JP3019045B2 - In-cylinder injection internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a direct injection internal combustion engine mounted on a vehicle, and more particularly to a four-valve direct injection gasoline engine having a small-diameter cylinder bore.

[0002]

2. Description of the Related Art In recent years, a spark-ignition internal combustion engine mounted on a vehicle has been developed to use a four-valve internal combustion engine having two intake valves and two exhaust valves in order to improve intake efficiency and exhaust efficiency. It has increased. In such a four-valve internal combustion engine, an ignition plug (ignition plug) is provided for each cylinder such that the tip faces the combustion chamber at the center of the cylinder bore, so that highly efficient combustion can be realized. Have been. Further, by providing the ignition plug at the center of the cylinder bore, a pair of intake openings of an intake port opened toward the combustion chamber and opened and closed by an intake valve and a pair of exhaust ports of an exhaust port opened and closed by an exhaust valve are provided. The opening diameter of the opening can be made relatively large, and the intake and exhaust efficiency can be improved.

In recent years, in order to reduce harmful exhaust gas components and improve fuel efficiency, an in-cylinder injection gasoline engine (in-cylinder injection type) in which fuel is directly injected into a combustion chamber instead of a conventional intake pipe injection type. Various types of injection type internal combustion engines have been proposed, and their configurations are disclosed in, for example, JP-A-5-240044 and JP-A-8-303245. These in-cylinder injection gasoline engines are also of a four-valve type, and an ignition plug is provided at the center of a cylinder bore.

[0004]

By the way, the direct injection gasoline engine disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-240044 is, for example, a direct injection gasoline engine having a large displacement and a relatively large bore diameter of each cylinder. The ignition plug is disposed at the center of the cylinder bore, and the injection nozzle of the fuel injection valve is disposed near the cylinder wall between the pair of intake openings, so that a pair of intake openings is provided.
The pair of exhaust openings, the fuel injection valve, and the spark plug are each located at an optimum position, so that efficient combustion can be realized.

However, when an in-cylinder injection gasoline engine is to be realized with a small displacement gasoline engine, the cylinder bore diameter of each cylinder is small, so the distance between the cylinder wall and the intake and exhaust openings, the intake opening. The problem is how to arrange the pair of intake openings, the pair of exhaust openings, the fuel injection valve, and the spark plug while ensuring the thickness and the like of the member between the exhaust opening.

Therefore, for example, while maintaining the positional relationship between the pair of intake openings, the pair of exhaust openings, the fuel injection valve, and the spark plug, the opening diameter of one or both of the intake opening and the exhaust opening is reduced. It is considered to be smaller. However, when the opening diameter of the intake opening is reduced, the intake efficiency is reduced, so that the combustion efficiency is deteriorated, and it is difficult to obtain a practically sufficient output in a high-speed region (high-speed rotation region) requiring a large amount of intake air. In addition, if the opening diameter of the exhaust opening is made too small, it leads to a decrease in the exhaust efficiency, and the combustion efficiency also deteriorates, which is not preferable.

The present invention has been made based on the above-described circumstances, and an object of the present invention is to provide a fuel injection valve in which an injection nozzle is provided between a pair of intake openings even when a cylinder bore diameter is small. It is an object of the present invention to provide an in-cylinder injection type internal combustion engine capable of maintaining a high combustion efficiency by optimizing the position of a spark plug by appropriately setting the opening diameters of an intake opening and an exhaust opening while being arranged close to a wall surface.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a cylinder in a cylinder head is provided.
On one side of the plane containing the cylinder axis along the cylinder axis
A pair of intake ports extend from the lower surface of the dahead to the upper surface
And a hemispherical cavity is formed on the top surface of the piston.
In a direct injection type internal combustion engine, the fuel injection valve
The nozzle is located between the two intake openings facing the combustion chamber
Further, the ignition plug is arranged such that the ignition portion faces the combustion chamber and is closer to the exhaust opening side than the plane including the cylinder axis by a range of 4% or more and less than 10% of the cylinder bore diameter.
Circumference, that is, are arranged so as to bias only suitable dimensions obtained experimentally, even small (cylinder bore diameter is less than 80 mm) cylinder injection type internal combustion engine having a cylinder bore diameter, two The opening diameter of the intake opening and the two exhaust openings, that is, the opening area, is extremely suitable for performing intake and exhaust, and the injection nozzle of the fuel injection valve and the ignition portion of the spark plug are located at appropriate positions. As a result, the volume efficiency and the combustion efficiency are maintained high as in the case of a direct injection type internal combustion engine having a large cylinder bore diameter (a cylinder bore diameter of 80 mm or more).

