US2203858A - Carburetor - Google Patents

Description

June 11, 1940. P. c. P. BooTY CARBURETOR Filed Nov. 3, 1938 Patented June 11, 1940 UNITED sTATEs oAaBURE'roR e Philip C. P. Booty, Chicago, Ill., assigner of onethird to William E.

ONeil and one-third to Leroy D. Winters, both of Evanston, Ill. `Application November 3, 1938, Serial No. 238,626'

2 Claims.

My invention `relatesto an improved fuel-air mixture control for` a constant vacuum type of carburetor usually associated with an internal combustion engine, one form of this type of carburetorbeing illustrated and described in United States Letters Patent No. 1,586,601, issued June 1, 1926.

e One of the objects of my invention is to provide a fuel-air mixture control which is automatic in operation for a carburetor of this type.

It is `another object of my invention to provide al control of this type which `operates automatically to produce the correct fuel-air mixture upon a change of temperature of the air used in Carburation.`

Itis also an object of my invention to provide a control of thistype which in order to produce the `correct fueleair `mixture is adapted to compensate automatically with a change of temperature of the` fuel for a change of viscosity thereof and` hence for a change of iiow resistance thereof in the conducting means of the carburetor.

Itis still another object of my invention to provide a control of this type which is of simple construction `and `which may be economically manufactured. e It is a further object of my invention to improve `controls of `this type in sundry `details Hhereinafter pointed` out.` The preferred means by `which `I have accomplished my several objects are illustrated `in the drawing and are hereinafter specifically described. That which `I believe tobe new and desire to cover by Letters Patent is set forth in the claims. i In the drawing- I Fig. l is a vertical sectional view of a carburetor embodying the principles oi my invention, this view `illustrating the movable parts of the `carburetor in their lowermost positions;

Fig.` 2 is a sectional view of the lower portion of the carburetor taken on line 2-2 of Fig. l;

Fig. 3 is a sectional View taken on the line 3 3 of Fig. 1; and e I e Fig. 4 is an enlargedlongitudinal sectional View of the lower portion of the metering pin.

Referring now to the several figures of the drawing, in `which corresponding parts are indicated by the same reference characters, Ill indicates a tubular carburetor casing closed at its upper end by a cap Hand provided with a delivery ductIZ leading from the side of the casing atan intermediate point. At the lower or inlet end ma of the casing an-d attached to the inter-' chamber I 4 and having an air entrance duct Iiy A float chamber I6 is formed by the tubular casing portion I'I and the bottom portion I8, and is supported by an arm` I b, the parts preferably being `cast integral with each other and separate 5 from the casing I0 and the auxiliary casing I3. The `parts Il), I 8b and I3 may be secured together i by any desired means.

The fuel for the carburetor is supplied through the fuel pipe I9 which is in threaded engagement 10 with a hollowmernber 20 in a side opening 2i: thereof. The hollow member 2d is positioned over a fitting 22 and its upper end 20a. is held in tight abutting engagernent` therewith by a cap nut 23 which `is in threaded engagement with` the fitting. 15 The fitting 22 is screwed into the bottom portion I8 ofthe float chamber I6, the tting being provided with a duct 2d and transverse openings 25, and being surrounded by a iilter screen 26. `In the float chamber I6 I have provided an inlet tube 2l which is screwed at its lower end into the fitting 22.` The inlet tube 2l is` slotted at 28 to permit theentrance of fuel and is provided with a seat 29 fora needle valve 30 which is 4supported by and projects downwardly through the tube.` Loosely secured to the needle valve jill is the usual float 3| which is composed of cork or similar material.

. A fuel supply duct 32 in the arm `Ilb` communicates withthe float chamber I6 and the interior of a fuel nozzle 33 which projects into the interior of thecasing 'Iii terminating in an oriiice 33a. A plug 34 closes an opening in the fuelv passage `made therein for convenience in drilling. The fuel nozzle 33 is fixed relative to the casing ID by being threaded into the arm Ib.

In the intake chamber I4 I have provided Va thermostaticmeans which comprises a header 35 threaded into the armv 81) and thus being xed relative thereto, a second header 36, and a bellows .or sylphon tube` 3T therebetween. In the compartment 38 formed by the headers and the bellows is a suitable thermo-expansive agent such, for example, as ether `or a mixture of ether and other alcohols, which expands and contracts with changes of temperature. The header 36 is connected by means of tie rods 39 with a cone member 40 which is positioned in the inlet end Illa of the casing IU over and slidable with respect to the nozzle 33. Inthe arrangement shown, the header '36 is fixed to a cross bar lil which is fastened by means of nuts Ma on the lower portionsof the` rods 3S. The upper ends of the rods 39 are threaded into the cone member 4i). The cone member' 40 is" disposed with its larger end as to engage the upper end of a metering pin 58 towards the air intake chamber |4, the arrangement being such that a movement of the headen 36 and the rods 39 relative to the casing ID causes the cone member 40 to slide upwardly or down-- wardly on the nozzle 33.

