the partition wall 21C of the third embodiment can reduce the manufacturing cost of this upper half portion, and the intake ports 46A, 46B. The weight of can be reduced.

Next, the structure of the intake port of the internal combustion engine as the fourth embodiment of the present invention will be explained. FIG. 13 is a schematic partial sectional view showing the structure thereof, and FIG. 3 in the first embodiment (FIG. 2). FIG. 9 is a view corresponding to a C-C cross-sectional view in FIG. The internal combustion engine is also configured as a layered combustion internal combustion engine. The partition wall 21D in the fourth embodiment is also the first
Similar to the embodiment, the intake ports 46A and 46B are formed parallel to each other from the inner wall 8 on the upper surface side to the inner wall 7 on the lower surface side, and are provided so as to divide each of the intake ports 46A and 46B in the left-right direction. And these partition walls 21D, 21D
Thus, the inside of each intake port 46A, 46B is divided into a spark plug side (center side) passage 4 and an anti-ignition plug side (outside) passage 5 along the flow direction of intake air.

Then, as shown in FIG.
1D is extended from the upstream side of the intake ports 46A, 46B to the front of the umbrella portion 56 of the intake valve 58, and is formed by omitting a portion near the umbrella portion 56 with respect to the partition wall 21B of the second embodiment. Has been done. Since the intake port structure for the internal combustion engine as the fourth embodiment of the present invention is configured as described above, it is possible to obtain the same effects as those of the first embodiment described above, and to reduce the number of manufacturing steps. You can That is, the partition wall 2
By forming 1D by omitting the portion of the intake valve 58 near the cap portion 56, the intake ports 46A and 46B can be molded without requiring a highly accurate manufacturing technique.

Next, an intake port structure for an internal combustion engine as a fifth embodiment of the present invention will be described. FIG. 14 is a schematic partial cross-sectional view showing the structure thereof, which is shown in FIG. 3 in the first embodiment (FIG. 2). FIG. 9 is a view corresponding to a C-C cross-sectional view in FIG. The internal combustion engine is also configured as a layered combustion internal combustion engine. The partition wall 21E of the fifth embodiment is provided by omitting the portion in the vicinity of the stem portion 57 of the intake valve 58 from the partition wall 21D of the fourth embodiment. That is, as shown in the drawing, the end portion of the partition wall 21E has the stem 5 of the intake valve 58.
The partition wall 21E is formed substantially parallel to the partition wall 7, and thus the end portion of the partition wall 21E is formed in a straight line. Also, this intake valve 5
If the gap between the stem portion 57 of No. 8 and the end portion of the partition wall 21E is too large, the flow of intake air in the intake ports 46A and 46B may be disturbed, so this gap is provided so as not to become too large. There is.

Since the intake port structure for the internal combustion engine as the fifth embodiment of the present invention is constructed as described above, the same effect as that of the first embodiment can be obtained, and
Since the partition wall 21E also has a simple shape, the manufacturing cost and the number of steps can be reduced. Next, the intake port structure of the internal combustion engine as the sixth embodiment of the present invention will be described. FIGS. 15 to 21 show the intake port structure of the internal combustion engine as the sixth embodiment of the present invention. Its schematic plan view, FIG. 16 is its schematic partial vertical cross-sectional view, FIG. 17 is a schematic cross-sectional view of a plane orthogonal to its flow direction, and FIGS. 18 to 20 are cross-sectional shapes of planes orthogonal to its flow direction. 2 is a schematic cross-sectional view showing various examples of FIG. 17 corresponding to FIG.
FIG. 1 is a schematic plan view showing a modified example corresponding to FIG.

The internal combustion engine is also constructed as a layered combustion internal combustion engine. Now, as shown in FIGS. 15 and 16, in each cylinder of the internal combustion engine having the intake port structure according to the first embodiment, the cylinder bore 24, the piston 26, and the cylinder head 2 formed in the cylinder block 22 are provided.
A combustion chamber 30 is formed by being surrounded by 8 and the combustion chamber 30.
Two intake ports 46A and 46B are introduced into the 0, and intake valves 58 are installed respectively. Further, two exhaust ports 47A and 47B are also introduced into the combustion chamber 30, and exhaust valves are respectively installed therein.

