US2394860A - Fuel pump - Google Patents

Description

Feb. 12, 1946..

' -ammumt -l A. cQ KORTE Filed Jan. 27, 1943 FUEL PUMP 2 Sheets-Sheet 1 ALFRED C. KORTE INVENII'OR ATTORNEY Feb. 12, 1946. A. c. KORTE 4,

FUEL PUMP Filed Jan. 27, 1943 2 Sheets-Sheet 2 INVENTOR ATTORNEY ALFRED c, KORTE' M 4 M, w 35; g @w 131::

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Patented Feb. 12, 1946 FUEL PUMP Alfred C. Korte, St. Louis, Mo., asslgnor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application January 27, 1943, Serial No. 473,683

11 Claims.

This invention relates to fluid pumps and consists particularly in a novel pump and motor unit arranged for operation submerged in a pool of liquid.

A pump designed for use with volatile liquid should have its inlet throat facing upwardly and the overlying structure arranged to permit the escape of bubbles, formed near the pump throat, to the surface of the liquid rather than into the pump casing. In the case of fuel pumps for internal combustion engines, vapor lock frequently occurs becauseof the substantial fillin of the pump casing'with gas, particularly after the hot engine stops. This retards or prevents pumping of fuel until the trapped gas is condensed or otherwise dissipated.

Mounting of the pump in the gasoline tank so as to push the fuel toward the carburetor substantially reduces the chances of vapor lock as against the usual automotive practice at present where the fuel pump is supported remotely from the tank and draws fuel therefrom. In Patents Nos. 2,271,650, 2,261,915, 2,260,946, and 2,319,934, all in the name of the present inventor and another, there is,illustrated and claimed an electrically operated centrifugal pump unit for operation submerged in an automotive fuel tank so as to provide for effective supply of fuel under normal fuel conditions. However, when the fuel is exposed to abnormally high temperatures, as in military vehicles, where the engine and fuel tank are enclosed by armor plate, gas bubbles may rise into the pump and motor chambers with serious effect.

A centrifugal pump having an upwardly facing inlet throat produces a swirling of the liquid entering the throat and, when the liquid level is lowered to six or eight inches from the throat, air may be drawn thereinto through the center of the vortex.

Accordingly, then, it is an object of the present invention to construct a rotary pump having an upwardly facing inlet throat, while at the same time, preventing the formation of a vortex above the throat through which air may be drawn.

Another object is to provide a pump and motor unit with the motor mounted closely above the pump, but constructed to permit the free entry of liquid into the pump and the escape of gas bubbles from the 'vicinity of the pump throat.

Another object is to provide an electric pump unit for operation submerged in a liquid tank with means forsupplying substantially gas free liquid to both the pump outlet and the interior of the motor casing for lubricating the bearings.

sun another object is to provide a motor pump 'unit of the above type which may be readily assembled and disassembled to facilitate manufacture and servicing thereof.

These objects and other more detailed objects hereafter appearing are attained substantially by the device illustrated in the accompanying drawings in which:

Fig. 1 is a diagrammatic view showing a fuel tank, pump and carburetor as commonly used with internal combustion engines.

Fig. 2 is a top view of the pump which embodies the present invention.

Fig. 3 is a section taken substantially on line 3-3 of Fig. 2.

Fig. 4 is a top view of the pump impeller disassembled.

Fig. 5 is a vertical, transverse section taken on a diameter of the impeller.

Fig. 6 is a top view showing the lower part of the motor housing disassembled.-

Fig. '7 is a side view of the same, a portion being sectioned and part of the underlying structure being shown for clearer illustration.

Fig. 8 is a bottom view of the housing part in Figs. 6 and '7.

Figs. 9 and 10 are diagrammatic representations illustrating the manner of functioning of the structure in breaking up the liquid vortex which tends to form adjacent the pump inlet throat.

