WO2020170635A1 - Internal combustion engine piston, and method for manufacturing same - Google Patents

Internal combustion engine piston, and method for manufacturing same Download PDF

Info

Publication number
WO2020170635A1
WO2020170635A1 PCT/JP2020/000423 JP2020000423W WO2020170635A1 WO 2020170635 A1 WO2020170635 A1 WO 2020170635A1 JP 2020000423 W JP2020000423 W JP 2020000423W WO 2020170635 A1 WO2020170635 A1 WO 2020170635A1
Authority
WO
WIPO (PCT)
Prior art keywords
piston
internal combustion
combustion engine
manufacturing
particles
Prior art date
Application number
PCT/JP2020/000423
Other languages
French (fr)
Japanese (ja)
Inventor
正登 佐々木
Original Assignee
日立オートモティブシステムズ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日立オートモティブシステムズ株式会社 filed Critical 日立オートモティブシステムズ株式会社
Publication of WO2020170635A1 publication Critical patent/WO2020170635A1/en

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/10—Pistons  having surface coverings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J1/00—Pistons; Trunk pistons; Plungers
    • F16J1/01—Pistons; Trunk pistons; Plungers characterised by the use of particular materials

Definitions

  • the present invention relates to a piston for an internal combustion engine and a method for manufacturing the piston.
  • Patent Document 1 discloses a technique of forming a low thermal conductive layer on the crown surface of a piston base material by performing spark plasma sintering of a mixed powder containing aluminum particles and ceramic particles.
  • a method for manufacturing a piston of an internal combustion engine in an embodiment of the present invention is a mixed powder preparation step of preparing a mixed powder containing particles of charcoal and particles of a metal binder, and applying an electric current between the mixed powder and the piston.
  • a sintering step of sintering the mixed powder on the crown surface of the piston.
  • the low thermal conductive layer can be easily formed.
  • FIG. 1 is a perspective view of a piston of an internal combustion engine according to a first embodiment
  • FIG. 2 is a sectional view taken along the line S1-S1 of FIG.
  • the piston 1 has a crown surface 2 on its upper surface.
  • the crown surface 2 faces the combustion chamber of the engine and is a part of the inner wall of the combustion chamber, and is a portion conventionally provided with a heat insulating layer in order to improve combustion efficiency.
  • the low thermal conductive layer 3 having both low thermal conductivity and low volume specific heat is provided on the upper surface of the piston 1, that is, the crown surface 2.
  • the low thermal conductive layer 3 is provided along the surface shape of the crown surface 2 and has a uniform film thickness.
  • FIG. 3 is a schematic diagram of the low thermal conductive layer of the first embodiment.
  • the piston 1 includes a piston body 1a, a low heat conductive layer 3 and a sealing layer 4.
  • the piston body 1a is formed of an aluminum alloy (for example, AC8A).
  • the low heat conductive layer 3 covers the crown surface 2 of the piston body 1a.
  • the low thermal conductive layer 3 has a metal binder 5, voids 6 and charcoal 7.
  • the metal binder 5 is an aluminum alloy (for example, A5083).
  • the voids 6 are holes and are uniformly distributed in the low thermal conductive layer 3.
  • the charcoal 7 is located inside the void 6.
  • the charcoal 7 is obtained by burning particles of bamboo charcoal, for example.
  • the charcoal 7 may be charcoal having a characteristic of starting combustion at 600 degrees Celsius or less.
  • charcoal is, in a narrow sense, a combustible substance containing carbon as a main component, which is obtained by steaming and carbonizing an organic substance, and in a broader sense, it is a general fuel containing carbon as a main component. Means Further, it is characterized by having conductivity as charcoal.
  • the sealing layer 4 is provided on the upper surface of the low thermal conductive layer 3 and seals the surface of the low thermal conductive layer 3.
  • the sealing layer 4 is made of a heat resistant resin (for example, PAI, PPS, etc.) or polysilazane. Since the side surface (outer peripheral surface) of the low thermal conductive layer 3 is not covered with the sealing layer 4, the void portion 6 of the void portion 6 that is desired on the outer peripheral surface of the low thermal conductive layer 3 is open to the atmosphere.
  • the method for manufacturing the piston 1 includes a mixed powder preparation step, a sintering step, a heat treatment step, and a sealing treatment step.
  • the mixed powder preparation step is a step of preparing a mixed powder that becomes the low thermal conductive layer 3 by uniformly mixing the particles of charcoal and the particles of the metal binder.
  • bamboo charcoal particles (15 ⁇ m) are used as the charcoal particles, and aluminum alloy (A5083) particles (20 ⁇ m) are used as the metal binder particles.
  • the sintering of the mixed powder in the sintering step can be promoted.
  • the content of bamboo charcoal particles in the mixed powder is set in the range of 25% by weight or more and 65% by weight or less. In the first embodiment, the content of bamboo charcoal particles is 55% by weight, and the content of aluminum alloy particles is 45% by weight.
  • paraffin wax is added to the mixed powder, and the mixture is heated at 120° C. to dissolve the paraffin and then stirred to obtain a paste-like mixture.
  • the sintering step is a step of sintering the piston base material to be the piston body 1a and the mixture by spark plasma sintering after the mixed component preparation step.
  • FIG. 4 is a schematic diagram showing an aspect of the sintering step of the first embodiment.
  • the piston base material 11 is housed in a carbon-made restraining metal fitting 12, and a disc-shaped mixture 13 is placed on the crown surface 2 of the piston base material 11.
  • the mixture 13 may be applied to the crown surface 2.
  • the upper electrode 14 made of carbon having an end surface shape that follows the shape of the crown surface 2 is pressed downward from above (FIG. 4(b)).
  • FIG. 5 is a schematic diagram showing the state of the mixed powder before the spark plasma sintering.
  • the mixture 13 includes bamboo charcoal particles 16 and aluminum alloy particles 17, and since the bamboo charcoal particles 16 are distributed in the mixture 13 so as to connect the upper surface and the lower surface of the mixture 13, the upper electrode 14 and the piston base material. 11 is a state of being electrically connected through particles 16 of bamboo charcoal. Therefore, the mixture 13 is sintered on the upper surface of the piston base material 11 due to the heat generation of the aluminum alloy particles due to the application of the pulse voltage, the discharge plasma energy generated between the particles, etc., and the bamboo charcoal particles 16 as shown in FIG. A sintered body 15 containing is obtained. This sintered body 15 becomes the low thermal conductive layer 3. In the sintered body 15, a large number of minute gaps (voids) 16a are formed around the particles 16 of bamboo charcoal.
  • the piston 1 according to the first embodiment includes a low thermal conductive layer 3 having a void portion 6, charcoal 7, and a metal binder 5.
  • the low heat conduction layer 3 has a structure for reducing heat conductivity from the combustion chamber to the piston body 1a, and functions as a heat insulating layer between the combustion chamber and the piston body 1a.
  • the low heat conduction layer 3 reduces the heat transfer from the gas in the combustion chamber to the piston head (piston body 1a), and suppresses the heat of the air-fuel mixture from being taken by the piston body 1a. Therefore, it is possible to suppress a decrease in the combustion efficiency of the engine (cooling loss) and improve the thermal efficiency of the engine. Since the charcoal 7 remaining in the voids 6 is porous, it does not impair the heat insulating performance of the voids 6.
  • the piston 1 includes a sealing layer 4 that seals the upper surface of the low thermal conductive layer 3. Since the low thermal conductive layer 3 is a porous body having a large number of voids 6, by covering the upper surface with the sealing layer 4, it is possible to prevent the mixture from entering the low thermal conductive layer 3 from the combustion chamber. As a result, thermal fatigue of the low thermal conductive layer 3 can be suppressed, so that durability can be improved.
  • the sealing layer 4 is made of heat resistant resin or polysilazane. Since the heat-resistant resin and polysilazane have high heat resistance, thermal fatigue of the low heat conductive layer 3 can be suppressed. Part of the void portion 6 is open to the atmosphere.
  • the bamboo charcoal particles 16 start burning at a temperature (400 degrees Celsius) lower than the melting point (more than 600 degrees Celsius) of the aluminum alloy (A5083) that is the material of the piston base material 11. Therefore, the bamboo charcoal particles 16 can be burned without melting the piston base material 11 by the solution treatment. As a result, by performing heat treatment after the sintering step, the particles 16 of bamboo charcoal disappear, and a large number of voids 6 are formed in the low thermal conductive layer 3. Since the thermal conductivity (W/mK) of the void portion 6 is lower than that of the bamboo charcoal particles 16, the thermal conductivity of the low thermal conductive layer 3 can be further lowered. Since the melting point of an aluminum alloy generally used as a material for pistons is 600 degrees Celsius or higher, the charcoal 7 may have a characteristic of starting combustion at 600 degrees Celsius or lower.
  • the voids 6 and the metal binder 5 are uniformly distributed in the low thermal conductive layer 3. That is, since the voids 6 are uniformly distributed in the low heat conductive layer 3, a uniform heat insulating effect can be obtained regardless of the position of the crown surface 2.
  • the piston 1 and the metal binder 5 are made of an aluminum alloy. By using the same metal for the piston 1 and the metal binder 5, a strong solid phase joint is formed at the interface between the crown surface 2 and the low thermal conductive layer 3, and the adhesion between the two can be secured, resulting in excellent durability.
  • the low heat conduction layer 3 can be realized.
  • the method for manufacturing the piston 1 according to the first embodiment includes a powder mixture preparation step of preparing a mixture 13 containing particles 16 of bamboo charcoal and particles 17 of an aluminum alloy, and a mixture 13 and a piston base material 11 are energized to form the mixture 13.
  • a sintering step of sintering on the crown surface (2) Since the particles 16 of bamboo charcoal are conductors, the mixture 13 and the piston base material 11 are energized via the particles 16 of bamboo charcoal. Therefore, even if the surfaces of the aluminum alloy particles 17 are insulated by oxidation, spark plasma sintering is possible. Therefore, the step of heating and melting the mixture 13 before the spark plasma sintering is unnecessary, so that the formation of the low thermal conductive layer 3 can be facilitated as compared with the conventional piston manufacturing method.
  • bamboo charcoal particles 16 and aluminum alloy particles 17 are mixed, and in the sintering step, spark plasma sintering is performed. Therefore, even when the particles 17 of the aluminum alloy are oxidized to be an insulator, the spark plasma sintering can be performed through the particles 16 of the bamboo charcoal which is the conductor. In spark plasma sintering, rapid heating and cooling can be performed compared to atmospheric heating in an electric furnace or the like, so that the sintering time can be greatly shortened.
  • bamboo charcoal particles 16 and aluminum alloy particles 17 are homogeneously mixed. Therefore, since the voids 6 are uniformly distributed in the low heat conductive layer 3, the low heat conductive layer 3 having a uniform heat insulating effect can be obtained.
  • the mixed powder preparation step paraffin wax is added to the mixed powder. Therefore, since the paste-like mixture 13 is obtained by melting the paraffin wax by heating, installation of the mixed powder on the crown surface 2 can be facilitated.
  • the bamboo charcoal particles 16 are distributed in the mixture 13 such that the upper electrode 14 and the piston base material 11 are electrically connected via the bamboo charcoal particles 16 in the sintering process. Therefore, spark plasma sintering is possible through the particles 16 of bamboo charcoal, which is a conductor.
  • the content of the bamboo charcoal particles 16 in the mixed powder was set to 25% by weight or more and 65% by weight or less by spark plasma sintering. It has been clarified that the low thermal conductive layer 3 can be formed.Furthermore, by setting the content of the aluminum alloy particles 17 to 45% by weight and the content of the bamboo charcoal particles 17 to 55% by weight in the mixed powder, discharge It was found that the balance of the conductivity, the heat insulating performance of the low thermal conductive layer 3 and the strength of the metal binder 5 at the time of plasma sintering can be optimized.
  • a sealing treatment step of performing a sealing treatment on the upper surface of the sintered body 15 sintered on the crown surface 2 is provided. Therefore, the sealing layer 4 for preventing the mixture from entering the low thermal conductive layer 3 can be formed, and the thermal fatigue of the low thermal conductive layer 3 can be suppressed.
  • a heat resistant resin or polysilazane is applied to the upper surface of the sintered body 15 sintered on the crown surface 2 after the heat treatment step. Therefore, the sealing layer 4 can be formed by a simple method.
  • FIG. 9 is a schematic diagram which shows the aspect of the mixed powder preparation process of Embodiment 2.
  • paraffin wax is added to a mixture of particles 16 of charcoal and particles 17 of aluminum alloy, heated and stirred, and thinly spread to form a disc-shaped paraffin sheet 23.
  • an aluminum foil 24 having a thickness of 10 to 50 ⁇ m is laid on the upper surface of the paraffin sheet 23.
  • FIG. 10 is a schematic diagram which shows the aspect of the sintering process of Embodiment 2.
  • the paraffin sheet 23 is placed on the crown surface 2 with the aluminum foil 24 facing upward.
  • the piston base material 11 and the upper mold electrode 14 are heated to 120 degrees Celsius in advance.
  • the piston base material 11 and the upper electrode 14 may be heated after the paraffin sheet 23 is placed on the crown surface 2.
  • pressure is applied in the vertical direction by the upper mold electrode 14 and the restraint fitting 12 (FIG. 10(b)).
  • a pulse voltage is applied to the upper electrode and the lower electrode from the power source for about 1 minute.
  • the sintered body 15 is sintered on the crown surface 2 and, at the same time, the sealing layer 4 is formed on the surface of the sintered body 15. That is, in the second embodiment, the sealing process is performed simultaneously with the sintering process.
  • FIG. 12 is a schematic diagram showing an aspect of the sintering step of the third embodiment.
  • the paraffin sheet 23 is placed on the crown surface 2.
  • pressure is applied in the vertical direction by the upper mold electrode 14 and the restraint fitting 12 (FIG. 12(b)).
  • a pulse voltage is applied to the upper electrode and the lower electrode from the power source for about 1 minute.
  • the sintered body 15 is sintered on the crown surface 2 and, at the same time, the sealing layer 4 is formed on the surface of the sintered body 15.
  • the aluminum layer 27 is a layer made of aluminum particles. Therefore, compared with the case where the aluminum layer 27 is made of aluminum foil, the sealing layer 4 can be made thicker, so that the strength of the sealing layer 4 can be improved. Further, the crown surface 2 can be sealed with almost no space.
  • the embodiment for carrying out the present invention has been described above, but the specific configuration of the present invention is not limited to the configuration of the embodiment, and there are design changes and the like within the scope not departing from the gist of the invention. Also included in the present invention.
  • the low thermal conductive layer may have a shape that covers a part of the crown surface. Further, the film thickness of the low thermal conductive layer may be non-uniform.
  • a piston of an internal combustion engine in one aspect thereof, is a piston of an internal combustion engine, comprising a crown surface facing a combustion chamber of the internal combustion engine, a low heat conductive layer provided on the crown surface, and a void portion. And the low thermal conductive layer having charcoal and a metal binder.
  • a sealing layer that seals the surface of the low thermal conductive layer is provided.
  • the sealing layer is formed of a heat resistant resin or polysilazane.
  • the sealing layer is formed of aluminum.
  • a part of the void portion is open to the atmosphere.
  • the charcoal has the property of initiating combustion at 600 degrees Celsius or less.
  • the voids, the charcoal, and the metal binder are uniformly distributed in the low thermal conductive layer.
  • the piston and the metal binder are formed of aluminum.
  • the mixed powder preparation step uniformly mixes the particles of the charcoal and the particles of the metal binder.
  • the discharge plasma electrode and the piston base material are electrically connected to each other via the charcoal particles. So that it is distributed in the mixed powder.
  • the content of the particles of the charcoal in the mixed powder is 25% by weight or more and 65% by weight or less.
  • the content of the metal binder particles in the mixed powder is 45% by weight, and the content of the charcoal particles is 55% by weight.
  • paraffin wax is added to the mixed powder.
  • the present invention is not limited to the above-described embodiment, and various modifications are included.
  • the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described.
  • a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)

