WO2025115386A1 - ピストン - Google Patents

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Publication number
WO2025115386A1
WO2025115386A1 PCT/JP2024/035110 JP2024035110W WO2025115386A1 WO 2025115386 A1 WO2025115386 A1 WO 2025115386A1 JP 2024035110 W JP2024035110 W JP 2024035110W WO 2025115386 A1 WO2025115386 A1 WO 2025115386A1
Authority
WO
WIPO (PCT)
Prior art keywords
land
piston
dead center
ring
skirt
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2024/035110
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
英幸 安田
信之 小松
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Motors Corp
Original Assignee
Mitsubishi Motors Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Motors Corp filed Critical Mitsubishi Motors Corp
Priority to JP2025560861A priority Critical patent/JPWO2025115386A1/ja
Publication of WO2025115386A1 publication Critical patent/WO2025115386A1/ja
Anticipated expiration legal-status Critical
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 

Definitions

  • This disclosure relates to a piston.
  • the piston is provided with a top land, a second land, a third land, and a skirt in that order from the top dead center side in the piston sliding direction.
  • a top ring is provided in the groove between the top land and the second land.
  • a second ring is provided in the groove between the second land and the third land.
  • An oil ring is provided in the groove between the third land and the skirt.
  • the side of the third land, the side of the top land, and the side of the second land are located in the order of furthest from the liner (cylinder liner) that houses the piston (see, for example, Patent Document 1).
  • piston scuffing hereinafter referred to simply as scuffing in the specification
  • the objective of this disclosure is to provide a piston that can reduce the amount of blow-by gas.
  • the piston according to the present disclosure is a piston that slides inside a cylinder liner and includes, in order from the top dead center side in the sliding direction, a top land, a top ring, a second land, a second ring, and a third land, with the side of the third land positioned radially outward of the piston than the side of the top land, and the side of the third land positioned radially inward of the piston than the side of the second land.
  • the direction in which the piston 1 slides will be referred to as the sliding direction
  • the side on which the top dead center of the piston 1 is located will be referred to as the top dead center side
  • the side on which the bottom dead center of the piston 1 is located will be referred to as the bottom dead center side.
  • a piston 1 is rotatably supported on a crankshaft 4 via a connecting rod 2.
  • the piston 1 is housed in a liner (cylinder liner) 6 fixed to a cylinder of an engine 3, and rotates the crankshaft 4 by reciprocating along the liner 6 between top dead center and bottom dead center.
  • Oil is stored in a crankcase 8 that houses the crankshaft 4.
  • the engine 3 in this embodiment is a diesel engine.
  • the top land 11 is the part of the piston 1 that is located closest to the top dead center and faces the combustion chamber 10.
  • the side surface 11a of the top land 11 widens radially outward toward the bottom dead center side in the sliding direction. In other words, the side surface 11a of the top land 11 is wider radially outward at the bottom dead center end than at the top dead center end.
  • a top ring groove 11b is provided between the top land 11 and the second land 13.
  • the top ring groove 11b accommodates an annular top ring 12.
  • the top ring 12 contacts the liner 6 and seals between the combustion chamber 10 and the crankcase 8.
  • the top ring 12 also maintains the oil film formed between the liner 6 and the top ring 12, and inhibits oil from entering the combustion chamber 10.
  • the second land 13 is a portion of the piston 1 adjacent to the top land 11 on the bottom dead center side, sandwiching the top ring groove 11b.
  • the side surface 13a of the second land 13 is wider toward the radial outside of the piston 1 at the bottom dead center end than at the top dead center end.
  • a second ring groove 13b is provided between the second land 13 and the third land 15.
  • the annular second ring 14 is housed in the second ring groove 13b.
  • the second ring 14 contacts the liner 6 in the same way as the top ring 12, and seals the gap between the combustion chamber 10 and the crankcase 8.
  • the second ring 14 maintains the oil film formed between the liner 6 and the top ring 12 in the same way as the top ring 12, and inhibits oil from entering the combustion chamber 10.
  • the third land 15 is a part of the piston 1 adjacent to the bottom dead center side of the second land 13 across the second ring groove 13b.
  • the side surface 15a of the third land 15 is formed straight along the sliding direction of the piston 1 at the top dead center side end and the bottom dead center side end.
  • An oil ring groove 15b is provided between the third land 15 and the skirt 17.
  • An annular oil ring 16 is accommodated in the oil ring groove 15b. The oil ring 16 contacts the liner 6 in the same way as the top ring 12 and the second ring 14, and seals between the combustion chamber 10 and the crankcase 8.
  • the oil ring 16 maintains the oil film formed between the liner 6 and the top ring 12 in the same way as the top ring 12 and the second ring 14, and suppresses the intrusion of oil into the combustion chamber 10. Furthermore, the oil ring 16 collects excess oil adhering to the liner 6 and returns the oil to the crankcase 8 via an oil passage (not shown) in the piston 1.
  • the skirt 17 is a part of the piston 1 adjacent to the bottom dead center side of the third land 15 across the oil ring groove 15b.
  • the side surface 17a of the skirt 17 is longer in the sliding direction than the top land 11, second land 13, and third land 15.