Slidable within the casing ID is an air valve 42 comprising at its lower end an annular piston 43, surrounding the cone member 40 and'serving to close the space between the cone member and the casing wall when the carburetor is in starting condition as shown in the drawing, a piston 44 at its upper end, and an intermediate connecting structure 45. On the rods 39 adjacent the bottom portion of the cone member 49 are washers 46 which project underneath the piston 43 andl support the air valve 42 when the carburetor is idle or inoperative. The washers 46 are held in position by nuts 41 on the' rods 39. The annular piston 43 is preferably provided with a plurality of peripheral grooves 48 for the purpose of preventing leakage of any substantial amount of air therearound. 'I'he upper piston 44 may be similarly grooved, although the matter of leakage past this piston is not so important, for reasons hereinafter pointed out. The connecting structure 45 between the pistons 43 and 44is preferably out away so as to leave only a plurality of connecting arms or strips 48. The'strips and the associated pistons are held against rotation by a pin 49 carried by the casing which extends into a vertical slot 50 in one of the strips 48.

The upper piston 44 is provided with a passage and a threaded opening 52 directly thereover and communicating therewith. In the opening 52 is a pointed valve 53 having a groove 54 therein. The piston 44 is also provided `with a second passage 55 and a second threaded opening 56 directly thereover and communicating therewith. A removable screw plug 51 is vprovided in the opening 56 but is not of such length which is suspended from the piston 44 by a transverse pin 59 which passes through the metering pin and rests on shoulders 56a-forming the bottom of the opening 56. The arrangement-is such that the metering pin, which has a working fit in the orifice 33a, has a freedom of movement relative to the piston 44. As shown most clearly in Figs. 3 and 4, the metering pin 58 is provided with a plurality of fuel openings or grooves 6D which are of uniform width and which uniformly increase in depth toward the lower end of the pin. Y'

The output of the fuel-air mixture .from the carburetor is controlled, as is usual, bya throttle y valve 6| of the butterfly type.

In the starting and` operation of an engine equipped with the carburetor, a suction is created and maintained therein causing a liftingvof the air valve 42 including the piston 43 with respect to the cone member 46 and a corresponding liftthat the eiective size of the fuel outlets betweenV the pin 58 and the nozzle orifice 33a, increases substantially in proportion to the rise of the pin 58 relative to the nozzle 33 and to the rise of the piston 43. As the throttle valve 6| is opened an increased suction is created in the carburetor with the result that both the air valve 42 and the fuel valve comprising the pin 58 and the orifice 33a are opened further and an increased amount of fuel and air is drawn through the casing I0, the richness of the mixture remaining uniform, since the ratio between the size of the air opening and the size of the fuel opening is constant. The richness of the mixtureis also uniform for the same reason when the throttle valve 6| is being closed, causing movements of the members in a reverse direction. n

When the air used in carburation changes in temperature, it is, of course, desirable that the fuel-air mixture delivered to the engine be changed in order that the engine may operate satisfactorily. 'I'he thermostatic means in the air intake performs this function automatically. If the temperature of the air taken into the carburetor through the air intake I5 is too cold for the `desired efficient operation, the thermo-responsive agent in the compartment -38 contractsY or decreases in volume and the lower header 36 rises, which causes the cone member 48 to rise through the action of the rods 39 and cross bar4l. Under such conditions, if the engine is not running, the piston 43 will be automatically lifted with the cone 40 by the `washers 46 to a height determined by the existing temperature, and the connecting arms 48, the piston 44, and the metering pin 58 will also be lifted.A Thetotal effective Afuel opening between the metering pin 58 and its nozzle, therefore, will be increased; and when the engine is started and the piston 43 is raised by the suction of the engine, the ratio of the fuel opening to the air inlet will be greater. Under operating conditions, the lower piston 43 floats in a raised position, allowing air to pass between that piston and the cone member 49.` If the temperature of the air entering through the air intake rises, the action of the thermostatic means causes the cone member ,to drop, and the lower piston 43 drops a corresponding amount and the amount of air flowing into the carburetor is substantially the same. This drop in the piston 43, however, causes a drop in the metering pin 58 relative to the nozzle A33, producing a lesser effective fuel opening therebetween. Since the volume of air flowing into the carburetor is substantially the samebut the volume of fuel is less, the richness of the fuelairmixture flowing through the delivery duct is decreased. With a drop of temperature of the,` air entering the air intake, the thermostatic means contracts, causing the actions of the cone member and the associated members to be 4the reverse of those just described. Y y

Since the cone member 40 is rigidly secured to the lower header 36 of the thermostatic device, the cone member 40 only moves away from or towards its seat on the arm |81)- as the thermoresponsive agent in the compartment 38 contracts or expands due to temperature changes. Upon the engine and the air drawn into, the intake of the carburetor reaching the desired operating temperatures, the thermo-responsive agent in the compartment 38 will have expanded to such an extent that the cone member 40 will be held tightly against its seat on the arm |819', and under such'conditions thesuction of the engine on the cone member 40 is not nearly enough to pull the cone member 46 away from its said seat. However, when the temperature of the air in the intake decreases substantially, the thermoresponsive agent in the compartment 38 con- 75 tracts with the result that the lower header 36 rises thereby raising the cone member 4U and maintaining the desired fuel air ratio.

