US3590793A - 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
US3590793A
US3590793A US781532A US3590793DA US3590793A US 3590793 A US3590793 A US 3590793A US 781532 A US781532 A US 781532A US 3590793D A US3590793D A US 3590793DA US 3590793 A US3590793 A US 3590793A
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Prior art keywords
engine
air
automobile
intake manifold
fuel
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Expired - Lifetime
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US781532A
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English (en)
Inventor
Kenji Masaki
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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

Definitions

  • the present invention relates to a system for reducing the hydrocarbon content of exhaust gases of an automotive gasolinepowered internal combustion engine, and more par ticularly 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 step mixture supply flow path of a carburetor and the level of intake manifold vacuum during deceleration of the automobile.
  • Automobile operation is usually divided into four different driving conditions; idle, acceleration, normal cruising, and deceleration.
  • the range of hydrocarbon content of engine exhaust gases varies 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 peaks up during deceleration. This is due partly to the inability of the carburetor to supply the engine with an air-fuel mixture having an air-fuel ratio which is appropriate to provide a satisfactory combustion of the mixture in the combustion chamber of the engine and partly to the occurrence of an unsatisfactory combustion and misfiring of the air-fuel mixture that are invited by the increase in the intake manifold vacuum during deceleration.
  • the carburetor is capable of supplying the engine with a mixture having an airfuel ratio best suited for each mode to eliminate the presence of partially burned or unburned hydrocarbons in the engine exhaust gases, and further to increase the amount of the mixture to be supplied to the engine thereby to prevent an excess increase of the intake manifold vacuum during deceleration.
  • the fact is however that, during deceleration of the automobile, the air-fuel ratio of the mixture produced by the carburetor remains substantially unchanged from that which is produced during 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 of the relationship between the air-fuel ratio of an air-fuel mixture and the automobile speed during decelerating operation;
  • FIG. 2 is a graph showing the relationship between the airfuel ratio determined under the idling conditions of the engine and the total engine exhaust gas hydrocarbon content under the idling, accelerating and normal cruising operations, viz., under the operations excepting 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 a system embodying the invention which is under the idle operation of the automobile;
  • FIG. 5 shows the system of FIG. 4 under deceleration of the automobile
  • FIG. 6 shows a modified form of the system of FIGS. 4 and 5.
  • the hydrocarbon content of engine exhaust gases produced during deceleration will be reduced to a minimum by controlling the airfuel ratio of the mixture in such a manner as to meet with the curve (a) of FIG. 1 which illustrates an example of a desired relationship between the automobile speed and the air-fuel ratio.
  • One simple and economical expedient of approximately realizing the curve (a) in a usual carburetor may be to restrict the air-fuel ratio to a predetermined within a certain range, say, anywhere between 12:l and l3r1 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 adjusting screw; the air-fuel ratio determined for idling remains substantially unchanged during 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 an increase in the hydrocarbon content of the engine exhaust gases emitted during 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 (0) of FIG 3, reducing the intake manifold vacuum to approximately 600mm. of 600 mm. is apparently conducive to the minimization of the hydrocarbon content of the engine exhaust gases.
  • the carburetor of this type will have the flow characteristics dictated by the lean side of the flow band in the established carburetor flow curve
  • using the system according to the invention in a carburetor having said flow characteristics will be conducive to the reduction of the total amount of hydrocarbons in engine exhaust gases emitted during the different operations of the automobile.
  • FIG. 4 One embodiment of the present invention to achieve such an end is shown in FIG. 4, wherein the carburetor is illustrated with the engine idling and the secondary butterfly valve substantially fully closed and with the secondary side of the car buretor kept inoperative.
  • the butterfly valve 10 may be of the type which is usually used in the conventional carburetors and is rotatable with the shaft 11.