In Fig. 1, a fuel pump 12, to be described in detail hereafter, is shown supportedin the'fuel tank i3 and provided with an insulated electrical connection M to the battery i5, and outlet tubing !6 extending to the carburetor l! for forming the combustible-mixture in the usual manner. Tank [3 may be mounted at any point with respect to the carburetor and battery and only a. single tube I6 is required between the tank and carburetor and a single connecting wire between'the battery and motor, assuming the tank and battery are grounded to the vehicle frame, as is the usual practice. Y

The pump unit comprises a motor housed in upper and lower, separatelyformed castings i8 and i9. Part l8 has ears 20 secured to flange 21 on part ill by bolts 23. Corner bosses 24 on the lower casting provide for vibration damping mountings as disclosed.in Patent No. 2,271,560. Upper part 20 has an apertured boss 25 within which is yieldingly supported a contact 26 upon a coiled spring 21 and connected by wire 28 to motor field 29. A plug 30 threaded into the boss carries a contact 3| connected to wire I4. Plug screen for washing the same.

rib 31, opposite passage 50, drains collected mat- 30 may be adjusted to maintain elements 26 and 3| in firm electrical contact.

A Journal bearing 32 is supported in a hollowed boss 33 in the center of housing part l8, one or more grooves 34 in the bearing opening to the outside of the housing through extended lateral passages 35. Field structure 29 is supported in this part of the housing in suitably grooved ribs 36.

Lower housing part i 9 (Figs. 6, 7 and 8), generally, is of conical shape with a series of radial ribs 31, 38, 39 and 46 formed on the underside thereof and terminating in apertured foot lugs 4|. Each of ribs 38, 40 extends above the housing wall and is provided with a brush pocket, one being shown at 42 in Fig. 3, receiving a brush, as at 43, constantly urged inwardly against commutator 44 by a coiled spring as at 45, compressed between the brush and a screw plug 46, closing the outer end of the brush pocket. Rib 40, shown in Figs. 3 and 6, has a recess 41 in its upper edge receiving an insulated terminal 48 for connection to the current source in any suitable manner, the other brush being grounded. Rib 39 is enlarged as at 49 and is provided with a diagonal duct 50 for conducting liquid into the motor housing, as will be described hereafter. Right hand rib 46 (Fig. 3) is provided with a second duct below the brush pocket for discharging liquid from the motor housing.

A journal bearing 52 is mounted at the apex of bottom housing part l9 beneath an upwardly projecting cup 53 on the inside of the casing part. Motor shaft 54 is supported in journal bearings 32 and 52, the upper end thereof terminating in boss 33 in engagement with a thrust screw 55 adjustable from outside the housing. Commutator 44 is located in cup 53 abreast the brushes, a shoulder 56 closely fitting the upper part of this cup as a flame propagation resistor. A filter screen 51 is secured between the housing parts and the downwardly tapering space 58 below this screen and outside cup 53 which forms a sump for collecting sediment, A jet forming nozzle 66 having inclined outlet apertures 6| directs the by-passed liquid from passage 50 against the A passage 8| in ter from the sump.

The centrifugal impeller 62 has a central hub 63 receiving the lower extremity of motor shaft 54, and provided with an eccentric pin 64 received ina slot 65 in the endof the shaft for causing the impeller to rotate with the shaft. A small drain hole 66 (Fig. 5) is provided adjacent pin 65.

- Spiral impeller blades 61 extend from the impeller hub outwardly, as shown. Underlying the impeller is a bottom plate 68 which, together with a top or throat plate 69 forms the voluted impeller casing. Plate 69 has a central opening forming the throat l0, substantially larger than impeller hub 63, and is thickened at its outer edge for mounting a screen 12. The size of throat is mathematically calculated in accordance with the capacity of the pump, it being important that this opening be neither substantially larger nor smaller than the calculated size.

