US3533386A - Apparatus for reducing hydrocarbon content of engine exhaust gases during deceleration of automobile - Google Patents

Apparatus for reducing hydrocarbon content of engine exhaust gases during deceleration of automobile Download PDF

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Publication number
US3533386A
US3533386A US781533A US3533386DA US3533386A US 3533386 A US3533386 A US 3533386A US 781533 A US781533 A US 781533A US 3533386D A US3533386D A US 3533386DA US 3533386 A US3533386 A US 3533386A
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United States
Prior art keywords
air
automobile
engine
deceleration
mixture
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Expired - Lifetime
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US781533A
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English (en)
Inventor
Kenji Masaki
Sinzo Kato
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Nissan Motor Co Ltd
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Nissan Motor Co Ltd
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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
    • F02M3/00—Idling devices for carburettors
    • F02M3/08—Other details of idling devices
    • F02M3/09—Valves responsive to engine conditions, e.g. manifold vacuum
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S261/00—Gas and liquid contact apparatus
    • Y10S261/19—Degassers

Definitions

  • the present invention relates to system for reducing the hydrocarbon content of exhaust gases of an automotive gasoline-powered engine. and more particularly to a system for controlling both the air-fuel ratio of an air-fuel mixture to be drawn into the engine by way of the slow running mixture supplyflow path of a carburetor and the level of intake manifold vacuum while in the deceleration of the automobile.
  • Automobile operation is usually divided into four different driving conditions; idle, acceleration. normal cruising, and deceleration.
  • the ranges of hydrocarbon contents of engine exhaust gases vary markedly according to the mode of automobile operation, and experiments thus far conducted on various engine exhaust gases emitted under different modes of automobile operation have revealed that the hydrocarbon content of exhaust gases displays the highest value during the deceleration.
  • This is due partly to the inability of the carburetor to supply the engine with an air-fuel mixturehaving an airfuel ratio which is appropriate for providing for the satisfactory combustion of the mixture in the combustion chamber of the engine and partly to the occurance of an unsatisfactory combustion and misfire of the airfuel mixture that are invited by the remarkable increase in the intake manifold vacuum during the deceleration.
  • the carburetor In order to accomplish satisfactory combustion of the air-fuel mixture during the deceleration, therefore, it is important to enable the carburetor to supply the engine with a mixture having an air-fuel ratio best suited to eliminate the presence of partially burned or unburned airfuel mixture in the engine exhaust gases, and further to increase the amount of the mixture to be supplied to the engine thereby to prevent excess increase of the intake manifold vacuum during the deceleration.
  • the fact is however that. when in the deceleration of the automobile, the air-fuel ratio of the mixture in the carburetor remains substantially unchanged from that which is determined in the idle operation in spite of the engine speed and intake manifold vacuum changing as the automobile speed changes.
  • FIG. I is a graph showing a desired example ofthe relationship between the air-fuel ratio of an air-fuel mixture and the automobile speed during the decelerating operation;
  • FIG. 2 is a graph showing the relationship between the airfuel ratio determined under the idling conditions of the engine and the engine exhaust gas hydrocarbon content under the idle. accelerating and normal cruising operations. vi:., under the operations excepting the deceleration;
  • FIG. 3 is a graph showing the effect of the intake manifold vacuum on the exhaust gas hydrocarbon content
  • FIG. 4 is a partial vertical sectional view of a carburetor incorporating an apparatus embodying the present invention.
  • FIG. 5 is similar to FIG. 4, but shows a modification of the apparatus shown in said figures.
  • the hydrocarbon content of engine exhaust gases produced during the deceleration will be reduced to a minimum by controlling the air-fuel ratio of the mixture in such a manner as to meet with the curve a of FIG. 1 which illustrates a desired example of the relationship between the automobile speed and the airfuel ratio.
  • One simple and economical expedient of approximately realizing the curve a in a usual carburetor may be to restrict the air-fuel ratio fixedly within a certain range, say, anywhere between 12 and 13 in consideration of the air-fuel ratio at idle of the existing automobiles. This will be achieved by regulating the air-fuel ratio by the use of the usual idle fuel adjusting screw; the air-fuel ratio determined at idle remains substantially unchanged during the deceleration, too, as previously noted.
  • the intake manifold vacuum that has increased to such a high level inevitably leads to unsatisfactory combustion and misfire of the air-fuel mixture in the combustion chamber of the engine, thereby remarkably giving rise to the hydrocarbon content of the engine exhaust gases emitted during the deceleration.
