NZ523624A - Drawing the windings of a stator from a co-planar position into a cyclindrical position around the stator - Google Patents

Abstract

A method and apparatus for placing substantially cylindrical coil windings on the stator or rotor of a slot less motor or alternator. A single or multi phase winding in co-planar form is trapped at the inner periphery and drawn in to the gap between a stator and a form. As it is drawn in it is converted to a cylindrical winding. Co-planar winding may be trapped byt the pins on the turret and stator are pressed in to mould the winding is drawn in and converted to cylindrical form. It may be fixed in place on the stator before removing the completed winding.

Description

Patents Form # 5 52 3 6 2-4 NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION TITLE : Winding Method We, W ellington Drive T echnologies Limited Address: 13 William Pickering Drive, North Harbour, Auckland, New Zealand Nationality: A New Zealand company do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: PF05.JWP FEE CODE 1050 INTELLECTUAL PROPERTY OFFICE OF N.Z. 1 4 JAN 2003 RECEIVED WINDING METHOD FIELD OF THE INVENTION This invention relates to the production of windings for dynamoelectric machines. In particular, the invention relates to methods of providing windings on a stator of a 5 dynamoelectric machine.

BACKGROUND OF THE INVENTION For good electric motor efficiency, it is important that windings be accurately located on the motor stator. It is also important that the maximum possible proportion of the available winding space be filled with windings. Most existing motor designs, are either distributed 10 winding (slotless) or concentrated winding (salient pole) types, and rely on slots in the stator to locate the windings. However the slot shape for salient pole machines makes achieving a high slot fill difficult, and complex multi-stage winding machines are commonly used to achieve this.

For distributed winding machines, slots are generally formed by wire guides rather than the 15 shape of the stator backiron. The gaps between these are usually shallow, so insertion of windings is easier, but the wire guides, which serve no purpose other than locating the coils, take up space which could usefully be filled with windings. Elimination of these guides would thus allow more winding area, and hence improved motor efficiency.

Existing techniques exist for winding and placing coils using a two step process, whereby 20 coils are wound in a substantially planar configuration and then pressed into or around the stator. However these techniques rely upon slots in the stator to guide and locate the wires during insertion and thus are not ideal for slotless machines. An insertion technique which does not inherently require slots in the stator is described in GB2076710. However this technique pushes the coils into place rather than drawing them, and thus is only applicable to 25 windings having sufficient stiffness to maintain their shape without assistance, i.e. windings made of relatively heavy gauge wire.

OBJECT OF THE INVENTION It is an object of the present invention to provide an improved method of providing windings for dynamoelectric machines which will at least go some way toward overcoming 106676NZ_DPCS_898.doc//pc INTELLECiUAL PROPERTY"' OFFICE OF N.Z - 5 JAM 2004 RECEIVED disadvantages associated with known methods, or which will at least provide the public with a useful choice.

SUMMARY OF THE INVENTION Accordingly in one aspect the invention may broadly be said to consist in a method of 5 providing a winding on a rotor or stator of a dynamoelectric machine, method including the steps of providing winding material having at least one phase winding in a substantially co-planar configuration, and transforming the winding material to a substantially cylindrical configuration for provision about a surface of the stator or rotor by drawing it into place.

A method as described above, wherein the substantially co-planar configuration has a general inner peripheral boundary and a general outer peripheral boundary, and the method includes the step of moving the outer boundary both radially and axially relative to the inner boundary to provide the inner boundary and the outer boundary at substantially the same diameter so that 15 the winding material forms a substantially cylindrical configuration.

A method as described above, wherein the method includes the step of providing an inner boundary engagement means to engage with parts of the windings along or adjacent to the inner boundary of the winding material.

A method as described above wherein the method includes the step of providing a mould 20 having a hollow cylindrical surface and a corresponding cylindrical turret on which the engagement means are provided.

A method as described above wherein the method includes the step of providing a stator form and placing the form on a turret over the inner periphery of the winding material and over the engagement means whereby the inner periphery of the winding material is held in 25 place between the turret and form by the engagement means.

