JPH0622532U - Heat-shielding structure in sub-chamber engine - Google Patents

Abstract

(57) [Abstract] [Object] The present invention provides a heat shield structure for a sub-chamber engine that forms a horizontal annular groove in the swirl flow in the sub-chamber to promote mixing of air and unburned air-fuel mixture. To do. According to the present invention, a sub-chamber member is formed of an upper member 5 and a lower member 4, and a metal gasket 10 having a sealing property and a damping function is disposed at a boundary between the upper member 5 and the lower member 4. The metal gasket 10 is formed in a U-shaped cross-section in which the annular groove 15 opening to the side of the sub chamber 2 is located in order to form an annular flow in the sub chamber 2. The metal gasket 1 so that the outer peripheral surface 26 of the metal gasket 10 contacts the wall surface of the mounting hole 9.
The outer diameter dimension of 0 is formed to a large diameter within the tolerance range with respect to the inner diameter dimension of the mounting hole 9.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat-shielding structure in a sub-chamber engine that shields a sub-chamber formed by a sub-chamber member from a cylinder head.

[0002]

[Prior art]

 Conventionally, as a sub-chamber engine, a sub-chamber member that forms a sub-chamber is fitted into a mounting hole formed in a cylinder head having an intake / exhaust port, and fuel from the fuel injection nozzle is introduced into the sub-chamber to the sub-chamber member. It is disclosed that a fuel injection hole for spraying and a communication hole communicating with the main chamber are formed and a cooling water chamber is provided on the outer periphery of a sub chamber member formed in the cylinder head. Further, the sub-chamber member is a lower member as a hot plug having a communication hole for communicating the sub-chamber with the main chamber, and an upper member having a fuel injection hole for injecting fuel from a fuel injection nozzle into the sub-chamber. What is produced with a member is disclosed.

Japanese Utility Model Laid-Open No. 62-10233 discloses an auxiliary chamber structure for an engine. The sub-chamber structure of the engine is formed by dividing the sub-chamber into upper and lower ceramic members, and the inner circumference is fitted to the upper outer circumference of the upper ceramic member and the lower outer circumference of the lower ceramic member, and the outer circumference is the cylinder head. The first and second retaining rings, which are press-fitted into the inner wall of the recess and partition the heat insulating space, and the first and second retaining rings made of a material having high heat resistance, the lower end outer peripheral portion of the upper ceramic member and the upper outer peripheral portion of the lower ceramic member And a third retaining ring of a low thermal expansion material, the inner periphery of which is fitted to the inner periphery of the cylinder head, and the outer periphery of which contacts the inner wall of the recessed portion of the cylinder head when hot.

Further, Japanese Utility Model Publication No. 55-92031 discloses an auxiliary chamber device for an engine. The sub-chamber device of the engine forms a sub-chamber by facing the cylinder head and the concave portion provided in the mouthpiece, and the cylinder head is made of cast iron and the mouthpiece is made of ceramic, and the shoulder portion of the mouthpiece mounting hole of the cylinder head and the mouthpiece are A spring is interposed between the shoulders.

Further, Japanese Utility Model Laid-Open No. 61-41827 discloses a ceramic auxiliary combustion chamber mounting structure. The mounting structure is such that a ceramic sub-combustion chamber in which a chamber part and a base part are integrated is fitted into a mounting hole provided in a cylinder head through a gasket having a U-shaped cross section to The outer periphery of an annular gasket having a U-shaped cross section that is convex in the axial direction and is provided on the outer periphery is in contact with the inner surface of a heat shield ring that is press-fitted into the cylinder head and has an L-shaped cross section.

Further, Japanese Utility Model Application Laid-Open No. 62-38424 discloses a secondary combustion chamber made of ceramics. In the ceramic auxiliary combustion chamber, an annular gasket is fitted integrally with the shoulder of a ceramic hot plug, and the hot plug is installed in the hot plug mounting hole of the cylinder head, and the annular gasket extends vertically. It has a fitting part.

[0007]

[Problems to be solved by the device]

 However, in the general sub-chamber, the heat flow from the sub-chamber to the cylinder head side is large, the area where the cooling holes are provided becomes hot, and the outer wall surface is cooled by the cooling water flowing out from the cooling holes. As a result, thermal stress increases and cracks and fractures occur.

