US2372306A

US2372306A - Fuel feeding device

Info

Publication number: US2372306A
Application number: US446073A
Authority: US
Inventors: Paul F Adair
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1942-06-06
Filing date: 1942-06-06
Publication date: 1945-03-27
Anticipated expiration: 1962-03-27

Description

' 2 sheets-sheet l P. F. ADAIR FUEL EEEDINQ DEVICE Filed Jung 6,' 1942 y .March 27, 1945.

FUEL FEEDING DEVICE ATTORNEY Patented Mar. 2'1, 1945 2,372,306 FUEL FEEDING DEVCE `Paul F. Adair. Dayton, Ohio, assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application June s, 1942, serial No. 446,073 claims. (creci- 09) This application relates to charge forming devices and more particularly to charge forming devices of the pressure feed type.

It is an object of the invention to provide a simple and compact pressure feed type 0f charge forming device.

Another object of the invention is'to provide a charge forming device of the pressure feed type in which vapor forming tendencies are reduced to a minimum.

It is a still further object of the invention to provide a pressure feed type of carburetor in which vapor formed within the carburetor is automatically eliminated. 1

Another object ofthe invention is to provide a simplified pressure feed type of carburetor which may be automatically filled with fuel and in which vapor will automatically be eliminated whenever it forms.

Another object of the invention is' to maintain the fuel under as high a pressure as possible until after it has been metered.

A still further object of the invention is to provide a simplified pressure feed carburetor of the anterior throttle type whereby induction passage icing is reduced to a minimum.

Another'object of the invention vis to provide v an improved anterior throttle carburetor.

Other objects and advantages of the invention will .be readily apparent to one skilled in the art from the following descriptiontaken in connection with the attacheddrawings wherein:

Figure 1 is a diagrammatic sectional view ,of one embodiment of the invention; and

Figure 2 is a similar View of another embodiment of the invention.

With reference to Figure 1 there isshown an v als drical recess surrounded by an annular attach-V y ing flange 20 to which

sections

22 and 24 of a regulator indicated generally at 25 are secured by bolts, not shown, the center section 22 being -provided with a web 26 having a central aperture 21. A pair of diaphragms 2l and 30, preferably having preformed annular grooves therein,

4and web 28` to eliminate the air leakage.

sections

24 and 22, and between section 22 and the iiange` 20 and are secured at their center portions to a rod 32, extending through the aperture 21, by means of diaphragm supporting plates 33 and 3 4 and lock nuts 35 and 36. The

diaphragms

28, 30, web 25, and section I2 thus divide the interior of the regulator into four

chambers

38, 39, 40 and 4I. The rod 32 extends through and is freely slidable in the aperture 2'I, a relatively close fit being provided to minimize air leakage between the chambers 39 and 40. If'desired, a sealing diaphragm may be provided between the rod 32 The rod 82 is provided at its right end with a valve -44 controlling aport 46 coaxially related to the chamber 4I and to rod 32 and communicating j of air now so as to be subjected to the impact of entering air in the inlet I I. A passage 52 connects the chamber 40 with an annular Venturi groove 53 'in communication with the throat of the venturi by means of a plurality of ports 54. The chambers 39 and 40 are thus subjected to air inlet pressure and Venturi pressure respectively whereby a differential in these pressures resulting from air flow through the induction passage I0 will tend to move the Tod 32 to the left and open the valve 44.

Fuel is supplied to a fuel passage 58 in the regulator through a pipe 59 by a fuel pump 60 which may be `of any desired type, the one shown being of the sliding vane type having an engine driven rotor 62, sliding 4vanes 63, a fuel inlet 84 and a by-pass 65 controlled by a fuel pressure responsive valve whereby fuel under substantially constant pressure is supplied to pipe Ports' 88 and 59 connect the chambers 38 and 4I with the passage 58 anterior and posterior to a metering element 10 respectively. The chambers 38,and 4I are thus subjected to unmetered andA metered fuel pressures respectively whereby a differential in these pressures resulting from fuel flow throughthe metering element 'ID will tend to move the rod 32 to the righty and close the valve 44. Themetering elementy -10 has been shown as an orifice of fixed size for convenience and simplicity; however, it will be apale clamped et their Outer edges between the Il parent that the element may be of a variable area type well known in the art whereby the fuel metering area. may be increased if desired to Drovide a richer mixture under conditions of high power output, as well as at other times when a richer mixture may be desirable.

