JPH05240044A - Cylinder injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To secure the setting space of an injector for cylinder injection so easily and improve the volumetric efficiency. CONSTITUTION:A combustion chamber 7 is formed in an interspace between the upside of a piston 2 and the underside of a cylinder head 1, and an inlet port 8a is installed at one side of the cylinder head 1 and an exhaust port 9a at the other side, respectively, in holding a plane inclusive of a cylinder axis L along the center of a cylinder, while these ports are interconnected each to the combustion chamber 7 via each of on-off valves 10 and 11. A conducting passage 4a of the inlet port extends downward in the cylinder head 1 and its upstream end is connected to an inlet pipe 13 on top of the cylinder head, and an injector setting part 1a is formed in a side face of the cylinder head at the inlet port side, thereby making an injector 18 attached hereat adjoin to the combustion chamber 7.

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 made into a swirling flow, and fuel is injected into the cylinder to generate a mixture gas for combustion. Regarding

[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, which are stacked in this order to form a main portion. A combustion chamber is composed of a cylinder in which a piston is inserted and an upper portion 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 rotational motion and transmits it to the crankshaft, etc. are housed. .. In the case where such an internal combustion engine is, for example, a 4-cycle engine, fuel corresponding to the intake amount is supplied to the intake air sucked into the cylinder in the intake stroke to generate combustion energy, and the same 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 directly injecting fuel into a combustion chamber to improve operation response.

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 cylinder injection type gasoline engine is configured as shown in FIGS. 10 and 11, 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.

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

[0005]

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, as shown in FIG. 11, the two intake passages 55
2, 52 and the two exhaust passages 53, 53, there is almost no space for securing the injector mounting portion for mounting the injector, and even if the space can be secured, there are design restrictions. However, it is extremely difficult to realize an optimal layout. Furthermore, the injector for in-cylinder injection is directly mounted in the combustion chamber, and it is necessary to fully consider the cooling performance of the injector body and the cooling performance of the fuel, which is also a problem.

An object of the present invention is to provide an in-cylinder injection type internal combustion engine in which it is easy to secure a mounting space for an injector for in-cylinder injection, and moreover, volume efficiency can be improved.

[0007]

In order to achieve the above-mentioned object, the present invention forms a combustion chamber between the upper surface of a piston and the lower surface of a cylinder head, which are fitted in a cylinder, and which is formed at the center of the cylinder. The cylinder head is provided with an intake port on one side and an exhaust port on the other side across the plane including the cylinder axis, and each of the ports is communicated with the combustion chamber via an on-off valve. The conduction path extends downward in the cylinder head, the upstream end of which is connected to the intake pipe on the top surface of the cylinder head, and the injector mounting portion is formed on the side surface of the cylinder head on the intake port side. Facing the combustion chamber.

[0008]

Since the conduction path of the intake port extends downward in the cylinder head and its upstream end is connected to the intake pipe on the top surface of the cylinder head, the side surface area of the cylinder head on the intake port side can be released relatively large. In addition, the injector mounting portion can be easily secured, and the inflow resistance of the conducting path can be relatively reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The in-cylinder injection type internal combustion engine of FIGS. 1 and 2 is a two-cycle four-valve internal combustion engine of in-line four-cylinder (hereinafter simply referred to 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 into which a piston 2 is fitted 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 these 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.

The cylinder head 1 here sandwiches a plane FC (which 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 on the other side and exhaust port 9
a are provided respectively. The cylinder head 1 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 wedge-shaped recess 601 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, 4b 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
The spark plug 20 is mounted at a position substantially opposite to a peak 232 of a protrusion 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 the 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 (right side area of FC in FIG. 3) and extend straightly 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 branch pipe 13 on the upper surface 1f of the cylinder head 1. Here, the upper end of each branch pipe 13 that is directly connected to each of the intake passages 4a and 4b communicates with the plenum chamber 14 with the intercooler 141, and the inlet 17 of the chamber 14 is a centrifugal scavenger with a variable speed pulley. It communicates with the pump 15. As described above, since the intake passages 4a, 4b and the branch pipes 13 of the engine E have a vertically long straight shape, the flow resistance to intake air becomes relatively low and the combustion chamber 7
It is easy to supply a relatively large amount of intake air, 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 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 for a predetermined injection time (PH, PL in FIG. 7) at a predetermined injection timing (crank angle). Has been done.

In the injector mounting portion 1a, the intake passages 4a extend straightly upward from the intake ports 8a, so that 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
It is easy to secure the optimal layout for itself. Furthermore, 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, and the durability of the injector is secured, and the heat damage of the injector and the fuel supply system is prevented. Easy to avoid.

A piston 2 is fitted in the cylinder S of one cylinder, and 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.
Reciprocates between C. This 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, 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, as shown in FIG.

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 orthogonal line view of the orthogonal line LH (a concave portion corresponding to the orthogonal plane view in FIGS. 2 and 6). 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 peak 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 moved to the U by the recess 24 and the side wall vf.
The reverse tumble flow TF that is turned 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 the solid line in FIG. 6, 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. At this time, the air-fuel mixture in the combustion chamber C is subjected to flow regulation by the recess 24 and the side wall vf, and the peak 23
The squish SF generated on the outer wall 231 side collides with the air flow toward the spark plug 20 at this time, and the air-fuel mixture is further stirred, so that the combustibility is further improved. Will be done.

