US2269276A - Carburetor - Google Patents

Description

Jan. 6, 1942- J. LICHTENSTEIN CARBURETOR Original Filed Feb. 5, 1936 2 SheetsSheet l .to facilitate the description.

Patented Jan. 6, 1942 CARBURETOR Johan Lichtenstein, Levallois-Perret, France, as-

signor to Societe Generale des Carburateurs Zenith, Geneva, Switzerland Switzerland, a corporation of Original application February 5, 1936, Serial No. 62,499. Divided and this application January 5, 1940, Serial'No. 312,614. -In Belgium February 8, 1935 I have applied for patent in: Belgium, February 8, 1935, now issued as Belgian Patent No. 407,771; Germany, application for patent of addition filed on February 8, 1936; Great-Britain, February 10, 1936, now issued as British Patent of Addition 474,975; France, February 7, 1936, now issued as French Patent 804,028; Italy, February 3, 1936, now issued as Italian Patent 339,760; Poland, application for patent of addition filed on February 5, 1936; and Czechoslovakia, applicafor patent of addition filed on February 4,

. This invention relates to improvements in carburetors for internal combustion motors, of the type described in Belgian Patent 406,646, of December 5, 1934, in the name of Societe Generale des Carburateurs Zenith, for improvements in carburetors. The present application is a divisional of my copending application Serial Number 62,499, filed February 5, 1936.

In said Belgian patent, there is described a carburetor comprising a mixture passage having an air inlet and a mixture outlet connected to .the motor, a throttle controlling the effective cross section of said passage, and a fuel outlet discharging into said passage posterior to the throttle. The carburetor is characterized essentially by a movable control member which controls the pressure at which liquid fuel is supplied to the fuel nozzle, theposition of said control member being a function of the absolute pressure obtaining in the mixing chamber of the carburetor posterior to the throttle and preferably of the absolute pressure which obtains in said mixture passage in the vicinity of the fuel nozzle. This control member will be referred to hereinafter as the manometric control member In the preferred embodiment, a second regulating device influencing the discharge of fuel delivered by the, fuel nozzle is controlled by the throttle. The manometric control member is arranged in such manner as to provide automatic functioning of the carburetor; that is to say, in such manner that the carburetor will deliver to the motor a mixture of the correct composition under all conditions of operation, and, when applied to an aircraft carburetor, is furthermore arranged in such manner as to provide an altimetric correction, that is to say in such manner as to modify the discharge of fuel in the degree required by variations in altitude.

- It is known that the. composition of the combustible mixture supplied to an internal combus- 3 Claims. (Cl. 26169) but that this composition may on the contrary vary within certain limits. As a general rule, if the richness of the mixture is increased, the motor is enabled to develop greater power, but the specific consumption is higher in such case. It is of advantage, chiefly in aviation carburetors.

.to provide means for modifying the richness of the mixture delivered, so as either to get maximum engine power or to diminish the specific consumption. In general, this modification of the richness is made at the will of the pilot.

The present invention has for its object an arrangement permitting the richness of the combustible mixture to be varied in carburetors of thetype described in said Belgian patent.

According to the present invention, the influence of the manometric control member on the discharge of fuel may be varied by a supplemental adjusting member. This adjusting member will generally be manually controlled, but

it will obviously be possible to control it autoa' mixture outlet 3 connected to the motor. The

effective cross section of the mixture passage l is controlled by'a throttle 4 actuated by means of lever 5 and rod 6.

The fuel nozzle 1 discharges into the venturi 8 posteriorjto the throttle 4. The cross section of the'fuel jet is controlled by a tapered buretor. throttle 4 through the intermediary of the arm needle 25 the shank 26 of which passes through a bushing 21 carried by the body of the car- Needle 2526 is controlled by the 28 of lever 5, line 29 andlever 30 turning about the axis 3|.