Abstract

This method for manufacturing a piston includes: a mixed power preparation step of preparing a mixture including charcoal particles and aluminum alloy particles; and a sintering step of sintering the mixture onto a crown surface of a piston base material by causing an electric current to flow between the mixture and the piston base material.

Description

内燃機関のピストンおよびその製造方法Internal combustion engine piston and method of manufacturing the same
　本発明は、内燃機関のピストンおよびその製造方法に関する。 The present invention relates to a piston for an internal combustion engine and a method for manufacturing the piston.
　特許文献１には、アルミニウム粒子とセラミック粒子とを含む混合粉をピストン基材の冠面に放電プラズマ焼結することにより、冠面に低熱伝導層を形成する技術が開示されている。 Patent Document 1 discloses a technique of forming a low thermal conductive layer on the crown surface of a piston base material by performing spark plasma sintering of a mixed powder containing aluminum particles and ceramic particles.
特開2018-053879号公報JP 2018-053879 JP
　しかしながら、上記特許文献１にあっては、アルミニウム粒子の表面は酸化により絶縁化しており、さらにセラミック粒子は絶縁体であるため、放電焼結開始直後は混合粉とピストン基材との間に電気が流れない。このため、ピストン基材において混合粉に接触する箇所を加熱し、混合粉を溶解させてから放電焼結を行う必要があり、低熱伝導層の形成に手間を要するという問題があった。
  本発明の目的の一つは、低熱伝導層を容易に形成できる内燃機関のピストンおよびその製造方法を提供することにある。 However, in Patent Document 1, the surface of the aluminum particles is insulated by oxidation, and the ceramic particles are an insulator. Does not flow. Therefore, it is necessary to heat the portion of the piston base material that comes into contact with the mixed powder to melt the mixed powder and then perform the electric discharge sintering, which causes a problem that it takes time to form the low thermal conductive layer.
One of the objects of the present invention is to provide a piston for an internal combustion engine that can easily form a low thermal conductive layer and a method for manufacturing the piston.
　本発明の一実施形態における内燃機関のピストンの製造方法は、炭の粒子と金属バインダの粒子とを含む混合粉を準備する混合粉準備工程と、混合粉とピストンとの間に電流を流して混合粉をピストンの冠面上に焼結する焼結工程と、を備える。 A method for manufacturing a piston of an internal combustion engine in an embodiment of the present invention is a mixed powder preparation step of preparing a mixed powder containing particles of charcoal and particles of a metal binder, and applying an electric current between the mixed powder and the piston. A sintering step of sintering the mixed powder on the crown surface of the piston.
　よって、本発明の一実施形態にあっては、低熱伝導層を容易に形成できる。 Therefore, in the embodiment of the present invention, the low thermal conductive layer can be easily formed.
実施形態１の内燃機関のピストンの斜視図である。FIG. 3 is a perspective view of a piston of the internal combustion engine of the first embodiment. 図１のS1-S1線矢視断面図である。FIG. 2 is a sectional view taken along the line S1-S1 of FIG. 実施形態１の低熱伝導層の模式図である。3 is a schematic view of a low heat conductive layer of Embodiment 1. FIG. 実施形態１の焼結工程の態様を示す模式図である。3 is a schematic view showing an aspect of a sintering step of Embodiment 1. FIG. 放電プラズマ焼結前の混合粉の状態を示す模式図である。It is a schematic diagram which shows the state of the mixed powder before a spark plasma sintering. 放電プラズマ焼結後の焼結体の状態を示す模式図である。It is a schematic diagram which shows the state of the sintered compact after spark plasma sintering. 放電プラズマ焼結実験の態様を示す模式図である。It is a schematic diagram which shows the aspect of a spark plasma sintering experiment. 混合粉における炭の粒子の含有量を変化させたときの放電プラズマ焼結実験および熱処理実験の結果を示す図である。It is a figure which shows the result of the spark plasma sintering experiment and heat processing experiment when changing the content of the particle|grains of the charcoal in mixed powder. 実施形態２の混合粉準備工程の態様を示す模式図である。It is a schematic diagram which shows the aspect of the mixed powder preparation process of Embodiment 2. 実施形態２の焼結工程の態様を示す模式図である。7 is a schematic view showing an aspect of a sintering step of Embodiment 2. FIG. 実施形態３の混合粉準備工程の態様を示す模式図である。It is a schematic diagram which shows the aspect of the mixed powder preparation process of Embodiment 3. 実施形態３の焼結工程の態様を示す模式図である。It is a schematic diagram which shows the aspect of the sintering process of Embodiment 3.
　〔実施形態１〕
  図１は実施形態１の内燃機関のピストンの斜視図、図２は図１のS1-S1線矢視断面図である。
  ピストン1は、その上面に冠面2を備える。冠面2は、エンジンの燃焼室に面し、燃焼室の内壁の一部となる部分であり、燃焼効率を向上するために従来断熱層が設けられる部分である。実施形態１では、ピストン1の上面、すなわち冠面2上に、低熱伝導性および低い体積比熱を併せ持つ低熱伝導層3を備える。低熱伝導層3は、図２に示すように、冠面2の表面形状に沿って設けられ、均一な被膜厚さを持つ。 [Embodiment 1]
1 is a perspective view of a piston of an internal combustion engine according to a first embodiment, and FIG. 2 is a sectional view taken along the line S1-S1 of FIG.
The piston 1 has a crown surface 2 on its upper surface. The crown surface 2 faces the combustion chamber of the engine and is a part of the inner wall of the combustion chamber, and is a portion conventionally provided with a heat insulating layer in order to improve combustion efficiency. In the first embodiment, the low thermal conductive layer 3 having both low thermal conductivity and low volume specific heat is provided on the upper surface of the piston 1, that is, the crown surface 2. As shown in FIG. 2, the low thermal conductive layer 3 is provided along the surface shape of the crown surface 2 and has a uniform film thickness.
　図３は、実施形態１の低熱伝導層の模式図である。
  ピストン1は、ピストン本体1a、低熱伝導層3および封孔層4を備える。ピストン本体1aは、アルミニウム合金（例えばAC8A）により形成されている。
  低熱伝導層3は、ピストン本体1aの冠面2を覆う。低熱伝導層3は、金属バインダ5、空隙部6および炭7を有する。金属バインダ5は、アルミニウム合金（例えばA5083）である。空隙部6は、空孔であって、低熱伝導層3内に均質に分布する。炭7は、空隙部6の内部に位置する。炭7は、例えば竹炭の粒子が燃焼したものである。炭7は、摂氏600度以下で燃焼を開始する特性を有する炭であればよい。竹炭に代えて、例えば、石炭、泥炭、練炭、コークス、活性炭等の粒子が燃焼したものであってもよい。ここで、炭とは、狭義には、有機物が蒸し焼きになり炭化することで得られる、炭素を主成分とする可燃物のことであり、また、広義には、炭素を主成分とする燃料全般を意味する。また、炭として、導電性を有することを特徴とする。
  封孔層4は、低熱伝導層3の上面に設けられ、低熱伝導層3の表面を封孔する。封孔層4は、耐熱樹脂（例えばPAI,PPS等）またはポリシラザンにより形成されている。低熱伝導層3の側面（外周面）は封孔層4で覆われていないため、空隙部6のうち低熱伝導層3の外周面に望む空隙部6は、大気開放されている。 FIG. 3 is a schematic diagram of the low thermal conductive layer of the first embodiment.
The piston 1 includes a piston body 1a, a low heat conductive layer 3 and a sealing layer 4. The piston body 1a is formed of an aluminum alloy (for example, AC8A).
The low heat conductive layer 3 covers the crown surface 2 of the piston body 1a. The low thermal conductive layer 3 has a metal binder 5, voids 6 and charcoal 7. The metal binder 5 is an aluminum alloy (for example, A5083). The voids 6 are holes and are uniformly distributed in the low thermal conductive layer 3. The charcoal 7 is located inside the void 6. The charcoal 7 is obtained by burning particles of bamboo charcoal, for example. The charcoal 7 may be charcoal having a characteristic of starting combustion at 600 degrees Celsius or less. Instead of bamboo charcoal, particles of coal, peat, briquette, coke, activated carbon or the like may be burned. Here, charcoal is, in a narrow sense, a combustible substance containing carbon as a main component, which is obtained by steaming and carbonizing an organic substance, and in a broader sense, it is a general fuel containing carbon as a main component. Means Further, it is characterized by having conductivity as charcoal.
The sealing layer 4 is provided on the upper surface of the low thermal conductive layer 3 and seals the surface of the low thermal conductive layer 3. The sealing layer 4 is made of a heat resistant resin (for example, PAI, PPS, etc.) or polysilazane. Since the side surface (outer peripheral surface) of the low thermal conductive layer 3 is not covered with the sealing layer 4, the void portion 6 of the void portion 6 that is desired on the outer peripheral surface of the low thermal conductive layer 3 is open to the atmosphere.
　以下、ピストン1の製造方法のうち、低熱伝導層3および封孔層4の形成に関する部分について説明する。ピストン1の製造方法は、混合粉準備工程、焼結工程、熱処理工程および封孔処理工程を含む。
  （混合粉準備工程）
  混合粉準備工程は、炭の粒子と金属バインダの粒子とを均質に混合して低熱伝導層3となる混合粉を準備する工程である。炭の粒子としては竹炭の粒子(15μm)を用い、金属バインダの粒子としてはアルミニウム合金(A5083)の粒子(20μm)を用いる。なお、A5083に加えて、Al-Si合金の粉末やAl-Mg合金の粉末等、低融点のアルミニウム合金の粉末を混合させることにより、焼結工程における混合粉の焼結を促進できる。混合粉における竹炭の粒子の含有量は、25重量%以上かつ65重量%以下の範囲で設定する。実施形態１では、竹炭の粒子の含有量を55重量%とし、アルミニウム合金の粒子の含有量を45重量%とする。次に、混合粉にパラフィンワックスを加え、これを摂氏120度で加熱してパラフィンを溶解させてから撹拌することにより、ペースト状の混合物が得られる。 In the following, of the method for manufacturing the piston 1, the part related to the formation of the low thermal conductive layer 3 and the sealing layer 4 will be described. The method for manufacturing the piston 1 includes a mixed powder preparation step, a sintering step, a heat treatment step, and a sealing treatment step.
(Mixed powder preparation process)
The mixed powder preparation step is a step of preparing a mixed powder that becomes the low thermal conductive layer 3 by uniformly mixing the particles of charcoal and the particles of the metal binder. Bamboo charcoal particles (15 μm) are used as the charcoal particles, and aluminum alloy (A5083) particles (20 μm) are used as the metal binder particles. In addition to A5083, by mixing a powder of a low melting point aluminum alloy such as a powder of Al-Si alloy or a powder of Al-Mg alloy, the sintering of the mixed powder in the sintering step can be promoted. The content of bamboo charcoal particles in the mixed powder is set in the range of 25% by weight or more and 65% by weight or less. In the first embodiment, the content of bamboo charcoal particles is 55% by weight, and the content of aluminum alloy particles is 45% by weight. Next, paraffin wax is added to the mixed powder, and the mixture is heated at 120° C. to dissolve the paraffin and then stirred to obtain a paste-like mixture.
