JPH0630435U - Heat-shielding structure of the auxiliary combustion chamber - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention is to make the upper member and the intermediate member of a low thermal conductive material to improve the heat shield property, and the lower member of a heat-resistant and high-strength ceramic to form a sub chamber wall. Provided is a heat-shielding structure for a sub-combustion chamber which prevents fuel from adhering to it. In this heat-shielding structure for the sub-combustion chamber, the sub-chamber member forming the sub-chamber 2 is composed of an upper member 6 having a fuel injection hole 14,
It is made of a lower member 4 having a communication hole 8 for communicating the sub chamber 2 and the main chamber 1 and an intermediate member 5 arranged between the upper member 6 and the lower member 4. The lower member 4 is made of heat-resistant and high-strength silicon nitride, and the upper member 6 and the intermediate member 5 are made of a low thermal conductive material containing Si—Ti—Al—O—N as a main component. A coating layer 7 made of polycarbosilane is disposed on the surfaces of the upper member 6 and the intermediate member 5 and the boundary surfaces between the members 4, 5, 6.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat shield structure for a sub-combustion chamber in a sub-chamber engine having a plurality of sub-chamber members forming a sub-chamber.

[0002]

[Prior art]

 Conventionally, a structure of a heat shield sub-combustion chamber in a sub-chamber engine shown in FIG. 2 has been disclosed. FIG. 2 is a cross-sectional view showing an example of the structure of a heat shield sub-combustion chamber in a conventional sub-chamber engine. As shown in the figure, in this sub-chamber engine, a cylinder block constituting a cylinder is fitted with a cylinder head 23 with a gasket interposed, and a heat shield air layer 30 is formed in a hole 28 formed in the cylinder head 23. The fitted sub-chamber member forms a sub-chamber 34 which is a swirl chamber of the diesel engine. The sub-chamber member is composed of an upper sub-chamber member 25 and a lower sub-chamber member 24 as a hot plug, which are divided into two in order not to apply thermal stress from the cylinder head 23 to the sub-chamber 34. The upper sub chamber member 25 is formed with a fuel injection hole 31 for injecting fuel from the fuel injection nozzle into the sub chamber 34 and an insertion hole 32 such as a heating plug. Further, the lower sub chamber member 24 is formed with a communication hole 27 communicating with the main chamber 33 formed on the cylinder side.

Further, between the upper sub chamber member 25 and the lower sub chamber member 24, a damping ring 29 having a sealing action and a shock absorbing action therebetween is interposed. The damping ring 29 can be manufactured in a hollow shape or a shape in which the inside of the hollow is filled with SUS or the like. The lower sub chamber member 24 is fixed to the cylinder head 23 by a fixing ring 26. The upper sub-chamber member 25 and the lower sub-chamber member 24 are made of high-strength ceramics such as silicon nitride.

Japanese Utility Model Laid-Open No. 60-137119 discloses a diesel engine sub chamber structure. The sub-chamber structure of the diesel engine has a structure in which a nozzle side ceramic piece having a nozzle opening in the main combustion chamber and an inner wall side ceramic piece having a larger coefficient of thermal expansion and superposed on the ceramic piece are fitted to a metal insert ring. And the metal insert ring is formed by a nozzle-side insert ring that is shrink-fitted to the nozzle-side ceramic piece and an inner-wall-side insert ring that is fitted to the inner-wall-side ceramic piece, and the nozzle-side insert ring and the inner wall. The side engaging ring is provided with a ring engaging portion that is slidably coupled in the radial direction.

Further, JP-A-57-68515 discloses a swirl chamber mouthpiece of a swirl chamber type diesel engine. The swirl chamber mouthpiece of the swirl chamber type diesel engine has a nozzle portion communicating with the main combustion chamber of the swirl chamber mouth member made of heat-resistant and thermal shock-resistant ceramics, and at least one of the inner wall of the swirl chamber is in contact with the nozzle hole portion. The parts that make up the parts are made of adiabatic ceramics. It is disclosed that high strength ceramics include silicon nitride and silicon carbide, and low thermal conductivity ceramics include zirconia and crystallized glass.

