Patent Application
20090295243
The invention relates to electric motors and more particularly to methods for positioning and securing a stator in an inner stator motor.
Electric motors have long been used as a means to power compressors used in air conditioning systems. For simplicity and cost effectiveness, electric motors have often been incorporated within a sealed compressor housing, being known as a hermetically sealed compressor. A sealed housing containing the electric motor and the compressor is advantageous because it eliminates the need for a durable power transfer seal between the electric motor and the compressor. Generally, assembly of the hermetically sealed compressor involves press fitting an outer stator into an open end of a half of the compressor housing, fixing it in place. A compressor with an attached inner rotor is then attached to another open end of a half of the compressor housing. Assembly of the hermetically sealed compressor is finished by joining the halves of the compressor housing, aligning the stator and rotor, and welding the housing halves together, forming a finished unit.
As a result of the benefits of the aforementioned outer stator arrangement, inner stator motors have not been used in hermetically sealed compressors. Additionally, inner stator motors encounter manufacturing difficulties when incorporated into a hermetically sealed compressor. Particularly, an inner stator arrangement makes insertion and removal of the stator very difficult. This is because of the large pressing forces needed to secure the stator to a central shaft. A compressor utilizing an inner stator motor could benefit from the higher torque and better space efficiency present in inner stator motors.
It would be desirable to have a method for mounting a stator in an inner stator motor, wherein the method facilitates easy insertion and removal of the stator and allows a stator to be securely and accurately mounted while militating against stator rotation during motor operation.
Presently provided by the invention, an apparatus and method for mounting a stator in an inner stator motor, that militates against stator rotation during motor operation, that allows a stator to be securely and accurately mounted, and facilitates easy insertion and removal of the stator has surprisingly been discovered.
In one embodiment, the assembly for an inner stator motor comprises a motor housing having an open end and a hollow stator post disposed therein, the stator post having at least one slot formed therein; a stator having a cavity and positioned on the stator post, the stator having at least one protuberance cooperating with the slot; and a fastener positioned in the stator post, the fastener exerting a radial force on the stator post and causing the stator post to expand to secure the stator to the stator post.
In another embodiment, the assembly for an inner stator motor comprises a motor housing having an open end and a hollow stator post disposed therein, the stator post having at least one slot formed therein; a stator having a cavity and positioned on the stator post, the stator having at least one protuberance cooperating with the slot; a sleeve disposed in the stator post, the sleeve adapted to engage a tool to remove the fastener from the stator post; and a fastener positioned in the stator post, the fastener exerting a radial force on the stator post and causing the stator post to expand to secure the stator to the stator post.
The invention also provides methods for mounting a stator in an inner stator motor.
In one embodiment, the method for assembling an inner stator motor comprises the steps of providing a motor housing, including a housing having an open end and a hollow stator post disposed in the housing, the stator post having at least one slot formed therein; providing a stator having a cavity, the stator having at least one protuberance to cooperate with the slot; providing a fastener; aligning protuberances of the stator with slots of the stator post; disposing the stator on the stator post; and positioning the fastener in the stator post, the fastener exerting a radial force on the stator post to cause the stator post to expand and secure the stator to the stator post.
The above, as well as other objects and advantages of the invention, will become readily apparent to those skilled in the art from reading the following detailed description of a preferred embodiment of the invention when considered in the light of the accompanying drawings in which:
The following detailed description and appended drawings describe and illustrate an exemplary embodiment of the present invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. It is understood that materials other than those described can be used without departing from the scope and spirit of the invention. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical.
The stator 14 includes a central hub 24 and windings 26. The central hub 24 can be produced from any conventional material such as aluminum, for example, and includes a radial array of winding heads 28. As shown, the winding heads 28 have a “T” shaped cross section, but other shapes may be used as desired. The windings 26 are disposed on the winding heads 28 in a manner needed to result in generation of magnetic forces for operating the completed electric motor. A cavity 30 in the stator receives the stator post 20. The cavity 30 has at least one protuberance 32 adapted to be received in the slot 23 to militate against a rotation of the stator 14 on the stator post 20.
The fastener 16 is adapted to be received in the stator post 20, as illustrated in
A method for assembling an inner stator motor incorporating the motor housing 12, the stator 14, and the fastener 16 facilitates secure and accurate mounting of the stator 14. The method may further provide a sleeve 40 disposed in the stator post 20, wherein the sleeve 40 is adapted to engage a fastener removal tool 42 for removal of the fastener 16 from the stator post 20. The method also militates against a rotation of the stator 14 during motor operation while facilitating easy insertion and removal of the stator 14, dependent on the position of the fastener 16. The method eliminates the need for a difficult mechanical pressing of the stator 14 on the stator post 20, allowing an inner stator motor to be used in a hermetically sealed compressor.
From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions in accordance with the scope of the appended claims.
