Bearing housing

A bearing housing for use with a centrifugal pump can include a bracket and a cradle separated from the bracket by a gap. A plurality of ribs can connect the bracket to the cradle across the gap. The ribs can be sized and configured to improve cooling to help minimize operational temperatures of the cradle.

BACKGROUND

Field

Various embodiments disclosed herein relate generally to centrifugal overhung pumps, including but not limited to horizontal and vertical inline pumps such as API standards classifications OH1, OH2, and OH3.

Related Art

Current centrifugal overhung pumps include components and designs to help maximize operating efficiencies of the pumps, including avoiding excess operational temperatures. However, present devices contain a variety of limitations and disadvantages.

SUMMARY OF THE DISCLOSURE

Centrifugal overhung pumps, such as horizontal and vertical inline pumps, have a variety of applications and can be used, for example, in petroleum or refinery processes, petrochemical processes, gas processing, coal processing, and/or slurry and solids handling. Overhung pumps can also be configured for use with a variety of API processes, and can be adapted to meet the requirements of API standards, such as API 610, API 682, and other standards, such as HI and ANSI standards.

Various embodiments of overhung pumps include an impeller at one end of the pump that may help drive movement of a material. The impeller is typically within a pump housing. Pumps often include a bearing housing connected to the pump housing. The bearing housing can include a bracket portion that can be used to attach the bearing housing to the pump housing. The bearing housing can also include a cradle portion that can retain a plurality of bearings, which help allow for rotation of a shaft that drives the impeller. Many processes are performed at high temperatures such that the impeller receives a significant amount of heat from the material it pumps. Other sources of heat, such as friction, may also heat the impeller.

It is frequently desirable to help minimize the operational temperatures of various portions and components of overhung pumps. Bearings, for example, can have an increased lifespan when they operate at lower temperatures. Additionally, various regulations, safety concerns, or operational concerns may require that portions of the pump remain below certain temperatures. Thus, various pumps include designs to help cool the pump, and in particular the bearing housing, such as by promoting heat transfer away from the pump and bearing housing. In some instances, this can be accomplished by including a shroud around at least a portion of the pump and a fan to help drive air along the body of the pump, promoting convection heat transfer. In some instances, cooling water can be run over a portion of the pump. Both of these cooling techniques, however, require additional expense in the form of energy output and/or the necessity for additional components. Additionally, in the case of cooling water, regulations often require the water to be filtered before it can be dumped. This is commonly done by reverse osmosis or other processes that can be quite expensive. Thus, a pump design, or a design for various components of the pump, that can help maximize efficient cooling of the pump can help minimize operational costs for many pump procedures.

Various embodiments described herein relate to an improved bearing housing that dramatically limits heat transfer from the bracket of the bearing housing to the cradle of the bearing housing and that improves cooling of the bracket. This can significantly decrease operating temperatures within the cradle relative to current bearing housing designs. Various embodiments described herein include a bearing housing with a gap separating the cradle from the bracket. A plurality of ribs can connect the cradle to the bracket across the gap. This can improve the ability of the bracket to cool. It can also minimize heat transfer from the bracket to the cradle.

In various embodiments, bridging ribs between a cradle and a bracket of a bearing housing serve to isolate bearings from heat of a pump. The ribs also create additional surface area for heat to escape in form of convectional and radiant heat loss. In addition, in some embodiments hollow channels that pass through lubricating oil or a lubricant reservoir allow for additional air cooling. These various features can in some embodiments eliminate the need for a cooling fan and/or cooling water.

In various embodiments, a centrifugal overhung pump can include a shaft defining a longitudinal axis of the pump, the shaft having a proximal end and a distal end; an impeller at the distal end of the shaft; a pump housing having an inlet and an outlet, wherein at least a portion of the impeller is within the pump housing; and a bearing housing attached to the pump housing. The bearing housing can include a central channel that receives at least a portion of the shaft, a distal portion that is attached to the pump housing and that includes a distal face and a proximal face, and a proximal portion that houses a plurality of bearings between an outer wall of the proximal portion and the shaft and that includes a distal face and a proximal face. A plurality of ribs can connect the distal portion to the proximal portion, the ribs defining a gap between the proximal face of the distal portion and the distal face of the proximal portion.

