JPS6210418A - Ceramic-made sub-chamber of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent abutting surfaces from chips, cracks and the like by grinding the respective abutting surfaces up to the respective surface roughness not exceeding the specified value on a plurality of ceramic body forming spaces communicated with a main combustion chamber. CONSTITUTION:An upperpart ceramic body 14 is enclosed, to form an upperpart chamber of a swirl chamber 12, and a lowerpart ceramic body 16 is inserted through a metallic ring 18, in a concave part provided on a cylinder head 10. Then, respective abutting surfaces 32, 34 of both ceramic bodies 14, 16 are formed by grinding process, and flaws 36 consisting of concave and convex streaks caused by grinding process are formed on the respective abutting surfaces 32, 34 to extend toward the grinding direction. In this case, the respective surface roughness of the respective abutting surface 32, 34 are processed not to exceed 10S (10mum). Unevenness caused by the respective flaws 36 due to grinding process on the respective abutting surfaces 32, 34 are limited to much finer degree to achieve desired aim by the above mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a ceramic pre-chamber of an internal combustion engine, and more particularly to an improvement of a ceramic pre-chamber composed of a plurality of ceramic bodies in an internal combustion engine such as an automobile. It is something.

(Prior Art) Many attempts have been made to use ceramics for auxiliary chambers such as auxiliary combustion chambers of internal combustion engines such as diesel engines, such as swirl chambers. To improve this, various ceramics including silicon carbide and silicon nitride have been tested by taking advantage of the excellent heat resistance and high strength properties of ceramics. Furthermore, in recent years, for the purpose of improving fuel efficiency and thermal efficiency, attempts have been made to form the entire swirl chamber with ceramics and utilize the heat resistance of ceramics to increase the temperature of the combustion gas inside the swirl chamber. Such a sub-chamber made of ceramic is generally composed of a plurality of ceramic bodies for manufacturing reasons, and a space communicating with the main combustion chamber is formed inside the sub-chamber. For example, Utsukai Showa 60-630
Publication No. 28 and the like discloses that a ceramic auxiliary chamber of an internal combustion engine is constructed from two ceramic members.

On the other hand, such a ceramic auxiliary chamber composed of a plurality of ceramic bodies is installed and arranged inside the cylinder head of an internal combustion engine so that the space formed therein communicates with the main combustion chamber. That will happen. In addition, when installing such a ceramic subchamber, a metal ring or a metal sleeve is provided to integrally hold the plurality of ceramic bodies constituting the subchamber and to facilitate the installation operation into the cylinder head installation hole. A structure in which a plurality of ceramic bodies are held integrally by such a metal ring or metal sleeve and is mounted inside the cylinder head has also been considered.

(Problem) However, when such a ceramic pre-chamber composed of a plurality of ceramic bodies is installed in the cylinder head, due to fuel explosion in the internal combustion engine, engine vibration, etc. Minute knocking occurs between the abutting surfaces of adjacent ceramic bodies, and this knocking causes chips and cranks on the abutting surfaces of each ceramic body, reducing the reliability of the ceramic sub-chamber. There was a problem.

Further, as described above, a plurality of ceramic bodies are held together by a metal ring or a metal sleeve,
Even if the structure is such that the metal ring or sleeve is installed, the holding force of the metal ring or metal sleeve will inevitably decrease due to the increase in temperature of the cylinder head due to the operation of the internal combustion engine. It has been difficult to avoid the problem of conflicts occurring and resulting in defects.

(Solution Means) Here, the present invention has been made to solve all of the conventional problems, and its characteristics are that the present invention is composed of a plurality of ceramic bodies and communicates with the main combustion chamber. In a ceramic auxiliary chamber of an internal combustion engine in which a space is formed inside, the abutting surfaces of a plurality of ceramic bodies that abut each other are ground to a surface roughness of not exceeding 10S. Also,
The present invention involves grinding each of these abutting surfaces to a surface roughness of not exceeding 10S, and abutting the ceramic bodies so that the directions of the grinding marks on the abutting surfaces substantially coincide. It is also characterized by

That is, the present invention is based on the inventors' detailed study of the form of the abutting surfaces where a plurality of ceramic bodies abut against each other, and the surface texture of such abutting surfaces, especially the fineness caused by grinding. We have obtained the knowledge that the formation direction of such fine irregularities (grinding marks) has a great influence on the occurrence of chips or cracks caused by the collision of adjacent ceramic bodies. In the present invention, the abutting surfaces of the ceramic bodies to be abutted are each ground to a surface roughness not exceeding 10S, and the abutting surfaces of the abutting ceramic bodies are 1 side each
In addition to grinding at a surface roughness not exceeding 0.03,
By assembling so that the direction of the grinding marks caused by the grinding process is substantially the same on the abutting surfaces of adjacent ceramic bodies, in other words, the direction is the same, the influence of knocking on such abutting surfaces can be reduced. This effectively suppressed the occurrence of defects such as chipping and cranks.

