WO2009010703A1

WO2009010703A1 - An electrical unit

Info

Publication number: WO2009010703A1
Application number: PCT/GB2007/002723
Authority: WO
Inventors: Frederic Dacheux; Lothar Weichenberger
Original assignee: Beattie Alex T S; Autoliv Development AB
Current assignee: Beattie Alex T S; Autoliv Development AB
Priority date: 2007-07-18
Filing date: 2007-07-18
Publication date: 2009-01-22
Anticipated expiration: 2010-01-18

Abstract

An electrical unit comprising: a housing main body (1) having an opening providing access to an interior thereof, the housing main body having a pair of substantially opposing walls (2, 3), each having pairs of protrusions (7) provided on an inner surface thereof, a space being defined between the pairs of protrusions; a circuit board (16) which is supported with respect to the housing main body between the pairs of protrusions; a mounting arrangement (8) adapted to receive and retain an electrical component (13), the mounting arrangement being provided on an inner surface of the housing main body; and an electrical component having at least one conductive contact pin (15) which has a substantially constant diameter over at least a contact portion thereof, the electrical component being mounted with respect to the housing main body by the mounting arrangement and being electrically connected to the circuit board by the contact portion of the at least one contact pin.

Description

Title: 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 a wire cable or lead.

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 main body having an opening providing access to an interior thereof, the housing main body having a pair of substantially opposing walls, each having pairs of protrusions provided on an inner surface thereof, a space being defined between the pairs of protrusions; a circuit board which is supported with respect to the housing main body between the pairs of protrusions; a mounting arrangement adapted to receive and retain an electrical component, the mounting arrangement being provided on an inner surface of the housing main body; and an electrical component having at least one conductive contact pin which has a substantially constant diameter over at least a contact portion thereof, the electrical component being mounted with respect to the housing main body by the mounting arrangement and being electrically connected to the circuit board by the contact portion of the at least one contact pin.

Advantageously, the mounting arrangement is provided on an inner surface of the housing main body which is substantially parallel with the circuit board.

Preferably, the housing main body comprises a back wall substantially opposite to the opening thereof, with the pairs of protrusions also being provided on the back wall.

Conveniently, the protrusions comprise spaced apart ribs.

Advantageously, the housing main body comprises two pairs of substantially parallel opposing walls.

Preferably, pairs of substantially parallel walls are generally perpendicular to one another. Conveniently, a cover is provided to close the opening of the unit, the cover being in electrical contact with the circuit board and allowing conductive communication between the circuit board and the exterior of the unit.

Another aspect of the present invention provides a method of manufacturing an electrical unit, comprising the steps of: providing a housing main body having an opening providing access to an interior thereof and pairs of spaced apart protrusions on inner surfaces of substantially opposite walls; mounting an electrical component to an inner surface of the housing main body, the electrical component having at least one conductive contact pin which has a substantially constant cross-section over at least a contact portion thereof; mounting a circuit board in the housing main body by sliding the circuit board between the pairs of protrusions so that the circuit board is retained in the housing main body; and connecting the circuit board to the contact portion of the at least one contact pin so that the circuit board is in conductive communication with the electrical component.

Advantageously, the step of mounting the circuit board in the housing main body comprises the step of mounting the circuit board substantially parallel to the surface to which the electrical component is mounted.

Preferably, the action of mounting the circuit board in the housing main body brings the circuit board into conductive contact with the at least one contact pin.

Conveniently, a leading edge of the circuit board has contact location, and wherein the step of mounting the circuit board in the housing main body brings the contact pin into contact with the contact location. Advantageously, the contact location comprises an opening to receive the contact pin, a neck portion which is narrower than the opening, and a receiving aperture which is on the far side of the neck from the opening, the act of inserting the circuit board into the housing main body causing the contact pin to be received in the opening, to pass through the neck and to be received in the receiving aperture.

Preferably, the method further comprises the step of fitting a cover over the opening of the housing main body to close the unit substantially, the cover being in electrical communication with the circuit board and allowing conductive communication between the circuit board and the exterior of the unit.

Conveniently, the step of mounting the electrical component is carried out before the step of introducing the circuit board into the housing main body.

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 a capacitor in two different positions with respect to a housing;

Figure 4 shows a contact notch formed in a circuit based; and

Figures 3 and 5 show various stages in the assembly of an electrical unit according to the present invention.

