JPH11200867A - Cylinder fuel injection engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion chamber structure for a cylinder fuel injection engine of simple constitution which can ensure good stratified combustion y utilizing reflection of fuel in a piston upper surface. SOLUTION: This cylinder fuel injection engine 10 has a cylinder head 14 having a vent roof type combustion chamber and a piston 18 formed with an upper surface as a plane of basic shape. In this cylinder head 14, an injection means 34 injecting fuel in a cylinder axial direction toward the piston 18 and a spark plug 30 protruded diagonally relating to a cylinder axial center direction from an intake means side are provided. An upper surface part has a cavity 36 hollowly provided to be opened in almost true circular shape, and a slope tilted so as to be opposed to a side of the spark plug 30 is formed in the cavity 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber of a direct injection type engine for directly injecting fuel into a cylinder.

[0002]

2. Description of the Related Art Hitherto, as a technique for improving the fuel efficiency of an engine, improvement of theoretical thermal efficiency, reduction of pumping loss, reduction of friction, and the like have been proposed. In order to improve the theoretical thermal efficiency and reduce the pumping loss, in addition to the method of increasing the compression ratio or expansion ratio in the combustion chamber, lean combustion control and high EGR (exhaust gas recircul
ation) There is a method of performing combustion control or the like. In the lean burn control and the high EGR control, a gas flow such as a tumble, a swirl, and a squish is generated in the cylinder to improve the combustibility of the air-fuel mixture in the combustion chamber.

[0003] Such an engine is basically based on forming a uniform mixture in the combustion chamber during the intake stroke. On the other hand, the mixture in the combustion chamber is adjusted by adjusting the fuel injection direction and the injection timing. It was also intentionally performed to locally change the air-fuel ratio of the fuel cell.

[0004] That is, a stratified combustion system in which combustion is performed at a lean air-fuel ratio as a whole in the entire combustion chamber by making the air-fuel ratio locally rich in the combustion chamber, or forming an air-fuel mixture only in a local portion, or the like. Had been proposed.

However, in the conventional stratified combustion system,
Such local formation of an air-fuel mixture in the combustion chamber is not sufficient, and it has been desired to greatly improve the degree of freedom of the air-fuel mixture formation. Therefore, various in-cylinder injection engines that directly inject fuel into the cylinder have been proposed as a countermeasure.

For example, Japanese Patent Application Laid-Open No. H5-1544 discloses that
A mask wall that directs the flow of intake air passing through the intake port is provided in a part around the intake valve, forcibly generating a reverse tumble flow in the cylinder, and the injection provided below the intake port during the compression stroke. A configuration example is shown in which fuel injected obliquely from the means (injector) with respect to the cylinder axis direction is placed on a reverse tumble flow, and the air-fuel mixture is guided toward a spark plug provided at the top of the combustion chamber. I have.

In Japanese Patent Application Laid-Open No. 146886/1994, an injection means is mounted at a lower position of an intake port in the same manner as in the technique of Japanese Patent Application Laid-Open No. 5-1544, and the sectional shape of the intake port is changed to one side. A half is widened. Then, the center of the intake air flow is eccentric to promote the generation of the reverse tumble flow, the fuel is injected obliquely to the cylinder axis direction, and the fuel is placed on the reverse tumble flow, and the air-fuel mixture is provided at the top of the combustion chamber at the spark plug. Is shown in the figure.

Further, in Japanese Patent Application Laid-Open No. 6-42352,
An example is shown in which the injection means is mounted in the cylinder axial direction at the center of the top of the combustion chamber and an ignition plug is projected from between two intake ports into the combustion chamber to perform ignition.

[0009]

However, the in-cylinder injection type internal combustion engine disclosed in the above-mentioned Japanese Patent Application Laid-Open No. H5-1544 employs an intake port for forcibly generating a reverse tumble flow by a mask wall. Therefore, the suction resistance may be excessive in a high-speed and high-load region. As a result, an insufficient intake air amount occurs, which may affect the output performance.

[0010] Next, in the technique disclosed in Japanese Patent Publication No. 6-146886, a reverse tumble flow is generated by adjusting the cross-sectional shape of the intake port as described above, and the reverse tumble flow is generated by the curved portion on the upper surface of the piston. It promotes the generation of flow. However, since only the inside of the curved portion forms the combustion chamber space, the compression ratio may be excessively high. As a result, it is difficult to set a compression ratio suitable for a fuel used in a normal practical engine, so-called regular gasoline.

Further, since there is a distance between the injection port of the fuel injection valve and the electrode of the ignition plug, it is difficult to control the local air-fuel ratio in the vicinity of the electrode in detail, and the combustion stability and ignitability are low. .

Further, the above two publications disclose a technique in which the injection means injects fuel obliquely to the cylinder axis direction. However, when the fuel is injected in an oblique direction, the fuel will wash away the lubricating oil on the inner peripheral wall of the cylinder, resulting in reduced lubricity, uneven wear of the inner peripheral surface of the cylinder and resulting functional failure such as compression leakage. Has the disadvantage of generating

Next, in the combustion chamber structure of the internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 6-42352, the spark plug is installed at substantially the center of the top of the combustion chamber and directly downward, and the ignition portion of the spark plug Are arranged in the injection region. However, in this conventional example, rather than igniting the fuel reflected on the upper surface of the piston, the rear end side of the injected fuel is ignited, and the rich mixture after ignition is directed to the center of the combustion chamber, and The main purpose is to perform combustion at the center position.

However, in this method, good stratified combustion can be obtained in the low injection amount region, but it becomes difficult to suppress the generation of smoke when the injection amount increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems in the above-mentioned various prior arts, and an object of the present invention is to always utilize a reflection of fuel on a piston upper surface in various operating states of an engine to obtain a good result. It is an object of the present invention to provide an in-cylinder injection engine having a simple configuration capable of ensuring stratified combustion.

[0016]

According to a first aspect of the present invention, there is provided an in-cylinder injection type engine having a cylinder head having a pent roof type, that is, a gable roof type combustion chamber ceiling. It has a piston having an upper surface having a basic shape as a plane and an injector for injecting fuel in a cylinder axial direction at a predetermined timing from a position near a center of a pent roof type combustion chamber ceiling.

The upper surface of the piston is provided with a cavity which is a substantially circular opening with a center point at a position substantially coaxial with the center axis in the injection direction of the injector. In addition, on the intake side of the ceiling of the combustion chamber, the piston is provided to project obliquely into the combustion chamber with respect to the cylinder axis direction. An ignition plug having an ignition portion is provided at a position deviated to the intake side.

The cavity has an inclined surface which is formed to have a concave vertical cross section perpendicular to the piston pin and which is inclined to face the ignition portion.

According to the in-cylinder injection type engine having the above-described structure, in the engine compression stroke in the medium / low load operation region in which the stratified charge combustion is performed, the piston rising toward the cylinder head is located at a predetermined position before the top dead center. Upon arrival, fuel is injected from the injector, and the injected fuel (hereinafter, simply referred to as “injected fuel”) spreads toward the cavity, is received in the cavity, and reflected,
Crawl around and spread by jumping.

Here, since the stratified mixture is formed while the injected fuel is reflected by the inclined surface, the mixture is guided to the intake side. Therefore, the ignited stratified mixture can be guided at an appropriate time around the ignition portion of the ignition plug provided at a position deviated to the intake side, and stable ignitability can be obtained.

As described above, by appropriately controlling the direction in which the injected fuel spreads, rapid combustion can be obtained without generation of a mixture in which the flame cannot be propagated or generation of an over-lean region. Partial burn can be prevented from occurring.

In addition, good ignitability and combustion stability can be obtained in a wide operating range, and as a result, good operability,
HC can be reduced and fuel efficiency can be improved. And
Because it has a combustion chamber space other than the cavity,
The compression ratio does not increase and regular gasoline can be used.

Further, since the fuel is injected toward the piston in the axial direction of the cylinder, a part of the injected fuel directly collides with the inner peripheral wall surface of the cylinder, thereby deteriorating the engine combustion caused by the cooling action and the plug. Smoldering and deterioration of lubrication between the cylinder and the piston can be prevented.

In the cylinder injection engine according to the second aspect, the cavity has a wall portion extending from the upper surface to the ceiling of the combustion chamber at a predetermined height at the exhaust side thereof and facing the center of the cavity. doing. Accordingly, when the injected fuel is reflected, crawled around, and jumped up, it hinders diffusion to the exhaust side and actively guides it to the ignition portion side. Therefore, it is possible to appropriately control the direction and spread of the injected fuel.

According to a third aspect of the present invention, the in-cylinder injection engine is such that the cavity has a long diameter in the same direction as the piston pin centered on a position substantially coaxial with the injection center axis of the injector, instead of the substantially circular opening. It has a substantially elliptical opening to be arranged. As a result, when the injection amount is large, the space where the spray spreads is sufficiently ensured, and the load limit at which stratified combustion can be performed increases.

According to a fourth aspect of the present invention, in the cylinder injection engine, the cavity has a substantially elliptical opening having a longer diameter in a direction perpendicular to the piston pin, instead of the substantially circular opening. . Thereby, the spread space of the spray when the injection amount is small is suppressed, and excessive diffusion of the spray is suppressed. Therefore, stable stratified combustion can be obtained at low load.

In the cylinder injection engine according to the fifth aspect, the injected fuel is injected so as to form a substantially conical hollow shape gradually expanding in the injection direction about the injection center axis of the injector. At times, it is set so that the spread range of the injected fuel falls within the cavity. Therefore, a stratified mixture can be easily and reliably formed by the cavity.

According to a sixth aspect of the present invention, there is provided an in-cylinder injection engine.
The injector has an injection nozzle that imparts a spiral rotational movement to the fuel to inject the fuel. By the injection of the injection nozzle, the fuel injection shape can be formed into a substantially conical hollow shape.

[0029]

Embodiments of the present invention will be described below in detail. FIG. 1 is a sectional explanatory view schematically illustrating a direct injection engine 10 according to a first embodiment of the present invention, and FIG. 2 is an explanatory view of a piston 18 in FIG. 2, (A) is an explanatory top view of the piston 18,
(B) is an explanatory sectional view taken along line XX of (A).

As shown in FIG. 1, the in-cylinder injection engine 10 includes a cylinder head 14 having a pent roof-shaped combustion chamber ceiling (hereinafter simply referred to as a “ceiling”) 12 and an upper surface 16. A piston portion 18 having a basically planar shape, and a cylinder portion 22 having a cylinder 20 into which the piston 18 is reciprocally fitted.
Are the basic components.

As shown in FIG. 1, the ceiling 12 has two slopes 12a and 12b that gradually expand toward the top.
And has a shape similar to a gabled roof as a whole. The slope 12 a is provided with two intake valves (not shown) for communicating and blocking between an intake port (not shown) provided in the cylinder head 14 and the combustion chamber 24. An exhaust port (not shown) is provided on the slope 12b.
There are two exhaust valves (not shown) for communicating and shutting off between the fuel cell and the combustion chamber 24. Hereinafter, for convenience of explanation, the intake valve side is referred to as an intake IN side, and the exhaust valve side is referred to as an exhaust EX side.

The spark plug 30 is, as shown in FIG.
The cylinder 2 provided on the intake IN side of the cylinder head 14
An electrode portion 32 is provided at an end protruding toward the combustion chamber 24 and is provided as an ignition portion.

Further, an injector 34 is provided above the ceiling 12. The injector 34 directs a predetermined amount of fuel toward the axial piston 18 of the cylinder 20 at a predetermined timing.
8 is injected so as to be orthogonal to the upper surface 16.

The injector 34 is connected to the cylinder 20
Is disposed at a position offset by a predetermined distance from the central axis 21 toward the exhaust EX side. Then, the injection shape of the injected fuel f by the injector 34 forms a substantially conical hollow shape gradually expanding around the injection center axis 35.

The substantially conical hollow shape of the injected fuel can be easily formed by, for example, setting the injection angle at an injection divergence angle of about 40 to 80 degrees and giving a rotational component to the injected fuel f. It is possible. Specifically, it can be formed by hollow cone spraying by the injector 34 using a swirl nozzle.

The swirl gas flow and the forward weak tumble gas flow are generated in the combustion chamber 24 by the shape of the intake port (not shown) which is communicated with and shut off from the combustion chamber 24 via the intake valve. Is configured. The tumble ratio is set to be about 0.5 to 2.

As shown in FIG. 1, the piston 18 basically has a top surface 16 in a plane shape perpendicular to the cylinder center axis 21. Then, on the upper surface portion 16, FIG.
As shown in FIG. 3, the cavity 36 having a substantially circular opening 39 centered on the position on the injection center axis 35 and having a concave shape.
Is provided.

The cavity 36 is formed in a concave shape, and basically, as shown in FIG. 1, the vertical cross section orthogonal to the piston pin 42 on the bottom surface is formed as a compound curve or curve, and the exhaust E
On the X side, a spark plug 3 which is a characteristic configuration of the present invention is provided.
An inclined surface 37 facing the zero electrode portion 32 is formed. Furthermore, as shown in FIG. 2, the vertical cross-sectional shape in the same direction as the piston pin 42 forms a compound curve of symmetry.

On the exhaust EX side of the peripheral edge of the cavity 36, there is provided a projection 38 having a predetermined height which does not come into contact with the ceiling 12 even when the piston 18 is at the top dead center position. A wall surface 38a extending above the upper surface 16 is formed on the exhaust EX side. The wall surface 38 a has a substantially semicircular shape centered on the center of the cavity 36 and faces toward the center of the cavity 36.

The diameter of the opening 39 is set to be about 30 to 70% of the diameter D of the cylinder 20, and the depth of the cavity 36 is one of the diameter D of the cylinder 20 at the deepest part.
It is set up to about 5%.

The electrode portion 32 of the ignition plug 30 is set so as to be located above the cavity 36 and offset from the center of the cavity 36 toward the intake IN when the piston 18 is located near the top dead center. In the present embodiment, it is arranged not to be directly exposed to the spray from the injector 34.

The injection divergence angle of the injector 34 is set so that the injection range falls within the cavity 36 at a predetermined timing (substantially near the top dead center) when the piston 18 moves up and down.

According to the in-cylinder injection engine having the above-described structure, the substantially conical hollow injection fuel f injected from the injector 34 collides with the bottom surface of the cavity 36, and the substantially conical hollow shape is collapsed, reflected and crawled. It diffuses by various operations such as turning and bouncing.

In particular, since the inclined surface 37 is provided in the cavity 36 so as to face the electrode portion 32, a part of the injected fuel f is formed by the inclined surface 37.
The light is reflected and diffused toward the 0 electrode portion 32 side. Then, an air-fuel mixture is formed by diffusion, and a part thereof is applied to the electrode portion 32,
An optimal mixture having good ignitability is formed in the vicinity of the electrode portion 32. That is, due to the inclined surface 37, the mixture is hardly diffused on the wall of the cylinder 18 on the exhaust side, and the air-fuel mixture can be easily formed in the vicinity of the electrode part 32, and a part of the air-fuel mixture is reliably applied to the electrode part 32 Things.

Next, the basic operation of the direct injection engine 10 in the present embodiment will be described. The in-cylinder injection engine 10 controls the amount of combustion injection, the injection timing, and the ignition timing so that the stratified combustion operation is performed during low / medium load operation and the uniform combustion operation is performed during high load operation.

The uniform combustion performed at the time of high load operation is to inject fuel into the combustion chamber 24 during the intake stroke, and is substantially the same operation as the conventional engine in which fuel is injected into the intake port during the intake stroke. Detailed description is omitted, and here, a description will be given of a low / medium load operation in which the stratified combustion operation is performed.

In the compression stroke, when the piston 18 rises to a predetermined position near the top dead center, fuel f is injected from the injector 34 into a hollow cone shape, and is received by the cavity 36 of the piston 18 that continues to rise. And the hollow cone shape of the injected fuel f collapses,
The injected fuel f diffuses in the cavity 36 while causing reflection, crawling, jumping, and the like.

Here, since the concave shape of the cavity 36 is basically formed by a compound curve or curve, the tumble flow in the combustion chamber is not disturbed, and is gradually uniform and suitable for stratified combustion. A mixture is formed. At this time, a favorable air-fuel mixture suitable for stratified charge combustion in which a part always applies to the electrode portion 32 can be easily formed by the inclined surface 37.

Here, when the fuel injection amount is large at the time of medium load operation or the like, the spray is spread over the cavity 36 and the upper area thereof, and a stratified mixture having a large diffusion volume and uniformly diffused is formed. Further, when the fuel injection amount such as idling is small, the spray is reliably guided toward the spark plug 30.

Since the exhaust side of the cavity 36 is provided with the wall surface 38 a extending above the upper surface 16, diffusion of the stratified mixture to the exhaust side is prevented, and Diffusion in the exhaust EX direction is prevented. After the injection is completed, ignition is performed at an appropriate timing to ignite and burn the air-fuel mixture.

Therefore, the air-fuel mixture can be easily collected near the electrode portion 32 by the inclined surface 37.
Stable stratified combustion can be obtained. In addition, it is possible to prevent the occurrence of air-fuel mixture tears and over-lean regions where flame propagation is impossible, to obtain appropriate and rapid combustion as a whole with a lean air-fuel ratio, and to prevent the occurrence of partial burn.

[0052] Thus, in a wide operating range of the low-load operation region can be obtained a good stratified charge combustion, as described above, as a result good driveability, HC, reduction of NO _X, even the fuel consumption Improvements can also be achieved. Also,
Since the combustion chamber 24 has a combustion space other than the cavity 36, the compression ratio does not increase, and ordinary fuel, that is, regular gasoline can be used.

Further, since the sprayed fuel f is not easily diffused to the cylinder 20 side by the injection direction and the action of the cavity 36 and the wall portion 38, the fuel 2
0 can be prevented, and a decrease in lubricity and occurrence of a functional failure in piston operation can be effectively prevented. Similarly, it is possible to prevent the deterioration of the combustion state and the smoldering of the spark plug 30 caused by the cooling effect caused by the collision of a part of the injected fuel directly with the inner peripheral wall surface of the cylinder 20.

Next, a second embodiment of the present invention will be described below. FIG. 3 is an explanatory sectional view of the second embodiment, and FIG. 4 is a piston 1 used in the second embodiment.
FIG. 8 is an explanatory diagram of FIG. 4, (A) is an explanatory top view of the piston 18, and (B) is an explanatory sectional view taken along line XX of (A). In the drawings, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, a characteristic configuration different from the above-described first embodiment lies in the shape of the opening of the cavity 36. That is, as shown in FIG.
Is provided with a cavity 36 which is opened in a substantially elliptical shape and extends in the same direction as the piston pin 42. The center position of the substantially elliptical opening is formed to be substantially the same as the injection center axis 35 of the injector 34.

Accordingly, similarly to the first embodiment, the injected fuel injected from the injector 34 toward the cavity 36 diffuses in the cavity 36 by performing operations such as reflection, crawling, and jumping. Slope 37
Thereby, a good air-fuel mixture suitable for stratified combustion partially applied to the electrode portion 32 is easily formed.

Since the cavity 36 further has the same width as the piston pin 42 as compared with the first embodiment, the spray is spread when the fuel injection amount is large in a medium load operation state or the like. Space is more fully secured. Thereby, stratified combustion having a higher load limit can be obtained.

Next, a third embodiment of the present invention will be described below. FIG. 5 is an explanatory cross-sectional view of the third embodiment, and FIG. 6 is an explanatory view of a piston 18 used in the third embodiment. 6A is an explanatory top view of the piston 18, and FIG. 6B is an explanatory sectional view taken along line XX of FIG. 6A. In the drawings, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment, a characteristic configuration different from the above-described embodiment is the opening shape of the cavity 36.

The shape of the opening 39 is a substantially elliptical shape extending in a direction perpendicular to the piston pin 42 as shown in FIG. 6A, and the center axis position of the opening 39 is in relation to the axis of the injector 34. They are arranged almost identically. Therefore,
Injected fuel injected from the injector 34 toward the cavity 36 is diffused in the cavity 36 by performing operations such as reflection, crawling, and jumping up, as in the first embodiment. Part must be electrode part 3
A good air-fuel mixture suitable for stratified combustion according to (2) is easily formed.

Since the cavity 36 suppresses the expansion in the same direction as the piston pin 42 as compared with the first embodiment, when the fuel injection amount is small in an idling operation state or the like, excessive spraying is performed. Is suppressed, and the stratified mixture is reliably led to the electrode portion 32 of the ignition plug 30. Thereby, more stable stratified combustion can be obtained at low load.

