RAFFIN, Vincent (55 Les Versants de la Raviniere, Osny, Osny, F-95520, FR)
BEATTIE, Alex (52 Bounds Green Road, London N11 2EY, GB)
HUGAUD, Pascal (8 parc du Belloy, Le Mesnil Le Roi, Le Mesnil Le Roi, F-78600, FR)
RAFFIN, Vincent (55 Les Versants de la Raviniere, Osny, Osny, F-95520, FR)
Claims
1. An electrical unit comprising: a housing; a first electrical component contained within the housing and mounted thereto or supported thereby, the first electrical component having at least one conductive contact pin having a substantially constant cross-section at least along a connection region of the contact pin; a circuit board mounted to be supported by the housing, having an aperture therethrough and being provided with a contact arrangement having at least one contact surface, the arrangement being such that the contact pin may pass through the aperture in the circuit board so that the connection region thereof is received and retained by the contact arrangement, such that the contact surface exerts a contact force on the contact pin, retaining the contact pin in conductive communication with the circuit board.
2. A unit according to claim 1 , wherein the housing comprises at least a main body and a cover which may be placed on the main body to enclose at least substantially an interior of the housing.
3. A unit according to claim 1 or 2, wherein the housing is at least substantially formed from a non-conductive material.
4. A unit according to claim 3, wherein the housing is made of a plastic material.
5. A unit according to any preceding claim, wherein the first electrical component has at least two contact pins.
6. A unit according to any preceding claim, wήerein at least the connection region of the or each contact pin has a substantially circular cross-section.
7. A unit according to any preceding claim, wherein the aperture is dimensioned to be larger than the connection region of the contact pin, so that the connection region of the contact pin may pass through the aperture without contacting the aperture.
8. A unit according to any preceding claim, wherein the aperture has a first portion which is larger than the connection region of the contact pin, so that the connection of the contact pin may pass through the first portion without touching the first portion, and a second portion which is in communication with the first portion and is dimensioned to receive the connection region of the contact pin in a close fit.
9. A unit according to claim 8, wherein an inner surface of the second portion comprises the contact surface.
10. A unit according to claim 8 or 9, wherein the first and second portions of the aperture are in communication such that the connection region of the contact pin may be inserted into the first portion of the aperture, and then pressed into the second portion of the aperture to be received in a close fit.
11. A unit according to any one of claims 8 to 10, wherein at least a part of the housing comprises a protrusion which, once the connection region of the contact pin has been received in the second portion of the aperture, may be inserted into the aperture to prevent the pin from being removed from the second portion of the aperture.
12. A unit according to claim 11 , wherein the protrusion is provided on a cover of the housing.
13. A unit according to any one of claims 1 to 7, wherein the contact arrangement comprises a contact member which is positioned so that, when the connection region of the contact pin passes through the aperture, the contact member is deflected by the contact pin.
14. A unit according to claim 13, wherein the contact member is elastically deflected by the contact pin, and exerts a force thereagainst once the contact pin has been inserted into the aperture.
15. A unit according to claim 14, wherein the contact member is supported on a resilient strut, which is elastically deformable when the contact pin passes through the aperture.
16. A unit according to any one of claims 11 to 15, comprising a plurality of contact members, each of which is deflected when the contact pin passes through the aperture so that each of the contact members presses against the contact pin, retaining the contact pin between the contact members.
17. A unit according to any one of claims 13 to 16, wherein the contact arrangement is in electrical connection with the circuit board.
18. A method of assembling an electrical unit, comprising the steps of: providing a housing; placing a first electrical component, within the housing so that it is mounted thereto or supported thereby, the first electrical component having at least one conductive contact pin having a substantially constant cross- section at least along a connection region of the contact pin; mounting a circuit board so that it is supported by the housing, the circuit board having an aperture therethrough and being provided with a contact arrangement having at least one contact surface, passing the contact pin through the aperture in the circuit board so that the connection region thereof is received and retained by the contact arrangement, such that the contact surface exerts a contact force on the contact pin, retaining the contact pin in conductive communication with the circuit board. |
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.