During operation the air nov/ing through the venturi |4 creates a differential in the pressures in the entrance and in the venturi |4 which varies in accordance with the rate of air flow through the induction passage. These pressures being transmitted to the chambers 39 and 40 act upon the diaphragms 23 and 3@ and urge the rod 32 to the left, in a direction to open the valve 36, with a force which likewise variesin accordance with the air flow.

Fuel discharged by the pump 5|] ows through pipe '59, passage 5d, orifice 1d and port ts, into chamber 13|, past valve ill and through passage d@ to the nozzle i8 from which it discharges into the air flowing through the induction passage l0. creates a dierential in fuel pressures anterior and posterior to the orice which varies in accordance with the rate of fuel ilow through the orifice. These pressures being transmitted to The flow of fuel through the oricep-lilaefraeoe stream. The fuel regulator indicated generally at includesan end section |24 and a center webbed section |22 secured by bolts not shown to an annular attaching flange |20 provided on the side of the induction passage body H2. Diaphragms |28 and |30 and web |26 divide the regulator into four chambers |38, |39, and |'4| in a manner similar to Figure 1.

The center portion of diaphragrn|28` is supported by a plate |33, the diaphragm and plate .being secured together by a bolt member |10.

chambers 38 and 5| act upon the diaphragms traneous force such as idle spring 159. 1i the air flow increases, as by manual opening ofthe throttle |t, the diierential between the pressures in chamber se and t@ will increase and open the valve ill an additional amountwhereby the fuel ow will be increased to compensate for the increase in air ilow. A decrease in air ow will similarly result in a corresponding decrease in fuel ow.

The idle spring d@ urges the rod` 32? in the. same direction as the air differential force. As a consequence the fuel ow differential must be slightly increased to balance not only the air diderential pressure but also the force of spring |19. At low rates of air ow, suchv as at idle,

the air differential -pressure is relatively small and as a consequence the force. of spring de, even though quite small, requires an appreciable percentage increase in the fuel ow to balance it.

A rich mixture is thus produced at idle, as is desired. As the air ow and consequently thev air diii'erential pressure increase, the force of spring becomes of decreasing eiectiveness for enriching the mixture and becomes substantially` negligible at air flows corresponding to cruising operation.

Figure 2 discloses another embodiment of the invention in which parts corresponding to similar parts of Figure 1 have been given corresponding reference numerals with the addition of 100. The carburetor of Figure 2 is an updraft carburetor in contrast to the d owndraft carburetor of Figure 1 and includes an induction passage il@ having a flared air inlet lll, a venturi H4, a pivotally mounted manually actuated throttle H6, 'and a hollow tube nozzle bar |8- having its downstream portion cut away to form a slot through which-.the fuel discharges into the all' and nut |15. The member |14 is provided with an annular groove |16 in which is received the -bowed end of a leaf type idle spring |18 adapted to be adjusted by means of an adjustment screw |19. The center portion of diaphragm |36 is supported by a plate |34, the diaphragm and plate being secured to a rod |32 slidable in a bearing member |82 mounted inthe web |25. The rod |32 is provided at its left end with a reduced diameter portion loosely received within a cylindrical recess |841 in the end of the bolt member |16. The right end of rod |32 is connected, by means of a pin and groove connection, to a lever |85 pivoted at |86 and connected to a fuel control valve |44 slidable within a valve guide and seat member |86 having a fuel inlet port |69.

