JPH0979040A - Cylinder injection type internal combustion engine - Google Patents

Abstract

(57) Abstract: The present invention relates to a cylinder injection type internal combustion engine that directly injects fuel into a combustion chamber, and makes it possible to form a vertical vortex flow of sufficient strength. SOLUTION: A combustion chamber 7, an intake opening end 4A opening to the combustion chamber 7, an intake port 4 extending upward from the intake opening end 4A, an exhaust port 5 communicating with the combustion chamber 7, and a combustion chamber 7
Of the intake port 4 in order to promote the formation of the longitudinal vortex flow TF, and the intake flow is configured to form the longitudinal vortex flow TF in the cylinder 3A. The half portion on the reference surface 40 side is wider than the other half portion so that the intake flow center of the intake port 4 is eccentric to the half portion on the reference surface 40 side. Is formed so as to smoothly guide the intake air flow from the intake opening end 4A to the cylinder side wall 1A side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder injection type internal combustion engine for directly injecting fuel into a combustion chamber, and more particularly to a cylinder injection type internal combustion engine for burning a lean mixture in a stable state. Regarding

[0002]

2. Description of the Related Art Conventionally, in a diesel engine which mainly uses light oil as a fuel among internal combustion engines, fuel is directly injected into a combustion chamber, and this fuel is spontaneously ignited by compressed air in the combustion chamber to obtain power. There is. In addition, as for a gasoline engine, various cylinder injection type gasoline engines have been proposed in which fuel is directly injected into a combustion chamber to improve the responsiveness of the engine.

The following is a brief description of the specific construction of such a cylinder injection type gasoline engine. The cylinder injection gasoline engine requires an ignition plug as an ignition means, and the ignition plug is arranged in the combustion chamber. Set up. The injector is provided, for example, in the cylinder head on the intake valve side.

Even in such a cylinder injection type internal combustion engine, it is desired to improve the fuel efficiency of the engine by forming a spiral intake flow in the combustion chamber to perform lean combustion with a fuel leaner than the theoretical mixture. Therefore, in order to form such a spiral intake flow, the intake flow from the intake port is taken in as parallel as possible to the piston top surface, and thereafter, this intake flow is directed downward along the cylinder inner wall. A structure has been proposed in which a spiral intake air flow is generated.

However, in order to generate a swirling intake flow using such a structure, it is necessary to dispose the intake port as parallel to the upper surface of the cylinder head as possible, and in the cylinder injection type internal combustion engine, the injector is used. Can not be secured enough. Therefore, for example, as in the technique disclosed in JP-A-6-146886, it is possible to form a strong vertical vortex flow (tumble flow) in the combustion chamber to stably operate the engine even with lean combustion. Conceivable.

[0006]

However, such a conventional technique has a problem that it becomes difficult to form a tumble flow having a sufficient strength when the volume of the combustion chamber becomes large to some extent. That is, when the volume of the combustion chamber becomes large, the intake flow drawn into the cylinder also becomes strong. However, as shown in FIG. 9, when the intake flow flows from the intake port 4 into the cylinder 1A, the intake flow is increased. Collides with the umbrella portion 62 of the intake valve 61, and intake air flows to both sides of the umbrella portion 62. Therefore, the intake valve 61 itself becomes an intake resistance, which becomes a hindrance factor when the vertical vortex flow is generated in the cylinder 1A.

The present invention was devised in view of the above problems, and by significantly reducing the intake resistance due to the intake valve, the intake flow smoothly flows into the cylinder, and the vertical vortex flow of sufficient strength is obtained. It is an object of the present invention to provide a cylinder injection internal combustion engine capable of forming a cylinder.