(Specific Description/Examples of Configuration) The present invention will be described in more detail below with reference to the drawings.

First, FIG. 1 shows an example of a swirl chamber type auxiliary combustion chamber in a diesel engine, in which the entire swirl chamber is made of ceramic. There, 2 is a cylinder body of a diesel engine, and a piston 6 is placed in a cylinder bore 4 formed in this cylinder body 2.
are slidably fitted together so that they can be slid up and down in FIG. On the other hand, above the cylinder body 2, a cylinder head 10 is placed and attached via a gasket 8. This cylinder head 10 is provided with a recess, and an upper ceramic body 14 whose top portion forms a part of an approximately spherical shape and forms an upper chamber of the swirl chamber 12 is mounted in the recess. Furthermore, the eye body made of a predetermined ceramic body, in other words, the lower ceramic body 16, is inserted and attached via the cylindrical metal ring 18 for insertion, so that A predetermined swirl chamber 12 is formed. - Also, glow plugs 20. Through hole 24 for injection nozzle 22
and 26 are provided, and a glow plug 20 and an injection nozzle 22 passing through the cylinder Rad 10 are attached to the upper ceramic body 14. A predetermined amount of fuel is injected into the swirl chamber 12 from the injection nozzle 22, and is combusted in the swirl chamber 12. The combustion swirl flows into the bottom of the lower ceramic body 16. Through the communication hole (nozzle port) 28 provided, it is led into the main combustion chamber 30 where the piston 6 is arranged.

Incidentally, the upper ceramic body 14 and the lower ceramic body 16 forming such a swirl chamber 12 are made of silicon nitride, silicon carbide, zirconia, alumina,
It is formed by molding a ceramic material such as glass ceramics or mullite according to a conventional method.

The abutting surfaces 32 of the upper ceramic body 14 and the lower ceramic body 16 are brought into contact with each other,
34 is formed by grinding the abutment surfaces of the ceramic bodies 14, 16 using a suitable grinding wheel, as is well known to those skilled in the art. Thus, the abutting surfaces 32 and 34 formed by such grinding process
As shown in FIG. 2, grinding traces 36 are formed which are made up of extremely fine uneven lines extending in the grinding direction. The grinding marks 36 are inevitably formed during the grinding process, and are formed as uneven lines having various depths depending on the size of the diamond abrasive grains of the grinding wheel.

Therefore, in the present invention, the surface roughness of the abutting surfaces 32, 34 of the upper ceramic body 4 and the lower ceramic body I6 is preferably 8S (8 μm) so that it does not exceed 103 (10 μm). The upper ceramic body 14 and the lower ceramic body 16 are assembled by grinding the ceramic body 14 and the lower ceramic body 16 so that the abutting surfaces made of the ground surfaces are brought into contact with each other, and a vortex chamber 12 is formed inside them. They were integrated to form a space.

Therefore, in terms of structure, the assembly of the upper ceramic body 14 and the lower ceramic body 16 requires grinding marks 3 on their abutting surfaces 32 and 34.
Since the unevenness caused by G is made finer, if a collision occurs between the upper ceramic body 14 and the lower ceramic body 16 due to fuel explosion, engine vibration, etc. Even so, the occurrence of defects such as chips and cracks on the abutting surfaces 32 and 34 can be effectively suppressed.

Furthermore, in the present invention, preferably <10 as described above.
The direction in which the grinding marks 36, 36 existing on the abutting surfaces 32, 34, which have been ground to a surface roughness not exceeding S, is substantially destroyed, as shown in FIG. , the upper ceramic body 14 and the lower ceramic body 16 are assembled, thereby making it possible to more effectively suppress the occurrence of defects such as chips and cracks as described above. Bare, abutting surface 32.
Since the formation directions of the respective grinding surfaces 36° 36 on the respective abutting surfaces 32 and 34 are substantially aligned, the convex grinding marks 36 on the respective abutting surfaces 32 and 34 contact and collide in an intersecting state. This is because the above-mentioned adverse effects caused by the collision between the ceramic bodies 14 and 16 can be more effectively avoided.

Incidentally, FIGS. 4 and 5 show a diesel engine having a ceramic auxiliary chamber (vortex chamber 12) composed of the above-mentioned upper ceramic body 14 and lower ceramic body 16 under full load for 300 hours continuously. The changes in the abutment surface 32 at the A portion of FIG. 2 of the upper ceramic body 14 during operation are shown.

