US3015282A - Pump - Google Patents

Description

Ja 2, 6 A. A. CAMARATA 3,015,282

PUMP

Filed Feb. 16, 1959 United States Patent 3,015,282 PUMP Alfred August Camarata, Cedar Falls, Iowa, assignor to Viking Pump Company, Cedar Falls, Iowa, a corporation of Iowa Filed Feb. 16, 1959, Ser. No. 793,557 2 Claims. (Cl. 103-126) This invention relates to pumps and particularly to an arrangement for the pressurized self-lubrication and hydraulic balance of positive displacement rotary pumps.

It is the principal object of the invention to provide in a rotary pump a simplified arrangement for utilizing the pumped liquid at the developed pressure for the forced lubrication of certain rotary elements, and at the same time to provide hydraulic balance of the rotary parts involved. A further object of the invention is to provide the aforesaid self-lubrication and balance in a reversible pump'independently of the direction of rotation.

Other objects and advantages 'of the invention will become apparent from the following description and the accompanying drawings, which illustrate the application of the invention to a gear pump of the internal gear type.

FIGURE 1 is a sectional view of the aforementioned pump taken perpendicularly to the pump axis (on the line 1--1 of FIG. 2), and having certain parts partially broken away for clarity of illustration;

FIGURE 2 is a sectional view through the rotary axis of the pump, taken on the line 2-2 of FIG. 1;

FIGURE 3 is an enlarged fragmentary sectional view of the pump taken on the line 33 of FIG 1; and

FIGURE 4 is a partial sectional view similar to FIG. 2 but with the pump housing removed to facilitate reference to the moving parts of the pump, particularly in connection with the hydraulic balance achieved by the disclosed pressure-lubrication system.

Referring particularly to FIGS. 1 and 2, the illustrated gear pump comprises a pump housing including a cup-shaped casing which has a central bearing 12 suitably bushed to journal an input drive shaft 14, and is closed at the side opposite the bearing 12 by a head or cover plate 16 secured to the casing by means of cap screws 18 or the like. As indicated,-the two-part housing may be of cast construction suitably machined for assembly and for proper fit with parts yet to be described.

The cover plate 16, to which detailed reference will later be made, forms with the casing 10 a cylindrical pumping chamber 20 in which the rotary pump parts operate to draw liquid into the housing through one radially extending opening 22 in the casing 10 and expel it from the chamber througha similar radially extending outlet opening 24, or vice versa, after traveling a gen erally peripheral path of about 270 degrees through the housing. As will later appear, the pump is reversible in character, operating equally wellin either direction of rotation.

Securely fitted on the end of the drive shaft 14 within the pump housing is an internal gear or rotor 26 which consists essentially of a heavy circular disk 28 having axially extending peripheral projections 30 formed as internal gear teeth. The cover plate 16 of the pump is provided with a stub shaft 32 which extends axially into the pump chamber eccentrically to the input shaft 14 and forms a journal for an idler gear 34 which is disposed in meshing engagement with the teeth 30 of the rotor 26 (as shown in FIG. 1). A crescent-shaped projection 36, formed integrally with the cover plate 16, extends into the pump chamber in the space between the two gears, with its end face in close proximity to the inside face of the motor. 26. The inner and, outer surfaces of "ice the crescent-shaped member 36 are circular arcs on the centers respectively of the idler 34 and the rotor 26, and are wiped by the teeth of those gears when the pump is in operation.

Referring to FIGURE 1, it will thus be understood thatwhen the rotor 26 is driven in a counter-clockwise direction, the internal idler 34 is driven thereby in the same direction, drawing liquid into the pump housing through the inlet opening 22 into the increasing spaces between the disengaging teeth of the two gears, and conveying it toward the outlet opening 24, Where the reengaging teeth of the gears expel the liquid from the pump housing under pressure through the outlet opening 24.

The high pressure and low pressure zones of the pump are separated from each other by the engaged gear teeth and by the closeness of the fit between the inner faces of the two gears and between their outer faces and the pump housing, as well as by the close peripheral fit of both gears with the walls of the pump chamber and the crescent 36 which fills the eccentric space between the two gears.

The illustrated clearances are exaggerated for clarity of illustration, but are maintained sufficiently close in actual operation that no appreciable amount of liquid is by passed by leakage between the high and low pressure zones through the running clearances.

In the illustrated pump, the idler gear 34 is lubricated and balanced axially on its supporting shaft 32 by the pumped liquid which is delivered from the high pressure side of the pump to the journal of the idler gear 34 through a system of channels and valves which operates efiectively regardless of the direction of rotation of the pump.

For this purpose the inside face of the cover plate 16 is relieved in two areas 38 and 40 respectively adjacent the two ports 22 and 24 of the pump casing 10, leaving an intermediate barrier against which the close fit of the outer faces of the two gears is maintained, and which also provides a boss 42. in which the stub shaft 32 is securely maintained by a press fit. The relief of the inside face of the cover plate 16 provides an enlargement of the low and high pressure areas within the pump chamber.

Within each relieved area 38 and 40 of the cover plate 16, there is further formed a recess 44, the purpose of which is to provide a flat surface 46 on the boss for the stub shaft 32 through which to bore passageways 48 generally radially, through the boss 42 but at a slight angle to the axis of the stub shaft 32. Each of the passageways 48 is tapped to receive the threaded body of a spring-and-ball check valve 50 which is designed to pass liquid only radially inwardly through the passageways 48.

