US2717771A - Carburetor - Google Patents

Description

Sept. 13, 1955 Filed Sept.

J. c. RICHARDSON 2,717,771

CARBURETOR 26 1951 filSheets-Sheet l H JJ 31 l I Zmventor James C. zw/m/ dson (Ittomeg 5' Sept. 13, 1955 J. c. RICHARDSON CARBURETOR 4 Sheets-Sheeh 2 Filed Sept. 26, 1951 9 H 9 2 a 3 31 W 0 [L22 A 1.1 5 3 F m 7 a 1 1| 1| 5 A; 7 O l. 3 2

C 3 Z m 5 mm 2 9 1 M I Snnentor Ja mes 6 P4 aha/"6730M attorneys 4 Sheets-Sheet 3 J. C. RICHARDSON CARBURETOR Jay. 8

(Ittomegs Sept. 13, 1955 Filed Sept. 26,

United States Patent CARBURETOR James C. Richardson, Naugatuck, Conn.

Application September 26, 1951, Serial No. 248,379

Claims. (Cl. 261-50) This invention relates to carburetors for gasoline engines, and more particularly to a carburetor of the type requiring no fuel pump, float or float tank under ordinary circumstances. Such carburetors are of the so-called self-feeding type.

Heretofore there have been many proposals for constructions of vehicle carburetors in which fuel is brought to the carburating chamber from the main fuel tank by the suction effect of the engine, but so far as I am aware no such constructions have gone into commercial or practical use.

Such proposed carburetors are based on the principle of sucking fuel from the fuel tank or other source to the carburating chamber as the result of engine suction, or by engine suction and a venturi effect produced by the flow of the intake air. The types which rely on engine suction alone normally require such a severe restriction of the air supply as to permit the obtaining of only a small portion of the power normally avilable from a given engine, and have long been excluded from practical consideration for this reason.

With regard to the latter type relying on engine suction together with venturi action, and giving particular attention to the constructions heretofore proposed, I have found, after much investigation and reasearch, that such devices were impractical in operation because they would not feed and carburate satisfactory quantities of fuel in starting up, accelerating, and decelerating the engine. Particularly was this true when the carburetor was used on a vehicle being driven up a hill when a greater amount of power was required in proportion to the amount of the intake air and the amount of suction created by the engine. One of the faults was that in accelerating, the engine would not get a proper or satisfactory mixture and might stop or operate irregularly.

I have found by experiment and test that to obtain economy of operation and smooth action, a ratio of air to fuel of between and 15 /2 to 1 is required on normal grades with normal speeds and normal acceleration, but that on steep hills or with a wide or near wide open throttle the ratio should be in the nature of 12 or 13 to lall ratios being weights of air to weights of fuel.

I have found that by increasing the richness of the mixture automatically during accelerating, much of the difficulty heretofore experienced has been avoided. Accordingly, I have provided in combination means responsive to the suction produced by the engine and the rate of flow of intake air through the carburetor for varying the force which draws the fuel into the carburating chamher, and means for varying the size of the path of fuel flowing to the fuel orifices in accordance with the extent to which the butterfly or other valve controlling intake air is opened. Thus, as the butterfly valve is opened when accelerating, the size of the path fuel flowing to the orifices is increased while the venturi stream remains reduced and confined to areas close to the orifices, thus tending to maintain the draft at the orifices whereby burating chamber.

2317,? 71 Patented Sept. 13, 1955 the amount of fuel passing to the combustion chamber, in relation to the air flow, is increased.

As the engine speeds up and the ratio of air to fuel may be increased, the venturi stream is widened, thereby reducing the relative suction effect on the fuel orifices, and the amount of fuel discharged in relation to the air flow.

I have further found that in starting the engine as well as at the instant of rapid acceleration, it is advantageous to make an extra quantity of fuel available to provide a rich mixture which will speed up the response of the engine. For this purpose I have provided means which reacts to the cessation of suction obtaining when the engine is stopped, or to the low suction values which exist in the manifold during cranking or when the butterfly valve is opened suddenly a substantial amount, to supply this extra quantity of fuel. This automatic means for supplying the extra quantity of fuel is so arranged that after the engine is started and the suction becomes normal, or after the engine has responded to an accelerating operation, the means supplying the extra quantity of fuel becomes inoperative until again required.

I have found that rather than use a single circular or annular orifice as heretofore proposed, more reliable operation and greater economy can be obtained by the use of a plurality of fuel discharging orifices arranged in a line across the carburating chamber. This may conveniently be done by passing through the carburating chamber a tube having a row of apertures of desired size and number over and around which tube the intake air flows.

I have found that the venturi effect resulting from the engine suction and the flow of intake air may be conveniently varied and controlled by providing at each side of the fuel tube a vane mounted in such a way as normally to lie against or close to the fuel tube when the engine is stopped but capable .of movement away from the fuel tube to produce a stream of gradually increasing width but of gradual decreasing venturi effect as the vanes move away from the fuel tube. To facilitate this, the carburetting chamber is advantageously made rectangular, other than circular as is usual.

To control the responsiveness of the vanes to the air flow, I provide reaction means either in the form of properly tensioned springs or weights.

The carburetor of the present invention lends itself admirably to meeting various special conditions. For instance, if the economy factor is not as important as the power factor, I can vary the fuel metering device operated in coordination with the butterfly valve to increase the amount of fuel which may pass into the car- In the form of my invention herein disclosed, the metering device comprises a rotary valve or plug shaped to change the area of the passage as it is rotated. By substituting another properly shaped plug, I can either increase or decrease the power output, or control the factor of economy.

