WO2006005277A1

WO2006005277A1 - Capacitor and capacitor module

Info

Publication number: WO2006005277A1
Application number: PCT/DE2004/002244
Authority: WO
Inventors: Michael Setz; Stefan Nowak; Albrecht Hörger; Hubertus Goesmann
Original assignee: Epcos Ag
Priority date: 2004-07-09
Filing date: 2004-10-08
Publication date: 2006-01-19

Abstract

The invention relates to a capacitor comprising a connecting element (3). The aim of the invention is to provide a capacitor that has a low resistance and a high mechanical strength. For this purpose, the connecting element is fastened to the capacitor (1, 2, 21) by laser welding. The invention also relates to a capacitor module.

Description

Capacitor and capacitor module

The invention relates to a capacitor having a connection element and a capacitor module having a plurality of capacitors.

From the document DE 102 18 295 Al and from the document DE 35 18 236 C2 capacitor modules are known in which connection elements are provided which are screwed to a capacitor.

It is an object of the present invention to provide a capacitor which allows a low-resistance contact. It is another object of the present invention to provide a capacitor module, which is characterized by a low ohmic resistance.

These objects are achieved by a capacitor according to claim 1 and 17 or by a capacitor module according to claim 16 and a capacitor arrangement according to claim 30. Advantageous embodiments of the capacitor can be found in the dependent claims.

According to one embodiment of the capacitor, it is provided that a capacitor has a connection element. The connecting element is preferably used for further contacting of the capacitor, for example, the supply of lines in which electrical currents can flow. These electrical currents can be used to charge the capacitor. To the condenser from the outside However, cables brought up can also be used to discharge the capacitor, that is, to take the electric energy stored therein in the form of electrical current from the capacitor.

According to one embodiment of the capacitor, it is provided that a connection element is attached to the capacitor by means of laser welding.

Preferably, the laser welding is performed so that both a part of the connection element and a part of the capacitor is melted. This allows a particularly intimate connection between the two elements can be achieved.

With the help of such an intimate connection advantageously a low contact resistance between the connection element and the capacitor can be achieved.

Furthermore, an intimate connection between the two elements is advantageous because, moreover, a good mechanical connection can also be achieved. This means that a mechanically stable connection of the connection element to the capacitor can be achieved by suitably carrying out the laser welding. Such a connection is particularly advantageous in capacitors which are exposed to external mechanical stresses, for example vibrations in a motor vehicle.

The specified capacitor makes use of the idea of using a laser welding a particularly advantageous connection of a connection element to the capacitor achieve. The specified manner of contacting is particularly suitable for electrochemical double-layer capacitors. Such capacitors are preferably used in motor vehicles as an energetic buffer. By using the laser welding, a connection between the connection element and the capacitor can be generated, which is advantageous both in terms of electrical contact resistance and in terms of mechanical stability.

According to another embodiment of the capacitor, it is provided that the connection element is attached to the housing of the capacitor. For example, a connection element can be fastened to the cover of a cup-shaped housing.

In order to achieve particularly good laser welding properties, it is advantageous if the materials of the connecting element on the one hand and the capacitor or of the part of the capacitor to be welded on the other hand are equal to one another. In particular, the same materials can be used. Advantageously, aluminum is used.

In many cases, the capacitor or its housing made of aluminum. In this case, it is advantageous to also choose the element to be welded made of aluminum, since the connection of other metals or materials to aluminum is difficult. In other cases, a capacitor has a stainless steel housing. In this case, it is advantageous to choose a member to be welded stainless steel.

According to another embodiment of the capacitor, it is provided that the connection element has a thread. Such a thread can preferably be used to connect further electrical contact elements with the capacitor by screws. For example, an electrically conductive sheet or a bus bar can be fastened by means of a screw connection to a capacitor formed in this way.

According to another embodiment of the capacitor, it may be provided that the connection element is fastened to an outer terminal of the capacitor by means of laser welding. In this embodiment, the capacitor therefore has an external connection which is suitable for fastening further connection elements. In particular, such a connection element can also advantageously be used to connect a plurality of capacitors, which in each case have an external connection, to one another electrically conductively and also mechanically stably.

For the laser welding between the connecting element and the outer terminal of the capacitor essentially applies to the laser welding between the connecting element and capacitor itself said.

According to another embodiment of the capacitor can be used as an external connection, an element which in turn is attached by laser welding to the capacitor. A Such an embodiment has the advantage that the current transport, starting from the outside at the connection element and ending at the capacitor itself, in each case runs through laser-welded connections, whereby a particularly low electrical resistance of the capacitor can be ensured.

According to another embodiment of a capacitor, it is provided that a plurality of laser welding points are formed at the connection between a connecting element and the capacitor. Laser welding is a process that is particularly well suited for the pointwise joining of two objects. Typically, in laser welding, a weld point is produced from a melt by melting the materials located near the weld. Several such spot welds can be created spatially close to each other or even at a slightly greater distance from each other in a contact area between the two elements to be welded.

It is particularly advantageous in this context if the region to be welded is easily accessible from the outside, so that the thermal energy required for the laser welding can be supplied from the outside by means of a laser beam without difficulty.

By using a plurality of laser welding points, it can be achieved that the electrical resistance for the transport of current through a connecting element into the capacitor or vice versa can be particularly low. Several adjacent laser welding points can namely as a parallel circuit of electrical resistors or be considered as parallel-connected current paths.

According to another embodiment of a capacitor, it is provided that a further capacitor is attached to a connection element.

Such an embodiment has the advantage that a plurality of capacitors can be connected to one another in a battery or in a module. This connection can be made particularly low impedance, since the advantages of the laser welding both at the contact of the connection element to the first and to the second capacitor each provide a low contact resistance.

According to another embodiment of a capacitor, it is provided that an outer terminal is connected to a housing of a capacitor by means of laser welding. External connections can for example be mounted on lids of cup-shaped housing. Such attachment preferably takes place by means of laser welding on the basis of the advantages already described above with regard to contact resistance and mechanical strength of such a connection.

In this case, the external connection conveys the connection of the capacitor winding usually contained in the capacitor to the outside and an optionally still used connection element ensures that electrical currents can flow from the external terminal of the capacitor into further electrical components. The connection element thus also serves, for example, to connect a capacitor to further electrical components.

According to another embodiment of a capacitor, it is provided that an external connection is part of a housing of a capacitor. Such an embodiment is an alternative to the embodiment just described. That is, in this case, the external connection does not have to be connected as a separate part to the housing, but the external connection can be integrally integrated in a part of the housing. For example, the cover of a cup-shaped housing by corresponding projections, beads or other shapes may be designed so that the lid itself as part of the housing at the same time as an external connection for connecting further electrical contact elements, is suitable.

According to another embodiment of the capacitor, it is provided that an outer terminal has a projection which engages in a recess of a connection element. By using such a fitting of the outer terminal in a connection element, an additional improvement of the mechanical stability can be achieved.

In addition, such an embodiment has the advantage that a battery of a plurality of juxtaposed capacitors, each having on the top connecting elements, by simply placing a hole having connecting element and subsequent laser welding is made. According to another embodiment of a capacitor, it is provided that a recess of the connecting element is a hole. Such a hole has the advantage that an external connection can be made from one side of the connection element and that the laser welding can take place from the other side.

This means that when using a hole as a recess in particular the advantage results that an arranged in the hole outer terminal is accessible from the opposite side of the connecting element ago.

According to another embodiment of the capacitor, it is provided that laser welding points are arranged along a line. This has the advantage that the laser welding can take place in a region in which different elements abut each other, so that by targeted positioning of a laser beam material of both the one and the other element material can be melted, resulting in a

Laser welding connection or positioning a laser welding point with good electrical and mechanical properties leads. The melt formed from the two elements can mix and thus lead to an intimate connection of the two elements, for example the connection element and the capacitor or an external connection.

According to another embodiment, it is provided that the number of welding points is selected so that it is adapted to a predetermined current carrying capacity. This means that at a given current and in about the previously known Current carrying capacity of a single weld point, the number of welds can be selected so that the desired current carrying capacity is achieved. For very large currents, for example, capacitor capacitors are specified here, which can absorb or deliver several amps of power, the number of welds must be 100, 200 or even 1000.

The current carrying capacity of a single welding point is added to the current carrying capacity of the other welding points due to the electrical parallel connection of the currents flowing through the welding points.

The number of welding points depends on the required total conductor cross section, which is given by the sum of individual conductor cross sections of individual laser welding points. This in turn depends on the laser power and the cross-sectional area of the laser focus.

According to another embodiment of a capacitor, it is provided that an external connection is a flow-molded part. Extruded parts have the advantage that they are particularly good laser weldable.

Accordingly, it is particularly advantageous if a connection element is a flow press.

Moreover, it is advantageous if the outer terminal and connecting element each contain aluminum.

Preferably, an aluminum of purity 99.5 is used. But it can also be another suitable material, such as stainless steel can be used.

In addition, a capacitor module is specified, which contains a plurality of capacitors. The capacitors are at least partially connected to one another by a connection element, wherein the connection of the connection element to each of the capacitors connected thereto is produced by laser welding.

Such an approach is particularly advantageous in capacitor modules where multiple capacitors are connected in series. In this case, the contact resistances also add up in series. Are the contact resistances also in series with each other and add up accordingly. In such a case, it is particularly important that the contact resistance between a connecting element and the capacitors involved is particularly low.

In a capacitor module, however, the capacitors may just as well be present in a parallel circuit or else in a mixed series / parallel circuit.

In addition, a capacitor is proposed, which has at least one outer terminal with at least one fixing element, wherein at least one attached to the outer terminal connecting element is provided, which has a circular recess into which engages the fixing element.

According to one embodiment of the invention, the at least one fixing element engages in the Connection element, that when the external connection is held a rotation of the capacitor around its longitudinal axis is possible.

Such a capacitor has the advantage that it can be rotated in any orientation about its longitudinal axis, without causing the position of the connecting element must be changed.

The fixing element is preferably a projection which is at least partially elastic. In this way, a particularly secure latching of the connection element to the outer connection of the capacitor can be achieved.

The outer terminal may be formed with a plurality of fixing elements in the form of protrusions of the type mentioned. These are preferably arranged concentrically about a central axis.

The capacitor may preferably be firmly connected to the connection element after the definition of a suitable orientation for its application. This is preferably done by welding and / or soldering.

Furthermore, a capacitor arrangement is proposed in which a first and a second capacitor are present, wherein the first capacitor has at least one outer terminal formed with at least one fixing element. The connecting element is attached to the outer terminal of the first capacitor and to the second capacitor and has at least one circular recess into which engages the fixing element of the first capacitor. Preferably this takes effect Fixing element in such a way in the connection element, that a rotation of the first capacitor according to the type mentioned is made possible.

Also, the second capacitor may have an external connection as in the first capacitor, in which case the connecting element has two circular recesses, wherein the fixing element of one of the two capacitors engages in each recess. It is also preferred that a rotation of said type of the second capacitor is made possible.

Along with the rotation of the capacitors about their own longitudinal axes when attached to the terminal, the positioning of a second capacitor to be connected to the first can be freely selected along a particular arc. This is possible because the connection element can be freely rotated around both capacitors.

In the following, a capacitor or a capacitor module will be explained in more detail with reference to embodiments and the accompanying drawings.

FIG. 1 shows a capacitor in a schematic cross section.

FIG. 2 shows a section through the condenser from FIG. 1 along the line II-II.

FIG. 3 shows a capacitor module in a schematic cross section. FIG. 4 shows a section through the module from FIG. 3 along the line IV-IV.

FIG. 5 shows two capacitors with a position-independent connection element.

FIG. 6 shows the engagement of fixing elements arranged on the capacitors in the recesses of a connecting element.

Elements which are identical or which have the same function are designated by the same reference numerals. The figures are not to scale, but distorted due to the better representation.

FIG. 1 shows a capacitor 1 which has a housing 41 on its outside. On the upper side of the housing 41, a recess is arranged. In the recess, a connection element 3 is arranged. The connecting element 3 is provided with a thread 5, which is arranged on a pin. At the top of the housing 41, at the point where the connection element 3 and the housing 41 touch each other, weld points 6 are attached to the transition point. These welds 6 are produced by laser welding. They allow a low electrical contact resistance between the connection element 3 and the housing 41.

FIG. 2 shows the arrangement of several spot welds 6 in one plane. It can be seen that the welding points are arranged along a line, wherein the distance between the welding points 6 may well vary. The welding points can produce a low-resistance and mechanically stable connection with a sufficiently large cross-section. At the same time, a connection can be made that causes only a low heat input, so that the capacitor 1 is not damaged or even destroyed. In particular, the method of laser welding can be applied to single double-layer capacitors or even to modules containing any number of interconnected single capacitors. Here an interconnection with extremely low internal resistance can be realized.

FIG. 3 shows a capacitor module with a first capacitor 1 and a second capacitor 2. An external contact 7 is arranged on the upper side of each capacitor 1, 2. In the left capacitor 1, the external contact 7 forms the positive pole, while in the right capacitor 2 the external contact 7 forms the negative pole. In the left capacitor 1, the housing 41 forms the negative pole of the capacitor. In the right capacitor, the housing 42 forms the positive pole. By connecting element 3, the negative pole of the right capacitor is connected to the positive pole of the left capacitor 1. Schematically, on the left side of Figure 3, yet another capacitor 21 is shown, the negative pole is disposed on the top and the positive pole on the housing. The housing of the capacitor 21 is welded to the housing of the capacitor 1, so that a total of a series connection of the three capacitors 1, 2, 21 results. The arrangement of the poles in a capacitor can be adjusted in the case of double-layer electrolytic capacitors by a corresponding applied poling voltage. The first external terminals, which are electrically insulated from the housing, generally serve to contact the capacitors located in the housing, which are in the form of capacitor films, for example. As a rule, capacitors consist of two electrode layers, between which a porous separator is arranged. Both the separator and the electrode layers are in contact with an electrolyte solution. The layer arrangements of the electrode layers and the separators can be rolled up to capacitor windings.

The capacitors 1, 2 have external connections 7, which are connected to the housings of the capacitors 1 and 2 either by laser welding by means of spot welds 6 (compare, in particular, the right-hand side of the capacitor 2) or by other attachment methods. An external connection 7 can also be part of the housing of the capacitor itself.

The connection element has the form of a busbar, which can carry currents of a few amperes or even 10 A. The busbar has at the locations of the external terminals 7 recesses 8, which are designed in the example of Figure 3 as holes. The outer terminals 7 have projections 71 which engage in the recesses 8 of the connecting element 3. At the contact point between the connection element 3 and the respective projection 71, welding spots 6 are produced, which are produced by laser welding. By means of these welding points 6, the connection element 3 is connected to the capacitors 1 and 2. The welding points 6 are located on top of the capacitor arrangement, so that they are easily accessible from the outside are and can be made by simply applying a laser beam.

FIG. 4 shows the arrangement of the welding spots 6 for the left-hand capacitor 1 and for the right-hand capacitor 2. In the region of the left-hand capacitor 1, the welding points which connect the connecting element 3 to the projection 71 are arranged at a relatively large distance from each other, but regularly. The currents flowing through the welding points 6 add up to a total current, which is transported by the connecting element 3 into the capacitor.

On the right side of Figure 4, the arrangement of the welds 6 for the second capacitor 2 can be seen. Here are the welds 6 very close, which can be transported in this area a very high current with low resistance.

FIG. 5 shows a first capacitor 1, which is connected by means of a connecting element 3 to a further, second capacitor 2. The capacitors 1, 2 each have external terminals 7 with circular cross-sections, and are designed as connecting pins. They also have one or more, sometimes elastic

Fixing elements in the form of protrusions 71, which are formed with flares, steps or flanges. It is advantageous if the projections have radially outwardly directed hooks at the free end, which may be sharp or abyssal.

It is also possible that only one fixing element is provided, which preferably at the free end a radially outwardly directed, elastic and as a hook serving wings. The fixing element may be formed as a projecting ring.

The connecting element 3 connecting the capacitors consists of an electrically conductive metal or sheet, from which recesses 8 are punched in the form of holes such that the external terminals 7 of the capacitors can engage in the recesses. However, it is not inevitable that holes are removed. Instead, the recesses may also be realized as circular depressions of a metal or sheet metal connector.

The engagement of the external terminals 7 takes place by means of the elastic projections 71 in the manner of a snap connection. In this case, the connection element 3 or the recesses 8 in the form of holes of the connection element is pushed onto the fixing element or onto the projections such that they yield radially inward. The connection element is pressed further until it has passed the hooks of the projections, the projections snap back into the original position and the connection element rests on a flange, a step or a flange of the projections. Thus, the connection element 3 is securely locked to the outer terminal.

