US3784172A - Carburetor for internal combustion engines - Google Patents

Carburetor for internal combustion engines Download PDF

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Publication number
US3784172A
US3784172A US00296530A US3784172DA US3784172A US 3784172 A US3784172 A US 3784172A US 00296530 A US00296530 A US 00296530A US 3784172D A US3784172D A US 3784172DA US 3784172 A US3784172 A US 3784172A
Authority
US
United States
Prior art keywords
air
fuel
mixture passage
front side
rear side
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
US00296530A
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English (en)
Inventor
T Sato
T Masago
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.)
Nissan Motor Co Ltd
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Nissan Motor Co Ltd
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 Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
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Publication of US3784172A publication Critical patent/US3784172A/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
    • F02M13/00—Arrangements of two or more separate carburettors; Carburettors using more than one fuel
    • F02M13/02—Separate carburettors
    • F02M13/025—Equalizing pipes between the carburettors, e.g. between the float chambers
    • 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
    • F02M7/00—Carburettors with means for influencing, e.g. enriching or keeping constant, fuel/air ratio of charge under varying conditions
    • F02M7/12—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves
    • F02M7/14—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves with means for controlling cross-sectional area of fuel spray nozzle
    • F02M7/16—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves with means for controlling cross-sectional area of fuel spray nozzle operated automatically, e.g. dependent on exhaust-gas analysis
    • F02M7/17—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves with means for controlling cross-sectional area of fuel spray nozzle operated automatically, e.g. dependent on exhaust-gas analysis by a pneumatically adjustable piston-like element, e.g. constant depression carburettors

