JPH06159076A - Internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to secure a sufficient intake amount without deteriorating the function of directing the intake air flow into the combustion chamber. The internal combustion engine is provided with an intake port formed so as to direct the intake air flow, and the intake port has a portion near the intake opening and having a curved portion with a larger curvature than the upstream side. It has a port. The curved portion has an inner diameter larger than the inner diameter of the intake opening, thereby ensuring a sufficient intake amount without deteriorating the function of directing the intake air flow into the combustion chamber. It is possible to do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine provided with an intake port for directing the flow of intake air flowing into a combustion chamber, and more particularly to generating a tumble flow in the combustion chamber by the directed intake air flow. The present invention relates to an internal combustion engine suitable for use in a stratified combustion internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, there is known an internal combustion engine in which an intake port shape is set so as to direct the flow of intake air flowing into the combustion chamber for the purpose of improving combustion characteristics in the combustion chamber. . Also, for the purpose of low fuel consumption operation, a stratified combustion internal combustion engine is known which is capable of igniting a mixture rich in air-fuel ratio by generating a rich mixture in the combustion chamber and igniting the rich mixture. There is. As a method of generating a rich layer of air-fuel mixture in the combustion chamber, it is also known to direct the flow of intake air flowing into the combustion chamber by an intake port to generate a stratified swirling flow in the combustion chamber. As one of them, for example, a stratified combustion internal combustion engine that generates a vertically oriented laminar vertical-vortex (vertical-vortex) as shown in FIGS. 37 and 38, that is, a tumble flow has already been put into practical use.

37 and 38 show one cylinder structure of a two-intake-port internal combustion engine. In the figure, reference numeral 322
Is a cylinder block, 324 is a cylinder bore, 326 is a piston, 328 is a cylinder head, and 330 is a combustion chamber. 334 is the upper wall of the combustion chamber 330,
It is formed in a pent roof type having two slopes 334a and 334b. The intake ports 340 and 342 are opened to the slopes 334a of the upper wall portion 334 of the combustion chamber 330, and intake valves 358 are installed at both openings. In the figure, reference numeral 347 is an exhaust port communicating with the exhaust passage 360, and 359 is an exhaust valve. The intake air that has flowed into the combustion chamber 330 from the intake ports 340 and 342 flows toward the inner wall surface of the cylinder bore 324 on the extension axis of the intake ports 340 and 342 along the slope 30b. Arrows Fa,
Generate a tumble as indicated by Fm.

Further, as shown in FIG. 37, an injector 312 is provided only on one intake port 342, and a spark plug 310 is arranged near an intake valve 358 of an intake port portion 342 equipped with this ejector 312. There is. Therefore, in the vicinity of the ignition plug 310, a tumble flow Fm of the air-fuel mixture formed by the fuel injected from the injector 312 and the intake air is formed, whereby the tumble flow Fm of the air-fuel mixture and the air are mixed in the combustion chamber 330. A tumble flow layered with the tumble flow Fa is formed.

Therefore, even when the air-fuel ratio between the air and the fuel in the combustion chamber 330 is large, that is, even when the combustion chamber 330 as a whole is in a lean burn state in which the fuel concentration is low, other portions around the spark plug 310 are present. Since a richer air-fuel mixture exists, a stable combustion state can be obtained.

[0006]

However, the combustion chamber 33
In order to direct the intake air flowing in from the intake ports 340, 342 so as to generate the tumble flows Fa, Fm in 0, the intake ports 340, 342 form a substantially straight shape up to the vicinity of the combustion chamber 330. There is. The portion of each intake port 340, 342 that performs this orientation may have a curved shape with a very small curvature in addition to the straight shape, but in any case, each intake port 340, 342.
Will be curved with the largest curvature in the combustion chamber 330, and the flow cross-sectional area of this curved portion will be small with respect to the flow of intake air, making it impossible to secure a sufficient amount of intake air, and a desired tumble flow cannot be obtained. However, there is a possibility that a problem such as failure to obtain a desired maximum intake amount may occur.

[0007]

The present invention provides an internal combustion engine capable of ensuring a sufficient intake amount without deteriorating the function of directing the intake air flow sucked into the combustion chamber, and more powerful in the combustion chamber. An object of the present invention is to provide an internal combustion engine that can generate a tumble flow, and a first invention is a combustion chamber defined by an inner surface of a cylinder, an upper surface of a piston inserted into the cylinder, and a lower surface of a cylinder head. An intake port that is provided on the lower surface of the cylinder head and has an intake opening that is opened and closed by an intake valve, and the intake port has a curved portion that is curved in the vicinity of the intake opening with a curvature larger than that on the upstream side thereof. In the internal combustion engine, a curved portion of the intake port near the intake opening has a bulge having an inner diameter larger than an inner wall of the intake opening. And it features.

According to a second aspect of the present invention, a combustion chamber defined by an inner surface of a cylinder, an upper surface of a piston fitted into the cylinder and a lower surface of a cylinder head, and a one side of an imaginary plane including the cylinder axis of the cylinder head are arranged. Has an intake opening that is opened and closed by an intake valve, respectively, and from the intake opening to the lower surface of the cylinder head so that the intake air generates tumble flows that are parallel to and in the same direction in almost the entire combustion chamber. Therefore, a plurality of intake ports for inflowing intake air toward the other side of the virtual plane, and an ignition plug provided at a position corresponding to an intake flow flowing in from one of the intake ports on the inner surface of the combustion chamber, Fuel is supplied to one of the intake ports corresponding to the position of the spark plug, which causes stratified tumble in the combustion chamber during the intake stroke. A plurality of intake ports, and the plurality of intake ports have a directing portion for directing intake air flowing into the combustion chamber, a downstream end of the directing portion, and the intake opening. A curved portion to be connected, and the curved portion has a bulge having an inner diameter larger than an inner diameter of the intake opening.

According to a third aspect of the present invention, a combustion chamber defined by an inner surface of a cylinder, an upper surface of a piston inserted into the cylinder and a lower surface of a cylinder head, and a combustion chamber defined on one side of an imaginary plane including a cylinder axis of the cylinder head. Are provided and each have an intake opening that is opened and closed by an intake valve, and along the bottom surface of the cylinder from the intake opening so that the intake air generates tumble flows that are parallel and in the same direction in almost the entire combustion chamber. Two intake ports for inflowing intake air toward the other side of the virtual plane, vertical partition walls partitioning at least one of the intake ports into a plurality of passages, and at least one of the passages on the inner surface of the combustion chamber.
And a fuel supply means for supplying fuel to the passage corresponding to the position of the spark plug, thereby generating a stratified tumble flow in the combustion chamber in the intake stroke. The two intake ports have a directing portion for directing intake air flowing into the combustion chamber, and a curved portion connecting a downstream end of the directing portion and the intake opening. The curved portion has a bulge having an inner diameter larger than the inner diameter of the intake opening.

[0010]

[Operation] According to the first invention, in the intake port having the intake opening opened and closed by the intake valve provided on the lower surface of the cylinder head forming the combustion chamber, the vicinity of the intake opening is larger than the upstream side thereof. Since the curved portion curved with a curvature has an inner diameter larger than the inner diameter of the intake opening, it is possible to sufficiently maintain the flow passage cross-sectional area at the curved portion and obtain a desired intake flow rate. Is.