In some embodiments, the pump housing can include a pump casing and a casing cover. In some embodiments, the bearing housing can include a length from the distal face of the distal portion to the proximal face of the proximal portion, the ribs can have a length, and the ratio of the width to the length width can be between approximately 20 and approximately 40. In some embodiments, the bearing housing can be formed monlithically. In some embodiments, the plurality of ribs can all either be generally horizontally aligned or generally vertically aligned. In some embodiments, a heat sink can be positioned about the shaft. The heat sink can include a plate that is positioned entirely between the distal portion of the bearing housing and the proximal portion of the bearing housing. In some embodiments, a lubrication ring that has a circumferential notch on its outer surface can be positioned around the shaft. In some embodiments, the lubrication ring can also have a chamfer on either side of its outer surface. In some embodiments, the bearing housing can include an oil reservoir and an enclosed cooling channel can pass through the reservoir, with opposite ends of the enclosed cooling channel communicating with an exterior of the bearing housing.

In various embodiments, a bearing housing for use with a centrifugal pump can include a first portion having an outer wall that defines an interior of the first portion, a first end that is configured to attach to a pump casing, and a second end opposite the first end. The first portion can be configured to receive a pump shaft inserted through the bearing housing and that passes through the first end and the second end. The bearing housing can also include a second portion adapted to house a plurality of bearings and positioned adjacent the first portion. The second portion can have a first side and a second side opposite the first side, the first side closer to the second end than the second side is to the second end, and when the pump shaft is inserted through the bearing housing the pump shaft can pass through the first side and the second side. The bearing housing can also include a gap separating the first portion and the second portion and a plurality of ribs extending across the gap and joining the first portion and the second portion. In some embodiments, the bearing housing can also include an oil reservoir and an enclosed cooling channel that passes through the reservoir.

In some embodiments, the second portion can include a plurality of exterior ridges configured to assist in heat transfer from the second portion. In some embodiments, at least some of the exterior ridges are also ribs extending across the gap and joining the first portion and the second portion. In some embodiments, the bearing housing can include an oil reservoir within the second portion. In some embodiments, an enclosed cooling channel can pass through the oil reservoir and can communicate with an exterior of the second portion.

In various embodiments, a bearing housing for use with a centrifugal pump can include a bracket configured to connect the bearing housing to a pump housing and to receive a portion of a pump shaft passing through the bearing housing, a cradle configured to retain a plurality of bearings between an outer wall of the cradle and a portion of the pump shaft passing through the bearing housing, and a connecting section joining the cradle and the bracket, the connecting section having an outer wall that defines an interior space configured to receive a portion of the pump shaft passing through the bearing housing, and a plurality of slots extending through the outer wall to the interior space to allow airflow through the interior space. In some embodiments, the bearing housing can include an oil reservoir. In some embodiments, an enclosed cooling channel can pass through the oil reservoir and can communicate with an exterior of the oil reservoir.

Various embodiments described herein also relate to an improved lubrication or flinger ring, which can be used to ensure a consistent spread of oil within a bearing housing. Flinger rings are generally positioned about a pump shaft and have a section within a lubricant reservoir of a bearing housing. The rings rotate with the shaft and spread lubricant from the reservoir within the bearing housing. In various embodiments, flinger rings can have different cross-sectional profiles that lead to more stability as they rotate and improved distribution of lubricant.

DETAILED DESCRIPTION

Various embodiments described herein relate to designs of pumps and pump components that can help maximize cooling from an end of the pump that receives a material to an end of the pump that houses bearings in a shaft of the pump. Although various embodiments may be illustrated and discussed with respect to overhung pumps, it is understood that they may equally apply to inline pumps.

FIG. 1illustrates one embodiment of a pump assembly10adapted to help minimize an operational temperature of a bearing housing100and bearings within the housing. The pump assembly can include the bearing housing100and a pump housing20. In some embodiments, the pump housing can include a pump casing22and a cover24. The pump casing and cover can be attached to each other according to a variety of configurations known in the art. The pump housing can also include an inlet26and an outlet28.

FIG. 1also illustrates an embodiment of a pump that includes a shroud80. In some embodiments, a shroud80can be attached to the bearing housing and can include a fan82that can help distribute cooling air across the bearing housing.FIG. 1also illustrates a shaft30, which can pass through the bearing housing and can connect to an impeller within the pump housing.

