US1994944A

US1994944A - Carburetor

Info

Publication number: US1994944A
Application number: US290393A
Authority: US
Inventors: Cole Don
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-07-05
Filing date: 1928-07-05
Publication date: 1935-03-19
Anticipated expiration: 1952-03-19

Description

D- COLE CARBURETOH Original Filed July 5, 1928 5 Sheecrs-SheefI 1 .wm ni h uw ES S N. mw I. IHN u( wk wk 1 I QQ u.- Il mm 1 'M |W| in U11 .Q w @d H ||1 |ll I mw w@ :M w .wl l1 www mi |MW|MQQ\\ MN N HH, -NM IIHI u @Mv um .Mh .nu @n Q n@ was wm w Q A rk Mm, www QQ N MN b\ n ,ww Q Q mm am ww N www March 19, 1935.

CARBURETOR Original Filed July 5, 1928 3 Sheets-Shree?l 2 i@ ai D. COLE 1,994,944

March 19, 1935. D, COLE .1,994,944

l CARBURETOR Original Filed July 5, 1928 3 Sheets-Sheet I S wvwwaewwawa PatentedvMar. 19, 1935 UNITED STATES "PATENT OFFICE Application July 5,1928, VSerial No. 290,393

Renewed December 3, 1934 20 Claims.

My invention relates to carburetors and is more particularly concerned with the provision of improved means .for supplying fuel for acceleration of the engine and certain other features of con. struction.

- The present invention is an improvement upon the device disclosed and claimed in my copending applications, Serial No. 189,983, filed May 9th, 1927, and Serial No. 629,555, filed August 19, 1934.

The accelerating device, commonly termed a pump or syringe,` of the present ,invention involves the graded volumetric discharge and the protracted period of discharge disclosed in my earlier application, and also includes the cut-ofi' valve for disconnecting the discharge passageway of the'syringe from the fuel nozzle of the carburetorf According to the present invention, however, the cut-olf valve and outlet port are disposed at the upper end of the discharge stem.

This construction facilitates manufacture and provides improved operating characteristics, one feature of which is the automatic thermostatic control of' the syringe or accelerating device.-

Also by collapsing the accelerating device over the stem the overall length of the device is decreased, and assembly and disassembly are facilitated.

Another feature of the present invention is an improved form of well and main nozzle construction which both facilitates ymanufacture and improves the operating characteristics by render' ing the accelerating well less=rsubject to surface tension. Where an accelerating device of the pump or syringe type is' employed, an accelerating well as such is not strictly essential. Air bleeding of the main jet is, however, desirable, and such air bleeding is best accomplished by an atmospheric or air passageway which partakes of the characteristic of an open well. To render the air bleed highly sensitive it is desirable to diminish as much as possible the eiect of the surface tension of the liquid. I provide, according to the present invention, a form of air bleed which accomplishes this purpose and which is peculiarly advantageous in connection with-an accelerating device of the pump or syringe type.

'I'here are certain other features of construction which will be more apparent from the following detailed descripton and drawings of a. device embodying my invention. f

Now in order to acquaint those skilled inthe art with the manner of constructing and operating a device embodying my invention, `I shall de- V,scribe in connection with the accompanying drawings a speciiic form of carburetor in which the invention appears.

Inthe drawings y l Fig. 1 is a diagrammatic section through 4a carburetor, embodying my invention. 5

Fig. 2 is a fragmentary'sectional view showing a modified form of high speed adjustable needle which is the equivalent of the metering orice shown in Fig. 1.

Fig. 3 is a fragmentary sectional view showing 10 the accelerating device in the position it occupies when the engine is running at low speed.

Fig. 4 is a similar' view showing the accelerating device just after opening the throttle valve of the carburetor. l5

Fig. v5 is a view similar to Figs. 3 and 4, showing the accelerating device with the throttle open and the engine running at high speed.

Fig. 6 is a fragmentary view of a modified form of accelerating device employing a thermo- 20 static control needle.

Fig. '7 is a diagrammatic sectional view showing the connections between the choke and the auxiliary needle valve employed during `the warming up period of the engine the priming 25 device controlled by the throttle being omitted for the sake of clearness.

