US2430806A - Carburetor - Google Patents

Description

Nov, 11,1947. LDE MARCO CARBURETOR Filed Sept. 27, 1945 2 Sheets-Sheet Al .Rim mw 10 w L Il Patented Nov. 11, 1947 UNITED STATES PATENT OFFICE CARBURETOR Louis De Marco, Cleveland, Ohio Application September 27, 1943, Serial No. 503,935

This invention relates to improvements in carburetors, more particularly carburetors for airplane engines where special conditions and requirements, not present in ground vehicles, are encountered.

One of the objects of the invention is the simplication of airplane carburetor equipment and the consequent simplification of the operation of such equipment, without sacriiicing any of the functions heretofore accomplished,

Another object is the provision of a carburetor in which the path for fuel from the pump to the jet shall be short and direct. i

Another object is the provision of a carburetor wherein the volume andproportons of the air and gas mixture flowing to the engine shall be best suited to the requirements under all conditions of engine speed, load, acceleration, and deceleration.

Another object is the provision for airplane engines of large capacity of a carburetor employing a single fuel jet.

A further object is the provision of emergency means under control of the pilot for readily increasing or decreasing the opening of the fuel valve proportionately throughout the range of throttle positions to overcome the effects `of a partial obstruction in the fuel line or to meet any unusual condition requiring a richer or leaner mixture.

Still another object is the provision of means under control of the pilots throttle lever for supplying the necessary rich mixture for take off.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which Fig. 1 is an elevational view, partly in vertical section, of carburetor control mechanism embodying the invention, set at idling position;

Fig. 2 is a detail sectional view taken substantially on the line 2 2 of Fig. 1;

Fig. 3 is a horizontal sectional view taken substantially on the line 3-3 of Fig. 1;

Fig. 4 is a view similar to Fig. 1, showing the control mechanism in the position which it occupies at partially open throttle; and

Fig. 5 is an elevational View at right angles .to that of Fig. 4 showing certain parts in vertical section.

In the drawings I represents a conduit for conducting air past a fuel jet which is indicated at I I. Within the conduit I0 there are two butterfly valves I2 and I3 controlling the ow of air through 18 Claims. (Cl. 12S-98) the conduit.` Valve I2 is a volume control valve, or throttle, manually operated, and valve I3 is a proportioning air valve, governor controlled.

Valve I2 is mounted upon and turns with a shaft I4 to one end of which, outside the conduit, there is attached a crank I5 connected by a link I3 with a throttle control device such as a lever adapted to be operated by the pilot. An adjustable stop I'I determines the idling position of valve I2.

Valve i3 is mounted upon and turns with a shaft I8, to which is attached a crank I9 by means of which the valve is operated. At the free end of this crank there is a roller follower 20 which runs in a cam slot 2l in a lever arm 22 that is adapted to be oscillated upon a pivot pin 23 carried by the conduit I0. The hub of arm 22 also carries a crank 24 to which is pivotally connected a link 25 that is adapted tobe moved back and forth by an engine governor, not shown. When engine speed increases lever arm 22 swings toward the left and causes crank I9 to swing in the same direction, opening valve I3. Decreasing engine speed has the opposite effect.

On the end of shaft I8 opposite crank I9 and outside conduit Il), the shaft carries a guide 26 in which a slide 21 is mounted to move endwise. At its upper end this slide is fo-rmed to provide a box cam 28 in which runs a roller follower 29 for a purpose which will presently appear.

At the lower end of slide 21 there is carried a roller follower 3B which runs in a box cam 3|. Cam 3|, as shown in Fig. 5, is so mounted as to turn about the axis of shaft I8 through a limited angle independently of that shaft. This movement is imparted to the cam through the movements of a link 32 which is pivotally connected with the cam at 33. The lower end of link 32 has a pivotal connection with a crank arm 34 that is fixed upon shaft I4. Consequently when the butterfly valve I2 is moved toward and away from closed position cam 3| is swung clockwise and counter-clockwise, respectively, as viewed in Figs. 1 and 4. Cam 3| has one continuous slot with which the follower cooperates but this slot is divided into two parts, the part 35 substantially concentric with shaft I8 and the part 36 which is eccentric and the radius of which gradually increases away from the central point of the slot. At the juncture of the two parts 35 and 36 there is a rather sudden transition point 3'I which as related to the part 35 is a low spot, and it is at this point that the roller 3|] stands except during acceleration or deceleration of the engine.

