US3381620A - Means to achieve close clearance between stationary and moving members - Google Patents

Description

May 7, 1968 o. s. CUSHING ETAL 3,331,520

MEANS TO ACHIEVE CLOSE CLEARANCE BETWEEN STATIONARY AND MOVING MEMBERS Filed Nov. 30, 1965 INVENTORS DONALD s. cusmwe BY$THOMAS E. TENKiNS F THEIR ATTORNEY United States Patent MEANS TO ACHIEVE CLOSE CLEARANCE BETWEEN fiTATlONARY AND MOVlNG MEMBERS Donald S. Cashing and Thomas E. Jenkins, Louisville,

Ky., assignors to General Electric Company, a corporation of New York Filed Nov. 30, 1965, Ser. No. 510,505 16 (Ilaims. (Cl. 103-111) ABSTRACT OF THE DISCLOSURE Means to achieve close clearance between stationary and moving members wherein one of the members is malleable. The malleable member will deform to the extent of any interference upon initial movement of the moving member. The deformed member will remain deformed, due to its malleable nature, and thus provide the closest possible clearance without actual interference be tween the stationary and moving members.

This invention relates to means to achieve close clearance between stationary and moving members.

It is often necessary to provide a reasonably effective seal between a stationary member and a moving member while at the same time avoiding frictional forces therebetween which would impede movement of the movable member or would create excessive heat generation and wear of the adjacent members. One example of such a necessity is a pump having a stationary housing with a moving impeller disposed therein to impel fluids through the housing. It is often necessary, in order to enhance the efficiency of the pump, to seal off the high pressure side of the impeller from the low pressure side to prevent fluid from flowing counter to the main stream of fluid flow in the area between the impeller and pump housing. In the past, various means have been proposed to provide such a seal; however, each in its own way presented an additional problem which tended to compromise the advantageous aspects of the resulting seal. For example, a standard means included lubricated contiguous stationary and moving parts which required lubrication means and were subject to wear and frictional drag. Another means heretofore proposed was that of initially providing a tight fit between the stationary and moving members with one member being designed to abrade the other member until attrition of the latter finally resulted in a close clearance between the two members, however,

- this type arrangement created particles of material, due

to the abrasive action, which have found their way into shaft bearings or the like to create obvious problems. It is also necessary with this latter arrangement to provide the abrading part with an abrasive surface and sufficient hardness, which may require undesirably expensive material, to assure suitable abrasive action. The present invention contemplates a means which will provide a suitably close clearance, and a resulting seal between moving and stationary members, without the problems attendant with the aforementioned prior art arrangements.

Accordingly, it is an object of this invention to provide an improved means to achieve close clearance between stationary and moving members.

It is a further object of this invention to provide means of the nature described which will function properly despite initial misalignment between the moving and stationary members.

It is also an object of this invention to provide means which will achieve a suitably close clearance between a stationary member and a rotary member despite initial asymmetry of the rotating member or initial asymmetry between the rotating member and the stationary member.

In accordance with one aspect of the present invention, there is provided, in combination, a first member and a second member adjacent the first member. One of the members is movable with respect to the other of the members. One of the members is malleable whereby the member being malleable will deform to provide a close clearance between the two members upon initial movement of the one of the members which is movable.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed the invention will be better understood from the following description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a side .elevational view, partly cut away to show details, of a motor-pump assembly employing the present invention;

FIGURE 2 is an enlarged fragmentary sectional view of the pump of the assembly of FIGURE 1; and

FIGURE 3 is an exploded fragmentary perspective view of some of the elements of FIGURE 2.

Referring now to the drawing, there is shown a motorpump assembly 10 including an electric motor 11 and a pump 12. A shaft 13 extends from motor 11 into pump 12. An impeller 14 is carried by shaft 13 for rotary movement therewith. Pump 12 has a stationary housing 15 within which impeller 14 rotates. Housing 15 is secured to a casing 16 of motor 11 by such suitable means as, for example, a plurality of bolts 17.

