US2578780A - Rotary pump seal - Google Patents

Description

Dec. 18, 1951 c. D. BOWER 2,578,780

ROTARY PUMP SEAL Filed Sept. 20, 1946 I j 37 34 35 E Ill I a Z I I2 4 III INVENTOR.

CLARK D.- BOWER.

ATTORNEY.

Patented Dec. 18, 1951 OFFICE ROTARY PUMP SEAL Clark D. Bower, Pomona, Caliil, assignor to Fairbanks, Morse & Co., Chicago, Ill., a corporation of Illinois Application September 20, 1946, Serial No. 698,228

4 Claims.

This invention relates to tnprovements in rotary pumps of the turbine type, and more particularly to the provision in a pump of this character, of improved means for sealin the fluid pumping channel and pump stator surfaces relative to the rotary impeller in the zone between the pump inlet and discharge ports, the sealing means as herein provided affording reduction to a negligible minimum or substantial avoidance of fluid leakage and by-pass in such zone, to the end of enhancing the efficiency of the pump.

The principal object of the present invention is to provide in a pump of the character indicated, improved partition means disposed in the zone of the pumping channel between the pump inlet and outlet, serving to prevent leakage or fluid bypass from the pump discharge side to the inlet, and to assure effective fluid diversion to pump discharge, the presently improved partition means being of a character to afford further, an effective seal not only in respect to the impeller buckets and the impeller periphery, but as to the clearance spaces between the impeller and adjacent casing surfaces in the zone radially inwardly of the pumping channel, whereby to prevent fluid by-pass or leakage in such zone.

Another object is to afford a sealing partition as above indicated, which is fully adjustable in a manner permitting initial setting thereof for effecting the desired degree of seal, and thereafter permitting further adjustments of the partition as wear may occur between the partition and rotor, thus facilitating maintenance of an effective seal at all times.

A further object is to provide a sealing partition as hereinabove indicated, which is characterized in whole or at least as to the effective sealing surfaces thereof, by a material such as a suitable plastic, which will avoid undue wear of the pump impeller due to impeller engagement with the sealing means.

Further objects and advantages of the present improvements will appear from the following description of the invention as such is illustrated in the accompanying drawing wherein:

Fig. 1 is a longitudinal vertical section of a turbine pump showing the present improvements embodied therein;

Fig. 2 is a transverse section of the pump as taken along line 2-2 of Fig. 1;

Fig. 3 is a fragmentary sectional view in the zone of impeller seal between the pump inlet and discharge, illustrating a modification in the adjustment provision for the sealing partition, and

Fig. 4 is a fragmentary view transversely of the pump, as taken from line 4-4 in Fig. 3.

2 Referring now to the several figures of the drawing and first to Figs. 1 and 2, there is illustrated a rotary pump of turbine type indicated generally at l0, which comprises connected frame sections H and 12 providing a central chamber M to accommodate the impeller and stator elements presently to be described, and affording at the outer ends thereof bearing supports for bearings l5 supporting a pump shaft I6. Also carried by the frame sections II and I2 in coaction with the shaft it, are shaft sealing glands l8 for preventing fiuid leakage from chamber l4 outwardly along the shaft.

As appears in Fig. 2 the frame section II affords a fluid inlet connection [9 and an adjacent oppositely directed discharge connection 20, each communicating with an annular pumping channel 22, the channel 22 being formed according to the present example, by complementary pump casing elements or liners 23 arranged in the chamber M. The liners 23 in assembly embrace the pump rotor or impeller member 24 which is suitably keyed or otherwise secured on shaft l6. Each liner 23 provides an annular land or rib 2G in running clearance with the face portion 21 of the impeller radially inwardly of the impeller buckets 28, and a peripheral land or rib 30 radially beyond the impeller periphery, the latter rib being interrupted at the inlet and discharge connections to the channel 22.