The intake ports 46A and 46B join together on the upstream side to communicate with the common intake passage 43, and the exhaust ports 47A and 47B merge onto the downstream side to communicate with the common exhaust passage 60. It is connected. In addition, at the center of the cylinder 25, the spark plug 1 as an ignition means is provided.
1 is located between the intake ports 46A and 46B.

Further, a pent roof 34 is formed on the upper wall of the combustion chamber 30, and the pent roof 34 has
A slope is provided so that the intake flow from each intake port 46A, 46B can be guided downward along the inner wall surface of the cylinder bore 24 on the extension axis of each intake port 46A, 46B. The guide of the pent roof 34 also promotes the generation of the tumble flow.

Further, each intake port 46 of this internal combustion engine
As shown in FIG. 16, A and 46B are formed in a straight straight port, and the cross-sectional shape of this straight port is as shown in FIG.
A half portion of A, 46B on the tumble flow side (that is, an upper half portion of the intake ports 46A, 46B through which the main component flow forming the tumble flow flows) 46A-1, 46B-1 blocks the other half portion (that is, the tumble flow). Intake port 4 through which such a component flow flows
6A, 46B lower half) 46A-2, 46B-2, and the intake flow centers of the intake ports 46A, 46B are on the tumble flow side (that is, the upper half 46A-1 of the intake ports 46A, 46B). , 46B-1).
As a result, the intake flow from the intake ports 46A and 46B easily forms a tumble flow in the combustion chamber 30.

In the sixth embodiment, the intake ports 46A and 46B are formed so as to have a cross section of a substantially inverted triangle. By the way, in the intake ports 46A, 46B, partition walls 21 are provided so as to divide the intake ports 46A, 46B into left and right directions, respectively, and the partition walls 21 allow the interiors of the intake ports 46A, 46B to be on the spark plug side (center side). ) And the non-ignition plug side (outside) along the flow direction of the air-fuel mixture.

An injector 12 as a fuel injection means is attached near the confluence of the intake ports 46A and 46B. The injector 12 is connected to the intake ports 46A and 46B.
The fuel is sent to the center side partitioned by the partition wall 21 of 46B (see FIGS. 15 and 17). The intake valve 5
The valve stem 57 of No. 8 penetrates the partition wall 21 in the vertical direction.

Further, the intake port 46A with the partition wall 21,
46B, the tumble flow side half portion 46A-1, 4
As a cross-sectional shape for widening 6B-1 from the other half portions 46A-2, 46B-2, in addition to that shown in FIG. 17, a baseball home base shape as shown in FIG. , The other half 46A-2,4 as shown in FIG.
6B-2 having a rounded shape and a tongue shape, and FIG.
As shown in FIG. 5, various intake ports divided by the partition wall 21 can be considered, such as a baseball home base.

With this structure, the intake air is mixed with the fuel injected by the injector 12, and the intake ports 46
After flowing into the combustion chamber 30 from A and 46B, the mixture is compressed and expanded (explosion) in the combustion chamber 30, and then discharged from the exhaust ports 47A and 47B to the exhaust passage 60. Since only the air is sent to the outside of the intake ports 46A and 46B, which is partitioned by the partition wall 21, and the fuel is sent only to the center side of the intake ports 46A and 46B, which is partitioned by the partition wall 21, the fuel and air are stratified. As a result, the spark plug 11 is supplied with the air-fuel mixture having a rich fuel layer. Therefore, the air-fuel mixture with less fuel is sent to the entire combustion chamber 30,
A sufficient amount of fuel is sent to the ignition plug 11 for ignition.
Therefore, since a fuel rich place can be made near the spark plug 11, it is possible to operate the engine with a mixture of fuel in an amount smaller than the stoichiometric air-fuel ratio without deteriorating the ignitability.

Further, the intake flow component from the tumble flow side half portions 46A-1, 46B-1 of each intake port 46A, 46B is significantly larger than the intake flow component from the other half portions 46A-2, 46B-2. Become stronger. That is, the intake ports 46A, 4
The intake flow component from the tumble flow side half portions 46A-1 and 46B-1 of 6B is a component of the flow forming the tumble flow,
The other half of the intake ports 46A, 46B 46A-2, 46B
Since the intake flow component from −2 is a component that blocks the tumble flow, the above-mentioned flow rate imbalance does not reduce the overall flow passage cross-sectional area of the intake port, that is, the intake flow of the entire intake port. The strength of the tumble flow can be increased while keeping the flow rate (velocity) constant.

