US3752133A - Multiple heat automatic choke - Google Patents

Multiple heat automatic choke Download PDF

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Publication number
US3752133A
US3752133A US00306776A US3752133DA US3752133A US 3752133 A US3752133 A US 3752133A US 00306776 A US00306776 A US 00306776A US 3752133D A US3752133D A US 3752133DA US 3752133 A US3752133 A US 3752133A
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United States
Prior art keywords
choke
choke valve
passage
temperature
heat
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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
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US00306776A
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English (en)
Inventor
D Irish
R Junttonen
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Ford Motor Co
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Ford Motor Co
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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
    • F02M1/12—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 with means for electrically heating thermostat
    • 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

  • This invention relates, in general, to a carburetor for a motor vehicle engine. More particularly, it relates to an automatic choke to control the idle speed of the engine during cold weather starts, while at the same time minimizing the output of undesirable emissions.
  • a choke mechanism is generally provided to lessen the air intake during cold starting and pre-engine warmup to insure a richer mixture.
  • the choke apparatus includes a coiled thermostatic spring that operatively rotates the choke valve towards a closed or nearly shut position with decreasing temperatures, and progressively opens it as the temperature returns towards a chosen level.
  • a manifold suction responsive device generally cracks open the choke a predetermined amount when the engine starts. The choke action provides a rich mixture so that sufficient fuel can be vaporized to permit smooth starting and running of the engine.
  • Another object of the invention is to provide an automatic choke construction including a thermostatically controlled bimetal spring normally urging the choke valve closed with decreasing ambient temperature changes and opposed by a suction operated motor device that initially cracks open the choke valve to a predetermined amount permitting running operation during cold weather; engine exhaust manifold heat being directed to the spring coil to warm it; and a first supplemental heat source providing additional heat at all times to the coil spring in the event the exhaust manifold heat flow is low; and, a second supplemental heat source providing further additional heat to the coil at ambient temperatures above a predetermined level to cause the closing force on the choke valve to be removed earlier than would be were the supplemental heat sources not provided; the supplemental heat sources consisting of positive temperature coefficient semi-conductor heater elements whose internal resistances increase with increases in the heater internal temperature and decreases in current flow so as to be selflimited in temperature output thereby eliminating the need for thermostatic circuit breakers to prevent bimetal coil distortion above predetermined temperature levels.
  • FIG. 1 is a cross-sectional elevational view of a portion of a four-barrel carburetor embodying the invention.
  • FIG. 2 is an enlarged view of a portion of the automatic choke shown in FIG. 1; and, 7
  • FIG. 3 is a graph plotting the changes in internal resistance of the heaters of this invention with changes in internal temperature.
  • FIG. 1 is obtained by passing a plane through approximately one-half of a known type of four-barrel, downdraft type carburetor.
  • the portion of the carburetor shown includes an upper air horn section 12, an intermediate main body portion 14, and a throttle valve flange section 16.
  • the three carburetor sections are secured together by a suitable means, not shown, over an intake manifold indicated partially at 18 leading to the engine combustion chambers.
  • Main body portion 14 contains the usual air/fuel mixture induction passages 20 having fresh air intakes at the air horn ends, and connected to manifold 18 at the opposite ends.
  • the passages are each formed with a main venturi section 22 containing a booster venturi 24 suitably mounted for cooperation therewith, by means not shown.
  • Airflow through passages 20 is controlled in part by a choke valve 28 unbalance mounted on a shaft 30 rotatably mounted on side portions of the carburetor air horn, as shown.
  • Flow of fuel and air through each passage 20 is controlled by a conventional throttle valve 36 (only one shown) fixed to a shaft 38 rotatably mounted in flange portion 16.
  • the throttle valves are rotated in a known manner by depression of the vehicle accelerator pedal, and move from an idle speed position essentially blocking flow through passage 20 to a wide open position essentially at right angles to the position shown.
  • the rotative position of choke valve 28 is controlled by a semiautomatically operating choke mechanism 40.
  • the latter includes a hollow housing portion 42 that is formed as an extension of the carburetor throttle flange.
  • the housing is apertured for supporting rotatably one end of a choke lever operating shaft 44, the opposite end being rotatably supported in a casting 46.
  • a bracket or lever portion 48 is fixed on the left end portion of shaft 44 for mounting the end of a rod 52 that is piVoted to choke valve shaft 30. It'will be clear that rotation of shaft 44 in either direction will correspondingly rotate choke valve 28 to open or close the carburetor air intake, as the case may be.