" Fig. 8 is an enlarged view of the idling device during idling action; and

Fig. 9 is a fragmentary sectional view of a mod- 30 iication.

In the actual construction of the carburetor the main body of the carburetor is constructed of two die cast parts, although obviously this may be varied, these parts having suitable pas- 35 sageways formed therein and provided with ttings to complete the construction. When so formed the carburetor consists of a main body portion 1, a cover portion 2 and a barrel portion '1.

The main body portion 1 provides the air inlet 3 40.

or air horn, in which there is disposed the butterfly choke valve 4 mounted on a transverse shaft 5. The body portion 1 also. contains a suitable cavity 6 defining the float -chamberor fuel supply chamber. lThe vertical Vbarrel '7 provides the 45 outlet 8 surrounded by the bolting or attaching flange 9 of well knownconstruction. A Venturi member 10 is disposed partly in the body member 1 and extends up into the barrel 7.

'I'he outlet is controlled by butterfly throttle 50 valve 12 mounted on a transverse stem or shaft 13. The space between the throttle valve 1,2 and the nozzle 14 is commonly termed the mixing chamber 15. The nozzle 14 is disposed at an angle to facilitate construction and to shorten the 55 passagewa'ys and it terminates slightly above the most restricted part of the venturi 10 according Ito known practice.

21 which extends downwardly from the cover member 2. The valve body 18 is threaded into an opening in the wall of the cover member 2 which leads into the chamber 22 containing the screen or strainer 23. The chamber 22 is provided with a removable cover in the shape of a threaded plug 24 through which access may be had to the thimble-shaped strainer 23. The body 18 extends for a short distance above the bottom wall of the chamber 22 to prevent sediment and impurities which might escape the strainer 23 from being washed directly into the passageway through the valve body 18.

A float 25 is provided with a lever 26 hinged at 27 to a depending stem 28 preferably formed integral with the cover member 2. The arm or lever 26 has a suitable stop 29 adapted to engage the lower end of the stem 28 to prevent the float 25 from resting against the bottom wall of the float chamber 6, thereby to avoid injury to the same. Under the control of the float valve 17 the level of fuel is maintained substantially asxindicated at line 30, and the same level tends to prevail throughout all connected passageways and chambers including the nozzle 14.

The level of liquid is preferably maintained slightly below the outlet end of the bore 32 of the nozzle 14. The nozzle 14 has an integral polygonal collar or shoulder 33 which is adapted f to seat against the upper surface of the boss 35,

a suitable gasket being interposed to provide a tight joint. The nozzle 14 comprises a sleevelike member threaded as at 36 at its lower end to receive a clamping nut 37 which also bears against a shoulder as at 38 through the intermediary of a gasket to maintain a tight joint. The boss 35 has a cylindrical bore 39 in which the sleeve-like bodyl of the nozzle 14 fits relatively closely. The body of the nozzle within the bore 39 has a series of grooves such as 41, 42 and 43 communicating `with the bore 32 through corresponding orifices -is concerned, but of suilicient cross section `to permit the necessary flow of air without serious interference from the surface tension of the liql,

` throttle and thereby supplies a larger quantum uid. If the passageway 47 were an annular` passageway about the stem ofthe nozzle 14, the radial ldimension of the same would have to be kept very small to avoid undesirable capacity or gasoline content, and by the present construction I have avoided such narrow passageway in which surface tension might have a very considerable effect.V

.The passageway 47 communicates with a restricted atmospheric passageway 48 that leads through an enlargement 49 to a recess 50 in the barrel member and a downwardly extending passageway 52 in the Venturi member 10, thereby leading to atmosphere th'iough the air horn 3. The groove 47 also communicates through a passageway 53 for supplying liquid fuel to the idling device 54, which idling device is located at the throttle valve 12. A connecting tube or idling tube 55 is threaded at 56 into the body of the casting 1 in communication with the passageway 53, and extends above the parting plane or line of the body member 1 and the barrel member 7. The upper end of the idling tube 55 telescopes in the passageway 57 leading to the idling device 54.

