US3779667A

US3779667A - Semi-seal device

Info

Publication number: US3779667A
Application number: US00228945A
Authority: US
Inventors: C Johnson
Original assignee: BAKER HYDRO Inc
Current assignee: BAKER-HYDRO INCORPORATED A CORP OF
Priority date: 1972-02-24
Filing date: 1972-02-24
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18

Abstract

A semi-seal device for controlling the flow of water along a rotating shaft, which device is annular and contained in a retainer disposed around the shaft. The containment is loose so that the semi-sealing member may move laterally in its retainer thus temporarily increasing the clearance between the semisealing member and the rotating shaft. In addition, the semisealing member is deformable and resilient. The lateral movement and deformation properties allow sand or other foreign particles to pass between the semi-sealing member and rotating shaft.

Description

United States Patent 1191 Johnson SEMI-SEAL DEVICE [75] Inventor: Charles S. Johnson, Laguna Niguel,

Calif.

[73] Assignee: Baker Hydro, Inc., Santa Ana, Calif.

[22] Filed: Feb. 24, 1972 [21] Appl. No.: 228,945

[52] US. Cl 415/170 A, 415/211, 277/163 [51] Int. Cl. F04d 29/08, F04d 29/44 [58] Field of Search 415/110, 111, 112, 415/170 A, 175, 134; 277/163, 173, 174, 177

[56] References Cited UNITED STATES PATENTS 3,707,335 12/1972 Barnard 415/170 A 1,715,944 6/1929 Oliver 2,034,790 3/1936 Arutunoff 415/134 FOREIGN PATENTS OR APPLlCATlONS 819,082 8/1959 Great Britain 277/163 1 Dec. 18, 1973 302,991 1/1918 Germany 415/170 A Primary Examinerl-lenry F. Raduazo Attorney-Allan R. Fowler et al.

[57] ABSTRACT A semi-seal device for controlling the flow of water along a rotating shaft, which device is annular and contained in a retainer disposed around the shaft. The containment is loose so that the semi-sealing member may move laterally in its retainer thus temporarily increasing the clearance between the semi-sealing member and the rotating shaft. In addition, the semi-sealing member is deformable and resilient. The lateral movement and deformation properties allow sand or other foreign particles to pass between the semi-sealing member and rotating shaft.

8 Claims, 3 Drawing Figures SEMI-SEAL DEVICE INTRODUCTION This invention relates to centrifugal water pumps and in particular to a means for protecting the impellor hub and pump housing against damage from foreign particles.

A centrifugal water pump includes a rotating impellor which is driven by an external power source and which functions to direct a stream of water through its outlet by creating a centrifugal force. The centrifugal force operating on the water in the impellor forces the water out the impellor exit thereby creating a suction at the impellor entrance. This suction then acts to bring water into the impellor thus completing the pumping action.

The impellor is circular and rotates within a fixed housing which functions to collect the water expelled from the impellor. In certain applications, the clearance between the impellor and the housing is such that some of the water expelled from the impellor recircu lates around the exterior of the impellor. That water which circulates on one side of the impellor, for example, may be used to cool the impellor hub ahd then allowed to re-enter the mainstream of water within the impellor. That water which circulates on the other side of the impellor, for example, may flow by the base of the impellor, the impellor hub, and into the body of water from which the pump draws.

The water which circulates around the impellor must pass through close tolerance areas. A small tolerance tends to create a high efficiency pump and as such is desirable. Pump efficiency is related to these tolerances because as the tolerances are increased, the nonproductive flow of water through these areas is increased thereby decreasing the volume per unit time output of the pump with no associated decrease in input power requirements.

However, a problem arises because the close tolerances often do not allow for the passage of foreign particles and thus they may become embedded in the pump housing or impellor hub thereby causing raceways to be formed and generating excessive noise. The raceways may lead to a weakening of the impellor hub and thence to possible pump failure.

Heretofore, a pump designer has been faced with the unpleasant trade off of minimizing impellor hub and pump housing damage at the expense of pump efficiency or maximizing pump efficiency at the expense of possible impellor hub and pump housing damage from foreign particles. The present invention allows the pump designer to maintain a sufficiently large pump housing to impellor hub tolerance while controlling pump efficiency. In general, this goal is accomplished by interposing a flexible, movable gasket, axially aligned with the impellor hub, which effectively restricts and controls the bypass water flow while allowing foreign particles to pass without incident.

The invention is most applicable to pumps having a plastic impellor hub and/or plastic housing but will serve the same function and eliminate the same, though not as severe, problems in metal housing and/or metal impellor pumps.

DRAWINGS FIG. 1 is a diametrical vertical section of a centrifugal pump, showing the semi-seal in place;

FIG. 2 is an enlarged partial vertical section of the semi-seal of FIG. 1 showing the semi-seal and its housing in relation to the centrifugal pump impellor hub and pump housing; and

FIG. 3 is an exploded perspective view of the semiseal assembly.

