US3925521A - Variable Venturi type carburetor - Google Patents

Variable Venturi type carburetor Download PDF

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Publication number
US3925521A
US3925521A US470277A US47027774A US3925521A US 3925521 A US3925521 A US 3925521A US 470277 A US470277 A US 470277A US 47027774 A US47027774 A US 47027774A US 3925521 A US3925521 A US 3925521A
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United States
Prior art keywords
air
orifice
type carburetor
bellows
venturi type
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
US470277A
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English (en)
Inventor
Tadahiko Otani
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Hitachi Ltd
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Hitachi Ltd
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Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
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Publication of US3925521A publication Critical patent/US3925521A/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
    • F02M7/00—Carburettors with means for influencing, e.g. enriching or keeping constant, fuel/air ratio of charge under varying conditions
    • F02M7/23—Fuel aerating devices
    • F02M7/24—Controlling flow of aerating air
    • F02M7/28—Controlling flow of aerating air dependent on temperature or pressure
    • 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

  • said air I chamber being connected to an air passage which is in communication with both the interior of an air cleaner [30] Foreign Application Priority Data and atmosphere for introducing a compensating air May 18, 1973 Japan 48-54567 into the air chamber-
  • the afomsaid air Passage air metering means consisting of an orifice and a nee- [52] US. Cl. 261/39 A; 261/44 R; 261/12] B dle.
  • the needle is connected to a bellows which is ex- [5 1] Int. Cl.
  • FOZM 9/06 pansible in response to the atmospheric density so that [58] Fi ld f S h u 261/39 A, 44 R, 12 B the needle can control, in co-operation with the associated orifice, the quantity of compensating air to be ⁇ 56] References Cit d fed into the air chamber in response to the atmo- UNITED STATES PATENTS spheric density for obtaining a desirable air/fuel ratio.
  • This invention relates to a variable Venturi type (or air valve type) carburetor for use in an internal combustion engine and, more particularly, to a carburetor provided with a compensating mechanism which is operable depending on the atmospheric density.
  • This carburetor comprises a carburetor main body having an induction passage formed therein, a piston reciprocably arranged to project into said induction passage for forming a Venturi section, means responsive to the pressure present in said Venturi section to displace said piston for maintaining the pressure in the Venturi section at a substantially constant level, fuel metering means consisting of an orifice fixed in the carburetor main body and a needle attached to said piston, and means for supplying fuel into said fuel metering means.
  • the piston is displaced in response to the quantity of intake air into the engine cylinder and hence the needle comprised in the fuel metering means is displaced with respect to the orifice to thereby change the opening area of the orifice for controlling the quantity of supply fuel.
  • an air/fuel mixture having a substantially constant air/fuel ratio can be obtained by controlling the position of the piston and hence the opening area defined between the orifice and needle depending on the quantity of intake air into the engine cylinder.
  • variable Venturi type carburetor In use of such a variable Venturi type carburetor, if it is initially adjusted so as to obtain an air/fuel ratio which is most suitable for purifying the exhaust harmful ingredients in a level ground driving, then a difficulty will be encountered in a high land driving due to a reduced air density. Because, in a high altitude, the quantity of air flowing into the engine cylinder will be reduced even when the pressure in the Venturi section remains unchanged, and accordingly the air/fuel mixture fed into the engine cylinder will become lean (or the mixture will contain a richer fuel). This will cause the exhaust gas purifying device to fail to maintain desired performance.
  • the fuel metering means is provided with an air chamber so arranged between the Venturi section and orifice that the air chamber is in communication with said Venturi section through a second orifice and an air cleaner through means for supplying a quantity of air depending on the altitude.
  • FIG. I is a schematic view of a prior art variable Venturi type carburetor equipped with an air density compensating device of a type which introduces an air density compensating air from the air cleaner;
  • FIG. 2 is a schematic view of the main portion of another prior art air density compensating device of the type which introduces an air density compensating air from atmosphere;
  • FIG. 3 is a schematic view of the variable Venturi type carburetor according to one embodiment of this invention.
  • FIG. 4 is a schematic view of the main portion of the air density compensating device for use in the variable Venturi type carburetor according to another embodiment of this invention.
  • Indicated at l is a carburetor main body provided with a throttle valve 3 for controlling the air/fuel mixture flowing through an induction passage 2.
  • a suction piston 5 is slidably and air-tightly received in a suction chamber in contact with the suction chamber wall 4.
  • the suction piston 5 has a suction hole 7 formed therein for introducing into the suction chamber 8 a negative pressure developed by the intake air flowing through a Venturi section 6.
  • An atmospheric pressure acts on the underside of a suction piston disc 9 through an air introducing port 12.
  • the suction piston 5 slides up and down to a position where the product of the negative pressure within the suction chamber 8 and the pressure receiving area of the suction piston 5 balances with the sum of the weight of suction piston 5 and a force applied by a suction piston spring 13.