FIG. 2illustrates a cross-sectional view of one embodiment of the pump assembly10. In various embodiments, the bearing housing100can be removably attached to the pump housing20, such as with bolts2or other attachment mechanisms. This can make it easier to maintain, repair, and/or replace the bearing housing itself and/or various components within the bearing housing. For example, bearings can wear down over time, particularly when operating at high temperatures and may need to be replaced. The bearing housing can be designed according to standard dimensions to make it easier to replace the bearing housing of existing and installed pump assemblies. Thus, according to some embodiments, bearing housings100described herein can be used to retrofit existing pump assemblies to include an improved bearing housing.

The bearing housing100preferably includes a first portion or bracket110at a distal end of the housing and a second portion or cradle120toward a proximal end of the housing. In some embodiments the bearing housing can be formed monolithically. In some embodiments, the bracket and cradle can be formed separately. The bracket can be adapted to provide access to bolts2or other attachment mechanisms that help retain the bearing housing to the pump housing. In some embodiments, the bracket can also retain a seal, such as a mechanical seal, that can seal with the pump housing.

FIG. 2also shows an embodiment of a shaft30that extends through a central channel of the bearing housing100and attaches to an impeller32within the pump housing20. One or more sets of bearings40can be positioned within the bearing housing to help assist with smooth and efficient rotation of the shaft. In various embodiments, a variety of bearings can be used, such as standard deep groove ball bearings, radial bearings, and/or cylindrical roller bearings, depending upon the necessary radial loads or other pump requirements. Preferably, the bearings are positioned within the cradle120. They can be positioned within an interior of the cradle defined by an outer wall128of the cradle.

In some embodiments, a bearing housing can also have components configured to help provide lubrication to the shaft and/or the bearings. Thus, for example, in some embodiments a bearing housing can include a lubricant or oil reservoir50. In some embodiments, an “oil level” line can be provided on the outside of the oil reservoir, such as by being cast as part of the bearing housing. One or more lubrication or flinger rings60can be positioned around the shaft and can rotate with the shaft. One end of the flinger rings can be within the lubricant, and as they rotate with the shaft the flinger rings can help distribute the lubricant within the bearing housing. In various embodiments, the flinger rings can have particular profiles that can help maximize their ability to distribute lubricant and to rotate efficiently about the shaft. In some embodiments, as described in more detail below, the lubricant reservoir50can include one or more cooling channels52that pass through the lubricant reservoir and can help cool the lubricant. The cooling channels can have openings on either end that communicate with an exterior of the bearing housing to allow air to flow through the channels.

In some embodiments, the pump assembly10can include a heat sink70positioned between the cradle120and the distal end of the bearing housing100. The heat sink can help minimize temperatures within the cradle, such as at the bearings, by absorbing a portion of the heat that flows from the pump housing toward the bearing housing and shaft.FIGS. 3A and 3Billustrate one embodiment of a heat sink70.FIG. 3Ais a perspective view andFIG. 3Bis a side view of the heat sink. In some embodiments, a heat sink can comprise a plate72, one or more radial ribs74, and a collar76that can be configured to position the heat sink about the shaft. In various embodiments, described in more detail below, the location of the heat sink on the shaft can help enhance cooling of the bearing housing. In various embodiments, also described in more detail below, certain dimensions of the heat sink can be relevant to help cool the bearing housing. In some embodiments, the heat sink can have a width w1, as illustrated, between a distal end of the collar and a proximal end of the plate. The ribs74can have a width w2between a distal end of the ribs and the proximal end of the plate. Similarly, the plate itself can have a width w3between a distal end of the plate and a proximal end of the plate.

FIG. 4illustrates one embodiment of a bearing housing100that can be designed to help minimize temperatures within the cradle120. The bracket110can have a first or distal end112and a second or proximal end114. The distal end can include mounting apertures111that can be used to mount the bearing housing to a pump housing. The bracket can also include one or more access openings118in an outer wall116of the bracket. The access openings can provide access to an interior of the bracket and anything within the bracket, such as a mechanical seal. In some embodiments, the access openings can also provide access to the mounting apertures111and any bolts or other attachment mechanisms passing through them. In some embodiments, the access openings can be sized according to applicable standards requirements, such as API 682.

The cradle120can include a first or distal end122and a second or proximal end124. In some embodiments, the cradle can also include a plurality of cradle ribs or fins126, which can help maximize heat transfer from the cradle to the environment. Preferably, the cradle includes ribs on at least both sides and the top of the cradle.

