JPH0681651A - Cylinder injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To secure the fitting space of an injector and improve combustion stability by disposing an intake port on one side of a cylinder head, and forming a recessed place on the upper face of a piston in order to promote intake air vortex flow. CONSTITUTION:An intake port 8a is provided, through an intake valve, on one side of a cylinder head with a plane FC, including a cylinder axis L along the center of a cylinder S, placed in between. A recessed place 24 presenting the downward protruding curved face from the orthogonal face view to an orthogonal line LH to the cylinder axis L within the plane FC is formed to promote intake air vortex flow TF around a parallel line LH1 to the orthogonal line LH. A raised part 23 is provided being raised gradually from the recessed place 24, with the crest 232 thereof coming close to the lower face of the cylinder head at the top dead center of a piston. The fitting space of an injector can be thereby secured easily, and combustion stability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to stratified combustion in which air flowing from an intake port is supplied to a combustion chamber and the mixture and air are burned in a stratified swirling flow in the combustion chamber. Type internal combustion engine.

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder injection type internal combustion engine in which a gas flowing from an intake port into a cylinder is made into a swirling flow, and fuel is injected into the cylinder to generate an air-fuel mixture for combustion. Regarding the institution.

[0003]

2. Description of the Related Art A main body of an ordinary internal combustion engine is composed of a cylinder head, a cylinder block, and a crankcase, which are stacked in this order to form a main part. A combustion chamber is formed of a cylinder into which a piston is inserted and an upper part of the cylinder. An intake / exhaust passage that can communicate with the chamber via an intake / exhaust valve, a valve system that drives the intake / exhaust valve, a connecting rod that converts the reciprocating motion of the piston into rotary motion and transmits the rotary motion, and the like are housed. When such an internal combustion engine is, for example, a 4-cycle engine, the amount of fuel commensurate with the amount of intake air is supplied to the intake air taken into the cylinder in the intake stroke to generate combustion energy, which is output as rotational energy. is doing. Among such internal combustion engines, there is known a cylinder injection type internal combustion engine capable of improving fuel injection performance by directly injecting fuel into a combustion chamber.

As an in-cylinder injection type internal combustion engine of this type,
A diesel engine, which is a compression ignition internal combustion engine, and a gasoline engine, which is a spark ignition internal combustion engine, are known.
Among them, the diesel engine does not need an ignition means, but needs an engine capable of achieving a high compression ratio and a high-pressure fuel injection means, and has a problem in increasing the size and weight.
On the other hand, the in-cylinder injection type gasoline engine is configured as shown in FIGS. 13 and 14, for example. The gasoline engine here is of a four-valve type, and a piston 51 is inserted into the cylinder S of the gasoline engine. When the piston 51 slides from the top dead center to the bottom dead center, a pair of intake valves (not shown) are opened to intake air. Air is introduced into the combustion chamber 50 through the intake ports 54 from the side of the communication path 52, an injector (not shown) is driven at a predetermined time of the intake and compression strokes to perform in-cylinder injection, and the ignition plug 56 is driven at the end of the compression strokes. Then, the combustion process is performed, and in the subsequent exhaust process, the exhaust gas is exhausted from the exhaust port 55 by opening an exhaust valve (not shown) when the piston 51 rises.
It is configured to discharge to the side.

Such a gasoline engine has few problems such as size increase and weight increase as compared with a diesel engine.

[0006]

However, such an in-cylinder injection type gasoline engine has a structure in which the respective communication passages 52 and 53 extending from the intake and exhaust ports are opened on both side wall surfaces of a cylinder head (not shown). Here, the conducting passages 52, 53 and the spark plug 56 are provided in the cylinder facing portion of the upper cylinder head of the combustion chamber, and in particular, the conducting passages 52, 53 are formed large in order to secure the volume efficiency of each cylinder. Or two intake passages 55 as shown in FIG.
2, 52 and the two exhaust passages 53, 53, there is little space for securing the injector mounting portion for mounting the injector, and there are many design restrictions, and it is extremely difficult to realize an optimal layout. ing.

Particularly, in order to realize the stratified lean burn in the cylinder injection engine, the spray is collected as compactly as possible, and the rich air-fuel mixture is collected in the vicinity of the ignition plug.
It is necessary to ensure combustion stability. However, in the conventional in-cylinder injection engine, it was almost difficult to direct the injector toward the spark plug due to the layout restrictions as described above.