[0009]

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a cylinder block and a cylinder head of a direct injection gasoline engine according to the present invention mounted on a vehicle, and FIG. A view of the lower surface of the head is shown. Hereinafter, the configuration of the direct injection internal combustion engine according to the present invention will be described with reference to FIGS.

The cylinder injection gasoline engine (hereinafter abbreviated as engine) 1 has a cylinder bore diameter b of a predetermined value b1.
(For example, 80 mm), a relatively small intake 2 valve exhaust 2
It is a four-valve small-displacement gasoline engine composed of valves. For example, a four-cylinder gasoline engine is configured to be capable of performing fuel injection not only in the intake stroke but also in the compression stroke for all four cylinders. The engine 1 can be operated at a lean air-fuel ratio with a small amount of fuel. Hereinafter, one of the four cylinders will be described as a representative.

As shown in FIG. 1, a piston 12 is fitted into a cylindrical cylinder 10 of the cylinder block 2. A hemispherical cavity 16 is provided on the top surface of the piston 12 similarly to the conventional direct injection gasoline engine disclosed in the above-mentioned publication (Japanese Patent Laid-Open No. 240044/1993).
Are formed. The shape and operation are the same as those of the above-described conventional in-cylinder injection gasoline engine, and a detailed description thereof will be omitted.

A pair of intake ports 24 is provided on one side of the cylinder head 4 so as to sandwich a base surface (plane) formed including the cylinder axis X of each cylinder and the center line Y of the engine 1 (see FIG. 2). , 24 are formed, and a pair of exhaust ports 28, 28 are formed on the other side. The intake ports 24, 24 are formed by a pair of intake ports (two intake openings) 30, 30 provided on one side of the base surface, being divided by the lower surface of the cylinder head 4 and the top surface of the piston 12. It opens to the combustion chamber 20 and has exhaust ports 28,
Reference numeral 28 denotes a pair of exhaust ports (two exhaust openings) 32, 32 provided on the other side of the base surface, and opens to the combustion chamber 20.

More specifically, in the engine 1, the opening diameter of the intake ports 30, ie, the opening area, is set to be larger than the opening diameter (opening area) of the exhaust ports 32, 32, as in a general engine. (See FIG. 2). In addition, intake port 2
The exhaust ports 28, 28 are cylinder head 4
On the other hand, it is open in the horizontal direction on the side surface of the cylinder head 4, while extending toward the upper surface of the cylinder head 4 from the intake ports 30, 30 substantially along the cylinder axis X. In other words, the intake ports 24, 24 are upright intake ports that stand upright with respect to the lower surface of the cylinder head 4, thereby improving the intake efficiency.

The intake ports 30, 30 are provided with a pair of intake valves 34, 34 for communicating and shutting off the intake ports 24, 24 and the combustion chamber 20, while the exhaust port 3 is provided.
The pair of exhaust valves 2 and 32 are provided with a pair of exhaust valves 36 and 36 for communicating with and shutting off the exhaust ports 28 and 28 and the combustion chamber 20. As shown in the figure, the intake valves 34, 34 and the exhaust valves 36, 36 are provided on the cylinder head 4 so as to also sandwich the above because of the positional relationship between the intake ports 24, 24 and the exhaust ports 28, 28. ing. For more information,
As shown in the figure, the intake valves 34, 34 and the exhaust valves 36, 36 extend in the cylinder head 4 such that their shafts gradually separate from each other toward the upper surface of the cylinder head 4.

The cylinder head 4 has a combustion chamber 20.
A fuel injection valve (injector) 22 is provided to directly inject fuel toward the fuel injection valve. More specifically, as shown in FIG. 1, the fuel injection valve 22 has a predetermined angle so that fuel can be injected obliquely with respect to the cylinder axis X,
Further, as shown in FIG. 2, the injection nozzle 22a faces the combustion chamber 20 at a position relatively close to the outer peripheral wall of the cylinder 10 in a region surrounded by the outer peripheral wall of the cylinder 10 and the pair of intake ports 30, 30. It is attached to the cylinder head 4.

