US3903211A - Control mechanism and method for dual carburetors - Google Patents

Control mechanism and method for dual carburetors Download PDF

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Publication number
US3903211A
US3903211A US477974A US47797474A US3903211A US 3903211 A US3903211 A US 3903211A US 477974 A US477974 A US 477974A US 47797474 A US47797474 A US 47797474A US 3903211 A US3903211 A US 3903211A
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United States
Prior art keywords
throttle valve
primary
barrel
diaphragm
venturi
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Expired - Lifetime
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US477974A
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English (en)
Inventor
Tadayoshi Kono
Takao Okuno
Mikio Kuno
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Toyota Motor Corp
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Toyota Motor Corp
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Publication date
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Publication of US3903211A publication Critical patent/US3903211A/en
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    • 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
    • F02M11/00—Multi-stage carburettors, Register-type carburettors, i.e. with slidable or rotatable throttling valves in which a plurality of fuel nozzles, other than only an idling nozzle and a main one, are sequentially exposed to air stream by throttling valve
    • F02M11/02—Multi-stage carburettors, Register-type carburettors, i.e. with slidable or rotatable throttling valves in which a plurality of fuel nozzles, other than only an idling nozzle and a main one, are sequentially exposed to air stream by throttling valve with throttling valve, e.g. of flap or butterfly type, in a later stage opening automatically

