GB2176941A

GB2176941A - Coil winding method

Info

Publication number: GB2176941A
Application number: GB08612194A
Authority: GB
Inventors: Frank Mclean Logie
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1985-06-18
Filing date: 1986-05-20
Publication date: 1987-01-07
Also published as: GB8515352D0; ES556148A0; IT8620619A1; GB8612194D0; FR2583566B1; IT8620619A0; GB2176941B; DE3620327A1; JPS61293138A; ES8800499A1; FR2583566A1; US4677743A; IT1190030B

Description

1 GB 2 176 941 A 1

SPECIFICATION

Winding method This invention relates to a method of winding the coils of a stator structure of an electromagnetic device of the kind in which the stator structure is of cylindrical form and defines a plurality of axially spaced circumferential pole pieces, adjacent pole pieces defining a groove therebetween, the coils being located in the grooves respectively and in use being supplied with electric current byway of a pair of supplyterminals at one end of the stator structure.

A device of the aforesaid kind is described in British specification 2036453. As described the coils are connected in series and the winding of all the coils can be achieved using a single length of wire. In this case since the electrical connections are to be made to terminals at one end of the stator structure longitu- dinal slots are formed in the pole pieces, the slots accommodating the interconnections between adjacent coils. The coils are wound in turn with thewindIng direction of one coil being opposite to that of the adjacent coil or coils so that adjacent pole pieces assume opposite magnetic polarity.

In some instances it is required thatthe coils should be connected in parallel. In this case thefurthestcoil from theterminals will be wound firstfollowed bythe adjacent coil and so on. In this casethe aforesaid slots will extend into a slotformed in the base walls of the grooves which is wide enough ordeep enough to accommodate the end connections of each coil, the coils can bewound in the same or in the opposite direction, providing the end turns are connected cor- rectlyto the terminals.

An electromagnetic device of the aforesaid type has been devised and is shown in British specification 2140214A in which the end coils of the stator structure have approximately half the number of turns of the intermediate coils. In the case where all the coils are conected in series, the winding of the stator structure can be achieved in the same manner as described. In the case howeverwhere the coils are connected in parallel across the supply terminals, the two end coils must be connected in series with each other before being connected to the supplyterminals and this poses problems since the winding of the coils musttake place in sequence. In another case where a series/parallel connection system has to be employed the two end coils are again connected in series with each other and with one or more of the intermediate coils across the supply terminals with the remaining intermediate coils connected in one or more series combination across the supply terminals.

The object of the invention is to provide a method of winding the coils of a stator structure of the aforesaid type and in which the end coils of the stator structure are connected in series with each other.

According to the invention a method of winding a stator structure of the kind specified in which the end coils have a reduced number of turns and are connected in series with each other, comprises providing a dummy connector terminal at said one end of the stator structure, connecting the wire to be used in winding the coils to said dummy con nectorterminal, laying the wire in a slot extending along the stator structure, winding the end coil furtherfrom said one end of the stator structure and returning the wire to one of the supply terminals, directly or byway of an intermediate coil, winding the remaining intermediate coils starting with the one further from said one end of the stator structure and winding the end coil at or nearest said one end of the stator structure, one end of said end coil being connected to said dummy connector term ina 1.

The winding method in accordance with the invention will now be described with reference to the accompanying drawings in which:- Figure 1 is a sectional side elevation of one exam- pie of an electromagnetic device the coils of which can be wound utilising the method of the invention, Figure2 shows one winding sequence for use when the electromagnetic device has an odd number of coils, Figure3 is a diagram similarto Figure 2 butshowing thewinding sequence when the device has an even number of coils, Figures4and 5show alternative winding sequences for a device, and Figure 6shows anotherwinding sequencefor a device employing series/parallel connections.

Referring to Figure 1 of the drawings the electromagnetic device comprises a stator structure 20 which is of generally cylindrical form and which defines a plurality of intermediate axially spaced annular pole pieces 21. The pole pieces 21 increase in diameter towards one end of the stator structure and between them define a groove. The stator structure also includes a pair of end pole pieces 23 between which and the adjacent pole piece 21 are defined a further pair of grooves. The groove or grooves defined between adjacent pole pieces 21 are provided with coils 24 and the grooves defined between the pole pieces 23 and the pole pieces 21 accommodate coils 25 respectively.

The electromagnetic device also includes an armature 22 which is of stepped form and which defines surfaces 22Awhich extend in a radial direction and which are presented to the side surfaces of the pole pieces 21. The armature also has plain cylindrical portions between which and the pole pieces 23, are formed radial air gaps. When current flows in the coil 24, the adjacent pole pieces 21 assume opposite magnetic polarity and an attraction force will be de- veloped tending to move the armature axially. The coils 25 also contribute to the fluxflowing in the adjacent pole piece 21, the return of the flux generated bythe coils 25 being by way of the pole pieces 23. The version of the device shown in Figure 1 isthe simplestform of the device and has only two pole pieces 21 and therefore one coil 24. A more complex device would have a greater number of pole pieces 21 with the armature defining complementary pole faces 22A butthe stator structure would have only two pole pieces 23. The number of turns of the coils 25 is substantially half the number of turns of the coil or coils 24 and if the coils are connected in series, there is no diff iculty in winding the stator structure.