Each of the liners 23 in the zone thereof between the pump inlet I 9 and discharge 20, is formed to provide a recess 32 extending by preference radially inwardly from the outer end of the liner to the inner periphery 33 thereof. In the assembly of the liners, the recesses 32 are in longitudinal alignment and afford mountin space for the presently improved impeller sealing partition as shown in Fig. 1. Although the seal may be a unitary or one-piece structure, by present preference it is comprised of a pair of plug elements 34, which in assembly in the recesses 32 coact to embrace the periphery and opposite sides of the impeller in the bucket zone thereof, as well as the sides 21 of the impeller radially inwardly of the bucket zone. In embracing the sides 21 of the impeller, the plug elements extend across or transversely of the casing ribs 25, thereby affording a leakage seal at the ribs. It will be observed from Fig. 1, that in transverse section, the impeller in the bucket zone and over the faces 21 thereof, is bevelled convergently toward the impeller periphery, and further, the opposed coopcratin face portions of the plugs 34 are relatively inclined to closely accommodate the bevelled surfaces of the impeller. Consequently, by radial inward displacement of the plug elements as a unit, a closer sealing relation may be obtained between the impeller and plugs. Accordingly, in order to afford such displacement of the plugs and as a means for retaining the plugs in operatlve position, the present provisions include a plug positioning and adjusting screw 36 carried by a plate or bridge piece 31 suitably secured to the casing II, the screw 36 at its inner end abutting a plate element 38 engaging the outer ends of the plugs 34. To prevent leakage past the adjusting screw 36 to the pump exterior, a suitable sealing cap 39 may be secured in a readily removable manner to the plate 31 over screw 36, as by threading to the plate boss shown. Further, it is to be noted that the annular lands 26 of the liners are bevelled correspondingly to the bevel of the impeller faces 21, to effect the desired running clearance with respect to the impeller.

From the foregoing it will be now appreciated that by the present provisions affording the sealing elements 34 in operative relation to the impeller as shown, that the impeller in the zone of the buckets 28 thereof, is effectively sealed against fluid leakage or by-pass, while the impeller and the liner ribs 25 and 30 in the region of the plugs are effectively sealed against fluid leakage. Further and importantly to the present invention, the cooperating bevelled sealing surfaces of the plugs and impeller and the provision for radial adjustment of the plugs, permit plug takeup in the event of wear, whereby an effective seal both peripherally and laterally of the im peller buckets, as well as at the liner ribs 26, may be maintained at all times.

In order to reduce frictional wear of the impeller by the partition elements or plugs 34, the present improvements further contemplate the provision of plugs having the operative faces thereof (with respect to the impeller) formed of a suitable plastic material, or the entire plug may be formed of plastic material or other material characterized by a minimum wear effect upon the impeller. As against the metal surfaces of the pump impeller, it will be thus appreciated that the plug wear of these surfaces will be thereby considerably reduced. One example of a plastic material suitable for the present purposes may be a phenolic resin of the thermosetting type.

Figs. 3 and 4 illustrate a provision for securing adjustments or wear takeup of the sealing plugs laterally with respect to the impeller. This is accomplished, after disassembly of the pump frame parts, preferably by one or more shims 40 inserted in the plug-receiving recess 32 of liner 44 behind the plug as shown in Fig. 3. Such lateral adjustment may be applied to either or both of the cooperating seal plugs as wear conditions may dictate, it being noted that while Fig'. 3 shows only one of the plugs with a shim or shims 4!! behind it, the same arrangement will apply equally to the other plug in its recess not here illustrated. Further with reference to the embodiment of the pump seal according to Figs. 3 and 4, each seal plug 4| may be formed of plastic or bronze and is provided as a replaceable element, to be inserted in a milled groove 42 in the liner 44. In assembly, the plug is retained against displacement radially of the liner by engagement of its upper or outer ends 46 by the overlying portion 41 of the pump stator frame. As wear may occur in pump operation, the close running seal effected by the plug with respect to the rotor buckets 48 and rotor side face 50 inwardly of the buckets, may be maintained by replacing the shim 40 with another of greater thickness, or by applying additional shims of equal thickness.