  • An essentially L-shaped thermostatic spring lever 54 has one leg 56 fixedly secured to the opposite or righthand end portion of shaft 44.
  • the other legportion 58 of the lever is secured to the outer end 59 of a coiled bimetallic thermostatic spring element 60 through an arcuate slot 62 in an insulating gasket 64.
  • Leg 56 is also pivotally fixed to the rod 76 of a piston 78.
  • the latter is movably mounted in a bore 79 in housing 42.
  • the under surface of piston 78 is acted upon by vacuum in a passage 80 that is connected to carburetor main induction passages 20 by a port 82 located just slightly below throttle valve 36. Piston 78, therefore, is always subjected to any vacuum existing in the intake manifold passage portion 18.
  • the casing 42 is provided with a hot air passage 68 connected to an exhaust manifold heat stove, for example.
  • the cylinder in which piston 78 slides is provided with bypass slots, not shown, in a known manner so that the vacuum acting on the piston will cause a flow of the hot air from passage 68 to passage 8th. More specifically, hot air will flow into the area around the spring coil 60 through a hole 83 in gasket 64 and out through slot 62 to the bypass slots around piston 78.
  • thermostatic spring element 60 will contract or expand as a function of the changes in ambient temperature conditions of the air entering tube 68; or, if there is no flow, the temperature of the air within chamber 42. Accordingly, changes in ambient temperature will rotate the spring lever 54 to rotate shaft 4-4 and choke valve 28 in one or the other directions as the case may be.
  • a cold weather start of a motor vehicle requires a richer mixture than a warmed engine start because considerably less fuel is vaporized. Therefore, the choke valve is shut or nearly shut to increase the pressure drop thereacross and draw in more fuel. Once the engine does start, however, then the choke valve should be opened slightly to lean the mixture to prevent engine flooding as a result of an excess of fuel.
  • the known choke mechanism described automatically accomplishes the action described. That is, on cold weather starts, the temperature of the air in chamber 42 will be low so that spring element 60 will contract and rotate shaft 44 and choke valve 28 to a closed or nearly closed position, as desired. Upon cranking the engine, vacuum in passage 80 will not be sufficient to move piston 78 to open the choke valve. Accordingly, the engine will be started with a rich mixture. As soon as the engine is running, higher vacuum in passage 80 moves piston 78 downwardly and rotates shaft 44 a slight amount so that choke valve 28 is slightly opened so that less fuel is admitted to induction passage 20.
  • thermostatic spring coil 60 is centrally staked to a metal post 84.
  • the post is formed as an integral part of a thin metal, aluminum, for example, disc 85 that is approximately the diameter of coil 60.
  • the disc constitutes a heat sink or transfer member to evenly radiate heat to the coil from a pair of heater elements 86 and 87 to which it is secured.
  • Heater elements 86 and 87 are positive temperature coefficient (PTC) semiconductors in the shapes of flat ceramic discs fixed on disc 85.
  • the element 86 has a central spring-leg type current carrying contact lug 88 projecting through an insulated cover of choke cap 90.
  • the heat sink disc is grounded through the cover to the cast choke housing by extensions and ground terminals 92.
  • Heater element 87 is connected at all times, to be energized at all times when the vehicle is running, by an interconnection 97 to terminal 96.
  • Heater disc 87 is smaller in size and, therefore, heat output capacity, than heater disc 86, for a purpose to be described. It is a characteristic of each of the PTC heaters that its internal resistance varies directly with the skin temperature of the element, from a predetermined switch point Ts. The change in the internal resistance is not a linear function of the elements internal temperature but varies in the manner shown more clearly in H6. 3.
  • the PTC device provides heat to coil 60 that is supplemental to that provided by the primary exhaust manifold hot air system.
  • the manifold heat flow is so low during cold weather operation due to low airflow in the carburetor that the coil 60 would not be warmed enough by primary manifold heat alone to provide the normal slow progressive heating of the coil 60.
  • the continuous heating of the smaller heater 87 in this case provides the desired compensatory primary heat at all times below its output limit to cause the choke to operate in the desired manner.
  • heater 87 is energized to transfer a small heat output to disc 35 and coil 60, but heater element 86 is not.
  • the bimetal switch contacts 94, 88 remain open, and the PTC heater 86 remains deenergized. Therefore, the choke hot air system supplemented by the small output heater 87 provide the only heat source for choking functions below 65 F.
  • the bimetal coil 60 will unwind, therefore, only as a function of the increased heating by the hot air from passage 68 and heater 87.
  • thermostatic spring means operably connected to the choke valve urging the choke valve towards a closed position with a force increasing as a function of decreases in the temperature of the spring means from a predetermined level
  • first and second self-limiting output temperature heater devices operably associated with the choke f valve to effect opening of the choke valve by varying degrees in response to increases in temperature of the heater devices up to their individual output limits, the first heater device being operable at all times, and control means to render the second heater device operable above a predetermined ambient temperature level.
  • a choke system as in claim 1, the heater devices comprising positive temperature coefficient (PTC)elements characterized by increasing internal impedance with increasing temperatures up to their limits limiting further current flow and heat buildup.