According to the second aspect of the invention, a plurality of intake ports are provided on one side of a virtual plane including the cylinder axis of the lower surface of the cylinder head forming the combustion chamber and each having an intake opening opened and closed by an intake valve. , The intake air directing portion is used to direct the intake air flow, and the directing portion has a curved portion connecting the downstream end of the directing portion and the intake opening. Also has a large inner diameter to secure a desired amount of intake air, so the intake air flows from the intake opening along the lower surface of the cylinder head toward the other side of the virtual plane, and is parallel to each other in almost the entire combustion chamber. In the same direction, the desired tumble flow can be generated. Furthermore, the fuel supply means
By supplying fuel to the intake flow corresponding to the spark plug provided at a position corresponding to the intake flow flowing from one of the intake ports, a stratified tumble flow is generated in the combustion chamber in the intake stroke. .

According to the third aspect of the invention, there are two intake ports which are arranged on one side of the virtual plane including the cylinder axis of the lower surface of the cylinder head forming the combustion chamber and each of which has an intake opening opened and closed by an intake valve. , The intake air directing portion is used to direct the intake air flow, and the directing portion has a curved portion connecting the downstream end of the directing portion and the intake opening. Also has a large inner diameter to secure a desired amount of intake air, so the intake air flows from the intake opening along the lower surface of the cylinder head toward the other side of the virtual plane, and is parallel to each other in almost the entire combustion chamber. In the same direction, the desired tumble flow can be generated. Furthermore, a vertical partition wall that partitions at least one of the intake ports into a plurality of passages is provided.
A spark plug is provided in a position corresponding to at least one of the passages on the inner surface of the combustion chamber, and fuel is supplied to the passages corresponding to the spark plugs, so that mutually parallel layered tumble flows can be generated. Is.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the layered combustion internal combustion engine of the first embodiment will be described with reference to FIGS. 1 and 3. In each cylinder of the internal combustion engine, a combustion chamber 30 is formed by being surrounded by a cylinder bore 24 formed in a cylinder block 22, a piston 26, and a cylinder head 28. An intake port 46 communicates with the combustion chamber 30. In detail, the intake port 46 is a Siamese port having two intake port portions 46 </ b> A and 46 </ b> B that are divided into two by a branch portion 46 </ b> C and open into the combustion chamber 30. At the intake openings of the intake port portions 46A and 46B to the combustion chamber 30, the intake valves 5 that open and close the intake openings, respectively.
8 are provided. Further, an exhaust port 47 to the combustion chamber 30 is connected. The exhaust port 47, in detail,
It is a Siamese port having two exhaust port portions 47A and 47B which are divided into two on the way and open into the combustion chamber 30, respectively. An exhaust valve 61 is arranged at the opening of each exhaust port to the combustion chamber 30. The intake port portions 46A and 46B open to the combustion chamber 30 on one side of the virtual plane FC including the cylinder axis L, and the exhaust port portions 47A and 47B open to the combustion chamber 30 on the other side of the virtual plane FC. is doing. Further, the ceiling of the combustion chamber 30 defined by the lower surface 60 of the cylinder head 28 is substantially a virtual plane FC.
It is formed in a pent roof type having two slopes 60a and 60b so as to have a top. Also, the combustion chamber 3
A spark plug 1 as an ignition means is provided in the center of the 0 ceiling.
1 is provided.

An injector 12 as fuel supply means, which will be described in detail later, is attached to an upstream side portion of the branch portion 46C in the intake port 46. By this injector 12, fuel is injected toward the downstream side from the vicinity of the branch portion 46C of the intake port 46.

As shown in FIGS. 1 and 2, the axial center lines 1A and 1B of the intake port portions 46A and 46B are straight lines parallel to each other. That is, each intake port portion 46
A and 46B each have a directing portion that produces a linear intake air flow parallel to each other. And each intake port portion 46
The intake air from A and 46B are in parallel with each other in the combustion chamber 3
It is designed to flow into 0. The intake air that has flowed into the combustion chamber from each of the intake port portions 46A and 46B in the intake stroke flows to the other side of the virtual plane FC along the slope 60b of the lower surface 60 of the cylinder head 28 that forms the combustion chamber ceiling. The intake air descends along the inner surface of the cylinder bore 24 and flows to the piston upper surface 35, and further the intake air rises along the inner surface of the cylinder bore 24 and flows to the inclined surface 60a of the lower surface 60 of the cylinder head 28, whereby combustion occurs. An intake longitudinal vortex flow (intake tumble flow) is generated in almost the entire chamber 30.

Further, each intake port portion 46A, 46B
A partition wall 21 extending in the vertical direction is formed on each of the shafts 1A and 1B. Each partition wall 21 divides each intake port portion 46A, 46B into a central passage 4 and a lateral passage 5 outside thereof. Then, the injector 12 is configured to inject fuel toward the central passage 4 that generates a tumble flow at a position corresponding to the spark plug 11.

With the above construction, the tumble flow Fm containing fuel and the tumble flow Fa containing no fuel are formed in layers in the combustion chamber 30 in the intake stroke. In addition,
It is important that the tumble flows Fm and Fa are substantially parallel to each other and have the same direction, so that even in the compression stroke, the laminar tumble flows Fm and Fm in the combustion chamber 30.
a can be present.

In this embodiment, each structure has its own characteristics, which will be described below in order. First, the top surface shape of the piston 26 will be described. The piston 26 is
As shown in FIGS. 1, 3 and 4, its top surface 34
And a raised portion 37. The top of the raised portion 37 is located on the intake opening side of the intake port 46 of the virtual plane FC on the top surface 34. The slope vf1 of the raised portion 37 on the virtual plane FC side is configured to smoothly continue to the top surface 34 of the piston 26. In addition, the slope vf of the raised portion 37
1 is configured such that the cross section parallel to the virtual plane FC is a straight line parallel to the reference plane of the top surface 34 of the piston 26. That is, the slope vf1 of the raised portion 37 causes the tumble flows Fm and Fa to move toward the top surface 3 of the piston 26 during the intake stroke.
When the direction is changed from 4 to the inner surface of the cylinder bore 24, they are not mixed with each other and are kept in a clean layered structure.

When the piston 26 is in the vicinity of the top dead center of the compression stroke, the outer slope vf2 of the raised portion 37 cooperates with the ceiling of the combustion chamber 30 to generate the squish SF, so that the tumble flow Fm, It is configured such that Fa is slightly disturbed.

Further, as shown in FIGS. 1, 3 and 4, a valve recess 39 for preventing interference with the intake valve 58 is provided on the outer slope vf2 of the raised portion 37. As a result, even if the intake valve 58 overlaps and opens at the time of opening the exhaust valve 61 at the top dead center, the piston 26 causes the intake valve 5 to open.
It is possible to maintain the position of the top dead center with a high compression ratio without interfering with No. In addition, in FIG. 3, the partition wall 21 is illustrated for convenience of description.
Are not shown.

