EP2147481B1

EP2147481B1 - Electrical connections

Info

Publication number: EP2147481B1
Application number: EP08762958.0A
Authority: EP
Inventors: Stefan Panzner
Original assignee: Zodiac Interconnect UK Ltd
Current assignee: Safran Electrical Components UK Ltd
Priority date: 2007-04-04
Filing date: 2008-04-04
Publication date: 2019-05-29
Anticipated expiration: 2028-04-04
Also published as: GB0806204D0; EP2147481A2; GB2449153A; WO2008122895A3; WO2008122895A2; GB2449153B; GB0706517D0

Description

This invention relates to electrical connections.
The invention is concerned in particular with electrical connections of the kind in which two contact-parts of the connection are interconnected electrically via an intermediate, resilient contact-band carried by one of the contact-parts. Electrical connections of this kind are used especially where currents of high magnitude are to pass between the two contact-parts, and are known, for example, from US-A-5,261,840 .
The resilient contact-band used in electrical connections of the above-specified kind may be of a unitary strip-metal structure having a multiplicity of closely-spaced and mutually-parallel lamella-elements which extend between border-regions of the band that interconnect the lamella-elements along opposite sides of the strip-metal. Each lamella-element has a central head-portion with two shoulder-portions through which the head-portion is linked to the two border-regions respectively, and is twisted between the shoulder-portions and the border-regions to give resilience with the head-portion inclined upwardly and the shoulder-portions inclined downwardly from the border-regions. Each border-region has outwardly-extending projections that are used for retaining the band within a surface-groove of one of the contact-parts with the shoulder-portions of the lamella-elements abutting the floor of the groove of the band-carrying part. When the two contact-parts are brought together with the band squeezed resiliently between them, the shoulder-portions of the lamella-elements of the band are urged resiliently against the groove-floor of the band-carrying contact-part and their head-portions are urged resiliently against the other contact-part so as to establish a multiplicity of parallel paths for current flow between the two contact-parts.
Instead of providing the contact-band in unitary form it may as an alternative comprise an elongate base-structure that carries a multiplicity of individual contact-elements which have head- and shoulder-portions corresponding to those of the lamella-elements referred to above, for establishing the multiplicity of parallel current paths between the two contact-parts. The base-structure carrying the contact-elements includes border-regions on either side of the contact-band for interconnecting the contact-elements and providing the outwardly-extending projections for retaining the band in its groove.
One of the problems experienced with electrical connections using contact-bands of the above kind centres on retention of the contact-band in its groove. In the electrical connections described in US-A-5,261,840 , the groove in which the contact-band is located has a dovetail cross-section in that opposite walls of the groove are inclined inwardly towards one another so that its width reduces upwardly of the groove. The contact-band is retained in the groove by engagement of outwardly-extending projections on both sides of the band under the inwardly-inclined walls, and although this is capable of ensuring secure retention of the band directly within the groove, it requires the band to be installed by feeding it lengthwise into the groove. This requirement adds to the cost and difficulty of manufacturing the electrical connection with its upwardly-narrowing groove of dovetail cross-section, not only in assembly of the connection initially, but also during replacement of the band for repair.
An alternative form of two-part electrical connection of the said above-specified kind is known from US-A-2001/0055919 where the walls of the groove are at right angles to the axis of the connection for ease of insertion of the contact-band. In this case, however, the projections from each border-region of the contact band extend into a respective one of two laterally-spaced slots in the floor of the groove. The end of each projection is configured to bend down towards the bottom of its slot and then to bend in the opposite direction to create an upturned end-face. The upturned end-faces of the projections bear on the outside walls of the groove at acute angles for retention of the contact-band within the groove.
It is one of the objects of the present invention to provide a two-part electrical connection of the above-specified kind that is of advantageous construction for manufacture and repair.