  • FIG. 2 is a graph showing simulated profiles of the side 11a of the top land 11 (see FIG. 1), the side 13a of the second land 13 (see FIG. 1), the side 15a of the third land 15 (see FIG. 1), and the side 17a of the skirt 17 (see FIG. 1). More specifically, FIG. 2 is a graph showing the distance from the liner 6 to the side 11a of the top land 11, the side 13a of the second land 13, the side 15a of the third land 15, and the side 17a of the skirt 17.
  • the graph shown by the solid line in FIG. 2 is the profile of the piston 1 of the present disclosure
  • the graph shown by the dashed line in FIG. 2 is the profile of a conventional piston disclosed as a comparative example.
  • Point A in Figure 2 indicates the position of the top dead center end of the side 11a of the top land 11.
  • Point B indicates the position of the bottom dead center end of the side 11a of the top land 11.
  • Point C indicates the position of the top dead center end of the side 13a of the second land 13.
  • Point D indicates the position of the bottom dead center end of the side 13a of the second land 13.
  • the solid line E indicates the position of the side 15a of the third land 15.
  • Point F indicates the position of the top dead center end of the side 17a of the skirt 17.
  • Point G indicates the position of the bottom dead center end of the side 17a of the skirt 17.
  • the side surface 15a of the third land 15 is positioned radially outboard of the piston 1 relative to the bottom dead center end of the side surface 11a of the top land 11.
  • the pressure on the bottom dead center side of the second ring 14 can be reduced and floating of the second ring 14 can be suppressed.
  • the second ring 14 floats toward the top dead center, a gap is generated between the second ring groove 13b and the second ring 14 through which blow-by gas can pass.
  • the piston 1 of the present disclosure suppresses the floating of the second ring 14, thereby suppressing the occurrence of this gap and realizing a reduction in the amount of blow-by gas.
  • the imaginary line X1 connecting points A and B in Figure 2 indicates the extension of the side 11a of the top land 11.
  • the side 15a of the third land 15 is located radially outward from the extension of the side 11a of the top land 11. This ensures that the side 15a of the third land 15 is always located radially outward from the bottom dead center end of the side 11a of the top land 11, even when the piston 1 rotates counterclockwise or clockwise and the position of the piston 1 is tilted relative to the sliding direction of the piston 1. As a result, floating of the second ring 14 can be more reliably suppressed.
  • the side surface 15a of the third land 15 is located radially inward of the piston 1 compared to the side surface 13a of the second land 13.
  • the imaginary line X2 in FIG. 2 indicates an extension plane obtained by extending the profile of the top dead center side of the side 17a of the skirt 17 toward the top dead center side.
  • the imaginary line X2 in FIG. 2 indicates an extension plane obtained by extending the profile of the top dead center side of the side 17a of the skirt 17 toward the top dead center side.
  • at least a portion of the side 13a of the second land 13 is located on an extension plane obtained by extending the profile of the top dead center side of the side 17a of the skirt 17 toward the top dead center side.
  • the side 13a of the second land 13 is formed so as to approximately coincide with the extension plane obtained by extending the profile of the side 17a of the skirt 17 toward the top dead center side.
  • the skirt 17 mainly functions to prevent the piston 1 from tilting.
  • the third land 15 is closer to the liner 6 than in conventional pistons.
  • the skirt 17 and second land 13 are used to stabilize the posture of the piston 1, which prevents scuffing caused by the third land 15.
  • the side surface 13a of the second land 13 is formed to coincide with the extension surface of the profile of the side surface 17a of the skirt 17 toward the top dead center side, thereby making the posture of the piston 1 more stable.
  • the shape of the side surface 17a of the skirt 17 is located radially inward of the piston 1 as it moves from the middle of the sliding direction of the piston 1 toward the top dead center side and the bottom dead center side.
  • the imaginary line X3 in FIG. 2 is a line extending from the position of point F toward the bottom dead center side in the sliding direction.
  • the shape of the side surface 17a of the skirt 17 is such that the end position on the bottom dead center side is located radially inward of the piston 1 compared to the end position on the top dead center side.
  • the end position on the bottom dead center side is located radially outward of the piston 1 compared to the end position on the top dead center side, suppressing the tilt of the piston posture.
  • the contact area between the skirt and the liner tends to be large, and the frictional resistance tends to be large.
  • the shape of the side surface 17a of the skirt 17 of the present disclosure is such that the end position on the bottom dead center side is located radially inward of the piston 1 compared to the end position on the top dead center side, thereby narrowing the lower end of the skirt 17 radially inward. This reduces the contact area between the liner 6 and the side surface 17a of the skirt 17, reducing frictional resistance.
  • the skirt 17 and the second land 13 are used to prevent the piston 1 from tilting, which makes the piston 1 more stable.
  • the piston 1 is also easier to prevent the second ring 14 from floating. As a result, this piston 1 can further reduce the amount of blow-by gas.
  • this disclosure provides a piston 1 that can reduce the amount of blow-by gas.
  • the engine 3 is described as a diesel engine, but the piston 1 may be a piston 1 used in a gasoline engine.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
PCT/JP2024/035110 2023-11-30 2024-10-01 ピストン Pending WO2025115386A1 (ja)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2025560861A JPWO2025115386A1 (https=) 2023-11-30 2024-10-01