[0006]

[Problems to be solved by the device]

 However, since the heat-shielding structure of the sub-combustion chamber in the sub-chamber engine upper sub-chamber member 25 and the lower sub-chamber member 24 shown in FIG. 2 is not a material having low thermal conductivity and high strength, the upper sub-chamber member 25 and the lower sub-chamber member 24, the damping ring 10 is interposed between the outer peripheral surfaces of the upper sub-chamber member 25 and the lower sub-chamber member 24 and the wall surface of the mounting hole 28 of the cylinder head 23 in order to improve heat insulation. An adiabatic air layer 30 is formed on the. The upper sub-chamber member 25 and the lower sub-chamber member 24 are made of ceramics such as silicon nitride, and the damping ring 10 is made of metal such as SUS.

Further, in the materials disclosed in the above-mentioned respective publications, the sub-chamber member is made of zirconia or crystalline glass. However, regarding the strength of the sub-chamber member, the pores existing on the surface, and the gap at the boundary surface, Does not have any measures in place.

[0008] Therefore, an object of the present invention is to solve the above-mentioned problems, and a sub-combustion chamber in a sub-chamber engine is composed of an upper member, a lower member, and an intermediate member between the upper member, the lower member, and the lower member. It is made of high-strength, high-strength silicon nitride ceramics, the upper member and the intermediate member are made of low thermal conductivity ceramics, fills the pores existing on the surface of the upper member and the intermediate member, and A coating layer of polycarbosilane that fills the gap between the boundary surfaces is placed to increase the heat insulation of the sub chamber, strengthen the surface of the sub chamber member, prevent combustion gas leakage, and prevent heat energy from radiating to the cylinder head. In addition, the heat insulation structure of the auxiliary combustion chamber is improved by improving the heat insulation of the auxiliary chamber and improving the heat resistance of the communication hole portion that communicates the main chamber with the auxiliary chamber.

[0009]

[Means for Solving the Problems]

 The present invention is configured as follows to achieve the above object. That is, the invention is a sub-chamber engine having a plurality of sub-chamber members forming a sub-chamber arranged in a mounting hole formed in a cylinder head, and the sub-chamber member communicates the sub-chamber with the main chamber. A lower member made of heat-resistant and high-strength silicon nitride for forming a communication hole, and a low thermal conductive material containing Si-Ti-Al-O-N as a main component for forming a fuel injection hole. An upper member, an intermediate member which is disposed between the upper member and the lower member, and made of a low thermal conductive material containing Si-Ti-Al-O-N as a main component, and the upper member and the intermediate member Of the sub-combustion chamber, which is composed of a coating layer composed of polycarbosilane disposed on the surface of the upper member, the boundary surface between the upper member and the intermediate member, and the boundary surface between the intermediate member and the lower member. Structure To do.

[0010]

[Action]

 The heat shield structure of the sub-combustion chamber according to the present invention is configured as described above and operates as follows. That is, in this heat-shielding structure of the sub-combustion chamber, the upper member and the intermediate member are made of a low heat conductive material containing Si-Ti-Al-O-N as a main component, and the lower member is provided with a communication hole that becomes high temperature. Is made of heat-resistant and high-strength silicon nitride, and polycarbosilane is formed on the surface of the upper member and the intermediate member, the boundary surface between both members, and the boundary interface between the intermediate member and the lower member. Since the coating layer of No. 3 is provided, the polycarbosilane of the coating layer can be well bonded to silicon nitride and Si-Ti-Al-O-N, and the pores existing on the surfaces of the upper member and the intermediate member are It can be filled with the coating layer to form a strong smooth surface, and the gap between the boundary surfaces between the members can be filled with the coating layer to firmly adhere to each other to eliminate the gap. Further, since the upper member and the intermediate member are made of a low heat conductive material and the coating layer is provided on the surface thereof, the heat capacity of the entire sub-chamber can be made small and the followability to the gas temperature can be improved. Can improve combustion.

[0011]

【Example】

 An embodiment of a heat shield structure for a secondary combustion chamber according to the present invention will be described below with reference to the drawings. An embodiment of a heat shield structure for a secondary combustion chamber according to the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing an embodiment of a heat shield structure for a secondary combustion chamber according to the present invention.

