JPH09317478A - Cylinder injection engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a homogeneous mixture by forming a head side projected body on the dished face of a cylinder head and a piston side projected body opposed thereto on the top face of a piston to cause a squish flow about the top dead center of the piston followed by rapid mixing of fuel and new charge. SOLUTION: In the suction stroke, new charge induced in a combustion chamber 16 from an intake port 20 is regulated for its flow direction into one direction by a head side projected body 34 formed to encircle the intake port 20, and is thus directed into a cavity 38. In the compression stroke thereafter, a fuel injection valve 32 jets fuel out directly into the cavity 38 in a combustion chamber 16, in which cavity the new charge and fuel are mixed together to form a mixture. In the end of the compression stroke when a piston 8 approaches its top dead center, a piston side squish part 42 of the piston side projected body 36 is brought closer to a head side squish part 40 of the head side projected body 34 to cause a squish flow directed into the cavity 38 followed by quick formation of a homogeneous mixture.

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 engine, and more particularly, to rapidly mixing fuel in a cavity with fresh air to promote generation of a uniform air-fuel mixture, and combustion of the air-fuel mixture. The present invention relates to an in-cylinder injection engine that can support the formation of a flame by the above, stabilize combustion in a lean region at a partial load, and improve a fuel consumption rate and a harmful exhaust gas component value in a lean region at a partial load.

[0002]

2. Description of the Related Art As an engine mounted on a vehicle or the like, there is a four-cycle cylinder injection engine provided with a fuel injection valve for directly injecting fuel into a combustion chamber. The cylinder injection engine delays the fuel injection timing at partial load and injects the fuel into the cavity on the top surface of the piston to realize stratification of the air-fuel mixture and reduce fuel consumption in the lean region. it can.

As such a cylinder injection type engine,
JP-A-63-215816, JP-A 1-21933
There is one disclosed in Japanese Patent No.

The in-cylinder injection engine disclosed in Japanese Patent Laid-Open No. 63-215816 has a combustion chamber formed by a cavity formed on the top surface of the piston and the lower surface of the cylinder head, and the tip of the spark plug is attached to the cylinder head. In the engine arranged to face the combustion chamber from the surface, while stratification means for forming a rich air-fuel mixture layer is provided in the upper portion of the combustion chamber, a squish flow is formed by the lower surface of the cylinder head and the piston top surface other than the cavity. A squish zone to be formed is provided, and a protrusion for directing the squish flow toward the spark plug is provided in the cavity.

The in-cylinder injection type engine disclosed in Japanese Patent Laid-Open No. 1-219311 has a spark plug facing a combustion chamber,
It is defined between two squish part defining surfaces, which are a part of the top surface of the piston and a part of the lower surface of the cylinder head, and has an open end and a closed end, and the open end is near the ignition plug. And a squish portion that has been enlarged to a closed end portion of the squish portion, and a part or all of the fuel injected near the piston top dead center position is provided on one of the two squish portion defining surfaces. And a fuel injection valve that injects toward the fuel injection valve.

[0006]

Various shapes have been proposed for the cavity formed on the top surface of the piston of the cylinder injection engine. The fuel injected from the fuel injection valve is mixed with fresh air in the cavity to generate an air-fuel mixture.

However, in the conventional in-cylinder injection type engine, it is difficult to uniformly mix the fuel injected into the cavity and the fresh air in a short time. As a result, a non-uniform air-fuel mixture is generated in the cavity, and there is a disadvantage that a locally rich or thin region is generated.

Therefore, the conventional in-cylinder injection type engine is
Combustion becomes unstable in the lean region at the time of partial load, and there is a disadvantage that the fuel consumption rate and the exhaust harmful component value deteriorate.

In order to solve such a problem, as disclosed in the above publication, a squish zone for forming a squish flow between the lower surface of the cylinder head and the top surface of the piston other than the cavity is provided (Japanese Patent Laid-Open No. 63-63). No. 215816), or one in which a squish portion is provided by part of the top surface of the piston and part of the lower surface of the cylinder head (JP-A 1-21).
No. 9311).

However, the in-cylinder injection type engines disclosed in these publications generate squish flow at a part of the lower surface of the cylinder head and a part of the top surface of the piston other than the cavity, so that the squish flow is directed into the cavity. There is a problem that it is difficult to generate a squish flow.

Therefore, in the cylinder injection type engines disclosed in these publications, it is difficult to uniformly mix the fuel and the fresh air in the cavity in a short time, and the cavity is locally rich or excessive. There is a disadvantage that a thin region is generated, combustion becomes unstable in a lean region at the time of partial load, and the fuel consumption rate and the exhaust gas harmful component value are deteriorated.

