JPH08144845A - Structure of thermal insulation engine - Google Patents

Abstract

PURPOSE: To heighten the thermal insulating rate of a combustion chamber in the structure of a thermal insulation engine. CONSTITUTION: A thermal insulation engine is formed by arranging a subchamber wall body 9 and a head liner 10 with a thermal insulation body 6 inserted between cavities 16, 17 formed in a cylinder head 4. The thermal insulation body 6 is composed of heat resisting metal bodies 7, 8 where the insides are formed into a vacuum layer 12 and a radiant heat shield-coated layer is formed on its inner face; and a metal wire 11 arranged inside the vacuum layer 12 to keep the shape of the heat resisting metal bodies 7, 8. A thermal insulation air layer 20 is formed in the cavities 16, 17 of the cylinder head 4 for arranging the thermal insulation body 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a heat shield engine in which a heat shield is interposed in a cavity of a cylinder head to form a combustion chamber.

[0002]

2. Description of the Related Art Conventionally, for example, an adiabatic engine is disclosed in JP-A-59-122765. The heat insulation engine has a ceramic liner head having an upper portion of a cylinder liner fitted inside the cylinder head. The liner head is formed by integrally forming a cylinder head inner wall portion and a cylinder liner upper portion, and the cylinder liner upper portion of the liner head is formed as a member different from a lower cylinder liner. Also,
To attach the liner head to the cylinder head, the liner head is fitted into the cavity of the cylinder head through a positioning gasket by press fitting, shrink fitting or the like in a state where an air layer is formed. The adiabatic engine has reduced heat escape due to the presence of the air layer.

Further, the present applicant has previously developed a heat shield gasket and a combustion chamber structure in which the heat shield gasket is interposed, and filed as Japanese Patent Application No. 5-96533. In order to seal the gap between the first member and the second member, the heat shield gasket is made of ceramics as the gasket disposed between the first member and the second member, and has a structure in which the heat transfer coefficient of the gasket is made small. The heat flow from the low temperature part to the low temperature part is reduced, and the heat insulation of the high temperature part such as the combustion chamber is improved. Further, a combustion chamber structure using the heat shield gasket has a combustion chamber wall body made of ceramics arranged in a hole formed in the cylinder head, and the combustion chamber wall body is provided in the hole part of the cylinder head. The heat shield gasket is disposed with the heat shield gasket interposed, the heat shield gasket is composed of at least two gasket members, and the gasket members are laminated so as to face each other,
A large number of concave portions and convex portions are formed on each facing surface of each gasket member to reduce the facing contact area of each gasket member and improve the heat shield.

[0004]

However, in the heat shield engine, the combustion chamber has a high temperature atmosphere, but if the heat shield structure between the wall of the combustion chamber and the cylinder head is not sufficient, the heat energy of the combustion chamber will be high. The heat is transferred from the wall of the combustion chamber to the cylinder head, and the heat is dissipated to the outside through the cylinder head, which causes a decrease in thermal efficiency. Therefore, the combustion chamber wall is made of a heat-resistant material such as ceramics, and a heat-shielding air layer having a small heat conductivity and a small heat transfer coefficient is formed outside the combustion chamber wall between the cylinder head and Although a heat shield structure in which a heat shield gasket with a low rate is arranged is conceivable, even if a ceramic such as zirconia-based ceramics is selected as a material for forming the heat shield gasket and the gasket is made of the ceramic, the heat conduction of the ceramic There is a limit to the rate reduction.

As described above, in a heat shield engine having a heat shield air layer, when the density of air in the heat shield air layer increases or the flow velocity increases due to convection of air, the heat transfer coefficient of air increases. , The heat shield effect becomes smaller. Further, when the gasket in the heat shield engine is formed of a heat insulating material or a ceramic of a heat resistant material, there is a limit to the decrease in thermal conductivity, and it is extremely difficult to obtain sufficient heat insulating characteristics, and sufficient heat insulating characteristics are required. In order to obtain it, there is a problem that the heat shield gasket becomes considerably thick. That is, the part of the engine facing the combustion chamber is made of ceramics such as silicon nitride having excellent heat resistance, heat insulation and heat shock resistance, and can withstand high temperature combustion gas. There is a problem of how to prevent the heat dissipation from the heat.

