US3825238A - Overflow type carburettor - Google Patents

Overflow type carburettor Download PDF

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Publication number
US3825238A
US3825238A US00302378A US30237872A US3825238A US 3825238 A US3825238 A US 3825238A US 00302378 A US00302378 A US 00302378A US 30237872 A US30237872 A US 30237872A US 3825238 A US3825238 A US 3825238A
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US
United States
Prior art keywords
fuel
carburettor
set forth
chamber
valve
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.)
Expired - Lifetime
Application number
US00302378A
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English (en)
Inventor
Y Nishihara
I Ohashi
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Mikuni Corp
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Mikuni Corp
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Filing date
Publication date
Application filed by Mikuni Corp filed Critical Mikuni Corp
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Publication of US3825238A publication Critical patent/US3825238A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M17/00—Carburettors having pertinent characteristics not provided for in, or of interest apart from, the apparatus of preceding main groups F02M1/00 - F02M15/00
    • F02M17/02—Floatless carburettors
    • F02M17/06—Floatless carburettors having overflow chamber determining constant fuel level
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S261/00—Gas and liquid contact apparatus
    • Y10S261/50—Surge prevention in carburetors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S261/00—Gas and liquid contact apparatus
    • Y10S261/67—Carburetors with vented bowl

Definitions

  • the overflow type carburettor has long been known and has been mainly used for small size internal combustion engine vehicles such as scooters, motorcycles and small size agricultural all-purpose tractors. But the prior art carburettors of this type are unsatisfactory in the following points.
  • the fuel tank In the case of motor cycles, the fuel tank is usually positioned higher than the carburettor, and fuel is freely fed by gravity to the fuel chamber of the carburettor. Excess fuel overflows the partition and is returned to the fuel tank by means of a recirculating pump.
  • a stopcock is provided in the tubing connecting the fuel tank and the fuel chamber, and this clock must be closed when the engine is not-operated. If the cock is inadvertently left open when the engine is not operating, the fuel may fill the fuel chamber, flow out of the carburettor and/or penetrate into the engine cylinders, since the circulating pump is not operated then, either.
  • the overflow type carburettors of the prior art do not provide stabilized engine operation when the vehicle is extremely inclined. If a vehicle is inclined more than 30, the prior art overflow carburettor usually does not work well, because the fuel level in the fuel chamber of the carburettor falls and fuel is not fed to the engine smoothly.
  • an overflow carburettor has no float in the fuel chamber, and therefore, the fuel in the fuel chamber is shaken harder than a float carburettor and the shaken fuel spatters and often penetrates the air vent to clog It.
  • the object of this invention is to provide a novel overflow type carburettor which is free from the abovementioned defects and is more versatile thanthe overflow carburettor of the prior art and thus can be used for vehicles which are driven in an extremely inclined state such as snowmobile.
  • an overflow type carburettor provided with a fuel supply valve 'which' closes the fuel inlet of the fuel chamber (fuel well) of the carburettor when no fuel supply pressure 2 is applied is provided. With this, the fuel does not drain from the carburettor and the fuel chamber is never emptied even when the engine is not operated.
  • an overflow type carburettor in which a plurality of air vents are pro vided in the head space of the fuel chamber is provided.
  • No prior art overflow carburettor is provided with a plurality of air vents in the fuel chamber. Said air vents open in the head space of the fuel chamber at different positions. Thus, communication between the head space of the fuel chamber and the atmosphere is always maintained by some vent or vents which are exposed to the gaseous phase in whichever direction the carburettor is inclined.
  • an overflow type carburettor in which a fuel channel which communicates with the lower end of the fuel feed duct leading to the fuel spray nozzle and the bottom of the fuel well of the fuel chamber.
  • the fuel channel has two or more branches, the end of each of which forms an opening to the fuel well provided with a valve, which closes the opening when the fuel channel lies horizontal and closes the opening when the carburettor is inclined and the opening is raised high.
  • an overflow type carburettor provided with said'fuel channel which further has as the overflow partition, a cylindrical wall surrounding the fuel feed duct is provided.
