US 3028811 A
Description (OCR text may contain errors)
April 10, 1962 R. H. ROTHENMEYER GEAR KEY Filed May 28, 1959 2 Sheets-Sheet 1 FIG?) FIGZ l4 IO l6 l2 April 10, 1962 R. H. ROTHENMEYER 3,028,811
GEAR KEY Filed May 28, 1959 2 Sheets-Sheet 2 F I G. 4
i I I r so I 1 I I 1. r 4 5 FIG 7 o; e4 64 L, 62 \Q 30 E? I 30 H 42 FIGS United States Patent Ofifice 3,028,811 Patented Apr. 10, 1962 3,028,811 GEAR KEY Robert H. Rothenmeyer, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed May 28, 1959, Ser. No. 816,563 4 Claims. (Cl. 103-4) This invention relates generally to precision rotary metering pumps and, more particularly, to gear pumps adapted for use in advancing two or more streams of a viscous liquid at substantially constant and equal rates.
Precision rotary metering pumps have long been used in the synthetic fiber industry for advancing a viscous fiber-forming composition at a substantially steady flow rate to a spinneret, thus facilitating the production of exceptionally uniform filaments. Recently, such pumps have been modified so that two or more metered streams may be supplied from a single pump. Such a pump is disclosed by Hull et al. in US. Patent No. 2,533,320 and includes a pair of spaced, aligned drive gears each coupled to a common drive shaft by axial key means. Although such a key means permits quick and easy disassembly of the pump for repair and maintenance purposes, the freedom of the shaft to migrate axially leads to numerous problems such as excessive hub wear, scoring of the pad or plate against which the drive shaft abuts, scoring of the gears, etc., any of which difiiculties leads to a disruption of operations and necessitates renovation of the pump.
The most important object of the present invention is the elimination of drive shaft migration in a plural stream gear pump.
A further important object of the invention is to provide improved means for keying a plurality of drive gears to a common drive shaft. in a multiple stream rotary metering pump.
With these and other objects in view, the improvement of the present invention may be incorporated into a gear pump by keying each of a pair of drive gears to a common drive shaft with elongated keys, each key extending through and beyond a diametric keyway in the drive shaft and terminating at each end in a recess opening into one face and the bore of a drive gear. The two drive gears are mounted with their key-receiving recesses in the inner, adjacent faces thereof. Further objects will become apparent in the specification which follows, wherein reference will be made by the use of designating numerals to the accompanying drawings, in which:
FIGURE 1 is an exploded perspective view of the rotary pump into which the improvement of the present invention has been incorporated for purposes of illustration;
FIG. 2 is a side elevational view of a pump assembly from which the drive coupling has been omitted for purposes of clarity;
FIG. 3 is a vertical longitudinal section through the pump assembly of FIG. 2;
FIGS. 4 and 5 are plan and end views, respectively, of a pump drive shaft which has been adapted for use according to the teachings of the present invention;
FIG. 6 is an end view showing the relationship between the drive shaft and a drive gear;
FIG. 7 is a sectional view taken on the line VII-VII of FIG. 6; and
FIG. 8 is a plan view of the elongated key shown in FIGS. 6 and 7.
The principal components of a pump assembly into which the improvement of this invention has been incorporated are shown in FIGURE 1. When assembled, a pair of gear plates 10, 12 are sandwiched between front plate 14, middle plate 16, and back plate 18, as shown in FIG. 2. The various plates and the passages therein are illustrated in FIG. 3.
In the assembled pump, plates 10-18 are held together by fasteners which extend through a plurality of openings 22 provided therefor. The gear plates 10, 12 each have a gear-receiving opening 24 provided with a semicircular recess 26 at the top thereof and another such recess 28 at the bottom. A drive shaft 30 extends through openings 32 in plates 16, 18 and abuts in opening 34 on the inner face of plate 14. Within the openings 32, shaft 30 is carried by bearings 33. Drive shaft .30also mounts a pair of drive gears 36, each of. which has an axial bore 37. The drive gears 36 mesh with driven gears 38, both of which are mounted on a fixed shaft 40 which passes through openings 41 in plates 14, f16, 18. The pump gears 36, 38 all have parallel side aces.
