GB2568497A

GB2568497A - A transformer and a method of manufacturing a transformer

Info

Publication number: GB2568497A
Application number: GB1719031.5A
Authority: GB
Inventors: Phillips Stephen
Original assignee: INVERTEK DRIVES Ltd
Current assignee: INVERTEK DRIVES Ltd
Priority date: 2017-11-17
Filing date: 2017-11-17
Publication date: 2019-05-22
Also published as: GB201719031D0

Abstract

A transformer comprises a former 1 with spool body 2 around which at least one winding is provided; at least one holder 5a, 5b attached to, or formed integrally with, the spool 2; and at least one conductive pin array 13a, 13b which is detachably received in the at least one holder 5a, 5b. The spool may have a generally elongate body 2 with a hollow region which is open at two ends 3. First and second end plates 4 may be provided at respective ends of the spool body 2. The required holder, or holders 5a, 5b, may be attached to the respective end plates 4. Each pin array 13a, 13b may comprise a non-conductive block of plastic material with conductive pins attached to or passing through the said block. The at least one holder 5 and the at least one pin array 13 may include corresponding attachment features such as cooperating ribs 15 and grooves 8 or protrusions and apertures. The spool 2 may include a separation component to provide an electrically isolating barrier between the winding, or windings, on the spool or a magnetic core, and the at least one conductive pin array 13a, 13b. The separation component may be part of a holder 5a, 5b.

Description

Title: A Transformer and a Method of Manufacturing a Transformer

Description of Invention

The present invention relates to transformers.

An electrical transformer generally comprises a non-conductive former or bobbin, which is typically formed from plastic, and which has a spool having a hollow space passing through the centre of the spool. Primary and secondary windings are formed around the spool, each of which consists of a number of turns of an elongate conductor, with each of the turns being insulated from the other turns. In practice, the primary and secondary windings will typically comprise several turns or coils of a wire which has a central conductor surrounded by an insulating sheet.

A ferrite core is then positioned around the primary and secondary windings, and also passes through the hollow core of the spool. As the skilled reader will appreciate, the ferrite core may comprise two generally E-shaped pieces, which are fitted together to surround the primary and secondary windings, and to pass through the interior of the spool.

A transformer will typically be provided with a number of electrical contact pins, and the primary and secondary windings are electrically connected to the contact pins so that electrical power can be supplied to the primary windings, and conducted from the secondary windings.

A safety clearance is required between the low voltage contact pins and the high voltage windings, and also between the contact pins and the core (since the core might, in the event of failure, provide a conductive bridge between the contact pins and the windings). If an adequate safety distance is not provided then there is a risk that, in the event of a failure such as partial melting of the former, one or more of the contact pins may come into direct contact with the ferrite core or the windings, thus causing a short circuit event, which will prevent the transformer from working and may also produce a fire or shock hazard.

In conventional transformers, this safety distance is achieved by including relatively large parts of the former between the ferrite core and the contact pins. However, this increases the size, weight and cost of the transformer.

It is an object of the present invention to provide an improved transformer. Accordingly, one aspect of the present invention provides a former for a transformer, the former comprising: a former body comprising a spool around which at least one of the primary and secondary windings of the transformer can be formed; at least one holder which is attached to, or formed integrally with, the spool or another component of the former; and at least one pin array comprising one or more conductive pins, wherein the pin array may be removably received in the at least one holder.

Advantageously, the former comprises first and second holders which are each attached to, or formed integrally with the spool, or with another component of the former, and first and second pin arrays which may be removably received in the respective holders.

Preferably, the spool body is generally elongate, having a hollow interior and two open ends.

Conveniently, the former comprises first and second end plates, provided at respective ends of the spool body.

Advantageously, the holders are attached to the respective end plates.

Preferably, the or each pin array comprises a block of a non-conductive material, with one or more conductive pins attached thereto or passing therethrough.

Conveniently, at least one pin array and the at least one holder have respective attachment features, allowing the pin array to be removably received and held by the holder.

Advantageously, the attachment features comprise cooperating ribs and grooves.

Preferably, the attachment features comprise cooperating protrusions and apertures.