An object of the present invention is to solve the above-mentioned problems. A combustion chamber wall body made of ceramics that constitutes a combustion chamber is arranged in a cavity formed in a cylinder head with a heat shield interposed therebetween. The heat shield is configured to have a vacuum layer, the heat transfer of the heat transfer section is blocked by the vacuum layer, the heat flow from the high temperature section to the low temperature section is reduced, and the mirror surface plating layer on the inner surface of the heat shield is formed. Thus, it is to provide a structure of a heat shield engine which shields radiant heat, reduces the heat transfer rate from the high temperature portion of the combustion chamber to the cylinder head, and significantly improves the heat shield degree of the combustion chamber.

[0007]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention relates to a structure of a heat shield engine having a cylinder head fixed to a cylinder block forming a cylinder in which a piston reciprocates, and a combustion chamber arranged in a cavity formed in the cylinder head, wherein the combustion chamber is the cylinder. A heat shield is disposed inside the cavity of the head, the heat shield having a vacuum layer formed inside and a radiant heat shield coating layer on the inner surface of the heat shield and the shape of the heat shield. And a structure of a wire structure disposed in the vacuum layer.

In the structure of this heat shield engine,
The heat shield is arranged to form a heat shield air layer in the cavity of the cylinder head. The combustion chamber is composed of a head liner made of ceramics or metal, which is composed of a lower surface of the head and an upper portion of the liner integrally formed with the lower surface of the head.

Alternatively, the combustion chamber wall body is a head liner made of ceramics composed of a head lower surface portion and a liner upper portion integrally formed with the head lower surface portion, and a ceramic or metal constituting a sub chamber fixed to the head liner. And a sub-chamber wall body, and a communication hole that connects the combustion chamber formed by the headliner and the sub-chamber is formed in the combustion chamber wall body.

In the structure of this heat shield engine, the refractory metal body is made of Ni--Cr type iron alloy or SUS. The wire structure is made of a metal wire having a circular cross section, and the contact surface between the metal wire and the refractory metal body is reduced as much as possible. Further, the radiant heat shielding coating layer is formed by Ag or Cr mirror plating having an excellent emissivity. In addition, the plate thickness of the joint portion connecting the inner and outer plates of the heat-resistant metal body forming the heat shield is smaller in the larger diameter portion than in the smaller diameter portion. . Further, the piston includes a piston head and a piston skirt fixed to the piston head, and the heat shield is interposed between the piston head and the piston skirt.

[0011]

The structure of the heat shield engine according to the present invention is constructed as described above and operates as follows. That is, the structure of this heat shield engine is such that a combustion chamber forming a combustion chamber is arranged in the cavity of the cylinder head with a heat shield interposed, and the heat shield is formed of a vacuum layer inside the heat resistant metal. The heat shield has a vacuum layer as an intermediate layer because it is composed of a body and a wire structure arranged in the vacuum layer, and the inner surface of the refractory metal body is coated with Ag or Cr to shield the radiant heat. Since the layer is plated, the radiant heat from the high temperature side in the combustion chamber is blocked, the amount of heat transfer is reduced, and the heat shield degree of the combustion chamber can be greatly increased.

The structure of this heat shield engine cannot reduce the thermal conductivity of the material constituting the heat resistant metal body and the wire structure itself, but the vacuum layer is formed inside the heat resistant metal body, The contact area between the metal body and the wire structure is extremely small due to the line contact between the circle and the surface, the heat transfer rate from the combustion chamber to the outside is significantly reduced, and the cylinder from the high temperature side combustion chamber to the low temperature side is reduced. The heat flow to the head is reduced and the heat flow velocity is greatly reduced. Also, the wire structure may firmly maintain the vacuum layer of the refractory metal body.
Since the heat-resistant metal body is arranged by forming a heat-shielding air layer in the cavity of the cylinder head, the heat-resistant metal body has a surface on the inside and the outside, and is configured in two layers,
Although the inner side is the heat receiving surface, since there is an air layer on the outer side, heat is not radiated to the outer side, and the core portion of the wall body is a portion where heat moves.

