US20110120409A1 - Four-stroke internal combustion engine lubrication device - Google Patents

Four-stroke internal combustion engine lubrication device Download PDF

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Publication number
US20110120409A1
US20110120409A1 US12/949,120 US94912010A US2011120409A1 US 20110120409 A1 US20110120409 A1 US 20110120409A1 US 94912010 A US94912010 A US 94912010A US 2011120409 A1 US2011120409 A1 US 2011120409A1
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US
United States
Prior art keywords
oil
crankcase
chamber
valve
oil chamber
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.)
Abandoned
Application number
US12/949,120
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English (en)
Inventor
Shinichi Saitou
Tomohiro OHTSUBO
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.)
Yamabiko Corp
Original Assignee
Yamabiko 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 Yamabiko Corp filed Critical Yamabiko Corp
Assigned to YAMABIKO CORPORATION reassignment YAMABIKO CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: OHTSUBO, TOMOHIRO, SAITOU, SHINICHI
Publication of US20110120409A1 publication Critical patent/US20110120409A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/04—Pressure lubrication using pressure in working cylinder or crankcase to operate lubricant feeding devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/06—Lubricating systems characterised by the provision therein of crankshafts or connecting rods with lubricant passageways, e.g. bores
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
    • F01M11/0004—Oilsumps