Next, the above-mentioned intake port portions 46A, 46
The partition wall 21 provided in B will be described. Each partition 21
As shown in FIG. 5, the intake port portions 46A, 46
The downstream end 21B of B extends to the vicinity of the intake valve 58. More specifically, the downstream end 21B of each partition wall 21 is formed with an appropriate clearance so as not to contact the umbrella portion 56 of the intake valve 58 and the stem portion 57 that crosses the intake port portions 46A and 46B. Has been done. For this reason,
The operation of the intake valve 58 is not affected at all. In addition, each partition wall 21 has an intake port portion 46A,
It is formed along the center line 45A of each streamline 45 of 46B and the axial center lines 1A, 1B of the intake port portions 46A, 46B. As a result, the intake flow that flows into the intake port 46 flows into the combustion chamber 30 in a more rectified state. Here, since the intake port portions 46A and 46B are substantially parallel to each other, the partition walls 21 and 21 are also disposed substantially parallel to each other.

Further, as shown in FIGS. 2 and 6, the upstream end 21A and the downstream end 21B of the partition wall 21 are both formed in a convex curved surface so as to improve the rectification effect of the intake flow. The upstream side 21A and the downstream end 21B are formed in this manner because the effect of reducing the fluid resistance is aimed at by rectifying the intake flow, and the manufacturing effect of the partition wall 21 is taken into consideration. That is, if each partition wall end 21A, 21B is formed into a convex curved surface, the mold (core) corresponding to each partition wall end 21A, 21B will be well removed when casting the intake port 46, for example. , Casting is reliable and easy.

Next, the arrangement of the injector 12 and the relationship between the injector 12 and the partition wall 21 will be described with reference to FIGS. 1, 3, 5 and 6. As shown in FIG.
Thus, the inside of each intake port portion 46A, 46B is divided into a central passage 4 and a side passage 5. The injector 12 as the fuel injection means is arranged upstream of the branch portion 46C in the two intake ports 46, as shown in FIGS. Further, the injector 12 is adapted to inject fuel toward the downstream of the two intake port portions 46A and 46B in accordance with the intake stroke. Reference numeral 6 in FIGS. 5 and 6 is the axis of the injector, and
It shows the center line of the injection range.

That is, as shown by the injection axis 6 of FIGS. 5 and 6, the fuel injected from the upper surface of the intake port is sucked into the combustion chamber 30 through the central passage 4, and Only air is sucked into the combustion chamber 30 from the side passage 5.

As a result, the intake port portions 46A, 46
The flow branched into the central passage 4 and the side passage 5 in B flows into the combustion chamber 30 in layers while being separated from each other while being rectified by the partition wall 21. Therefore, due to the partition wall 21, when the intake air flows into the combustion chamber 30 as shown in FIG. 6, the intake air flows between Fm along the air-fuel mixture and the air-only Fa and Fa. A tumble flow in a state of being separated into three layers (a total of three flows of the central passage 4 and the side passages 5 on both sides thereof), that is, a stratified state, is formed.

Next, the thickness of the valve stem 57 and the thickness of the partition wall 21 will be described with reference to FIGS. 2 and 6. As shown in FIGS. 2 and 6, the center line of the partition wall 21 and the center line of the valve stem 57 are located on the same plane, and the partition wall 21 is formed thinner than the diameter of the valve stem 57. That is, the surface 121 of the partition wall 21 on the central passage 4 side.
A has a shape that is biased toward the side passage 5 side from the surface of the valve stem 57 on the side of the central passage 4.

As a result, as shown in FIG. 6, the fuel spray in the mixed air flow along the inner surface 121A of the partition wall 21 is guided by the inner surface of the valve stem 57 and burns along the arrow P shown in FIG. Aimed at the spark plug 11 in the center of the room,
The fuel spray is concentrated on the spark plug 11.

Next, the sectional shape of the intake port 46 in the intake flow direction will be described with reference to FIGS. 7 and 8. FIG. 7 is a cross-sectional view of the intake port 46 along the intake flow direction, and FIG. 8 is a view showing the cross-sectional shapes of the end face H-H and the cross-sections S1-S1 to S6-S6 orthogonal to this. As shown in FIGS. 8A to 8G, in the intake port 46, the upper half portions 46A-1 and 46B-1 gradually become more gradually downstream than the lower half portions 46A-2 and 46B-2. It is formed to be relatively wide. As a result, the intake port 4
The intake air flow from 6A and 46B easily forms a tumble flow in the combustion chamber 30. And intake port 4
Reference numeral 6 is a S3-S3 cross section of FIG. 8 (f), which branches into a Siamese port to form intake port portions 46A and 46B. Furthermore, the port shape is also an inverted triangular shape.
Further, the intake port portions 46A and 46B exhibit a substantially inverted triangular cross-sectional shape toward the downstream side to strengthen the tumble flow.

That is, by widening the upper half portion 46-1 in each cross section of the intake port 46 more than the lower half portion 46-2, the flow velocity and the flow rate of the upper half portion 46-1 in the intake port 46 become lower. It is bigger than half. On the other hand, when the intake valve 58 is opened, as shown in FIG.
There is a flow component a that increases the tumble flows Fa and Fm, and a flow component b that suppresses the tumble flows Fa and Fm. Therefore, since the flow velocity and the flow rate of the upper half of the intake port 46 are larger than those of the lower half, the tumble flows Fa and Fm can be made stronger. Moreover, since the flow component a is in the same direction as the tumble flows Fa and Fm, the flow resistance to the flow component a is extremely small, and therefore the flow rate as a whole can be greatly increased.

Further, as shown in FIGS. 8 (a) to 8 (g),
The partition wall 21 is provided in the intake port 46 over substantially the entire length. This partition wall 21 is the intake port portion 4
6A and 46B are provided so as to divide the inside of the 6A and 46B into two in the left-right direction from the intake port lower side wall surface 7 to the intake port upper side wall surface 8. From this, the intake port portions 46A and 46B are provided.
It can be seen that the intake air flow that has flowed in branches into the central passage 4 and the side passages 5.

That is, as shown in FIG. 8A, the two intake port portions 46A, 46B are formed as one intake passage near the cylinder head side surface 28A (FIG. 7) which is the most upstream side, and immediately thereafter. The partition wall 21 divides the flow of intake air into the central passage 4 and the side passages 5. Then, as shown in FIGS. 8B to 8D, the central passage 4 is gradually divided into two parts, and the intake flow is completely divided into two parts downstream from the cross section S4-S4 shown in FIG. 8E. To be done. Then, the intake flow divided into two in this manner flows into the combustion chamber 30 by the intake valve 58.

The intake port 46 will be described in more detail with reference to FIGS. 7, 8 and 9. As shown in FIG. 7, the intake port 46 directs the intake flow and
Since a tumble flow is generated within 0, it has a substantially straight shape. On the other hand, due to the structure of the cylinder head, the axis of the intake opening opened / closed by the intake valve 58 and the direction of the intake flow cannot be the same. Therefore, the downstream end portions of the intake port portions 46A and 46B are connected to the intake opening via the curved portion having a large curvature. The substantial flow cross-sectional area in this curved portion is the smallest as is clear from FIGS. 8 (f) and (g), and in particular, the presence of the valve stem 57, the stem guide (not shown) and the partition wall 21 makes it possible to obtain the substantial flow cross-sectional area. The drop in the rate is extremely high.

Therefore, the intake port portions 46A, 46B
Is provided with a bulge 13 in which the width of the inner diameter of the curved portion in the intake port portions 46A and 46B is the largest and is set larger than the intake opening opened and closed by each intake valve 58. As a result, it is possible to prevent the substantial flow cross-sectional area from decreasing in the curved portion and to secure a sufficient flow velocity and flow rate.