  • the reasonable level to which the intake manifold vacuum should be reduced is generally considered to be in the neighborhood of 600 mm. of Hg. As illustrated by the curve c of FIG. 3, reducing the intake manifold vacuum to approximately 600 mm. of Hg is apparently conducive to the minimization of the hydrocarbon content of the engine exhaust gases.
  • FIG. 4 One embodiment of the present invention to achieve such an end is shown in FIG. 4, wherein the carburetor is illustrated to be under the decelerating operation with its butterfly valve substantially fully closed.
  • the butterfly valve 10 may be of the type which is usually used in the conventional carburetor and is mounted rotatably on the shaft 1 l.
  • Air is introduced into the slow running mixture supply flow path from the orifice 12 which is provided atop the slow running air bleed chamber 13 and which'is vented from the atmosphere. Air introduced from the orifice 12 is further admitted into the first and second slow running air bleeds l4 and 15, respectively. in a normal state. lt will be understood that the amount of air to be introduced from the orifice 12 may be determined properly by varying the inside diameter thereof. Air passing through the first air bleed 14 is then fed to the slow running jet 16 where it is mixed in a predetermined mixture ratio with the liquid fuel supplied by way of the fuel supply passage 17 from the liquid fuel source (not shown).
  • the mixture of air and fuel is metered and atomized at the slow jet l6 and delivered to the slow running economizer 18 for further mixing with air introduced from the second air bleed 15.
  • the resultant engine fuel mixture is now fed through the fuel mixture supply passage 19 and is spurted out of the slow port 20 and the idle port 21' into the main running mixture supply path of the carburetor downstream of the butterfly valve 10.
  • the amount of the fuel mixture to be spurted out of the idle port 21 may be adjusted in a usual manner by the use of the idle adjusting screw 30.
  • the slow running air bleed chamber 13 is so arranged as to communicate with the main mixture supply flow path of the carburetor downstream of the idle port 21 by way of an outlet 22, a conduit 23. an orifice 24, a valve assembly 25 and a decelerating port 29.
  • the intake manifold vacuum remains of the order of 500 mm. of Hg during the idle operation so that the ball valve member 27 is forced against the valve seat 26 by the action of the coil spring 28, prohibiting air to flow through the valve assembly 25 into the decelerating port 29.
  • the air introduced from the orifice 12 of the chamber 13 is admitted to the main mixture supply flow path as well as to the slow running mixture flow path during the deceleration while it is permitted to flow solely into the slow running fuel flow path while in the idle operation of the automobile.
  • the amount of air passing the valve assembly 25 may be determined by properly selecting the inside diameter of the orifice 24 thereof, preferably in the neighborhood of 600 mm. of Hg so as to meet with the characteristics of the curve 0 of FIG. 3.
  • the orifice 12 is so sized in inside diameter as to maintain the interior of the air bleed chamber 13 at a normal or slightly lower pressure during the idle operation and at a suitable level of vacuum during the deceleration.
  • the engine is supplied during the idle operation with such an amount of the fuel mixture as is considered reasonable in the conventional carburetors.
  • a material amount of air is fed to the main mixture supply flow path by way of the conduit 23 so that the pressure in the chamber 13 becomes negative.
  • the result is that the amount of air to be admitted to the first and second air bleeds 14 and 15, respectively, is reduced in proportion to the drop of the pressure in the chamber 13, so that the fuel mixture to spurt out of the slow port 20 and the idle port 21 is enriched.
  • the fuel mixture delivered out of these two ports 20 and 21 is admixed with the air flowing through the clearance between the butterfly valve 10 and the slow port 20 and further with air introduced from the decelerating port 29 so that the amount and the air-fuel ratio of the engine fuel mixture attain values optimum for the deceleration of the automobile.
  • the amount of air to be admixed with the fuel mixture fed from the first and second air bleeds l4 and 15. respectively is controlled through the reduction in the level of the pressure in the chamber 13 which diminishes during the deceleration. It is, however, more conducive to the increased simplicity of the mechanical construction of the carburetor to have controlled the amount of air to be admitted into the second air bleed only, through the provision of slow running air bleed chamber at the second air bleed, whereby similar performance and effect to those obtained in the first embodiment of the invention may be achieved.
  • a slow running air bleed chamber 13' and a second air bleed 15 are provided in the slow running mixture supply flow path so that air supplied from the at mosphere through the orifice 12 is mixed with the fuel mixture to be fed from the slow jet 16 and spurts out of the slow port 20 and the idle port 21 into the main mixture supply flow path during the idle operation and, while, in the deceleration, said air is also drawn to the decelerating port 29 by way of the conduit 23.
  • the air drawn from the outlet 22 is controlled by the cooperation of a solenoid valve assembly 30 and a diaphragm switch assembly 34, which are electrically wired to one another.