Definitions

  • the present invention relates to a lubrication device for a four-stroke internal combustion engine that is suitable for use as a power source of a portable work machine such as a brush cutter, a chain saw, etc., and more specifically to a four-stroke internal combustion engine lubrication device that is so arranged as to be capable of appropriately lubricating various parts regardless of the orientation of the work machine (engine), of improving the capability for collecting excess oil within a valve chamber, etc., and the capability for supplying oil to the various parts, and of reliably preventing oil leakage from a breather port (blow-by gas discharge port) provided in the valve chamber.
  • a breather port blow-by gas discharge port
  • Patent Document 1 JP Patent Publication (Kokai) No. 2002-188423 A (“Patent Document 1”), incorporated by reference herein, discusses four-stroke internal combustion engines that are suitable for use as power sources of portable work machines such as brush cutters, chain saws, etc., of the overhead cam type comprising: a cylinder portion into which a piston is inserted; a valve chamber formed above the cylinder portion; a crankcase formed below the cylinder portion; and an oil chamber (oil reservoir) formed at the outer circumference of the crankcase.
  • the oil within the oil chamber is caused to flow into the crankcase in mist form.
  • the oil mist within the crankcase is supplied to the valve chamber via an L-shaped passage portion formed within a crankshaft, a gas-liquid separation chamber provided at the outer circumference thereof, and an oil supply passage formed in the cylinder portion.
  • Patent Document 2 JP Patent Publication (Kokai) No. 11-36839 A (1999) (“Patent Document 2”), incorporated by reference herein, discusses those in which a one-way valve is provided between a crankcase and an oil chamber, the positive pressure of the crankcase is utilized to supply oil to various parts, and an oil circulation path in a given direction from the crankcase to the oil chamber via a valve chamber is formed.
  • An aspect of the present invention includes a four-stroke internal combustion engine lubrication device that is capable of appropriately lubricating various parts regardless of the orientation of the engine, of improving the capability for collecting excess oil within a valve chamber, etc., and the capability for supplying oil to the various parts, and of reliably preventing oil leakage from a breather port (blow-by gas discharge port) provided in the valve chamber.
  • a four-stroke internal combustion engine lubrication device basically comprises: a cylinder portion into which a piston is inserted; a valve chamber formed above the cylinder portion; a crankcase formed below the cylinder portion; and an oil chamber formed at the outer circumference of the crankcase, wherein, utilizing the up/down motion of the piston, oil within the oil chamber is caused to flow into the crankcase in mist form.
  • the four-stroke internal combustion engine lubrication device further comprises: a one-way valve configured to allow oil flow from the oil chamber into the crankcase, while preventing oil flow from the crankcase into the oil chamber; an oil supply passage for supplying oil to the valve chamber from the crankcase; and a plurality of independent oil collection passages with differing inlet/outlet positions and for collecting in the oil chamber the excess oil in the valve chamber, wherein the dimensions of each part are so designed as to constantly maintain the oil chamber under negative pressure during operation, and the excess oil within the crankcase is returned to the oil chamber utilizing the negative pressure of the oil chamber.
  • a reed valve is used for the one-way valve.
  • the oil chamber is disposed adjacent to the crankcase in such a manner as to surround the crankcase with a baffle in-between, and a predetermined number of fine holes are formed in the baffle in order to return the excess oil within the crankcase to the oil chamber utilizing the negative pressure of the oil chamber.
  • the effective passage sectional area of the narrowest portion of each of the oil collection passages is set to or below a predetermined value.
  • the oil mist within the crankcase is supplied to the valve chamber via an L-shaped passage portion formed within the crankshaft, a gas-liquid separation chamber provided at the outer circumference thereof, and the oil supply passages.
  • the shape of the oil chamber that surrounds the crankcase is such that there is provided an expansive bulging portion that protrudes further outward, as compared to the other sides, on a side below the crankshaft and where the valve opening in the reed valve is located relative to the engine centerline.
  • a one-way valve such as a reed valve, etc.
  • a one-way valve such as a reed valve, etc.
  • the reed valve opens as the piston rises and the crankcase becomes negatively pressured (i.e., lower in pressure than the oil chamber).
  • the crankcase becomes negatively pressured (i.e., lower in pressure than the oil chamber).
  • air and oil end up rapidly passing through a small gap (ordinarily of approximately 1 mm) that is formed between the valve member and valve seat of the reed valve. Consequently, the turning of oil into mist is further facilitated, and oil flows into the crankcase (i.e., the reed valve functions as a means for facilitating oil mist generation).
  • the reed valve closes as the piston descends and the crankcase becomes positively pressured (i.e., higher in pressure than the oil chamber), and the oil mist within the crankcase is thus supplied to various parts.
  • some of the oil mist within the crankcase is supplied to the valve chamber via the L-shaped passage portion formed within the crankshaft, the gas-liquid separation chamber provided at the outer circumference thereof, and the oil supply passages.
  • the oil chamber is maintained under negative pressure, the excess oil within the valve chamber is sucked into and collected in the negatively pressured oil chamber via the plurality of independent oil collection passages with differing inlet/outlet positions. Further, the excess oil within the crankcase is also returned to the oil chamber via, for example, fine holes formed in the baffle.
  • various parts can be appropriately lubricated regardless of engine orientation, the capability for collecting the excess oil within the valve chamber and the capability for supplying oil to the various parts can be improved, and oil leakage from the breather port (blow-by gas discharge port) provided in the valve chamber can be prevented reliably.
  • oil can be fed to the various parts in sufficiently large amounts (i.e., oil circulation flow rate is increased). Consequently, lubrication is improved, and, at the same time, cooling of the various engine parts is improved.
  • the oil chamber that surrounds the crankcase is so shaped as to comprise an expansive bulging portion in the direction in which the one-way valve is provided so that the one-way valve would always be maintained at a position above oil level regardless of engine orientation, oil is prevented from flowing into the crankcase while still in liquid form, and it is possible to reliably supply to the crankcase oil that has been turned into mist.
  • FIG. 1 is a partially cutaway front view of an overhead cam type four-stroke internal combustion engine to which an embodiment of a lubrication device according to an aspect of the present invention is applied.
  • FIG. 3 is a schematic view corresponding to FIG. 1 and for illustrating an oil supply path and an oil collection path.
  • FIG. 4 is a schematic view corresponding to FIG. 2 and for illustrating an oil supply path and an oil collection path.
  • FIG. 1 is a partially cutaway front view of an overhead cam type four-stroke internal combustion engine to which an embodiment of a lubrication device according to the present invention is applied.
  • FIG. 2 is a partially cutaway side view as viewed in the direction of arrow X in FIG. 1 .
  • FIGS. 3 and 4 which are schematic views of FIGS. 1 and 2 , respectively, the outlined white arrows indicate the oil supply path, whereas the arrows with hatching indicate the oil collection path.