To meet other unusual conditions such as the extraordinary power required in racing cars, the carburetor of the present invention, although a self-feeding carburetor, may be used in connection with a float tank connected with a fuel pump. Since the effort required to draw the fuel from the float tank is less than from the main tank, the means for regulating the opening of the venturi controlling vanes may be changed so as to allow the vanes to open to a greater extent than they would without the pump and tank, thereby permitting a greater quantity of air and fuel to enter the carburating chamber than would otherwise be possible. When used on bus or truck engines, the carburetor of the present invention may also be used advantageously with a float tank and fuel pump. Since, by having a supply of fuel close at hand, the head against which the fuel is required to be lifted is slight and virtually constant regard-less of whether the vehicle .is traveling on the level or up and down inclines, still more accurate regulation of the desired ratio of air to fuel may be maintained, resulting in even further fuel economy.

The carburetor of the present invention also lends itself to use with an auxiliary source of air supply, such as a super-charger, in which case the means resisting the movement of the vanes will be regulated to suit the conditions.

This application is a continuation in part of my previously filed copending applications Serial No. 201,205, filed December 16, 1950, and Serial No. 229,601, filed June 2, 1951.

Additional features and advantages will hereinafter appear.

In the accompanying drawings:

Figure 1 is a front elevation of a carburetor in accordance with the present invention.

Fig. 2 is a side elevation of the device of Fig. 1 taken from the left-hand side and looking towards the right.

Fig. 3 is a section taken approximately on line 33 of Fig. 1.

Fig. 4 is a section taken on line 4-4 of Fig. 1.

Fig. 5 is a section taken on line 5-5 of Fig. 1 with one position of the parts being shown in broken lines.

Fig. 6 is a perspective view of the throttle valve shaft with the throttle operating arm, butterfly valve, and metering plug assembled thereon.

Fig. 7 is a section taken on line 7-7 of Fig. 6.

Fig. 8 is an elevation similar to Fig. 2 but showing the complete assembly including the diaphragm for automatically controlling the fuel bypass.

Fig. 9 is a partial section taken substantially on line 99 of Fig. 8.

Fig. 10 is a .plan of the carburetor with the top section removed, the air vanes being arranged in normal, non: operating position.

Fig. 11 is a view similar to Fig. 10, but with the air vanes in partly opened, operating position.

Fig. 12 is a fragmentary elevation looking in the same direction as Fig. 3 and illustrating another embodiment of the control means for the air yanes.

Fig. 13 is an elevation to a reduced scale of the carburetor of the invention showing an automatic starting mixture adjusting means mounted thereon.

Fig. 14 is an elevation, partly in section'similar to Fig. 8, but illustrating an embodiment of the invention slightly different from the Fig. 8 showing and wherein provision has been made for mounting the diaphragm directly on the carburetor body by means of its air outlet fitting, and illustrating a novel air mixing device.

Fig. 15 is a cross sectional view of the novel .air mixing device of Fig. 14 to an enlarged scale, and taken substantially on line 15-15 of Fig. 14.

Fig. 16 is a vertical sectionof a novel fuel level maintaining andfuel cooling device according to the present invention.

Fig. 17 is a section taken on line 17.17-.of Fig. 16.

Referring to Figs. 1 to 11, the present invention includes, in the preferred embodiment thereof, a carburetor body which comprises an upper casting 20 and a lower casting 21 having suitable flanges for connection to each other by screws 22. A large passage .23 runs vertically through the casting assembly and consists ofan upper cylindrical portion 23a through the upper casting which connects with the upper end -of a passage 23]) through the 'lower casting. The passage 23b is mainly rectangular in horizontal cross section, 'but merges into a cylindrical portion 230 at its lowerextremity. The passage 23 constitutes the air duct and mixing chamber of the carburetor. The upper end of the casting 20 is provided with means such as seat 25 for receiving the collar 27 .of a .cOnventional air filter. The lower end of casting -21is shaped to provide a sealing flange 29 which is bolted toa corresponding flange 31 on the intake manifold. On one side of the upper casting 29 is an integral enlargement or 'boss 33 which overlies and merges with a corresponding boss 33a on the lower casting 21. The combined enlargement 33, 33a provides for most of the principal operating parts and connections to the carburetor as will hereinafter appear. Small bosses 35 and 37 are also formed on the other sides of the castings 24) and 21 respectively. A small boss 39 towards the upper end of the carburetor provides for the conventional vacuum connection 41 communicating with .12. port .43 opening in the air passage 23 for controlling the spark advancing and retarding mechanism. it will be seen from the foregoing that no float chamber is necessary to the makeup of the carburetor of this invention.

Throttle valve assembly The carburetor of this invention is essentially an anterior throttle carburetor, in that the throttle valve is 10- catedat a position in the main air stream, upstream from the ;fuel emission apparatus.

A horizontal bore 51 formed through ' bosses 33 and 35 rotatably carries a throttle shaft 53 which extends diametrically of the circular portion 23a of the air passage 23, and beyond each side of'the casting, and has mounted thereon a butterfly valve 55 of the proper size and shape to open and close the main air passage 23. Attached to one end of the shaft 53 is a collar 57, fixed thereon by means of a set screw 59. The collar 57 carries an integral operating lever 61 which is connected to a member 63 in the conventional throttle operating linkage (Figs. 1 and 2). The collar also carries integral stops 65 and 67 for engagement with portions of the boss 35 to fixthe maximum and minimum throttle position.