A method as described above, wherein the method further includes the steps of pressing the form into the mould to thereby draw the winding material into a gap between the outside of the stator form and the inside of the mould. 106676NZ_DPCS_898.doc//pc INTELLECjnML^PROpgf^iy " 5 JAN 2004 RECEIVED I A method as described above, wherein the form is pressed into the mould until the winding material forms a substantial cylinder about the stator form.

A method as described above, wherein the windings include thermobondable wire and a current is passed through the coils to bond the winding to the stator form.

A method as described above, wherein the stator form either comprises a part of the stator or a rotor, or simply comprises a substantially cylindrical member which may be used to merely support the winding material. In this way the free standing form that is produced may be applied to a stator or a rotor or may simply have backiron wrapped around it to be used as an external stator of an internal rotor machine.

In a further aspect the invention may broadly be said to consist in a rotor or stator for a dynamoelectric machine, the rotor or stator having windings provided on a surface of the rotor or stator in accordance with the method of the invention.

DRAWING DESCRIPTION An example of an embodiment of the invention will be described with reference to the drawings in which Figure 1 shows diagrammatic cross sections and plan views of a plunger, main mould and turret for use in accordance with the invention Figure 2 is a section and planned view of the components of figure 1 assembled ready for use with windings Figure 3 is a diagrammatic cross section of the windings being introduced to the mould Figure 4 is a diagrammatic cross section showing the windings partially pressed into the mould Figure 5 is a diagrammatic cross section showing the windings fully pressed within the 25 mould including a lower face plunger Figure 6 shows a diagrammatic cross section as shown in figure 5 with the lower face plunger at a full extent of travel. 106676NZ_DPCS_898.doc//pc 'NrcLLECTUAL PROPERTY j OFPICE OF M.z ' - 5 JAN 2004 Figure 7 is a plan view of one version of a completed stator Figure 8 is a diagrammatic cross-section of the stator of figure 7 along line A-A Figure 9 is a detail of the corner of the stator of figure 8 DESCRIPTION OF PREFERRED EMBODIMENT Referring to figure 1, a main mould 1 is shown. It is substantially cylindrical in form and is lined with a low friction material such as mylar or PTFE. Also shown in figure 1 is a turret generally referenced 2 having a number of pins 4 which are located at the top of the turret. Each pin 4 is biased either directly or indirectly into the upright position as shown in the figure so that the pin protrudes upwardly away from the body of the turret. The preferred 10 biasing arrangement is the use of springs 6.

Also shown in figure 1 is a face pressing plunger 8 which has an outside dimension that can be accommodated within the mould 1.

Turning now to figure 2, the mould 1 and turret 2 are shown located together, the turret being provided within another part of the mould 1. The turret is biased into position near the top of 15 mould 1 by springs 10. Immediately above the turret is a stator form for a dynamoelectric machine. The stator is generally referenced 12. It will be appreciated that although item 12 is referred to as being a stator, it could be another part of a dynamoelectric machine such as a rotor, or this item could simply provide a cylinder for forming windings rather than comprising a stator in itself. Therefore, item 12 may need further material apart from 20 windings attached to it to form a true stator or rotor of a dynamoelectric machine.

As can be seen in figure 2, there is an arrangement of windings generally referenced 14 provided in an annular form having a general outer peripheral boundary 16 and inner peripheral boundary 18. The windings comprise prewound phase strings which are ready for placement about an appropriate former such as the stator form 12. The windings 14 are 25 arranged so that the innermost point of each coil (these points for each coil together forming the inner boundary 18) is looped over one of the pins 4. Therefore, the number of pins 4 corresponds to the number of wire guides or slots in a more conventional motor (which equals the number of phases multiplied by the number of poles). 106676NZDPCS898,doc//pc ,NTEL^|CTUaTpropeRty" office of M.Z - 5 JAN 2004 RECEIVED The winding coils are placed on the stator as follows. Firstly, the windings are placed in a series of generally rectangular coils in a "star" pattern, upon the horizontal top of the mould. The inner corners of each coil are hooked over the pins 4 as mentioned above. It will be seen that other coil shapes could be adopted.

The coils are prewound in strings on a bobbin type winding machine and placed in a star pattern, or alternatively may be directly wound into the star pattern. Adaptations of existing stator coil "fall winding" machines are suitable for this purpose. It will be appreciated that other methods may also be used.

Turning now to figure 3, the stator form 12 has now been pressed down onto the pins 4. The 10 spring force holding the turret in the mould is higher than the sum of the spring forces on the retractable pins, so that the retractable pins are initially pushed down as shown in figure 3 without any substantial movement of the turret. This traps the inner ends of the coils between the pins, stator and turret as the pins retract.

Turning to figure 4, it will be seen that the stator is now pressed down further into the mould. 15 As the stator continues to be pressed down, the coils are drawn into the gap between the outside of the stator and the inside of the mould.

In figure 5, the stator has been fully pressed into the mould, and the windings now form a substantial cylinder about the outside of the stator form. As can be seen, when the stator is nearly pushed home into the mould, the upper ends (i.e. the "upper" end turns of the coils), 20 which were at the outer edges of the star pattern shown in figure 2, are unable to be pulled into the gap between the stator and the mould. This is because they cross over each other and are bulkier than the sides of the coils. Therefore, as the stator is pressed into the mould, the coils are stretched down the side of the stator and this pulls the coils straight.

The upper edge of the mould can be chamfered or otherwise shaped to promote neat forming 25 of the upper end turns of the windings.

As can be seen from figure 5, the face pressing plunger is now introduced to the bottom of the mould.

In figure 6, the plunger is shown being pressed up home into the base of the stator form. This presses the lower end turns, which are trapped behind the pins, into a controlled shape. 106676NZ_DPCS_898.doc//pc JAN 2004 RPOCrM /I— INTELLECTUAL PROPERTY OFPICE OF N.Z - 5 JAM 2004 RECEIVED Once the stator has been fully pressed home, the windings (provided thermobondable wire has been used) can be set off by passing a current through the coils. After a period of cooling, which is short due to good thermal contact between the windings and the mould, the finished stator can be removed from the mould.

It will be appreciated that the stator form 12 shown in the drawings will typically have backiron and insulation provided on it.

It will further be appreciated that in instances where accurate forming of the end turns is not required, the pins 4 may be fixed to the turret rather than retractable.

It will further be appreciated that the pins, whether retractable or not, may alternatively be 10 placed on the plunger or stator form rather than the turret. If the pins need not be retractable, the turret may then be completely eliminated.

It will further be appreciated that the windings before pressing, though shown here as a set of coils laid out in a star pattern, may alternatively be formed in any generally annular shape which allows the inner part of the annulus to be hooked over the pins A variation of this technique is to use wire which is not thermobondable, and to fix the wires in place with epoxy while still in the mould. For rapid production the section of the mould which is in contact with the finished stator may be removable from the machine, so that the epoxy pouring and setting may happen while further stators are being formed.

A further variation is to replace the stator with a plunger coated with PTFE or another low 20 friction material. After forming the windings as in the method above, it will be seen that it is possible to remove the plunger from the windings, to form an electrical free-standing "self supporting" winding. This self supporting winding can then have backiron wrapped around the outside of it and be used as the external stator of an internal rotor dynamoelectric machine. Alternatively the backiron may be pre-wound and placed either in the mould (for 25 an internal rotor machine) or around the plunger (for an external rotor machine), along with a layer of insulating material, before pressing. The winding thus conforms closely to the backiron after pressing , and may be removed after setting off as a single assembly.

Still a further variation as shown in figure 7 is to place in the mould (for external rotor machines) or on the plunger (for internal rotor machines) a stator lining of a non-conductive 30 material (typically a polymer). Upon pressing the winding, the winding is contained 106676N Z_DPCS_898.doc//pc between the stator and stator insulation, and thus does not require bonding or epoxy to retain its form. A stator for an internal rotor machine, constructed using this method, is shown in figures 7, 8 and 9 where windings 14 are drawn between a backiron 90 with insulation 91 and a stator liner 92.

It will be seen that the invention provides improved method of placing coils on a distributed winding type stator (and possibly with other stator or rotor arrangements) so as to eliminate the need for wire guides, while still providing central placement accuracy, rapid operation and very efficient area utilisation.

INTELLECTUAL PROPERTY OFRCP OF M.Z - 5 JAM 2004 RECEIVED 106676NZJDPCS_898.doc//pc

Claims (10)

WHAT WE CLAIM IS:

1. A method of providing a winding for a slotless rotor or stator of a dynamoelectric machine, including the steps of providing a winding material having at least one phase winding in a substantially co-planar configuration, and 5 transforming the winding material to a substantially continuous cylindrical configuration for provision about a surface of the stator or rotor by drawing it into place.

2. A method as described as claimed in claim 1, wherein the substantially co-planar configuration has a general inner peripheral boundary and a general outer peripheral 10 boundary, and the method includes the step of moving the outer boundary both radially and axially relative to the inner boundary to provide the inner boundary and the outer boundary at substantially the same diameter so that the winding material forms a substantially cylindrical configuration.

3. A method as claimed in claim 2, wherein the method includes the step of providing 15 an inner boundary engagement means to engage with parts of the windings along or adjacent to the inner boundary of the winding material.

4. A method as described in claim 2 wherein the method includes the step of providing a mould having a hollow cylindrical surface and a corresponding cylindrical turret on which the engagement means are provided. 20

5. A method as described in claim 2 wherein the method includes the step of providing a stator form and placing the form on a turret over the inner periphery of the winding material and over the engagement means whereby the inner periphery of the winding material is held in place between the turret and form by the engagement means.

6. A method as claimed in Claim 5, wherein the method further includes the steps of 25 pressing the form into the mould to thereby draw the winding material into a gap between the outside of the stator form and the inside of the mould.

7. A method as claimed in Claim 6, wherein the form is pressed into the mould until the winding material forms a substantial cylinder about the stator form. INIELLECTIJAL p. 106676NZ_DPCS_898.doc//pc ACPin,- .'ROPERTY OFFICE OF N.Z - 5 JAN 2004 RECEIVED - 10-

8. A method as claimed in Claim 1, wherein the winding includes thermobondable wire and a current is passed through the coils to bond the winding to the stator form.

9. A method as claimed in Claim 5, wherein the stator form either comprises a part of the stator or a rotor, or comprises a substantially cylindrical member which may be 5 used to support the winding material for transfer to a rotor or stator.

10. A slotless rotor or stator for a dynamoelectric machine, the rotor or stator having windings provided on a surface of the rotor or stator by drawing a co-planar winding into place on the rotor or stator as a substantially cylindrical winding. 10 PIPERS Attorneys for Wellington Drive Technologies Ltd 106676NZ_DPCS_898.doc//pc INTELLcOiUAL PROPERTY OFFICE OF N2 - 5 JAN 2004 RECEIVED -11 - ABSTRACT A method and apparatus for placing substantially cylindrical coil windings on the stator or rotor of a slotless motor or alternator. A single or multi-phase winding in co-planar form is trapped at the inner periphery and drawn into the gap between, typically, a stator and a form. 5 As it is drawn in it is converted to a cylindrical winding. Co-planar winding 14 may be trapped by pins 4 on turret 6 at each winding pole point and as turret 6 and stator 12 are pressed into mould 1 the winding is drawn in and converted to a cylindrical form. It may be fixed in place on the stator before removing the completed winding. 10 IN I ELLCU>Uml r nwPtRTY OFRCE OF N.Z - 5 JAN 2004 RECEIVED 106676NZDPCS898 .doc//pc