US2269277A - Carburetor - Google Patents

Description

Jan. 6, 1942- J. LICHTENSTEIN CARBURETOR Original Filed Feb. 5, 1936' m w Tm m m5 T m w% H m [Q M a J, Y B m latented Jan. 6, 1942 I cmm'roa Johan Idchtensteln, Levalloll-l'errct, ma, 'u-

signer to Societe Switzerland Original application February Divided and this application January 312,615. In Belgium Febru- 62,499. 5, 1940, Serial No. ary 8, 1935 Ge'nerale dea Carburateurs Zenith, Geneva, Switaerland,

a corporation of 5, 1936, serial No.

3 Claims. (Cl. 261-69) I have applied for patent in: Belgium, February 8, 1935, now issued as Belgian Patent No. 407,771; Germany, application for patent of addition flied 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 804,023; Italy, February 3, 1936, now issued as Italian Patent 339,760; Poland, application for patent of addi- --tion filed on February 5, 1936; and Czechoslovakia, application for patent of addition filed on February 4, 1936.

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 controllingthe effective cross section of said passage, and a fuel outlet discharging into, said passage posterior to the trary vary within certain limits. 'As a general rule, if'the richness of the mixture is increased,

' the motor isenabled to develop greater power,

throttle. The carburetor is characterized essentially by a movable control member which controls the efiective area of the fuel discharge nozzle, the position of said control member being a function of the absolute pressure obtaining in the mixing chamber of the carburetor posterior I to the throttle and preferably of theabsolute 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 to facilitate the description. A second regulating device influencing the discharge of fuel delivered by the nozzle is provided and is controlled by the throt tle. 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 cornbustible mixture supplied to an internal cornbustion engine need not be an absolutely fixed one, but that this composition may on the conliquid fuel by a" pressure regulator designatedas a whole by the numeral 22.

.but the specific consumption is higher in such case. It is of advantage, chiefly in aviation ca'r-' buretors, to provide means for modifying the richness of the mixture delivered, so as either to get maximum engine power or to diminish the speciflcconsumption. In general, this modification of the richness is made at the will of V the pilot.

The present invention has for its 'objectan arrangement permitting the richness of the combustible mixture to be varied'in carburetors of the type 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 posslbleto control it automatically the same as other organs of the carburetor.

' The description which follows, taken in connection with the appended drawing, will give.

by way of example, aready understanding of several ways of realizing the invention.

Figures 1 to 3 are schematic views, in longitudinal section, of several forms of the invention.

The carburetor shown in Figure 1 comprises 1 a mixture passage it having; an air inlet l2 and a mixture outlet II connected to the motor; The effective cross section of the mixture passage II is controlled by'a throttle ll actuated by means of lever Ii and rod ii.

A fuel nozzle l9, discharging into a venturi posterior to the throttle it, is supplied with The pressure regulator 22 includes a fuel chamber 24 supplied with fuel under pressure through the conduit 26 and orifice 28, The fuel chamber 24 and an adjacent depression chamber ill are separated by a flexible membrane 3! which is connected to a movable valve member 34 controlling the orifice 2|, the arrangement being such that any increase in thepressure within the fuel chamber 2| or-any decrease in the pressure within the adjoining chamber 30 tends to move the membrane 32 upwardly and close the valve 28, 34.

A calibrated orifice 36' in the outlet of fuel nozzle I8 is controlled by a tapered needle attached to one endof an enclosed manometric capsule ll. Capsule III is located in a chamber 42 outside the carburetor body which communieration. Obviously,

the needle 38.. The section of the nozzle outlet 36 is in this way regulated, dependent on the absolute pressure in venturi 20. The other end of the capsule is fixed to a rod 46 which extends through a bushing 48 mounted in the wall of the chamber 42'. The rod 46 terminates in a plate which is regulated by a. tapered needle I06. The

I intermediate chamber I02 communicates with the 50 which is yieldingly urged by a spring 52 into contact with a cam 54 rotatable about an axis I 56 and actuated by lever 58. Cam 54. constitutes that which has been referred to asthe supplemental adjusting member. ver 58 causes a displacement of needle 38 which controls the fuel outlet 36 and consequently permits the mixture proportions to be varied.

