US20150300215A1 - Exhaust valve for engine - Google Patents

Exhaust valve for engine Download PDF

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Publication number
US20150300215A1
US20150300215A1 US14/542,274 US201414542274A US2015300215A1 US 20150300215 A1 US20150300215 A1 US 20150300215A1 US 201414542274 A US201414542274 A US 201414542274A US 2015300215 A1 US2015300215 A1 US 2015300215A1
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United States
Prior art keywords
engine
aerogel
exhaust valve
polyamideimide resin
coating layer
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Abandoned
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US14/542,274
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English (en)
Inventor
Hongkil Baek
Bokyung Kim
Seungwoo Lee
Jiho Kim
Inwoong Lyo
Jiyoun Seo
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Hyundai Motor Co
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Hyundai Motor Co
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Publication date
Application filed by Hyundai Motor Co filed Critical Hyundai Motor Co
Assigned to HYUNDAI MOTOR COMPANY reassignment HYUNDAI MOTOR COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BAEK, HONGKIL, KIM, BOKYUNG, KIM, JIHO, LEE, SEUNGWOO, LYO, INWOONG, SEO, JIYOUN
Publication of US20150300215A1 publication Critical patent/US20150300215A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/02—Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials
    • F01L3/04—Coated valve members or valve-seats

Definitions

  • An exemplary embodiment of the present invention relates to an engine for a vehicle, and more particularly, to an exhaust valve discharging an exhaust gas generated in a combustion chamber.
  • an internal combustion engine refers to an engine where a fuel gas generated by combusting fuel directly acts to a piston, a turbine blade, or the like to convert heat energy of the fuel into mechanical work.
  • the internal combustion engine refers to a reciprocal motion type engine which ignites a mixture gas of the fuel and air in a cylinder to cause an explosion and thus move a piston, but a gas turbine, a jet engine, a rocket, and the like are also the internal combustion engine.
  • the internal combustion engine is classified into a gas engine, a gasoline engine, a petroleum engine, a diesel engine, and the like by the used fuel.
  • the petroleum, gas, and gasoline engines cause ignition by an electric flame by a spark plug, and the diesel engine sprays the fuel into air at high temperatures and high pressure to cause spontaneous ignition.
  • the internal combustion engine of a vehicle has heat efficiency of about 15% to 35%, about 60% or more of total heat energy is consumed due to heat energy emitted to the outside through a wall of the internal combustion engine, an exhaust gas, and the like even at maximum efficiency of the internal combustion engine.
  • Various aspects of the present invention are directed to providing an exhaust valve for an engine, which is capable of ensuring high temperature durability and reducing heat energy emitted to the outside by applying an adiabatic coating layer securing high mechanical properties and heat resistance while having low thermal conductivity and a low volume thermal capacity, thereby improving efficiency of an engine and fuel efficiency of a vehicle.
  • an exhaust valve for an engine which discharges an exhaust gas generated in a combustion chamber of the engine, may include an adiabatic coating layer including a polyamideimide resin and an aerogel dispersed in the polyamideimide resin and having thermal conductivity of 0.60 W/m or less formed on a face portion of the exhaust valve coming into contact with a flame.
  • an exhaust valve for an engine which discharges an exhaust gas generated in a combustion chamber of the engine, may include an adiabatic coating layer including a polyamideimide resin and an aerogel dispersed in the polyamideimide resin and having thermal conductivity of 0.60 W/m or less formed on a neck portion of the exhaust valve coming into contact with the exhaust gas.
  • an exhaust valve for an engine which discharges an exhaust gas generated in a combustion chamber of the engine, may include an adiabatic coating layer including a polyamideimide resin and an aerogel dispersed in the polyamideimide resin and having thermal conductivity of 0.60 W/m or less formed on a face portion of the exhaust valve coming into contact with a flame and a neck portion of the exhaust valve coming into contact with the exhaust gas.
  • the adiabatic coating layer may have a thermal capacity of 1,250 KJ/m 3 K or less.
  • the polyamideimide resin may exist in a content of 2 wt % or less in the aerogel.
  • the polyamideimide resin may not exist at a depth corresponding to 5% or more of a longest diameter from a surface of the aerogel.
  • Each aerogel may have porosity of 92% to 99% while being dispersed in the polyamideimide resin.
  • the adiabatic coating layer may have a thickness of 50 ⁇ m to 500 ⁇ m.
  • the adiabatic coating layer may include 5 to 50 parts by weight of the aerogel based on 100 parts by weight of the polyamideimide resin.