Since such an 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 operated after the crank angle of 90 ° has elapsed.
The intake valve 10 is opened to enter the exhaust stroke, and when the crank angle approaches 120 °, the intake valve 10 is also opened to enter the intake stroke. After the bottom dead center BDC has passed, the exhaust valve 11 is closed near the crank angle of 230 °, the compression stroke is started, and the injection is performed for a predetermined injection time PH during high-speed high-load operation, and for a predetermined injection time PL during low-speed low-load operation. Drive it. After this, the intake valve 10 is also closed to complete the intake and exhaust, and only the compression stroke is performed completely. Then, 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. 7). Due to this ignition processing, the cylinder pressure in the combustion chamber rises, the piston is pushed down, and an output is generated.

Here, the injector 18 is controlled so as to drive the injection for a predetermined injection time PH when the engine rotates at a high speed, and to drive the injection for a predetermined injection time PL when the engine rotates at a low speed. As a result, at high speed, the fuel and the reverse tumble flow T
By starting the mixing with the air forming F early, it is possible to promote turbulence and achieve rapid combustion. On the other hand, at low speed, the injection is delayed to wait for the production of the compact combustion chamber C, and the fuel is injected into the compact combustion chamber C to produce a relatively rich air-fuel mixture, and the squish SF
It is possible to sufficiently secure the ignitability by receiving the stirring action of. Furthermore, the compact combustion chamber C is spherical,
It is possible to reduce heat loss and stabilize low load operation.
Further, the injector mounting portion 1a includes a pair of intake passages 4a.
It is located on the outer side of the engine, and it is relatively easy to improve the cooling performance of the injector body and the fuel, and it is also easy to ensure the durability of the injector and avoid heat damage. Although the 2-cycle gasoline engine has been described with reference to FIGS. 1 to 6, the present invention may be applied to a 4-cycle gasoline engine instead. In this case, the structure of the engine body can be the same, and a duplicate description will be avoided.

In the four-cycle engine in this case, as shown in FIG. 8, the intake valve 10 is opened from 0 ° before TDC, and the exhaust valve 11 is closed after 0 ° of TDC when the intake stroke starts and the exhaust gas from the previous exhaust is exhausted. Finish the process. After this, the piston 2 descends to 180 ° at the crank angle, and during this period, the reverse tumble flow TF is generated as shown in FIGS. 2 and 6.
Fuel is injected from the injector into 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 high speed, the injection is driven at a predetermined injection timing PH in the early suction period, and at low speed, it is driven at a predetermined injection timing PL in the latter compression period. .. 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 wait for the generation of the compact combustion chamber C, the fuel is injected into the compact combustion chamber C, and the stirring action of the squish SF is also received to sufficiently secure the ignitability.

After that, the squish SF shown in FIG. 6 also works in the vicinity of 360 ° before TDC to further generate turbulence in the air-fuel mixture flowing from the compact combustion chamber C toward the ignition plug 20, thereby further improving the combustibility. Immediately after that, when the predetermined ignition timing is reached, the spark plug 20 is driven to start the ignition process (indicated by symbol Δ in FIG. 8). By this ignition process, the in-cylinder pressure of the combustion chamber rises, the piston is pushed down, an output is generated, and the combustion stroke is performed up to a crank angle of approximately 540 °. 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.

Instead of the 2-cycle 4-valve engine E of FIG. 1, for example, a 2-cycle 5-valve engine or a 3-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, 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 again, an intake port 8a following the pair of intake passages 4a, 4b on one side across the plane FC including the cylinder axis L, and an exhaust port 9'following one exhaust passage 5'on the other side. Each of them is formed (see FIG. 9), and each port is opened and closed by an intake valve 10 and an exhaust valve 11, respectively. Further, the spark plug 20 is mounted at a position facing the cylinder axis L.

Also in this case, the same operational effect as 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 also, the two-cycle spark ignition of FIG. The ports and injectors can be arranged in the same manner as in the expression engine E, and the same effects can be obtained.

[0024]

As described above, according to the present invention, since the conduction path of the intake port extends downward in the cylinder head and its upstream end is connected to the intake pipe on the upper surface of the cylinder head, the flow resistance to intake air is compared. It is possible to improve the volumetric efficiency of the engine. Moreover, since the side surface area of the cylinder head on the intake port side of the cylinder can be released relatively large,
The injector can be mounted easily, the optimum layout of the injector mounting part can be easily secured, and this injector mounting part can be located outside the intake passage, and it is relatively easy to improve the cooling performance of the injector body and fuel. It is easy to ensure durability and avoid heat damage.

[Brief description of drawings]

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

FIG. 7 is a drive cycle explanatory diagram of the in-cylinder injection internal combustion engine of FIG. 1.

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

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

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

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

[Explanation of symbols]

 1 Cylinder head 1a Injector mounting part 2 Piston 3 Cylinder block 4a Intake passage 4b Intake passage 5a Exhaust passage 5b Exhaust passage 7 Combustion chamber 8a Intake port 8b Intake port 9a Exhaust port 9b Exhaust port 10 Intake valve 11 Exhaust valve 13 Branch pipe 18 Injector 20 Spark plug L Cylinder axis LH Straight line LH1 Parallel line FC Plane E Engine S Cylinder

Claims (1)

[Claims] 1. A combustion chamber is formed between an upper surface of a piston fitted in a cylinder and a lower surface of a cylinder head, and one side of the cylinder head is sandwiched across a plane including a cylinder axis line along the center of the cylinder. Is provided with an intake port and an exhaust port on the other side, and each of the ports is communicated with the combustion chamber via an on-off valve, and the intake port extends downward in the cylinder head and its upstream end is on the upper surface of the cylinder head. An in-cylinder injection internal combustion engine which is connected to an intake pipe and has an injector mounting portion formed on a side surface of a cylinder head on an intake port side, and an injector mounted on the injector mounting portion facing the combustion chamber. ..