  • PTC positive temperature coefficient
  • An automatic choke system for use with a carburetor having an air/fuel induction passage and an unbalance mounted, air movable, choke valve mounted for variable movement across the passage to control airflow through the passage,
  • thermostatic spring means operably connected to the choke valve urging the choke valve towards a closed position with a force increasing as a function of decreases in the temperature of the spring means from a predetermined level
  • PTC positive temperature coefficient
  • a choke system as in claim 5 including a heat sink secured to the second heater device for uniformly radiating the heat of the second heater device to the spring means.
  • a choke system as in claim 5, the heater devices comprising positive temperature coefficient heater elements characterized by increasing internal impedance with increases in internal temperature up to their limits limiting furthercurrent flow and heat buildup.
  • a two phase automatic choke system for use with a carburetor having an air/fuel induction passage open at one end and adapted to be connected to an engine intake manifold at the other end for subjecting the passage to varying manifold vacuum, the passage having a throttle valve mounted for a variable movement between positions opening and closing the passage to control air/fuel flow through it,
  • the choke system including an unbalance mounted, air movable choke valve mounted anterior of the throttle valve for variable movement across the passage to control airflow towards the throttle valve,
  • thermostatic spring means operably connected to the choke valve urging the choke valve towards a closed position with a force increasing as a function of decreases in the temperature of the spring means from a predetermined level
  • first power means sensitive to engine manifold vacuum for moving the choke valve towards an open position in opposition to the spring means
  • the supplemental means including first and second electrically energized positive temperature coefficient (PTC) heater devices located adjacent the bimetallic spring means and operable to transfer their heat output to the spring means to reduce its choke valve closing force and permit opening of the choke valve by airflow through the passage against it, the first heater device being operable at all times,
  • PTC positive temperature coefficient
  • a two phase automatic choke system for use with an internal combustion engine carburetor having an air/fuel induction passage open at one end and adapted to be connected to an engine intake manifold at the other end for subjecting the passage to varying manifold vacuum, the passage having a throttle valve rotatably mounted across the passage adjacent the lower end for a variable movement between positions opening and closing the passage to control air/fuel flow through it,
  • the choke system including an unbalance mounted
  • thermostatically responsive spring coil operably connected to the choke valve and normally urging the choke valve towards a closed position with a force increasing with decreases in the temperature of the coil from a predetermined level
  • first power means operably connected to the choke valve and sensitive to engine manifold vacuum for moving the choke valve from an initially closed position towards an open position in opposition'to the coil and in response to operation of the engine from a start to a running conditon
  • the first power means including a vacuum operated movable piston means, and a first heat source transferring engine heat to the coil and comprising a hot air containing duct operably connected from the engine exhaust system to the coil for warming the coil to reduce its choke valve closing force, and supplemental second and third electrically controlled, temperature responsive heat meansin a parallel and series flow arrangement, respectively, with the first power means heat source and effecting subsequent movement of the choke valve towards a position more open than the position effected by the first power means alone,
  • the supplemental means including a source of electrical energy, first and second positive temperature coefiicient (PTC) heater device located adjacent the bimetallic spring means and operable to transfer their heat output to the coil to reduce its choke closing force and permit opening of the choke valve by airflow through the passage against it, means connecting the first heater device to the source at all times for concurrent operation with the first power means, and temperature responsive switch means operable above a predetermined ambient air temperature to connect the source to the second heater device to energize the second heater device, the internal resistance of the first and second heater devices above a predetermined heater temperature level increasing to a level restricting further heat buildup beyond a predetermined level.
  • PTC positive temperature coefiicient
  • a choke system as in claim 9 including a heat sink secured to the second PTC device for uniformly radiating the heat of the second PTC device to the coil, the second PTC device being larger than the first device and providing a greater heat output.
  • a choke system as in claim 9, including a housing enclosing the PTC heater devices and coil, an insulating gasket dividing the housing into a first chamber and a second chamber, the first chamber having an inlet and outlet for the hot air duct, the second chamber containing the heater devices and coil and containing an aperture for flow of hot air through the gasket in a path to indirectly heat the coil, the PTC heater devices being located in the housing on the side of the coil opposite to the gasket to receive heat from a direction opposite to that from the gasket.