Main fuel path and metering means The * bosses 33 and 33a together provide a plurality of intersecting passages, best seen in Fig. 4, which go to make up the liquid fuel conduit system of the carburetor. A 'large bore '69 surrounds the end of the throttle shaft 53 opposite to that on which the throttle lever 61 is mounted, and forms a metering chamber which rotatably receives a metering plug 71 attached to the end of shaft 53. A disk 73 is fitted into the end of the bore 69 to close the same. A horizontal bore 75 communicates with the metering chamber 69 and is fitted for receiving a supply connection 77 for attachment to a conduit leading directly to a fuel supply tank. 'No fuel pump is normally required even though the tank is located at the rear of the vehicle and lower than the carburetor. A vertical passage 79 is blind at the bottom and communicates at its upper end with the lower portion of the metering chamber 69. The passage 79 also intersects a horizontal bore 81 extending across the air path 23 and in which is fixed the open end of a nozzle tube 83. Inasmuch as the tube '83 will normally be used as a partial premixing chamber for liquid and air as hereinafter described in connection with the preferred embodiment of the invention, its diameter willpreferably be more than twice that of-the maximum opening of the connected liquid orifices, and an internal .diameter of ,4 inch has been found suitable :forordinarymotor car operation. The opposite end of the tube may be supported in a continuation of thebore 81 formed in the boss 37. The ends of bore 81 are shown as .closed by threaded plugs 82. The tube 83 has a plurality .of emission orifices 85 which face downstream-of the air path, are spaced along the tube 83, and are substantially equal in total area to the interior crosssection of the tube 83. The metering plug 71 has a peripheral groove 87 which is quite narrow, and except atits extreme ends is much deeper than it is wide. The groove is designed so that a path of zero or minimum erosssection connects the bores '75 and 79 when the throttle is closed, and a maximum connection is provided when the throttle is open. The plug 71 is preferably angularly adjustable about the axis of shaft 53, by means of wrench-receiving openings 89 for example, and may be clamped in adjusted position by suitable means such as screw 91 threaded into a suitable opening in shaft 53, in cooperation with a lock washer 92. The primary path of liquid fuel through the carburetor, therefore, includes bore 75, metering groove 87 in plug 71, passage 79, nozzle tube 83 and orifices 85 therein. A suitable maximum effective cross section of the orifice provided by the plug groove has been found to be about .005 square inch for ordinary motor car operation.

Air speed control Inasmuch as the present carburetor must draw liquid fuel up from the supply tank, the control of the air speed through the carburetor is quite important under certain conditions, and means is provided for accomplishing this in the form of air vanes 93 which are pivotally mounted on the casting 21 on axes parallel to the nozzle tube 83.

Each vane 93 is attached to a shaft 94 rotatably mounted on the shafts 94; and, in general, when the spring pressure or vane reaction is weakened, a slight increase in liquid fuel opening sizes is advisable. Correspondingly, a strengthening of vane reaction indicates a slight reduction in liquid metering passages. When the fiow of air displaces the vanes 93 they swing away from the nozzle 83 an amount determined by the speed of the air, and thus form closely adjacent the nozzle a variable restriction or venturi in which the air travels at higher velocity than in the remainder of the path 23. The curved lower ends 93a of the vanes 93 cooperate with the curved sides of the tube 83 to provide paths of elongate rectangular aspect in cross section (Fig. ll) and which are relatively streamlined in the direction of flow in order that the air may have smooth flow adjacent the nozzle openings 85. It will be understood that the flaps 93 provide a moderate restriction in the air path 23 even when they are fully open as shown in dotted lines in Fig. 5. Figs. and 11 illustrate the flaps looking from the top, and the latter view shows particularly the shape of the divided air path when the flaps are partly open.

Starting mixture control Inasmuch as fuel vaporization is apt to be incomplete in a cold manifold, it is normally the practice to provide a choke, or other means for temporarily admitting a greater proportion of liquid fuel into the mixture so that the part which does vaporize will bring the gaseous portion of the mixture up to the proper combustion ratio during starting. According to the present invention a bypass conduit which circumvents the metering device is provided. This bypass includes a vertical passage 103 in the bosses 33, 33a, which passage communicates at its upper end with the induction bore 75. A sloping bore 105 connects the vertical passages 103 and 79 and is stepped to provide between them a valve seat 107. Threaded into the outer end of bore 105 is a guide cap 109 in which is slidably mounted an operating rod 111 the lower end of which has a valve member 113 with a tapering nose 115. A compression spring 117 placed between the inner end of the cap 109 and the valve member 113 urges the latter against the seat 107 to close the bypass conduit. Any suitable linkage (not shown) may be employed to connect the end of the rod 111 with a control at the operators station, or suitable automatic control mechanism may be connected therewith as hereinafter described. It will be readily seen that drawing of rod 111 outwardly raises valve 113 from seat 107 and admits liquid fuel to the nozzle pipe 83 in addition to that provided through the path 75, 87, 79, and that the degree to which the rod 111 is withdrawn controls the amount of extra fuel admitted due to the metering action of the tapered nose 115. The valve 113 may therefore be opened to the desired degree to provide an appropriate starting mixture, and may be closed when the engine is warm and when normal running conditions are established. A suitable maximum opening at the valve 113 is usually found to be about one-fifth of the maximum opening at the groove 87 in plug 71. Guide cap 109 is threaded and also serves as an adjustable stop by means of which the maximum opening of valve 113 may be set. A lock nut 119 is provided for fixing the setting once determined.

In Fig. 13 is shown a form of the invention in which the rod 111 is connected to the core 112 of a solenoid 114 connected in the circuit of switch 116, which may be any suitable switch which closes when the starter circuit is completed and opens during normal running, for example, the manual dash button switch in a starter relay circuit. Thus whenever the starter motor is energized, the solenoid 114 will lift the valve 113 and projection 115 and provide a rich starting mixture automatically. Another automatic starting arrangement, which is at present preferred, is more directly related to operation under conditions of acceleration and will be discussed hereinafter under that heading.