Moreover, as is apparent from FIG. 9, the bulge 13 is mainly formed in the upper half portion 4 of each of the intake port portions 46A and 46B.
Since 6A-1 and 46B-1 are provided, the flow velocity and the flow rate of the upper half portions 46A-1 and 46B-1 can be made larger than those of the lower half portions 46A-2 and 46B-2. , Tumble flows Fa and Fm are generated more effectively.

Since the stratified combustion internal combustion engine as the first embodiment of the present invention is constructed as described above, in the intake stroke, from the intake port portions 46A, 46B to the combustion chamber 3
The intake air that has flowed into 0 forms a tumble flow Fm of the air-fuel mixture and a tumble flow Fa of air in a layered manner in the combustion chamber 30. Next, the stratified tumble flows Fm and Fa still exist even after entering the compression stroke, but when the vicinity of the top dead center of the compression stroke is approached, the tumble flows Fm and Fa begin to collapse. However, a rich mixture still exists in the vicinity of the ignition plug 11 in the combustion chamber 30, and the ignition plug 11 ignites in this state. The subsequent explosion stroke and exhaust stroke are exactly the same as those of the conventional stratified combustion internal combustion engine.

As a result, in the combustion chamber 30 as a whole, even if the air-fuel mixture has less fuel than the stoichiometric air-fuel ratio, the air-fuel mixture having a sufficient concentration for ignition exists in the vicinity of the spark plug 11, so that the ignition performance is improved. The engine can be operated without deterioration.

In particular, in this embodiment, a stronger tumble flow Fm, Fa is generated on the top surface 34 of the piston 26 by the slope vf1 of the raised portion 37 to obtain a more complete layered tumble flow Fm, Fa. You can Thereby, even if the air-fuel ratio of the air-fuel mixture in the entire combustion chamber 30 is made thinner, it is possible to obtain sufficiently stable ignition and combustion.

Further, the outer slope vf2 of the raised portion 37 of the piston 26 is located near the top dead center of the compression stroke, and the combustion chamber 30
Since the squish SF generated in cooperation with the ceiling of the squid causes slight turbulence in the air-fuel mixture, the combustion speed after ignition is improved. Note that if the squish SF is too strong, it has an adverse effect. Therefore, it is important that the distance between the outer slope vf2 and the ceiling of the combustion chamber 30 at the piston top dead center be appropriately adjusted. Further, a valve recess 39 is provided on the outer slope vf2 of the raised portion 37, and even when the intake valve 57 is opened due to valve overlap when the piston 26 reaches the top dead center, the outer slope vf2 and the intake valve 57 are separated from each other. It is configured to avoid interference. For this reason, the top dead center of the piston 26 is further increased to increase the compression ratio,
The combustion efficiency can be improved.

That is, as shown in the graph of FIG. 10, the partition walls 21 are provided in the intake ports 46A and 46B to promote stratification of the air-fuel mixture, so that the engine can be operated with a leaner air-fuel mixture. Here, the horizontal axis of the figure is the air-fuel ratio (A /
F), and the vertical axis is the NO _x emission amount and the Pi (illustrated average effective pressure) fluctuation rate. Lines a and c show the characteristics of an engine having a partition wall 21 in the intake port, and lines b and d show the characteristics of an engine having a normal tumble flow intake port without the partition wall 21. Shows. Also, line a, line b
Indicates the NO _x emission, and lines c and d relate to the Pi fluctuation rate.

As shown in FIG. 10, in the engine provided with the partition wall 21 (see line a), the A / F value is on the leaner side than the engine using the normal tumble flow (see line b). Thus, the amount of NO _x emission peaks. Further, it is possible to reduce the peak value itself of the NO _X emission amount. That is, because the stratification of the tumble flow in the combustion chamber 30 is promoted, the A / F at which the NO _x emission amount reaches the peak value moves to the lean side as compared with the conventional engine.

Lines c and d show the relationship between A / F and Pi fluctuation rate. Here, the Pi fluctuation rate serves as a guide for determining the combustion stability of the engine. If the Pi fluctuation rate is too high, 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 generally the Pi fluctuation rate of the combustion stability limit at which the engine can be operated without any discomfort.

As shown in this figure, in the engine provided with the partition wall 21 (see the line c), the normal tumble flow is used for the limit value of the Pi fluctuation rate at which the stable combustion state in the cylinder is obtained. A / on the leaner side than the engine (see line d)
It is possible to operate the engine at F, and the NO _X emission amount at this time can be greatly reduced. That is, it shows that a stable combustion state can be obtained even with a leaner A / F, and the A / F at the combustion stability limit is improved. Therefore, with this structure, it is possible to realize an engine that has extremely low fuel consumption and emits almost no NO _x .

Further, the thickness of the partition wall 21 depends on the thickness of the valve stem 5.
7 is smaller than the diameter of 7, and the center line of the partition wall 21 and the valve stem 5
Since the center line of 7 is located on the same plane, the partition wall 2
The central passage side wall surface of No. 1 is biased to the side passage 5 side from the central passage side wall surface of the valve stem 57, and the fuel spray in the mixed air flow along the partition wall 21 in the central passage 4 is generated by the valve stem 57.
While being guided to the inner surface of the fuel cell, the fuel spray in the air-fuel mixture is concentrated in the vicinity of the spark plug 11 by being directed toward the spark plug 11, the ignition is favorably performed, and the lean limit can be further extended.

Particularly in this embodiment, as shown in FIGS. 7 and 9, in this structure, the upper half portions 46A-1, 46B-1 of the intake port portions 46A, 46B of the cross section of the substantially inverted triangle are sufficiently large. Since it is formed, a strong tumble flow in the combustion chamber 30 and a flow coefficient when the engine is fully opened can be secured.

Further, in this embodiment, the bulge 13 is provided on each curved portion of the intake port portions 46A, 46B where the actual flow cross-sectional area is the smallest, and the partition wall 21 serving as a flow resistance is provided on the downstream side of the valve stem 57. Since it is configured so as not to be provided, it is possible to more effectively secure the above-described strong tumble flow in the combustion chamber 30 and the flow rate count during the entire engine rotation.

Further, the construction in which the partition wall 21 is not provided on the downstream side of the valve stem 57 in the intake port portions 46A and 46B has a great advantage in the manufacturing method as described below. That is, if the partition wall 21 is provided also on the downstream side of the valve stem 57, a portion of the partition wall corresponding to the valve stem 57 needs to be drilled after the partition wall is cast. There is a possibility that it will occur, and since there is a cantilevered partition wall on the downstream side of the valve stem 57 in the intake ports 46A, 46B, there is a problem in that it is also unfavorable in terms of strength. However, in the present embodiment, as described above, the valve stem 57
Since there is no partition wall 21 on the downstream side, it is possible to avoid such a problem at all. Moreover, the valve stem 5
It has been confirmed that even if the downstream side partition wall 21 of No. 7 is not present, there is almost no effect on the stratification, and it is possible to provide a great advantage in manufacturing.