By the way, regarding the combustion of the sub-combustion chamber of the swirl chamber, air is introduced into the sub-combustion chamber, that is, the sub-chamber through the communication hole of the swirl chamber as the piston rises. The communication hole is eccentric with respect to the center of the sub chamber, forming a strong swirl in the sub chamber. When the piston is near the top dead center TDC, the fuel is injected from the fuel injection nozzle so as to flow in the swirl flow formed above, and the fuel mixes with the air while riding in the swirl flow, and the ignition delay time increases. Ignite after it occurs. The flame after this ignition is rotated by the swirl in the sub chamber and is burned by the propagation of the flame. At this time, since the fuel and air are not completely mixed, the burnt high-temperature gas gathers in the center of the sub-chamber, and the air in the center is heavier than the high-temperature combustion gas, so it is subjected to centrifugal force. Move to the outer circumference. That is, the air on both sides of the swirl chamber (in other words, on the streamline of the air flowing from the communication hole, that is, on both sides of the swirl flow) flows toward the center of the sub-chamber and the outer peripheral portion of the sub-chamber facing the communication hole. Since the combustion gas in the room is hot and has a low specific gravity, it flows to both sides along the inner wall of the sub chamber.

Therefore, an object of the present invention is to solve the above-described problems, and a sub-chamber member is made of an upper member and a lower member made of ceramics, and a metal having an annular groove between both members. By interposing a gasket to improve the heat shield of the sub chamber, lower the temperature of the metal gasket part, and further strengthen the flow in the sub chamber to promote the mixing of air and unburned mixture. Yes, by generating a good air-fuel mixture, the generation of smoke in combustion in the sub-chamber is suppressed, the occurrence of cracks and cracks in the sub-chamber members is reduced, and the durability of the sub-chamber engine is improved. Is to provide a heat shield structure in.

[0010]

[Means for Solving the Problems]

 The present invention is configured as follows to achieve the above object. That is, in this invention, a sub-chamber member that forms a sub-chamber is fitted into a mounting hole formed in a cylinder head, and a fuel injection hole for spraying fuel from a fuel injection nozzle into the sub-chamber is inserted into the sub-chamber member. In a sub-chamber engine in which a communication hole communicating with the main chamber is formed, a heat-shielding air layer is formed between the sub-chamber member and the mounting hole, and the sub-chamber member is approximately parallel to the cylinder axis. It is composed of a ceramic upper member and a lower member which are divided into two, and an annular groove is formed between the upper member and the lower member, the annular groove being open to the side of the sub chamber where an annular flow is formed in the sub chamber. A metal gasket having a U-shaped cross section is arranged, and the outer diameter of the metal gasket is increased within a tolerance range with respect to the inner diameter of the mounting hole so that the outer peripheral surface of the metal gasket contacts the wall surface of the mounting hole. Characterized by being formed to a diameter The present invention relates to a heat shield structure in a room engine.

Further, in the heat shield structure of the sub chamber engine, a heat shield ring made of a low heat conductive material is interposed between the outer peripheral surface of the sub chamber member and the mounting hole of the cylinder head, and The heat shield air layer is formed in a region where the heat shield ring is not located.

[0012]

[Action]

 The present invention is configured as described above and operates as follows. That is, the heat-shielding structure in this sub-chamber engine is composed of a ceramic upper part member and a lower member, which are obtained by dividing the sub-chamber member into two parts, and is opened on the sub-chamber side between the upper member and the lower member. A metal gasket having a U-shaped cross section in which an annular groove is located, and the outer diameter of the metal gasket is set relative to the inner diameter of the mounting hole so that the outer peripheral surface of the metal gasket contacts the wall surface of the mounting hole of the cylinder head. Since it is formed with a large diameter within the tolerance range, the temperature of the metal gasket region is lowered, the strength of the metal gasket is secured, and the swirl flow of the annular flow in the annular groove formed by the metal gasket described above, that is, It is possible to further strengthen the flow of air around and promote the mixing of air and unburned air-fuel mixture in the sub chamber.

Further, a heat shield ring made of a low heat conductive material is interposed between the outer peripheral surface of the sub chamber member and the mounting hole of the cylinder head, and a heat shield air layer is formed in a region where the heat shield ring is not located. Therefore, the heat shield degree of the sub chamber can be improved as a whole.