  • the fuel well formed by thecylindrical wall is separated by a horizontal partition into an upper section and a lower section, and an annular hole surrounding the fuel feed duct is provided in the horizontal partition so that the upper section and the lower section communicate with each other.
  • the carburettor is practically operable in whichever direction the vehicle may be inclined.
  • an overflow type carburettor in which a baffleboard which extends under the opening of the air vents, is provided. This further contributes to stabilized engine operation.
  • FIG. 1 is a longitudinal elevational cross-sectional view of an embodiment of the carburettor of this invention.
  • FIG. 2 is a traverse elevational cross-sectional view of the carburettor of FIG. 1 along line A A in FIG. 1.
  • FIG. 3 is a plan view of the carburettor of FIG. 1, showing the connection with the engine.
  • FIG. 4 is a traverse elevational cross-sectional view of the fuel chamber of another embodiment of the carburettor of this invention.
  • FIG. 5 is a cross-sectional view of another example of the fuel supply valve used in the carburettor of this invention.
  • member 1 is a fuel-air mixing channel
  • 2 is a throttle valve for fuel-air mixture
  • 3 is a fuel nozzle
  • 4 is an air inlet
  • 5 is a fuel-air mixing chamber
  • 6 is a fuel chamber which is positioned on the underside of the fuel air mixing chamber.
  • the fuel chamber is separated by an overflow partition 7 into a well or pool for fuel 8 and an overflow drain section 9.
  • a fuel supply valve 10 at the bottom and a fuel feed duct 11 at the center.
  • the overflow drain section 9 are provided, a drain outlet 12 atthe bottom and a baffleboard 13 at the top.
  • the fuel supply valve 10 may be a ball valve for example.
  • the valve comprises a ball 16 which closes the opening of fuel supply tubing 14 by virtue of the resilient force of a spring 15 supported by a suitable supporter 17.
  • the valve closes the fuel inlet when no pumping force (fuel supply pressure) is applied to the fuel supplied.
  • the carburettor of this invention is used for an engine provided with a fuel supply pump.
  • the valve may be surrounded by a filter net or a flowregulating member made of a porous material 20.
  • FIG. 5 An alternative structure of the fuel supply valve is shown in FIG. 5. This is a diaphragm valve, and this is installed between the fuel chamber of the carburettor and the fuel supply pump.
  • member 51 is a valve body
  • 52 is a diaphragm
  • 53 is an atmospheric pressure chamber
  • 54 is a fuel chamber of the valve
  • 55 is a spring
  • 56 is a stopper attached to the diaphragm 52
  • 57 is a passage communicating with the fuel supply pump
  • 58 is a fuel feed duct communicating with the fuel chamber of the carburettor
  • 59 is a through hole.'This valve functions as follows.
  • the diaphragm 52 When the engine is not operating, that is, when the fuel supply pump is not working, the diaphragm 52 is pressed by the spring 55 and the stopper 56 closes the fuel passage. But when the engine is in operation, the pressure of the fuel opens the stopper and the fuel flows into the fuel chamber of the carburettor. It is advantageous that a through hole 59 in the atmospheric pressure chamber 53 is arranged so as to communicate with the engine manifold. By this the atmospheric chamber is maintained at sub-atmospheric pressure and this will make the diaphram more responsive.
  • the fuel feed duct 11 communicates with a spray nozzle 3 at the upper end thereof and it contains a jet orifice 18 therein.
  • the fuel feed duct 11 communicates with the fuel well 8 by a horizontal fuel channel 19 which runs beneath the bottom of the fuel well 11 and opens to the well at both ends 21 and 22 thereof as shown in FIG. 2.
  • valve chambers 23 and 24 At the openings 21 and 22 are provided valve chambers 23 and 24, in which a free ball valve 25 or 26 is placed respectively.
  • air vents 27 and 28 are provided. They penetrate through the wall of the fuel-air mixing chamber and open in the fuel-air mixing channel. In FIGS. 1 and 2, the two vents join together and open in the mixing channel by a common opening 29 on the center line of the mixing channel. But they may have independent openings.
  • FIG. 3 shows such an arrangement of the carburettor, a fuel tank and a fuel supply pump.
  • member 30 drawn in broken line is an engine manifold
  • 31 is a fuel tank and 32 is a fuel supply pump
  • 33 is a fuel supply pipe
  • 34 is a fuel recirculation duct.
  • fuel chamber 6, overflow partition 7, fuel supply valve 10, fuel feed duct 11, fuel channel 19, valve chambers 23 and 24, ball valves 25 and 26 are shown in broken lines, too.
  • a small size vehicle such as motorcycle is often titled or tipped extremely in the direction perpendicular to the direction of the motion of the vehicle. Especially in the case of a snowmobile, it is often driven tippped to the side almost in order to remove the snow piled thereon.