[0012]

In order to eliminate the above-mentioned disadvantages, the present invention provides a combustion chamber between the head-side recessed surface of the cylinder head and the piston top surface of the piston. An intake port and an exhaust port are provided in the concave surface on the head side, an intake valve and an exhaust valve for opening and closing the intake port and the exhaust port are provided, and an ignition plug is provided so as to face the combustion chamber. A fuel injection valve for injecting fuel is provided, a head-side projecting body is provided on the head-side concave surface, and a piston-side projecting body is projected on the piston top surface so as to face the head-side projecting body. A cavity for injecting fuel from the fuel injection valve is formed on the piston top surface on the intake port side with respect to the piston side protrusion, and the head side protrusion and the piston side protrusion are provided on the piston. Near dead point Characterized in that the head-side squish portion to generate a squish flow directed into the cavity to close and piston-side squish portion provided to respectively form at.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The in-cylinder injection engine of the present invention has a head-side projecting member provided so as to project on the head-side recessed surface of a cylinder head and a piston top surface so as to face the head-side projecting member. On the piston side protruding body provided by
The head-side squish portion and the piston-side squish portion that generate a squish flow that closely points in the vicinity of the piston top dead center are formed to form a squish flow toward the inside of the cavity near the piston top dead center. The squish flow can rapidly mix the fuel in the cavity with the fresh air to promote the generation of a uniform air-fuel mixture.

[0014]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 11 show an embodiment of the present invention. 1 to 3, 2 is a cylinder injection engine,
Reference numeral 4 is a cylinder block, 6 is a cylinder head, and 8 is a piston. The in-cylinder injection type engine 2 has a piston 8 built in a cylinder 10 of a cylinder block 4, and a head-side concave surface 12 and a piston 8 formed below a cylinder head 6.
A combustion chamber 16 is formed between the piston and the piston top surface 14.

An intake port 20 of an intake port 18 communicating with the combustion chamber 16 is formed in the recess 12 on the head side of the cylinder head 6.
Further, an exhaust port 24 of the exhaust port 22 is provided so as to be opened, and an intake valve 26 and an exhaust valve 28 for opening and closing the intake port 20 and the exhaust port 24 are provided. In this embodiment, the intake port 20 of the intake port 18 and the exhaust port 2 of the exhaust port 22
4 are provided for each two, and the intake port 20 and the exhaust port 2 are provided.
Two intake valves 26 and two exhaust valves 28 for opening and closing 4 are provided respectively.

The cylinder head 6 has a combustion chamber 16
Spark plug 3 to ignite and burn the air-fuel mixture facing the center of
0 to provide the outer edge 4 of the combustion chamber 16 between the two inlets 20.
A fuel injection valve 32 that directly injects fuel into the combustion chamber 16 by directing it toward the center of the combustion chamber 16 so as to face the fourth side.
Is provided.

The in-cylinder injection type engine 2 is provided with a head-side protruding member 34 protruding from the head-side recessed surface 12 of the cylinder head 6, and the piston top surface 14 faces the piston-side protruding member 34 so as to face the head-side protruding member 34. The protrusion 36 is provided so as to protrude. The intake port 20 is located farther than the piston side protrusion 36.
A cavity 38 for injecting fuel from the fuel injection valve 32 is formed by being recessed in the piston top surface 14 on the side.

As shown in FIG. 2, the head-side protruding member 34 is formed in a substantially three-letter shape on the head-side recessed surface 12 between the intake port 20 and the spark plug 30 so as to surround the intake port 20. Are provided. The piston side protrusion 36 is shown in FIG.
As shown in, the piston top surface 14 is formed in a substantially C shape so as to surround the cavity 38. As shown in FIGS. 5 to 7, the piston side protrusion 36 may be formed separately from the piston 8 and attached to the piston top surface 14 so as to surround the cavity 38 with an attaching screw or the like.

The head-side projecting body 34 and the piston-side projecting body 36 are close to each other in the vicinity of the top dead center of the piston 8 as shown by the diagonal lines in FIGS.
Head side squish portion 40 and piston side squish portion 42 for generating a squish flow (arrow) directed in
Are formed and provided, respectively.

The head-side squish portion 40 is formed on the head-side protrusion 34, as shown by hatching in FIG. The piston-side projecting body 36 is provided with a piston-side squish portion 42, as shown by hatching in FIG. The head-side squish portion 40 and the piston-side squish portion 42 are provided on the head-side protrusions 34 and the piston-side protrusions 36 on both outer edges 44 side that are separated from the center of the combustion chamber 16, as shown by the diagonal lines in FIGS. The intake port 20 is formed so as to be sandwiched from both sides.