AA passage |56 connects the air chamber |39 with an annular groove |5| provided in venturi |||l and in communication with the air inlet whereby chamber |39 is subjected to entering air pressure. A passage |52 leads from they air chamber |C||l to an annular groove |54 located substantially at the throat of the venturi whereby chamber |430 is subjected to the 4pressure in the venturi. Fuel chambers |38 and 36| are intercommunicated adjacent their bottoms and tops by passages |51 and |58, respectively, containing metering elements |1|l and |1|. Fuel is supplied to chamber |38 by a pump |60 through a pipe |59 connected to a fuel inlet fitting |S| threadedly mounted in the end section |26 and provided with a fuel straining screen |92 secured in the fitting by a snap ring i'l.

During the carburetor fuel lling operation, the passage |51 permits the fuel chambers |33 and Ml to ll simultaneously. 1f the fuel chambers were not connected adjacent their lower portions, fuel entering chamber |38 would urge the diaphragm |28 to the right and close the valve |44 thereby trapping air in the chambers |33 and A|4| and preventing automatic filling. The passage |58 has been located adjacent the uppermost portion of chamber |38 so that any small particles of air or vapor which are entrained in the fuel entering the chamber will be eliminated as quickly asthey are received and cannot accumulate and so interfere "with the operation o the device, as .would be the case if only the passage |51 connected to the lower portion of chamber |38 were provided. For similar reasons of vapor elimination, the fuel valve |44 is located in the uppermost portion of chamber |49 and lever connected with the rod |32 in contrast to the coaxial valve and rod yarrangement o Figure 1.

vThe oatin'g connection between rod |32 and the-.bolt member |14 of diaphragm |28 eliminates binding or excessive bearing friction in the event the two diaphragme are not perfectly coaxially aligned, and permits angular rotation of one dia phragm relative to the other for aligning bolt holes and tiie'likel to facilitate assembly. Since the fuel pressure in chamber |38 is always greater than the air pressure in chamber l" there ication of Figure 2 functions in the same manner tering, in which case it would severely interefere with the operation of the device, has been minimized. Since the chamber 38 (Figure l) is subjected to full fuel'pump pressure, any variations in supply pressure are transmitted undiminished to the regulator chamber and would necessitate a change in the position of valve 44 for each change in fuel supply pressure to maintain constant fuel proportioning. Although the regulator will maintain constant fuel proportioning, perhaps subject to a` slight lag in reaction, even though the fuel supply pressure varies widely, it,

is preferable to eliminate such fuel supply pressure variations, and I consequently provide a fuel pump of the constant supply pressure type.

Although the invention has been described with reference to the particular` embodiments disclosed in the drawings, it. will be apparent that many changes or rearrangements ofthe parts maybe made without departing from the .spirit of the invention. For example, a valve .coaxially related to the control rod, as shown inFigure -1,

could readily .control a passage connected to the y top of the metered fuel chamber wherebyat least `a portion of the fuel supplied to the nozzle is withdrawn from the topof the chamber to elimnate vapor as in the-modification of Figure 2.. Many other modifications will likewise be apparentto one skilled in the art from the foregoing description taken in connection with the appended drawings, and it should therefore be understood that the invention is not limited to the particular embodiments disclosed, nor otherwise than in accordance with the `subjoined claims.

Iclaim: 1. A charge forming device comprising an air passage, spaced vparallel diaphragms forming movable walls of four chambers, a fuel inlet, a`

fuel conduit connecting the inlet to one end chamber and having a fuel metering restriction therein, means communicating the other end chamber with the conduit anterior to the restriction, means for subjecting the center two chambers to two pressures the difference of which varries with variation in air flow through the air passage, a fuel discharge -passage leading from the upper portion of the said one end chamber, a valve in said passage, means forming an operative connection between the diaphragms, and a lever pivoted within the said one end chamber and forming an operative connection between the diaphragrns and the valve.

