US2263091A - Fuel pump - Google Patents

Description

Nov. 18; 1941. 1.1 JOHNSON FUEL PUMP Filed March 18', 1958 2 Sheets-Sheet 1 INYENTQR TTORNEY 4 J. P. JOHNSON! 2,263,09i

FUEL PUMP F iled March 18, 1938" 2 Sheets-Sheet 2 I Pig 5 Ja'mas P. Johnsan mvemon ATTOR N EY Patented Nov. 1%, WM

warren stars s sar -1m eerie artaesi FUEL PUIVIP James P. Johnson, Shaker Heights, Ohio, um gnor, by mesne assignments, to Pump Engineering Service Corporation, Cleveland, Ohio, at corporation of (iliio ApplicationMarch is, 1938, Serial No. 198,693 6 Claims. (01. 103-42) This invention relates to fueLpumps for use on aircraft, and particularly to improvements over the formof pump disclosed in my copending application, Serial No.170,844, filed October 25, 1937.

In the pump disclosed in my copending application. the relief and by-pass valve assembly is relatively complicated requiring several steps in provide an improved assembly whereby the movement of the valve member is restricted so as .to minimize the hammer action between the valve head and its seat.

Another object of the invention is to provide external adjustment for preloading the "valve member.

A still further object of the invention is to provide a new and simple means of connecting the detachable reversible relief valve housing to the pump housing proper. With the objects above indicated and other objects hereinafter explained in view, my invention consists in the construction and combination of elements hereinafter described and claimed.

" Referring to the drawings,

Figure l is a longitudinal sectional view taken online l- -l in Figure 3 and showing the improved pump structure embodying the present invention.

Figure 2 is a transverse vertical sectional view taken on line 2-2 in Figure 3.

Figure 3 is a top plan view of the pump shown in Figure 1.

Figure 4 is a transverse'sectional view taken on line 4-4 in Figure 1.

Figure 5 is a transverse sectional view taken on line 5-5 in Figure 4 and showing themeans for connecting the reversible housing to the pump housing proper;

Figures 6 and 7 are transverse sectional views;

taken on line 6-6 and 1-,! respectively in Figure 1 and show details of the valve assembly. 1

Figure 8 is avschematic broken-away sect-ion view showing the upper side of the diaphragm connected with a supercharger.

pump provided with a fuel by-pass and relief valve embodying the present invention and designed especially for use on-aircraft where lightness, compactness, and efllciency are of utmost importance.

The fuel pump is indicated generally by the numeral Ill and consists of a housing II, preferablyoi' aluminum or some similar light-weight material, having an axial opening I2 therein extending inwardly from one end of the housing and which is closed at the other end by an integral end wall l3. The housing II is provided with an interiorly screwthreaded opening H on one side thereof, which communicates with the axial bore l2, while the opposite side of the housing is provided with a similar screw-threaded opening I! which likewise communicates with the bore l2 as more clearly shown in Figure 2. These openings l4 and I5 are adapted to be connected, one with the fuel supply and the other with the. carbureter which supplies the fuel to the motor, and the respective openings. will be connected in the manner herein stated, depending on the direction of rotation of the fuel pump.

A liner l1, preferably of hardened steel, is positioned within the axial bore l2 and is provided with an axial bore I I which is eccentric to the axial bore l2. The liner II, as more clearly shown in Figure 2, has oppositely disposed, transversely extending openings I9 and I9 communicating respectively with the screwthreaded openings It and I5 so as to provide communication with the interior of the bore It, the latter constii tuting a circular chamber.

' A rotor 2|, preferably of hardened steel, is eccentrically positioned within the bore l8 and has a running engagement with the inner peripheral wall of the chamber at 22, which separates the opening l9 from the opening it. The rotor 2| is provided with tubular extensions which extend axially thereof, and are suitably mounted for rotation in spaced bearings disposed within the housing. The body portion of the rotor 2| .is provided with angularly disposed slotsfpositioned longitudinally, and within which are slid ably mo'un'ted a plurality of blades 24, the blades being coextensive with the body portion of the rotor. adapted for engagement with the inner peripheral wall of the chambenwhile the inner end of the blades extend inwardly within an axial bore 25 provided in the rotor. A roller member 28 is freely positioned within the bore 25 and is adapt- In the drawings, lhaveillustrated a rotary fuel ed for engagement with the inner ends of the The outer ends of the blades 24 are cent end of thebearing flange.

