JPH064025Y2 - Structure of vehicle swirl chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a structure of a swirl chamber in which a vehicle engine swirl wall made of a ceramic material is combined with vertically split component pieces and fixed by a ring.

[Conventional technology]

There are many known techniques for achieving heat resistance and low fuel consumption by constructing all or part of the wall of the swirl chamber of the engine with a ceramic material (for example, Japanese Patent Laid-Open No. 47-21508). Since the ceramic swirl chamber wall is made by molding, when making only the lower part of the swirl chamber wall with shellac molding, there is no problem because the mold will come off, but the entire swirl chamber wall including the ceiling part is made of ceramic material. At the time of manufacture, the wall of the swirl chamber is divided and formed due to the problem of die cutting.

Conventionally, in the divisional formation of the ceramic swirl chamber wall, the dividing line is horizontal, that is, a plane perpendicular to the axis, as shown in the above-mentioned JP-A-47-21508, and is produced by transverse division. It was usual to be done. This is because if it is split vertically, a gap is created in the abutting part when the combination is loosened, and the swirl chamber and the combustion chamber 6 immediately above the piston communicate with each other in a place other than the injection hole, and desired combustion may not be obtained. Because there is.

[Problems to be solved by the invention]

However, in the case of horizontal production, if the vortex chamber wall surface is a hemispherical surface in the upper part and a substantially cylindrical surface in which the lower part is reduced in diameter downward, it is desirable to have at least three divisions on the core, and increase the division. As a result, there is a problem in that the number of molding dies, the number of molding steps, and the cost increase increase. Further, it is generally difficult to form a laterally sliced divided piece by molding, and there is a problem that it is not suitable for mass production.

In the present invention, the vertical split molding, which has not been seen in the past for forming the wall of the swirl chamber, is applied to facilitate the production, and also the solution for the problem caused by the vertical split is provided, and the vertical split molding is put into practical use. The purpose is to make possible.

[Means for solving problems]

In order to achieve the above object, the structure of a vehicle engine swirl chamber of the present invention is a vehicle engine swirl chamber structure in which an engine swirl chamber wall is made of a ceramic material. Then, the divided vortex chamber wall bodies are assembled in the circumferential direction with shims, and the combined vortex chamber wall bodies are fixed by shrink-fitting with a metal ring from the outer peripheral side, and compression preload is applied to the vortex chamber wall bodies. It consists of

[Action]

In the structure of the engine swirl chamber according to the present invention, the manufacture of the swirl chamber wall can be facilitated by vertically dividing the wall of the swirl chamber.
This vertically divided split vortex chamber wall body is assembled by a ring that is shrink-fitted to the outer periphery. The ring has been used in the past to apply a compressive preload to a ceramic material that is weak against tensile stress and to use it under compressive stress.However, at the same time when this preload occurs, the divided vortex chamber is divided in the circumferential direction. It also has the effect of reciprocally fixing the walls to each other. Further, since the divided vortex chamber wall bodies are in contact with each other through the shims, the combustion surface is not disturbed due to the formation of gaps in the divided surfaces and the flow of gas.

〔Example〕

Hereinafter, preferred embodiments of the structure of an engine swirl chamber according to the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a cylinder block of an engine, 2 is a cylinder head, which is mounted on the top of the cylinder block 1 via a gasket 3. A piston 4 is reciprocally inserted in the cylinder block 1 and a recess is formed on the top surface of the piston 4 to form a part of the piston upper combustion chamber 5. The cylinder head 2 is formed with a recess 6 that opens downward, and the swirl chamber wall 7 is inserted therein. The swirl chamber wall 7 has a swirl chamber 8 therein, and the swirl chamber 8 communicates with the piston upper combustion chamber 5 and a nozzle hole 9 formed at the bottom of the swirl chamber wall 7 and extending obliquely therethrough. Has been done. The swirl chamber wall 7 has holes 10, 11 and 12 penetrating therethrough, and the glow plugs 13 and 12 respectively penetrating the holes 10, 11 and 12 respectively.
The injection nozzle 14 and the sensor 15 at the time of ignition face the swirl chamber 8. Water jackets 16 and 17 are formed around the combustion chamber in the cylinder block 1 and the cylinder head 2, and engine cooling water is circulated therein. The configuration up to this point is the same as the conventional one.

The swirl chamber wall 7 has a disk-shaped bottom portion 7a having a nozzle hole 9 formed therein.
And a cylindrical intermediate portion 7b having a cylindrical outer peripheral surface rising upward from the bottom portion 7a, and a hemispherical ceiling portion 7c extending upward from the intermediate portion 7b. The swirl chamber 8 is formed inside them and has a shape obtained by cutting a sphere at the upper surface of the bottom portion 7a.

The swirl chamber wall 7 is made of a ceramic material such as Si ₃ N ₄ (a fine ceramic material can be used), and is divided into two vertically in the middle of injection molding. Reference numeral A in FIG. 1 indicates the divided surface, and core removal is easy. In FIG. 1, the divided surface A cuts the injection hole 9, but the injection hole 9 may be provided at a position not including the divided surface A.

2 and 3 show the divided vortex chamber wall bodies 7-1 and 7-2 thus formed.