According to one aspect of the present invention there is provided a two-part electrical connection in which first and second contact-parts of the connection are interconnected electrically via an intermediate, resilient contact-band that extends lengthwise within a surface-groove of the first contact-part and has projections which extend outwardly from each of two opposite border-regions of the band, wherein the projections from each border-region extend into a respective one of two laterally-spaced slots in the floor of the groove that run lengthwise of the groove, the projections of each border-region extending into the respective slot to engage resiliently with an outermost wall with the groove in retention of the contact-band in the groove, characterised in that the outermost walls with which the projections engage resiliently are the outside walls of the two slots respectively, and that the outermost wall of each slot is inclined to the floor of the groove (for example at substantially 60 degrees) such that the lateral spacing between the outermost walls of the two slots increases with increasing slot-depht.
The two-part electrical connection of this aspect of the invention has the advantage that retention of the contact-band in the groove does not require the walls of the groove to have a dovetail or other entry-limiting cross-section for engagement by the outwardly-extending projections, since it is engagement of the projections within the slots that is used for retention. Consequently, the cross-section of the groove may be chosen to admit the contact-band directly into the groove simply by pressing it down into the groove. Entry of the projections into the slots as the contact-band is pressed down into the groove, may be facilitated by the resilience of the projections themselves and to a lesser extent possibly by a degree of lateral resilience of the contact-band when out of the groove.
Although the retention of the contact-band within the groove in the two-part electrical connection of the present invention has some similarity to the teaching of US-A-5,261,840 , it is significantly different insofar as the inclined walls in the two-part connection of the present invention are walls of slots in the floor of the groove rather than walls of the groove itself. This is advantageous for simplifying assembly during manufacture and repair of the two-part connection in that it can be carried out, as described above, by pressing the contact-band downwardly into the groove instead of feeding it lengthwise into the groove.
The need in the prior art of US-A-5,261,840 to feed the contact-band lengthwise into the upwardly-narrowing groove of dovetail cross-section, requires there to be an open end to the groove and for this to be closed once the band is installed. This requirement is of especial disadvantage where one of the contact-parts has the form of a cylindrical plug and the other has a cylindrical socket for receiving the plug, and may lead in these circumstances to compromise of design integrity. It is possible to avoid the requirement in the case of a cylindrical plug by using a groove that is of constant width throughout its depth, and clamping the contact band circumferentially in the groove using spring-wire clips tightly overlying the projections of its border-regions. However, this has disadvantages, in particular of complication in assembly of the connection during manufacture and repair, which are overcome with the present invention.
The outermost wall of each slot of the two-part connection of the invention, may include an inwardly-projecting lip or rim such that retention of the contact-band in the groove is in part by resilient engagement of the outwardly-extending projections of each border-region under the lip or rim of the respective slot.
Foot-extremities of the projections may be configured to engage under the lip or rim, or more especially substantially conformally with the underside of the lip or rim, to enhance retention of the contact-band further.
According to another aspect of the invention there is provided a method of assembly of a two-part electrical connection in which first and second contact-parts of the connection are interconnected electrically via an intermediate, resilient contact-band which has projections that extend outwardly from each of two opposite border-regions of the contact-band, wherein the method comprises the steps of locating the contact-band aligned lengthwise with, but spaced above, a surface-groove of the first contact-part, and pressing the contact-band down into the groove for entry of the projections of each border-region into a respective one of two laterally-spaced slots in the floor of the groove that run lengthwise of the groove, for retention of the contact-band in the groove by resilient engagement of the outwardly-extending projections of each border-region with an outermost wall within the groove, and bringing the first and second contact-parts together into electrical interconnection via the contact-band squeezed resiliently between them, characterised in that the outermost walls with which the projections engage resiliently are the outside walls of the two slots respectively, and that the outermost wall of each slot is inclined to the floor of the groove such that the lateral spacing between the outermost walls of the two slots increases with increasing slot-depht.
The method of assembly may be applied during manufacture or repair of the two-part connection.