Regarding the heat transfer of the laminated body such as the gasket, the heat flow from the high temperature side wall body to the low temperature side wall body is steadily governed by the heat transmission rate K. The thermal conductivity of the material of the high temperature side wall is λ ₁ , the thermal conductivity of the material of the low temperature side wall is λ ₂ , the heat transfer coefficient of the high temperature gas is α _g , the heat transfer coefficient of the low temperature side gas is α _a , and the intermediate Where the thermal conductivity of the portion is λ _cc , the wall thickness of the high temperature side wall is δ ₁ , the wall thickness of the low temperature side wall is δ ₂ , and the thickness of the intermediate portion between the high temperature side wall and the low temperature side wall is δ _cc. , The following formula is established. 1 / K = (δ _cc / λ _cc ) + (1 / α _g ) + (δ ₁ /
λ ₁ ) + (δ ₂ / λ ₂ ) + (1 / α _a ) However, the unit of heat transfer rate is kcal / m ² · h · ° C, the unit of thermal conductivity is kcal / m · h · ° C, and The unit of heat transfer coefficient is kcal / m ² · h · ° C. Here, the thermal conductivity λ _cc of the intermediate portion is the thermal conductivity of the intermediate layer connecting the high temperature side wall body and the low temperature side wall body, and the convection and conduction of air existing between the high temperature side wall body and the low temperature side wall body. And the total thermal conductivity of radiation and the level of the amount of heat transfer by air is measured to be very large.

That is, the amount of heat transfer by air is quantitatively calculated assuming that air is enclosed between the flat walls, and the result is as follows. Here, the temperature difference between the high temperature side wall body and the low temperature side wall body is ΔT, the heat transfer area of the wall body is A, the heat transfer area of the outer periphery of the wall body is a, and the heat transfer area between the high temperature side wall body and the low temperature side wall body is If the length is δ, the heat transfer coefficient from the wall to the air is α ₁ , the heat transfer coefficient from the wall to the outer air is α ₂ and the heat conductivity of the wall is λ, then the surface of the high temperature side wall is The heat transfer amount Q ₁ and the heat transfer amount Q ₂ from the outer peripheral surface are as follows. Q ₁ = K ・ A ・ ΔT = A ・ ΔT / [(1 / α ₁ ) + (1
/ Α ₂ ) + (δ ₁ / λ ₁ )] Q ₂ = (λ ₁ / δ) · a · ΔT As can be seen from the above equation, in such a structure, heat transfer from the surface causes Large heat transfer (Q ₂ ＞
Q ₁ ). Therefore, in order to satisfy Q ₂ <Q ₁ , α ₂ = α
When _{1, a · (λ 1 /} δ) <A / _{[(2 / α 1) + (} δ 1 /
The relational expression λ ₁ )] must hold. Therefore, the calculation is made as follows when the iron material is used as the gasket material and air is present in the middle and when the middle is evacuated.
At this time, λ ₁ = 30 W / m · K, α ₁ = 116 W / m ²
• K (air) and δ ₁ = 0.001 m. Also,
Since α ₁ has a small value in vacuum, Q ₁ has an extremely small value. In the case of air, a (λ ₁ / δ) <A / [(2 / α ₁ )
+ (Δ ₁ / λ ₁ )] a (30 / δ) <A / [(2/116) + (0.001
/ 30)] 0.518 (a / A) <δ. In the case of vacuum, if the value of Q ₁ is set to about 1/50 of that of air, a (λ ₁ / δ) <A / 50 × [(2 / α ₁ ) + (δ ₁ /
λ ₁ )] a (30 / δ) <A / (50 × 0.017) 25.5 (a / A) <δ.

