Sealed steady bearing assembly for non-metallic vertical sump and process pumps

A bearing assembly for radially supporting a drive shaft of a pump such as a vertical sump and process pump. The bearing assembly has a bearing housing, a bearing having inner and outer surfaces, a bearing housing for holding the bearing, seals disposed in the housing for retaining a lubricant pumped into a space formed between the inner surface of the bearing and the drive shaft, and at least one water jacket disposed about a portion of the outer surface of the bearing. The water jacket circulates cooling liquid that contacts the outer surface of the bearing and carries away heat conducted through the bearing due to rotation of the drive shaft during operation of the pump.

FIELD OF THE INVENTION
 This invention relates to non-metallic vertical sump and process pumps, and
 in particular to a steady bearing assembly for same that uses a sealed
 bearing supported in a non-metallic, corrosion resistant bearing housing.
 BACKGROUND OF THE INVENTION
 Steady bearing assemblies for non-metallic, vertical sump and process pumps
 are normally lubricated by a clean external source of liquid, usually
 water, or by delivery of product being pumped through a piping system from
 the pump's discharge. Steady bearing assemblies for metallic, vertical
 sump and process pumps are also normally lubricated by a clean external
 source or by product flush. A clean external source of cooling liquid,
 such as water, requires a delivery piping system and a control system to
 shut off the liquid when the pump is not running. Some of these metallic
 pumps employ a sealed bearing assembly that includes a bearing lubricated
 by grease introduced through external tubing. The grease is retained in
 the bearing by lip-style grease seals. Heat generated by the grease seals
 and by churning of the grease is carried away from the bearing through
 convective and conductive heat transfer through the metal housing and
 column pipe preventing excessive temperatures.
 Both of these designs have inherent equipment, material, installation, and
 maintenance costs. For example, water lines installed in climates where
 the ambient temperature drops below freezing must be protected from
 freezing or the pump installed indoors which increases installation costs.
 If the liquid is not turned off, and continues to drain into the sump, the
 liquid will eventually have to be pumped out of the sump and treated which
 adds to maintenance costs. Product-flush bearing lubrication requires that
 the product be relatively clean, although sump applications can contain
 abrasive particles which can accelerate wear of the bearings and
 necessitate repeated and costly replacement. Various chemicals can be
 collected in waste sumps. If the chemicals are corrosive, e.g.,
 hydrochloric acid, sulfuric acid, etc., the bearing assemblies must be
 fabricated using noble alloys to withstand the effects of these chemicals
 and yield a reasonable pump life. Noble alloys, such as Hastelloy B or C,
 Titanium, etc., can be very expensive and have long lead times as compared
 to non-metallic materials that can withstand the same chemicals.
 Accordingly, there is a need for a steady bearing assembly that is less
 costly to build, install and maintain than conventional steady bearing
 assemblies.
 SUMMARY OF THE INVENTION
 A bearing assembly for radially supporting a drive shaft of a pump. The
 bearing assembly comprises a bearing housing, a bearing having inner and
 outer surfaces, a bearing housing for holding the bearing, seals disposed
 in the housing for retaining a lubricant pumped into a space formed
 between the inner surface of the bearing and the drive shaft, and at least
 one water jacket disposed about a portion of the outer surface of the
 bearing. The water jacket circulates cooling liquid that contacts the
 outer surface of the bearing and carries away heat conducted through the
 bearing due to rotation of the drive shaft during operation of the pump.
 A pump comprising a pump assembly, a motor and mounting assembly, a drive
 shaft connecting the motor and mounting assembly to the pump assembly, and
 one or more of the bearing assemblies of the invention for radially
 supporting the drive shaft.

DETAIL DESCRIPTION OF THE INVENTION
 FIG. 1 shows a sealed steady bearing assembly 20 made according to the
 invention, as typically used in a pump 10 such as a non-metallic, vertical
 sump and process pump. The pump 10 includes a mounting plate 11 having an
 upper surface 12 which mounts a motor and mounting assembly 13, and a
 lower surface 14 which mounts in in line order a cylindrical column pipe
 assembly 15, the bearing assembly 20 and a pump assembly 16. A drive shaft
 17, extending through the mounting plate 11, and column pipe and bearing
 assemblies 15, 20, couples the motor and mounting assembly 13 to a pump
 impeller 18 disposed in an impeller casing 19 of the pump assembly 16.
