DE2060612A1 - Carburetor - Google Patents

Description

PATENT LAWYERS 1 MONKS 15
KAISER-LUDWIG-PLATZ β
TEL. M11 / S30S11
930212
CABLES: THOPATENT
TELEX: FOLQT Dipi.chem. Dr D. Thomson Dipi.-ing. H. Tiedtke
Dipi.-chem. G. Bühiing Dipi.-ing. R. Kinne FRANKFURT (MAIN) 50
FUCHSHOHL 71
TEL. M11 / S14M Dipi.-ing. W. Weinkauff 2060612

Answer requested to: Plea ·· reply toi

8000 MQnchcn 15 December 8, 1970 T 3941 / case PG 23 - 7028

Nissan Motor Company, Limited
Yokohama City, Japan

Carburetor

The invention relates to a carburetor for
Motor vehicle internal combustion engines, specifically to a carburetor of the type whose air funnel or venturi section has a variable cross-sectional area; the invention relates in particular to a carburetor, the engine thereby with
a selected air-fuel mixture supplies that the effective cross-sectional area at the venturi section is changed as a function of the change in the .Under pressure itromab the venturi section of the carburetor.

109825/1415

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BATH ORIGINAL

In a conventional carburetor with a variable venturi cross-sectional area a throttle valve is essentially closed when idling or when the engine is lightly loaded, so that there is little or no suction around the venturi section. This increases the effective cross-sectional area at the venturi section reduced, whereby the speed of the air flowing through is increased. Under these conditions a Excess liquid fuel is sucked from the fuel nozzle, whereby the fuel mixture to be supplied to the engine becomes too rich; this leads to the engine producing a large amount of unburned,

releases gases containing toxic hydrocarbons into the atmosphere.

The air-fuel ratio of the air-fuel mixture for idling operation is used in the conventional carburetor controlled with a variable venturi section by changing the position of the fuel nozzle relative to the fuel needle. Such The position of the nozzle also determines the air-fuel ratio not only when idling but also during other engine operating conditions, so that it is extremely difficult to run the engine while idling with a fuel mixture with optimal To supply the air-fuel ratio without at the same time the To impair air-fuel ratios that are optimal for other operating conditions.

Object of the invention is to eliminate these and other drawbacks inherent in the known gasifiers variable Venturiquereohnitt} According to the invention, the air-Kraftetoffverhlltni "to the eVktt ^ S ^! V £ ft ^Governing fuel ratio

BAD ORIQJWit.

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and the emission of unburned hydrocarbons is controlled in an economical and simple manner during idling from the engine without significantly affecting air-fuel ratios during other engine operating conditions be excluded.

This task is in a carburetor for an automotive internal combustion engine with a main air duct, a throttle valve, one between the main air duct and the throttle valve located venturi section with a constriction and a Flow regulation device for continuous reduction the effective cross-sectional area at the venturi section when closing the throttle valve, one between the venturi section and the main mixture passage located upstream of the throttle valve, and a main mixture passage located downstream of the throttle valve an intake line of the engine leading to the main mixture duct and a main mixture duct opening into the venturi section and having a fuel supply line connected fuel nozzle released by one of the main air channel outgoing additional air channel, an additional primary mixture channel starting from the upstream mixing channel, where the additional channels meet at a connection, • as a result of which sucked in from the main air duct above the auxiliary air duct Air is mixed with fuel mixture by the Additional primary mixture channel is sucked in from the upstream mixture channel, furthermore through an additional secondary mixture channel, from the dew connection and through the downstream one

109825/141 5

Main mixture duct to the intake pipe leads to the fuel feed mixture to the engine, and through a flow control device, which is arranged between the additional air duct and the additional secondary mixture duct and an air flow adjusting device which is housed in the auxiliary air duct to the air flow rate through the auxiliary air duct to control and thereby to determine an air-fuel ratio for the fuel mixture and also a fuel Has mixture adjustment device in the additional secondary mixture channel is subordinated to the fuel mixture flow rate to control.

The invention is explained in more detail below with reference to schematic drawings of an exemplary embodiment.

Fig. 1 is a schematic sectional view

a carburetor with a variable venturi cross section according to the invention;

Figure 2 is a graphical representation for a

Typical example of the relationship between the volume of intake air and the air-fuel ratio of the air-fuel mixture in the embodiment of the invention shown in FIG. 1.

