Patent Application
20100047088
1. Field of the Invention
The subject invention is directed to a roller vane pump driven by an electric motor, wherein the rotor assembly of the electric motor also serves to pressurize the working fluid.
2. Description of Related Art
Pumps are well known in the art, and have been employed in a wide variety of application for many years. Most pumps utilize a motor to drive a drive shaft with a rotary impeller mounted thereon. Typically, large housings are required to contain the separate components. Pumps for the aerospace industry, fuel cell applications and the like must be designed with cost, size, weight, complexity, performance and durability requirements in mind.
In an effort to simplify pump design, U.S. Pat. No. 6,109,887, the disclosure of which is herein incorporated by reference in its entirety, has added a blade to a rotor to push the working fluid. The overall pump in U.S. Pat. No. 6,109,887 is still relatively large as a blade was simply added onto a traditional rotor. In view of the above, there is a need for an improved pump that has parts which serve multiple functions to simplify design and decrease the overall profile.
Pumps in accordance with the subject disclosure have numerous applications such as fuel cells or as a cooling pump for a spacecraft, avionics equipment or for computers and high-power electronics. Such pumps are miniature and can pump fluids in pumped two-phase electronics cooling loops and be used for any applications requiring a small pump.
The subject disclosure is directed to a roller vane pump assembly including a housing defining an interior, at least one inlet for admitting fluid in and at least one outlet for allowing fluid out of the interior. A stator assembly is within the interior and has a stator and windings for generating a rotating magnetic field. The stator assembly defines a pumping chamber within the interior. A rotor assembly mounts for axial rotation within the pumping chamber, the rotor assembly including a body having salient poles to interact with the rotating magnetic field. The body also defines a plurality of hollows intermediate the salient poles, wherein the rotor assembly is mounted eccentrically with respect to the pumping chamber such that a gap between the rotor body and pumping chamber varies circumferentially.
A plurality of cylindrical rollers are disposed in the hollows for free radial movement within the hollows. Fluid-filled volumes are formed between the housing interior, the rotor body and the rollers. On each side of a plane passing through the rotor axis and the housing axis, the pumping chamber is in fluid communication with an inlet or outlet. As the rotor body spins due to the rotating magnetic field, the fluid-filled chambers expand on one side of the plane and contract on the other side of the plane. The expanding volumes draw fluid from the inlet and the contracting volumes expel fluid from the outlet.
In a further embodiment, the stator assembly further comprises a filler material that defines the pumping chamber and secures the stator assembly in place. Alternatively, the stator assembly further comprises a wall for defining the pumping chamber. The rotor assembly may include a permanent magnet coupled to each projection or be fabricated from a magnetic material.
It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, and a method for applications now known and later developed. These and other features of the system disclosed herein will become more readily apparent from the following description and the drawings.
So that those skilled in the art to which the subject invention appertains will readily understand how to make and use a vane pump of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail below with reference to the following figures.
The advantages, and other features of the technology disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred embodiments taken in conjunction with the drawings which set forth some representative embodiments of the present invention. All relative descriptions herein such as 12 o'clock, 6 o'clock, front, rear, side, left, right, up, and down are with reference to the Figures, and not meant in a limiting sense.
Referring now to
The housing 20 of the pump assembly 10 serves as an outer pressure boundary and includes front and rear end caps 22a, 22b. The front and rear end caps 22a, 22b are separated from one another by an annular spacer 24. The end caps 22a, 22b and annular spacer 24 sealingly couple together to form an interior or sealed chamber 25 of the housing 20. The front and rear end caps 22a, 22b may include a circular shoulder 23 only shown on rear end cap 22b.
As shown in
An inlet port 26a and an outlet port 26b are formed in the respective end caps 22a, 22b. In a preferred embodiment, there may be multiple inlet and outlet ports formed separately, in the annular spacer 24 or in a single end cap 22a, 22b. The inlet port 26a admits low pressure fluid into the pump assembly 10. By passing through the pump assembly 10, the low pressure fluid becomes pressurized and exits by the outlet port 26b.
