Pump motor combination

A pumping apparatus includes a housing having an inlet at a first end and an outlet at an opposite second end. An encapsulated stator defines an opening and is supported by the housing. A pressure plate includes diffuser vanes formed as part of the pressure plate. The pressure plate is formed as part of the encapsulated stator. A rotor is positioned at least partially within the opening and is rotatable with respect to the stator and an impeller is coupled to the rotor and cooperates with the pressure plate and the housing to pump a fluid from the inlet to the outlet in response to rotation of the rotor.

BACKGROUND

The invention relates to a combined motor and pump assembly. More specifically, the invention relates to a combined motor and multi-stage pump assembly configured to be positioned within a pipe.

In some applications, it is desirable to position a pump and motor within the fluid being pumped. However, this can shorten the life of many of the pump and motor components as some fluids present a corrosive environment for materials typically used to manufacture pumps and motors.

SUMMARY

In one embodiment, the invention provides a pumping apparatus that includes a housing having an inlet at a first end and an outlet at an opposite second end. An encapsulated stator defines an opening and is supported by the housing. A pressure plate includes diffuser vanes formed as part of the pressure plate. The pressure plate is formed as part of the encapsulated stator. A rotor is positioned at least partially within the opening and is rotatable with respect to the stator and an impeller is coupled to the rotor and cooperates with the pressure plate and the housing to pump a fluid from the inlet to the outlet in response to rotation of the rotor.

In another embodiment, the invention provides a pumping apparatus that includes a housing defining an inlet and an outlet and a plurality of diffuser vanes formed as part of the housing and positioned adjacent the inlet. A stator defines an opening and is supported within the housing. An encapsulant is formed around the stator and includes a pressure plate at a first end and positioned adjacent the inlet. A rotor is positioned at least partially within the opening and is rotatable with respect to the stator and an impeller is coupled to the rotor and cooperates with the pressure plate and the diffuser vanes to pump a fluid from the inlet to the outlet in response to rotation of the rotor.

The invention also provides a pumping apparatus that includes a housing having an inlet, an outlet and an interior space between the inlet and the outlet. A motor is positioned in the interior space and includes a rotor positioned adjacent a stator and rotatable with respect to the stator. The stator is substantially surrounded by an encapsulation that defines a pressure plate. A pump is positioned in the interior space and is coupled for rotation with the rotor. The pump includes a first stage impeller positioned adjacent the inlet and a last stage impeller positioned adjacent the pressure plate. The pump is operable in response to rotor rotation to move a fluid from the inlet to the outlet.

Other aspects and embodiments of the invention will become apparent by consideration of the detailed description and accompanying drawings.

DETAILED DESCRIPTION

FIG. 1illustrates a pumping apparatus10in section view. The pumping apparatus10includes a housing15that substantially encloses a motor20and a pump25attached to the motor20. The housing15includes a substantially cylindrical outer wall30, an inlet end cap35, and an outlet end cap40that cooperate to substantially enclose an interior space45. An inlet aperture50is formed in the inlet end cap35and an outlet aperture55is formed in the outlet end cap40. In the illustrated construction, the inlet end cap35is removable to provide access to the interior space45to allow for the insertion and removal of the motor20and the pump25, while the outlet end cap40is formed as part of the cylindrical outer wall30. In other constructions, the inlet end cap35is formed as part of the cylindrical outer wall30or both the inlet end cap35and the outlet end cap40are removably attached to the cylindrical outer wall30.

The housing15includes a support boss60formed as part of the outlet end cap40and arranged to support the motor20in an operating position. A cord boss65extends inward around a cord aperture70. A power cord80passes through the cord aperture70to provide power to the motor30. An outer boss85is formed on the outer surface of the housing15to allow for the passage of the power cord80out of the housing15. A cord seal90and packing nut95are received within the outer boss85to define a seal and inhibit fluid leakage from the power cord opening. The packing nut95is tightened to compress the seal90against the outer boss85and the cord80to form the desired seal.

As illustrated inFIG. 2, the inlet end of the housing15includes a plurality of diffuser vanes100arranged around the inlet aperture50. The diffuser vanes100also include attachment points105that facilitate the attachment of the motor20to the housing15as will be discussed.