FIG. 5Aillustrates a side view of the bearing housing100andFIG. 5Billustrates a top view of the bearing housing. As illustrated inFIGS. 5A and 5B, in some embodiments a bearing housing can include a separation or gap130between the bracket110and the cradle120. Providing a gap as described according to various embodiments herein can dramatically decrease the operating temperatures within the bearing housing. In some embodiments, the bracket and cradle can be connected to each other across the gap by bridging ribs132, which can be separated by openings or slots133. In some embodiments, some of the bridging ribs can be integrally formed with one or more of the cradle ribs126. In some embodiments, all of the cradle ribs126can extend across the gap as bridging ribs132.

In some embodiments, the bridging ribs132can be considered to define an outer wall131of a connecting section between the bracket110and the cradle120. Openings or slots133can pass to an interior of the connection section. In some embodiments, such as shown inFIG. 5A, one or more openings133between bridging ribs132on a first side of the bearing housing can be aligned with openings133on an opposing side of the bearing housing (i.e., positioned about 180 degrees apart). This can help improve cooling of the bracket110and cradle120.

In some embodiments, the openings or slots133can comprise varying percentages of the total outer surface area of the outer wall131of the section connecting the bracket110and the cradle120. For example, a percentage of 0% would indicate that the outer wall131lacks a single opening133. A percentage of 100% would indicate that there is no outer wall surface. In some embodiments, openings133can be at least 20% of the total surface area of the outer wall131. In some embodiments, openings133can be at least 30% of the total surface area of the outer wall131. In some embodiments, openings133can be at least 50% of the total surface area of the outer wall131. In some embodiments, openings133can be at least 70% of the total surface area of the outer wall131.

Referring toFIG. 5B, in some embodiments, the width w4of the gap130can affect the effectiveness of the gap in lowering the operating temperature within the cradle120. In some embodiments, the relationship between the width w4of the gap and the length L1of the bearing housing100can affect how well the bearing housing cools. For example, in some embodiments the ratio of the length L1to the width w4can be between approximately 5 and approximately 70. In some embodiments, the ratio of the length L1to the width w4can be between approximately 10 and approximately 60. In some embodiments, the ratio of the length L1to the width w4can be between approximately 15 and approximately 50. In some embodiments, the ratio of the length L1to the width w4can be between approximately 20 and approximately 40. In some embodiments, the ratio of the length L1to the width w4can be between approximately 25 and approximately 35.

In some embodiments, as illustrated inFIG. 2, the gap130(and any ribs spanning the gap) can be aligned or partially aligned with the heat sink70. In some embodiments, the width w4of the gap can be at least as wide as certain portions of the heat sink and those portions of the heat sink can be aligned with the gap. This can make it easier for heat absorbed by the heat sink to dissipate away from the bearing housing100instead of passing into the cradle120. Thus, for example, in some embodiments the width w4can be greater than or equal to the width w1of the heat sink70(illustrated inFIG. 3B) and the portion of the heat sink defined by the width w1can be aligned with the gap. In some embodiments, the width w4can be greater than or equal to the width w2of the heat sink70, and the portion of the heat sink defined by the width w2can be aligned with the gap. In some embodiments, the width w4can be greater than or equal to the width w3of the heat sink70, and the portion of the heat sink defined by the width w3can be aligned with the gap. In some embodiments, the width w4of the gap130can be less than the width w3of the heat sink.

FIG. 6illustrates a front view of the bearing housing100.FIG. 6also illustrates a distal face140of the bracket110. The distal face can include a central opening142that can be configured to receive a shaft as shown and described above. The distal face can also include one or more mounting apertures111, also described above.FIG. 6also illustrates an opening to the cooling channels52that pass through the lubricant reservoir50.

FIG. 7illustrates a back or rear view of the bearing housing100.FIG. 7also illustrates the proximal face154of the cradle120of the bearing housing. The proximal cradle face154can include a central opening156through which the shaft can also pass.FIG. 7also illustrates the cradle ribs126. In some embodiments, as illustrated, the cradle ribs can extend outward into alignment with an outer perimeter of a proximal face144of the bracket. In some embodiments, one or more of the cradle ribs can extend past the outer perimeter of the proximal bracket face. In some embodiments, one or more of the cradle ribs may not extend completely to the outer perimeter of the proximal bracket face.

