JPH0429055Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a pre-chamber structure for an engine, and more particularly to a pre-chamber structure for an engine at least partially composed of ceramic parts.

(Prior Art) It has been known for a long time that an engine sub-combustion chamber is made of ceramic. Ceramic materials have excellent heat resistance, so they are advantageous as constituent materials for the subchamber, but they have low thermal conductivity and coefficient of thermal expansion, low brittleness, and are extremely susceptible to tensile stress. have different properties. Therefore, various proposals have been made to solve the problems caused by the unique properties of these ceramic materials.

For example, Japanese Utility Model Application No. 58-175118 discloses a sub-chamber structure in which a metal sleeve is fitted on the outside of a ceramic component forming the sub-chamber. The outer ends of the upper and lower parts of the metal sleeve are fitted into the inner wall of the sub-chamber fitting recess formed in the cylinder head, and between the middle part of the outer periphery of the metal sleeve and the inner wall of the sub-chamber fitting recess. A heat insulating space is formed. The structure disclosed in this published utility model publication is such that the sub-chamber is divided into upper and lower parts in order to facilitate the manufacture of the sub-chamber of ceramic material.
It has a divided structure, and a metal sleeve is fitted to the outside in order to assemble the two divided parts together. However, this construction offers several advantages in addition to the ease of manufacturing the ceramic antechamber. That is, in this structure, by fitting the metal sleeve around the outer periphery of the ceramic material constituting the subchamber, it is possible to suppress the application of tensile force to the ceramic material. Also,
Since metal materials are good conductors of heat, the problem of heat dissipation from the metal sleeve lowering the temperature of the outer wall surface of the ceramic subchamber and creating a sharp temperature gradient between the inner and outer surfaces of the subchamber can be solved. This problem can be solved by providing an insulating space between the outer periphery of the metal sleeve and the inner wall of the sub-chamber fitting part of the cylinder head.As a result, thermal stress can be alleviated and cracks in the ceramic can be prevented. .

(Problem that the invention aims to solve) However, in the conventional structure, a metal sleeve is fitted over the entire upper and lower ceramic parts, which are divided into two parts, the upper and lower parts. The vertical expansion of the metal sleeve becomes larger than the vertical expansion of the metal sleeve, and the upper ceramic part and the lower ceramic part are separated by the metal sleeve, creating a gap on the mating surface, causing combustion gas to directly hit the inner surface of the metal sleeve. , there is a problem that the metal sleeve burns out. Furthermore, the metal sleeve for fixing the ceramic was expensive.

The purpose of the present invention is to provide a pre-chamber structure for an engine that eliminates the gap between the upper and lower parts of the ceramic member during engine operation, prevents ring burnout, and allows the ceramic member to be fixed at a low cost. be.

(Means for Solving the Problems) The present invention provides an engine sub-chamber structure in which the sub-chamber is formed of a ceramic member which is divided into upper and lower parts. First and second retaining rings whose inner peripheries are fitted together and whose outer peripheries are press-fitted into the inner wall of the cylinder head recess and define a heat insulating space, the lower end outer periphery of the upper ceramic member, and the lower ceramic member. The inner periphery fits into both parts of the upper outer periphery of the
The present invention is characterized by the provision of a third retaining ring whose outer periphery abuts the inner wall of the cylinder head recess at least when hot.

(Function) According to the present invention, both the outer circumference of the lower end of the upper ceramic member and the outer circumference of the upper end of the lower ceramic member are held by a short third holding ring in the vertical direction, and when the engine is running, The upper ceramic member and the lower ceramic member are separated by the third retaining ring so that no gap is created in the mating surfaces.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

Referring to the figure, subchamber structure 1 according to the present invention
is adapted to be accommodated in a recess 3 formed in the cylinder head 2. The sub-chamber structure 1 includes a ceramic member 4 that forms a sub-chamber 4a therein, and a first holding thing 5 that supports the ceramic member.
a, a second holding ring 5b, and a third holding ring 5c.