Drive shaft 30 has a terminal fitting 42 which 00- operates with a mating part in a hub 44, the latter being adapted for coupling to a suitable drive means (not shown). Hub 44 is attached to back plate 18 by means of suitable fasteners which pass through openings 46 in hub plates 48 and through aligned openings in hub 44 and plate 18.
In operation, a viscous composition is pumped through an inlet passage 50 in front plate 14 which passage is in communication with the top recess 26 of gear plate 10. The first of the twin streams passes from bottom recess 28 of plate 10 through an outlet passage 52 in plate 14. Inlet passage 58 also communicates with the second pair of gears through top recess 26 of plate 10 and a passage 54 in plate 16. This second stream exits the pump along the following path: bottom recess 28 of plate 12, a con necting groove 56 in plate 16, and a passage 58 in fixed shaft 40.
As noted previously, the improvement of the present invention relates to the manner in which the drive gears 36 are keyed to the drive shaft 30. In FIG. 4,-drive shaft 30 is shown in detail to include a pair of transverse diametric keyways 60, each of which receives an elongated cylindrical key 62. Keys 62 are rounded at each end thereof and project radially from shaft 30 into a pair of opposed, semicircular recesses 64 which open into a side face and the bore 37 of the gears 36. In FIG. 1, it is seen that the opposed recesses 64 are formed in the inner, adjacent side faces of the gears 36.
The improvement disclosed herein has utility in preventing drive shaft migration and the previously enumerated difiiculties inherent in such migration. In the assembly, drive gears 36 and their associated driven gears 38 are located in a gear chamber defined by the edge of an opening 24 and the parallel surfaces of the two plates between which the particular gear plate is sandwiched. Each gear has the side faces thereof in close proximity to two of the plates 14, 16, 18 so that a thin film of the liquid being pumped exists between the plates and the gear faces, serving as a lubricant. Any migration-inducing thrust is transmitted by one of the keys 62 to a gear 36 and thence to the plate which is situated in the direction of the thrust, via the film of liquid, thereby positively eliminating any axial movement of the drive shaft in that direction. Since recesses 64 are in the inner, adjacent faces of gears 36, migration in either direction is precluded. In pumps wherein a plurality of drive gears are driven from a given shaft, only two of these need be keyed according to the teachings of the present invention.
The relatively inexpensive keying means disclosed herein may be incorporated into most plural stream gear pumps in use today, facilitates rapid and efficient 3 pump assembly, and contributes in a substantial way to pump longevity. Other advantages inherent in the practice of this invention will occur readily to those skilled in the art and, accordingly, its extent is intended to be limited only by the scope of the appended claims.
1. In a gear pump: a housing having therein at least two gear chambers each defined by opposed parallel end walls and a side Wall; a pair of meshing gears in each of said chambers, said gears having parallel side faces, one gear of each pair being a drive gear and having an axial bore; a drive shaft extending into said chambers and through said bores, at least two of said drive gears each having a pair of radially spaced recesses opening into one side face and the bore thereof, said recesses being located in opposite faces of the respective drive gears and extending only partially through the width thereof; and key means projecting radially from said shaft into each of said recesses.
2. The gear pump of claim 1 wherein said recesses open into the inner, adjacent faces of said drive gears.
3. The gear pump of claim 2 wherein said drive shaft is provided with transverse keyways and wherein said key means comprises an elongated key member extending through one of said keyways into each pair of recesses.
4. The gear pump of claim 3 wherein said keyways extend diametrically through said shaft.
References Cited in the file of this patent UNITED STATES PATENTS 1,541,435 Reller June 9, 1925 1,640,727 Scott Aug. 30, 1927 1,663,253 Hillborn Mar. 20, 1928 2,909,137 Kleckner July 23, 1935 2,541,405 Chapman Feb. 13, 1951