WO2017122474A1 - Method for producing piston, and piston - Google Patents

Method for producing piston, and piston Download PDF

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Publication number
WO2017122474A1
WO2017122474A1 PCT/JP2016/086692 JP2016086692W WO2017122474A1 WO 2017122474 A1 WO2017122474 A1 WO 2017122474A1 JP 2016086692 W JP2016086692 W JP 2016086692W WO 2017122474 A1 WO2017122474 A1 WO 2017122474A1
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WO
WIPO (PCT)
Prior art keywords
low heat
heat conduction
piston
pressing
manufacturing
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Application number
PCT/JP2016/086692
Other languages
French (fr)
Japanese (ja)
Inventor
高橋　智一
Original Assignee
日立オートモティブシステムズ株式会社
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Publication of WO2017122474A1 publication Critical patent/WO2017122474A1/en

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    • 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
    • F02F3/12—Pistons  having surface coverings on piston heads
    • F02F3/14—Pistons  having surface coverings on piston heads within combustion chambers
    • 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 
    • F02F3/26—Pistons  having combustion chamber in piston head
    • 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 manufacturing method and a piston.
  • Patent Document 1 discloses a structure in which a cavity is formed on the top surface of a piston made of an aluminum alloy, and a low thermal conductivity member having a low thermal conductivity is attached to the bottom surface of the cavity.
  • an object of the present invention is to provide a piston manufacturing method and a piston capable of providing a low heat conductive member at a position corresponding to the fuel injection region of the piston. .
  • an annular low heat conduction part formed of a low heat conduction part forming material which is a material having a lower thermal conductivity than an aluminum alloy, is provided on the piston body part.
  • a step of forming the crown portion on the combustion chamber side of the internal combustion engine, and a lower heat conduction portion forming material inside the inner peripheral edge of the annular low heat conduction portion in a cross section orthogonal to the moving direction of the piston in the cylinder of the internal combustion engine In addition, a low thermal conduction part forming step of forming a low thermal conduction part so as to have a non-low thermal conduction part made of a material having high thermal conductivity is provided.
  • the piston of the internal combustion engine is formed of a low heat conduction part forming material that is provided on the combustion chamber side of the internal combustion engine at the crown of the piston and has a lower thermal conductivity than the aluminum alloy.
  • the low heat conduction portion can be provided at a position corresponding to the fuel injection amount region.
  • FIG. 1 is a perspective view of a piston of an internal combustion engine of Embodiment 1.
  • FIG. 3 is a flowchart showing manufacturing steps of the piston of Example 1.
  • FIG. 3 is a view showing a piston after completion of a primary machining process of Example 1.
  • FIG. 3 is a view showing the piston after completion of the mixed powder filling step of Example 1.
  • FIG. 3 is a view showing the piston after execution of the mixed powder pressing step of Example 1.
  • FIG. 3 is a view showing the piston after the mixed powder pressing step of Example 1 is completed.
  • FIG. 3 is a view showing a piston after completion of the secondary machining process of the first embodiment.
  • 6 is a perspective view of a piston according to Embodiment 2.
  • FIG. 5 is a flowchart showing a manufacturing process of a piston of Example 2.
  • FIG. 5 is a flowchart showing a manufacturing process of a piston of Example 2.
  • FIG. 6 is a view showing a piston after completion of a primary machining process of Example 2.
  • 5 is a perspective view of a preform of Example 2.
  • FIG. FIG. 5 is a view showing a piston after completion of a preform arranging step in Example 2.
  • FIG. 6 is a view showing a piston when a preform pressing process of Example 2 is performed.
  • FIG. 6 is a view showing a piston at the end of a pressing step in Example 2.
  • FIG. 6 is a view showing a piston after completion of a pressing step in Example 2.
  • FIG. 6 is a view showing the shape of a piston after the completion of the secondary machining process of Example 2.
  • 6 is a perspective view of a piston of Example 3.
  • FIG. FIG. 6 is a perspective view of a piston of an internal combustion engine according to a fourth embodiment.
  • FIG. 1 is a perspective view of a piston 1 of an internal combustion engine.
  • the piston 1 is formed using an aluminum alloy as a base material.
  • the piston 1 according to the first embodiment is used in a cylinder injection type internal combustion engine.
  • the piston 1 is formed in a substantially cylindrical shape.
  • the surface (top surface) on the combustion chamber side in the axial direction of piston 1 (the direction in which piston 1 reciprocates within the cylinder) constitutes crown 2.
  • a low heat conduction portion 3 is formed in the crown portion 2.
  • the low heat conducting portion 3 is formed in an annular shape in a cross section orthogonal to the axial direction of the piston 1.
  • the low heat conducting portion 3 is formed in a single ring over the entire circumference of the crown portion 2 inside the outermost circumference of the crown portion 2.
  • the low heat conduction part 3 is formed of a material having a lower thermal conductivity than the aluminum alloy.
  • the material of the low heat conduction part 3 will be described in detail later.
  • the material on the inner peripheral side of the low heat conducting portion 3 is an aluminum alloy.
  • the inner peripheral side of the low heat conducting portion 3 constitutes a non-low heat conducting portion 2b.
  • the entire outer periphery of the outer peripheral edge of the low heat conducting portion 3 is surrounded by an aluminum alloy.
  • the entire outer periphery of the outer peripheral edge of the low heat conducting portion 3 is surrounded by an aluminum alloy.
  • a ring groove 4 is formed over the entire circumference.
  • the ring groove 4 is formed at three positions apart in the axial direction, and constitutes a top ring groove 4a, a second ring groove 4b, and an oil ring groove 4c in order from the crown portion 2 side.
  • a cylinder ring is engaged with each of the top ring groove 4a and the second ring groove 4b.
  • An oil ring is engaged with the oil ring groove 4c.
  • a skirt portion 5 is formed below the oil ring groove 4c.
  • the skirt portion 5 is formed at two locations separated in the circumferential direction.
  • the skirt portions 5 are formed at positions facing each other.
  • the outer peripheral surface of the skirt portion 5 is formed in a substantially cylindrical shape.
  • the crown part 2, the skirt part 5, and the land part 8 constitute the main body part 9.
  • the boss part 6 is formed at a position substantially orthogonal to the opposing skirt part 5 with the skirt part 5 sandwiched therebetween. .
  • the boss portion 6 is formed with a pin hole 6a into which a piston pin for assembling the connecting rod to the piston 1 so as to be rotatable is inserted.
  • FIG. 2 is a flowchart showing the manufacturing process of the piston 1.
  • FIG. 3 shows the piston 1 after the primary machining process.
  • FIG. 4 is a view showing the piston 1 after the mixed powder filling step.
  • FIG. 5 is a view showing the piston 1 during the mixed powder pressing step.
  • FIG. 6 is a view showing the piston 1 after the mixed powder pressing step.
  • FIG. 7 shows the piston 1 after the secondary machining process.
  • Step S1 is a piston 1 casting process. In the piston casting process, the rough material of the piston 1 is cast with an aluminum alloy. In this step, the main body 9 is formed.
  • Step S2 is a primary machining process (FIG. 3).
  • the annular groove 2a is formed by processing a concave groove over the entire circumference in the crown portion 2.
  • the annular groove 2a is filled with the material of the low heat conducting portion 3 in a later step.
  • the annular groove 2a may be formed by casting in the casting process.
  • Step S3 is a mixed powder filling process (FIG. 4).
  • the mixed powder 3a which is the material of the low heat conduction part 3, is filled into the annular groove 2a.
  • the mixed powder 3a is alloyed with a powder of a material having a lower thermal conductivity (low thermal conductivity material) than an aluminum alloy that is a material of the main body 9 of the piston 1 and an aluminum alloy that is a material of the main body 9 by plastic flow. It consists of a powder of a material (joining material) that can be an intermetallic compound.
  • Step S4 is a mixed powder pressing step (FIGS. 5 and 6).
  • the mixed powder pressing step the cylindrical tool 7 is rotated in the circumferential direction while pressing the mixed powder 3a into the annular groove 2a by the cylindrical tool 7. Thereby, the joining material is softened and stirred. Therefore, the low thermal conductive material can be held in the bonding material.
  • the bonding material is alloyed with the aluminum alloy that is the material of the main body 9, or forms an intermetallic compound.
  • a method similar to the friction stir welding is used.
  • the low heat conducting portion 3 is integrated with the aluminum alloy portion that is the material of the main body portion 9.
  • a stirring trajectory when the joining member is stirred by the cylindrical tool 7 remains on the surface of the low heat conducting portion 3.
  • the volume of the low heat conductive portion 3 is reduced from the state of the mixed powder 3a and is not exposed on the surface of the crown portion 2.
  • the inner diameter of the cylindrical tool 7 is slightly smaller than the inner diameter of the annular groove 2a (the diameter of the side surface on the radially inner side of the groove).
  • the outer diameter of the cylindrical tool 7 is slightly larger than the outer diameter of the annular groove 2a (the diameter of the side surface on the radially outer side of the groove).
  • Step S5 is a heat treatment process.
  • the piston 1 after the mixed powder pressing step is heat treated.
  • Step S6 is a secondary machining process (FIG. 7).
  • the secondary machining process the piston 1 is finished by a machine tool. At this time, the crown portion 2 is cut, and the low heat conduction portion 3 is exposed on the surface of the crown portion 2. Further, the ring groove 4 is formed in the secondary machining process.
  • the piston 1 Since the piston 1 has a large volume, the heat capacity is large and the temperature of the piston 1 does not rise rapidly. Further, since the piston 1 is made of an aluminum alloy, heat conductivity is high, and heat received from the fuel gas in the cylinder at the crown portion 2 is transmitted from the piston ring or the skirt portion 5 to the cylinder. Therefore, the temperature rise of the piston 1 is gradual.
  • the piston 1 of the first embodiment is used for a cylinder injection internal combustion engine. The fuel injected into the cylinder evaporates in the cylinder, but part of it collides with the crown 2 of the piston 1. When the temperature of the piston 1 is sufficiently high, when the fuel collides with the crown 2, the fuel receives heat from the piston 1 and evaporates.
  • the temperature of the piston 1 is moderately increased, the temperature of the piston 1 is low when the internal combustion engine is started, and there is a possibility that fuel that cannot be evaporated on the crown portion 2 remains as a liquid film. The fuel remaining on the crown 2 causes deposits and contamination of unburned hydrocarbons into the exhaust.
  • Example 1 the low thermal conductivity portion 3 having a lower thermal conductivity than the aluminum alloy that forms the piston 1 is formed in the crown portion 2.
  • the heat received from the fuel gas in the low heat conducting section 3 is not easily transmitted to other parts, and the temperature rise of the low heat conducting section 3 can be accelerated. Therefore, the fuel that has collided with the low heat conducting section 3 is likely to evaporate.
  • the low heat conduction portion 3 is formed in an annular shape at the radially outer portion of the crown portion 2. Formed.
  • the low heat conduction portion 3 can be provided at a position corresponding to the fuel injection amount region.
  • the crown 2 of the piston 1 is filled with the mixed powder 3a in the annular groove 2a, and the mixed powder 3a is pressed by the cylindrical tool 7 so as to pack the mixed powder 3a into the annular groove 2a in the circumferential direction. It was made to rotate to.
  • the annular low heat conduction portion 3 can be formed at a time.
  • Example 1 the aluminum alloy of the main body portion 9 is provided on the inner peripheral side of the annular low heat conducting portion 3. Thereby, it is not necessary to use an inner peripheral side of the low heat conducting portion 3 other than the aluminum alloy that is the material of the main body portion 9. Further, since the meat of the main body 9 is present inside the inner peripheral edge of the low heat conduction part 3, the mixed powder 3a is difficult to escape inside the low heat conduction part 3 in the mixed powder pressing step, and it is easy to apply pressure to the mixed powder 3a. Become. In Example 1, the entire outer periphery of the outer peripheral edge of the annular groove 2a is surrounded by the aluminum alloy of the main body 9.
  • the meat of the main body 9 is present outside the outer peripheral edge of the low heat conduction part 3, so that the mixed powder 3a is difficult to escape outside the low heat conduction part 3 in the mixed powder pressing step, and pressure is applied to the mixed powder 3a. It becomes easy.
  • the forming material of the low heat conducting portion 3 was the powder mixed powder 3a. Accordingly, the mixed powder pressing step can be performed in a state where the bonding material and the low heat conductive material are uniformly mixed in the annular groove 2a, and the low heat conductive portion 3 can be made of a uniform material.
  • a method for manufacturing a piston 1 of an internal combustion engine includes a casting step (main body portion forming step) in which a main body portion 9 having a crown portion 2 and a skirt portion 5 provided on the crown portion 2 is formed of an aluminum alloy.
  • an annular low heat conduction part 3 formed of a low heat conduction material which is a material having a lower thermal conductivity than aluminum alloy, on the combustion chamber side of the internal combustion engine in the crown part 2
  • the low heat conduction part forming step is a mixed powder filling step (filling step) of filling the mixed powder 3a (low heat conduction part forming material) into the annular groove 2a (concave part) provided on the combustion chamber side of the crown part 2. And a mixed powder pressing step (pressing step) in which the mixed powder 3a (low heat conduction portion forming material) in the annular groove 2a (recessed portion) is pressed by the rotating cylindrical tool 7 (tool). By performing the mixed powder pressing step using the cylindrical tool 7, the annular low heat conduction portion 3 can be formed at a time.
  • the non-low heat conduction part 2b is made of an aluminum alloy of the main body part 9.
  • the low heat conduction part forming step includes a step of filling the annular groove 2a (annular recess) provided on the combustion chamber side of the crown 2 with the mixed powder 3a (low heat conduction part forming material), and the annular groove 2a ( A mixed powder pressing step (pressing step) for pressing the mixed powder 3a (low heat conduction portion forming material) in the annular recess) with a rotating cylindrical tool 7 (tool), and the annular groove 2a (annular recess)
  • a mixed powder pressing step pressing step for pressing the mixed powder 3a (low heat conduction portion forming material) in the annular recess) with a rotating cylindrical tool 7 (tool), and the annular groove 2a (annular recess)
  • the entire outer periphery of the outer peripheral edge of the annular groove 2a (annular recess) is surrounded by the aluminum alloy of the main body 9.
  • the mixed powder 3a (low heat conduction part forming material) was used as a powder mixed material. Accordingly, the mixed powder pressing step can be performed in a state where the bonding material and the low heat conductive material are uniformly mixed in the annular groove 2a, and the low heat conductive portion 3 can be made of a uniform material.
  • a piston 1 of an internal combustion engine which is made of an aluminum alloy and has a crown portion 2 and a main body portion 9 provided with a skirt portion 5 provided on the crown portion 2, and combustion of the crown portion 2 of the internal combustion engine
  • a non-low heat conductive portion 2b provided on the inner side and formed of a material having higher thermal conductivity than the mixed powder 3a (low heat conductive portion forming material).
  • Example 2 In the piston 1 of Example 1, the entire outer periphery of the outer peripheral edge of the low heat conducting portion 3 was surrounded by an aluminum alloy. In Example 2, it was formed so that the entire outer periphery of the outer peripheral edge of the low thermal conductive portion 3 was exposed.
  • the piston 1 of the second embodiment will be described, but the same components as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.
  • FIG. 8 is a perspective view of the piston 1 of the second embodiment.
  • a low heat conduction portion 3 is formed in the crown portion 2 of the piston 1.
  • the low heat conducting portion 3 is formed in an annular shape in a cross section orthogonal to the axial direction of the piston 1.
  • the low heat conducting portion 3 is formed in a single ring over the entire circumference of the crown portion 2 on the outermost circumference of the crown portion 2.
  • the low heat conduction part 3 is formed of a material having a lower thermal conductivity than the aluminum alloy.
  • the material on the inner peripheral side of the low heat conducting portion 3 is an aluminum alloy.
  • the inner peripheral side of the low heat conducting portion 3 constitutes a non-low heat conducting portion 2b.
  • the low heat conducting portion 3 is provided so that the outer peripheral surface is exposed.
  • FIG. 9 is a flowchart showing the manufacturing process of the piston 1.
  • FIG. 10 is a view showing the piston 1 after completion of the primary machining process.
  • FIG. 11 is a perspective view of the preform 3b.
  • FIG. 12 is a view showing the piston 1 after completion of the preform arranging step.