A sub-chamber engine incorporating this heat-shielding structure for the sub-combustion chamber has a cylinder block 9, a cylinder liner 10 constituting a cylinder 18 fitted in a hole formed in the cylinder block 9, and a gasket on the cylinder block 9. It has a cylinder head 3 fixed via 11 and a sub chamber member forming a sub chamber 2 arranged in a mounting hole 16 formed in the cylinder head 3. The sub-chamber member may be arranged in a state where a heat-shielding air layer 17 is formed in the mounting hole 16 of the cylinder head 3 as shown in the drawing, or, although not shown, the sub-chamber member of the cylinder head 3 is not shown. It may be arranged in contact with the inner wall surface of the mounting hole 16. The main chamber 1 is formed on the cylinder 18 side and is formed by the upper portion of the cylinder liner 10 and the lower surface of the head, or, although not shown, is formed on the top surface of the piston that reciprocates in the cylinder 18. Is also good.

In this heat-shielding structure for the auxiliary combustion chamber, the auxiliary chamber member is made up of three members, that is, the upper member 6, the lower member 4, and the intermediate member 5 arranged between the upper member 6 and the lower member 4. ing. The upper member 6 is formed with a fuel injection hole 14 for installing the fuel injection nozzle 13 and a glow plug hole 15 for installing the glow plug 12. The intermediate member 5 is formed in a tubular shape. Further, the lower member 4 is formed with a connecting hole 8 that connects the main chamber 1 and the sub chamber 2 to each other.

In particular, this heat-shielding structure for the sub-combustion chamber is heat-resistant to the lower member 4 in which the sub-chamber member has a communication hole 8 that communicates the sub-chamber 2 with the main chamber 1 formed on the cylinder 18 side. The upper member 6 made of high-strength silicon nitride and having the fuel injection hole 14 in which the fuel injection nozzle 13 is installed, and the intermediate member 5 arranged between the upper member 6 and the lower member 4 are made of Si- It is made of a low thermal conductive material containing Ti-Al-O-N as a main component. In the structure of the heat-shielding sub-combustion chamber, the surface of the upper member 6 and the intermediate member 5, the interface of the upper member 6 and the intermediate member 5, and the interface of the intermediate member 5 and the lower member 4 are A coating layer 7 made of polycarbosilane is arranged.

The heat shield structure of the auxiliary combustion chamber has the above-mentioned configuration and can be manufactured as follows. First, the lower member 4 is made of silicon nitride, and the upper member 6 and the intermediate member 5 are made of low thermal conductive materials containing Si—Ti—Al—O—N as a main component. Next, the boundary surface or the bonding surface 19 of the lower member 4 bonded to the intermediate member 5, the boundary surface or the bonding surfaces 20 and 21 of the intermediate member 5 bonded to the lower member 4 and the upper member 6, and the intermediate member 5 are bonded. A coating layer 7 is formed by coating polycarbosilane on the boundary surface of the upper member 6, that is, the bonding surface 22. The lower member 4 and the intermediate member 5 are brought into contact and close contact with each other, and the intermediate member 5 and the upper member 6 are brought into contact and close contact with each other to form a sub chamber member which forms the sub chamber 2 with the three members 4, 5, and 6. Further, the polycarbosilane layer is converted into a dense layer by heat-treating the sub chamber member.

At this time, since polycarbosilane is well bonded to silicon nitride and Si—Ti—Al—O—N, the lower member 4, the intermediate member 5 and the upper member 6 are firmly bonded to each other. To be strengthened. In particular, the pores existing on the surfaces of the intermediate member 5 and the upper member 6 are filled with the dense layer of polycarbosilane to form a smooth surface. Therefore, the fuel injected from the fuel injection nozzle 13 into the sub chamber 2 does not permeate into the pores of the intermediate member 5 and the upper member 6 and does not cause smoke or the like.

In this heat-shielding structure of the sub-combustion chamber, the low thermal conductive material containing Si—Ti—Al—O—N as a main component that constitutes the upper member 6 and the intermediate member 5 has a thermal conductivity of 1 to 4 W / m · K (watt / meter · absolute temperature), and its thermal conductivity is low when the pore volume is large and is high when the pore volume is small. In addition, the silicon nitride that forms the lower member 4 in which the communication hole 8 that connects the main chamber 1 and the sub chamber 2 is formed is a region where the temperature rises due to the passage of the flame in the communication hole 8; Excellent in high temperature strength and durability, ensuring durability.

