US3906911A - Fast idle assembly for carburetors having automatic choke - Google Patents

Fast idle assembly for carburetors having automatic choke Download PDF

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Publication number
US3906911A
US3906911A US381423A US38142373A US3906911A US 3906911 A US3906911 A US 3906911A US 381423 A US381423 A US 381423A US 38142373 A US38142373 A US 38142373A US 3906911 A US3906911 A US 3906911A
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United States
Prior art keywords
choke
fast idle
spring means
lever
valve
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Expired - Lifetime
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US381423A
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English (en)
Inventor
Masahiko Nakada
Hirofumi Matsumoto
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Toyota Motor Corp
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Toyota Motor Corp
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Publication date
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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
    • F02M1/00—Carburettors with means for facilitating engine's starting or its idling below operational temperatures
    • F02M1/08—Carburettors with means for facilitating engine's starting or its idling below operational temperatures the means to facilitate starting or idling becoming operative or inoperative automatically
    • F02M1/10—Carburettors with means for facilitating engine's starting or its idling below operational temperatures the means to facilitate starting or idling becoming operative or inoperative automatically dependent on engine temperature, e.g. having thermostat

Definitions

  • FIG. 1 A first figure.
  • This invention relates to improvements in the fast idle mechanism of a carburetor equipped with-an automatic choke.
  • This invention has for its object provision of a fast idle assembly of a carburetor equipped with an automatic choke which, for the purpose of eliminating the foregoing disadvantages, affords an angular difference between the choke valve opening and functioning of the fast idle cam, so that the fast idle is maintained for a certain period after the choke valve'has fully opened and thus allowing the engine .to idle stably until it warms up.
  • FIG. 1 is a front view, partly in section, of a carburetor of a conventional design
  • FIG. 2 is a side view showing the inside case of the carburetor in FIG. 1;
  • FIG. 3 is a front view, partly in section,- of a carburetor having an automatic choke with a fast idle assembly embodying the present invention
  • FIGS. 4 and 5 are side .views showingthe inside of. the choke case of thecarburetor shown in FIG. :3;
  • FIG. 6 is a front view, partly in section, of another embodiment of the invention.
  • FIGS. 7 and 8 are side views showing the inside of the choke case of the carburetor shown in FIG. 6; and.
  • FIG. 9 is a graph giving characteristic curves representing changes of choke openingand fast idle speed with time.
  • FIGS. 1 and 2 there are shown a carburetor body I, a choke valve 2, a choke shaft 3, a throttle valve 4, and a throttle shaft 5.
  • a choke lever 6 To the choke shaft 3 is secured a choke lever 6 in one piece with a piston lever 7.
  • the choke lever 6 is hooked to the outer extremity of a spiraled thermostatic spring 8, the inner extremity of which is fixed to a choke case cap 9.
  • the piston lever '7 is connected at its end with one end of a connecting rod 10, the other end of which is connected to a vacof the choke uum piston (not shown) in a choke cylinder 11.
  • a fast idle cam 13 On the choke shaft 3 is revolvably mounted a fast idle cam 13 having a fast idle lever 12.
  • a relatively weak coil spring 14 is secured to the fast idle lever 12, and the other end 14b of the spring is secured to the choke lever 6.
  • This spring exerts spring force on the fast idle lever 12 and choke lever 6 to preclude any angular difference between the two levers.
  • the two levers l2, 6 are in the relative positions as in FIG. 2.
  • a throttle lever 15 which in'turn is connected to afast idle rod 17 through a link 16.
  • a cam follower 18 secured to the fast idle rod 17 is in contact with the underside of the fast idle cam 13 as long as the driver does not operate the throttle valve 4 of the engine before its warmup.
  • thefollower serves to keep the throttle wider open than during idle after warmup.
  • the fast idle mechanism of the construction so far described has been well known in the art.
  • a spiraled thermostatic spring 8 is formed with a hook 8a for engagement with a choke lever 6 and is also formed with a hook 8b for engagement with a fast idle lever 12.
  • One end 14a of a relatively weak coil spring 14' is fixedlyinserted through a small hole 19 formed in the fast idle lever 12, the other end 14b of the spring being also fixedly inserted through a small hole 20 in the choke lever 6.
  • the spring 14' biases the fast idle lever 12' and choke lever 6 to maintain a certain angular displacement (e.g., 15 or 20) therebetween. It follows that, in the absence of any other force exerted on the fast idle cam 13, the two levers I2, 6 would assume the relative positions as shown in FIG. 4. The rest of the construction is the same as that which has been described in connection with FIGS. Land 2.
  • the fast idle cam 13' is'formed in' one piece with a fast idle lever 12" and a spring lever 21with a certain angular displacement (e.g.',l5 or 20) therebe'tween.
  • One end 14a" of a relativelyweak coil spring 114" is connected to the spring lever 21.
  • the spring 14 biases the spring lever 21 and choke lever 6 lest there should occur any angular difference between the two levers. Therefore, when the fast idle cam 13 is free from any force other than the spring force, the two levers 21, 6 are in contact and in the relative positions as shown in FIG. 8. Hence there occurs an angular displacement between the choke lever 6 and fast idle lever 12".
  • the thermostatic spring 8 urges the fast idle lever 12" and choke lever 6 to turn counter-clockwise, and therefore the two levers 12", 6 are in the relative superposed positions as shown in FIG. 7, or are substantially superposed.
  • the choke lever 6 and fast idle lever 12 function, as a rule, without an angular difference therebetween. Consequently, whatever the shape of the fast idle cam 13, it is inevitable that, as indicated by the changes of fast idle speed represented by the solid line A in FIG. 9, the fast idle mechanism stops working at the point a shortly after the choke opening D has reached the maximum F, and the engine idles slowly.
  • FIGS. 3 to 5 operates in the following manner. Normally, under the urging of the spring 14, a certain angular displacement is maintained between the choke lever 6 and fast idle lever 12.
  • a fast idle cam of the shape substantially the same as that in FIGS. 1 and 2 is employed, a time lag corresponding to the angular difference will cause a change in the fast idle speed.
  • the fast idle mechanism will now be able to work with the choke valve fully open. As the temperature inside the choke case rises with the lapse of time, the hooks 8a, 8b of the thermostatic spring 8 turn clockwise.
  • the operation of the second embodiment shown in FIGS. 6 to 8 is as follows.
  • the choke lever 6 and spring lever 21 are biased by the spring 14 so that there is practically no angular difference therebetween as shown in FIG. 8.
  • the fast idle lever 12' is hooked by the outer end of the theremostatic spring 8 and is turned counter-clockwise against the urging of the spring 14", with the result that the choke valve 2 is closed as in an ordinary carburetor.
  • the fast idle mechanism of a conventional carburetor of the automatic choke type is released once the choke valve is fully opened and, moreover. It is a recent trend that the choke valve is often set to open rather prematurely for the purpose of emission control. This causes the release of the fast idle mechanism prior to the engine warmup and sometimes results in unstable idling or even engine stall.
  • the fast idle mechanism can continue to work after the choke valve opening D has reached the full open position F, and. even with early opening of the choke, the engine is enabled to idle stably before it warms up.
  • the invention is contributory to the prevention of air pollution. This purpose can be fully achieved with only a slight modification of an existing fast idle assembly in accordance with the present invention.
  • a carburetor of the automatic choke type including a fast idle mechanism for an internal combustion engine comprising a throttle valve, a choke valve, a choke shaft having said choke valve fixedly mounted thereon, a choke lever mechanism fixedly mounted to said choke shaft, a fast idle cam revolvably mounted to said choke shaft, linkage means operatively interconnecting said fast idle cam and said throttle valve to control the idling position of said throttle valve, first spring means operatively connected between said choke lever mechanism and said fast idle cam to effect a predetermined angular displacement therebetween, and second spring means having a first and a second end with the first end of said second spring means fixed relative to said carburetor and with the second end of said second spring means including a first engagement member for engaging said choke lever and a second engagement member for engaging said fast idle cam, said second spring means being thermostatically responsive to the operating temperature of said engine to control the opening of said choke valve and the working angle of said fast idle cam, said second thermostatically responsive spring means cooperating with said first spring means to effect continued operation of said fast