tion.

in my copending application, Serial No. 196,694,

flied March 18, 1938. A drive shaft H is disposed axially of the rotor 2| and has at its inner end a transversely extending projection III which is disposed in aligned recesses H2 provid ed in the adjacent tubular extension. The projection lH is mounted for slight axial movement within the recesses H2 but connected thereto in a manner to insure rotation. of the rotor 2|. outwardly of the projection I II is an enlarged circular portion H3 which is disposed within the flanged extension of the bearing opening in the adjacent bearing and has a close running flt therewith. The inner face of the circular portion H3 is spaced slightly from the adjacent end of the rotor extension but is movable axially into engagement therewith for a purpose to be later described. The shaft III) has a reduced portion H4 outwardly of the circular portion H3 and of relatively smaller diameter and a second enlarged circular portion H5 substantially midway of its ends.

A seal supporting member H6, preferably of steel material, has an annular wall I I! which encircles the flanged extension of the adjacent bearing and an inwardly extending peripheral flange H8 arranged in spaced relation with respect to the adjacent end of the bearing flange. The opposite end of the supporting member H6 has an outwardly extending peripheral flange H9 which rests upon the adjacent portion of the bearing and is of a diameter such as to permit it to be slidably mounted within the bore l2-of the housing. Positioned upon the inner face of the peripheral flange H8 is a flexible disc l20,- of duprene and fabric material or other suitable material, and positioned upon the inner face of the disc is a metal disc |2l which has its inner face spaced a suitable distance from the adja- The metal and flexible discs and flange H8 are secured in any suitable manner for their intended function but in the present instance, a plurality of pins I22 have their outer ends secured to the flange H8 and their inner ends projecting freely through aligned openings in the flexible and metal discs. The metal disc HI and the enlarged portion H3 of the drive shaft are so arranged that their adjacent marginal portions are in running engagement and their contacting surfaces being. machined, produce a seal against the escape of fluid by reason of the pressure existing in the pump during its operation. The flexible and metal disc arrangement provides another advantage inthat it insures a proper seal even though the drive shaft HOis in slight misalignment. This is made possible by the flexible disc I29 yielding slightly without causing any misalignment between the contacting portions of the metal disc HI and the enlarged portion H3.

The construction is such that when the pump is vacuum tested by the interior of the pump being placed under vacuum, the enlarged portion H3 of the drive shaft is moved inwardly axially blades 24 to maintain the latter in spaced relabore l2 has an annular flange 124 which is adapted to engage the flange H9 on the supporting member and by screwing the plug inwardly the flange H9 is secured in rigid position. The plug I23 has an end wall I25 provided with an axial opening to-receive the enlarged portion H5 of the drive shaft. The outer end of the drive shaft H0 is in the form of a gear I26 adapted for driving connection with the motor of the aircraft or other means.

The operating parts of the pump are, of course, so arranged that the pump may be operated in either direction without the necessity of rearrangement thereof, which is quite advantageous in view of the fact that different types ofmotors operate in different directions. -It is not necessary, therefore, to change the position of the ,pump, irrespective of the direction of rotation into contact with'the adjacent end of the bearof the motor used.

When the pump is used on an airplane, the rotor is operated at various speeds, depending upon the R. P. M. of the motor, as the rotor is usually connected to the motor to operate at the same or slightly greater R. P. M. The volume of fuel pumped by the pump therefore varies with the changes in the R. P. M., and, for example, at 1750 R. P. M. approximately 360 gallons of fuel per hour are pumped by the pump. Such a volume of fuel is, of course, out of proportion to the volume of fuel adapted to be handled by the carbureter, and means must therefore, be provided to return the excess fuel to, the inlet side of the pump. Furthermore, for eflicient operation of the motor, the fuel should be delivered at a constant pressure irrespective of the volume required, and the pressure most effective has been found to be approximately 3 /2 pounds, although this may vary somewhat, depending upon different conditions. Means is, therefore, provided in the pump to maintain the volume of fuel discharged at a constant pressure irrespective of flying conditions.

