US2057552A - Carburetor - Google Patents

Description

N. H. ElssELL.

CARBURETOR 's sheets-sheet 1 Fi1ed oon. 8, 1955 Gct. 13, 1936. N. H. BlssELl.

CARBURETOR Filed Oct. 8, 1955 3 Sheets-Sheet 2 0d. 13, 1936. N. H, BlSSELL 2,()57552 CARBURETOR Filed Oct. 8, 1935 3 Sheets-Sheet 3 Patented ct. 13, 1936 PA'EN'E' FFECE CARBURETOR Neil H. Bissell, Akron, administratrix of said Ohio; Bessie L. Bissell Neil H. Bissell, deceased Application October 8, 1935, Serial No. 44,035

3 Claims.

My invention relates to carburetors for internal combustion engines of the general type known as plain tube carburetors, and more particularly to downdraft plain tube carburetors.

Usual plain tube carburetors are ineife'ctive inA providing satisfactory carburetion at idling and intermediate speeds, and in order to supply even incompletely carbureted fuel at idling and intermediate speeds, a usual plain tube carburetor may consist of a complicated arrangement of parts, orifices, nozzles, and passageways which may include an enlarged lower carbureting chamber having the throttle valve located therein, an idle orifice in the carbureting chamber,

primary and secondary Venturi tubes above the carbureting chamber, an accelerating pump or device, check valves, and a high speed nozzle or jet.

The arrangements of the venturis in the carbureting chamber are such as to cause eddy currents and to obstruct the flowrof air and fuel through the carburetor and to preclude perfect carburetion at idling and intermediate speeds.

The ideal carburetor may be described as providing the greatest possible quantity rate of flow of air through the carburetor to the manifold at all engine speeds, and parts coordinated to give a perfect proportion and a perfect atomization or vaporization of fuel at intermediate to closed throttle positions, as Well as at wide open throttle position.

The more rapid and complete the vaporization of a volatile hydrocarbon the lower becomes the' temperature of the body or substance from which heat for vaporization is absorbed. This fact may be readily demonstrated by pouring a highly volatile hydrocarbon, such as ether, on the back of the hand. The ether almost instantly Vaporizes completely with an immediate extreme drop in the temperature of the hand from which the heat for vaporization was absorbed.

Usual gasoline of the type used as fuel for usual internal combustion engines, when subject to the same test vaporizes from the back of the hand more slowly and with much less temperature drop.

When fuel enters the manifold of an internal combustion engine in the form of liquid drops of from l/64 inch to inch in diameter or greater, only about one-fourth of such fuel in the form of such drops is utilized in the ensuing combustion in the engine.

In a usual carburetor with a short venturi and the throttle located in a cylindric or other enlarged housing a substantial distance from, or in a downdraft carburetor below, the short venturi, when the throttle disk is open a suiicient amount so as to cause a delivery of gasoline from the main fuel jet in the venturi, there is not suicient vacuum in the chamber of the carburetor housing below the venturi and above the throttle to cause the necessary complete atomization or vaporization of the liquid fuel delivered into such carbureting chamber from the main jet.

This results in the formation of drops of liquid fuel about #-6 inch in diameter or larger at the main jet, which fall down upon the throttle disk and then run off the throttle disk and drop into the manifold in larger drops of liquid fuel with the incomplete combustion incident to the introduction of such drops of liquid fuel into the manifold.

In other words, there is imperfect carburetion at intermediate speeds in such carburetors.

Many usual carburetors in efforts to solve the problem of carburetion at intermediate speeds, utilize accelerating pumps to pump raw gasoline into the carburetor to provide a too rich mixture which gives the desired performance at excessive cost due to imperfect carburetion.

Also for compensating over richness at wide open throttle, such carburetors utilize an air bleed into the main nozzle, but such air bleeds set up forces opposing the ow of fuel out of the main nozzle.

Moreover in a carburetor having an air bled main nozzle, the flow through the passageways to and out of the main nozzle consist of alternate slugs of fuel and air, the rate of flow of which is substantially impossible to control so as to afford a variable flow which is uniform for any particular rate.

The under-hood temperature in a usual passenger automobile is 250 F. in the summer, and 150 F. in the winter.

In summer with the atmospheric temperature at from 60 to 80 F., usual carburetors operate at a temperature of from atmospheric temperature to 120 F. in the carbureting chamber.