. The 'depression chamber 30 of the regulator. 22 connects through passages 60 and 62 with the carburetor air inlet I2 and through passages 60 and 64 with the venturi 20. Passage 64 opens in venturi 20 at a .point 66 where the pressure closely approximates that at the fuel outlet 36.

The connection between chamber 30 and the air inlet I2 is controlled by a calibrated orifice 68 while the connection between chamber 30 and ve uri 20 is controlled by calibrated orifice 10. The effective cross section of orifice I is regulated by' a tapered needle 12 passing through guide bearing 14 and connected mechanically-- to operating lever I of the throttle valve I4. The depression transmitted to chamber'30 and consequently the pressure in fuel chamber 24 are thereby. regulated in accordance with theopening of the. throttle valve.

\ For any given position of lever 58, capsule 40 is more extended the lower the absolute pressure at the venturi 20, and consequently in chamber 42; consequently the cross section of orifice 36 is smaller the lower the pressure in the venturi 20. The needle 12 is withdrawn from the orifice as the throttle is closed. The ori- The operation of leventuri 20 by annular space I08 surrounding the shaft of needle I 06. The intermediate chamber I02 communicates also with, the carburetor air inlet I2 through orifice I 10 regulated by needle [I2 and passages H4 and H61 An air chamber II8 positioned adjacent the fuel chamber 24 and separated therefrom communicates with the air inlet I2 through passages I20 and H6. Needle I I2 passes through guide bearing I22 and is controlled mechanically by lever I5 secured to the shaft of the throttle valve l4. The air passing. through orifice IIO enters the chamber I02 and emulsifies the liquid fuel delivered by orifice I04. The emulsified fuel enters the venturi 20 through the passage I08. Needle I06 is attached to capsule 40 located in' chamber 42 Chamber 42 connects with the venturi 20 through the annular space 44 provided around the needle I06. Capsule 40 elongates or contracts depending on the variation of pressure in venturi 20 and its variations in length cause the displace- I06 which regulates the fuel as previously explained in'connection with Figure 1.

In the embodiment shown in Figure 3 the fuel is delivered to the venturi 20 by tube I sliding in a guide I32 fixed in the carburetor body. The

fice 10 therefore has the largest effective opening when the throttle is closed, at which time a high depression exists posterior to the throttle and consequently at point 66 the entrance to passage 64. hence the fuel pressure in chamber 24 therefore increase as the throttle is opened. The shapes of the tapered needle 38 and the needle 12 are so predetermined that-the richness of the mixture delivered by the carburetor is correct for all positions of the throttle and for operation at various altitudes.

When the lever 58 is in the position shown in solid'lines in Figure l the mixture delivered may be considered as corresponding to normal operation. If lever 58 is brought to the position represented in dotted lines in Figure 1 the needle 38 is moved toward the orifice 36 and consequently decreases the effective cross section thereof and diminishes the discharge of fuel. The second position of lever 58, shownin broken lines in Figure 1, may be considered as corresponding to lean operation, which means economical opthe expressions normal mixture" and lean mixture" have here only a relative significance; they simply mean that in one case the mixture contains a proportion of fuel greater than in the other case, without signifying the absolute value of the ratio of the quantity of fuel to the quantity of air in the mixture.

In the embodiment shown in Figure 2 intermediate chamber I02 receives fuel from the fuel chamber 24 through orifice I04 the section of end I34 of tube I30 receives a shaft I36 which passes through an air tight packing I38. movements of tube I30 are controlledby the throttle valve I4 by means of throttle lever I5. link I40, and lever. I42 pivoted on axis I44, link I46 and shaft I36. Tube I30 is pierced by a specially shaped slot I48 and has in addition in the vicinity of end I34 holes I50 having a sufficiently large section to permit tube I30 to be freely supplied with fuel. The portion of .the

tube I30 having the holes I50 is located in a chamber 152 connected through passage I54 to the fuel chamber 24 of the pressure regulator 22,

the air chamber I I8 of which communicates fre ly with the air inlet I2. through passage I56. Slot I48 of tube I30 is in this way supplied with fuel by the pressure regulator by means of passage I54, chamber I52, holes I50 and tube I30 itself.