Here, the injection nozzle 22a is connected to the intake port 30,
The reason why the position is relatively close to the outer peripheral wall of the cylinder 10 at a distance from the cylinder 30 is to prevent the intake valves 34, 34 that are being opened from obstructing fuel injection when fuel is injected in the intake stroke. It is. That is, a certain distance is required between the injection nozzle 22a and the intake ports 30, regardless of the size of the cylinder bore diameter b.

The reason why the injection nozzle 22a is slightly recessed from the lower surface of the cylinder head 4 is mainly in consideration of the arrangement of the fuel injection valve 22 and the intake valves 34,34. The allowable fuel injection pressure of the fuel injection valve 22 is set to a high pressure (e.g., during the compression stroke in which the pressure in the combustion chamber 20 becomes high). 50 kgf / cm ² or more).

Then, as shown in FIG.
A concave portion 4a is formed around 2a so as to be gradually depressed toward the cylinder head 4 side. The concave portion 4a is provided to prevent the cone-shaped fuel spray F injected from the injection nozzle 22a positioned deeper than the lower surface of the cylinder head 4 from inadvertently interfering with the lower surface portion of the cylinder head 4 as described above. (See FIG. 1).

The cylinder head 4 has an inlet 3
0, 30 and the central part of the area surrounded by the exhaust ports 32, 32,
That is, the ignition plug (ignition plug) 40 is attached by projecting the ignition part 40a, which is a spark generation part, to an ignition position where the air-fuel mixture in the combustion chamber 20 can be burned most effectively. More specifically, as shown in FIG.
The center point Pc of the igniting part 40a extends from the center line Y to the exhaust port 32,
It is inserted and screwed into the plug hole 4b so as to be offset (biased) by the distance a toward the side 32.

The distance a is, here, the cylinder bore diameter b.
The ratio (a / b) between the distance and the distance a is set within a suitable range, that is, within a range of a predetermined ratio of 4% or more and less than 10%. That is, when the cylinder bore diameter b is a small bore and is small, such as less than a predetermined value b1 (for example, 80 mm), the intake ports 30, 30 are maintained in order to maintain a high combustion efficiency.
The problem is how to set the respective opening diameters of the ignition plug 40 and the exhaust ports 32, 32, and the ignition portion 40a of the ignition plug 40 is set in relation to the intake ports 30, 30, the exhaust ports 32, 32 and the fuel injection valve 22. How to position is an important issue. In this way, the ignition portion 40a is offset from the center line Y so that the ratio (a / b) is within a range of 4% or more and less than 10%. If it is located, even if it is a small bore, the intake ports 30, 30 and the exhaust ports 32, 3
The combustion efficiency can be maintained high by appropriately setting the opening diameter of No. 2.

Here, referring to FIG. 3, as described above, the cylinder bore diameter b is small bore (for example, b = 65).
mm) and smaller than the predetermined value b1 (for example, 80 mm), the ratio (a /
The relationship between b) and the volumetric efficiency μ is shown based on experimental data. Based on the figure, the ratio (a / b) is set to a predetermined ratio 4 when the cylinder bore diameter b is smaller than a predetermined value b1.
A description will be given of an effect obtained by setting the range of not less than 10% and less than 10%. In the drawing, the broken line indicates that the ratio (a / b) is 0%, that is, the case where the ignition unit 40a is located at the center of the cylinder on the center line Y, and the solid line indicates that the ratio (a / b) is 4% or more and 10%. And the dashed line indicates the case where the ratio (a / b) is 10% or more. Further, the two-dot chain line indicates that the cylinder bore diameter b is a large bore (for example, b = 85 mm) and the ratio (a / b) is 0%, that is, the ignition unit 40
The case where a is ideally located is shown for reference.

According to FIG. 3, when the cylinder bore diameter b is small and small, the volume efficiency μ decreases in the high rotation range when the ratio (a / b) is 0% (broken line). This is the ignition part 40a
If the offset is not made, the opening diameter of the intake ports 30, 30 must be reduced, and the intake efficiency deteriorates. When the ratio (a / b) is 10% or more, the volumetric efficiency μ also decreases in the high rotation range (dashed line), but this causes the ignition part 40a to be offset too much and the opening diameter of the exhaust ports 32, 32 to be too large. And the exhaust efficiency sharply deteriorates. On the other hand, when the ratio (a / b) is set within the range of 4% or more and less than 10% (that is, the distance a is, for example, 2.6 mm ≦ a <with respect to the cylinder bore diameter b (= 65 mm)).
6.5 mm), the ratio (a / b) is set to 0% in the large bore, and the ignition portion 40a is positioned at the center of the cylinder (two-dot chain line). High volume efficiency μ with good balance from to high speed range
Is obtained (solid line).