  • the carburettor of this invention can be used for such a vehicle that is driven in such an extremely inclined position.
  • the carburettor of this embodiment is installed in a vehicle in the above-explained fashion. If the vehicle is tipped to the right with respect to FIG. 2, the left side inlet 21 of the fuel channel 19 is raised high and is exposed to the gaseous phase or the head space in an extreme case. However, the inlet of the fuel channel is closed by the ball valve 25 by virture of gravity, and, therefore, neither excess fuel is supplied to the spray nozzle nor only air is fed to the nozzle, but fuel continues to be almost normally supplied through the right side inlet 22.
  • the overflow drain outlet 12 As the overflow drain outlet 12 is positioned on the axial line of inclination and air vents are provided on both sides of the axial line, the fuel level determined by the position of the drain outlet 12 is secured and the head space is maintained at the atmospheric pressure whether the vehicle is inclined to the right or to the left. That is, with this carburettor, the engine can be almost normally operated even when the vehicle is inclined or tipped, since fuel head is maintained at an operating level all the time, although it may be lower or higher than the normal level as determined when the engine is level. It will be noted that the fuel level is lowered as the vehicle is inclined to some extent, but the level is raised again as the inclination approaches 90 and at 90 the fuel level is a little higher than at the normal position.
  • a vehicle in which the carburettor of this invention is to be installed is a vehicle, which may be inclined not in a definite direction, such as an agricultural vehicle, and if the carburettor can be made on a little larger scale, it will be advantageous to construct the fuel chamber as shown in FIG. 4.
  • the overflow partition is not a straight wall as 7 in FIGS. 1 and 2 but is a cylindrical wall surrounding the fuel feed duct 11 as shown at 41 in FIG. 4.
  • the overflow drain section is provided outside of the cylindrical overflow partition as shown at 9 in FIG. 4.
  • a plurality of drain outlets 12 are provided in the overflow drain section 9 but they are not necessarily positioned on the longitudinal central line.
  • the fuel well 8 is separated into an upper section 8" and a lower section 8 by a horizontal partition 42 and an annular hole 43 is provided around the fuel feed duct 11.
  • Member 44 is a fuel supply duct communicating with the fuel tank, and there is a'small through-hole 45 open in the lower section 8' and there is another small through-hole 46 open in the upper section 8".
  • FIG. 4 a fuel supply valve such as shown in FIG. 1 or FIG. 4 is provided.
  • the fuel channel 19 has more than two branches.
  • the ball valve that is positioned at the highest level closes the corresponding branch of the fuel channel so as to prevent introduction of air into the fuel duct 11.
  • FIG. 1 and FIG. 2 Another aspect of this invention is the provision of a baffleboard under the air vents as shown in FIG. 1 and FIG. 2.
  • the baffleboard prevents penetration into the air vents of fuel spattered by agitation of fuel caused by vibration of the engine and jolting of the vehicle.
  • the arrangement of the carburettor and the fuel mixing chamber is not limited to that represented by FIGS. 1 through 3. It is of course possible to arrange so that the orientation of the fuel channel 19 and air vents is perpendicular to that of the longitudinal axis of the fuel-air mixing chamber.
  • An overflow carburettor comprising, a fuel chamber, an overflow drain section, an overflow partition separating said fuel chamber and said overflow drain section, an outlet return means for excess fuel to a fuel tank from said overflow section, an inlet means to the fuel chamber connectable to a fuel supply pump and entering the fuel chamber below the fuel level, a fuel supply valve at the fuel inlet of the fuel chamber and forming part of the carburettor structure, said valve being operable to close the fuel inlet when fuel supply which vents open in the head space of the fuel chamber at spaced different positions, whereby irrespective of the inclination of the carburettor at least one vent is free of fuel.
  • each valve is a ball valve.
  • the overflow partition comprises a cylindrical wall surrounding the central fuel feed duct, a horizontal partition separates the fuel chamber into an upper section and a lower section, said horizontal partition being provided with an annular hole surrounding the fuel duct, and a fuel supply duct extends from the fuel inlet to supply both the upper section and the lower section.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of The Air-Fuel Ratio Of Carburetors (AREA)
US00302378A 1971-11-10 1972-10-30 Overflow type carburettor Expired - Lifetime US3825238A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7190086A JPS5014689B2 (enrdf_load_stackoverflow) 1971-11-10 1971-11-10