[0008]

For this reason, in the cylinder injection type internal combustion engine of the present invention as defined in claim 1, the combustion formed between the upper surface of the piston fitted in the cylinder and the lower surface of the cylinder head. A chamber, an intake opening end that opens to the combustion chamber on one side of a reference plane that includes the central axis of the cylinder, an intake port that extends upward from the intake opening end, and an intake port that is located on the other side of the reference plane. An exhaust port formed in the cylinder head and communicating with the combustion chamber via an opening / closing valve, and a side portion of the combustion chamber on the intake port side, the injection port is disposed so as to face the combustion chamber. An intake flow, which is provided with an injector and is introduced into the combustion chamber by the intake port, is directed toward the upper surface of the piston from the lower surface of the cylinder head on one side of the reference surface along the central axis direction. From the top of the piston on the other side of It is configured to form a longitudinal vortex flow having a streamline toward the lower surface of the Linda head, and in order to promote the formation of the longitudinal vortex flow, the reference surface side half of the intake port is wider than the other half. The intake flow center of the intake port is eccentric to the reference surface side half portion, and the intake flow of the intake port is supplied to the reference surface side half portion near the intake opening end of the intake port from the intake opening end. It is characterized in that a guide portion that smoothly guides to the side wall of the cylinder is formed.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the in-cylinder injection type internal combustion engine of the present invention has a cross-sectional shape of the intake port which is approximately a semicircle near the intake opening end. It is characterized in that it is formed in a shape. Further, the cylinder injection type internal combustion engine of the present invention according to claim 3 is the above-mentioned claim 1.
In addition to the described structure, the cross-sectional shape of the intake port is formed in a substantially triangular shape in the vicinity of the intake opening end.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A cylinder injection type internal combustion engine according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows its main part and shows the flow of intake air. 2 is a schematic view showing the internal structure, FIG. 3 is a front view showing the intake port, and FIG.
Is a diagram showing a cross-sectional shape of the intake port, FIG. 5 is a schematic overall perspective view showing its configuration, FIG. 6 is a diagram for explaining its operating state, FIG. 7 is a diagram for explaining its characteristics, FIG. 8 is a view showing a modified example thereof and is a view showing another example of the sectional shape of the intake port.

First, the overall structure of the cylinder injection type internal combustion engine will be described. The cylinder head of the internal combustion engine is a four-valve internal combustion engine in which each cylinder has two intake valves and two exhaust valves. ing.

As shown in FIGS. 2 and 5, a combustion chamber 7 is formed between the piston 2 and the cylinder head 1. The cylinder head 1 of the combustion chamber 7 has an intake port as an intake passage. 4 and an exhaust port 5 as an exhaust passage are connected to each other. In addition, these intake and exhaust ports 4,
An intake valve 61 and an exhaust valve (not shown) are installed in each of the combustion chamber openings 4A and 5A of No. 5, and the combustion chamber openings 4A and 5A are opened and closed by these intake and exhaust valves. Reference numerals 51 and 52 shown in FIG. 2 indicate valve stems of the intake and exhaust valves.

As shown in FIG. 5, the combustion chamber 7 has one of the reference planes 40 with a virtual plane that includes the central axis 42 of the cylinder 3A and the axis of the crankshaft (not shown) as a reference plane 40. Is provided with two intake ports 4 and two exhaust ports 5 are provided on the other side of the reference surface 40.
(See FIG. 2). Further, as shown in FIG. 2, the spark plug 20 is arranged at the center of the top of the combustion chamber 7 (that is, on the reference surface 40) or in the vicinity thereof.

Further, as shown in FIGS. 1 to 3 and 5,
Each intake port 4 described above is provided so as to be substantially upright from the cylinder head 1, and as shown in FIGS. 1 and 2, the opening 4A of each intake port 4 is attached to the mounting surface of the cylinder head 1. It is arranged slightly inclined. Therefore, the upper portion of the combustion chamber 7 of this engine on the intake valve side has a pent roof shape.

Further, as shown in FIGS. 5 and 6, an injector 18 for supplying fuel to the combustion chamber 7 is arranged on the intake port 4 side of the cylinder head 1. The injector 18 is provided with an injection hole 18A at its tip end facing the inside of the combustion chamber 7 so that fuel is directly injected into the combustion chamber 7.