The vaporizing and expansion of fuel takes place in the carbureting chamber, and the relatively high temperature thereof is not conducive to effective carburetion, because of vapor lock or molecular disturbance in the main fuel nozzle and fuel supply passageways, and also because of a relatively narrow temperature differential between the entering air and fuel.

Moreover, the heat required for the vaporizing of the fuel is obtained in part from the air passing through the carburetor, and in part from the Walls of the carbureting chamber.

Because of the normal relatively high temperature in the carbureting chamber of a usual carburetor, the walls of the housing are usually insulated from the manifold, thereby substantially cutting olf the manifold as a source of heat for vaporization of the fuel passing through the carbureting chamber. f

The foregoing disadvantages of a usual carburetor arise fundamentally from the fact that at intermediate engine speeds above idling there is` not sufficient pressure drop and velocity ow through the carbureting chamber to attain perfect carburetion prior to the entry of the mixture into the manifold, and at wide open throttle there still exists obstructions in or in advance of the carbureting chamber limiting the desired maximum rate of flow of air to the engine.

Moreover at low speeds with the throttle disk providing a very small opening, in a usual carburetor, Ythe available working pressure which may be of the magnitude of only one pound per square inch, pushes the fuel charge out of the idling jet and the charge drips down the side Wall of the carbureting chamber into the manifold with little or no carburetion.

After continuous operation of an internal combustion engine with a usual carburetor, when the engine is stopped, heat from the engine raises the temperature of the carburetor walls frequently to such magnitude as to cause a substantial expansion in the volume of the supply of liquid fuel in the carburetor float chamber.

In most usual carburetors the arrangement of the supply channels for the idling and main jets are such that liquid fuel thus expanded by heat flows into the carbureting chamber in the manifold and causes a flooding of the engine.

The objects of the present invention include in general the provision of an improved carburetor, not-only having a simplified construction with consequent reductions in the cost of manufacture and maintenance, but which also operates so as to attain substantially perfect carburetion at all engine speeds and at the same time permitting a maximum rate of flow of air, thereby reducing the fuel cost and increasing the power of the engine to which the improved carburetor is applied, so that an automobile driven by the engine may have an increased speed.

More particular objects of the present invention include the provision of an improved carburetor of the plain tube or Venturi type, having no air bleed for the main fuel supply, and with variable and complete control of air and fuel flow at all engine speeds above idling.

Further particular objects of the present invention include the provision of an improved carburetor constructed and arranged so that the temperature of the carbureting chamber under operating conditions is relatively low as the result of complete vaporization of the liquid fuel as it passes through the carbureting chamber at all speeds above idling.

Further objects of the present invention include the provision of an improved carburetor so constructed and arranged as to permit the use of a relatively long venturi.

Further particular objects of the present invention include the provision of an improved carburetor in which the throttle and carbureting chamber are so'arranged with respect to each other and with the other parts of the carburetor as to preclude the formation of drops of liquid fuel and the collection thereof on the throttle disk and the delivery of such drops into the manifold of the engine.

Further objects of the present invention include the provision of an improved carburetor whose construction and arrangement is such as to enable the utilization of heat from the manifold transmitted through the walls of the carburetor to assist in the vaporization of the fuel in the carbureting chamber.

Further objects of the present invention include the provision of an improved carburetor having a main fuel supply outlet and an idling jet, a float chamber, passageways connecting between the float chamber and the main outlet and another passageway connecting between the float chamber and the idling jet, and the main outlet idling jet, iioat chamber, and passageways being so arranged and being provided with a drain passageway so that expanding liquid fuel from the float chamber may be expelled through the drain passageway and may not enter the carbureting chamber through the outlet and jet so as to floodl the engine.

Further objects of the p-resent invention in` clude the provision of an improved carburetor with an improved carbureting chamber into which liquid fuel is introduced in an improved manner so as to be broken up into small particles by the air passing through the carburetor at all engine speeds above idling, and so that the small particles of liquid fuel shall be intimately intermingled with the air, and so as to provide for expansion of the liquid fuel and substantially complete vaporization of the same in the carbureting chamber of the carburetor at all engine speeds, and prior tothe introduction of the mixture of fuel and air into the engine manifold.

The foregoing and other objects are attained by the carburetor, apparatus, parts, improvements, combinations, and subcombinations, which comprise the present invention, and the nature of which are set forth in the following general statement, and preferred embodiments of which, together with their mode ofuse, are set forth in the following description, and which are particularly and distinctly pointed out and set forth in the appended claims forming part hereof.