The fuel nozzle 1 is supplied with liquid fuel by a pressure regulator designated as a whole by the numeral 9. The pressure regulator 9 includes a fuel chamber l0 supplied with fuel under pressure through the conduit II and the orifice I4. The fuel chamber I0 is closed by a flexible membrane I2 connected to a movable tion engine need not be an absolutely fixed one, 55 valve member I! controlling the inflow of fuel to the fuel chamber I through the orifice I4, the arrangement being such that any increase in pressure within the fuel chamber I0 or any decrease inpressure within the adjoining chamber I5 tends to move membrane I2 upwardly and close the valve I3, I4.

The membrane I2 separates the fuel chamber I0 from a depression chamber I5, which communicates with the air inlet 2 located at the entrance of the carburetor through a calibrated orifice I6 and a conduit II. Orifice I6 could equaly well be open directly to the atmosphere. Chamber I5 communicates also with a chamber I8 through a calibrated orifice I9. Chamber I8 communicates freely with the venturi 8 through a conduit 20. The conduit opens into the ven-.

turi 8 at 2I in the vicinity of the fuel nozzle 1, that is to say at a point in the venturi where the pressure is approximately the same as at the fuel nozzle 1. The pressure which obtains in the chamber, I8 is therefore approximately the same as the pressure which obtains at the fuel nozzle I. In the chamber I8 is disposed a closed manometric bellows 22 of the aneroid capsule type, the length of which varies in accordance with the pressure obtaining in the chamber I8, to which it is exposed. The capsule 22 is fixed to the end of chamber I8 and controls only the movement of the taperedvalve'member 23 which controls the cross section of the 4 orifice I9 in the same manner as in Figure 1 of the Belgian patent referred to above. Chamber I8 is connected to the chamber I5 not only through the orifice I9, but also by a bypass I45 which has a calibrated orifice I48. The bypass I45 is controlled by a manual valve I46 actuated through lever H1. The valve I46 constitutes the supplemental adjusting member.

When the manual valve is closed, the functioning of the apparatus is identical with the functioning of the apparatus shown in Figure 1 of the Belgian patent, and the richness of the mixture is represented by the curve shown in full lines in Figure 4. When the valve I46 is open, the cross section of the calibrated orifice I48 is added to the cross section of the orifice I9, and the depression transmitted to the chamber I5 is higher. Therefore the mixture delivered to the carburetor is leaner. The richness of the mix ture is then shown by th curve in broken lines I in Figure 4,

In the arrangement shown in Figure 2, instead of the bypass connecting the chamber I8 to the chamber I5, a bypass I49is provided connecting the conduit II to the chamber I5. The bypass includes a calibrated orifice I52 and is controlled by a manual valve I50 actuated by a lever I5I.

When the valve I 50 is open (normal operation), the chamber l5 communicates with the air inlet of the carburetor through the calibrated orifices'I6 and I52 the cross sections ofwhich are added to each other, and it communicates with the venturi 8 of the carburetor through the orifice IS the section of which is controlled by the tapered valve member 23. The richness of the mixture is then represented by the curve shown in full lines in Figure 5, which is similar to the curve in full lines in Figure 4. If the valve I50 is closed, the chamber I5 communicates with the air entrance of the carburetor only through the orifice IS. The depression transmitted to this chamber is then higher, and the mixture delivered bythe carburetor is leaner. The leaning out thus obtained depends upon the depression of the air feed of the carburetor (the atmospheric presnearly the throttle is closed. 0

ness of the mixture as a function of the opening of the throttle is represented by the curve A in dotted lines in Figure 5, whereas for a given altitude, the variation in the richness of the mixture is represented by the curve B. It may be seen that the leaning out of the mixture created by the closing of valve I50 is greater the higher the altitude. Furthermore, the leaning out both on the ground and at, altitude is reater the more The curves shown in Figures 4 and 5 illustrate clearly the differences in function between the apparatus shown in Figures 1 and 2 respectively. Whereas in the apparatus shown in Figure 1, the adjustment of the supplemental adjusting member modified the richness of the mixture in approximately constant proportion, whatever the opening of the throttle and whatever the altitude may be, the adjustment of the supplemental adjusting member in the arrangement shown in Figure 2 modifies the richness of the mixture in a proportion which depends at the same time on the openin of the throttle and upon the altitude.