On the other end of tube I30 slides a sleeve .I58 provided with cover I60. Sleeve I58 passes throughopening I62 in the wall of the vcarbu'retor body and there exists between the sleeve I58 and opening I62 an. annular space which permits a free connection between venturi 20 and a chamber 42 situated outside of the body.

In chamber 42 is mounted a sealed manometric capsule 40. The capsule 40 carries at one end a rod 46 which passes through a guide fixed at one end of chamber 42 and which has on its end a plate 50 held against cam 54 by spring 52. Cam 54 is operated by means of lever 58 aroundaxis 56.

The movements of end I64 of capsule 40 which are caused by the variation of pressure in chamber 42 are transmitted to sleeve. I58 by means of lever I66 pivoted upon an axis I68. Lever I66 contacts through a projection I10 with end I64 of capsule 40 and with cover I60 of sleeve I58 through cam surface I12. A compression spring I14 maintains the cover ofthe sleeve, the lever, and the capsule in contact with each other. The

The

pivoting during fixed guide I32 terminates in a circular edge I18.

"while the moving sleeve I58 terminatesin acirsides of which are the circular edges I18 and I18 while the non-parallel sides are'the edges of slot I48.

In operating lever 58 the whole capsule 40 is 277 3 ated from a point remote from the engine, a

' member connected to said bellows and engaging displaced and ,these movementsaretransmitted to sleeve I58. In this manner the size of the slot formed between the edge I18 of sleeve I58 and the edge I16 of guide I32, and consequently the section of fuel outlet I88, are varied. The operation bf lever 58 thus permits the changing of the mixture proportions. v

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

I claim:

- 1. In a carburetor for an aircraft engine, an

air supply passage, a throttle therein, a fuel conduit discharging in the passage posterior to the throttle, a fuel chamber supplying fuel to the conduit, means including a movable member for varying the effective cross section of the fuel conduit, automatic means for controlling the richness of the mixture comprising a sealed manometric capsule subjected to pressures derived from the induction passage posterior to the throttle for operating said movable member, and manual means operable independently of the throttle from a point remote from the carburetor substantially all conditions of engine said cam, and a spring urging said member into engagement with said cam.

2. The invention defined in claim 1 together with means for varying the pressure of the fuel in the fuel chamber comprising a variable pressure chamber, connections from the variable pressure chamber to the air supply passage respectively anterior and posterior to the throttle, throttle operated means for varying the relative effective cross sections of said connections to thereby vary the pressure in the variable pressure chamber, and means responsive to the pressure in the variable pressure chamber for controlling the infiowof fuel to the fuel chamber.

3. A charge forming device comprising an induction pipe, flow restricting means including a throttle in said pipe, a fuelchamber having a fuel inlet, an air chamber, a connection from said air chamber to the induction pipe anterior to said flow restricting means, means responsive to the pressures in the air and fuel chambers for variably. restricting the fuel inlet, a fuel conduit leading from said fuel chamber and discharging in the induction pipe in a region of depression created by said flow restrictingmeans, automatic means for controlling the richness of the mixture including a valve for varying the effective cross sectional area of said fuel conduit and an expansible member responsive to the pressure in,

said regionof depression for actuating said valve,

1 and manual means for varying at will the richness operation for moving the sealed capsule as a unit to thereby vary at'the will of the pilot during periods of operation the richness of the mixture determined by the automatic means comprising a pivotally mounted cam having an operating lever connected thereto. and adapted to be actuofthe mixture determined by said automatic means comprising an eccentric member having a manual control lever operable independently of the throttle from a point remote from the device under substantially all conditions of operation, and means. interconnecting the eccentric.

and expansible members varying the position of said expansible member as a unit upon movement of said control lever.

' ,JOHANHCHTENSTEIN.

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