A further feature of the present improvements concerns the facility of formation and reduction of manufacturing cost of the liners 23. By reasons of the improved character of impeller and channel seal constructionherein provided, it will be observed that each of the liners 23 may be formed with the bucket channel-half completely annular, following which the radial slot or recess 32 may be provided by a simple milling operation.

Having now illustrated and described the present improvements, what I desire to secure by Letters Patent is:

1. In a rotary pump, a casing structure including casing portions having cooperating inner and outer annular lands serving to define therebetween an annular pressure developing channel, said casing structure having an inlet and an outlet each open to said channel, and providing recesses in the casing portions, extending radially thereof in the zone of the casing structure between said inlet and outlet, a rotor having marginal brackets operative in said channel and opposite side faces in close running clearance with the inner lands of said casing portions, and a fluid leakage and by-pass stop comprising partition means received in said recesses in the casing portions and extending radially 0f the pump across said inner and outer lands and the channel, and closely embracing the rotor periphery, the sides of the buckets and said rotor side faces.

2. In a rotary pump, a casing structure including casing portions having cooperating inner and outer annular lands serving to define therebetween an annular pressure developing channel, said casing structure having an inlet and an outlet each open to said channel, and providing recesses in the casing portions, extending radially thereof in the zone of the casing structure between said inlet and outlet, a rotor having marginal buckets operative in said channel and opposite side faces in close running clearance with the inner lands of said casing portions, the opposite sides of the buckets and said side faces being bevelled convergently toward the rotor periphery, a fluid leakage and by-pass stop comprising partition means received in said recesses in the casing portions and extending radially of the pump across said inner and outer lands and the channel, said partition means providing inclined surfaces closely embracing the rotor periphery and said bevelled sides of the buckets and I rotor side faces, and means accessible from the exterior of the casing portions for adjusting said partition means radially of the rotor.

3. In a rotary pump, a casing providing casing sections formed and adapted for cooperation to define an annular pressure developing passage therein, and having relatively adjacent fluid inlet and outlet means open to the passage, said casing sections having opposed recesses in the portion thereof between said fluid inlet and outlet means, extending radially of the casing across said passage, a metallic rotor having marginal buckets operative in said passage and opposite side faces inwardly of the buckets, and a stop comprising partition means received in said recesses and c0 operating with the passage, the rotor buckets and said rotor side faces to prevent fluid by-pass from the outlet to the inlet, said partition means being formed at least in the portions thereof opposed to the rotor buckets and rotor side faces,

of a material characterized by a minimum frictional wear effect upon the metallic rotor.

4. In a rotary pump, a casing providing casing sections cooperating to define an annular pressure developing passage therein, and having relatively adjacent inlet and outlet means each open to said passage, said casing sections having opposed recesses in the portions thereof between said fluid inlet and outlet means, extending radially of the casing across said passage, a metallic rotor having marginal buckets operative in said passage and opposite side faces inwardly of the buckets, a stop for preventing fluid by-pass relative to the passage and rotor between the outlet and inlet, said stop comprising complemental plug elements received in said recesses and radially adiustable therein, extending across said passage and embracing the rotor periphery and rotor buckets, said plug elements extending radially inwardly of said casing passage in relatively close embracing relation to said rotor side faces, and

further, said elements each being formed of a plastic material characterized by a minimum frictional wear eifect upon the metallic rotor, and means for effecting radial adjustments of said stop.

CLARK D. BOWER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,418,041 Trane May 30, 1922 1,678,977 Finn July 31, 1928 2,245,094 Neibert June 10, 1941 2,420,556 Mueller May 13, 19M

FOREIGN PATENTS Number Country Date 28,367 Great Britain 1902

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