US2899185A

US2899185A - Carburetor x

Info

Publication number: US2899185A
Authority: US
Publication date: 1959-08-11
Anticipated expiration: 1976-08-11

Description

E. RECTO R Aug. 11, 1959 CARBURETOR Filed April 26, 1957 3&9

INVENTOR. /V06// #5670? JTTOPAZ'Y CARBURETOR Application April 26, 1957, Serial No. 655,332

Claims. (Cl. 26172) This invention relates to a carburetor for internal combustion engines and more particularly to the control of fuel flow in relation to airflow in a carburetor which includes a single fuel jet between throttle and manifold.

Heretofore the efficiency of carburetor operation has been substantially influenced by variations in atmospheric pressure and temperature. In cold climates considerable choking of the carburetor has been used to maintain a rich enough vapor, and this as well as other mechanical expedients, relying upon moving parts, has been generally used to maintain a satisfactory fuel and air mixture. In vacuum lift type carburetors, which operate without a fuel pump between main fuel supply and float chamber, excessive vacuum in the float chamber has sometimes caused fuel to boil and so forced vapor through the fuel jet in varying amounts depending upon atmospheric temperature. Poor vaporization of fuel and variation in the ratio of fuel to air at different engine speeds have led to inefliciency and less than ideal fuel economy.

Therefore, it is an object of this invention to provide more efficient carburetion and greater fuel economy in relation to increases in power than have heretofore been known. 1

It is also an object of this invention to overcome the objectionable aspects of boiling fuel due to vacuum in vacuum lift carburetors.

Another object of this invention is to provide a substantially uniform mixture of' fuel and air at all atmospheric pressures and temperatures.

A further object of this invention is to provide a means for maintaining a proper mixture of fuel and air at all engine speeds without'the use of moving parts.

These and other objects of the invention are set forth in detail in conection with the accompanying drawing in which like reference characters designate like parts and in which:

Fig. 1 is a partially cut-away elevation of a carburetor showing the arrangement of the elements of this invention;

Fig. 2 is a partially cut-away plan view of Fig. 1 along the line AA;

Fig. 3 is a partially cutaway detail elevation of the fuel jet of Figs. 1 and 2 shown enlarged;

Fig. 4 is a plan view through the line BB of Fig. 3.

According to a preferred embodiment of the invention as shown in Fig. l of the drawing, a float or fuel chamber 301, provided with an annular float 302 is vertically traversed by an air passage 303 in the form of a venturi which at its lower end is connected to the engine manifold at a junction 304. At its upper end the venturi passage opens to the atmosphere through a throttle valve 305 which is externally controlled to regulate the speed of the engine by varying the atmospheric air supply to the carburetor.

Within the venturi air passage between the throttle 305 and the manifold junction 304 at least one fuel jet 306 is axially mounted with a radially symmetrical orifice in a horizontal plane above the highest level of the States Patent 0 'ice .2. fuel'307 in the float chamber 301. The range of the level of the fuel 307 is regulated by the ring float 302 by Well known means which may be those described in U.S. Patent No. 2,719,707 of E. Rector. The fuel jet 306 is connected with the fuel 307 in the fuel chamber 301 by a duct or conduit 308.

A series of perforations or holes 309 in the form of short ducts connects the interior of the air passage with the upper interior of the fuel chamber 301 above maximum fuel level. Within the venturi passage these are all at the same elevation as the orifice of the fuel jet 306 and slope downwardly into the fuel chamber. The preferred angle is about 22 but may conveniently vary from about 10 to about 30. Choice of the angle of the ducts 309 depends on the desired ratio of pressures between fuel chamber and fuel jet. The pressure at the jet 306 and the rate of fuel flow is generally increased by making the ducts more vertical.

The fuel jet 306 may conveniently be in a mushroom or umbrella form as shown in the relatively enlarged views of Figs. 3 and 4. The vertical stem 312 carries at its core a duct 308 which carries fuel 307 from the fuel chamber 301 to the nozzle orifice 310 supplying fuel to the main jet orifice 306 at the edge of the canopy 311. The duct 308 terminates under the canopy 311. At the top of the stem 312 fuel flows through a nozzle 310 into a mix chamber 313 into which air may be fed through a vent 314 at the apex of the canopy 311. The vent 314 connects with an air nozzle orifice 315 which includes several small holes adjacent the fuel nozzle orifices 310. The vent 314 is a threaded valve and may be easily removed and replaced by similar components of different dimensions. The vent is an optional but desirable feature of the invention as it seems to contribute to smoother operation and better fuel economy.

The invention exploits the phenomenon that a fluid (which in the present case'is air) moving rapidly past a small opening creates a negative pressure or vacuum at the opening. This principle is often usedin chemical laboratories in the form of a water pump which consists of a small tube attached at a right angle to a rapidly moving stream of water. The Water creates suction on the small tube which provides a vacuum for the operation of such equipment as filters. The maximum vacuum results when the small tube is at a right angle. By forming a more acute anglethe pressure within the tube is increased and the vacuum correspondingly reduced.