An object of the present invention is to provide an in-cylinder injection type internal combustion engine in which a mounting space for an injector for in-cylinder injection with respect to a spark plug can be easily secured and the combustion stability can be improved.

[0009]

In order to achieve the above-mentioned object, the present invention provides a combustion chamber formed between an upper surface of a piston and a lower surface of a cylinder head to be inserted into a cylinder, and a center of the cylinder. An intake port that is disposed on one side of the cylinder head across a plane that includes the cylinder axis and that communicates with the combustion chamber via an intake valve, and the in-plane cylinder axis orthogonal line in the combustion chamber. Of the recesses formed on the upper surface of the piston in order to promote the vortex flow of the intake air around the parallel line and exhibiting a downwardly convex curved surface when viewed at right angles to the orthogonal line, and the side end of the recess on the upper surface of the piston. And a ridge that gently bulges from the recess and is close to the lower surface of the cylinder head at the piston top dead center, and in the recess when the piston is located near the top dead center. An injector having an injection port for injecting fuel, and an ignition plug arranged at a position facing the raised portion where the injected fuel of the injector reaches by the flow restriction of the recess. To do.

[0010]

[Operation] An intake port communicating with the combustion chamber is provided on one side of the cylinder head that extends across the plane including the cylinder axis, and promotes the vortex flow of the intake around the line parallel to the cylinder axis in the plane. Therefore, a recess is formed on the upper surface of the piston, and the recess presents a curved surface that is convex downward at least in the orthogonal view with the orthogonal line, and when the piston is located near the top dead center, the injection port of the injector faces the recess. Since the fuel can be injected, it is possible to reliably guide the fuel from the injector whose flow is regulated in the recess to the spark plug arranged at the position facing the raised portion.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The in-cylinder injection type internal combustion engine shown in FIGS. 1 and 2 is a two-cycle four-valve internal combustion engine of in-line four-cylinder (hereinafter referred to simply as engine E).
Will be attached). The main body of the engine E is configured by integrating a cylinder head 1 with a head cover, a cylinder block 3, a crank case and a crank cover (not shown) in this order and integrating them, and a cylinder S in which a piston 2 is inserted and inserted, Intake and exhaust passages 4a, 4b, 5 which can communicate with the combustion chamber 7 formed of the upper part of the cylinder S.
a, 5b, a valve operating system (not shown) for driving the pair of intake / exhaust valves 10, 11 for opening / closing the intake / exhaust passages, a crankshaft, connecting rod, etc. for converting reciprocating motion of the piston 2 into rotational motion. Is housed. Since the configuration of each cylinder in the engine E here is the same,
Here, the description will focus on the one cylinder.

Here, the cylinder head 1 sandwiches a plane FC (here, it extends in the head longitudinal direction as shown in FIG. 3) including the cylinder axis L along the center of the cylinder S, and has a pair of sides on one side. Intake port 8a to the other side and exhaust port 9
a is provided. The cylinder head 1 has a cylinder S
A cylinder facing lower wall surface 6 that faces the combustion chamber 7 formed therein is formed, and the lower wall surface is formed with a wedge-shaped recess 601 that is long in the direction in which the plane FC extends in the center thereof. Intake ports 8a, 8b following the pair of intake passages 4a, 4a on one side of the wedge-shaped recess 601, that is, one side across the plane FC including the cylinder axis, and a pair of exhaust passages 5a on the other side. ，
Exhaust ports 9a and 9b following 5b are formed (see FIGS. 1 and 5), and each port is opened and closed by an intake valve 10 and an exhaust valve 11, respectively. Further, the wedge-shaped recess 60
A spark plug 20 is mounted at a position substantially opposite to a peak 232 of a raised portion 23, which will be described later, when the piston 2 reaches the TDC position at a substantially central position of 1.

Here, as shown in FIGS. 2 and 5, the pair of exhaust passages 5a and 5b extend in a curved manner from the exhaust port 9a, and further extend straight in a direction away from the plane FC, and It is configured to open to the side wall surface.
The pair of intake passages 4a and 4b are formed on one side of the plane FC including the cylinder axis (on the right side of the plane FC in FIG. 3) and extend straight in the cylinder head 1 in the vertical direction. The downstream side communicates with each intake port 8a, and the upstream end is connected to the branch pipe 13 on the upper surface 1f of the cylinder head 1.