Housing 15 includes an enlarged portion 18 which serves as a scroll and has an outlet 19 through which fluids are pumped by impeller 14. Outlet 19 may be connected with any suitable conduit or receptacle to receive the fluid from housing 15.

The inlet to pump 12 may be provided with a conduit 20 secured to housing 15 by means a circular band 21 which clamps conduit 26 to housing 15. It may be desirable, in some applications of a pump such as that illustrated in the drawing, to employ a grid-like element 22 to prevent articles which may damage impelled 14 from passing through the inlet to the pump.

With the foregoing arrangement, upon energization of motor 11, impeller 14 rotates to draw fluid from conduit 20 through grid-like element 22 and into enlarged portion 18 of housing 15. Of course, the fluid contained within enlarged portion 18 is of substantially higher pressure than the fluid in conduit 2%) and this pressure is such as to force the fluid out through outlet 19.

With the impeller 14 creating a high pressure as just described, the fluid attempts to seek its way around the periphery of the impeller 14 to the low pressure, or upstream, side of impeller 14. Means must be provided to minimize or prevent such escape of fluid since such escape will inherently decrease the efficiency of the pump and, in some instances, will create such a turbulence at the pump inlet as to starve the impeller and make it ineffective in pumping fluid. As discussed above, various means have been proposed heretofore to provide a seal to minimize the escape of fluid; however, these have created attendant disadvantages which compromised their desirability.

In accordance with the present invention, an annular malleable member 23 is supported from housing 15 and is adapted to cooperate with imepller 14 to achieve a close clearance between the member 23 and impeller 14 to provide ,a seal which minimizes escape of high pressure fluid back toward the inlet of pump 12. Member 23 is supported from housing 15 by means of a ring 24 which seats against an annular surface on housing 15 and by means of a threaded member 25 which has screw threads 26 adapted to cooperate with threads formed in housing 15 whereby member 25 may be screwed into housing 15 to clamp member 23 against ring 24. Member 25 is provided with a plurality of angularly spaced brackets 27 which may be formed integrally with member 25 and which support grid-like element 22. If desired, grid-like element 22 may also be formed integrally with brackets 27 and member 25. Bracket 27 has a projection 28 which bears against member 23, as shown in FIGURE 2, to increase the rigidity of member 23 and overcome any tendency of member 23 to bend away from impeller 14 under the influence of the pressure differential on opposite sides of member 23.

The distal end of member 23 has a radially outward projecting portion 29 which is adapted to cooperate with a generally cylindrical sealing surface 30 on impeller 14. As will become evident, it is not necessary that surface 30 be cylindrical. It may, for example, be conical or spherical. Ideally, surface 35) will be symmetrical about shaft 13; however, it is an object of this invention to compensate for any asymmetry or eccentricity of surface 3% with re spect to shaft 13, as will be explained in greater detail hereinafter. Also ideally, housing 15, where it circumscribes impeller 14, and threaded member 25 will be concentric with shaft 13 and impeller 14; however, due to the accumulation of manufacturing tolerances, it is not unlikely that these elements will have a slightly eccentric relationship and it is a further object of this invention to compensate for this eccentricity. As best seen in FIGURE 2, the outside diameter of member 23 is less than the inside diameter of housing 15 at the point where member 23 is positioned. Because of this difference in size, when member 23 is assembled into housing 15 and impeller 14, it will align itself with sealing surface 36 and any eccentricity between surface 39 and housing 15 will not create an interference between the periphery of member 23 and the inner surface of housing 15. It will be further noted that ring 24 and threaded member 25 have sufficient radial dimension to securely clamp the member 23 even though member 23 may be asymmetrical with housing 15.

Accumulation of manufacturing tolerances may also result in a variance of the axial relationshipbetween impeller 1 and housing 15 which in turn would create a variance in the axial relationship between impeller 14 and member 23. This variance is compensated by providing sealing surface 30 with a substantial axial dimension so that cooperation between portion 29 of member 23 and surface 30 will be achieved despite the aforementioned variance.

As stated earlier, member 23 is malleable and, in the preferred embodiment of the present invention, is formed from a material comprising, by weight, 95% tin and antimony. The use of a noble metal such as tin avoids any corrosion problems without necessitating a protective coating and, at the same time, provides the desirable malleability. Although it is not necessary to use a material which is dead soft, the aforementioned composition provides a material which is practically dead soft.

Preferably, the diameter of portion 29 is initially sufficiently large so that a reasonably snug fit with sealing surface 3d is provided as member 23 is assembled into impeller 14. After threaded member 25 is threaded into housing 15 to clamp member 23 securely, initial rotary movement of the impeller 14 will deform member 23 to the extent necessary to overcome any eccentiricity between sealing surface 30 of impeller 14 and portion 29 of member 23. Once this deformation has occurred, there will exist between member 23 and impeller 14 the closest clearance possible in view of the attendant eccentricity of surface 39 of impeller 14. This close clearance provides a seal between the two parts to minimize escape of fluid from the high pressure side of impeller 14 to the low pressure side.

It should be noted that with the configuration illustrated in FIGURE 2, i.e., with member 23 having a generally L-shaped cross section with the free end of one leg of the L pointing along the direction of flow of the fiuid passing through the pump, any leakage of fluid from the high pressure side of the impeller to the lower pressure side will be directed in line with the flow of fiuid through the impeller. In other words, any leakage of fluid will be redirected toward the impeller thereby minimizing the creation of turbulence at the impeller inlet which might otherwise result. Moreover, the L-shaped cross section of member 23 provides a reasonably streamline inlet at the impeller so that member 23 serves not only as a sealing means but as an inlet conditioner for fluid entering impeller 14.

The use of a malleable material for member 23 provides an additional advantage. If it is necessary to disassemble the pump 12 for servicing, upon reassembly the Serviceman may manually bend portion 29 of member 23 radially outward to re-establish the snug fit between surface 30 and impeller 14 so that initial rotary movement of the impeller 14 after reassembly will re-establish the close clearance between member 23 and surface 30.

It has been found from practice that with an impeller, such as impeller 14, molded from a glass-filled polypropylene and a malleable member, such as member 23, formed from a composition comprising tin and 5% antimony, with the metal forming member 23 having a thickness of .018 inch, the invention will perform suitably. Thus it can be seen that the present invention provides an improved means for achieving a close clearance between a moving member and a stationary member.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of construction of the example illustrated, and it is contemplated that various modifications or applications will occur to those skilled in the art. It is there fore intended that the appended claims shall cover such modifications or applications as do not depart from the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In combination:

(a) a first member,

(b) a second member adjacent said first member,

(0) one of said members being rotatable with respect to the other of said members about an axis of rotation,

((1) stationary means supporting the other of said members for radial movement relative to said axis of rotation, and

(e) means for detachably securing said other of said members to said stationary means,

(f) one of said members being malleable whereby said member being malleable will deform to provide a close clearance between said members upon initial rotation of the one of said members being rotatable.

2. The combination of claim 1 wherein said first member is the one of said members being rotatable.

3. The combination of claim 2 wherein said first member is a pump impeller and said second member forms a seal therewith between the high pressure side and the low pressure side of said pump impeller.

4. The combination of claim 3 wherein said pump impeller has a sealing surface of elongated dimension in the direction of said axis.

5. A pump comprising:

(a) a stationary housing,

(b) a rotatable impeller disposed within said housing to impel a fluid through said housing,

(c) a sealing surface on said impeller substantially symmetrical about the axis of rotation of said impeller,

(d) an annular member having a portion adapted to cooperate with said sealing surface to provide a seal between the high and low pressure sides of said impeller, and

(e) means for detachably securing said annular member to said housing and providing a space adjacent the outer periphery of said annular member to allow said annular member to move radially relative to said axis of rotation during assembly of said annular member to said housing whereby said portion of said annular member may substantially align itself with said sealing surface.

6. A pump comprising:

(a) a stationary housing,

(b) a rotatable impeller disposed within said housing to impel a fluid through said housing,

(c) a sealing surface on said impeller substantially symmetrical about the axis of rotation of said impeller,

(d) an annular member having a portion adapted to cooperate with said sealing surface to provide a seal between the high and low pressure sides of said impeller, and

(e) means for detachably securing said annular member to said housing and providing a space adjacent the outer periphery of said annular member to allow said annular member to move radially relative to said axis of rotation during assembly of said annular member to said housing whereby said portion of said annular member may substantially align itself with said sealing surface,

(f) said annular member being formed from a malleable metal whereby at least said portion will be deformed upon initial rotation of said impeller to the extent that said sealing surface is eccentric to the axis of rotation of said impeller.

7. A pump comprising:

(a) a stationary housing,

(b) a rotatable impeller disposed within said housing to impel a fluid through said housing, and

(c) a stationary annular member supported by said housing,

(d) said annular member having a generally L-shaped cross-section with first and second legs,

(c) said first leg being secured to said housing and said second leg being adjacent said impeller,

(f) said impeller having a portion thereof positioned radially outward of said second leg,

(g) said portion of said impeller and said first leg forming a seal between the high pressure side of said impeller and the low pressure side,

(h) said annular member being malleable whereby it will deform to provide a close clearance between said annular member and said impeller upon initial rotation of said impeller.

8. The invention of claim 7 wherein said annular member has the free end of said second leg pointing along the direction of flow of the fluid whereby any leakage of fluid from the high pressure side of said impeller to the lower pressure side will be directed in line with the flow of fluid through said impeller.

9. A pump comprising:

(a) a stationary housing,

(b) an impeller rotatable about an axis and disposed within said housing to impel a fluid through said housing,

(c) a stationary annular member supported by said housing,

(d) said annular member having a generally L-shaped cross section with first and second legs,

(e) said first leg being secured to said housing and said second leg being adjacent said impeller,

(f) said impeller having a sealing surface positioned radially outward of said second leg,

(g) said sealing surface having an elongated dimension in the direction of said axis to compensate for axial misalignment of said impeller and said annular member,

(h) said sealing surface and said first leg forming a seal between the high pressure side of said impeller and the low pressure side,

(i) said annular member being malleable whereby it will deform to provide a close clearance between said annular member and said sealing surface upon initial rotation of said impeller,

(j) the free end of said second leg pointing along the direction of flow of the fluid whereby any leakage of fluid from the high pressure side of said impeller to the low pressure side will be directed in line with the flow of fluid through said impeller,

(k) said annular member having a space adjacent its outer periphery to allow said annular member to move radially during assembly of said annular member to said housing whereby said second leg may substantially align itself with said sealing surface.

10. A pump comprising:

(a) a stationary housing,

(b) a rotatable impeller disposed within said housing to impel a fluid through said housing,

(0) a sealing surface on said impeller, and

(d) an annular member carried by said housing and having a portion adapted to cooperate with said sealing surface to provide a seal between the high and low pressure sides of said impeller,

(e) said annular member being formed from a malleable metal comprising a combination of tin and 5% antimony by weight whereby at least said portion will be deformed upon initial rotation of said impeller to the extent that said sealing surface is eccentric to the axis of rotation of said impeller.

References Cited UNITED STATES PATENTS 786,922 4/ 1905 Smith et al 103-1 14 1,114,238 10/1914 Doble 103-111 1,525,884 2/1925 Plummer 1031 11 1,631,359 6/ 1927 Brown. 1,681,796 8/ 1928 Wendell. 1,805,765 5/1931 Frederick 103-111 1,878,429 9/1932 Staup 1031 14 2,117,011 5/1938 Pratt -Q 103103 2,209,466 7/1940 Miller 103-111 2,210,401 8/ 1940 Fulton 1031 11 2,431,221 11/1947 Allen 103-103 2,492,935 12/ 1949 McCulloch et al. 2,505,197 4/ 1950 McCulloch et al. 2,869,471 1/ 1959 Copeland 103-111 3,092,306 6/ 1963 Eder. 3,108,366 10/1963 Duffy.

FOREIGN PATENTS 786,795 6/ 1935 France.

2,802 1907 Great Britain.

HENRY F. RADUAZO, Primary Examiner.

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