AU665027B2 - Inductive component manufacture - Google Patents

Description

5027S F Ref: 222554 S F Ref: 222554

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Trestoto Pty Limited Lot 120 Aylmerton Road Aylmerton New South Wales 2575

AUSTRALIA

Donat Witold Majewski Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Inductive Component Manufacture I I 9 o 0 I009q ASSOCIATED PROVISIONAL APPLICATION DETAILS [31] Application No(s) [33] Country PK8836 AU [32] Application Date 10 October 1991 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815/3 1, -2- Inductive Component Manufacture Field of the Invention The present invention relates to inductive components, and in particular, to the final assembly of such inductive components.

Although the present invention will be described in relation to transformers, the invention is also applicable to inductive components such as ballasts.

Description of the Prior Art During the assembly of inductive components, such as transformers, it is necessary to correctly locate the pre-wound coil (which may include one or more windings) relative to the magnetic core, which is formed from a stack of suitably shaped laminations. Typically the laminations are in the shape of an E and an I, however, other Slamination configurations are well known.

Prior to finalisation of the assembly procedure, it is necessary that the stack of laminations be compressed to a maximum extent possible. This, for example, reduces hum which tends to occur by magnetically induced vibration, and also reduces heat losses which 1would otherwise occur through poor magnetic coupling between laminations.

oa Hitherto various methods have been used to clamp the stack of laminations together and, when necessary, a packer has been slid oo~ i relative to the coil so as to achieve the final desired compression of i ,tne stack. Generally such arrangements have taken the form of parallel 25 sided packing shims of various thicknesses. Because the number and/or V thickness of laminations in a stack can vary, and because the coil winding tension can vary, the thickness of packing required in general varies from one component to another. As a result, the packing step Is different for each component as a different number of, or thicknesses t 30 of, shims must be selected.

The object of the present invention is to provide a simple and effec'cive double wedge means of compressing the stack of laminations.

Summary of the Invention In accordance with one aspect of the present invention there is provided a method of tightening laminations of a stack of laminations BFD/63K R 3 of an inductive component including at least one coil winding prior to final assembly of the inductive component, said method comprising the steps of: inserting at least one pair of wedges between said coil winding and said stack, one wedge of each of said pair of wedges having a substantialy flat face which is engaged with said coil, the other wedge 1 of said pair of wedges having a substantially flat face which is h engaged with said stack, the inclined faces of said wedges being abutted, and moving said other wedge relative to said stack to force said flat faces apart and to thereby compress said stack.

In accordance with another aspect of the present invention there is provided a pair of wedges for tightening lanminations of a stack of laminations of an inductive component including at least one coil winding, each of which said wedges has a substantially flat face and a substantially inclined face, one of said wedges being provided with a lip on the substantially flat face, and whereby, in use, said pair of wedges are inserted between said coil winding and said stack, and said lip engages said at least one coil winding, and further whereby movement of one wedge relative to the other wedge increases the spacing between the opposed flat faces to compress the stack of laminations, and whereby both of said wedges have ratchet means to retain same i" against further movement.

1: *d

I.I

I

I I and r 3A In accordance with yet a further aspect of the invention there is provided an inductive component comprising a stack of two part laminations; at least one winding located, in part, in a window of the said stack of laminations; and a pair of wedges, each one of which has a substantially flat face and a substantially inclined face, the pair of wedges being located in a gap between the stack of laminations and the winding, with the flat face of one of wedges abutting the winding and the flat face of the other of the wedges abutting at least a portion of both of the parts of said two part laminations, and whereby movement of one wedge relative to the other wedge increases the spacing between the opposed flat faces to compress the stack of laminations, the pair of wedges further having ratchet means which retain the wedges against further movement.

Brief Description of the Drawings Embodiments of the present invention will now be described with reference to the drawi'ngs, in which: Fig. 1 is a perspective view of a first wedge of the preferred embodiment; Fig. 2 is a perspective view of the second wedge of the preferred Iembodiment; Fig. 3 is a perspective view showing how the first and second wedges are engaged and abutted; and

I

*I

4

C

L

:I

Fig. 4 is a perspective view of an assembled transformer having two pairs of wedges as in Fig. 3 inserted between the stack of laminations and the coil or winding(s).

