US2223070A - Two-stage fuel pump - Google Patents

Description

Nw; 26,' 1940. A. c. KLECKNER TWO-STAGE FUEL PUMP Filed June 8, 1938 2 Sheet-Sheet l WQ o ZZ 23 5.3

Nov. 26, 1940.

A. c. KLECKNER 2,223,070

TWO-STAGE FUEL PUMP Filed June 8, 1938 2 Sheets-Sheet 2 J3 jfl y g Patented Nov. 26, 1940 UNITED STATES PATENT OFFICE.I

TWO- STAGE FUEL PUBIP Arthur C. Kleckner, Racine, Wis., assignor, by

mcsne assignments, to Webster Electric Company, Racine, Wis., a corporation oi Delaware Application June 8, 1938, Serial No. 212,415

7 Claims.

takes advantage of the fact that a larger internal gear pump stage is adapted to pump an excess of liquid fuel over that pumped by a smaller internal gear pump, which is one of the requirements for a two-stage gear pump of the type in which the first stage is merely used for bringing an excess supply of liquid fuel to the pump, and the second stage produces the required pressure in a predetermined amount of liquid fuel for an oilburner or other device.

Another object of the invention is the provision of an improved two-stage `gear pump which is adapted to be constructed more economically than the devices of the prior art and which is adapted to be used for a long period of time without necessity for any repair.

Another object of the invention is the provisin of an improved two-stage gear pump of the class described which is adapted to be self-priming and which vis adapted, therefore, to be used with oil burners under the most adverse conditions of installation.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the two sheets of drawings accompanying this specification,

Fig. 1 is a diagrammatic view of the installation of the two stage gear pump in relation to a 5 supply tank;

Fig.v 2 is a sectional view in partial elevation on the plane of the line 2 2 of Fig. 3, looking in the direction of the arrows;

Fig. 3 is a vertical sectional view, taken on the plane of the line 3-3 of Fig. 2, looking in' the direction of the arrows;

Fig. 4 lis another sectional view, taken on the plane of the line 4-4 of Fig. 2, looking in the direction of the arrows;

Fig. 5 is another sectional view, taken on the (Cl. 10S-126) plane of the line 5-5 of Fig. 2, looking in the, direction of the arrows;

Fig. 6 is a side elevational view of the pump, partially broken away, to show the by-pass conduit;

. Fig. 7 is a sectional view, taken on the plane of the line 1-1 of Fig. 3, showing the location of certain ports;

Fig. 8 is a view similar to Fig. 3, of a lmodiiied form of construction.

Referring to Fig. 1, this is a diagrammatic illustration in which the fuel supply tank I0 is provided with a supply of liquid fuel Il, such as oil, suitable for an oil burner, and the tank is provided with an intake pipe I2 leading to the intake' conduit of the pump I3.

The pump is provided with a by-pass outlet which is connected to the by-pass pipe I4, which leads back to the tank I Il and may discharge above or below'the surface of the supply of liquid fuel II.

The burner outlet conduit I5 communicates with the pump and leads to the nozzle of the oil burner, of which the pump I3 comprises a part.

For purposes of illustration, the pump is diag5 grammatically shown with a flexible drive IIiand an electric motor I1.

It should be understood that the present pump may be used in any oil burner installation, the usual installation including, not only the motor and pump and the flexible drive, but an air fan, suitable ignition and safety devices, and the-conduits for air as well as fuel.

In order to include the illustrations in the minimum amount of space, some of the views show the gear pump inverted, or in a sidewise position, but the proper operating position is shown in Fig. 1, with the by-pass outlet I8 and by-pass conduit I4 at the top.

This by-pass conduit communicates with a fuel reservoir 20, 'from which the excess fuel is returned freely to the tank IIJ, and since the outlet is at the top of the pump, the fuel reservoir will at all times be iilled with a supply of liquid fuel. Liquid fuel is thus available for priming the pump at all times.