The idling device, which is shown more in detail inl Fig. 8, comprises a chamber 58 formed in the boss 59. 'Ihis chamber 58 communicates with the idling tube 55, the idling tube 55 supplying liquid fuel to the chamber 58 when suiicient suction is imposed upon the chamber 58 to raise gasoline to that level. The upper and lower ends of the idling tube 55 are constricted to control the rate of ow to the idling device. The chamber 5 8, in addition to its communication with the'idling tube 55, has an air inlet pasageway 60 valve has a suitable adjusting head 63 and a stem 64 threaded into the boss 59. 'Ihe air passageway 60 communicates with the valve chamber 65 and the chamber 65 in turn communicates with the main bore of the carburetor through a passageway 66 extending through the upper end of the venturi 10 and terminating in a port 67, which, when the throttle valve 12 is closed or substantially closed, receives air' at substantially atmospheric pressure by way of the air horn 3.

The chamber 58 has two passageways 69 and leading to the main bore of the mixture passageway in the barrel member 7, the passageway 69 extending above the throttle 12 when in closed position, and the passageway 70 extending to a point below the throttle valve 12 when it is in closed position.

As shown in Fig. 8, when the engine is running at low speed with the throttle valve 12 closed, a

relatively high suction prevails in the main pas- -sageway above the throttle 12, subjecting the passageway 69 to such high suction. In response to this suction or; depression, liquid ows from the idling tube 55 which is suitably connected to the main liquid fuel supply chamber, as will be explained later, and air flows in through the passageway 70 into the chamber 58 and air under regulation also iiows in through the port 67, passageway 65 and air port 60 past the needle valve As the throttle valve positionthe first result thereof is to pbstruct the passageway 70, diminishing the ow of air into the chamber 58, and consequently increasing the liquid flow through the passageway 69. Since some air is admitted around the throttle when it is thus moved towards open position, theadditional fuel flowing through the passageway 69 mixes with the air moving past the edges of the of mixture for operating the engine.

12 is moved towards open When the throttle 12 ismoved still further supplies the requirements of the engine. Y

sure upon the port 67 and also is accompanied venting rapid iiow of liquid thereby and to proby a lower degree of suction upon the ports 69 vide lodgment for particles which might otherand 70, but such increase of air flow draws fuel wise tend to bind the two parts together.

from the main supply nozzle 14. Thus -as the The piston 101 isprovided with aoonical valve idling device becomes insuicient or tapers olf face 102 at its upper end and acentral bore, which its function, the main jet comes into eiIect and central bore is guided on a stem 103. The stem 103 has a conical head 104 at its upper end con- Fuel is supplied from chamber 6 to the main taining a radialA passageway 105 communicating nozzle and to the idling tube through a paswith the axial passageway 106 extending longisageway 72 indicated in dotted lines in Fig. 1.`tudinally of the stemand opening at the lower 'I'his passageway is controlled by a metering oriend of the stem into the passageway 87. A comce 73 mounted in a removable plug 574 having pression spring 107 is disposedbetween the botan external polygonal head 75 inserted at its tom wall of the oat chamber 6 and the piston inner end into the metal of the body member 1. 101, the piston being recessed annularly to re- The orice 73 is formed preferably as a xed ceive the upper end of the spring. The lower opening `in a thin metal plate which is cupend of the stem 103 is threaded in a boss 108, shaped to be suitably disposed in the end of the which boss guides the lower end of vthe 'spring hollowplug 74. 107.

In lieu of the orifice plate, a metering restriction may be formed by a needle valve 76 cooperdepressed any liquid which is contained within It can now be seen that if the cylinder 90 is r ating with a valve port 77, as shown in the modithe cylinder will'transmit pressure to the upper 4iication of Fig. 2. Needle valve 76 has a stem 78 end of the piston 101 and force the `same downextending through a packing device 'I9 to prewardly against the spring 107, thereby opening vent leakage, and having a head 80 at its outer the valve port 105 and permitting the discharge end by which the position of the needle 76 may be of liquid therethrough and through the passageadjusted with respect to the port 77. way 106 into the passageway 87 and from thence The main Apassageway 72 terminates in an to the passageway 32 of the nozzle 14. opening -82in the chamber 81, which is formed If the piston is held down, the spring 107 by as an enlargement of the bore in the boss 35. its recoil drives the piston 101 upwardly, ex-