FIG. 7also shows the cooling channels52, which can pass entirely through the reservoir50. In some embodiments, as illustrated, a bearing housing100can include two cooling channels. In some embodiments, a bearing housing can have one or no cooling channels, and in some embodiments a bearing housing can have more than two cooling channels. In various embodiments, the cooling channels can have a variety of profiles. Preferably, the cooling channels are shaped to maximize the available surface area for cooling. Thus, as illustrated, in some embodiments the cooling channels can be elongated, generally rectangular slots. In some embodiments they can be oriented generally vertically, in some embodiments they can be oriented generally horizontal, and in some embodiments they can be oriented at an angle. In various embodiments, the cooling channels can have cross-sectional profiles that are oval-shaped, round, square, or of other shapes.

FIGS. 8 and 9illustrate cross-sectional views of the bearing housing100taken at the gap130.FIG. 8is a cross-sectional view identified by the line8-8inFIG. 5A, andFIG. 9is a cross sectional view identified by the line9-9inFIG. 5A.FIG. 8illustrates a distal face150of the cradle120and an opening152in the distal face.FIG. 8also illustrates ribs132that bridge the gap between the cradle and the bracket.

In some embodiments, the bridging ribs132can include side bridging ribs134and top and bottom bridging ribs136. In some embodiments, the bearing housing100can include just side ribs, just top ribs, just bottom ribs, or just top and bottom ribs. In some embodiments, the side ribs134can be shaped and/or configured differently from the top and bottom ribs136. For example, in some embodiments, as illustrated, side bridging ribs134can all have approximately the same profiles and dimensions. In some embodiments, these profiles and dimensions can be different from top and bottom ribs136. In some embodiments, each side rib134can have the same size and dimension of an opposite side rib. In some embodiments, side ribs134and/or top and bottom ribs136can be narrower at an outer end of the ribs than they are at an inner end of the ribs. Thus, for example, in some embodiments, the gaps135between the side ribs can narrow as the gaps get closer toward the opening152in the distal cradle face. Similarly, in some embodiments the gaps137between the upper ribs can narrow as the gaps get closer toward the opening152in the distal cradle face150.

FIG. 9illustrates the bridging ribs extending from a proximal face144of the bracket110. In some embodiments, as described above, the outer ends of the ribs can extend to an outer surface145of the proximal bracket face144. In some embodiments, such as illustrated, the inner ends of the top and bottom ribs136can also or alternatively extend to an inner surface143of the proximal bracket face144that defines an opening146within the proximal face. In some embodiments, as illustrated, an inner end of the side ribs134may not extend all the way to the inner surface143of the proximal face144. In some embodiments, the side ribs134can extend to the inner surface143.

In various embodiments, the upper and lower ribs136can be generally vertically oriented, and the side ribs134can be generally horizontally oriented, such as illustrated. In some embodiments, all of the bridging ribs132can be radially aligned. In other words, in some embodiments each of the ribs can be aligned with a radius extending from a longitudinal axis of the bearing housing.

FIG. 9also illustrates a radius R1of the bracket110at the proximal bracket face144. In various embodiments, efficient cooling of the bearing housing can depend upon the size of the gap130between the bracket110and cradle120relative to the size of the of the bracket or cradle, such as the radius R1. In some embodiments, the ratio of radius R1to the gap width w4can be between approximately 5 and approximately 20. In some embodiments, the ratio of radius R1to the gap width w4can be between approximately 5 and approximately 15. In some embodiments, the ratio of radius R1to the gap width w4can be between approximately 8 and approximately 13.

In some embodiments, efficient cooling of the bearing housing can depend upon the size of the gap130between the bracket110and cradle120relative to the thickness t1of the outer wall116of the bracket110. In some embodiments, the ratio of the thickness t1to the gap width w4can be between approximately 1 and approximately 6. In some embodiments, the ratio of the thickness t1to the gap width w4can be between approximately 2 and approximately 5. In some embodiments, the ratio of the thickness t1to the gap width w4can be between approximately 2.5 and approximately 3.5.

FIG. 10illustrates a temperature analysis performed on one embodiment of a bearing housing100that includes a gap130between the bracket110and cradle120. The analysis assumes a pumping temperature of at least 850 degrees Fahrenheit and a bearing housing in still air (i.e., without a fan or cooling water). As illustrated, the bearing housing100can help lower the temperature at the bracket110from about 850 degrees to about 180 degrees at a location where bearings would be positioned within the cradle120. This temperature distribution may not require additional cooling, or may require only a fan and/or shroud. This is a significant improvement over existing pumps, which often require the addition of cooling water at pumping temperatures of 700 degrees or below.