'I'he pump preferably comprises a` pump hous-`1 ing 2 I, which is formed with a pump chamber 22 and a fuel reservoir 20, separated bya partition 23. 'I'he pump housing 2| may be substantially cylindrical in shape, as shown in Fig. 2, and may have an axially extending wall 24 at one side of Fig. 3, provided with an internal cylindrical surface 25, forming the pump chamber.

The adjacent surface 26 of the partition 23 y maybe a plane surface for engaging the fiat ends of the gears. The pump chamber is completed by means of a cover plate 21, which may consist of a cast metal member of circular shape and having adjacent its outer edge a plane seating surface 28, which is adapted to t against the p lane seating surface 29 that is provided on the edge of the axially extending flange 24. These surfaces may be lapped and ground to an accuratet.

The flange 24 has threaded bores 30 for receiving the screw bolts 3|, which pass through apertures in the cover plate 21 and are threaded in the bores 30 to secure the cover plate on the housing 2 I.

The cover plate 21 is adapted to support a pair of integral, arcuate members or shields 32, 33, which are of sufficient depth to extend from the cover plate between the gears to the fiat surface 26, and bear a particular relation to the gears of the pump, as will be described in full hereinafter.

The pump gears include an internal gear 34, another gear member 35, which is not only provided with `external spur teeth, but with internal teeth, and a pinion 36. The partition 23 is provided with a centrally located bore 31 adapted to receive, with a pressed frictional fit, a bearing member 38 for the drive shaft 39.

The drive shaft 39 is rotatably mounted in the bearing 38 and is also rotatably supported by a second self-lubricating bearing 40 ofthe type constructed of a porous bearing metal which has been soaked or impregnated with lubricant.

'Ihe shaft 39 extends into a cylindrical aperture 4| in the pinion 36, pinion 36 being provided with oppositely located slots 42 for receiving a key 43. The key 43 may consist of a flat piece of metal which is alsov located in a complementary slot 44, formed in the end of the shaft 39. Thus the pinion 36 isl adapted to be rotated or driven by the shaft 39, which in turn is driven by the motor I1.

The arcuate shield 32, carried by the cover 21, has its innermost partially cylindrical surface 45 formed with respect to the center or axis of the shaft 39, which is indicated by the point 46. The outer partially cylindrical surface 41 of the shield 32 is formed on a longer radius, which corresponds to the radius of the circle at the outer edges of the teeth of the internal gear teeth of member 35.

'I'he center with respect to which this outer surface 41 is formed is indicated at 48.

It should be understood that all of the gear members herein are preferably formed with helically or spirally extending teeth and bearing such a relation toward the outlets that the shape of the teeth tends to force the liquid longitudinally of the gears, toward the proper outlet.

For the purpose of clarity and simplicity, however, the helical teeth are not specifically illustrated in the drawings, which are tobe regarded as diagrammatic in this respect.

,The radius of the internal cylindrical surface 45 is equal Ato the radius of a circle located at the outer edges of the teeth of thepinion 36. Thus the arcuate shield or member 32 is adapted to fit inside yof the internal gear teeth of the member 35 and outside the teeth of the pinion 36. Its length is slightly less than the intersection of the two circles by means of which it is indicated, for the reason that it is undesirable to have sharp points on the shield 32, and better construction at such a point that it covers a predetermined number of tooth depressions.

It is inherent in a construction of the type involving pinion 36 and internal gears of member 35 that there must be more teeth in the larger internal gear than there are in the pinion. Thus the pinion 36 has seven teeth, while the internal teeth on the gear member 35 number nine.

The shield 32 not only serves to cover a predetermined number of tooth grooves, but it also serves to keep the gear members in their proper positions in connection with the other shield 33, now to be described.

The gear member 35, which has external gear teeth and internal gear teeth, is adapted to be rotated by the pinion 36, and its teeth engage in the grooves between the internal teeth of the internal gear 34.

The internal gear 34 is adapted to be rotated by the gear member 35, and thus internal gear 34 slidably engages the cylindrical Wall 25 and the flat surfaces of the adjacent cover 21 and partition 23.

