Patent Application
20230223809
Embodiments of the present disclosure generally relate to electric motors. More specifically, embodiments of the disclosure relate to an apparatus and methods for segmented stators including over-molded windings and incorporated bus bars for multi-phase electric motors.
A conventional brushless motor typically includes a stator that is centered on a central axis and comprises a plurality of axially laminated steel plates. The stator may include a core back having a circular shape that is centered on the central axis and teeth extending radially inward from an inner circular surface of the core back. The teeth generally are circumferentially spaced from one another. One or more insulators may be attached to each of the teeth and then a magnet wire wound around each of the teeth such that a coil having a multilayer structure of magnet wire is formed on each of the teeth. The brushless motor includes a bus bar having a connector to which the coils arranged on the stator are connected.
In an attempt to reduce mechanical vibrations, some electric motor embodiments include a relatively greater number of teeth comprising the stator. One approach to increasing the number of teeth of the stator is known as a “divided-core” manufacturing technique wherein a plurality of individual stator teeth are formed, and a coil of magnet wire is wound onto each of the teeth. Next, the individual stator teeth are circumferentially attached to one another to form a stator. Another approach is known as a “curving-core” manufacturing technique wherein the coils are wound onto teeth extending from an elongate core back having a substantially linear shape. The core back is then bent at predetermined positions so as to form a circular shape suitable for a stator.
In general, the magnet wire may be wound around each of the above-mentioned teeth separately. As such, each of the teeth may include two protruding wire-ends, a winding-starting end and a winding-terminating end. Thus, the bus bar generally includes twice as many terminals as the number of the teeth comprising the stator. A drawback to increasing the number of terminals arranged on the bus bar, however, is that the space between the terminals is reduced, thus increasing the difficulty associated with connecting the wires to the terminals. Therefore, there is a continual desire to improve manufacturability, eliminate components (e.g., the bus bar), and reduce costs associated with assembling electric motors, particularly in the automotive sector.
An apparatus and methods are provided for a segmented stator comprising over-molded windings and an incorporated bus bar for a multi-phase electric motor. The segmented stator comprises a plurality of stator segments that are arranged into a circular configuration. The circular configuration is fixated by way of a cylindrical portion comprising an injection-molded polymer. Each stator segment comprises a divided core that includes a core back portion and a core tooth portion. An insulator is disposed on at least the core tooth portion, and a winding of magnet wire is disposed on the insulator. An over-molded encapsulation is applied to fixate the divided core and the winding. A bus bar is incorporated into the stator segments and placed into electrical communication with the windings. The bus bar includes annular conductors that may be over-molded such that the bus bar is encapsulated within the segmented stator. Connectors coupled with the bus bar are configured for passing an electric current to the stator segments.
In an exemplary embodiment, a segmented stator for a multi-phase electric motor comprises: a plurality of stator segments that are arranged into a circular configuration; a cylindrical portion that fixates the circular configuration; a bus bar incorporated into the stator segments; and connectors coupled with the bus bar for passing an electric current to the stator segments.
In another exemplary embodiment, the cylindrical portion comprises an injection-molded polymer that is applied to retain the circular configuration of the plurality of stator segments. In another exemplary embodiment, each of the plurality of stator segment comprises: a divided core that includes a core back portion and a core tooth portion; an insulator disposed on at least the core tooth portion; a winding of magnet wire disposed on the insulator; and an over-molded encapsulation of the divided core and the winding. In another exemplary embodiment, the divided core comprises a solid piece of magnetically permeable material, such as iron, steel, or other ferrous materials, without limitation. In another exemplary embodiment, the divided core comprises a plurality of laminated steel plates that are held together by way of the insulator. In another exemplary embodiment, the insulator comprises an over-molding that fixates the plurality of laminated steel plates in the form of the divided core. In another exemplary embodiment, the insulator comprises any suitable polymer that may be injection-molded around the section of the core tooth portion that receives the winding.
In another exemplary embodiment, the over-molded encapsulation is configured to cover and fixate primarily the winding and allow a winding start end and a winding terminal end to protrude from the stator segment. In another exemplary embodiment, the over-molded encapsulation includes raised ribs that are injection molded into the stator segment to define multiple channels so as to facilitate placing the winding into electrical communication with a bus bar. In another exemplary embodiment, the multiple channels are configured to form circular recesses when a plurality of stator segments are assembled into a circular configuration. In another exemplary embodiment, the circular recesses are configured to receive annular conductors comprising the bus bar. In another exemplary embodiment, the bus bar includes connectors whereby electric current may be conducted to the windings by way of the annular conductors. In another exemplary embodiment, the annular conductors are over-molded within the circular recesses such that the bus bar is encapsulated within the segmented stator.
In an exemplary embodiment, a stator segment for a multi-phase electric motor comprises: a divided core that includes a core back portion and a core tooth portion; an insulator disposed on at least the core tooth portion; a winding of magnet wire disposed on the insulator; and an over-molded encapsulation of the divided core and the winding.
In another exemplary embodiment, the insulator comprises an over-molding that fixates a plurality of laminated steel plates comprising the divided core. In another exemplary embodiment, the over-molded encapsulation is configured to fixate the winding and form raised ribs that define multiple channels for placing a bus bar into electrical communication with the winding.
In an exemplary embodiment, a method for a segmented stator for a multi-phase electric motor comprises: forming a plurality of stator segments; arranging the plurality of stator segments into a circular configuration; fixating the circular configuration by way of a cylindrical portion; placing a bus bar into electrical communication with the plurality of stator segments; incorporating the bus bar into the circular configuration; and coupling connectors with the bus bar for passing an electric current to the stator segments.
In another exemplary embodiment, forming the plurality of stator segment comprises: forming a divided core that includes a core back portion and a core tooth portion; disposing an insulator on at least the core tooth portion; disposing a winding of magnet wire on the insulator; and encapsulating the divided core and the winding. In another exemplary embodiment, disposing the insulator includes injection molding an over-molding that fixates a plurality of laminated steel plates comprising the divided core. In another exemplary embodiment, encapsulating the divided core and the winding includes injection molding an over-molded encapsulation to fixate the winding and form raised ribs that define multiple channels for placing a bus bar into electrical communication with the winding.
These and other features of the concepts provided herein may be better understood with reference to the drawings, description, and appended claims.
The drawings refer to embodiments of the present disclosure in which:
While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The invention should be understood to not be limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one of ordinary skill in the art that the invention disclosed herein may be practiced without these specific details. In other instances, specific numeric references such as “first connector,” may be made. However, the specific numeric reference should not be interpreted as a literal sequential order but rather interpreted that the “first connector” is different than a “second connector.” Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present disclosure. The term “coupled” is defined as meaning connected either directly to the component or indirectly to the component through another component. Further, as used herein, the terms “about,” “approximately,” or “substantially” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein.
In general, a conventional brushless motor may be formed by a divided-core manufacturing technique that comprises forming a plurality of individual stator teeth and winding a coil of magnet wire onto each of the teeth before assembling the wound teeth into a circular stator. The magnet wire may be wound around each of the teeth separately, and thus each of the teeth includes two protruding wire-ends that are to be connected to terminals on a bus bar. A drawback to increasing the number of terminals arranged on the bus bar is that the space between the terminals is reduced, thus increasing the difficulty associated with connecting the wires to the terminals. There is a continual desire, therefore, to improve manufacturability, eliminate components, and reduce costs associated with assembling electric motors, particularly in the automotive sector. Embodiments presented herein provide segmented stators and methods for over-molding windings and incorporating bus bars comprising electric motors.
It should be borne in mind that any number of stator segments 104 may be assembled to form a desired segmented stator 100, without limitation. For example, in one embodiment, a three-phase electric motor may include a segmented stator 100 that comprises 18 stator segments 104, such that each phase includes 6 stator segments 104. In another embodiment of a three-phase electric motor, a segmented stator 100 comprises 27 stator segments 104 arranged such that each phase includes 9 stator segments 104. In still another embodiment of a three-phase electric motor, a segmented stator 100 includes 33 stator segments 104 that are arranged such that each phase comprises 11 stator segments 104. Further, in still another embodiment of a three-phase electric motor, a segmented stator 100 includes 36 stator segments 104 that are arranged such that each phase comprises 12 stator segments 104. Thus, it is contemplated that the segmented stator 100 may comprise any number of stator segments 104 that may be arranged into any number of phases and incorporated into any of various multi-phase electric motor configurations, without limitation, and without straying beyond the spirit and scope of the present disclosure.
In some embodiments, the divided core 132 comprises a solid piece of magnetically permeable material, such as iron, steel, or other ferrous materials, without limitation. In some embodiments, the divided core 132 comprises a plurality of laminated steel plates that may be held together by way of an insulator 144. It is contemplated that, in some embodiments, the insulator 144 may comprise an over-molding that fixates the laminated steel plates in the form of the divided core 132. In such embodiments, the insulator 144 may comprise any suitable polymer that may be injection-molded around the section of the core tooth portion 140 that receives the winding 128, as shown in
As further shown in
Turning, now, to
As shown in
As will be recognized, the connectors 224, 228, 232 facilitate passing an electric current to stator segments 104 comprising different phases of the electric motor. For example, during a first phase of the electric motor, an electric current may be passed through all of the first connector 224, the first annular conductor 208, all of the windings 128 comprising first-phase stator segments 104, the common conductor 220, all of the windings 128 comprising second-phase stator segments 104, the second annular conductor 212, and the second connector 228. During a second phase of the electric motor, an electric current may be passed through all of the first connector 224, the first annular conductor 208, all of the windings 128 comprising first-phase stator segments 104, the common conductor 220, all of the windings 128 comprising third-phase stator segments 104, the third annular conductor 216, and the third connector 232. And, during a third phase of the electric motor, an electric current may be passed through all of the second connector 228, the second annular conductor 212, all of the windings 128 comprising second-phase stator segments 104, the common conductor 220, all of the windings 128 comprising third-phase stator segments 104, the third annular conductor 216, and the third connector 232.
Once the stator segments 104 are formed, the method 240 progresses to step 248 wherein a plurality of stator segments 104 may be arranged into a circular configuration suitable for operating as a segmented stator 100 of an electric motor. The segmented stator 100 may comprise any number of stator segments 104, without limitation. In some embodiments, wherein the electric motor comprises a three-phase electric motor, the segmented stator 100 may comprise 18 stator segments 104 that are assembled in step 248 such that each phase includes 6 stator segments 104. In another embodiment of a three-phase electric motor, the segmented stator 100 may comprise 27 stator segments 104 that are arranged in step 248 to includes 9 stator segments 104 in each phase. In still another embodiment of a three-phase electric motor, the segmented stator 100 may include 33 stator segments 104 that are arranged in step 248 such that each phase comprises 11 stator segments 104.
In step 252, the circular configuration of the stator segments 104 may be fixated by an exterior cylindrical portion 112. In some embodiments, fixating the cylindrical portion 112 may comprise injection-molding a polymer that fixates the stator segments 104 in the circular configuration. In some embodiments, the cylindrical portion 112 may be configured to conduct a cooling fluid around the stator segments 104. For example, the cylindrical portion 112 may, in some embodiments, include a water jacket configured to conduct heat away from the stator segments 104. Further, the cylindrical portion 112 may be provided with a plurality of mounting lugs 116 that are disposed at intervals along a circumferential direction and protrude along a radial direction with respect to the cylindrical portion 112. As will be appreciated, the mounting lugs 116 generally may include mounting holes 120 for mounting the segmented stator 100 to a base (not shown) of an electric motor.
Next, in step 256, a bus bar 108 may be placed into electrical communication with the plurality of stator segments 104 that are arranged in the circular configuration. In some embodiments, the bus bar 108 may include annular conductors 208, 212, 216, 220 that may be respectively seated in circular recesses 192, 196, 200, 204 formed by the channels 172, 176, 180, 184 disposed between raised ribs 168 comprising stator segments 104. In some embodiments, the raised ribs 168 may be injection molded into the stator segment 104, such that a winding start end 148 comprising each stator segment 104 may be disposed in any one of the first, second, and third channels 172, 176, 180, and a winding terminal end 152 may be disposed in the common channel 184.
As will be appreciated, the phase of the electric motor in which each stator segment 104 is to participate determines which of the channels 172, 176, 180 is to include the winding start end 148. Thus, step 256 may include disposing the winding start ends 148 of all first-phase stator segments 104 in the first channel 172, disposing the winding start ends 148 of all second-phase stator segments 104 in the second channel 176, and disposing the winding start ends 148 of all third-phase stator segments 104 in the third channel 180. Further, step 256 may include disposing the winding terminal ends 152 of all stator segments 104 in the common channel 184. It should be recognized, therefore, that step 256 may include establishing electrical communication between a first annular conductor 208 of the bus bar 108 and the winding start ends 148 of all first-phase stator segments 104 in the first channel 172, and establishing electrical communication between a second annular conductor 212 and the winding start ends 148 of all second-phase stator segments 104 in the second channel 176. Further, step 256 may include establishing electrical communication between a third annular conductor 216 and the winding start ends 148 of all third-phase stator segments 104 in the third channel 180, and establishing electrical communication between a common annular conductor 220 and the winding terminal ends 152 of all the stator segments 104 in the common channel 184.
Once the bus bar 108 is in electrical communication with the plurality of stator segments 104, the bus bar 108 may be incorporated into the circular configuration in step 260. In some embodiments, the bus bar 108 may include annular conductors 208, 212, 216, 220 that may be respectively seated in circular recesses 192, 196, 200, 204 formed by the channels 172, 176, 180, 184 disposed between raised ribs 168 comprising stator segments 104. Thus, the first annular conductor 208 may be seated into the first circular recess 192, a second annular conductor 212 may be seated into the second circular recess 196, and a third annular conductor 216 may be seated into the third circular recess 200 while a common annular conductor 220 comprising the bus bar 108 may be seated into the common circular recess 204. Once the bus bar 108 is seated in the circular recesses 192, 196, 200, 204, the bus bar 108 may be over-molded such that the bus bar 108 is encapsulated within the segmented stator 100.
As shown in
While the invention has been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. To the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well. Therefore, the present disclosure is to be understood as not limited by the specific embodiments described herein, but only by scope of the appended claims.
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