The first retaining ring 5a has its inner circumference fitted to the outer circumference of the upper end of the upper ceramic member, and its outer circumference is press-fitted into a stepped portion 3a formed in the recess 3 of the cylinder head. The second retaining ring 5b has its inner circumference fitted to the lower end outer circumference of the lower ceramic member, and its outer circumference is press-fitted into the large diameter portion 3b formed in the recess 3 in a press-contact state. The ceramic member 4 is fixed to the cylinder head 2 at two locations by a first retaining ring 5a and a second retaining ring 5b.
As a result, compressive stress is applied from the outer surface. A certain heat insulating space 11 is formed around the ceramic member 4 by both rings 5a and 5b, and between it and the recess 3 of the cylinder head.

Further, the third retaining ring 5c has an inner periphery that fits into both the outer periphery of the lower end of the upper ceramic member and the outer periphery of the upper end of the lower ceramic member, and the outer periphery of the third holding ring 5c fits into the cylinder head recess 3 at least when hot. It is designed to come into contact with the inner wall of the In the embodiment, when cold, there is a gap between the ring 5c and the inner wall of the recess 3, and when hot, the ring 5c contacts the inner wall of the recess 3, and the heat of the ring 5c is transferred to the cylinder head 2. can be conducted to.

It should be noted that the first retaining ring 5a and the second retaining ring 5b are preferably formed of a material with lower expansion than the third retaining ring 5c, such as Incoro Alloy 903. Further, the third retaining ring 5c is preferably formed of a material with higher heat resistance and strength than the first retaining ring 5a and the second retaining ring 5b, such as Inconel 718.

A glow 7 for heating the inside of the auxiliary chamber 4a is arranged in the upper part of the cylinder head recess 3, and the glow 7 is connected to the glow hole 4 provided in the ceramic member 4.
It is inserted into the subchamber 4a through b. Further, a fuel injection nozzle 8 is attached to the upper part of the cylinder head recess 3 on the side opposite to the glow 7, and the fuel injected from the fuel injection nozzle 8 is transmitted through a nozzle hole provided in the upper part of the ceramic member 4. The air is blown into the subchamber 4a through 4c.
Further, in the lower part of the ceramic member 4, there is a nozzle 4d for injecting combustion gas in the subchamber 4a into the combustion chamber.
is provided.

(Effects of the invention) According to the invention, since the ceramic member is held by the first, second, and third holding rings, it is possible to eliminate gaps between the upper and lower divided parts of the ceramic member during engine operation. Burnout of the ring can be prevented, and ceramic members can be fixed at low cost.

[Brief explanation of the drawing]

The figure is a sectional view of the subchamber structure of an engine according to the present invention. 1... Sub-chamber structure, 2... Cylinder head, 3
...Concave portion, 3a...Stepped portion, 3b...Large diameter portion, 4...
...ceramic member, 4a...subchamber, 5a...first
retaining ring, 5b... second retaining ring,
5c...Third holding ring, 11...Insulating space.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In an engine sub-chamber structure in which the sub-chamber is formed of a ceramic member divided into upper and lower parts, an inner part is provided at the upper end outer circumference of the upper ceramic member and the lower end outer circumference of the lower ceramic member, respectively. first and second retaining rings whose peripheries fit together, whose outer peripheries are press-fitted into the inner wall of the cylinder head recess, and which define a heat insulating space; a lower end outer periphery of the upper ceramic member; and an upper end outer periphery of the lower ceramic member. A sub-chamber structure for an engine, comprising: a third retaining ring whose inner periphery fits into both parts of the cylinder head, and whose outer periphery abuts the inner wall of the cylinder head recess at least when hot. (2) The third retaining ring is made of a material with higher heat resistance and strength than the first and second retaining rings. Chamber structure. (3) The first and second retaining rings are made of a material with lower expansion than the third retaining ring. Engine pre-chamber structure.