Abstract:
An electric energy storage component having coil windings and at least one connector. A plate of the connector is in contact with the coil windings. The plate of the connector has a surface which is provided with a terminal wherein the shape thereof is essentially that of a revolution. The plate also forms a series of bosses extending in a raised manner along a surface of the plate opposite to that containing the terminal. The terminal has at least one inner recess and at least one boss which penetrates into the recess.

Description:
The present patent application is a non-provisional application of International Application No. PCT/FR2005/001425, filed Jun. 9, 2005. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to electrical connection and external casing arrangements for electric energy storage components (batteries, capacitors, for example capacitors of the electrochemical type) and notably for supercapacitors. 
     2. Description of Related Art 
     An electric energy storage component, notably a supercapacitor, appears as a winding of several material layers with, jutting out from each end of the winding, a sheet based on aluminium, called a collector, and which enables the current to be drained outwards. This collector should be electrically connected to an electric connection terminal which is part of the global supercapacitor casing, either in its cover, or in its case. 
     Welding the collector onto the connector of the terminal by a weld is known, possibly by a laser weld on the bottom of bosses made in the connector. 
     But a supercapacitor generates strong charge or discharge currents on the sections of this collector which is relatively soft, because it is relatively thin, so that a maximum of (surface) sections have to be connected to the terminal or to the cover or to the case, in order to limit the resulting electric connection resistance and therefore heat build-up, notably at the interface between the sections of the collector and the connector. 
     For reasons of performances, but also for the simplicity of application, and reasons of cost, the terminal should ideally be an integral part of the cover or case to which the collector is connected electrically, and not added to the latter by another process step. 
     The terminal is not part of the cover in the existing solutions (commercial products). 
     Moreover, it is difficult to reconcile on a same part (cover, case), a current-collecting central terminal as wide as possible, and a weld in bosses attaining the turns of the centre of the winding, as much as possible. 
     Indeed, a central terminal should be as superficial as possible (sufficient sectional area for collecting current and letting it flow through) and it therefore occupies a certain surface area at the centre of the cover which may limit accessibility to the bosses and prevent laser shots from reaching the turns of the centre. 
     In the prior art, the terminal is, for this reason, often treated separately and added to the cover or to the bottom of the case, which allows both aspects to be reconciled. 
     But this requires that they be subsequently connected in order to provide the whole of the required functions. From an electrical point of view, this connection generates an additional series resistance detrimental to the properties of the supercapacitor, a process step and therefore a cost, and also additional mechanical brittleness. 
     The terminals added to the cover or the case by a laser weld, are thus found to have brittleness of the connection between both parts. Jamming two cones with each other for attaching the terminal is of course suggested, but such jamming increases heat build-ups by the surface contact resistance at the interface between both mutually jammed parts. Moreover, fitting of the parts should then be perfect, which generates significant machining costs. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the invention is to facilitate contact of the connector with the sections of the innermost turns of an electric storage component winding, while providing sufficient space for a central terminal with a substantially circular contour, notably made in the same material as the connector. 
     This object is achieved according to the invention by means of an electric energy storage component including a winding of turns, and at least one connector including a plate in contact with a plurality of these turns, the connector plate having a face provided with a terminal of a substantially axisymmetric shape, the plate further forming a series of bosses which extend in a raised manner along a face of the plate opposite to that bearing the terminal, characterized in that the terminal has at least one inner recess and in that at least one boss penetrates into such a recess. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features, objects and advantages of the invention will become apparent upon reading the detailed description which will follow, made with reference to the appended figures wherein: 
         FIG. 1  is a perspective view of a connector according to a first embodiment of the invention; 
         FIG. 2  is a top view of this same connector; 
         FIG. 3  is a perspective and underside view of this same connector; 
         FIG. 4  illustrates a first method for welding this connector on a storage winding; 
         FIG. 5  is a top view of this first method for welding this connector; 
         FIG. 6  illustrates a second method for welding this connector; 
         FIG. 7  is a side view illustrating a method for attaching such a connector on a supercapacitor case component; 
         FIG. 8  is a top view of a connector according a second embodiment of the invention; 
         FIG. 9  is a side view of this same connector; 
         FIG. 10  is a top view of a connector according to a third embodiment of the invention; 
         FIG. 11  is a top view of a connector according to a fourth embodiment of the invention; 
         FIG. 12  is a side view of this same connector; 
         FIG. 13  is a top view of a connector according to a fifth embodiment of the invention. 