  • FIG. 13 is a view showing the piston 1 when the preform pressing process is performed.
  • FIG. 14 shows the piston 1 at the end of the pressing step.
  • FIG. 15 is a view showing the piston 1 after completion of the pressing step.
  • FIG. 16 is a view showing the shape of the piston 1 after completion of the secondary machining process.
  • Step S11 is a casting process of the piston 1. In the piston casting process, the rough material of the piston 1 is cast with an aluminum alloy.
  • Step S12 is a primary machining process.
  • the outer diameter of the rough land of the piston 1 is cut by the machine tool, the outer diameter of the skirt 5 is cut, the boss 6 is processed, the pin hole 6a is processed, and the annular groove 2a of the crown 2 is formed.
  • Perform processing The annular groove 2a is formed by processing a concave groove over the entire circumference in the crown portion 2.
  • the annular groove 2a is provided with a low heat conduction portion 3 in a later step.
  • the annular groove 2a is formed so that the outer peripheral side is exposed after the low heat conducting portion 3 is provided.
  • the annular groove 2a may be formed by casting in the casting process.
  • the fixing jig 10 is formed in a cylindrical shape.
  • the inner diameter of the fixing jig 10 is substantially the same as the outer diameter of the land portion 8 of the piston 1 and is formed so that the piston 1 can be accommodated on the inner periphery.
  • the height of the fixing jig 10 is substantially the same as the height of the piston 1 in the axial direction.
  • Step S13 is a green compact forming process.
  • the mixed powder 3a is filled in the annular groove 2a.
  • the annular preform 3b is formed from the low heat conductive material and the bonding material.
  • the preform 3b is formed as a green compact by mixing and pressing a powdery low thermal conductive material and a bonding material.
  • Step S14 is a green compact heat treatment process. After forming the preform 3b as a green compact, the preform 3b is heated. As a result, the particulate low thermal conductive material and the oxide film covering the surface of the bonding material are broken, and the particles are easily bonded to each other. Therefore, the preform 3b is not easily collapsed.
  • Step S15 is a preform placement process.
  • Step S16 is a preform pressing process.
  • the cylindrical tool 7 is rotated in the circumferential direction while pressing the preform 3b so as to be packed in the annular groove 2a.
  • the joining material is softened and stirred. Therefore, the low thermal conductive material can be held in the bonding material.
  • the bonding material is alloyed with the aluminum alloy that is the material of the main body 9, or forms an intermetallic compound.
  • the low heat conducting portion 3 is integrated with the aluminum alloy portion that is the material of the main body portion 9.
  • a stirring trajectory when the joining member is stirred by the cylindrical tool 7 remains on the surface of the low heat conducting portion 3.
  • the volume of the low heat conductive portion 3 is reduced from the state of the mixed powder 3a and is not exposed on the surface of the crown portion 2.
  • the inner diameter of the cylindrical tool 7 is formed to be approximately the same as the inner diameter of the annular groove 2a (the diameter of the side surface on the radially inner side of the groove).
  • the outer diameter of the cylindrical tool 7 is formed to be approximately the same as the outer diameter of the land portion 8 of the piston 1.
  • the preform 3b of Example 2 is a green compact, and therefore there is little risk of leakage from the annular groove 2a. Therefore, unlike the first embodiment, it is not necessary to make the width of the cylindrical tool 7 larger than the width of the annular groove 2a so as to overlap and contact the main body 9 other than the annular groove 2a.
  • Step S17 is a heat treatment process.
  • the piston 1 that has undergone the preform pressing step is subjected to heat treatment.
  • the strain associated with the plastic flow during the preform pressing step is removed, and the strength is made uniform.
  • Step S18 is a secondary machining process.
  • the piston 1 is finished by a machine tool. At this time, the crown portion 2 is cut, and the low heat conduction portion 3 is exposed on the surface of the crown portion 2. Further, the ring groove 4 is formed in the secondary machining process.
  • the top ring groove 4a is formed on the outer peripheral surface of the low heat conducting portion 3.
  • Example 2 The effects of Example 2 are listed below.
  • Primary machining peripheral part removing step
  • the low heat conduction part 3 can be provided on the outermost peripheral side of the crown surface 2 of the piston 1. Therefore, in the internal combustion engine in which the fuel injection region exists on the outermost peripheral side of the crown portion 2, the low heat conduction portion 3 can be provided at a position corresponding to the fuel injection amount region.
  • the preform 3b (low heat conduction part forming material) is a material having a hardness higher than that of the aluminum alloy, and the low heat conduction part forming step is performed so that the low heat conduction part 3 is exposed to the outer peripheral side of the piston 1.
  • a secondary machining step (ring groove forming step) for forming the top ring groove 4a into which the piston ring is inserted on the outer peripheral side of the low heat conducting portion 3 is further provided. Thereby, the strength of the top ring groove 4a can be improved.
  • the low heat conduction part forming step is a preform setting step in which the annular groove 2a (concave part) provided in the outermost peripheral part on the combustion chamber side of the crown part 2 is filled with the preform 3b (low heat conduction part forming material).
  • the preform pressing step (pressing step) was performed in a state where the outer peripheral side of the main body 9 was surrounded by the fixing jig 10 (mold).
  • the low thermal conduction part forming process includes a green compact forming process (compacting process) for forming a green compact obtained by pressing a powder mixed material that is a preform 3b (low thermal conductive part forming material), a crown A preform arranging step (arranging step) in which the green compact is arranged in an annular groove 2a (concave portion) provided on the combustion chamber side of the portion 2. This makes it difficult for the preform 3b to escape from the annular groove 2a in the preform pressing step.
  • the low thermal conduction part forming step further includes a pre-farm heat treatment step (heat treatment step) performed after the green compact formation step (compact step) and before the preform placement step (placement step). did. Thereby, the preform 3b can be made difficult to collapse, and the preform 3b can be made difficult to escape in the preform pressing step.
  • the low heat conduction portion forming step is a preform arrangement step (filling step) in which the annular groove 2a (concave portion) provided on the combustion chamber side of the crown portion 2 is filled with the preform 3b (low heat conduction portion forming material).
  • the preform 3b (low heat conduction portion forming material) is a material having a hardness higher than that of the aluminum alloy, and the crown portion 2 is provided on the outer peripheral side of the crown portion 2 and is a top ring groove into which a piston ring is inserted. It has 4a (ring groove), and the low heat conduction part 3 is provided in a range including the top ring groove 4a (ring groove). Thereby, the strength of the top ring groove 4a can be improved.
  • Example 3 In Example 1, it was formed in a single ring over the entire circumference of the low thermal conductivity portion 3 and the crown portion 2. In Example 3, the low heat conductive portion 3 is formed in a plurality of annular shapes.
  • the piston 1 of the third embodiment will be described, but the same components as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.
  • FIG. 17 is a perspective view of the piston 1 of the third embodiment.
  • a low heat conduction portion 3 is formed in the crown portion 2 of the piston 1.
  • the low heat conducting portion 3 is formed in an annular shape in a cross section orthogonal to the axial direction of the piston 1.
  • a plurality of low heat conduction portions 3 are formed and arranged in the circumferential direction of the crown portion 2.
  • the low heat conduction part 3 is formed of a material having a lower thermal conductivity than the aluminum alloy.
  • the material on the inner peripheral side of the low heat conducting portion 3 is an aluminum alloy.
  • the inner peripheral side of the low heat conducting portion 3 constitutes a non-low heat conducting portion 2b.
  • the annular groove 2a is formed in the same manner as in Example 1, and the mixed powder 3a is pressed by the cylindrical tool 7 after filling the annular groove 2a with the mixed powder 3a. May be formed.
  • the preform 3b may be disposed in the annular groove 2a.
  • the pressing process may be performed eight times with one cylindrical tool 7. Further, the pressing process may be performed once by the eight cylindrical tools 7. In any method, there are a plurality of rotation centers of the cylindrical tool 7 in a cross section orthogonal to the moving direction of the piston 1 in the cylinder.
  • the cylindrical tool 7 since the size of one low heat conducting portion 3 is small, the cylindrical tool 7 can also be made small. Therefore, the pressing force of the mixed powder 3a or the preform 3b by the cylindrical tool 7 can be suppressed, and the deformation of the piston 1 in the pressing process can be suppressed.
  • the low heat conduction part forming step is a mixed powder filling (filling step) in which the mixed powder 3a (low heat conduction part forming material) is filled in the annular groove 2a (concave part) provided on the combustion chamber side of the crown part 2.
  • a mixed powder pressing step pressing step for pressing the mixed powder 3a (low heat conduction portion forming material) in the annular groove 2a (recessed portion) with a rotating cylindrical tool 7 (tool), and a mixed powder pressing step ( The pressing step) is performed so that there are a plurality of rotation centers of the cylindrical tool 7 (tool) in a cross section orthogonal to the moving direction of the piston 1.
  • the low heat conduction part forming step is a mixed powder filling step (filling step) of filling the mixed powder 3a (low heat conduction part forming material) into the annular groove 2a (concave part) provided on the combustion chamber side of the crown part 2.
  • the low heat conduction section 3 has a plurality of parts to be stirred having a stirring locus in which the mixed powder 3a (low heat conduction forming member) is stirred around the stirring center in a cross section orthogonal to the moving direction of the piston 1. As a result, a plurality of low heat conduction parts 3 can be formed, and the low heat conduction part 3 having an appropriate shape can be formed at an appropriate position in accordance with the fuel injection region.
  • Example 4 In Example 1, it was formed in a single ring over the entire circumference of the low thermal conductivity portion 3 and the crown portion 2.
  • the second low heat conduction part 11 is further formed on the inner peripheral side of the annular low heat conduction part 3 formed in the same manner as in Example 1.
  • FIG. 18 is a perspective view of the piston 1 of the internal combustion engine. A low heat conduction portion 3 and a second low heat conduction portion 11 are formed in the crown portion 2 of the piston 1.
  • the low heat conducting portion 3 is formed in a single ring over the entire circumference of the crown portion 2 as in the first embodiment.
  • a circular second low heat conduction portion 11 is formed in the central portion of the crown portion 2.
  • a non-low heat conduction part 2b is provided between the low heat conduction part 3 and the second low heat conduction part 11.
  • the non-low heat conduction part 2b is a part of the main body part 9, and is formed of an aluminum alloy.
  • the annular groove 2a is formed in the same manner as in Example 1, and the mixed powder 3a is pressed by the cylindrical tool 7 after filling the annular groove 2a with the mixed powder 3a. May be formed.
  • a cylindrical recess is formed instead of the annular groove 2a, and after the mixed powder 3a is filled in this recess, it is matched with the shape of the cylindrical recess. What is necessary is just to form so that the mixed powder 3a may be pressed with the formed cylindrical tool. Further, a preform 3b may be disposed instead of the mixed powder 3a as in the second embodiment.
  • the low heat conduction part 3 and the second low heat conduction part 11 are not pressed at once using the cylindrical tool 7 or the columnar tool, but have a diameter smaller than the width of the annular groove 2a and the diameter of the cylindrical recess. You may make it press the mixed powder 3a and the preform 3b, moving a tool using a tool.
  • the step of pressing the mixed powder 3a (low heat conduction portion forming material) is performed while moving the tool. Thereby, it is not necessary to prepare a tool according to the shape of the low heat conduction part 3. In addition, a continuous low heat conducting portion 3 can be formed.
  • the present invention has been described based on the first to fourth embodiments.
  • the specific configuration of each invention is not limited to the first to fourth embodiments, and does not depart from the gist of the present invention.
  • Such design changes are included in the present invention.
  • the mixed powder 3a is filled in the annular groove 2a.
  • the preform 3b may be disposed in the annular groove 2a.
  • the preform 3b is disposed in the annular groove 2a.
  • the mixed powder 3a may be filled in the annular groove 2a.
  • the mixed powder 3a or the preform 3b was pressed by the cylindrical tool 7, but using a tool having a diameter smaller than the width of the annular groove 2a, the tool was moved.
  • the mixed powder 3a and the preform 3b may be pressed.
  • the non-low heat conduction part 2b on the inner peripheral side of the low heat conduction part 3 is a part of the main body part 9, and is formed of an aluminum alloy.
  • the non-low heat conduction part 2b may be formed of a material different from that of the main body part 9.
  • the shapes of the low thermal conductive material and the bonding material in Examples 1 to 4 are not limited to powder, but may be flakes or chips.
  • a hollow porous ceramic bead, a hollow glass bead, and a hollow metal sphere can be used in addition to a filler having a fine porous structure mainly composed of silica, silica gel, silica airgel, and the like.
  • high strength and high heat resistance ceramic fibers low heat conductivity and low specific heat heat resistant metal materials such as titanium, titanium alloys, SUS, low alloys Powders of steel, cast iron (gray cast iron, spheroidal graphite cast iron) and the like can be used similarly.
  • metal materials such as titanium, titanium alloys, SUS, low alloys Powders of steel, cast iron (gray cast iron, spheroidal graphite cast iron) and the like can be used similarly.
  • a method for manufacturing a piston of an internal combustion engine is as follows: A body part forming step of forming a body part having a crown part and a skirt part provided in the crown part from an aluminum alloy; A step of forming an annular low heat conduction part formed of a low heat conduction part forming material having a lower thermal conductivity than the aluminum alloy on the combustion chamber side of the internal combustion engine in the crown part, A non-low heat conduction part formed of a material having a higher thermal conductivity than the low heat conduction part forming material is provided inside the inner peripheral edge of the annular low heat conduction part in a cross section orthogonal to the moving direction of the piston in the cylinder. And a low thermal conduction part forming step for forming the low thermal conduction part.
  • the low thermal conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low thermal conduction portion forming material, and a tool for rotating the low thermal conduction portion forming material in the concave portion.
  • a pressing step of pressing with, The pressing step is performed such that a plurality of rotation centers of the tool exist in a cross section orthogonal to the moving direction of the piston.
  • the step of pressing the low heat conduction portion forming material with the tool is performed a plurality of times. Thereby, a pressure can be efficiently applied to the low heat conduction part forming material with a tool, and the adhesiveness of the low heat conduction part can be improved.
  • the pressing step is performed while the tool is moved in the step of pressing the low heat conduction portion forming material. Thereby, it is not necessary to prepare a tool according to the shape of the low heat conduction part. Moreover, the continuous low heat conductive part can be formed.
  • the low heat conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low heat conduction portion forming material, and an annular shape rotating the low heat conduction portion forming material in the concave portion. Pressing with a tool. By performing the pressing step using an annular tool, an annular low heat conduction portion can be formed at a time.
  • the non-low heat conduction part is the aluminum alloy of the main body part.
  • the aluminum alloy which is a raw material of a main-body part for the inner peripheral side of a low heat conductive part.
  • flour of a main-body part exists inside the inner periphery of a low heat conductive part, mixed powder cannot escape easily inside a low heat conductive part in a press process, and it becomes easy to apply a pressure to mixed powder.
  • the low heat conduction part forming step includes a step of filling the annular recess provided on the combustion chamber side in the crown with the low heat conduction part forming material, and rotating the low heat conduction part forming material in the annular recess. Pressing with a tool, and In the annular recess, the entire outer periphery of the outer peripheral edge of the annular recess is surrounded by the aluminum alloy of the main body.
  • flour of a main-body part exists outside the outer periphery of a low heat conductive part, mixed powder cannot escape easily to the outer side of a low heat conductive part in a mixed powder press process, and it becomes easy to apply a pressure to mixed powder.
  • the low heat conduction part forming material is a material having a higher hardness than the aluminum alloy
  • the low heat conduction part forming step is performed such that the low heat conduction part is exposed on the outer peripheral side of the piston, It further has a ring groove forming step of forming a ring groove into which a piston ring is inserted on the outer peripheral side of the low heat conducting portion. As a result, the strength of the ring groove can be improved.
  • the low heat conduction portion forming step includes a filling step of filling the concave portion provided in the outermost peripheral portion on the combustion chamber side of the crown portion with the low heat conduction portion forming material, and the low heat conduction portion forming material in the concave portion. Pressing with a rotating tool, and The pressing step is performed in a state where the outer peripheral side of the main body is surrounded by a mold. Thereby, even if it is a case where the thickness of a crown part does not exist in the outer peripheral side from a low heat conductive part, the escape of the low heat conductive part formation material can be suppressed by a type
  • the low heat conduction part forming material is a mixed powder material.