The divided vortex chamber wall bodies 7-1 and 7-2 are circumferentially abutted via a shim 18. The shim 18 is made of a plate-like body having the same plane shape as the contact surface as shown in FIG. The shim 18 has a cushioning property and has a structure that can function as a gasket when tightened, and is made of, for example, an inorganic fiber body, a metal foil film plate body, a laminated body of metal and inorganic material plates, or the like. . The insertion of the shim 18 eliminates the need for precision in the injection molding of the divided contact surface of the divided vortex chamber wall body 7, and sufficient precision can be obtained only by injection molding. It may be more accurate.

The divided vortex chamber wall bodies 7-1 and 7-2 are circumferentially abutted via the shim 18, and then cylinders 19 and 20 are hung from the outer peripheral side to be integrally fixed in the circumferential direction and swirled. A compression preload is applied to the chamber wall 7. These rings 1
Of 9 and 20, the ring 19 is made of a metal-like (Fe material is good) ring that extends continuously in the circumferential direction as shown in FIG. 5, and is located near the central portion in the height direction of the outer circumference of the swirl chamber wall body 7. Shrink fit to generate preload. Since the ring 19 is thin, it is not overloaded and has a large elastic deformation amount. The other ring 20, which is a rod-shaped metal ring, has one circumferential cut, as shown in FIG. 6, and is formed on the outer circumference of the bottom portion 7a of the swirl chamber wall 7 along the entire circumference in the circumferential direction. The split swirl chamber wall bodies 7-1 and 7-2 are fitted into the extending groove 21 and the cut portions are butted and welded to each other to form a ring having no break in the circumferential direction.
Position and fix. It should be noted that the ring 20 may be pre-formed as a closed ring and shrink-fitted. A tensile force is applied to the ring 20 so that the ring 20 and the vortex chamber wall 7 are in close contact with each other so as not to be displaced in the circumferential direction. This may be done by, for example, gripping the ring 20 with a robot at a high temperature and welding the cuts so that a tensile force is generated in the ring 20 at the time of cooling. 22 is a pin integrally welded to the ring 20,
The cylinder head 2 is driven into a groove 23 formed by drilling or the like so as to extend in the exit of the recess 6 of the cylinder head 2 in the axial direction to fix the circumferential position of the swirl chamber wall body 7 with respect to the cylinder head 2.

When the vortex chamber wall body 7 is inserted into the recess 6 of the cylinder head 2 by the fitting of the rings 19 and 20, a gap 24 is formed between the outer surface of the vortex chamber wall body 7 and the surface of the recess 6. It The gap 24 escapes the difference in thermal expansion between the swirl chamber wall 7 and the cylinder head 2, and minimizes heat loss due to heat conduction.

In the structure of the swirl chamber having the above configuration, since the swirl chamber wall body 7 is vertically divided, molding is easy, the number of cores can be reduced and simplified, and the ceramic material is made of SiC, Si ₃ N _4, or the like. It is possible to use low-cost fine ceramic materials without using the highest grade materials.

The ring 19 and 20 need only be fitted by the method of fixing, which is a member that has been necessary in the past for generating preload, but is directly integrated in the circumferential direction of the divided vortex chamber walls 7-1 and 7-2. Since it can be used for static fixation, it is possible to exert a summation effect.

Dividing vortex chamber walls 7-1 and 7 which are problems in vertical division
The gap between the two is sealed by the shim 18 so that no gas leaks in the bypass.

The rings 19 and 20 for providing the preload have a small cross-sectional area, are elastically deformable, and do not give an excessively large preload to the swirl chamber wall 7.

The circumferential fixing of the swirl chamber wall 7 can be facilitated by the pin 22.

[Advantages of the Invention] In the structure of the vehicle engine swirl chamber according to the present invention, since the ceramic swirl chamber wall is divided into two vertically, the molding can be facilitated.

In addition, since it is fixed integrally with the ring in the circumferential direction, the ring for giving the preload can be used as it is,
A reciprocal effect is obtained.

Further, since the divided vortex chamber wall bodies are butted against each other via the shims and combined, it is possible to prevent gas leakage at the butted surfaces and to obtain stable combustion.

[Brief description of drawings]

FIG. 1 is a sectional view of the structure of an engine swirl chamber according to an embodiment of the present invention, FIG. 2 is a perspective view of one divided swirl chamber wall, and FIG. 3 is a perspective view of the other divided swirl chamber wall. FIG. 4 is a perspective view of a shim, FIG. 5 is a perspective view of a ring (bill-shaped), and FIG. 6 is a perspective view of a ring (rod-shaped). 2 ... Cylinder head 7 ... Vortex chamber wall 7-1, 7-2 ... Split vortex chamber wall 8 ... Vortex chamber 18 ... Shim 19, 20 ...... Ring 22 ...... Pin

Claims (1)

[Scope of utility model registration request] 1. In a structure of a vehicle engine swirl chamber in which the swirl chamber wall of the engine is made of a ceramic material, the swirl chamber wall is divided into two vertically divided parts, and the divided swirl chamber walls are mutually circumferentially arranged. Structure of vehicle engine swirl chamber characterized by combining through a shim, shrink-fitting a metal ring from the outer peripheral side to fix the combined swirl chamber wall body and applying compression preload to the swirl chamber wall body .