It should be understood that all of the gears and fiat or plane end surfaces engage the complementary surfaces on the inside of the cover 21 and the surface 26 on the partition 23. Furthermore, the width of these gear members is such that there is a substantial t between the chamber 22 of the gears; that is to say, a close sliding t, which is made fluid-tight by the presence of the liquid fuel, which also has some lubricating qualities.

In all gear pumps there is a certain amount of leakage or slippage of liquid fuel past the gear teeth, and uid passes through the spaces at the ends of the gears. That is also true in the present case, as it is necessary to have the gears free for sliding motion in the chamber 22, in order to reduce friction.

The arcuate shield member 33 is so located inside of the cover 21 that it is adapted to engage the outside of the teeth on gear member 35 and the inside edges of the teeth on the internal gear 34.

This arcuate shield member has an internal, partially cylindrical surface 49, which is formed on a radius that is equal to the radius of the circle located at the edges of the external teeth of the gear 35. y The center with respect to which the cylindrical surface 49 is formed is the center of the gear 35; that is, the point indicated at 48.

The external partially cylindrical surface 50 of the arcuate shield 33 is formed on a radius which is equal to the radius of a circle located at the inner edges of the teeth of the internal gear 34. .f

The center with respect to this cylindrical surface 50 is formed in the center of the drive shaft,

indicated at the point 46.

In this case the arcuate shield 33 is again made shorter than the distance between the intersecting points of the arcs 49'and 50, in order that it may be of suitable strength at its ends, and in order that it may merely cover a predetermined number of tooth spaces; for example, four tooth spaces in the internal gear 34 are covered by the shield 33.

Whereas the gear member 35 has sixteen external teeth, the internal gear 34, being larger, naturally has a larger number of inwardly projecting teeth, eighteen in number.

All of the gear members 34, 35, and 36 rotate together, being driven from the same shaft; and,

involves the rounding olf of the ends 0f the shieldsince they operate like a train of gears, the internal gear being the last in the train, there is no backlash or lost motion between the gears, which are constantly driven in the same direction.

It will thus be observed that by means of these gear members there is provision for two separate stages or pumps; that is, the pumping which is accomplished between the teeth of the pinion 36 and internal teeth of gear member 35, which may comprise one stage, and the pumping which is accomplished between the external teeth on gear member 35 and the internal teeth of internal gear 34, which may comprise another stage.

The two stages rotate at the same number of revolutions per minute, but the outermost stage, or gear teeth, are larger in number, even if they are of the same size, and therefore must pump a larger volume of liquid fuel.

It will thus be observed that I have provided 0 two stages, one of which pumps an excess of fuel over the other, and I prefer to utilize these two stages in such manner that the outermost stage is used as the first stage, pumping an excess of fuel, and the innermost stage is used as a second stage, utilizing only what fuel it needs,

but producing the high pressure which is desired for an oil burner. With this in mind, I

shall now describe the location of the conduits by means of which the liquid is conducted to the proper points in the two stages of the pump.

It should be understood that while the gear members are shown having teeth of substantially the same size, the teeth in the outermost stage may be made of different size from the teeth in the innermost stage, or vice versa, providing, however, that in -each case the teeth which intermesh must be of the same size.

The cylindrical housing 2l is provided with a pair of downwardly projecting lugs -4I, 52, and with an upwardly projecting lug 53' (Fig. 1). These lugs are cored out to provide conduits, such as the by-pass conduit I8, the inlet conduit 53, and the outlet conduit 54. Fig. 4,.which is a section taken on the plane of the line 4--4 of Fig. 2, shows the inlet conduit 53, which extends into the partition 23, and is provided with a laterally extending portion 55, terminating in the fiat face 26 in an aperture 56, shown in dotted lines.