Here, FIG. 11 shows the port cross-sectional area and average tumble coefficient (rotation speed of tumble flow / engine rotation speed).
And the average flow rate coefficient (flow rate as a whole). Here, the line a shows the relationship between the port cross-sectional area and the average tumble ratio, the line b shows the relationship between the port cross-sectional area and the average flow coefficient, and the mark ■ indicates the intake port portion 4
Upper half portions 46A-1 and 46B-1 of the cross sections of 6A and 46B
Is an average flow coefficient of an engine having an intake port with a sufficiently large value.

Further, ○ indicates the average tumble ratio of the engine equipped with the intake port of the normal tumble flow, and ●
Is the upper half 46 of the intake port portions 46A and 46B.
Since A-1 and 46B-1 are 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.

As a result, the relationship between the tumble ratio and the flow coefficient becomes as shown in FIG. In FIG. 12, the triangle mark indicates an engine using a conventional tumble flow, and the star mark indicates a partition wall 2.
1 is provided, but the partition wall 21 reduces the cross-sectional area in the intake port portions 46A and 46B,
★ indicates the engine equipped with this structure and the intake port 46
The upper half portions 46A-1 and 46B-1 of the cross sections of A and 46B are sufficiently large. That is, as shown in FIG. 12, only by providing the partition wall 21 in the intake port portions 46A and 46B, the flow coefficient decreases even if stratification of the intake flow is promoted, and the full-open performance deteriorates. There is. Here, as indicated by the star, the intake port portion 46
Upper half portions 46A-1 and 46B-1 of the cross-sectional areas of A and 46B
Can be sufficiently increased to improve the tumble ratio and the flow coefficient. In this way, the partition wall 2
1, it is possible to compensate for the reduction in the cross-sectional area of the intake port portions 46A and 46B, and to secure a strong tumble flow in the combustion chamber 30 and a fully open performance of the engine.

FIG. 13 shows the rotational 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 are conventional. 3 is a graph showing the characteristics of an engine having the intake port structure of FIG. First, lines a and b show the relationship between the engine speed and torque, but there is almost no difference between these two curves, and the engine with this structure operates with a leaner mixture than before. Also shows that it achieves torque equivalent to that of a conventional engine.

The lines c and d show the relationship between the engine speed and the output. These lines c and d
Similar to the above-mentioned torque characteristics, there is almost no difference in the above, 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. 13, the engine having this structure has a large tumble ratio and a large flow coefficient in the intake port portions 46A and 46B, and as a result, an internal combustion engine having torque and output characteristics equivalent to those of the conventional engine is obtained. Can be realized.

As described above, the partition wall 21 is provided in the intake port 46, and the upper half portions 46A-1 and 46B-1 of the substantially triangular cross section of the intake port portions 46A and 46B are made sufficiently large. , without lowering than the output with conventional internal combustion engine, with the conventional stable combustion state lean mixture than the internal combustion engine can be coercive, it can reduce even the NO _X. At the same time, fuel efficiency can be improved.

Next, a modified example of the shape of the upper surface of the piston will be described with reference to FIGS. 14 and 15. The engine of FIGS. 1 and 3 of the first embodiment includes the piston 26 having the raised portion 37 as shown in FIGS. 4A and 4B. Instead of this piston, FIG. 14A is used. , (B) is used as the piston 26a.

The piston 26a shown in FIGS. 14A and 14B has a raised portion 37a on its upper surface. The apex 232 of the raised portion 37a is located on the intake opening side of the intake port 46 of the virtual plane FC on the top surface 34. The slope vf3 of the raised portion 37a on the virtual plane FC side is configured to smoothly continue to the upper surface of the piston 26a. The inclined surface vf3 is formed in a concave shape and is symmetrical with respect to a plane (center of the tumble flow F in the width direction) that is perpendicular to the virtual plane FC and includes the cylinder axis L.

In the modified example of FIGS. 14A and 14B, since the slope vf3 is concave as described above, the tumble flows Fa and Fm are directed from the upper surface of the piston 26a along the inner wall surface of the cylinder bore. When changing, all try to get close to the center of the tumble flow Fm. However, since the slope vf3 is symmetrical with respect to the center plane in the width direction of the tumble flow Fa, the layered state of the tumble flows Fa and Fm does not collapse.

The following modification employs a piston 26b as shown in FIGS. 15 (a) and 15 (b). Figure 15
The piston 26b of (a) and (b) has a recess 35 on its upper surface.
And a raised portion 37b. Of these, the top 232 of the raised portion 37b is located on the intake opening side of the intake port 46 of the virtual plane FC on the top surface 34. On the other hand, the recess 35 is located adjacent to the virtual plane FC side of the top surface 34. The slope vf4 of the raised portion 37b on the virtual plane FC side is formed by a set of straight lines parallel to the virtual line L1 orthogonal to the cylinder axial battle L on the virtual plane FC.

In the modified example of FIGS. 15 (a) and 15 (b), since the concave portion 35 is provided together with the raised portion 37b, the tumble flows Fa and Fm are arranged so as to extend from the inner wall surface of the cylinder bore to the top surface of the piston 26b. When the direction is changed to, the layered state of the tumble flows Fa and Fm can be kept clearer.

Here, FIG. 16 shows the characteristic of an engine with a conventional piston having a flat upper surface by the N line and the inner wall v of FIG.
The characteristic of the engine E on the upper surface of the piston having f1 is represented by the line A, and the concave portion 35 and the inner wall vf4 of FIGS.
The characteristic of the engine on the upper surface of the piston having is shown by C line. Here, the combustion stability, the indicated output, and the NO _X reduction rate are sequentially shown. In this test, the air-fuel ratio is changed by changing the air amount with a constant fuel amount, and the difference in the indicated output in this case indicates the difference in fuel consumption.

Here, the lean limit air-fuel ratio was improved by 1 in type A and 2 in type C as compared with the standard type. As a result, NO _X during the lean limit 50% Type A, is reduced to 16% type C.

Next, a modified example of the partition wall 21 in the intake port portions 46A and 46B will be described with reference to FIG. In this modification, instead of the partition wall 21, the intake port portion 46A,
The partition wall 21Q is provided only in the lower half of 46B. However, as described above, the injector 12 is arranged upstream of the branch portion 46C of the intake port 46 and downward from the intake port upper surface side. Since the fuel easily collects on the lower surface side of the intake port, the tumble flows Fa and Fm are sufficiently stratified by the central passage 4 and the side passages 5 even when installed on the relatively lower surface side of the intake port as in the partition wall 21Q. It is possible.

Next, a modification of the relationship between the arrangement and direction of the injector 12 and the partition wall 21 will be described with reference to FIGS. As shown in the axial direction 6 of the injector 12 in FIGS. 18 and 19, the injector 12 is installed in the intake port 46 from the lower side of the intake port 46A, 46B.
Fuel is injected diagonally upward and downstream. And
The fuel injected obliquely upward is sucked into the combustion chamber 30 through the intake passage 46 and the central passage 4 in the intake port portions 46A and 46B.

In FIG. 20, instead of the partition wall 21 of FIG. 19, a partition wall 21C is provided so as to hang down from the upper surface side of the intake port and only in the upper half portion. According to the modified examples shown in FIGS. 19 and 20, the fuel flows along the injector injection axis 6 and
In the tumble flow Fm of the air-fuel mixture that is injected toward the upper inner wall 8 and is formed in the vicinity of the spark plug 11, the spark plug 11 is more likely to flow than the flow inside the tumble flow center of the tumble flow Fm.
The flow outside the tumble flow center in the vicinity becomes a rich mixture. Therefore, leaner combustion can be more stably established.