Here, the upper end of each branch pipe 13 directly connected to the intake passages 4a, 4b is an intercooler 141.
It communicates with the built-in plenum chamber 14, and the inlet 17 of the chamber 14 is a centrifugal scavenging pump 15 with a variable speed pulley.
Is in communication with. As described above, since the intake passages 4a and 4b of the engine E and the branch pipes 13 are vertically long and straight, the flow resistance to intake air is relatively low, and a relatively large amount of intake air is supplied to the combustion chamber 7. And the volumetric efficiency of the engine can be improved.

An injector mounting portion 1a is formed on one side of the plane FC of the cylinder head 1 outside the pair of intake passages 4a, and an injector 18 is mounted on the portion 1a. A high-pressure pump 19 is connected to the injector 18 via a pressure storage device 25. The high-pressure pump 19 and the injector 18 are connected to an engine controller (not shown), and a drive output is supplied to the injector at a predetermined injection timing (crank angle) for a predetermined injection time (PH, PL in FIG. 7). Has been done.

In the injector mounting portion 1a here, since the intake passages 4a extend straightly upward from the intake ports 8a, the regions outside the pair of intake passages 4a are released. Enough space can be secured. Therefore, the injector mounting portion 1a and the injector 18
There is a large degree of freedom in securing the optimum layout of itself and also in setting the relative orientation and position with respect to the spark plug 20. Further, the injector mounting portion 1a is located outside the pair of intake air passages 4a, and it is relatively easy to improve the cooling performance of the injector body and the fuel, ensuring the durability of the injector and avoiding heat damage to the fuel supply passage. Easy to plan.

A piston 2 is fitted in the cylinder S of the first cylinder. As shown in FIG. 8, the piston 2 has a top dead center TDC indicated by a solid line and a bottom dead center BD indicated by a two-dot chain line.
Reciprocates between C. As shown in FIG. 2, the piston 2 has a skirt portion 21 and a main portion 22, and a recess 24 and a raised portion 23 are formed on the upper surface of the main portion 22 of the piston. Here, the concave portion 24 and the raised portion 23 are formed to promote the reverse tumble flow TF of the intake air around the parallel line LH1 of the orthogonal line LH of the cylinder axis L in the plane FC.

In this case, the recess 24 is formed eccentrically on the exhaust port 9a side in a state including the cylinder axis L, and at least the straight line LH is viewed in the orthogonal plane view (a concave portion corresponding to the orthogonal plane view in FIGS. 2 and 8). Location 24 is shown) presenting a downwardly convex curved surface. The raised portion 23 is continuously provided on the intake port 8a side of the recess 24 and extends in the plane direction while facing the plane FC, the side wall vf, the outer wall 231 and the peak 232 at the joint end of both walls.
Have. In particular, as shown by the solid line in FIG.
Is located at the top dead center TDC, the ridge 232 is configured to approach the cylinder facing lower wall surface 6. The side wall vf of the raised portion 23 is continuously connected to a curved surface that gently rises from the recess 24.

Therefore, as shown in FIG.
When the intake air reaches the bottom dead center BDC side at the end of intake air, the intake air that has flowed in from the intake port 8a heads toward the piston upper surface along the direction of the axis L, and is further U-shaped by the recess 24 and the side wall vf.
A straight line LH in the plane FC that turns and includes the cylinder axis L
The inverse tumble flow TF that rotates around the parallel line LH1 of is generated.

Further, as shown by the solid line in FIG. 8, when the piston 2 reaches the end of compression, the recess 24 of the piston 2 is reached.
A compact combustion chamber C is formed between the side wall vf and the cylinder facing lower wall surface 6. The fuel injected into the combustion chamber C collides with the recess 24 and the side wall vf, and the sprayed fuel after the collision can be scattered toward the spark plug 20 arranged at the position facing the ridge 232, and is compact. The air current generated in the combustion chamber C is flow-controlled by the recess 24 and the side wall vf and can flow toward the spark plug 20 at the same time. Moreover, at this time, the squish SF generated on the outer wall 231 side hits the mixed airflow toward the spark plug 20 due to the rise of the piston 2, and the mixed air is further stirred, so that the combustibility is further improved. Furthermore, the recess 24
Also, the injected fuel, particularly the fuel injected in the latter stage of compression, is reliably received by the compact combustion chamber C and prevented from diffusing to the peripheral portion of the piston, and the fuel is applied to the clevis Q between the piston and the inner wall of the cylinder. Penetration can be reduced, and as a result, the concentration of HC in exhaust gas can be reduced.