Conveniently, the former comprises a separation component provided between the spool body and the location of the pin array when it is received and retained by the at least one holder, wherein the separation component protrudes outwardly with respect to the spool body further than any of the conductive pins of the at least one pin array, when the pin array is received and retained by the holder.

Advantageously, the separation component comprises part of the holder.

Another embodiment of the present invention provides a transformer comprising a former according to any of the above, and further comprising at least one winding wound around the spool body, and a core which protrudes at least partially into the hollow interior of the spool body, wherein at least one of the conductive pins of one of the pin arrays is conductively connected to the winding.

Preferably, a straight line connecting an outer edge of the core, and an outer point of any of the pins, will pass through the separation component or will lie closer to the centre of the spool body than the separation component.

Conveniently, a straight line connecting an outer edge of the winding, and an outer point of any of the pins, will pass through the separation component or will lie closer to the centre of the spool body than the separation component.

In order that the invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying figures, in which:

Figure 1 shows a former body and two pin arrays, in accordance with the invention;

Figure 2 shows the former body and pin arrays of figure 1, in an assembled form; and

Figure 3 shows the former body and pin arrays of figure 2, with windings and core halves positioned thereon.

Referring firstly to figure 1, a former 1 embodying the present invention is shown. The former 1 includes a spool body 2, which is generally hollow and elongate. In the example shown the spool body 2 has a rectangular cross section, but in other embodiments spool body 2 may have any suitable crosssectional shape. The spool body 2 has two open ends 3 providing access to the hollow interior.

An end plate 4 is attached to, or formed integrally with, the spool body 2 at each of its ends. Each end plate 4 is generally planar, and has an aperture therethrough corresponding to the aperture of the open end 3 of the spool body 2. Each end plate 4 extends outwardly from the spool body 2, and has (in the embodiment shown) a generally rectangular shape, with the longer edges of the end plates 4 being aligned with the longer edges of the rectangular cross-sectional shape of the spool body 2.

In preferred embodiments each end plate 4 lies in a plane which is perpendicular or substantially perpendicular to the longitudinal axis of the spool body 2. Preferably, the end plates 4 are parallel with one another, and are of the same size as each other.

The skilled reader will note that the presence of the two end plates 4 does not block or obstruct access to the hollow interior of the spool body 2, as the end plates 4 do not occlude the open ends 3 of the spool body 2.

Each end plate 4 has a holder 5a, 5b attached thereto, or formed integrally therewith. Each holder 5a, 5b is attached to the respective end plate 4 on one side of the open end 3 of the spool body 2 (in the orientation shown in the figures, adjacent the lower edge of the open end 3).

It is envisaged that, in practical embodiments, a former 1 will have two holders which are of the same design, for the sake of simplicity. However, to illustrate two different possibilities, the former 1 is shown with two different designs of holder.

A first holder 5a includes a top surface 6, which in the example shown is planar and generally rectangular and extends substantially perpendicular to the plane of the respective end plate 4. The top surface 6 is, in the example shown, wider than the end plate 4 to which it is attached, and extends outwardly beyond the end plate 4 in both directions. First and second side walls 7 extend from the ends of the top plate 6, in a direction away from the corresponding open end 3 of the spool body 2, and are generally parallel with one another. The two side walls 7 have, in the embodiment shown, parallel guidance grooves 8 formed therein, on the surfaces thereof that face each other.

The first holder 5a also has a back wall 9 which extends generally parallel with the respective end plate 4, and is joined (or formed integrally with) both the top plate 6 and the side walls 7.

It will be understood that the first holder 5a generally takes the form of an elongate cuboid, with two of its adjacent longer faces missing.

At the edge 10 of the back wall 9 which is furthest from the top wall 6, a series of cut-out notches 11 are formed. This may give the edge 10 a castellated appearance. In the example shown, this edge 10 of the rear wall 9 overlaps the end plate 4, and the end plate 4 also has corresponding cut-out notches 11 formed therein.

The second holder 5b is positioned on the opposite side of the holder 1, and is attached to, or formed integrally with, the other end plate 4. The second holder 5b has a top wall 6 and back wall 9, which in the embodiment shown are similar to the top wall 6 and back wall 9 of the first holder 5a. However, the second holder 5b does not have side walls 7. The second holder 5b is therefore elongate, and has a generally L-shaped cross-section. The second holder 5b preferably has a length and width which are the same as, or similar to, the length and width of the first holder 5a.

The second holder 5b has engagement protrusions (not visible in the figures) which protrude from the interior side of the top wall 6 and/or back wall 9. In one embodiment, the engagement protrusions take the form of pins or rods, which may have a generally circular cross-section, and which protrude from the interior surface of the top wall 6, in a direction that is parallel or substantially parallel with the back wall 9.

Once again, at the edge 10 of the back wall 9 which is furthest from the top wall 6, a series of cut-out notches 11 are formed, and this may give the edge 10 a castellated appearance. In the example shown, this edge 10 of the rear wall 9 overlaps the end plate 4, and the end plate 4 also has corresponding cut-out notches 11 formed therein.

Each end plate 4 also has a retaining protrusion 12 attached thereto, or formed integrally therewith. Each retaining protrusion 12 is, in the example shown in the figures, formed on the opposite side of the respective open end 3 of the spool body 2 from the side on which the holder 5a, 5b is formed. Each retaining protrusion 12 takes the form of a rib which runs generally parallel with the holder 5a, 5b.

In the example shown, each retaining protrusion 12 is wider than the end plate 4 on which it is provided, and extends outwardly therefrom in both directions. Each retaining protrusion 12 may be the same, or substantially the same, width as the corresponding holder 5a, 5b.

The former 1 may be moulded as a single unitary item, or alternatively may be assembled from a number of sub-components which are fixed together by gluing, welding or any other suitable method. The former 1 is preferably formed from a non-conductive material, and may, for instance, be formed from a plastic material.

First and second pin arrays 13a, 13b are also shown in figure 1. Each pin array 13a, 13b is separate to the former 1, but is adapted to be received and retained by one of the holders 5a, 5b, and has one or more engagement features provided thereon which are adapted to cooperate with engagement features on the respective holder 5a, 5b.

Turning firstly to the first pin array 13a, the first pin array 13a is adapted to be received and retained by the first holder 5a, and comprises a block 14, formed from a non-conductive material such as plastic. The block 14 is adapted to fit into the interior space defined by the first holder 5a. The block 14 has protruding ribs 15 formed on each end, and the ribs 15 are suitably sized and spaced to fit into the grooves 8 formed inside the end walls 7 of the first holder 5a. It will therefore be understood that the first pin array 13a can be slid into the space defined by the first holder 5a, and the interaction of the grooves 8 and ribs 15 will help to hold the first pin array 13a in place.

The second pin array 13b is adapted to be received and retained by the second holder 5b, and also comprises a block 14. The block 14 of the second pin array 13b is of a suitable size and shape to fit into the space defined between the top wall 6 and back wall 9 of the second holder 5b. The block 14 also comprises a pair of engagement apertures 24 formed therein. Each engagement aperture 24 is formed through a rear wall 25 of the block 14 (i.e. the wall which will, in use, lie against the back wall 9 of the second holder 5b), and which extends from a point near the middle of the height of the rear wall 25, all the way to the top surface 26 of the block 14 (i.e. the wall which will, in use, lie against the top wall 6 of the second holder 5b). An upper part of each engagement aperture 24 is narrowed, compared to a lower part thereof.

Two engagement apertures 24 are provided, spaced apart from each other, in the block 14 of the second pin array 13b.

When the second pin array 13b is placed into the space defined by the top wall 6 and back wall 9 of the second holder 5b, the pins of the second holder 5b enter the engagement apertures 24, and are gripped and held by the narrowed upper portions of the engagement apertures 24. The second pin array 13b will therefore be retained and held in place by the second holder 5b.

The invention is not limited to these examples, and the pin arrays 13a, 13b and holders 5a, 5b may have any suitable type of cooperating features to allow the pin arrays 13a, 13b to be received and retained by the respective holders 5a, 5b. The skilled reader will be aware of many different types of possible such cooperating features.

Each pin array 13a, 13b further comprises a plurality of electrically conductive pins 16, which pass through or are embedded in the block 14. Each pin 16, is, in the embodiment shown, generally L-shaped, protruding from first and second surfaces 17, 18 of the block 14, and turning through a right angle within the block 14.

The pins 16 are preferably arranged so that, when a pin array 13a, 13b is received within one of the holders 5a, 5b, the pins 16 protrude from the first surface 17, away from the spool body 2 in a direction which is generally parallel with the end plates 4, and from the second surface 18, away from the spool body 2 in a direction which is generally parallel with the longitudinal axis of the spool body 2. However, this arrangement is not essential and the pins 16 may be arranged in any suitable way.

Figure 2 shows the two pin arrays 13a, 13b fully installed in the respective holders 5a, 5b. In this embodiment, the block 14 of each pin array 13a, 13b fills or substantially fills the interior space defined within the respective holder 5a, 5b. The pins 16 protrude from the holder 5a, 5b in two directions, i.e. substantially directly away from the top surface 6, and substantially directly away from the back wall 9.

In order to form a transformer 19, as shown in figure 3, primary and secondary windings are wound onto the former 1. Primary and secondary windings will be wound around the spool body 2, and are retained in place by the two end plates 4. In the image shown in figure 3, only the secondary windings 20, which are outermost, can be seen. However, the primary windings may be formed around the spool body 2, with a shielding layer (not shown) then being formed around the primary windings. The shielding layer may, for example, comprise a metallic layer to provide an inductive shield at least partly around the primary windings.

The secondary windings 20 are then formed around the exterior of the shielding layer.

Once this has been done, two core halves 21, both being generally E-shaped, are placed together to form a core. Each core half 21 is positioned so that the central prong of the E-shape passes into the hollow interior of the spool body 2, and the two outermost prongs of the E-shape lie on either side of the secondary windings 20. The two core halves 21 preferably meet each other, on both sides of the secondary windings 20 and also within the interior of the spool body 2. The dimensions of the core halves 21 are preferably such that they fit (preferably with a close fit, to reduce or eliminate unwanted movement of the core halves 21) between the top walls 6 of the holders 5a, 5b and the retaining protrusions 12, on each side of the spool body 2.

The safety clearances 22 between the pins 16, and the core halves 21, on each side of the transformer 19 are shown in figure 3. It can be seen that these safety clearances 22 are relatively large.

One reason for these relatively large safety clearances 22 is that the top wall 6 of each holder 5a, 5b can be relatively deep (i.e. extend outwardly a relatively long way from the spool body 2, in a direction which is generally parallel with the longitudinal axis of the spool body 2). This means that a relatively large, solid sheet of insulating material is present between the core halves 21 and the pins 16. As can be seen in figure 3, the effective distance (i.e. safety clearance 22) between each core half 21 and the corresponding pin 16 must extend outwardly and around the free end 23 of the top wall 6 of each holder 5a, 5b. In preferred embodiments, the top wall 6 of each holder 5a, 5b presents an Overhang’, i.e. the top wall 6 projects outwardly, in a direction generally parallel with the longitudinal axis of the spool body, beyond the level of both the contact pins 16 and each core half 21.

In other words, a straight line drawn between the outer edge of the core (i.e. the edge which is furthest from the centre of the spool body 2, in a direction generally parallel with the longitudinal axis of the spool body 2) and the outer edge of any of the contact pins 16, will pass through the top wall 6 of the corresponding holder 6, or will lie closer to the centre of the spool body 2 than the top wall 6.

The skilled reader will understand that, for the same reasons, there are also relatively large safety clearances between the windings 20 and the contact pins 16, since the shortest distance from the windings 20 to the contact pins 16 must also pass over and around the outer free edge 23 of the top wall 6 of each holder 5a, 5b. Once again, a straight line drawn between the outer edge of the winding 20 (i.e. the edge which is furthest from the centre of the spool body 2, in a direction generally parallel with the longitudinal axis of the spool body 2) and the outer edge of any of the contact pins 16, will pass through the top wall 6 of the corresponding holder 6, or will lie closer to the centre of the spool body 2 than the top wall 6.

It will be appreciated that this arrangement would be awkward and impractical to mould if the former 1 and the pin arrays 13a, 13b were formed integrally as one unit. However, forming the pin arrays 13a, 13b to be removably attachable to the holders 5a, 5b, which are attached to the former 1, greatly increases the ease with which this arrangement can be created.