The lower end of the bore is closed by a drilled pelling liquid until the valve face 102 closes thel screwvplug 83. The screw plug 83 has a central` port 105 and thereby both limits the upward passageway 84 communicating with a diametritravel o f the piston 101 and closes off communical passageway' 85.which at its ends communicates with a groove 86. Ilhe groove 86 in turn communicates with a passageway 87 extending along the bottom of the carburetor body 1 and having two connections, one with the accelerating device 88 and the other with the economizer 89 Fuel from ether'the accelerating device 88 or the economizer`89 is thus delivered through the passageway 87, groove 86, bores and 84 to the chamber 83 below the nozzle 14 and -in direct communication with the bore 32 thereof.

The accelerating device 88 comprises a movable cylinder or sleeve 90 closed at its upper end by the head 92, which head has a ball and socket connection 93 with an operating rod 94, this rod being hinged or pivoted at 95 upon the lever 96. The lever 96 at its other end is hinged for swinging movement at 97 in a boss formed in the barrel portion 7 of the carburetor.

Anoperating arm 98 bears at its outer end a roller 99 and is fastened at its inner'end to the throttle shaft 13. The lever 98 is termed the throttle syringe lever, and the lever 96 is termed the syringe lever. It will be observedthat for -motion of the throttle shaft in opening the throttle valve 12 the roller 99 bearing down upon' the lever 96 forces the same downwardly and thereby causes the cylinder or sleeve member 90 to be depressed. However, for upward motion of the throttle syringe lever 98'the`arm 96 need not follow upwardly since thereis no positive connection for upward motion of the two The syringe lever is provided with a. spring -100 disposed about the Divotalpoint .97 tending at all times to raise the lever and the cylinder 90 with it. 'rnefspring 19o raises tneiever .9s and piston 101 which plays with a relatively brings it against .the roller` .99 tending thereby to close the throttle valve 12. Y The cylinder 90 is provided with a movable loose fit therein. The piston 101 is provided 'with a series off grooves to facilitate the desired action ofprecation between the interior of the cylinder 90 and the nozzle 14. In eilect the piston forms an overrunning valve for the port 105.

Upon upward motion of the throttle 12 towardsclosed position thespring 100 tending to raise the syringe lever 96 creates a' drop of pressure -inside the cylinder 90 and liquid ilows into the same'throughthe clearance between the piston and the cylinder.

It will be observed that the upper end of the cylinder 90 extends above the liquid level 30, and the cylinder in operation becomes illled with liquid which may be held at a level above the normal level 30. It will be appreciated that the discharge port 105 comes very close to the cylinder head 92 when` the cylinder 90 is fully depressed, and the cylinder 90 is thereby evacuated of any air which might tend to be trapped in the same. It is to be observed that the cylinder 90 forms an inverted cup o r bell which provides a relatively important function in providing an automatic thermostatic control which will be described later. f .The'stem 94 passes loosely through a hole in the cover member 2, which hole is covered by a .sheet metal washer 109 embracing the stem 94 with sumclent freedom to permit the stem toplay freely up and down, the washer109 playing sidewise.

t 'Ihe carburetor constructed as aforesaid tends to 'give a mixture which becomes too lean at wide open throttle, and .I' have provided, therefore, an economizer 89 which operates to open an auxiliary restrictedeway for fuel between the float ehambero and the bore of the nozzle 14 plug 113 contains transverse openings -114 leadring to a central passageway 115 controlled by the valve 110 and its seat 1-11. The. upper end 75 of the plug 113 serves to guide the stem 116 of the valve '110, this stem extending up through a hole inthe cover and lying in the path of the syringe lever 96 so that when the syringe lever is depressed by wide opening of the throttle the economizer valve 110 will be opened. A spring 117 about the stem 116 tends at all times to close the valve 110.