         FIG. 14  is a top view of a connector according to a sixth embodiment of the invention. 
         FIG. 15  is a side view of the connector of the sixth embodiment. 
         FIG. 16  is a top view of a connector according to a seventh embodiment of the invention. 
         FIG. 17  is a side view of the seventh embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The connector of  FIG. 1  is a one-piece part, here in aluminium, including both a plate  100  intended for covering and contacting turns of a supercapacitor winding, and an upper trunnion  200  rising in the central portion of this plate in order to form the outer connection terminal of a supercapacitor. 
     The cover plate is a disk with a contour substantially matching that of the winding to be covered, this contour being provided here with a groove  110  intended for receiving a gasket for sealing the supercapacitor. 
     This plate has a series of deformations or bosses  120 ,  125  which rise and form a relief on a lower face of the plate  100 , i.e., on the face opposite to the one where the external connection terminal  200  rises. 
     These bosses have a small height relatively to that of the terminal  200  but most of them have sufficient extent in order to radially cross a majority of the turns of the winding. 
     In order to contact a maximum of these sections, the bosses  120 ,  125  each extend transversely to these sections, i.e., every time along a radius of the connector. 
     Certain bosses  120  extend over a majority of the length of the relevant radius. These bosses  120  with maximum radial extent are here four in number, and are placed at 90° relatively to each other around the terminal  200 . These long bosses  120  will be designated subsequently as &lt;&lt;main bosses&gt;&gt; because of their electric function consisting of collecting a maximum of the amount of current available upon contacting the turns of the winding. 
     Four other bosses  125 , called &lt;&lt;complementary bosses&gt;&gt;  125  hereafter, although they are also oriented radially, are limited in their extent upon crossing a peripheral edge area of the plate  100  in order to collect the current from the winding only on this peripheral edge area. 
     By this function consisting of collecting the current only on the peripheral edge, these complementary bosses  125  balance the electric flux in the collector, for better efficiency in the role of the collector and for reducing its global electric resistance. 
     The ratio of the length between the complementary bosses  125  and the main bosses  120  is advantageously selected in order to distribute at best the current in the coil and thereby balance the heat build-up areas. 
     The complementary bosses  125  may be welded for applications with a strong average current (for example cycling applications in hybrid or electric transportation) and may not be welded for applications with a weak average current (for example in so-called floating applications or uninterrupted power supplies. 
     The cover comprising this connector may include several main  120  and complementary  125  bosses per angle of 90° in order to increase the weld section with the coil. 
     The terminal  200  described here, therefore belongs to the family of terminals which have substantially an axisymmetric shape, i.e., an outer contour at least partly inscribed on a circle. 
     It will be noted that a delimitation circle may be constant over the height of the terminal or increasing towards the base of this terminal which gives the latter a shape which is at least partly frustro-conical, according to the arrangements specified hereafter. 
     The substantially axisymmetric shape is suitable for receiving a lug of the clamping collar type, typically associated with such a terminal. 
     With a substantially axisymmetric shape, it is also possible to obtain an upper surface adapted so as to cooperate with a planar lug, for example itself attached by means of peripheral clamping. 
     The axisymmetric shape, even if it is only partial, is also advantageous because it is well suited for bearing an outer thread for attaching a lug of the &lt;&lt;screw-in &gt;&gt; type. 
     It is then also possible to screw a nut thereon in order to tighten a flat lug against the surface of the cover plate of the collector. 
     Such a terminal  200  may also have an inner tapped thread for fitting or screwing a male connector. 
     The terminal  200  shown here is however provided with four recesses  210 , distributed at 90° from each other and each extending over the whole height of the terminal  200 . 
     Consequently, the terminal  200  as viewed from above has the shape of a cross with orthogonal branches  220 . 
     The recesses  210  each have a bottom wall  215  with a curved shape, i.e., as an arc of circle when viewed from above, if they are made by a stamping-extrusion process. 
     More specifically, each recess bottom wall  215  is configured as a frustrum so that the recess widens from the bottom to the top. Conversely, each branch, delimited by two recesses, widens upon travelling down the latter from top to bottom (from its end to its base). 
     The main bosses  120  will each extend up to the very contact of the bottom wall of an associated recess  210 . 
