Abstract:
A bearing assembly, a pump with a bearing assembly and a method of lubricating a pump bearing using a bearing assembly. The bearing assembly includes a bearing carrier and a bearing housing that are rotatably connected to one another to permit axial adjustment of the pump&#39;s impeller or other fluid-conveying apparatus, as well as variable rotational positioning of the bearing carrier relative to a pump housing. Numerous lubricant access apertures placed around the periphery of the bearing carrier facilitate lubricant passage from a connection on the bearing housing to the bearings, regardless of the rotational position of the carrier relative to the bearing housing or other pump structure.

Description:
This application claims the benefit of the filing date of U.S. Provisional Application No. 61/446,731, filed Feb. 25, 2011. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to pumps, and more particularly to a bearing carrier for such pumps that use multiple lubrication access locations for bearings located within the pump. 
     Chemical process pumps are often used to move petroleum products, industrial chemicals, solvents and related fluids. Such pumps are especially well-suited for use with low-viscosity and relatively non-abrasive fluids. In one particular form, chemical process pumps employ rotating vanes that are placed relative to complementary stator or related housing surfaces to ensure tight tolerances and precise degrees of adjustment. One form of such pump, which is manufactured by the assignee of the present invention, is a centrifugal pump with a rotating impeller; such pump is referred to commercially as the Flowserve Durco® Mark 3™ ISO Pump. 
     For optimum capability for handing chemical products, the impellers of such pumps are of a semi front-open type, or a reverse vane type. To ensure continued proper operation over time, the pump impeller may need to be periodically adjusted. In such case (as with the pump model discussed above), the pump may include a device to permit fine-tuned adjustment of the impeller. Such a device involves rotating a bearing carrier that is disposed within a bearing housing; such a process is referred to by the Assignee of the present invention as “micrometer adjustment”. While this ability to quickly and precisely adjust impeller clearances significantly contributes to overall pump operability and efficiency, it increases the complexity of the mechanism used to contain the pump&#39;s thrust bearings. This is especially true in situations involving bearing lubrication, where the connection for grease lubrication or oil mist is traditionally situated in the end face of the bearing carrier to give a simple direct passage into the chamber behind the bearing. This connection position has two disadvantages. Firstly (in situations where the connection is configured to receive grease), the connection is inside a coupling guard which therefore has to be removed every time re-greasing is required. Secondly (in situations where the lubrication system is oil mist), because the bearing carrier is rotatable, then the piping carrying the oil mist to the connection on the bearing carrier has to be remade each time the micrometer adjustment is used. In either form, this undesirably increases maintenance time and complexity. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a bearing carrier for a chemical pump has multiple apertures, slots, ports or related access holes that define passages to allow grease or oil mist entry to the bearing (including the region behind the bearing), irrespective of the bearing carrier orientation. More particularly, the connections for grease, oil mist and related lubricants are situated in the body of the bearing housing, allowing them to be in a fixed position relative thereto. In this way the multiple apertures mean that an adjacent aperture is available regardless of the angular position of the bearing carrier. The multiple apertures or holes in the bearing carrier also ensure that there is no buildup of oil on the outside of the bearing that could otherwise leak along the rotating shaft. Such oil is drained back into an oil reservoir through the adjacent hole or holes. 
     According to another aspect of the present invention, a pump is disclosed that includes a fluid inlet, a fluid outlet and a rotatable shaft-mounted impeller to deliver a fluid between the inlet and outlet. The pump also includes structural members to promote the rotational movement of the shaft and impeller. These structural members include a bearing assembly that is made up of at least a bearing housing and a bearing carrier that are rotatably moveable relative to one another. The bearing housing includes a connection formed through its outer surface such that a fluid link may be formed between a remote lubricant supply and one or more bearings being supported in the bearing housing. Upon coupling of the bearing carrier to the bearing housing, the relative placement of the two is such that lubricant may flow into numerous apertures formed in the channel such that passages defined by the apertures allow delivery of the lubricant to bearings mounted or otherwise supported by the assembly. Importantly, the fluid communication formed by the connection, channel, apertures and passages ensures that lubricant is delivered to the bearing regardless of a relative rotational alignment between the housing and the carrier. In this way, periodic adjustments made to (for example) the pump&#39;s impeller to control a gap or related spacing between it and a portion of the flowpath into which the impeller is disposed will not necessitate disassembly or other maintenance-intensive actions to ensure continued lubricant delivery to the bearings contained within the assembly. In one particular form, the connection in the housing is placed adjacent the channel in the carrier so that direct fluid coupling is established between them. In such a direct coupling configuration, there is no intervening structure to interfere with the relatively free flow of lubricant from the connection to the apertures that form or otherwise feed the passages. 