[0014]

【Example】

 Hereinafter, with reference to the drawings, an embodiment of a heat shield structure in a sub-chamber engine according to the present invention will be described. First, with reference to FIGS. 1, 2, 3 and 4, an embodiment of a heat shield structure in a sub-chamber engine according to the present invention will be described. 1 is a sectional view showing an embodiment of the structure of a cylinder head according to the present invention, FIG. 2 is an explanatory view for explaining the structure of the cylinder head of FIG. 1, and FIG. 3 is a sectional view taken along line AA of FIG. , And FIG. 4 are enlarged cross-sectional views of a region of reference numeral B in FIG.

As shown in FIGS. 1 and 2, this sub-chamber engine is of a swirl chamber type, and includes a cylinder liner 12 and a cylinder block 11 which form a cylinder 13 fitted in a hole of the cylinder block 11. A cylinder head 3, a sub-chamber member fitted with a heat-shielding air layer 8 formed in a mounting hole 9 formed in the cylinder head 3, and a swirl chamber of a diesel engine formed by the sub-chamber member. It has a fuel injection nozzle 17 for injecting fuel into the sub chamber 2 and a glow plug 18 arranged in the sub chamber 2. The sub-chamber member is composed of an upper member 5 and a lower member 4 as a hot plug, which are divided into two parts, in order not to apply thermal stress from the cylinder head 3 to the sub-chamber 2, and are made of ceramics such as silicon nitride. Has been done. The upper member 5 has a fuel injection hole 20 for injecting fuel from the fuel injection nozzle 17 into the sub chamber 2 and an insertion hole 21 for the glow plug 18. Further, the lower member 4 is formed with a communication hole 7 communicating with the main chamber 1 formed on the cylinder 13 side.

The heat shield structure in the sub-chamber engine according to the present invention is that, in particular, the metal gasket 10 having a sealing function and a cushioning action therebetween is interposed between the upper member 5 and the lower member 4. . The metal gasket 10 is made of a metal material such as SUS, has a hollow shape with an inner side cut out, and has a U-shaped cross section having an annular groove 15 opening to the sub chamber 2 side. The metal gasket 10 can form an annular flow in the sub chamber 2 by having the annular groove 15. Further, the outer diameter 26 of the metal gasket 10 is formed to have a large diameter within a tolerance range with respect to the inner diameter of the mounting hole 9 so that the outer peripheral surface 26 contacts the wall surface of the mounting hole 9. Is.

Further, the lower member 4 is positioned with respect to the cylinder head 3 by the circumferential positioning member 24, and is fixed to the cylinder head 3 by the fixing ring 6. The upper member 5 and the lower member 4 are made of high-strength ceramics such as silicon nitride. A water jacket, that is, a cooling water chamber 14, in which cooling water circulates is formed in the cylinder head 3, and is formed between valve seats so that the cooling water passes between the intake and exhaust ports 22 and 23 where the intake and exhaust valves are seated. A cooling hole 16 is formed. A heat shield air layer 8 for reducing the thermal stress of the sub chamber member is formed in a region covering the outer surfaces of the cylinder head 3, the upper member 5, and the lower member 4.

By forming a heat-shielding air layer 8 between the upper member 5 and the lower member 4 and the inner wall surface of the mounting hole 9 of the cylinder head 3 to form the sub-chamber 2 in a heat-shielding structure, the sub-chamber 2 Although the inside becomes hot, the heat shield structure minimizes the heat flow from the sub-chamber 2 to the cylinder head 3 to reduce the temperature difference in the region of the cylinder head portion 19, thereby causing cracks and cracks in the ceramic lower member 4. Can be prevented.

As described above, the heat shield structure in the sub-chamber type engine has the metal gasket 10 arranged on the boundary surface between the upper member 5 and the lower member 4, and the metal gasket 10 has an annular shape that opens toward the sub chamber 2 side. By forming the groove 15, the annular groove 15 forms a horizontal sneak path that directly intersects the swirl flow, and the outer peripheral portion facing the communication hole 7 is guided by the annular groove 15 to sneak into the swirl flow. The swirl flow from both outer circumferences toward the center is further strengthened, and the air is actively introduced into the center of the sub-chamber 2 to promote the mixing of the air and the unburned mixture in the sub-chamber 2. As a result, the occurrence of smoke can be suppressed.