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2023203291 2023-11-30
JP2023-203291 2023-11-30

Publications (1)

Publication Number Publication Date
WO2025115386A1 true WO2025115386A1 (ja) 2025-06-05

Family

ID=95897496

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2024/035110 Pending WO2025115386A1 (ja) 2023-11-30 2024-10-01 ピストン

Country Status (2)

Country Link
JP (1) JPWO2025115386A1 (https=)
WO (1) WO2025115386A1 (https=)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56159642U (https=) * 1980-04-28 1981-11-28
JPS613947U (ja) * 1984-06-13 1986-01-11 イズミ工業株式会社 内燃機関用ピストン
US20100108015A1 (en) * 2008-11-05 2010-05-06 Rainer Scharp Multi-part piston for an internal combustion engine
JP2020045795A (ja) * 2018-09-18 2020-03-26 スズキ株式会社 内燃機関のピストン

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56159642U (https=) * 1980-04-28 1981-11-28
JPS613947U (ja) * 1984-06-13 1986-01-11 イズミ工業株式会社 内燃機関用ピストン
US20100108015A1 (en) * 2008-11-05 2010-05-06 Rainer Scharp Multi-part piston for an internal combustion engine
JP2020045795A (ja) * 2018-09-18 2020-03-26 スズキ株式会社 内燃機関のピストン

Also Published As

Publication number Publication date
JPWO2025115386A1 (https=) 2025-06-05

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