  • the suction piston 5 is normally displaced so that the negative pressure in the Venturi section 6 is kept substantially constant.
  • To the bottom end of the suction piston S is fixed a tapered jet needle 10 so that it extends into an orifice 17 formed in the carburetor main body 1.
  • the jet needle 10 moves up and down through the orifice 17 to thereby change the opening area or fuel flowing area of the orifice 17 for metering the flow quantity of the fuel, which is supplied from a float chamber 14 into the orifice 17 via a fuel passage 15.
  • an air chamber 16 which is in communication with the Venturi section 6 via an orifice 11.
  • the air chamber 16 is also in communication with an air cleaner 19 via air passages 18 and 18A.
  • air metering means consisting of a tapered valve body 21 and a neck portion 22.
  • Said valve body 21 is connected to a bellows 20 which is positioned in a chamber 30 and expansible in response to the pressure in the chamber 30.
  • the chamber 30 is fluidically connected to the interior of the air cleaner 19 so that the pressure in the chamber 30 is substantially identical with the atmospheric pressure. Therefore, the bellows 20 is expanded or compressed in response to the atmospheric pressure.
  • the valve body 21 is so contoured that when the bellows 20 is expanded in response to the reduction in the aunospheric pressure, the opening area defined between the valve body 21 and neck portion 22 increases.
  • the bellows 20 is expanded in response to the reduction in the atmospheric pressure to thereby increase the air passing area .at the neck portion 22, so that an increased amount of air is allowed to flow from the air cleaner section into the air chamber 16 of the fuel metering section.
  • the quantity of fuel fed into the Venturi section 6 is reduced, permitting to compensate the reduced air proportion in the air/fuel mixture which might otherwise be caused due to reduction in the air density at a high altitude.
  • the air supply quantity into the air chamber 16 is controlled mainly depending on the opening area of the neck portion 22 and, therefore, the configuration of valve body 21 and the expansible range of bellows 20 are selected so that an optimum opening area can be obtained depending on the atmospheric pressure.
  • an air passage 18B communicating with the air metering means is directly communicated with atmosphere by way of a filter 24 as shown in FIG. 2.
  • Another object of this invention is to provide a carburetor which is operative to compensate for the variation in air/fuel ratio due to the variation in air density, for maintaining a desirable air/fuel ratio.
  • Still another object of this invention is to provide a carburetor which is operative to compensate for the variation in air/fuel ratio due to the variation in temperature, for maintaining a desirable air/fuel ratio.
  • variable Venturi type carburetor of this invention is characterized in that the fuel metering device consisting of an first orifice and a needle is provided with an air chamber which is located between the Venturi section and the first orifice and in communication with the Venturi section via a second orifice, and the pressure within said air chamber is varied by varying the quantity of compensating air fed into the air chamber, for compensating the discharge quantity of fuel.
  • the air chamber is in communication with the air cleaner and atmosphere by way of an air metering means, for introducing the compensating air both from atmosphere and from air cleaner into said air chamber.
  • the air passages communicating the air metering means with the air cleaner and atmosphere are respectively provided with a flow controlling means adapted to control the proportion of compensating air from atmosphere and air cleaner. In this manner, a proper amount of compensating air can be introduced into the air chamber both from atmosphere and from air cleaner over the entire engine operation range covering from low to high speed operation range.
  • the air metering means is connected to bellows expansible depending on the atmospheric pressure for varying the opening area depending on the atmospheric pressure.
  • the bellows may be either evacuated or filled with a gas. In the latter case, the bellows may be expansible in response not only to the atmospheric pressure but also to the atmospheric temperature. ln other words, the bellows filled with a gas is responsive to the variation of air density due to the variation in both atmospheric pressure and temperature, thereby allowing to compensate the variation in air/fuel ratio caused by the variation in air density.
  • the bellows of the type When suitably held by suitable means which is operative in response to the temperature, the bellows of the type is responsive only to the variation in temperature to vary the quantity of compensating air into the air chamber, thereby allowing to compensate the variation in air/fuel ratio caused by the variation in temperature.
  • the carburetor is provided with a passage 25 communicating with the air cleaner and another passage 26 communicatin g with atmosphere by way of a filter 24. Both of these passages 25 and 26 are air passages communicating with a chamber 30 in which a bellows 20 is received.
  • the compensating air is therfore supplied into the air chamber 16 from the air cleaner 19 through the passage 25 and also from atomsphere through the passage 26.
  • the passages 25 and 26 have neck portions 27 and 28, respectively, which are so selected as to provide a preselected air passing ratio therebetween to thereby predetermine the ratio of the air quantities passing through these passages 27 and 28.
  • the bellows when an automobile is driven on a high land, the bellows will be expanded in response to the variation in atmospheric pressure to thereby widen the air metering area defined between the valve body 21 and neck portion 22 for introducing the air-density compensating air from the air cleaner l9 and atmosphere.