Idling control mechanism As the result of extensive experiment I have discovered that it is possible to derive extreme accuracy in fuel metering over the entire range of operation under load by a careful angular adjustment of the plug 71 on the shaft 53. This being the case, I have also discovered that the same degree of accuracy can be maintained if idling speed and mixture adjustments are arranged to be made separately from the setting of plug 71 or the shaft 53. With this in mind the groove 87 is normally cut so as to close off entirely when the butterfly S5 is in closed position, and the closed position of the butterfly is preferably predetermined and not relied on for idling speed control adjustment as is commonly done. Fuel for idling passes down passage 163 and is permitted to enter the nozzle tube 83 by means of a short horizontal bore 119 which connects therewith. An adjustable valve 121 is threaded in the bore 119 for controlling its effective size, and a lock nut 123 is provided for securing the valve 121 in fixed position when an appropriate setting has been achieved. This small passage causes a fairly rich idling mixture when the engine is running at idling speeds, but its effect becomes proportionately less as more air flows through the path 23, so that under normal running conditions its effect is negligible.

Instead of providing an adjustment which varies the angle of minimum opening of the butterfly to determine the idling speed, this invention includes an opening 125 in the butterfly valve 55. The underside of the opening is closed by a flexible metal reed 127 which can flex slightly until its end strikes the stop 129 and whose resiliency is suificient to insure a suitable minimum static depression on the nozzle tube during cranking rotation of the engine sufficient to draw the starting and idling fuel charge from a normally located supply tank positioned below the engine at the rear of the car even when the car is standing on a hill with its engine high and its tank low. For most conditions the setting of reed 127 will be satisfactory if it produces a manifold depression of about seven inches of mercury at cranking speeds. Once the butterfly 55 is opened to a slight degree during normal running, the opening 125 and reed 127 will have little or no effect. The amount of air permitted to pass the opening 125 is adjusted by means of a gate valve 131 which is swingable across the opening 125 to any desired Rapid acceleration control mechanism In providing for the fueling of vehicle engines it is customary to incorporate devices which will correct for special conditionsoccurring during rapid acceleration, for example, automatic pumps, self-emptying wells, and the like. The present invention provides a device of exceed-ingly simple construction for this purpose which makes use of the starting bypass valve 113 in its .operation. This arrangement is illustrated in Figs. 8 and 9, but has been omitted from the previous views for purposes of clarity. Mounted on one of the castings 20 or 21 is a bracket 135 carrying a housing 137 which encloses a flexible diaphragm 139; an operating arm 141 is mounted on one side of the diaphragm 139, and on the opposite side is a compression spring 143 in a spring barrel 138 urging the arm 141 outwardly of the housing 137. A vacuum line 145 connects the housing 137 on the spring side of the diaphragm 139 with a port 147 in the casting 20 just below the butterfly valve 55. A suitable mechanical connection is provided between the arm 141 and rod 111. In the form shown .a guide bar 148 is mounted on the housing 137 for stiffening the arm against lateral swinging due to the flexibility of the diaphragm 139, and a cross bar 149 is connected to the rod 111 by a link 151.

Operation in general After the carburetor has been connected to the intake manifold, air cleaner, and throttle linkage in the usual manner, the general mixture may be regulated to a desired value by loosening screw 91, setting the plug 71 at the desired angular position .as determined by the normal running performance, and tightening the screw 91.

As in most carburetors there is an air flow in the directio of arrow A, Fig. '5, through passage 23, which flow is induced by the pumping action of the engine cylinders on intake stroke, and the speed of this flow is roughly proportional to engine speed for any given loading. The structure described is basically an anterior throttle carburetor which tends to provide .a fairly constant draft on the fuel nozzle as opposed to the widely varying draft of the posterior throttle carburetor. When the butterfly 55 is closed the static depression at the nozzle openings 85 due to the pumping action of the engine is quite high. As the butterfly opens, the static depression drops off, but kinetic depression, due to the increasing speed of air flow through the restriction between vanes 93 and nozzle tube .83, picks up, so that the draft at the nozzle is maintained. it will be seen that .as the throttle is opened and the ,air flow increases, additional liquid fuel output at the nozzle is required to maintain the prescribed air-fuel ratio. This effect is brought about 'by the metering groove 87 in the plug 71 attached to throttle shaft 53. The

groove is so formed as to provide the proper fuel passage for any given throttle setting, giving a minimum (preferably zero) connection between the passages 75 and 79 when the throttle 55 is .closed as shown in Fig. 4, and a maximum connection when the throttle 55 is full open (i. e. when drum 71 is rotated about 80 degrees clockwise from the Fig. 4 position). As the throttle opens gradually and the air speed increases, the vanes '93 open progressively wider against the force of spring 97. The vanes are arranged so that normal gradual throttle advance opens them to about one-half open position at about one-quarter throttle as indicated in Fig. 11. Thereafter they may diverge slightly with a further gradual increase in throttle opening, but rarely reach the full open condition shown in dotted lines in Fig. 5 except possibly under conditions of high speed, full power operation. The effect of the vanes during the first one-eighth of throttle travel is also somewhat secondary for it is during this :8 period that the nozzle draft still consists to a large extent of the static engine depression, the kinetic portion due to the venturi having .as yet become only a fraction of the effect. This fraction is, however, important during a rapid throttle advance as will subsequently appear.

Rapid throttle opening under load One important reason for having the vanes 93 movable and lightly urged towards closed position as Shown, is to provide for a special case Where .a rapid throttle advance from initial slow engine speed under load is desired. A similar carburetor provided with afixed venturi and lacking any equivalent for the vanes 93, and which operates normally for all other conditions, will cause spitting and possibly stalling under these special circumstances, probably due to the height through which the fuel must be lifted from the ordinary automobile fuel tank. However, when the novel structure including the vanes 93 which are hinged and urged in a direction normally to close off the air supply is provided, this phenomenon is prevented. it may be that the spring urging of the air vanes 93 delays their opening just long enough behind the throttle opening to prevent the static depression at the nozzle from dropping too precipitously, and maintains a smoothly falling static manifold depression curve until the air speed effect at the nozzle has an opportunity to start assisting in the fuel draft function. However, since the vane spring 97 is quite light, it is more likely that the position of the vanes closely adjacent the sides of the elongate nozzle tube at this stage of the operation represents a condition such that the kinetic depression at the nozzle represents a significantly higher proportion of the total draft than is usual with the previously known fixed venturi type of anterior throttle carburetor at low air speeds. Thus when the throttle is thrown open suddenly and the static depression tends to drop rapidly, the kinetic depression remaining due to the partly closed position of the vanes '93 holds a necessary minimum draft on the fuel at the nozzle. Whereas the intake manifold depression may well drop from 20 inches of mercury to about 1 /2 inches of mercury when the throttle is opened wide, the vanes 93 will be found to prevent a corresponding drop in the draft at the fuel nozzle 93, so at all times the nozzle draft will be at least slightly greater than that resulting from manifold depression alone and in the most severe condition will not drop below the-equivalent-of a static manifold depression of 2 /2 inches of mercury. Whatever the exact explanation, the spring urged vanes 93, in combination with the nozzle tube 83, are found to produce a sufiicient draft such that, in cooperation with the Wide valve opening at groove 87 due to the wide throttle opening, they provide a mixture slightly richer than normal which gives a smooth flow of power with the liquid fuel drawn directly from a normally placed low supply tank and without danger of stalling whenever a sudden opening of the throttle occurs, even at slow speeds under heavy load, or when the vehicle is climbing a hill. One important advantage which is found to result from the construction according to this invention is that the fuel flow can be thus maintained without any hiatus even when the throttle is advanced rapidly during steep hill climbing, a feat which was beyond the capabilities of self-feeding carburetors of the types known heretofore.

Starting and rapid acceleration While the spring urged vanes 93 serve to prevent the possibility of any hiatus in the nozzle draft and to provide a slightly enriched mixture when needed due to a rapidly opened throttle, full performance at the instant of acceleration commencement requires that a full power fuel mixture somewhat richer even than that used for normal running or normal acceleration be supplied to the engine in order to accelerate smartly, and this the vanes 93 do not alone provide. The accelerating mechanism including diaphragm 139 and valve 113, shown in Figs. 8

and 9 and previously described, is used for this purpose and provides the rich power mixture which is needed for peak performance.

The diaphragm spring 143 is strong enough normally to hold the valve 113 fully open against its stop 109 when the engine is not running. Cranking speed of the engine, while causing a fuel raising draft of about 7 inches of mercury, is insufiicient to overcome the force of spring 143 and the valve 113 remains open to provide a rich starting mixture. When the engine has started and is idling or otherwise operating normally, however, the static depression is high enough to overcome the spring 143 and allow the valve 113 to close, providing normally lean mixtures under the control of plug 71 and idling valve 121. When, however, the static depression under the butterfly drops rapidly for any reason, e. g. when the throttle is opened rapidly under load, the spring 143 will again overcome the diaphragm to provide the rich power mixture necessary to bring the engine quickly up to speed whereby the depression is returned to normal and the valve 113 is again allowed to close. By means of this simple yet sensitive and accurate control which provides richness in the mixture instantly when needed but only as needed, the general normal running characteristics of the carburetor as determined by the groove 37 may be made to provide an exceedingly lean mixture for normal purposes with unusually clean and economical operation resulting, but without detracting from performance features.

The carburetor of this invention, when used as a selffeeding fueling device, may be employed to the greatest advantage if the characteristics of the fuel line connecting it with the liquid fuel tank are taken into consideration. I have discovered that the best length for the fuel line for a given tube diameter bears a definite relation to the size of the metering groove 87 when the displacement of the engine and the type of operation desired are given. While the number of variable factors involved prevents the stating of an accurate rule covering all conditions, it will be found possible to determine values readily for any specific set of circumstances. As an example of the appropriate relationship between the values, I have discovered that an engine having an S. A. E. horsepower rating of 30.4 and a maximum brake horsepower of 105 (i. e. an engine having a total piston displacement of 235.5 cubic in. and a maximum speed of about 4,000 R. P. M.) used with a carburetor having a metering groove 87 of the approximate proportions showing in the accompanying drawings and whose maximum cross section is about .0048 sq. in. operates satisfactorily with a A I. D. tube, ft. in length. The relationship between the parts is such that for a given engine and given tube length, a reduction in tube diameter requires an increase in metering groove cross section.

In Fig. 12 is illustrated a slightly different embodiment of the invention in which the collars 96 are replaced by collars 196a, each of which has a radially extending arm 99 on which is slidably mounted a weight 100 fixed thereon by a set screw 101. The arms 99 are positioned to extend so that their average position is nearly horizontal. This form employing weights is found to operate equally as well as the form using spring 97, but the latter is preferred at present from considerations of compactness. Adjustment of the weights 100 along the arms 99 provides for controlling the effect of the vanes 93 similar to the tension adjustment of spring 97.

A leaf spring 102 may be provided, if desired, in order to place a slight drag on the shafts 94 to introduce a small reluctance into the motion of shafts 94 in either vane opening or closing direction. Such a spring preferably has two similar ends 104 which are bent into opposed, outwardly opening V shapes which support the spring in place on the shafts 94 and simultaneously provide the friction surfaces for the control of the shafts.

The main bow of the spring is normally so configured as to space the ends farther apart than the shafts 94 so that a bending force must be applied to the spring to place it on the carburetor, and relaxing of the bending force when the spring is in place allows the V ends 104 to press against the shafts 94. The spring 102 serves to provide slightly increased nozzle draft during rapid opening of the throttle for better acceleration performance, and is particularly intended for use in cases where the diaphragm assembly 137, 139, 141 of Figs. 8 and 9 is omitted for reasons of reduction in initial cost. The spring 102 while providing satisfactory operation in this respect is not the full equivalent of the preferred diaphragm operated form of Figs. 8 and 9 and of Fig. 14 to be hereinafter described, which form gives a quality of performance that is entirely satisfactory by comparison with any modern standards. The spring 102 is also suitable for use when the shafts 94 are controlled by means other than the weights 100, e. g. the spring 97, as will be readily understood. The showing of the carburetor in general in Fig. 12 is fragmentary since all of the other parts are identical with those previously described, and those parts which appear have been given the same reference characters as previously assigned.

In Fig. 14 is illustrated the presently preferred embodiment of the invention which includes a lower easting 21a slightly different from the lower casting 21 previously described in that the angle of the by-pass valve boss has been slightly changed, and an upper casting 20a which provides an integral boss 39a which accommodates both the spark advance connection and the diaphragm mounting by turning the opening for the former at a slight angle to provide clearance for the spark control line around the diaphragm. The tapped opening 3% provides for the spark advance connection while the tapped opening 147a connects with a fitting 145a. The fitting preferably has a reduced pipe thread which takes into the opening 147a and a machine thread matching the threads in the spring barrel 138 of the diaphragm housing 137. A lock nut 137]) is provided for clamping the barrel 138 when the diaphragm is suitably oriented with respect to the carburetor body. The diaphragm mechanism is the same as that shown in Figs. 8 and 9 and hence has not been shown in detail in this view, and

' the same parts are indicated by the same reference characters throughout.

The connection between the operating arm 141 and the by-pass valve is made by means of a J-shaped link 149a which has one end passing through an opening in the end of arm 141 and fastened therein by pins 142 at either side of the arm. The other end of the link connects loosely with the end of the by-pass valve stem, as by means of a pin 151a and has a slight rocking connection to allow for the angular relationship between the paths of the parts. As previously pointed out the angle of the by-pass' valve boss has been changed slightly so as to accommodate the changed diaphragm position, and the new boss is indicated by the reference character 33b.

An improved valve stem 111a is provided which lacks any enlargement and merely includes the reduced tapered nose for seating in the valve seat 107 of the angular bore 105. The spring 117 of Figs. 4 and 9 is omitted, and the action of diaphragm 139 relied on for the entire control operation. In other respects the carburetor of Fig. 14 is the substantial equivalent of that of the previous figures, and the same reference characters have been used in identifying the same parts. The operation of the carburetor of Fig. 14 is the same as that prevously described for the form of the invention shown in Figs. 8 and 9 as will be understood.

Figs. 14 and 15 also illustrate a refinement which may be applied to any of the embodiment hereinbefore described, namely a controlled aerator for the nozzle tube 83. This element is designated generally by the referonce character 153 and is shown in detail in Fig. 15. It consists of a small cylinder 155 which has its outlet formed :as a threaded nipple 157. The cylinder has a small inlet opening 159 and houses a piston 161 which is slidable between two end positions within the cylinder. The piston has a central blind bore 163 which opens towards the outlet passage 165 through the nipple 157, and which receives and guides a compression spring 167, which is arranged to urge the piston 161 away from the outlet passage 165. A stop 168 determines the maximum outward position of the piston 161. A peripheral groove 169 is formed in the piston 1.61 and is so located that when the piston is in full inward position, the groove registers With the inlet 159 and when the piston is urged outwardly against the stop 168 the communication is cut off "by the cylindrical portions of the piston. A small passage 1'71 connects the groove 1-69 and the central piston bore 163. The nipple 157 is threaded into the lower casting 21a or 21 in place of one of the plugs 82, preferably the one at the side of the carburetor with the valve plug 71, and is thus subjected directly to the depression in the nozzle tube 83. Under normal conditions the depression is such as to hold the piston 161 inwardly against the force of spring 167, so that a small stream of air enters through passages 159, 169, 171, 163, 165 to mix with the liquid fuel on its way to nozzle openings '85. The metering orificeformed by groove '87 is accordingly set slightly clockwise from the position shown to compensate for the air thus drawn in. When conditions are abnormal and the nozzle depression drops off to extremely low values such as during rapid throttle opening and the like, maintenance of the nozzle depression and production of slightly richer mixtures is insured by the automatic closing of the air opening 159 due to spring 167.

The carburetor of the'present invention lends itself admirably to meeting various special conditions. For instance, economy or power can be determined within limits by angular adjustmentof the plug 71 as previously described. Furthermore, if the economy factor is not as important as the power factor, I can vary the shape of the groove :87 in the plug 71 to increase the amount of fuel which may pass for any given throttle setting. By merely removing one plug 71 and substituting another properly shaped plug, I can either increase or decrease the power output.

When it is desired to apply the present invention unusual conditions such as those of extreme power required in racing cars, the carburetor of the present invention, although capable of operating as a self-feeding carburetor, may be beneficially used in connection with a float tank connected with a fuel pump. Since the effort required to draw the fuel from the float tank is less than from the main tank, the means for regulating the opening of the venturi controlling vanes 93 may be changed by adjusting collars 96 or weights 1&0 so as to allow the vanes to open even more readily than they would in the example first given, thereby permitting a slightly greater quantity of air and fuel to enter the carburating chamber than would otherwise be possible. When used on bus or truck engines, the carburetor of the present invention may also be used advantageously with a float tank and fuel pump to provide the extreme in economy, since, by having a supply of fuel close at hand, the head is virtually constant regardless of whether the vehicle is traveling on the level or up and down inclines, and still more accurate "regulation of the desired ratio of air to fuel may be maintained.