Definitions

  • twin carburetor of the variable-area choke type for use in multi-cylinder engine of a motor vehicle which twin carburetor includes a balance tube interconnecting a front side mixture passage and a rear side mixture passage at a point downstream of each throttle valve for balancing the pressures therein to equalize the amounts of air-fuel mixtures to be supplied to individual cylinders of the engine and an additional balance tube interconnecting the front side mixture passage and the rear side mixture passage at a point downstream of each choke for balancing the suctions or depressions acting on each air valve to provide the same effective cross-sectional area at each fuel jet for thereby producing air-fuel mixtures having equal airfuel ratios in each mixture passage.
  • a well known carburetor of this type known as the S.U. twin carburetor, usually includes an air valve provided upstream of a throttle valve and movable in dependence on the suction or depression prevailing at the choke of the carburetor, the air valve carrying thereon a tapered metering needle adapted to vary the open effective cross-sectional area of a fuel jet thereby to vary the air-fuel ratio of an air-fuel mixture to be supplied to groups of individual cylinders of an internal combustion engine.
  • the carburetor of this kind as the engine speed or the engine load increases, then the effective choke area and accordingly the effective cross-sectional area of the fuel jet are enlarged since the air valve lift is proportional to the volume of air passing through the throttle valve.
  • Conventional twin carburetors of the type abovespecified usually employ a front side mixture passage having therein a front side throttle valve and a rear side mixture passage having therein a rear side throttle valve.
  • the arrangement is such that the front side throttle valve and the rear side throttle valve are opened simultaneously through the use ofa suitable common throttle actuating mechanism.
  • it is a common practice to provide a throttle actuating mechanism for opening and closing both throttle valves to the same ratio with a view of supplying the groups of individual engine cylinders with an equal amount and equal airfuel ratio of the air-fuel mixture.
  • the twin carburetors of the type above-described equipped with a balance tube connecting the front side and rear side mixture passages at a point downstream of each of the throttle valves with a view of balancing the pressures and thus ensuring a more equal mixture distribution to the individual cylinders.
  • a difficulty is encountered in this prior art method is that, if there is a pressure difference between the front side mixture passage and the rear side mixture passage at a point downstream of each choke due to differencial opening between the two throttle valves, different extents of valve lifts are caused in the air valves of the front side and rear side mixture passages and, therefore, the fuel jets of the front side and rear side mixture passages are opened to different degrees. This results in uneven charges of fuel from each fuel jet to provide air-fuel mixtures of unequal air-fuel ratios which invites irregular operation of the engine.
  • an object of the present invention to provide a new and improved carburetor of the variablearea choke type for use in an internal combustion engine of a motor vehicle whereby a maximum engine performance efficiency will be obtained throughout varying operating conditions of the engine.
  • Another object of the present invention is to provide a new and improved twin carburetor of the type abovespecified for use in a multi-cylinder engine of a motor vehicle.
  • Still another object of the present invention is to provide a twin carburetor of the type above-specified which is capable of increasing engine performence efficiency throughout various operating conditions of the engine.
  • a further object of the present invention is to provide a twin carburetor of the type above-specified which is adapted to improve the charging of the groups of individual cylinders of the engine and therefore engine performance efficiency.
  • a further object of the present invention is to provide a twin carburetor of the type above-specified which is arranged to supply the groups of individual cylinders of the engine with air-fuel mixtures of equalized air-fuel ratios.
  • a still further object of the present invention is to provide a twin carburetor of the type above-specified which is arranged to equalize the air-fuel ratios of airfuel mixtures to be delivered to individual cylinders of a multi-cylinder engine and to give equal mixture distribution to the groups of individual cylinders for thereby improving engine performance efficiency.
  • a twin carburetor of the variable-area choke type which is specifically adapted for use in a multi-cylinder engine ofa motor vehicle.
  • This carburetor includes a front side mixture passage having therein a front side throttle valve and a rear side mixture passage having therein a rear side throttle valve, the arrangement being such that the front side and rear side throttle valves are simultaneously opened.
  • the twin carburetor is provided with a first balance tube connecting the front side mixture passage and the rear side mixture passage at a point downstream of respective throttle valves and a second balance tube connecting the front side mixture passage and the rearside mixture passage at a point between the choke and the throttle valve.
  • the first balance tube serves to balance the pressures in the front side and rear side mixture passages downstream of the respective throttle valves for thereby equalizing the quantities of air-fuel mixtures to be supplied through respective mixture passages to the groups of individual cylinders.
  • the second balance tube serves to balance the pressures in the front side and rear side mixture passages downstream of the respective chokes for equalizing the extents of lifts of respective air valves so that an equal cross sectional area is obtained at each fuel jet of each mixture passage for thereby producing air-fuel mixtures of present invention is specifically suited for use in a multi-cylinder engine of a motor vehicle.
  • the twin carburetor includes as customary a front side and a rear side 10'.
  • the front side 10 is composed of a front side mixture passage 12 which communicates with intake manifolds 14 of the engine which intake manifolds lead to a series of groups of individual cylinders (not shown), a front side throttle valve 16 mounted in the front side mixture passage 12 for controlling the quantity of air-fuel mixture to be supplied to the individual cylinders through the intake manifolds 14, and a choke 18 including an air valve or flow regulating means 20 and a constriction or bridge 22.