The injector 18 is, for example,
The controller is controlled by a controller (not shown), so that a predetermined amount of fuel is injected at a predetermined injection timing. Here, the attaching portion of the injector 18 will be described.
The intake port 4 of the book is connected to the cylinder head 1 as described above.
Since it is provided substantially vertically upward, a sufficient space for mounting the injector 18 around the opening 4A of the intake port 4 can be secured.
Therefore, the degree of freedom in setting the positional relationship with the ignition plug 20 is large, and the injector 18 can be installed at the optimal arrangement position for fuel injection.

By the way, as described above, the piston 2 is fitted in the cylinder 3A, and a recess (curved portion) 2A as shown in FIG. 5 is formed at the top of the piston 2. There is. The recess 2A is provided in a portion of the top of the piston 2 below the intake port 4, and is formed in a downward curved convex curved surface. That is, this recess 2A
Is provided at a position eccentric to the intake port 4 side with respect to the reference surface 40, and is formed, for example, in a spherical shape curved downward in a convex shape.

On the lower side of the exhaust port 5 of the top of the piston 2, there is formed an exhaust valve side upper surface 2B which is close to the recess 2A and is raised more than the recess 2A. The upper side surface 2B is connected to the recess 2A. As a result, as shown in FIG. 6, when the piston 2 reaches the end of the compression stroke, the recess 2A of the piston 2 and the cylinder inner wall 1A.
A compact combustion chamber 7A surrounded by the cylinder head 1 is formed.

Now, the main part of the present invention will be explained here. In the in-cylinder injection type internal combustion engine, as shown in FIGS. 1 and 4 (a), a part of each intake port 4 has a substantially semicircular cross section. Is formed. As shown in FIGS. 4 (a) to 4 (i), the intake port 4 having a substantially triangular cross section has a different shape from the semicircular shape on the upstream side, and the downstream side on the downstream side. It is formed to have a substantially semicircular shape as it gets closer. Further, the respective cross-sectional shapes shown in FIGS. 4A to 4I are formed so as to be connected smoothly, so that the flow of the intake air flow is not hindered.

As shown in FIG. 4 (a), the intake port 4 is formed in a substantially semicircular shape in the vicinity of the intake opening 4A of the intake port 4. The reference surface side half portion 40 is formed so as to be wider than the other half portion. Specifically, the linear portion of the semicircle (the widened portion) is formed on the center side of the cylinder 3A, and the arcuate portion of the semicircle is formed on the side wall of the cylinder 3A. -ing

On the other hand, as shown in FIGS. 1, 2 and 6, in the half of the reference port 40 near the intake opening end 4A of the intake port 4, the intake flow flowing through the intake port 4 is introduced into the intake opening end. A raised portion 60 is formed as a guide portion that smoothly guides from 4A toward the cylinder inner wall 1A side.
The ridge 60 has a direction in which the reference surface 40 overlaps the cylinder center axis 42 and appears as one line (that is, the state of FIG. 1).
As seen from the above, it is formed as a jump table that is slightly warped toward the cylinder center axis 42 side, and collects the flow of intake air in a direction away from the cylinder center 42 of the intake port 4.

This raised portion 60 will be described in more detail. In the raised portion 60, the intake flow center in the intake port 4 is eccentric from the cylinder center axis 42 side to the cylinder inner wall side 1A in the vicinity of the intake opening end 4A of the intake port 4. It is provided to do so. Further, as described above, in the vicinity of the intake opening end 4A in the intake port 4, since the cross section of the intake port 4 is formed in a substantially semicircular shape in which the center side of the cylinder 3A is widened, it has passed through the intake port 4. The inspiratory flow is
The cylinder 3 of the intake port 4 near the intake opening end 4A
A large amount of the intake air flows to the center side of A (that is, the reference surface side half portion 40 side).