The rate of fuel flow through the economizer passageway 112 is controlled by a metering orifice 118 formed in a thin plate, this plate having flanges to seat the same in the upper end of a removable plug 119. 'Ihe plug 119, like the plug 74, may be removed for the purpose of substituting a -plate of a larger or smaller metering orifice. `By the means of this economizer the tendency of the fuel mixture to grow too lean at wide open throttle is counteracted. By constructing the economizer separate from the ac-l celerating device each may have its own proper adjustment without interfering with the function-of the other. The rate of fuel discharged from the accelerating device or syringe 88 is controlled by the spring 107-and by the size of the valve port 105. Preferably these features are so arranged as to' give a protracted discharge as distinguished from a sudden. injection of a relatively large mass of fuel into the air stream.

In Figs. 3, 4 and 5 I have illustrated diagrammatically the operatiunI of the accelerating deviceor syringe. In Fig. 3 cylinder 90 is fully raised and is filled with liquid fuel. The throttle is closed and there is not suflicient suction on the nozzle 14`to cause fuel to flow therefrom. In Fig. 4 thethrottle has been opened, fully depressing thficylinder 90, causing suction to be imposed upon Athe nozzle414 by the opening of the throttle and fuel to be discharged through the port 105, passageway 106, from the accelerating' device. Such downward motion of the cylinder 90 forces the piston 101 downwardly since the liquid is not appreciably compressible, and

. while a part of the liquid escapes through the clearance between the piston and cylinder, the

major part thereofis driven through the discharge passageway to the nozzle 14. The pressure on the liquid in the cylinder 90 forces the piston 101 down against the spring 107 opening limit of motion where it cuts oif the discharge port 105 Vto prevent suction on the nozzle 14 from drawing fuel through the accelerating device or pump 88.

, Now I wish to call attention to an important function which .this structure inherently provides,

namely, thermostatic control of the vquantity of liquid fuel discharged by the accelerating device.

It has been found that when the engine is fully warmed up and atmospheric temperature is relatively high, the amount offuel required for proper acceleration should be reduced in proportion generally to the temperature rise. The device of my invention automatically graduates the quantum discharge per given displacement of the cylinder l 9011i accordance -with temperature rise for the of fuel should be decreased. It is to be observed that the cylinder 90 when fully extended has its upper end lying above the gasoline level in the 'I'he inverted bell shape of the movable cylinder member 90 traps the vapors or gases so evolved and holds them against escape since the cylinder 90 is liquid sealed at its lower end. When gas or vapor is thus formed within the cylinder 90, depression of the cylinder corresponding to opening of the throttle drives out this liquid, with the result that the discharge of the accelerating device is graduated in accordance with temperature.

If desired, a separate thermostatic element such as the thermostatic spring 121, bearing a valve member 122 controlling the port 123 in the upper part of the cylinder member 90, may beprovided. Such thermostatic spring 121 may be made of a piece of bi-metallic thermostatic "metal, one end being anchored to a boss 124 and the other end being free and bearing the valve member 122. However, I find that the structure shown in Figs. 1, 3, 4 and 5 automatically compensate for temperature changes to meet the requirements of the engine to a highly satisfactory degree.

In Fig. 7 I have illustrated the warming up control which-is preferably employed with the carburetor shown in Fig. 1, this warming up control having been omitted from Fig. 1 for the sake of clearness.

A passageway 125 including theneedle valve port 126 communicates with a well 127 formed in the body portion 1, said well extending upwardly above the level 30 of fuelin the chamber 6. The well 127 contains stem 128 of the needle valve 129, which controls the port 126. The stem 128 is guided in a suitable guide 130 in the well 127 adjacent the lower end thereof, and is suitably guided in an extending flange 131 of the barrel member 7.

The needle valve 129 is urged downwardly by a compression spring.132, tending at all times to close the port 126. A discharge passageway 133' communicates with the bottom of the well 127 at its lower end, and at its upper end communicates with a discharge port 134 formed in' the constricted part of the Venturi member 10. 'The stem 128 has a head 134 at its upper end,` which head rests upon the end 135 of a bell crank'lever 136 pivoted' on the side of the barrel member 7. 'I'he otherarm of the bell crank lever 136 is indicated in dotted lines at 138, and this arm lies in the path of a cam member 139 which is attached to the shaft of the choke valve'4.