  • an adiabatic coating layer securing high mechanical properties and heat resistance while having low thermal conductivity and a low volume thermal capacity, thereby improving efficiency of an engine and fuel efficiency of a vehicle.
  • vehicle or “vehicular” or other similar terms as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuel derived from resources other than petroleum).
  • a hybrid vehicle is a vehicle that has two or more sources of power, for example, both gasoline-powered and electric-powered vehicles.
  • FIG. 1 is a view schematically illustrating an exemplary exhaust valve for an engine according to the present invention.
  • FIG. 2 is a picture illustrating a surface of an adiabatic coating layer obtained in the exemplary exhaust valve for the engine according to the present invention.
  • FIG. 3 is a picture illustrating a surface of a coating layer obtained in a Comparative Example as compared to the exemplary exhaust valve for the engine according to the present invention.
  • FIG. 1 is a view schematically illustrating an exhaust valve for an engine according to various embodiments of the present invention.
  • an exhaust valve 100 for an engine may be applied to an engine for vehicles, which ignites and explodes a mixture gas of a fuel and air in a cylinder to move a piston.
  • the exhaust valve 100 for the engine may be applied to a turbo engine where a temperature of an exhaust gas is high.
  • the exhaust valve 100 for the engine is a matter for exhausting the exhaust gas generated in a combustion chamber of the cylinder, and includes a stem portion 11 , a face portion 13 , and a neck portion 15 .
  • the stem portion 11 may be defined as a portion coming into contact with a valve guide and the like
  • the face portion 13 may be defined as a portion coming into contact with a flame of the combustion chamber
  • the neck portion 15 may be defined as a portion coming into contact with the stem portion 11 and the face portion 13 and coming into contact with the exhaust gas.
  • the exhaust valve 100 according to the various embodiments of the present invention to an engine of a vehicle will be described as an example, but it should be understood that the protection scope of the present invention is not essentially limited thereto, and as long as the exhaust valve is an exhaust valve adopted in various kinds of internal combustion engines for the various purposes, such as a gas turbine, a jet engine, and a rocket, the technical spirit of the present invention may be applied thereto.
  • the exhaust valve 100 for the engine has a structure which can ensure high temperature durability and reduce heat energy emitted to the outside by applying an adiabatic coating layer securing high mechanical properties and heat resistance while having low thermal conductivity and a low volume thermal capacity, thereby improving efficiency of an engine and fuel efficiency of a vehicle.
  • various embodiments of the present invention provide the exhaust valve 100 for the engine, which can secure high temperature durability by reducing a valve temperature, without using a very costly high heat resistant material (inconel and the like) where a nickel (Ni) content is increased.
  • the adiabatic coating layer 50 is formed on the face portion 13 coming into contact with the flame. That is, the adiabatic coating layer 50 is a bottom surface of the valve, and may be formed on the face portion 13 coming into contact with the flame of the combustion chamber of the cylinder.
  • the adiabatic coating layer 50 is formed on the neck portion 15 coming into contact with the exhaust gas.
  • the adiabatic coating layer 50 may be formed on any one of the face portion 13 and the neck portion 15 , and may be formed on both the face portion 13 and the neck portion 15 .
  • adiabatic coating layer 50 applied to the exhaust valve 100 for the engine and an adiabatic coating composition thereof will be described in more detail.
  • adiabatic coating composition including a polyamideimide resin dispersed in a high boiling point organic solvent or an aqueous solvent and an aerogel dispersed in a low boiling point organic solvent as the adiabatic coating layer.
  • the adiabatic coating layer includes the polyamideimide resin and the aerogel dispersed in the polyamideimide resin, and has thermal conductivity of 0.60 W/m or less.
  • the adiabatic coating composition including the polyamideimide resin dispersed in the high boiling point organic solvent or the aqueous solvent and the aerogel dispersed in the low boiling point organic solvent may be provided.
  • the present inventors confirmed through an experiment that the coating composition obtained by dispersing the polyamideimide resin and the aerogel in predetermined solvents, respectively and then mixing the resultant solutions, and the coating layer obtained therefrom could secure high mechanical properties and heat resistance while having lower thermal conductivity and low density, and are applied to the internal combustion engine to reduce heat energy emitted to the outside and thus improve efficiency of the internal combustion engine and fuel efficiency of the vehicle, thereby accomplishing the invention.