In Figure 3 is shown an arrangement by which may be obtained results intermediate between the results obtained in the apparatus shown in Figure 1 and the apparatus shown in Figure 2. In the arrangement shown in Figure 3, the chamber I8 is connected to the chamber I5 simultaneously through the orifice I9 and the bypass I45 controlled by the valve I46 the same as the arrangement shown in Figure 1, and th conduit I1 is connected to chamber I5 simultaneously by the calibrated orifice I6 and the bypass I49 controlled by the valve I50 the same as in the arrangement shown in Figure 2. The two levers I41 and I5 I, which control respectively the valves I46 and I50, are coupled by means of a link I53, so that when one of the valves is open the other one is closed. The curves which represent the richness of the mixture in accordance with the positions of the valves I46 and I50, and in accordance with the altitude, are of the same shape as the curves shown in Figure 5, but the curves A and B, which correspond to the open position of valve I46 and to the closed position of valve I50, curve A corresponding furthermore to operation on the ground whereas curve B corresponds to operation at altitude, are less inclined and approach each other more ,closely than in thediagram shown in Figure 5, which represents the operation of the carburetor represented in Figure 2. The curves A and B approach more closely to the curve shown in dotted lines in Figure 4 when the calibrated orifice I 52 in the bypass I49 is smaller relative to the calibrated orifice I48 in the bypass I45.

Although the invention has been described with particular reference to specific embodiments thereof, it is to be understood that the invention is not limited thereto, nor otherwise except in accordance with the appended claims.

I claim:

1. A charge forming device for an internal combustion engine, includin an air supply passage, a throttle therein, a fuel chamber closed by a diaphragm, means for discharging the fuel from said chamber into the passage posterior to the throttle; a suction chamber closed by said diaphragm, a valve connected to said diaphragm for controlling the inflow of fuel to said fuel chamber, a conduit connecting said suction chamber with the passage posterior to the throttle, a valve operably connected to a manometric capsule for controlling said conduit in response to pressures derived from the air supply passage posterior to the throttle, a bypass passage aroundsaid second-mentioned valve, a valve in said bypass passage adapted to be manually controlled from a point remote from the engine, a calibrated restriction in the bypass passage for limiting the maximum effective opening of the lastnamed valve, and a calibrated passage connecting the suction chamber with a source of subchamber, meansresponsive to the. pressures in said air and fuel chambers for variably restricting the fuel inlet, calibrated passages connecting the air chamber to said region of depression and to the induction pipe anterior to the throttle, and automatic means for controlling the relative effective areas of said calibrated passages com-,

prising a valve controlling one of said passages and an expansible capsule responsive to pressures derived from said region of depression for actuating said valve: the combination therewith of a manually operable means for varying the relative' effective areas of said calibrated passages as determined by the automatic means comprising a passage in parallel with one of said calibrated passages, a valve in said passage, said valve being manually operable under substantially all engine operating conditions from a point remote from the carburetor, and a calibrated restriction in said passage for limiting the maximum eifective opening of said valve.

3. A charge forming device for an internal combustion engine, including an air supply passage, a throttle therein, a, fuel chamber closed by a diaphragm, means for discharging fuel from said chamber into the passage, a suction chamber closed by a diaphragm, means responsive to the pressure in said suction chamber for controlling the pressure in the fuel chamber, and means for varying the' pressure in the suction chamber comprising a suction conduit connecting said suction chamber and the air supply passage posterior' to the throttle, a variable restriction in said conduit, means responsive to pressures derived from the air supply passage posterior to the throttle for controllin said variable restriction,

an air conduit connecting the suction chamber with the air passage anterior to the throttle, a calibrated orifice in said air conduit, a bypass passage around said variable restriction, a second bypass passage around the calibrated orifice, and manually operable means for controlling said bypass passages, said manual means being effective to simultaneously decrease the effective cross-section of one of the bypass passages while increasing the effective cross-section of the other of said bypass passages.

J OHAN I LICHTENSTEIN.

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