The nature of the improvements of the present invention may be described in general terms as including preferably in a down-draft carburetor, preferably Venturi tube means having a passageway including an upper converging air inlet section, a lower diverging carbureting chamber section, and' a throat or fuel receiving section between the converging and diverging sections.

Improved main fuel supply means are arranged for delivering a thin sheet or stream of liquid fuel transversely of the tube passageway at the posteriorv side of the throat section and transverselyV of the air stream flowing therethrough, so that the air stream will bend the sheet or stream and shatter the same into particles of liquid fuel which are intimately intermingled with the air and substantially completely vaporized in the divergent section of the Venturi passageway at all engine speeds above idling.

' Throttle means are preferably operative in the diverging carbureting chamber below the outlet means for the main fuel supply. Y

The diverging section of the Venturi passageway is preferably relatively long.

Means operable by changes vin pressure in the tube passageway are provided for varying the throat area of theV Venturi passageway andthe 75 quantity rate of air flow therethrough, and means preferably actuated by the same pressure changes are provided for varying the quantity rate of fuel introduced* into the tube passageway, whereby substantially perfect carburetion is attained at all engine speeds, above idling.

The improvements also include improved details of construction and arrangement of the improved means and parts of the carburetor, as set forth in the detailed descriptive specification hereinafter, and as set forth in the claims.

By way of example, preferredl embodiments of the present improvements are illustrated in the accompanying drawings forming part hereof, in which Figure 1 is a fragmentary elevation and vertical sectional view as on line I I, Fig. 2, other portions being broken away and shown in oblique section on line 3 3, Fig. 2, of a carburetor including the present improvements in place upon the manifold of an internal combustion engine shown fragmentarily, and the carburetor being equipped with an air cleaner shown fragmentarily;

Fig. 2, a transverse fragmentary plan sectional view of the carburetor as on line 2 2, Fig. l;

Fig. 3, another vertical sectional View of the carburetor as on line 3 3, Fig. 2;

Fig. 4, an enlarged fragmentary sectional view similar to Fig. l, as on line I I, more clearly illustrating the improved fuel delivery groove means in the throat of the venturi of the improved carburetor;

Fig. 5, an enlarged fragmentary view similar to Fig. 4 as on line 5 5, Fig. 2;

Fig. 6, a fragmentary top plan view of the improved carburetor with the air cleaner removed;

Fig. 7, a fragmentary elevation view with certain portions broken away and shown in section as on line 1a 1a, Fig. 6, and other portions broken away and shown in vsection as on line 1b 1b, Fig. 6;

Fig. 7b, a fragmentary vertical section thereof as on line 'Ib 'Ib, Fig. 6;

Fig. 8, another fragmentary vertical sectional view thereof as on line 8 8, Fig. 6.

Similar numerals refer to similar parts throughout the drawings. A

The improved carburetor is indicated generally by I0 and in the preferred form shown in a downdraft carburetor, the lower end of which communicatingly connects with the manifold II of an internal combustion engine, not otherwise shown, and the other end of the carburetor I0 communicatingly connects with the outlet tube I2 of an air cleaner, not otherwise shown.

'Ihe carburetor I0 in the preferred construction thereof as shown, includes a cylindric sleeve I3 having a flanged lower end I4 adapted for connection to the manifold II, a flanged upper end I5, and a cylindric bore I6 extending therethrough.

A mounting, housing, and float chamber forming member I'I, preferably of one-piece construction, has a lower end face which seats upon the upper face of the sleeve flange I5, and the mounting, housing, and float chamber forming member I'I is secured to the flange I5 as by screws I8. The member I'I has a cylindric bore I9 extending therethrough which registers with the bore I6 of the sleeve I3, whereby in applying the carburetor I0 to various types of engines, the member I'I and the parts mounted on and carried thereby may be rotated with respect to the sleeve I6 so as to afford the best relative arrangement of the member II and the parts mounted on and carried thereby with respect to the adjacent parts of the engine so as to obtain clearance therebetween.

A Venturi tube member 20 has an externally flanged head portion 2I which rests upon the upper end 22 of the member Il, and the Venturi tube member 2D has a lower elongated externally cylindric portion 23 extending from the head portion 2| and extending into and fitting the registering bores I 9 and I6 of the sleeve I3 and the mounting member I'I.