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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)
  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
US00306776A 1972-11-15 1972-11-15 Multiple heat automatic choke Expired - Lifetime US3752133A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US30677672A 1972-11-15 1972-11-15

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US3752133A true US3752133A (en) 1973-08-14

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US00306776A Expired - Lifetime US3752133A (en) 1972-11-15 1972-11-15 Multiple heat automatic choke

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US (1) US3752133A (ja)
JP (1) JPS525647B2 (ja)
CA (1) CA972240A (ja)
DE (1) DE2339955C2 (ja)
GB (1) GB1419602A (ja)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3831567A (en) * 1973-08-16 1974-08-27 Ford Motor Co Supplemental pulldown mechanism for carburetor automatic choke
US3898422A (en) * 1973-12-26 1975-08-05 Texas Instruments Inc PTC heater assembly bonding
US3898967A (en) * 1973-06-04 1975-08-12 Gte Sylvania Inc Automatic choke assembly
US3905346A (en) * 1974-03-20 1975-09-16 Ford Motor Co Choke cap altitude kit
DE2507615A1 (de) * 1974-03-19 1975-10-02 Sibe Startvorrichtung fuer vergaser
US3947531A (en) * 1974-12-23 1976-03-30 Ford Motor Company Carburetor with controlled fast idle cam
US3972311A (en) * 1974-11-20 1976-08-03 Depetris Peter S Electronic choke control
US4044736A (en) * 1973-07-18 1977-08-30 Toyota Jidosha Kogyo Kabushiki Kaisha Device for controlling a choke valve in a carburetor
US4058097A (en) * 1975-06-30 1977-11-15 Texas Instruments Incorporated Choke control
US4081499A (en) * 1976-06-15 1978-03-28 Honda Giken Kogyo Kabushiki Kaisha Carburetor with electric heating type autochoke device
US4096837A (en) * 1975-12-16 1978-06-27 Honda Giken Kogyo Kabushiki Kaisha Automatic choking device of electric heating type
US4131657A (en) * 1977-03-10 1978-12-26 Gte Sylvania Incorporated Electric automotive choke
US4132211A (en) * 1975-10-24 1979-01-02 Robert Bosch Gmbh Fuel injection system
US4201735A (en) * 1978-09-08 1980-05-06 Fasco Industries, Inc. Method of manufacturing a choke control device
US4237077A (en) * 1978-08-29 1980-12-02 Texas Instruments Incorporated Automatic choke system
US4496496A (en) * 1982-11-01 1985-01-29 Texas Instruments Incorporated Fuel supply system with electric choke and control therefor
US9464588B2 (en) 2013-08-15 2016-10-11 Kohler Co. Systems and methods for electronically controlling fuel-to-air ratio for an internal combustion engine
US10054081B2 (en) 2014-10-17 2018-08-21 Kohler Co. Automatic starting system