A second hollow housing 21, of aluminum or other similar material, is detachably connected to the housing proper I l and has two positions of mounting thereon so as to adapt the pump for operation in either direction without the necessity of dismantling the operating elements. This housing is provided with a transversely extending partition 28 having an axial opening providing a valve seat 29 on its outer side. valve member 30 has a valve head 3| engageable with the valve seat 29 and a depending tubular stem portion 32 having its lower end slidably mounted in an opening 33 provided in the adjacentportion of the housing H, the bottom of the stem terminating short of the bottom of the opening 'to provide a dash pot for minimizing vibrations imparted to the valve member. The under side of the valve head 3| is in communication with the outlet opening l5 through aligned openings 34 and 35 provided in the respective housings while the outer side of the valve head 3| is in communication with the inlet opening through aligned openings 35 and 31 similarly located.

The upper end of the tubular housing 21 has an outwardly extending circumferential flange 38 which is provided with a marginal extension 39 to provide a recessed outer surface and a relatively flat flexible disc 42, of impervious mate- I rial such as duprene and fabric or other suit ablematerial, is positioned within the recessed outer surface and extends across the open end ofthe housing. A cover 43 preferably of alumi- A relief num, has acircumferential flange M fitting snugly within the recessed portion and is detachably connected to the flange 38 by means of a. plurality of bolts 45 which engage aligned openings provided in the respective flanges and the marginal edge of the disc 42 so as to provide a sealed joint. The cover 43 also has a conical tapered portion 46 providing a chamber d1 above the central portion of the disc 42 and a tubular extension 48 extending axially outwardly therefrom which is provided with an externally screwthreaded end 49.

r The valve member 30 is connected to the disc 42 by means of a tubular extension 5! which is an integral part thereof and the outer end of the extension 5| is exteriorly screwthreaded. The extension 5| is formed with a circumferential flange 52 disposed upon the inner side of the disc M and the disc is provided with an axial opening through which the extension projects. A washer 53, of metal or other rigid material, has an axial opening through which the extension 5l projects and is disposed upon the outer side of the disc 42 in engagement therewith. A nut 56 is mounted upon the screwthreaded end of the extension 5| and when screwed into place, securely maintains the central portion of the disc 42 between the washer 53 and the flange 52 for unitary movement.- It should be noted that the relative diameters or areas of the flange 52 and washer. 53 are difierent and may be varied or arranged in reverse relation to that shown in the drawings for a purpose to be later described.

A coiled spring 51 has'its major portion disposed within the tubular extensions 32 and Si of thevalve member 30 and its lower end engaging thebottom of the extension 32, while its upper portion fits freely within the tubular extension 48 of the cover. The tubular extension 38 is interiorly screwthreaded throughout its entire length and receives an adjusting plug 58 which has its inner end in engagement with the outer end of the spring 51 by means of which the tension of the latter may be varied so as'to predeterminately preload the valve member and to normally maintain the latter in engagement with its valve seat. By -mounting the spring in the manner shown, an extra long spring may be used with the result that a greater variation in the spring tensionis possible and consequently a greater variation of pressure of the discharged fluid. a

For adjusting the plug 58, a square rod 59 is extension acts as an abutment for and is predeterminately spaced from the outer end of the tubular extension all of the valve member so as to limit the'movement of the latter and thus minimize the hammer action of the valve head and its valve seat. v

The conical porfion i6 is provided with a pipe tap 65 which is normally closed by a plug 66 having an axial opening 8'! therethrough which connects the chamber All and consequently the outside of the disc 43 with the atmosphere. When the motor is super-charged the plug 66 is removed 7 ing M, passes around the rotor and is discharged from the outlet opening l5 where it passes to the I carbureter in desired volume and at the most efficient pressure, the latter two factors being controlled by the preloading of the relief valve.-

Inasmuch as the capacity of the pump is much greater than the volume of fuel required by the carbureter, the excess fuel passes upwardly through the communicating openings 34 and 35 into engagement with the under side of the valve head 3| and the pressure exerted raises the valve head from its valve seat so as topermit the excess fuel to pass therethrough and return, through the communicating openings 35 and 31, to the inlet'openingl4, its return being aided by the suction present at the inlet opening. It will be noted that the washer 53 is of a larger diameter than the circumferential flange formed on the valve member. The flange 52 must be of such size that its effective area combined with the effective area of said diaphragm is substantially equal to the effective area of said valve head to provide a statically balanced relation.

