EP0255952A2 - Système de commande du carburant à bas régime pour carburateurs - Google Patents

Système de commande du carburant à bas régime pour carburateurs Download PDF

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Publication number
EP0255952A2
EP0255952A2 EP87111377A EP87111377A EP0255952A2 EP 0255952 A2 EP0255952 A2 EP 0255952A2 EP 87111377 A EP87111377 A EP 87111377A EP 87111377 A EP87111377 A EP 87111377A EP 0255952 A2 EP0255952 A2 EP 0255952A2
Authority
EP
European Patent Office
Prior art keywords
fuel
low
passageway
flow rate
speed
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.)
Withdrawn
Application number
EP87111377A
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German (de)
English (en)
Other versions
EP0255952A3 (fr
Inventor
Tetsuo Muraji
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.)
Mikuni Corp
Original Assignee
Mikuni Corp
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 Mikuni Corp filed Critical Mikuni Corp
Publication of EP0255952A2 publication Critical patent/EP0255952A2/fr
Publication of EP0255952A3 publication Critical patent/EP0255952A3/fr
Withdrawn legal-status Critical Current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
    • F02M3/00—Idling devices for carburettors
    • F02M3/08—Other details of idling devices
    • F02M3/09—Valves responsive to engine conditions, e.g. manifold vacuum
    • 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
    • F02M3/00—Idling devices for carburettors
    • F02M3/08—Other details of idling devices
    • F02M3/12—Passageway systems