Returning toFIG. 1, the motor20includes a stator110and a rotor115positioned adjacent the stator110and rotatable with respect to the stator110. The stator110, illustrated inFIG. 3includes a plurality of windings120(one shown in section) arranged to define a central opening125that is sized to receive the rotor115and an encapsulation130that substantially surrounds the stator110. The encapsulation130, illustrated inFIG. 3includes a first encapsulant135positioned or formed around the stator110to insulate the windings120of the stator110. In some constructions, a stainless steel foil140is positioned along the central opening125of the stator110. The stator110and the stainless steel foil140are then positioned within a mold and the first encapsulant135is injection molded into the stator110. The first encapsulant135thus attaches the stainless steel foil140to the stator110, fills in spaces within the stator110to hold the windings120in the desired position and acts as a binder to hold the windings120together. In some constructions, the stainless steel foil140is positioned around the outside diameter, as well as in the central opening125of the stator110to further protect the stator110from corrosion initiated by contact with the fluid being pumped. It should be noted thatFIG. 3shows the foil and first encapsulant135as being relatively thick compared to the winding120for illustrative purposes only.

The encapsulation130also includes a second encapsulant145formed around the stator110to enhance the structural capabilities of the stator110and to improve the thermal conductivity properties of the stator110. The second encapsulant145defines a first end cap150that covers the end windings on an end of the stator110nearest the outlet end cap40and a second end cap155that covers the end windings on the end of the stator110nearest the inlet end cap35. The first end cap150surrounds the power cord80and defines a boss160that fits within the boss aperture75of the cord boss65. Another boss165formed as part of the outlet end cap40engages the support boss60to position the stator110and the rotor115in the proper position with respect to the housing15.

The second end cap155, illustrated inFIGS. 3 and 4, includes an inner cylindrical surface170that is divided into a bearing surface175and a thrust surface180by a rabbit fit185that extends radially inward from the cylindrical surface170. The bottom of the second end cap155includes a frustoconical surface190and a planar surface195positioned radially outward of the frustoconical surface190that cooperate to define a pressure plate. A plurality of diffuser vanes200are formed as part of the second end cap155and serve to guide fluid in a desired direction after it is discharged from the pump25. A portion of the diffuser vanes200includes an attachment flange205that facilitates the attachment of the motor20to the housing15. In the illustrated construction, the attachment flange205includes an aperture sized for the passage of a fastener (not shown). The fastener engages the attachment points105of the inlet end cap35to attach the motor20and pump25to the housing15.

With reference toFIG. 1, the rotor115includes a cylindrical body210that is sized to fit within the central opening125. A first shaft portion215extends along a rotational axis220toward the outlet55. A first bearing225has an inner aperture that engages the first shaft portion215and an outer surface that engages the first end cap150. A second shaft portion230extends along the rotational axis220toward the inlet aperture50. A second bearing235includes an inner opening that engages the second shaft portion230and an outer surface that engages the second end cap155at the bearing surface175. Thus, the first bearing225and the second bearing235support the rotor115for rotation about the rotational axis220. In the illustrated construction, roller bearings are employed. However, other constructions may include needle bearings, ball bearings, journal bearings or the like.

FIG. 6illustrates a bearing225,235that could be used as either the first bearing225or the second bearing235. As can be seen, the bearing225,235is a typical roller bearing having an inner race, an outer race, and a plurality of rollers positioned between the races. A bearing groove240is formed axially along the inner race to allow fluid to pass through the bearing225,235to cool and lubricate the bearing225,235as will be discussed.

The pump25, best illustrated inFIG. 5attaches to the second shaft portion230and includes an impeller245having a backface250and a plurality of vanes255. The backface250includes a frustoconical portion260and a planar portion265disposed radially outward of the frustoconical portion260. The backface250corresponds to the bottom surface190,195of the second end cap155and cooperates with the bottom surface190,195to form a partial seal therebetween. The plurality of vanes255cooperates with the vanes100of the housing15to form a plurality of channels that operate to pump a fluid in response to rotation of the impeller245. The pump25operates in much the same way as a conventional centrifugal pump or scroll pump. In preferred constructions, the impeller245is permanently attached (i.e., not removal without damaging or destroying components) to the second shaft portion230(e.g., bonded, welded, brazed, soldered, etc.) with other constructions employing non-permanent attachment schemes (e.g., pins, splined shafts, threaded, etc.).