  • a press process can be performed in the state with which the low heat conductive part formation material was mixed uniformly in the recessed part of a crown part, and a low heat conductive part can be made into a uniform material.
  • the low thermal conduction portion forming step is provided on the combustion chamber side of the crown portion, and a compacting step of forming a green compact by pressing the mixed material of the powder that is the low thermal conduction portion forming material. An arrangement step of arranging the green compact in the recess.
  • the low heat conduction part forming step further includes a heat treatment step performed after the compacting step and before the arranging step. Thereby, the green compact can be made difficult to collapse, and the green compact can be made difficult to escape in the pressing step.
  • the low heat conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side of the crown portion with the low heat conduction portion forming material, and a plurality of rotating the low heat conduction portion forming material in the concave portion. Pressing with the tool at the same time. Thereby, in the mixed pressing step, the meat of the piston between the recesses is difficult to escape, and it is possible to easily apply pressure to the low heat conduction portion forming material with the tool.
  • the low thermal conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low thermal conduction portion forming material, and a tool for rotating the low thermal conduction portion forming material in the concave portion.
  • a pressing step of pressing with, The pressing step is performed in a state where the outer peripheral side of the main body is surrounded by a mold. Thereby, a deformation
  • the piston A piston of an internal combustion engine, formed of an aluminum alloy, and having a crown portion, and a skirt portion provided on the crown portion, a main body portion, An annular low heat conduction part formed of a low heat conduction part forming material which is provided on the combustion chamber side of the internal combustion engine of the crown part and has a lower thermal conductivity than the aluminum alloy; A non-low heat conduction portion that is provided on the inner side of the inner peripheral edge of the annular low heat conduction portion and is formed of a material having a higher thermal conductivity than the low heat conduction portion forming material.
  • the low heat conduction part has a plurality of parts to be stirred having a stirring locus in which the low heat conduction forming member is stirred around a stirring center in a cross section orthogonal to the moving direction of the piston.
  • a plurality of low heat conduction parts can be formed, and a low heat conduction part having an appropriate shape can be formed at an appropriate position according to the fuel injection region.
  • the low heat conduction part forming material is a material having a higher hardness than the aluminum alloy
  • the crown portion has a ring groove provided on an outer peripheral side of the crown portion and into which a piston ring is inserted, and the low heat conduction portion is provided in a range including the ring groove.
  • the low heat conduction part forming material is a mixed powder material.

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  • 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

In order to provide a method for producing a piston with which a low thermal conduction member can be provided at a position corresponding to a fuel injection region of the piston, this method for producing a piston for an internal combustion engine is configured to have a low thermal conduction portion formation step in which an annular low thermal conduction portion, which is formed from a low thermal conduction portion formation material which is a material having lower thermal conductivity than an aluminum alloy, is formed on an internal combustion engine combustion chamber side of a crown portion of a piston main body portion, wherein the low thermal conduction portion is formed so as to have a non-low thermal conduction portion, which is formed from a material having a higher thermal conductivity than the low thermal conduction portion formation material, further to the inside than the inner peripheral edge of the annular low thermal conduction portion in a cross-section that is orthogonal to the direction of movement of the piston in a cylinder of the internal combustion engine.

Description

ピストンの製造方法およびピストンPiston manufacturing method and piston
　本発明は、ピストンの製造方法およびピストンに関する。 The present invention relates to a piston manufacturing method and a piston.
　この種の技術としては、下記の特許文献1に記載の技術が開示されている。特許文献1には、アルミニウム合金を素材とするピストンの頂面にキャビティを形成し、キャビティの底面に熱伝導率の小さい低熱伝導部材を取り付けたものが開示されている。 As this type of technology, the technology described in Patent Document 1 below is disclosed. Patent Document 1 discloses a structure in which a cavity is formed on the top surface of a piston made of an aluminum alloy, and a low thermal conductivity member having a low thermal conductivity is attached to the bottom surface of the cavity.
特開平11-193721号公報Japanese Patent Laid-Open No. 11-193721
　上記特許文献1の技術にあっては、ピストンを軸方向から見たときに、燃料噴射弁側の半分の領域に低熱伝導部材を設けている。しかし、燃料噴射領域は燃料噴射弁の取り付け位置などに応じて異なるため、燃料噴射領域に低熱伝導部材を設けることができないおそれがあった。
  本発明は、上記問題に着目されたもので、その目的とするところは、ピストンの燃料噴射領域に応じた位置に低熱伝導部材を設けることができるピストンの製造方法およびピストンを提供することである。 In the technique disclosed in Patent Document 1, when the piston is viewed from the axial direction, the low heat conduction member is provided in a half region on the fuel injection valve side. However, since the fuel injection region differs depending on the mounting position of the fuel injection valve and the like, there is a possibility that the low heat conduction member cannot be provided in the fuel injection region.
The present invention has been focused on the above problems, and an object of the present invention is to provide a piston manufacturing method and a piston capable of providing a low heat conductive member at a position corresponding to the fuel injection region of the piston. .
　第一の発明の一実施形態では、内燃機関のピストンの製造方法において、アルミニウム合金よりも熱伝導率の低い材料である低熱伝導部形成材で形成された環状の低熱伝導部をピストン本体部の冠部のうち内燃機関の燃焼室側に形成する工程であって、内燃機関のシリンダ内におけるピストンの移動方向の直交断面における環状の低熱伝導部の内周縁よりも内側に低熱伝導部形成材よりも熱伝導率の高い材料で形成された非低熱伝導部を有するように低熱伝導部を形成する低熱伝導部形成工程を有するようにした。
  第二の発明の一実施形態では、内燃機関のピストンにおいて、ピストンの冠部の内燃機関の燃焼室側に設けられアルミニウム合金よりも熱伝導率の低い材料である低熱伝導部形成材で形成された環状の低熱伝導部と、環状の低熱伝導部の内周縁よりも内側に設けられ、低熱伝導部形成材よりも熱伝導率の高い材料で形成された非低熱伝導部と、を有するようにした。 In one embodiment of the first invention, in the method of manufacturing a piston of an internal combustion engine, an annular low heat conduction part formed of a low heat conduction part forming material, which is a material having a lower thermal conductivity than an aluminum alloy, is provided on the piston body part. A step of forming the crown portion on the combustion chamber side of the internal combustion engine, and a lower heat conduction portion forming material inside the inner peripheral edge of the annular low heat conduction portion in a cross section orthogonal to the moving direction of the piston in the cylinder of the internal combustion engine In addition, a low thermal conduction part forming step of forming a low thermal conduction part so as to have a non-low thermal conduction part made of a material having high thermal conductivity is provided.
In one embodiment of the second invention, the piston of the internal combustion engine is formed of a low heat conduction part forming material that is provided on the combustion chamber side of the internal combustion engine at the crown of the piston and has a lower thermal conductivity than the aluminum alloy. An annular low heat conduction part, and a non-low heat conduction part that is provided inside the inner peripheral edge of the annular low heat conduction part and formed of a material having a higher thermal conductivity than the low heat conduction part forming material. did.
　よって、本発明の一実施形態によれば、燃料噴射領域が冠部上で円環状となる内燃機関において、燃料噴射量域に対応した位置に低熱伝導部を設けることができる。 Therefore, according to one embodiment of the present invention, in the internal combustion engine in which the fuel injection region is annular on the crown, the low heat conduction portion can be provided at a position corresponding to the fuel injection amount region.
実施例1の内燃機関のピストンの斜視図である。1 is a perspective view of a piston of an internal combustion engine of Embodiment 1. FIG. 実施例1のピストンの製造工程を示すフローチャートである。3 is a flowchart showing manufacturing steps of the piston of Example 1. 実施例1の一次機械加工工程終了後のピストンを示す図である。FIG. 3 is a view showing a piston after completion of a primary machining process of Example 1. 実施例1の混合粉末充填工程終了後のピストンを示す図である。FIG. 3 is a view showing the piston after completion of the mixed powder filling step of Example 1. 実施例1の混合粉末押圧工程実施後のピストンを示す図である。FIG. 3 is a view showing the piston after execution of the mixed powder pressing step of Example 1. 実施例1の混合粉末押圧工程終了後のピストンを示す図である。FIG. 3 is a view showing the piston after the mixed powder pressing step of Example 1 is completed. 実施例1の二次機械加工工程終了後のピストンを示す図である。FIG. 3 is a view showing a piston after completion of the secondary machining process of the first embodiment. 実施例2のピストンの斜視図である。6 is a perspective view of a piston according to Embodiment 2. FIG. 実施例2のピストンの製造工程を示すフローチャートである。5 is a flowchart showing a manufacturing process of a piston of Example 2. 実施例2の一次機械加工工程終了後のピストンを示す図である。FIG. 6 is a view showing a piston after completion of a primary machining process of Example 2. 実施例2のプリフォームの斜視図である。5 is a perspective view of a preform of Example 2. FIG. 実施例2のプリフォーム配置工程終了後のピストンを示す図である。FIG. 5 is a view showing a piston after completion of a preform arranging step in Example 2. 実施例2のプリフォーム押圧工程実施時のピストンを示す図である。FIG. 6 is a view showing a piston when a preform pressing process of Example 2 is performed. 実施例2の押圧工程終了時のピストンを示す図である。FIG. 6 is a view showing a piston at the end of a pressing step in Example 2. 実施例2の押圧工程終了後のピストンを示す図である。FIG. 6 is a view showing a piston after completion of a pressing step in Example 2. 実施例2の二次機械加工工程終了後のピストンの形状を示す図である。FIG. 6 is a view showing the shape of a piston after the completion of the secondary machining process of Example 2. 実施例3のピストンの斜視図である。6 is a perspective view of a piston of Example 3. FIG. 実施例４の内燃機関のピストンの斜視図である。FIG. 6 is a perspective view of a piston of an internal combustion engine according to a fourth embodiment.
　〔実施例1〕
  ［ピストンの構成］
  図1は内燃機関のピストン1の斜視図である。ピストン1はアルミニウム合金を母材として形成されている。実施例１のピストン1は、筒内噴射式の内燃機関に用いられるものである。
  ピストン1は、略円柱状に形成されている。ピストン1の軸方向（ピストン1がシリンダ内で往復運動する方向）の燃焼室側の面（頂面）は冠部2を構成している。冠部2には低熱伝導部3が形成されている。低熱伝導部3はピストン1の軸方向に対して直交する断面において環状に形成されている。低熱伝導部3は、冠部2の最外周よりも内側に、冠部2の全周に渡って1つの環状に形成されている。低熱伝導部3は、アルミニウム合金よりも熱伝導率が低い材料により形成されている。低熱伝導部3の材料については後で詳述する。低熱伝導部3の内周側の素材はアルミニウム合金である。低熱伝導部3の内周側は非低熱伝導部2bを構成している。低熱伝導部3の外周縁の外側全周はアルミニウム合金で包囲されている。低熱伝導部3の外周縁の外側全周はアルミニウム合金で包囲されている。 Example 1
[Piston configuration]
FIG. 1 is a perspective view of a piston 1 of an internal combustion engine. The piston 1 is formed using an aluminum alloy as a base material. The piston 1 according to the first embodiment is used in a cylinder injection type internal combustion engine.
The piston 1 is formed in a substantially cylindrical shape. The surface (top surface) on the combustion chamber side in the axial direction of piston 1 (the direction in which piston 1 reciprocates within the cylinder) constitutes crown 2. A low heat conduction portion 3 is formed in the crown portion 2. The low heat conducting portion 3 is formed in an annular shape in a cross section orthogonal to the axial direction of the piston 1. The low heat conducting portion 3 is formed in a single ring over the entire circumference of the crown portion 2 inside the outermost circumference of the crown portion 2. The low heat conduction part 3 is formed of a material having a lower thermal conductivity than the aluminum alloy. The material of the low heat conduction part 3 will be described in detail later. The material on the inner peripheral side of the low heat conducting portion 3 is an aluminum alloy. The inner peripheral side of the low heat conducting portion 3 constitutes a non-low heat conducting portion 2b. The entire outer periphery of the outer peripheral edge of the low heat conducting portion 3 is surrounded by an aluminum alloy. The entire outer periphery of the outer peripheral edge of the low heat conducting portion 3 is surrounded by an aluminum alloy.
　ピストン1の外周面であって軸方向において燃焼室側はランド部8を構成している。ランド部8にはリング溝４が全周に渡って形成されている。リング溝４は、軸方向に離間して3箇所に形成されており、冠部2側から順にトップリング溝4a、セカンドリング溝4b、オイルリング溝4cを構成している。トップリング溝4a、セカンドリング溝4bにはそれぞれシリンダリングが係合される。オイルリング溝4cにはオイルリングが係合される。
  オイルリング溝4cよりも下側にはスカート部5が形成されている。スカート部5は、周方向に離間して2箇所に形成されている。スカート部5は、それぞれ対向する位置に形成されている。スカート部5の外周面は略円筒状に形成されている。冠部2、スカート部5、ランド部8により本体部9を構成している
  対向するスカート部5と略直交する位置に、スカート部5を挟んで離間した状態でボス部6が形成されている。ボス部6には、ピストン1にコネクティングロッドを回動可能に組み付けるためのピストンピンが挿入されるピン孔6aが形成されている。 On the outer peripheral surface of the piston 1 in the axial direction, the combustion chamber side forms a land portion 8. In the land portion 8, a ring groove 4 is formed over the entire circumference. The ring groove 4 is formed at three positions apart in the axial direction, and constitutes a top ring groove 4a, a second ring groove 4b, and an oil ring groove 4c in order from the crown portion 2 side. A cylinder ring is engaged with each of the top ring groove 4a and the second ring groove 4b. An oil ring is engaged with the oil ring groove 4c.
A skirt portion 5 is formed below the oil ring groove 4c. The skirt portion 5 is formed at two locations separated in the circumferential direction. The skirt portions 5 are formed at positions facing each other. The outer peripheral surface of the skirt portion 5 is formed in a substantially cylindrical shape. The crown part 2, the skirt part 5, and the land part 8 constitute the main body part 9. The boss part 6 is formed at a position substantially orthogonal to the opposing skirt part 5 with the skirt part 5 sandwiched therebetween. . The boss portion 6 is formed with a pin hole 6a into which a piston pin for assembling the connecting rod to the piston 1 so as to be rotatable is inserted.
　［ピストン製造工程］
  図2はピストン1の製造工程を示すフローチャートである。図３は一次機械加工工程後のピストン1を示す図である。図４は混合粉末充填工程後のピストン1を示す図である。図5は混合粉末押圧工程時のピストン1を示す図である。図6は混合粉末押圧工程後のピストン1を示す図である。図７は二次機械加工工程後のピストン1を示す図である。
  ステップS1はピストン1の鋳造工程である。ピストン鋳造工程では、アルミニウム合金によりピストン1の粗材を鋳造する。この工程で、本体部9が形成される。
  ステップS２は一次機械加工工程である（図3）。一次機械加工工程では、工作機械によりピストン1の粗材のランド部8の外径切削、スカート部5の外径切削、ボス部6の加工、ピン孔6aの加工、冠部2の環状溝2aの加工などを行う。環状溝2aは、冠部2に全周に渡って凹状の溝を加工することにより形成される。環状溝2aには、後の工程で低熱伝導部3の材料が充填される。なお、環状溝2aは鋳造工程において鋳抜きにより形成するようにしても良い。 [Piston manufacturing process]
FIG. 2 is a flowchart showing the manufacturing process of the piston 1. FIG. 3 shows the piston 1 after the primary machining process. FIG. 4 is a view showing the piston 1 after the mixed powder filling step. FIG. 5 is a view showing the piston 1 during the mixed powder pressing step. FIG. 6 is a view showing the piston 1 after the mixed powder pressing step. FIG. 7 shows the piston 1 after the secondary machining process.
Step S1 is a piston 1 casting process. In the piston casting process, the rough material of the piston 1 is cast with an aluminum alloy. In this step, the main body 9 is formed.
Step S2 is a primary machining process (FIG. 3). In the primary machining process, the outer diameter cutting of the land portion 8 of the rough material of the piston 1 by the machine tool, the outer diameter cutting of the skirt portion 5, the processing of the boss portion 6, the processing of the pin hole 6a, the annular groove 2a of the crown portion 2 Processing. The annular groove 2a is formed by processing a concave groove over the entire circumference in the crown portion 2. The annular groove 2a is filled with the material of the low heat conducting portion 3 in a later step. The annular groove 2a may be formed by casting in the casting process.