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Means For Warming Up And Starting Carburetors (AREA)
US381423A 1972-08-10 1973-07-23 Fast idle assembly for carburetors having automatic choke Expired - Lifetime US3906911A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7946272A JPS5435261B2 (enrdf_load_stackoverflow) 1972-08-10 1972-08-10

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US3906911A true US3906911A (en) 1975-09-23

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3962379A (en) * 1975-09-30 1976-06-08 Ford Motor Company Carburetor cold enrichment system having automatic choke opener and fast idle cam high step pulloff apparatus
US3962380A (en) * 1975-10-14 1976-06-08 Ford Motor Company Carburetor with combined choke pulldown and fast idle cam kickdown apparatus
US4005690A (en) * 1975-06-23 1977-02-01 Honda Giken Kogyo Kabushiki Kaisha Automatic choke valve apparatus in an internal combustion engine
US4196156A (en) * 1977-01-26 1980-04-01 Ford Motor Company Carburetor with limited interconnected choke valve and fast idle cam
US4226814A (en) * 1979-03-05 1980-10-07 Ford Motor Company Carburetor
US4351782A (en) * 1980-02-06 1982-09-28 Weber S.P.A Cold-engine starting and operating devices for carburetors
US4439377A (en) * 1981-03-03 1984-03-27 Regie Nationale Des Usines Renault Carburetor for an internal combustion motor
US4524742A (en) * 1982-12-20 1985-06-25 Weber S.P.A. Carburetor having electronically controlled elements for maintaining engine idling speed at a constant level and for controlling choke-valve position during a warm-up phase
US4615845A (en) * 1984-04-25 1986-10-07 Honda Giken Kogyo Kabushiki Kaisha Variable venturi type carburetor and associated method
US6779785B2 (en) * 2002-07-25 2004-08-24 Walbro Engine Management, L.L.C. Self-relieving choke adjustment apparatus
US20090293828A1 (en) * 2008-05-27 2009-12-03 Briggs & Stratton Corporation Engine with an automatic choke and method of operating an automatic choke for an engine
US20120161342A1 (en) * 2010-12-28 2012-06-28 Shebuski David R Carburetor with one piece choke valve and shaft assembly
US20130106002A1 (en) * 2011-10-26 2013-05-02 Mikuni Corporation Carburetor Choke Mechanism

