JPS6210417A - Ceramic-made sub-chamber of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent abutting surfaces from chips, cracks and the like by practically adjusting the direction of flaws due to forming process on the respective abutting surfaces in the case of a plurality of ceramic body which form spaces communicated with a main combustion chamber. CONSTITUTION:An upperpart ceramic body 14 is enclosed to form the upperpart 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, fuel injected from an injection nozzle 22 is burnt in the swirl chamber 12, and the burnt swirl is made to be led into a main combustion chamber 30 through the nozzle hole 28 of the lowerpart ceramic body 16. In this case both upper and lower ceramic bodies 14, 16 are incorporated together so as to roughly adjust the forming direction of flaws 36 due to forming process on the respective abutting surfaces 32, 34. Contact and collision of both abutting surfaces 32, 34 occurring in the condition that the respective flaws 36 due to forming process cross each other can be eliminated 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 sub-combustion chambers such as sub-combustion chambers of internal combustion engines such as diesel engines, such as swirl chambers. Therefore, 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.

Furthermore, even if a plurality of ceramic bodies are integrally held and mounted using a metal ring or a metal sleeve as described above, the holding force of the metal ring or metal sleeve is insufficient for internal combustion engines. It is unavoidable that the temperature of the cylinder head decreases due to the increase in temperature caused by the operation of the cylinder head. Therefore, it is possible to avoid the problem of similar collisions occurring on the contact surfaces and the occurrence of chips, etc.
It was difficult.

(Solution Means) Here, the present invention has been made to solve all the problems of the conventional art, and its feature is that the present invention is composed of a plurality of ceramic bodies, and is connected to the main combustion chamber. In a ceramic pre-chamber of an internal combustion engine in which a communicating space is formed inside, the abutting surfaces of the plurality of ceramic bodies that abut each other are ground, and the direction of the grinding marks on the abutting surfaces is The reason is that a structure is adopted in which the ceramic bodies are brought into contact with each other so that they substantially match.

That is, the present invention has been made possible by the detailed study by the present inventors of the form of the abutting surfaces on which such a plurality of ceramic bodies abut, and the fine irregularities of the grinding marks on such abutting surfaces are This was completed based on the knowledge that the impact of ceramic bodies having a large effect on the occurrence of chips or cracks, and the present invention does not require such grinding. By making the machining marks substantially coincident with each other on the abutting surfaces of adjacent ceramic bodies, in other words, in the same direction, the effects of hitting each other on the abutting surfaces can be effectively suppressed. This made it possible to significantly suppress the occurrence of defects such as chips 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 inserted into a cylinder pore 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 mounted through the cylindrical metal ring 18 for insertion, so that A predetermined swirl chamber 12 is formed.

Further, glow plugs 20. Through holes 24 and 26 for injection nozzles 22 are provided so that the glow plug 20 and injection nozzle 22 passing through the cylinder head 10 are attached to the upper ceramic body 14. Then, from the injection nozzle 22, a predetermined fuel is injected into the swirl chamber 12.
The combustion vortex is injected into the vortex chamber 12, and the combustion vortex is
Through a communication hole (nozzle port) 28 provided at the bottom of the lower ceramic body 16, it is led into the main combustion chamber 30 in which the piston 6 is disposed.

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, a grinding mark 36 consisting of extremely fine uneven lines extending in the grinding direction is formed. The grinding marks 36 are inevitably formed during the grinding process, and are formed as irregularities of various depths, for example, about 1 μm to 15 μm, depending on the size of the abrasive grains of the grinding wheel. be.

Therefore, in the present invention, the upper ceramic body 14 and the lower ceramic body 16 are arranged in the direction in which the grinding marks 36, 36 are formed on the abutting surfaces 32, 34, respectively, as shown in FIG. As shown in FIG. 3, they were assembled so that they were almost aligned, and they were integrated so that a space as a vortex chamber 12 was formed inside them.

