JP2792308B2 - In-cylinder injection type internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 swirled, and fuel is injected into the cylinder to generate a mixture and burn. About.

[0002]

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 stacked in this order to form a main part. An intake / exhaust passage that can communicate with the chamber via an intake / exhaust valve, a valve operating system that drives the intake / exhaust valve, a connecting rod that converts the reciprocating motion of the piston into a rotational motion and transmits the rotational motion to a crankshaft are housed. . In the case where such an internal combustion engine is, for example, a four-cycle engine, fuel corresponding to the amount of intake air is supplied to intake air sucked into a cylinder during an intake stroke to generate combustion energy, and the energy is output as rotational energy. ing.
Among such internal combustion engines, there is known an in-cylinder injection type internal combustion engine capable of improving driving responsiveness by directly injecting fuel into a combustion chamber.

[0003] As this kind of in-cylinder injection type internal combustion engine,
BACKGROUND ART 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, a diesel engine does not require an ignition means, but requires an engine capable of achieving a high compression ratio and a high-pressure fuel injection means, and has a problem in increasing its size and weight.
On the other hand, an in-cylinder injection type gasoline engine is configured, for example, as shown in FIGS. The gasoline engine here is of a four-valve type. A piston 51 is inserted into a cylinder S of the gasoline engine, and a pair of intake valves (not shown) is opened when the piston 51 slides from a top dead center to a bottom dead center. Air is introduced into the combustion chamber 50 from the conduction path 52 through each intake port 54, and an injector (not shown) is driven at a predetermined time during the intake and compression strokes to perform in-cylinder injection, and a spark plug 56 is driven at the end of the compression stroke. In a subsequent exhaust stroke, exhaust gas (not shown) is opened when the piston 51 rises, and an exhaust valve (not shown) is opened.
It is configured to discharge to the side.

[0004] Such a gasoline engine has few problems such as an increase in size and weight as compared with a diesel engine.

[0005]

However, such an in-cylinder injection type gasoline engine has a configuration in which respective conduction paths 52 and 53 extending from the intake / exhaust ports are respectively opened on both side walls of a cylinder head (not shown). Here, conductive paths 52 and 53 and a spark plug 56 are provided in the cylinder facing portion of the cylinder head on the upper side of the combustion chamber. In particular, the conductive paths 52 and 53 are formed large in order to ensure the volume efficiency of each cylinder. Or two intake passages 55 as shown in FIG.
When the exhaust passages 2 and 52 and the two exhaust passages 53 and 53 are provided, there is almost no space for securing the injector mounting portion for mounting the injector. Even if the space can be secured, the design is restricted. However, it is extremely difficult to realize an optimum layout. Further, the injector for in-cylinder injection is directly mounted in the combustion chamber, and it is necessary to sufficiently consider the cooling performance of the injector body and the cooling performance of the fuel. This also has a problem.

An object of the present invention is to provide an in-cylinder injection type internal combustion engine which can easily secure a space for mounting an in-cylinder injector and can improve the volumetric efficiency.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a combustion chamber formed between an upper surface of a piston inserted into a cylinder and a lower surface of a cylinder head;
In the cylinder head, one end is opened so as to communicate with the combustion chamber, the other end is opened on the upper surface of the cylinder head, and the intake passage extends from the opening on the combustion chamber side to the opening on the cylinder head upper surface side. An injector mounting portion formed on one side of the cylinder head and outside the intake passage, and an injector mounted on the injector mounting portion and directly injecting fuel into a combustion chamber. And

[0008]

The conduction path of the intake port extends downward in the cylinder head, and the upstream end thereof is connected to the intake pipe on the upper surface of the cylinder head. In addition, the injector mounting portion can be easily secured, and the inflow resistance of the conduction path can be relatively reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The in-cylinder injection type internal combustion engine shown in FIGS.
Attached). The main body of the engine E is configured by integrally stacking a cylinder head 1 with a head cover, a cylinder block 3, a crankcase and a crank cover (not shown) in this order, and a cylinder S having a piston 2 inserted therein, Intake / exhaust passages 4a, 4b, 5 which can communicate with the combustion chamber 7 formed on the upper part of the cylinder S
a and 5b, a valve train (not shown) for driving a pair of intake and exhaust valves 10 and 11 for opening and closing these intake and exhaust passages, and a crankshaft and connecting rod (not shown) for converting the reciprocating motion of the piston 2 into rotary motion. Is housed. Since the configuration of each cylinder in the engine E here is the same,
Here, one cylinder will be mainly described.