  • the front side 10 is also composed of a fuel jet 24 through which fuel is drawn into the choke 18.
  • the air valve 20 comprises a casing 26 and a movable suction piston 28 of known construction.
  • a metering needle is carried on the bottom wall of the suction piston 28 and extends into the fuel jet 24 for metering the amount of fuel to be drawn into the choke 18.
  • the metering needle 30 is tapered toward its tip for continuously changing the open effective cross-sectional area of the fuel jet 24 for thereby varying the amounts of fuel to be drawn into the choke 18 as the suction piston 28 and accordingly the metering needle 30 move upwardly and downwardly in response to the fluctuations in the depression in the front side mixture passage 12 upstream of the front side throttle valve 16 to thereby vary the effective cross-sectional area at the choke 18 into which the liquid fuel is drawn from the fuel jet 24.
  • the rear side 10' is composed of a rear side mixture passage 12 communicating with intake manifolds 14' leading to another series of individual cylinders (not shown), a rear side throttle valve 16' mounted in the rear side mixture passage 12' for controlling the quantity of airfuel mixture to be supplied to the individual cylinders through the intake manifolds 14', and a choke 18' including an air valve or flow regulating means 20 and a constriction or bridge 22'.
  • the rear side 10 is also composed of a fuel jet 24 through which fuel is drawn into the choke 18'
  • the air valve 20 comprises a casing 26' and a movable piston 28' of known construction, the suction piston 28 carrying at its bottom wall a metering needle 30' which extends through the fuel jet 24' for varying the effective cross-sectional area of the fuel jet 24.
  • the front side throttle valve 16 and the rear side throttle valve 16 are associated with each other by means of a suitable common throttle actuating mechanism so that these throttle valves are opened simultaneously to the same opening degree for supplying the groups of individual cylinders with air-fuel mixtures of equal quantities and equal air-fuel ratios, respectively. If, however, there exists a difference in opening degrees between the two throttle valves as seen in the drawing, that is, if the the opening degree of the, e.g., front side throttle valve 16 is larger than that of the rear side throttle valve 16', then the front side throttle valve 16 permits the air-fuel mixture to flow into the intake manifolds 14 at an amount which is larger than that delivered through the rear side mixture passage 12'. This causes irregular operation of the engine and therefore reduction in power output.
  • a balance tube 32 is provided in the twin carburetor. As shown in the drawing, the balance tube 32 is connected between the front side mixture passage 12 and the rear side mixture passage 12' at a point downstream of each throttle valve. This balance tube 32 serves to balance the pressures P, and P prevailing in the front side mixture passage 12 and the rear side mixture passage 12 downstream of the front side throttle valve 16 and the rear side throttle valve 16', respectively, so that same amounts of air-fuel mixtures are drawn into the intake manifolds l4 and 14, respectively.
  • the twin carburetor there is provided in the twin carburetor an additional balance tube 34 with a view of equalizing the air-fuel ratios of the air-fuel mixtures to be delivered to the groups of individual cylinders.
  • the balance tube 34 is interconnected between the front side mixture passage 12 and the rear side mixture passage 12' at a point downstream of each choke l8 and 18'.
  • This balance tube 34 serves to balance the suctions or depressions S, and S prevailing in the front side mixture passage 12 and the rear side mixture passage 12' downstream of the chokes 18 and 18', respectively, so that the valve lifts of the air valves 20 and 20 are equalized to cause the respective metering needles 30 and 30 to move to the same extent for thereby providing equal cross-sectional area at the fuel jets 24 and 24, respectively.
  • the depression S, prevailing downstream of the choke 18 is larger than the depression S prevailing in the rear side mixture passage 12'.
  • the depression S is partially transmitted through the balance tube 34 into the rear side mixture passage 12' downstream of the choke 18' as shown by unnumbered arrows until the latter reaches the level of the depression S,.
  • the (extents of) valve lifts (h, and k are equalized so that the metering needles 30 and 30' provide equal cross-sectional areas at the fuel jets 24 and 24' thereby producing air-fuel mixtures having an equal air-fuel ratio at the chokes l8 and 18', respectively.
  • twin carburetor of the present invention advantageously incorporates an additional balance tube interconnecting the front side mixture passage and the rear side mixture passage at a point downstream of each choke whereby the depressions acting on the air valves are equalized to provide the same extents of valve lifts for providing the same effective crosssectional areas at the fuel jets for thereby equalizing the air-fuel ratios of air-fuel mixtures to be supplied to the individual engine cylinders.
  • a twin carburetor for an internal combustion engine of a multi-cylinder type comprising at least two mixture passages adapted to supply air-fuel mixtures to groups of individual cylinders of said engine, at least two throttle valves disposed in said mixture passages respectively for controlling the amounts of the air-fuel mixtures to be supplied to said groups ofindividual cylinders, at least two chokes provided upstream of said throttle valves, respectively, each of said chokes including a movable air valve and a constriction, at least two fuel jets each opening into each of said chokes for supplying fuel thereinto, and a balance tube interconnecting said two mixture passages at a point downstream of said throttle valves for balancing the pressures in said mixture passages downstream of said throttle valves for thereby equalizing the amounts of the air-fuel mixtures to be supplied to said groups of individual cylinders, and an additional balance tube interconnecting said two mixture passages at a point downstream of said chokes for balancing the depressions prevailing therein and acting on said air valves for thereby