The cam member 139 is channel-shaped so that the flanges thereof lie on opposite sides of the edge of the lever arm 138. The bell crank lever 136 is preferably formed of sheet metal, and it has its end 135 formed in the shape of a hook or bend encircling the stem 128. 'I'he web of the channel of which the cam member 139 is formed is extended andwrapped aroimd the choker valve shaft 5 to form -a split clamp held by means of the screw 141 in adjustable position on said shaft.

\ The shaft 5 is preferably lcontrolled by a manual operating member such as a Bowden cable and a lever attached to the shaft 5. 'Ihe cam member 1355 is so Shaped asto start to lift the 'needle valve 129 upon av slight change of position of the lchoker valve 4, thus opening up the auxiliary "needle valve 129 without greatly obstructing the air iiow. In this manner additional fuel may be thrown into the air stream at a point where it will be effectively mixed with the infiowing air in the venturi 10. At the same time the choker valve 4 can be closed if desired. The upper part of the cam member 139 is substantially concentric with the shaft 5, so that after the valve 129 has once been completely opened further motion thereof is not required.

By this means additional fuel can be effectively Fsupplied without cutting olf the air supplied to the carburetor, and yet if it is desired to put the carburetor under suction, the choker valve 4 can be closed.

While the metering restriction for the accelerating device 88 is provided iii-radial port 105, I may, in order to facilitate change of such orices, insert a removable plug bearing an orifice plate, through the bottom wall of passage 87 as is done in the main metering orifice 73.-A

The injection of the accelerating fuel through passageway 84 into chamber 81 directly in line with the bore 32 of main nozzle 14 facilitates the promptresponse of the carburetor to the action of the accelerating device. In a large size of carburetor I have extended a small pipe 141 integra1 with plug 83 and forming a continuation of passageway 84, up inside the nozzle 14 to a point a short distance below its outlet, as shown in Fig. 9. By this arrangement the discharge of the accelerating device 88 is delivered directly into the air stream with minimum impedance and with practically no back flow through the main passageway 72 and main orice 73 and no dissipation into the passages or spaces communicating with the main nozzle. In other words, the syringe action then becomes more pronounced. The economzer valve 110 may open into the same passageway 87 as shown in Fig. 1, when the additional nozzle tube 141 is employed, as shown in Fig. 9, or it may open into the main passageway 72 as desired.

` It is believed that the operation of the device herein disclosed and illustrated will be apparent from the foregoing description. The air bleed to the main nozzle 14 occurs through the passageways 52, 50,'48 and the groove 47 tothe successive openings 44, 45 and 46 as the suction upon the nozzle 14 increases.

While in the preferred form of my invention the accelerating device fills through the clearance between the piston and cylinder and thereby secures a delay in filling so that successive rapid operations of the throttle valve will not continue to discharge fuel, it will be `apparent to those skilled in the art that this detail may be varied without departing from the scope of the invention.

I do not intend to be limited to the details shown and described except as they are recited in the appended claims.

I claim:

1. In a throttle controlled carburetor, an accelerating device comprising a collapsible chamber having a movable wall actuated upon operation of the throttle, a hollow stationary discharge stem having a sliding fit with said wall of the chamber, said-chamber wall and stem having cooperating valve parts for shutting oif communication between -said chamber and the hollow stem.

2.In a throttle controlled carburetor, an accelerating device comprising a collapsible chamber having walls movable relative to each other, a discharge stem having a discharge passageway for fuel, said stem and one of said walls having relatively movable valve parts controlling the communication of said stem with the chamber, means actuated upon operation of the throttle for moving another wall of said chamber, and a spring abutment for said one wall ofthe chamber tending to move said one wall towards the other wall of the chamber and to close the valve parts.

3. In a carburetor, the combination of a movable cylinder, a piston for the same, a. stem on which the piston is guided, the stem being hollow to provide a discharge passageway, said stem having a conical head, said head having a port,

communicating with the discharge passageway, a spring abutment for the piston tending to move the piston into position to obstruct said port, and means for moving the cylinder.

