US2619334A - Carburetor for aircraft engines without compressors - Google Patents

Description

Nov. 25, 1952 R. H. nssn-zn CARBURETOR FOR AIRCRAFT ENGINES WITHOUT COMPRESSORS 3 Sheets-Sheet 1 Filed April 2, 1949 Iuwsyrae aowflfn sul B L001? Co-en, qaukd a 40:11am

Rr-rrs CARBURETOR FOR AIRCRAFT ENGINES WITHOUT COMERESSORS Filed April 2, 1949 3Sheets-Sheet 2 Nov. 25, 1952 R. H. TISSIER CARBURETOR FOR AIRCRAFT ENGINES WITHOUT COMPRESSORS Filed April 2, 1949 3 Sheets-Sheet 3 Patented Nov. 25, 1952 CARBURETOR FOR AIRCRAFT ENGINES WITHOUT COMPRESSORS Roger H. Tissier, Paris, France, assignor to Societe Nationale dEtude et de Construction de Moteurs dAviation, Paris, France, a French pany Application April 2, 1949, Serial No. 85,142

In France April 2, 1948 4 Claims.

The carburetors for aircraft engines without an air compressor should meet certain requirements:

1. For the comparatively high air inlet pressures. (on take 01f, or rated engine running), that is near the atmospheric pressure at ground level, the air-gasoline mixture provided by the carb retor should be rich.

2. For the cruising load, the pilot should be able to obtain either a mixture giving an economical consumption, or, during a, temporary period of strenuous working of the. engine (for instance during climbing) a comparatively rich mixture.

3-. Finally, it may be useful, chiefly in the case of engines without air compressor, to. be able to obtain the maximum power ofthe engine at any altitude, that is to pass from the economical mixture to the mixture corresponding to the maximum power.

If the carburetor is provided for manual altimetrical correction, these requirements may be achieved at the cost ofimposing an additional duty on the pilot. Moreover, this may lead to overstrain of the engine in case-thepilot, lacking experience in handling the control, sets the latter ina position corresponding to too weak a mixture.

If the carburetor is arranged for automatic a1- timetric correction, it is convenient to be able to use asupplementary manual control in order to pass. from the economical mixture to the maximum power or climbing mixture.

lnotherwords, in an engine without air compressor, under otherwise equal conditions, the downstream pressure with respect to the butterfly. or throttle-control depends on the altitude and on the pressure-loss dueto the butterfly position.

The present invention has for its object to provide an adjusting device to obtain automatically the resultant of boththese factors on the carburetor mixture and which can be conveniently combined with a manual correcting means available to the pilot, thus providing a richness suitable toeach admission pressure, both at altitude and ,on the ground, without requiring anadmissionipressure diaphragm.

Thisdevice-comprises a linkbetween thethrottle-lever (or the butterfly) and the altimetrical adjusting; needle ,or valve; operated-by means of the altimetrical-control box.

Other objects and advantages of the. invention will. be; apparent during the course-of the following" description.

In the. accompanying drawing forming a, part of; this application andin which like numerals 2 are employed to designate like parts throughout the same,

Figures 1 to 3 are diagrammatic cross-sections of three embodiments of the invention which may be applied to every aircraft engine without compressor, whatever its principle.

These embodiments permit automatic enrich ment for high admission pressures at ground level, as well as for full-throttle running up to the altitude corresponding to the admission pressure necessitating enrichment. Moreover, they allow, for an operating condition other than high admission pressure conditions, automatic operation either With a weak mixture or with a rich one.

In the drawings, for convenience, the butterfly or air throttle It] has been separated from the carburetor whose choke tube or venture forming the mixing space is in Illa, but obviously, the air throttle is located as usual either in front, or behind this venture. The engine is in M; it sucks air through the tube 2 and venture Illa. The atmospheric air is in A.

In the embodiment shown in Fig. 1 an emulsifier I receives the liquid fuel as usual from a constant level container, not shown, which is connected to the emulsifier through a duct Ia. Said emulsifier receives further air through a channel Ib originatin at I-c upstream with re' spect to the nozzle Illa, so that the pressure of said air is the atmospheric one.

The exit. Id of said-emulsifier being connected to ports Illb provided in therest-ricted zone of the venturi. Illa, the. suction generated in said zone by the air stream is transmitted through said ports to the said exitof the emulsifier. Consequently air and fuel are sucked in through said emulsifier and form a primary mixture (emulsion) which is finally admitted through ports I U into the air. flowing. through nozzle Ilia.