　ステップS3は混合粉末充填工程である（図4）。混合粉末充填工程では、低熱伝導部3の材料である混合粉末3aが環状溝2aに充填される。混合粉末3aは、ピストン1の本体部9の材料であるアルミニウム合金よりも熱伝導率が低い材料（低熱伝導材料）の粉末と、塑性流動により本体部9の材料であるアルミニウム合金と合金化または金属間化合物となり得る材料（接合材料）の粉末からなる。低熱伝導材料の例としては、ジルコニア、コージェライト、ムライト、シリコン、シリカ（二酸化ケイ素）、層状ケイ酸塩（例えばマイカ）、タルク、アルミナ系や窒化ケイ素系等の中実のセラミックケイ酸塩ガラス、アクリルガラス、有機ガラス、などが挙げられる。接合材料の例としては、アルミニウム、アルミニウム合金などが挙げられる。
  ステップS４は混合粉末押圧工程である（図5,6）。混合粉末押圧工程では、円筒ツール7により混合粉末3aを環状溝2a内に詰め込むように押圧しつつ、円筒ツール7を周方向に回転させる。これにより、接合材料が軟化し、撹拌される。そのため、低熱伝導材料を接合材料内に抱え込むことができる。また接合材料は、本体部9の材料であるアルミニウム合金と合金化、または金属間化合物を形成する。混合粉末押圧工程では摩擦攪拌接合と類似した手法を用いている。混合粉末押圧工程の後には、低熱伝導部3は本体部9の材料であるアルミニウム合金部分と一体になっている。また混合粉末押圧工程の後には、低熱伝導部3の表面には円筒ツール7により接合部材が撹拌されたときの撹拌軌跡が残る。低熱伝導部3は混合粉末3aの状態から体積が減少し、冠部2の表面に露出していない。 Step S3 is a mixed powder filling process (FIG. 4). In the mixed powder filling step, the mixed powder 3a, which is the material of the low heat conduction part 3, is filled into the annular groove 2a. The mixed powder 3a is alloyed with a powder of a material having a lower thermal conductivity (low thermal conductivity material) than an aluminum alloy that is a material of the main body 9 of the piston 1 and an aluminum alloy that is a material of the main body 9 by plastic flow. It consists of a powder of a material (joining material) that can be an intermetallic compound. Examples of low thermal conductivity materials include solid ceramic silicate glasses such as zirconia, cordierite, mullite, silicon, silica (silicon dioxide), layered silicate (eg mica), talc, alumina and silicon nitride , Acrylic glass, organic glass, and the like. Examples of the bonding material include aluminum and an aluminum alloy.
Step S4 is a mixed powder pressing step (FIGS. 5 and 6). In the mixed powder pressing step, the cylindrical tool 7 is rotated in the circumferential direction while pressing the mixed powder 3a into the annular groove 2a by the cylindrical tool 7. Thereby, the joining material is softened and stirred. Therefore, the low thermal conductive material can be held in the bonding material. The bonding material is alloyed with the aluminum alloy that is the material of the main body 9, or forms an intermetallic compound. In the mixed powder pressing step, a method similar to the friction stir welding is used. After the mixed powder pressing step, the low heat conducting portion 3 is integrated with the aluminum alloy portion that is the material of the main body portion 9. In addition, after the mixed powder pressing step, a stirring trajectory when the joining member is stirred by the cylindrical tool 7 remains on the surface of the low heat conducting portion 3. The volume of the low heat conductive portion 3 is reduced from the state of the mixed powder 3a and is not exposed on the surface of the crown portion 2.
　円筒ツール7の内径は、環状溝2aの内径（溝の径方向内側の側面の径）よりも若干小さく形成されている。円筒ツール7の外径は、環状溝2aの外径（溝の径方向外側の側面の径）よりも若干大きく形成されている。これにより、混合粉末押圧工程において円筒ツール7が環状溝2a以外の本体部9にオーバラップして当接することとなる。そのため、混合粉末3aが環状溝2aから漏れ出さないようにすることができる。また、混合粉末押圧工程において環状溝2aと隣接する本体部9も軟化し、混合粉末3aの接合材料と混ざり合うため、混合粉末押圧工程後は低熱伝導部3とピストン1の母材とは境目なく一体となっている。なお、ステップS3の混合粉末充填工程とステップS4の混合粉末押圧工程を低熱伝導部形成工程としている。
  ステップS5は熱処理加工である。熱処理加工では、混合粉末押圧工程が終了したピストン1に熱処理を施す。熱処理により、混合粉末押圧工程の際の塑性流動に伴う歪みを除去し、強度の均一化を行う。
  ステップS6は二次機械加工工程である（図7）。二次機械加工工程では、工作機械によりピストン1に仕上加工を施す。このとき、冠部2を切削し、低熱伝導部3は冠部2の表面に露出する。また二次機械加工工程において、リング溝4を形成する。 The inner diameter of the cylindrical tool 7 is slightly smaller than the inner diameter of the annular groove 2a (the diameter of the side surface on the radially inner side of the groove). The outer diameter of the cylindrical tool 7 is slightly larger than the outer diameter of the annular groove 2a (the diameter of the side surface on the radially outer side of the groove). Thereby, in the mixed powder pressing step, the cylindrical tool 7 overlaps and contacts the main body 9 other than the annular groove 2a. Therefore, the mixed powder 3a can be prevented from leaking from the annular groove 2a. In addition, since the main body 9 adjacent to the annular groove 2a is softened in the mixed powder pressing step and is mixed with the bonding material of the mixed powder 3a, the low heat conduction portion 3 and the base material of the piston 1 are the boundary after the mixed powder pressing step. It is not united. Note that the mixed powder filling process in step S3 and the mixed powder pressing process in step S4 are the low heat conduction part forming process.
Step S5 is a heat treatment process. In the heat treatment, the piston 1 after the mixed powder pressing step is heat treated. By heat treatment, the distortion caused by the plastic flow during the mixed powder pressing step is removed, and the strength is made uniform.
Step S6 is a secondary machining process (FIG. 7). In the secondary machining process, the piston 1 is finished by a machine tool. At this time, the crown portion 2 is cut, and the low heat conduction portion 3 is exposed on the surface of the crown portion 2. Further, the ring groove 4 is formed in the secondary machining process.
　［作用］
  ピストン1は体積が大きいため熱容量が大きく、ピストン1の温度は急上昇しない。またピストン1はアルミニウム合金製であるため、熱伝導率が高く冠部2においてシリンダ内の燃料ガスから受け取った熱は、ピストンリングやスカート部5からシリンダへ伝わる。そのため、ピストン1の温度上昇は緩やかである。
  実施例1のピストン1は筒内噴射式の内燃機関に用いられるものである。シリンダ内に向かって噴射された燃料はシリンダ内で蒸発するが、一部はピストン1の冠部2に衝突する。ピストン1の温度が十分に高いときには、燃料が冠部2に衝突した際に、燃料はピストン1から熱を受け取り、蒸発する。しかし、前述のようにピストン1は温度上昇が緩やかであるため、内燃機関始動時等においてはピストン1の温度が低く、冠部2上に蒸発しきれない燃料が液膜として残るおそれがある。冠部2上に残った燃料は、デポジットや、排気への未燃炭化水素の混入の原因となる。 [Action]
Since the piston 1 has a large volume, the heat capacity is large and the temperature of the piston 1 does not rise rapidly. Further, since the piston 1 is made of an aluminum alloy, heat conductivity is high, and heat received from the fuel gas in the cylinder at the crown portion 2 is transmitted from the piston ring or the skirt portion 5 to the cylinder. Therefore, the temperature rise of the piston 1 is gradual.
The piston 1 of the first embodiment is used for a cylinder injection internal combustion engine. The fuel injected into the cylinder evaporates in the cylinder, but part of it collides with the crown 2 of the piston 1. When the temperature of the piston 1 is sufficiently high, when the fuel collides with the crown 2, the fuel receives heat from the piston 1 and evaporates. However, as described above, since the temperature of the piston 1 is moderately increased, the temperature of the piston 1 is low when the internal combustion engine is started, and there is a possibility that fuel that cannot be evaporated on the crown portion 2 remains as a liquid film. The fuel remaining on the crown 2 causes deposits and contamination of unburned hydrocarbons into the exhaust.
　そこで実施例1では冠部2にピストン1を形成するアルミニウム合金よりも熱伝導率が低い低熱伝導部3を形成するようにした。これにより、低熱伝導部3において燃料ガスから受け取った熱は他の部分に伝達されにくく、低熱伝導部3の温度上昇を迅速にすることができる。そのため、低熱伝導部3に衝突した燃料は蒸発しやすくなる。
  また実施例1では、例えば燃料噴霧がピストン1の軸線とほぼ同軸上で円錐形に広がるタイプの内燃機関に対応して、低熱伝導部3を冠部2の径方向外側部分に環状となるように形成した。このため、燃料噴射領域が冠部2の径方向外側に存在するような内燃機関において、燃料噴射量域に対応した位置に低熱伝導部3を設けることができる。
  また実施例1では、ピストン1の冠部2に環状溝2aに混合粉末3aを充填し、混合粉末3aを円筒ツール7により、混合粉末3aを環状溝2a内に詰め込むように押圧しつつ周方向に回転させるようにした。円筒ツール7を用いて混合粉末押圧工程を行うことで、一度に環状の低熱伝導部3を形成することができる。 Therefore, in Example 1, the low thermal conductivity portion 3 having a lower thermal conductivity than the aluminum alloy that forms the piston 1 is formed in the crown portion 2. As a result, the heat received from the fuel gas in the low heat conducting section 3 is not easily transmitted to other parts, and the temperature rise of the low heat conducting section 3 can be accelerated. Therefore, the fuel that has collided with the low heat conducting section 3 is likely to evaporate.
Further, in the first embodiment, for example, in correspondence with an internal combustion engine of a type in which fuel spray spreads conically on the same axis as the axis of the piston 1, the low heat conduction portion 3 is formed in an annular shape at the radially outer portion of the crown portion 2. Formed. For this reason, in the internal combustion engine in which the fuel injection region exists on the radially outer side of the crown portion 2, the low heat conduction portion 3 can be provided at a position corresponding to the fuel injection amount region.
Further, in Example 1, the crown 2 of the piston 1 is filled with the mixed powder 3a in the annular groove 2a, and the mixed powder 3a is pressed by the cylindrical tool 7 so as to pack the mixed powder 3a into the annular groove 2a in the circumferential direction. It was made to rotate to. By performing the mixed powder pressing step using the cylindrical tool 7, the annular low heat conduction portion 3 can be formed at a time.
　また実施例1では、環状に形成した低熱伝導部3の内周側に本体部9のアルミニウム合金を有するようにした。これにより、低熱伝導部3の内周側を本体部9の材料であるアルミニウム合金以外を用いる必要がない。また、低熱伝導部3の内周縁よりも内側に本体部9の肉が存在するため、混合粉末押圧工程において低熱伝導部3の内側に混合粉末3aが逃げにくく、混合粉末3aに圧力をかけやすくなる。
  また実施例1では、環状溝2aの外周縁の外側全周が本体部9のアルミニウム合金で包囲されるようにした。これにより、低熱伝導部3の外周縁よりも外側に本体部9の肉が存在するため、混合粉末押圧工程において低熱伝導部3の外側に混合粉末3aが逃げにくく、混合粉末3aに圧力をかけやすくなる。
  また実施例1では、低熱伝導部3の形成材を粉体の混合粉末3aとした。これにより、環状溝2a内で接合材料と低熱伝導材料とが均一に混ざり合った状態で混合粉末押圧工程を行うことができ、低熱伝導部3を均一な材質とすることができる。 Further, in Example 1, the aluminum alloy of the main body portion 9 is provided on the inner peripheral side of the annular low heat conducting portion 3. Thereby, it is not necessary to use an inner peripheral side of the low heat conducting portion 3 other than the aluminum alloy that is the material of the main body portion 9. Further, since the meat of the main body 9 is present inside the inner peripheral edge of the low heat conduction part 3, the mixed powder 3a is difficult to escape inside the low heat conduction part 3 in the mixed powder pressing step, and it is easy to apply pressure to the mixed powder 3a. Become.
In Example 1, the entire outer periphery of the outer peripheral edge of the annular groove 2a is surrounded by the aluminum alloy of the main body 9. As a result, the meat of the main body 9 is present outside the outer peripheral edge of the low heat conduction part 3, so that the mixed powder 3a is difficult to escape outside the low heat conduction part 3 in the mixed powder pressing step, and pressure is applied to the mixed powder 3a. It becomes easy.
Further, in Example 1, the forming material of the low heat conducting portion 3 was the powder mixed powder 3a. Accordingly, the mixed powder pressing step can be performed in a state where the bonding material and the low heat conductive material are uniformly mixed in the annular groove 2a, and the low heat conductive portion 3 can be made of a uniform material.
　［効果］
  実施例1の効果を以下に列記する。
  (1) 内燃機関のピストン1の製造方法は、冠部2と、冠部2に設けられたスカート部5と、を有する本体部9をアルミニウム合金で形成する鋳造工程（本体部形成工程）と、アルミニウム合金よりも熱伝導率の低い材料である低熱伝導材料（低熱伝導部形成材）で形成された環状の低熱伝導部3を冠部2のうち内燃機関の燃焼室側に形成する工程であって、内燃機関のシリンダ内におけるピストン1の移動方向の直交断面における環状の低熱伝導部3の内周縁よりも内側に混合粉末3a（低熱伝導部形成材）よりも熱伝導率の高い材料で形成された非低熱伝導部2bを有するように低熱伝導部3を形成する低熱伝導部形成工程と、を有するようにした。
  このため、燃料噴射領域が冠部2の径方向外側に存在するような内燃機関において、燃料噴射量域に対応した位置に低熱伝導部3を設けることができる。 [effect]
The effects of Example 1 are listed below.
(1) A method for manufacturing a piston 1 of an internal combustion engine includes a casting step (main body portion forming step) in which a main body portion 9 having a crown portion 2 and a skirt portion 5 provided on the crown portion 2 is formed of an aluminum alloy. In the step of forming an annular low heat conduction part 3 formed of a low heat conduction material (low heat conduction part forming material), which is a material having a lower thermal conductivity than aluminum alloy, on the combustion chamber side of the internal combustion engine in the crown part 2 In the cylinder of the internal combustion engine, a material having a higher thermal conductivity than the mixed powder 3a (low heat conduction part forming material) inside the inner peripheral edge of the annular low heat conduction part 3 in the cross section orthogonal to the moving direction of the piston 1 A low thermal conduction part forming step of forming the low thermal conduction part 3 so as to have the formed non-low thermal conduction part 2b.
For this reason, in the internal combustion engine in which the fuel injection region exists on the radially outer side of the crown portion 2, the low heat conduction portion 3 can be provided at a position corresponding to the fuel injection amount region.
　(2) 低熱伝導部形成工程は、冠部2のうち燃焼室側に設けられた環状溝2a（凹部）に混合粉末3a（低熱伝導部形成材）を充填する混合粉末充填工程（充填工程）と、環状溝2a（凹部）内の混合粉末3a（低熱伝導部形成材）を回転する環状の円筒ツール7（ツール）で押圧する混合粉末押圧工程（押圧工程）と、を有する。
  円筒ツール7を用いて混合粉末押圧工程を行うことで、一度に環状の低熱伝導部3を形成することができる。
  (3) 非低熱伝導部2bは、本体部9のアルミニウム合金とした。
  これにより、低熱伝導部3の内周側をピストン1の素材であるアルミニウム合金以外を用いる必要がない。また、低熱伝導部3の内周縁よりも内側に本体部9の肉が存在するため、混合粉末押圧工程において低熱伝導部3の内側に混合粉末3aが逃げにくく、混合粉末3aに圧力をかけやすくなる。 (2) The low heat conduction part forming step is a mixed powder filling step (filling step) of filling the mixed powder 3a (low heat conduction part forming material) into the annular groove 2a (concave part) provided on the combustion chamber side of the crown part 2. And a mixed powder pressing step (pressing step) in which the mixed powder 3a (low heat conduction portion forming material) in the annular groove 2a (recessed portion) is pressed by the rotating cylindrical tool 7 (tool).