  • Represented by 12 is a step air bleed, which is vented from the atmosphere and which is so sized in diameter as to admit a suitable amount of air to the step fuel supply flow path of the carburetor.
  • the air bleed l2 communicates upstream with a step jet 13 by way of a passage 15.
  • the fuel fed from the liquid fuel passage 14 leading to the fuel source (not shown) is metered and mixed with air introduced from the air bleed 12.
  • the resultant mixture of air and fuel is then introduced into a step fuel mixture passage 16.
  • a combination valve and diaphragm fuel control assembly 18 is provided behind the step port I7, whereby the air-fuel mixture flowing in the fuel mixture passage 16, is allowed into the carburetor downstream of the secondary butterfly valve 10 during deceleration of the automobile when the intake manifold vacuum increases abruptly while, in the idling operation, the step fuel supply flow path of the carburetor remains inoperative with the secondary butterfly valve fully closed.
  • the construction ol'the fuel control assembly 18 is such that it is divided by a diaphragm member I9 into atmospheric and suction chambers 20 and 21 of which the suction chamber 21 communicates with the intake manifold (not shown) of the engine by way of a suction conduit 25 and the atmospheric chamber 20 has provided therein a valve member 23 which is fixedly connected with the diaphragm member I9.
  • the diaphragm member 19 and accordingly the valve member 23 are normally held in their leftmost positions, namely, in positions remotest from the suction conduit 25 by the action of a coil spring 24, as illustrated in FIG. 4.
  • the valve member 23 has a hollow, cylindrical and openended portion 23', m which are provided two different holes 26 and 27 of which the former is shown to be smaller in diameter than the latter.
  • the hole 27 is located in such a manner as to let the air-fuel mixture passage 16 communicate with the step port 17 and be isolated from the passage 28 leading to the decelerating port 29 during the idling operation of the automobile when the valve member 23 is held in a position remotest from the suction conduit 25 as shown in FIG. 4, while the hole 26 is located in such a manner as to let the airfuel mixture passage 26 communicate not only with the step port 17 but with the passage 28 when the valve member 23 is held in its rightmost position, viz., when in deceleration, as shown in FIG. 5.
  • the engine intake manifold vacuum is kept at a relatively low level and, as a consequence, the diaphragm member 19 of the fuel control assembly 18 is held in the leftmost position on the drawing by the action of the coil spring 24.
  • the result is that the ztir fuc mixture passage 16 is permitted to communicate with the step port 17 through the hole 27 of the cyiindrical portion 23' and is prohibited from communicating with the passage 28 leading to the decelerating port 29 which opens into the secondary main mixture supply flow path of the "tit-buretor downstream of the secondary butterfly valve 10.
  • the secondary butterfly valve 10 being in a substantially fully closed position, however, there takes place no flow of air between the secondary side of the carburetor the secondary main mixture supply flow path and the step fuel supply flow path so that the atomized air'fuel mixture is not generated.
  • the air-fuel mixture in the fuel mixture passage I6 is introduced into the main mixture supply flow path downstream of the butterfly valve 10 through the decelerating port 29 during deceleration 'of the automobile, thereby eliminating the possibility of an unburned fuel remaining in the engine exhaust gases, which would otherwise lead to the presence of hydrocarbon content therein.
  • the hole 26 is so sized in diameter as to serve as an orifice adapted to properly determine the flow rate of the air-fuel mixture which debouches into the step port 17.
  • the air-fuel mixture to be drawn into the decelerating port 29 through the passage 28 is mixed with air supplied from the step port 17 so that the air-fuel ratio of the air-fuel mixture is controlled to a satisfactory level for the operation of the engine during deceleration.
  • the inlet slit of the step port 17 is usually shaped, sized and located in such a manner as to provide for the best performance of the secondary side of the carburetor.
  • the size of the said inlet slit being optimum for compensating for the extreme deficiency of air in the fuel mixture during deceleration, the slit used in the conventional carburetor can be utilized without making any modification thereto.
  • the secondary butterfly valve may be of the type which is usually used in the conventional carburetors of compound type and there is, again, no need of making a major modification thereto in respect of the dimensions.
  • the tip of the butterfly valve 10 thinner toward the peripheral edge thereof so that, when the butterfly valve is held in a substantially fully closed position as in the idling and deceleration, the upper surface of the butterfly valve becomes substantially flush with the lower periphery of the slit of the step port 17.