Carburetors of this kind are well known. is also known to regulate the richness of the final mixture in nozzleI Ga in the followingmannerz.

A channel 9a communicating with port I'c'and channel Ibis connected with. the exit Id of the emulsifier through a calibrated. aperture controlled. by a needle-valve 4 controlled in its turn by a pressure responsive box 5,- the outline of this needle 4 being adapted toralter the area of flow section between the wall of the aperture or seat 3 and the needle 4, according to theaa'ltitu'de'.

The, proposed improvement comprises the following arrangements:

The altimetrical adjusting: needle-valve 4' isprovided with a cylindrical extension 6on which a sleeve 1 freely slides, its displacement being controlled by a lever 8. The needle is hollow and pierced with ports 9, at a, convenient height, on its cylindrical portion and also with ports 9b under the seat 3. Thus, through the duct 9a, through ports 9 whose sizes are predetermined during adjustment and through ports 9?), a connection is established between the air-channel 2 and the exit of the emulsifier I, thus causing a drop in the suction over the emulsifier, and hence, a leaning of the mixture.

According to its position, the sliding sleeve I covers or uncovers the calibrated ports 9.

The control of the position of this sleeve 1 is effected automatically by the rotation of the butterfly H]. For this purpose, a cam H is keyed to the axle We of butterfly I0, in such a way as to turn at the same time as that butterfly when the throttle-control is operated. On this cam is applied a roller 12a carried at the end of a connecting rod l2 hinged on lever B. This lever pivots about a fixed point 8a and is submitted to the action of a spring so which applies permanently the roller iEa on the cam ii. The connecting rod i2 is guided on the butterfly axle by means of a slot ifid which this axle crosses. In the drawing, cam H as well as connecting rod [2 are shown inside the suction-duct of the engine. In practice, these members are outside this duct, cam H being keyed to an extension of the butterfly axle lilo.

The device described causes the sleeve 1 to move along the extension 6 of the needle 4 when the butterfly or throttle-control is operated, the position of sleeve 1 depending therefore on that of the butterfly.

During operation at ground level and starting with a certain opening of the butterfly ii), the sliding sleeve 1 closes ports 9 of the adjusting needle 6; the maximum richness is achieved when the ports are entirely closed (the butterfly is wide open).

If it is now assumed that the aircraft takes off with the butterfly wide open, then as the aircraft climbs, the altimetrical-control diaphragm lengthens and causes the ports 9 to be uncovered, thus lowering progressively the richness while the inlet pressure decreases.

Thus, at ground level and at altitudes, a mixture proportional to the inlet pressure is achieved.

Moreover by acting on lever 8 through a manual control, not shown, connected to the end 81) of lever B, it is always possible to set sleeve 7 at its upper posit-ion, whatever the altitude, so that ports 9 are closed and the mixture enriched.

It is thus possible, by means of this manual control to feed the engine either with a weak mixture (economic cruising rating), or with a rich one (climbing, maximum power in altitude, etc.)

The embodiment shown in Fig. 2 is of the type with altimetrical adjustment through decrease in pressure above the level of the fuel in the float chamber M which supplies the jet l. The device is similar to the previous one and the operation identical, but the adjustment is achieved by connecting the neck of the venturi [0a to the upper part of the chamber I4 through duct 9a, seat 3 controlled by needle 4 and ports 9 controlled by sleeve 1.

Over the fuel in chamber 14, a pressure less than atmospheric and determined according to the altitude by the position of the altimetrical adjusting needle 4, is thus created.

The third embodiment shown in Fig. 3 is of the type with altimetrical adjustment by reducing the flow of gasoline, the adjusting needle 4 operated by the pressure responsive box 5 actin on the gasoline flow supplying the jet 1 from container l4 through ports 3 and 9 and duct l5.

On this needle is arranged the sliding sleeve 1 operable to cover or uncover one or more ports 9 connecting, through the inner cavity of needle 4, container I4 and duct l5 of the emulsifier. The device is such that these ports 9 are wholly or partly uncovered for high air inlet pressures, while they are covered for low air inlet pressures owing to the action of the pressure responsive box 5.

As above, it is further possible to arrange a manual control for operation with either weak or rich mixtures.