  • the construction of the diaphragm switch assembly 34 is such that it is divided by a diaphragm member 35 into two different chambers 36 and 37 of which the suction chamber 37 communicates with the intake manifold (not shown) by way of a conduit 42 and of which the atmospheric chamber 36 has mounted therein a set of moving and stationary contacts 39 and 40, respectively, of which the moving contact 39 is connected by a rod 4i with the diaphragm member 35.
  • the diaphragm member 35 is nonnally forced toward the chamber 36 by the action of the spring 38 and as the consequence the moving contact 39 is kept released from the stationary contact 40.
  • the solenoid valve assembly 30 has mounted therein a needle valve member 32 which is normally forced against the valve seat or stopper 33 by the action of the coil spring 31 so that air introduced by way of the conduit 23 is prohibited to flow into the decelerating port 29 inasmuch as the solenoid valve assembly 30 remains inoperative.
  • the air-fuel ratio of the engine fuel mixture for the idle and decelerating operations may be determined to at optimum values by appropriately selecting the diameters of the orifice 12', first air bleed 14 and second air bleed 15, when in designing the carburetor. Furthermore, the amount of air to be drawn from the chamber 13' to the decelerating port 29 can attain a desirable intake manifold vacuum level by properly determining the size of the orifice 24.
  • the hydrocarbon content of engine exhaust gases is diminished through the effective utilization of the abrupt increase in the intake manifold vacuum in the slow running mixture supply flow path without major dimensional modification to the carburetor in its entirety.
  • This is particularly important in this invention in that the concentration of the hydrocarbons in en gine exhaust gases is sufficiently stabilized by improving the quality of combustion in the combustion chamber especially during the deceleration of the automobile.
  • not only the amount but also the air-fuel ratio of the engine fuel mixture can be controlled during the deceleration ofthe automobile independently of the other modes of the automobile operation in such a manner as to keep the engine fuel mixture richer during the deceleration and leaner during the idle, accelerating and normal cruising operations of the automobile.
  • the intake manifold vacuum which increases abruptly at the initial stage of the deceleration of the automobile is rendered low, say, reduced to about 600 mm. of Hg which is considered a level appropriate for minimizing the presence of hydrocarbons in the engine exhaust gases without impairing the driveability of the automobile, as is previously noted with reference to the curve c of FIG. 3.
  • the apparatus according to the invention is placed on use with a carburetor operating on the lean side of the flow band of the carburetor flow curve, it will lend itself to the reduction of the hydrocarbon content of engine exhaust gases during every mode of the automobile operation.
  • the system according to the invention is operable with a relatively lean air-fuel mixture, it will prove advantageous in the reduction of carbon monoxide content of engine exhaust gases as well as in the saving of engine fuel consumption.
  • a carburetor for an automotive gasoline-powered engine having a main mixture supply flow path leading to the intake manifold of said engine and kept substantially closed by a butterfly valve mounted therein during the idle and decelerating operations of the automobile and a slow running mixture supply flow path which is adapted to supply said engine with an air fuel mixture having a predetermined air-fuel ratio during said operations and which includes a first and second air bleeds which are vented to the atmosphere, a liquid fuel passage leading from a fuel source and communicating with said first and second air bleeds, a mixture passage for passing the air delivered from said first and second air bleeds and fuel delivered from said fuel passage, a slow port communicating with said mixture passage and opening into said main mixture supply path at a position where said butterfly valve substantially closes the last named path during the idle and decelerating operations and an idle port communicating with said slow port and opening into said main mixture supply flow path downstream of said butterfly valve, a system for reducing the air-fuel ratio of the air-fuel mixture to be drawn to the combustion chamber of said engine through said
  • valve assembly further comprises a solenoid device which becomes energized in response to the increase in the vacuum at the intake manifold of the engine for thereby causing said valve member to be released from said valve seat.
  • said solenoid device is connected by an electrical circuit to a diaphragm switch assembly by way of a power source, said diaphragm switch assembly being divided by a diaphragm member into two different chambers, of which the atmospheric chamber has accommodated therein a set of moving and stationary contacts both connected with said electrical circuit and of which the suction chamber communicates with the intake manifold of the engine and has accommodated therein a coil spring acting to normally keep said moving contact released froin said stationary contact, wherein, as an increased vacuum develops at the intake manifold of the engine during the decelerating operation, said diaphragm member is displaced with said in creased vacuum exerted thereto and against the actioniof the last named coil spring in a direction to cause said moving contact to abut against said stationary contact for letting said solenoid device be energized from said power source during the decelerating operation.

