DE2310873A1 - CARBURETTORS FOR COMBUSTION ENGINES - Google Patents

Description

Carburetors for internal combustion engines

The invention relates to a carburetor for internal combustion engines a float chamber, which is connected to the suction channel via a ventilation channel connected is.

Current or future legislation regarding the withdrawal of In particular, fuel vapors from a motor vehicle limit the quantities of fuel that is emitted by an internal combustion engine when it is hot, i.e. after a warm engine has been switched off. To meet the requirements To comply with such legislation, it is necessary to move the float chamber of the carburetor into the intake duct instead of outwards inwards of the carburetor. As soon as the ventilation of a float chamber is switched from an external ventilation to an internal ventilation there is often an undesirable increased fuel delivery with the throttle valve wide open and at low speeds. This increased fuel delivery is most likely due to pressure fluctuations caused in the float chamber, which occur because of pressure fluctuations in the intake duct of the carburetor via the ventilation duct to the

Act back on the float chamber.

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The object of the invention is to overcome this disadvantage of a known internal Avoid venting.

According to the invention, this object is achieved by the ventilation channel is much longer than the distance from the float chamber to the suction channel.

The ventilation channel here preferably runs in a meander shape.

The ventilation duct preferably runs above in the carburetor housing the float chamber.

The ventilation channel can run in an insert that is in the upper Part of the float chamber is arranged.

This insert can be made of plastic and on one side with be provided meander-shaped grooves through a flat plate to a Channel to be closed.

The ventilation channel is preferably longer than 200 mm.

The length and cross-section of the ventilation duct are chosen so that that the fuel flow with the throttle valve wide open is equal to the fuel flow of the same carburetor with venting of the float chamber to the outside.

The invention is illustrated by means of one in the accompanying drawings Embodiment explained in more detail.

GB-103 / February 21, 1973

309842/0349

Fig. 1 shows a partial section through a carburetor according to the Invention the line A-A in Fig. 2.

FIG. 2 is a bottom plan view of the insert of FIG. 1 according to the invention.

Fig. 3 shows a diagram in which the fuel flu ß when fully open Throttle valve is plotted as a function of the speed, with the same engine and the same carburetor once with one external ventilation, examined once with a known internal ventilation and once with the internal ventilation according to the invention became.

A carburetor 10 of an internal combustion engine of a power vehicle be seated Intake duct 11 through which air flows from an air filter to the internal combustion engine. A float chamber 12 is fueled in a known manner and the fuel in the float chamber is kept at a constant level. The space of the float chamber above the fuel level is except for a vent pipe 13, which is in the intake duct 11 of the carburetor 10 leads, closed. The conventional vent pipe 13, however, has a meander-shaped vent channel 14 in accordance with the invention in connection. The meandering ventilation channel 14 is formed by grooves 15 formed in an insert 16 which is made of plastic and is arranged in the upper part of the float chamber 12. The bottom of the insert 16 is closed by a flat plate 17. One end 18 of the meander-shaped ventilation duct 14 is in connection with the ventilation pipe 13. The other end 19 of the meander-shaped ventilation duct 14 stands via an opening in connection with the float chamber 12.

In Fig. 3 a diagram is shown in which the fuel flow in kg / h at Full load or with the throttle valve fully open is shown above the speeds.

CIIi-103 / February 21, 1973 ' ⁴ "

309842 / 03A9

The fuel flow was here with the same internal combustion engine and same carburetor held once with external venting (see curve 1).

The fuel flow was then recorded for internal venting, the length of the vent channel it was about 35 mm and one diameter of 4 mm (see curve 2).

As can be clearly seen from curve 2, occurs at low speeds between 1000 and 2500 rpm an increased friction material flow. The effect of this increased fuel flow is that the internal combustion engine has a too rich mixture is supplied and thereby its torque drops.

Subsequently, the fuel flow with an internal vent according to the Invention considered by an insert 16 with a meander-shaped ventilation channel 14 was placed in the float chamber, extending the entire length of the ventilation channel from 35 mm to 260 mm became. The cross section of the ventilation channel 14 corresponded approximately here a diameter of 4 mm (see curve 3).

As can be seen from curve 3, the internal ventilation according to the invention enables To reduce the increased friction material flow at low speeds via a long meandering ventilation duct, so that almost the values can be achieved as with external ventilation.

For every combination of an internal combustion engine with a carburetor results a maximum value for the required length of the meandering ventilation duct, which can easily be determined by empirical tests can. If the length of the ventilation duct is greater or less than this maximum value, the fuel flow is in the range of the critical speeds increase sharply between 1000 and 2500 rpm.

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309842/0349

Of course, instead of using the meander-shaped Ventilation channel of the ventilation channel can be formed directly in one piece in the housing of the carburetor.

GB-103 / February 21, 1973

309842/0349

Claims (7)

Claims Carburetor iilr internal combustion engines with ciiu'r Srlnviinnu'rkamnior that is connected to the intake duct via a ventilation duct, thereby characterized in that the ventilation duct (13 and 14) is much longer than the distance from the float chamber (12) to the suction channel (11). 2. Carburetor according to claim 1, characterized in that the ventilation duct (14) meanders. 3. Carburetor according to claims 1 and 2, characterized in that the ventilation duct (14) in the carburetor housing (10) above the float chamber (12) runs. 4. Carburetor according to claims 1 and 2, characterized in that the ventilation channel (14) runs in an insert (16) in the upper part the float chamber (12) is arranged. 5. Carburetor according to claim 4, dadu r c h gek e nn ζ e i c h η e t that the insert (16) is made of plastic and on one side with a meander-shaped Grooves (15) is provided which are closed by a flat plate (17) to form a channel. 6. Carburetor according to claims Ibis 5, characterized in that the ventilation duct (13 and 14) is longer than 200 mm. 7. Carburetor according to claims 1 to 6, characterized in that the length and the cross section of the ventilation duct (13 and 14) are chosen so that the fuel flow is the same when the throttle valve is wide open the fuel flow of the same carburetor with venting of the float chamber to the outside. GB-103 / February 21, 1973 309842/0349 Blank page