  • the neck portion 27 in the passage 25 is selected so as to give a wider cross section that the neck portion 28 in the passage 26, then a smaller quantity of compensating air than that required will be supplied in the high speed operation range; on the other hand, if the neck portion 28 is selected so as to give a wider cross section than the neck portion 27, then a larger quantity of compensating air than that required will be supplied in the high speed operation range.
  • the neck portion 28 has a wider cross section than the neck portion 27, the air passing through the narrowed portion 27 is small in quantity and an excessive quantity of compensating air is supplied from atmosphere via the neck portion 28 in the high speed operation range, so that the total quantity of air supplied into the air chamber 16 will be increased in the high speed operation range.
  • any desired quantity of compensating air can be supplied into the air chamber 16 in the high speed operation range. So long as the neck portions 27 and 28 are so selected as to give sufficiently larger cross sections than the fuel metering area defined between the jet needle and nozzle 1 1, no difficulty will be encountered in compensation in the low and medium speed operation ranges because the pressure drop within the air cleaner 19 due to its resistance can be neglected in such operation ranges. Similar effects may conveniently be attained by use of the air passing resistance of the passages 25 and 26 instead of provision of narrowed portions 27 and 28.
  • the present invention provides a constant compensation in a wide operation range covering from low to high speed operation range.
  • the bellows 20 may have a danger of being damaged easily or entail a varied compensation characteristic because of the engine oscillation. To eliminate this danger the bellows 20 may be separated from the carburetor and mounted as a single unit together with the chamber 30, orifice 21 and neck portion 22 on the car body at any suitable position free from oscillation. The attachment of the filter 24 integrally to said unit will also be preferred for making the entire construction compact.
  • the bellows 20 may be either evacuated or filled with any suitable gas.
  • a vacuum bellows will provide the aforesaid actions by expanding and contracting in response only to the pressure within the chamber 30 (this pressure is almost equal to the atmospheric pressure).
  • the atmospheric density varies not only with the atmospheric pressure but also with the atmospheric temperature. This necessitates the compensation also with respect to the variation of air density due to the temperature change.
  • a temperature sensitive substance such as alcohol is filled into the bellows 20
  • the bellows 20 will be expanded and contracted depending on the temperature change even when the atmospheric pressure remains unchanged, thereby allowing to compensate the variation in air density due to the variation in atmospheric temperature.
  • FlG. 4 illustrates another embodiment of this invention, wherein a container 31 is fixed to the bottom of the chamber 30.
  • the container 31 is filled with a temperature sensitive substance 29 such as wax and slidably receiving therein a piston 32 which holds the bellows 20.
  • the temperature sensitive substance 29 expands in response to the temperature and displace the valve body 21 together with the bellows 20 to thereby control the compensating air fed into the air chamber.
  • the quantity of compensating air can be controlled irrespective of the variation in air density, and therefore the fluctuation of the air/fuel ratio may be compensated for, which might otherwise be caused when the fuel discharge quantity varies upon variation in the viscous resistance of the fuel depending on the temperature.
  • a variable Venturi type carburetor which consists of a carburetor main body having an induction passage extending through it and connected to an air cleaner, a piston movably arranged so as to project into said induction passage for thereby forming a Venturi section, means responsive to the pressure in said Venturi section to move the piston for thereby maintaining the pressure in the Venturi section at a substantially constant level, fuel metering means consisting of an orifice integrally formed in the carburetor main body and a needle mounted to said piston, and means for supplying the fuel into said fuel metering means, characterized by a small chamber arranged between said orifice and Venturi section so as to be in communication with said Venturi section through a second orifice; air metering means in communication with said small chamber; a first air passage communicating said air metering means with said air cleaner; a second air passage communicating said air metering means with atmosphere, atmospheric density sensitive means responsive to the atmospheric density to operate said air metering means; and wherein said first and second air passage
  • variable Venturi type carburetor according to claim 1, wherein said means for controlling the air passing resistance are neck portions.
  • a variable Venturi type carburetor wherein said air metering means consists of an orifice and needle, and said atmospheric density means is a bellows having one end fixed and the opposite end connected to said needle.
  • a variable Venturi type carburetor wherein said bellows is received in a second chamber which is in communication with both said air metering means and first and second air passages.
  • a variable Venturi type carburetor according to claim 4 wherein said bellows in filled with a gas.
  • variable Venturi type carburetor according to claim 1, wherein said air metering means and atmospheric density sensitive means are separated from the 8 claim 8, wherein said temperature sensitive means consists of a container filled with wax which is expansible in response to the temperature and a piston slidably received in said container.