Definitions

  • a throttle valve disposed in the secondary barrel of a dual carburetor is controlled by a diaphragm movable in response to pressures applied on opposite sides thereof.
  • One side of the diaphragm has applied thereto a combined pressure derived from each of the venturis in the primary and secondary barrels of the carburetors.
  • the other side of the diaphragm has applied thereto a combined pressure derived from the primary and secondary barrels at points therein upstream of the venturi with the point in the primary barrel being selected from between the venturi and a choke valve located in said primary barrel.
  • Displacement of the diaphragm caused by pressure imbalances on opposite sides thereof is communicated to the throttle valve in the secondary barrel through a linkage means to control operation of the secondary barrel throttle valve.
  • the present invention relates generally to dual carburetors for internal combustion engines which include an automatic choke unit, and more particularly to a dual carburetor of the type in which a throttle valve in the secondary barrel of the carburetor may be controlled in response to both the opening of the choke valve in the primary carburetor barrel and the operating conditions of the engine.
  • the opening of a throttle valve which is located in the secondary carburetor barrel is controlled by a diaphragm which has applied thereto pressure differences between the pressure at the venturi tubes of the primary and secondary carburetor barrels and the pressure downstream of a choke valve located in the primary carburetor barrel.
  • the choke valve is so arranged that it will be automatically controlled in response to movement of a bimetal' lic spring member or the like, depending upon the operating conditions of the engine. As a result, the choke valve will be closed before the engine is sufficiently warmed up and the pressures acting upon the diaphragm will become equal to each other so that the diaphragm will not undergo displacement before sufficient engine warming is achieved thereby holding the throttle valve in the secondary carburetor barrel closed.
  • a diaphragm which controls the opening of the throttle valve located in the secondary carburetor barrel, with the diaphragm being actuated in response to pressure differences between atmospheric pressure and the pressure at the venturis in the primary and secondary carburetor barrels.
  • the throttle valve in the secondary carburetor barrel will be opened or closed only in response to the pressures at the venturi tubes and independently of the level of opening of the choke valve in the primary carburetor barrel. Therefore, excessive amounts of air will be charged into the combustion chambers of the engine during a time when a rich fuelair mixture should be supplied. Thus, a lean fuel-air mixture will be supplied into the combustion chamber of the engine and, again, insufficient engine power will be developed.
  • the present invention is intended to provide a dual carburetor of the type in which the opening of the throttle valve located in the secondary carburetor barrel may be controlled in an optimum manner under any operating condition of the internal combustion engine to which the carburetor is applied.
  • the present invention may be described as a control system for a dual carburetor having a primary barrel including first venturi means and a first throttle valve located on one side thereof, a secondary barrel including second venturi means and a second throttle valve located on one side thereof, and a choke valve located in the primary barrel on the side of said first venturi means opposite said first throttle valve.
  • a movable diaphragm is mounted to divide a diaphragm chamber into a pair of pressure chambers with one of said pressure chambers being communicated with ports opening into the passages of the primary and secondary carburetor barrels, said ports being equivalently spaced, respectively, from said first and second venturis, with the port opening into the primary barrel being located downstream of the choke valve between the choke valve and the first venturi.
  • the other pressure chamber is communicated with ports opening directly into the venturi sections of both carburetor barrels.
  • FIG. 1 is a schematic diagram of an engine having a dual carburetor constructed in accordance with the present invention.
  • FIG. 2 is a schematic sectional view of the dual earburetor shown in FIG. 1 incorporating the features of the present invention.
  • a dual carburetor 1 comprising a primary barrel 2 and a secondary barrel 3. Air is introduced into the air intake section of the carburetor through an air cleaner 4 with an intake manifold 5 operating to deliver air-fuel mix 1 ture to the combustion chamber 6 of an internal com bustion engine.
  • the primary carburetor barrel 2 includes a choke valve 8 which is automatically opened and closed by a bimetallic spring member 7.
  • the choke valve 8 is located within the primary barrel 2 on one side of a large venturi tube 9 and a throttle valve 10 located on the opposite side of the venturi tube 9 is operatively coupled to an accelerator pedal (not shown).
  • a small venturi tube 11 is disposed within the large venturi 9 and a nozzle 14 extends into the small venturi 11 from a float chamber 12 through a passage 13.
  • the secondary carburetor barrel 3 also includes a large venturi 9', a small venturi 11, a nozzle 14', and
  • a shaft of the throttle valve 10 of the secondary carburetor barrel 3 is operatively coupled by a linkage mechanism 18 to a diaphragm 17 which is disposed within a casing 16.
  • the opening of the throttle valve 10' is controlled in response to movement of the diaphragm 17 through operation of the linkage mechanism 18.
  • the casing 16 is divided by the diaphragm 17 into a pair of pressure chambers 19 and 20, with the pressure chamber 19, located to the left in FIG. 2, being communicated with a pressure intake port 21 opening into the primary carburetor barrel 3 at a point downstream of the closed choke valve 8.
  • a tube 23 having inserted therein a nozzle or orifice 22 extends between the port 21 and the chamber 19.
  • the coefficients of the nozzle orifices 22 and 23 are so selected that a desired pressure difference may be produced between the two pressure chambers 19 and 20. That is, the pressure transmitted to the pressure chamber 19 is such that it represents a balance between the pressures at the pressure intake ports 21 and 21.
  • Pressure chamber 20 shown to the right in FIG. 2, is communicated through a tube 28 with a passage 27 which, in turn, is communicated with ports 26 and 26 opening at the large venturis 9 and 9', respectively.
  • the bimetallic spring 7 will not undergo movement and the choke valve 8 is almost closed thereby providing only a small opening in the choke section.
  • the negative pressure developed at the large venturi 9 in the primary carburetor barrel 2 is low. Therefore, the balanced pressure between this negative pressure and the atmospheric pressure existing at the large venturi 9 in the secondary carburetor barrel 3 will be transmitted through the openings 26 and 26, the passage 27 and the conduit 28 to the right pressure chamber 20.
  • the balanced pressure obtained between the pressures at the ports 21 and 21 is almost equal to atmospheric pressure and it is applied to the left pressure chamber 19. Therefore, the pressure difference between the two pressure chambers 19 and will be low and, therefore, the diaphragm 27 will not be displaced. As a result, the throttle valve 10 in the secondary carburetor barrel 3 will be held in its closed position.
  • the bimetallic spring 7 When the engine is sufficiently warmed up, the bimetallic spring 7 will be heated and, accordingly, the choke valve 8 will be opened.
  • the negative pressure at the opening 26 of the primary carburetor barrel 2 will be higher than at the opening 21.
  • the balanced pressure will be transmitted to the right pressure chamber 20 through the ports 26 and 26, the passage 27 and the conduit 28. Since the negative pressure in the right pressure chamber 20 will be higher than that in the left pressure chamber 19, the diaphragm 17 will be displaced to the right, as seen in FIG. 2, thereby causing the throttle valve 10' to open through operation of the linkage mechanism 18 connected to the shaft 15. Accordingly, sufficient fuel and air will again be supplied to the combustion chamber 6 of the engine.
  • the throttle valve in the second carburetor barrel may be opened, even when the choke'valve is closed, depending upon the operating conditions of the engine so that a fuel-air mixture having an optimum air-fuel ratio may be delivered into the combustion chamber of the engine despite any changes in the operating conditions of the engine. Therefore, undesireable decrease in engine output may be prevented. Furthermore, there is eliminated the need for a reloader for controlling the opening of the throttle valve in the secondary carburetor barrel and, as a result, the construction of the dual carburetor is, in accordance with the present invention, greatly simplified and improved.
  • a control mechanism for said second throttle valve comprising a diaphragm chamber having a diaphragm therein dividing said diaphragm chamber into a pair of pressure chambers, said diaphragm being displaceable in response to pressure differences between said chambers, linkage means interconnecting said diaphragm with said second throttle valve for movement thereof in response to displacement of said diaphragm.
  • first conduit means for applying to one of said pressure chambers the pressures within both said first and said second venturi means
  • second conduit means for applying to the other of said pressure chambers pressures from both said primary and secondary barrels taken at points therein substantially equivalently spaced from said first and second venturi means on the sides thereof, respectively
  • said point in said primary barrel being located between said choke valve and said first venturi means.
  • a control mechanism comprising a pair of conduits each extending, respectively, between said points in said primary and secondary barrels and said other pressure chamber, said control latter further including first and second nozzle means located, respectively, in each of said pair of conduits.
  • a method for operating a dual carburetor having a primary barrel including first venturi means and a first throttle valve located on one side thereof, a second barrel including second venturi means and a second throttle valve located on one side thereof, and a choke valve located in said primary barrel on a side of said first venturi means opposite said first throttle valve,
  • said method comprising the steps of combining pressures taken respectively from within said first and said second venturi means to derive therefrom a first combined control pressure, combining pressures taken respectively from points from within said primary and secondary barrels, said points being substantially equivalently spaced from said first and said second venturi means on a side of each of said venturi means opposite said throttle valves to derive therefrom a second combined control pressure, said point within said primary barrel being selected from between said choke valve and said first venturi means, and applying said first and said second combined control pressures to control operation of said second throttle valve in accordance with differences between said control pressures.