Further, as shown in FIGS. 21 and 22,
The partition wall 21C includes an intake port 46, an intake port portion 46A,
It is provided on the upper half side of 46B. Only the upper half is divided into left and right. Furthermore, this partition 21C
Along the lower edge of the intake port 46, the intake port portion 46
A substantially horizontal partition wall 21F as an auxiliary wall is provided so as to divide A and 46B into upper and lower parts. Therefore, due to the partition wall 21F, the inside of the intake port portions 46A and 46B are in the upper half portions 46A-1 and 46B-1 and the lower half portion 46A-.
It is divided into 2,46B-2. Upper half 46A-
1, 46B-1 are divided into a central side (ignition plug side) passage 4 and a lateral (anti-ignition plug side) passage 5 by a partition wall 21C. And the injector 12
Is configured to inject fuel to a portion above the partition wall 21F in the central passage 4 of each intake port 46A, 46B. As a result, the outside of the tumble flow Fm of the air-fuel mixture becomes an air-fuel mixture having a high fuel concentration, and this air-fuel mixture is concentrated near the spark plug 11. Therefore, a stable combustion state is possible even with a leaner fuel.

23 to 25 are shown in FIGS.
An auxiliary partition wall 21G is provided in place of the auxiliary partition wall 21F shown in FIG. However, the injector 12 is arranged on the upper surface of the intake port 46 and on the upstream side of the branch portion 46C as in the first embodiment. The upstream end of the partition wall 21G is provided up to the vicinity of the position where the injector 12 is disposed, similarly to the partition wall 21C in the vertical direction. The horizontal partition wall 21 prevents the fuel injected from the injector 12 from diffusing downward in the intake port 46. That is, on the upstream side of the branch portion 46C of the intake port 46, the central passage 4 having a rectangular cross section as shown in FIG. That is, the inside of the intake port 46 is divided into the central passage 4 and the side passage 5. Further, on the downstream side of the branch portion 46C, the center side passage 4 is formed in the upper portion of the intake ports 46A, 46B on the reference surface 3 side. Due to this, the fuel injected downward toward the intake port portions 46A and 46B is prevented from flowing into the side passage 5 by the horizontal partition wall 21G provided inside the intake port portions 46A and 46B.
Then, the injected fuel is the upper half portion 46A-1, 46B-
1 into the central passage 4, and only the air flows into the side passage 5. Further, since the partition wall 21G extends from the upstream side to the downstream side of the position where the injector 12 is disposed, the fuel is reliably fed to the central passage 4 of the upper half portions 46A-1 and 46B-1 of the intake port portions 46A and 46B. Therefore, the outside of the tumble flow Fm of the air-fuel mixture becomes a fuel-rich air-fuel mixture, which is the spark plug 1
Concentrate in the vicinity of 1. As a result, the air-fuel mixture becomes 30 in the combustion chamber.
With this, it is possible to reliably ignite and burn, and it is possible to achieve a stable combustion state even with fuel leaner than in the past.

Next, a modified example relating to the injection of the injector 12 will be described with reference to FIGS. (A) is a branch portion 46C of the Siamese type intake port 46
The fuel is injected toward the front end of the intake port, and after the fuel is positively collided with the branch portion 46C, the diffused fuel is allowed to flow into the central passage 4 in the intake port portions 46A and 46B. The branch portion 46C of the intake port 46 has a positive collision surface that is substantially orthogonal to the injection direction of the injector 12, and diffuses the fuel that collides with this collision surface. .

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

(C) is a type in which 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, 21. is there. In this case, the branch portion 46C of the intake port 46 is configured so that the fuel is smoothly taken in with the intake air.
Is formed at an acute angle.

Contrary to the above-mentioned (c), (d) is a type using an injector which positively injects the fuel toward the wide angle up to the respective partition walls 21, 21. In this case, the branch 46C of the intake port 46 is rounded into a curved shape in the same manner as (b) above to reduce the resistance. In addition,
The above-mentioned (a) to (d) are modified examples of the injection related to the injector 12, and the disposition position of the injector 12 and the injection axis 6 are the same as those in the first embodiment.

Next, a modification of the arrangement of the valve stem 57 and the partition wall 21 will be described with reference to FIGS. 27 to 29. As described above, in the first embodiment of the present invention, the partition wall 21 is formed narrow as shown in FIG.
This is because the inner surface 121A of the partition wall 21 is
It is biased to the lateral passage 5 from the inner surface of 7. As a result, it is possible to obtain the effect that the fuel spray in the air-fuel mixture flowing along the surface 121A of the partition wall 21 is concentrated in the vicinity of the spark plug 11 in the direction shown by P in FIG.

In the arrangement shown in FIG. 27, in order to obtain the same effect as that of the first embodiment, the inner surface of the partition 121A is biased to the side passage 5 more than the inner surface of the valve stem 57, and the center of the partition 21 is adjusted. The line itself is also biased toward the side passage 5 side from the axis of the valve stem 57.

Arrangements as shown in FIGS. 28 and 29 are also possible. The upstream and intermediate portions of the partition walls 121B and 121C are biased outside the axis of the valve stem 57. Then, the downstream portions 122 of the partition walls 121B and 121C,
Ignition means side partition wall (inner wall surface) 122a, 1 in 123
23a is inclined toward the center so that the intake flow on the central passage side 4 is directed to the ignition plug 11 side. In this case, the intake flow is directed toward the spark plug 11 side more smoothly, the lean combustion of the engine can be further promoted, and it is extremely effective for the stratified combustion engine. In the example shown in FIG. 28, only the inner wall surface 122a of the partition wall 121B is bent, and the outer wall surface of the partition wall 121B is flat. Further, in the example shown in FIG. 29, the thickness of the partition wall 121C is set to be substantially constant over its entire length, and the outer wall surface as well as the inner wall surface 122a of the partition wall 121B is formed to be bent.

In this way, at least the inner side surface of the partition wall is biased to the side passage side slightly from the inner side surface of the valve stem 57, or the inner wall surface at the downstream end of the partition wall is inclined toward the central passage side. The fuel spray in the air-fuel mixture flowing along the inner wall surface of the partition wall can be concentrated on the spark plug side. The degree of concentration of the air-fuel mixture on the ignition plug side can be adjusted, for example, according to the biased state of the inner wall surface 121A and the inclined state of the inner wall surfaces 122A and 123A itself.

Next, as a variation of the partition wall structure with respect to the direction of the intake flow flowing into the intake port 46, FIG.
It will be described using 0. In the first embodiment, the inner wall and the outer wall of the partition wall 21 are set substantially parallel to each other. This is a simplified shape in consideration of manufacturing. Considering that the flow of the intake air flowing in the intake port portions 46A and 46B is rectified to prevent the disturbance of the intake air flow in the portion of the valve stem 57, as shown in FIG. It is preferable that the thickness is made thinner toward the upstream side, and the upstream end portion 21A is made as thin as possible.
As the valve stem 57 on the further downstream side is approached,
It is preferable that the valve stem 57 is gradually formed to have a thickness substantially equal to the outer diameter of the valve stem 57. By doing this,
The flow of the intake air flow can smoothly flow into the combustion chamber 30 without being disturbed by the partition wall 21 and the valve stem 57.