Definitions

  • the present invention relates to a carburetor and more particularly to a low-speed fuel control system for carburetors which is provided with a low-speed system venturi to enable an air to fuel ratio of mixture in a low-speed region to be controlled into an optimum condition.
  • the low­speed system comprising a slow port 33, a slow jet 31 and a slow air jet 36 is generally known.
  • the amount of fuel coming out of the slow port 33 is controlled by varying the opening area of the slow port 33 opening at the downstream side of a throttle valve 35 in accordance with the opening degree of the throttle valve and thereby the measurement of a flow rate of fuel is performed.
  • many tenta­tive steps are required.
  • the opening degree of the throttle valve 35 is not exactly proportion­al to a flow rate of air passing through a venturi 34 and it is therefore difficult to control the fuel flow rate through the throttle valve 35.
  • a primary object of the present invention to provide a low-speed fuel control system for carburetors in which the diameter and setting position of a slow port can simply be selected and durability of which is excellent.
  • This object can be attained, according to the present invention, in such a way that a low-speed system venturi capable of generating a vacuum corresponding to a flow rate of air is provided in an intake bore, a sensor for detecting the height of a fuel column existing in a passageway connecting the venturi portion to a slow jet is disposed, and a fuel flow rate control device provided between a slow jet and a slow port is actuated in accordance with an output signal delivered from the sensor.
  • the fuel flow rate control device controls the fuel flow rate so that the height of the fuel column follows exactly the variation of the vacuum occurring in the low-speed venturi portion correctly representative of the air flow rate in the intake bore through the output signal generated by a level sensor which has detected whether or not the level of the fuel column is higher than a preset level, the mixture with a proper air-fuel ratio can always be supplied in the low-speed region even if the air flow rate is varied.
  • FIGs. 2 to 9 show a first embodiment of the low-­speed fuel control system according to the present invention.
  • reference numeral 1 represents an intake passageway of the carburetor; 2 an air valve capable of opening and closing the intake passageway 1; 3 an operation controlling device of the air valve 2 provided with a diaphragm 3a connected to the air valve 2, a spring 3b and a vacuum chamber 3c communicating with the downstream side of the air valve 2; 4 a fixed venturi; 5 a throttle valve; 6 a main nozzle opening in to the fixed venturi 4; 7 a main air jet; 8 a main jet; 9 a low-speed system venturi formed in a bypass through which the upstream side of the air valve 2 is connected to the downstream side thereof on the downstream side of the fixed venturi 4; 10 a passageway connecting the low-speed system venturi 9 and the downstream side of the main jet 8 through a slow jet 11; 12 a level detector comprising a light-emitting device 12a and a light-receiving device 12b
  • 13 a slow port opening into a vacuum generating section which is formed by the outer peripheral edge of the throttle valve 5 and the inner circumferential surface of the intake passageway 1; 14 a solenoid valve disposed in a fuel passageway 15 in position and capable of opening and closing the passageway 15 in accordance with the variation of an input voltage; 16 a control circuit for controlling the input voltage to the solenoid valve 14; and 17 a float chamber.
  • the arrangement is such that the operation controlling device 3 holds the air valve 2 at a closing position through the diaphragm 3a pressed by the spring 3b when an engine is stopped and, after the engine is started, it displaces the diaphragm 3b against the resilience of the spring 3a by virtue of a vacuum or negative pressure produced at the downstream side of the air valve 2 in at least its low speed region and enables the air valve 2 to open.
  • level detector 12 is adapted to detect whether or not the pressure head of the fuel column in the passageway 10 is higher than the preset head to be able to supply outputs O h , O l (see Figs. 3 and 4) corresponding thereto. Further, as shown in, for example, Fig.
  • the control circuit 16 includes a comparator C which enables a reference voltage V R to be imputted to a negative terminal and which enables the output from the level detector 12 to be inputted to a positive terminal, and a transistor T connected to the output side of the comparator C and is made up so that the opening degree of the solenoid valve 14 can be controlled into two steps (which will be hereinafter referred to as steps A and B) corresponding to the outputs O h , O l supplied from the level detector 12.
  • the air valve 2 closes the intake bore 1 at the start of the engine or in the low-speed region of the engine and suction air is introduced from the downstream side of the fixed venturi 4 through the low-speed system venturi 9 to the manifold.
  • the negative pressure in the fixed venturi 4 is not increased enough to cause the fuel to be jetted from the main nozzle 6 and, on the other hand, the negative pressure in the low-speed system venturi 9 is raised in proportion to the square of the flow rate of air passing through the venturi 9.
  • the negative pressure generated on the downstream of the slow jet 11 is proportional to the square of the flow rate of the fuel flowing through the passageway 15, it follows that if the magnitude of this negative pressure is made to coincide with that in the low-speed system venturi 9, a proper amount of fuel according to the flow rate of the air flowing through the venturi 9 can be supplied into the intake bore 1.
  • the height of the fuel column 10a exceeds the preset value, the light travelling from the light-emitting device 12a to the light-receiving device 12b traverses the fuel column and as a result, due to the presence of the fuel or a float in the fuel column 10a, the amount of the light reaching the light-receiving device 12b from the light-emitting device 12a will be decreased. Accordingly, the output delivered from the level detector 12 will become a high level O h (see Fig. 4). The output O h is transmitted through the control circuit 16 to the solenoid valve 14 as a driving signal and thereby the opening degree of the valve 14 is switched over to the step A of a larger opening degree.
  • the fuel flow rate is increased and the fuel pressure on the downstream side of the slow jet 11 is reduced to lower the level of the fuel column 10a.
  • Such raising and lowering of the fuel column 10 are repeated alternately and thereby the level of the fuel column 10a is substantially always held at the preset level to thus maintain the balance between the vacuum generated in the low-speed system venturi 9 and the fuel pressure in the downstream side of the slow jet 11.
  • the amount of the fuel coming out of the slow port 13 follows exactly with respect to the vacuum produced in the low-­speed system venturi 9 fully representative of the flow rate of intake air, so that the mixture with the air to fuel ratio which is always proper over the entire low-­ speed region is supplied to the engine.
  • the relationship between the flow rate of the air flowing through the suction bore 1 and the flow rate of the fuel fed into the suction bore 1 is directly controlled, thereby determining the air to fuel ratio of the mixture supplied to the engine.
  • This fact therefore, eliminates delicate settings necessary for the determination of, for example, the diameter and position of the slow port 13 and makes it possible to control automatically the air flow rate and the fuel flow rate. Hence the steps of such settings can materially be reduced.
  • the light-emitting device 12a and the light-­receiving device 12b of the level detector 12 in the above embodiment may be disposed in such a manner as to project into the passageway 10 at the predetermined height thereof as shown in Fig. 6 and may be arranged, as indicated in Fig. 8, in such a manner as to be incorporated in the passageway 10 at the predetermined height thereof to detect then the fuel level by providing a float 10b formed of an opaque material in the fuel column 10a.
  • the outputs generated from the level detector 12 deliver the signals to the control circuit 16 in accordance with the fuel level as indicated in Figs. 7 and 9, respectively, and consequently the same function as in the above embodiment can be brought about.
  • Fig. 10 shows a second embodiment of the present invention, which is an example that the low-speed fuel control system of the present invention is applied to a primary bore side P of a compound type carburetor.
  • reference numeral 21 denotes a venturi, 22 a throttle valve, 23 a passageway for connecting a slow jet 24 with a venturi 21, 25 a level detector disposed in the passageway 23 and having the same structure as in the first embodiment, 26 a slow port communicating with the slow jet 24 through a passageway 27 and opening into the intake bore of the primary side P, and 28 a solenoid valve disposed in position along the passageway 27 and having the same structure as in the first embodiment.
  • a secondary bore side S comprises a venturi 29, a throttle valve 30, a main nozzle 31, a main air jet 32, a main jet 33, a slow jet 34, and a slow air jet 35, and the throttle valve 30 is set so that the intake bore of the secondary side S is closed, in the low-speed region, through a control device 36 actuated by the vacuums in the venturi 21 and the venturi 29.
  • the suction air is supplied from the primary side P in the low-speed region of the engine, while the level detector 25, the solenoid valve 28 and the like are operated as is the case with the first embodiment. That is, the flow rate of the fuel discharged from the slow port 26 is controlled so that the ratio of the fuel pressure in the downstream side of the slow jet 24 to the negative pressure generated in the venturi 21 properly representative of the flowrate of the air passing through the venturi 21 is consistently maintained to be a constant value, and therefore the mixture with the air to fuel ratio which is always constant is supplied to the manifold over varying air flow rates.
  • the solenoid valves 14, 28 in respective embodiments mentioned above may be duty-controlled by an input pulse or may be adapted to open and close the fuel passageways 15, 27, respectively, by the variation of an input voltage.
  • the level detectors 12, 25 can be replaced by known level indicators for which a float provided with an electric contacts or optical fibers and supersonic are utilized and in any of these cases, the same effect as in the above embodiments is achieved.