  • the present inventors confirmed through an experiment that the aforementioned coating layer could be applied to a portion of the exhaust valve 100 or the entire exhaust valve 100 , which was a part of the internal combustion engine, to secure high temperature durability by reducing a valve temperature, without using the very costly high heat resistant material where the nickel (Ni) content was increased, thereby accomplishing the invention.
  • This aerogel has a structure formed by entangling microfilaments having a thickness that is a ten-thousandth of that of hair, and has porosity of 90% or more, and main materials thereof are silicon oxide, carbon, or an organic polymer.
  • the aerogel is an ultra-low density material having high translucency and ultra-low thermal conductivity due to the aforementioned structural characteristic.
  • the aerogel is easily broken by small impact due to high brittleness to exhibit very poor strength and it is difficult to process the aerogel to have various thicknesses and shapes, there is a predetermined limitation in application to the adiabatic material even though the aerogel has an excellent adiabatic characteristic, and in the case where the aerogel and other reactant are mixed, there are problems in that since a solvent or a solute permeates an inside of the aerogel to increase viscosity of a compound and thus make mixing unfeasible, it is difficult to perform complexation of the aerogel with the other material or use the aerogel after mixing with the other material, and a characteristic of the porous aerogel is not exhibited.
  • the polyamideimide resin exists while being dispersed in the high boiling point organic solvent or aqueous solvent and the aerogel exists while being dispersed in the low boiling point organic solvent, and thus a solvent dispersion phase of the polyamideimide resin and a solvent dispersion phase of the aerogel do not agglomerate but may be uniformly mixed, and the adiabatic coating composition may have a homogeneous composition.
  • the polyamideimide resin and the aerogel are mixed while the polyamideimide resin is dispersed in the high boiling point organic solvent or aqueous solvent and the aerogel is dispersed in the low boiling point organic solvent, to form the coating composition, and thus direct contact between the polyamideimide resin and the aerogel may be minimized until the adiabatic coating composition of the various embodiments is applied and dried, and the polyamideimide resin may be prevented from permeating the inside of the aerogel or the pore or being impregnated in the aerogel or the pore.
  • the low boiling point organic solvent may serve to materially mix the aerogel dispersed in the low boiling point organic solvent and the polyamideimide resin dispersed in the high boiling point organic solvent or aqueous solvent and thus uniformly distribute the aerogel and uniformly distribute the polyamideimide resin in the high boiling point organic solvent or aqueous solvent.
  • the aerogel may be secured at the same level or more, and the aerogel may be more uniformly dispersed in the polyamideimide resin to implement improved adiabatic characteristics together with high mechanical properties and heat resistance.
  • the adiabatic coating layer obtained from the adiabatic coating composition of the various embodiments, since physical properties and the structure of the aerogel may be maintained at the same level, the adiabatic coating layer may secure high mechanical properties and heat resistance while having lower thermal conductivity and lower density, and may be applied to the internal combustion engine to reduce heat energy emitted to the outside and thus improve efficiency of the internal combustion engine and fuel efficiency of the vehicle.
  • the adiabatic coating layer obtained from the adiabatic coating composition of the various embodiments may be applied to a portion of the exhaust valve or the entire exhaust valve, which is a part of the internal combustion engine, to secure high temperature durability by reducing a valve temperature, without using the very costly high heat resistant material where the nickel (Ni) content is increased.
  • the adiabatic coating layer may be applied to the face portion 13 coming into contact with the flame of the combustion chamber, the neck portion 15 coming into contact with the exhaust gas, and both the face portion 13 and the neck portion 15 .
  • the adiabatic coating composition of the various embodiments may be formed by mixing the polyamideimide resin dispersed in the high boiling point organic solvent or aqueous solvent and the aerogel dispersed in the low boiling point organic solvent as described above.
  • the mixing method is not largely limited, and any typically known physical mixing method may be used.
  • any typically known physical mixing method may be used.
  • the method of mixing the solvent dispersion phases of the polyamideimide resin and the aerogel is not limited to the aforementioned example.
  • the adiabatic coating composition of various embodiments may provide the adiabatic material, an adiabatic structure, and the like, which may be maintained over a long period of time in the internal combustion engine to which a repeated high temperature and high pressure condition is applied, and specifically, the adiabatic coating composition of various embodiments may be used in coating of an internal surface of the internal combustion engine or parts of the internal combustion engine, and as described above, may be used in coating of the face portion and/or the neck portion of the exhaust valve.
  • polyamideimide resin which may be included in the adiabatic coating composition of the various embodiments, is not largely limited, but the polyamideimide resin may have a weight average molecular weight of 3,000 to 300,000, or 4,000 to 100,000.