Here, the cylinder head 1 has a pair of sides on one side across a plane FC (here, extending in the longitudinal direction of the head as shown in FIG. 3) including the cylinder axis L along the center of the cylinder S. The intake port 8a is connected to the other side with the exhaust port 9
a. The cylinder S has a cylinder S
A cylinder-facing lower wall surface 6 facing the combustion chamber 7 formed therein is formed, and the lower wall surface is formed with a long wedge-shaped recess 601 in the center thereof in the direction in which the plane FC extends. One side of the wedge-shaped recess 601, that is, one side sandwiching a plane FC including the cylinder axis, a pair of intake ports 8 a and 8 b following the pair of intake channels 4 a and 4 b, and a pair of exhaust channels 5 a on the other side. ,
Exhaust ports 9a and 9b following 5b are respectively 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
The ignition plug 20 is mounted at a substantially central position of the piston 1 at a position facing the peak 232 of the raised portion 23 described later when the piston 2 reaches the TDC position.

Here, the pair of exhaust passages 5a and 5b are curved and extend from the exhaust port 9a as shown in FIGS. 2 and 5, and extend straight in a direction away from the plane FC. It is configured to open to the side wall surface.
The pair of intake passages 4a and 4b are located on one side of the plane FC including the cylinder axis (the right side of the FC in FIG. 3), and are formed so as to extend vertically in the cylinder head 1 in the vertical direction, and downstream thereof. The side communicates with each intake port 8a, and the upstream end is connected to the intake pipe 13 at the upper surface 1f of the cylinder head 1. Here, the upper end of each intake pipe 13 connected to each intake passage 4a, 4b in a straight line communicates with the plenum chamber 14 in the intercooler 141 through each branch pipe 12, and the inlet 17 of the chamber 14 is open. It is connected to a centrifugal scavenging pump 15 with a variable speed pulley. Thus, the intake passages 4a and 4b of the engine E and the intake pipes 13
Has a long vertical shape, the flow resistance to intake air is relatively low, a relatively large amount of intake air is easily supplied to the combustion chamber 7, and the volumetric efficiency of the engine can be improved.

On one side of the plane FC of the cylinder head 1, an injector mounting portion 1a is formed in a region 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 an accumulator 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 for a predetermined injection time (PH, PL in FIG. 7) at a predetermined injection timing (crank angle). Have been.

In the injector mounting portion 1a, since each intake passage 4a extends straight upward from each intake port 8a, an area outside the pair of intake passages 4a is opened. Sufficient space can be secured. For this reason, the injector mounting portion 1a and the injector 18
It is easy to secure the optimal layout of itself. Further, the injector mounting portion 1a is located outside the pair of intake passages 4a, so that it is relatively easy to improve the cooling performance of the injector body and the fuel, to ensure the durability of the injector, and to reduce the heat damage of the injector and the fuel supply system. It is easy to avoid.

A piston 2 is fitted in the cylinder S of the first cylinder. As shown in FIG. 6, 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.
Reciprocate between C. The piston 2 has a skirt portion 21 and a main portion 22 as shown in FIG.
A concave portion 24 and a raised portion 23 are formed on the upper surface of the. Here, as shown in FIG. 3, the concave portion 24 and the raised portion 23 are formed so as 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.

[0015] In this case, the recess 24 is at least orthogonal plane view of the orthogonal line LH with formed eccentrically to the exhaust port 9a side while containing the cylinder axis L (FIG. 2, perpendicular <br/> surface in FIG. 6 A concave portion 24 corresponding to the view is shown.). The raised portion 23 is continuously provided on the intake port 8a side of the concave portion 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 the both walls.
Having. In particular, as shown by the solid line in FIG.
Is located at the top dead center TDC so that the peak 232 approaches the cylinder-facing lower wall surface 6. Note that the side wall vf of the raised portion 23 is continuously connected to a curved surface that is gently raised from the recess 24.

For this reason, as shown in FIG.
Reaches the bottom dead center BDC side at the end of the intake, the intake air flowing from the intake port 8a goes to the upper surface of the piston along the direction of the axis L, and further, the U
The reverse tumble flow TF that turns and rotates around the parallel line LH1 of the orthogonal line LH in the plane FC including the cylinder axis is generated.