From the above matters, the heat conduction in vacuum is overwhelmingly smaller than the heat conduction in air, and the heat conduction from the side wall is dominant in the heat conduction in vacuum. Therefore, maintaining a vacuum between the walls rather than enclosing air can significantly reduce the heat transmission rate. Assuming that the heat shield coefficient β, the heat radiation amount to the cooling water are Q _W , and the heat radiation amount Q _E of the heat shield engine is about the heat shield engine, the following formula is established. β = (Q _W −Q _E ) / Q _W × 100 When the air layer is configured as a heat shield layer, maximum β = 50 to 7
While it is 0%, when the vacuum layer is configured as a heat shield layer, a maximum β = 80% or more can be expected.

[0016]

Embodiments of the structure of a heat shield engine according to the present invention will be described below with reference to the drawings. Regarding the structure of this heat shield engine, there are drawings that do not show the intake / exhaust ports, the intake / exhaust valves arranged in the intake / exhaust ports, the glow plugs for assisting the starting of the engine, the fuel injection nozzles, etc. 2-stroke engine, 4
It is provided corresponding to various engines such as a stroke engine, a gasoline engine, a diesel engine, an alcohol engine, a gas engine, etc., and a description thereof will be omitted.

An embodiment of the structure of a heat shield engine according to the present invention will be described with reference to FIGS. 1 and 2. 1 is a sectional view showing an embodiment of the structure of the heat shield engine according to the present invention, and FIG. 2 is an enlarged sectional view of a portion E of the heat shield in FIG.

The structure of this heat shield engine includes a cylinder head 4 fixed to a cylinder block 25 with a gasket 21 interposed therebetween, cavities 16 and 17 formed in the cylinder head 4, and a cylinder center in the cavity 16 of the cylinder head 4. A sub-chamber wall 9 that constitutes the sub-chamber 2 arranged in
The headliner 10 arranged in the cavity 17 is fitted into the hole 24 of the cylinder block 25, and the cylinder 19
It has a cylinder liner 18 constituting the above, a piston 3 reciprocating in a cylinder 19 formed in the cylinder liner 18, and a main chamber 1 formed by a head liner 10. The sub-chamber wall 9 has a lower portion fitted and fixed to a fitting hole 28 formed in the center of the cylinder of the headliner 10. The sub chamber wall 9 and the head liner 10 are arranged such that the heat shield 6 is interposed in the cavities 16 and 17 of the cylinder head 4 and the heat shield air layer 20 is formed.
Further, the piston 3 is composed of a piston head 31 made of ceramics and a piston skirt 32 in which a heat shield air layer 23 is formed on the piston head 31 and fixed by a metal flow of a coupling ring 26 or the like. Further, the sub chamber wall body 9 is provided with a fuel injection nozzle 15 having multiple injection holes 27 for injecting fuel into the sub chamber 2.

In the structure of this heat shield engine, the combustion chamber wall body is composed of the headliner 10 and the sub chamber wall body 9 fixed to the fitting hole 28 formed in the headliner 10.
A communication hole 5 that connects the main chamber 1 and the sub chamber 2 to each other in the combustion chamber wall.
Are provided in a circumferentially spaced manner. The communication hole 5 is
The sub-chamber 2 is formed to be inclined from the main chamber 1 toward the periphery of the cylinder 19. The head liner 10 has a head lower surface 2
9 and a liner upper portion 30 integrally formed with the head lower surface portion 29 and made of ceramics or heat-resistant metal,
The sub-chamber wall 9 is composed of a sub-chamber wall made of ceramics or heat-resistant metal that constitutes the sub-chamber 2. Since the headliner 10 and the sub-chamber wall 9 are exposed to high temperature gas, they are made of ceramics such as silicon nitride or Ni—Cr heat resistant metal that has high heat resistance and high temperature and high strength.