Fuel enters the carburetor from a conductor 49 which connects with the bottom end of a fuel valve casing 4| having a valve seat 42. Just above this seat a passage 43 extends from casing 4| to fuel jet II. A needle valve 44 is mounted to slide in casing 4I. When in its lowermost position this valve engages seat 42 and cuts off fuel flow to the jet. Needle valve 44 is connected by a link 45 with the free end of a lever 46 which is adapted to swing normally about a pivot 41 and carries intermediate its ends the roller follower 29 previously referred to. When pivot 41 is stationary, as it is normally, movement of follower 29 up or down raises or lowers link 45 and. moves needle valve 44 away from or toward its4 seat 42. As will be apparent from an inspection of the drawings the roller 29 maybe actuatedeither by the longitudinal movement of slide 21, or by the swinging movement thereof caused by the oscillation of shaft I8 and the guide 2.6 earried thereby.

The adjustment of pivot 41. may be accomplished either manually or automatically, and the automatic adjustment is superimposed upon the manual adjustment. For this purpose the pivot is mounted in a plunger 4 8 withinA a cylindrical upper portion 49 of a post 59that is slidable within a sleeve which in turn is slidable in a housing` 52 carried by a bracket 52 projecting from conduit IIJ. Sleeve 5 I is adapted to be moved up or down by a pinion 53 meshing with rack teeth 54 cut inthe sleeve, the pinion 53 being adapted to be rotated. by a crank 55 and a link 55 leading to an auxiliary lever onv the instrument board of the airplane. Movement of, the sleeve 5I upwardly is communicated through a coil spring 56 to the cylindrical upper portion 4 9 of the post. Downward movement of sleeve 5|. is communicatedto the post through a grooved collar 51 surrounding the post and-,bearing against a nut 58 threaded upon the constricted lower extremity ofv the post. Movement ofv the post downwardly independently of sleeve 5| may also be effected, and this is accomplished b y means of a yoke 59 pivoted at 69 to sleeve 5|, straddling collar. 51 and having a projection 6I extending laterally far enough to be engaged by. a lug 62v which is adjustably mounted upon link 32. The position of lug 62 is such that when thevalve I2 is swung to fully open position, as when an airplane is taking off, yoke 59 will be swung down and post 59 lowered t0 adjust the pivot 41 downwardly, thus swinging lever 25 upon followe1` 29 as a fulcrum andshifting needle valve 44 away from its seat.

In order that pivot pin 41 may be adjusted automatically to compensate for differences in atmospheric pressure at different elevations, plunger 48 is arranged to be moved within the cylindrical portion 49. ofthe post. Fory this purpose a pintle 63 is mounted in plunger 4 8 and extends in both directions from that plunger through slots; 64 in cylinder 49and into cam slots 65 in the two arms of a bifurcated lever 66 which arms are mounted to .turn upon trunnions` 61 carried by the post. The outer end of this lever is pivotally connected atY 68. to thebottom of a metal bellows 69, the upper end of whichis connected at 19 to a plateTI attached to thecylindrical part 49. ofA the post.` Bellows 69 is lled with al gas which isf responsive to pressure changes. Expansion .of the` bellows ,as an airplane ascends causes-the plungerx48 to rise, lifting pivot 41 correspondingly.andswinging lever 4,6. about follower 29 toy lower needle4 valve .44.and thusreduce fuel flow yto compensate for therarefied air.4

Operation-Valve I2. mayr be closed onlyv to engine idling position, and valve I3 may be closed to a somewhat less extent than valve I2. Hence sufficient air for idling will always be available. Assuming that the parts are in idling position, as illustrated in Fig. 1, the operator may open his throttle control to any degree desired, swinging the valve I2 toward open position. As much air as can pass valve I3 in the illustrated position then flows past jet II. At the same time that valve I2 is opened, cam 3 I isswung counter-clockwise and the roller follower 39 is thus caused to ride up from the lo-w spot 31 into the concentric part 35 of the slot, the effect upon the follower 30.bei,ng the same whether the valve I2 is opened a slight amount only or completely opened. Slide 2-1: is thus. cammed diagonally upward through guide 2 6 and thereby pushes roller follower 29 upwardly, imparting a lifting movement to needle valve 44. The mixture is thereby enriched during acceleration. As the engine picks up speed the. governor, acting4 throughv link 25 and crank 2 4, swingsarrn, 22 totheleft, Fig. l-, which works through. cam slot 2| and follower 2) tov swing crank arm I9; andy shaft I8 gradually counterclockwise, thereby moving valve I3 toward open position. At the same timeslide 21 is also swung counter-clockwise and the. cam 28 thereby acts upon, the follower 29A to swing lever 46v upward and1 further open. the fuel valve in proportion to the air which isv permitted to flow throughy the conduit IIJ*l in respQnse-to enginevvacuum. The formy of. camy 28may besuch as to vary the proportions of the mixturetoeffect thebest results for different engine` speedsv or, loads. Ifr we assume that the operator haso-pened-histhrottle to the extent indicateddnlig, 4, the gradual2 swinging of slide 2.1- counterclockwisewill.finally bring itv to the position of Fig; 4A, when the followerl 3G will descend into the cam low spot 31, whereupon the slideV 21 will be lowered andithe enrichment o f the mixture f or.A acceleration. will. be discontinued. In other words as soon asA the valve I3 by action ofl the governor hasfollo'wed. proportionately the opening movement. of valve I2, the mixture is returned` to normal. Similarly if the. operator shouldthen advance Vthe throttle further cam 3| would be swung furtherI counter-clockwise andthe slide 21 wouldagain bel raisedand held raised until the. follower 3DI again reached low spot 31. The enrichment of the mixture isnot merely, momentary, but. continuesuntil. the acceleration is concludedi. When it, automatically ceases.-