     The main bosses  120  themselves have sloped side walls  122  and this notably at their inner end at the terminal  200 , these side walls forming a clearance surface during the cover manufacturing process. 
     Each main boss inner end wall will consequently lie directly in the extension of the bottom wall  215  of the relevant recess  210 . 
     The complementary bosses  125  as for them break off more or less significantly at a distance from the periphery of the terminal  200 . 
     The walls of the terminal which are the closest to the complementary bosses  125 , i.e., the ends  225  of the branches  220  of the terminal  220 , are themselves frustro-conical. 
     With the recesses  210 , a terminal with a large radius may be made simultaneously with long range bosses towards the centre of the cover. 
     These arrangements further allow extended welding of the cover on the innermost windings. 
     Such a welding is carried out at the bottom walls of the bosses  120 ,  125  which are in contact with the turns of the windings. Among the possible welding techniques, welding with laser shots on the bottom of the bosses is what gives the best results. 
     Thus, with the cover described here, the boss may be welded on the winding as well as in the most central portions of the collector, i.e., actually inside the circular contour delimiting the terminal. 
     A laser beam  300  ( FIG. 4 ) is typically point-like at its tip, while however exhibiting a certain width along a portion of its travel. 
     In order that the tip of the beam  300  may penetrate into the recesses of the terminal without the beam being interrupted in its travel portion, the inner frustro-conical walls  215  of the recesses  210  are sufficiently sloped in order to receive the whole laser beam  300 . 
     Alternatively, recesses  210  are provided, the contour  215  of which is sufficiently wide for including the laser beam  300  in its widest portion, i.e., at the upper limit of the terminal  200  ( FIG. 5 ). 
     Another embodiment ( FIG. 6 ) consists of slightly tilting the laser beam  300  so that its conical shape only approaches the terminal  200  at its tip  310 . 
     In spite of the truncation of the terminal  200 , the contact surface remains amply satisfactory here with a surface area of the order of 365 mm 2  (for an initial terminal with a base diameter of 18 mm, a top diameter of 17 mm, and with a height of 20 mm, and ⅔ truncated) allowing a nominal DC current of about 900 A without excessive heating. 
     As a comparison, an equivalent solid frustro-conical terminal has a contact surface of 1,100 mm 2 , i.e., a nominal DC current of 2,750 A in an aluminium type material (2.5 A/mm 2  without excessive heating. 
     The fact of only having here a single part including plate, bosses and terminal, produced from a same block of material and which provides both inner and outer connection functions, simplifies the assembling and reduces the cost of the complete component. 
     The present cover is sealed at its periphery by means of seal gasket onto which the edge  410  of the case  400  ( FIG. 7 ) is folded. As discussed earlier, this collector has a projecting edge  110  for blocking such a gasket during the closing operation. 
     This cover may include any other type of edge capable of being used for closing the component (crimping, welding, etc.). 
     The connector has two excentered holes  130  for letting through an electrolyte after this closing operation so as to allow impregnation of the winding of the supercapacitor by the electrolyte after closing the casing (case, or tube+covers(s)). Both holes  130  are then hermetically blocked, by any known means. 
     This connector is also provided on its inner face, with a network of grooves  140  which form a space for the flow of electrolyte between the winding and the connector, in order to assist impregnation. 
     In the alternative of  FIG. 8 , a central terminal  200  is proposed, with an essentially axisymmetric shape, and even, more specifically, externally frustro-conical and the base of which, with a substantially circular contour, is recessed so that the main bosses  120  may penetrate as close as possible to the centre of the turns, inside the terminal. 
     In this alternative, laser shooting is advantageously carried out at an angle in order to reach the end of the bosses  120  ( FIG. 9 ). 
     Advantageously, the recesses  210  here have an inner wall  215  with a section, considered parallel to the covering plate, with an oval shape. By this oval shape, the side walls of each recess  210  will laterally come closer to the boss  120  so as to edge it very close here, in a substantially parallel way. 
     Consequently, the terminal  200  forms branches  220  which each tend to widen when running outwards. 
     Thus, the terminal when it is observed as a section parallel to the covering plate  100 , has in a planar section the shape of a cross, a so-called “cross patee” (in heraldry), the branches of which  220  widen and are curved at a distance from the centre in order to form at their end  225 , a widening with pointed edges  216  and  215 . 