  • the weight average molecular weight of the polyamideimide resin is very small, it may be difficult to sufficiently secure mechanical properties, heat resistance, and an adiabatic property of a coating layer, a coating film, or a coating membrane obtained from the adiabatic coating composition, and a polymer resin may easily permeate the inside of the aerogel.
  • the weight average molecular weight of the polyamideimide resin is very large, uniformity or homogeneity of the coating layer, the coating film, or the coating membrane obtained from the adiabatic coating composition may deteriorate, dispersibility of the aerogel in the adiabatic coating composition may be reduced or a nozzle and the like of a coating device may be clogged when the adiabatic coating composition is applied, a heat-treating time of the adiabatic coating composition may be prolonged, and a heat-treating temperature may be increased.
  • a typical aerogel known in the art may be used as the aforementioned aerogel, and specifically, the aerogel of components including silicon oxide, carbon, polyimide, metal carbide, or a mixture of two or more kinds thereof may be used.
  • the aerogel may have a specific surface area of 100 cm 3 /g to 1,000 cm 3 /g, or 300 cm 3 /g to 900 cm 3 /g.
  • the adiabatic coating composition may include the aerogel in a content of 5 to 50 parts by weight or 10 to 45 parts by weight based on 100 parts by weight of the polyamideimide resin.
  • a weight ratio of the polyamideimide resin and the aerogel is a weight ratio of solids other than the dispersion solvent.
  • the content of the aerogel based on the polyamideimide resin is very small, it may be difficult to reduce thermal conductivity and density of the coating layer, the coating film, or the coating membrane obtained from the adiabatic coating composition, it may be difficult to secure a sufficient adiabatic property, and heat resistance of the adiabatic membrane manufactured from the adiabatic coating composition may be reduced.
  • the content of the aerogel based on the polymer resin is very large, it may be difficult to sufficiently secure mechanical properties of the coating layer, the coating film, or the coating membrane obtained from the adiabatic coating composition, cracks may be generated in an adiabatic membrane manufactured from the adiabatic coating composition, or it may be difficult to maintain a strong coat form of the adiabatic membrane.
  • the solid content of the polyamideimide resin in the high boiling point organic solvent or aqueous solvent is not largely limited, but the solid content may be 5 wt % to 75 wt % in consideration of uniformity or physical properties of the adiabatic coating composition.
  • the solid content of the aerogel in the low boiling point organic solvent is not largely limited, but the solid content may be 5 wt % to 75 wt % in consideration of uniformity or physical properties of the adiabatic coating composition.
  • the high boiling point organic solvent or aqueous solvent and the low boiling point organic solvent are not easily mutually dissolved or mixed, direct contact between the polyamideimide resin and the aerogel may be minimized until the adiabatic coating composition of the various embodiments is applied and dried, and the polyamideimide resin may be prevented from permeating the inside of the aerogel or the pore or being impregnated in the aerogel or the pore.
  • a boiling point difference between the high boiling point organic solvent and the low boiling point organic solvent may be 10° C. or more, 20° C. or more, or 10 to 200° C.
  • the high boiling point organic solvent an organic solvent having the boiling point of 110° C. or more may be used.
  • the high boiling point solvent may include anisole, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, ethyleneglycol monomethylether, ethyleneglycol monoethylether, ethyleneglycol monobutylether, butyl acetate, cyclohexanone, ethyleneglycol monoethylether acetate (BCA), benzene, hexane, DMSO, N,N′-dimethylformamide, or a mixture of two or more kinds thereof.
  • an organic solvent having the boiling point of less than 110° C. may be used.
  • the low boiling point organic solvent may include methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, iso-butyl alcohol, tert-butyl alcohol, acetone, methylene chloride, ethylene acetate, isopropyl alcohol, or a mixture of two or more kinds thereof.
  • aqueous solvent may include water, methanol, ethanol, ethyl acetate, or a mixture of two or more kinds thereof.
  • an adiabatic coating layer including a polyamideimide resin and an aerogel dispersed in the polyamideimide resin and having thermal conductivity of 0.60 W/m or less may be provided.
  • the present inventors manufactured the adiabatic coating layer, which could secure high mechanical properties and heat resistance while having low thermal conductivity and low density, and be applied to an internal combustion engine to reduce heat energy emitted to the outside and thus improve efficiency of the internal combustion engine and fuel efficiency of a vehicle, by using the aforementioned adiabatic coating composition of the various embodiments.