whereby the pump suction force created at the inlet side of the pump will have no appreciable slidably mounted in a square opening provided in the plug and has its inner portion extending centrally of the spring for a distance sufllcient to permit tension adjustment of the spring throughout its entire range. At the outer end of the rod 59 is a relatively flat circumferential flange 60 of a diameter slightly less than the outer diameterof the extension 48 adapted to engage the outer end of the latter. Beyond the flange 80 the rod 59 is provided with a knurled thrust member 6| by means of which the rod may be rotated in the direction desired which causes the effect upon the normal operation of thepre-load-V ed valve member. By reason of the opposite side of the disc 42 being in communication with the atmosphere, or the super-charger as the case may be, the valve member is at all times properly balanced and therefore unaliected by changes in pressure occurring at the inlet opening particularly -due to changes in flying conditions.

While the actual unit area of the'flexible diaphragm and associated means attached thereto may be greater than theactual area of the adjacent upper surface of the valve, the important factor to be taken into account, as pointed out above, is that the eflfective suction areas of each of the respective opposed surfaces must be sub stantially equal. In other words, the suction pull-up on the valve must always balance the suction pull-down on the sealing means. While it is not my intention to be committed to any par ticular explanation of this fact, it would appear that this is the result of the valve being a rigid member while the seal is made up at least in part of a flexible diaphragm.

When the pump becomes inoperative for any reason, iuel may be try-passed by means of the wobble pump installed on a plane in a suitable handy location. The operation 01' this wobble functioning as a gasket. The inner end of the v pump draws fuel from the tank and forces it into the inlet opening ll of the pump shown in Figure 2. The fuel passes upwardly through the communicating openings 31 and 36 and into the chamber between the top side of the valve head and the under side of the disc 42. To overcome the otherwise balanced condition of the valve member, the washer 53 is made larger than the flange 52 so that its effective area combined with the effective area of said diaphragm is greater than the effective area of said valve head whereby pressure exerted by the inflow of fluid into the chamber between the top side of the valve head'and the under side of said diaphragm causes the valve head to be lifted from its seat and after the valve is once off, the valve area is of no consequence and fuel is passed through the pump into the carbureter at no great pressure difference between the inlet and outlet openings of the pump.

A different and expedient means is provide for detachably connecting the relief and by-pass housing to the pump housing proper whereby the pump may be operated in either direction without the necessity of removing or dismantling the operating elements. This construction is more clearly shown in Figures 4 and 5, wherein a plurality of bolts 65 extend through portions of the housing proper on opposite sides of the drive .shaft and their threaded ends engage a plurality of aligned screwthreaded openings provided in the flanged portion 66 of the detachable housing 21. Four of these bolts are shown and preferably connected to diametrically opposite corners to insure proper positioning.

It will be noted that in the present instance, I have illustrated and described the use of an impervious flexible substantially flat disc or diaphragm which wellsatisfies the conditions required but it should be understood that other types may be adopted which have the required characteristics.

' While I have described the preferred embodiment of the invention it is to be understood that I am not to be' limited thereto inasmuch as changes and modifications may be resorted to without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. In an aircraft fuel pump of the type including a housing having an inlet and outlet, a disclike relief valve adapted to cooperate with a valve seat formed in saidhousing for controlling the flow of excess fuel from the pump outlet to the inlet thereof, said valve having a stem portion extending from the upper face thereof, the underside of said valve being in communication with said outlet and the upper side thereof being in communication with said inlet, and means within said housing sealably connecting said stem ing a hollow bore formed in said stem portion,

a second stem portion extending from the underside of said valve being closed at the outer end thereof, said valve being centrally orificed complementary to said. stem portions, a long helical sensitive spring positioned with one end thereof incontact with the inner closed end of said stem,

I and adjustable means engaging the other end of said spring for adjusting the compression thereof for determining the output pressure of said pump.