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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)
EP87111377A 1986-08-07 1987-08-06 Système de commande du carburant à bas régime pour carburateurs Withdrawn EP0255952A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP121596/86 1986-08-07
JP12159686 1986-08-07

Publications (2)

Publication Number Publication Date
EP0255952A2 true EP0255952A2 (fr) 1988-02-17
EP0255952A3 EP0255952A3 (fr) 1988-08-10

Family

ID=14815168

Family Applications (1)

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EP87111377A Withdrawn EP0255952A3 (fr) 1986-08-07 1987-08-06 Système de commande du carburant à bas régime pour carburateurs

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4201166A (en) * 1977-10-20 1980-05-06 Hitachi, Ltd. Air to fuel ratio control system for internal combustion engine
DE2910605A1 (de) * 1979-03-17 1980-09-25 Pierburg Gmbh & Co Kg Vergaser fuer verbrennungsmotoren
JPS5647649A (en) * 1979-09-21 1981-04-30 Aisan Ind Co Ltd Air-fuel mixture feeding apparatus for internal combustion engine
JPS57124062A (en) * 1981-01-26 1982-08-02 Aisan Ind Co Ltd Electronic control type carburetter
JPS6043160A (ja) * 1983-08-19 1985-03-07 Aisan Ind Co Ltd 可変ベンチユリ気化器における燃料流量制御装置
EP0207796A2 (fr) * 1985-07-05 1987-01-07 Mikuni Kogyo Kabushiki Kaisha Système réglé de carburant pour dispositifs d'alimentation de mélange d'air-carburant

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4201166A (en) * 1977-10-20 1980-05-06 Hitachi, Ltd. Air to fuel ratio control system for internal combustion engine
DE2910605A1 (de) * 1979-03-17 1980-09-25 Pierburg Gmbh & Co Kg Vergaser fuer verbrennungsmotoren
JPS5647649A (en) * 1979-09-21 1981-04-30 Aisan Ind Co Ltd Air-fuel mixture feeding apparatus for internal combustion engine
JPS57124062A (en) * 1981-01-26 1982-08-02 Aisan Ind Co Ltd Electronic control type carburetter
JPS6043160A (ja) * 1983-08-19 1985-03-07 Aisan Ind Co Ltd 可変ベンチユリ気化器における燃料流量制御装置
EP0207796A2 (fr) * 1985-07-05 1987-01-07 Mikuni Kogyo Kabushiki Kaisha Système réglé de carburant pour dispositifs d'alimentation de mélange d'air-carburant

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 5, no. 105, 8th July 1981; & JP-A-56 047 649 (AISAN KOGYO) 30-04-1981 *
PATENT ABSTRACTS OF JAPAN, vol. 6, no. 220, 5th November 1982; & JP-A-57 124 062 (AISAN KOGYO) 02-08-1982 *
PATENT ABSTRACTS OF JAPAN, vol. 9, no. 172, 17th July 1985; & JP-A-60 043 160 (AISAN KOGYO) 07-03-1985 *

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Publication number Publication date
EP0255952A3 (fr) 1988-08-10

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