This aperture 56 is located at the point where the teeth of the internal gear 34 begin to separate from the external teeth on the gear member 35, as these gears rotate in a counter-clockwise direction in Fig..2. The port 56 then is the 1nlet port for the rst stage of the pump, and liquid fuel is sucked up through the conduit 53 into the spaces between the teeth 51, 58 and carried on around with the gear members 34 and 3 5 to the discharge aperture 59, seen in dotted l1nes at the right of Fig. 2. 'I'here the liquid is squeezed out from between the spaces between the teeth on account of the closer engagement of the teeth. The liquid does' not leak past and back of the teeth 51, 58 because at all times there is a sliding engagement between certain of the teeth 51, 58 or between tooth 58 and the inner surface 49 of shield 33, or tooth 51y and the outer surface 50 of shield 33. The

aperture 59 is then the outlet aperture for the rst stage, and it is shown in Fig. 5 as being in communication with the reservoir 20.

The reservoir 26 is formed by an axially extending flange 60 carried by partition 23, and

l it is closed by means of a gasket 6I and a. resilient diaphragm 62, both of which are clamped underneath another cover plate 63, by means of screw bolts 64.

The screw bolts 64 pass through the apertures in the cover plate 63, and are threaded into threaded bores in the ange 68. The diaphragm 62 has the centrally located aperture 65 for pass.. ing the shaft 39 and has a metal collar 66, which is provided with a plane surface 61 that has a lapped or ground fit with a rib 68 carried by the collar 69.

The collar 69 is a tight frictional fit on the shaft 39, and the surfaces on the collars 66 and 69 are held in tight engagement with each other by the spring 10, which is compressed between the collar 66 and a hub 1I.

The spring 10 is of suicient size to be spacedy from the shaft 39, and it is held in place by the projecting bearing 38, which also serves to space the spring from the shaft. A fiber washer 12 may be interposed between the collar 69 and the self-lubricating bearing 40, which is provided with a thrust surface. A

'I'he cover plate 63 may also have a lubricant reservoir 13, which is filled with a fibrous material 14, impregnated with semi-solid lubricant adapted to be fed to the porous bearing 48. The diaphragm 62 is thus adapted to prevent leakage of liquid from the reservoir 20, and theonly points of moving contact are those at engaging surfaces on the collars 66 and 69, which may be provided with a lapped fit so that there is practically no leakage past the spaces between these collars. In any event, the reservoir. 20 is, according to Fig. 6, which happens to be upside down. in communication with the by-pass conduit I8 that leads by means of conduit I4 directly back to the tank.

The first stage, therefore, merely keeps the reservoir 20 filled with liquid fuel, which is under no greater pressure than that involved by the resistance of the by-pass pipe I4 leading back to the tank, and the pressure in the reservoir 20 is substantially atmospheric. Under these conditions there is a tendency toward practically no leakage past the sealing collars 66, 69.

The intake port for the second stage, or smaller gears, is the aperture 15, shown in dotted lines in Fig. 2, which, according to Fig. 4, is also in communication with the lower part of the reservoir 29. Since this intake aperture extends from the lower part of the reservoir 20, there is absolute assurance that intake port 15 of the second stage or high pressure gears will always be covered, so that the second stage4 will be self-priming. Liquid fuel enters at the port 15 into the interstices between the teeth 16, 11 of the smaller gears and is carried on around to an outlet port 18. Outlet port 18 is formed in the cover plate 21, being a cored conduit which leads radially of the cover plate 21 and inside the cover plate to a port 19 that registers with a port 80 carried by the pump body. The port 8Il,of the pump body communicates with the outlet conduit 54 and is intended to be connected tothe pipe I5, which leads to the nozzle of the oil burner.

It will thus be observed that all of the inlet and outlet ports I8, 53, and 54 are provided with pipe threads so that they can be connected to the pipes I2, I4, and I5.

The pinion 3s is, of course, heid in piace by v being mounted on the shaft 39 and by its engagement with the cylindrical surface 45 on the the shield 33.

, 26 inside of the cover plate 2l.

, gagement of the outer cylindrical edges of its teeth with the cylindrical surface 49 on the shield 33. It is also held in place by the engagement of the inner cylindrical edges of its teeth l1 .with the outer cylindrical surface 61 on the shield 32.