2. In an aircraft fuel pump of the type including a housing having an inlet and an outlet, a

disc-like relief valve for controlling the flow of excess fuel from the pump outlet to the inlet thereof, the underside of said valve being in communication with said outlet and the underside thereof being in communication with said inlet and sealing means in said housing including a flexible disc-like diaphragm spaced from the upsaid housing engaging the outer end of said perside of said valve and having an effective suction area substantially equal to the effective suction area of the adjacent exposed portion of said valve whereby to balance the same against inlet suction, said arrangement being particularly characterized by the provision of means for ren-- dering said relief valve operable to cause said pump to deliver a wide range of output pressures depending upon the adjustment thereof, said means comprising a hollow stem member having a first portion extending axially from the upperside of said valve, means sealably attaching said diaphragm to said stem in spaced relation to the upperside of said valve, means sealably connecting said diaphragm to said housing at the periphery thereof, and a second hollow stem portion extending axially from the lower side of said valve, said last named stem portion being closed .at the outer end thereof, said valve being comnamed stem portion, and extending up through said valve orifice and said first named tubular stem portion, and adjustablelmeans carried by spring for varying the compression thereof for determining the output pressure at which said valve will operate.

3. In an aircraft fuel pump of the type including a housing having an inlet and an outlet, a disc-like relief valve in said housing for controlling the flow of excess fuel from the pump outlet to the inlet thereof, the underside of said valve being in communication with said outlet and the upperside thereof being in communication with said inlet and means for dividing said housing adjacent the upper face of said valve into a first compartment and a second compartment, said first compartment being in communication with said pump inlet pressure and means adapted to connect said second compartthereof, said valve being complementarily centrally orificed, a long helical sensitive spring positioned with one end thereof in contact with the inner. closed end of said stem passing up through the orificed portion of said valve and through said first named hollow stem portion, and adjustable means carried by said housing engaging the other end of said spring for varying the compressionthereof for determining the output pressure at which said valve will operate, means sealably attaching said diaphragm to said I a stem in spaced relation tothe upperside of said cluding a disc-like valve for controlling the flow of fuel from the pump outlet to the inlet thereof,

the underside of said valve being incommunication with said outlet and the upperside thereof being in communication with said inlet and means including a flexible disc-like diaphragm. positioned in said housing in spaced relation to the upper face of said valve for balancing the pull of inlet suction acting on the upper side of said valve tending to open the same, said arrangement being particularly characterized by the provision of sensitive means for rendering said relief valve operable to cause said pump to deliver a wide'range of output pressures, said means comprising a hollow tubular stem having a first portion extending axially from the upperside of said valve, and a second portion extending v axially from the underside ofsaid valve, the outer end of said second named portion being closed, said valve being axially oriflced complementarily to said'stem portions, a long helical upperface of said valve, said diaphragm being centrally oriflced for reception about saidfirst named stem portion and seating upon said annular flange, a rigid washer member received about said stem in engagement with the upperside of said diaphragm, a threaded locking member received about the upper end of said stem for locking said washer member against said diaphragm with a predetermined pressure and means for sealably connecting the outer periphery of said diaphragm to said housing.

5. In an aircraft fuel pump and relief valve assembly including a housing having fuel inlet and outlet openings, means in said housing for pumping fuel from said inlet to said outlet, relief means for conducting excess fuel from said outlet to said inlet comprising a passage formed around said pumping means, a disc-like valve for controlling the flow through said passage, the underside of said valve beingin communication with said outlet, said arrangement being particularly characterized by the fact'that said valve is provided with a hollow tubular stem extending axially from each side thereof, the cross sec- 'tional area of said stem being substantially less than the cross-sectional area of said valve whereby to expose a substantial portion of the underside of said valve to outlet pressure and a substantial portion of the upperside of said valve to inlet suction, a long sensitive helical spring contacting the inner closed end of said hollow stem and extending up beyond the upper end of said stem and adjustable means carried by said housing for varying the compression of said spring, sealing means in said housing for coun-. teracting the opening effect of inlet suctionon the upperside of said valve, said means including a flexible diaphragm, a rigid peripheral flange on the upper portion of said stem in spaced relation to the upperside of'said valve, said diaphragm being axially oriflced for reception about the upper end of said stem and seating on said flange, a rigid washer-like member received about said stem in engagement with said diaphragm,

a lock nut threadedly received about said stem in engagement with said washer-like member with a predetermined degree of tightness, said diaphragm being attached about the periphery thereof to the surrounding housing, the size of said flange, the size of said washer-like member and the area of said diaphragm exposed to suetion being so proportioned that the suction pull on the seal tending to close the valve is counteracted by the suction pull on the upperside of the valve, tending to open the same for widely v varying inlet suctions. a

6. The structure defined in claim 4 wherein the area of said washer member is greater than the juxtaposed area of said annular flange whereby when said pump inlet is supplied with fuel under pressure from an auxiliary source,

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