Uponv deceleration. anopposite effecty is experienced. Whentheoperator movesvalve I2. from tlneposition-of Fig, 4 to that ofy Eig. 1, thereby suddenly. reducing tlfieflowV of air, it is obviously desirableI that. the fQW of fuel bel correspondingly reduced. The. governor-however tends to slow down theclosingofthefuelvalve, in other words to make it proportionate tothe gradual deceleration of the. engine.v Obviously this would be undesirable as the high vacuum induced Withthe valve I2, closed-would draw `quantities of raw gas into the engine cylinders. Theportion36 of the slot incam 3| prevents thiscondition, for when the valve I2, isswungto closed positionfrom the position of Fig. 4.for example the. portion 36 of.

a rich mixture enabling smooth engine operation will be maintained as long as acceleration is continued, and no longer. Furthermore the volume of the charge will be accurately proportioned to engine speed by the joint operation of valve I3 and the fuel valve, through the action of the governor. In other words, exactly the right amount of mixture will be fed to the engine at each moment of engine acceleration. In addition, the configuration of cam 28 is made such that under any given speed or load condition the ratio of air and gas making up the mixture is the optimum for that condition, that is to sai7 the ratio may be varied gradually from closed throttle to wide open throttle in order to automatically fit the mixture to the requirements of the engine.

An airplane engine must be operated to its full capacity at times, particularly on the ,take oif and also during power dives, and an extra rich mixture should be provided for those relatively short periods, not only because extra power is required at those times but also because the presence of raw gas in the mixture has a cooling effect upon the engine valves. The usual equipment includes a control on the instrument 'board which must be operated by the pilot, necessitating thought as well as manual action, following as well as preceding the extra power requirement. In accordance with my invention this procedure is simplified. The pilot in operating his engine for the take off, for example, gradually advances his throttle lever to bring the engine up to top speed, and when that has been attained the final actuation of the lever causes lug 62 to engagethe extremity 6| of bifurcated lever`59 which results in pulling down pivot pin 41 against the action of spring 56 and imparting an extra lift t0 needle valve 54. As soon as the take oif is completed the pilot retards the throttle to the extent necessary to reduce engine speed to take care of the reduced load, and the rst effect of that retardation is to enable spring 56 to return pivot 41 to its normal position. If desired, of course, the throttle lever may be provided with a catch, the purpose of which is to prevent movement to the extent necessary to operate lever 59, the catch be adapted to being withdrawn by the actuation of a thumb release or the like. Hence the pilot is enabled to provide extra rich mixture for the take off by manipulation of the throttle lever only, andthe operation becomes practically automatic. Furthermore he cannot overlook returning the mixture to normal immediately after the take off is completed.

The instrument board control mentioned above as conventional equipment ordinarily has four positions which may be termed full rich, auto rich, auto lean and shut ofi. The auxiliary lever in my invention, connected to link 55', is not needed for full rich control, that being effected by the lug 52 above referred to under control of the throttle, and instead of having definite positions the lever may shift to any position between auto rich and shut off. For cruising the auxiliary lever is retarded somewhat to lean the mixture to whatever extent is required. It is also available as an emergency control to enable the pilot to change the mixture whenever any unusual necessity for so doing may arise. For example if extraneous matter should get into a fuel passage and cause a partial blocking of the same, resulting in reduced power, the pilot may quickly compensate for that condition by manipulation o f his auxiliary lever to pull down the pivot 41 and impart a raising movement to the fuel valve. This is an important safety feature and may on occasion spell the difference between reaching a landing eld and attempting a forced landing elsewhere. Furthermore, if something should go wrong with the automatic regulation of the mixture for high altitudes, the pilot may operate his auxiliary lever to raise pivot l1` and reduce the richness of the mixture. This lever may also be operated to raise pivot 41 far enough to cause needle valve 44 to engage its seat 42 and thus completely cut off the flow of fuel.