  • the rate of the coil spring 24 is so determined that it overcomes the force of the intake manifold vacuum occurring during the idling operation, so that the fuel control assembly 18 remains inoperative under the automobile operation excepting deceleration.
  • Represented by 30 is a decelerating port adjusting screw, which is adapted to control the amount of the air-fuel mixture to be debouched out of the decelerating port 29, which screw may be removed if desired, however.
  • the fuel control assembly 18 is described and shown to use a diaphragm member, it will be understood that the assembly may be operated by the use of a solenoid device which is actuated by a diaphragm switch assembly of suitable construction arrangement.
  • the air-fuel mixture fed from the passage 16 is substantially shut ofi from the engine combustion chamber while in the idling operation, but, as soon as the automobile slows down on deceleration and the manifold vacuum decreases rapidly, the air-fuel mixture from the passage 16 is supplied with additional air from the step port 17 and is introduced to the engine combustion chamber during deceleration.
  • FIG. 6 shows a modified form of the system according to the present invention, wherein the valve for regulating the flow of air-fuel mixture in the step mixture supply flow path is constructed basically similarly to the counterpart of the first embodiment and is controlled by means of an electrically powered solenoid device actuated by a diaphragm switch assembly is constructed basically similarly to the counterpart in the first embodiment.
  • the valve 23 is connected with a solenoid valve assembly 31 incorporating a solenoid device 32 and a coil spring 33 which normally holds the valve member 13 in a position to close the passage 28 from the step port 17 and the passage 16.
  • the solenoid valve assembly 31 is linked by a wire circuit to a diaphragm switch assembly l8 via a power source 34.
  • the assembly 18 is divided by a diaphragm member 19 into atmospheric and suction chambers 20' and 21'.
  • the suction chamber 21' communicates with the intake manifold (not shown) of the engine by way of a conduit 35, while the other atmospheric chamber 20' has mounted therein a moving contact 36a and a stationary contact 36b.
  • a coil spring 24' is mounted in the chamber 2
  • the diaphragm member 19 is forced toward the atmospheric chamber 20' by the action of the spring 24- as shown in the drawing so that the moving contact 360 remains released from the stationary contact 36b, disconnecting the circuit connecting the diaphragm switch assembly ll and the solenoid valve assembly 31. While the solenoid valve assembly 31 remains deenergized, the valve member 23 rests at its leftmost position on the drawing by the action of the spring 33 so that the step port 17 is isolated from the passage 28, prohibiting the mixture to spurt from the passage 16 into the secondary main mixture supply flow path downstream of the butterfly valve 10 during the idle operation.
  • the hydrocarbon content of engine exhaust gases produced during deceleration is diminished through the effective utilization of the abrupt increase in the intake manifold vacuum of the engine 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 engine exhaust gases is sufficiently stabilized by improving the quality of combustion in the combustion chamber especially during deceleration of the automobile.
  • not only the amount but also the air-fuel ratio of the engine air-fuel mixture can be controlled dun'ng deceleration of the automobile independently of the other modes of the automobile operation in such a manner as to keep the engine air-fuel mixture richer during deceleration than during the idling, accelerating and normal cruising operations of the automobile.
  • the intake manifold vacuum which increases abruptly at the initial stage of 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) ofFlG. 3.
  • the system 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 during the idling, accelerating and normal cruising operations 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.
  • 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 move to a position to permit said mixture passage to communicate with said deceleration port.
  • 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 atmospheric and suction chambers, of which the atmospheric chamber has accommodated therein a set of moving and am' tionary contacts both connected with sand 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 releases from 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 by the increased vacuum exerted thereon and against the action of the last named coil spring in a direction to cause said moving contact to abut against said stationary contact for causing said solenoid device he 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)
US781532A 1968-03-30 1968-12-05 Apparatus for reducing hydrocarbon content of engine exhaust gases during deceleration of automobile Expired - Lifetime US3590793A (en)