Therefore, in terms of structure, the assembly of the upper ceramic body 14 and the lower ceramic body 16 according to the present invention requires the respective grinding marks 36 on the abutment surfaces 32, 34.
．． 36 are formed in substantially the same direction, the protruding strip-shaped machining marks 36 on the respective abutting surfaces 32 and 34 do not come into contact or collide in an intersecting state. Due to an explosion, engine vibration, etc., the upper ceramic body 14 and the lower ceramic body 16
Even if a collision occurs between the two, it is possible to effectively prevent defects such as cracks and cranks from occurring on the abutting surfaces 32 and 34.

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 state of change in the abutment surface 32 at the A portion of FIG. 2 of the upper ceramic body 14 during operation is shown at 0, respectively. Note that FIG. 4 shows a case where the direction of the grinding marks 36 on the abutting surface 32 of the upper ceramic body 14 and the direction of the grinding marks 36 on the abutting surface 34 of the lower ceramic body 16 do not match, FIG. 5 shows the results when the directions in which the grinding marks 36° 36 were formed were almost the same.

First, FIG. 4 clearly shows a situation where a chip has occurred on the abutting surface 32 of the ceramic body 14. That is, the grinding marks 36 are observed on the entire abutting surface 32, and in addition, there are scratches 40 diagonally intersecting with the grinding marks 36, and at the same time, the presence of a recess 42 is also observed. The scratches 40 diagonally crossing the grinding marks 36 are the grinding marks 3 on the abutting surface 34 of the other ceramic body, that is, the lower ceramic body 16.
It is thought that it was formed by a collision with 6. Note that 38 and 38 located on both sides of the abutment surface 320 are chamfered portions.

On the other hand, considering the grinding direction of the abutting surface 32, the direction of the grinding marks 36 on the abutting surface 32 is made to match the direction of the grinding marks 36 on the abutting surface 34 of the lower ceramic body 16. In this case, as shown in Fig. 5, the defective parts (40, 42) seen in Fig. 4 were not found, indicating that the reliability of the ceramic subchamber was significantly improved. Is recognized. In addition, in FIG. 5, the black parts seen between the grinding traces 36 are the soot 44 produced by combustion of fuel.

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 chamber type is composed of a plurality of ceramic bodies, the present invention can be applied. Needless to say, it can be suitably applied.

Further, the present invention can be suitably applied to a sub-combustion chamber structure of a diesel engine, but is by no means limited to this, and can be applied to a sub-combustion chamber provided in an internal combustion engine other than a diesel engine. The present invention is also applicable to the case where the sub-chamber 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 problem 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 illustrated, 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 makes the directions of the grinding marks on the abutting surfaces of the plurality of ceramic bodies constituting the pre-chamber of an internal combustion engine coincide with each other. The ceramic bodies are assembled together, thereby preventing the occurrence of chips, cranks, etc. on the abutting surfaces of the ceramic bodies, and effectively increasing the reliability of the ceramic body constituting the subchamber. This is where the present invention has great industrial significance.

[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 form of the abutting surfaces of the ceramic bodies constituting the auxiliary combustion chamber of FIG. 1, and FIG. 3 is an explanatory diagram showing the case where the upper ceramic body and the lower ceramic body are assembled according to the present invention. Figure 4 is a sketch diagram of part A in Figure 2 when the directions of the grinding marks are not matched, and Figure 5 is a sketch diagram of part A in Figure 2 when the directions of the grinding marks are matched. It is a sketch diagram of a part. 2 cylinder body 6: piston 10 cylinder head 12: swirl chamber 14: upper ceramic body 16: lower ceramic body

Claims (1)

[Claims] 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 abutment surfaces of the plurality of ceramic bodies that abut each other are ground. Then,
A pre-chamber made of ceramic for an internal combustion engine, characterized in that the abutting surfaces are abutted so that the directions of grinding marks on the abutting surfaces substantially match.