  • the present inventors manufactured the adiabatic coating layer, which could secure high temperature durability by using the aforementioned adiabatic coating composition of the various embodiments to reduce an exhaust valve temperature, without using the very costly high heat resistant material where the nickel (Ni) content was increased.
  • the aerogel is uniformly dispersed over an entire region of the polyamideimide resin, and thus physical properties implemented from the aerogel, for example, low thermal conductivity and low density may be more easily secured, and a characteristic revealed from the polyamideimide resin, for example, high mechanical properties, heat resistance, and the like, may be implemented at the same level or more as the case where only the polyamideimide resin is used.
  • the adiabatic coating layer may have low thermal conductivity and the high thermal capacity, and specifically, the adiabatic coating layer may have thermal conductivity of 0.60 W/m or less, 0.55 W/m or less, or 0.60 W/m to 0.200 W/m, and the adiabatic coating layer may have the thermal capacity of 1,250 KJ/m 3 K or less or 1,000 to 1,250 KJ/m 3 K.
  • the adiabatic coating composition of the various embodiments includes the polyamideimide resin dispersed in the high boiling point organic solvent or aqueous solvent and the aerogel dispersed in the low boiling point organic solvent, direct contact between the polyamideimide resin and the aerogel may be minimized until the coating composition is applied and dried, and thus the polyamideimide resin may not permeate the inside of the aero gel or the pore included in the finally manufactured adiabatic coating layer or not be impregnated in the aerogel or the pore.
  • the polyamideimide resin may not substantially exist in the aerogel dispersed in the polyamideimide resin, and for example, the polyamideimide resin may exist in a content of 2 wt % or less or 1 wt % or less in the aerogel.
  • the aerogel may exist while being dispersed in the polyamideimide resin, and in this case, the outside of the aerogel may be in contact with or combined with the polyamideimide resin, but the polyamideimide resin may not exist in the aerogel.
  • the polyamideimide resin may not exist at a depth corresponding to 5% or more of a longest diameter from a surface of the aerogel included in the adiabatic coating layer.
  • the aerogel may have the same level of porosity before and after the aerogel is dispersed in the polyamideimide resin, and specifically, each aerogel included in the adiabatic coating layer may have porosity of 92% to 99% while being dispersed in the polyamideimide resin.
  • the adiabatic coating layer of the various embodiments may provide an adiabatic material, an adiabatic structure, and the like, which may be maintained over a long period of time in the internal combustion engine to which a repeated high temperature and high pressure condition is applied, and specifically, the adiabatic coating layer of the various embodiments may be formed on the internal surface of the internal combustion engine or the exhaust valve that is a part of the internal combustion engine.
  • a thickness of the adiabatic coating layer of the various embodiments may be determined according to an application field or position, or required physical properties, and for example, may be 50 ⁇ m to 500 ⁇ m.
  • the adiabatic coating layer of the various embodiments may include the aerogel in a content of 5 to 50 parts by weight or 10 to 45 parts by weight based on 100 parts by weight of the polyamideimide resin.
  • the content of the aerogel based on the polyamideimide resin is very small, it may be difficult to reduce thermal conductivity and density of the adiabatic coating layer, it may be difficult to secure a sufficient adiabatic property, and heat resistance of the adiabatic coating layer may be reduced. Further, if the content of the aerogel based on the polymer resin is very large, it may be difficult to sufficiently secure mechanical properties of the adiabatic coating layer, cracks of the adiabatic coating layer may be generated, or it may be difficult to maintain a strong coat form of the adiabatic membrane.
  • the polyamideimide resin may have a weight average molecular weight of 3,000 to 300,000 or 4,000 to 100,000.
  • the aerogel may include one or more kinds of compounds selected from the group consisting of silicon oxide, carbon, polyimide, and metal carbide.
  • the aerogel may have a specific surface area of 100 cm 3 /g to 1,000 cm 3 /g.
  • a specific content of the polyamideimide resin and the aerogel includes the aforementioned content of the adiabatic coating composition of the various embodiments.
  • the adiabatic coating layer of the various embodiments may be obtained by drying the adiabatic coating composition of the various embodiments.
  • a device or a method, which may be used in drying the adiabatic coating composition of the various embodiments, is not largely limited, and a spontaneous drying method at a temperature of room temperature or more, a drying method by heating to a temperature of 50° C. or more, or the like may be used.