Due to the fact that the fuel is more viscous than air, its flow does not respond as readily to variations in suction of the engine as that of the air, and, therefore, it is desirable to provide means whereby the responsiveness of the air valve changes the volume of the compartment in the upper portion of the casing formed between the i cap Il and the upper face of the piston 44 and il U ` `ual adjustment of the parts by the operator of makes it necessary that a certain amount of air therein pass in or out in some way. By screwing down the valve, the eifective size of the passage through the piston is decreased, the time in which an amount of air may pass therethrough to or from the compartment is increased, and the responsiveness of the air valve to variations in suction is retarded. Inasmuch as a certain amount of leakage through or past the piston is required to retard movement of the air valve, a close t of such piston in the `casing lll is` not essential since in adjusting the valve 53 the leakage past the piston will always be taken into consideration.

The upper piston `d4 also performs another important function in addition to that of retarding the responsiveness of the air valve 42, The bottom pressure face of the piston 44 is opposed to the top pressure face of the piston 43 and the pressure face of the former is greater than` ,that ofthe latter as shown in the drawing. In case of a back-fire, the pressure thereof does not drive the lower piston downwardly against the washers 46 with a possibility of destruction of any of the members, but it rather exerts a greater pressure on the pressure face of the upper piston M due to its greater size with the result that the pistons and their connections are slightly lifted.

My improved thermostatically controlled carburetor provides an arrangement in which the delivered fuel-air mixture is automatically maintained in the correct ratio during temperature changes and without the necessity for any manthe engine.

The operation of the thermostatic means in the air intake chamber is `positive and dependable under all temperature variations, its operation notbeing adversely affected by the pressure of the inrushing air or the suction of the engine. The carburetor is` simple in construction, economical to manufacture and easy to install, the `air intake casing being turnable on the main casing for ready attachment to the exhaust manifold of a motor.

While I prefer to employ the form of arrangement as shown in the drawing and as above described, it is to be understood that I do not limit my invention to the form as shown except so far as the claims may be so limited, it being understood that changes` might be made in the form and arrangement of parts Without departing from my invention.

I claim:

1. In a carburetor for an internal combustion engine, the combination of a casing, an air intake chamber communicating with said casing at its inlet end, a cone member adapted to close partially the passage between said casing and said chamber, a fuel nozzle member extending through said cone member and projecting into said casing, one of said members being movable relative to the other and to said casing, the other of said members being fixed relative to the casing, said movable member being adapted to seat against a fixed portion of the casing, an air valve adapted to close substantially the remainder of said passage, said valve being supported by said cone member when the engine is not running and opening away therefrom under the suction of the engine when it is operating, a metering pin having tapered grooves therein extending into said nozzle member and connected with said valve, and thermostatic means in said chamber ycomprising two headers with a bellows therebetween and a thermo-expansive body in the compartment formed by the headers and the bellows, one of said headers being fixed relative to the casing and the other of said .headers being rigidly connected with said movable member, said thermostatic means under normal operating temperature of the air in said chamber holding the movable member against its said seat, the arrangement being such that movement of said second named header in response to a decrease of temperature in said chamber causes a movement of said movable member away from its said seat and a further outward movement of said pin relative to the nozzle member.

2. In a carburetor `for an internal combustion engine, the combination of a casing, an air intake chamber communicating with said casing at its inlet end,4 a cone member adapted to close partially the passage between said casing and said chamber, a fuel nozzle extending through said cone member, said nozzle being xed relative to said casing, said cone member being movable with respect to the nozzle and adapted to seat against `a fixed portion of the casing, an air valve adapted to close substantially the remainder of said passage, said valve being supported by said cone member when the engine is not running and opening away therefrom under the suction of the engine when it is operating, a metering pin having tapered grooves therein extending into said nozzle and connected with said valve, and thermostaticmeans in said chamber comprising two headers with a bellows therebetween and a thermo-expansive body in the compartment formed by the headers and the bellows, one of said headers being xed relative to said casing and the other of said headers being rigidly connected with said cone member, said thermostatic means under normal operating temperature of the air in said chamber holding the cone member against its said seat, the arrangement being such that movement of said second named header in response to a decrease of temperature in said chamber causes a movement of said cone member away from its said seat and a further outward movement of said pin relative to the nozzle.

C. P. BOOTY.

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