     In other words, each branch has two opposite side tips  216  and  217  which separate from each other, the ends of the branches however remaining inscribed on a circle. 
     This shape gives the terminal  200  a wide peripheral section formed by the widened ends of each of the branches  220 , while it also allows marked penetration of each boss  120  within the axisymmetric shape. 
     There again, this terminal  200  is frustro-conical, the recesses  210  being provided here only on the half of the height of this terminal, i.e., on the half adjacent to the covering plate  160 . 
     In this embodiment, the terminal is also in a single piece with the covering plate, as a single aluminium part. 
     There again, a peripheral surface and a section of large surface area may be obtained with the recesses  210  provided in this terminal  200 . 
     In the alternative illustrated in  FIG. 10 , the terminal  200 , instead of being solid in its central portion, there consists exclusively of four branches  220 , not connected to each other, except by the covering plate  100  of the collector. 
     The contact surface between a lug with an upper contact and the terminal  200  is certainly reduced, but remains sufficient in this alternative as well. 
     With the recess at the centre  230 , the bosses  120  may come closer together, even closer to the centre, or even be continuous upon crossing the plate  100 . 
     Moreover, with this alternative, an impregnation port  130  may be inserted at the very centre of the plate  100 . 
     Here also, the branches  220  have an end surface with a frustro-conical shape in order to promote connections by a lug with peripheral clamping. 
     Also in this case, the branches  220  have a width which increases when running along a branch from the inside to the outside of the terminal, with substantially rectilinear branch edges when observed in a section parallel to the plate. 
     In order to guarantee the connection, it is advantageous to insert a central spacer at the centre of the branches  220  in order to strengthen the whole under the effect of the peripheral clamping. 
     The number of branches  220  may be different, for example three (spaced out by 120°), for gaining space, material and simplicity in the making. The number of branches may also be X, with X larger than 4, with a spacing of (360/X°). 
     It is also possible to make branches which are not spaced out regularly, even if this tends to “de-homogenize” the flow of the current in the coil and therefore unbalance the component as regards heat build-up and ageing. 
     In the alternative of  FIGS. 11 and 12 , a ring-shaped terminal  200  is proposed, i.e., having the shape of a concentric cylinder with the tubular cover, this cylinder advantageously has recesses at its base to let the bosses pass through to the interior of the cylinder. 
     Its radius is sufficiently large for providing a sufficient contact peripheral surface, and simultaneously, with the space left at the centre, the bosses may attain the most central turns. 
     An impregnation hole  130  is provided here at the centre of the plate  100  inside the terminal  200 . 
     In the alternative of  FIG. 13 , benefit is drawn from the fact that the external turns drain more current than the turns of the centre. 
     Now, for a relevant turn, a weld by a laser shot perpendicular to this turn provides a boss/turn contact surface which is the same whether the turn is external or internal. 
     Application of a weld which on the contrary generates a contact surface which is much larger for the external turns than for the internal turns, is desired here. 
     A means for providing such a result is to form the bottom of the bosses in a conical way, i.e., with a lower contact surface which is wider in the external portion of the collector, in order to have more surface of the collector in contact towards the outside of the latter. 
     Here, however, in order to increase the welding surface at the external turns, and this with a single laser shot, a spiral boss  120  is adopted which tends to be tangent to the turns outwards. More generally, a boss is achieved, the direction of which gradually deviates from a radial orientation. Thus, the closer the laser ray approaches from the outside, the larger is the welded section of the collector, because crossing between boss and turn is increasingly more tangential. 
     In a quite different approach, a terminal with branches, the number of branches of which may be two (spaced by 180°) or even a terminal in the shape of a rectangular parallelepiped  400  ( FIGS. 14 and 15 ) will be mentioned. The latter then extends between bosses of the main type. 
     This terminal for example includes a port  410  for screwing or is directly welded on a current-collecting bar. 
     In order to allow the bosses to access the turns of the centre, while keeping a terminal integrated to the cover, an even different approach is to excenter the terminal in an area located between the bosses (terminal  500  in  FIGS. 16 and 17 ). 
     This configuration has the disadvantage of unbalancing the current flow in the relevant storage component. 
     A second excentered terminal of the same type and diametrically opposite to the first, or even several other excentered terminals are advantageously added in order to homogenize the current flow in the collector without paying any penalty for welding all the turns.