By performing the mixed powder pressing step using the cylindrical tool 7, the annular low heat conduction portion 3 can be formed at a time.
(3) The non-low heat conduction part 2b is made of an aluminum alloy of the main body part 9.
As a result, it is not necessary to use a material other than the aluminum alloy that is the material of the piston 1 on the inner peripheral side of the low heat conducting portion 3. Further, since the meat of the main body 9 is present inside the inner peripheral edge of the low heat conduction part 3, the mixed powder 3a is difficult to escape inside the low heat conduction part 3 in the mixed powder pressing step, and it is easy to apply pressure to the mixed powder 3a. Become.
　(4) 低熱伝導部形成工程は、冠部2のうち燃焼室側に設けられた環状溝2a（環状凹部）に混合粉末3a（低熱伝導部形成材）を充填する工程と、環状溝2a（環状凹部）内の混合粉末3a（低熱伝導部形成材）を回転する円筒ツール7（ツール）で押圧する混合粉末押圧工程（押圧工程）と、を有し、環状溝2a（環状凹部）は、環状溝2a（環状凹部）の外周縁の外側全周が本体部9のアルミニウム合金で包囲されるようにした。
  これにより、低熱伝導部3の外周縁よりも外側に本体部9の肉が存在するため、混合粉末押圧工程において低熱伝導部3の外側に混合粉末3aが逃げにくく、混合粉末3aに圧力をかけやすくなる。
  (5) 混合粉末3a（低熱伝導部形成材）を、粉体の混合材料とした。
  これにより、環状溝2a内で接合材料と低熱伝導材料とが均一に混ざり合った状態で混合粉末押圧工程を行うことができ、低熱伝導部3を均一な材質とすることができる。 (4) The low heat conduction part forming step includes a step of filling the annular groove 2a (annular recess) provided on the combustion chamber side of the crown 2 with the mixed powder 3a (low heat conduction part forming material), and the annular groove 2a ( A mixed powder pressing step (pressing step) for pressing the mixed powder 3a (low heat conduction portion forming material) in the annular recess) with a rotating cylindrical tool 7 (tool), and the annular groove 2a (annular recess) The entire outer periphery of the outer peripheral edge of the annular groove 2a (annular recess) is surrounded by the aluminum alloy of the main body 9.
As a result, the meat of the main body 9 is present outside the outer peripheral edge of the low heat conduction part 3, so that the mixed powder 3a is difficult to escape outside the low heat conduction part 3 in the mixed powder pressing step, and pressure is applied to the mixed powder 3a. It becomes easy.
(5) The mixed powder 3a (low heat conduction part forming material) was used as a powder mixed material.
Accordingly, the mixed powder pressing step can be performed in a state where the bonding material and the low heat conductive material are uniformly mixed in the annular groove 2a, and the low heat conductive portion 3 can be made of a uniform material.
　(6) 内燃機関のピストン1であって、アルミニウム合金で形成され、冠部2と、冠部2に設けられたスカート部5と、を有する本体部9と、冠部2の内燃機関の燃焼室側に設けられアルミニウム合金よりも熱伝導率の低い材料である混合粉末3a（低熱伝導部形成材）で形成された環状の低熱伝導部3と、環状の低熱伝導部3の内周縁よりも内側に設けられ、混合粉末3a（低熱伝導部形成材）よりも熱伝導率の高い材料で形成された非低熱伝導部2bと、を有する。
  このため、燃料噴射領域が冠部2の径方向外側に存在するような内燃機関において、燃料噴射量域に対応した位置に低熱伝導部3を設けることができる。 (6) A piston 1 of an internal combustion engine, which is made of an aluminum alloy and has a crown portion 2 and a main body portion 9 provided with a skirt portion 5 provided on the crown portion 2, and combustion of the crown portion 2 of the internal combustion engine An annular low thermal conduction part 3 formed of a mixed powder 3a (low thermal conduction part forming material), which is provided on the chamber side and has a lower thermal conductivity than an aluminum alloy, and an inner peripheral edge of the annular low thermal conduction part 3 A non-low heat conductive portion 2b provided on the inner side and formed of a material having higher thermal conductivity than the mixed powder 3a (low heat conductive portion forming material).
For this reason, in the internal combustion engine in which the fuel injection region exists on the radially outer side of the crown portion 2, the low heat conduction portion 3 can be provided at a position corresponding to the fuel injection amount region.
　〔実施例2〕
  実施例1のピストン1では、低熱伝導部3の外周縁の外側全周はアルミニウム合金で包囲されていた。実施例2では、低熱伝導部3の外周縁の外側全周が露出するように形成した。以下、実施例2のピストン1について説明するが、実施例1と同じ構成については同一の符号を付して説明を省略する。
  ［ピストンの構成］
  図8は実施例2のピストン1の斜視図である。ピストン1の冠部2には低熱伝導部3が形成されている。低熱伝導部3はピストン1の軸方向に対して直交する断面において環状に形成されている。低熱伝導部3は、冠部2の最外周に冠部2の全周に渡って1つの環状に形成されている。低熱伝導部3は、アルミニウム合金よりも熱伝導率が低い材料により形成されている。低熱伝導部3の内周側の素材はアルミニウム合金である。低熱伝導部3の内周側は非低熱伝導部2bを構成している。低熱伝導部3は外周面が露出するように設けられている。 (Example 2)
In the piston 1 of Example 1, the entire outer periphery of the outer peripheral edge of the low heat conducting portion 3 was surrounded by an aluminum alloy. In Example 2, it was formed so that the entire outer periphery of the outer peripheral edge of the low thermal conductive portion 3 was exposed. Hereinafter, the piston 1 of the second embodiment will be described, but the same components as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.
[Piston configuration]
FIG. 8 is a perspective view of the piston 1 of the second embodiment. A low heat conduction portion 3 is formed in the crown portion 2 of the piston 1. The low heat conducting portion 3 is formed in an annular shape in a cross section orthogonal to the axial direction of the piston 1. The low heat conducting portion 3 is formed in a single ring over the entire circumference of the crown portion 2 on the outermost circumference of the crown portion 2. The low heat conduction part 3 is formed of a material having a lower thermal conductivity than the aluminum alloy. The material on the inner peripheral side of the low heat conducting portion 3 is an aluminum alloy. The inner peripheral side of the low heat conducting portion 3 constitutes a non-low heat conducting portion 2b. The low heat conducting portion 3 is provided so that the outer peripheral surface is exposed.
　［ピストン製造工程］
  図9はピストン1の製造工程を示すフローチャートである。図10は一次機械加工工程終了後のピストン1を示す図である。図11はプリフォーム3bの斜視図である。図12はプリフォーム配置工程終了後のピストン1を示す図である。図13はプリフォーム押圧工程実施時のピストン1を示す図である。図14は押圧工程終了時のピストン1を示す図である。図15は押圧工程終了後のピストン1を示す図である。図16は二次機械加工工程終了後のピストン1の形状を示す図である。
  ステップS11はピストン1の鋳造工程である。ピストン鋳造工程では、アルミニウム合金によりピストン1の粗材を鋳造する。この工程で、本体部9が形成される。
  ステップS12は一次機械加工工程である。一次機械加工工程では、工作機械によりピストン1の粗材のランド部の外径切削、スカート部5の外径切削、ボス部6の加工、ピン孔6aの加工、冠部2の環状溝2aの加工などを行う。環状溝2aは、冠部2に全周に渡って凹状の溝を加工することにより形成される。環状溝2aには後の工程において低熱伝導部3が設けられる。環状溝2aは、低熱伝導部3が設けられた後に、外周側が露出するように形成される。なお、環状溝2aは鋳造工程において鋳抜きにより形成するようにしても良い。一次機械加工工程終了後、ピストン1は固定治具10内に収容される。固定治具10は、円筒形状に形成されている。固定治具10の内径は、ピストン1のランド部8の外径とほぼ同じ大きさであって、内周にピストン1を収容可能に形成されている。また固定治具10の高さは、ピストン1の軸方向の高さとほぼ同じ高さに形成されている。 [Piston manufacturing process]
FIG. 9 is a flowchart showing the manufacturing process of the piston 1. FIG. 10 is a view showing the piston 1 after completion of the primary machining process. FIG. 11 is a perspective view of the preform 3b. FIG. 12 is a view showing the piston 1 after completion of the preform arranging step. FIG. 13 is a view showing the piston 1 when the preform pressing process is performed. FIG. 14 shows the piston 1 at the end of the pressing step. FIG. 15 is a view showing the piston 1 after completion of the pressing step. FIG. 16 is a view showing the shape of the piston 1 after completion of the secondary machining process.
Step S11 is a casting process of the piston 1. In the piston casting process, the rough material of the piston 1 is cast with an aluminum alloy. In this step, the main body 9 is formed.
Step S12 is a primary machining process. In the primary machining process, the outer diameter of the rough land of the piston 1 is cut by the machine tool, the outer diameter of the skirt 5 is cut, the boss 6 is processed, the pin hole 6a is processed, and the annular groove 2a of the crown 2 is formed. Perform processing. The annular groove 2a is formed by processing a concave groove over the entire circumference in the crown portion 2. The annular groove 2a is provided with a low heat conduction portion 3 in a later step. The annular groove 2a is formed so that the outer peripheral side is exposed after the low heat conducting portion 3 is provided. The annular groove 2a may be formed by casting in the casting process. After completion of the primary machining process, the piston 1 is accommodated in the fixing jig 10. The fixing jig 10 is formed in a cylindrical shape. The inner diameter of the fixing jig 10 is substantially the same as the outer diameter of the land portion 8 of the piston 1 and is formed so that the piston 1 can be accommodated on the inner periphery. The height of the fixing jig 10 is substantially the same as the height of the piston 1 in the axial direction.
　ステップS13は圧粉体形成工程である。実施例1では混合粉末3aを環状溝2aに充填するようにしたが、実施例2では低熱伝導材料と接合材料から環状のプリフォーム3bを形成する。プリフォーム3bは、粉末状の低熱伝導材料と接合材料を混ぜあわせ加圧して圧粉体として形成される。
  ステップS14は圧粉体熱処理工程である。圧粉体としてプリフォーム3bを形成した後に、プリフォーム3bを加熱する。これにより、粒子状の低熱伝導材料と接合材料の表面を覆っていた酸化膜が崩れ、粒子同士が接着しやすくなる。そのため、プリフォーム3bが崩れにくくなる。
  ステップS15はプリフォーム配置工程である。プリフォーム工程では、プリフォーム3bを環状溝2a内に配置する。
  ステップS16はプリフォーム押圧工程である。プリフォーム押圧工程では、円筒ツール7によりプリフォーム3bを環状溝2a内に詰め込むように押圧しつつ、円筒ツール7を周方向に回転させる。これにより、接合材料が軟化し、撹拌される。そのため、低熱伝導材料を接合材料内に抱え込むことができる。また接合材料は、本体部9の材料であるアルミニウム合金と合金化、または金属間化合物を形成する。混合粉末押圧工程の後には、低熱伝導部3は本体部9の材料であるアルミニウム合金部分と一体になっている。また混合粉末押圧工程の後には、低熱伝導部3の表面には円筒ツール7により接合部材が撹拌されたときの撹拌軌跡が残る。低熱伝導部3は混合粉末3aの状態から体積が減少し、冠部2の表面に露出していない。 Step S13 is a green compact forming process. In the first embodiment, the mixed powder 3a is filled in the annular groove 2a. However, in the second embodiment, the annular preform 3b is formed from the low heat conductive material and the bonding material. The preform 3b is formed as a green compact by mixing and pressing a powdery low thermal conductive material and a bonding material.
Step S14 is a green compact heat treatment process. After forming the preform 3b as a green compact, the preform 3b is heated. As a result, the particulate low thermal conductive material and the oxide film covering the surface of the bonding material are broken, and the particles are easily bonded to each other. Therefore, the preform 3b is not easily collapsed.
Step S15 is a preform placement process. In the preform process, the preform 3b is disposed in the annular groove 2a.
Step S16 is a preform pressing process. In the preform pressing step, the cylindrical tool 7 is rotated in the circumferential direction while pressing the preform 3b so as to be packed in the annular groove 2a. Thereby, the joining material is softened and stirred. Therefore, the low thermal conductive material can be held in the bonding material. The bonding material is alloyed with the aluminum alloy that is the material of the main body 9, or forms an intermetallic compound. After the mixed powder pressing step, the low heat conducting portion 3 is integrated with the aluminum alloy portion that is the material of the main body portion 9. In addition, after the mixed powder pressing step, a stirring trajectory when the joining member is stirred by the cylindrical tool 7 remains on the surface of the low heat conducting portion 3. The volume of the low heat conductive portion 3 is reduced from the state of the mixed powder 3a and is not exposed on the surface of the crown portion 2.
　円筒ツール7の内径は、環状溝2aの内径（溝の径方向内側の側面の径）とほぼ同じ大きさに形成されている。円筒ツール7の外径は、ピストン1のランド部8の外径とほぼ同じ大きさに形成されている。実施例2のプリフォーム3bは実施例1の混合粉末3aと異なり圧粉体であるため、環状溝2aから漏れ出すおそれが少ない。そのため、実施例1と異なり、円筒ツール7の幅を環状溝2aの幅よりも大きくして、環状溝2a以外の本体部9とオーバラップして当接させる必要はない。なお、ステップS15のプリフォーム配置工程とステップS16のプリフォーム押圧工程を低熱伝導部形成工程としている。
  ステップS17は熱処理加工である。熱処理加工では、プリフォーム押圧工程が終了したピストン1に熱処理を施す。熱処理により、プリフォーム押圧工程の際の塑性流動に伴う歪みを除去し、強度の均一化を行う。
  ステップS18は二次機械加工工程である。二次機械加工工程では、工作機械によりピストン1に仕上加工を施す。このとき、冠部2を切削し、低熱伝導部3は冠部2の表面に露出する。また二次機械加工工程において、リング溝4を形成する。トップリング溝4aは低熱伝導部3の外周面に形成されている。 The inner diameter of the cylindrical tool 7 is formed to be approximately the same as the inner diameter of the annular groove 2a (the diameter of the side surface on the radially inner side of the groove). The outer diameter of the cylindrical tool 7 is formed to be approximately the same as the outer diameter of the land portion 8 of the piston 1. Unlike the mixed powder 3a of Example 1, the preform 3b of Example 2 is a green compact, and therefore there is little risk of leakage from the annular groove 2a. Therefore, unlike the first embodiment, it is not necessary to make the width of the cylindrical tool 7 larger than the width of the annular groove 2a so as to overlap and contact the main body 9 other than the annular groove 2a. Note that the preform placement step in step S15 and the preform pressing step in step S16 are the low heat conduction portion forming step.
Step S17 is a heat treatment process. In the heat treatment, the piston 1 that has undergone the preform pressing step is subjected to heat treatment. By heat treatment, the strain associated with the plastic flow during the preform pressing step is removed, and the strength is made uniform.
Step S18 is a secondary machining process. In the secondary machining process, the piston 1 is finished by a machine tool. At this time, the crown portion 2 is cut, and the low heat conduction portion 3 is exposed on the surface of the crown portion 2. Further, the ring groove 4 is formed in the secondary machining process. The top ring groove 4a is formed on the outer peripheral surface of the low heat conducting portion 3.
　［効果］
  実施例2の効果を以下に列記する。
  (7) 低熱伝導部3が外周側に露出するように低熱伝導部3の外周縁よりも外側の本体部を切削除去する一次機械加工（外周部除去工程）を有するようにした。
  これにより、ピストン1の冠面2の最外周側に低熱伝導部3を設けることができる。そのため、燃料噴射領域が冠部2の最外周側に存在するような内燃機関において、燃料噴射量域に対応した位置に低熱伝導部3を設けることができる。
  (8) プリフォーム3b（低熱伝導部形成材）は、アルミニウム合金よりも硬度の高い材料であって、低熱伝導部形成工程は、低熱伝導部3がピストン1の外周側に露出するように行われ、低熱伝導部3の外周側にピストンリングが挿入されるトップリング溝4aを形成する二次機械加工工程（リング溝形成工程）を更に有するようにした。
  これにより、トップリング溝4aの強度向上を図ることができる。 [effect]
The effects of Example 2 are listed below.