  • the engine 10 in FIG. 1 is an overhead earn type four-stroke internal combustion engine with a displacement of approximately 30 cc that is suitable for use as a power source for a portable work machine such as a brush cutter, a chain saw, etc.
  • the engine 10 comprises: a cylinder portion 12 into which a piston 11 is inserted; an upper chamber defining portion 13 provided above the cylinder portion 12 ; and a lower chamber defining portion 14 of a two-part structure provided below the cylinder portion 12 .
  • a valve chamber 18 in which a camshaft 25 for driving an intake/exhaust valve to open/close is disposed is formed in the upper chamber defining portion 13 .
  • a crankcase 15 in which a crankshaft 20 that is linked to the piston 11 via a con rod 22 is disposed, and an oil chamber 17 (a reservoir for oil 5 ), which is disposed adjacent to the crankcase 15 in such a manner as to surround the crankcase 15 with a baffle 16 in-between, are formed in the lower chamber defining portion 14 .
  • the lower-left portion, as viewed from the front, of the baffle 16 that separates the crankcase 15 and the oil chamber 17 is open, and a reed valve 40 is attached in such a manner as to block this opening.
  • the oil chamber is so arranged as to be greater in volume at the position in the same direction as compared to other directions. This is to maintain the reed valve 40 above oil level regardless of orientation and state, and to prevent oil from flowing into the crankcase in a liquid state. In this respect, so long as the relative positions of expanded portion of the oil chamber and the reed valve are maintained, the expanded portion and the reed valve may be provided in any given direction.
  • dead-space can be used effectively, and the volume of the oil chamber can be secured without increasing the longitudinal direction of the engine. Further, only oil that has been turned into mist would flow into the crankcase regardless of orientation, which is desirable.
  • the reed valve 40 comprises: a valve seat 41 comprising a metal plate member in which a valve opening 42 of a predetermined diameter is formed; and an elastically flexible tongue-shaped valve member 43 of which one end is fixed to the surface of this valve seat 41 on the side of the crankcase 15 , and of which the other end covers and blocks the valve opening 42 .
  • this reed valve 40 so functions as to allow oil flow from the oil chamber 17 into the crankcase 15 , while preventing oil flow from the crankcase 15 into the oil chamber 17 .
  • a breather port (blow-by gas discharge port) 19 is provided in the center portion of the valve chamber 18 .
  • An oil supply passage 35 for supplying oil from the crankcase 15 to the valve chamber 18 , and two independent oil collection passages 51 and 52 for collecting in the oil chamber 17 the excess oil within the valve chamber 18 are formed in the wall portions of the cylinder portion 12 , the lower chamber defining portion 14 and the upper chamber defining portion 13 .
  • the positive pressure of the crankcase 15 is used for supplying oil to the valve chamber 18 , and the oil mist within the crankcase 15 is supplied to the valve chamber 18 via an L-shaped passage portion 31 formed in the crankshaft 20 , a gas-liquid separation chamber 32 provided at the outer circumference thereof, and the oil-supply passage 35 (see also Patent Document 1 mentioned above for additional details).
  • the passage diameter (sectional diameter) of the passage 35 is set to approximately 3 mm or above in order to increase supply amount (circulation amount).
  • the first oil collection passage 51 has its inlet (upper end portion) 51 a open into an excess oil reservoir 18 a (mainly for when the engine is upright) provided on the left side of the floor portion side of the valve chamber 18 as viewed from the side
  • the other (the second oil collection passage 52 ) has its inlet (upper end portion) 52 a open into an excess oil reservoir 18 b (mainly for when the engine is inverted) provided on the right side of the ceiling portion side of the valve chamber 18 as viewed from the side.
  • outlets (lower end portions) 51 b and 52 b of the first and second oil collection passages 51 and 52 respectively, open into the upper portion of the oil chamber 17 .
  • portions of the oil collection passages 51 and 52 on the side of the outlets 51 b and 52 b are made narrower than the upstream portions.
  • the passage diameter (sectional diameter) of the respective upstream portions of the oil collection passages 51 and 52 are set to approximately 2.5 mm, with which adequate suction capability can be attained, and the respective portions thereof on the side of the outlets 51 b and 52 b (the downstream portions) have their passage diameter set to approximately 1 mm in order to prevent backflow (from the oil chamber 17 to the valve chamber 18 ).
  • an orifice may be provided in the middle of each passage.
  • the sectional shapes of the passages 35 , 51 and 52 have been defined as being circular in the present case, generally similar working effects may be attained with other shapes, too, so long as the effective passage sectional areas are the same.
  • the reed valve 40 opens as the piston 11 rises and the crankcase 15 becomes negatively pressured (i.e., lower in pressure than the oil chamber).
  • oil consequently flows into the crankcase 15 from the oil chamber 17 , air and oil end up rapidly passing through a small gap (ordinarily of approximately 1 mm) that is formed between the valve member 43 and valve seat 41 of the reed valve 40 . Consequently, the oil becomes mist-like and flows into the crankcase (i.e., the reed valve 40 functions as an oil mist generation means).
  • a vibrating body may be provided in the oil chamber as the oil mist generation means that causes the oil within the oil chamber to flow into the crankcase in mist form.
  • the reed valve 40 closes and the oil mist within the crankcase 15 is supplied to various parts.
  • some of the oil mist within the crankcase 15 is supplied to the valve chamber 18 via the L-shaped passage portion 31 formed within the crankshaft 20 , the gas-liquid separation chamber 32 provided at the outer circumference thereof, and the oil supply passage 35 .
  • the oil chamber 17 be negatively pressured, it is possible to confer flow directionality to each of the oil passages, and oil collection becomes possible regardless of the orientation of the engine 10 (e.g., upright, inclined, inverted, etc.). It is noted that since both the gas and liquid portions within the oil chamber 17 are negatively pressured, the positional freedom of the respective outlets (downstream end portions) 51 b and 52 b of the oil collection passages 51 and 52 (i.e., the freedom of passage layout) is extremely high, thereby enabling omnidirectional operation.
  • various parts can be appropriately lubricated regardless of engine orientation, the capability for collecting the excess oil within the valve chamber 18 and the capability for supplying oil to the various parts can be improved, and oil leakage from the breather port (blow-by gas discharge port) 19 provided in the valve chamber 18 can be prevented reliability.
  • oil can be adequately fed to the various parts (i.e., oil circulation flow rate is increased), as a result of which it is possible to improve lubrication, while at the same time improving cooling for the various parts of the engine.
  • the baffle 16 which separates the oil chamber 17 and the crankcase 15 , as oil returning means for returning the excess oil within the crankcase 15 to the oil chamber 17 utilizing the negative pressure of the oil chamber 17 , it is possible to achieve overall simplification, cost reduction, etc., as compared to cases in which other oil returning means, such as valve devices, etc., are employed.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Lubrication Details And Ventilation Of Internal Combustion Engines (AREA)
  • Lubrication Of Internal Combustion Engines (AREA)
US12/949,120 2009-11-26 2010-11-18 Four-stroke internal combustion engine lubrication device Abandoned US20110120409A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2009268516A JP5414477B2 (ja) 2009-11-26 2009-11-26 ４サイクルエンジンの潤滑装置
JP2009-268516 2009-11-26