2. A charge formingdevicefor an internal combustion engine comprising an air induction passage, a fuel conduit for supplyingl -fuel to the engine, means in the air passage. for creating a differential between two air pressures varying with variations in air iiow through the passage,

means in the `fuel conduit for creating a differ-` ential betweenv two fuel pressures varying with variations in fuel flow through the conduit, a valve controlling the flow of fuel through the conduit, coaxial parallel diaphragms, means forming operative connections between the'diaphragms andl between the diaphragms and the valve, said' vmeans including an abutting one-way connection intermediate the diaphragms adapted t0 permit relative angular displacement of one diaphragm with respect to another for purpose of alignment and to facilitate assembly, means for subjecting the diaphragms to the two air and two fuel pressures and so arranged that the pressures maintain the one-way connection in abutted relation whereby the diaphragms are shiftable as a unitary assembly and tend to move the `assembly and valve in a direction to increase the fuel flow upon increase in the air pressure differential and in a direction to decrease lthe fuel flow upon increase in the fuel pressure differential.

3. A fuel and air proportioning device comprising an air supply passage, a fuel supply passage, means in the air passage for creating a differential between two air pressures which varies with variations in air ow through the air passage,

means in the fuel passage for creating a differ.-

ential between two fuel pressures whichvaries with variations in fuel flow through the fuel passage, a valve in one of said passages for controlling the flow therethrough, coaxial parallel diaphragms', means forming an operative connection between the diaphragms including an abutting connection adapted to accommodate misalignment of the diaphragme and to permit relative angular displacement vof one diaphragm with respect to another during assembly, means forming an operative connection between one of the diaphragms andthe valve, means for subjecting the diaphragms to the two air and twofuel pressures and s'o arranged that the pressures maintain the connection between the diaphragms in abutted relation whereby the diaphragms are shiftable as a unitary assembly and tend to move the valve to increase and decrease the flow through the valve controlled passage upon increase and decrease respectively in the flow through the other passage.

4. In a charge forming device for an internal combustion engine, an air induction passage, a fuel conduit for supplying fuel to the engine, a valve for varying the flow through the conduit, a casing, substantially coaxial parallel diaphragms in the casing forming movable walls of four chambers, means for subjecting the center two chambers to two air pressures the differential of which varies with variations in the air now through the air passage, means for subjecting the outer two chambers to two fuel pressures greater than the air pressures, thedierence between the two fuel pressures varying 'with variations in fuel flow through the fuel passage, means forming an operative connection between the diaphragms including an abutting connection for accommodatl5 one of'said diaphragmsand the valve.

5. In a.. charge forming device for an internal combustion engine, an air passage,'a fuel conduit for supplying fuel to the engine, a valve for varyf ing the ow through the conduit, ancasing, coaxial parallel diaphragm in the casing forming movable walls of four chambers, a member secured to the central portion of one of Vthe diaphragms and'positively connected to the valve, an operative connection between the diaphragms including parts in telescoping abutting connection for allowing angular displacement of one diaphragm relative'to another diaphragm during assembly, one part being -supported by a guide'in the casing. means for subjecting the center two chambers to two air pressures having a differential which varies with variations in theair ow through the air passage, and means for` subjecting the end two chambers totwo fuel pressures having a differential which varies with variations in the fuel ow through the fuel conduit, said two fuel pressures being greater than the air pressures whereby the telescoping connection is maintained in abutting relation and the diaphragms are shlftable as a unitary'assembly. y

6.-In a charge forming device for an interna combustion engine, a throttle-controlled air`supply passage, a fuel supply passage, means in the air passagefor creating ea differential between two air pressures which varies with variations in air flow through the air passage, means in the asfrasoe fuel passage for'creating a dierential: between two fuel pressures which varies with variations in uelflow through the fuel passage, a valve4 controlling the flow of fuel through the fuel passage, a'casing, substantially coaxial parallel diierential-pressure diaphragms mounted in said casing, a substantially rigid partition interposed between said diaphragms and in conjunction with the latter and the casing providing four chambers, two of said chambers being subjected to the air dif,- ferential pressures and the other two chambers being subjected to the fuel differential pressures, means forming an operative connection between the two diaphragme and between the diaphragms and said valve including a member movably supported by said partition and connecting the central portion of one of said diaphragms to the valve for movement therewith and another member connected to the central portion of the other .of said diaphragms and having an abutting cylindrical pin and socket connection with said firstnamed connecting member to permit movement of one diaphragm independently of the other, the