US2173281A - Carburetor - Google Patents

Description

Spt. 19, 1939.

J. LICHTENSTEIN 2,173,281

CARBURETOR} Fil led Feb. 19, .1936

INVENTOR. dam/WV Z ICHTEMSTEI/Y Patented Sept. 19, 1939 J ohann Lichtenstein,

assignor to Societe Levallois-Perret, France, Generale des Carburateurs Zenith, Levallois-Perret, France, a corporation of Switzerland Application February. 19, 1936, Serial No. $4,617 In Belgium February 19, 1935 3 Claims. (01. 261-69) The present inventionrelates to carburetors for internal combustion motors comprising an induction passage controlled by a throttle valve and supplied with fuel by a fuel reservoir comprising 5 a yieldable wall or membrane, the membrane being connected to a valve which controls the admission of fuel to the reservoir in such manner as to control the fuel pressure within the same.

The object of the invention is to provide a carburetor of this type provided with an arrangement permitting it to stop the motor.

As a general rule in internal combustion motors provided with electric ign'tion the throttle valve cannot be closed beyond a certain position which corresponds to the idling speed of the motor. In order to stop the motor, the ignition is cut off with the throttle valve in idling position; the mixture supplied to the motor ceases to burn and the motor stops. Under actual conditions in certain motors and particularly in certain. air-2. cooled motors the temperature at certain points in the cylinder walls is sufficiently high to cause automatic ignition of the fuel mixture supplied to the motor, even after the ignition has been cut off, so that the motor continues to operate through self-ignition sometimes for a considerable period of time. A carburetor in accordance with this invention comprises a chamber separated from the fuel reservoir by a membrane, or by a 'yieldable wall (membrane or piston) connected mechanically to said membrane. Said chamber is connected to the induction passage posterior to the throttle valve through a' suction passage and also through an air passage to the carburetor air intake or to atmosphere. If the section of the suction passage is increased or the section of the airpassage is diminished, the depression transmitted to the chamber is increased; in other words the pressure in said chamber is lowered. The pressure in the fuel reservoir will vary with the pressure in said chamber in such a manner that when the pressure falls in the chamber it will fall'equally in the fuel bowl and the output of fuel supplied to the carburetor will diminish correspondingly. It is known, however, that the mixture of air and fuel cannot ignite unless the fuel contained in the mixture exceeds a certain ratio. In accordance with the present invention, the carburetor comprises a controlling arrangement placed in one of said two passages permitting either the suction passage to be increased or the air passage to be reduced, in such a proportion that the amount of fuel supplied to the suction passage by the fuel reservoir will be below the minimum required to form an inflammable .mixture. When this arrangement is in operation, the motor, no longer receiving an inflammable mixture, stops.

In actual practice, the stoppage of the motor is not always instantaneous. It happens often that the intake manifold contains liquid fuel which, vaporizing in air, is capable of maintaining the operation of the motor for a certain length of time. with superchargers, it is found that after the shut-off of fuel the condensed fuel contained in the intakepassage is capable of keeping the motor running approximately for ten seconds. It is evident then that even if the output of fuel is reduced to a quantity which of itself is insufficient to form an inflammable mixture with the air, this quantity added to the condensation may be sufficient to keep the motor running and thereby retard the stopping of the motor. It is therefore preferable in order to render the invention most efficient to cut off completely the supply of fuel or at least to reduce it to its minimum value. To this end, according to the preferred application of the invention, a shut-off arrangement is provided in the air passage permitting the same to be closed completely. In this man,- ner the entire suction is transmitted to the membrane or the movable wall which encloses the chamber.

In the- Belgian Patent No. 404,966, dated August 30,- 1934', relating to altitudinal carburetor correction, there is described a carburetor of the type to which the present invention applies. In this carburetor the altitudinal correction is obtained by adjusting the relative sections of a suction passage and of an air passage connecting a chamber both to the suction passage and to the air intake or atmosphere, said chamber being operated from the fuel reservoir by a membrane enclosing the same or being enclosed by a movable wall (membrane or piston) connected mechanical- 1y to said membrane. The carburetor described in the patent differs from that of the present invention inthat the operation of the altitudinal corrector does not allow the pressure in the fuel reservoir to be reduced in a proportion sufficient to bring the fuel output below the minimum quan-y tity necessary to form a non-inflammable mixture. The same carburetor may also include the altitudinal correction provided in Belgian Patent No. 404,966 in the arrangement for causing the stoppage of the motor which is the object of the present invention.

The following description relating to the attached drawing, is given as an example for a bet- For example, in certain motors equipped 7 pressure exerted by the ter understanding of the application of the vention: Figures 1 and 2 showschematically in longitudinal section the application of the invention to a carburetor comprising an altitudinal corrector as disclosed in Belgian Patent No. 404,966. The carburetor shown in Figure 1 comprises an induction passage which is controlled by a throttle valve 2 and supp iedjwith air through air intake 3. The suction passage I is supplied with fuel by a fuel jet 4 located posterior to the throttle valve. The fuel jet is controlled by needle 5 mechanically connected to the throttle valve by means of lever 6, link 1 and lever 8.

Fuel jet 4 is supplied with fuel by a fuel reservoir 9, which is supplied with fuel under pressure through passage Ill. Admission of fuel to reservoir 9 is controlled by valve connected to membrane l2 which forms a wall of the reservoir. Membrane I2 is subjected to the pressure of a spring l3, although this spring may be omitted if desired.