It is an object of the present invention to seek to provide an improved electrical unit of this type.
Accordingly, one aspect of the present invention provides an electrical unit comprising: a housing; a first electrical component contained within the housing and mounted thereto or supported thereby, the first electrical component having at least one conductive contact pin having a substantially constant cross-section at least along a connection region of the contact pin; a circuit board mounted to be supported by the housing, having an aperture therethrough and being provided with a contact arrangement having at least one contact surface, the arrangement being such that the contact pin may pass through the aperture in the circuit board so that the connection region thereof is received and retained by the contact arrangement, such that the contact surface exerts a contact force on the contact pin, retaining the contact pin in conductive communication with the circuit board.
Advantageously, the housing comprises at least a main body and a cover which may be placed on the main body to enclose at least substantially an interior of the housing.
Preferably, the housing is at least substantially formed from a non-conductive material.
Conveniently, the housing is made of a plastic material.
Advantageously, the first electrical component has at least two contact pins.
Preferably, at least the connection region of the or each contact pin has a substantially circular cross-section.
Conveniently, the aperture is dimensioned to be larger than the connection region of the contact pin, so that the connection region of the contact pin may pass through the aperture without contacting the aperture.
Advantageously, the aperture has a first portion which is larger than the connection region of the contact pin, so that the connection of the contact pin may pass through the first portion without touching the first portion, and a second portion which is in communication with the first portion and is dimensioned to receive the connection region of the contact pin in a close fit.
Preferably, an inner surface of the second portion comprises the contact surface.
Conveniently, the first and second portions of the aperture are in communication such that the connection region of the contact pin may be inserted into the first portion of the aperture, and then pressed into the second portion of the aperture to be received in a close fit.
Advantageously, at least a part of the housing comprises a protrusion which, once the connection region of the contact pin has been received in the second portion of the aperture, may be inserted into the aperture to prevent the pin from being removed from the second portion of the aperture.
Preferably, the protrusion is provided on a cover of the housing.
Conveniently, the contact arrangement comprises a contact member which is positioned so that, when the connection region of the contact pin passes through the aperture, the contact member is deflected by the contact pin.
Advantageously, the contact member is elastically deflected by the contact pin, and exerts a force thereagainst once the contact pin has been inserted into the aperture.
Preferably, the contact member is supported on a resilient strut, which is elastically deformable when the contact pin passes through the aperture.
Conveniently, the unit comprises a plurality of contact members, each of which is deflected when the contact pin passes through the aperture so that each of the contact members presses against the contact pin, retaining the contact pin between the contact members.
Advantageously, the contact arrangement is in electrical connection with the circuit board.
Another aspect of the present invention provides a method of assembling an electrical unit, comprising the steps of: providing a housing; placing a first electrical component within the housing so that it is mounted thereto or supported thereby, the first electrical component having at least one conductive contact pin having a substantially constant cross-section at least along a connection region of the contact pin; mounting a circuit board so that it is supported by the housing, the circuit board having an aperture therethrough and being provided with a contact arrangement having at least one contact surface, passing the contact pin through the aperture in the circuit board so that the connection region thereof is received and retained by the contact arrangement, such that the contact surface exerts a contact force on the contact pin, retaining the contact pin in conductive communication with the circuit board.
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:
Figure 1 shows components of an electrical unit embodying the present invention, in a separated state;
Figures 2a to 2f show stages in the connection of components of an electrical unit embodying the present invention;
Figures 3a and 3b show stages in the connection of alternative components of an electrical unit embodying the present invention;
Figures 4 and 5 show profiles of apertures formed in a PCB of an electrical unit embodying the present invention;
Figures 6a to 6d show views of a component of an alternative electrical unit embodying the present invention;
Figures 7a and 7b show stages in connection of components of electrical units embodying the present invention; and
Figures 8a to 8d and 9a to 9d show views of alternative components of an electrical unit embodying the present invention.