At least one of the end caps 22a, 22b forms an axial passageway 27 through which an elongated shaft 45 passes to attach to the rotor assembly 40. Bearings 46 mount between the shaft 45 and the housing 20, and/or between the shaft 45 and the rotor assembly 40 to reduce friction. The rotor assembly 40 is mounted on the shaft 45 for axial rotation within the housing 20. The rotor assembly 40 rotates about a first central axis or rotor axis 42 (see
The stator assembly 30 is also inside the housing 20 and surrounds the rotor assembly 40. The stator assembly 30 includes a stator 31 and associated windings 32. A control circuit (not shown) provides current to the stator windings or coils 32 to generate a rotating magnetic field. The magnetic field drives the rotor assembly 40. The current to the stator windings 32 may be switched such that the stator and rotor assemblies 30, 40 function as a brushless DC motor in a manner known to those skilled in the art. Alternative embodiments may include, without limitation, synchronous AC motors, switched-reluctance motors and stepper motors.
Referring additionally to
In the embodiment of
Still referring to
In one embodiment, the pumping chamber wall 60 is formed as part of one side of the housing 20. In another embodiment, the pumping chamber wall 60 is a thin sleeve that is inserted into one part of the housing 20 before the stator assembly 30 is potted in place with plastic or epoxy.
Referring to
In another embodiment, the pumping chamber wall 60 is not a separate component from the filler material 61. In other words, the filler material 61 is formed to create a cylindrical surface surrounding the rotor assembly 40. For example, to form the cylindrical surface from the filler material 61, a temporary plug (not shown) is placed into the pumping chamber 70. The space between the housing 20 and the plug is filled with a plastic or epoxy material, in this way creating the cylindrical surface or wall as an integral part of the plastic or epoxy potting compound for the stator assembly 30. After the epoxy or potting compound has sufficiently cured, the plug may be removed.
A cylindrical roller 50 is disposed in each hollow 47 intermediate the salient poles or projections 41 of the rotor body 44. The rollers 50 are free to move within the hollows 47 but radially retained therein by the pumping chamber wall 60. The rollers 50 may be comprised of plastic, metal, ceramic or combinations thereof. Plastic rollers 50 filled with low-friction material are particularly advantageous, as such rollers have low density and low coefficients of friction, minimizing the frictional losses in the pump assembly 10.
As a result of the eccentricity between the rotor assembly 40 and the pumping chamber wall 60, the space 72 between the pumping chamber wall 60 and the projections 41 of the rotor body 44 varies. The position of the rollers 50 in the respective hollow 47 also varies depending upon the rotational position of the rotor body 44. Consequently, the volume between the rotor body 44, the pumping chamber wall 60 and adjacent rollers 50 varies depending upon the rotational position of the rotor body 44.
In operation, the windings 32 of the stator assembly 30 are energized in sequence to provide a rotating magnetic field. The magnetic field interacts with the salient poles or projections 41 to rotate the rotor assembly 40. Fluid-filled volumes 71 are formed between the housing interior 25, the rotor body 44 and the rollers 50. On each side of a plane 49 passing through the rotor axis 42 and the housing axis 43, the pumping chamber 70 is in fluid communication with the inlet 26a or outlet 26b, respectively. As the rotor body 44 spins due to the rotating magnetic field, the fluid-filled volumes 71 expand on one side of the plane 49 and contract on the other side of the plane 49. The expanding volumes 71 draw fluid from the inlet 26a and the contracting volumes expel fluid from the outlet 26b.
For example, assume that the rotor body 44 rotates clockwise in
As the rotor body 44 continues to spin clockwise, the space 72 and the volumes 71 between the six o'clock and twelve o'clock positions decrease (e.g., the left side of the plane 49), expelling fluid from the outlet port 26b. If the rotor body 44 spins counterclockwise, fluid is drawn into the port 26b and expelled from the port 26a. Therefore, the pumping direction may be reversed by reversing the direction of rotor assembly rotation.
In view of the above, the rotor body 44 provides a plurality of volumes 71, partially defined by the varying space 72, which combine to pressurize the low pressure intake fluid. The rotor body 44 also provides projections 41 that act as salient poles, which are a component of the electrical drive motor. Thus, a drive mechanism separate from the component that works the fluid is not required. Such a pump assembly 10 can be miniaturized for applications requiring a small pump because of the dual function of the rotor assembly 40. Additionally, the pump assembly 10 has the rotor assembly 40 and optionally the stator assembly 30 immersed in fluid which may provide cooling for the electrical drive motor of the pump assembly 10.
It is to be appreciated that the subject disclosure includes many different advantageous feature, each of which may be interchanged in any combination on like pump assemblies. While pump assemblies of the subject invention have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications may be made thereto without departing from the spirit and scope of the subject invention as defined by the appended claims.