The preferred embodiment of the invention will be described in the context of a centrifugal water pump which is oriented to have its impellor hubs axis of rotation in the vertical position.

The present invention can best be understood by referring to FIG. l which shows the source of water to be pumped 10, The pump impellor 12, the interior 14 of the pump impellor, the upper impellor hub 25, the lower impellor hub 27, and the output water collector box 16. The pump impellor 12 is driven by a motor 18 through a rotating shaft 20 around which is disposed a water-tight seal 22. The heat of friction generated by the shaft 20 rotating within the water-tight seal 22 is dissipated through the heat exchange chamber 24. The outside wall of the heat exchange chamber 24 is formed by the upper impellor hub 25 and the lowermost portion of the heat exchange chamber 24 contains outlets 30 connecting it to the interior of the impellor 14.

The first annular semi-seal or wear ring assembly 32 is attached to the lower portion of a pump housing structural member 52 located immediately adjacent the upper hub impellor 25. The second annular semi-seal assembly 32 is attached to a pump housing structural member 54 located adjacent to the lower impellor hub 27. Both semi-seal assemblies are positioned around the impellor hub.

The semi-seal assembly 32, or wear ring, can best be understood by referring to FIG. 3 which shows the ring shaped semi-sealing member 34, an upper retaining member 42, and a lower retaining member 44. These retaining members, when assembled, contain the semisealing member 34 in a sandwich configuration. Each retaining member has a recessed area 46 such that when the two retaining members are in an assembled configuration the semi-sealing member 34 fits loosely in the recessed area. The recessed area is formed by an annular shoulder 47 located at the outer periphery of each of the retaining

members

42 and 44. Located on this shoulder 47 are pins 48 and holes suitable for aligning the two retaining members in an assembled configuration.

The diametric distance between the interior walls of the recess shoulders 47 is greater than the outside diameter D of the semi-sealing member 34. The height of the recess shoulder is greater than one half the thickness of the semi-sealing member 34. Thus the semisealing member 34 is loosely contained by the upper 42 and lower 44 retaining members in assembled configuration.

In FIG. 2, an enlarged view shows the semi-seal assembly 32 attached to the upper, structure member 52 and adjacent to-the upper impellor hub 25. The semisealing member 34 is loosely encased by the upper retaining member 42 and the lower retaining member 44. To the right of the semi-sealing member 34 is located the recess shoulders 47 and the alignment pin 48 and hole 50 in assembled configuration,

Most centrifugal pumps are designed with a clearance between the edge of the pump impellor l3 and the edge of the pump housing 15 so that the impellor may rotate freely within its housing. Normally the clearance is such that some water leaving the impellor recirculates through the areas above 26 and below 28 the impellor. That water recirculating above 26 the impellor passes through the heat exchange chamber 24 and then re-enters the interior of the impellor 14 via inlets 30 in its wall.

In order for this reciruclating water to flow from the area above 26 the impellor into the heat exchange chamber, it must pass between the upper impellor hub 25 and the semi-sealing member 34, as shown in FIG. 2. Similarly, in order for the recirculating water to flow from the lower 28 chamber into the impellor intake 14 it must pass between the lower impellor hub 27 and its associated semi-sealing member 34.

Any foreign matter, such as sand, in the water may eventually enter the impellor l4 and from there enter the upper 26 and lower 28 recirculation areas. When this occurs, the foreign matter must pass through the narrow strait 56 between the upper impellor hub 25 and the semi-sealing member 34. In order to facilitate passage of the forcing matter, clearances must be kept at an adequate size but at the same time, if clearances are excessive, too much water will recirculate thus lowering the pumps efficiency. The present invention solves the above problem by allowing the pump designer to enlarge the recirculation pathway while at the same time controlling the flow of recirculating water.

The operation of the semi-seal can be best understood by referring to FIG. 2. The recirculating water and associated foreign matter flow between the semisealing member 34 and the impellor hub 25. In normal operation each semi-sealing member centers itself around its related hub because of the centrigugal force of the rotating hub and surrounding water. The distance 56 between the semi-sealing member 34 and the impellor hub 25 is designed so as to adequately control this flow and may vary from pump to pump. The smaller the clearance the less the flow.

Any foreign matter entering the strait 56 between the impellor hub 25 and the structural member 52 must pass through without becoming lodged in this passage way. The narrowest portion of the passage way occurs at the sealing member 34. As a sand particle, for example, begins to be lodged between the semi-sealing member 34 and the hub, the particle is pushed against the semi-sealing member by the rotating hub. This causes the semi-sealing member 34 to move laterally in its

retainer

42 and 44 away from the particle so that the semi-sealing member is eccentric to the hub and the clearance 56 adjacent the particle increases. Further, the edge of the semi-sealing member exposed to the flow of water tends to be deformed by the particle. Both of these reactions cooperate to allow the passage of the sand particle with no damage to any adjacent part of the pump. Upon passage of the same particle, the resilient sealing member 34 assumes its former shape and position in its

housing

42 and 44. It is this combination of the deformation and lateral movement of the sealing member which allows the safe passage of the sand particle.

I claim:

1. A centrifugal water pump including a semi-seal comprising:

a housing;

a pump impellor mounted for rotation within said housing and having a circular hub thereon;

a chamber defined between said impellor and said housing and in fluid communication with the interior of said impellor through the intake and discharge of the impellor;

an annular semi-sealing member having a slightly large interior diameter than the exterior diameter of said hub and disposed in said chamber in closelyspaced position around said hub for allowing limited flow of water through said chamber through the space defined between inner diameter of the annular semi-sealing member and the hub;

said pump impellor creating a pressure differential in said chamber between opposite axial sides of said semi-sealing member; and

retaining means on said housing having a recess therein with walls retaining said semi-sealing member in its axial position relative to said hub, said recess being of greater axial length than the axial thickness of said semi-sealing member and of an outer diameter greater than the outer diameter of said semi-sealing member for permitting said semisealing member to move laterally relative to said hub to an eccentric position therewith to permit particles in said water larger in dimension than the difference in radius between the exterior of said hub and the interior of said semi-sealing member to pass between the semi-sealing member and the hub in response to the differential pressure between the intake and discharge of the impellor.

2. A centrifugal water pump including a semi-seal as defined in claim 1 and further comprising a second one of said chambers, said semi-sealing members, and said retaining means disposed on the opposite side of said impellor.

3. A centrifugal water pump including a semi-seal as defined in claim 2 in which the axis of rotation is substantially vertical, the first chamber is above the impellor, and the second chamber is below the impellor.

4. A centrifugal water pump including a semi-seal as defined in claim 1 wherein the water flowing through the chamber is used to cool the impellor shaft.

5. A centrifugal water pump including a semi-seal as defined in claim 1 wherein:

said housing includes an assembly disposed around said hub in spaced relation thereto and having a first member and a second member in juxtaposed relation forming an annular recess for receipt of said semi-sealing member; and

said retaining means is mounted on said housing assembly.

6. A centrifugal water pump including a semi-seal as defined in claim 1 wherein said retaining means comprises:

first and second annular members removably connected together, one of said annular members having a retaining shoulder forming a recess in said connection between said first and second annular members, said recess containing the semi-sealing member, the largest diameter of said recess being substantially greater than the largest diameter of said semi-sealing member, and the height of said recess being slightly greater than the height of said semi-sealing member.

7. A centrifugal water pump including a semi-seal as defined in claim 6 and further comprising:

pins on one of said annular retaining means members and holes in the other of said annular retaining is a resilient ring adapted to be deformed by the passing of the particles to promote movement of said semisealing member to said eccentric position.

Claims

1. A centrifugal water pump including a semi-seal comprising: a housing; a pump impellor mounted for rotation within said housing and having a circular hub thereon; a chamber defined between said impellor and said housing and in fluid communication with the interior of said impellor through the intake and discharge of the impellor; an annular semi-sealing member having a slightly large interior diameter than the exterior diameter of said hub and disposed in said chamber in closely-spaced position around said hub for allowing limited flow of water through said chamber through the space defined between inner diameter of the annular semisealing member and the hub; said pump impellor creating a pressure differential in said chamber between opposite axial sides of said semi-sealing member; and retaining means on said housing having a recess therein with walls retaining said semi-sealing member in its axial position relative to said hub, said recess being of greater axial length than the axial thickness of said semi-sealing member and of an outer diameter greater than the outer diameter of said semisealing member for permitting said semi-sealing member to move laterally relative to said hub to an eccentric position therewith to permit paRticles in said water larger in dimension than the difference in radius between the exterior of said hub and the interior of said semi-sealing member to pass between the semi-sealing member and the hub in response to the differential pressure between the intake and discharge of the impellor.

5. A centrifugal water pump including a semi-seal as defined in claim 1 wherein: said housing includes an assembly disposed around said hub in spaced relation thereto and having a first member and a second member in juxtaposed relation forming an annular recess for receipt of said semi-sealing member; and said retaining means is mounted on said housing assembly.

6. A centrifugal water pump including a semi-seal as defined in claim 1 wherein said retaining means comprises: first and second annular members removably connected together, one of said annular members having a retaining shoulder forming a recess in said connection between said first and second annular members, said recess containing the semi-sealing member, the largest diameter of said recess being substantially greater than the largest diameter of said semi-sealing member, and the height of said recess being slightly greater than the height of said semi-sealing member.

7. A centrifugal water pump including a semi-seal as defined in claim 6 and further comprising: pins on one of said annular retaining means members and holes in the other of said annular retaining means members for aligning the two retaining members.

8. A centrifugal water pump including a semi-seal as defined in claim 1, wherein said semi-sealing member is a resilient ring adapted to be deformed by the passing of the particles to promote movement of said semi-sealing member to said eccentric position.