In addition to this, by providing the above-mentioned raised portion 60 in the vicinity of the intake opening end 4A, the flow of intake air is guided to the raised portion 60 in the vicinity of the intake opening end 4A, and the cylinder center of the intake port 4 is guided. It is eccentric from the axis 42 side to the cylinder inner wall 1A side. Then, the intake air flows toward the intake opening 4A with the angle change in this way, so that when the intake valve 61 is opened, the intake air flows into the combustion chamber 7 from the cylinder inner wall 1A side of the intake opening 4A. . As a result, the angle of incidence of the intake air flow on the valve head portion 62 during intake becomes an acute angle, and the intake resistance at the valve head portion 62 is greatly reduced.

Further, the intake opening 4A has the pent roof shape as described above, and since the umbrella portion 62 of the intake valve 61 is arranged so that the cylinder center axis 42 side is upward, the intake flow valve 4A is further expanded. The incident angle with respect to the umbrella portion 62 becomes an acute angle. As a result, as shown in FIG. 1, when the intake valve 61 is opened, most of the intake flow in the intake port 4 smoothly enters between the umbrella portion 62 of the intake valve 61 and the intake opening end 4A, This prevents the intake flow from directly colliding with the umbrella portion 62 of the intake valve 61 and disturbing the intake flow.

The intake air is prevented from flowing in from the cylinder center 42 side of the intake valve 4, and the combustion chamber 7
Since a strong intake flow flows in from the side close to the cylinder inner wall 1A, a strong vertical vortex (tumble flow TF) can be formed in the cylinder 3A in the clockwise direction in FIG. And after that, the piston 2 as described above
The formation of the vertical vortex (tumble flow TF) is promoted by the recess 2A.

On the other hand, as shown in FIG. 6, the upper surface 2B of the piston 2 on the exhaust valve side and the upper exhaust port 5 of the combustion chamber 7
A squish area 2C is formed between the side and the side. As a result, as shown in FIGS. 2, 5 and 6, after the intake flow flowing from the intake port 4 flows toward the lower piston 2, it is guided upward along the recess 2A of the piston 2. They flow and form a tumble flow TF.
Therefore, in the combustion chamber 7, the intake air flow promotes the formation of the tumble flow TF along the recess 2A.

Moreover, at this time, the squish SF as shown in FIG. 6 is generated in the flow toward the spark plug 20 due to the squish area 2C. The squish SF is a flow that is guided to the exhaust valve side upper surface 2B and the upper surface of the combustion chamber 7 and heads toward the center of the top of the combustion chamber 7. Then, the squish SF and the tumble flow TF collide with each other to strengthen the flow of the air-fuel mixture.

Since the cylinder injection type internal combustion engine as one embodiment of the present invention is constructed as described above, in the intake stroke of the engine, intake air flows from each intake port 4 to the opening of the intake port 4. It flows into the combustion chamber 7 through 4A. Further, the fuel is directly injected into the combustion chamber 7 through the injection hole 18A of the injector 18. Also, the injector 1
Since 8 is controlled by a controller (not shown), the fuel is injected from the injector 18 at an appropriate timing and mixed with the inhaled air to generate an air-fuel mixture.

At this time, since the intake port 4 is provided substantially upright, the intake flow flowing into the combustion chamber 7 goes downward (toward the piston 2). Further, as shown in FIG. 6, in the vicinity of the intake opening end 4A in the intake port 4, since the cross section of the intake port 4 is formed in a substantially semicircular shape in which the center side of the cylinder 3A is widened, the intake port 4 passes through the inside of the intake port 4. The intake air flow that has arrived is near the center of the intake port 4 in the cylinder 3A of the intake port 4 (that is, the reference surface side half portion 40).
A lot of intake flow passes to the side).

Further, by providing the raised portion 60 in the vicinity of the intake opening end 4A, the flow of the intake air is guided to the raised portion 60 in the vicinity of the intake opening end 4A and the cylinder from the cylinder center axis 42 side of the intake port 4 to the cylinder. It is eccentric to the inner wall 1A side. Then, since the intake air flow is directed to the intake opening 4A with the angle change in this way, the incident angle of the intake air flow with respect to the valve umbrella portion 62 becomes an acute angle, and the intake resistance at the valve umbrella portion 62 is greatly reduced. Become.

Further, the cylinder head 1 has a pent roof shape, and the umbrella portion 62 of the intake valve 61 has the cylinder center axis line 42.
By arranging so that the side is upward, the incident angle of the intake air flow with respect to the valve head portion 62 becomes more acute. This allows
The intake resistance by the intake valve 61 is significantly reduced, and a strong intake flow can be introduced from the side of the combustion chamber 7 near the cylinder inner wall 1A.

On the other hand, the intake air flow that has flowed downward from above the combustion chamber 7 collides with the recess 2A at the top of the piston 2 and is directed upwards of the combustion chamber 7 along the curved surface of this recess 2A. change.

The intake port opening 4A is provided on one side of the cylinder head 1 partitioned by the reference surface 40, and the recess 2A is provided below the opening 4A so as to face the opening 4A. Therefore, the intake flow is in the recess 2
While flowing toward the cylinder inner wall 1A side of A, the tumble flow TF is formed by being guided by the curved surface of the recess 2A and flowing upward along the recess 2A toward the vicinity of the center of the top surface of the cylinder 3A.

Thereafter, the intake flow is mixed with the fuel injected by the injector 18 in the combustion chamber 7, compressed and expanded (explosed) in the combustion chamber 7, and then discharged from the exhaust port 5. Now, as described above, the half portion of the intake port 4 which is substantially upright on the side of the reference surface 40 is formed to have a substantially semicircular shape which is wider than the other half portion, and the opening portion 4A of the intake port 4 is formed.
By providing the raised portion 60 that eccentrically moves the intake air flow toward the cylinder inner wall 1A side in the vicinity, when the intake air flow flows into the cylinder, the intake resistance caused by the collision of the intake air flow with the intake valve umbrella portion 62 is significantly increased. Since it can be reduced, a stronger tumble flow TF can be formed.
As a result, a strong intake flow will flow into the cylinder 3A from the side of the intake opening end 4A away from the cylinder center 43 (cylinder inner wall 3A side). When such a strong intake flow enters the cylinder 1A, Since the tumble flow TF is strengthened, the tumble flow TF can be sufficiently formed even in an engine having a large combustion chamber volume.

Further, by forming the tumble flow TF in this way, it becomes possible to operate the engine with a mixture of fuel in an amount smaller than the theoretical air-fuel ratio without deteriorating the ignitability. Further, due to the tumble flow TF, the air-fuel mixture reaches the vicinity of the ignition plug 20 provided at the center of the top of the combustion chamber 7 while being sufficiently stirred,
The ignitability can be improved and a stable combustion state can be obtained.

Further, by making the intake port 4 substantially upright, a sufficient space for mounting the injector 18 in the cylinder head 1 is secured, and the degree of freedom in mounting the injector 18 is increased. As a result, the injector 1 is arranged at a position suitable for directly injecting fuel into the combustion chamber 7.
8 can be attached. When the flow coefficient and tumble ratio of the direct injection internal combustion engine are compared with those of the conventional one, the characteristics shown in FIG. 7 are obtained. Here, the line a shown in FIG. 7 shows the characteristic of the cylinder injection type internal combustion engine of the present invention, and the line b shows the characteristic of the cylinder injection type internal combustion engine having the conventional intake port.

As shown in FIG. 7, according to the in-cylinder injection type internal combustion engine of the present invention, the flow coefficient hardly changes as compared with the conventional one, but the tumble ratio is greatly improved. In particular, this improvement in the tumble ratio is due to the intake valve 4
It can be seen that it becomes remarkable when the valve lift amount of is large. Next, a modified example of the embodiment of the present invention will be described. In the cylinder injection type internal combustion engine of this modified example, only the cross-sectional shape of the intake port is different from the above-described embodiment, and other than that, the above-described embodiment is performed. It is configured in the same manner as the form.

That is, in this modified example, FIG.
As shown in (j), each intake port 4 is formed to have a substantially triangular cross section as it approaches the downstream side. Further, each cross-sectional shape shown in FIGS. 8A to 8I is formed so as to change smoothly, so that the flow of the intake air flow is not obstructed. This triangular cross section is formed so that the reference surface side half portion 40 of the intake port 4 is wider than the other half portion, as in the above embodiment. That is, the base portion (the widened portion) of the triangular cross section is formed on the center side of the cylinder 3A, and is formed on the side wall side of the other half cylinder 3A having a small cross-sectional area.

In addition, in the half of the reference surface side 40 in the vicinity of the intake opening end 4A of the intake port 4, the intake port 4 is also provided.
The intake air flow that flows inside is introduced from the intake opening end 4A into the cylinder inner wall 1
A raised portion 60 that smoothly guides toward the A side is formed. In the IA-IA cross section shown in FIG. 8A, the raised portion 60 appears on the left side in the figure. Also in this modification, the operation and effect similar to those of the above-described embodiment can be obtained by forming the cross section of the intake port 4 into a substantially triangular shape as described above.

The sectional shape of the intake port 4 is as follows.
The shape is not limited to the semi-circular shape or the triangular shape as described above, and if the reference surface 40 side half is wider than the other half near the open end 4A of the intake port 4, It may have another shape. Further, in the above-described present embodiment and its modified example, the main cylinder injection type internal combustion engine is provided with the intake air 2
Although it is described as a four-valve internal combustion engine with two valves and two exhaust valves,
The present invention is not limited to the four-valve internal combustion engine, and can be applied to, for example, a three-valve internal combustion engine having two intake valves and one exhaust valve and other various internal combustion engines.

Regarding the detailed shape of the piston 2,
The present invention and the modified examples thereof are not limited to those described above, and a strong tumble flow TF can be obtained in a compact combustion chamber.
Other shapes may be used as long as they can be formed.

[0042]

As described in detail above, according to the cylinder injection type internal combustion engine of the present invention as defined in claim 1, it is formed between the upper surface of the piston fitted into the cylinder and the lower surface of the cylinder head. A combustion chamber, an intake opening end that opens to the combustion chamber on one side of a reference plane that includes the central axis of the cylinder, an intake port that extends upward from the intake opening end, and that is located on the other side of the reference plane. An exhaust port formed in the cylinder head and communicating with the combustion chamber via an on-off valve, and an injection port disposed on a side portion of the combustion chamber on the intake port side so as to face the combustion chamber. The intake flow introduced into the combustion chamber by the intake port is directed toward the upper surface of the piston from the lower surface of the cylinder head on one side of the reference surface along the central axis direction. From the top of the piston on the other side of the reference plane It is configured to form a vertical vortex flow having a streamline toward the lower surface of the cylinder head, and in order to promote the formation of the vertical vortex flow, the reference surface side half portion of the intake port is wider than the other half portion. The intake flow center of the intake port is eccentric to the reference surface side half portion, and the intake flow of the intake port is supplied to the reference surface side half portion near the intake opening end of the intake port from the intake opening end. With the configuration in which the guide portion that smoothly guides to the side wall of the cylinder is formed,
There is an advantage that the intake resistance of the intake flow when flowing into the combustion chamber can be significantly reduced and a strong longitudinal vortex flow can be formed in the combustion chamber. As a result, even in an engine having a relatively large combustion chamber volume, a longitudinal vortex flow can be sufficiently formed, and there is an advantage that a stable combustion state can be obtained even with fuel leaner than the stoichiometric air-fuel ratio.

According to the cylinder injection type internal combustion engine of the present invention as set forth in claim 2, in addition to the structure of claim 1,
Due to the configuration that the cross-sectional shape of the intake port is formed in a substantially semicircular shape in the vicinity of the intake opening end, of the intake flow in the intake port, the flow on the reference plane side half part of the intake port is surely strong. There is an advantage that can be done. In addition, in the cylinder injection type internal combustion engine of the present invention described in claim 3, in addition to the configuration described in claim 1, the cross-sectional shape of the intake port is formed in a substantially triangular shape in the vicinity of the intake opening end. With such a configuration, as in the second aspect, there is an advantage that, of the intake air flow in the intake port, the flow in the half on the reference surface side of the intake port can be reliably strengthened.