 Fluid pumping is achieved by means of the motor and mounting assembly 13
 which when energized, produces high speed rotation of the impeller 18 via
 the drive shaft 17 which couples the impeller 18 to the motor and mounting
 assembly 13. The steady bearing assembly 20, which is typically disposed
 between the pump assembly 16 and the column pipe assembly 15, radially
 supports the drive shaft 17 and impeller 18, and thus, reduces radial
 movement thereof. This in turn prevents the impeller 18 from contacting
 the impeller casing 19. Although only one steady bearing assembly 20 is
 shown in use with the pump 10 of FIG. 1, it should be understood that
 additional steady bearing assemblies 20 can be employed in the pump 10
 depending upon the length of the column assembly 15 and drive shaft 17.
 Moreover, the steady bearing assembly 20 can be mounted directly on the
 pump assembly 16 as shown in FIG. 1 or between various sections of the
 column assembly 15.
 FIG. 2 shows the steady bearing assembly 20 separate from the pump 10. The
 steady bearing assembly 20 typically includes a bearing housing 21 having
 an axially extending open ended bore 22, a generally cylindrical shape
 bearing 23 disposed in the bore 22, and a grease seal 24 and retaining
 clip 25 arrangement disposed at each end of the bearing 23.
 As shown collectively in FIGS. 3A and 3B, the axial bore 22 of the bearing
 housing 21 has a generally circular cross section and a diameter which is
 greater than that of the drive shaft 17. The bore 22 includes a pair of
 annular recesses 26 for seating the retaining clips 25 in the bore 22, and
 a raised, generally cylindrical bearing land surface 27 disposed between
 the recesses 26 for mounting the bearing 23. The bearing land surface 27
 includes two outer annular grooves 28 separated by an inner annular groove
 29. A first group of orifices having two outer inlet orifices 30 and an
 inner inlet orifice 31, extend through the bearing housing 21 at a first
 location. The outer inlet orifices 30 each open into a corresponding one
 of the outer annular grooves 28. The inner inlet orifice 31 of the first
 group opens into the inner annular groove 29. A second group of orifices
 including two outlet orifices 33 (FIG. 3A & FIG. 2) extend through the
 bearing housing 21 at a second location. Each outlet orifice 33 opens into
 an associated one of the outer annular grooves 28. A pin aperture 34
 extends through the bearing housing 2l at a third location and opens into
 the bearing land surface 27.
 The bearing housing 21 can be fabricated from any suitable corrosion
 resistant non-metallic or metallic material. However, in order to take
 full advantage of the cost saving features of the invention, the bearing
 housing 21 is preferably made from a non-metallic material such as
 fiberglass reinforced polyester because it is significantly less expensive
 than noble metal alloys typically used for fabricating corrosion resistant
 metallic-based bearing housings.
 FIGS. 4A and 4B collectively show the bearing 23 of the steady bearing
 assembly 20. The bearing 23 has a generally cylindrical wall 37 extending
 between first and second open ends 35, 36 thereof. The wall 37 of the
 bearing has an inner surface 38 (contact grease lubrication surface), an
 outer surface 39 (contact cooling liquid surface), and one or more
 apertures 40 extending through an intermediate section of the wall 37
 between the inner and outer surfaces 38, 39. The bearing is typically
 fabricated from carbon or any other suitable bearing material.
 FIGS. 5A and 5B collectively show one of the two grease seals 24 used in
 the steady bearing assembly 21. Each grease seal 24 has a ring-like body
 42 with an inwardly projecting curved sealing lip 43 or flange. The seal
 24 is preferably made from a non-metallic, corrosion resistant material
 such as a graphite filled PTFE. The outer peripheral surface 44 of the
 body 42 includes a slot 45 that houses an elastomeric O-ring 46.
 FIGS. 6A and 6B collectively show one of the retaining clips 25 used in the
 steady bearing assembly 20. Each retaining clip 25 is C-shaped, and
 fabricated from a corrosion resistant metallic material or preferably a
 non-metallic material such as PTFE, that provides the clips 25 with a
 spring like character. This enables the retaining clip 25 to firmly engage
 the axial bore recess 26 when installed therein.