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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)
US477974A 1973-08-11 1974-06-10 Control mechanism and method for dual carburetors Expired - Lifetime US3903211A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1973093998U JPS5220598Y2 (en, 2012) 1973-08-11 1973-08-11

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US3903211A true US3903211A (en) 1975-09-02

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JP (1) JPS5220598Y2 (en, 2012)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4075993A (en) * 1975-09-03 1978-02-28 Robert Bosch Gmbh Fuel mixture control apparatus
US4096211A (en) * 1975-10-01 1978-06-20 Regie Nationale Des Usines Renault Variable flow elastic nozzle
US4103657A (en) * 1975-06-13 1978-08-01 Nissan Motor Company, Limited Twin-barrel carburetor with an air-fuel ratio control device
US4271801A (en) * 1977-10-12 1981-06-09 Toyota Jidosha Kogyo Kabushiki Kaisha Internal combustion engine with twin intake ports for each cylinder
US4373485A (en) * 1980-07-14 1983-02-15 Nissan Motor Company, Limited Carburetor for an internal combustion engine
KR100304277B1 (ko) * 1997-12-30 2001-11-30 이계안 디젤엔진의2단드로틀밸브

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3013777A (en) * 1958-09-04 1961-12-19 Acf Ind Inc Remote control mechanism for pneumatic and hydraulic systems
US3186691A (en) * 1961-05-25 1965-06-01 Holley Carburetor Co Control means for the secondary induction passage of a two-stage carburetor
US3223391A (en) * 1962-10-26 1965-12-14 Jr Warner B Shepherd Carburetor
US3249099A (en) * 1962-10-01 1966-05-03 Holley Carburetor Co Multi-stage carburetor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3013777A (en) * 1958-09-04 1961-12-19 Acf Ind Inc Remote control mechanism for pneumatic and hydraulic systems
US3186691A (en) * 1961-05-25 1965-06-01 Holley Carburetor Co Control means for the secondary induction passage of a two-stage carburetor
US3249099A (en) * 1962-10-01 1966-05-03 Holley Carburetor Co Multi-stage carburetor
US3223391A (en) * 1962-10-26 1965-12-14 Jr Warner B Shepherd Carburetor

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4103657A (en) * 1975-06-13 1978-08-01 Nissan Motor Company, Limited Twin-barrel carburetor with an air-fuel ratio control device
US4075993A (en) * 1975-09-03 1978-02-28 Robert Bosch Gmbh Fuel mixture control apparatus
US4096211A (en) * 1975-10-01 1978-06-20 Regie Nationale Des Usines Renault Variable flow elastic nozzle
US4271801A (en) * 1977-10-12 1981-06-09 Toyota Jidosha Kogyo Kabushiki Kaisha Internal combustion engine with twin intake ports for each cylinder
US4373485A (en) * 1980-07-14 1983-02-15 Nissan Motor Company, Limited Carburetor for an internal combustion engine
KR100304277B1 (ko) * 1997-12-30 2001-11-30 이계안 디젤엔진의2단드로틀밸브

Also Published As

Publication number Publication date
JPS5039629U (en, 2012) 1975-04-23
JPS5220598Y2 (en, 2012) 1977-05-12

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