JPH0763117A - Internal combustion engine having auxiliary chamber - Google Patents

Abstract

PURPOSE:To reduce longitudinal dimension of an engine with an auxiliary chamber of a combustion chamber disposed in between cylinders. CONSTITUTION:An auxiliary chambers 10 is disposed in between cylinders. To reduce the distance between cylinders, part of the auxiliary chamber 10 overlaps on an upper portion of a main combustion chamber 1 of an adjoining cylinder. In a lower portion of a portion of the auxiliary chamber 10, overlapping on the upper portion of the main combustion chamber 1 of the adjoining cylinder, a seal wall 30 is formed, connecting together the outer peripheral wall of the main combustion chamber and a cylinder head 3 integrally. The seal wall 30 thus covers up the portion of the auxiliary chamber 10, overlapping on the upper portion of the main combustion chamber 1 of the adjoining cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine with a sub chamber having a sub chamber above the main combustion chamber of a cylinder.

[0002]

2. Description of the Related Art In an engine having a combustion sub-chamber such as a swirl chamber and a pre-combustion chamber above the main combustion chamber of a cylinder, the sub-chamber is usually arranged at the end of the upper part of the cylinder in the direction perpendicular to the longitudinal direction of the engine. To be done. However, when the sub-chamber is arranged at the end of the upper part of the cylinder at a right angle to the longitudinal direction of the engine in this manner, the fuel injection valve, the fuel pipe, etc. attached to the sub-chamber interfere with the engine intake pipe, etc., causing a problem in the arrangement of the intake pipe. There is.

In order to solve the above problem, for example, in Japanese Utility Model Laid-Open No. 3-83349, a sub-chamber is arranged at the end of the upper part of the cylinder in the longitudinal direction of the engine so that the sub-chamber is located between adjacent cylinders. Therefore, a configuration has been proposed that avoids interference with the intake pipe and the like.

[0004]

However, when the sub chamber is arranged between the adjacent cylinders as in the above Japanese Utility Model Laid-Open No. 3-83349, the longitudinal dimension of the engine cannot be shortened. It becomes difficult to achieve the miniaturization of.
That is, in order to reduce the longitudinal dimension of the engine, it is necessary to reduce the arrangement interval of the cylinders of the engine as much as possible and arrange the cylinders close to each other. For this reason, it is preferable to employ a so-called siamize structure in which adjacent cylinders are arranged with a common wall (cylinder wall) having a relatively thin wall interposed therebetween. However, when such a siamize structure is adopted, since the thickness of the cylinder wall is thin, a sufficient seal width cannot be obtained, and it tends to be difficult to seal the joint between the top surface of the cylinder wall and the cylinder head. . For this reason, high-pressure gas during compression and combustion in the cylinder easily leaks into the adjacent cylinder through the joint between the top surface of the cylinder wall and the cylinder head. There is a problem that the combustion state of the engine deteriorates due to the inflow of combustion gas from the engine.

Moreover, in the structure in which the sub chambers are arranged between the adjacent cylinders as described above, when the distance between the cylinders is shortened, a part of the lower surface of the sub chamber crosses the cylinder wall and the main combustion chambers of the adjacent cylinders are crossed. It will overhang on top and overlap. As will be described later, the temperature of the sub-chamber, especially the nozzle in the lower part of the sub-chamber, becomes high.Therefore, the sub-chamber or the bottom of the sub-chamber is made of heat-resistant metal separately from the cylinder head. It is common practice to fit an auxiliary chamber or the like into the formed recess. However, in the case of such a structure, when a part of the lower surface of the sub chamber overlaps with the upper portion of the main combustion chamber of the adjacent cylinder, the top surface of the cylinder wall is not only the bottom surface of the cylinder head but also the bottom surface of the auxiliary chamber formed separately. Since they come into contact with each other, it becomes more difficult to seal between the top surface of the cylinder wall and the surface of the cylinder head, and there arises a problem that leakage easily occurs, which makes it difficult to achieve downsizing of the engine by adopting the above-described structure.

On the other hand, in order to solve the problem of the seal between the top surface of the cylinder wall and the cylinder head, the cylinder block and the cylinder head are integrally cast so that the cylinder wall and the cylinder head have no joint. An integrated structure (monoblock structure) is also possible. However, also in this case, if the structure is such that the lower surface of the auxiliary chamber overlaps the upper portion of the main combustion chamber of the adjacent cylinder as described above, the problem of the leak cannot be solved.