 Referring again to FIG. 2, the components of the steady bearing assembly 20
 interact as follows. A cylindrical space 41 is provided between the inner
 surface 38 of the bearing 23 and the outer surface 56 of the drive shaft
 17 to allow forced delivery of a lubricating grease. The outer surface 39
 of the bearing 23 closes off the annular grooves 28, 29 defined in the
 bearing land surface 27 thereby forming three annular spaces 47, 48, 49
 about the outer surface 39 of the bearing 23. A grease line tube assembly
 and grease pump cup arrangement 50 (FIG. 1) communicates with the
 cylindrical space 41 by way of a passageway formed by the inner inlet
 orifice 31, the inner annular space 48 defined between the inner annular
 groove 29 and the bearing wall 37, and the apertures 40 in the bearing
 wall 37. The grease seals 24 disposed at the ends 35, 36 of the bearing 23
 in the axial bore 22 are positioned so that the free ends of their sealing
 lips 43 face away from the ends 35, 36 of the bearing 23 to seal off the
 cylindrical space 41 to prevent the escape of grease from therein and also
 to prevent liquid and abrasive particles from entering. The retaining
 clips 25 disposed in the annular recesses 26 (visible in FIG. 3B) retain
 the grease seals in the axial bore 22 of the bearing housing 21. The two
 outer annular spaces 47, 49 operate as cooling jackets around the bearing
 23 to remove heat therefrom by circulating pumped cooling liquid supplied
 from the pump assembly's discharge via a piping system 52 that includes a
 discharge pipe assembly 53, flush spacer 54, and internal tube flush
 assembly 55 (FIG. 1). The pumped cooling liquid in the outer annular
 spaces 47, 49 contact the outer surface 39 of the bearing 23 and carry
 away heat conducted through the bearing wall 37 that has been generated by
 fiction between the grease seals 24 and rotating shaft 17, and by viscous
 churning of the grease in the cylindrical space 41 defined between the
 inner bearing surface 38 and the outer surface 56 of the drive shaft 17. A
 pin (not shown) disposed in the pin aperture 34, engages the outer surface
 39 of the bearing 23 to prevent it from spinning relative the bearing
 housing 21.
 As should now be apparent, the sealed steady bearing assembly 20 of the
 invention realizes cost advantages of non-metallic pumps which employ
 conventionally lubricated non-metallic steady bearing assemblies and
 metallic pumps which employ conventionally sealed metallic steady bearing
 assemblies. In particular, sealing features of the bearing assembly 20
 substantially prevent pumped cooling liquid from entering the cylindrical
 space 41 and contacting the inner bearing surface 38 and the outer drive
 shaft surface 56 thus, abrasives in the pumpage can not infiltrate the
 bearing assembly 20 and caused accelerated wear. The water cooled bearing
 feature of the bearing assembly 20 advantageously allows the bearing
 housing 21 to be constructed from relatively inexpensive non-metallic
 corrosion resistant materials like fiberglass reinforced polyester (FRP).
 Non-metallic materials act more like insulators than conductors of thermal
 energy. Consequently, the bearing assembly 20 of the invention provides a
 method for removing heat and preventing the internal bearing temperature
 from exceeding the temperature limits of the bearing housing material.
 Metallic steady bearing assemblies rely solely on the expensive metallic
 corrosion resistant composition (noble metal alloys) of the bearing
 housings for removing heat by way of thermal conduction and convection,
 and do not typically provide any other method for removing heat from the
 bearing housing as the temperature limits of metals are much higher than
 non-metals like FRP.
 FIG. 7 shows another aspect of the invention. More specifically a pair of
 spaced apart holes 60 are provided in the column pipe assembly 15 adjacent
 the top and bottom ends thereof. The holes 60 allow any pumped cooling
 liquid that may be forced up the column pipe assembly 15 by the pumping
 action of the impeller 18 (FIG. 1) to drain back into the sump thus,
 reducing the possibility of abrasive particles being forced through the
 grease seals 24 and damaging the seals 24, the bearing 23, and/or the
 drive shaft 17. The holes 60 also allow drainage of any pumpage that
 collects in the column pipe assembly 15 when the sump level is above the
 level of the holes 60 as is the case before the pump is energized to drain
 the sump.
 It should now be apparent that the sealed steady bearing assembly 20 of the
 invention can be beneficially used in pump applications where it is
 desirable to exclude external environment, reduce or eliminate
 flushing/lubricating liquid, and prevent contaminants from being
 introduced into the bearing by the flushing liquid.
 While the foregoing invention has been described with reference to the
 above embodiment, various modifications and changes can be made without
 departing from the spirit of the invention. Accordingly, all such
 modifications and changes are considered to be within the scope of the
 appended claims.