When an engine starts, a vacuum is created at the manifold junction of the carburetor 304 which draws atmospheric air into the venturi passage 303 past the throttle 305 and past the fuel jet 306 and venturi ports or ducts 309. A constriction 316 in the passage 303 accelerates the air relative to its speed at the throttle.

As air passes the fuel jet 306 which is a small opening at a right angle to the direction of the air stream, a vacuum is created within the jet and fuel is drawn from the jet into the moving air stream.

Simultaneously, the air stream passes the ports 309 which are inclined into the air stream, and partly because they are not at right angles to the direction of the moving air stream, less vacuum occurs than at the fuel jet. Relatively, less vacuum is equivalent to more pressure. The pressure is exerted upon the surface of the fuel 307 in the fuel chamber 301 whose other opening (except for the main supply port which is suitably valved and not shown) is the duct 308 leading to the fuel jet 306. Since there is an induced variation in the pressure on the surface of the fuel relative to the jet orifice, fuel flows from the fuel chamber 301, through the duct 308 and out of the fuel jet 306 into the air stream Where it mingles with the air and is vaporized. The disadvantage of boiling fuel in the fuel chamber, as in a vacuum lift type carburetor, is clearly avoided by the pressure on the fuel surface transmitted through ports 309;

It is obvious that as the throttle opens and the engine accelerates, more-air moves along the-@venturivpassage.

and its velocity increases at the constriction .316;.pro-v proportion to) the increased air, and relative .proportions of the air-fuel mixture are maintained without recourse to moving-parts. The pressure upon the surface' of the fuel in the fuel-chamber transmitted through' the ports also varies in relation to .(and generally indirect proportion to) the quantity of air entering the carburetor;- and the pressure at the fuel jet varies inversely withthe quantity of air entering the carburetor.

The mushroom fuel jet 306 is provided with both an air feed 314 and a fuel feed 308whi ch dischargein a premix chamber 313. From the fuel chamber 301,- fuel 397 moves along the jet feed .duct 308, through a number of small nozzles 310 which break the fuel stream into drops and into the mix chamber 313 where the fuel impinges upon and rningles with-moving airdispelled through similar nozzles 315. The air enters the mushroom through-a vent 314=where it is drawn and forced by both the orifice vacuum at the venturi constriction and by its central, axial-location in the coreof the air stream where its opening-is directed fully against the down-rushing air. The air and dispersed fuel droplets form a fog or mist which improves the efiiciency of vapor' ization as the fuel is drawnout of the jet. andinto the main air stream; Air rushing through'the 'vent 314'and past the fuel nozzles 310 also helps draw fuel fromthe jet and force it into the main down draft where it is dispersed and vaporized.

There has thus been described a .novel carburetor which provides a means for mixing-fuel and air at all engine speeds without moving parts inthe -rnixing systern by means of a differential in dynamicair pressureupon the fuel supply and the fuel jet in proportion to the quantity of air entering the carburetor.

What is claimed is:

with a connection to an engine manifoldandwith-a plurality of holes located in the wall thereof in a plane above the surface of the fuel in said chamber, said holes form ing openings between said fuel chamber and the interior of "said passage and being inclined from the venturi passage to the surface of said fuel, a fuel jet mounted within said venturi :and provided with an orifice in the same plane as the openings of said holes on the interior of the venturi, said orifice being connected with the fuel in said chamber by a duct."

2. A carburetor comprising in combination a main fuel chamber traversed by a'venturipa'ssage, provided at one end-open'to the-atmosphere with a throttle, at the other end with a connection toan engine manifold and with'a plurality of holes located in the wall of said venturi tpassage abov'e th'e' level-of the surface of the fuel in said chamber, said holesformingopenings-between said fuel chamber and the interior of said venturi passage and said holes being downwardly directed from said venturi passage toward said fuel chamber and a fuel jet connected by a duct with said fuel chamber and mounted within said venturi passage.

3. A carburetor comprising a fuel chamber containing fuel and traversed by a venturi passage, said passage provided: at one end open to' the atmosphere with a throttle; at the other end with a connection to an engine manifold-and with a holelocated in the wall of said venturi passage at a level above the surface of said fuel in said chamber, said hole forming an opening between said chamber and said passage and being inclined from said passage rto the surface of said fuel, a fuel jet mounted within said-passage and provided with an orifice in the same plane as the opening of said-hole in said passage, said orifice being connected with the fuel in saidchamher by a duct.

4. A carburetor according to claim 1 wherein said openingsare'downwardly inclined from the venturi at an angle between about 10 and about 30.

5. A carburetor according to claim 3 wherein said openingis downwardly inclined from the venturi at an angle between aboutll0 and about 30.

References Cited in the file of this patent UNITED STATES PATENTS