Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-02-22
2002-08-06
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S091000, C310S270000
Reexamination Certificate
active
06429557
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates generally to dynamoelectric devices, such as electric motors, and more particularly to the stator construction of the device where the stator assembly consists of a stator having a center bore with a plurality of stator poles circumferentially spaced around the center bore. The stator poles have wiring wrapped in windings around the stator poles and the windings have end turns arranged around the stator center bore at axially opposite sides of the stator. The end turns of the windings are laced and manually positioned at opposite ends of the stator to prevent their interference with the rotor assembly in the stator center bore, the motor housing, and/or with the end plates of the motor housing.
(2) Description of the Related Art
In a traditional dynamoelectric device such as a motor, the stator consists of a plurality of stator poles surrounding a rotor. Devices like this are well known in the art, and one is shown generally in FIG.
1
. Because such devices are well known, their assembly is only generally discussed here. The stator can be a collection of individual poles as in a segmented stator, or can be formed together as a single unit. As shown in
FIG. 1
, the stator poles
10
, generally, have a “I”-shaped cross-section, which creates two channels on opposite sides of a central member
12
or web of the “I”-shaped cross section. A length of wire is wrapped around the central member of the “I”-shaped cross-section forming wire windings
14
that are partially contained within the channels on opposite sides of the central member
12
. Where the wire winding exits one channel at an end of the stator pole
10
, crosses over the central member
12
, and is redirected to enter the channel on the opposite side of the central member
12
, the wire winding creates an end turn
16
.
End turns
16
of the wire windings
14
are created at both axial ends of each stator pole. At times windings are formed with the end turns
16
positioned at an axial distance from the opposite ends of the stator pole
10
to provide a smooth transition as they wrap around the end of the stator pole from one channel to the other channel. At this distance from the stator pole, the end turns are grouped and bound together with laces
18
. Grouping wire windings
14
with laces
18
prevents the wire windings from interfering with subsequent assembly operations. Generally, materials such as insulated tape or common nylon electrical tie wraps are used as laces
18
. After winding, the stator assembly is assembled into a housing
20
, a rotor assembly (not shown) is inserted into the stator center bore, and end plates or end bells (not shown) are assembled over the opposite ends of the housing with the rotor shaft supported by bearings in each of the end plates.
There are many methods of motor construction, and the method described herein and shown in
FIG. 1
, demonstrates one technique where the inside of the housing
20
is fitted to the outer wall of the stator assembly
22
. By lacing the end turns
16
, the wire windings
14
are prevented from accidentally fouling areas adjacent to the stator poles where the housing
20
, rotor assembly (not shown), or end plates (not shown) are installed. As the stator is wound, winding leads
24
are brought from the wire windings
14
around the stator pole for connection outside the stator assembly
22
. The winding leads provide current input to the stator poles
10
for the development of electromotive force, and the winding leads
24
provide connection for other electrical switching devices used to regulate current and stator controls. Winding leads
24
must be sized in length for the particular connection to be made outside the stator assembly
22
, and the winding leads are often color coded to provide assembly personnel a reference during connection to external devices.
This method of stator construction has many shortcomings. Lacing the end turns
16
and grouping the winding leads
24
is a manually intensive operation, requiring significant manipulation of the wire windings. The manipulation of wire windings
14
causes quality problems. Moreover, the process of generating winding leads
24
and installing winding lead connectors adds assembly time to motor manufacturing.
Misplaced end turns
16
and wire windings
14
can compromise conductivity in the stator assembly
22
. As the end turns
16
are manually positioned to clear areas adjacent to the stator poles
10
for the housing
20
, the rotor assembly, or end plate installation, grounding of the wire windings can occur. Generally, the wound stator poles
10
are press fit into the housing
20
. During this operation, loose winding wires can be accidentally crimped or damaged against the housing
20
. End plates (not shown) are often mechanically fastened to the housing
20
. Similarly, during this phase of motor construction, loose winding wires can be accidentally crimped or damaged when the end plates are bolted to the housing. When the rotor assembly (not shown) is installed into the stator assembly bore it is critical that the wire windings
14
and end turns
16
do not foul the interface or air gap between the rotor assembly and the stator assembly bore. Often rotor assembly installation is a blind installation, where the end plates obscure viewing of the rotor assembly. It is important that the wire windings and end turns clear the rotor and shaft of the rotor assembly and the bearing assemblies to be fitted thereon.
Protective sealant is applied to the stator assembly
22
and housing to prevent humidity from damaging the wire windings
14
when the motor is de-energized after a period of operation. The protective sealant also provides electrical insulation for the wire windings
14
from other components and debris. This sealant can become cracked if manual manipulation of the end turns
16
and wire windings
14
is needed when the stator assembly
22
is assembled with the housing, the end shields, and the rotor assembly.
Generation of the winding leads
24
is another manual operation required when winding the stator poles. Winding leads
24
must be properly sized in length after winding to allow proper connection to switching devices outside the stator assembly. The winding leads
24
must be specially marked for terminal points, which vary depending upon customer requirements and motor configuration. The length of the winding leads
24
must be sufficient to allow connection to the terminal points, and the ends of the winding leads
24
must be fitted with connectors. These connectors must be specifically configured for the specific terminal point and connector style required for the customer application. Often, winding leads
24
and connectors are color coded to assist assembly personnel in making proper connections. In the prior art mechanical connectors and shrink caps on winding leads
24
have been used to provide connections to terminal points. However, the preparation of winding leads
24
in this manner creates non-standard interfaces for motor construction. This creates inflexibility in the manufacturing lines and slows overall motor production rates.
The winding leads
24
and the connectors attached thereon are frequently used during inspection and testing. Manual connection and disconnection at these points during this phase of the manufacturing process is also labor-intensive. Quality can be compromised as protective sealant is sometimes damaged from the areas of the leads where connection and re-connection was made.
The problems set forth above could be overcome by a device that attaches to the stator assembly
22
of the motor and contains the winding leads
24
and end turns
16
therein, thus eliminating manual lacing of the winding end turns. The device would also have a terminal container to provide uniform connector styles for winding leads. Additionally, the device would be provided with a compartment for housing protectors such as temperature and current overload circuitry.
SUM
Rassoolkhani Payman
Sheeran Kent
Emerson Electric Co.
Nguyen Tran
Thompson & Coburn LLP
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