  • the adiabatic coating composition of the various embodiments may be applied on a coating target, for example, the internal surface of the internal combustion engine or an external surface of parts of the internal combustion engine, and semi-dried at a temperature of 50° C. to 200° C. one or more times, and the semi-dried coating composition may be completely dried at a temperature of 200° C. or more to form the adiabatic coating layer.
  • a specific manufacturing method of the adiabatic coating layer of the various embodiments is not limited thereto.
  • porous silica aerogel (specific surface area: about 500 cm 3 /g) dispersed in ethyl alcohol and the polyamideimide resin (products manufactured by Solvay SA, weight average molecular weight: about 11,000) dispersed in xylene were injected into the 20 g reactor, the zirconia bead was added thereto (440 g), and ball milling was performed under the room temperature and normal pressure condition at the speed of 150 to 300 rpm to manufacture the adiabatic coating composition (coating solution).
  • the weight ratio of the porous silica aerogel based on the polyamideimide resin is the same as the matter described in the following Table 1.
  • the obtained adiabatic coating composition was applied on a part for a vehicle engine by a spray coating method.
  • the adiabatic coating composition was applied on the part, primary semi-drying was performed at about 150° C. for about 10 minutes, the adiabatic coating composition was re-applied, and secondary semi-drying was performed at about 150° C. for about 10 minutes. After secondary semi-drying, the adiabatic coating composition was applied again, and complete drying was performed at about 250° C. for about 60 minutes to form the adiabatic coating layer on the part.
  • the thickness of the formed coating layer is the same as the matter described in the following Table 1.
  • the solution (PAI solution) of the polyamideimide resin (products manufactured by Solvay SA, weight average molecular weight: about 11,000) dispersed in xylene was applied on a part for a vehicle engine by the spray coating method.
  • the PAI solution was applied on the part, primary semi-drying was performed at about 150° C. for about 10 minutes, the PAI solution was re-applied, and secondary semi-drying was performed at about 150° C. for about 10 minutes. After the secondary semi-drying, the PAI solution was applied again, and complete drying was performed at about 250° C. for about 60 minutes to form the adiabatic coating layer on the part.
  • the thickness of the formed coating layer is the same as the matter described in the following Table 1.
  • porous silica aerogel (specific surface area: about 500 cm 3 /g) and the polyamideimide resin (products manufactured by Solvay SA, weight average molecular weight: about 11,000) dispersed in xylene were injected into the 20 g reactor, the zirconia bead was added thereto (440 g), and ball milling was performed under the room temperature and normal pressure condition at the speed of 150 to 300 rpm to manufacture the coating composition (coating solution).
  • the weight ratio of the porous silica aerogel based on the polyamideimide resin is the same as the matter described in the following Table 1.
  • the coating layer having the thickness of about 200 ⁇ m was formed by the same method as Example 1.
  • Thermal conductivity of the coating layers on the parts obtained in the Examples and the Comparative Examples was measured on the basis of ASTM E1461 under the room temperature and normal pressure condition using the laser flash method by the thermal diffusion measuring method.
  • the thermal capacity was confirmed by measuring specific heat of the coating layers on the parts obtained in the Examples and the Comparative Examples on the basis of ASTM E1269 under the room temperature condition using the DSC device and using sapphire as a reference.
  • the adiabatic coating layer obtained in Examples 1 to 3 had the thermal capacity of 1240 KJ/m 3 K or less and thermal conductivity of 0.54 W/m or less in the thickness of 120 to 200 ⁇ m. Accordingly, the adiabatic coating layer obtained in Examples 1 to 3 may be applied to coating of the parts of the internal combustion engine to reduce heat energy emitted to the outside and thus improve efficiency of the internal combustion engine and fuel efficiency of the vehicle.
  • the adiabatic coating layer obtained from Examples 1 to 3 may be applied to coating of a portion of the exhaust valve or the entire exhaust valve to secure high temperature durability by reducing a valve temperature, without using the very costly high heat resistant material where the nickel (Ni) content is increased.
  • the polyamideimide resin does not permeate the inside of the aerogel and almost 92% or more of the pores in the aerogel are maintained.
  • the adiabatic coating layer capable of securing high mechanical properties and heat resistance while having low thermal conductivity and the low volume thermal capacity, thereby improving efficiency of an engine and fuel efficiency of a vehicle.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Paints Or Removers (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)
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KR101575328B1 (ko) * 2014-04-29 2015-12-07 현대자동차 주식회사 엔진용 흡기 밸브

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CN105038577A (zh) 2015-11-11

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