When the transformer 19 is formed, the primary and secondary windings 20 can be attached to the pins 16 through wires or other conductors, which pass through the cut-out notches 11 which are formed in the back wall 9 of each holder 5a, 5b (and also, if present, the cut-out notches 11 formed in each end plate 4). These cut-out notches 11 therefore provide convenient access to allow electrical connection of the primary and secondary windings 20 to the pins 16 of the pin arrays 13a, 13b. The pins 16 can then be plugged into any suitable component during use of the transformer 19.

In the discussion above, the former 1 has two holders 5a, 5b attached thereto, each of which is adapted to receive and retain a respective pin array 13a, 13b. In other embodiments, however, the former 1 may have only one holder attached thereto, or formed integrally therewith. This holder will be adapted to receive and retain only one pin array. Embodiments of this type may be used where, for example, only one of the primary and secondary windings is to be attached to a pin array on the former 1, and the other of the primary and secondary windings has a different type of connection.

In the above embodiments a spool body has end plates attached thereto, or formed integrally therewith, and holders are attached to the end plates. However, in other embodiments this need not be the case. In particular, one or both of the holders may be attached directly to the spool body, as well as, or instead of, being attached to the end plates. In other embodiments, the holders may be attached to a different component, which is not the spool body or either of the end plates.

The core of the transformer discussed above is formed from two generally Eshaped halves. However, this is not essential and any suitable type of core can be used. For instance, the core may be formed from one E-shaped part and one generally elongate bar, or take any other suitable form or shape.

The skilled reader will understand that the invention provides transformers, and methods of forming transformers, that are easy to form and assemble, and which display clear advantages over known transformers.

When used in this specification and claims, the terms comprises and comprising and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A former for a transformer, the former comprising:

a former body comprising a spool around which at least one of the primary and secondary windings of the transformer can be formed;

at least one holder which is attached to, or formed integrally with, the spool or another component of the former; and at least one pin array comprising one or more conductive pins, wherein the pin array may be removably received in the at least one holder.

2. A former according to claim 1, comprising first and second holders which are each attached to, or formed integrally with the spool, or with another component of the former, and first and second pin arrays which may be removably received in the respective holders.

3. A former according to claim 1 or 2, wherein the spool body is generally elongate, having a hollow interior and two open ends.

4. A former according to any preceding claim, comprising first and second end plates, provided at respective ends of the spool body.

5. A former according to claim 4, when dependent upon claim 2, wherein the holders are attached to the respective end plates.

6. A former according to any preceding claim, wherein the or each pin array comprises a block of a non-conductive material, with one or more conductive pins attached thereto or passing therethrough.

7. A former according to any preceding claim, wherein at least one pin array and the at least one holder have respective attachment features, allowing the pin array to be removably received and held by the holder.

8. A former according to claim 7, wherein the attachment features comprise cooperating ribs and grooves.

9. A former according to any one of claims 1 to 7, wherein the attachment features comprise cooperating protrusions and apertures.

10. A former according to any preceding claim, comprising a separation component provided between the spool body and the location of the pin array when it is received and retained by the at least one holder, wherein the separation component protrudes outwardly with respect to the spool body further than any of the conductive pins of the at least one pin array, when the pin array is received and retained by the holder.

11. A former according to claim 10, wherein the separation component comprises part of the holder.

12. A transformer comprising a former according to any preceding claim, and further comprising at least one winding wound around the spool body, and a core which protrudes at least partially into the hollow interior of the spool body, wherein at least one of the conductive pins of one of the pin arrays is conductively connected to the winding.

13. A transformer according to claim 12, when dependent upon claim 10 or 11, wherein a straight line connecting an outer edge of the core, and an outer point of any of the pins, will pass through the separation component or will lie closer to the centre of the spool body than the separation component.

14. A transformer according to claim 12, when dependent upon claim 10 or

11, wherein a straight line connecting an outer edge of the winding, and an outer point of any of the pins, will pass through the separation component or

5 will lie closer to the centre of the spool body than the separation component.

15. Any novel feature or combination of features disclosed herein.