At such times as a float tank is found useful for special application, a novel attachment of this character is provided according to the showing in Figs. 16 and 17. Fig. 16 is shown a tank 173 having a main float chamber 175 and a small tube-receiving groove 177 to one side thereof. A hollow sheet metal float cylinder 179 fits snugly but slidably in the float chamber 175, and a cover plate 181 closes the top of the tank with an air-tight seal.

iii

Connected to the cover plate 181 and projecting downwardly therefrom is a dip tube 183 which occupies the groove 177 and communicates with a short fuel line 185 designed for direct connection to the intake 77 of the carburetor with which the tank is to be used. Also carried by the .cover plate is an intake fitting 187 which has means for connection to a suitable fuel line from a fuel pump or other pressure source of liquid fuel. The fitting 187 also embodies a valve seat 189 and a cylindrical guide 191 in which slides a valve member 1'93'having a conical nose 1'95 for engagement with the seat 139 and a body 1'97 which is a prism so as to pass liquid fuel thereby when the valve is open. A bell crank having .a valve operating arm 199 and a weighted float sensing arm 201 is also pivoted on the cover plate 1'31.

When the fuel stands at the proper level, the float 179 will be raised sufficiently to press on the arm 201 and, through the arm 199, hold thevalve 195 closed against the seat 189. If the liquid level tends to fall due to withdrawal of fuel through the tube 183, the float will relax its pressure on the arm 261 allowing fuel to enter past the valve 195 and around the body 197 until the prescribed fuellevel is restored.

A tube 203 makes connection with the float chamber 175 through the cover plate 181, and is connected to the carburetor or intake manifold at some point where manifold depression will be applied thereto. A stand pipe 205 connects to the bottom of chamber 175 and rises to any desired level above the liquid fuel level in the tank 173. By this arrangement, air is caused to bubble through the fuel in chamber 175 and groove 177. This air causes some of the more volatile parts of the fuel to evaporate quickly with a rapid reduction in temperature of the main body of liquid. Thus the fuel is at a temperature sharply reduced from atmospheric when it passes into the metering mechanisms of the carburetor, and is accordingly controlled and regulated with extreme accuracy since any tendency toward premature vaporization has been removed, and metering is performed on a body of fluid which is slightly contracted, as compared with its volume at atmospheric temperature and which is entirely liquid. For best operation the tank of Fig. 16 should be installed so that the plane on which the section is taken is vertical and extends in a fore and aft direction with respect to the vehicle, the intake fitting 187 being forwardly directed.

The carburetor of the present invention also lends itself to use with an auxiliary source of air supply such as a super-charger, in which case the means such as spring 97 or weights 100 controlling the movement of the vanes will be changed to suit the conditions.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

1. A carburetor comprising a body having an upstream section and a downstream section separably connected thereto; each of said sections having an air path therethrough, and being arranged for connection with their air paths end to end to provide a continuous air path through said body; a throttle valve shaft having a throttle valve thereon for controlling the flow of air in said path and rotatably mounted in said upstream section; a fuel inducting nozzle mounted in the air path of said downstream section; an air vane hinged adjacent the upstream end of said downstream section; means urging said vane towards path closing position adjacent said nozzle; a rotary fuel valve connected to said throttle shaft and received in a housing formed on said upstream section; and connecting passages formed in said upstream and downstream sec tions for conducting fuel from said fuel valve .to said nozzle.

2. A carburetor comprising a body having an upstream section and a downstream section separably connected thereto; each of said sections having an air path therethrough, and being arranged for connection with their air paths end to end to provide a continuous air path through said body; a throttle valve shaft having a throttle valve thereon for controlling the flow of air in said path and rotatably mounted in said upstream section; a fuel induction nozzle tube mounted in said downstream section transversely of the air path; a pair of air vanes hinged adjacent the upstream end of said downstream section at either side of said tube; means urging said vanes towards path obstructing position against the sides of said tube; a rotary fuel valve connected to said throttle shaft and received in a housing formed on said upstream section; and connecting passages formed in said upstream and downstream sections for conducting fuel from said fuel valve to said nozzle.

3. A carburetor comprising a body having an upstream section and a downstream section separably connected thereto; each of said sections having an air path therethrough, and being arranged for connection with their air paths end to end to provide a continuous air path through said body, the air path in the upstream section being circular in cross section, and that in the downstream section being larger and rectangular in cross section; a throttle valve shaft having a throttle valve thereon for controlling the flow of air in said path and rotatably mounted in said upstream section; a fuel induction nozzle mounted in the air path of said downstream section; an air vane hinged adjacent the upstream end of said downstream section; means urging said vane towards path obstructing position adjacent said nozzle; a rotary fuel valve connected to said throttle shaft and received in a housing formed on said upstream section; and connecting passages formed in said upstream and downstream sections for conducting fuel from said fuel valve to said nozzle.

4. A carburetor comprising a body having an upstream section and a downstream section separably connected thereto; each of said sections having an air path therethrough, and bein arranged for connection with their air paths end to end to provide a continuous air path through said body, the air path in the upstream section being circuiar in cross section, and that in the downstream section being larger and rectangular in cross section; a throttle valve shaft having a throttle valve thereon for controlling the flow of air in said path and rotatably mounted in said upstream section; a fuel induction nozzle tube mounted in said downstream section transversely of the air path and parallel to one pair of walls thereof; a pair of air vanes hinged adjacent the upstream end of said downstream section and one adjacent each of the walls of said pair; means urging said vanes towards path obstructing position against the sides of said tube; a rotary fuel valve connected to said throttle shaft and received in a housing formed on said upstream section; and connecting passages formed in said upstream and downstream sections for conducting fuel from said fuel valve to said nozzle.