In the structure of this heat shield engine, in particular, the sub chamber wall 9 of the combustion chamber wall and the head liner 10 are arranged in the cavities 16 and 17 of the cylinder head 4 with the heat shield 6 interposed. It is characterized by being The heat shield 6 is arranged in contact with the outer surface of the sub-chamber wall 9 and the headliner 1
0 is placed on the step portion 22 formed on the liner upper portion 30 and is arranged in contact with the outer surface of the head liner 10. Also,
The heat shield 6 is provided in the cavities 16 and 17 of the cylinder head 4.
A heat-shielding air layer 20 is formed inside and arranged. Furthermore,
A heat shield 6 is interposed as a gasket between the piston head 31 and the piston skirt 32, and the heat shield 6 blocks heat transfer from the piston head 31 to the piston skirt 32. The piston 3 has a heat shield structure.

The heat shield 6 is formed with a vacuum layer 12 inside, and an outer heat-resistant metal body 7 and an inner heat-resistant metal body 7 each having a radiant heat-shielding coating layer 13 on the inner surface thereof.
It is composed of a plurality of metal wires 11 constituting a wire structure arranged in a vacuum layer 12 which retains the shape of a hollow portion composed of eight. The metal wires 11 are arranged in the vacuum layer 12 in contact with the outer refractory metal body 7 and the inner refractory metal body 8 by line contacts 14 respectively in order to make the contact area as small as possible. The heat-resistant metal bodies 7 and 8 are composed of a laminated material of thin plates made of Ni-Cr-based iron alloy or SUS, and
The metal wire 11 is composed of a metal wire having a circular cross section. The radiant heat shielding coating layer 13 is composed of a mirror-plated layer of Ag or Cr having a large thermal emissivity.

Therefore, in the structure of this heat shield engine, the headliner 10 which constitutes the main chamber 1 and the sub chamber wall 9 which constitutes the sub chamber 2 are covered with the heat shield 6, so that the main chamber is covered. The heat shield 1 includes a heat shield 6, a headliner 10 and a piston head 31, and the sub chamber 2 has a high heat shield including a heat shield 6, a heat shield air layer 20 and a sub chamber wall 9. Structured into a structure. Therefore, the high temperature gas generated in the sub chamber 2 and the main chamber 1 is
The heat shield 6 greatly reduces the heat transmission rate, and the headliner 1
0 and the heat radiation from the sub chamber wall 9 to the cylinder head 4 is reduced, and a heat shield rate of 80% or more can be achieved.

Next, another embodiment of the structure of the heat shield engine according to the present invention will be described with reference to FIG. The structure of this heat shield engine is an engine of a type that does not have a sub chamber, and the combustion chamber wall body is a headliner 1 that constitutes the combustion chamber 1M.
It is formed by 0. The head liner 10 is made of ceramics in an integrated structure from the head lower surface portion 29 and the liner upper portion 30. Regarding the structure of this heat shield engine, the heat shield structure is the same as in the above embodiment.
The outer surface of 0 is covered with the heat shield 6, and the same degree of heat shield can be secured. In the figure, reference numeral 33 is an intake / exhaust port, and reference numeral 34
Indicates an intake / exhaust valve.