　（焼結工程）
  焼結工程は、混合分準備工程後、ピストン本体1aとなるピストン基材および混合物を放電プラズマ焼結によって焼結する工程である。図４は、実施形態１の焼結工程の態様を示す模式図である。まず、図４(a)に示すように、ピストン基材11をカーボン製の拘束金具12内に収容し、円盤状に成形した混合物13を、ピストン基材11の冠面2に載せる。混合物13を冠面2に塗布してもよい。続いて、上方から冠面2の形状に沿う端面形状を有するカーボン製の上型電極14で下方に加圧する（図４(b)）。これにより、冠面2と上型電極14との間に必要量の混合物13を均一に配置できる。次に、上型電極14の上方におよび拘束金具12の下方に配置された図外の上部電極および下部電極に対し、電源からパルス電圧（電流）を1分程度印加する。これにより、冠面2に焼結体15が焼結される（図４(c)）。 (Sintering process)
The sintering step is a step of sintering the piston base material to be the piston body 1a and the mixture by spark plasma sintering after the mixed component preparation step. FIG. 4 is a schematic diagram showing an aspect of the sintering step of the first embodiment. First, as shown in FIG. 4( a ), the piston base material 11 is housed in a carbon-made restraining metal fitting 12, and a disc-shaped mixture 13 is placed on the crown surface 2 of the piston base material 11. The mixture 13 may be applied to the crown surface 2. Subsequently, the upper electrode 14 made of carbon having an end surface shape that follows the shape of the crown surface 2 is pressed downward from above (FIG. 4(b)). Thereby, the required amount of the mixture 13 can be uniformly arranged between the crown surface 2 and the upper electrode 14. Next, a pulse voltage (current) is applied from the power source to the upper and lower electrodes (not shown) arranged above the upper mold electrode 14 and below the restraint fitting 12 for about 1 minute. As a result, the sintered body 15 is sintered on the crown surface 2 (FIG. 4(c)).
　図５は、放電プラズマ焼結前の混合粉の状態を示す模式図である。混合物13は竹炭の粒子16およびアルミニウム合金の粒子17を含み、竹炭の粒子16は、混合物13の上面と下面を繋ぐように混合物13内に分布しているため、上型電極14とピストン基材11とは竹炭の粒子16を介して電気的に接続した状態である。よって、パルス電圧の印加によるアルミニウム合金の粒子の発熱や粒子間に発生する放電プラズマエネルギー等により、混合物13はピストン基材11の上面に焼結され、図６に示すような竹炭の粒子16を含む焼結体15が得られる。この焼結体15が低熱伝導層3となる。なお、焼結体15において、竹炭の粒子16の周囲には、微小な隙間（空隙）16aが多数形成されている。 FIG. 5 is a schematic diagram showing the state of the mixed powder before the spark plasma sintering. The mixture 13 includes bamboo charcoal particles 16 and aluminum alloy particles 17, and since the bamboo charcoal particles 16 are distributed in the mixture 13 so as to connect the upper surface and the lower surface of the mixture 13, the upper electrode 14 and the piston base material. 11 is a state of being electrically connected through particles 16 of bamboo charcoal. Therefore, the mixture 13 is sintered on the upper surface of the piston base material 11 due to the heat generation of the aluminum alloy particles due to the application of the pulse voltage, the discharge plasma energy generated between the particles, etc., and the bamboo charcoal particles 16 as shown in FIG. A sintered body 15 containing is obtained. This sintered body 15 becomes the low thermal conductive layer 3. In the sintered body 15, a large number of minute gaps (voids) 16a are formed around the particles 16 of bamboo charcoal.
　（熱処理工程）
  熱処理工程は、焼結工程後、酸素を含む気体中で、ピストン基材11を所定温度で加熱する工程である。実施形態１では、熱処理工程として、T6処理またはT7処理を行う。T6処理は、溶体化処理後焼入れし、人工時効処理を行う処理であり、高強度が得られる。T7処理は、T6処理と同様であるが、人工時効処理を若干高温または長時間行い、過時効状態とする処理であり、機械的性質（寸法精度等）を向上できる。溶体化処理では、大気中で基材11を摂氏400度以上かつ摂氏600度以下、好ましくは摂氏480度以上かつ540度以下の温度で1～1.5時間程度加熱した後、水または温水に漬けて急冷させる。実施形態１では、摂氏510度で1時間程度加熱する。この溶体化処理により、竹炭の粒子16が燃焼してCOまたはCO2となり体積が著しく減少する（例えば、摂氏500度で1.5時間大気加熱した場合、竹炭の粒子16の重量は93%減少する。）ため、低熱伝導層3には、竹炭の粒子16が消失した箇所に、空隙部6が形成される。竹炭の粒子16の燃焼により形成された各空隙部6のうち、互いに隣接する空隙部6,6同士は連結している。なお、熱処理工程によって燃焼した竹炭の粒子16の一部は、図３に示したように、空隙部6内に残留する。 (Heat treatment process)
The heat treatment step is a step of heating the piston base material 11 at a predetermined temperature in a gas containing oxygen after the sintering step. In the first embodiment, T6 treatment or T7 treatment is performed as the heat treatment step. The T6 treatment is a solution treatment followed by quenching and artificial aging treatment, and high strength is obtained. The T7 treatment is the same as the T6 treatment, but it is a treatment in which the artificial aging treatment is carried out at a slightly high temperature or for a long time to make it overaged, and the mechanical properties (dimensional accuracy etc.) can be improved. In the solution treatment, the base material 11 is heated in the air at a temperature of 400° C. or higher and 600° C. or lower, preferably 480° C. or higher and 540° C. or lower for about 1 to 1.5 hours, and then immersed in water or warm water. Quench quickly. In the first embodiment, heating is performed at 510 degrees Celsius for about 1 hour. By this solution treatment, the particles 16 of bamboo charcoal are burned to form CO or CO2, and the volume is significantly reduced (for example, when the particles 16 of bamboo charcoal are heated to the atmosphere for 1.5 hours, the weight of the particles 16 of bamboo charcoal is reduced 93%). Therefore, voids 6 are formed in the low thermal conductive layer 3 at the locations where the bamboo charcoal particles 16 have disappeared. Among the voids 6 formed by burning the bamboo charcoal particles 16, the voids 6 and 6 adjacent to each other are connected to each other. It should be noted that some of the bamboo charcoal particles 16 burned in the heat treatment step remain in the voids 6 as shown in FIG.
　（封孔処理工程）
  封孔処理工程は、熱処理工程後、低熱伝導層3の上面に封孔処理を行う工程である。実施形態１では、封孔処理として、低熱伝導層3の上面に耐熱樹脂またはポリシラザンを塗布する。封孔処理により、低熱伝導層3の表面に封孔層4が形成される。なお、封孔処理は低熱伝導層3の上面のみに行い、低熱伝導層3の側面（外周面）には封孔処理を行わない。よって、低熱伝導層3の外周に位置する空隙部6は、大気開放された状態に維持される。 (Sealing process)
The sealing treatment step is a step of performing a sealing treatment on the upper surface of the low thermal conductive layer 3 after the heat treatment step. In the first embodiment, as the sealing treatment, a heat resistant resin or polysilazane is applied to the upper surface of the low thermal conductive layer 3. By the sealing treatment, the sealing layer 4 is formed on the surface of the low thermal conductive layer 3. The sealing treatment is performed only on the upper surface of the low thermal conductive layer 3, and the side surface (outer peripheral surface) of the low thermal conductive layer 3 is not subjected to the sealing treatment. Therefore, the void portion 6 located on the outer periphery of the low thermal conductive layer 3 is maintained in a state of being open to the atmosphere.
　次に、実施形態１の作用効果を説明する。
  実施形態１のピストン1は、空隙部6と、炭7と、金属バインダ5とを有する低熱伝導層3を備える。低熱伝導層3は、燃焼室からピストン本体1aへの熱伝導性を低めるための構造であり、燃焼室とピストン本体1aとの間にあって断熱層として機能する。低熱伝導層3は、燃焼室内のガスからピストンヘッド（ピストン本体1a）への熱伝達を低下させ、混合気の熱がピストン本体1aに奪われるのを抑制する。よって、エンジンの燃焼効率の低下（冷却損失）を抑制し、エンジンの熱効率の向上を図れる。なお、空隙部6に残留する炭7は多孔性を有するものであるため、空隙部6による断熱性能を阻害しない。 Next, the function and effect of the first embodiment will be described.
The piston 1 according to the first embodiment includes a low thermal conductive layer 3 having a void portion 6, charcoal 7, and a metal binder 5. The low heat conduction layer 3 has a structure for reducing heat conductivity from the combustion chamber to the piston body 1a, and functions as a heat insulating layer between the combustion chamber and the piston body 1a. The low heat conduction layer 3 reduces the heat transfer from the gas in the combustion chamber to the piston head (piston body 1a), and suppresses the heat of the air-fuel mixture from being taken by the piston body 1a. Therefore, it is possible to suppress a decrease in the combustion efficiency of the engine (cooling loss) and improve the thermal efficiency of the engine. Since the charcoal 7 remaining in the voids 6 is porous, it does not impair the heat insulating performance of the voids 6.
　ピストン1は、低熱伝導層3の上面を封孔する封孔層4を備える。低熱伝導層3は多数の空隙部6を有する多孔体であるため、上面を封孔層4で覆うことにより、燃焼室から低熱伝導層3の内部への混合気の侵入を防止できる。この結果、低熱伝導層3の熱疲労を抑制できるため、耐久性の向上を図れる。
  封孔層4は、耐熱樹脂またはポリシラザンにより形成されている。耐熱樹脂およびポリシラザンは高耐熱性を有するため、低熱伝導層3の熱疲労を抑制できる。
  空隙部6の一部は、大気開放されている。よって、ピストン1の加熱冷却に伴い、空隙部6内の空気は膨張および収縮したとしても、大気開放された空隙部6を介して空気を排出または吸入できるため、低熱伝導層3の変形および破損を抑制できる。 The piston 1 includes a sealing layer 4 that seals the upper surface of the low thermal conductive layer 3. Since the low thermal conductive layer 3 is a porous body having a large number of voids 6, by covering the upper surface with the sealing layer 4, it is possible to prevent the mixture from entering the low thermal conductive layer 3 from the combustion chamber. As a result, thermal fatigue of the low thermal conductive layer 3 can be suppressed, so that durability can be improved.
The sealing layer 4 is made of heat resistant resin or polysilazane. Since the heat-resistant resin and polysilazane have high heat resistance, thermal fatigue of the low heat conductive layer 3 can be suppressed.
Part of the void portion 6 is open to the atmosphere. Therefore, even if the air in the void 6 expands and contracts due to the heating and cooling of the piston 1, the air can be discharged or taken in through the void 6 open to the atmosphere, so that the low thermal conductive layer 3 is deformed and damaged. Can be suppressed.