With reference firstly to figure 1 , a cut-away side view of an electrical unit 1 embodying the present invention is shown. The electrical unit 1 comprises a box 2 or other housing formed from a sturdy, insulating material such as a plastics material. The box 2 comprises a lower containing portion 3, comprising a base 4 surrounded by four upstanding walls 5, to define an inner space 6 having a substantially rectangular cross-section. The box 2 also has
a lid 7, which may be fitted on to the open upper end of the lower portion 3, to close this opening and substantially seal the inner space 6.
In preferred embodiments of the invention, the lid 7 is substantially planar but a peripheral groove 8 runs around the underside of the lid. A corresponding lip 9 projects upwardly from the periphery of the outer walls 5 of the lower portion 3, which is received in the peripheral groove 8 of the lid, thus ensuring a tight fit between the lower portion 3 and the lid 7.
A lower part of each of side walls 5 of the lower portion 3 is thicker than an upper part of these walls 5, with an upward-facing shoulder 10 being provided at the junction between these parts. The upward-facing shoulder 10 therefore comprises a peripheral ledge within the box 2 on which the edges of a PCB 11 can rest to accommodate the PCB 11 in the box 2. At one side of the box 2, upward-facing press-fit electrical connections 12 project from the upward-facing shoulder 10, and engage with female press-fit electrical contacts 13, provided in an appropriate part of the PCB 11. The PCB 11 may therefore communicate electrically with an exterior of the box 2 when the PCB 11 has been placed within the box 2 and the lid 7 has been fitted.
The PCB 11 is provided with a plurality of electrical components 14, which are surface-mounted to the PCB 11 on upper and lower sides thereof, and interconnected by conducting tracks (not shown), as will be readily understood by a person of ordinary skill in the art.
Fixed to an inner surface of the base 4 is a relatively large capacitor 15, which is too heavy to be surface-mounted on the PCB 11 without risk of causing damage to the PCB 11 , and must therefore be supported at least individually by the housing rather than by the PCB11. The capacitor 15 is snap-fitted into a holder 16 which is mounted on the base 4, and the weight of the capacitor
15 is therefore supported by the holder 16 and the base 4, and not by the PCB 11.
A pair of electrical contact pins 17 extend from the capacitor 15, and may be received by and connected to the PCB 11 , as will be explained in more detail below.
Turning to figure 2a, the PCB 11 is provided with a pair of connection apertures 18, each of which is adapted to receive and retain an electrical connection pin 17 of the capacitor 15. The electrical connection pins 17 are substantially cylindrical, having a generally uniform cross-section along their length. There are therefore no features of the connection pins 17 which assist in making a firm electrical and mechanical connection between these pins 17 and other components, in contrast to conventional press-fit connections which rely on connection pins having a specific shape including relatively wide and narrow portions.
Each of the connection apertures 18 comprises a main aperture 19 (as can be seen more clearly in figure 4), which passes all the way through the depth of the PCB 11 and is of a suitable size that a connection pin 17 may easily pass therethrough with clearance on all sides. In preferred embodiments of the invention, the main aperture 19 is generally oval in shape.
At one end of the main aperture 19 is an engagement slot 20, which passes through the entire depth of the PCB 11. The engagement slot 20 is elongate, extends away from the main aperture 18 and is in communication therewith.
The width of the engagement slot 19 is the same as, or slightly less than, the diameter of a connection pin 17 of the capacitor 15. An inner edge of the connection slot. 20 is conductive, and is electronically connected to one or more conductive tracks on the PCB 11.
In order to connect the connection pin 17 of the capacitor 15 to the PCB 11 , the connection pins 17 are first inserted through the main apertures 19 of the connection apertures 18, so that a short length of connection pin 17 protrudes from the far side of the PCB 11 , as shown in figure 2b. The connection pin is then pushed into the engagement slot 20 to form an electrical connection thereon.