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS559547B2 (enrdf_load_stackoverflow) * 1973-03-23 1980-03-11
JPS552842U (enrdf_load_stackoverflow) * 1978-06-20 1980-01-10
JPS60194854U (ja) * 1984-06-06 1985-12-25 三菱電機株式会社 熱動式過電流継電器

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2189219A (en) * 1933-01-13 1940-02-06 Bendix Aviat Corp Carburetor
US2348544A (en) * 1939-10-23 1944-05-09 Gen Motors Corp Automatic choke mechanism
US2410758A (en) * 1941-07-20 1946-11-05 Bendix Aviat Corp Carburetor
US2415529A (en) * 1940-10-24 1947-02-11 Gen Motors Corp Thermostatic throttle stop
US2957465A (en) * 1958-05-23 1960-10-25 Gen Motors Corp Fast opening choke mechanism
US3109874A (en) * 1961-02-20 1963-11-05 Sibe Carburetors comprising an auxiliary device to increase the fuel feed for cold starting conditions
US3185453A (en) * 1961-07-17 1965-05-25 Sibe Carburetors

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2189219A (en) * 1933-01-13 1940-02-06 Bendix Aviat Corp Carburetor
US2348544A (en) * 1939-10-23 1944-05-09 Gen Motors Corp Automatic choke mechanism
US2415529A (en) * 1940-10-24 1947-02-11 Gen Motors Corp Thermostatic throttle stop
US2410758A (en) * 1941-07-20 1946-11-05 Bendix Aviat Corp Carburetor
US2957465A (en) * 1958-05-23 1960-10-25 Gen Motors Corp Fast opening choke mechanism
US3109874A (en) * 1961-02-20 1963-11-05 Sibe Carburetors comprising an auxiliary device to increase the fuel feed for cold starting conditions
US3185453A (en) * 1961-07-17 1965-05-25 Sibe Carburetors

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4005690A (en) * 1975-06-23 1977-02-01 Honda Giken Kogyo Kabushiki Kaisha Automatic choke valve apparatus in an internal combustion engine
US3962379A (en) * 1975-09-30 1976-06-08 Ford Motor Company Carburetor cold enrichment system having automatic choke opener and fast idle cam high step pulloff apparatus
US3962380A (en) * 1975-10-14 1976-06-08 Ford Motor Company Carburetor with combined choke pulldown and fast idle cam kickdown apparatus
US4196156A (en) * 1977-01-26 1980-04-01 Ford Motor Company Carburetor with limited interconnected choke valve and fast idle cam
US4226814A (en) * 1979-03-05 1980-10-07 Ford Motor Company Carburetor
US4351782A (en) * 1980-02-06 1982-09-28 Weber S.P.A Cold-engine starting and operating devices for carburetors
US4439377A (en) * 1981-03-03 1984-03-27 Regie Nationale Des Usines Renault Carburetor for an internal combustion motor
US4524742A (en) * 1982-12-20 1985-06-25 Weber S.P.A. Carburetor having electronically controlled elements for maintaining engine idling speed at a constant level and for controlling choke-valve position during a warm-up phase
US4615845A (en) * 1984-04-25 1986-10-07 Honda Giken Kogyo Kabushiki Kaisha Variable venturi type carburetor and associated method
US6779785B2 (en) * 2002-07-25 2004-08-24 Walbro Engine Management, L.L.C. Self-relieving choke adjustment apparatus
US20090293828A1 (en) * 2008-05-27 2009-12-03 Briggs & Stratton Corporation Engine with an automatic choke and method of operating an automatic choke for an engine
US8434444B2 (en) * 2008-05-27 2013-05-07 Briggs & Stratton Corporation Engine with an automatic choke and method of operating an automatic choke for an engine
US20120161342A1 (en) * 2010-12-28 2012-06-28 Shebuski David R Carburetor with one piece choke valve and shaft assembly
US8695952B2 (en) * 2010-12-28 2014-04-15 Usa Zama Inc. Carburetor with one piece choke valve and shaft assembly
US9316176B2 (en) 2010-12-28 2016-04-19 Usa Zama Inc. Carburetor with one piece choke valve and shaft assembly
US9828946B2 (en) 2010-12-28 2017-11-28 Usa Zama Inc. Carburetor with one piece choke valve and shaft assembly
US20130106002A1 (en) * 2011-10-26 2013-05-02 Mikuni Corporation Carburetor Choke Mechanism
US8657264B2 (en) * 2011-10-26 2014-02-25 Mikuni Corporation Carburetor choke mechanism

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Publication number Publication date
JPS5435261B2 (enrdf_load_stackoverflow) 1979-11-01
JPS4935728A (enrdf_load_stackoverflow) 1974-04-02

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