Since such an engine E has two cycles, as shown in FIG. 6, the exhaust stroke of the exhaust valve 11 after the previous combustion stroke is started from 0 ° of TDC and the crank angle of 90 ° has elapsed.
To open the exhaust stroke, and when the crank angle approaches 120 °, the intake valve 10 is also opened to enter the intake stroke.
At this time, as shown by the two-dot chain line in FIG.
The intake air from b can make a reverse tumble flow TF by making a U-turn of the intake air flowing downward in the cylinder axis L direction by the action of the recess 24 and the side wall vf.

After the bottom dead center BDC has passed, the crank angle is 230 °.
The exhaust valve 11 is closed in the vicinity of this side, the compression stroke is started, and at the same time, when the engine speed is high, the injector 18 is driven to inject the injector for a predetermined injection time PH. As a result, the fuel injected into the reverse tumble flow TF is reliably mixed, and high power generation can be appropriately performed. After that, the intake valve 10 is also closed to complete the intake and exhaust, and only the compression stroke is completely performed. At this time, if the engine is in the low rotation speed, at this time, the latter-stage in-cylinder injection is performed for the predetermined time PL.

In the latter in-cylinder injection, the compact combustion chamber C
Is formed, the mixture is compactly gathered to form a layer, and the layered rich mixture flows to the ignition plug 20 and is easily ignited and burned to achieve lean burn.
In this latter in-cylinder injection, it is possible to secure a super lean burn with an air-fuel ratio of 50 or more depending on the setting of combustion conditions, and it is also possible to achieve a fuel consumption complaint of 30% at the indicated fuel consumption rate. After that, when the predetermined ignition timing before the top dead center TDC is reached, the spark plug 20 is driven to start the ignition process (indicated by the symbol Δ in FIG. 6). Due to this ignition process, the in-cylinder pressure in the combustion chamber rises, the piston is pushed down, and an output is generated.

Here, the injector 18 is controlled by the control means so as to drive the injector 18 for a predetermined injection time PH when the engine is rotating at a high speed, and to drive the injector 18 for a predetermined injection time PL when the engine is rotating at a low speed. As a result, at high speed, turbulence can be promoted and rapid combustion can be realized by starting the mixing of the fuel and the air forming the reverse tumble flow TF early. On the other hand, at a low speed, the injection is delayed to execute the latter in-cylinder injection, wait for the generation of the compact combustion chamber C, inject the fuel there, and also receive the stirring action of the squish SF to sufficiently secure the ignitability. be able to.

Further, the injector mounting portion 1a is located outside the pair of intake passages 4a, and it is relatively easy to improve the cooling performance of the injector body and the fuel, and the durability of the injector is secured and the heat damage is avoided. Easy to plan. Therefore, it starts early for the chamber to sufficiently generate the air-fuel mixture and promotes the generation of high output, while delaying the injection at low speed to wait for the generation of the compact combustion chamber C and inject fuel there. go,
The stirring action of the squish SF is also received, and it is possible to sufficiently secure the ignitability and the combustion stability. Furthermore, since the compact combustion chamber C is spherical, heat loss can be reduced and low-load operation can be stabilized. Although a two-cycle gasoline engine has been described with reference to FIGS. 1 to 5, instead of this, a four-cycle gasoline engine is used.
The present invention may be applied to a gasoline engine of a cycle. In this case, the same engine body configuration can be used, and duplicated description will be avoided.

In the four-cycle engine in this case, as shown in FIG. 7, the intake valve 10 is opened from 0 ° before TDC, and the exhaust valve 11 is closed after 0 ° of TDC while the intake stroke starts and the exhaust gas from the previous exhaust is exhausted. Finish the process. After that, the piston 2 descends to 180 ° at the crank angle, the reverse tumble flow TF is generated during this, and fuel is injected from the injector during the high rotation and high output in the reverse tumble flow TF. The injection timing of the injector 18 is also performed in the compression stroke after the intake valve 10 has been closed after the intake stroke has passed 210 ° as shown in FIG. 7. That is, the injector 18 performs the injection drive during the predetermined injection time PH of the intake early when the engine rotates at high speed, and the latter P of the latter stage of compression at the time of low speed and low output.
It is controlled so that the latter-stage in-cylinder injection is performed on L.