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US (1) US20110120409A1 (ja)
EP (1) EP2333258A1 (ja)
JP (1) JP5414477B2 (ja)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130104839A1 (en) * 2011-10-31 2013-05-02 Suzuki Motor Corporation Engine provided with lubricating structure
US20140096738A1 (en) * 2011-09-22 2014-04-10 Etg Limited Engine Lubrication Method
US20150233246A1 (en) * 2012-09-21 2015-08-20 Exoes Steam engine electricity production assembly

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101317201B1 (ko) * 2013-03-29 2013-10-15 (주)테너지 예초기용 엔진의 윤활구조
JP6357119B2 (ja) * 2015-02-05 2018-07-11 株式会社マキタ エンジンの潤滑装置
GB2550113B (en) * 2016-05-03 2019-07-24 Ford Global Tech Llc Crankcase oil catcher with an aperture and seal.

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US6508224B2 (en) * 2000-03-14 2003-01-21 Honda Giken Kogyo Kabushiki Kaisha Handheld type four-cycle engine
US6546907B2 (en) * 2000-12-18 2003-04-15 Kioritz Corporation Four-stroke cycle internal combustion engine
US6786187B2 (en) * 2000-05-29 2004-09-07 Kioritz Corporation Internal combustion engine
US6935297B2 (en) * 2002-07-24 2005-08-30 Honda Giken Kogyo Kabushiki Kaisha Lubricating system for 4-cycle engine

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US6508224B2 (en) * 2000-03-14 2003-01-21 Honda Giken Kogyo Kabushiki Kaisha Handheld type four-cycle engine
US6786187B2 (en) * 2000-05-29 2004-09-07 Kioritz Corporation Internal combustion engine
US6546907B2 (en) * 2000-12-18 2003-04-15 Kioritz Corporation Four-stroke cycle internal combustion engine
US6935297B2 (en) * 2002-07-24 2005-08-30 Honda Giken Kogyo Kabushiki Kaisha Lubricating system for 4-cycle engine

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140096738A1 (en) * 2011-09-22 2014-04-10 Etg Limited Engine Lubrication Method
US20130104839A1 (en) * 2011-10-31 2013-05-02 Suzuki Motor Corporation Engine provided with lubricating structure
US9057294B2 (en) * 2011-10-31 2015-06-16 Suzuki Motor Corporation Engine provided with lubricating structure
US20150233246A1 (en) * 2012-09-21 2015-08-20 Exoes Steam engine electricity production assembly

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Publication number Publication date
JP2011111960A (ja) 2011-06-09
EP2333258A1 (en) 2011-06-15
JP5414477B2 (ja) 2014-02-12

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AS Assignment

Owner name: YAMABIKO CORPORATION, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SAITOU, SHINICHI;OHTSUBO, TOMOHIRO;REEL/FRAME:025374/0112

Effective date: 20100922

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION