Tab insulators for insulating armature core slots

Abstract: The invention provides an insulator (52) for insertion in an armature core slot (30) of a motor (10) and for preventing an electrical connection between the core (22) and wire (32) wound in the armature core slots (30). The insulator (52) includes, when it is mounted in an armature core slot (30), a first end (54) aligned with an end (24) of the core (22) that faces a commutator (20) included in the armature (14), and a second end (56) aligned with the opposite end (26) of the core (22). The insulator (52) further includes a tab (58) extending from the second end (56) of the insulator (52). The tab (58) is bent to prevent movement of the insulator (52) in the slot (30) and toward the commutator (20). The insulator (52) optionally includes another tab (66) extending from the first end (54) of the insulator (52). The optional tab (66) is bent to prevent movement of the insulator (52) in the slot (30) and away from the commutator (20).

Description: FIELD OF THE INVENTION The invention relates generally to armatures for electric motors and, more particularly, to insulators for armature core slots that are adapted to have wire wound therein. BACKGROUND OF THE INVENTION It is known to insert paper, paper-mylar, or mylar insulators in slots (or channels) in a core of an armature to prevent electrical contact between wire wound in the slots and the core as shown in DE-A-30 44 537. Typically, a roll of insulation paper is fed between forming rolls to define a core slot insulator shape, is cut to a length corresponding to the axial length of the core, and is inserted into the core. Machines that use this process to insert insulators in each slot of an armature core are commercially available. After the insulators are inserted into each slot of an armature core, wire is wound into the slots to define coils of wire. When a first strand of wire falls into one of the insulated slots, the wire tends to move the insulator axially in the direction in which the wire is wound. If the insulator moves in the slot, a portion of the core may be exposed adjacent a wire. The wire may not thereafter be adequately insulated from the core. Further, at the other end of the core, the insulator will protrude from the end of the core and wound wire may split the insulator at the bend lines of the insulator, resulting in the wire travelling through the split and toward an exposed portion of the core. In either case, the wound armature may have to be scrapped or reworked. In large armatures, washers may be provided on opposite ends of the armature core before wire is wound and after insulators are slid into the core slots. These washers overlap a radially inwardly located portion of each of the slots in the core and prevent axial movement of the insulators in the core slots. A problem with this approach is that the washers used are relatively expensive and use of washers requires additional manufacturing operations during assembly of an armature. According to the invention, there is provided an armature comprising a shaft supportable for rotation in a motor body and defining an axis, a commutator on said shaft and rotatable with said shaft, an armature core on said shaft, rotatable with said shaft and spaced from said commutator, said core having an end facing said commutator, an opposite end, and an outer generally cylindrical surface including a plurality of spaced apart slots adapted to have wire wound therein, each of the slots extending in a direction generally parallel to the axis, a core end insulator on said opposite end of said core, said core end insulator having a side facing said core and having a side facing away from said core, and insulator means, slidably mounted in one of said slots, for preventing an electrical connection between said core and wire wound in the slots, said insulator means comprising a main body portion having a first end generally aligned with said commutator facing end of said core, and having a second end generally aligned with said opposite end of said core, characterized in that said insulator means further comprises tab means extending from said second end of said main body portion and for preventing movement of said insulator means in said one of said slots in a direction parallel to the axis, said tab means extending out of said one of said slots and being bendable against the side of said core end insulator facing away from said core. In one aspect of the invention, one or both of the tabs (if not yet bent) are bent by wire as wire is wound in the core slots, and the wire cooperates with the tab(s) to prevent movement of the insulator in the slot. In another aspect of the invention, the armature core slot is channel shaped, the insulator is correspondingly channel shaped and includes sidewalls and a bite portion connecting the sidewalls, and the tab(s) extend()s) from the bite portion. These and