An electrical two-part connection, and modifications to it, all in accordance with the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a part of the length of a contact-band used in the two-part electrical connection according to the present invention;
Figure 2 is a section through part of the two-part electrical connection of the present invention showing the contact-band of Figure 1 interconnecting the two contact-parts of the connection;
Figure 3 is illustrative of the configuration in cross-section of the groove of the contact-part that carries the contact-band in the two-part electrical connection of Figure 2;
Figure 4 is an enlarged portion of Figure 3 illustrating details of the cross-section of one of two slots in the floor of the groove shown in Figure 3;
Figures 5(a) and (b) are illustrative respectively of an initial stage of assembly of the contact-band in the two-part electrical connection of Figure 2, and of the resilient deflection of the contact-band in the next stage of assembly; and
Figures 6(a) and (b) are illustrative of a modification in accordance with the invention, of the two-part electrical connection of Figure 2.

Referring to Figure 1, the resilient contact-band 1 used in the example of electrical connection to be described is of a unitary strip-metal structure having a multiplicity of closely-spaced and mutually-parallel lamella-elements 2 which extend between border-regions 3 of the band 1 that interconnect the elements 2 along opposite sides of the strip-metal. Each lamella-element 2 has a central head-portion 4 with two shoulder-portions 5 that link the head-portion 4 to the two border-regions 3 respectively, and is twisted between each shoulder-portion 5 and its adjoining border-region 3 to give resilience to the element 2 with the head-portion 4 inclined upwardly and the shoulder-portions 5 inclined downwardly from the border-regions 3. Each border-region 3 has outwardly-extending projections in the form of resilient legs 6 spaced apart from one another along the length of the band 1.
As illustrated in Figure 2, the contact-band 1 is used for electrical interconnection of two contact-parts 10 and 11 of a two-part electrical connection. In this respect, the band 1 is located within a surface-groove 12 (more clearly shown in Figure 3) of the contact-part 10 with areas of the shoulder-portions 5 of each lamella-element 2 abutting the floor 13 of the groove 12, and the head-portion 4 abutting a surface 14 of the other contact-part 11 of the connection. For example, the contact-parts 10 and 11 may be cooperating contact-plates or -blades of a bus-bar form of connection; examples of such a form are illustrated in, and are described with reference to, Figure 1 of US-A-5, 261, 840 and Figure 1 of US-A-5, 360, 355 . Alternatively, the connection may be of a plug-and-socket form in which the contact-part 10 is a cylindrical plug and the contact-part 11 provides the plug-receiving socket(the section of Figure 2 in this case being taken axially of the plug and socket), or vice versa, and the groove 12 is circumferential externally or internally of the plug and socket respectively, with the band 1 having the form of a ring occupying the full circumference (the cross-section of the cylindrical plug and socket will normally be circular but may be otherwise). Examples of plug-and-socket forms of two-part connections where one of the contact-parts is a cylindrical plug and the other has a plug-receiving socket are illustrated in, and are described with reference to, Figure 7 of US-A-5,261,840 and Figures 6 and 7 of US-A-6,547,607 ; Figure 10 of US-A-5,261,840 illustrates an example of an alternative form of plug-and-socket connection.
In the illustration of Figure 2, the space between the contact-parts 10 and 11 is much exaggerated, and the band 1 in practice is subjected to substantial compression by which the head-portion 4 of each element 2 is squeezed hard against the surface 14 and its shoulder-portions 5 are squeezed hard onto the floor 13 of the groove 12. The resultant areas of strong resilient contact established in this way between the head-portion' 4 and the contact-part 11, and between shoulder-portions 5 and the contact-part 10, and thus between the contact-parts 10 and 11 through each of the multiplicity of elements 2 of the band 1, ensures a multiplicity of parallel paths of low electrical-resistance to enable high-magnitude current-flow between the two parts 10 and 11.