4. In a throttle controlled carburetor, a fuel supply chamber, an accelerating device disposed in said chamber, said device comprisinga movable cylinder and a movable piston, a stationary stem upon which the piston is guided, said stem having a discharge passageway terminating in a port at the upper end of the stem, a spring abutment for the piston tending to move the 'piston to close said port, a lever connected to the piston, and means actuated by operation ofthe throttle for actuatingsaid lever.

5. In a throttle controlled carburetor, a fuel supply chamber, an accelerating device disposed in said chamber, saidv device comprising a movable cylinder and a movable piston, a stationary stem upon which the piston is guided, said stem having a discharge passageway terminating in a port at the upper end of the stem, a spring abutment for thev piston tending to move the piston to close said port, a lever connected to the piston, means actuated by operation of the throttle for actuating said lever, an economzer. passageway communicating with the fuel supply chamber and having a restriction, and a valve normally 'closing said economzer passageway, said valve having a stem adapted to be moved by said lever to operate the economzer valve when the throttle is in substantially wide open position.

6. In a throttle controlled carburetor, anaccelerating device comprising a vertical stem having a passageway, a piston guided on the stem,

said stem and piston having cooperating valve parts, a spring for the piston tending to move it to a position to close said valve parts, and an i inverted closed end cylinder embracing the piston. and vverticallyimovable in conjunction with the operation of the throttle, the lower lend of said inverted cylinder being at all times sealed by liquid fuel.

7. In combination in a throttle controlled carburetor, a vertical stem having a central passageway and having a head at its upper end, a radial passageway opening into the central passageway,

\ a piston embracing said stem and having its upper end adapted to cooperate with said head to obstruct said radial passageway, a spring' tending to move the piston on the stem to cause it to close said radial passageway, a movable cylinder ernbracing the piston, the lower end of the cylinder being open and the upper end thereof closed, and means for actuating the cylinder upon opening oi' the throttle.

8. In a throttle controlled carburetor, the combination of a fuel supply chamber, an accelerating device having a movable closed end cylinder disposed in said fuel supply chamber, a stationary stem containing a discharge passageway terminating in a port, a piston for the cylinder guided on said stem and adapted at one end of its travel to close said port, a spring for the piston tending to move it to the end of itstravel, spring means tending to raise the cylinder and a lost motion connection between the throttle and the piston, said lost motion being taken up by the last mentioned spring.

9. In a throttle controlled carburetor, an accelerating device comprising a collapsible chamber, one wall thereof movable by movement of the throttle, a second wall of the chamber movable relative to said one wall, a stationary hollow stem comprising a valve port, said latter wall -having a sleeve movable on said stem, and a spring abutment for 'lsaid latter wall tending to cause the sleeve to close the valve port when the latter Wall is moved by the spring abutment to the limit of its movement. y

10. Ina throttle controlled carburetor having a fuel supply chamber, a venturi, a fuel supply passageway leading from the chamber into the venturihsaid passageway including a metering orifice, an air bleed passageway opening into the said fuel supply passageway at a point adjacent its outlet in the venturi and on the outlet side of the metering orifice, an accelerating syringe for drawing fuel from the supply chamber and discharging the same into the fuel supply passageway upon opening of the throttle, said syringe having a fuel discharge passage opening into the fuel supply passageway between the metering orifice and the connection of the air bleed passageway, and a valve closing oif the syringe discharge passageway, after operation of the syringe. 11. In a throttle controlled carburetor having a constant level fuel supply chamber the combination of an accelerating device operated upon opening of the throttle for discharging accelerating fuel, said device comprising a movable pumping chamber having an imperforate closed top extending above the fuel level in said fuel supply chamber when the throttle is in closed position, adapted to be lled with liquid to a variable degree depending upon the temperature of the fuel in said supply chamber and having an outlet valve opened by pressure of the fuel thereon.

12. The combination of a. throttle controlled carburetor having a substantially constant level fuel supply chamber and an accelerating pump 'communicating with said chamber, said pump being actuated upon opening of the throttle to discharge fuel for acceleration purposes, said pump comprising a movable member carrying a thermostatic element for controlling the discharge of acceleration fuel.