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JP2078568 1968-03-30

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US (1) US3590793A (fr)
DE (1) DE1816232C3 (fr)
FR (1) FR1599395A (fr)
GB (1) GB1254458A (fr)
NL (1) NL147509B (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3749376A (en) * 1970-06-12 1973-07-31 Vic Chemicals Inc Vapor injector for engines
US3796415A (en) * 1972-08-17 1974-03-12 Colt Ind Operating Corp Carburetor fuel transfer discharge port
US3942493A (en) * 1972-09-22 1976-03-09 Robert Bosch Gmbh Fuel metering system
US3952076A (en) * 1974-03-21 1976-04-20 Regie Nationale Des Usines Renault Carburettors
US4007721A (en) * 1974-05-17 1977-02-15 Teledyne Industries, Inc. Fuel metering apparatus for a carburetor
US4092961A (en) * 1977-03-10 1978-06-06 Toyota Jidosha Kogyo Kabushiki Kaisha Carburetion system for preventing engine misfires during gear changes
US4104881A (en) * 1975-05-12 1978-08-08 Honda Giken Kogyo Kabushiki Kaisha Prevention of overheating of catalytic converter for engine exhaust gases
US4146595A (en) * 1976-12-13 1979-03-27 Osrodek Badawczo-Rozwojowy Samochodow Malolitrazowych "Bosmal" Idling device of carburettor
EP0023837A1 (fr) * 1979-08-02 1981-02-11 Xtec Incorporated Dispositif économiseur de carburant pour moteurs à combustion interne
USRE30622E (en) * 1978-04-17 1981-05-26 Teledyne Industries, Inc. Fuel metering apparatus for a carburetor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2921920C2 (de) * 1979-05-30 1982-11-18 Adam Opel AG, 6090 Rüsselsheim Vorrichtung zur Verhinderung des Nachlaufens bei abgeschalteter Zündung und der knallartigen Nachverbrennungen bei Schubbetrieb von Verbrennungskraftmaschinen, insbesondere in Kraftfahrzeugen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2392681A (en) * 1945-06-23 1946-01-08 Mallory Marion Carburetor for internalcombustion engines
US2621911A (en) * 1947-12-30 1952-12-16 Bendix Aviat Corp Carburetor
US2824726A (en) * 1955-11-08 1958-02-25 Gen Motors Corp Degasser attachment for internal combustion engines
US3042387A (en) * 1959-12-01 1962-07-03 Kenneth P King Fuel shut off device or degasser
US3078078A (en) * 1960-03-30 1963-02-19 Acf Ind Inc Carburetor
US3304068A (en) * 1964-08-13 1967-02-14 Ford Motor Co Automatic idle speed-up device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2392681A (en) * 1945-06-23 1946-01-08 Mallory Marion Carburetor for internalcombustion engines
US2621911A (en) * 1947-12-30 1952-12-16 Bendix Aviat Corp Carburetor
US2824726A (en) * 1955-11-08 1958-02-25 Gen Motors Corp Degasser attachment for internal combustion engines
US3042387A (en) * 1959-12-01 1962-07-03 Kenneth P King Fuel shut off device or degasser
US3078078A (en) * 1960-03-30 1963-02-19 Acf Ind Inc Carburetor
US3304068A (en) * 1964-08-13 1967-02-14 Ford Motor Co Automatic idle speed-up device

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3749376A (en) * 1970-06-12 1973-07-31 Vic Chemicals Inc Vapor injector for engines
US3796415A (en) * 1972-08-17 1974-03-12 Colt Ind Operating Corp Carburetor fuel transfer discharge port
US3942493A (en) * 1972-09-22 1976-03-09 Robert Bosch Gmbh Fuel metering system
US3952076A (en) * 1974-03-21 1976-04-20 Regie Nationale Des Usines Renault Carburettors
US4007721A (en) * 1974-05-17 1977-02-15 Teledyne Industries, Inc. Fuel metering apparatus for a carburetor
US4104881A (en) * 1975-05-12 1978-08-08 Honda Giken Kogyo Kabushiki Kaisha Prevention of overheating of catalytic converter for engine exhaust gases
US4146595A (en) * 1976-12-13 1979-03-27 Osrodek Badawczo-Rozwojowy Samochodow Malolitrazowych "Bosmal" Idling device of carburettor
US4092961A (en) * 1977-03-10 1978-06-06 Toyota Jidosha Kogyo Kabushiki Kaisha Carburetion system for preventing engine misfires during gear changes
USRE30622E (en) * 1978-04-17 1981-05-26 Teledyne Industries, Inc. Fuel metering apparatus for a carburetor
EP0023837A1 (fr) * 1979-08-02 1981-02-11 Xtec Incorporated Dispositif économiseur de carburant pour moteurs à combustion interne
US4344406A (en) * 1979-08-02 1982-08-17 Gasaver Corp. Fuel saver

Also Published As

Publication number Publication date
NL147509B (nl) 1975-10-15
NL6901667A (fr) 1969-10-02
GB1254458A (en) 1971-11-24
FR1599395A (fr) 1970-07-15
DE1816232B2 (de) 1974-03-14
DE1816232C3 (de) 1974-10-24
DE1816232A1 (de) 1969-10-16

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