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US3825238A true US3825238A (en) 1974-07-23

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Application Number Title Priority Date Filing Date
US00302378A Expired - Lifetime US3825238A (en) 1971-11-10 1972-10-30 Overflow type carburettor

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JP (1) JPS5014689B2 (enrdf_load_stackoverflow)
CA (1) CA964538A (enrdf_load_stackoverflow)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4168289A (en) * 1977-12-19 1979-09-18 Saunion Oscar P Floatless carburetor
US4254064A (en) * 1979-08-02 1981-03-03 Kohler Co. Carburetor starting mixture control
US4350124A (en) * 1979-09-29 1982-09-21 Yamaha Hatsudoki Kabushiki Kaisha Overflow device for vehicular carburetor
US4353847A (en) * 1980-12-26 1982-10-12 Kawasaki Jukogyo Kabushiki Kaisha Fuel supply system for small engine
US4574755A (en) * 1982-11-08 1986-03-11 Honda Giken Kogyo Kabushiki Kaisha Air/fuel ratio control device for a carburetor
US4757792A (en) * 1983-06-29 1988-07-19 Outboard Marine Corporation Internal combustion engine
US4820454A (en) * 1986-04-04 1989-04-11 Tillotson Limited Starting aid for small internal combustion engines
US4947807A (en) * 1983-06-29 1990-08-14 Outboard Marine Corporation Internal combustion engine
US5049318A (en) * 1988-11-04 1991-09-17 Tecumseh Products Company Carburetor assembly
USRE34224E (en) * 1988-11-04 1993-04-20 Tecumseh Products Company Method of making a carburetor
US6439548B2 (en) * 1999-12-28 2002-08-27 Honda Giken Kogyo Kabushiki Kaisha Overflow device for carburetor
US20110168122A1 (en) * 2010-01-12 2011-07-14 Honda Motor Co., Ltd. Carburetor and general purpose engine
US20110291306A1 (en) * 2010-05-28 2011-12-01 Stoner Dale A Retrofit Roll-Over Valve for Carburetor Float Bowl Vent Tube
US10465642B2 (en) 2017-03-27 2019-11-05 Kohler Co. Carburetor drain
US11008978B2 (en) * 2019-03-05 2021-05-18 Kohler Co. Bail driven stale fuel evacuation
US11193452B2 (en) * 2019-09-18 2021-12-07 Christopher M Graves Carburetor drain valve

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5192789U (enrdf_load_stackoverflow) * 1975-01-24 1976-07-24

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4168289A (en) * 1977-12-19 1979-09-18 Saunion Oscar P Floatless carburetor
US4254064A (en) * 1979-08-02 1981-03-03 Kohler Co. Carburetor starting mixture control
US4350124A (en) * 1979-09-29 1982-09-21 Yamaha Hatsudoki Kabushiki Kaisha Overflow device for vehicular carburetor
US4353847A (en) * 1980-12-26 1982-10-12 Kawasaki Jukogyo Kabushiki Kaisha Fuel supply system for small engine
US4574755A (en) * 1982-11-08 1986-03-11 Honda Giken Kogyo Kabushiki Kaisha Air/fuel ratio control device for a carburetor
US4757792A (en) * 1983-06-29 1988-07-19 Outboard Marine Corporation Internal combustion engine
US4947807A (en) * 1983-06-29 1990-08-14 Outboard Marine Corporation Internal combustion engine
US4820454A (en) * 1986-04-04 1989-04-11 Tillotson Limited Starting aid for small internal combustion engines
US5049318A (en) * 1988-11-04 1991-09-17 Tecumseh Products Company Carburetor assembly
USRE34224E (en) * 1988-11-04 1993-04-20 Tecumseh Products Company Method of making a carburetor
US6439548B2 (en) * 1999-12-28 2002-08-27 Honda Giken Kogyo Kabushiki Kaisha Overflow device for carburetor
US20110168122A1 (en) * 2010-01-12 2011-07-14 Honda Motor Co., Ltd. Carburetor and general purpose engine
US8550050B2 (en) * 2010-01-12 2013-10-08 Honda Motor Co., Ltd. Carburetor and general purpose engine
US20110291306A1 (en) * 2010-05-28 2011-12-01 Stoner Dale A Retrofit Roll-Over Valve for Carburetor Float Bowl Vent Tube
US8231110B2 (en) * 2010-05-28 2012-07-31 Stoner Dale A Retrofit roll-over valve for carburetor float bowl vent tube
US10465642B2 (en) 2017-03-27 2019-11-05 Kohler Co. Carburetor drain
US10823124B2 (en) 2017-03-27 2020-11-03 Kohler Co. Carburetor drain
US11125195B2 (en) 2017-03-27 2021-09-21 Kohler Co. Carburetor drain
US11408382B2 (en) 2017-03-27 2022-08-09 Kohler Co. Carburetor drain
US11614060B2 (en) 2017-03-27 2023-03-28 Kohler Co. Carburetor drain
US11008978B2 (en) * 2019-03-05 2021-05-18 Kohler Co. Bail driven stale fuel evacuation
US11591989B2 (en) 2019-03-05 2023-02-28 Kohler Co. Bail driven stale fuel evacuation
US11193452B2 (en) * 2019-09-18 2021-12-07 Christopher M Graves Carburetor drain valve

Also Published As

Publication number Publication date
CA964538A (en) 1975-03-18
JPS4854316A (enrdf_load_stackoverflow) 1973-07-31
JPS5014689B2 (enrdf_load_stackoverflow) 1975-05-29

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