WO2009010704A1

WO2009010704A1 - An electrical unit

Info

Publication number: WO2009010704A1
Application number: PCT/GB2007/002727
Authority: WO
Inventors: Henry Caussade; Frederic Dacheux; Lothar Weichenberger
Original assignee: Autoliv Development Ab; Beattie, Alex, T., S.
Priority date: 2007-07-18
Filing date: 2007-07-18
Publication date: 2009-01-22

Abstract

An electrical unit comprising: a housing having a first wall (1); a first.electrical component (6) contained within the housing and mounted onto the first wall, the first electrical component having at least one conductive contact pin (8) protruding therefrom; a circuit board (9) mounted to be supported by the housing; a plurality of connectors (10) which are attached t the circuit board and to at least one of the contact pins, thus providing conductive communication therebetween; and a holder (15) which holds the connectors in fixed relation with respect to one another, the holder being separated from the housing so that, during assembly of the electrical unit, the holder may move with respect to the housing to allow alignment of the connectors with the at least one contact pin.

Description

An Electrical Unit

Description of Invention

THIS INVENTION relates to an electrical unit, and in particular concerns a closed electrical unit which contains a PCB and at least one other electrical component that cannot be supported directly by the PCB.

In several technical fields, for instance in the control of electrical systems on board a motor vehicle, it is desirable to provide a sealed non-conductive (e.g. plastic) housing containing a PCB, onto which are mounted several electrical components. An electrical unit of this type is disclosed in US 6163460.

In many cases, one of the electrical components that must be housed within the unit is a large, relatively heavy capacitor. While most of the electronic components are surface-mounted on the PCB, it is preferred not to attach a bulky capacitor to the PCB directly, since the weight of the capacitor is likely to break or distort the substrate of the PCB. It has therefore been proposed to attach large components such as capacitors to an interior surface of the housing of the unit, so that the weight of the component places no mechanical stress on the PCB itself, and to connect the component electrically to the PCB by one or more wires, cables or leads.

A further complication is that, in the case of certain components such as electrolyte capacitors, it is not possible to solder the leads of the capacitor directly to a PCB, since the high temperatures transmitted to the capacitor along the leads would irreparably damage the capacitor. In any event, when assembling a unit of this type, it is preferred not to carry out any further soldering operations. Accordingly, one aspect of the present invention provides an electrical unit comprising: a housing having a first wall; a first electrical component contained within the housing and mounted onto the first wall, the first electrical component having at least one conductive contact pin protruding therefrom; a circuit board mounted to be supported by the housing; a plurality of connectors which are attached to the circuit board and to at least one of the contact pins, thus providing conductive communication therebetween; and a holder, which holds the connectors in fixed relation with respect to one another, the holder being separated from the housing so that, during assembly of the electrical unit, the holder may move with respect to the housing to allow alignment of the connectors with the at least one contact pin.

Advantageously, during assembly of the unit, the holder may move with respect to the housing both parallel with and perpendicular to the plane of the first wall.

Preferably, at least some of the connectors are press-fitted to the circuit board.

Conveniently, at least some of the connectors are soldered to the circuit board.

Advantageously, each of the connectors has a connection arrangement for connection to one of the pins, the connection arrangement comprising a pair of spaced apart tines, so that the pin may be received and retained between the tines.

Preferably, a positioning protrusion is provided to maintain the position of at least one of the pins with respect to the housing. Conveniently, two spaced apart positioning protrusions are provided for each pin, a gap being present between the positioning protrusions to receive at least part of the connection arrangement of one of the connectors.

Advantageously, three or more positioning protrusions are provided for each pin, gaps being provided between the positioning protrusions to receive at least part of the connection arrangements of two of the connectors.

Preferably, the width of the at least one gap is at least 1.5 times the thickness of the part of the connection arrangement that is received within the gap.

Conveniently, the one or more positioning protrusions is provided as part of a positioning element which is mounted to, or formed as part of, an inner surface of the housing.

Advantageously, two connectors are provided to connect each pin of the first electrical component to the circuit board.

Preferably, the first electrical component has two pins, two connectors being provided to connect each of the pins to the circuit board, and all of the connectors are held in fixed relation to one another by the holder.

Another aspect of the present invention provides a method of assembling an electrical unit, comprising: providing a housing having a first wall; mounting a first electrical component onto the first wall, the first electrical component having at least one conductive contact pin protruding therefrom; providing a circuit board; providing a plurality of connectors; attaching the connectors to a holder which hold the connectors in fixed relation with respect to one another, the holder being separated from the housing; connecting the connectors to the circuit board; moving the holder with respect to the housing to allow alignment of the connectors with the at least one contact pin; and attaching the connectors to the at least one contact pin, thus providing conductive communication between the circuit board and the at least one contact pin.