Impeller 62 rests upon a thrust bearing ball 1| which, in turn, rests upon impeller casing bottom plate 68. A circular screen 12 encloses the space between the motor housing and the pump casing for filtering the fuel entering the pump throat. At the edges of the pump casing parts there are provided spaced bolting lugs as at 12 and 13 for attachment to foot lugs 4| on motor housing part I!) by bolts 14. Bottom plate 63 has a peripheral enlargement l5 forming an outlet fitting for connection of discharge tubing l6. The order of assembling the unit is as follows:

The motor armature and field are placed in upper motor housing part l8, lower housing part l9, carrying screen 5'|, is bolted thereto, throat member 69 is mounted upon foot lugs 4|, impeller 62 is fitted on the end of the motor shaft, and impeller casing bottom plate 68 is bolted in position. When so assembled, passage 56 in rib 39 registers with a port 16 in throat member 69 so that a portion of the pumped fuel is by-passed into the motor housing. Finally, the brushes are placed in their respective pockets and the electrical connection made.

The pumping unit operates as follows:

When current is applied to the motor, impeller 62 is rotated causing liquid fuel to be thrown outwardly into the voluted casing and thence through outlet tubing l6 to the carburetor. The swirling body of fuel adjacent the inlet throat strikes ribs 31, 38, 39 and 4|] on the conical lower part of the motor housing resulting in effective prevention of the formation of a vortex above the pump inlet, particularly, as the fuel level in the tank approaches the pump casing. These ribs terminate slightly above the pump casing (Fig. 7) to provide for freer ingress of fuel but these may be extended to the throat plate. Ordinarily, it is undesirable to pump fuel from the bottom of the tank because of the presence of water and sediment. Ample clearance is provided between the pump casing and the tapering bottom wall of the motor housing to permit bubbles formed in this space to escape to the surface of the fuel, as indicated by the dotted arrows in Fig. 3.

Figs. 9 and 10 illustrate the functioning of the device in breaking up of the fuel vortex. Fig. 9 represents, in section, the appearance of the body of fuel immediately above inlet opening 10 as the liquid level approaches to'within six or eight inches of the throat plate, if ribs 36 etc. were omitted. A conical void would be formed at the center of the vortex, as at through which air may be drawn into the pump. Fig. 10 indicates in broken lines the relative positions of'ribs 31, etc., and the action of the fuel adjacent the, inlet throat in rebounding from the ribs. The ribs effectively prevent the formation of the vortex but even without the ribs the conical lower wall of the motor casing would obstruct the center of the vortex and prevent the drawing of air into the pump. Adequate clearance is provided between the motor and pump casings for the entry of fuel and the discharge of bubbles by their own tendency to rise.

The motor housing is kept full of liquid fuel free of bubbles at all times during operation of the pump, this liquid passing in through duct 50 and out through passages 35, 5|, 66 and 8| and the space around the motor shaft below lower bearing 52. Thus, the bearings are adequately lubricated and no packing glands or bushings are required. Even though the motor runs in atcombustible fuel, there is no fire hazard because of the efiective bafiling at 56 and the elongated, restricted openings through the motor housing wall.

It is, of course, desirable that the pump inlet throat face in an upward direction and a free path be provided thereabove for the rising b'ubbles. However, this direction need not be vertical. The invention may be modified in various respects as will occur to those skilled in the art.

and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. A pumping unit for operation submerged in a body of liquid comprising a casing having partition structure forming spaced motor and pump chambers, a direct current electric motor including commutator and bearings mounted in said motor chamber, a cup-shaped flame baflie receiving said commutator, a centrifugal impeller mounted on the motor shaft in said pumping chamber, said latter chamber having an upwardly facing inlet opening freely communicating, between said chambers, with the body of liquid to be pumped, and a connection between said I chambers for maintaining the motor commutator and bearings bathed in the liquid during operation.

2. In a pump unit, an electric motor having a vertical shaft, a housing for said motor having a generally conical bottom, an impeller on the motor shaft below said housing, a casing receiving said impeller, a radial rib forming a rigid support between said housing and said casing, a motor brush mounted in said rib, and means to by-pass a part of the pumped liquid into said motor housing, said conical housing bottom receiving the motor commutator and providing for collection of sediment.

3. In a liquid pumping unit, a motor, a housing therefor, a partition screen in said housing, an impeller on the motor shaft, outside said housing, a casing receiving said impeller and having inlet and discharge openings, and a duct to bypass a part of the pumped liquid into said housing, said duct being shaped to discharge the bypassed liquid against said screen for filtering said liquid and washing said screen.

4. A pump unit as specified in claim 3 in which the bottom wall of said housing below said screen forms a sump for collecting sediment.

5. In a pump unit, casing structure defining motor and pump chambers, the bottom 'wall of said motor chamber being depressed to form a sediment collecting sump, a liquid =by-pass from said pump chamber to a point in said motor chamber substantially above the bottom of said sump for conducting a supply of liquid to said motor chamber during operation, and a second passage from the bottom of said sump for discharging liquid and sediment therefrom.

6. In apump unit, a housing having. a bottom wall with a central cupped part, an electric motor mounted in said housing with its commuta-.

tor in said cup'part, an impeller on the motor shaft outside said housing, a casing receiving said impeller and spaced from said housing, spaced elements rigidly connecting said casing and said housing, at least one of said elements extending laterally from said cupped part and being recessed, and a motor brush mounted in said recess part and normally engaging said commutator.

7. In a liquid pump unit for operation submerged in a tank, immediately adjacent motor and pump casings, said pump casing being below said motor casing and having an upwardly facing'inlet throat and said motor casing having a centrally depending element forming a motor shaft Journal bearing, and ribs projecting radially from said depending element and rigidly connecting said casings, said ribs forming substantial open passages between said casings for entry of liquid from the tank into said throat whilepreventing theformation of a vortex in the liquid above said throat.

8. A pumping-unit for operation submerged in a body of volatile liquid comprising a casing having partition structure forming spaced motor and pump chambers, a direct current electric motor including commutator, armature, and bearings mounted in said motor chamber, and a centrifugal impeller mounted on the motor shaft in said pump chamber, said pump chamber having 'an upwardly facing inlet opening freely communicating in a generally upward direction with the ambient liquid to cause release of bubbles in the vicinity of said opening, said casing having a relatively long and restricted passage leading to said motor chamber for supplying lubricating and cooling liquid to the motor while preventing the propagation of flame beyond said motor chamber.

. 9. A pumping unit for operation submerged in a body of volatile liquid comprising casing structure forming spaced motor and pump chambers, a direct current electric motor including commutator, armature, and bearings mounted in said motor chamber, and a centrifugal impeller mounted on the motor shaft in said pump chamspaced outwardly from said inlet opening for supplying substantially bubble free liquid to'said motor chamber while preventing the propagation of flame beyond said motor chamber.

10. In a pump device for volatile liquid, a

tator, a housing for said motor, a centrifugal pump having a casing with a central, upwardly facing opening for releasing bubbles from liquid being drawn into said opening, and an elongated, restricted passage extending to said motor housing from a portion of aid pump casing spaced outwardly from said opening for supplying bub- -ble free liquid to said motor housing for lubricating and cooling the motor.

11. In a pump device for volatile liquid, a direct current motor having an armature and commutator, a housing for said motor, a centrifugal pump having a casing with a central, upwardly facing opening for releasing bubbles, said motor housing having an upwardly diverging wall adjacent said central opening for diverting bubbles, and an elongated, restricted passage .extending to said motor housing from a portion of saidpump casing spaced outwardly from said bubble releasing opening for supplying bubble free liquid to said motor housing for lubricating and cooling the motor. ALFRED C. KOR-TE.

direct current motor having an armature and commu-

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