Note that FIG. 4 shows the abutment surface 32 of the upper ceramic body 14.
The surface roughness of the abutting surface 34 of the lower ceramic body 16 is both 20S, and the direction of the grinding marks 36 on the abutting surface 32 and the direction of the grinding marks 36 on the abutting surface 34 match. The results are shown in the case where no Further, FIG. 5 shows the abutment surface 3 of the upper ceramic body 14.
The abutting surfaces 34 of 2 and the lower ceramic 16 are each ground to a surface roughness of 7S, and the abutting surfaces 32 and 34 are assembled so that the directions in which the grinding marks 36° 36 are formed are almost the same. The results are shown in the case where

As is clear from FIG. 4, when the surface roughness of the abutting surfaces 32, 34 is 2O3, a very violent collision occurs between the upper ceramic body 14 and the lower ceramic body 16. It can be seen that the grinding marks 36 on the abutting surface 32 have been completely scraped off, and that many chips (recesses) 40 have occurred at various locations on the surface. On the other hand, on the abutment surface 32 with a surface roughness of 78, as shown in FIG. 5, no defect (40) as seen in FIG. 4 was found on the surface. The grinding marks 36 remain as they are, and it is recognized that the reliability of the ceramic sub-chamber can be significantly improved.

In the above explanation, an example has been described in which the swirl chamber, which is one of the sub-combustion chambers in a diesel engine, is composed of a plurality of ceramic bodies, but other types of sub-combustion chambers, such as The situation is the same for pre-combustion chamber type, air chamber type, etc., and even if such pre-combustion type is composed of a plurality of ceramic bodies, the present invention is suitable. Needless to say, it can be applied to

Further, the present invention can be suitably applied to a sub-combustion chamber structure of a diesel engine, but is not limited to this, and is applicable to a sub-combustion chamber provided in an internal combustion engine other than a diesel engine. In this case, the present invention can be applied even when the subchamber is composed of a plurality of ceramic bodies.

Furthermore, in the specific example illustrated, the sub-chamber of the internal combustion engine is composed of two parts, the upper ceramic body 14 and the lower ceramic body 16, but the sub-chamber consists of three parts.
There is no difference even if the ceramic body is composed of one or more ceramic bodies, and in such a case, the directions of the grinding marks on the abutting surfaces of adjacent ceramic bodies should be made to match. The Rukoto. Furthermore, the abutting surfaces of the plurality of ceramic bodies are not only provided in the horizontally dividing direction of the subchamber as shown in the example, but also in some cases in the vertically dividing direction of the subchamber. It is also possible to apply the present invention to such cases.

In addition, various changes, improvements, modifications, etc. may be made to the present invention without departing from the spirit of the present invention, and the present invention also includes embodiments to which such changes, etc. are added. , it goes without saying that it is included within that scope.

(Effects of the Invention) As is clear from the above description, the present invention provides a method in which the surface roughness of the abutting surfaces of a plurality of ceramic nox bodies constituting the subchamber of an internal combustion engine is set to IO3, preferably 83 or less, or A plurality of ceramic bodies are assembled by abutting surfaces having such surface roughness so that the directions of the grinding marks match, and thereby the ceramic bodies are This makes it difficult for the abutting surfaces to crack or crack, effectively increasing the reliability of the ceramic body constituting the auxiliary chamber, and this is where the great industrial significance of the present invention lies. .

[Brief explanation of drawings]

FIG. 1 is a partial vertical cross-sectional view showing a sub-combustion chamber portion of a cylinder head in a diesel engine. Figure 2 shows
FIG. 3 is a front view for explaining the properties of the abutting surfaces of the ceramic bodies constituting the auxiliary combustion chamber of FIG. 1, and FIG. 3 is an explanation showing the case where the upper ceramic body and the lower ceramic body are assembled according to an example of the present invention. It is a diagram. FIG. 4 is a sketch diagram of part A in FIG. 2 in the case where the surface roughness of the abutting surfaces of the ceramic bodies is large and the directions of the grinding marks on the abutting surfaces are not made to match;
FIG. 5 is a sketch of part A in FIG. 2 in the case where the surface roughness of the abutting surfaces of the ceramic body is small and the direction of the grinding marks on the abutting surfaces is completely changed. 2 Niji cylinder body 6: Piston IO Niji cylinder head 12: Whirlpool chamber 14: Upper ceramic body 16: Lower ceramic body

Claims (2)

[Claims] (1) In a ceramic auxiliary chamber of an internal combustion engine, which is composed of a plurality of ceramic bodies and has a space inside that communicates with the main combustion chamber, the abutment surfaces of the plurality of ceramic bodies that abut each other, A pre-chamber made of ceramics for an internal combustion engine, characterized in that each chamber is ground to a surface roughness not exceeding 10S. (2) In a ceramic auxiliary chamber of an internal combustion engine that is composed of a plurality of ceramic bodies and has a space inside that communicates with the main combustion chamber, the abutting surfaces of the plurality of ceramic bodies that abut each other are A pre-chamber made of ceramics for an internal combustion engine, characterized in that it is ground to a surface roughness not exceeding 10S, and that the abutting surfaces are abutted so that the directions of the grinding marks are substantially the same.