The Venturi tube head portion 2I as shown is provided with an externally protruding ange 2 la which is adapted to seat the outlet tube I2 of the air cleaner.

The Venturi tube member 20 has an elongated Venturi passageway extending therethrough which is indicated generally by 24 and which has an upper converging air receiving section or end 25, a lower diverging carbureting chamber section or end 26 for Idischarging a mixture of air and fuel into the interior chamber 2l of the manifold II, and the elongated Venturi passageway 24 also includes a throat section or fuel receiving section 2B between the converging section or end 25 and the diverging section or end 26.

The throat section 28 of the Venturi passageway 24 is the section thereof of least diameter and area.

Improved fuel outlet means indicated generally by 29 are arranged for delivering liquid fuel in an improved manner hereinafter set forth into the Venturi passageway 24 immediately adjacent and posterior to the throat section 28 in the transverse sectional portion of the Venturi passage- Way where occurs the greatest pressure drop when gases ow therethrough.

Throttle means indicated generally by 30 are located for the purposes of the present improvements within the diverging section 26 of the Venturi passageway below the fuel outlet means 29, and the diverging section 26 of the Venturi passageway extends in the direction of the longitudinal axis 3| of the Venturi passageway a distance several times greater than the .distance in the same direction of the throttle means 30 from the transverse section of the Venturi passageway into which fuel is delivered by the fuel outlet means 29.

For the purposes of the present improvements, the length of the diverging section 26 of the Venturi passageway 24 is preferably at least` 5 times and not over 10 times the diameter of the throat section 28, and locating the throttle means 30 relatively close to the fuel outlet means 29 permits an improved carbureting action in the elongated portion of the diverging carbureting section 26 of the Venturi passageway 24. rI'he included angle of the divergent section 26 of the Venturi passageway 24 is preferably not over 7% degrees, and in the carburetor illustrated is 51/2 degrees.

It has been determined by experiment that when the divergent section of a Venturi passageway is at least 5 times and not over 10 times the diameter of the throat section, and when the included angle of the divergent section is not over 'l1/2 degrees, such a Venturi passageway attains the maximum efficiency with respect to the quantity rate of flow of gases therethrough.

In usual carburetor construction with the throttle means located immediately adjacent the manifold at the lower discharge end of the carburetor tube, the necessary increase in length has `mitigated against the use of long divergent section Venturi passageways.- Y

In the present improved carburetor l the relatively long divergent section 26 of the Venturi passageway 24 in combination with the above set forth location of the throttle means 30 relatively close to the thro-at section 28 and with other parts permits the use of the above set forth preferred length and taper characteristics for the Venturi passageway and at the same time gives rise to other beneficial operating characteristics, hereinafter set forth.

- Fuel supply means for delivering liquid fuel to the improved main fuel supply outlet means 29 are provided in the carburetor 9, and preferably include constant level iioat chamber means indicated generally by 32 which communicates with the main fuel supply outlet means 29 through a series of passageways in the member l1 and indicated generally by 33.

Improved means indicated generally by 39, preferably of a unitary construction and arrangement, are removably mounted on the member l1 and operatively associated with the Venturi tube member 29 and the throat section 28 of the passageway 24 thereof for Varying the area of the throat section according to changes in pressure in the Venturi passageway so as to provide for Venturi action at all engine speeds above idling characterized by suitable pressure drops and velocities of the air flowing therethrough for attaining substantially perfect carburetion at all engine speeds above idling, in addition to varying the quantity of air passing through the venturi, all as more fully set forth hereinafter. t

Improved means indicated generally by 55,` preferably of a unitary construction and arrangement, are removably mounted on the member l1 and operatively associated with the passageway 29 of the Venturi tube member 2i! and with the main fuel supply passageways 33 for varying the rate of ow or quantity per unit oftime of fuel delivered to the improved main fuel supply outlet means 29 and consequently from the outlet means 29 into the Venturi passageway, according to the same changes in pressure in the Venturi passageway utilized to operate the Venturi throat varyl ing means 34.