(7) Primary machining (peripheral part removing step) for cutting and removing the main body part outside the outer peripheral edge of the low heat conductive part 3 so that the low heat conductive part 3 is exposed to the outer peripheral side is provided.
Thereby, the low heat conduction part 3 can be provided on the outermost peripheral side of the crown surface 2 of the piston 1. Therefore, in the internal combustion engine in which the fuel injection region exists on the outermost peripheral side of the crown portion 2, the low heat conduction portion 3 can be provided at a position corresponding to the fuel injection amount region.
(8) The preform 3b (low heat conduction part forming material) is a material having a hardness higher than that of the aluminum alloy, and the low heat conduction part forming step is performed so that the low heat conduction part 3 is exposed to the outer peripheral side of the piston 1. In addition, a secondary machining step (ring groove forming step) for forming the top ring groove 4a into which the piston ring is inserted on the outer peripheral side of the low heat conducting portion 3 is further provided.
Thereby, the strength of the top ring groove 4a can be improved.
　(9) 低熱伝導部形成工程は、冠部2のうち燃焼室側の最外周部に設けられた環状溝2a（凹部）にプリフォーム3b（低熱伝導部形成材）を充填するプリフォーム設定工程（充填工程）と、環状溝2a（凹部）内のプリフォーム3b（低熱伝導部形成材）を回転する円筒ツール7（ツール）で押圧するプリフォーム押圧工程（押圧工程）と、を有し、プリフォーム押圧工程（押圧工程）は、本体部9の外周側を固定治具10（型）で包囲した状態で行われるようにした。
  これにより、低熱伝導部3より外周側に冠部2の肉が存在しない場合であっても、プリフォーム押圧工程時に固定治具10によりプリフォーム3の逃げを抑制することができる。
  (10) 低熱伝導部形成工程は、プリフォーム3b（低熱伝導部形成材）である粉体の混合材料を加圧した圧粉体を形成する圧粉体形成工程（圧粉工程）と、冠部2のうち燃焼室側に設けられた環状溝2a（凹部）に圧粉体を配置するプリフォーム配置工程（配置工程）と、を有するようにした。
  これにより、プリフォーム押圧工程において環状溝2aからプリフォーム3bを逃げにくくすることができる。 (9) The low heat conduction part forming step is a preform setting step in which the annular groove 2a (concave part) provided in the outermost peripheral part on the combustion chamber side of the crown part 2 is filled with the preform 3b (low heat conduction part forming material). (Filling step) and a preform pressing step (pressing step) for pressing the preform 3b (low heat conduction portion forming material) in the annular groove 2a (concave portion) with a rotating cylindrical tool 7 (tool), The preform pressing step (pressing step) was performed in a state where the outer peripheral side of the main body 9 was surrounded by the fixing jig 10 (mold).
Thereby, even when the crown portion 2 does not have the meat on the outer peripheral side from the low heat conducting portion 3, it is possible to suppress the escape of the preform 3 by the fixing jig 10 during the preform pressing step.
(10) The low thermal conduction part forming process includes a green compact forming process (compacting process) for forming a green compact obtained by pressing a powder mixed material that is a preform 3b (low thermal conductive part forming material), a crown A preform arranging step (arranging step) in which the green compact is arranged in an annular groove 2a (concave portion) provided on the combustion chamber side of the portion 2.
This makes it difficult for the preform 3b to escape from the annular groove 2a in the preform pressing step.
　(11) 低熱伝導部形成工程は、圧粉体形成工程（圧粉工程）後でかつプリフォーム配置工程（配置工程）前に行われるプリファーム熱処理工程（加熱処理工程）を更に更に有するようにした。
  これにより、プリフォーム3bを崩れにくくすることができ、プリフォーム押圧工程においてプリフォーム3bが逃げにくくすることができる。
  (12) 低熱伝導部形成工程は、冠部2のうち燃焼室側に設けられた環状溝2a（凹部）にプリフォーム3b（低熱伝導部形成材）を充填するプリフォーム配置工程（充填工程）と、環状溝2a（凹部）内のプリフォーム3b（低熱伝導部形成材）を回転する円筒ツール7（ツール）で押圧するプリフォーム押圧工程（押圧工程）と、を有し、プリフォーム押圧工程（押圧工程）は、本体部9の外周側を固定治具10（型）で包囲した状態で行われるようにした。
  これにより、プリフォーム押圧工程においてピストン1の変形を抑制することができる。
  (13) プリフォーム3b（低熱伝導部形成材）は、アルミニウム合金よりも硬度の高い材料であって、冠部2は、冠部2の外周側に設けられピストンリングが挿入されるトップリング溝4a（リング溝）を有し、低熱伝導部3は、トップリング溝4a（リング溝）を含む範囲に設けられるようにした。
  これにより、トップリング溝4aの強度向上を図ることができる。 (11) The low thermal conduction part forming step further includes a pre-farm heat treatment step (heat treatment step) performed after the green compact formation step (compact step) and before the preform placement step (placement step). did.
Thereby, the preform 3b can be made difficult to collapse, and the preform 3b can be made difficult to escape in the preform pressing step.
(12) The low heat conduction portion forming step is a preform arrangement step (filling step) in which the annular groove 2a (concave portion) provided on the combustion chamber side of the crown portion 2 is filled with the preform 3b (low heat conduction portion forming material). And a preform pressing step (pressing step) for pressing the preform 3b (low heat conduction portion forming material) in the annular groove 2a (concave portion) with a rotating cylindrical tool 7 (tool), and a preform pressing step The (pressing step) was performed in a state where the outer peripheral side of the main body 9 was surrounded by the fixing jig 10 (mold).
Thereby, deformation of the piston 1 can be suppressed in the preform pressing step.
(13) The preform 3b (low heat conduction portion forming material) is a material having a hardness higher than that of the aluminum alloy, and the crown portion 2 is provided on the outer peripheral side of the crown portion 2 and is a top ring groove into which a piston ring is inserted. It has 4a (ring groove), and the low heat conduction part 3 is provided in a range including the top ring groove 4a (ring groove).
Thereby, the strength of the top ring groove 4a can be improved.
　〔実施例3〕
  実施例1では低熱伝導部3と冠部2の全周に渡って1つの環状に形成していた。実施例3では低熱伝導部3を複数の環状に形成するようにした。以下、実施例3のピストン1について説明するが、実施例1と同じ構成については同一の符号を付して説明を省略する。
  図17は実施例3のピストン1の斜視図である。ピストン1の冠部2には低熱伝導部3が形成されている。低熱伝導部3はピストン1の軸方向に対して直交する断面において環状に形成されている。低熱伝導部3は複数（実施例3では8個）形成され、冠部2の周方向に並んでいる。低熱伝導部3は、アルミニウム合金よりも熱伝導率が低い材料により形成されている。低熱伝導部3の内周側の素材はアルミニウム合金である。低熱伝導部3の内周側は非低熱伝導部2bを構成している。 Example 3
In Example 1, it was formed in a single ring over the entire circumference of the low thermal conductivity portion 3 and the crown portion 2. In Example 3, the low heat conductive portion 3 is formed in a plurality of annular shapes. Hereinafter, the piston 1 of the third embodiment will be described, but the same components as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.
FIG. 17 is a perspective view of the piston 1 of the third embodiment. A low heat conduction portion 3 is formed in the crown portion 2 of the piston 1. The low heat conducting portion 3 is formed in an annular shape in a cross section orthogonal to the axial direction of the piston 1. A plurality of low heat conduction portions 3 (eight in the third embodiment) are formed and arranged in the circumferential direction of the crown portion 2. The low heat conduction part 3 is formed of a material having a lower thermal conductivity than the aluminum alloy. The material on the inner peripheral side of the low heat conducting portion 3 is an aluminum alloy. The inner peripheral side of the low heat conducting portion 3 constitutes a non-low heat conducting portion 2b.
　冠部2に低熱伝導部3を形成する際には、実施例1と同様に環状溝2aを形成し、環状溝2aに混合粉末3aを充填した後に円筒ツール7により混合粉末3aを押圧するようにして形成すれば良い。また実施例2と同様に環状溝2aにプリフォーム3bを配置するようにしても良い。
  混合粉末3aまたはプリフォーム3bを押圧する際には、1つの円筒ツール7により押圧工程を8回行うようにすれば良い。また8個の円筒ツール7により押圧工程を1回行うようにしても良い。いずれの方法であっても、円筒ツール7の回転中心がシリンダ内のピストン1の移動方向の直交断面において、複数個存在する。実施例3では1つの低熱伝導部3の大きさが小さいため、円筒ツール7も小さくすることができる。そのため、円筒ツール7による混合粉末3aまたはプリフォーム3bの押圧力を抑えることができ、押圧工程におけるピストン1の変形を抑制することができる。 When forming the low thermal conductivity portion 3 in the crown portion 2, the annular groove 2a is formed in the same manner as in Example 1, and the mixed powder 3a is pressed by the cylindrical tool 7 after filling the annular groove 2a with the mixed powder 3a. May be formed. Similarly to the second embodiment, the preform 3b may be disposed in the annular groove 2a.
When pressing the mixed powder 3a or the preform 3b, the pressing process may be performed eight times with one cylindrical tool 7. Further, the pressing process may be performed once by the eight cylindrical tools 7. In any method, there are a plurality of rotation centers of the cylindrical tool 7 in a cross section orthogonal to the moving direction of the piston 1 in the cylinder. In the third embodiment, since the size of one low heat conducting portion 3 is small, the cylindrical tool 7 can also be made small. Therefore, the pressing force of the mixed powder 3a or the preform 3b by the cylindrical tool 7 can be suppressed, and the deformation of the piston 1 in the pressing process can be suppressed.
　［効果］
  (14) 低熱伝導部形成工程は、冠部2のうち燃焼室側に設けられた環状溝2a（凹部）に混合粉末3a（低熱伝導部形成材）を充填する混合粉末充填（充填工程）と、環状溝2a（凹部）内の混合粉末3a（低熱伝導部形成材）を回転する円筒ツール7（ツール）で押圧する混合粉末押圧工程（押圧工程）と、を有し、混合粉末押圧工程（押圧工程）は、円筒ツール7（ツール）の回転中心がピストン1の移動方向の直交断面において、複数個存在するように行われるようにした。
  これにより、円筒ツール7を小さくすることができるため、混合粉末押圧工程における円筒ツール7による混合粉末3aの押圧力を抑えることができる。そのため、ピストン1の変形を抑制することができる。 [effect]
(14) The low heat conduction part forming step is a mixed powder filling (filling step) in which the mixed powder 3a (low heat conduction part forming material) is filled in the annular groove 2a (concave part) provided on the combustion chamber side of the crown part 2. A mixed powder pressing step (pressing step) for pressing the mixed powder 3a (low heat conduction portion forming material) in the annular groove 2a (recessed portion) with a rotating cylindrical tool 7 (tool), and a mixed powder pressing step ( The pressing step) is performed so that there are a plurality of rotation centers of the cylindrical tool 7 (tool) in a cross section orthogonal to the moving direction of the piston 1.
Thereby, since the cylindrical tool 7 can be made small, the pressing force of the mixed powder 3a by the cylindrical tool 7 in the mixed powder pressing step can be suppressed. Therefore, deformation of the piston 1 can be suppressed.
　(15) 混合粉末押圧工程（押圧工程）は、円筒ツール7（ツール）で混合粉末3a（低熱伝導部形成材）を押圧する工程が複数回行われるようにした。
  これにより、円筒ツール7により混合粉末3aに効率的に圧をかけることができ、低熱伝導部3の密着性を向上させることができる。
  (16) 低熱伝導部形成工程は、冠部2のうち燃焼室側に設けられた環状溝2a（凹部）に混合粉末3a（低熱伝導部形成材）を充填する混合粉末充填工程（充填工程）と、環状溝2a（凹部）内の混合粉末3a（低熱伝導部形成材）を回転する複数の円筒ツール7（ツール）で同時に押圧する混合粉末押圧工程（押圧工程）と、を有するようにした。
  これにより、混合粉末押圧工程において環状溝2a同士の間のピストン1の肉が逃げにくく、円筒ツール7により混合粉末3aに圧をかけやすくすることができる。
  (17) 低熱伝導部3は、ピストン1の移動方向の直交断面において、撹拌中心周りに混合粉末3a（低熱伝導形成部材）が撹拌された撹拌軌跡を有する被撹拌部を複数有するようにした。
  これにより、低熱伝導部3を複数形成することができ、燃料噴射領域に応じて適切な位置に適切な形状の低熱伝導部3を形成することができる。 (15) In the mixed powder pressing step (pressing step), the step of pressing the mixed powder 3a (low heat conduction portion forming material) with the cylindrical tool 7 (tool) is performed a plurality of times.
Thereby, the cylindrical tool 7 can efficiently apply pressure to the mixed powder 3a, and the adhesion of the low heat conducting section 3 can be improved.
(16) The low heat conduction part forming step is a mixed powder filling step (filling step) of filling the mixed powder 3a (low heat conduction part forming material) into the annular groove 2a (concave part) provided on the combustion chamber side of the crown part 2. And a mixed powder pressing step (pressing step) in which the mixed powder 3a (low heat conduction portion forming material) in the annular groove 2a (recessed portion) is simultaneously pressed by a plurality of rotating cylindrical tools 7 (tool). .
Thereby, in the mixed powder pressing step, the meat of the piston 1 between the annular grooves 2a is difficult to escape, and the cylindrical tool 7 can easily apply pressure to the mixed powder 3a.
(17) The low heat conduction section 3 has a plurality of parts to be stirred having a stirring locus in which the mixed powder 3a (low heat conduction forming member) is stirred around the stirring center in a cross section orthogonal to the moving direction of the piston 1.
As a result, a plurality of low heat conduction parts 3 can be formed, and the low heat conduction part 3 having an appropriate shape can be formed at an appropriate position in accordance with the fuel injection region.
　〔実施例4〕
  実施例1では低熱伝導部3と冠部2の全周に渡って1つの環状に形成していた。実施例4では実施例1と同様に形成した環状の低熱伝導部3の内周側に、さらに第2低熱伝導部11を形成するようにした。以下、実施例4のピストン1について説明するが、実施例1と同じ構成については同一の符号を付して説明を省略する。
  図18は内燃機関のピストン1の斜視図である。ピストン1の冠部2には低熱伝導部3および第2低熱伝導部11が形成されている。低熱伝導部3は実施例1と同様に冠部2の全周に渡って1つの環状に形成されている。冠部2の中心部分には、円状の第2低熱伝導部11が形成されている。低熱伝導部3と第2低熱伝導部11との間には非低熱伝導部2bが設けられている。非低熱伝導部2bは本体部9の一部であり、アルミニウム合金により形成されている。 (Example 4)
In Example 1, it was formed in a single ring over the entire circumference of the low thermal conductivity portion 3 and the crown portion 2. In Example 4, the second low heat conduction part 11 is further formed on the inner peripheral side of the annular low heat conduction part 3 formed in the same manner as in Example 1. Hereinafter, the piston 1 of the fourth embodiment will be described, but the same components as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.
FIG. 18 is a perspective view of the piston 1 of the internal combustion engine. A low heat conduction portion 3 and a second low heat conduction portion 11 are formed in the crown portion 2 of the piston 1. The low heat conducting portion 3 is formed in a single ring over the entire circumference of the crown portion 2 as in the first embodiment. A circular second low heat conduction portion 11 is formed in the central portion of the crown portion 2. A non-low heat conduction part 2b is provided between the low heat conduction part 3 and the second low heat conduction part 11. The non-low heat conduction part 2b is a part of the main body part 9, and is formed of an aluminum alloy.