Next, another embodiment of the structure of the heat shield engine according to the present invention will be described with reference to FIG. The structure of this heat shield engine is an engine of the type in which a central communication hole 36 is provided in the sub-chamber wall body 9 that constitutes the sub-chamber 2. A central protrusion 35 is formed on the top surface of the piston head 31 of the piston 3, and a central communication hole 36 is formed in the lower center of the sub chamber wall 9. In the structure of this heat shield engine, the central projecting portion 35 projects into the central communication hole 36 near the top dead center of the piston, and the central communication hole 36 is almost closed.
Intake air is introduced from the main chamber 1 to the sub chamber 2 through the communication hole 5. Fuel is injected from the fuel injection nozzle 15 into the sub chamber 2 and ignites and burns, and a flame is ejected from the sub chamber 2 through the communication hole 5 to the vicinity of the cylinder 19 of the main chamber 1 to entrain fresh air existing around the cylinder. Then, as the piston descends, the protrusion 35 comes out of the central communication hole 36,
It is ejected from the sub chamber 2 to the center of the main chamber 1 through the central communication hole 36, and burns by using the fresh air existing in the center to increase the air utilization rate to shorten the combustion period and complete the combustion in a short time. And the thermal efficiency can be improved. Regarding the structure of this heat shield engine, the heat shield structure is constructed by covering the outer surfaces of the headliner 10 and the sub-chamber wall body 9 with the heat shield body 6 in the same manner as in the above embodiment, and the same heat shield degree can be secured. .

Next, another embodiment of the structure of the heat shield engine according to the present invention will be described with reference to FIGS. The structure of this heat shield engine is applied to a gas engine that uses natural gas as a fuel. This gas engine is provided with a central communication hole 36 in the sub-chamber wall 9 that constitutes the sub-chamber 2, and a control valve 3 that opens and closes the central communication hole 36 and the communication hole 5.
7 are provided. In this gas engine, the sub-chamber 2 is cut off from the main chamber 1, the gas fuel is supplied from the fuel supply means 41 to the sub-chamber 2 in a state where there is no air in the sub-chamber 2, and the main chamber 1 is supplied with the gas fuel. It highly compresses the intake air in the absence of air to prevent abnormal combustion and ensures high compression.
The control valve 37 is actuated in the vicinity of the top dead center of the piston to open the communication hole 5 and introduce highly compressed air into the sub chamber 2 for ignition and combustion. In the structure of this heat shield engine, the heat shield structure is formed by covering the outer surfaces of the headliner 10 and the sub-chamber wall body 9 with the heat shield body 6 as in each of the above-described embodiments, and the same heat shield degree can be secured. .

In this gas engine, a valve seat 40 is formed around the central communication hole 36, a control valve 37 is arranged in the central communication hole 36, and a valve face 39 of the control valve 37 is seated on the valve seat 40. ing. Control valve 37
Is arranged in the cylinder head 4 penetrating through the center of the sub chamber wall 9 and the sub chamber 2. The control valve 37 has a central communication hole 36.
A valve face 39 having a conical surface which is seated on the valve seat 40 and closes the communication hole 5 by fitting with the projection 38 for closing the communication hole 5.
It has. A plurality of communication holes 5 are formed so as to be inclined from the valve seat 40 toward the wall surface of the cylinder.
6 has a large passage cross-sectional area formed in the center of the cylinder.

Although not shown, the control valve 37 can be constructed so as to be driven by an electromagnetic force by an electromagnetic valve driving device, and is controlled by a controller command in response to engine operating conditions such as engine load and engine speed. The opening / closing operation can be controlled. The solenoid valve driving device may be configured such that the communication hole 5 is opened first, and then the central communication hole 36 is opened in two steps. Control valve 37
The solenoid valve drive device that opens and closes the connection hole 5 opens the communication hole 5 with a small electromagnetic force and opens the central communication hole 36 with a large electromagnetic force.
Can be configured to open. For example, when a small current flows through the electromagnetic coil in response to a command from the controller in response to a detection signal from a load sensor that detects the engine load, a small electromagnetic force is applied and the control valve 37 is slightly lifted. When the control valve 37 rises slightly, the conical surface valve face 39 separates from the valve seat 40, the communication hole 5 opens, and the opening degree becomes a minute degree. Next, when a large current flows through the electromagnetic coil according to a command from the controller, a large electromagnetic force is applied, and the control valve 37 is largely lifted. Control valve 37
Is greatly raised, the protruding portion 38 comes out of the central communication hole 36, and the central communication hole 36 is opened.