The constant level float chambermeans indicated generally by 32 include a float chamber 35 preferably formed as shown in the one-piece member I1 and a float 31 is operatively mounted within the float chamber 36, on one arm 38 of a bell crank which pivots on a horizontal shaft 39. An inlet valve bushing 45 is screwed into a suitable threaded aperture in the upper portion of an end wall of the float chamber, and the bushing 99 has a connector fitting 42 which may be utilized to connect the bushing 40 with the main fuel supply tank, not shown, through tubing, not shown, gravity or a fuel pump being utilized to provide a suitable head on the liquidfuel in the communicating tubular openings 43 and M of the fitting 42 and bushing 4U.

The valve opening 54 of the bushing 49 has a Valve seat d5 formed therein, and a reciprocating horizontal plunger valve pin 46 is arranged in a usual manner for reciprocation towards and away from the valve seat 15, the extremity of the valve plunger pin 45 in the iioat chamber 36 abutting in a usual manner with the upwardly extending bell crank arm 41 having the iioat 31 secured on the other arm 38 thereof. l Y

The operation of the iioat chamber means 32 serves to keep the4 chamber 35 thereof Vfullmof liquid fuel in a usual manner substantially to the level indicated by the dot-dash line 48.

The member l1 includes a main cylindric body portion 99 having a passageway forming boss por# tion 50 protruding from one side thereof, and having a lateral extensionincluding walls forming the float chamber 36.

For purposes of convenience, the longitudinal axis 3l of the Venturi passageway 24 is referred to as Vertical, and the directions of the several fuel supply passageways will be described 'with reference to a vertical location of the longitudinal axis 3l of the Venturi passageway 24, although the improved carburetor l0 will operate underrthe normal varying inclination conditions incident to the operation of a passenger automobile, truck, bus, or the like, the internal combustionengine of which may be equipped with the improved car: buretor l0.

The boss portion 59 of the member I1; has formed therein fuel supply and other passageways which are described as follows: Y v

A horizontal passageway 5! communicas at one end with the lower portion of the float chamber 39 and communicates adjacent its other endV with a short passageway 52 extending latright angles to the passageway 5l. f

The passageways 5l and 52 are formed by drilling in the boss portion 5E), and the outer ends thereof are closed by screw plugs 53V and 54,l respectively.

The inner end of the passageway 52 communicates with the lower end of an upwardlyextending and outwardly sloping enlarged bore passageway 55 having an intermediate internally threaded portion 56.

Adjacent the upper end of the member I1, a horizontal passageway 51 communicates intermediate its ends with the bore passageway 55V and communicates at its inner end with the improved main fuel supply outlet means 29, the outer end of the passageway 51 being closed by a screw plug 5S. f

'I'he preferred unitary means 35 whichrmay be termed automatically'variable valve means, and which as aforesaid Yvaries the quantity rate of flow of fuel delivered to the improved main fuel supply outlet means 29 according to changes in pressure in the Venturi passageway, includes an elongated guide and valve tube 59 having a threaded outer, and as shown lower, end which extends into the bore passageway 55 and is screwed in the threaded portion 55 thereof, and the tube 59 has an elongated valve stem guide bore Eil in its upper portions and an enlarged valve passageway bore v6| in its lower portions, the lower end of the tube 59 preferably being internally threadedand having a short orifice tube 62 screwed therein which provides a communication between the bottom ofthe bore 55 and the valve passageway 6| preferably through the opening of a metering orifice 63 1ocated intermediate the ends of the short tube62.

The tube 59 is provided with an external groove 64 and transverse ports 65 communicating between the groove `55 and the valve passageway 5I, and the groove 64,0pens into the horizontal passageway 51, whereby liquid fuel delivered from the iioat chamber into the'bottom of the bore passageway 55 may pass therefrom through the orifice 63, the valve passageway 5l and the ports 55 into the horizontal passageway 51 and tothe main fuel supply outlet means 29.

As best shown in Figs. 6 to 8 inclusive, the carburetor i9 is provided with idling fuelv supply means indicated generally by Gliwhichare cern bined by novel passageway means best shown in Fig. 7b with the main fuel supply passageways and the float chamber 36, so as to prevent flooding of the carburetor I0 by expansion of the supply of liquid fuel in the float chamber 36 under the action of heat.

The idling fuel supply means 66 includes a lower idling jet opening 61 located in the Venturi member 20 so as to be below one side ofthe throttle disk 68 when the same is in closed position as shown in dot-dash lines in Fig. 8.