　冠部2に低熱伝導部3を形成する際には、実施例1と同様に環状溝2aを形成し、環状溝2aに混合粉末3aを充填した後に円筒ツール7により混合粉末3aを押圧するようにして形成すれば良い。冠部2に第2低熱伝導部11を形成する際にも、環状溝2aに代えて円筒状の凹部を形成し、この凹部に混合粉末3aを充填した後に円筒状の凹部の形状に合わせて形成した円柱状のツールにより混合粉末3aを押圧するようにして形成すれば良い。また実施例2と同様に混合粉末3aに代えて、プリフォーム3bを配置するようにしても良い。
  また低熱伝導部3および第2低熱伝導部11を円筒ツール7や円柱状のツールを用いて一度に押圧するのではなく、環状溝2aの幅や円筒状の凹部の径よりも小さい径を有するツールを用いて、ツールを移動させながら混合粉末3aやプリフォーム3bを押圧するようにしても良い。 When forming the low thermal conductivity portion 3 in the crown portion 2, the annular groove 2a is formed in the same manner as in Example 1, and the mixed powder 3a is pressed by the cylindrical tool 7 after filling the annular groove 2a with the mixed powder 3a. May be formed. When forming the second low thermal conductivity portion 11 in the crown portion 2, a cylindrical recess is formed instead of the annular groove 2a, and after the mixed powder 3a is filled in this recess, it is matched with the shape of the cylindrical recess. What is necessary is just to form so that the mixed powder 3a may be pressed with the formed cylindrical tool. Further, a preform 3b may be disposed instead of the mixed powder 3a as in the second embodiment.
In addition, the low heat conduction part 3 and the second low heat conduction part 11 are not pressed at once using the cylindrical tool 7 or the columnar tool, but have a diameter smaller than the width of the annular groove 2a and the diameter of the cylindrical recess. You may make it press the mixed powder 3a and the preform 3b, moving a tool using a tool.
　［効果］
  (18) 混合粉末押圧工程（押圧工程）は、混合粉末3a（低熱伝導部形成材）を押圧する工程がツールを移動させながら行われるようにした。
  これにより、低熱伝導部3の形状に応じてツールを用意する必要がない。また連続した形状の低熱伝導部3を形成することができる。 [effect]
(18) In the mixed powder pressing step (pressing step), the step of pressing the mixed powder 3a (low heat conduction portion forming material) is performed while moving the tool.
Thereby, it is not necessary to prepare a tool according to the shape of the low heat conduction part 3. In addition, a continuous low heat conducting portion 3 can be formed.
　〔他の実施例〕
  以上、本発明を実施例1～実施例4に基づいて説明してきたが、各発明の具体的な構成は実施例1～実施例4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。
  実施例1では混合粉末3aを環状溝2aに充填するようにしたが、実施例2と同様にプリフォーム3bを環状溝2aに配置するようにしても良い。
  実施例2ではプリフォーム3bを環状溝2aに配置するようにしたが、実施例2と同様に混合粉末3aを環状溝2aに充填するようにしても良い。
  実施例1～実施例3では、円筒ツール7により混合粉末3aまたはプリフォーム3bを押圧するようにしていたが、環状溝2aの幅よりも小さい径を有するツールを用いて、ツールを移動させながら混合粉末3aやプリフォーム3bを押圧するようにしても良い。
  実施例1～実施例4では、低熱伝導部3の内周側の非低熱伝導部2bを本体部9の一部であり、アルミニウム合金により形成するようにした。非低熱伝導部2bは本体部9とは別の材料により形成するようにしても良い。 [Other Examples]
As described above, the present invention has been described based on the first to fourth embodiments. However, the specific configuration of each invention is not limited to the first to fourth embodiments, and does not depart from the gist of the present invention. Such design changes are included in the present invention.
In the first embodiment, the mixed powder 3a is filled in the annular groove 2a. However, as in the second embodiment, the preform 3b may be disposed in the annular groove 2a.
In the second embodiment, the preform 3b is disposed in the annular groove 2a. However, as in the second embodiment, the mixed powder 3a may be filled in the annular groove 2a.
In Examples 1 to 3, the mixed powder 3a or the preform 3b was pressed by the cylindrical tool 7, but using a tool having a diameter smaller than the width of the annular groove 2a, the tool was moved. The mixed powder 3a and the preform 3b may be pressed.
In Examples 1 to 4, the non-low heat conduction part 2b on the inner peripheral side of the low heat conduction part 3 is a part of the main body part 9, and is formed of an aluminum alloy. The non-low heat conduction part 2b may be formed of a material different from that of the main body part 9.
　また実施例1～実施例4の低熱伝導材料および接合材料の形状は、粉末状に限らず、フレーク状やチップ状のものであっても良い。
  また低熱伝導材料は、シリカを主成分とする微細多孔質構造の充填部材やシリカゲル、シリカエアロゲル等のほか、中空のセラミックビーズ、中空のガラスビーズ、中空の金属球を用いることができる。さらには、炭素、酸素、珪素等を含んだ有機珪素化合物や、高強度且つ高耐熱性のセラミック繊維のほか、低熱伝導率且つ低比熱の耐熱金属材料であるチタンやチタン合金、ＳＵＳ、低合金鋼、鋳鉄（ねずみ鋳鉄、球状黒鉛鋳鉄）等の粉末も同様に用いることができる。
  以上説明した実施形態から把握しう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の製造方法は、
  冠部と、前記冠部に設けられたスカート部と、を有する本体部をアルミニウム合金で形成する本体部形成工程と、
  前記アルミニウム合金よりも熱伝導率の低い材料である低熱伝導部形成材で形成された環状の低熱伝導部を前記冠部のうち内燃機関の燃焼室側に形成する工程であって、内燃機関のシリンダ内におけるピストンの移動方向の直交断面における前記環状の低熱伝導部の内周縁よりも内側に前記低熱伝導部形成材よりも熱伝導率の高い材料で形成された非低熱伝導部を有するように前記低熱伝導部を形成する低熱伝導部形成工程と、を有する。
  これにより、燃料噴射領域が冠部上で円環状となる内燃機関において、燃料噴射量域に対応した位置に低熱伝導部を設けることができる。 In addition, the shapes of the low thermal conductive material and the bonding material in Examples 1 to 4 are not limited to powder, but may be flakes or chips.
As the low thermal conductive material, a hollow porous ceramic bead, a hollow glass bead, and a hollow metal sphere can be used in addition to a filler having a fine porous structure mainly composed of silica, silica gel, silica airgel, and the like. Furthermore, in addition to organic silicon compounds containing carbon, oxygen, silicon, etc., high strength and high heat resistance ceramic fibers, low heat conductivity and low specific heat heat resistant metal materials such as titanium, titanium alloys, SUS, low alloys Powders of steel, cast iron (gray cast iron, spheroidal graphite cast iron) and the like can be used similarly.
The technical idea that can be grasped from the embodiment described above will be described below.
A method for manufacturing a piston of an internal combustion engine is as follows:
A body part forming step of forming a body part having a crown part and a skirt part provided in the crown part from an aluminum alloy;
A step of forming an annular low heat conduction part formed of a low heat conduction part forming material having a lower thermal conductivity than the aluminum alloy on the combustion chamber side of the internal combustion engine in the crown part, A non-low heat conduction part formed of a material having a higher thermal conductivity than the low heat conduction part forming material is provided inside the inner peripheral edge of the annular low heat conduction part in a cross section orthogonal to the moving direction of the piston in the cylinder. And a low thermal conduction part forming step for forming the low thermal conduction part.
Thereby, in the internal combustion engine in which the fuel injection region is annular on the crown, the low heat conduction portion can be provided at a position corresponding to the fuel injection amount region.
　より好ましい態様では、上記態様において、
  前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転するツールで押圧する押圧工程と、を有し、
  前記押圧工程は、前記ツールの回転中心が前記ピストンの移動方向の直交断面において、複数個存在するように行われる。
  これにより、ツールを小さくすることができるため、押圧工程におけるツールによる低熱伝導部形成材の押圧力を抑えることができる。そのため、ピストンの変形を抑制することができる。
  別の好ましい態様では、前記態様のいずれかにおいて、
  前記押圧工程は、前記ツールで前記低熱伝導部形成材を押圧する工程が複数回行われる。
  これにより、ツールにより低熱伝導部形成材に効率的に圧をかけることができ、低熱伝導部の密着性を向上させることができる。 In a more preferred embodiment, in the above embodiment,
The low thermal conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low thermal conduction portion forming material, and a tool for rotating the low thermal conduction portion forming material in the concave portion. A pressing step of pressing with,
The pressing step is performed such that a plurality of rotation centers of the tool exist in a cross section orthogonal to the moving direction of the piston.
Thereby, since a tool can be made small, the pressing force of the low heat conductive part formation material by the tool in a press process can be suppressed. Therefore, deformation of the piston can be suppressed.
In another preferred embodiment, in any of the above embodiments,
In the pressing step, the step of pressing the low heat conduction portion forming material with the tool is performed a plurality of times.
Thereby, a pressure can be efficiently applied to the low heat conduction part forming material with a tool, and the adhesiveness of the low heat conduction part can be improved.
　さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記押圧工程は、前記低熱伝導部形成材を押圧する工程が前記ツールを移動させながら行われる。
  これにより、低熱伝導部の形状に応じてツールを用意する必要がない。また連続した形状の低熱伝導部を形成することができる。
  さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転する環状のツールで押圧する押圧工程と、を有する。
  環状のツールを用いて押圧工程を行うことで、一度に環状の低熱伝導部を形成することができる。
  さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記非低熱伝導部は、前記本体部の前記アルミニウム合金である。
  これにより、低熱伝導部の内周側を本体部の素材であるアルミニウム合金以外を用いる必要がない。また、低熱伝導部の内周縁よりも内側に本体部の肉が存在するため、押圧工程において低熱伝導部の内側に混合粉末が逃げにくく、混合粉末に圧力をかけやすくなる。 In yet another preferred embodiment, in any of the above embodiments,
The pressing step is performed while the tool is moved in the step of pressing the low heat conduction portion forming material.
Thereby, it is not necessary to prepare a tool according to the shape of the low heat conduction part. Moreover, the continuous low heat conductive part can be formed.
In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low heat conduction portion forming material, and an annular shape rotating the low heat conduction portion forming material in the concave portion. Pressing with a tool.
By performing the pressing step using an annular tool, an annular low heat conduction portion can be formed at a time.
In yet another preferred embodiment, in any of the above embodiments,
The non-low heat conduction part is the aluminum alloy of the main body part.
Thereby, it is not necessary to use other than the aluminum alloy which is a raw material of a main-body part for the inner peripheral side of a low heat conductive part. Moreover, since the meat | flour of a main-body part exists inside the inner periphery of a low heat conductive part, mixed powder cannot escape easily inside a low heat conductive part in a press process, and it becomes easy to apply a pressure to mixed powder.
　さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた環状凹部に前記低熱伝導部形成材を充填する工程と、前記環状凹部内の前記低熱伝導部形成材を回転するツールで押圧する押圧工程と、を有し、
  前記環状凹部は、前記環状凹部の外周縁の外側全周が前記本体部の前記アルミニウム合金で包囲される。
  これにより、低熱伝導部の外周縁よりも外側に本体部の肉が存在するため、混合粉末押圧工程において低熱伝導部の外側に混合粉末が逃げにくく、混合粉末に圧力をかけやすくなる。
  さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部が外周側に露出するように前記低熱伝導部の外周縁よりも外側の前記本体部を切削除去する外周部除去工程を有する。
  これにより、燃料噴射領域が冠部の最外周側に存在するような内燃機関において、燃料噴射量域に対応した位置に低熱伝導部を設けることができる。 In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction part forming step includes a step of filling the annular recess provided on the combustion chamber side in the crown with the low heat conduction part forming material, and rotating the low heat conduction part forming material in the annular recess. Pressing with a tool, and
In the annular recess, the entire outer periphery of the outer peripheral edge of the annular recess is surrounded by the aluminum alloy of the main body.
Thereby, since the meat | flour of a main-body part exists outside the outer periphery of a low heat conductive part, mixed powder cannot escape easily to the outer side of a low heat conductive part in a mixed powder press process, and it becomes easy to apply a pressure to mixed powder.
In yet another preferred embodiment, in any of the above embodiments,
An outer peripheral portion removing step of cutting and removing the main body portion outside the outer peripheral edge of the low thermal conductive portion so that the low thermal conductive portion is exposed to the outer peripheral side;
As a result, in the internal combustion engine in which the fuel injection region exists on the outermost peripheral side of the crown portion, the low heat conduction portion can be provided at a position corresponding to the fuel injection amount region.
　さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成材は、前記アルミニウム合金よりも硬度の高い材料であって、
  前記低熱伝導部形成工程は、前記低熱伝導部がピストンの外周側に露出するように行われ、
  前記低熱伝導部の外周側にピストンリングが挿入されるリング溝を形成するリング溝形成工程を更に有する。
  これにより、リング溝の強度向上を図ることができる。
  さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側の最外周部に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転するツールで押圧する押圧工程と、を有し、
  前記押圧工程は、前記本体部の外周側を型で包囲した状態で行われる。
  これにより、低熱伝導部より外周側に冠部の肉が存在しない場合であっても、押圧工程時に型により低熱伝導部形成材の逃げを抑制することができる。 In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction part forming material is a material having a higher hardness than the aluminum alloy,
The low heat conduction part forming step is performed such that the low heat conduction part is exposed on the outer peripheral side of the piston,
It further has a ring groove forming step of forming a ring groove into which a piston ring is inserted on the outer peripheral side of the low heat conducting portion.
As a result, the strength of the ring groove can be improved.
In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction portion forming step includes a filling step of filling the concave portion provided in the outermost peripheral portion on the combustion chamber side of the crown portion with the low heat conduction portion forming material, and the low heat conduction portion forming material in the concave portion. Pressing with a rotating tool, and
The pressing step is performed in a state where the outer peripheral side of the main body is surrounded by a mold.
Thereby, even if it is a case where the thickness of a crown part does not exist in the outer peripheral side from a low heat conductive part, the escape of the low heat conductive part formation material can be suppressed by a type | mold at the time of a press process.
　さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成材は、粉体の混合材料である。
  これにより、冠部の凹部内で低熱伝導部形成材が均一に混ざり合った状態で押圧工程を行うことができ、低熱伝導部を均一な材質とすることができる。
  さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成工程は、前記低熱伝導部形成材である前記粉体の混合材料を加圧した圧粉体を形成する圧粉工程と、前記冠部のうち前記燃焼室側に設けられた凹部に前記圧粉体を配置する配置工程と、を有する。
  これにより、押圧工程において凹部から圧粉を逃げにくくすることができる。
  さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成工程は、前記圧粉工程後でかつ前記配置工程前に行われる加熱処理工程を更に更に有する。
  これにより、圧粉体を崩れにくくすることができ、押圧工程において圧粉体が逃げにくくすることができる。 In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction part forming material is a mixed powder material.
Thereby, a press process can be performed in the state with which the low heat conductive part formation material was mixed uniformly in the recessed part of a crown part, and a low heat conductive part can be made into a uniform material.
In yet another preferred embodiment, in any of the above embodiments,
The low thermal conduction portion forming step is provided on the combustion chamber side of the crown portion, and a compacting step of forming a green compact by pressing the mixed material of the powder that is the low thermal conduction portion forming material. An arrangement step of arranging the green compact in the recess.
Thereby, it is possible to make it difficult for the powder to escape from the recess in the pressing step.
In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction part forming step further includes a heat treatment step performed after the compacting step and before the arranging step.
Thereby, the green compact can be made difficult to collapse, and the green compact can be made difficult to escape in the pressing step.
　さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転する複数のツールで同時に押圧する押圧工程と、を有する。
  これにより、混押圧工程において凹部同士の間のピストンの肉が逃げにくく、ツールにより低熱伝導部形成材に圧をかけやすくすることができる。
  さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転するツールで押圧する押圧工程と、を有し、
  前記押圧工程は、前記本体部の外周側を型で包囲した状態で行われる。
  これにより、押圧工程においてピストンの変形を抑制することができる。 In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side of the crown portion with the low heat conduction portion forming material, and a plurality of rotating the low heat conduction portion forming material in the concave portion. Pressing with the tool at the same time.
Thereby, in the mixed pressing step, the meat of the piston between the recesses is difficult to escape, and it is possible to easily apply pressure to the low heat conduction portion forming material with the tool.
In yet another preferred embodiment, in any of the above embodiments,
The low thermal conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low thermal conduction portion forming material, and a tool for rotating the low thermal conduction portion forming material in the concave portion. A pressing step of pressing with,
The pressing step is performed in a state where the outer peripheral side of the main body is surrounded by a mold.
Thereby, a deformation | transformation of a piston can be suppressed in a press process.