Further, by forming the sub chamber member by the upper member 5 and the lower member 4 and disposing the metal gasket 10 at the boundary surface between the two, the metal gasket 10 fulfills the function of damping ring and the dimensional variation. Therefore, the lower surface of the cylinder head 3 on the main chamber 1 side and the lower surface of the lower member 4 of the sub chamber member can be set on the same plane. Further, the metal gasket 10 can perform the sealing of the boundary surface between the upper member 5 and the lower member 4, and the heat shield formed between the upper member 5 and the lower member 4 and the mounting hole 9 of the cylinder head 3. The air layer 8 can be sealed, gas can be prevented from flowing out to the heat shield air layer 8, and therefore, the metal gasket 10 can reduce a waste volume.

Further, the metal gasket 10 is formed such that the outer diameter dimension of the metal gasket 10 has a large diameter within a tolerance range with respect to the inner diameter dimension of the mounting hole 9, so that the outer peripheral surface 26 thereof is a wall surface of the mounting hole 9. Therefore, the contact portion of the metal gasket 10 with the wall surface of the outer peripheral surface is a portion that receives a compressive stress, but since the portion has a relatively low temperature, the strength of the portion can be secured. Moreover, even if the lower member, that is, the hot plug is formed thin, the annular groove 15 of the metal gasket 10 can surely secure the space.

Next, another embodiment of the heat shield structure in the sub-chamber engine according to the present invention will be described with reference to FIGS. 5 and 6. This embodiment has the same structure as that of the above embodiment except that a heat shield ring is provided between the cylinder head 3 and the sub chamber member. The same reference numerals are given to the parts, and duplicate explanations are omitted.

In this embodiment, in particular, between the outer peripheral surfaces 28 of the upper member 5 and the lower member 4 and the mounting hole 9 of the cylinder head 3 which form the sub chamber member, low thermal conductivity made of ceramics such as zirconia is provided. That is, the heat shield ring 27 made of a material is interposed, and the heat shield air layer 8 is formed in a region where the heat shield ring 27 is not located. Further, in the metal gasket 10, the outer diameter dimension of the metal gasket 10 is within a tolerance range with respect to the inner diameter dimension of the heat shield ring 27 so that the outer peripheral surface 26 contacts the inner peripheral surface 29 of the heat shield ring 27. That is, it is formed to have a large diameter. Therefore, the outer peripheral surface 26 of the metal gasket 10 comes into contact with the inner peripheral surface 29 of the heat shield ring 27 in a contacting state. Further, the gaps 30 and 31 between the upper member 5 and the outer peripheral surfaces of the lower member 4 are formed to be smaller than the gaps of the heat-shielding air layer 8 formed at other boundary portions for positioning. However, by interposing the heat shield ring 27 in that portion, the heat shield degree can be improved.

Further, in this embodiment, the sub-chamber member can be positioned by the metal gasket 10, and the lower member 4 and the lower member 4 can be provided with a contact surface having a very narrow width with respect to the wall surface of the mounting hole 9 of the cylinder head 3. Since the upper member 5 can be positioned with respect to the cylinder head 3, it is possible to restrict the heat flow between the sub chamber member and the cylinder head 3 and block the heat flow from the sub chamber 2 to the cylinder head 3. it can. In addition, in this embodiment, in order to further improve the heat shield, the portion of the sub chamber 2 where the upper member 5 and the lower member 4 are in contact with the inner wall surface of the mounting hole 9 of the cylinder head 3 is shielded by the low heat conductive material. That is, the heat ring 27 is incorporated.

Therefore, the upper member 5 and the lower member 4 have a heat shield degree between the inner wall surface of the mounting hole 9 of the cylinder head 3 and the heat shield air layer 8 so that the cylinder head 3 is protected from the sub chamber 2. In the region where the heat shield ring 27 is arranged, the heat shield ring 27 is arranged in a portion where the sub chamber member and the inner wall surface of the mounting hole 9 of the cylinder head 3 are in contact with each other. Therefore, the heat flow from the sub chamber member to the cylinder head 3 can be shielded. Further, in the annular passage formed by the annular groove 15 of the metal ring 10, a swirl can be formed so as to wrap around as in the above-described embodiment, air can be taken into the central portion of the sub chamber 2, and the sub chamber 2 You can further strengthen your swirl.