The advantages of the invention are as follows:

1. Automatic regulation of the richness for high air inlet pressures with a single atmospheric pressure responsive box, the action of which is combined with that of sleeve 1 and ports 9 according to the aperture of the air throttle, enabling to obtain simultaneously the altimetrical adjustment and a richness varying according to the air inlet pressure.

2. Possibility to operate automatically with a very economical adjustment (weak mixture).

3. Possibility to have the maximum engine power available at altitudes by the operation of the primer (rich mixture-ratio).

4. Possibility to increase the richness for high power ratings required from the engine (climbing for instance).

What I claim is:

1. In a carburetor for an aircraft engine without compressor having a movable air throttle and a mixing space, two valve devices arranged in parallel relationship to control independently from one another the fuel supply to the mixing space, one of said valve devices being adapted to reduce the fuel supply in response to a decrease in atmospheric pressure and conversely, while the other valve device includes two valve members arranged to move independently with respect to one another, one of said members being adapted.

to reduce the fuel supply in response to a decrease in atmospheric pressure and conversely,. and means for connecting operatively the othermember to the throttle, said means being adapted to move said other member towards its fuel sup-- ply increasing position when the throttle is open and conversely.

2. In a carburetor for an aircraft engine without compressor, having a movable air throttle and a mixing space, a regulating device for the fuel supply to said mixing space comprising a fuel supply control passageway, a stationary seat provided in said passageway, a movable needle the outer surface of which is adapted to cooperate with said seat in order to vary the cross-section area of said passageway, means sensitive to the atmospheric pressure operatively connected to said needle and adapted to move it with respect to said seat so as to reduce the fuel supply in response to a decrease in atmospheric pressure and conversely, said needle being provided with an internal cavity and with lateral ports adapted to connect said cavity respectively with the ports of said passageway located on each side of said seat so as t form a second fuel supply control passageway arranged in parallel relationship with respect to the first-named passageway. a sleeve slidably mounted on said needle so as to control its ports on one side of said seat, and means mechanically connecting said sleeve to said movable air throttle, said means being adapted to move said sleeve with respect to the corresponding needle ports towards the fuel supply increasing position of said sleeve when the throttle is open and conversely.

3. In a carburetor for an aircraft engine without compressor, having a movable air throttle and a mixing space, an emulsifier the exit of which is connected to said mixing space, an air passageway connected to the atmosphere and to the exit of said emulsifier, two valve devices arranged in para1le1 relationship in said air passageway to control independently from one another the cross-section area of said air passageway, one of said valve devices being adapted to increase the cross-section area of said air passageway in response to a decrease in atmospheric pressure and conversely, whil th other valve device includes two valve members arranged to move independently with respect to one another, one of said members being adapted to increase the cross-section area of said air passageway in response to a decrease in atmospheric pressure and conversely, and means for connecting operatively the other member to the said throttle, said means being adapted to move said other member towards its cross-section area reducing the position when the throttle is open and conversely.

4. In a carburetor for an aircraft engine without compressor, having a movable air throttle and a mixing space, an emulsifier the exit of which is connected to said mixing space, an air passageway connected to the atmosphere and to the exit of said emulsifier, a stationary seat provided in said air passageway, a movable needle the outer surface of which is adapted to cooperate with said seat in order to vary the cross-section area of said air passageway, means sensitive to the atmospheric pressure operatively connected to said needle and adapted to move it with respect to said seat so as to increase the cross-section area of said air passageway in response to a decrease in atmospheric pressure and conversely, said needle being provided with an internal cavity and with lateral ports adapted to connect said cavity respectively with the ports of said passageway located on each side of said seat so as to form a second air passageway arranged in parallel relationship with respect to the firstnamed passageway, a sleeve slidably mounted on said needle so as to control its ports on one side of said seat, and means mechanically connecting said sleeve to said movable air throttle, said means being adapted to move said sleeve with respect to the corresponding needle ports towards the ports opening position of said sleeve when the throttle is open and conversely.

ROGER H. TISSIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,802,321 Mabee et a1. Apr. 21, 1931 2,203,858 Booty June 11, 1940 2,212,101 Kratzer Aug. 20, 1940 2,216,677 Schuttler Oct. 1, 1940 2,291,048 Lichtenstein July 28, 1942 FOREIGN PATENTS Number Country Date 109,099 Great Britain Aug. 31, 1917

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