The idling jet opening 61 has preferably associated therewith means for varying the size thereof which Vmay include a tapered pin 69 on the inner end of a spring pressed valve screw 10 screwed in a suitable threaded opening formed in the housing member I1 and the tapered pin 69 extending into the tapered inner end 1| of the jet opening 61.

Above the jet opening 61 so as to be just above the top of the throttle disk 68 when the same is in closed position there is provided another idling jet opening 12 extending through the side of the Venturi tube member 29. As shown the inner ends of the jet openings 61 and 12 communicate with an upwardly extending passageway 13 formed by a longitudinally extending socket in the outer cylindric surface of the Venturi tube member 20 and the opposite inner cylindric wall of the mounting member I1.

The upper end of the passageway 13 communicates with the inner end of a horizontal passageway 14 formed in the member I1, the outer end of which is closed by a screw plug 15.

The passageway 14 communicates with the lower. end of a short vertical passageway 16. the upper end of which is closed by a screw plug 11.

The passageway 16 communicates with one end of a sloping drain and air bleed passageway 18 formed in the member I1, the outer end of which is provided with an apertured air bleed and drain screw collar 19.

The member I1 has a vertical passageway 89 drilled therein intersecting the passageway 18 and into the upper end of which is screwed a screw plug 8| having depending therefrom a metering tube 82 having a longitudinal metering opening 83 extending from its lower end to lateral ports 84 formed in a valve head portion 85 located immediately below the screw plug 8|.

The valve head portion 85 includes tapered valve seat portions 86 seating in a conical seat formed at the upper end of the bore 89 at its intersection with the sloping passageway 18.

The lower end of the bore 80 communicates with the inner end of a horizontal bore 81 formed in the member I1, the outer end of which is closed by a screw plug 88 and which intersects with the horizontal bore 5I extending from the float chamber 36;

The improved Venturi throat section area varying means indicated generally by 34, preferably of a unitary'construction and arrangement, includes a mounting and guide tube 89 which has a threaded outer end 90 which is screwed in an internally threaded opening in the member I1.

The bore 9| of the tube 89 preferably has its longitudinal axis at vright angles to the longitudinal axis 3| of the Venturi passageway 24.

The bore 9| of the tube 89 registers with a cylindric opening 92 provided in the Venturi tube member 20. A reciprocating member 93, which as shown is a cylindric plunger, is slidable in the bore 9| of the tube 89 and the opening 9-2, and has an inner end 94 adapted for being extended into and out of the throat section 28 of the Venturi passageway 24 for varying the area thereof, or in other words, the cylindric end 94 of the plunger 93 is movable back and forth cross-wise of the throat section 29 of the Venturi tube passageway 24.

The mounting and guide tube 89 fits and mounts on its outer cylindric surface a aphragm chamber forming housing indicated generally by 95, and which as shown includes bossed, cupped, and flanged separable sections 96 and 91, the section 96 having a boss 98 with a cylindric bore tting upon the outer cylindric surface of the mounting and guide tube 89.

The section 96 also includes walls forming a cup 99 and an outwardly extending securing flange |00.

IThe section 91 includes a cylindric boss |0I, walls forming a cup |02, and outwardly extending anges |03.

A diaphragm |04 which may be made of thin sheet rubber is interposed between the flanges |00 and |03 and the same are secured and clamped against the outer peripheral portions of the diaphragm by screw means I 05. Because of the relatively low pressure differential available for operating the plunger 93, the end thereof extending within the diaphragm chamber has secured thereon, on opposite faces of the flexible diaphragm |04, rigid disks |06 and |01, the larger disk |06 of which provides the working surface for reciprocation of the plunger 93 by differential pressures in the diaphragm compartment |98 on one side of the diaphragm and the diaphragm compartment |09 on the other side thereof formed by the above described construction.

The diaphragm compartment |09 is provided with a vent orice |09- I in one wall of the housing section 96 opening to the atmosphere, so that the pressure in the diaphragm compartment |09 is atmospheric at a static position of the diaphragm, and so that there is a slight lag in the plunger action to avoid too rapid movement after abrupt changes in the throttle position.

The plunger 98 has a longitudinally extending passageway ||0 extending from its inner end in communication with the diaphragm compartment |08 to the inner end of an angular passageway I I I, the outer end of which opens into the throat section 28 of the Venturi passageway 24.