5. A carburetor comprising a body having an upstream section and a downstream section separably connected thereto; each of said sections having an air path there through, and being arranged for connection with their air paths end to end to provide a continuous air path through said body; a throttle valve shaft having a throttle valve thereon for controlling the flow of air in said path and rotatably mounted in said upstream section; a fuel induction nozzle mounted in the air path of said downstream section; a shaft rotatably mounted adjacent one side of said downstream section near the upstream end thereof; an air vane on said shaft positioned for swinging movement in said path and engageable with said nozzle for obstructing said air path and movable to open position by I air flowing in said path, said shaft extending through a wall of said downstream section to the exterior thereof; urging means mounted on the exterior of said downstream section tending to rotate said shaft in a direction to cause path obstructing movement of said vane; a rotary fuel valve connected to said throttle shaft and received in a housing formed on said upstream section; and connecting passages formed in said upstream and downstream sections for conducting fuel from said fuel valve to said nozzle.

6. A carburetor comprising a body having an upstream section and a downstream section separably connected thereto; each of said sections having an air path therethrough, and being arranged for connection with their air paths end to end to provide a continuous air path through said body, the air path in the upstream section being circular in cross section, and that in the downstream section being larger and rectangular in cross section; a throttle valve shaft having a throttle valve thereon for controlling the flow of air in said path and rotatably mounted in said upstream section; a fuel induction nozzle tube mounted in said downstream section transversely of the air path and parallel to one pair of walls thereof; a pair of shafts rotatably mounted adjacent the upstream end of said downstream section and one adjacent each of said pair of walls; an air vane on each of said shafts positioned for swinging movement in said path .and both engageable with said nozzle for obstructing said air path and movable to open position by air flowing in said path, said shafts extending through a wall of said downstream section to the exterior thereof; spring means mounted exteriorly of said downstream section connecting said shafts and tending to rotate each in a direction to cause path obstructing movement of its vane; a rotary fuel valve connected to said throttle shaft and received in a housing formed on said upstream section; and connecting passages formed in said upstream and downstream sections for conducting fuel from said fuel valve to said nozzle.

7. A carburetor comprising a body having an air path therethrough; a shaft rotatably mounted in said body and carrying a throttle valve in said air path; a fuel valve on said body having an inlet and an outlet and including a rotary controlling member on said shaft rotatable therewith; a first passage in said body for connecting a fuel supply with the inlet of said fuel valve; a second passage in said body for connecting the outlet of said fuel valve with said air path downstream from said throttle; a third passage in said body connecting said first and second passages, to by-pass said fuel valve; a by-pass valve controlling the amount of fuel flow in said third passage; a depression sensing diaphragm having an atmospheric pressure side and a sealed depression side with an air outlet fitting, and spring means for urging the diaphragm towards the atmospheric pressure side, the air outlet fitting thereof being connected to the air path downstream from the throttle valve to be effected by manifold pressure; means for connecting said diaphragm to said by-pass valve to open the same when the depression in the air path has a. predetermined low value, to close the same when the depression has higher values; a fourth passage in said body in parallel with and by-passing said by-pass valve; and an idling mixture adjustment valve controlling the fiow in said fourth passage.

8. A carburetor comprising a body having an air path therethrough; a shaft rotatably mounted in said body and carrying a throttle valve in said air path; a fuel valve on said body having an inlet and an outlet and including a rotary controlling member on said shaft and rotatable therewith; a first passage in said body for connecting a fuel supply with the inlet of said fuel valve; a second passage in said body for connecting the outlet of said fuel valve with said air path downstream from said throttle; a third passage in said body connecting said first and second passages, to by-pass said fuel valve; a bypass valve controlling the amount of fuel flow in said third passage; a depression sensing diaphragm having an atmospheric pressure side and a sealed depression side with an air outlet fitting, and spring means for urging the diaphragm towards the atmospheric pressure side, the air outlet fitting thereof being connected to the air path downstream from the throttle valve to be effected by manifold pressure; means for connecting said diaphragm to said by-pass valve to open the same when the depression in the air path has a predetermined low value, to close the same when the depression has higher values; and means responsive to nozzle draft for mixing air with the fuel in said carburetor after the same leaves said fuel valve and before the same is discharged from said nozzle when the nozzle draft is above a predetermined value.

9. A carburetor comprising a body having an air path therethrough; a throttle valve for controlling the flow .of air in said path; means providing a restriction in said path downstream from said throttle valve; a nozzle for introducing fuel into said path in the vicinity of said restriction, said means comprising spring urged vanes mounted in said air path adjacent said nozzle and positioned in path obstructing position; shafts rotatable on parallel axes located at opposite sides of said path, and extending through said body to the exterior thereof, said vanes being mounted each on one of said shafts; urging means mounted exteriorly of said body, and connected with said shafts tending to rotate each in a direction to cause path obstructing movement of its vane, said vanes being displaceable to non-obstructing position in various degrees by air flowing in said path; friction means comprising a pair of V-shaped elements opening in opposite directions, one engaging and supported by each of said shafts exteriorly of said body; and spring means sup- References Cited in the file of this patent UNiTED "STATES PATENTS 1,293,348 Costa Feb. -4, 1919 1,316,545 Schutt et al. Sept. 16, 1919 1,336,070 Coombs Apr. 6, 1920 1,426,570 King et al. Aug. 22, 1922 1,462,641 Jackson et al. July 24, 1923 1,625,787 Braselton Apr. 26, 1927 1,673,306 Ball June 12, 1928 1,832,243 Ritchie Nov. 17, 1931 1,968,553 Heitger July 31, 1934 2,035,191 Reynolds Mar. 24, 1936 2,066,544 Shaw Jan. 5, 1937 2,214,964 Leibing Sept. 17, 1940 2,457,570 Leibing Dec. 28, 1948 2,495,299 Tarter Jan. 24, 1950 2,573,093 Burson Oct. 30, 1951 2,590,972 Johnson Apr. 1, 1952 FOREIGN PATENTS 502,527 Great Britain Mar. 20, 1939

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