According to FIG. 1, the carburetor according to the invention is generally designated by the reference numeral 10. The carburetor 10 has how

109825/141 5

BATH ;

usually, a main air duct 12 which comes from the open air, an upstream main mixture duct 14 which is connected to the main air duct 12, a downstream main mixture duct 16 which is connected to the. Intake line (not shown) of the engine leads, a throttle valve 18, which controls the flow of the air-fuel mixture to the engine via the mixture channels 16 and 18 and a Venturiäbabschnitt 20, which has a flow regulator 22 and a constriction or bridge 24. The ^ carburetor 10 also has a fuel nozzle 26 for the delivery of liquid fuel into the mixture duct 14. A liquid fuel supply line 28 ends in the fuel nozzle 26 at the venturi section 20 of the carburetor 10. The fuel supply duct 28 is above a duct 30 with a float chamber (not shown) in Link. The flow regulator 22 has a housing 32 and a movable suction piston 34 of known type. A nozzle needle 36 protrudes from the bottom wall of the suction piston 3 ** and is inserted into the fuel supply line 28 through the fuel nozzle 26. The nozzle needle 36 is tapered towards the M point in order to continuously change the amount of fuel admitted into the venturi section 20 when the suction piston 34 and accordingly the nozzle needle 36 move up and down depending on fluctuations in the suction line, so that the effective venturi cross section varies into which the liquid fuel is sucked from the fuel nozzle 26.

During idling operation is in accordance with Figure I · closed the throttle valve is substantially such that upstream of the throttle valve 18 adjusts atmospheric pressure and the suction piston 34 approximates 41 · narrowing od # r Brtfoke f * to the Luftdurahflui

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to be limited by the venturi section 20. In this case, the speed of the air flowing through the effective cross-sectional area of the venturi section 20 increases, so that excessive liquid fuel is sucked from the fuel supply line 28 into the upstream main mixture duct 14. Through this the fuel mixture becomes enriched and becomes the amount of unburned or partially burned fuel content the engine exhaust gases increased during idling due to incomplete combustion.

In order to supply the engine with a fuel mixture with an optimal air-fuel ratio during idling, the invention proposes providing an additional air duct 38 on the carburettor, the inlet opening 40 of which opens into the main air duct 12, and an additional primary mixture duct 42, the inlet opening 44 of which opens into the upstream main mixture channel opens and which, as shown, is connected to a connection 46 with the additional air channel 38, as well as an additional secondary mixture channel 48 which emanates from the connection 46 and whose outlet opening 50 into the downstream main mixture channel 16 or, if necessary, into the intake line of the Motors opens. The channels 38, 42 and 48 thus meet at the connection 46, where the air sucked in from the main air channel 12 via the additional air channel 38 is mixed with the fuel mixture that is supplied from the upstream main mixture channel 14, with the resulting air-fuel mixture is supplied via the Susatz-Saku, lärgamiseh- channel 48 into the main mixed channel 16 located downstream.

BAD ORJQINAt

, 109825 / 141.5

For regulating the air flow through the Channel 38 and the fuel mixture flow through the Channel 48 is a flow control unit between channels 38 and 48 which is generally designated by the reference numeral 52.

The flow control unit 52 has a housing 5 **, an air flow adjustment screw 56 for controlling the air

flow through the channel 38 and a fuel mixture flow ^w flow adjusting screw 58 for controlling the fuel mixture flow through the channel 48. These adjusting devices 56 and 58 are, for example, adjustable screws.

The flow control unit 52 can thus control both the air-fuel ratio and the amount of fuel mixture to be supplied to the engine during idling. The Luftdurchflußeinstellschraube 56 controls the amount of the air supplied to port 46, where the air supplied from the main air passage 12 is mixed with the M located upstream of the main mixture passage 14 supplied fuel mixture at a relatively lean fuel mixture. The fuel mixture generated at the connection 46 is metered by the screw 58 and fed to the intake line of the engine through the opening 50 and the main mixture duct 16 located downstream.

If, during operation, the throttle valve is essentially closed during idling operation or with a light engine load, developed downstream of the throttle valve 18 is a high negative pressure,

'109 8 2

so that a pressure difference occurs across the throttle valve 18. As a result, the air flows in the main air channel 12 through the opening 40 and the channel 38 to the connection 46 if an atmospheric pressure is set upstream of the throttle valve 18, the suction piston 34 approaches the constriction 24 and reduces the effective cross-sectional area at the venturi section 20. The air passes through the venturi section 20 into the mixture channel 14, so that the liquid fuel is guided from the fuel supply channel 28 into the mixture channel 14 and with the air contained therein is mixed. It is important that in this case the throttle valve 18 is completely or substantially closed so that the fuel mixture during idle operation completely through the channel in the optimal amount and optimal mixture ratio into the intake line of the engine goes, thereby preventing the emission of toxic unburned hydrocarbons.