The operation of the herein disclosed means for automatic adjustment of pivot 41 by means of bellows 69 will be obvious without further explanation, but attention should be called to the fact that this adjustment means is superimposed upon the manual regulation of pivot 41. In other words it functions regardless of the position of the sleeve 5I, which is controlled by the emergency lever.

It is sometimes beneficial to add to the gas and air mixture drawn into an engine a fluid such as alcohol or water or a mixture of the two. The means herein disclosed may be employed to control the addition of such a fluid or any other fluid benecial to engine operation. Hence where the term fuel is employed herein it should be construed broadly enough to include fluids other than gasoline, whatever their function may be.

In the foregoing description I have necessarily gone somewhat into detail in order to explain fully the particular embodiments of the invention herein illustrated, but I desire it to be understood that such detailed disclosures are not to be construed as amounting to limitations except as they may be included in the appended claims. Having thus described my invention, I claim: 1. In a carburetor, an intake conduit, two air valves therein, a fuel jet and a fuel valve therefor, manual means operatively connected with one of said air valves for controlling the volume of mixture leaving the carburetor, and governor actuated cam means operatively connected with said fuel valve and the other of said air valves for controlling the quantity and proportions of the mixture.

2. In a carburetor, a fuel jet, a fuel valve, an air intake conduit, two valves in said conduit arranged to control air flow past said jet, manual control means connected with one only of said air valves, means for operatively connecting the second of said air valves to a centrifugal governor, and means operatively associated with said second air valve for moving said fuel valve.

3. In a carburetor, a fuel jet, a fuel valve, an air intake conduit, two valves in said conduit arranged to control air flow past said jet, manual control means connected with one only of said air valves adapted upon opening movement initially to increase the opening of said fue] valve slightly, means for connecting the second of said air Valves to a centrifugal governor, and means operatively associated with said second air valve for moving said fuel valve.

4. In a carburetor, a fuel jet, a fuel valve, an air intake conduit, two valves in said conduit arranged to control air ilow past said jet, manual control means connected with one only of said air valves adapted upon movement toward closed position initially to reduce the opening of said fuel valve, means for operatively connecting the second of said air valves to a centrifugal governor. and means operatively associated With said second .air valve for moving said fuel valve invariable ratio therewith.

5. In a carburetor, a valve, 'and twoicontrols therefor Vcomprising the following "parts, Van os# cillatable guide, a slide movable in said guide,lcam means for so moving said slide comprising an element on said slide and an element independently oscillatable about the axis of said guide, and means operatively connected with said valve adapted to be actuated by either the slidingmovement or the swinging movement of said slide 'for operating said valve.

6. In a carburetor, a valve and two controls therefor comprising the following parts, an ,oscillatableguide, a slide movableinsaid guidegrst cam-.means for so moving saidslidefcom'prising an element on said slide andan l,element independently :oscillatable .about theaxisofsaid guide, .a second cam nmeans comprisingan 'element :on `said slide `and an element operativelyconnected said valve, whereby longitudinal movement v.of said slide resulting from actuation of said irst cam means or swinging vof said 4slide `resulting from oscillation of said guide will function through said .second cam means to operateaid valve.

,'7. In a carburetor, .a valve and `two controls therefor lcomprising the following parts, an oscillatable guide, a slide movable .in saidlgude, aa rstcam means for so moving .said'slideoomprising an-element on said slid'eand'an'element independently .oscillatable about 'the axis .of said guide, a second cam means comprising afcam on said slide in a plane at right l,angles to',the.,axis of Vsaid guide and a follower, said followerbeing operatively connected with said valve, whereby longitudinal movement of fsaid slide `resulting from Aactuation of said rstcam meansior'swinging of said slide'resultingfromoscillation ofisaid guide will function through `said .second cam means to operate said valve.

8. In a carburetor, a valve, and twocontrols therefor comprising the `following parts, an .oscillatable guide, a slidemovable in said guide, cam means for so moving said slide oomprisingnn element on said slide and an elementfindependently oscillatable about the axis .of said guide, means operatively connected with said'valve and adapted to be actuated by Aeither the .fsliding movement or the swinging movementof said slide for operating said valve, and cammeans forroscillating said guide.

`9. lIn a carburetor, a 'fuel valve, an air '.valve, an oscillatable cam, a slide carrying a rfollower cooperating with said cam,anr-operative.connection'between said slide and said fuel valve, anoperative -connectio-n between said air k'valve and said cam, said cam being Lso -shaped'that'at the start only ofeach movement ofsaid air 1valve :.to- Ward open position saidslide vwill be moved :toward fuel valve opening position, andmeansde pendent upon increase'of engine speed forlcausing said follower to resume its original .-positionfrelative` to the cam.

l0. In acarburetonmanual controlmeansse'ttable to call for a given engine'speedand*governor controlled-means for supplying-andpropon tioning the necessary air and fuel-'during accel eration to the engine speed corresponding lwith that setting and for running'econom'ically atthat speed under existing load conditions.

11. In a carburetor, m-anual eontrol'fmeansfsettable'to call for a given engine speed, governor controlled means for supplyingthe necessary air and fuel for the engine speedcorresponding with 8 that :setting under existing load conditions, rand means actuated by :the movement of said manual control means toa lower speed setting for immediately :reducing .the :air 'and fuel supply.

i12. .1nl acarburetor, manual control means'settable'to call fora given engine speed, governor controlled means for supplying the necessary air and fuel -forthe'engine speed corresponding with that setting under 'existing load conditions, said manual control means .functioning also to add a predeterminedincrement to the fuel supply upon movement vof the manual control means to a higher speed settingfandsaid governor controlled means actingthrough said manualcontrol means to .subtract a correspondingincrement from the fuel supply when the engine speed increases to the point called for by said manual oontrolfmeans.

`13. In va carburetor, manual control means settable to call for a given engine speed, and governor controlled means for supplying the necessarylair andfuel for theengine speed corresponding with that setting under existing vload conditions, said manual control means when moved toward idling position functioning independently of said governor controlled means for reducing the fuel admitted to the carburetor.

14. VIn a carburetor, a fuel valve, manual control means settable to call for a given engine speed, governor controlled means 'for supplying the necessary air and fuel for the engine speed corresponding vwith that setting, a'lever having vthree pivot points, one constituting a fulcrum,

one'operatively connected with said fuel valve and one constituting a point of force application Yresponsive to movements of said governor controlled means, said manual control means when set at a point in the maximum speed range under heavy load conditions functioning further to set said fulcrum pivot in a position to augment the fuel valve opening ability of said governor controlled means.

lo. In a carburetor, a fuel valve, an oscillatable manual control means embodying a cam, said means being settable t0 call for a given engine speed, a guide oscillatable about the axis of said manual control means, a slide in said guide having a Vfollower cooperating with said cam and occupying a 'given relation Awith said cam under normal running conditions, an operative connection between said slide and said fuel valve, said cam being so shaped that movement of said control means in one direction will act through said follower to shift said slide toward fuel valve opening positiomand means dependent upon engine speed, following a setting of said manual controlfor higher speed, for causing said follower to vresume its normal position relative to said cam.

"16. "In a carburetor, a fuel valve, an oscillatable manual control means embodying a cam, saidmeans being settable to call for a given engine speed, a guide osolllatableabout the axis of said manual control means, a slide in said guide having a follower cooperating with said cam and occupying a given relation with said cam under normal running conditions, anfoperative connection between said slide andsaid fuel valve, said cambeing so shaped that movement of said control means in one direction will act through said follower to-sliift said slide toward fuel valve closing position,.and meanszdependent upon engine speed, following a setting of said manual control for lowel` speed, for causing said follower to resume its normal position relative to said cam.

117. In a carburetor, manual control means settable to call for a given engine speed, governor controlled means for supplying the necessary air and fuel for the engine speed corresponding with that setting under existing load conditions, said manual control means functioning also to increase the fuel supply upon movement of the manual control means to a higher speed setting, and said governor controlled means acting through said manual control means to decrease the fuel supply by a corresponding amount when the engine speed increases to the extent called for by said manual control means.

18. In a carburetor, manual mechanism for opening the iue1 valve to an idling extent and for providing a power demand by setting a limit upon air ow, and automatic mechanism responsive to variations in engine speed for providing and proportioning the fuel and air required for that power demand.

LOUIS DE MARCO.

REFERENCES CITED The following references are of record in the file of this patent:

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