The band 1 is retained in the groove 12 of the contact-part 10 by means of the legs 6. More particularly, the legs 6 of each border-region 3 of the band 1 are engaged in a respective one of two laterally-spaced slots 15 in the floor 13 of the groove 12. The slots 15, which both run throughout the full extent of the groove 12, extend into the floor 13 inclined outwardly to it so that there is a progressively increasing lateral spacing between them with depth; as illustrated in Figure 4 for one of the slots, the outward inclination to the floor 13 may be, for example, 60 degrees. The legs 6 of each border-region 3 extend into the respective slot 15 to engage resiliently against the outermost wall 16 of that slot 15. Owing to the outward inclination with depth, of each slot 15, the engagement of the legs 6 of the respective border-region 3 with the slot 15 is 'under' its outermost wall 16 to the extent that any tendency for withdrawal of any of the legs 6 from that slot 15 is opposed resiliently by the remainder of the band 1.
The contact-band 1 can be engaged in the groove 12 during assembly of the electrical connection by initially entering the legs 6 of both border-regions 3 into the mouths of the respective slots 15 with the band 1 aligned lengthwise with, but straddling, the groove 12, as illustrated in Figure 5(a). Entry of the legs 6 into the mouths of the slots 15 in this way may be eased where, as in this example, the walls 16 of the slots 15 are co-terminus with walls 17 of the surface-groove 12, by bevelling the edges of the walls 17; the walls 17 may be bevelled for example as illustrated in Figure 4 at an angle of 50 degrees. Bevelling of the edges of the walls of the surface-groove in this way in electrical connections of the prior art is not a practical possibility since it would militate against secure retention of the contact-band.
Full engagement of the contact-band 1 in the groove 12 from the initial condition in which the groove 12 is straddled, is achieved simply by pressing the band 1 down into the groove 12. This, as indicated in Figure 5(b), squeezes the legs 6 inwardly towards one another as they are forced to slide down the inclined walls 16 for deflected engagement resiliently under the walls 16 of the slots 15.
The resilient engagement of the legs 6 within the slots 15 on both sides of the contact-band 1 holds the band 1 firmly in place and ensures that good electrical contact is maintained within the two-part electrical connection. However, Figures 6(a) and (b) illustrate a modification that may be used to enhance retention. This involves the provision, as shown in Figure 6(a), of an inwardly-projecting lip or rim 20 to the outermost wall 16 of each slot 15, and, as shown in Figure 6(b), an upwardly-slanted or turned-up foot-extremity 21 to each leg 6 of the contact-band 1. Final assembly of the modified contact-band 1 in the electrical connection in this case, locates the foot-extremity 21 of each leg 6 engaged conformally with the underside of the lip or rim 20 of the relevant slot 15, so as effectively to hook the contact-band 1 resiliently into the groove 12.
Although the contact-band 1 described above is of a unitary form this is not essential to the invention.

Claims

A two-part electrical connection in which first and second contact-parts (10, 11) of the connection are interconnected electrically via an intermediate, resilient contact-band (1) that extends lengthwise within a surface-groove (12) of the first contact-part (10) and has projections (6) which extend outwardly from each of two opposite border-regions (3) of the band (1), wherein the projections (6) from each border-region (3) extend into a respective one of two laterally-spaced slots (15) in the floor (13) of the groove (12) that run lengthwise of the groove (12), the projections (6) of each border-region (3) extending into the respective slot (15) to engage resiliently with an outermost wall (16) within the groove (12) in retention of the contact-band (1) in the groove (12), characterised in that the outermost walls with which the projections (6) engage resiliently are the outside walls (16) of the two slots (15) respectively, and that the outermost wall (16) of each slot (15) is inclined to the floor (13) of the groove (12) such that the lateral spacing between the outermost walls (16) of the two slots (15) increases with increasing slot-depht.