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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)
  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
US00296530A 1971-10-19 1972-10-11 Carburetor for internal combustion engines Expired - Lifetime US3784172A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1971096618U JPS4850722U (el) 1971-10-19 1971-10-19

Publications (1)

Publication Number Publication Date
US3784172A true US3784172A (en) 1974-01-08

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Family Applications (1)

Application Number Title Priority Date Filing Date
US00296530A Expired - Lifetime US3784172A (en) 1971-10-19 1972-10-11 Carburetor for internal combustion engines

Country Status (5)

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US (1) US3784172A (el)
JP (1) JPS4850722U (el)
DE (1) DE2251049C3 (el)
FR (1) FR2157565A5 (el)
GB (1) GB1357273A (el)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4502435A (en) * 1978-03-24 1985-03-05 Mazda Motor Corporation Intake system for multiple cylinder internal combustion engine
US4508189A (en) * 1981-08-03 1985-04-02 Yamaha Hatsudoki Kabushiki Kaisha Motorcycle
US5648023A (en) * 1993-11-30 1997-07-15 Suzuki Kabushiki Kaisha Vacuum response type carburetor

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5519946A (en) * 1978-07-31 1980-02-13 Toyota Motor Corp Intake system for multi-cylinder internal combustion engine
JPS5525543A (en) * 1978-08-10 1980-02-23 Toyota Motor Corp Intake apparatus of multicylinder internal combustion engine
IT1161115B (it) * 1983-03-16 1987-03-11 Alfa Romeo Auto Spa Impianto di aspirazione a risonanza per motori a c.i.

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2765780A (en) * 1954-01-20 1956-10-09 Gen Motors Corp Intake and exhaust manifold
US2896597A (en) * 1957-08-07 1959-07-28 Robert E Patrick Carburetor adapter for internal combustion engines
GB935882A (en) * 1960-07-29 1963-09-04 Sibe Improvements in or relating to carburetting apparatus
US3698371A (en) * 1970-04-28 1972-10-17 Toyo Kogyo Co Surging prevention device for use in vehicle having multicylinder spark-ignition internal combustion engine

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2765780A (en) * 1954-01-20 1956-10-09 Gen Motors Corp Intake and exhaust manifold
US2896597A (en) * 1957-08-07 1959-07-28 Robert E Patrick Carburetor adapter for internal combustion engines
GB935882A (en) * 1960-07-29 1963-09-04 Sibe Improvements in or relating to carburetting apparatus
US3698371A (en) * 1970-04-28 1972-10-17 Toyo Kogyo Co Surging prevention device for use in vehicle having multicylinder spark-ignition internal combustion engine

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4502435A (en) * 1978-03-24 1985-03-05 Mazda Motor Corporation Intake system for multiple cylinder internal combustion engine
US4508189A (en) * 1981-08-03 1985-04-02 Yamaha Hatsudoki Kabushiki Kaisha Motorcycle
US5648023A (en) * 1993-11-30 1997-07-15 Suzuki Kabushiki Kaisha Vacuum response type carburetor

Also Published As

Publication number Publication date
FR2157565A5 (el) 1973-06-01
JPS4850722U (el) 1973-07-03
GB1357273A (en) 1974-06-19
DE2251049A1 (de) 1973-04-26
DE2251049B2 (de) 1978-03-30
DE2251049C3 (de) 1978-11-09

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