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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)
US470277A 1973-05-18 1974-05-15 Variable Venturi type carburetor Expired - Lifetime US3925521A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP48054567A JPS5142269B2 (nl) 1973-05-18 1973-05-18

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CA (1) CA997970A (nl)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4060064A (en) * 1975-03-20 1977-11-29 Nissan Motor Company, Limited Variable size venturi carburetor with an electronic air/fuel ratio control system
DE2643113A1 (de) * 1976-06-09 1978-03-16 Toyota Motor Co Ltd Einrichtung zum steuern des luft- kraftstoffverhaeltnisses in einem mit einem vergaser ausgestatteten verbrennungsmotor zugefuehrten gemisch
US4292258A (en) * 1979-01-26 1981-09-29 Hitachi, Ltd. Altitude compensating device for carburetors
US4320731A (en) * 1980-01-04 1982-03-23 Ford Motor Company Carburetor air bleed control system
US4472321A (en) * 1981-11-06 1984-09-18 Toyota Jidosha Kabushiki Kaisha Altitude compensation apparatus for carburetor
US4472326A (en) * 1981-12-21 1984-09-18 Toyota Jidosha Kabushiki Kaisha Variable venturi-type carburetor
US4627401A (en) * 1983-10-13 1986-12-09 Atlas Fahrzeugtechnik Gmbh High-velocity carburetor for an Otto engine
EP0728935A1 (en) * 1995-02-21 1996-08-28 Tk Carburetor Co., Ltd. Carburetor having metering valve with improved air-fuel ratio adjusting performance
US20070246846A1 (en) * 2006-04-25 2007-10-25 Honda Motor Co., Ltd. Carburetor equipped with needle jet