Next, the intake port 46 and the intake port 4
A modified example of the intake manifold 14 connected to the upstream side of No. 6 will be described with reference to FIGS. 31 to 33. As described above, in the first embodiment of the present invention, the intake port portion 46A,
The upper half 46A-1 and 46B-1 of 46B are the lower half 46
It is wider than A-2 and 46B-2. However, by further improving the shape of the intake manifold connected to the upstream side of the intake port 46, stronger tumble flows Fa and Fm can be obtained in the combustion chamber 30.

In FIG. 31, reference numeral 14 is an intake manifold fixed to the side surface 28A of the cylinder head 28 and connected to the upstream end of the intake port 46. The sectional shape of each part of the intake port 46 and the intake manifold 14 is configured as shown in FIG. That is,
In this intake manifold 14, each intake port portion 46
So that the intake air flows smoothly into A and 46B (that is,
32 (a)-(not to decrease the flow rate of intake air)
As shown in (c), the cross-sectional shape is gradually changed from the upstream side to the downstream side, and the intake passage portion 14A,
On the most downstream side (FIG. 32 (c)) connected to 14B,
Intake port portions 46A, 46B and intake manifold 14
Are formed so that their cross-sectional shapes substantially match.

That is, inside the intake manifold 14,
With the two intake passage portions 14A and 14B, the upper half portions 14A-1 and 14B-1 are connected to the lower half portions 14A-2 and 14B as they go downstream, similarly to the cross-sectional shapes of the intake port portions 46A and 46B. It is formed to have an eccentric shape that is relatively wider than -2.

As a result, the intake air is supplied to the intake manifold 1
Since the intake flow center 45 is eccentric to the upper half portions 14A-1 and 14B-1 and flows into the intake port portions 46A and 46B in the two intake passages 14A and 14B within the intake manifold 4, the intake port portions 46A and 46B It is designed to further promote the formation of tumble flow.

Further, in the first embodiment, the partition wall is provided only in the intake port, but as shown in FIG. 33, the partition wall 15 which divides each of the intake passage portions 14A and 14B into the left and right directions in the intake manifold 14, It is also possible to provide 15. The partition wall 15 is provided from the upper end to the lower end of each intake passage portion 14A, 14B, so that in each intake passage portion 14A, 14B, this side passage with respect to the central passage 4'of the intake flow is provided. It is divided into 5 '. The partition wall 15 is located at the downstream end of the intake manifold 14, that is, the intake port portions 46A, 46.
It is provided up to the vicinity of the joint surface with B, and the partition wall 15 separates the intake flow into the central passages 4, 4'and the side passages 5, 5'in the intake manifold 14 and the intake port portion 46A. . As a result, the intake air flow branched into the central passages 4, 4'and the side passages 5, 5'is completely separated into the air-fuel mixture and the air, and the tumble flows Fa, Fm in the combustion chamber 30 are separated.
The layering of can be further enhanced.

Next, the second embodiment of the present invention applied to an engine having a plurality of intake ports without partition walls in the intake ports.
An example will be described with reference to FIGS. 34 to 36. FIG. 34 shows
2 shows a stratified combustion internal combustion engine according to the second embodiment, in which the top surface shape of a piston 26 and an intake port 46A,
The structure is basically the same as that of the layered combustion internal combustion engine shown in FIGS. 37 and 38 except for the shape of 46B.

As the shape of the top surface of the piston 26, the shape shown in FIGS. 1 and 4 or the shape shown in FIG. 15 can be adopted. Intake port 46A, 46
The cross-sectional shape of B is, as shown in FIGS. 34 and 35,
The upper half has a substantially inverted triangular shape in which the upper half is wider than the lower half. The intake ports 46A, 46B have a substantially straight shape as a whole, and are largely curved near the intake opening end to the combustion chamber 30. As shown in FIG. 36, the curved portion is provided with a bulge having an inner diameter larger than the intake openings of the intake ports 46A and 46B mainly in the upper half portion thereof.

As a result, the air-fuel mixture from the intake port 46A and the air from the intake port 46B flow into the combustion chamber 30 while forming a sufficient tumble flow for lean combustion and at the same time ensuring a sufficient intake flow rate. It is possible to improve the combustion stability, the combustion efficiency, and the output compared with the conventional lean-burn internal combustion engine.

In all the above-mentioned embodiments, the tumble flow Fm of the air-fuel mixture and the tumble flow Fa of air are generated in the combustion chamber 30. However, the present invention is not limited to this. For example, instead of the tumble flow Fa of air, a fuel is also supplied to the tumble flow Fa so that a tumble flow Fa 'having a smaller air-fuel ratio than the tumble flow Fm is generated. It is also possible to configure.

[0084]

[Effect] The present invention can secure a sufficient intake amount without deteriorating the function of directing the intake air flow into the combustion chamber, can generate a stronger tumble flow in the combustion chamber, and can further increase the fuel concentration in the combustion chamber. A layered tumble flow that is a tumble flow and a thin tumble flow can be generated in a more complete layered form.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a stratified combustion internal combustion engine as one embodiment of the present invention.

FIG. 2 is a schematic top view showing a main configuration of an intake port,
FIG. 2 is a view on arrow A in FIG. 1.

3 is a schematic side view showing a configuration of a main part of a combustion chamber, and is a view taken along an arrow A ′ in FIG. 1. FIG.

FIG. 4 is a schematic perspective view showing a top surface shape of a piston in detail.

5 is a schematic partial cross-sectional view showing the configuration of the intake port structure, which is a cross-sectional view taken along line CC of FIG.

FIG. 6 is a schematic top view showing the configuration in the combustion chamber, and is a view taken in the direction of arrow A in FIG.

FIG. 7 is a schematic diagram showing the configuration of an intake port structure and is a view taken in the direction of arrow A ′ in FIG.

8 is a schematic diagram showing a configuration of an intake port structure, and views (b) to (g) taken in the direction of arrow H in FIG. 1 are cross-sectional views from the S1-S1 cross section to the S6-S6 cross section in FIG. 7, respectively. .

9 is a schematic view showing an intake port structure and is a sectional view taken along line BB in FIG.

FIG. 10 is a graph showing the effect of the intake port structure of the present invention.

FIG. 11 is a graph showing the effect of the intake port structure of the present invention.

FIG. 12 is a graph showing the effect of the intake port structure of the present invention.

FIG. 13 is a graph showing the effect of the intake port structure of the present invention.

FIG. 14 is a schematic perspective view showing in detail the shape of the top surface of the piston, which is a modification of FIG.

FIG. 15 is a schematic perspective view showing the shape of the top surface of the piston in detail, which is a modification of FIG.

FIG. 16 is a graph showing the effect of the piston top surface shape of the present invention.

FIG. 17 is a schematic diagram showing the configuration of the intake port structure of the present invention, which is a modification of FIG.

FIG. 18 is a schematic perspective view showing a configuration of a layered combustion internal combustion engine, which is a modification of FIG. 1.

19 is a schematic partial cross-sectional view showing the intake port structure of the embodiment shown in FIG. 18, and is a view corresponding to FIG. 5.