In the sixth embodiment, as shown in FIG. 21, two intake ports 46A and 46B and an exhaust port 4 are provided.
The present invention can be similarly applied to a three-valve type internal combustion engine having one.

[0074]

As described in detail above, according to the intake port structure for an internal combustion engine of the present invention as defined in claim 1, an intake port having two combustion chamber openings that are opened and closed by two intake valves is provided. In an internal combustion engine configured such that an intake air flow from the intake port becomes a tumble flow in the combustion chamber, an ignition means arranged at a central portion of the combustion chamber top and a lower surface side in the intake port Two partition walls that extend along the intake streamline on the inner wall and divide the inside of the intake port into a central passage on the ignition means side and side passages on both sides thereof, and the upper surface of the intake port or its By the structure that is provided in the vicinity and is provided with fuel injection means for injecting fuel toward the lower side of the central passage in the intake port, the flow of air-fuel mixture and the flow of air in the intake port are separated. What to do Can, a tumble flow of the air-fuel mixture layer is formed on the ignition means side of the central portion of the combustion chamber top, it is possible to form a tumble flow of a layer of air only in the anti-ignition device side. As a result, a stable combustion state can be obtained even with a lean air-fuel mixture, and an internal combustion engine with extremely low fuel consumption can be realized.

When the partition wall extends from the inner wall on the lower surface side of the intake port to the inner wall on the upper surface side, the flow of the air-fuel mixture and the air in the intake port may be increased. Can be completely separated and the stratification of the mixture layer and the air-only layer can be enhanced. Further, as described in claim 3, even if the space is provided between the partition wall and the inner wall of the intake port upper surface side, the flow of the air-fuel mixture and the flow of air in the intake port are separated. In addition, the weight of the intake port can be reduced.

[Brief description of drawings]

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

FIG. 2 is a schematic top view showing the configuration of the intake port structure of the internal combustion engine as the first 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 the structure of the intake port structure of the internal combustion engine as the first embodiment of the present invention, and FIG.
6 is a sectional view taken along line CC in FIG.

FIG. 4 is a schematic partial cross-sectional view showing the structure of an intake port structure for an internal combustion engine as a first embodiment of the present invention, and FIG.
FIG. 6 is a sectional view taken along line BB in

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

FIG. 6 is a schematic diagram showing a variation of a fuel injection method in the intake port structure of the internal combustion engine as the first embodiment of the present invention.

FIG. 7 is a graph showing the effect of the intake port structure of the internal combustion engine as the first embodiment of the present invention.

FIG. 8 is a graph showing the effect of the intake port structure of the internal combustion engine as the first embodiment of the present invention.

FIG. 9 is a graph showing the effect of the intake port structure of the internal combustion engine as the first embodiment of the present invention.

FIG. 10 is a graph showing the effect of the intake port structure of the internal combustion engine as the first embodiment of the present invention.

FIG. 11 is a schematic partial cross-sectional view showing the structure of the intake port structure of the internal combustion engine as the second embodiment of the present invention, which is shown in FIG. 3 (C-C cross-sectional view in FIG. 2) of the first embodiment. Corresponding figure

FIG. 12 is a schematic partial cross-sectional view showing the structure of an intake port structure for an internal combustion engine as a third embodiment of the present invention, which is shown in FIG. 3 (C-C cross-sectional view in FIG. 2) of the first embodiment. It is a corresponding figure.

FIG. 13 is a schematic partial cross-sectional view showing the structure of an intake port structure for an internal combustion engine as a fourth embodiment of the present invention, which is shown in FIG. 3 (C-C cross-sectional view in FIG. 2) of the first embodiment. It is a corresponding figure.

FIG. 14 is a schematic partial cross-sectional view showing the structure of the intake port structure of the internal combustion engine as the fifth embodiment of the present invention, which is shown in FIG. 3 (C-C cross-sectional view in FIG. 2) of the first embodiment. It is a corresponding figure.

FIG. 15 is a schematic plan view of an intake port structure for an internal combustion engine as a sixth embodiment of the present invention.