That is, in the case of a monoblock structure in which the cylinder head and the cylinder block are integrally cast,
Since it is not possible to process the cylinder head after casting to form a recess for fitting the sub chamber, the pre-fabricated sub chamber is mounted inside the mold for casting, and the sub chamber is built in the cylinder head integrated with the cylinder block. Need to be cast. In this case, since the cylinder head and the cylinder wall and the sub chamber are made of different materials, they are not integrally joined by casting, and there is a slight gap between the sub chamber outer wall and the cylinder head and the cylinder wall. A gap will remain. For this reason, if the lower surface of the sub chamber overlaps the upper part of the main combustion chamber of the adjacent cylinder as described above, leakage occurs through these gaps, and even though the monoblock structure is adopted, the leakage increases on the contrary. There will be a problem.

FIG. 4 is a cross-sectional view in the engine longitudinal direction of a cylinder formed in a monoblock structure for explaining the above problem. In FIG. 4, reference numeral 1 denotes a main combustion chamber of two cylinders that are adjacent to each other with a cylinder wall 2 interposed therebetween. Further, 3 is a cylinder head which is cast integrally with the cylinder wall 2, and 10 is a sub chamber arranged in the cylinder head 3 above the main combustion chamber 1. The sub-chamber 10 has a sub-chamber wall 11 made of heat-resistant metal, which is separate from the cylinder head 3, and when the cylinder head 3 and the cylinder wall 2 are integrally cast, the sub-chamber is cast into the cylinder head. It is held in the cylinder head 3.

Further, since the auxiliary chamber 10 is disposed at the longitudinal end of the upper portion of the cylinder 1, a part of the lower surface of the auxiliary chamber 10 is superposed on the main combustion chamber of the adjacent cylinder. However, as described above, the cylinder head 3 and the cylinder wall 2 are
Since the sub chamber wall 11 and the sub chamber wall 11 are made of different materials, the sub chamber wall 11 and the sub chamber wall 11 do not come into close contact with each other, and the space between the outer peripheral portion 11a of the sub chamber wall 11 and the cylinder head 3 and the bottom portion 11b of the sub chamber wall 11 and the cylinder wall 2 There is a slight gap between them. Therefore, as shown by the arrow in FIG. 4, a leak will occur in the main combustion chamber of the adjacent cylinder passing through this portion. Moreover, since the sub chamber wall 11 becomes extremely hot when the sub chamber 10 is formed by casting, the sub chamber wall 11 and the cylinder head 3 are
Since it is virtually impossible to install a sealing material or the like between the cylinder wall 2 and the cylinder wall 2, it is extremely difficult to prevent leakage from this portion.

As described above, in the structure in which the sub chambers are arranged between the cylinders, it has been extremely difficult to prevent the leakage between the cylinders. Was becoming. An object of the present invention is to solve the above problems and to provide an internal combustion engine with a sub-chamber, which has a configuration in which a sub-chamber is arranged between cylinders and which can reduce the dimension in the longitudinal direction of the engine.

[0011]

According to the present invention, in an internal combustion engine having a sub-chamber in a cylinder head above each cylinder main combustion chamber, the sub-chamber is a main chamber of a cylinder in which a part of the sub-chamber lower part is adjacent. It is arranged between the cylinders so as to overlap with the upper part of the combustion chamber, and covers the lower side of the part of the lower part of the auxiliary chamber that overlaps with the upper part of the main combustion chamber of the adjacent cylinder, and the cylinder head part around the auxiliary chamber and the adjacent cylinder main part. Provided is an internal combustion engine with a sub chamber, in which a seal wall integrally connecting with a peripheral wall surface of a combustion chamber is formed.

[0012]

The lower side of the lower part of the sub chamber, which overlaps the upper part of the adjacent main combustion chamber of the cylinder, is completely covered with the seal wall that integrally connects the cylinder head and the cylinder wall around the sub chamber. Therefore, it is possible to prevent the gaps formed between the outer peripheral portion of the auxiliary chamber and the cylinder head and between the lower portion of the auxiliary chamber and the cylinder wall from communicating with the main combustion chamber of the adjacent cylinder.