A thrust bearing270, illustrated inFIG. 5is positioned adjacent the thrust surface180of the second end cap155to accommodate the thrust load produced by the pump25during operation. The thrust bearing270includes a biasing member275(e.g., coil spring, Bellville washers, etc.) that engages the rabbit fit185at one end and the pump25at the opposite end. Of course other constructions could use other types of thrust bearings270or could combine the function of one of the first bearing225and the second bearing235with the function of the thrust bearing270by using a single combined rotary and thrust bearing capable of supporting the rotor115for rotation and supporting a thrust load.

To assemble the pumping apparatus10, the stator windings120are positioned on a support structure. Once wound, the windings and support structure are positioned in a mold. Typically, the mold includes a core wrapped with the stainless steel foil140. The first encapsulant135is injection molded into the windings120to seal and insulate the windings120and to hold the stainless steel foil140against the windings120. The windings120, the first encapsulant135, and the mold core are then positioned within a second mold and the second encapsulant145is injected into the second mold to complete the stator110(as illustrated inFIG. 4). Leaving the mold core in the partially completed stator110assures that the core will be properly positioned in the second mold.

The rotor115is next positioned within the stator10. The first bearing225and the second bearing235are positioned to engage the rotor115and the stator110to support the rotor115for rotation. Next, the thrust bearing270is positioned on the second shaft portion230and the pump impeller245is positioned against the second shaft portion230and welded or otherwise attached. The inlet end cap35is next attached to the stator110. The attachment points105of the housing vanes100are aligned with the attachment flange205of the vanes200of the inlet end cap35and fasteners are used to complete the attachment.

The inlet end cap35is moved into engagement with the cylindrical outer wall30of the housing15as the power cord80is pulled through the aperture75. The inlet end cap35is then attached to the cylindrical outer wall30of the housing15. In one construction, the inlet end cap35is welded in place with other constructions using a threaded connection. The packing nut95is then tightened to complete the assembly of the pumping apparatus10.

In one construction, the pumping apparatus10is used as a submersible water pump. In operation in this construction, power is provided to the motor20to rotate the rotor115and the impeller245. Water is drawn into the impeller245through the inlet aperture50and is pumped toward the outlet aperture55. Water is able to pass through the impeller245(via a bleed aperture280) and some water may pass between the pressure plate190,195and the backface250and to the bearing groove240to cool the second bearing. Water continues to flow between the cylinder outer wall30and the stator110toward the outlet aperture55. Water is able to flow to the first bearing225and through the bearing groove240to cool and lubricate the first bearing225before it is ultimately discharged from the pump25through the outlet aperture55.

FIG. 7illustrates another construction of a pumping apparatus290in which the single stage impeller245is replaced by a multi-stage pump295including a plurality of impellers300. A first stage impeller300adraws fluid in through the inlet aperture50as has been described, and passes the fluid to the next successive stage300b. The final stage300n(adjacent the motor20) discharges the fluid into the cylindrical outer wall30much like the construction ofFIGS. 1-6. The additional stages allow the pump295to discharge at a higher overall pressure ratio, thereby allowing the pump295to pump water or other fluids to a higher level or to a higher pressure.

The construction ofFIG. 7also illustrates a thrust bearing305positioned at the opposite end of the motor20when compared to the construction ofFIG. 1. As one of ordinary skill will understand, there are many different arrangements of bearings and thrust bearings, as well as other components that are possible. As such, the invention should not be limited to the constructions illustrated herein.

FIG. 8illustrates another construction of a pumping apparatus305in which two pumping assemblies290such as those illustrated inFIG. 7are arranged in series to further enhance the pressure ratio, outlet pressure, or overall pumping capability of the system. In this construction, the outlet aperture55of the first pumping apparatus290ais connected to the inlet aperture50of the second pumping apparatus290b. As one of ordinary skill will realize, more than two pumping apparatus290or different arrangements of the pumping apparatus10,290could be arranged in series as desired. For example, in another construction, the single stage arrangement ofFIG. 1is combined in series with the multi-stage arrangement ofFIG. 7. In still other constructions, three or more assemblies are arranged in series.

Thus, the invention provides, among other things, a new and useful pumping apparatus10,290,305for pumping fluid. The constructions of the pumping apparatus10,290,305and the methods of manufacturing the pumping apparatus10,290,305described herein and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the invention.