In idle mode, as described above, the flow rate of the air mixture through the venturi section 20 is so low that when the flow rate of the air through the channel 38 is increased by turning the screw 56, the air passage through the venturi section 20 decreases further and, accordingly, the suction piston 34 widens the constriction 24 approaching. In this case, too much liquid fuel is drawn from the fuel supply duct 28 into the upstream main mixture duct 14, as a result of which the fuel mixture is excessively enriched, as indicated by curve A in FIG. 2 is indicated.

To avoid such a difficulty, a stopper or stop 60 can be provided on the constriction 24.

109825 / U1 5

The stop 60 limits the movement of the suction piston 3 * 1, whereby air can pass through the venturi section 20 at a limited constant rate when the suction piston 34 rests against the stop, so that the air-fuel ratio is kept at a constant level, as is interrupted by Line B in Fig. 2 is indicated. The air-fuel ratio of the air-fuel mixture is thus adjusted by turning the screw 56 after the suction piston 34 has come into contact with the constriction 24 so that the M discharge of unburned hydrocarbons is prevented.

If the throttle valve 18 is moved into the open position when the engine is running at high speed or when the engine is under high load, the negative pressure prevailing downstream of the venturi section 20 causes the suction piston 34 to lift off the constriction 24, thereby enlarging the air passage and the fuel passage through the venturi section 20. Thus, when operating at high speed, the engine is supplied with a fuel mixture of optimal volume and with optimal mixture ratio. Since the pressure difference between the main air duct 12 or the upstream main mixture duct lh and the downstream main mixture duct 16 then decreases as the opening cross-section of the throttle valve 18 increases, the amount of fuel mixture passing through duct 48 decreases and in this way has no noticeable influence on the degree of performance engine stops when operating at high speed.

Thee is also clearly shown by the fact that the Kohlenwaeeeretoffhalt that in a conventional carburetor

10S825 / U15

is about 7 % , reduced to about 0.2 % when idling
can be achieved if a carburetor with the improvement according to the invention is used, while the hydrocarbon is reduced from 0.5% to 0.2 % when the vehicle is driven at a speed of 60 km / h.

From the above it follows that the air-fuel mixture in an economical and simplified manner
Turning the screw 56 for idling is adjusted so
that the emission of toxic hydrocarbons in the engine exhaust gases is reduced and that the air-fuel ratio is determined so that it is designed specifically for idling operation, which in no way adversely affects the output of the engine
when it is operated at high speed or heavy load.

109825 / U1 5

Claims (1)

-U- Claims "Λ / 1. Carburetor for a motor vehicle internal combustion engine. with a main air duct, a throttle valve, an between the main air duct and the throttle valve located Venturi section with a constriction and a flow control device for continuously reducing the effective cross-sectional area on the venturi when the throttle valve is closed, an upstream main mixture channel that runs between the Venturi section and the throttle valve is arranged, a downstream main mixture channel, which is located downstream of the throttle valve and leads to an intake line of the engine ^ and with a fuel nozzle opening into the venturi section, which is connected to a fuel supply channel j characterized by one of the main air channel (12) outgoing additional air duct (38), an additional primary mixture duct ( ^{42) originating from the upstream mixture duct (I 1} O), the additional ducts meeting at a connection (46), whereby the air sucked in from the main air duct through the supplementary air duct with a mixture duct located upstream The fuel mixture sucked in through the additional primary mixture duct is mixed, through an additional secondary mixture duct (48) which originates from the connection (46) and leads via the downstream main mixture duct (16) to the intake line in order to supply the fuel mixture to the engine and through a flow control device (52 ), which is arranged between the additional air duct (38) and the additional secondary mixture duct (48) and has an air flow adjustment device (56), 109825 / U16 which is provided in the auxiliary air duct to the air flow rate to control through the additional air duct and set an air-fuel ratio of the fuel mixture, as well a fuel mixture adjustment device (58), which in the Additional secondary mixture channel is provided to control the flow rate of the fuel mixture 2. Carburetor according to claim 1, characterized in that on the constriction (2 ¹ I) there is a stop (6O) for limiting the movement of the flow regulating device (, 3 ¹ O in the direction of the constriction, so that on the Venturi section (20) Air can flow past at a limited constant rate, thereby preventing the delivery of an excess of liquid fuel from the nozzle (26) during idling . 1 09825 / U 1 5 91 I θ SJ θ 91 ■ ΐ, , iiiihiiij ,! ■; ,,, .- ■ i: .... i !! iii: i!; :: ii-.i>!;!; I,: -., ■■; ■ '■ skii, .,