[0026]

[Effect of device]

 The heat shield structure in the subchamber engine according to the present invention is configured as described above and has the following effects. The heat shield structure in this sub-chamber engine is composed of a ceramic upper member and a lower member, which are obtained by dividing the sub-chamber member into two parts, and is opened between the upper member and the lower member on the sub-chamber side. A U-shaped metal gasket having a U-shaped cross section in which an annular groove is located, and the outer diameter of the metal gasket matches the dimension of the mounting hole so that the outer peripheral surface of the metal gasket contacts the wall surface of the mounting hole of the cylinder head. Since it is formed with a large diameter within the tolerance range, the temperature of the area of the metal gasket is lowered, the strength of the metal gasket is secured, and the swirl or air flow of the annular flow in the annular groove formed by the metal gasket is achieved. It is possible to further strengthen the flow around the air and promote the mixing of the air and the unburned air-fuel mixture in the sub chamber.

Further, a heat shield ring made of a low heat conductive material is interposed between the outer peripheral surface of the sub chamber member and the mounting hole of the cylinder head, and a heat shield air layer is formed in a region where the heat shield ring is not located. Therefore, the heat shield degree of the sub chamber can be improved as a whole.

Further, since the heat shield degree of the sub chamber can be improved by the heat shield air layer, for example, the portion facing the cooling hole of the cylinder head is not overcooled and the cooling hole is not cooled. The temperature difference in the outflow region of the cooling water can be reduced, the thermal stress can be reduced, the damage of the sub chamber member can be avoided, and the durability can be greatly improved to enable long-term use.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a heat shield structure in a sub-chamber engine according to the present invention.

FIG. 2 is an explanatory diagram for explaining the structure of the cylinder head of FIG.

3 is a cross-sectional view showing a positioning member taken along the line AA in FIG.

FIG. 4 is an enlarged cross-sectional view of a region of reference B in FIG.

FIG. 5 is a sectional view showing another embodiment of the heat shield structure in the sub-chamber engine according to the present invention.

FIG. 6 is an enlarged cross-sectional view of a region of reference B in FIG.

[Explanation of symbols]

 1 Main Chamber 2 Sub Chamber 3 Cylinder Head 4 Lower Member 5 Upper Member 7 Communication Hole 8 Heat Shielding Air Layer 9 Mounting Hole 10 Metal Gasket 13 Cylinder 15 Annular Groove 17 Fuel Injection Nozzle 24 Positioning Member 26 Outer Surface 27 Heat Shield Ring 28 Lower Outer peripheral surface of member 29 Inner peripheral surface of heat shield ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Tsubonuma 8 Tsutana, Fujisawa City, Kanagawa Prefecture Isuzu Ceramics Laboratory Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A fuel injection hole and a main chamber for fitting a sub-chamber member forming a sub-chamber into a mounting hole formed in a cylinder head, and for spraying fuel from a fuel injection nozzle into the sub-chamber to the sub-chamber member. In a sub-chamber engine in which a communication hole communicating with the sub-chamber is formed, a heat-shielding air layer is formed between the sub-chamber member and the mounting hole, and the sub-chamber member is divided into two substantially parallel to the cylinder axis. A metal having a U-shaped cross section, which is composed of an upper member and a lower member made of ceramics, and in which an annular groove opening toward the sub chamber for forming an annular flow in the sub chamber is located between the upper member and the lower member. A gasket is arranged, and the outer diameter of the metal gasket is formed to have a large diameter within a tolerance range with respect to the inner diameter of the mounting hole so that the outer peripheral surface of the metal gasket contacts the wall surface of the mounting hole. Sub-chamber engine Heat shield structure. 2. A heat shield ring made of a low heat conductive material is interposed between the outer peripheral surface of the sub chamber member and the mounting hole of the cylinder head, and the heat shield ring is provided in an area where the heat shield ring is not located. The heat shield structure in the sub-chamber engine according to claim 1, wherein an air layer is formed.