A connection tool 21 may be used to assist in this operation. Turning to figure 2c, an end 22 of the connection tool 21 is pushed into the main aperture 19 of one of the connection apertures 18, with the connection pin 17 being positioned between the tool 21 and engagement slot 20. One side of the end 22 of the connection tool 21 has a pair of spaced apart pin-receiving protrusions 23 each of which is adapted to receive the connection pin 17 at an arbitrary point along its length, without gripping or retaining the connection pin 17. An engagement surface of each of the pin-receiving protrusions 23 is in the form of a groove, with the diameter of the groove being greater than the diameter of the connection pin 17. The pin-receiving protrusions 23 are arranged so that one is closer to the end 22 of the connection tool 21 than the other, with the grooves being aligned with one another. The spacing between the pin-receiving protrusions 23 is such that one may be positioned above the plane of the PCB 11 , with the other being positioned below this plane.
An opposite side of the end 22 of the connection tool 21 comprises an inclined surface 24, arranged so that the tip of the end 22 of the tool 21 is relatively narrow, but becomes progressively wider away from the tip.
With reference to figure 2d, the tool 21 is inserted further into the main aperture 19, until the connection pin 17 is received in the grooves of the pin- receiving protrusions 23, the inclined plane 24 abuts against the edge of the main aperture 19 which is furthest from the engagement slot 20, and the pair of pin-receiving protrusions 23 are respectively above and below the PCB 11.
As the tool 21 is pushed further into the engagement aperture 18, the tool 21 is pushed towards the engagement slot 20, as the inclined plane 24 pushes against the edge of the main aperture 18. This action drives the connection pin 17 into the engagement slot 20, where it is firmly received in an interference fit so that there is an electrical connection between the connection pin 17 and the PCB 11. The engagement tool 21 is then removed from the hole, as shown in figures 2e and 2f, leaving the connection pin 17 firmly connected to the PCB 11.
Referring to figures 3a and 3b, in embodiments of the invention the underside of the lid 7 is provided with two downward-facing protrusions 25, each of which is slightly tapered, being narrower at the tip 26 than the root 27. Each protrusion 25 has a cross-sectional shape which corresponds to one of the engagement apertures 18, being generally oval with a relatively narrow fin 28 projecting from one side. The fin 28 is positioned so that, when the protrusion 25 fits into an engagement aperture 18, the fin 28 fits into the engagement slot 20 thereof, but the width of the fin 28 is less than the length of the engagement slot 20.
In order to connect the capacitor 15 to the PCB 11 , the connection pins 17 of the capacitor 15 are inserted into the connection apertures 18, and positioned near the engagement slots 20 thereof. The lid 7 is then placed on the lower portion 3 of the box 2, and the protrusions 25 align with the engagement apertures 18. As the lid 7 is fitted the protrusions 25 project further into the engagement apertures 18, and the fins 28 thereof drive the connection pins 17 into the engagement slots 20, forming an interference fit between the connection pins 17 and the inner edges of the engagement slots 20. When the box 20 is sealed the lid 7 and its protrusions 25 remain in place, thus ensuring a strong mechanical and electrical connection between the connection pins 17 and the PCB 11.
With reference to figure 4, the shape of the connection aperture 18 is shown in more detail, both before and after connection to a connection pin 17. As can be seen in figure 5, the connection apertures 18 may also be formed at an edge of the PCB 11.
It will be appreciated that the connection arrangement described above allows connection pins of a capacitor to be connected directly to a PCB, without the need for soldering or other connection methods which generate excessive quantities of heat, and without the need for any additional connection components to provide an electrical contact between the capacitor and the PCB.
With reference to figures 6a, 6b and 6c, plan, elevation and perspective views respectively are shown of a first connection component 26, which may be used with further embodiments of the invention. The first connection component 26 has a substantially annular, ring-shaped main body 27, which is planar, of generally circular shape and has an aperture 28 formed in the centre thereof. Four evenly-spaced struts 29 project inwardly from the inner edge of the main body 27, and support four contact members 30, each of which is generally planar and wider than its supporting strut 29. Each contact member 30 projects inwardly towards the centre of the aperture 28, but is also deflected away from the plane of the main body 27, and in a preferred embodiment of the invention is disposed at an angle of around 60° to the plane of the main body 27. The contact members 30 lie close to one another but do not touch one another, leaving a gap passing through the first connection component 26 which is generally positioned on or near an axis passing through the centre of the ring-shaped main body 27.