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3806854A (en) * 1972-12-05 1974-04-23 Texas Instruments Inc Control for automotive choke
JPS5438166Y2 (ja) * 1975-04-11 1979-11-14
JPS5266116A (en) * 1975-12-01 1977-06-01 Hitachi Ltd Air amount control device in injection carburetor
JPS5294936A (en) * 1976-02-06 1977-08-10 Hitachi Ltd Auto choke carburator
JPS52106028A (en) * 1976-03-03 1977-09-06 Hitachi Ltd Auto choke carbureter
JPS581640Y2 (ja) * 1979-03-19 1983-01-12 マツダ株式会社 エンジンの暖機状態検出装置
JPS55128645A (en) * 1979-03-28 1980-10-04 Fuji Heavy Ind Ltd Electronic control of carburettor in internal combustion engine
JPS576757Y2 (ja) * 1980-04-02 1982-02-08

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR969619A (fr) * 1948-07-17 1950-12-22 Solex Perfectionnements apportés aux commandes automatiques, par thermostat, des dispositifs qui doivent fonctionner en dessous d'une température déterminée, notamment à celles des dispositifs auxiliaires facilitant la mise en marche, à froid, des moteurs à combustion interne
US4083336A (en) * 1971-08-10 1978-04-11 Texas Instruments Incorporated Condition responsive control device

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898967A (en) * 1973-06-04 1975-08-12 Gte Sylvania Inc Automatic choke assembly
US4044736A (en) * 1973-07-18 1977-08-30 Toyota Jidosha Kogyo Kabushiki Kaisha Device for controlling a choke valve in a carburetor
US3831567A (en) * 1973-08-16 1974-08-27 Ford Motor Co Supplemental pulldown mechanism for carburetor automatic choke
US3898422A (en) * 1973-12-26 1975-08-05 Texas Instruments Inc PTC heater assembly bonding
DE2507615A1 (de) * 1974-03-19 1975-10-02 Sibe Startvorrichtung fuer vergaser
US4038955A (en) * 1974-03-19 1977-08-02 Societe Industrielle De Brevets Et D'etudes S.I.B.E. Automatic choke systems for carburetors
US3905346A (en) * 1974-03-20 1975-09-16 Ford Motor Co Choke cap altitude kit
US3972311A (en) * 1974-11-20 1976-08-03 Depetris Peter S Electronic choke control
US3947531A (en) * 1974-12-23 1976-03-30 Ford Motor Company Carburetor with controlled fast idle cam
US4058097A (en) * 1975-06-30 1977-11-15 Texas Instruments Incorporated Choke control
US4132211A (en) * 1975-10-24 1979-01-02 Robert Bosch Gmbh Fuel injection system
US4096837A (en) * 1975-12-16 1978-06-27 Honda Giken Kogyo Kabushiki Kaisha Automatic choking device of electric heating type
US4081499A (en) * 1976-06-15 1978-03-28 Honda Giken Kogyo Kabushiki Kaisha Carburetor with electric heating type autochoke device
US4131657A (en) * 1977-03-10 1978-12-26 Gte Sylvania Incorporated Electric automotive choke
US4237077A (en) * 1978-08-29 1980-12-02 Texas Instruments Incorporated Automatic choke system
US4201735A (en) * 1978-09-08 1980-05-06 Fasco Industries, Inc. Method of manufacturing a choke control device
US4496496A (en) * 1982-11-01 1985-01-29 Texas Instruments Incorporated Fuel supply system with electric choke and control therefor
US9464588B2 (en) 2013-08-15 2016-10-11 Kohler Co. Systems and methods for electronically controlling fuel-to-air ratio for an internal combustion engine
US10240543B2 (en) 2013-08-15 2019-03-26 Kohler Co. Integrated ignition and electronic auto-choke module for an internal combustion engine
US10794313B2 (en) 2013-08-15 2020-10-06 Kohler Co. Integrated ignition and electronic auto-choke module for an internal combustion engine
US10054081B2 (en) 2014-10-17 2018-08-21 Kohler Co. Automatic starting system

Also Published As

Publication number Publication date
JPS525647B2 (ja) 1977-02-15
DE2339955A1 (de) 1974-05-22
GB1419602A (en) 1975-12-31
DE2339955C2 (de) 1985-02-21
JPS4980427A (ja) 1974-08-02
CA972240A (en) 1975-08-05

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