other features and advantages of the invention will become apparent to one of ordinary skill in the art upon review of the following detailed description of the preferred embodiment of the invention, reference being made to the appended drawings. BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS Fig. 1 is a perspective view of a motor embodying various of the features of the invention. Fig. 2 is a block diagram illustrating a method for manufacturing the motor of Figure 1. Fig. 3 is a block diagram illustrating an alternative method for manufacturing the motor of Fig. 1. Fig. 4 is a partially exploded perspective view illustrating an armature core and an insulator that are included in the motor of Fig. 1, and illustrates a step that is including in the method of Fig. 2 or the method of Fig. 3. Fig. 4 illustrates a core end insulator that is partially broken away to show an end of the armature core. Fig. 5 is a perspective view illustrating the insulator of Fig. 4 mounted in the armature core of Fig. 4. Fig. 6 is a perspective view illustrating the insulator of Fig. 4 mounted in the armature core of Fig. 4 and illustrating a core end insulator partially broken away to show a commutator end of the armature core. Fig. 7 is a perspective view illustrating the armature of Fig. 5 after a step that is optionally included in the method of Fig. 2 or the method of Fig. 3. Fig. 8 is a perspective view illustrating the armature of Fig. 6 after a step that is optionally included in the method of Fig. 2 or the method of Fig. 3. Fig. 9 is a perspective view illustrating the armature of Fig. 5 after wire is wound in the core slots of the armature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Illustrated in the various figures is a method of manufacturing a motor 10. The motor 10 includes a motor body 12 that supports a motor armature 14 for rotation. The armature 14 includes a shaft 16 (see Figs. 5-9) that is supportable for rotation in the motor body 12, and that defines an axis 18. The armature 14 further includes a commutator 20 on the shaft 16 and rotatable with the shaft 16. The armature 14 further includes an armature core 22 on the shaft 16, rotatable with the shaft 16, and spaced from the commutator 20. The core 22 is defined by a lamination stack. The core 22 has an end 24 (see Fig. 6) facing the commutator 20, an opposite end 26 (see Fig. 4), and an outer generally cylindrical surface 28 including a plurality of radially spaced apart slots 30 extending radially inwardly therefrom and adapted to have wire 32 wound therein (see Fig. 9), each of the slots 30 extending in a direction generally parallel to the axis 18. Each of the slots 30 has a length LS (see Fig. 4) defined between the commutator end 24 and the opposite end 26 of the core 22. Preferably the armature further comprises a core end insulator 104 (see Figs. 4 and 7) on the opposite end 26 of the core, the core end insulator 104 being configured to prevent electrical contact between the opposite end 26 of the core 22 and wire 32 wound in the slots 30. Preferably, the armature further comprises a core end insulator 108 on the commutator end 24 of the core, the core end insulator 108 being configured to prevent electrical contact between the commutator end 24 of the core 22 and wire 32 wound in the slots 30. While various slot configurations are possible, in the illustrated embodiment each of the slots 30 is channel shaped and includes a channel bottom surface 34, and channel side walls 36 transversely extending from the channel bottom surface 34. The channel bottom surfaces 34 collectively define an inner cylindrical surface 38 of the core 22, and adjacent sidewalls 36 of adjacent channel shaped slots (channels) 30 define spokes 40 (see Figs. 4 and 6) extending radially outwardly from the inner cylindrical surface 38. The armature core 22 defines, on each spoke 40, an arcuate portion 42 of the outer cylindrical surface 28. Adjacent arcuate portions 42 define opposed ribs 46 that each define a portion of, and that together partially close, the channel 30 that the arcuate portions 42 are commonly adjacent to. The method further comprises the step of providing a strip 48 or 50 (see Figs. 2 and 3) of insulating material (preferably paper, paper-mylar, or mylar). The method further comprises the step of cutting and bending the strip 48 or 50 to define an insulator 52 having a shape generally corresponding to the shape of one of the channels 30 for close sliding contact with the channel 30, and inserting the insulator 52 into one of the channels 30 in the armature core 22, such that the insulator 52 has a main body portion 53 (see Fig. 5) having an end 54 aligned with the commutator end 24 of the core 22, and having an end 56 aligned with the opposite end 26 of the core 22, and such that the insulator 52 has a tab 58 extending from the opposite end 26 and out of the channel 30, and such that at least a portion 60 of the tab 58 is selectively deformable (or bendable) to lie in a plane 62 that is generally parallel to a plane 64 defined by the opposite end 26 of the core. In one form of the invention, the insulator 52 further includes a tab 66 extending from the commutator end 24 and out of the channel 30, and such that at least a portion 68 of the tab 66 is selectively deformable (or bendable) to lie in a plane 70 that is generally parallel to a plane 72 defined by the commutator end 24 of the core. The insulator 52 has a length dimension extending between the end 54 and the end 56. The strip of insulating material (see Fig. 2) is a strip 48 having a sufficient length L that a plurality of insulators 52 could be made from the strip 48. The strip 48 has a width W perpendicular to its length, and the strip 48 is bent along lines parallel to the length dimension L to define the channel shape. The strip has a constant width W, before the bending, cutting and inserting step, for a length L that is sufficient for two insulators 52 to be made from the strip 48. The method illustrated in Fig. 2 employs an apparatus 74 that includes forming rolls that bend the strip 48 on bend lines 73 that are illustrated with long dashes, and that includes a cutter that cuts the strip 48 along cut lines that are illustrated with short dashes, to perform the bending, cutting and inserting step to define the insulator 52. The apparatus 74 is preferably a conventional machine for cutting and bending a conventional strip 48, the machine being advantageously modified to cut the strip 48 along the cut lines 75. In Fig. 3, the strip of insulating material is a strip 50 of sufficient length L2 that a plurality of insulators 52 could be made from the strip 50. The strip 50 has a width W2 perpendicular to its length, and the strip 50 is bent along lines parallel to the length dimension L2 to define the channel shape. The strip 50 has pairs 76 of opposite notches 78 at a plurality of locations along the length L2 of the strip 50, before the cutting, bending, and inserting step. Each pair 76 of opposite notches 78 defines a reduced width connecting portion 80. The bending, cutting, and inserting step includes the step of cutting the strip 50 at one of the reduced width portions 80 such that at least a portion 82 of the one reduced width portions 80 defines at least one tab 58 or 66. The cutting, bending, and inserting step comprises the step of cutting the strip 50 across the one of the reduced width portions 80 to separate one insulator 50 from an adjacent insulator 50 and to define the tab 58 or 66 of the one insulator 50 and to define a tab 58 or 66 of the adjacent insulator 50. The method illustrated in Fig. 3 employs an apparatus 84 that includes forming rolls that bend the strip 48 on bend lines 77 that are illustrated with long dashes, and that includes a cutter that cuts the strip 48 along cut lines 79 that are illustrated with short dashes, to perform the bending, cutting and inserting step to define the insulator 52. Although the cut lines and bend lines illustrated in Figs. 2 and 3 are used to define insulators 52 having lengths (between the end 54 and the end 56 of each insulator) parallel to the length L or L2 of the strip 48 or 50 from which the insulators are defined, the bend and cut lines could be arranged in other configurations, for example, to define the lengths of each insulator (between the end 54 and the end 56) perpendicularly to the length L or L2. While other methods of manufacturing the insulator 52 can be used, and while insulators differing from the insulator 52 can be used, in the preferred embodiment the insulator 52 formed by either the method of Fig. 2 or the method of Fig. 3 is used to define an armature, in accordance with the invention, comprising insulator means, slidably mounted in one of the slots 30, for preventing an electrical connection between the core 22 and wire 32 wound in the slots 30, wherein the insulator means comprises a main body portion 53 having an end 54 aligned with the commutator end 24 of the core 22, an end 56 aligned with the opposite end 26 of the core 22, and wherein the main body portion 53 further includes tab means 58 extending from the opposite end 26 of the main body portion 53 and for preventing movement of the main body portion 53 of the insulator means in the slot in a direction parallel to the axis 18 and toward the commutator 20, the tab means 58 extending out of the slot 30. Preferably, the insulator means used to define the armature further comprises tab means 66 extending from the commutator end 24 of the main body portion 53 and for preventing movement of the main body portion 53 of the insulator means in the slot in a direction parallel to the axis 18 and away from the commutator 20, the tab means 66 extending out of the slot 30. Alternatively stated, while other methods of manufacturing the insulator 52 can be used, and while insulators differing from the insulator 52 can be used, the insulator 52 formed by either the method of Fig. 2 or the method of Fig. 3 is used to define an armature, in accordance with the invention, comprising an insulator slidably mounted in one of the armature slots 30, the insulator including a portion 86 having an end 88 (see Fig. 6) aligned with the commutator end 24 of the core 22 and having an end 90 (see Fig. 5) aligned with the opposite end 26 of the core 22, and including a portion 92 having a length longer than the length LS of the slot 30 in which the insulator 52 is mounted. The portion 92 has an end 94 extending out of the slot 30 past the opposite end 26 of the core 22 to define the tab 58. The portion 92 further has an end 96 (see Fig. 6) that is either aligned with the commutator end 24 of the core 22, or that extends out of the slot 30 past the commutator end 24 of the core 22 to define the tab 66. Preferably, the armature provided by the invention comprises an insulator (or insulator means) 52, having a tab (or tab means) 58 and optionally further having a tab (or tab means) 66, in all of the slots 30 of the armature. Preferably, at least the portion 60 of the tab (or tab means) 58 lies in the plane 62 that is generally parallel to the plane 64 defined by the opposite end 26 of the core 22 to perform the function of preventing movement of the ends 54 and 56 of the insulator (or insulator means) 52 in the direction parallel to the axis 18 and toward the commutator 20. Preferably, at least the portion 68 of the tab (or tab means) 66 lies in the plane 70 that is generally parallel to the plane 72 defined by the commutator end 24 of the core 22 to perform the function of preventing movement of the ends 54 and 56 of the insulator (or insulator means) 52 in the direction parallel to the axis 18 and away from the commutator 20. Preferably, when the insulator (or insulator means) 52 of the armature provided by the invention is in one of the armature slots 30, the tab (or tab means) 58 is appropriately located in the slot 30, and is appropriately bendable, so as to be bent by wire 32, to lie in the plane 62, when wire is wound in the slot 30. Then, the wire 32 wound in the slot 30 will cooperate with the tab (or tab means) 58 to prevent the insulator (or insulator means) 52 from sliding in the slot 30. Preferably, when the insulator (or insulator means) 52 is in one of the armature slots 30, the tab (or tab means) 66 is appropriately located in the slot 30, and is appropriately bendable, so as to be bent by wire 32, to lie in the plane 70 when wire 32 is wound in the slot 30. Then, the wire 32 wound in the slot 30 will cooperate with the tab (or tab means) 66 to prevent the insulator 52 from sliding in the slot 30. Preferably, the insulator (or insulator means) 52 of the armature of the invention has a shape generally corresponding to the shape of the channel 30 in which the insulator (or insulator means) 52 is mounted, and the insulator (or insulator means) 52 comprises opposed sides 98 (see Fig. 8), each of the opposed sides 98 being in close contact with one of the sidewalls 36 of the channel 30 in which the insulator (insulator means) 52 is mounted, a bite portion 100 transverse to each of the opposed sides 98 and connecting the opposed sides 98, the bite portion 100 being in close contact with the channel bottom surface 34 of the channel 30 in which the insulator (or insulator means) 52 is mounted, and an inwardly extending flange 102 extending from each of the opposed sides 98, each of the inwardly extending flanges 102 being in close contact with one of the opposed ribs 46, and the tab (or tab means) 58 extends from the bite portion 100 of the insulator (or insulator means) 52. The optional tab (or tab means) 68, if included in the insulator (or insulator means) 52, also extends from the bite portion 100. Preferably, at least the portion 60 of the tab (or tab means) 58 lies in a plane parallel to the plane defined by the core end insulator 104 and lies in contact with the core end insulator 104. Although the armature 14 could be manufactured with the tab (or tab means) 58 in another location, in the preferred embodiment, the tab (or tab means) 58 lies against an axially outer side 106 (see Figs. 4 and 7) of the core end insulator 104, with respect to the axis 18. Preferably, at least the portion 68 of the optional tab (or tab means) 66, if included, lies in a plane parallel to the plane defined by the core end insulator 108 and lies in contact with the core end insulator 108. Although the armature 14 could be manufactured with the tab (or tab means) 66 in another location, in the preferred embodiment, the tab (or tab means) 66, if included, lies against an axially outer side 110 of the core end insulator 104, with respect to the axis 18. Preferably, the opposite end 26 of the core 22 is generally planar, and the core end insulator 104 is also generally planar.

Claims: An armature (14) comprising a shaft (16) supportable for rotation in a motor body (12) and defining an axis (18), a commutator (20) on said shaft (16) and rotatable with said shaft (16), an armature core (22) on said shaft (16), rotatable with said shaft (16) and spaced from said commutator (20), said core (22) having an end (24) facing said commutator (20), an opposite end (26), and an outer generally cylindrical surface (28) including a plurality of spaced apart slots (30) adapted to have wire (32) wound therein, each of the slots (30) extending in a direction generally parallel to the axis (18), a core end insulator (104) on said opposite end (26) of said core (22), said core end insulator (104) having a side facing said core (22) and having a side facing away from said core (22), and insulator means (52), slidably mounted in one of said slots (30), for preventing an electrical connection between said core (22) and wire (32) wound in the slots (30), said insulator means (52) comprising a main body portion (53) having a first end (54) generally aligned with said commutator facing end (24) of said core (22), and having a second end (56) generally aligned with said opposite end (26) of said core (22), characterized in that said insulator means (52) further comprises tab means (58) extending from said second end of said main body portion (53) and for preventing movement of said insulator means (58) in said one of said slots (30) in a direction parallel to the axis (18), said tab means (58) extending out of said one of said slots (30) and being bendable against the side (106) of said core end insulator (104) facing away from said core (22). An armature (14) as set forth in claim 1 and further characterized in that a second core end insulator (108) on said commutator facing end (24) of said core (22), said second core end insulator (108) having a side facing said core (22) and having a side (110) facing away from said core (22), and a second tab means (66) extending from said first end (54) of said insulator means (52) and for preventing movement of said insulator means (52) in said one of said slots (30) in a direction parallel to the axis (18), said second tab means (66) extending out of said one of said slots (30) and being bendable against the side (110) of the second core end insulator (108) facing away from said core (22). An armature (14) as set forth in claim 1 and further characterized in that said tab means (58) is formed of insulating material, and said tab means (58) and said insulator means (52) both comprise the same type of insulating material. An armature (14) as set forth in claim 1 and further characterized in that one of said insulator means (52) is mounted in each of said slots (30). An armature (14) as set forth in claim 1 and further characterized in that said tab means (58) is located so as to be bent by the wire (32), when said armature (14) is wound with the wire (32), to lie in a plane that is generally parallel to a plane defined by the opposite end (26) of said core (22). An armature (14) as set forth in claim 1 and further characterized in that each of said slots (30) is channel shaped and includes a channel bottom surface (34), and channel side walls (36) transversely extending from said channel bottom surface (34), wherein said channel bottom surfaces (34) collectively define an inner cylindrical surface (38) of said core (22), wherein adjacent sidewalls (36) of adjacent channels (30) define spokes (40) extending radially outwardly from said inner cylindrical surface (38), wherein said armature core (22) defines, on each spoke (40), an arcuate portion (42) of said outer cylindrical surface (28), wherein adjacent arcuate portions (42) define opposed ribs (46) that each define a portion of, and that together partially close, the channel (30) that said arcuate portions (42) are commonly adjacent to, wherein said insulator means (52) has a shape generally corresponding to the shape of the channel (30) in which said insulator means (52) is mounted, wherein said insulator means (52) comprises opposed sides, each of the opposed sides being in close contact with one of the sidewalls of said channel (30) in which said insulator means (52) is mounted, a bite portion (100) transverse to each of said opposed sides and connecting said opposed sides, said bite portion (100) being in close contact with said channel bottom surface (34) of said channel (30) in which said insulator means (52) is mounted, and an inwardly extending flange (102) extending from each of said opposed sides, each of said inwardly extending flanges being in close contact with one of the opposed ribs (46) that partially define said channel (30) in which said insulator (52) is mounted, and wherein said tab means (58) extends from said bite portion (100) of said insulator means (52).

Inventors: CUMMINGS DAVID H, CUMMINGS, DAVID H.
Applicants: MILWAUKEE ELECTRIC TOOL CORP, MILWAUKEE ELECTRIC TOOL CORPORATION
Application year: 1991
Main classification: H02K3
IPC codes: H02K3