I Description of Preferred Embodiments As seen in Fig. 1, the first wedge 1 has a flat rear face 2 and i an inclined front face 3 which has a series of spaced apart grooves 4 extending thereacross. The wedge 1 also has a top 5 and a bottom 6.

As seen in Fig. 2, the second wedge 11 has a flat rear face 12 Sand an inclined front face 13 which is provided with a series of ridges 14 extending thereacross. The second wedge 11 has a top 15 and a bottom 16. The inclined front face 13 is located between a pair of Iside walls 17 which are dimensioned to receive the first wedge 1.

Fig. 3 illustrates the first and second wedges 1 and 11 engaged i with their respective front faces and 3,13 abutted. It will be apparent to those skilled in the art that relative movement of the first and second wedges 1,11 towards each other increases the spacing between the oppositely facing rear faces 2,12. The grooves 4 and i ridges 14 are a preferment and enable a ratchet-like action to be achieved by interengagement of one or more of the ridges 14 with the grooves 4. If the coefficient of friction of the material from which the wedges 1,11 are made is sufficiently high, the grooves 4 and ridges i: 14 can be dispensed with.

As also seen in Figs. 2 and 3, the second wedge 11 has a lip 19 which extends away from the flat rear face 12. A function of the lip 25 is to enable the second wedge 11 to sit on a coil prior to engagement of the pair of wedges 1,11. Another function of the lip can be to securely clamp the start lead of the winding.

Turning now to Fig. 4, a transformer 20 is illustrated having a £i stack 21 of laminations formed from I-laminations 22 and E-laminations i *jt- BFD/63K r I r 5 23. In conventional fashion between the arms of the E-laminations are located two winding windows 24 within which a substantially conventional O-shaped coil or winding 25 is located.

As seen in Fig. 4 between opposite faces of the stack 21 and between the ends of the coil 25 is located one pair of two pairs of wedges 1, 11. The wedges are so arranged so as to compress the stack 21.

During the assembly procedure, the requisite number of E-laminations are assembled thereby forming the winding windows 24. Then the pre-wound coil 25 is located within the winding windows 24. Next the requisite number of I-laminations 22 is placed across the arms of the E-laminations 23.

Next two of the second wedges 11 are positioned so that the flat face 12 thereon abuts the interior surface of the coil 25. The lip 19 of each of the second wedges 11 abuts the upper surface of the coil 25 and one of the second wedges can be positioned so that it also holds the starting wire of the coil 25, illustrated schematically at 26, in its intended position.

Next two of the first wedges 1 are each placed relative to the second wedges 11 in the manner illustrated in Figs. 3 and 4 with the bottom 6 of the first wedges 1 passing beyond the tops 15 of the second wedges 11. The first wedges 1 are then driven home by means of a hammer, or like implement or a press, forcing the tops 5 so as to drive the wedges 1 into the configuration illustrated in Fig. 3. Because of the movement of the wedge 1 expands the distance between the flat rear .surfaces 2, 12, the stack 21 is compressed. Moreover, only the first wedges 1 move so there is no scraping motion to disturb the interior insulation of the coil Preferably the outer ends of the I-laminations 22 are welded to the outer arms of the E-laminations once the wedges 1 are driven home. No Srivets are required. It will be apparent to those skilled in the art Sthat the wedges 1, 11 hold the centre arm of the E-laminations and the central portion of the I-lamination against any flapping or rattling motion. Secure clamping of the laminations is particularly important In inductive components (such as ballasts) having an airgap In their magnetic path because the magnetic forces on the laminations in the region of the airgap are extremely high.

In addition, because the spacing between the flat outer faces 2, 12 I I 'A is adjustable with the degree of penetration of the wedge 1, the system automatically adjusts for differences in size caused by different numbers of either or both laminations, and different coil tensions. This makes the assembly of all components substantially the same. If large tolerances are experienced wedges 1 of different sizes can be used. The system holds the stack and coil securely in place prior to varnishing of the entire unit.

i The foregoing describes only one embodiment of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention, for example, the second wedge 11 could be an integral part of a moulded bobbin onto which the winding of the inductive component is wound.

oE Another example would be to have a termination assembly (eg a terminal block) being an integral part of or being attached to the second wedge 11.

0 0 049 oo 0 0

I

9 i. .Li 1

Claims (12)

1. A method of tightening laminations of a stack oi laminations of an inductive component including at least one coil winding prior to final assembly of the inductive component, said method comprising the steps of: inserting at least one pair of wedges between said coil winding and said stack, one wedge of each of said pair of wedges having a substantially flat face which is engaged with said coil, the other wedge of said pair of wedges having a substantially flat face which is engaged with said stack, the inclined faces of said wedges being abutted; and moving said other wedge relative to said stack to force said flat faces apart and to thereby compress said stack.

2. A method as claimed in claim 1 wherein there are two pairs of wedges, and the step of moving comprises moving said other wedge of a first pair relative to said stack to force the flat faces of the first pair apart and thereby partially compress said stack, then moving said other wedge of the second pair relative to said stack to force the flat faces of the second pair apart andi thereby complete compression of the stack. s

3. A method as claimed in either one of claim 1 or claim 2, wherein the said one wedge of the one or each pair having the flat face which engages the coil is provided with a lip, and the step of inserting comprises inserting the one or each wedge having the lip such that the ,ip engages and is supported by the coil, and then inserting S26 the said other wedge of the one or each pair. i

4. A method as claimed in claim 3, comprising the further step of placing a starting wire of said coil under the said lip following the inserting step to securely clamp the starting wire after the moving step, A

5, A pair of wedges for tightening laminations of a stack of laminations 4 of an inductive component including at least one coil winding, each of which said wedges has a substantially flat face and a substantially inclined face, one of said wedges being provided with a lip on the substantially flat face, and whereby, in use, said pair of wedges are inserted between said coil winding and said stack, and said lip engages said at least one coil winding, and further whereby movement of one wedge relative to the other wedge increases the spacing between the opposed flat faces to compress the INlibklOOt 33dD -8- stack of laminations, and whereby both of said wedges have ratchet means to retain same against further movement.

6. A pair of wedges as claimed in claim 5, wherein the said ratchet means comprises a series of laterally extending grooves substantially equally spaced along the inclined face of a one of the pair of wedges, and one or more substantially identically spaced laterally extending ridges on the inclined face of the other one of the pair of wedges.

7. A pair of wedges as claimed in claim 6, wherein the one of the pair of wedges having the ridge(s) has a pair of side walls which define the sides of a channel in which the other one of the said pair of wedges can slide during engagement of the grooves and ridges, and which side walls restrain the other one of the pair of wedges from lateral motion.

8. An inductive component comprising a stack of two part laminations; at least one winding located, in part, in a window of the said stack of laminations; and a pair of wedges, each one of which has a substantially flat face and a 20 substantially inclined face, the pair of wedges being located in a gap between the stack S: of laminations and the winding, with the flat face of one of wedges abutting the winding and the flat face of the other of the wedges abutting at least a portion of both of the parts of said two part laminations, and whereby movement of one wedge relative to the other wedge increases the spacing between the opposed flat faces to compress the stack 26 of laminations, the pair of wedges further having ratchet means which retain the wedges against further movement.

9, An inductive component as claimed in claim 8, wherein there are two gaps between the coil and the stack of laminations the gaps being at opposed sides of the stack of laminations, and one pair of the said wedges is located in each of the said two opposed gaps.

A method of tightening lamination stacks substantially as herein described and as illustrated in the accompanying drawings.

11, A pair of wedges substantially as herein described and as illustrated in Figs. 1 to 3 of the accompanying drawings and suitable for use in tightening IN\IIbk|O1 33:OFD I- r -9- laminations of a stack of laminations as herein described and illustrated in Fig. 4 of the accompanying drawings.

12. An inductive component substantially as herein described and as illustrated in the accompanying drawings. DATED this Twelfth Day of October 1995 Trestoto Pty Limited Patent Attorneys for the Applicant SPRUSON FERGUSON 4 d 1 I1 N:\llbk)001 33:BFD M