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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)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
US781533A 1968-03-30 1968-12-05 Apparatus for reducing hydrocarbon content of engine exhaust gases during deceleration of automobile Expired - Lifetime US3533386A (en)

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JP2078468 1968-03-30

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US3533386A true US3533386A (en) 1970-10-13

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US (1) US3533386A (enrdf_load_stackoverflow)
DE (1) DE1816237C3 (enrdf_load_stackoverflow)
FR (1) FR1598602A (enrdf_load_stackoverflow)
GB (1) GB1242288A (enrdf_load_stackoverflow)
NL (1) NL143654B (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3680318A (en) * 1969-12-29 1972-08-01 Yasuo Nakajima Centralized air-pollution preventive system
US3706444A (en) * 1969-09-09 1972-12-19 Nissan Motor Carburettor for motor vehicle
US3738109A (en) * 1970-01-14 1973-06-12 Toyo Kogyo Co Exhaust gas purifying system
US3756208A (en) * 1969-02-05 1973-09-04 Nissan Motor Apparatus for reducing hydrocarbon content of exhaust gases during deceleration
US3866584A (en) * 1970-11-03 1975-02-18 Volkswagenwerk Ag Switching device and circuit
US3937766A (en) * 1972-05-17 1976-02-10 Alpha Romeo S.P.A. Mixture carburation device for the operation in idling conditions in progression of an internal combustion engine
US4229384A (en) * 1977-05-13 1980-10-21 Hitachi, Ltd. Carburetor with starting means

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2333968A1 (fr) * 1975-12-02 1977-07-01 Sibe Perfectionnements aux dispositifs de carburation pour moteurs a combustion interne

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3756208A (en) * 1969-02-05 1973-09-04 Nissan Motor Apparatus for reducing hydrocarbon content of exhaust gases during deceleration
US3706444A (en) * 1969-09-09 1972-12-19 Nissan Motor Carburettor for motor vehicle
US3680318A (en) * 1969-12-29 1972-08-01 Yasuo Nakajima Centralized air-pollution preventive system
US3738109A (en) * 1970-01-14 1973-06-12 Toyo Kogyo Co Exhaust gas purifying system
US3866584A (en) * 1970-11-03 1975-02-18 Volkswagenwerk Ag Switching device and circuit
US3937766A (en) * 1972-05-17 1976-02-10 Alpha Romeo S.P.A. Mixture carburation device for the operation in idling conditions in progression of an internal combustion engine
US3963808A (en) * 1972-05-17 1976-06-15 Alfa Romeo S.P.A. Carburetors for internal combustion engines
US4229384A (en) * 1977-05-13 1980-10-21 Hitachi, Ltd. Carburetor with starting means

Also Published As

Publication number Publication date
DE1816237B2 (de) 1973-09-27
GB1242288A (en) 1971-08-11
DE1816237C3 (de) 1974-04-25
NL143654B (nl) 1974-10-15
FR1598602A (enrdf_load_stackoverflow) 1970-07-06
NL6901768A (enrdf_load_stackoverflow) 1969-10-02
DE1816237A1 (de) 1969-10-23

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