In various embodiments, it can be desirable to have a bearing housing100with natural structural frequencies that differ from operating frequencies of pumps that may be used with the bearing housing. Many pumps operate at different rotational speeds between 20 Hz and 60 Hz. Thus, for example, it may be desirable for a bearing housing to have a natural frequency that is outside of that range. This prevents potential vibration problems and can allow the bearing housing to be used with a greater variety of pumps. Various embodiments described herein have a natural frequency greater than approximately 200 Hz. In some embodiments, a bearing housing100may have a natural frequency greater than approximately 300 Hz. In some embodiments, a bearing housing100may have a natural frequency greater than approximately 400 Hz. In some embodiments, a bearing housing100may have a natural frequency approximately equal to 433 Hz. In some embodiments, a bearing housing100may have a natural frequency greater than approximately 440 Hz.FIG. 11illustrates the results of a frequency analysis performed on one embodiment of a bearing housing100establishing a first natural frequency of approximately 443 Hz.

In some embodiments, the dimensions of the gap and/or ribs can affect the natural structure frequency of the bearing housing. For example, in some embodiments the gap can have a width w4(shown inFIG. 5A) that is between about 0.50 inches and about 1.50 inches. In some embodiments, the gap can have a width w4that is between about 0.75 and 1.25 inches. In some embodiments, the gap can have a width that is about 1.00 inches. In some embodiments, the gap width can be less than 0.50 inches or greater than 1.5 inches. In some embodiments, average thickness of the ribs can also vary. In some embodiments, the ribs can have an average thickness between about 0.10 inches and about 0.50 inches. In some embodiments, the ribs can have an average thickness between about 0.10 inches and about 0.40 inches. In some embodiments, the ribs can have an average thickness between about 0.20 inches and about 0.30 inches. In some embodiments, the ribs can have an average thickness of about 0.25 inches. In some embodiments, the ribs can have an average thickness less than about 0.10 inches or greater than about 0.50 inches.

In some embodiments, as described above, flinger rings can be used to distribute lubricant within the bearing housing.FIGS. 12 and 13illustrate one embodiment of a flinger ring60that has been configured to improve the efficiency and effectiveness of the flinger ring.FIG. 12illustrates a side view of the ring andFIG. 13illustrates a cross section of the ring. In some embodiments, a flinger ring60can include an outer notch64that extends around the circumference of the ring and can help the ring distribute oil. In some embodiments, the notch can have angled walls that extend toward each other. In some embodiments, the walls can meet each other and the notch can have a profile of a “V.” In some embodiments, as illustrated, the notch walls68can extend toward a bottom69. In some embodiments, the bottom can be flat. In other embodiments, it can be curved.

In various embodiments, the size of the notch64can affect how well the ring distributes oil. Thus, for example, in some embodiments, the width of the ring w5relative to the width of the notch w6can effect oil distribution. For example, in some embodiments the ratio of the width w5of the ring to the width w6of the notch can be between approximately 1.5 and approximately 5. In some embodiments, the ratio of the width w5of the ring to the width w6of the notch can be between approximately 2 and approximately 4. In some embodiments, the ratio of the width w5of the ring to the width w6of the notch can be between approximately 2.5 and approximately 3.5. In some embodiments, the ratio can be approximately 3.

Similarly, in some embodiments, the width of the notch w6relative to its depth d1can affect oil distribution. In some embodiments, the ratio of w6to d1can be between approximately 0.75 and approximately 2. In some embodiments, the ratio can be between approximately 1 and approximately 1.5.

In some embodiments, the ring60can also include a chamfer66on either side of its outer surface. In some embodiments, the size of the chamfer d2can be defined relative to the depth d1of the notch64. In some embodiments, d2can be less than d1, as illustrated. In some embodiments, d2can be greater than d1. In some embodiments, the ratio of the depth d1of the notch64to the size of the chamfer d2can be between approximately 2 and approximately 4. In some embodiments, it can be between approximately 2.5 and approximately 3.5.

In some embodiments, an inner wall of the ring60can include one or more rectangular notches62. The rectangular notches can help the inner ring maintain stability as it rotates with the shaft of the pump assembly. This can help generate a more constant flow of lubricant and a more consistently placed flow of lubricant within the lubricant reservoir50.

The terms “approximately”, “about”, and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount.

Similarly, this method of disclosure is not to be interpreted as reflecting an intention that any claim require more features than are expressly recited in that claim. Rather, inventive aspects may lie in a combination of fewer than all features of any single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment.