Patent Application
20090160276
1. Field of the Invention
The subject matter described herein relates generally to motors and, more particularly, to electric motor support structures.
2. Related Art
Support structures for laminated stators and rotors of electric motors are known. In one general construction, end brackets or end shields are mounted to opposing ends of the stator and the rotor. For example, U.S. Pat. No. 5,929,545 illustrates an end shield for mounting on a stack of laminations forming the stator of an electric motor. The end shield has an inner face facing the stack, with four mounting openings alignable with four holes extending into the stack, and a spacer on the inner face adjacent at least one of the openings to space the inner face from the stack so that a threaded fastener extending through the mounting opening and into a hole in the stack can more readily pull material surrounding the hole upwardly to form a protuberance on the stack to engage and resist movement of the end shield relative to the stack.
In another example, U.S. Pat. No. 4,306,168 describes a system that involves the use of self-tapping screws that are inserted through enlarged holes provided in the end shield into mating holes provided in the end face of the core of the stator assembly. During assembly, fasteners are tightened to securely draw the end shield into firm gripping engagement with the end face of the stator core while the desired uniform air gap between the rotor and the bore of the stator assembly is maintained.
However, the above constructions suffer from numerous deficiencies including that the end shield must be closely machined to ensure alignment of the rotor and stator and assembly time and/or cost is relatively high, accordingly, to date, no suitable device or method of motor construction is available.
In accordance with an embodiment of the present invention a motor comprises a rotor core and a stator core disposed about the rotor core. The stator core comprises three support portions and at least one end bracket supporting the stator core solely by three mounting portions that are interconnected with a respective support portion.
In another aspect of the invention, a method of mounting an end shield to a laminated motor stator core, comprises providing a stator core comprising three support portions extending through each of a plurality of laminations of a motor stator core; providing three fasteners; providing an end shield comprising three mounting portions; and securing each of the fasteners solely to a respective one of the three mounting portions and the support portions.
The following detailed description is made with reference to the accompanying drawings, in which:
One embodiment of the present invention concerns a device and a method of motor construction wherein, e.g., alignment problems and assembly time and/or cost is significantly reduced. In one aspect of the invention, a stator core and a rotor core are provided and at least one end bracket supports the stator core solely by three mounting portions that are interconnected with a respective support portion of the stator core.
Referring now to
The motor controller electronics 12 may comprise any well-known and suitable devices for controlling the motor 10. In a usual manner, output torque from the motor 10 is carried by axle 14 which may be grooved at 24 for receiving a correspondingly configured belt (not shown).
As best seen in
The stator core 18 may comprise a number of laminations 28 of a ferromagnetic material, an example of which is shown in detail in
Referring again to
Referring now to
As also seen in
During assembly, the fasteners 56 may be inserted through the mounting portions 54 passing adjacent the notched portions 34 and into the mounting portions 58. Through proper alignment of the mounting portions 54 and 58 and the notched portions 34, the proper gap 36 (
The exemplary embodiment of an end shield with three mounting portions has numerous advantages relative to that with four mounting portions. For example, since three points define a plane, the alignment during assembly of each of three mounting portions is enhanced relative to that of four mounting portions which may define multiple planes without highly precise machining. Accordingly, there is no stress or distortion of an endshield with a three mounting portions that may occur during assembly of an endshield to a motor with a four mounting portions.
Where the end shield is machined at each of the three mounting portions and a machining clamping fixture is configured to reference these mounting portions, nearly perfect bearing pocket alignment can be accomplished. If machining is instead carried out for four mounting portions, greater likelihood of distortion occurs during assembly of the end shield to a motor since the additional aligning of all four mounting portions, which may define multiple planes, on one plane is necessary.
Also, with three mounting portions, an end shield easily lends itself to nesting of motor laminations in a stator die and, further, it will be appreciated that the cost associated with assembly of a fourth bolt is saved.
While the present invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the present invention is not limited to these herein disclosed embodiments. Rather, the present invention is intended to cover all of the various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