The length of the shields 32, 33 is such that -they cover such an 'arc of such a number of teeth'or such a portion of the cylindrical edge surfaces of the teeth that the lgears are positively held in proper position.

The operation of the gear pump will be evident from the foregoing description and explanation of the operation of its parts. The pinion 36 is driven'by the shaft 39, which in -turn drives the gear member 35 by virtue' of itsinternal teeth. The gear member 35 in turn drives the internal gear 34. Thus the two stages of the pump are simultaneously driven, and the outer or first stage, having more teeth, is adapted to pump more than the inner stage. The reservoir 2l). i's thus adapted to be constantly lled'with an excess of liquid fuel, which is taken from the reservoir by the inner stage and delivered to a nozzle in such volume with respect to the nozzle capacity that a suitabl pressure is produced.

It should be understood that in any gear pump the size of the gears in relation to the nozzle capacity and the speed of rotation determines the pressure produced, disregardingl cer.

tain other minor factors.

Referring to Fig. 8, this is a modification in which the gear member 35 is indicated by the numeral 35a to signify that it has been changed,

and it is provided with axially, inwardly extending annular grooves 85 and 86, and the cover plate 21a is provided with an inwardly extending annular rib 81, while the partition 23a hasan inwardly extending annular rib 88. The rib 88 has a sliding iit in groove 86, and rib 81 has a sliding fit in groove 85. `Thus, in this case the gear member 35a is rotatably and slidably mounted on the ribs 81, 88, in addition to the other elements of the pump, holding this lgear member in place.

The shields 32 and' 33 are particularly adaptv ed to be machined with arminimum number of settings, because they are formed only upon two different centers, and only two settings with respect to the centers are required. The present construction is simpler than the devices of the prior art, and therefore is adapted to perform its functions better.l

Due to the two-stage arrangement, this pump may be used as a fuel pump Wherever there is a heavy suction on the intake pipe or where there is liquid fuel under pressure applied to the intake pipe. Since the pump is self-priming, it will operate under all conditions,`and the first stage is practically self-priming because it does not pump against any substantial pressure. By the time the liquid fuel in the reservoir is exhausted, the rst stage will have primed itself completely, due to the remaining film of liquid fuel serving as lubricant on the gears, and Will have eliminated all air.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be ylimited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a gear pump, the combination of a housing provided with a pump chamber and bearings for a drive shaft, a drive shaft in said bearings, a driving gear carried by said drive shaft in said pump chamber and having external teeth and tooth spaces, a gear member carried in said housing surrounding said rstmentioned gear and having internal teeth, said gear member also having external teeth and a third gear member rotatably mounted in said said pump, said housing also having arcuate shields between the teeth of said gear members for maintaining the alignment and location of said gear members, said housing being formed with reservoir, and one of the stages of said pump. discharging into said reservoir,

`and the other of said stages having its intake port communicating with said reservoir.

2. In a gear pump, the combination of a houspump chamber and having external teeth and 'Y tooth spaces, a gear member carried in said housing surrounding said first-mentioned gear and having internal teeth, said gear member also having external teeth and a third gear member rotatably mounted in said housing and having internally extending teeth for engaging the second-mentioned gear member, said housing having intake and outlet conduits extending to suitable points between the intermeshing teeth of said gear members whereby pumping is accomplished in two stages in said pump, said housing also having arcuate shields between the teeth of said gear members for maintaining the alignment and .location of said gear members, said housing being formed with a reservoir, and one of the stages of said pump discharging into said reservoir, and the other of said stages having its intake port communicating with said reservoir, said reservoir having a free return conduitto .the source of supply whereby it is at substantially atmospheric pressure, and said drive shaft extending through said reservoir.