Referring firstly to figure 1, a main body 1 of a housing for use with an electrical unit embodying the present invention is shown. The main body 1 defines a substantially oblong, hollow box with one face thereof missing, and has opposing substantially planar side surfaces 2,3, top and bottom surfaces 4,5 and a back surface 6. The main body 1 is preferably formed from a rugged, electrically insulating material such as a plastics material.

A pair of parallel, spaced apart ribs 7 run around the interior of the main body 1 , protruding from the two side walls 2,3 and the back wall 6. The ribs are provided parallel with and slightly above the bottom surface 5, and define a narrow space therebetween.

A mounting arrangement 8 is provided to receive and retain an electronic component, as will be described in more detail below. The mounting arrangement 8 comprises a hollow, generally cylindrical holder 9, which is attached to the inner surface of the top wall 4, and has a break 10 in the circumference thereof on the side opposite from the top wall 4. The holder 9 is oriented so that its longitudinal axis is parallel with the planes of the top, bottom and side walls 4,5, 2,3, and the holder 9 extends over substantially the entire depth of the main body 1. On the back wall 6 of the main body 1 two elongate, generally rectangular support protrusions 11 are provided, which are spaced apart from one another, and extend from the side of the holder 9 furthest from the top wall 4 to the bottom wall 5, being parallel with the side walls 2,3. - The supporting protrusions 11 are disposed on the back wall 6, crossing the ribs 7 at right angles thereto, and protrude from the back wall 6 by a greater distance than the ribs 7. The support protrusions 11 have a break therein, coincident with the space between the ribs 7. On the front surface of each of the support protrusions 11 is a groove 12, which runs along the length of the support protrusion 11. The grooves are therefore at right angles to the longitudinal axis of the holder 9, and to the portions of the ribs 7 which are on the back wall 6. The mounting arrangement 8 is adapted to receive and retain a capacitor 13

(although it should be noted that the invention is not limited to use with capacitors), which comprises a substantially cylindrical body 14, and has two contact pins 15 protruding from one of the end faces thereof. The contact pins 15 preferably have a substantially constant diameter over their lengths, or at least over contact portions thereof which are to be connected to a circuit

^•board (described below). In order to be received by the mounting arrangement 8, the contact pins 15 of the capacitor 13 are manipulated so that they extend from the main body 14 substantially at right angles to the longitudinal axis thereof.

In order to insert the capacitor 13 into the mounting arrangement 8, the capacitor 13 is aligned so that the main body 14 thereof is coaxial with the cylindrical holder 9, with the contact pins 15 being provided on the end of the main body 14 that is closest to the mounting arrangement 8. The capacitor 13 is then inserted into the holder 9 so that the contact pins 15 pass through the break 10 in the circumference of the holder 9. If the capacitor 13 is inserted all the way into the holder 9, the contact pins 15 are received in the grooves 12 presented on the front surfaces of the support protrusions 11 , and this situation can be seen in figure 2.

Once the capacitor 13 has been received and retained by the mounting arrangement 8, a circuit board 16 is inserted into the main body 1 , as can be seen in figure 3. The circuit board 16 may be of a conventional type, comprising a substantially planar substrate formed from a semiconductor material, with various electronic components mounted on one or both of the major surfaces thereof, and connected by conductive tracks. The circuit board 16 is substantially rectangular, but has two contact notches 17 formed at one edge thereof. As can be seen in figure 4, each of the contact notches 17 has a generally triangular entry portion 18 with a relatively narrow neck 19 at the apex thereof. A retaining aperture 20, whose diameter is slightly larger than the width of the neck 19, is provided on the far side of the neck 19 from the entry portion 18. At least part of the inner surface of the retaining aperture 20 is in conductive communication with one or more of the conductive tracks of the circuit board 16.

The circuit board 16 is oriented so that the plane thereof is parallel with the ribs 7, with the contact notches 17 being presented on the edge of the circuit board 16 that is closest to the main body 1 of the housing. The circuit board 16 is then slid into the main body 1 so that the edges thereof pass into the space between the ribs 7. If the circuit board 16 is slid all the way into the main body 1 of the housing, the contact pins 15 of the capacitor 13 will enter the entry portions 18 of the contact notches 17, and if sufficient force is applied to the circuit board 16 the contact pins 15 will pass through the necks 19 of the entry notches 17 and into the retaining apertures 20 thereof, so that the contact pins 15 are connected directly to the circuit board 16. It will therefore be appreciated that the capacitor 13 will then be in conductive communication with the circuit board 16, and may form a part of the circuit defined thereby. The support protrusions 11 ensure that the contact pins 13 are held in an appropriate location to be engaged in this way, and it will be understood that the leading edge of the circuit board 16 is received in the break in each of the contact protrusions 11.