　また他の観点から、ピストンは、
  内燃機関のピストンであって、アルミニウム合金で形成され、冠部と、前記冠部に設けられたスカート部と、を有する本体部と、
  前記冠部の内燃機関の燃焼室側に設けられ前記アルミニウム合金よりも熱伝導率の低い材料である低熱伝導部形成材で形成された環状の低熱伝導部と、
  前記環状の低熱伝導部の内周縁よりも内側に設けられ、前記低熱伝導部形成材よりも熱伝導率の高い材料で形成された非低熱伝導部と、を有する。
  これにより、燃料噴射領域が冠部上で円環状となる内燃機関において、燃料噴射量域に対応した位置に低熱伝導部を設けることができる。
  より好ましい態様では、上記態様において、
  前記低熱伝導部は、前記ピストンの移動方向の直交断面において、撹拌中心周りに前記低熱伝導形成部材が撹拌された撹拌軌跡を有する被撹拌部を複数有する。
  これにより、低熱伝導部を複数形成することができ、燃料噴射領域に応じて適切な位置に適切な形状の低熱伝導部を形成することができる。 From another point of view, the piston
A piston of an internal combustion engine, formed of an aluminum alloy, and having a crown portion, and a skirt portion provided on the crown portion, a main body portion,
An annular low heat conduction part formed of a low heat conduction part forming material which is provided on the combustion chamber side of the internal combustion engine of the crown part and has a lower thermal conductivity than the aluminum alloy;
A non-low heat conduction portion that is provided on the inner side of the inner peripheral edge of the annular low heat conduction portion and is formed of a material having a higher thermal conductivity than the low heat conduction portion forming material.
Thereby, in the internal combustion engine in which the fuel injection region is annular on the crown, the low heat conduction portion can be provided at a position corresponding to the fuel injection amount region.
In a more preferred embodiment, in the above embodiment,
The low heat conduction part has a plurality of parts to be stirred having a stirring locus in which the low heat conduction forming member is stirred around a stirring center in a cross section orthogonal to the moving direction of the piston.
Thereby, a plurality of low heat conduction parts can be formed, and a low heat conduction part having an appropriate shape can be formed at an appropriate position according to the fuel injection region.
　さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成材は、前記アルミニウム合金よりも硬度の高い材料であって、
  前記冠部は、前記冠部の外周側に設けられピストンリングが挿入されるリング溝を有し、前記低熱伝導部は、前記リング溝を含む範囲に設けられる。
  これにより、リング溝の強度向上を図ることができる。
  さらに別の好ましい態様では、前記態様のいずれかにおいて、
  前記低熱伝導部形成材は、粉体の混合材料である。
  これにより、冠部の凹部内で低熱伝導部形成材が均一に混ざり合った状態で押圧工程を行うことができ、低熱伝導部を均一な材質とすることができる。 In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction part forming material is a material having a higher hardness than the aluminum alloy,
The crown portion has a ring groove provided on an outer peripheral side of the crown portion and into which a piston ring is inserted, and the low heat conduction portion is provided in a range including the ring groove.
As a result, the strength of the ring groove can be improved.
In yet another preferred embodiment, in any of the above embodiments,
The low heat conduction part forming material is a mixed powder material.
Thereby, a press process can be performed in the state with which the low heat conductive part formation material was mixed uniformly in the recessed part of a crown part, and a low heat conductive part can be made into a uniform material.
　以上、本発明の幾つかの実施形態のみを説明したが、本発明の新規の教示や利点から実質的に外れることなく例示の実施形態に、多様な変更または改良を加えることが可能であることが当業者には容易に理解できるであろう。従って、その様な変更または改良を加えた形態も本発明の技術的範囲に含むことを意図する。上記実施形態を任意に組み合わせても良い。 Although only a few embodiments of the present invention have been described above, various modifications or improvements can be made to the illustrated embodiments without substantially departing from the novel teachings and advantages of the present invention. Will be easily understood by those skilled in the art. Therefore, it is intended that the embodiment added with such changes or improvements is also included in the technical scope of the present invention. You may combine the said embodiment arbitrarily.
　本願は、２０１６年１月１３日付出願の日本国特許出願第２０１６－００４７３１号に基づく優先権を主張する。２０１６年１月１３日付出願の日本国特許出願第２０１６－００４７３１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. 2016-004731 filed on Jan. 13, 2016. The entire disclosure including the specification, claims, drawings, and abstract of Japanese Patent Application No. 2016-004731 filed on January 13, 2016 is incorporated herein by reference in its entirety.
1　　ピストン2　　冠部2a　　環状溝（凹部）2b　　非低熱伝導部3　　低熱伝導部3a　　混合粉末（低熱伝導部形成材）3b　　プリフォーム（低熱伝導部形成材）5　　スカート部7　　円筒ツール（ツール）9　　本体部 1 piston 2 crown 2a annular groove (recess) 2b non-low heat conduction part 3 low heat conduction part 3a mixed powder (low heat conduction part forming material) 3b preform (low heat conduction part forming material) 5 skirt part 7 cylindrical tool (tool) 9 Body part

Claims (19)

  1. 　内燃機関のピストンの製造方法であって、
    　冠部と、前記冠部に設けられたスカート部と、を有する本体部をアルミニウム合金で形成する本体部形成工程と、
    　前記アルミニウム合金よりも熱伝導率の低い材料である低熱伝導部形成材で形成された環状の低熱伝導部を前記冠部のうち内燃機関の燃焼室側に形成する工程であって、内燃機関のシリンダ内におけるピストンの移動方向の直交断面における前記環状の低熱伝導部の内周縁よりも内側に前記低熱伝導部形成材よりも熱伝導率の高い材料で形成された非低熱伝導部を有するように前記低熱伝導部を形成する低熱伝導部形成工程と、
    　を有することを特徴とするピストンの製造方法。     A method of manufacturing a piston for an internal combustion engine,
    A body part forming step of forming a body part having a crown part and a skirt part provided in the crown part from an aluminum alloy;
    A step of forming an annular low heat conduction part formed of a low heat conduction part forming material having a lower thermal conductivity than the aluminum alloy on the combustion chamber side of the internal combustion engine in the crown part, A non-low heat conduction part formed of a material having a higher thermal conductivity than the low heat conduction part forming material is provided inside the inner peripheral edge of the annular low heat conduction part in a cross section orthogonal to the moving direction of the piston in the cylinder. A low thermal conductive portion forming step for forming the low thermal conductive portion;
    The manufacturing method of the piston characterized by having.
  2. 　請求項１に記載のピストンの製造方法において、
    　前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転するツールで押圧する押圧工程と、を有し、
    　前記押圧工程は、前記ツールの回転中心が前記ピストンの移動方向の直交断面において、複数個存在するように行われることを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 1,
    The low thermal conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low thermal conduction portion forming material, and a tool for rotating the low thermal conduction portion forming material in the concave portion. A pressing step of pressing with,
    The method of manufacturing a piston, wherein the pressing step is performed such that a plurality of rotation centers of the tool exist in a cross section orthogonal to the moving direction of the piston.
  3. 　請求項２に記載のピストンの製造方法において、
    　前記押圧工程は、前記ツールで前記低熱伝導部形成材を押圧する工程が複数回行われることを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 2,
    In the pressing step, the step of pressing the low heat conduction portion forming material with the tool is performed a plurality of times.
  4. 　請求項２に記載のピストンの製造方法において、
    　前記押圧工程は、前記低熱伝導部形成材を押圧する工程が前記ツールを移動させながら行われることを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 2,
    The method of manufacturing a piston, wherein the pressing step is performed while the tool is moved while the step of pressing the low heat conduction portion forming material is performed.
  5. 　請求項１に記載のピストンの製造方法において、
    　前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転する環状のツールで押圧する押圧工程と、を有することを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 1,
    The low heat conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low heat conduction portion forming material, and an annular shape rotating the low heat conduction portion forming material in the concave portion. And a pressing step of pressing with the tool.
  6. 　請求項１に記載のピストンの製造方法において、
    　前記非低熱伝導部は、前記本体部の前記アルミニウム合金であることを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 1,
    The non-low heat conduction part is the aluminum alloy of the main body part.
  7. 　請求項６に記載のピストンの製造方法において、
    　前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた環状凹部に前記低熱伝導部形成材を充填する工程と、前記環状凹部内の前記低熱伝導部形成材を回転するツールで押圧する押圧工程と、を有し、
    　前記環状の凹部は、前記環状の凹部の外周縁の外側全周が前記本体部の前記アルミニウム合金で包囲されるように形成されることを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 6,
    The low heat conduction part forming step includes a step of filling the annular recess provided on the combustion chamber side in the crown with the low heat conduction part forming material, and rotating the low heat conduction part forming material in the annular recess. Pressing with a tool, and
    The annular recess is formed such that the entire outer periphery of the outer periphery of the annular recess is surrounded by the aluminum alloy of the main body.
  8. 　請求項６に記載のピストンの製造方法は、前記低熱伝導部が外周側に露出するように前記低熱伝導部の外周縁よりも外側の前記本体部を切削除去する外周部除去工程を有することを特徴とするピストンの製造方法。 The method for manufacturing a piston according to claim 6 includes a peripheral portion removing step of cutting and removing the main body portion outside the outer peripheral edge of the low heat conductive portion so that the low heat conductive portion is exposed to the outer peripheral side. A method for manufacturing a piston.
  9. 　請求項１に記載のピストンの製造方法において、前記低熱伝導部形成材は、前記アルミニウム合金よりも硬度の高い材料であって、
    　前記低熱伝導部形成工程は、前記低熱伝導部がピストンの外周側に露出するように行われ、
    　前記低熱伝導部の外周側にピストンリングが挿入されるリング溝を形成するリング溝形成工程を更に有することを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 1, the low heat conduction part formation material is material higher in hardness than the aluminum alloy,
    The low heat conduction part forming step is performed such that the low heat conduction part is exposed on the outer peripheral side of the piston,
    A method for manufacturing a piston, further comprising a ring groove forming step of forming a ring groove into which a piston ring is inserted on an outer peripheral side of the low heat conducting portion.
  10. 　請求項１に記載のピストンの製造方法において、前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側の最外周部に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転するツールで押圧する押圧工程と、を有し、
    　前記押圧工程は、前記本体部の外周側を型で包囲した状態で行われることを特徴とするピストンの製造方法。     2. The method for manufacturing a piston according to claim 1, wherein the low thermal conductive portion forming step is a filling step of filling the concave portion provided in the outermost peripheral portion on the combustion chamber side in the crown portion with the low thermal conductive portion forming material. And a pressing step of pressing the low heat conduction portion forming material in the recess with a rotating tool,
    The method of manufacturing a piston, wherein the pressing step is performed in a state where the outer peripheral side of the main body is surrounded by a mold.
  11. 　請求項１に記載のピストンの製造方法において、
    　前記低熱伝導部形成材は、粉体の混合材料であることを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 1,
    The method for manufacturing a piston, wherein the low heat conduction part forming material is a mixed powder material.
  12. 　請求項１１に記載のピストンの製造方法において、
    　前記低熱伝導部形成工程は、前記低熱伝導部形成材である前記粉体の混合材料を加圧した圧粉体を形成する圧粉工程と、前記冠部のうち前記燃焼室側に設けられた凹部に前記圧粉体を配置する配置工程と、を有することを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 11,
    The low thermal conduction portion forming step is provided on the combustion chamber side of the crown portion, and a compacting step of forming a green compact by pressing the mixed material of the powder that is the low thermal conduction portion forming material. And a disposing step of disposing the green compact in the recess.
  13. 　請求項１２に記載のピストンの製造方法において、
    　前記低熱伝導部形成工程は、前記圧粉工程後でかつ前記配置工程前に行われる加熱処理工程を更に更に有することを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 12,
    The low heat conduction part forming step further includes a heat treatment step performed after the compacting step and before the arranging step.
  14. 　請求項１に記載のピストンの製造方法において、
    　前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転する複数のツールで同時に押圧する押圧工程と、を有することを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 1,
    The low heat conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side of the crown portion with the low heat conduction portion forming material, and a plurality of rotating the low heat conduction portion forming material in the concave portion. And a pressing step of simultaneously pressing with the tool.
  15. 　請求項１に記載のピストンの製造方法において、
    　前記低熱伝導部形成工程は、前記冠部のうち前記燃焼室側に設けられた凹部に前記低熱伝導部形成材を充填する充填工程と、前記凹部内の前記低熱伝導部形成材を回転するツールで押圧する押圧工程と、を有し、
    　前記押圧工程は、前記本体部の外周側を型で包囲した状態で行われることを特徴とするピストンの製造方法。     In the manufacturing method of the piston according to claim 1,
    The low thermal conduction portion forming step includes a filling step of filling the concave portion provided on the combustion chamber side in the crown portion with the low thermal conduction portion forming material, and a tool for rotating the low thermal conduction portion forming material in the concave portion. A pressing step of pressing with,
    The method of manufacturing a piston, wherein the pressing step is performed in a state where the outer peripheral side of the main body is surrounded by a mold.
  16. 　内燃機関のピストンであって、アルミニウム合金で形成され、冠部と、前記冠部に設けられたスカート部と、を有する本体部と、
    　前記冠部の内燃機関の燃焼室側に設けられ前記アルミニウム合金よりも熱伝導率の低い材料である低熱伝導部形成材で形成された環状の低熱伝導部と、
    　前記環状の低熱伝導部の内周縁よりも内側に設けられ、前記低熱伝導部形成材よりも熱伝導率の高い材料で形成された非低熱伝導部と、
    　を有することを特徴とするピストン。     A piston of an internal combustion engine, formed of an aluminum alloy, and having a crown portion, and a skirt portion provided on the crown portion, a main body portion,
    An annular low heat conduction part formed of a low heat conduction part forming material which is provided on the combustion chamber side of the internal combustion engine of the crown part and has a lower thermal conductivity than the aluminum alloy;
    A non-low heat conduction part provided on the inner side of the inner periphery of the annular low heat conduction part, and formed of a material having a higher thermal conductivity than the low heat conduction part forming material;
    A piston characterized by comprising:
  17. 　請求項１６に記載のピストンにおいて、
    　前記低熱伝導部は、前記ピストンの移動方向の直交断面において、撹拌中心周りに前記低熱伝導形成部材が撹拌された撹拌軌跡を有する被撹拌部を複数有することを特徴とするピストン。     The piston according to claim 16,
    The low heat conduction part includes a plurality of parts to be stirred having a stirring locus in which the low heat conduction forming member is stirred around a stirring center in a cross section orthogonal to the moving direction of the piston.
  18. 　請求項１６に記載のピストンにおいて、
    　前記低熱伝導部形成材は、前記アルミニウム合金よりも硬度の高い材料であって、
    　前記冠部は、前記冠部の外周側に設けられピストンリングが挿入されるリング溝を有し、
    　前記低熱伝導部は、前記リング溝を含む範囲に設けられることを特徴とするピストンリング。     The piston according to claim 16,
    The low heat conduction part forming material is a material having a higher hardness than the aluminum alloy,
    The crown portion is provided on the outer peripheral side of the crown portion and has a ring groove into which a piston ring is inserted,
    The low-heat conducting portion is provided in a range including the ring groove.
  19. 請求項１６に記載のピストンにおいて、
    　前記低熱伝導部形成材は、粉体の混合材料であることを特徴とするピストン。     The piston according to claim 16,
    The low heat conduction part forming material is a powder mixed material.
PCT/JP2016/086692 2016-01-13 2016-12-09 Method for producing piston, and piston WO2017122474A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59111918U (en) * 1983-01-18 1984-07-28 トヨタ自動車株式会社 direct injection diesel engine
WO2015016122A1 (en) * 2013-08-01 2015-02-05 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 piston for internal combustion engine
JP2015094292A (en) * 2013-11-12 2015-05-18 トヨタ自動車株式会社 Internal combustion engine
JP2015169193A (en) * 2014-03-11 2015-09-28 日産自動車株式会社 Piston for internal combustion engine

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59111918U (en) * 1983-01-18 1984-07-28 トヨタ自動車株式会社 direct injection diesel engine
WO2015016122A1 (en) * 2013-08-01 2015-02-05 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 piston for internal combustion engine
JP2015094292A (en) * 2013-11-12 2015-05-18 トヨタ自動車株式会社 Internal combustion engine
JP2015169193A (en) * 2014-03-11 2015-09-28 日産自動車株式会社 Piston for internal combustion engine

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