　竹炭の粒子16は、ピストン基材11の素材であるアルミニウム合金(A5083)の融点（摂氏600度超）よりも低い温度（摂氏400度）から燃焼を開始する。よって、溶体化処理によってピストン基材11を溶かすことなく竹炭の粒子16を燃焼させられる。これにより、焼結工程後に熱処理を行うことで竹炭の粒子16が消失し、低熱伝導層3に多数の空隙部6が形成される。空隙部6の熱伝導度(W/mK)は竹炭の粒子16の熱伝導度よりも低いため、低熱伝導層3における熱伝導性をより低くできる。なお、一般的にピストンの素材として用いられるアルミニウム合金の融点は、摂氏600度以上であるため、炭7は、摂氏600度以下で燃焼を開始する特性であればよい。 -Bamboo charcoal particles 16 start burning at a temperature (400 degrees Celsius) lower than the melting point (more than 600 degrees Celsius) of the aluminum alloy (A5083) that is the material of the piston base material 11. Therefore, the bamboo charcoal particles 16 can be burned without melting the piston base material 11 by the solution treatment. As a result, by performing heat treatment after the sintering step, the particles 16 of bamboo charcoal disappear, and a large number of voids 6 are formed in the low thermal conductive layer 3. Since the thermal conductivity (W/mK) of the void portion 6 is lower than that of the bamboo charcoal particles 16, the thermal conductivity of the low thermal conductive layer 3 can be further lowered. Since the melting point of an aluminum alloy generally used as a material for pistons is 600 degrees Celsius or higher, the charcoal 7 may have a characteristic of starting combustion at 600 degrees Celsius or lower.
　空隙部6、および金属バインダ5は、低熱伝導層3内で均質に分布する。つまり、低熱伝導層3内で空隙部6が均質に分布することにより、冠面2の位置にかかわらず、均一な断熱効果が得られる。
  ピストン1および金属バインダ5は、アルミニウム合金により形成されている。ピストン1と金属バインダ5を同じ金属とすることにより、冠面2と低熱伝導層3との界面で強固な固相接合部が形成され、両者の密着性を確保できるため、耐久性に優れた低熱伝導層3を実現できる。 The voids 6 and the metal binder 5 are uniformly distributed in the low thermal conductive layer 3. That is, since the voids 6 are uniformly distributed in the low heat conductive layer 3, a uniform heat insulating effect can be obtained regardless of the position of the crown surface 2.
The piston 1 and the metal binder 5 are made of an aluminum alloy. By using the same metal for the piston 1 and the metal binder 5, a strong solid phase joint is formed at the interface between the crown surface 2 and the low thermal conductive layer 3, and the adhesion between the two can be secured, resulting in excellent durability. The low heat conduction layer 3 can be realized.
　実施形態１におけるピストン1の製造方法は、竹炭の粒子16とアルミニウム合金の粒子17とを含む混合物13を準備する混合粉準備工程と、混合物13およびピストン基材11間を通電して混合物13を冠面2上に焼結する焼結工程と、を備える。竹炭の粒子16は導体であるため、混合物13およびピストン基材11間が竹炭の粒子16を介して通電する。よって、アルミニウム合金の粒子17の表面が酸化により絶縁化している場合であっても、放電プラズマ焼結が可能である。よって、放電プラズマ焼結前に混合物13を加熱溶融させる工程が不要であるため、従来のピストンの製造方法と比べて、低熱伝導層3の形成を容易化できる。 The method for manufacturing the piston 1 according to the first embodiment includes a powder mixture preparation step of preparing a mixture 13 containing particles 16 of bamboo charcoal and particles 17 of an aluminum alloy, and a mixture 13 and a piston base material 11 are energized to form the mixture 13. A sintering step of sintering on the crown surface (2). Since the particles 16 of bamboo charcoal are conductors, the mixture 13 and the piston base material 11 are energized via the particles 16 of bamboo charcoal. Therefore, even if the surfaces of the aluminum alloy particles 17 are insulated by oxidation, spark plasma sintering is possible. Therefore, the step of heating and melting the mixture 13 before the spark plasma sintering is unnecessary, so that the formation of the low thermal conductive layer 3 can be facilitated as compared with the conventional piston manufacturing method.
　実施形態１におけるピストン1の製造方法は、焼結工程後、酸素を含む気体中で、ピストン基材11を所定温度で加熱する熱処理工程を備える。熱処理工程により、竹炭の粒子16が燃焼して消失した箇所に多数の空隙部6が形成されることで、低熱伝導層3の空孔率が増大する。つまり、空間保持材として炭を用い、炭とアルミニウム合金とを焼結して、その後炭を消失させるため、空間保持材としてシリカを用いた従来の製造方法と比べて、空間保持材の消失分だけ空隙部を拡大できる。この結果、低熱伝導層3における熱伝導性をより低くでき、断熱性能を向上できる。 The method for manufacturing the piston 1 according to the first embodiment includes a heat treatment step of heating the piston base material 11 at a predetermined temperature in a gas containing oxygen after the sintering step. By the heat treatment step, a large number of voids 6 are formed at the locations where the bamboo charcoal particles 16 have burned and disappeared, so that the porosity of the low thermal conductive layer 3 increases. In other words, since charcoal is used as the space retaining material, the charcoal and the aluminum alloy are sintered, and then the charcoal is eliminated, compared with the conventional manufacturing method using silica as the space retaining material, the amount of disappearance of the space retaining material Only the void can be enlarged. As a result, the thermal conductivity of the low thermal conductive layer 3 can be further lowered, and the heat insulating performance can be improved.
　熱処理工程において、ピストン基材11を加熱する温度を、摂氏400度以上かつ摂氏600度以下の温度とした。これにより、アルミニウム合金で形成されたピストン基材11を溶かすことなく、竹炭の粒子16を燃焼させて空隙部6を形成できる。
  熱処理工程では、溶体化処理を行う。溶体化処理はピストンを製造する際に一般的に行われる熱処理であるから、既存の熱処理を利用して竹炭の粒子16を燃焼させ、空隙部6を形成できる。つまり、竹炭の粒子16を燃焼させるための新たな工程の追加が不要である。 In the heat treatment step, the temperature for heating the piston base material 11 was set to a temperature of 400 degrees Celsius or higher and 600 degrees Celsius or lower. As a result, the voids 6 can be formed by burning the particles 16 of bamboo charcoal without melting the piston base material 11 formed of an aluminum alloy.
In the heat treatment step, solution treatment is performed. Since the solution heat treatment is a heat treatment that is generally performed when manufacturing a piston, the voids 6 can be formed by burning the bamboo charcoal particles 16 using an existing heat treatment. That is, it is unnecessary to add a new process for burning the bamboo charcoal particles 16.
　混合粉準備工程は、竹炭の粒子16とアルミニウム合金の粒子17とを混合し、焼結工程は、放電プラズマ焼結を行う。よって、アルミニウム合金の粒子17が酸化して絶縁体となっている場合であっても、導体である竹炭の粒子16を介して放電プラズマ焼結が可能である。放電プラズマ焼結は、電気炉などの雰囲気加熱と比べて急速昇温・冷却が可能であるため、焼結時間の大幅な短縮が可能である。
  混合粉準備工程は、竹炭の粒子16とアルミニウム合金の粒子17とを均質に混合する。よって、低熱伝導層3内で空隙部6が均質に分布するため、均一な断熱効果を持つ低熱伝導層3が得られる。
  混合粉準備工程は、混合粉にパラフィンワックスを加える。よって、加熱によりパラフィンワックスを溶解させることでペースト状の混合物13が得られるため、混合粉の冠面2への設置を容易化できる。
  竹炭の粒子16は、焼結工程において、上型電極14とピストン基材11とが竹炭の粒子16を介して電気的に接続されるように混合物13中に分布する。よって、導体である竹炭の粒子16を介して放電プラズマ焼結が可能である。 In the mixed powder preparation step, bamboo charcoal particles 16 and aluminum alloy particles 17 are mixed, and in the sintering step, spark plasma sintering is performed. Therefore, even when the particles 17 of the aluminum alloy are oxidized to be an insulator, the spark plasma sintering can be performed through the particles 16 of the bamboo charcoal which is the conductor. In spark plasma sintering, rapid heating and cooling can be performed compared to atmospheric heating in an electric furnace or the like, so that the sintering time can be greatly shortened.
In the mixed powder preparing step, bamboo charcoal particles 16 and aluminum alloy particles 17 are homogeneously mixed. Therefore, since the voids 6 are uniformly distributed in the low heat conductive layer 3, the low heat conductive layer 3 having a uniform heat insulating effect can be obtained.
In the mixed powder preparation step, paraffin wax is added to the mixed powder. Therefore, since the paste-like mixture 13 is obtained by melting the paraffin wax by heating, installation of the mixed powder on the crown surface 2 can be facilitated.
The bamboo charcoal particles 16 are distributed in the mixture 13 such that the upper electrode 14 and the piston base material 11 are electrically connected via the bamboo charcoal particles 16 in the sintering process. Therefore, spark plasma sintering is possible through the particles 16 of bamboo charcoal, which is a conductor.
　混合粉における竹炭の粒子16の含有量を25重量%以上かつ65重量%以下とした。発明者は、ピストン1の製造に先立ち、竹炭の粒子とアルミニウム合金の粒子を含む混合粉をアルミニウム合金製の基材に放電プラズマ焼結し、その後所定温度で大気加熱させる実験を行った。図７は、放電プラズマ焼結実験の態様を示す模式図である。まず、アルミニウム合金(AC8AまたはA4032)により形成された基材18の上面に鉛直方向に直径30mmの貫通穴19aを有する厚さ3mmのセラミックシート19を設置する。続いて、貫通穴19aに竹炭の粒子(15μm)とアルミニウム合金(A5083)の粒子(20μm)とを均質に混合した混合粉20を高さ1mmとなるように均一に敷き詰める。次に、基材18を下部カーボン電極21の上に設置し、直径30mmの上部カーボン電極22をセラミックシート19の貫通穴19aに押し込み、両電極21,22で基材18および混合粉20を上下方向に加圧した状態で、電源からパルス電圧（電流）を1分程度印加する。続いて、放電プラズマ焼結実験により混合粉が焼結された基材を、摂氏510度で1時間大気加熱する熱処理実験を行った。 The content of bamboo charcoal particles 16 in the mixed powder is set to 25% by weight or more and 65% by weight or less. Prior to the manufacture of the piston 1, the inventor conducted an experiment in which a mixed powder containing bamboo charcoal particles and aluminum alloy particles was spark plasma-sintered on a base material made of an aluminum alloy, and then heated in the atmosphere at a predetermined temperature. FIG. 7 is a schematic diagram showing an aspect of a spark plasma sintering experiment. First, a 3 mm-thick ceramic sheet 19 having a through hole 19a with a diameter of 30 mm in the vertical direction is placed on the upper surface of a base material 18 formed of an aluminum alloy (AC8A or A4032). Then, a mixed powder 20 in which bamboo charcoal particles (15 μm) and aluminum alloy (A5083) particles (20 μm) are homogeneously mixed is uniformly spread in the through holes 19a so as to have a height of 1 mm. Next, the base material 18 is placed on the lower carbon electrode 21, the upper carbon electrode 22 having a diameter of 30 mm is pushed into the through hole 19a of the ceramic sheet 19, and the base material 18 and the mixed powder 20 are vertically moved by both electrodes 21 and 22. Applying a pulse voltage (current) from the power supply for about 1 minute with the pressure applied in the direction. Subsequently, a heat treatment experiment was performed in which the base material in which the mixed powder was sintered by the discharge plasma sintering experiment was heated in the atmosphere at 510 degrees Celsius for 1 hour.
