JPS61119892A - Heat-insulating structure of heat engine, etc. - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heat insulating structure for a heat engine, etc., which provides heat shielding between a ceramic heat insulating type and a metal structure in terms of heat rays.

[Prior Art] Insulating engines using ceramics that have been proposed in the past have been using monolithic silicon dioxide or silicon carbide on the piston crowns, cylinder liners, cylinder heads, fire decks, and other walls that are exposed to combustion gas. This is mainly made of ceramic, which is bonded to the inner surface of metal structures such as the piston body, cylinder body, and cylinder head. In order to suppress heat dissipation from the ceramic insulation wall, a means for interposing a cavity or an air layer between the ceramic insulation wall and the metal structure (Japanese Patent Application No. 1983-
No. 151885), and means (Japanese Patent Application Laid-Open No. 58-25552) in which a gasket made of a metal plate is sandwiched between a ceramic heat insulating wall and a metal structure are adopted in the portion subjected to explosion pressure. However, such means have a limit in suppressing the amount of heat transferred from the ceramic heat insulating wall to the metal structure. In other words, even though the thermal conductivity of the wall during combustion is reduced by 1/25th due to the adoption of the ceramic insulation wall, the heat drop between the combustion chamber and the metal AA body is 3 times as large. , the amount of heat transfer is reduced to only about one-seventh.

[Problems to be Solved by the Invention] Therefore, it is necessary to insulate the combustion chamber by suppressing heat convection and heat radiation in the space between the metal structure and the ceramic insulation wall. .

An object of the present invention is to provide a heat insulating structure such as a heat engine that is effective in suppressing heat convection in a space between a ceramic heat insulating wall and a metal structure.

[Means for solving problems]

In order to achieve the above object, the structure of the present invention is such that the space between the metal structure and the ceramic heat insulating wall is filled with a heat convection preventing material such as ceramic fiber or stainless fiber.

[Function] Since the cavity A between the ceramic insulation wall 51 and the metal structure 52 is filled with heat-resistant metal fibers such as stainless steel, ceramic fibers, etc., heat convection in the cavity A is blocked, and the ceramic insulation Heat conduction from the wall 51 to the metal structure 52 is suppressed.

[Examples of the Invention] The present invention will be described based on Examples. FIG. 1 shows the basic thermal insulation structure of the present invention. A heat insulating gasket 55 is sandwiched between the ceramic heat insulating wall 51 exposed to combustion gas and the metal structure 52, and a nut 5 is attached to a bolt 53 passing through these.
4 are tightened and connected, and a cavity A is formed between the ceramic heat insulating wall 51 and the metal structure 52.

According to the present invention, in order to prevent heat conduction from the ceramic heat insulating wall 51 to the metal structure 52 via heat convection in the cavity A, a heat convection prevention material such as ceramic fiber or stainless steel fiber with excellent heat resistance is used. 58 is empty part A
is filled with.

As shown in FIG. 2, the insulating gasket 55 has a closed cross-section ring 56 made of a heat-resistant metal such as stainless steel, or a bag body containing potassium titanate powder with low thermal conductivity, ceramic fiber with excellent heat resistance, and stainless steel. The cylindrical body 56a is filled with a thermal convection prevention material 57 such as fiber, and is connected to both the upper and lower surfaces of the ring 56 by fitting the cylindrical body 56a into the bolt insertion hole and bending the edges of the cylindrical body 56a. In particular, it is preferable to densely fill the potassium titanate powder.
Even if 3 is tightened, the compressive load can be withstood, and the distance between the metal structure 52 and the ceramic heat insulating wall 51 can be maintained.

In the embodiment shown in FIG. 3, a heat reflecting surface is provided on the inner surface of the ceramic heat insulating wall 51 that defines the cavity A. Specifically, ceramic insulation! 51 and metal structure 52
A metal heat reflecting plate 59°598 made of heat-resistant material such as stainless steel or aluminum is superimposed on the inner surface of the plate. Instead of providing the heat reflecting plate 59, a metallized layer may be formed on the inner surface of the ceramic heat insulating wall 51, and this metalized layer may be plated with chrome to form a heat reflecting surface. Metal structure 52
A chrome plating layer can be provided directly on the inner surface of the plate.

As described above, in the present invention, by filling the cavity Ak:i51 with thermal metal fibers or ceramic fibers, heat convection in the cavity A is blocked, so that heat reaches the metal structure 52 from the ceramic heat insulating wall 51. The amount of heat transferred is reduced.

In the heat insulating gasket 55, a ring 56 or a bag with a closed cross section made of a stainless steel plate that serves as a heat reflecting surface contacts the ceramic heat insulating wall 51 and the metal structure 52, and a heat convection prevention material 57 is provided inside the bag. Since it is filled with potassium titanate powder having extremely low thermal conductivity, the amount of heat dissipated from the ceramic heat insulating wall 51 to the metal structure 52 through the bag and the heat convection prevention material 57 can be significantly reduced. .

FIG. 4 is a front sectional view of a specific heat-insulating engine using ceramics. A cylinder head 1 made of ordinary metal is formed with a cylindrical part 1a, into which a cup-shaped helad liner 3 made of ceramic is fitted via a pair of upper and lower positioning rings 9, and a lower surface 1b of the cylinder head 1. A ring 26 and a ring 10.16 surrounding the fuel injection nozzle 5 and the intake/exhaust port 11 are interposed between the fuel injection nozzle 5 and the helad liner 3. The intake/exhaust ports 11 are opened and closed by intake/exhaust valves 7 coated with ceramics. The combustion chamber includes a cup-shaped helad liner 3 made of ceramics and a piston crown part 8 made of ceramics.
A cylinder liner 4 made of ceramic is defined by the headliner 3 in a part separated from the main part of the combustion chamber.
is confronted with.