A further aspect of the present invention provides a kit for producing an electrical unit, the kit comprising: a housing having a first wall and a mounting arrangement provided on the first wall; a first electrical component adapted to be mounted on the mounting arrangement so that the first electrical unit is contained within the housing, the first electrical component having at least one conductive contact pin protruding therefrom; a circuit board for mounting so that it is supported by the housing; a plurality of connectors for attachment to the circuit board and to at least one of the contact pins, to provide conductive communication therebetween; and a holder which holds the connectors in fixed relation with respect to one another, the holder being separated from the housing so that, during assembly of the electrical unit, the holder may move with respect to the housing to allow alignment of the connectors with the at least one contact pin.

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

Figures 1 and 2 show components of an electrical unit embodying the present invention in unassembled and assembled forms, respectively; and

Figure 3 shows part of the process of assembly of an electrical unit embodying the present invention. Figure 4 shows components of an alternative electrical unit embodying the present invention in an unassembled form, and

Figure 5 is a cutaway view of an assembled electrical unit embodying the present invention.

With reference firstly to figure 1 , one wall 1 is shown of a housing for an electrical unit. Although the entire electrical unit is not shown, it is envisaged that the electrical unit will comprise a closed box-like housing formed from a sturdy, insulating material such as a plastics material. Preferably, the housing comprises a lower containing portion, comprising a base surrounded by four upstanding walls, to define an inner space having a substantially rectangular cross-section. A lid is also provided, which may be fitted onto the upper end of the lower portion, to close this opening and seal substantially the inner space.

The wall 1 shown in figure 1 may comprise any of the walls of the housing, or indeed may comprise the lid thereof.

Attached to an inner surface of the wall 1 is a mounting arrangement 2 comprising first and second opposing clips 3 which project from the inner surface 4 of the wall 1. Each of the clips 3 comprises a substantially rectangular body, which is arranged to be generally perpendicular to the plane of the wall 1 , and each of which has a protruding lip 5 at or near the free end thereof, which protrudes towards the other one of the pair of clips 3.

The clips 3 are preferably formed from a sturdy, resilient, non-conductive material, and may be formed integrally with the wall 1. A capacitor 6 is provided, the capacitor 6 being of the type which incorporates a relatively large, substantially cylindrical body 7 and has two contact pins 8 protruding therefrom, each of the contact pins 8 simply comprising a metal lead having a round cross-section with a substantially constant diameter along its length.

The mounting arrangement 2 is adapted to receive and retain the capacitor 6. The dimensions and spacing of the two clips 3 are such that the body 7 of the capacitor may be pushed between the clips 3, contacting the lips 5 thereof so that the clips 3 are deflected and forced apart, and then allowed to return to their initial positions once the body 7 of the capacitor 6 has been pushed past the lips 5. The capacitor 6 is then held in place, being trapped between the inner surfaces of the wall 1 and the clips 3, and being prevented from becoming detached from the mounting arrangement 2 by the protruding lips 5, since the gap between the protruding lips 5 is less than the width of the body 7 of the capacitor 6.

A PCB 9 is also provided within the housing as part of the electrical unit. The PCB 9 may be conventional, comprising a substrate of a semiconductor material, having electrical components (not shown) mounted thereto, with conductive tracks being provided on one or both major surfaces of the PCB 9 to connect the components to one another.

The PCB 9 is preferably mounted within the housing so that it is substantially parallel to, and spaced apart from, the wall 1 to which the capacitor 6 is mounted. The PCB 9 is also preferably mounted within the housing so that it is moveable within a plane that is generally parallel with and spaced apart from the wall 1 , and this may be achieved, for example, by inserting the PCB

9 between two sets of spaced apart ribs on the surrounding walls (not shown). A plurality of conductive connectors 10 are provided to connect the contact pins 8 of the capacitor 6 to the PCB 9. Each of the connectors 10 has a short conductive protrusion 11 extending from one end thereof, which is adapted to be received in a corresponding aperture 12 formed in the PCB 9. The connnector 10 may therefore be connected to the PCB 9, for instance by soldering or with a press-fit connection. Each of the apertures 12 is in conductive communication with at least one of the conductive tracks formed on the surface(s) of the PCB 9.