The head-side squish portion 40 and the piston-side squish portion 42 are close to each other in the vicinity of the top dead center of the piston 8, and generate a squish flow (arrow) directed from the both outer edges 44 of the combustion chamber 16 into the cavity 38. To do.

Next, the operation will be described.

The in-cylinder injection engine 2 sucks fresh air into the combustion chamber 16 from the intake port 20 in the intake stroke. The fresh air sucked into the combustion chamber 16 has its flow direction regulated in one direction by the head-side protrusion 34 formed so as to surround the intake port 20, and is directed in the direction of the cavity 38.

Further, as shown in FIGS. 8 and 9, the direct injection engine 2 injects fuel directly from the fuel injection valve 32 into the cavity 38 of the combustion chamber 16 in the compression stroke,
In the cavity 38, the mixture is mixed with the fresh air thus sucked to generate a mixture.

The cylinder injection type engine 2 is shown in FIGS.
When the piston 8 approaches the top dead center at the end of the compression stroke, as shown in FIG.
0 and the piston-side squish portion 42 of the piston-side protrusion 36 approach each other, and fresh air between both portions 40 and 42 is pushed out to generate a squish flow (arrow) directed into the cavity 38 (see FIG. 3).

As a result, the fuel droplets in the cavity 38 and the fresh air are rapidly mixed by the squish flow,
It is possible to promote the generation of a uniform air-fuel mixture. The generated air-fuel mixture is ignited and burned by the spark of the spark plug 30, presses the piston 8 in the expansion stroke, and is discharged from the exhaust port 24 to the exhaust port 22 in the exhaust stroke.

Thus, the cylinder injection type engine 2
Has a head-side squish portion 40 and a piston-side squish portion 42 that generate a squish flow directed into the cavity 38 in the vicinity of the top dead center of the piston 8. And can be rapidly mixed to promote the production of a uniform air-fuel mixture, which can assist the formation of a flame by combustion of the air-fuel mixture, and stabilize combustion in a lean region at partial load.

As a result, the in-cylinder injection type engine 2 is
Even if the injection timing of the fuel injection valve 32 is delayed, stable combustion can be obtained in a lean state. As shown in FIG. 4, the fuel consumption rate (BSFC) and the harmful exhaust gas component value (BSTHC) in the lean region at the partial load are obtained. ) Can be improved.

The in-cylinder injection type engine 2 is not limited to the above-mentioned embodiment, but various application modifications are possible.

For example, as shown in FIGS. 12 and 13, the head-side projecting body 34 and the piston-side projecting body 36 are provided in the exhaust port 2.
4 and the spark plug 30, the head-side recessed surface 12 and the piston top surface 14 may be provided in a substantially C-shape so as to surround the spark plug 30. The head-side protruding body 34 and the piston-side protruding body 36 are close to each other in the vicinity of the top dead center of the piston 8, and a head that is indicated by a diagonal line that generates a squish flow (arrow) directed in the cavity 38 and toward the spark plug 30. The side squish portion 40 and the piston side squish portion 42 are formed and provided, respectively.

In this way, the exhaust port 24 and the spark plug 30
A cylinder injection engine 2 in which a head side protrusion 34 and a piston side protrusion 36 are formed so as to surround the ignition plug 30 on the head side concave surface 12 and the piston top surface 14 between
Since the squish flow can be directed not only into the cavity 38 but also toward the spark plug 30, in addition to the effect of the above-described embodiment, fresh air can be given to the spark plug 30 to promote combustion.

Further, as shown in FIGS. 14 and 15, the head-side projecting body 34 and the piston-side projecting body 36 are provided in the combustion chamber 16
It is also possible to provide the head-side recessed surface 12 and the piston top surface 14 so as to surround one intake port 20 so as to be biased toward one outer edge 44 side away from the center. The head-side projecting body 34 and the piston-side projecting body 36 are close to each other in the vicinity of the top dead center of the piston 8, and the spark plug 30 in the cavity 38 and the center of the combustion chamber 16 is biased toward the one intake port 20 side. Directional squish flow (arrow)
The head-side squish portion 40 and the piston-side squish portion 42, which are indicated by the diagonal lines, are provided.

In this way, the exhaust port 24 and the spark plug 30
Between the head-side concave surface 12 and the piston top surface 14, the head-side protrusion 34 and the piston-side protrusion 34 are biased toward the one outer edge 44 side away from the center of the combustion chamber 16 and surround one intake port 20, respectively. The in-cylinder injection type engine 2 provided by forming the body 36 can generate the swirl flow (hatching) as shown by the thick arrow in FIG. 14 by biasing the squish flow. The combustion can be accelerated by the swirl flow.