Actually, in order to avoid stress due to the difference in thermal expansion between the headliner 3 and the cylinder liner 4, a small gap is provided between the two, and the lower end surface of the headliner 3 and the cylinder body 2 are separated. A gasket 22 is interposed between the cylinder head 1 and the upper end surface, and the cylinder head 1 is fastened by screwing a bolt (not shown) into the cylinder body 2. The cylinder liner 4 is fitted into the cylindrical portion 20 of the cylinder body 2.

One piston is constructed by overlapping a piston crown part 8 made of ceramics with a skirt part 6 made of ordinary metal, and tightening a nut 33 onto a bolt 31 inserted from above. A recess 39 is provided on the upper surface of the piston crown portion 8 to promote mixing of fuel and air, and a cylindrical portion 34 is provided at the center of the lower surface, and a stepped portion is provided on the outer peripheral portion of the lower surface. A piston ring 41 is mounted on the outer peripheral surface of the skirt portion 6, and a protrusion 24 provided on the outer peripheral portion of the upper surface is fitted into the stepped portion of the piston crown portion 8 described above. Further, a column 35 is formed at the center of the upper surface of the skirt portion 6, and the piston crown portion 8 is superimposed on this via a gasket 27, so that an empty space is formed between the column 35 and the cylindrical portion 34.

A seal ring 28 is interposed between the overlapping surfaces of the piston crown portion 8 and the skirt portion 6 on the outer circumferential side.

In this way, a cavity C is formed by the pair of upper and lower rings 9 between the inner peripheral surface of the cylindrical portion 1a of the cylinder head 1 and the Herad liner 3, and a ring is formed between the lower surface 1b and the Herad liner 3. A cavity 8 is formed by 10.16.26. Further, a hollow space is defined between the piston crown portion 8 and the skirt portion 6 by a ring 28. These empty spaces B, C,
D acts as a heat insulating layer.

Silicon titanide is used as the ceramic for the headliner 3, PSZ (partially stable zirconia) is used for the cylinder liner 4, and silicon titanide is used for the piston crown 8.

Vacant part B of the cylinder head 1 configured as described above
. Heat dissipation reaching the cylinder head 1 through the piston crown 8 is suppressed, and heat dissipation from the piston crown 8 to the skirt 6 is suppressed.

4. In terms of the cavity B, as in the case of the heat insulating gasket 55 shown in FIG. The bags are stacked one on top of the other to form a bag body, and a heat convection preventing material 58 is filled inside the bag body, which is sandwiched between the headliner 3 and the lower surface 1b of the cylinder head 1. in this case,
A heat insulating gasket 55 as shown in FIG. 2 or a hollow ring with a circular cross section made of a heat-resistant metal such as Inconel is attached to the mounting hole of the fuel injection nozzle 5 and the intake/exhaust port 11, so that the head bolt can be tightened without any load. To support.

As for the cavity C, two inner and outer cylinders made of stainless steel plates are connected to each other at both upper and lower ends, or a positioning ring 9 is interposed between them, and the inside is filled with a heat convection prevention material 58.

Further, the hollow portion of the piston 19 is also filled with a heat convection preventing material 58 . The thermal convection prevention material 58 may be wrapped in an annular bag made of aluminum foil, silver foil, etc. and housed so that the bag is in close contact with the inner surface of the empty space.

[Effects of the Invention] As described above, the present invention provides a metal structure 52 in a heat engine.
A heat convection prevention material 58 is placed in the space between the ceramic insulation wall 51 and the ceramic insulation wall 51.
Because it fills the engine with heat, it can be easily applied to conventional adiabatic engines without any design changes, which greatly reduces heat dissipation from the combustion chamber and improves the thermal efficiency of the heat engine. Ru. If a bag body provided with a heat-reflecting surface is filled with a heat-convection preventing material, the heat-reflecting surface will be brought into close contact with the inner surface of the cavity due to the heat-convection preventing material, and assembly will be simplified.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the basic structure of the thermogravimetric insulation structure according to the present invention, and Fig. 2 is a gasket for forming a cavity between the metal structure and the ceramic insulation wall in the thermal insulation structure. 3 is a sectional view showing a partially modified embodiment of the heat insulating structure, and FIG. 4 is a front sectional view of an adiabatic engine to which the heat insulating structure according to the present invention is applied. A to D: Hole 51: Ceramic heat insulating wall 52: Metal structure 5: Heat insulating gasket 57.58: Heat convection prevention material 59: Heat reflecting plate

Claims (3)

[Claims] (1) A heat insulating structure for a heat engine, etc., characterized in that a space between a metal structure and a ceramic heat insulating wall is filled with a heat convection prevention material such as ceramic fiber or stainless steel fiber. (2) A heat insulating structure for a heat engine or the like according to claim (1), wherein the inner wall of the cavity is provided with a heat reflecting plate made of a heat-resistant metal. (3) An insulating gasket made of a bag body made of a heat-resistant metal plate filled with a heat convection prevention material is installed at the part where the bolt connecting the metal structure and the ceramic insulating wall passes through the cavity. A heat insulating structure for a heat engine or the like according to claim (1).