Further, as shown by a solid line in FIG. 6, when the piston 2 reaches the end of compression,
A compact combustion chamber C is formed between the side wall vf and the lower wall 6 facing the cylinder. At this time, the air-fuel mixture in the combustion chamber C is flow-regulated by the recess 24 and the side wall vf,
2 flows toward the spark plug 20 in the vicinity, and at this time, the squish SF generated on the side of the outer wall 231 collides with the airflow toward the spark plug 20, and the air-fuel mixture is further agitated, thereby further improving the combustibility. Will be done.

Since the engine E has two cycles, as shown in FIG. 7, the previous combustion stroke is performed from 0 ° of TDC, and the exhaust valve 11 is turned off after 90 ° in crank angle.
To start the exhaust stroke, and further, when the crank angle reaches about 120 °, the intake valve 10 is also opened to start the intake (scavenging) stroke. After the bottom dead center BDC has elapsed, the exhaust valve 11 is closed near the crank angle of 230 ° and the compression stroke is started. Drive. Thereafter, the intake valve 10 is also closed to complete the intake and exhaust, and only the compression stroke is completely performed. Then, when the ignition timing reaches a predetermined ignition timing before the top dead center TDC, the ignition plug 20 is driven to start an ignition process (indicated by a symbol に は in FIG. 7). Due to this ignition processing, the in-cylinder pressure of the combustion chamber rises, pushing down the piston and generating an output.

Here, the injector 18 is controlled so as to perform injection driving for a predetermined injection time PH when the engine is rotating at high speed, and to perform injection driving for a predetermined injection time PL when the engine is rotating at low speed. Thus, at high speed, the fuel and the reverse tumble flow T
By starting the mixing with the air forming F at an early stage, turbulence can be promoted and rapid combustion can be realized. On the other hand, at low speed, the injection is delayed to wait for the generation of the compact combustion chamber C, and the fuel is injected into the compact combustion chamber C to generate a relatively rich air-fuel mixture.
Ignitability can be sufficiently ensured. Furthermore, the compact combustion chamber C is spherical,
Heat loss can be reduced, and low load operation can be stabilized.
Further, the injector mounting portion 1a is provided with a pair of intake passages 4a.
, The cooling performance of the injector body and the fuel is relatively easily improved, the durability of the injector is ensured, and the heat damage is easily avoided. Although FIGS. 1 to 6 illustrate a two-cycle gasoline engine, the present invention may be applied to a four-cycle gasoline engine instead. In this case, the same configuration of the engine body can be used, and redundant description will be avoided.

In this case, as shown in FIG. 8, the four-stroke engine opens the intake valve 10 at 0 ° before TDC, enters the intake stroke, and closes the exhaust valve 11 after 0 ° of TDC. End the process. Thereafter, the piston 2 descends to a crank angle of 180 °, during which a reverse tumble flow TF is generated as shown in FIGS.
Fuel is injected from the injector during the reverse tumble flow TF. As shown in FIG. 8, the injection timing of the injector 18 is controlled such that when the engine is rotating at a high speed, the injection is driven at a predetermined injection timing PH at the early stage of intake, and when the engine is at a low speed, the injection is driven at a predetermined injection timing PL in the late compression period. . Thus, at high speed, mixing of the fuel and the air forming the reverse tumble flow TF is started early to promote turbulence and achieve rapid combustion. On the other hand,
At low speeds, the injection is delayed to wait for the generation of the compact combustion chamber C, where fuel injection is performed, and the squish SF is also agitated, so that ignitability can be sufficiently ensured.

Thereafter, near the TDC 360 °, the squish SF shown in FIG. 6 also acts to further disturb the air-fuel mixture flowing from the compact combustion chamber C to the spark plug 20, thereby further improving the combustibility. When the predetermined ignition timing immediately after that is reached, the ignition plug 20 is driven to start the ignition processing (indicated by the symbol に は in FIG. 8). By this ignition processing, the in-cylinder pressure of the combustion chamber increases, the piston is pushed down, an output is generated, and the combustion stroke is performed up to a crank angle of about 540 °. When the crank angle is around 480 °, the exhaust valve 11 is opened, the exhaust stroke is continued until the crank angle 720 elapses, the opening process of the intake valve 10 for the next intake stroke is performed, and four cycles are completed. In this case, the same operation and effect as in the case of two cycles can be obtained.