[0028]

The structure of the heat shield engine according to the present invention is
It is configured as described above and has the following effects. That is, in the structure of this heat shield engine, the combustion chamber is disposed in the cavity of the cylinder head with the heat shield interposed, and the heat shield is formed of a vacuum layer inside the heat resistant metal body and the vacuum layer. Since the heat shield has a vacuum layer as an intermediate layer, it has a shield structure as compared with a conventional heat shield layer having an air layer and a heat insulating material. The heat rate can be improved to 80% or more. In addition, since the radiant heat shielding coating layer formed by Ag or Cr plating is formed on the inner surface of the heat-resistant metal body that constitutes the heat shield, the radiant heat from the high temperature side in the combustion chamber is shielded by the coating layer and heat is generated. The passing rate is reduced, and the heat shield of the combustion chamber can be greatly increased.

[Brief description of drawings]

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

FIG. 2 is an enlarged sectional view of a portion E of the heat shield in FIG.

FIG. 3 is a sectional view showing another embodiment of the structure of the heat shield engine according to the present invention.

FIG. 4 is a sectional view showing still another embodiment of the structure of the heat shield engine according to the present invention.

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

FIG. 6 is a front view showing a part of a control valve in the structure of the heat shield engine shown in FIG.

[Explanation of symbols]

 1 Main Chamber 2 Sub Chamber 3 Piston 4 Cylinder Head 5 Communication Hole 6 Heat Shield 7, 8 Heat Resistant Metal Body 9 Sub Chamber Wall 10 Headliner 11 Metal Wire 12 Vacuum Layer 13 Radiation Heat Shield Coating Layer 14 Wire Contact Part 16, 17 Cavity 19 Cylinder 20 Heat-insulating air layer 25 Cylinder block 29 Head bottom part 30 Liner upper part 31 Piston head 32 Piston skirt

Claims (9)

[Claims] 1. A structure of a heat shield engine having a cylinder head fixed to a cylinder block forming a cylinder in which a piston reciprocates, and a combustion chamber arranged in a cavity formed in the cylinder head. A heat shield is disposed inside the cavity of the cylinder head, and the heat shield has the shape of a heat resistant metal body in which a vacuum layer is formed inside and a radiant heat shielding coating layer is applied to the inner surface and the heat resistant metal body. A structure of a heat shield engine comprising a wire structure disposed within the vacuum layer for holding. 2. The heat shield engine according to claim 1, wherein the heat shield forms a heat shield layer in the cavity of the cylinder head and is arranged outside the combustion chamber. Construction. 3. The headliner made of ceramics or metal, which is composed of a lower surface of the head and an upper portion of the liner integrally formed with the lower surface of the head, and the combustion chamber is composed of a headliner made of ceramics or metal. Structure of the heat shield engine described. 4. A headliner made of ceramics or metal, which is composed of a lower surface of the head and an upper portion of the liner integrally formed with the lower surface of the head, and a ceramic or metal constituting a subchamber fixed to the headliner. 2. A sub-chamber wall body composed of a sub-chamber and a sub-chamber wall body having a communication hole for communicating the main chamber formed by the headliner with the sub-chamber. Alternatively, the structure of the heat shield engine according to item 2. 5. The structure of a heat shield engine according to claim 1, wherein the refractory metal body is made of a laminated material of thin plates of Ni—Cr based iron alloy or SUS. 6. The wire structure is made of a metal wire having a circular cross section, and a contact surface between the metal wire and the refractory metal body is reduced as much as possible. The structure of the heat shield engine according to any one of 1. 7. The structure of the heat shield engine according to claim 1, wherein the radiant heat shield coating layer is formed by specular plating of Ag or Cr. 8. The plate thickness of a joint portion connecting the inner and outer plates of the heat-resistant metal body forming the heat shield is smaller in a larger diameter portion than in a smaller diameter portion. The structure of the heat shield engine according to any one of claims 1 to 7. 9. The piston comprises a piston head and a piston skirt fixed to the piston head,
The heat shield is interposed between the piston head and the piston skirt.
The structure of the heat shield engine according to any one of to 8.