As described above, the head-side squish portion 40 and the piston-side squish portion 42 provided on the head-side protrusion 34 and the piston-side protrusion 36 face each other in the combustion chamber 16 as shown in FIGS. It is possible to change the direction of the squish flow by setting the angle and the position where it is arranged, which is effective for matching the spray characteristic of the fuel injection valve 32 with the cavity 38.

[0035]

As described above, the in-cylinder injection engine of the present invention can generate a squish flow toward the inside of the cavity on the top surface of the piston near the top dead center of the piston, and the squish flow causes fuel in the cavity to be generated. And fresh air can be rapidly mixed to promote the production of a uniform air-fuel mixture.

Therefore, the in-cylinder injection type engine of the present invention can rapidly mix the fuel in the cavity and the fresh air to promote the generation of a uniform air-fuel mixture, and the formation of a flame by the combustion of the air-fuel mixture. Can be supported to stabilize the combustion in the lean region at the partial load, and as a result, the fuel consumption rate and the exhaust gas harmful component value in the lean region at the partial load can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a direct injection type engine showing an embodiment of the present invention.

FIG. 2 is a bottom view of the cylinder head of FIG. 1;

FIG. 3 is a plan view of the piston of FIG.

FIG. 4 is a diagram showing a relationship between a fuel consumption rate and an exhaust gas harmful component value depending on the presence or absence of squish.

FIG. 5 is a plan view of a piston side protrusion.

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is a front view of a piston-side protruding body.

FIG. 8 is a cross-sectional view of a cylinder injection type engine at the time of fuel injection.

9 is a plan view of the piston in FIG. 8. FIG.

FIG. 10 is a cross-sectional view of the in-cylinder injection type engine when the piston is near the top dead center.

FIG. 11 is a plan view of the piston in FIG.

FIG. 12 is a plan view of a combustion chamber of a cylinder injection type engine showing another embodiment.

13 is a perspective view of the in-cylinder injection type engine in FIG. 12. FIG.

FIG. 14 is a plan view of a combustion chamber of a cylinder injection engine showing still another embodiment.

15 is a perspective view of the in-cylinder injection type engine in FIG. 14. FIG.

FIG. 16 is a cross-sectional view of an in-cylinder injection engine in which a squish flow is directed in a direction parallel to the recessed surface on the head side.

FIG. 17 is a sectional view of an in-cylinder injection type engine in which a squish flow is directed in a direction parallel to the piston top surface.

[Explanation of symbols]

 2 In-cylinder injection type engine 4 Cylinder block 6 Cylinder head 8 Piston 10 Cylinder 12 Head side concave surface 14 Piston top surface 16 Combustion chamber 18 Intake port 20 Intake port 22 Exhaust port 24 Exhaust port 26 Intake valve 28 Exhaust valve 30 Spark plug 32 Fuel injection valve 34 Head-side protruding body 36 Piston-side protruding body 38 Cavity 40 Head-side squish portion 42 Piston-side squish portion 44 Outer edge

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F02F 3/26 F02F 3/26 A

Claims (5)

[Claims] 1. A combustion chamber is provided between a head-side recessed surface of a cylinder head and a piston top surface of a piston, and an intake port and an exhaust port are provided in the head-side recessed surface. And an intake valve and an exhaust valve for opening and closing an exhaust port, a spark plug facing the combustion chamber, a fuel injection valve for directly injecting fuel into the combustion chamber, and a head on the recessed surface on the head side. A projecting side projection is provided, and a piston projecting body is provided projecting on the piston top surface so as to face the head projecting body, and the piston top surface is closer to the intake port than the piston projecting body. A cavity for injecting fuel from the fuel injection valve is formed so as to generate a squish flow which is close to the head-side projecting body and the piston-side projecting body in the vicinity of the piston top dead center and is directed into the cavity. An in-cylinder injection engine characterized in that a head-side squish portion and a piston-side squish portion are respectively formed and provided. 2. The head-side projecting body is formed on the recessed surface on the head side between the intake port and the spark plug so as to surround the intake port. In-cylinder injection type engine. 3. The head-side squish portion and the piston-side squish portion are formed so as to sandwich the intake port from both sides in the head-side protruding body and the piston-side protruding body on both outer edge sides that are separated from the center of the combustion chamber. The in-cylinder injection engine according to claim 1, wherein the in-cylinder injection engine is provided. 4. The head-side projecting body and the piston-side projecting body are respectively formed on the head-side concave surface between the exhaust port and the spark plug and on the piston top surface so as to surround the spark plug. The in-cylinder injection type engine according to claim 1, wherein 5. The head-side projecting body and the piston-side projecting body are formed on the recessed surface on the head side and the top surface of the piston, respectively, which are biased toward one outer edge side away from the center of the combustion chamber. The in-cylinder injection engine according to claim 1.