     According to yet another aspect of the present invention, a method of lubricating a pump bearing compartment is disclosed. The method includes introducing a lubricant to one or more bearings in the bearing compartment, the introducing taking place through a bearing assembly that includes a bearing housing configured to support the bearing, and bearing carrier that is rotatably engageable with the bearing housing. A connection formed in the housing cooperates with a channel formed in the bearing carrier such that numerous lubricant passages formed in the channel receive the lubricant from the connection through the channel regardless of a relative rotational alignment between the bearing housing and the bearing carrier. This is important in that periodic adjustments to pump impeller spacings—as well as uncertain rotational positions between the housing and carrier in the assembly—do not contribute to either (a) a reduction in lubricant delivery due to lubricant flowpath misalingment or (b) increased maintenance time needed to ensure proper alignment of the carrier and housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: 
         FIG. 1  is a cutaway view of a pump highlighting the location of various components therein, including the bearing carrier; 
         FIG. 2  is a section of an assembled bearing housing that makes up a portion of the pump of  FIG. 1 , the housing showing the location of a lubricant connection and an oil drain passage; 
         FIG. 3  is a perspective view of the bearing carrier disassembled from the bearing housing of  FIG. 2 ; and 
         FIG. 4  is a side cutaway view of the bearing carrier of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring first to  FIG. 1 , a cutaway view of a centrifugal pump  1  according to the present invention is shown. Pump  1  includes a pump housing (or casing)  10 , inlet  20  and outlet  30  along with a fluid flowpath (or pumping chamber)  40  defined between them. In the present context, while pump housing  10  may be associated predominantly with the casing formed around the inlet  20 , outlet  30  and flowpath  40 , as well as defining integral or connectable footers and other structural hardware, it will be understood that additional covers, casing or related containment structure may also be included. Inlet flange  25  and outlet flange  35  form mounting locations to fluidly connect the respective inlet  20  and outlet  30  of pump housing  10  to corresponding conduit (not shown), and may include apertures formed therein to receive screws, bolts or related fasteners that can be used to facilitate such connection. An impeller  50  is mounted to an axle or shaft  60  that is rotated by the operation of a separate motor (not shown). In a preferred form, the shaft  60  may be made from a stiff, corrosion-resistant material, such as 316 stainless steel or the like. As is well-understood by those skilled in centrifugal pump art, fluid is received from a separate conduit through input  20  and operated upon by rotating impeller  50  so that it exits the outlet  30  with an increased pressure, velocity or related indicia of energy. A seal chamber  55  is integrally-formed in a cover  56  which is disposed within pump housing  10  behind impeller  50 . Due to the small nature of the clearances between impeller  50  and casing  10  and impeller  50  and cover  56 , they don&#39;t show up in the present drawing. In particular, the clearance of the reverse vane impeller  50  with cover  56  is only about 0.3 mm; with such a clearance, the impeller  50  front face runs about 2 mm axially from the casing  10 . A sealing device (not shown) in chamber  55  prevents leakage of pumped fluid to atmosphere. The reliability of the seal is dependent on the pressure in the seal chamber  55 , which in turn is affected by the clearance between the reverse open impeller  50  and the cover  56 ; this clearance may be set and adjusted by the micrometer adjustment mentioned above. Seals  65  are placed at various axial locations along shaft  60  in order to provide fluid isolation; such seals may be of any suitable static or dynamic configuration (depending on the use), including brush seals, lip seals, labyrinth seals, packing or the like. The potential for high rotational speeds of shaft  60  and impeller  50  means that structural members within pump housing  10  may be exposed to significant loads, often over the relatively long service life of pump  1 . Axially-mounted bearings, such as journal bearings  80 , provide radial load-transferring from the rotating impeller  50  and shaft  60  to structure within pump housing  10  and bearing housing  100 , while thrust bearings  90  provide axial and radial load-transferring. Together, bearings  80  and  90  constitute a group of bearing members. 
