JPH032680Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Field of Application" The present invention is suitably used in a mounting structure for a ceramic pre-chamber heat insulator of an internal combustion engine.

"Conventional technology" The sub-combustion chamber of a diesel engine is insulated to improve combustion efficiency and to prevent erosion of parts exposed to high temperatures, such as the nozzle holes that communicate with the main combustion chamber. Research is progressing on the use of ceramics, which have excellent heat resistance and heat resistance. However, ceramics have low thermal shock resistance and are prone to damage due to thermal stress. An idea has also been made to provide an air layer in the

However, although the conventional method of preventing the cap from falling off using an annular stopper is effective in soaking the ceramic and relieving stress, when considering the heat insulation effect that contributes to the thermal efficiency of the engine, it is difficult to prevent this air layer from falling off. Gas got in and the insulation was not effective enough. There is also a method of holding the cap with an 0 ring,
Due to insufficient precision, it was impossible to seal the gas in the circumferential direction.

In order to solve this problem, the applicant previously constructed a ceramic auxiliary combustion chamber 21 in which the chamber part and the mouthpiece part are integrated with gaskets 23, 23' having a U-shaped cross section, as shown in FIG. "Mounting structure for a ceramic auxiliary combustion chamber fitted into the mounting hole 27 provided in the cylinder head 24 through the
41827).

“Problems that the invention attempts to solve” However, the above structure
Since the ridge angles 22a and 22b of No. 1 are exposed, there is a risk that chipping may occur near the ridge lines when attaching to the attachment hole 27.

"Means for Solving the Problem" As shown in Fig. 1, the means is a cylinder head in which a ceramic pre-chamber insulator 1 having a thick flange 2 on the outer periphery is formed with a large diameter near the opening end. 4, and a heat shielding ring 8 having an L-shaped cross section facing the hem side edge angle 2b of the brim 2 is press-fitted into the open end of the recess 7, in which the recess 7 and the brim 2 and the gap between the head side ridge angle 2a and the heat shield ring 8.
Gaskets 3, 3' each having a J-shaped cross section are interposed in the gap between the ridge 2b and the bottom edge 2b of the flange 2 to provide an airtight seal.

``Function'' When fitting the pre-chamber insulator 1 into the recess 7, gaskets 3 and 3' can be fitted in advance to the upper and lower two ridge angles 2a and 2b of the collar 2 of the sub-chamber insulator 1. , the gasket protects the edge angle, prevents the ceramic from chipping during fitting, and reduces the possibility of forgetting the gasket. Further, it is desirable for production control that the upper and lower gaskets have the same shape.

Embodiment FIG. 1A is a cross-sectional view of a ceramic pre-chamber heat insulator used in a mounting structure according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view of the mounting structure for the pre-chamber heat insulator.

Reference numeral 1 denotes a silicon nitride sintered pre-chamber insulator having a thick flange 2 on the outer periphery; 3 and 3' have a J-shaped cross section as shown in an enlarged view in FIG. 1C; Gaskets 2a and 2b are fitted, 4 is a cylinder head, 5 is a glow hole, 6 is a nozzle hole, 7 is provided on the lower surface of the cylinder head, and a pre-chamber insulator 1 is fitted with gaskets 3 and 3'. a recess that fits;
8 is a large diameter portion 7a formed near the opening end of the recess 7
A heat shielding ring having an L-shaped cross section is shown, which is press-fitted into the gasket 3' and also externally fitted to the gasket 3' fitted to the edge 2b on the hem side of the collar 2. It makes up the combustion chamber.

With this structure, no abnormality was found when a 4500 rpm full load 300 hour durability test and 10000 cycles of idle 4500 rpm full load (1 minute turn) were performed on a 2000 c.c. 4 cylinder pre-chamber diesel engine.

``Effect of the invention'' Even if the pre-chamber insulator is made of ceramic, it can be easily attached to the cylinder head.

[Brief explanation of drawings]

FIG. 1A is a cross-sectional view of a ceramic pre-chamber heat insulator used in a mounting structure according to an embodiment of the present invention, FIG. 1B is a cross-sectional view of the mounting structure of the pre-chamber heat insulator, and FIG. 1C is the above FIG. 2 is a sectional perspective view of a main part of a gasket used in the mounting structure, and FIG. 2 is a sectional view of a conventional mounting structure. 1... Ceramic subchamber insulation, 2... Tsuba,
3, 3'...gasket, 2a, 2b...edge angle,
4...Cylinder head, 7...Recess, 8...Heat shield ring.

Claims (1)

[Scope of utility model registration request] A ceramic pre-chamber insulator having a thick flange on the outer periphery is fitted into a recess of a cylinder head having a large diameter near the opening end, and a cross section opposite to the hem side edge angle of the flange is fitted at the opening end of the recess. In the case where an L-shaped heat shielding ring is press-fitted, a gasket having a J-shaped cross section is provided in both the gap between the recess and the head edge angle of the collar, and the gap between the heat shield ring and the bottom edge angle of the collar. A mounting structure for a ceramic pre-chamber heat insulator, characterized by an interposed airtight seal.