As indicated particularly in FIGURE 3, the body of the check valve 5% may be hollow, its inner space 52 communicating with the pump chamber through a small passage 54 having a conical seat 56 which is normally closed by a ball valve element 58. The opposite or inner end of the valve chamber 52 is provided with interior threads to receive a plug 60 which forms a seat for the valve spring 62, and which may be adjusted axially of the valve body to adjust the pressure at which the valve opens. A small opening in the center of the plug 60 completes the channel from the stub shaft to the pump chamber.

3 and the two chambers 48 in the boss 42, and radially near its inner end to provide a passage 68 between the central shaft passage '64 and the surface of the journal for the idler gear 34. As shown particularly in FIGURE 2, the surface of the journal is grooved at the outer end of the radial bore 68, the groove 70 extending axially of the journal in both directions from the radial bore 68, but not fully to the ends of the journal. The idler gear 34 is provided with a bushing 72 of sufiicient length to extend axially beyond the groove 70 in both directions as shown in FIGURE 2.

In the operation of the pump, assuming again a counter-clockwise direction of rotation as seen in FIGURE 1, the right hand side of the pump is the high pressure zone and the left hand side the low pressure zone. By the same token, the check-valve in the high pressure zone 38 is opened by the pumped liquid which is delivered through the aforementioned channels to the journal for the idler gear 34 to lubricate the engaged surfaces of the stub shaft'32 and the bushing 72 of the gear. The high pressure liquid is prevented from direct access to the-low side of the pump by the opposite check-valve in the low pressure zone 40.

The running clearance between the bushing 72 of the idler 'gear and the journal surface of the stub shaft 32, while throttling the flow of liquid through the lubrication system suficiently to maintain the liquid in the hearing at a pressure approaching the pump delivery pressure, neverthel'ess permits escape of the pumped fluid from the ends of the bushing 72 to both faces of the idler gear 34, which are disposed in close proximity to the inner face of the cover plate 16 and the inner face of the rotor gear 26 respectively. The running clearances between those faces are shown in exaggerated form in FIGURE 4 as spaces A and B, and it will be apparent that pumped liquid escaping in both directions from the idler gear journal finds access to the aforementioned clearance spaces. In the spaces A and B the liquid escaping from the journal lubricates the faces of the relatively moving parts, providingby pressurized flow a film of. liquid which maintains the idler gear 34 in a state of floating balance between the rotor gear 26and the face of the cover plate 16. Inasmuch as the contact areas between the hub portion of the idler gear 34 and the adjacent surfaces of the rotor gear 26 and thecover plate 16 are substantially the 'same, axial movement of the idler gear in either direction momentarily increases the pressure in the liquid film on the advancing side of the idler, creating a momentary imbalance in the axial forces on the idler which moves the idler back toward a more central position on the journal.

When the direction of rotation of the pump is reversed, the operation of the self-lubrication and balancing system remains essentially the same with the exception that the check-valve whic'h was previously open is now closed, and

that which was closed is now opened. The direction of flow of pumped liquid through the stub shift 32 and the journal of the idler gear 34 remains the same in both instances.

In the above-described system, the idler journal is constantly lubricated and cooled, and the idler gear is buffered on both faces by a film of the pumped liquid which prevents galling and seizure at the contact surfaces of the 4 relatively moving parts. As a result, pump maintenance is materially reduced and the useful life of the pump is greatly extended. 7

Features of the invention believed new and patentable are set forth in the appended claims.

I claim:

1. In a reversible gear pump, a pump housing, a driving gear journalled in the housing, a smaller idler gear within and in meshing engagement with said driving gear, said idler gear being journalled eccentrically to said driving gear on a shaft fixed in the wall of said housing and being formed so as to provide a clearance space adjacent each face of said idler gear, said housing having a crescentshaped projection extending into the eccentric space between said two gears, said gears dividing said .pump into high and lower pressure zones, said housing and shaft having formed therein at least one continuous communicating passageway extending from said high pressure zone regardless of the direction of rotation of the pump to a point on said journal which is midway between the high and low pressure zones of the pump on the side of the journal which is farthest from the full meshing point of the gears and extending through said idler gear journal and into said clearance spaces adjacent said idler gear faces so as to fill said clearance spaces, a portion of-the pumped liquid being thereby continuously diverted under maximum pump pressure to the journal and equally to the idler gear faces irrespective to the direction of rotation of said gears so as to lubricate and cool the journal and provide axial balance for said idler gear, a portion of the length of said passageway being at and enclosed within the surface of said shaft, and a check valve in said passageway permitting liquid to flow only from the high pressure zone to the journal. i

2. A reversible gear pump as set forth in claim 1, wherein said one continuous communicating passageway comprises a first transverse passage in said idler gear shaft, an axial passage in said idler shaft in communication with said first transverse passage, a second transverse passage in said idler gear. shaft generally midway of said idler gear, and a groove extending lengthwise along the periphery of said idler gear shaft and having communication with said second transverse passage, said groove terminating at its opposite ends at positions inwardly of the ends of the journal on said shaft'for said idler gear.

References Cited in the file of this patent UNITED STATES PATENTS Zieg etal. June '14, 1960

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