20 is a schematic partial cross-sectional view showing a modified example of the intake port structure shown in FIG.

21 is a schematic partial cross-sectional view showing a modified example of the intake port structure shown in FIG.

22 is a schematic partial sectional view of the intake port structure shown in FIG. 21, and is a sectional view taken along line XXII-XXII of FIG. 21.

FIG. 23 is a schematic perspective view showing a modified example of the configuration of the layered combustion internal combustion engine, and is a diagram corresponding to FIG. 1.

24 is a schematic partial cross-sectional view showing the configuration of the intake port structure of the modification example shown in FIG. 23, taken along line X- in FIG.
It is an X sectional view.

FIG. 25 is a schematic partial cross-sectional view showing the configuration of the intake port structure cormorant of the modified example shown in FIG. 23, where X in FIG.
It is an XV-XXV sectional view.

FIG. 26 is a schematic diagram showing types of fuel injection in the intake port.

FIG. 27 is a schematic view showing a modified example of the partition structure of the intake port structure of the present invention.

FIG. 28 is a schematic view showing a modified example of the partition structure of the intake port structure of the present invention.

FIG. 29 is a schematic view showing a modified example of the partition structure of the intake port structure of the present invention.

FIG. 30 is a schematic view showing a modified example of the partition structure of the intake port structure of the present invention.

FIG. 31 is a schematic view showing an intake passage structure of the present invention,
It is a modification of FIG.

FIG. 32 is a schematic view showing an intake passage structure of the present invention,
It is the R1-R1-R6-R6 cross section and GG cross section of FIG.

FIG. 33 is a schematic view showing a modified example of the intake passage structure of the present invention, and is a view corresponding to FIG. 32 (c).

FIG. 34 is a schematic perspective view showing a stratified combustion internal combustion engine as a second embodiment in which the present invention is applied to another intake port structure having no partition wall.

FIG. 35 is a schematic partial cross-sectional view showing a stratified combustion internal combustion engine as a second embodiment of the present invention, which is XX in FIG. 34.
It is an XV-XXXV sectional view.

FIG. 36 is a schematic top view in which the present invention is applied to another intake port structure having no partition wall.

FIG. 37 is a schematic perspective view showing a conventional stratified combustion internal combustion engine.

FIG. 38 is a schematic sectional view showing a conventional stratified combustion internal combustion engine.

[Explanation of symbols]

 1A Shaft center line of the intake port 46A 1B Shaft center line of the intake port 46B 4 Central passage 5 Side passage 6 Injection axis 11 Spark plug 12 Injector 13 Bulge 21 Partition 21A Upstream end of partition 21 21B Downstream end of partition 21 22 Cylinder block 24 Cylinder 26 Piston 28 Cylinder head 30 Combustion chamber 34 Piston top surface 37 Raised part 39 Valve recess 46 Intake port 46A, 46B Intake port part 46-1 Intake port upper part 46A-1, 46B-1 Intake port part upper part 46-2 Lower part of intake port 46A-2, 46B-2 Lower part of intake port 46C Intake port branch part 47 Exhaust port 57 Valve stem 58 Intake valve 60 Cylinder head lower surface 60a, 60B Cylinder head lower surface slope 61 Exhaust valve 121A Central passage of partition wall 21 Surface 232 ridge peak vf1 slope vf2 outer slope FC virtual plane SF squish L1 imaginary line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Takemura 5-3-8 Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (72) Inventor Taizo Kitada 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Automobile Industry Co., Ltd. (72) Inventor Yoshio Akishino 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Yasuki Tamura 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation Co., Ltd. (72) Inventor Michihiro Hata 5-3-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Hichiichi Iwachi, 5-33-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation Stock In-house (72) Inventor Masayuki Motomochi 5-3-8, Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Shunsuke Matsuo 5-33-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Motor Co., Ltd. (72) Inventor Nobuaki Murakami 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Keizo Furukawa 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation Within the corporation

Claims (7)

[Claims] 1. A combustion chamber defined by an inner surface of a cylinder and an upper surface of a piston fitted into the cylinder and a lower surface of a cylinder head, and an intake port having an intake opening provided on the lower surface of the cylinder head and opened and closed by an intake valve. With and
In an internal combustion engine having a curved portion in which the intake port is curved near the intake opening with a curvature larger than that on the upstream side, the curved portion near the intake opening in the intake port is an inner wall of the intake opening. An internal combustion engine having a bulge having an inner diameter larger than that of the internal combustion engine. 2. The intake opening of the intake port is provided on one side of a virtual plane including the axis of the cylinder, and the intake port allows intake air to flow from the intake opening toward the other side of the virtual plane. The internal combustion engine according to claim 1, wherein a substantially straight-shaped portion for directing an intake air flow is provided upstream of the curved portion to generate a tumble flow in the combustion chamber. . 3. The intake port is characterized in that the upper portion is substantially wider than the lower portion in a cross section orthogonal to the intake streamline, whereby the intake flow center of the intake port is eccentric to the upper portion. The internal combustion engine according to claim 2. 4. The internal combustion engine according to claim 3, wherein the bulge is formed by further widening the upper portion of the curved portion of the intake port. 5. The internal combustion engine according to claim 3, wherein the intake port has a substantially inverted triangular shape in a cross section orthogonal to the intake streamline. 6. A combustion chamber defined by an inner surface of the cylinder and an upper surface of a piston fitted into the cylinder and a lower surface of the cylinder head, and the combustion chamber is arranged on one side of a virtual plane including a cylinder axis of the cylinder head. The intake air is opened and closed by an intake valve, and the virtual air flows from the intake opening along the lower surface of the cylinder head so that the intake air generates tumble flows that are parallel to each other and substantially in the same direction in almost the entire combustion chamber. A plurality of intake ports for inflowing intake air toward the other side of the plane; an ignition plug provided at a position corresponding to an intake flow inflowing from one of the intake ports on the inner surface of the combustion chamber; The fuel is supplied to one of the intake ports corresponding to the position, thereby creating a stratified tumble flow in the combustion chamber during the intake stroke. A plurality of intake ports, wherein the plurality of intake ports include a directing portion for directing intake air flowing into the combustion chamber, and a curve connecting a downstream end of the directing portion and the intake opening. Internal combustion engine, wherein the curved portion has a bulge having an inner diameter larger than the inner diameter of the intake opening. 7. A combustion chamber defined by an inner surface of the cylinder and an upper surface of a piston fitted into the cylinder and a lower surface of the cylinder head, and the combustion chamber is disposed on one side of an imaginary plane including the cylinder axis of the cylinder head. An intake opening that is opened and closed by an intake valve is provided, and the intake air forms a tumble flow that is parallel and in the same direction in almost the entire combustion chamber. Two intake ports for inflowing intake air toward the other side, vertical partition walls partitioning at least one of the intake ports into a plurality of passages, and a position corresponding to at least one of the passages on the inner surface of the combustion chamber. Fuel is supplied to the provided spark plug and the passage corresponding to the position of the spark plug, whereby the combustion is performed in the intake stroke. A fuel supply means for generating a stratified tumble flow therein, wherein the two intake ports have a directing portion for directing intake air flowing into the combustion chamber, and a downstream end of the directing portion. An internal combustion engine having a bulge having a larger inner diameter than the inner diameter of the intake opening.