　上記放電プラズマ焼結実験および熱処理実験において、混合粉20における竹炭の粒子の含有量を変化させたときの実験結果（導通の有無、焼結体の形成の可否、空孔率および熱伝導度を図８に示す。図８に示すように、竹炭の粒子の含有量が25重量%未満では導通が得られず、竹炭の粒子の含有量が25重量%以上で導通が得られ、竹炭の粒子の含有量が増えるほど空孔率が上昇すると共に、熱伝導度が低下した。また、焼結後に熱処理を行うと、さらなる空孔率の上昇および熱伝導度の低下がみられた。なお、竹炭の粒子の含有量が75重量%を超えると、アルミニウム合金の粒子の含有量が乏しいため、焼結体を形成できなかった。つまり、アルミニウム合金の粒子の含有量が少ないほど、金属バインダ5の焼結強度が低下することがわかった。よって、上記の実験結果から、混合粉における竹炭の粒子16の含有量を25重量%以上かつ65重量%以下とすることにより、放電プラズマ焼結によって低熱伝導層3を形成できることが明らかとなった。さらに、混合粉において、アルミニウム合金の粒子17の含有量を45重量%とし、竹炭の粒子17の含有量を55重量%とすることにより、放電プラズマ焼結時における導電性、低熱伝導層3の断熱性能および金属バインダ5の強度のバランスが最適化できることがわかった。 In the above-mentioned spark plasma sintering experiment and heat treatment experiment, the experimental results when the content of the particles of bamboo charcoal in the mixed powder 20 was changed (presence or absence of conduction, presence or absence of formation of sintered body, porosity and thermal conductivity As shown in Fig. 8, when the content of particles of bamboo charcoal is less than 25% by weight, conduction is not obtained, and when the content of particles of bamboo charcoal is 25% by weight or more, conduction is obtained. The porosity was increased and the thermal conductivity was decreased as the content of was increased, and when the heat treatment was performed after sintering, the porosity was further increased and the thermal conductivity was decreased. When the content of particles of bamboo charcoal exceeded 75% by weight, the sintered body could not be formed because the content of particles of aluminum alloy was insufficient. From the above experimental results, it was found that the content of the bamboo charcoal particles 16 in the mixed powder was set to 25% by weight or more and 65% by weight or less by spark plasma sintering. It has been clarified that the low thermal conductive layer 3 can be formed.Furthermore, by setting the content of the aluminum alloy particles 17 to 45% by weight and the content of the bamboo charcoal particles 17 to 55% by weight in the mixed powder, discharge It was found that the balance of the conductivity, the heat insulating performance of the low thermal conductive layer 3 and the strength of the metal binder 5 at the time of plasma sintering can be optimized.
　冠面2上に焼結された焼結体15の上面に封孔処理を行う封孔処理工程を備える。よって、低熱伝導層3の内部への混合気の侵入を防止する封孔層4を形成でき、低熱伝導層3の熱疲労を抑制できる。
  封孔処理工程は、熱処理工程後、冠面2上に焼結された焼結体15の上面に耐熱樹脂またはポリシラザンを塗布する。よって、簡易な方法で封孔層4を形成できる。 A sealing treatment step of performing a sealing treatment on the upper surface of the sintered body 15 sintered on the crown surface 2 is provided. Therefore, the sealing layer 4 for preventing the mixture from entering the low thermal conductive layer 3 can be formed, and the thermal fatigue of the low thermal conductive layer 3 can be suppressed.
In the sealing treatment step, a heat resistant resin or polysilazane is applied to the upper surface of the sintered body 15 sintered on the crown surface 2 after the heat treatment step. Therefore, the sealing layer 4 can be formed by a simple method.
　〔実施形態２〕
  実施形態２の基本的の構成は実施形態１と同じであるため、実施形態１と相違する部分のみ説明する。
  （混合粉準備工程）
  図９は、実施形態２の混合粉準備工程の態様を示す模式図である。
  実施形態１と同様に、炭の粒子16とアルミニウム合金の粒子17との混合物にパラフィンワックスを加えて加熱後に撹拌し、薄く延ばして円盤状のパラフィンシート23を成形する。続いて、厚さ10～50μmのアルミ箔24を、パラフィンシート23の上面に重ねる。 [Embodiment 2]
Since the basic configuration of the second embodiment is the same as that of the first embodiment, only the parts different from the first embodiment will be described.
(Mixed powder preparation process)
FIG. 9: is a schematic diagram which shows the aspect of the mixed powder preparation process of Embodiment 2.
As in the first embodiment, paraffin wax is added to a mixture of particles 16 of charcoal and particles 17 of aluminum alloy, heated and stirred, and thinly spread to form a disc-shaped paraffin sheet 23. Then, an aluminum foil 24 having a thickness of 10 to 50 μm is laid on the upper surface of the paraffin sheet 23.
　（焼結工程）
  図１０は、実施形態２の焼結工程の態様を示す模式図である。
  まず、図１０(a)に示すように、アルミ箔24を上方に向けた状態で、パラフィンシート23を冠面2の上に載せる。このとき、予めピストン基材11および上型電極14は摂氏120度に加熱しておく。なお、冠面2の上にパラフィンシート23を載せた後、ピストン基材11および上型電極14を加熱してもよい。続いて、上型電極14および拘束金具12で上下方向に加圧する（図１０(b)）。次に、上部電極および下部電極に対し、電源からパルス電圧を1分程度印加する。これにより、図１０(c)に示すように、冠面2に焼結体15が焼結されると同時に、焼結体15の表面に封孔層4が形成される。つまり、実施形態２では、焼結工程と同時に封孔処理が同時に行われる。 (Sintering process)
FIG. 10: is a schematic diagram which shows the aspect of the sintering process of Embodiment 2.
First, as shown in FIG. 10A, the paraffin sheet 23 is placed on the crown surface 2 with the aluminum foil 24 facing upward. At this time, the piston base material 11 and the upper mold electrode 14 are heated to 120 degrees Celsius in advance. The piston base material 11 and the upper electrode 14 may be heated after the paraffin sheet 23 is placed on the crown surface 2. Subsequently, pressure is applied in the vertical direction by the upper mold electrode 14 and the restraint fitting 12 (FIG. 10(b)). Next, a pulse voltage is applied to the upper electrode and the lower electrode from the power source for about 1 minute. As a result, as shown in FIG. 10C, the sintered body 15 is sintered on the crown surface 2 and, at the same time, the sealing layer 4 is formed on the surface of the sintered body 15. That is, in the second embodiment, the sealing process is performed simultaneously with the sintering process.
　次に、実施形態２の作用効果を説明する。
  封孔層4は、アルミニウムにより形成されている。よって、封孔層4をピストン1および金属バインダ5と同じ金属とすることにより、焼結工程で封孔層4を形成できる。
  封孔処理工程は、混合粉準備工程後、パラフィンシート23を冠面2との間で挟み込むようにアルミニウム層をパラフィンシート23の上面に設置する。よって、焼結工程と同時に封孔処理が行えるため、封孔処理を焼結工程の後工程で行う場合と比べて、ピストン1の製造コストを低減できる。
  アルミニウム層は、アルミ箔による層である。アルミ箔は厚さが均一であるため、均一な厚さの封孔層4が得られると共に、封孔層4の厚さの管理を容易化できる。また、冠面2を隙間なく(100%)封孔できる。 Next, the function and effect of the second embodiment will be described.
The sealing layer 4 is made of aluminum. Therefore, by using the same metal as the piston 1 and the metal binder 5 for the sealing layer 4, the sealing layer 4 can be formed in the sintering step.
In the sealing treatment step, after the mixed powder preparation step, the aluminum layer is placed on the upper surface of the paraffin sheet 23 so that the paraffin sheet 23 is sandwiched between the crown surface 2 and the paraffin sheet 23. Therefore, the sealing process can be performed at the same time as the sintering process, so that the manufacturing cost of the piston 1 can be reduced as compared with the case where the sealing process is performed in the post process of the sintering process.
The aluminum layer is a layer made of aluminum foil. Since the aluminum foil has a uniform thickness, the sealing layer 4 having a uniform thickness can be obtained, and the control of the thickness of the sealing layer 4 can be facilitated. Further, the crown surface 2 can be sealed without any gap (100%).
　〔実施形態３〕
  実施形態３の基本的な構成は実施形態２と同じであるため、実施形態２と相違する部分のみ説明する。
  （混合粉準備工程）
   図１１は、実施形態３の混合粉準備工程の態様を示す模式図である。
  まず、実施形態２と同様に、炭の粒子16とアルミニウム合金の粒子17との混合物にパラフィンワックスを加えて加熱後に撹拌し、薄く延ばして円盤状のパラフィンシート23を形成する（図９参照）。続いて、図１１(a)に示すように、上型電極14を摂氏120度に加熱し、その表面を溶融したパラフィン25に浸してパラフィン25を付着させる。次に、上型電極14の表面にアルミニウム合金(Al-Si合金、準アルミニウム)の粒子26を振り掛けてパラフィン25に付着させる（図１１(b)）。最後に、上型電極14の表面からパラフィン25に付着していない余分なアルミニウム合金の粒子26を振り落とす（図１１(c)）。これにより、上型電極14の表面は均一な厚みのアルミニウム層27が形成される。 [Embodiment 3]
Since the basic configuration of the third embodiment is the same as that of the second embodiment, only the parts different from the second embodiment will be described.
(Mixed powder preparation process)
FIG. 11 is a schematic diagram showing an aspect of the mixed powder preparation step of the third embodiment.
First, as in the second embodiment, paraffin wax is added to a mixture of charcoal particles 16 and aluminum alloy particles 17, heated and stirred, and thinly spread to form a disc-shaped paraffin sheet 23 (see FIG. 9). .. Subsequently, as shown in FIG. 11A, the upper electrode 14 is heated to 120 degrees Celsius, and the surface thereof is immersed in the melted paraffin 25 to adhere the paraffin 25. Next, particles 26 of an aluminum alloy (Al-Si alloy, quasi-aluminum) are sprinkled on the surface of the upper mold electrode 14 to adhere to the paraffin 25 (FIG. 11(b)). Finally, excess aluminum alloy particles 26 not attached to the paraffin 25 are shaken off from the surface of the upper electrode 14 (FIG. 11(c)). As a result, the aluminum layer 27 having a uniform thickness is formed on the surface of the upper mold electrode 14.
　（焼結工程）
  図１２は、実施形態３の焼結工程の態様を示す模式図である。
  まず、図１２(a)に示すように、パラフィンシート23を冠面2の上に載せる。続いて、上型電極14および拘束金具12で上下方向に加圧する（図１２(b)）。次に、上部電極および下部電極に対し、電源からパルス電圧を1分程度印加する。これにより、図１２(c)に示すように、冠面2に焼結体15が焼結されると同時に、焼結体15の表面に封孔層4が形成される。
  次に、実施形態３の作用効果を説明する。
  アルミニウム層27は、アルミニウムの粒子による層である。よって、アルミニウム層27をアルミ箔とした場合と比べて、封孔層4を厚くできるため、封孔層4の強度を向上できる。また、冠面2をほぼ隙間なく封孔できる。 (Sintering process)
FIG. 12 is a schematic diagram showing an aspect of the sintering step of the third embodiment.
First, as shown in FIG. 12A, the paraffin sheet 23 is placed on the crown surface 2. Subsequently, pressure is applied in the vertical direction by the upper mold electrode 14 and the restraint fitting 12 (FIG. 12(b)). Next, a pulse voltage is applied to the upper electrode and the lower electrode from the power source for about 1 minute. As a result, as shown in FIG. 12C, the sintered body 15 is sintered on the crown surface 2 and, at the same time, the sealing layer 4 is formed on the surface of the sintered body 15.
Next, the function and effect of the third embodiment will be described.