A main body 12 of each connector is substantially planar and elongate, and terminates at the end opposite from the conductive protrusion 11 in a contact arrangement 13 which is adapted to form an electrical contact with one of the pins 8 of the capacitor 6. In the embodiment depicted in the figures, the contact arrangement 13 comprises a pair of spaced apart tines 14 with a gap therebetween which is of the same width as, or slightly narrower than, the diameter of one of the pins 8 of the capacitor 6.

In the illustrated embodiment, four connectors 10 are provided, arranged in a square 2 x 2 grid pattern, with the tines 14 of the connection arrangements 13 all arranged so as to be parallel with one another and with one of the sides of the square pattern. It will therefore be appreciated that there are two rows of connectors 10, and within each row the spaces between the tines 14 are aligned with one another. The spacing between the two rows is equal or substantially equal to the spacing between the pins of the capacitor 6.

A holder 15 is provided to retain the connectors 10 in this formation, as can be seen clearly in figure 3. The holder 15 preferably comprises a moulded plastic component, having four walls which are joined together at their corners to form a square shape with an aperture passing through the middle of the shape. At each corner of the square, a holder 16 is formed, having an aperture 17 therethrough which is dimensioned to receive and retain one of the connectors 10, so that at least the conductive protrusion 11 projects from one of the open ends of the holder 16 and the connection arrangement 13 projects from the other open end.

To assist in this, the main body 12 of each of the connectors 10 preferably has a first portion 18 disposed near one end thereof, which is relatively wide, and a second portion 19 disposed near the other end thereof, which is narrower than the first portion 18.

Within each of the holders 16, the width of the aperture is preferably wider at one end than at the other, with a "shoulder" being formed where the wider portion meets the narrower portion. A connector 10 may therefore be inserted into the wider part of the aperture 17, with the second, narrower portion 19 of the connector 10 being introduced into the aperture 17 first. The connector 10 may be inserted into the aperture 17 until the junction between the second and first portions 19, 18 reaches the shoulder within the holder 16, thus preventing further movement of the connector into the aperture 17.

To assemble the electrical unit, the capacitor 6 is fixed to the mounting arrangement 2 so that the contact pins 8 thereof lie substantially parallel to, but spaced apart from, the wall 1. The four connectors 10 are inserted into the holder 15 as described above, and are each soldered or press-fitted to the PCB 9. The wall 1 and the PCB 9 are then brought closer together until the connection arrangements 13 of the connectors 10 are in the vicinity of the pins 8 of the capacitor 6. The position of the PCB 9 with respect to the wall 1 may then be adjusted, so that the connection arrangements 13 of two of the connectors 10 are aligned with each of the pins 8 of the capacitor 6. Finally, the PCB 9 is brought closer to the wall 1 so that the connection arrangements 13 of the connectors 10 engage with the pins 8 of the capacitor 6. It will therefore be understood that the capacitor 6 is electrically connected to the PCB 9 and can form part of the circuit thereof.

In preferred embodiments of the invention, a pair of positioning elements 20 are each attached to the inner surface of the wall 1. the positioning elements 20 are preferably formed from a robust, non-conductive material, and each has three positioning protrusions 21 , which project directly away from the inner surface of the wall 1. The positioning protrusions 21 of each of the positioning elements 20 are aligned with one another, and each has a groove formed therein, on the side furthest from the inner surface of the wall 1 , and having a diameter slightly larger than that of each of the pins 8 of the capacitor 6. The longitudinal axes of the grooves are also aligned with one another. Gaps are provided between the positioning protrusions 21 , with the spacing between the gaps being substantially equal to the spacing between the connection arrangements 13 of two connectors 10 that are provided for attachment to any one of the pins 8 of the capacitor 6. The width of each gap is preferably at least 1.5 times the thickness of the connection arrangement 13 of one of the connectors 10.

When the PCB 9 is brought towards the wall 1 to attach the connectors 10 to the pins 8 of the PCB 6, the connectors 10 will tend to push the pins 8 towards the wall 1. The positioning protrusions 21 contact the pins 8, with the pins 8 being received in the grooves provided in the positioning protrusions 21 , and this prevents the pins 8 from being deflected away from the PCB 9, which would be likely to prevent the pins 8 from forming a good electrical and mechanical with the connectors 10. As can be seen in figure 2, once this process has been completed, the connection arrangements 13 of the connectors 10 are received within the gaps between the positioning protrusions 21 , with these components holding the pins 8 of the capacitor 6 firmly in place.

It should be noted that the holder 15 is not connected directly to the housing, and may move with respect thereto. Preferably, the holder 15 may move with respect to the housing at least two orthogonal directions, each of which is parallel with the wall 1 of the housing to which the capacitor 6 is mounted.

This is beneficial, since the alignment of the PCB with respect to the capacitor 6 may be adjusted during assembly of the electrical unit, to compensate for any mis-alignment between the connectors 10 and the pins 8 of the capacitor 6 which may have been introduced.

It is envisaged that, if the wall 1 to which the capacitor 6 is mounted is a lid of the housing, the connection between the PCB 9 and the capacitor 6 may be formed when the lid is placed on the housing to form a sealed unit. Alternatively, of course, the capacitor 6 may be mounted to any other internal wall of the housing.

Figure 4 corresponds to figure 1, but shows components of a unit in which only one connector 10 is provided for each contact pin 8 of the capacitor 6.

Figure 5 is a side, cutaway view of an assembled electrical unit according to the above. External connection leads 22 are shown to allow communication between the PCB 9 and external components.

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

CLAIMS:

1. An electrical unit comprising: a housing having a first wall; a first electrical component contained within the housing and mounted onto the first wall, the first electrical component having at least one conductive contact pin protruding therefrom; a circuit board mounted to be supported by the housing; a plurality of connectors which are attached to the circuit board and to at least one of the contact pins, thus providing conductive communication therebetween; and a holder which holds the connectors in fixed relation with respect to one another, the holder being separated from the housing so that, during assembly of the electrical unit, the holder may move with respect to the housing to allow alignment of the connectors with the at least one contact pin.

2. Ari electrical unit according to claim 1 wherein, during assembly of the unit, the holder may move with respect to the housing both parallel with and perpendicular to the plane of the first wall.

3. An electrical unit according to claim 1 or 2, wherein at least some of the connectors are press-fitted to the circuit board.

4. An electrical unit according to any preceding claim, wherein at least some of the connectors are soldered to the circuit board.

5. An electrical unit according to any preceding claim, wherein each of the connectors has a connection arrangement for connection to one of the pins, the connection arrangement comprising a pair of spaced apart tines, so that the pin may be received and retained between the tines.

6. An electrical unit according to any preceding claim, wherein a positioning protrusion is provided to maintain the position of at least one of the pins with respect to the housing.

7. an electrical unit according to claim 6, wherein two spaced apart positioning protrusions are provided for each pin, a gap being present between the positioning protrusions to receive at least part of the connection arrangement of one of the connectors.

8. An electrical unit according to claim 7, wherein three or more positioning protrusions are provided for each pin, gaps being provided between the positioning protrusions to receive at least part of the connection arrangements of two of the connectors.

9. An electrical unit according to claim 7 or 8, wherein the width of the at least one gap is at least 1.5 times the thickness of the part of the connection arrangement that is received within the gap.

10. An electrical unit according to any one of claims 6 to 9, wherein the one or more positioning protrusions is provided as part of a positioning element which is mounted to, or formed as part of, an inner surface of the housing.

11. An electrical unit according to any preceding claim, wherein two connectors are provided to connect each pin of the first electrical component to the circuit board.

12. An electrical unit according to claim 11 , wherein the first electrical component has two pins, two connectors being provided to connect each of the pins to the circuit board, and all of the connectors are held in fixed relation to one another by the holder.

13. A method of assembling an electrical unit, comprising: providing a housing having a first wall; mounting a first electrical component onto the first wall, the first electrical component having at least one conductive contact pin protruding therefrom; providing a circuit board; providing a plurality of connectors; attaching the connectors to a holder which hold the connectors in fixed relation with respect to one another, the holder being separated from the housing; connecting the connectors to the circuit board; moving the holder with respect to the housing to allow alignment of the connectors with the at least one contact pin; and attaching the connectors to the at least one contact pin, thus providing conductive communication between the circuit board and the at least one contact pin.

14. A kit for producing an electrical unit, the kit comprising: a housing having a first wall and a mounting arrangement provided on the first wall; a first electrical component adapted to be mounted on the mounting arrangement so that the first electrical unit is contained within the housing, the first electrical component having at least one conductive contact pin protruding therefrom; a circuit board for mounting so that it is supported by the housing; a plurality of connectors for attachment to the circuit board and to at least one of the contact pins, to provide conductive communication therebetween; and a holder which holds the connectors in fixed relation with respect to one another, the holder being separated from the housing so that, during assembly of the electrical unit, the holder may move with respect to the housing to allow alignment of the connectors with the at least one contact pin.