3. In a two-stage gear pump, the combination of a housing provided with a pump chamber and having -three gear members in said pump chamber, said housing having bearings for a drive shaft, and a drive shaft in said bearings projecting into said pump chamber, said gear members comprising a pinion carried by the drive shaft, a gear member having internal and external teeth, the internal gear teeth being engaged'by said pinion, and a gear member having internal teeth engaging the external teeth of said second-mentioned gear member, said housing having intake and outlet conduits communieating with the spaces between the intermeshing teeth of the two stages, and having arcuate members for maintaining coverage of the gear tooth spaces-and for separating the gear teeth during their, rotation a-t a predetermined point.

4. In a two-stage gear'pump, the combination of a housing provided with a pump chamber and having three gear members in said pump chamber, said housing having bearings for a drive shaft, and a drive shaft in said bearings projecting into said pump chamber, said gear members comprising a pinion carried by the drive shaft, a gear member having internal and external teeth, the internal gear teeth being engaged by said pinion, and a gear member having internal teeth engaging the external teeth of said second-mentioned gear member, said housing having intake and outlet conduits communicating with the spaces between the intermeshing teeth of the two stages, and having arcuate members for maintaining coverage of the gear tooth spaces and for separating the gear teeth during their rotation at a predetermined point, the outlet from the first stage of said pump being in communication with the vinlet of the second stage of said Dump- 5. In a two-stage gear pump, the combination of a housing provided with a pump chamber and having three gear members in said pump chamber, said housing having bearings for a drive shaft, and a drive shaft in said bearings projecting into said pump chamber, said gear members comprising a pinion carried by the drive shaft, a gear member having internal and external teeth,- the internal gear teeth being engaged by said pinion, and a gear member having internal teeth engaging the external teeth of' said second-mentioned gear member, said housing having intake and outlet conduits communicating with the spaces between the intermeshing teeth of the two stages, and having arcuate members for maintaining coverage of the gear tooth spaces and for separating the gear teeth during their rotation at a predetermined point, the outlet from the first stage of said pump being in communication with the inlet of the second stage of said pump, through a reservoir, said reservoir being located about said drive shaft, and said drive shaft having packing located beyond said reservoir.

6. Ina two-stage gear pump, the combination of a metal housing formed with a centrally located partition and a pair of axially extending cylindrical anges, one of said cylindrical flanges forming a pump chamber, and the other of said cylindrical anges forming a reservoir, said partition having a bearing, a drive shaft in said bearing, a cover plate Afor said pump chamber, a pinion carried by said drive shaft in said pump chamber, and a second internal and external gear toothed member surrounding and meshing with said-pinion in said pump chamber, an internal toothed member surrounding and meshing with said second gear memberv in said pump chamber, all of said gear members being driven from said drive shaft, arcuate shields carried by said housing between the intermeshing teeth of said gear member, an intake conduit extending into said pump chamber in communication with the tooth spaces between the two outermost sets of gear teeth, a discharge conduit extending from the tooth spaces between said gear teeth to said reservoir, an intake conduit leading from said reservoir to'the gear tooth spaces between the teeth of the other intermeshing gears,and an outlet conduit extending from the tooth spaces between said other intermeshing gears, said reservoir having a cover plate through which said ,drive shaft extends.

shaft, a drive shaft in said bearing, a drivingA pinion concentrically carried by said drive shaft in said pump chamber, and vhaving external teeth and tooth spaces, an internally toothed gear member having an external cylindrical surface rotatably mounted in said housing and concentrically rotatable in said housing, said cylindrical surface engaging the outer cylindrical wall of said housing, and a third floating gear toothed member having internal and external teeth, and tooth spaces, the internal teeth of said floating member meshing with the teeth of said driving gear, and the external teeth of said oating member meshing with the teeth of said internally toothed member, said housing having intake and outlet conduits for the space between the driving gear and the floating member and for the space between the floatingI member and the internally toothed member, and an arcuate shield between said driving gear and said fioating member for holding the external teeth of said oating member in engagement with the internal teeth of said internally toothed member, and covering predtermined toothed spaces, and a second arcuate member located between said oating member and said internally toothed vmember, and covering predetermined toothed spaces.

ARTHUR C. KLECKNER.

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