     Referring next to  FIG. 2  in conjunction with  FIG. 1 , a bearing carrier  110  is situated within bearing housing  100  at a distal end thereof such that is axially-spaced from impeller  50  within pump housing  10 . The bearing carrier  110  includes the ability to vary axial clearances of impeller  50  relative to cover  56  through an externally adjusted mechanism (such as the aforementioned micrometer adjustment). The thrust bearing  90 , which may be any type of anti-friction bearing capable of taking both an axial and radial load, is retained against axial movement in the bearing carrier  110 . Thrust bearing  90 , which in one preferred embodiment is a double row bearing, is retained by a circlip  66 . Other locking mechanisms, such as nut  67 , are used to help keep thrust bearing  90  locked to the shaft  60 . The shaft  60 , bearing carrier  110 , bearings  80 ,  90  and impeller  50  become an axially fixed assembly. The bearing carrier  110  connects to the bearing housing  100  through threads  68  on their respective surfaces to produce a threaded and rotatable connection therebetween, where the axial position of bearing carrier  110  is determined by how far the threads  68  have been engaged. Thus, by rotating the bearing carrier  110 , the axial clearance between the impeller  50  and the cover  56  may be adjusted. Once the desired position is reached, one or more screws  71  (shown with particularity in  FIG. 1 ) are screwed and tightened through complementary holes  69  formed in the end face of the bearing carrier  110 . For periodic adjustment, the screws  71  are slackened and the bearing carrier  110  is rotated by hand or by tool on one or more bosses (that project rearwardly from the bearing carrier  110 ) until a new desired position of the impeller  50  is achieved, after which the screws  71  are re-tightened to lock the angular position between the bearing carrier  110  and the bearing housing  100  in place. This action improves pump head and efficiency and restores the pressure in seal chamber  55  to that preferred for seal reliability. Other features useful for relating the adjusting clearances to the angular rotation of the bearing carrier  110  may also be used; for example, a scale (not shown) may be included on the end of the bearing carrier  110  as a way to help set clearances without the need for measuring devices. In a pump which has a previously mentioned semi front-open type of impeller (not shown), instead of reverse vane type of impeller  50 , the impeller is set to have a controlled axial clearance with casing  10  instead of cover  56 . The same mechanism is used to make the axial adjustment. 
     As stated above in conjunction with the prior art, a connection for feeding lubricant to the bearings is traditionally located on the rear portion of the bearing carrier. Referring next to  FIGS. 2 through 4 , the grease or oil mist connection  77  of the present invention is relocated onto a circumferential outer surface of the bearing housing  100  such that it is in an accessible and fixed position. This continued accessibility (irrespective of the relative angular position of the bearing carrier  110  to the bearing housing  100 ) is made possible by the bearing carrier  110  having multiple apertures that define passages  72  which convey the lubricant from the connection  77  in the bearing housing  100  to the chamber  78  behind the bearing  90 . A circumferential channel (or groove)  73  is formed in the bearing housing  110  and permits fluid communication among all of the apertures  72  so that the lubricant being introduced through connection  77  can pass through to the bearing  90  even if the lubricant inlet connection  77  and one of the apertures  72  do not exactly line up. 
     If the lubrication is by oil bath, the apertures  72  and circumferential channel  73  connect the chamber  78  at the back of the bearing  90  through grooves  74  to an oil sump  101  in the bearing housing  100 . Such a configuration allows any excess oil behind the bearing  90  to drain back into the sump  101 . In this way, any excess lubricant buildup against bearing  90  has a substantially unimpeded flowpath to the sump  101 , and as with the delivery of the lubricant to the bearing  90  through the connection  77 , channel  73  and apertures  72 , may take place irrespective of the rotational orientation between the bearing carrier  110  and the bearing housing  100 . Significantly, this avoids having lubricant connections (in a manner generally similar to those of connections  77 ) be formed in the bearing carrier  110 , as well as the concomitant need for removing the coupling guard to get access to such connections for re-greasing or related operations. Grooves  74  in the bearing housing  100  fluidly connects to the circumferential channel  73  to make a continuous passage, thereby allowing oil to have access to the rear row of balls (or rollers in some designs) in a double row or pair of bearings that make up bearing  90 , to ensure lubrication. 
     Referring with particularity to  FIGS. 3 and 4 , while the number of lubricant apertures  72  may be varied, (potentially up to a hundred or more) one preferred embodiment includes between twelve and twenty spaced in substantially equal increments about the periphery of the circumferential channel  73  Likewise, threaded holes  69  may be formed in the outer flange of bearing carrier  110  to serve as a way to securely couple it to the bearing housing  100  through the use of complementary screws  71  or the like. 
     While the remainder of the present disclosure focuses on centrifugal (also known as kinetic or dynamic) variants of pump  1 , it will be appreciated by those skilled in the bearing design art that the bearing carrier  110  of the present invention may be applicable to other pump configurations (such as positive displacement pumps) that may require axial adjustment of the fluid-pumping components. 
     While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention, which is defined in the appended claims.