US 3512788 A
Description (OCR text may contain errors)
May 19, 1970. J. KL'VKILBANE 3,512,788
SELF-ADJUSTING WEARING RINGS Filed Nov. 1, 1967 J45 W g M @XX B/MM United States Patent 3,512,788 SELF-ADJUSTING WEARING RINGS John K. Kilbane, Wauwatosa, Wis., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed Nov. 1, 1967, Ser. No. 679,759 Int. Cl. F16j 9/00; F16k 41/00 US. Cl. 277-25 2 Claims ABSTRACT OF THE DISCLOSURE A self-adjusting wearing ring between a pump impeller and the pump casing. The wearing ring is slidably contained in an annular groove in the peripheral surface of the impeller and forced into sealing engagement with the pump casing due to centrifugal force as the impeller rotates.
This invention relates generally to rotary pumps and more specifically to a means for providing a seal between the pump impeller and the pump casing.
In rotary pumps it is necessary to provide a seal between the rotating impeller and the stationary casing so that the fluid passing through the pump will not leak excessively between the impeller and the casing. This is usually accomplished by providing a wearing ring in the pump casing. In most cases the wearing ring is rigidly contained in the pump casing. In some cases means to manually adjust the wearing ring are provided so that adequate sealing can be maintained as wear takes place between the relatively rotating parts. However, even with an adjustable wearing ring, it is difficult to determine when adjustment should be made and at what frequency.
It is therefore the general object of this invention to provide a seal between the pump impeller and the pump casing which is self-adjusting.
A more specific object of the subject invention is to provide a seal element in the pump impeller which is forced radially due to centrifugal action, into sealing engagement with a sealing surface on the pump casing.
These and other objects of the subject invention will become more fully apparent as the following description is read in light of the attached drawing wherein:
FIG. 1 is a cross sectional view of a pump incorporating this invention;
FIG. 2 is an exploded view of a portion of FIG. 1 showing the invention; and
FIG. 3 shows a suggested type of sealing element.
Referring more specifically to the drawing and particularly FIG. 1, the invention is shown for purposes of illustration in connection with a centrifugal pump generally designated 6. The pump has a casing 7 having an axial inlet 8 and a radially spaced discharge 9. .The casing 7 is provided with a rear cover plate 11 which combines with the rest of the casing to define an impeller chamber 12. A suitable impeller 13 is mounted on one end of a drive shaft 14 and positioned within the impeller chamber 12 with the other end of the shaft extending through an opening in the rear cover plate 11. For purposes of illustration, the impeller shown herein is of the closed type and has both a front and rear shroud plate numbered and 15 respectively. The shaft is adapted to be driven by a suitable source of power such as an electric motor (not shown).
A stufling box 16 with an annular cavity surrounding the shaft 14 is formed in the rear cover plate 11. The stuffing box is filled with any suitable packing material and the outboard end of the stufling box is closed oif by an annular gland 17. v
The impeller 13 has an intake 18 aligned with the inlet 8 and a set of blades 19 that propel fluid radially outward into the discharge volute 21. In the preferred em- 3,512,788 Patented May 19, 1970 bodiment, the impeller 13 has a front hub 22 and a rear hub 23. The rear hub 23 is rigidly connected to the shaft 14. In the preferred embodiment shown herein for purposes of illustration, the front hub 22 is an extension of the front shroud plate 10.
The front hub 22 has an annular groove 24 therein with an open end facing radially outward from the rotational axis of the impeller. A sealing surface 26 in the form of a ringed insert is rigidly connected to the pump casing 7 and positioned concentric with the groove 24. A sealing element 27 is slidably contained within the groove 24. The sealing element 27 may be composed of two half sections as shown in FIG. 3. This is to permit radial movernent of the sealing element in the groove 24 due to centrifugal force as the impeller 13 rotates. Grooves 25 are provided on the interior surface of the ring 27. In order to prohibit relative rotation between the ring 27 and the impeller 13 antirotation pins 29 are provided in the front hub 22 and extend into the grooves. The grooves are open on the radially inner end to permit radial movement of the ring. With the sealing element 27 in the groove 24, upon rotation of the impeller the two half sections of the sealing element will move outward into sealing engagement with the insert 26. With this arrangement, an adequate seal is provided between the impeller and the pump casing which does not require periodic adjustment.
There is contact along the surface 28 between the sealing element 27 and the front wall of the groove 24. This contact is caused by the pressure differential between opposite sides of the sealing element. The interior of the pump is exposed to the higher pressure of the fluid WhlCh has been expelled into the volute after passing through the pump impeller. This higher pressure fluid therefore forces the sealing element 24 into contact with the forward surface of the groove 24 providing a seal along the surface 28.
From the above it can be seen that an extremely inexpensive self-adjusting seal has been provided bet-ween the rotating impeller and stationary casing of a rotary pump. Although only one embodiment has been herern shown and described, other embodiments will be ap parent to those skilled in the art after reading this description and it is intended that all such embodiments as come within a reasonable interpretation of the appended claims be covered.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. In a rotary pump, the combination of a casing defining a pumping chamber, an impeller including a hub rotatably supported in the pumping chamber and a sealing device between the impeller and casing for sealing high pressure fluid in the pumping chamber comprising: an annular groove in the outer surface of said hub having radially extending side walls and an open end extending radially from the rotational axis of the impeller; an annular sealing surface on the interior of said casing concentric with said groove and radially spaced therefrom; a sealing ring composed of at least two arcuate segments slidably contained in said groove and moved radially outwardly by centrifugal force into sealing engagement with said sealing surface upon rotation of said impeller, the width of said sealing ring being slightly less than the width of said groove whereby said ring is urged axially into sealing engagement with the side wall of said groove remote from said pumping chamber by the action of the high pressure fluid in the pumping chamber upon rotation of the impeller; and means associated with said ring and said hub prohibiting relative rotational movement therebetween while permitting both radial and axial movement of said ring relative to said hub.
2. The sealing device set forth in claim 1 wherein said pump is of the centrifugal type, said impeller is of 4 the closed 'type having both a front and rear shroud plate 2,570,427 10/ 1951 Chillson et al 27781 X and said groove is in said front shroud plate. 2,943,463 7/1960 Shipley 277-25 X References Cited SAMUEL ROTHBERG, Primary Examiner UNITED STATES PATENTS 5 US. Cl. X.R.
1,715,944 6/1929 Oliver. 2,162,218 6/1939 Hill 27768 X 27732, 132, 174; 103-103, 111