A two-part electric connection according to Claim 1 wherein the contact-band (1) comprises a multiplicity of closely-spaced and mutually-parallel lamella-elements (2) each having a central head-portion (4) for bearing resiliently in electrical contact with the second contact-part (11) and two shoulder-portions (5) through which the head-portion (4) is linked to the two border-regions (3) respectively and which bear resiliently in electrical contact with the floor (13) of the groove (12).
A two-part electrical connection according to Claim 2 wherein the contact-band (1) is of unitary strip-metal structure.
A two-part electrical, connection according to any one of claim 1 to 3 wherein the outermost wall (16) of each slot (15) is inclined at substantially 60 degrees to the floor (13) of the groove (12).
A two-part electrical connection according to any one of claims 1 to 4 wherein the outermost wall (16) of each slot (15) includes an inwardly-projecting lip or rim (20), and retention of the contact-band (1) in the groove (12) is in part by resilient engagement of the outwardly-extending projections (6) of each border-region (3) under the lip or rim (20) of the respective slot (15).
A two-part electrical connection according to claim 5 wherein each projection (6) has a turned-up foot-extremity (21) for engaging under the lip or rim (20) of the respective slot (15).
A two-part electrical connection according to any one of claims 1 to 6 wherein the walls (17) of the surface-groove (12) have bevelled edges.
A two-part electrical connection according to any one of claims 1 to 7 wherein the first and second contact-parts (10,11) are contact-plates or -blades of a bus-bar connection.
A two-part electrical connection according to any one of claims 1 to 7 wherein the first and second contact-parts (10,11) make plug-and-socket interconnection with one another.
A method of assembly of a two-part electrical connection in which first and second contact-parts (10,11) of the connection are interconnected electrically via an intermediate, resilient contact-band (1) which has projections (6) that extend outwardly from each of two opposite border-regions (3) of the contact-band (1), wherein the method comprises the steps of locating the contact-band (1) aligned lengthwise with, but spaced above, a surface-groove (12) of the first contact-part (10), and pressing the contact-band (1) down into the groove (12) for entry of the projections (6) of each border-region (3) into a respective one of two laterally-spaced slots (15) in the floor (13) of the groove (12) that run lengthwise of the groove, for retention of the contact-band (1) in the groove (12) by resilient engagement of the outwardly-extending projections (6) of each border-region (3) with an outermost wall (16) within the groove (12), and bringing the first and second contact-parts (10,11) together into electrical interconnection via the contact-band (1) squeezed resiliently between them, characterised in that the outermost walls with which the projections (6) engage resiliently are the outside walls (16) of the two slots (15) respectively, and that the outermost wall (16) of each slot (15) is inclined to the floor (13) of the groove (12) such that the lateral spacing between the outermost walls (16) of the two slots (15) increases with increasing slot-depht.
A method according to Claim 10 wherein the contact-band (1) comprises a multiplicity of closely-spaced and mutually-parallel lamella-elements (2) each having a central head-portion (4) for bearing resiliently in electrical contact with the second contact-part (11) and two shoulder-portions (5) through which the head-portion (4) is linked to the two border-regions (3) respectively which are for bearing resiliently in electrical contact with the floor (13) of the groove (12).
A method according to claim 10 or claim 11 wherein the outermost wall (16) of each slot (15) includes an inwardly-projecting lip or rim (20), and retention of the contact-band (1) in the groove (12) is in part by resilient engagement of the outwardly-extending projections (6) of each border-region (3) under the lip or rim (20) of the respective slot.
A method according to Claim 12 wherein each projection (6) has a turned-up foot-extremity (21) for engaging under the lip or rim (20) of the respective slot (15) retention of the contact-band (1) in the groove (12).
A method according to any one of Claims 10 to 13 wherein the walls (17) of the surface-groove (12) have bevelled edges for easing entry of the projections into the groove (12).
A method according to any one of Claims 10 to 14 wherein the first and second contact-parts (10,11) are plates or make-plug-and-socket interconnection with one another.