That is, the in-cylinder injection type in which the cylinder bore diameter b is a small bore, is small as less than a predetermined value b1 (for example, 80 mm), and the injection nozzle 22a of the fuel injection valve 22 is arranged as shown in FIG. On gasoline engines,
By positioning the ignition part 40a of the ignition plug 40 so that the ratio (a / b) is within the range of 4% or more and less than 10%,
The opening diameters of the intake ports 30, 30 and the exhaust ports 32, 32 are respectively appropriate, and the intake / exhaust efficiency is high and the volumetric efficiency μ is maintained high as in the case where the ignition section 40a is located at the center of the cylinder with the large bore . it is possible to maintain a high combustion efficiency.

[0025]

As described above in detail, according to the cylinder injection type internal combustion engine of the first aspect of the present invention, the cylinder
One side of the plane containing the cylinder axis in the head
Extending from the lower surface of the cylinder head to the upper surface along the line
An intake port is formed, and a hemispherical cap is
In the direct injection type internal combustion engine in which the cavities are formed, the ignition portion faces the combustion chamber and is at least 4 % and less than 10% of the cylinder bore diameter closer to the exhaust opening side than the plane including the cylinder axis.
There range, that is, were so arranged to to spark plug to bias only suitable size obtained experimentally, in small bore diameter (bore diameter is less than 80 mm) cylinder injection type internal combustion engine However, in order to perform the suction and exhaust of the opening diameters of the two intake openings and the two exhaust openings, that is, the opening areas.
It can be made extremely suitable and the injection nozzle of the fuel injection valve and the ignition part of the spark plug can be located at the appropriate positions, respectively, and the volumetric efficiency is similar to that of a direct injection type internal combustion engine with a large cylinder bore diameter (cylinder bore diameter of 80 mm or more) Thus, the combustion efficiency can be kept high.

[Brief description of the drawings]

FIG. 1 is a view showing a part of a longitudinal section of a direct injection gasoline engine according to the present invention.

FIG. 2 is a view of a cylinder head as viewed from a combustion chamber side, showing a positional relationship of a spark plug.

FIG. 3 is a graph showing the relationship between the ratio (a / b) to the engine rotation speed Ne and the volumetric efficiency μ in the case of a small bore, based on experimental data.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 In-cylinder injection gasoline engine 10 Cylinder 20 Combustion chamber 22 Fuel injection valve 22a Injection nozzle 24 Intake port 28 Exhaust port 30 Intake port (intake opening) 32 Exhaust port (exhaust opening) 34 Intake valve 36 Exhaust valve 40 Ignition plug ( Ignition plug) 40a ignition part

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomoyuki Muraoka 4-2-1-1, Shimomaruko, Ota-ku, Tokyo Inside Mitsubishi Motors Engineering Co., Ltd. (56) References JP-A 1-124042 (JP, U) JP-A Hei 5-21132 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02B 17/00-23/10 F02F 1/24 F02P 13/00

Claims (1)

(57) [Claims] A combustion chamber formed between a lower surface of a cylinder head and a top surface of a piston inserted into a cylinder, and one side of a plane including a cylinder axis in the cylinder head.
Under the cylinder head along the cylinder axis
A pair of intake ports formed extending from the surface to the top surface, and a hemispherical cavity formed on the top surface of the piston
When, with the provided to face the lower surface of the cylinder head into the combustion chamber, two intake opening located on one side of the plane including the silicon <br/> Sunda axis while the lower end communicating with the intake port Two exhaust openings provided on the lower surface of the cylinder head facing the combustion chamber and communicating with an exhaust port and located on the other side of the plane ; and an injection nozzle provided on the cylinder head, wherein the injection nozzle is provided with the combustion nozzle. A fuel injection valve located between the two intake openings facing the chamber; and a cylinder bore provided on the cylinder head, wherein an ignition portion faces the combustion chamber and has a cylinder bore diameter closer to the exhaust opening than the plane. An in-cylinder injection type internal combustion engine, comprising: a spark plug that is deviated in a range of 4% or more and less than 10% .