It should be noted that the present invention is not limited to the configurations of the above-described embodiments, and various modifications can be made within the scope of the invention. For example, in each of the above embodiments, the case where the gas flow due to the weak tumble flow exists has been described. However, when the reflection effect of the spray toward the electrode portion 32 by the inclined surface 37 of the cavity 36 appears strongly, the tumble gas flow is reduced. It is not necessary to adopt a configuration that causes the generation.

In the above-described embodiment, the wall surface 38 extending above the upper surface 16 is provided on the exhaust side of the cavity.
Although a is provided, depending on the state of gas flow generated in the combustion chamber, the same effect can be obtained without providing the wall surface 38a.

[0063]

As described above, according to the in-cylinder injection engine of the present invention, the injected fuel injected from the injector and colliding with the inclined surface in the cavity is reflected and diffused toward the spark plug. Therefore, a stratified mixture that can be ignited can be easily guided around the ignition portion of the ignition plug, and stable ignitability can be obtained.

When the opening shape of the cavity is formed in a substantially elliptical shape having a major axis in the direction of the piston pin, a sufficient diffusion space for the reflected fuel is ensured when the injection amount is large such as under a medium load. Thus, the load limit at which stratified combustion can be performed can be increased.

Further, when the shape of the opening of the cavity is formed in a substantially elliptical shape having a short axis in the direction of the piston pin, excessive diffusion of the reflected fuel when the fuel injection amount is small such as at a low load is suppressed. As a result, stable stratified combustion can be obtained by improving ignitability.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view schematically illustrating a direct injection engine according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of the piston of FIG. 1;

FIG. 3 is a sectional view schematically illustrating a direct injection engine according to a second embodiment of the present invention.

FIG. 4 is an explanatory view of the piston of FIG. 3;

FIG. 5 is a sectional view schematically illustrating a direct injection engine according to a third embodiment of the present invention.

FIG. 6 is an explanatory view of the piston of FIG. 5;

[Explanation of symbols]

 12 Combustion chamber ceiling 14 Cylinder head 16 Upper surface 18 Piston 20 Cylinder 22 Cylinder 24 Combustion chamber 30 Spark plug 32 Electrode 34 Injector 36 Cavity 37 Slope f Fuel

Claims (6)

[Claims] An in-cylinder injection engine comprising: a cylinder head having a pent roof type combustion chamber ceiling; and a piston having a top surface having a flat basic shape, wherein a center of the combustion chamber ceiling is provided. An injector that is disposed at an offset position and injects fuel in a cylinder axial direction at a predetermined timing; and a cavity that is formed in the upper surface portion in a substantially perfect circular shape with a center point at a position substantially coaxial with an injection center axis of the injector. And is provided to project obliquely from the intake side of the ceiling of the combustion chamber into the combustion chamber with respect to the cylinder axis direction, and when the piston is at a substantially top dead center position, it is located at an upper inside position of the cavity. And a spark plug having an ignition portion at a position deviated from the center of the cavity toward the intake side, wherein the cavity is orthogonal to the piston pin. Cylinder injection type engine cross section and having an inclined surface inclined so as to face the firing side is formed in a concave shape. 2. The cavity has a wall portion extending at a predetermined height from the upper surface to a ceiling side of the combustion chamber at an exhaust-side portion of the cavity, and facing a center of the cavity. The in-cylinder injection engine according to claim 1. 3. The direct injection engine according to claim 1, wherein the cavity has a substantially elliptical opening extending in the same direction as the piston pin, instead of the substantially circular opening. . 4. The in-cylinder injection according to claim 1, wherein the cavity has a substantially elliptical opening extending in a direction perpendicular to the piston pin, instead of the substantially circular opening. Expression engine. 5. The injector performs injection such that the injected fuel has a substantially conical hollow shape that gradually expands in an injection direction about an injection center axis of the injector, and a spread angle of the injected fuel is equal to that of the piston. The in-cylinder injection engine according to any one of claims 1 to 4, wherein the spread range of the injected fuel is set to fall within the cavity at a predetermined timing during the vertical operation. 6. The in-cylinder injection engine according to claim 5, wherein the injector has an injection nozzle for giving a fuel in a spiral rotation direction to inject the fuel.