Finally, a closure 21 is fitted onto the open end of the main body 1 of the ^• housing, to form the housing into a sealed unit, as shown in figure 5, by a press-fit or in any other appropriate way. The closure 21 is provided with one or more electrical contacts which connect with the circuit board 16, and has an interface 22 presented on an external surface 23 thereof, to allow communication between the circuit board 16 and the exterior of the housing. It will be appreciated that, as an alternative to the above assembly method, the contact pins 15 of the capacitor 13 could firstly be connected to the circuit board 16 by means of the contact notches 17. The combined circuit board 16 and capacitor 13 may then be slid into the main body 1 of the housing before the closure 21 is put in place to seal the housing.

It will be appreciated that embodiments of the present invention provide a simple and robust method of assembling a closed electrical unit, which requires a minimum of additional connecting 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 main body having an opening providing access to an interior thereof, the housing main body having a pair of substantially opposing walls, each having pairs of protrusions provided on an inner surface thereof, a space being defined between the pairs of protrusions; a circuit board which is supported with respect to the housing main body between the pairs of protrusions; a mounting arrangement adapted to receive and retain an electrical component, the mounting arrangement being provided on an inner surface of the housing main body; and an electrical component having at least one conductive contact pin which has a substantially constant diameter over at least a contact portion thereof, the electrical component being mounted with respect to the housing main body by the mounting arrangement and being electrically connected to the circuit board by the contact portion of the at least one contact pin.

2. A unit according to claim 1, wherein the mounting arrangement is provided on an inner surface of the housing main body which is substantially parallel with the circuit board.

3. A unit according to claim 1 or 2, wherein the housing main body comprises a back wall substantially opposite to the opening thereof, with the pairs of protrusions also being provided on the back wall.

4. A unit according to any preceding claim, wherein the protrusions comprise spaced apart ribs.

5. A unit according to any preceding claim, wherein the housing main body comprises two pairs of substantially parallel opposing walls.

6. A unit according to claim 5, wherein the pairs of substantially parallel walls are generally perpendicular to one another.

7. A unit according to any preceding claim, wherein a cover is provided to close the opening of the unit, the cover being in electrical contact with the circuit board and allowing conductive communication between the circuit board and the exterior of the unit.

8. A method of manufacturing an electrical unit, comprising the steps of: providing a housing main body having an opening providing access to an interior thereof and pairs of spaced apart protrusions on inner surfaces of substantially opposite walls; mounting an electrical component to an inner surface of the housing main body, the electrical component having at least one conductive contact pin which has a substantially constant cross-section over at least a contact portion thereof; mounting a circuit board in the housing main body by sliding the circuit board between the pairs of protrusions so that the circuit board is retained in the housing main body; and connecting the circuit board to the contact portion of the at least one contact pin so that the circuit board is in conductive communication with the electrical component.

9. A method according to claim 8, wherein the step of mounting the circuit board in the housing main body comprises the step of mounting the circuit board substantially parallel to the surface to which the electrical component is mounted.

10. A method according to claim 8 or 9, wherein the action of mounting the circuit board in the housing main body brings the circuit board into conductive contact with the at least one contact pin.

11. A method according to claim 10, wherein a leading edge of the circuit board has contact location, and wherein the step of mounting the circuit board in the housing main body brings the contact pin into contact with the contact location.

12. A method according to claim 11 , wherein the contact location comprises an opening to receive the contact pin, a neck portion which is narrower than the opening, and a receiving aperture which is on the far side of the neck from the opening, the act of inserting the circuit board into the housing main body causing the contact pin to be received in the opening, to pass through the neck and to be received in the receiving aperture.

13. A method according to any one of claims 8 to 12, further comprising the step of fitting a cover over the opening of the housing main body to close the unit substantially, the cover being in electrical communication with the circuit board and allowing conductive communication between the circuit board and the exterior of the unit.

14. A method according to any one of claims 8 to 13, wherein the step of mounting the electrical component is carried out before the step of introducing the circuit board into the housing main body.