The aluminum layer 27 is a layer made of aluminum particles. Therefore, compared with the case where the aluminum layer 27 is made of aluminum foil, the sealing layer 4 can be made thicker, so that the strength of the sealing layer 4 can be improved. Further, the crown surface 2 can be sealed with almost no space.
　〔他の実施形態〕
  以上、本発明を実施するための実施形態を説明したが、本発明の具体的な構成は実施形態の構成に限定されるものではなく、発明の要旨を逸脱しない範囲の設計変更等があっても本発明に含まれる。
  低熱伝導層は、冠面の一部を覆う形状としてもよい。また、低熱伝導層の被膜厚さは不均一でもよい。 [Other Embodiments]
The embodiment for carrying out the present invention has been described above, but the specific configuration of the present invention is not limited to the configuration of the embodiment, and there are design changes and the like within the scope not departing from the gist of the invention. Also included in the present invention.
The low thermal conductive layer may have a shape that covers a part of the crown surface. Further, the film thickness of the low thermal conductive layer may be non-uniform.
　金属バインダとしては、アルミニウム合金だけでなく、チタン合金またはニッケル合金であってもよい。チタン合金、ニッケル合金は、どちらも焼結ができると共に、基材のアルミニウム合金と接合可能な材料であり、アルミニウム合金と熱膨張係数が近く、アルミニウム合金よりも低熱伝導という利点があり、低熱伝導層を形成するための金属バインダとして適している。 The metal binder may be not only an aluminum alloy but also a titanium alloy or a nickel alloy. Titanium alloys and nickel alloys are both materials that can be sintered and can be joined to the aluminum alloy of the base material, and have a coefficient of thermal expansion close to that of the aluminum alloy, and have the advantage of lower thermal conductivity than the aluminum alloy. It is suitable as a metal binder for forming layers.
　以上説明した実施形態から把握し得る技術的思想について、以下に記載する。
  内燃機関のピストンは、その一つの態様において、内燃機関のピストンであって、前記内燃機関の燃焼室に面する冠面と、前記冠面上に設けられた低熱伝導層であって、空隙部と、炭と、金属バインダと、を有する前記低熱伝導層と、を備える。
  より好ましい態様では、上記態様において、前記低熱伝導層の表面を封孔する封孔層を備える。
  別の好ましい態様では、上記態様のいずれかにおいて、前記封孔層は、耐熱樹脂またはポリシラザンにより形成されている。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記封孔層は、アルミニウムにより形成されている。 The technical idea that can be understood from the embodiment described above will be described below.
A piston of an internal combustion engine, in one aspect thereof, is a piston of an internal combustion engine, comprising a crown surface facing a combustion chamber of the internal combustion engine, a low heat conductive layer provided on the crown surface, and a void portion. And the low thermal conductive layer having charcoal and a metal binder.
In a more preferred aspect, in the above aspect, a sealing layer that seals the surface of the low thermal conductive layer is provided.
In another preferred aspect, in any one of the above aspects, the sealing layer is formed of a heat resistant resin or polysilazane.
In yet another preferred aspect, in any of the above aspects, the sealing layer is formed of aluminum.
　さらに別の好ましい態様では、上記態様のいずれかにおいて、前記空隙部の一部は、大気開放されている。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記炭は、摂氏600度以下で燃焼を開始する特性を有する。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記空隙部、前記炭および前記金属バインダは、前記低熱伝導層内で均質に分布する。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記ピストンおよび前記金属バインダは、アルミニウムにより形成されている。 In yet another preferred aspect, in any of the above aspects, a part of the void portion is open to the atmosphere.
In yet another preferred aspect, in any of the above aspects, the charcoal has the property of initiating combustion at 600 degrees Celsius or less.
In yet another preferred aspect, in any of the above aspects, the voids, the charcoal, and the metal binder are uniformly distributed in the low thermal conductive layer.
In yet another preferred aspect, in any one of the above aspects, the piston and the metal binder are formed of aluminum.
　また、他の観点から、内燃機関のピストンの製造方法は、ある態様において、内燃機関の燃焼室に面する冠面を有するピストンの製造方法であって、炭の粒子と金属バインダの粒子とを含む混合粉を準備する混合粉準備工程と、前記混合粉と前記ピストンのピストン基材との間を通電して前記混合粉を前記冠面上に焼結する焼結工程と、を備える。
  好ましくは、上記態様において、前記焼結工程後、酸素を含む気体中で、前記ピストン基材を所定温度で加熱する熱処理工程を備える。
  別の好ましい態様では、上記態様のいずれかにおいて、前記所定温度は、摂氏400度以上かつ摂氏600度以下である。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記熱処理工程は、溶体化処理を行う。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記混合粉準備工程は、前記炭の粒子と前記金属バインダの粒子とを混合し、前記焼結工程は、放電プラズマ焼結を行う。 From another point of view, a method for manufacturing a piston of an internal combustion engine, in one aspect, is a method of manufacturing a piston having a crown surface facing the combustion chamber of the internal combustion engine, wherein particles of carbon and particles of a metal binder are used. A mixed powder preparation step of preparing a mixed powder containing the powder and a sintering step of energizing the mixed powder and the piston base material of the piston to sinter the mixed powder on the crown surface.
Preferably, in the above aspect, after the sintering step, a heat treatment step of heating the piston base material at a predetermined temperature in a gas containing oxygen is provided.
In another preferred aspect, in any one of the above aspects, the predetermined temperature is 400 degrees Celsius or higher and 600 degrees Celsius or lower.
In yet another preferred aspect, in any of the above aspects, the heat treatment step is a solution treatment.
In yet another preferred aspect, in any one of the above aspects, the mixed powder preparation step mixes the particles of the charcoal and the particles of the metal binder, and the sintering step performs discharge plasma sintering.
　さらに別の好ましい態様では、上記態様のいずれかにおいて、前記混合粉準備工程は、前記炭の粒子と前記金属バインダの粒子とを均質に混合する。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記炭の粒子は、前記焼結工程において、前記放電プラズマの電極と前記ピストン基材とが前記炭の粒子を介して電気的に接続されるように前記混合粉中に分布する。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記混合粉における前記炭の粒子の含有量が25重量%以上かつ65重量%以下である。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記混合粉において、前記金属バインダの粒子の含有量が45重量%であり、前記炭の粒子の含有量が55重量%である。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記混合粉準備工程は、前記混合粉にパラフィンワックスを加える。 In still another preferred aspect, in any one of the above aspects, the mixed powder preparation step uniformly mixes the particles of the charcoal and the particles of the metal binder.
In yet another preferred aspect, in any one of the above aspects, in the charcoal particles, in the sintering step, the discharge plasma electrode and the piston base material are electrically connected to each other via the charcoal particles. So that it is distributed in the mixed powder.
In still another preferred embodiment, in any one of the above embodiments, the content of the particles of the charcoal in the mixed powder is 25% by weight or more and 65% by weight or less.
In still another preferred embodiment, in any of the above embodiments, the content of the metal binder particles in the mixed powder is 45% by weight, and the content of the charcoal particles is 55% by weight.
In still another preferred embodiment, in the mixed powder preparing step according to any one of the above embodiments, paraffin wax is added to the mixed powder.
　さらに別の好ましい態様では、上記態様のいずれかにおいて、前記冠面上に焼結された前記混合粉の表面に封孔処理を行う封孔処理工程を備える。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記封孔処理工程は、前記熱処理工程後、前記冠面上に焼結された前記混合粉の表面に耐熱樹脂またはポリシラザンを塗布する。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記封孔処理工程は、前記混合粉準備工程後、前記混合粉を前記冠面との間で挟み込むようにアルミニウム層を前記混合粉の上に設置する。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記アルミニウム層は、アルミ箔による層である。
  さらに別の好ましい態様では、上記態様のいずれかにおいて、前記アルミニウム層は、アルミニウムの粒子による層である。 In still another preferred aspect, in any one of the above aspects, a sealing treatment step of performing a sealing treatment on the surface of the mixed powder sintered on the crown surface is provided.
In still another preferred aspect, in any of the above aspects, in the sealing treatment step, after the heat treatment step, a heat resistant resin or polysilazane is applied to the surface of the mixed powder sintered on the crown surface.
In still another preferred aspect, in any one of the above aspects, the sealing treatment step comprises, after the mixed powder preparation step, an aluminum layer on the mixed powder so as to sandwich the mixed powder with the crown surface. To install.
In yet another preferred aspect, in any of the above aspects, the aluminum layer is a layer made of aluminum foil.
In yet another preferred aspect, in any of the above aspects, the aluminum layer is a layer of aluminum particles.
　尚、本発明は上記した実施形態に限定されるものではなく、様々な変形例が含まれる。例えば、上記した実施形態は本発明を分かりやすく説明するために詳細に説明したものであり、必ずしも説明した全ての構成を備えるものに限定されるものではない。また、ある実施形態の構成の一部を他の実施形態の構成に置き換えることが可能であり、また、ある実施形態の構成に他の実施形態の構成を加えることも可能である。また、各実施形態の構成の一部について、他の構成の追加・削除・置換をすることが可能である。 It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are included. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add/delete/replace other configurations with respect to a part of the configurations of the respective embodiments.
　本願は、２０１９年２月２０日付出願の日本国特許出願第２０１９－０２７９５０号に基づく優先権を主張する。２０１９年２月２０日付出願の日本国特許出願第２０１９－０２７９５０号の明細書、特許請求の範囲、図面、及び要約書を含む全開示内容は、参照により本願に全体として組み込まれる。 This application claims priority based on Japanese Patent Application No. 2019-027950 filed on February 20, 2019. The entire disclosure of Japanese Patent Application No. 2019-027950 filed on Feb. 20, 2019, including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety.
1　ピストン2　冠面3　低熱伝導層4　封孔層5　金属バインダ6　空隙部7　炭16　竹炭の粒子17　アルミニウム合金の粒子 1 piston 2 crown surface 3 low thermal conductivity layer 4 sealing layer 5 metal binder 6 void 7 charcoal 16 bamboo charcoal particle 17 aluminum alloy particle