In some instances it is preferable to connectthe coils in parallel butthe end coils must be connected in 2 GB 2 176 941 A 2 series in view of the reduced number of turns.

Referring to Figure 2 this shows a winding diagram of a device having three coils 24 and of course two coils 25. The problem with winding such a device with a continuous length of wire, is arranging forthe series connection between the coils 25. The supply termin als 26,27 are situated atone end of the stator struc ture and in order to assist the winding a dummy connectortermina128 is provided at the same end of the stator structure, it being appreciated that the ter minals 26,27 and 28 are insulated from the stator structure and from each other.

Figure 2 shows the winding route of an electro magnetic devicewhich has an odd number of coils and the winding starts byfirstwrapping an end of the wire around the dummy connector terminal 28. The wire is then laid in a slot 20Awhich extends axially in the stator structure and the winding of the coil 25 furthestfrom the one end of the stator structuretakes place. The starts and finishes of the coils are indicated 85 in the diagram bythe letters S and F respectively and the letters CW below each coil indicate one direction of winding, the letters ACW in Figure 3 indicating the opposite direction of winding. When the winding of the coil 25 furthestfrom the one end of the stator structure is completed, the wire is returned to the supply terminal 26 and it is then returned along the slotto permitthe next adjacent coil 24to bewound.

The end of this coil is returned to the supplyterminal 27 and the winding of the enxt adjacent coil 24then takes place. This procedure is repeated until the coils 24 have been wound, the end of the last coil 24 being returned to the supply terminal 27 and then returned along the slotto permitwinding of the coil 25 nearest the one end of the stator structure. The end of this coil 100 is returned to the dummy connector terminal 28. Us ing the aforesaid winding route all the coils are wound in the same direction but when current is supplied to the supply terminals 26,27 the current floyv in adjacent coils is opposite so that adjacent pole 105 pieces assume opposite magnetic polarity and the device can function as described. Itwill be seen that the dummy connector terminal 28 serves as an anchor point in the series connection between the two end coils and it enables the winding of the stator structure to be effected using a single length of wire.

Turning nowto Figure 3, there is shown the wind ing routefor an electromagnetic device having an even number of coils and the initial winding method is as described with reference to Figure 2. When com pleting the winding of the last coil 24thewire is returned to the supply terminal 26 but since the coil 25 must have its end connected to the terminal 27, the wire is then taken around theterminal 27 and the coil 25 nearestto the one end of the stator structure is then wound. The direction of winding however must be reversed. The end of this coil is taken to the dum my connector terminal 28 and the direct connection between the terminals 26 and 27 is severed as indi cated at 29. When the supplyterminals of the device wound as described with reference to Figure 3, are connected to a source of supply, adjacent pole pieces again assume opposite magnetic polarity and the devicefunctions as described.

In some examples of the device it is not necessary to ensure that adjacent pole pieces haveopposite magnetic polarityand in this case the winding routes shown in Figures4and 5 are adopted. The winding routeshown in Figure 4 corresponds to that of Figure 2with changes in thedirection ofwinding of adjacent coils and the winding routeshown in Figure 5correspondstothatof Figure3 again with appropriate changes in the direction of winding of some of the coils.

In the example shown in Figure 6 a series/parallel connection is employed. Thetwo end coils 25 are connected in series with one of the intermediate coils 24 across the supply terminals 26,27 and the two remaining intermediate coils 24 are also connected in series across the supply terminals. The use of the series/parallel connection maybe dictated bythe supply voltage and wire size.

Using the winding routes described the coils of the stator structure can be wound using a single length of wire.

Claims

1. A method of winding the coils of a stator struc- ture of an electromagnetic device of the kind in which the stator structure is of cylindrical form and defines a plurality of axially spaced circumferential pole pieces, adjacent pole pieces defining a groove therebetween, the coils being located in the grooves respectively and connected to a pair of electric supply terminals at one end of the stator structure, the end coils having a reduced number of turns and being connected in series with each other, the method comprising providing a dummy connector terminal at said one end of the stator structure, connecting the wire to be used in winding the coils to said dummy connector terminal, laying the wire in a slot extending along the stator structure, winding the end coil furtherfrom said one end of the stator structure and returning the wire to one of the supply terminals directly or byway of an intermediate coil, winding the remaining intermediate coils starting with the one furtherfrom said one end of the stator structure and winding the end coil at or nearest said one end of the stator structure, one end of said end coil being connected to said dummy connector terminal.

2. A method according to Claim 1 in which the stator structure carries an even number of coils and priorto winding the end coil adjacent said one end of the stator structure the wire is looped around the supply terminals, the portion of the wire connecting said supply terminals subsequently being severed.

3. A method of winding the coils of a stator structure substantially as hereinbefore described with re- ferenceto the accompanying drawings.

Printed in the U l(for HMSO, D8818935,11186,7102. Published by The Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies maybe obtained.