WO2000046903A1

WO2000046903A1 - Stator coil winding with start wire protection

Info

Publication number: WO2000046903A1
Application number: PCT/US2000/002846
Authority: WO
Inventors: Lawrence E. Newman
Original assignee: Globe Products Inc.
Priority date: 1999-02-03
Filing date: 2000-02-03
Publication date: 2000-08-10

Abstract

Abrasion of the start wire segment SW at the front end of a stator core (40) resulting from the start wire SW being scraped or abraded by the wire segments that form the subsequently wound turns of a stator coil (42), (44) is avoided by moving the start wire SW at the front end of the stator core (40) to a protected position in which the start wire SW is sufficiently remote from the paths taken by the wire segments that form subsequent turns of the stator coil (42), (44) that the start wire SW cannot be abraded by wire segments that form subsequently wound coil turns.

Description

STATOR COIL WINDING WITH START WIRE PROTECTION

BACKGROUND

1. Field of Invention This invention relates to a method and apparatus for stator coil winding with start wire protection. The invention is particularly intended for the manufacture of two-pole stators for universal electric motors. However, the invention may be useful for manufacturing other electrical devices, such as four pole stators.

2. Cross Reference to Related Applications

This application claims the benefit of U.S. Provisional Application No. 60/118,360, filed February 3, 1999.

3. Incorporation by Reference

The disclosure of United States Patent No. 5,090,108, granted Feb. 25, 1992 to Banner et al. is hereby incorporated by reference herein. 4. Prior Art and Other Considerations

A conventional method of winding stators includes the steps of locating a stator at a stator coil winding station with its center axis aligned with the longitudinal axis of a wire winding ram or shuttle. Upper and lower pairs of winding forms are clamped to the stator to be wound and held in position by upper and lower pairs of form retainer plates. The above mentioned Banner et al. Patent No. 5,090,108 discloses a stator coil winding station having upper and lower winding station tooling assemblies 86 and 88 which include pairs of winding form retaining blades or plates 74 and 76 used in conventional fashion to clamp winding forms in position to guide magnet wires exiting from the winding shuttle around pole pieces formed on the stator core. The stator coils are simultaneously wound on the pole pieces by repeated reciprocal and oscillatory movements of the winding shuttle along and about its longitudinal axis to draw wires from sources of wire under tension, which wires exit through wire-exit needles at the end of the shuttle. Before and during the winding procedure, the bitter ends of the wires projecting from the winding shuttle are clamped by devices known as "lead pulls" which grip the finish wires at the end of the winding of one stator, cut the wire segments between the finish wire and the shuttle so that the newly-wound stator can be moved away from the winding station, and retain their grip on the freshly cut ends of the wire segments exiting from the shuttle while the next unwound stator is moved into the winding station and at least during the initial part of the winding of the next stator. During the winding procedure, the wires exiting from the shuttle, guided by the winding forms, are wrapped around the stator pole pieces to form the stator coils as the shuttle repeatedly reciprocates through the bore of the stator and rotates adjacent each end of the stator.

The Banner et al. Patent No. 5,090,108 also shows upper and lower start wire placing assemblies 140 and 142 used to hold the start wires away from the pole pieces during the winding of the coils. Start wire placing assemblies are used when there is a need or preference that the start wires not be wound under the subsequently wound turns of the stator coils. In the embodiment shown in the Banner et al. Patent No. 5,090,108, each start wire placing assembly 140 and 142 includes a pair of start wire placing blades 144 and 146, one at each end of the stator, which are pivoted by operation of a single air actuator to move a start wire outwardly away from its associated pole piece.

It is not necessary that a single air actuator be used to drive the start wire placing blades at the opposite ends of the stator core. Other start wire placing assemblies have been used by which the two placing blades are separately driven by separate air actuators.

In operation, the placing blades are so located at the beginning of the winding operation that the start wires are extended outwardly of the placing blades when the winding shuttle first moves through the stator bore adjacent a side of the stator pole piece. When past the front face of the stator, the shuttle begins to rotate to carry the magnet wire across the front face of the pole piece. This also brings the start wires into engagement with the front placing blades. Operation of the shuttle is momentarily stopped at which time the placing blades are pivoted to move the start wires away from the pole pieces. Operation of the winding shuttle is then resumed and continues until the winding of the coils is completed. At the end of the winding operation, the start wire placing blades are moved away from the newly wound stator along with the form retaining blades, leaving behind loops in the start wires which are pulled out during subsequent manufacturing steps.

There are occasions in which, when a start wire is held away from its associated pole piece, the stretch or segment of wire extending from the start wire placing blade across the front end face of the pole piece can interfere with a desirable formation of the coil end turns extending along the front end of the stator. This occurs because that segment of wire may become quite taut because it extends across the front end of the stator in the area in which the end turns build up as the winding progresses. In some cases, this problem has been alleviated by lowering the pressure on the air cylinder which holds the placing blades away from the pole piece, thereby permitting the front placing blade to move toward the stator pole piece and reducing the tension on the segment of wire that extends from the start wire across the front of the stator. In other cases, this problem is alleviated by temporarily forming larger loops in the wire, as discussed in United States Patent No. 5,833,166, granted Nov. 10, 1998 to Newman.

A problem that can occur using the wire placing assemblies of the Banner et al. Patent No. 5,090,108 is that segments of the start wires at the front ends of the stators which are held by loop-forming hooks or fingers extend from those hooks or fingers in an essentially straight line path to the top of the winding form and over the path of the wire segments used to form subsequent turns of the coils. Because of the location of the start wire at the front end of the stator, the latter wire segments may scrape or abrade along the start wire and skive off parts of the insulating coating on the start wire, which can lead to early failure of the motors or other dynamoelectric machines incorporating the stators. This problem can occur even when special steps are taken, as described above, to reduce the tension on the start wire during the winding process. Accordingly, there is a need to prevent the abrasion of segments of start wires extending across the paths of the wire segments that form subsequently-wound turns of a stator coil. 5. Definitions The following terms used in the specification and claims are used in the senses indicated in this paragraph. The terms "upper," "lower," "vertical" and "horizontal" are used in a relative sense and not in an absolute sense. The term "front" in reference to a stator winding machine or a stator being wound is used to refer to the parts of the machine and the stator facing an observer standing in front of, or facing, the winding shuttle during a winding operation. The term "rear" is used in the opposite sense. Thus, for example, at the outset of a winding operation, the winding shuttle moves from behind the rear end of the stator to the front end of the stator to extend the start wire through the bore of the stator. As used herein, "start wires" are the segments of the magnet wires extending forwardly from the lead pulls through the bore of the stator and around the front winding form. The segment of wire that extends from the front start wire placing blade across the front of a stator pole piece is part of the start wire and is also referred herein to as the "first end turn."

SUMMARY The primary object of this invention is to provide a method and an apparatus for preventing the abrasion of the start wire segment at the front end of the stator core resulting from the start wire being scraped or abraded by the wire segments that form the subsequently wound turns of the stator core.

In accordance with this invention, the start wire at the front end of the stator is moved to a protected position in which the start wire is sufficiently remote from the paths taken by the wire segments that form subsequent turns of the stator coil that the start wire cannot be abraded by wire segments that form subsequently-wound coil turns.

Further in accordance with this invention, a start wire placing apparatus is provided that causes the start wire at the front end of a stator core to follow a path that partly encircles the path taken by the wire segments that form the subsequently-wound turns of the stator core so that the front end of the start wire is protected against abrasion during the subsequent winding of the stator.

Other objects and advantages will become apparent from the following description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary front elevational view of a stator coil winding machine including a lead placing apparatus in accordance with this invention. FIG. 1 also shows a fragmentary end view of a stator in position to be wound thereby.

FIG. 2 is a fragmentary, exploded, partly diagrammatic, perspective view of parts of the machine of FIG. 1, including the lead placing apparatus. FIG. 2 also shows a fragment of a stator in position to be wound.

FIG. 3 is an enlarged, exploded, fragmentary perspective view of a coil end turn-manipulating hook assembly of the machine of FIG. 1.

FIG. 4 is a fragmentary perspective view of a stator and parts of the stator winding machine and illustrating a first stage in the winding of the stator. FIGS. 5, 6 and 7 are each fragmentary exploded perspective views similar to FIG. 4 and illustrate successive steps in the winding of the stator in order to position a start wire in a protected position.

FIG. 8 is a fragmentary perspective view similar to FIGS. 4 through 1 of t e stator and parts ot the end turn-manipulating hook assembly after the stator core has been wound.

FIGS. 9 and 10 are enlarged, exploded, fragmentary perspective views similar to FIG. 3 and illustrate, in sequence, the steps of removing the start wire from the end turn-manipulating hook assembly.

FIG. 11 is a fragmentary perspective view similar to FIG. 8 of the stator and parts of the end turn-manipulating hook assembly at a time when the stator is being released from the winding machine after being fully wound.

FIG. 12 is a perspective view of the finished stator. DETAILED DESCRIPTION OF THE DRAWINGS With reference to FIGS. 1 and 2, this invention is shown in connection with the winding of a two-pole stator, generally designated 40, comprising a pair of field coils 42 and 44 (FIGS. 8,11 and 12), wound on pole pieces 45 of a laminated stator core 46. The end faces, designated 48, of the stator 40 are plastic end plates, either one or both may have terminal-receiving sockets (not shown) . Although not illustrated in the drawings, the stator 40 is supported by a suitable support or nest in a winding station, which is the station shown in FIGS. 1 and 2, with its center axis aligned with the longitudinal axis of a wire winding ram or shuttle 78 having wire exit needles 80. In this case, when an unwound stator arrives at the winding station, two pairs of winding forms 52 are assembled onto the stator, each winding form 52 being clamped to the stator by one of four form retainer plates or blades 74, only two of which can be seen in FIG. 2. The retainer plates or blades 74 are part of upper and lower winding station tooling assemblies, generally designated 86.

Here it may be observed that the stator 40 is essentially symmetrical about its horizontal axis and the lower tooling assembly (not shown) may essentially be a mirror image of the upper tooling assembly 86. To simplify the drawings and this description, only the upper portion of the stator 40 is illustrated as is only the upper tooling assemblies herein, it being well understood in the art that the upper and lower tooling assemblies 86 normally function simultaneously in the same manner. The manner in which the tooling assemblies are mounted to move with the form retainer blades may be the same as described in the Banner et al. '108 patent and is not further described herein. With reference to FIGS. 2, 3, 9 and 10, in accordance with this invention, the start wire SW placing assembly 140 includes, in addition to the wire placing blade 144, an end turn manipulating hook assembly, generally designated 200 comprising an end turn-engaging hook or finger assembly 202 mounted on a finger mounting plate 204 and comprising a bifurcated hook 206 having bifurcations that straddle a wire kicker 208 which has a depending wire-kicking leg 210 and movable by operation of an air actuator 212.

With reference also to FIGS. 4 through 10 in addition to FIGS. 1 and 2, the bifurcated hook 206 is lowered into a pocket 214 in the front winding form 52 by operation of a hook assembly air actuator 216. After a start wire SW is coursed over the top of the front winding form 52, as shown in FIGS. 4 and 5, the bifurcated hook 206 is raised, as shown in FIG. 6, by the cylinder 216 (FIGS. 1 and 2) to pull the first end turn radially outwardly from the horizontal center axis of the stator core. Thereafter, as shown in FIG. 7, the placing blade 144 and the entire start wire SW placing assembly 140 are moved to the side so that the front end of the start wire SW partly encircles the path of the wire segments that form the completed stator coil. See FIGS. 8, 9, 10 and 12. After the winding of the coil is completed, the blade assembly air actuator 94 drives the form retaining blade 94 downwardly or inwardly through a short distance, typically about l/16th inch, to enable the winding forms to be removed in conventional fashion. The bifurcated hook 206 accordingly moves inwardly away from the start wire SW whereupon the start wire SW become slack. Thereafter, the kicker cylinder 212 is operated to move the kicker 208 to kick the wire off the bifurcated hook 206, as shown in FIG. 10. After the winding forms have been removed, the entire assembly 140 is then retracted as shown in FIG. 11 in the manner described in the Banner et al. '108 patent. While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various alterations in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for winding a stator coil around the upper pole piece of a stator core comprising the steps of forming a coil start wire segment across the front end of the pole piece, forming a wire loop from said start wire segment, which loop extends upwardly from the pole piece, and winding a stator coil around said pole piece beneath said wire loop to avoid abrading the start wire segment at the front end of a stator core resulting from the start wire segment being scraped or abraded by the wire segments that form the subsequently wound turns of the stator coil.

2. The method of claim 1 further comprising the step of the steps of pulling the start wire through the stator core to remove said loop after all of the turns of the stator coil have been wound.

3. A stator winding machine comprising a reciprocating and oscillating wire winding shuttle for winding a coil of wire around a stator pole piece, an end turn hook movable between a position in which the first end turn of a coil wound by said shuttle is placed over said hook to a raised position in which the first end turn is moved upwardly away from the center of said stator core, and a wire kicker for removing the first end turn from said hook after the winding of a coil around said pole piece is completed.

4. The stator winding machine of claim 3 further comprising a wire placing blade for moving one side of said first end turn away from said pole piece.

5. The stator winding machine of claim 3 wherein said hook is bifurcated and part of said kicker is located between the bifurcations thereof.