Claims (23)

  1. 　内燃機関のピストンであって、
    　前記内燃機関の燃焼室に面する冠面と、
    　前記冠面上に設けられた低熱伝導層であって、空隙部と、炭と、金属バインダと、を有する前記低熱伝導層と、
    　を備える内燃機関のピストン。     A piston of an internal combustion engine,
    A crown surface facing the combustion chamber of the internal combustion engine,
    A low thermal conductive layer provided on the crown surface, the low thermal conductive layer having a void, charcoal, and a metal binder,
    Of the internal combustion engine equipped with.
  2. 　請求項１に記載の内燃機関のピストンであって、
    　前記低熱伝導層の表面を封孔する封孔層を備える内燃機関のピストン。     The piston of the internal combustion engine according to claim 1,
    A piston for an internal combustion engine, comprising a sealing layer for sealing the surface of the low thermal conductive layer.
  3. 　請求項２に記載の内燃機関のピストンであって、
    　前記封孔層は、耐熱樹脂またはポリシラザンにより形成されている内燃機関のピストン。     A piston for an internal combustion engine according to claim 2, wherein
    A piston for an internal combustion engine, wherein the sealing layer is made of a heat resistant resin or polysilazane.
  4. 　請求項２に記載の内燃機関のピストンであって、
    　前記封孔層は、アルミニウムにより形成されている内燃機関のピストン。     A piston for an internal combustion engine according to claim 2, wherein
    The sealing layer is a piston for an internal combustion engine, which is made of aluminum.
  5. 　請求項２に記載の内燃機関のピストンであって、
    　前記空隙部の一部は、大気開放されている内燃機関のピストン。     A piston for an internal combustion engine according to claim 2, wherein
    A part of the void is a piston of an internal combustion engine that is open to the atmosphere.
  6. 　請求項１に記載の内燃機関のピストンであって、
    　前記炭は、摂氏600度以下で燃焼を開始する特性を有する内燃機関のピストン。     The piston of the internal combustion engine according to claim 1,
    The charcoal is a piston of an internal combustion engine having a characteristic of starting combustion at 600 degrees Celsius or less.
  7. 　請求項１に記載の内燃機関のピストンであって、
    　前記空隙部、前記炭および前記金属バインダは、前記低熱伝導層内で均質に分布する内燃機関のピストン。     The piston of the internal combustion engine according to claim 1,
    The piston of the internal combustion engine in which the void portion, the charcoal, and the metal binder are uniformly distributed in the low thermal conductive layer.
  8. 　請求項１に記載の内燃機関のピストンであって、
    　前記ピストンおよび前記金属バインダは、アルミニウムにより形成されている内燃機関のピストン。     The piston of the internal combustion engine according to claim 1,
    The piston and the metal binder are pistons of an internal combustion engine formed of aluminum.
  9. 　内燃機関の燃焼室に面する冠面を有するピストンの製造方法であって、
    　炭の粒子と金属バインダの粒子とを含む混合粉を準備する混合粉準備工程と、
    　前記混合粉と前記ピストンのピストン基材との間を通電して前記混合粉を前記冠面上に焼結する焼結工程と、
    　を備える内燃機関のピストンの製造方法。     A method of manufacturing a piston having a crown surface facing a combustion chamber of an internal combustion engine, comprising:
    A mixed powder preparation step of preparing a mixed powder containing particles of charcoal and particles of a metal binder,
    A sintering step of energizing the mixed powder and the piston base material of the piston to sinter the mixed powder on the crown surface.
    A method for manufacturing a piston of an internal combustion engine, comprising:
  10. 　請求項９に記載の内燃機関のピストンの製造方法であって、
    　前記焼結工程後、酸素を含む気体中で、前記ピストン基材を所定温度で加熱する熱処理工程を備える内燃機関のピストンの製造方法。     A method for manufacturing a piston for an internal combustion engine according to claim 9,
    A method for manufacturing a piston of an internal combustion engine, comprising a heat treatment step of heating the piston base material at a predetermined temperature in a gas containing oxygen after the sintering step.
  11. 　請求項１０に記載の内燃機関のピストンの製造方法であって、
    　前記所定温度は、摂氏400度以上かつ摂氏600度以下である内燃機関のピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine according to claim 10,
    The method for producing a piston of an internal combustion engine, wherein the predetermined temperature is 400 degrees Celsius or more and 600 degrees Celsius or less.
  12. 　請求項１０に記載の内燃機関のピストンの製造方法であって、
    　前記熱処理工程は、溶体化処理を行う内燃機関のピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine according to claim 10,
    The heat treatment step is a method for manufacturing a piston of an internal combustion engine, which performs solution treatment.
  13. 　請求項９に記載の内燃機関のピストンの製造方法であって、
    　前記混合粉準備工程は、前記炭の粒子と前記金属バインダの粒子とを混合し、
    　前記焼結工程は、放電プラズマ焼結を行う内燃機関のピストンの製造方法。     A method for manufacturing a piston for an internal combustion engine according to claim 9,
    The mixed powder preparation step mixes particles of the charcoal and particles of the metal binder,
    The sintering step is a method of manufacturing a piston for an internal combustion engine, which performs spark plasma sintering.
  14. 　請求項１３に記載の内燃機関のピストンの製造方法であって、
    　前記混合粉準備工程は、前記炭の粒子と前記金属バインダの粒子とを均質に混合する内燃機関のピストンの製造方法。     A method for manufacturing a piston for an internal combustion engine according to claim 13,
    The mixed powder preparation step is a method of manufacturing a piston of an internal combustion engine, wherein the particles of the charcoal and the particles of the metal binder are uniformly mixed.
  15. 　請求項１３に記載の内燃機関のピストンの製造方法であって、
    　前記炭の粒子は、前記焼結工程において、前記放電プラズマの電極と前記ピストン基材とが前記炭の粒子を介して電気的に接続されるように前記混合粉中に分布する内燃機関のピストンの製造方法。     A method for manufacturing a piston for an internal combustion engine according to claim 13,
    The particles of the charcoal are distributed in the mixed powder so that the electrode of the discharge plasma and the piston base material are electrically connected through the particles of the charcoal in the sintering step. Manufacturing method.
  16. 　請求項９に記載の内燃機関のピストンの製造方法であって、
    　前記混合粉における前記炭の粒子の含有量が25重量%以上かつ65重量%以下である内燃機関のピストンの製造方法。     A method for manufacturing a piston for an internal combustion engine according to claim 9,
    A method for producing a piston of an internal combustion engine, wherein the content of the particles of the charcoal in the mixed powder is 25% by weight or more and 65% by weight or less.
  17. 　請求項１６に記載の内燃機関のピストンの製造方法であって、
    　前記混合粉において、前記金属バインダの粒子の含有量が45重量%であり、前記炭の粒子の含有量が55重量%である内燃機関のピストンの製造方法。     A method for manufacturing a piston for an internal combustion engine according to claim 16,
    The method for producing a piston for an internal combustion engine, wherein, in the mixed powder, the content of particles of the metal binder is 45% by weight and the content of particles of the charcoal is 55% by weight.
  18. 　請求項１７に記載の内燃機関のピストンの製造方法であって、
    　前記混合粉準備工程は、前記混合粉にパラフィンワックスを加える内燃機関のピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine according to claim 17,
    The mixed powder preparation step is a method of manufacturing a piston for an internal combustion engine, in which paraffin wax is added to the mixed powder.
  19. 　請求項１０に記載の内燃機関のピストンの製造方法であって、
    　前記冠面上に焼結された前記混合粉の表面に封孔処理を行う封孔処理工程を備える内燃機関のピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine according to claim 10,
    A method for manufacturing a piston for an internal combustion engine, comprising a sealing treatment step of performing a sealing treatment on a surface of the mixed powder sintered on the crown surface.
  20. 　請求項１９に記載の内燃機関のピストンの製造方法であって、
    　前記封孔処理工程は、前記熱処理工程後、前記冠面上に焼結された前記混合粉の表面に耐熱樹脂またはポリシラザンを塗布する内燃機関のピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine according to claim 19,
    The sealing treatment step is a method for manufacturing a piston of an internal combustion engine, which comprises applying a heat-resistant resin or polysilazane to the surface of the mixed powder sintered on the crown surface after the heat treatment step.
  21. 　請求項１９に記載の内燃機関のピストンの製造方法であって、
    　前記封孔処理工程は、前記混合粉準備工程後、前記混合粉を前記冠面との間で挟み込むようにアルミニウム層を前記混合粉の上に設置する内燃機関のピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine according to claim 19,
    In the sealing treatment step, after the mixed powder preparation step, a method for manufacturing a piston of an internal combustion engine, in which an aluminum layer is placed on the mixed powder so as to sandwich the mixed powder with the crown surface.
  22. 　請求項２１に記載の内燃機関のピストンの製造方法であって、
    　前記アルミニウム層は、アルミ箔による層である内燃機関のピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine according to claim 21,
    The method for manufacturing a piston of an internal combustion engine, wherein the aluminum layer is a layer made of aluminum foil.
  23. 　請求項２１に記載の内燃機関のピストンの製造方法であって、
    　前記アルミニウム層は、アルミニウムの粒子による層である内燃機関のピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine according to claim 21,
    The method for manufacturing a piston of an internal combustion engine, wherein the aluminum layer is a layer made of aluminum particles.
PCT/JP2020/000423 2019-02-20 2020-01-09 Internal combustion engine piston, and method for manufacturing same WO2020170635A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019027950A JP2020133492A (en) 2019-02-20 2019-02-20 Piston for internal combustion engine and method for manufacturing the same
JP2019-027950 2019-02-20