In this heat-shielding structure of the auxiliary combustion chamber, the polycarbosilane of the coating layer 7 can be well bonded to silicon nitride and Si—Ti—Al—O—N, and the upper member 6 and the intermediate member 5 can be bonded together. The pores existing on the surface are completely filled with the coating layer 7 to form a strong smooth surface. Further, the gaps between the boundary surface between the upper member 6 and the intermediate member 5 and the boundary surface between the intermediate member 5 and the lower member 4 are completely filled with the coating layer 7 and firmly adhered to each other to form the members 4, 5 , 6 can be eliminated.

Since the heat shield structure of the sub combustion chamber is configured as described above, the heat shield of the sub chamber 2 is increased and the surfaces of the upper member 6 and the intermediate member 5 are reinforced with the coating layer 7. , Prevents leakage of combustion gas, prevents heat energy from radiating from the sub chamber 2 to the cylinder head 3, improves the heat insulation of the sub chamber 2, and connects the main chamber 1 and the sub chamber 2 with each other. It is possible to improve the heat resistance and the strength of the 8 parts of the communication hole, and to improve the durability of the heat shield auxiliary combustion chamber.

[0020]

[Effect of device]

 The heat shield structure for the auxiliary combustion chamber according to the present invention is configured as described above and has the following effects. This sub-combustion chamber has a heat shield structure in which the upper member and the intermediate member are made of a low heat conductive material containing Si-Ti-Al-O-N as a main component, and the lower member having a communication hole at a high temperature is heat-resistant. A high-strength silicon nitride, and a coating layer of polycarbosilane on the surface of the upper member and the intermediate member, the boundary surface between the two members, and the boundary surface between the intermediate member and the lower member. Therefore, the polycarbosilane of the coating layer can satisfactorily bond to silicon nitride and Si-Ti-Al-O-N, and the pores existing on the surfaces of the upper member and the intermediate member are It is completely filled with a coating layer to form a strong smooth surface, and the gaps at the boundary surfaces between the members are completely filled with the coating layer and firmly adhered to each other to form a gap between the members. It can be lost.

Therefore, the combustion gas and flame in the sub-chamber do not leak from the sub-chamber to the cylinder head side, and the fuel injected from the fuel injection nozzle into the sub-chamber permeates and adheres to the pores on the wall of the sub-chamber. Therefore, a good mixture of fuel and air can be generated without causing smoke and the like, and good ignition and combustion can be performed. Further, the boundary surface in the sub chamber can be completely sealed, the heat shield degree of the entire sub chamber can be improved, and the thermal efficiency can be improved.

Further, the sub-chamber member is composed of three parts, that is, the upper member having the fuel injection hole, the tubular intermediate member, and the lower member having the communication hole. Therefore, each member has a simple shape. Therefore, the cost of press molding can be greatly reduced, and the communication hole, fuel injection hole, glow plug hole, etc. can be accurately formed. Further, even if the auxiliary chamber member is used for a long period of time, the auxiliary chamber member is not damaged, and the durability of the auxiliary combustion chamber can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a heat shield structure for a secondary combustion chamber according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a conventional heat shield structure for a secondary combustion chamber.

[Explanation of symbols]

 1 Main chamber 2 Sub chamber 3 Cylinder head 4 Lower member 5 Intermediate member 6 Upper member 7 Coating layer 8 Communication hole 14 Fuel injection hole 16 Mounting hole 19, 20, 21, 22 Joint surface (boundary surface)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takato Kanno, Inventor, Takatoshi Kanno 8 Isabi, Fujisawa, Kanagawa

Claims (1)

[Scope of utility model registration request] 1. A sub-chamber engine having a plurality of sub-chamber members forming a sub-chamber arranged in a mounting hole formed in a cylinder head, wherein the sub-chamber member connects the sub-chamber with the main chamber. A lower member which is made of silicon nitride having a hole, which is heat resistant and has a high strength, an upper member which is made of a low heat conductive material which has a fuel injection hole and has Si-Ti-Al-O-N as a main component, An intermediate member that is arranged between the upper member and the lower member and is made of a low thermal conductive material containing Si-Ti-Al-O-N as a main component, and the surfaces of the upper member and the intermediate member, A heat shield structure for a sub-combustion chamber, comprising a coating layer made of polycarbosilane disposed on a boundary surface between the upper member and the intermediate member and a boundary surface between the intermediate member and the lower member.