At opposing outer edges of the main body 27 are substantially planar interface portions 31 , which are generally rectangular in shape and are coplanar with one another, but are in a plane which is offset from the plane of
the main body 27 in the same direction as the direction in which the contact members 30 are deflected from the plane of the main body 30.
With reference to figure 6d, the first connection component 26 is attached to a PCB 11 having a substantially circular aperture 32 formed therethrough, so that the centre of the aperture 32 is generally aligned with the centre of the ring-shaped body 27 of the first connection component 26. The interface portions 31 are connected to the PCB 11 such that they are in electrical contact with one or more conducting tracks (not shown) formed on the PCB 11. It will be understood that the main body 27 is spaced apart from the surface of the PCB11.
A connection pin 17 of a capacitor (not shown) can then be inserted into the gap between the contact members 30, approaching from the side of the first connection component 26 which is opposite to the side to which the contact members 30 are deflected from the main body 27 thereof. The central gap between the contact members 30 is of a width which is slightly less than that of the connection pin 17. It will therefore be appreciated that, as the connection pin 17 is inserted into the gap between the connection members 30, the connection members 30 will be splayed apart, deflecting the struts 29 elastically. It will be understood that this elastic deformation of the struts 29 will cause the contact members 30 to be pressed against the connection pin 17, as the struts 29 attempt to resume their original shape, and therefore that a firm electrical connection will be made between the contact members 30 and the connection pin 17. This allows the connection pin 17 to be robustly electrically connected to other components of the PCB 11.
With reference to figure 7a and 7b, a capacitor 15 is shown before and after connection to a PCB 11 which is provided with two of the first connection components 26.
With reference to figures 8a to 8d, a second connection component 33 is shown. The second connection component 33 has, in common with the first connection component 26, a substantially ring-shaped main body 27, with struts 29 supporting contact members 30 in the space 28 within the ring 27. The second connection component 33 has, however, four connection legs 34, two of which extend away from respective opposing edges of the main body 27 substantially at right angles thereto, and take the place of the interface portions 31 of the first connection component 26. As can be seen in figure 8d, the connection holes 34 may pass through corresponding connection holes 35 in a PCB 11 , and be soldered thereto to form an electrical and mechanical connection between the connection legs 34 and the PCB 11. This can be done before a connection pin 17 is attached to the PCB 11 by way of the second connection component 33, thereby ensuring that heat generated by the soldering process is not transmitted through the connection pin 17 to another component such as a capacitor.
With reference to figures 9a to 9d, a third connection component 36 is shown. The third connection component 36 corresponds to the first connection component 26, but has planar interface portions 37 which lie in the same plane as the ring-shaped main body 27. To connect the third connection component 36 to a PCB 11 , as shown in figure 9d, the third connection component 37 is placed against the PCB 11 so that the aperture 32 through to PCB 11 is aligned with the space between the contact members 30, with the contact members 30 being deflected away from the PCB 11. The interface portions 37 are attached to the PCB 11 by soldering or by any other suitable means, so that the interface portions 37 form a firm electrical contact with one or more conductive tracks formed on the PCB 11. A connection pin 17 may then be passed through the aperture 32 in the PCB 11 and connected to the third connection component 36 by deflecting the contact members 30, as discussed above in relation to the first connection component 26.
It will be appreciated that the first, second and third connection components 26,33,36 each provide practical methods by which a contact pin having a substantially constant cross-sectional diameter may be attached to a PCB without the need for the contact pin to be soldered thereto, and will find use in many applications, for instance that of providing sealed-nonconductive units housing PCBs which must be connected to the components which are too heavy to be safely mounted on the PCB itself.
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.
Next Patent: APPARATUS AND METHOD FOR FORMING FIBRE REINFORCED COMPOSITE STRUCTURES