[Brief description of drawings]

FIG. 1 is a schematic diagram for illustrating a flow of an intake air flow while paying attention to a main part in a direct injection internal combustion engine as an embodiment of the present invention.

FIG. 2 is an overall view schematically showing an internal configuration of a cylinder injection type internal combustion engine as an embodiment of the present invention.

FIG. 3 is a front view showing an intake port in a cylinder injection type internal combustion engine as one embodiment of the present invention.

4 (a) to (i) are views showing a cross-sectional shape of an intake port in a cylinder injection type internal combustion engine as one embodiment of the present invention.

FIG. 5 is a schematic overall perspective view showing a configuration of a cylinder injection internal combustion engine as one embodiment of the present invention.

FIG. 6 is a diagram for explaining an operating state in a cylinder injection internal combustion engine as an embodiment of the present invention.

FIG. 7 is a diagram showing a flow coefficient characteristic and a tumble ratio characteristic in a direct injection internal combustion engine as an embodiment of the present invention.

8 (a) to (j) are changes in a cylinder injection type internal combustion engine as one embodiment of the present invention.

FIG. 9 is a schematic diagram showing a conventional in-cylinder injection internal combustion engine.

[Explanation of symbols]

 1 Cylinder Head 1A Cylinder Inner Wall 2 Piston 2A Recess as Curved Part 2B Piston Exhaust Valve Side Upper Surface 2C Squish Area 3 Cylinder Block 3A Cylinder 4 Intake Port 4A Intake Passage Combustion Chamber Opening 5 Exhaust Port 5A Exhaust Passage Combustion Chamber Opening 7 Combustion Chamber 7A Compact combustion chamber 18 Injector 18A Injector injection hole 20 Spark plug 40 Reference plane 42 Cylinder center axis 51, 52 Valve stem 60 Guide or ridge 61 Intake valve 62 Intake valve disc TF Tumble flow SF Squish

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Oda 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Satoshi Yoshikawa 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Automobile Industry Co., Ltd. (72) Inventor Kenji Goto 5-3-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Industry Co., Ltd.

Claims (3)

[Claims] 1. A combustion chamber formed between an upper surface of a piston fitted into a cylinder and a lower surface of a cylinder head, and an intake air opening into the combustion chamber on one side of a reference surface including a central axis of the cylinder. An open end, an intake port extending upward from the intake open end, an exhaust port formed on the cylinder head so as to be located on the other side of the reference surface, and an exhaust port communicating with the combustion chamber via an on-off valve, An injector arranged so that an injection port faces the combustion chamber is provided at a side portion of the combustion chamber on the intake port side, and an intake flow introduced into the combustion chamber by the intake port has a central axis line. Along the direction, a longitudinal vortex flow having a streamline from one side of the reference surface toward the upper surface of the piston toward the upper surface of the piston and the other side of the reference surface from the upper surface of the piston toward the lower surface of the cylinder head. To form In order to promote the formation of the longitudinal vortex flow, the reference surface side half portion of the intake port is wider than the other half portion and the intake flow center of the intake port is eccentric to the reference surface side half portion. A guide portion that smoothly guides the intake flow of the intake port from the intake opening end to the side wall of the cylinder is formed in the reference surface side half portion near the intake opening end of the intake port. A cylinder injection internal combustion engine characterized by the following. 2. The in-cylinder injection internal combustion engine according to claim 1, wherein a cross-sectional shape of the intake port is formed in a substantially semicircular shape in the vicinity of the intake opening end. 3. The in-cylinder injection internal combustion engine according to claim 1, wherein a cross-sectional shape of the intake port is formed in a substantially triangular shape in the vicinity of the intake opening end.