[0013]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan view showing a positional relationship between each cylinder and an auxiliary chamber of an internal combustion engine with an auxiliary chamber according to the present invention. In the figure, 1 is a main combustion chamber of the cylinder, and 21 and 22 are an intake port and an exhaust port respectively provided in the cylinder head. In this embodiment, each cylinder is provided with two intake ports 21 and two exhaust ports 22.
Is connected to two intake pipes (not shown) connected to the outside of the cylinder head 3 via two independent intake passages 25 provided in the cylinder head 3. Similarly, the exhaust port 22 is connected via a common exhaust passage 26 to an exhaust pipe (not shown) connected to the outside of the cylinder head 3.

Reference numeral 10 in the drawing denotes a sub chamber which functions as a swirl chamber in this embodiment. In order to avoid interference with the intake passage 25 and the intake pipe connected to the intake passage 25, the sub-chamber 10 is arranged at the upper end of the main combustion chamber of the cylinder in the engine longitudinal direction, that is, between the adjacent cylinders. As shown in FIG. 1, in the embodiment according to the present invention, the cylinders are arranged close to each other in order to reduce the longitudinal dimension of the engine, and the wall (cylinder wall) 2 forming the main combustion chamber 1 of each cylinder is The cylinders are partially connected to each other, and the cylinders adjacent to each other share a part of the cylinder wall to form a siamize structure. Also,
The sub-chamber 10 is the above-mentioned connecting portion (siamize portion) of the cylinder wall 2.
2a, and as a result, the sub-chamber 10 is configured to project beyond the siamize portion 2a and to the upper part of the main combustion chamber of the adjacent cylinder. Injection is performed from the injection port 10a into the cylinder combustion chamber 1.

FIG. 2 is a sectional view taken along line II-II in FIG. 1, that is, a sectional view perpendicular to the longitudinal direction of the engine. As can be seen from FIG. 2, the engine of this embodiment has a monoblock structure made of an aluminum alloy in which the cylinder block 4 and the cylinder head 3 are integrally cast, and the cylinder main combustion chamber 1 and the sub chamber 10 are A cooling water bore 5 is formed around the periphery.

As shown in FIG. 2, the sub chamber 10 has a substantially cylindrical shape having a spherical upper portion, and has a sub chamber wall 11 made of a heat resistant material such as heat resistant steel or ceramic. As described above, when the cylinder block 4 and the cylinder head 3 are manufactured in the monoblock structure, the sub chamber 10 is fixed to the upper part of the size portion 2a in the mold and cast into the cylinder head. Reference numeral 6 is a fuel injection valve for injecting fuel into the sub chamber 10. The fuel injection valve 6 is attached to the upper portion of the sub chamber 10 through an attachment hole 6a formed in the cylinder head portion after casting.

Next, FIG. 3 shows a cross section taken along line III-III in FIG. 1, that is, a cross section taken along the longitudinal direction of the engine. As described above, in the present embodiment, the sub chamber 10 is arranged above the cylinder portion 2a of the wall of the cylinder combustion chamber, and a part of the lower surface of the sub chamber 10 is projected to the adjacent main combustion chamber of the cylinder. . Therefore, conventionally, as described above, the outer peripheral portion 1 of the sub chamber 10 is
1a and a portion of the cylinder head 3 contacting the outer peripheral portion 11a, a sub chamber bottom 11b and a sub chamber bottom 11b.
There is a problem that a leak occurs in the adjacent main combustion chamber of the cylinder from a gap formed between the upper portion of the siamize wall 2a in contact with the cylinder.
In the embodiment according to the present invention, in order to solve this problem,
A seal wall 30 is provided to cover the lower portion of the sub-chamber 10 portion that overlaps the adjacent cylinder combustion chambers to prevent leakage from occurring.

The seal wall 30 connects the cylinder wall 2 including the size portion 2a and the cylinder head 3 and is integrally cast as a part of the monoblock structure, so that the lower surface of the overhanging portion of the sub chamber 10 is completely formed. It is formed so as to cover. Therefore, the sub-chamber 10 is completely isolated from the main combustion chamber of the adjacent cylinder, and the gap between the outer wall surfaces 11a and 11b of the sub-chamber 10 and the cylinder head 3 or the size wall 2a is adjacent to the cylinder. No longer communicates with the main combustion chamber of
The occurrence of the aforementioned leakage is completely prevented.