Thus, at high speed and high load, the turbulence can be promoted and the rapid combustion can be realized by starting the mixing of the fuel and the air forming the reverse tumble flow TF early. On the other hand, at low speed, the injection is delayed to wait for the generation of the compact combustion chamber C, and fuel injection is performed here.
With the stirring action of the squish SF, ignitability can be secured and lean burn can be sufficiently achieved. After this, TDC
Near 360 °, the squish SF shown in Fig. 8 also works,
The turbulence of the air-fuel mixture from the compact combustion chamber C toward the ignition plug 20 is further disturbed, and the combustibility can be further improved. Immediately after that, when the predetermined ignition timing is reached, the ignition plug 20 is driven to start the ignition process (indicated by the symbol Δ in FIG. 7). Due to this ignition process, the cylinder pressure in the combustion chamber rises, the piston is pushed down, an output is generated, and the combustion process is performed at a crank angle of 5 degrees.
Perform up to nearly 40 °. In the vicinity of the crank angle of 480 °, the exhaust valve 11 is opened, the exhaust stroke is continued until the crank angle 720 elapses, the intake valve 10 is opened for the next intake stroke, and four cycles are completed. In this case as well, the same operational effect as in the case of two cycles can be obtained.

The intake passages 4a and 4b of the engine E shown in FIG.
Although the engine has a straight upper and lower shape, an engine E1 as shown in FIGS. 9 to 11 may be configured instead. The engine E1 is different from the engine E of FIG. 1 in the configuration of the intake passages 4a, 4b and the piston 2a, and is different in that a forward tumble flow TF1 is generated. Since the other configuration is the same as that of the engine E, The duplicate explanation is omitted. The pair of intake ports 8a, 8b and the intake passage 4c,
4d is on one side of the plane FC including the cylinder facing lower wall surface 6 cylinder axis L, and the intake passages 4c and 4d extend in a direction straight away from the plane FC, so that the intake air that flows in is opposed to the cylinder in the cylinder. The intake air is introduced along the lower wall surface 6 toward the other side (exhaust ports 9a, 9b side). On the other hand, the piston 2a is the skirt portion 2
1 and a main part 22, and a recess 24 'and a raised part 23' are formed on the upper surface of the main part 22 'of the piston. Here, the concave portion 24 'and the raised portion 23' are formed so as to promote the forward tumble flow TF1 of the intake air around the parallel line LH1 of the orthogonal line LH of the cylinder axis L in the plane FC.

In this case, the recess 24 'is formed eccentrically on the exhaust port 9a side in a state including the cylinder axis L, and at least the straight line LH of the recess 24' (the recess 24 corresponding to the direct surface view in FIG. 9). 'Is shown) and presents a downwardly convex curved surface. The raised portion 23 ′ is continuously provided on the intake port 8 a side of the recess 24 ′ and extends in the plane direction while facing the plane FC, the side wall vf, the outer wall 231 and the peak 232 at the joint end of both walls.
Have. In particular, as shown by the solid line in FIG.
When a is located at the top dead center TDC, the ridge 232 is configured to approach the cylinder facing lower wall surface 6. In addition,
The side wall vf of the raised portion 23 is continuously connected to a curved surface that gently rises from the recess 24.

Therefore, as shown in FIG. 10, the intake air that has flowed in from the intake port 8a when the piston 2a finishes the intake air is directed to the other side (exhaust ports 9a, 9b side) along the cylinder facing lower wall surface 6 in the cylinder S. To introduce intake air,
The intake air flows toward the upper surface of the piston along the direction of the axis L, makes a U-turn by the recess 24 ′ and the side wall vf, and the forward tumble flow TF1 that rotates around the parallel line LH1 of the orthogonal line LH in the plane FC including the cylinder axis L is generated. Is generated.

Further, as shown by the solid line in FIG. 9, when the piston 2a reaches the end of compression, the compact combustion chamber C is formed. The fuel injected into the combustion chamber C has a recess 2
4'and the side wall vf, the sprayed fuel after the collision can be scattered toward the spark plug 20, and the airflow generated in the compact combustion chamber C is flow-controlled toward the spark plug 20 under flow regulation. However, the squish SF generated on the outer wall 231 side collides with the mixed airflow toward the ignition plug 20, and the mixed air is further agitated, so that the combustibility is further improved. In this case as well, the same operational effects as the engine E of FIG. 1 can be obtained.