FIG. 16 is a schematic partial vertical sectional view of an intake port structure for an internal combustion engine as a sixth embodiment of the present invention.

FIG. 17 is a schematic cross-sectional view of a plane orthogonal to the flow direction in the intake port structure of the internal combustion engine as the sixth embodiment of the present invention.

FIG. 18 is a schematic cross-sectional view showing another example of the cross-sectional shape of the plane orthogonal to the flow direction in the intake port structure of the internal combustion engine as the sixth embodiment of the present invention, corresponding to FIG. 3.

FIG. 19 is a schematic cross-sectional view showing another example of the cross-sectional shape of the plane orthogonal to the flow direction in the intake port structure for the internal combustion engine as the sixth embodiment of the present invention, corresponding to FIG. 17;

FIG. 20 is a schematic cross-sectional view showing another example of the cross-sectional shape of the plane orthogonal to the flow direction in the intake port structure for the internal combustion engine as the sixth embodiment of the present invention, corresponding to FIG. 17.

FIG. 21 is a schematic plan view showing a modification of the intake port structure of the internal combustion engine as the sixth embodiment of the present invention, corresponding to FIG. 15.

FIG. 22 is a schematic vertical cross-sectional view showing a structure of an intake port of a conventional internal combustion engine together with a structure around a combustion chamber.

FIG. 23 is a schematic perspective view showing a structure of an intake port of a conventional internal combustion engine together with a structure around a combustion chamber.

FIG. 24 is a schematic cross-sectional view of a surface of the conventional intake port structure of the internal combustion engine, which is orthogonal to the flow direction of intake air (DD in FIG. 22).
FIG.

FIG. 25 is a cross-sectional view (a view corresponding to a cross section taken along the line DD in FIG. 22) showing another example of a schematic cross section of a surface of the conventional intake port structure for an internal combustion engine, which is orthogonal to the flow direction of intake air. is there.

FIG. 26 is a schematic vertical sectional view showing another example of a conventional intake port structure for an internal combustion engine.

FIG. 27 is a graph showing an effect of a tumble flow in an internal combustion engine using a conventional tumble flow.

[Explanation of symbols]

 1A, 1B Intake port axis 2 Intake valve axis 3 Intake port reference plane 4 Central passage 5 Side passage 6 Injector injection axis 7 Intake port lower side inner wall 8 Intake port upper side inner wall 11 Spark plug 12 as ignition means 12 Fuel Injector as injection means 13 Intake port oblique line parts 21, 21A to 21E Partition wall 22 Cylinder block 24 Cylinder bore 25 Cylinder 26 Piston 28 Cylinder head 30 Combustion chamber 34 Pentroof 35 Recess 37 Slope 39 Raised part 46, 44 ', 40F, 42F Intake air Port 40 ', 42', 46A, 46B Intake 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 Exhaust Port 47A, 47B Exhaust port part 5 6 Valve head 57 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

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location F02F 1/42 F 8503-3G F02M 69/00 360 P 7825-3G (72) Inventor Yasuki Tamura Tokyo 5-33-8 Shiba, Minato-ku, Mitsubishi Motors Co., Ltd. (72) Inventor, Michihiro Hata, 5-33-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors, Co., Ltd. (72) Shunsuke Matsuo, Tokyo Port 5-3-5, Shiba, ward Within Mitsubishi Motors Corporation

Claims (3)

[Claims] 1. An internal combustion engine having an intake port having two combustion chamber openings that are opened and closed by two intake valves, and configured so that the intake flow from the intake port becomes a tumble flow in the combustion chamber. In the central portion of the top of the combustion chamber, and extending along the intake streamline direction on the inner surface of the lower surface side in the intake port, the inside of the intake port on the center of the ignition means side. Two partition walls that divide into a side passage and side passages on both sides thereof, and fuel that is disposed on or near the upper surface of the intake port and injects fuel toward the lower side of the central side passage in the intake port. An intake port structure for an internal combustion engine, characterized in that injection means are provided. 2. The intake port structure for an internal combustion engine according to claim 1, wherein the partition wall extends from the inner wall on the lower surface side of the intake port to reach the inner wall on the upper surface side. 3. The intake port structure for an internal combustion engine according to claim 1, wherein a space is provided between the partition wall and the inner wall of the intake port upper surface side.