For permitting movement of the plunger 93 so that its end face |I2 is entirely out of the throat section 29 of the Venturi passageway 24, the Venturi passageway is provided with a sloping recess I|3 which gives clearance to the outer end of the angular passageway in the plunger 93 in its extreme retracted position, the angular passageway III opening into the Venturi passageway in the downstream direction thereof, and accordingly the pressure in the diaphragm compartment |08 varies as the pressure varies in the Venturi passageway immediately posterior of the throat section 28.

The plunger 93 is preferably made of noncorrosive material such as stainless steel, and the guide tube 89 is also preferably made of noncorrosive material such as brass or bronze.

The diaphragm chamber forming housing 95 and the flexible diaphragm |04 and disks |06 and |01 connected to one end of the plunger 93 as aforesaid may be termed improved low differential pressure reciprocating motor means which may be indicated by M-I operated by changes in pressure in the Venturi passageway.

Y 'I'he boss 0| has formed therein a counterbore II4, the inner end of which communicates with the compartment |08 and the boss |0| is provided with an end head H5 having an internally threaded bore H5 forme-d therethrough and communicating with the counterbore H4.

An externally threaded tube I 'i is screwed into the bore I6 and within the counterbore I I4, the tube is provided with a spring reacting head I8, and a compression spring ||9 is interposed between the head II 8 and the disk |06.

' The improved fuel supply varying means indicated generally by 35 includes improved low differential pressure reciprocating motor means indicated generally by M-Z and which includes parts similar in construction and operation to the parts of the-improved motor means M-|, the elongated tube 59 of the motor M-2 mounts its diaphragm chamber forming housing and the bore .60 .of the-tube 59 has an elongated yvalve stemV |29 reciprocating therein and Vhaving its upper end preferably screw thread connected with the diaphragm andv rigid piston disks Vof the motor M-2. y

The lower end of the valve stem |20v is in the form of a tapered metering pin I 2| which reciprocates upwards and downwards in the opening of the orice 63.

The tube I'ITI of themotor M,-| is connected by suitable tubings and fittings with the similar tube of the motor M--2 whereby the diaphragm compartment |08 of the motor M--|, and the diaphragm compartment |22 of the motor M-2 are atthe same pressure which is the same as and varies with the pressure in the throat section of the Venturi tube passageway as aforesaid. Y

The diaphragm compartment |23 of the motor M-2 is-provided with a vent |24 communicating with the atmosphere so that the diaphragm compartments |09 and |23 are bothsubject to atmospheric pressure.

The improved carburetor I0 illustrated has been yconstructed with an opening of the throat section 28 having a minimum diameter of ll-g inches, and the diameter of the plunger 93 for this size throat opening is substantially inch. 1

The plunger 93 Vis vpreferably made` of non- .corrosive material such as stainless steel.

Likewise the valve guide and valve ytube 59 is preferably made of non-corrosivematerial such as stainless steel.`

The oth-er parts of the carburetor are preferably made of material having alhigh rate of heat transfer such as aluminum alloy or copper alloys. l Y To facilitate starting in cold weather, the carburetor I0 is preferably provided with a starting 4jet opening |25 below the idling jetopening 61.

with the passageway 73 is normally closed by spring pressed manually releasable valve pin meansgsindicated generally by |26;

The` improved fuel outlet means 29 for thev purposes of the present improvements includes van annular fuel outlet groove |2'I'formed in the Venturi passageway just below theY transverse plane of the throat section 28 having the mini- -mum area, the center of the groove |21 being preferably 0.020 inch below the transverse plane 'the divergent carbureting chamber 26 which of the throat section 28 having the minimum area.

An annular channel |28 spaced radially outwardly of the groove |27 is formed by a groove provided in the external cylindric surface 23of the Venturi tube member 20 andthe internal cylindric wall of the cylindric opening of the member in which the Venturi tube member 20 The channel |28 communicatingly connects with the groove |27 by a plurality of ducts |29. The vducts |29 have diameters greaterthanthe groove |2l, and the channel |28 receives fuel from the horizontal passageway 51; and fuel is delivered through the ducts |29 to the groove |21, vand by reason of the fact thatY the`diameter of the ducts |29 is greater than the width of th groove |27, the groove |27 is maintained fullof liquid fuel. 'i The width of the groove |2'| is preferably 0.018 inch and the diameter of the ducts |29 is preferably 0.040 inch. The operating cycle of the improved carburetor E0 may be described as follows: With the throttle disk 68 open approximately 0.015 inch, the liquid fuel, 'usually gasoline, 'is rst drawn out of the idling jet opening 6l with an air by-pass bleed through the opening 12, and also through the opening 79. i