Publications (1)

Publication Number Publication Date
WO2020170635A1 true WO2020170635A1 (en) 2020-08-27

Family

ID=72144594

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2020/000423 WO2020170635A1 (en) 2019-02-20 2020-01-09 Internal combustion engine piston, and method for manufacturing same

Country Status (2)

Country Link
JP (1) JP2020133492A (en)
WO (1) WO2020170635A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013461A (en) * 1971-07-21 1977-03-22 Union Carbide Corporation High void porous sheet and process therefor
JPS60184950A (en) * 1984-03-02 1985-09-20 Isuzu Motors Ltd Internal-combustion engine having wall face of combustion chamber applied with heat insulating material
WO2016111022A1 (en) * 2015-01-05 2016-07-14 イビデン株式会社 Engine member with ceramic coating layer and method for producing engine member with ceramic coating layer
JP2018053879A (en) * 2016-09-30 2018-04-05 日立オートモティブシステムズ株式会社 Piston for internal combustion engine and method for manufacturing the same
JP2020012413A (en) * 2018-07-18 2020-01-23 日立オートモティブシステムズ株式会社 Manufacturing method of piston for internal combustion engine

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016063754A1 (en) * 2014-10-21 2016-04-28 日立オートモティブシステムズ株式会社 Method for manufacturing piston for internal combustion engine and frictional hole sealing device for piston for internal combustion engine
JP6557583B2 (en) * 2015-11-30 2019-08-07 日立オートモティブシステムズ株式会社 Piston for internal combustion engine and method for manufacturing piston for internal combustion engine
JP2018031302A (en) * 2016-08-25 2018-03-01 日立オートモティブシステムズ株式会社 Piston of internal combustion engine and method of manufacturing piston of internal combustion engine

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013461A (en) * 1971-07-21 1977-03-22 Union Carbide Corporation High void porous sheet and process therefor
JPS60184950A (en) * 1984-03-02 1985-09-20 Isuzu Motors Ltd Internal-combustion engine having wall face of combustion chamber applied with heat insulating material
WO2016111022A1 (en) * 2015-01-05 2016-07-14 イビデン株式会社 Engine member with ceramic coating layer and method for producing engine member with ceramic coating layer
JP2018053879A (en) * 2016-09-30 2018-04-05 日立オートモティブシステムズ株式会社 Piston for internal combustion engine and method for manufacturing the same
JP2020012413A (en) * 2018-07-18 2020-01-23 日立オートモティブシステムズ株式会社 Manufacturing method of piston for internal combustion engine

Also Published As

Publication number Publication date
JP2020133492A (en) 2020-08-31

Similar Documents

Publication Publication Date Title
JP5315880B2 (en) Method for forming thin film and method for manufacturing internal combustion engine
US6610964B2 (en) Multi-layer ceramic heater
EP1869739B1 (en) Open-chamber multi-spark plug
JP6356823B2 (en) Heat-resistant member with thermal barrier coating and method for manufacturing the same
US4107510A (en) Starting aids for combustion engines
CN1957641A (en) Ceramic heater, and glow plug using the same
JP2011517045A (en) Ceramic spark plug insulator and method of manufacturing the same
JP6694301B2 (en) Joined body and method for manufacturing joined body
WO2020170635A1 (en) Internal combustion engine piston, and method for manufacturing same
WO2018061591A1 (en) Piston for internal combustion engine and method for manufacturing piston for internal combustion engine
JP2009241030A (en) Package, vacuum container and reaction apparatus
EP2792035A1 (en) Electrode beam welded spark plugs for industrial electrodes
JP6809872B2 (en) Spark plug
JP2021131019A (en) Piston for internal combustion engine and method for manufacturing piston for internal combustion engine
WO2018199024A1 (en) Internal-combustion engine piston, and method for manufacturing internal-combustion engine piston
WO2019187273A1 (en) Internal combustion engine piston and manufacturing method for internal combustion engine piston
JP3774410B2 (en) Refractory insulation for microwave firing furnaces
RU2154361C1 (en) Ceramic electric heating element and process of its manufacture
JPH03225785A (en) Spark plug for internal combustion engine
CN117581434A (en) Spark plug
JPH04259781A (en) Ceramic heater
JPS58210341A (en) Ceramic cylinder head
JP3075660B2 (en) Ceramic heater and method of manufacturing the same
WO2018198898A1 (en) Piston
JP2999002B2 (en) Ceramic heater

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20759645

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 20759645

Country of ref document: EP

Kind code of ref document: A1