Membrane l2 separates reservoir 9 from chamber II, which communicates with air intake 3 through air passage 22 and with induction passage I through conduit 29. The air passage 22 comprises a calibrated orifice while the conduit 29 comprises a calibrated orifice 3|. A

needle 32 passing through guide 33 and held by spring 3| against actuating lever 35 permits the adjustment of'the efiective cross section of orifice The pressure in reservoir 9 is such that the fuel on membrane l2 balances the pressure of the air in chamber H on the opposite face of membrane l2 plus the pressure of spring I 3. The pressures existing in reservoir 9 and in chamber H are subject to the same variations.

By operating lever 35, the relative efl'ectlve cross sections'of orifice 3| and of orifice 33 may be varied so that the depression transmitted to chamber II and the discharge of fuel is correspondingly varied. arrangement permits the incorporation in the fuel discharge of an altitudinal correction in accordance with Belgian Patent No. 404,966; that is, permits the fuel discharge to be readily varied in accordance with the altitude. The air passage 22 is controlled by valve 23 which remainsopen during the normal operation of the motor. In order to stop the motor, the valve 23 is closed, since the chamber It then communicates only with the induction Passage I, the-total depression posterior to the throttleis transmitted to membrane l2. If spring I3 is so adjusted that its pressure is inwhen the motor is stopped, the closing of valve 23 closing of valve 23 but will be reduced to-its minimum value and the residual very low in practice.

I'br example, spring I3 may be adjusted so output is usually that fuel outlet 4 is supplied under pressure of 10 grams per square centimeter. The depression to which the fuel outlet 4 is subjected at idling is about 600 grams per square centimeter and the mixture delivered by the carburetor is then correct when fuel outlet 4 discharges under a pres- -and orifice 3| controlled sure drop of 610 grams per square centimeter. When valve 23 is closed, fuel outlet 4 discharges under a pressure drop of only 10 grams per square centimeter, that is, under a pressure drop which is about one-sixtieth of the normal pressure drop. The residual fuel discharge is consequently but one-seventh "to one-eighth of that fuel discharge which, when mixed with the inducted air, forms a normal mixture. It is obvious that under these conditions the discharge of fuel at outlet 4 falls far below the minimum quantity which, mixed with the inducted air, is capable of forming an inflammable mixture. The motor stops upon receiving a mixture too lean to ignite. In order that this action take place, it is necessary that chamber ll communicate efi'ectivelywith induction passage I. Such communication is assured by providing a small section orifice 36 which constitutes a fixed communication between chamber H and induction passage In this'way the closing of valve 23 causes stoppage of the motor even if orifice 3| is completely closed by needle 32. If valve 23 were open, the total opening of orifice 3| obtainable by the movement of needle 32 would not permit the discharge of fuel to bedecreased sufliciently to render the mixture uninfiammable and cause the motor to stop. Theoretically it is possible to make the effective cross section in relation to section of orifice 3| of such size as to obtain this result, but in such case the small efi'ective aperture between orifice 3| and needle 32 in order to effect altitudinal correction would not be controlled in a practicable manner, since it is wellknown that it is impossible to regulate small sections by means of a large needle controlling a large orifice. Furthermore, it appears frequently that the altitudinal correction means are controlled automatically, which makes itimpossible to utilize such altitudinal corrector for the purpose of stopping the motor.

In order to stop the motor by increasing the section of the depression passage, an arrangement is required as shown in Figure 2. In this arrangement the induction passage communicates with chamber I both through passage 29 by needle 32, and also by a bypass 3! controlled by valve 33. Chamber ll communicates also with air intake 3 through a passage 39 in which is incorporated calibrated orifice ll. During the operation of the motor, valve 33 remains closed and the carburetor functions in the same manner as the carburetor shown in Figure 1-. To stop the mo r thevalve the motor act directly on the membrane of the fuel reservoir, this depression may equally well chamber larger than that closing the fuel chamber it would be possible to apply sumcient force to the fuel valve to positively close the valve for stopping the engine.

I claim:

1. In a carburetor for an internal combustion engine, an induction passage, a throttle controlling the same, a fuel nozzle discharging into said induction passage, a fuel reservoir supplying fuel to said nozzle and comprising a movable wall, a valve connected to said wall and controlling the inflow of fuel to said reservoir, a pressure chamber controlling the position of the movable -wall, two passages leading from the pressure chamber to separate points at opposite sides. of the throttle, a valve for completely closing one of the two passages, and a mixture control valve,

1 for varying the effective cross section of the other of the two passages.

2. In a carburetor for an internal combustion engine, an induction passage, a throttle controlling the same, a fuel nozzle discharging into said induction passage, a fuel reservoir supplying fuel to said nozzle and comprising a wall movable under the influence of pressure, a fuel valve actuated by said wall and controlling the inflow of fuel to said reservoir, 'a pressure chamber controlling the position of the wall, a suction conduit connecting the pressure chamber to the induction passage posterior to the throttle, a second conduit connecting the pressure chamber to the induction passage anterior to the throttle, a valve operative independently of throttle position to completely close the second conduit to thereby substantially close said fuel valve, and a mixture control valve for varying the effective cross section of the suction conduit.

3. The invention defined in claim 2, wherein. the suction conduit comprises in addition a restricted bypass around the mixture control valve.

J OHANN LICHTENS'IEIN.

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