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5416998Y2 (nl) * 1975-11-18 1979-07-02
JPS5437445U (nl) * 1977-08-17 1979-03-12
US4146810A (en) * 1977-12-29 1979-03-27 International Business Machines Corporation Radiation heated acceleration
JPS555701U (nl) * 1978-06-29 1980-01-16
JPS5776460U (nl) * 1980-10-28 1982-05-12

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1636480A (en) * 1918-07-10 1927-07-19 Stromberg Motor Devices Co Mixture control for airplane carburetors
US1802321A (en) * 1923-12-31 1931-04-21 Marvel Carbureter Co Carburetor
US2387676A (en) * 1943-03-17 1945-10-23 Tillotson Mfg Co Carburetor
US3493217A (en) * 1966-12-16 1970-02-03 John Dashwood Farley Carburettors
US3764120A (en) * 1970-10-09 1973-10-09 Honda Motor Co Ltd Air bleed adjusting device for the carburetor of an internal combustion engine
US3831910A (en) * 1971-12-16 1974-08-27 Zenith Carburetter Co Ltd Carburetors
US3836128A (en) * 1972-11-03 1974-09-17 Ford Motor Co Carburetor ambient mixture control

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1636480A (en) * 1918-07-10 1927-07-19 Stromberg Motor Devices Co Mixture control for airplane carburetors
US1802321A (en) * 1923-12-31 1931-04-21 Marvel Carbureter Co Carburetor
US2387676A (en) * 1943-03-17 1945-10-23 Tillotson Mfg Co Carburetor
US3493217A (en) * 1966-12-16 1970-02-03 John Dashwood Farley Carburettors
US3764120A (en) * 1970-10-09 1973-10-09 Honda Motor Co Ltd Air bleed adjusting device for the carburetor of an internal combustion engine
US3831910A (en) * 1971-12-16 1974-08-27 Zenith Carburetter Co Ltd Carburetors
US3836128A (en) * 1972-11-03 1974-09-17 Ford Motor Co Carburetor ambient mixture control

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4060064A (en) * 1975-03-20 1977-11-29 Nissan Motor Company, Limited Variable size venturi carburetor with an electronic air/fuel ratio control system
DE2643113A1 (de) * 1976-06-09 1978-03-16 Toyota Motor Co Ltd Einrichtung zum steuern des luft- kraftstoffverhaeltnisses in einem mit einem vergaser ausgestatteten verbrennungsmotor zugefuehrten gemisch
US4144855A (en) * 1976-06-09 1979-03-20 Toyota Jidosha Kogyo Kabushiki Kaisha Device for controlling the air-fuel ratio of a mixture
US4292258A (en) * 1979-01-26 1981-09-29 Hitachi, Ltd. Altitude compensating device for carburetors
US4320731A (en) * 1980-01-04 1982-03-23 Ford Motor Company Carburetor air bleed control system
US4472321A (en) * 1981-11-06 1984-09-18 Toyota Jidosha Kabushiki Kaisha Altitude compensation apparatus for carburetor
US4472326A (en) * 1981-12-21 1984-09-18 Toyota Jidosha Kabushiki Kaisha Variable venturi-type carburetor
US4627401A (en) * 1983-10-13 1986-12-09 Atlas Fahrzeugtechnik Gmbh High-velocity carburetor for an Otto engine
EP0728935A1 (en) * 1995-02-21 1996-08-28 Tk Carburetor Co., Ltd. Carburetor having metering valve with improved air-fuel ratio adjusting performance
US20070246846A1 (en) * 2006-04-25 2007-10-25 Honda Motor Co., Ltd. Carburetor equipped with needle jet
US7637483B2 (en) * 2006-04-25 2009-12-29 Honda Motor Co., Ltd. Carburetor equipped with needle jet

Also Published As

Publication number Publication date
JPS5142269B2 (nl) 1976-11-15
JPS504429A (nl) 1975-01-17
CA997970A (en) 1976-10-05

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