13. The combination of a throttle controlled carburetor having a substantially constant level fuel supply chamber and an acceleration pump communicating with said fuel supply chamber, said pump being actuated upon opening of the throttle to discharge fuel for acceleration purposes, said pump comprising a movable cylinder member, said member having a bypass port and a thermostatically controlled valve for said port carried by said cylinder.

14. The combination of a throttle controlled carburetor having a substantially constant level fuel supply chamber and an acceleration pump communicating with said fuel supply chamber,

said pump being actuated upon opening of the' throttle to discharge fuel foracceleration purposes, 4said pump comprising a cylinder having a bypass, a valve controlling said bypass and a thermostatic element responsive to the temperature of the fuel in the fuel supply chamber for controlling said valve. v l

15. In a carburetor, a constant level fuel supply chamber, an accelerating device comprising means forming a fuel pumpingchamber having an imperforate gas-tight upper portion extending above the fuel level in said fuel supply chamber for containing a gas or vapor, means responsive to throttle operation for reducing the effective volume of the chamber, and a pressure responsive outlet valve permitting flow of fuel from the chamber only when the pressure reaches a predetermined value.

16. In a throttle-controlled carburetor having a fuel supply chamber, a venturi, a fuel supply air bleed passage opening into the fuel supply passage on the outlet side of the metering orice, an accelerating pump for drawing 'fuelfrom the fuel supply chamber and discharging the same into the fuel supply passage upon opening ofthe throttle, said pump having a fuel discharge passage opening into the fuel supply passage on the outlet side of the metering orifice, and a pressure-responsive valve closing olf said fuel discharge passage after operation of the pump.

17. In a carburetor having a fuel nozzle, a fuel supply chamber, an accelerating device comprising means forming a fuel chamber having a vapor tight upper portion for containing a gas or vapor, said portion being movable under certain conditions of operation to a position where it extends a substantial distance above the fuel level in said fuel supply chamber, means responsive to throttle operation to reduce the effective Volume `of the chamber, a discharge passage communicating with said chamber and with said fuel nozzle, and a pressure-actuated valve controlling said passage permitting flow of fuel from the chamber to the nozzle and preventing flow of fuel from the nozzle to the chamber.

18. In a carburetor including a fuel reservoir and having an induction passage, a normal fuel system for feeding fuel from said fuel reservoir to said induction passage, an acceleration system including a pump having a stationary outlet Aport and a discharge passage leading therefrom to Asaid induction passage, said discharge passage being subject to the suction in the induction passage, said pump comprising a pumping membermovable upon opening movement of the throttle to exert pressure upon the fuel in said pump, a plunger associated with said pumping member andcarrying a valve element controlling said outlet port, said plunger being yieldingly urged toward a position where said element closes said outlet port but movable by the pressure produced by said pumping element upon the fuel in the pump to a position where the valve element is in open position.

19. In a carburetor having a fuel mixture passage including a throttle, a main fuel system for supplying fuel to said fuel mixture passage, a fuel-reservoir, means for temporarily feeding a charge of fuel into said'fuel mixture passage includinga pump having a stationary outlet port and a passageway leading from the outlet port and communicating with said fuel mixture passage at an elevation above that of the fuel level n said reservoir, said passageway being subject t0 the suction in the fuel mixture passage, said pump comprising a hollow reciprocable pumping member actuated in accordance with throttle movements to exert pressure on the fuel being pumped, and a plunger slidable within said pumping member and carrying a valve member adapted to close said outlet port, said plunger being yieldingly urged to a. position where the valve member closes said outlet port-but movable by the pressure produced by the pumping member in the fuel being pumped to a position where vthe valve member is in open position.

20. In a. carburetor having a fuel mixture pasres'ervoir, a. main fuel system for supplying fuel from said reservoir to -ing member to a position 7 said fuel mixture passage, and an acceleration system including a. pump and an outlet from the pump to the fuel mixture passage, said pump comprising a reciprocable pumping member having an internal bore and actuated in accordance with opening movements of the throttle to exert pressure on'the-fuel being pumped-and a plunger vslidable within said'bore and carrying af valve member adapted to close said outlet, said plunger being yieldigly urged to a position where, the valve member movable by the pressure produbed by the pumpwhere the valve member is in open position. i DoN` COLE.

1o" closes said outlet but