The air passing the'thro'ttle disk at high velocity causes a slight pressure drop adjacent the opening 61 permitting the entrance of a`rich'mixture through the opening 6T beneath the slightly opened disk 68. When the throttle disk 68/is open to a position causing a speed of substantially 15 miles a'n hour in an automobile equipped withan engine provided with the improve-d carburetor I0, the pressure drop through the Venturi passagewayV at the fuel delivery groove' |21. becomesV suicient to permit a discharge into the Venturi passageway of a thin annular sheet or stream of gasoline which is bent in the direction 'ofi-low ofiair through the passageway by 'the' air passing through the Venturi passageway, and for iany particular position of the throttle Vdisk, there is perfect control with a constant pressure and a constant flow of fuel out of the groove I2|.v

vsheet of fuel beinglforced out of the annular groove |27, andthe fuel is completelyv atomized and the particles of fuel are intimatelymixed with' the air as the fuel and air pass through 55 wayw 24.

`There occurs in the divergent section 26 of the Venturi passageway 24 an expansion or vaporization of the fuel and .absorption of heat from theV airA by the fuel and Yfrom the walls of 1n turnY receive heat from the manifold.

A perfectly carbureted mixture thus enters the manifold, and as the mixture passes through the Venturi passageway 24 there is a drop intemperature of the air passing therethroughand a continuous loss of heat from the walls of the venturi, and an absorption of heat by the particles of fuel with a consequent perfect vapori- Zation. Y

Theplunger 93 and the metering-pin |2| are caused to synchronously move back and forth so as to vary the area of the throat section of the Venturi passageway and to vary the rate of 75 delivery of fuel out of the groove |21, as the square root of the variations in pressure immediately below the throat section, initiated by changes in the throttle opening.

The motion of the plunger 93 actuated by changes in pressure in the Venturi passageway, provi-des proper pressure drops and velocities to permit the formation of a sheet of fuel coming out of the slot |21 and the shattering thereof and intimate contacting of fuel particles and air providing a heat transfer resulting in perfect vaporization of the fuel at all engine speeds above idling, in addition to varying the quantity of air passing through the Venturi passageway 24 at intermediate speeds.

It will be noted also that in the carburetor IB, there is a delivery of fuel at all motor speeds out of the openings 61 and 12.

I claim:

1. In a carburetor and the like, a tube having a passageway arranged for having a flow of gases therethrough, means associated with the tube passageway for Varying the flow of gases therethrough sol as to cause variations in pressure within the passageway, a reciprocating member slidable in a guide tube, a diaphragm chamber forming housing, a diaphragm within the housing and separating the chamber into two compartments, the guide tube communicating with one of the compartments and the reciprocating member being eXtendible into the tube passageway, and the reciprocating member extending into one of the compartments and being secured to the diaphragm, one of the diaphragm chamber compartments communicating with the passageway, and the other diaphragm chamber compartment communicating with the atmosphere.

2. In a carburetor and the like, a tube having a passageway arranged for having a ow of gases therethrough, means associated with the tube passageway for varying the flow of gases therethrough so as to cause variations in pressure within the passageway, a reciprocating member slidable in a guide tube, a diaphragm chamber forming housing, a diaphragm within the housing and separating the chamber into two compartments, the guide tube communicating with one of the compartments, one end of the reciprocating member extending into one of the compartments and being secured to the diaphragm, the other end of the reciprocating member extendible through the side of the tube and movable crosswise of the passageway, one of the diaphragm chamber compartments communicating with the atmosphere, and the other diaphragm chamber compartment communicating with the tube passageway by means of a duct formed in and extending through the reciprocating member.

3. In a carburetor and the like, a tube having a Venturi passageway extending therethrough, a housing mounting the Venturi tube and having formed therein a float chamber for a fuel supply, unitary means removably mounted on the housing and associated with the tube and operative by variations of pressure in the tube passageway to vary the area of the passageway opening at one transverse section thereof, fuel supply passageways providing a communication between the fuel supply chamber and the Venturi passageway, and unitary means removably mounted on the housing and associated with the fuel supply passageways and operative by variations of pressure in the tube passageway to vary the rate of flow of fuel through the fuel supply passageways.

NEIL H. BISSELL.

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