The lower surface of the seal wall 30 forms a flat surface which is continuous with the cylinder head wall surface 3a forming the top of the upper part of the main combustion chamber of the cylinder, and the seal wall 30 portion may project into the main combustion chamber. It is supposed not to. For this purpose, the bottom wall surface 11b of the sub-chamber 10 is provided with a stepped surface 11c having a reduced thickness on the side in contact with the seal wall.
The wall thickness of the seal wall is secured.

As in the embodiment according to the present invention, by providing the seal wall 30 that completely covers the lower surface of the projecting portion of the sub chamber 10 and integrally connecting the cylinder wall 2 and the cylinder head 3, In addition to the effect of preventing the leak to the adjacent cylinder as described above, the following effects can be obtained. That is, during operation, the sub-chamber bottom 11b becomes hot due to combustion in the sub-chamber, so the temperature of the upper portion of the siamize wall 2a that contacts the sub-chamber bottom 11b rises. Therefore, in the conventional structure, there is a problem that the upper part of the siamese wall 2a is deformed by thermal expansion and the roundness of the cross section of the combustion chamber is deteriorated. However, in the embodiment according to the present invention, since the cylinder wall 2 including the siamize wall 2a is integrally connected to the combustion chamber top surface 3a of the cylinder head by the seal wall 30, thermal deformation of the upper portion of the siamize wall 2a due to high temperature is suppressed. Therefore, it becomes possible to prevent deterioration of the roundness of the cross section of the combustion chamber during operation.

Further, in the embodiment according to the present invention, since the lower surface of the seal wall 30 is formed as a flat surface continuous with the combustion chamber top surface 3a, the bottom wall surface 1 of the sub chamber 10 to be cast into the cylinder head is formed.
A stepped surface 11c is formed on 1b. This step surface 1
Since 1c functions as a detent for fixing the sub chamber to the mold and preventing rotation when the sub chamber 10 is cast, the above configuration can improve the direction accuracy of the injection port after the sub chamber is cast. The effect that can be obtained is obtained.

In the embodiment according to the present invention, the injection chamber 10a side of the sub chamber bottom 11b is exposed in the main combustion chamber for injecting fuel, but as shown in FIG. A wall surface 32 may be provided so that the sub chamber 10 is completely cast into the cylinder head. In this case, the injection port 10a is formed on the wall surface 32 and the sub chamber bottom 10a from the main combustion chamber 1 side by drilling after casting, and the opening of the injection port 10a of the wall surface 32 is heat-resistant coated. May be improved.

[0023]

According to the present invention, by providing the seal wall which covers the lower portion of the sub chamber overlapping the upper portion of the adjacent main combustion chamber and integrally connects the cylinder head and the cylinder wall, during the compression stroke or combustion. Since it is possible to completely prevent high-pressure gas from leaking to the adjacent cylinder main combustion chamber during the stroke, it is possible to arrange the sub chamber between the cylinders and reduce the inter-cylinder distance while avoiding interference with the intake pipe, etc. This has the effect of significantly reducing the longitudinal dimension of the engine.

[Brief description of drawings]

FIG. 1 is a plan view showing an arrangement of each cylinder and a sub chamber.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a view similar to FIG. 3 for explaining the problems of the conventional technique.

FIG. 5 is a view similar to FIG. 3, showing another embodiment of the present invention.

[Explanation of symbols]

 1 ... Cylinder main combustion chamber 2 ... Cylinder wall 2a ... Siamese part 3 ... Cylinder head 10 ... Sub chamber 30 ... Seal wall

Claims (1)

[Claims] 1. An internal combustion engine with a sub-chamber having a sub-chamber in a cylinder head above each cylinder main combustion chamber, wherein the sub-chamber is partially overlapped with an upper part of the main combustion chamber of an adjacent cylinder. It is arranged between the cylinders, covers the lower side of the lower part of the sub chamber overlapping the upper part of the main combustion chamber of the adjacent cylinder, and forms a cylinder head part around the sub chamber and a peripheral wall surface of the adjacent cylinder main combustion chamber. An internal combustion engine with a sub-chamber, in which a sealing wall that is integrally connected is formed.