Instead of the 2-cycle 4-valve engine E shown in FIG. 1, for example, a 2-cycle 5-valve engine or a 3-valve engine E'shown in FIG. 12 may be constructed. In the case of the cylinder S of the three-valve engine E ′ shown in FIG. 13, the intake passages are in communication with the pair of intake ports 8a and 8b, and the exhaust passage 5 ′ is in communication with one exhaust port 9 ′. Here, too, an intake port 8a following the pair of intake passages 4a and 4b across the plane FC including the cylinder axis L and an exhaust port 9'following one exhaust passage 5'on the other side. Each is formed and each port has an intake valve 10 and an exhaust valve 11
Each is opened and closed by. Further, the spark plug 20 is mounted at a position facing the cylinder axis L.

Also in this case, the same operational effect as that of the engine E of FIG. 1 can be obtained. Although each of the above-mentioned engines E, E ', etc. was a spark ignition type engine, the present invention can be applied to a compression ignition internal combustion engine instead of this, and in this case as well, the two-cycle engine E of FIG. The same arrangement and effect of each port and injector can be taken, and the same effect can be obtained.

[0034]

As described above, according to the present invention, the intake port is provided on one side of the cylinder head which is across the plane including the cylinder axis, and the recess on the upper surface of the piston is defined by a line perpendicular to the in-plane cylinder axis. It is formed around the parallel lines to promote the vortex flow of the intake air, and it is also formed so as to have a downwardly convex curved surface when viewed orthogonally to the orthogonal line, and the injector injects fuel toward the recess near the top dead center. When this is done, the fuel from the injector can be reliably guided to the spark plug at a position facing the raised portion, the mixture can be easily ignited, and combustion stability can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a cylinder injection internal combustion engine as an embodiment of the present invention.

FIG. 2 is a side sectional view of one cylinder of the in-cylinder injection internal combustion engine of FIG.

3 is a schematic perspective view of one cylinder of the in-cylinder injection internal combustion engine of FIG. 1. FIG.

FIG. 4 is a schematic view taken along line A of FIG.

5 is a schematic top view of one cylinder of the in-cylinder injection internal combustion engine of FIG. 1. FIG.

FIG. 6 is a drive cycle explanatory diagram of the in-cylinder injection internal combustion engine of FIG. 1.

FIG. 7 is a drive cycle explanatory diagram of a cylinder injection internal combustion engine of another embodiment.

8 is an operation explanatory view of a piston 1 in a cylinder of the in-cylinder injection internal combustion engine of FIG. 1. FIG.

FIG. 9 is a schematic side sectional view of an essential part of one cylinder of an in-cylinder injection internal combustion engine as another embodiment of the present invention.

10 is a schematic perspective view of one cylinder of the in-cylinder injection internal combustion engine of FIG. 9. FIG.

FIG. 11 is a schematic layout diagram of main parts of one cylinder of the in-cylinder injection internal combustion engine of FIG. 9.

FIG. 12 is a schematic layout view of a main portion of one cylinder of a cylinder injection type internal combustion engine as another embodiment of the present invention.

FIG. 13 is a schematic side view of a main portion of a conventional in-cylinder injection internal combustion engine.

FIG. 14 is a schematic side view of the direct injection internal combustion engine of FIG.

[Explanation of symbols]

 1 cylinder head 2 piston 3 cylinder block 4a intake passage 4b intake passage 5a exhaust passage 5b exhaust passage 6 cylinder facing lower wall 7 combustion chamber 8a intake port 8b intake port 9a exhaust port 9b exhaust port 10 intake valve 11 exhaust valve 18 injector 20 spark plug 23 raised portion 24 recess vf side wall TF reverse tumble flow TF1 forward tumble flow SF squish L cylinder axis FC plane E engine S cylinder

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02B 31/00 Z 7541-3G F02F 3/26 C 8503-3G

Claims (1)

[Claims] 1. A combustion chamber formed between an upper surface of a piston inserted into a cylinder and a lower surface of a cylinder head, and a cylinder head sandwiched by a plane including a cylinder axis line along a center of the cylinder. Formed on the upper surface of the piston to promote intake vortex flow around the parallel to the intake port that is located on one side and communicates with the combustion chamber via the intake valve and the in-plane cylinder axis orthogonal line in the combustion chamber And a recess having a downwardly convex curved surface when viewed at right angles to at least the perpendicular line, and a piston which is continuously provided at the side end of the recess on the upper surface of the piston and gently swells from the recess and above the piston. A raised portion near the bottom surface of the cylinder head at the dead point; an injector having an injection port for injecting fuel toward the recess when the piston is located near the top dead center; Cylinder injection type internal combustion engine, characterized in that a spark plug fuel injected injector is disposed in a position facing the said protuberance reaching receiving flow restriction of the recess.