In place of the two-cycle four-valve engine E shown in FIG. 1, for example, a two-cycle five-valve engine or a three-valve engine E 'shown in FIG. 9 can be constructed. In the case of the cylinder S of the three-valve engine E 'shown in FIG. 9, each of the intake passages communicates with the pair of intake ports 8a and 8b, and the exhaust passage 5' communicates with one exhaust port 9 '. Here, too, on one side of the plane FC including the cylinder axis L, there is an intake port 8a following the pair of intake passages 4a, 4b, and on the other side, an exhaust port 9 'following one exhaust passage 5'. Each port is formed (see FIG. 9), and each port is opened and closed by an intake valve 10 and an exhaust valve 11, respectively. Further, a spark plug 20 is mounted at a position facing the cylinder axis L.

In this case, the same operation and effect as those of the engine E of FIG. 1 can be obtained. Although each of the engines E, E ', etc. described above is a spark ignition type engine, the present invention can be applied to a compression ignition internal combustion engine instead. In this case, the two-cycle spark ignition of FIG. The same arrangement and arrangement of each port and injector as in the expression engine E can be obtained, and the same operation and effect can be obtained.

[0024]

As described above, according to the present invention, the intake passage extending from the opening on the combustion chamber side to the opening on the top surface of the cylinder head is provided in the cylinder head, and the area outside the intake passage is compared. The injector mounting portion can be formed with a large opening, and the optimum layout of the injector itself can be easily secured, and the degree of freedom of the mounting angle of the injector increases. For this reason, at the time of the intake stroke injection such as a full-open operation, by suppressing the adhesion of fuel to the cylinder liner, a uniform air-fuel mixture can be generated, and the in-cylinder gas temperature is reduced by the latent heat of vaporization of the entire air introduced into the cylinder. Since it can be reduced, the charging efficiency of the intake air is increased, the output is improved, and the emission of smoke and HC can be suppressed. Also, during the compression stroke injection in the low / medium load region, it becomes easy to store the injected fuel in the recess of the piston, and it is possible to stably perform stratified combustion from low speed running to high speed running, thereby improving fuel efficiency. it can. Further, since the injector mounting portion can be formed by opening the region outside the intake passage relatively large, the cooling water passage can be easily arranged in the portion, and the injector and the fuel can be easily cooled. And the heat damage of the injector and the fuel supply system can be avoided.

[Brief description of the drawings]

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

FIG. 2 is a side sectional view of one cylinder of the direct injection internal combustion engine of FIG. 1;

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

FIG. 4 is a schematic diagram viewed from A in FIG. 3;

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

FIG. 6 is an operation explanatory view of a piston in a cylinder of the in-cylinder injection type internal combustion engine of FIG. 1;

FIG. 7 is an explanatory diagram of a drive cycle of the direct injection internal combustion engine of FIG. 1;

FIG. 8 is an explanatory diagram of a drive cycle of a direct injection internal combustion engine of another embodiment.

FIG. 9 is a schematic top view of one cylinder of a direct injection internal combustion engine of another embodiment.

FIG. 10 is a schematic side view of a main part of a conventional direct injection internal combustion engine.

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

[Description of Signs] 1 Cylinder head 1a Injector mounting section 2 Piston 3 Cylinder block 4a Intake conduction path 4b Intake conduction path 5a Exhaust conduction path 5b Exhaust conduction path 7 Combustion chamber 8a Intake port 8b Intake port 9a Exhaust port 9b Exhaust port 10 Intake Valve 11 Exhaust valve 13 Intake pipe 18 Injector 20 Spark plug L Cylinder axis LH orthogonal line LH1 Parallel line FC plane E Engine S cylinder

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-58030 (JP, A) JP-A-62-243945 (JP, A) JP-A-2-96470 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) F02B 1/00-23/10

Claims (1)

(57) [Claims] A combustion chamber formed between an upper surface of a piston inserted into a cylinder and a lower surface of a cylinder head; and one end in the cylinder head is opened so as to communicate with the combustion chamber. An end opening to the upper surface of the cylinder head, an intake passage extending from the opening on the combustion chamber side to an opening on the upper surface of the cylinder head, and formed in a region on one side of the cylinder head and outside the intake passage. An in-cylinder injection type internal combustion engine, comprising: an injector mounting portion that is provided; and an injector that is mounted on the injector mounting portion and that directly injects fuel into a combustion chamber.