It is preferred that the connection element 3 after its mounting on the outer terminal 7 of a capacitor 1.2 has a rotational clearance. On the basis of the rotational clearance, the connection element 3 can be rotated in an already mounted on an external connection state, so that the position of a second capacitor 2, which is to be attached to the connection element, along a circular arc A, B can be arbitrarily selected with a certain radius. The radius is the distance between the centers of the two Recesses 8 of the connection element or alternatively, if the connection element is provided with only one recess, the distance between the center of this recess and the point of contacting the connection element with a second capacitor. 2

Not only is a free positioning (due to the dimensions of the connection element) of the capacitors relative to each other possible, but also the orientation of the capacitors themselves. A rotation of the capacitors is also possible if the capacitors already connected to each other by the connection element, but not yet soldered / welded. They can therefore be rotated in each case in an orientation in which they can be contacted for example optimally with a power rail or another connection.

Depending on the requirements, it may be favorable to design the connection element 3 with only one recess 8 into which an outer connection 7 of only one capacitor 1 engages. Thus, the external connection of a second or further capacitor 2 may be formed as desired and the connection between the connection element 3 and the second capacitor 2 done in any way, for example by means of a screw or clamp connection. Thus, further capacitors with different external connection types compared to the first capacitor can advantageously be connected to the first capacitor. The possibility of a free positioning of the second capacitor along a circular arc relative to the first capacitor still exists. The mechanical connection between the external connection 7 and the connection element 3 is preferably supplemented or strengthened by means of a connection in which the materials of the external connection and of the connection element merge into one another. In this case, soldering and / or welding connections are particularly favorable, in particular laser welding connections. The mechanical connection of the connection element to the external connection by means of welding or soldering technology is preferably carried out after the desired orientations and positioning of the rotatable capacitors has taken place. Such compounds have the advantage that they are low impedance. The soldering or welding is preferably carried out at one or more contact points between the connection element 3 and the projections 71 of the external terminals 7 of the capacitors.

It is preferred that at least one of the capacitors has a housing 41 with a top and a bottom or bottom side. The outer terminal 7 is preferably attached to the top of the capacitor 41, wherein on the bottom side of the housing, a preferably be contacted with another capacitor busbar 3 'can be arranged. However, it is also possible to form an outer terminal 7 of the type mentioned on both the upper and on the bottom side of the housing. Thus, one or more capacitors can also be attached to the bottom of a connection element 3.

FIG. 6 shows how a connection element 3 with two round recesses 8 is mounted on two capacitors 1, 2 of a capacitor arrangement. The outer terminals are arranged with a plurality of concentric about a central axis or a central point, protruding Fixing elements 71 are formed, which engage in the recesses of the connecting element. On the bottom side of the capacitors each busbars 3 ^λ are arranged. The arrows A and B each show the possibility of rotation of a first capacitor 1 about its axis and the circular arc, along which the second capacitor 2 can be positioned.

The present invention is not limited to individual capacitors and not to double-layer capacitors. It is applicable to all possible capacitors as well as to series connections, parallel connection and mixed interconnections of several capacitors with each other.

Reference sign list

1, 2, 21 capacitor

3 connection element

41, 42 housing

5 threads

6 welding point

7 external connection

71 lead

8 recess

A, B circular arc

Claims

claims

1. capacitor, with a connection element (3) which is fixed by means of laser welding to the capacitor (1, 2, 21).

2. A capacitor according to claim 1, wherein the connection element (3) on the housing (41, 42) of a capacitor (I ₇ 2, 21) is attached.

3. A capacitor according to any one of claims 1 or 2, wherein the connecting element (3) has a thread (5).

4. A capacitor according to claim 1, wherein the connection element (3) on an outer terminal (7) of a capacitor (I ₇ 2, 21) is fixed by means of laser welding.

5. A capacitor according to any one of claims 1 to 4, wherein at the connection between a connecting element (3) and the capacitor (I ₇ 2, 21) a plurality of laser welding points (6) are formed, which form parallel-connected current paths.

6. A capacitor according to any one of claims 1 to 5, wherein on the connection element (3), a further capacitor (1, 2, 21) is attached.

7. A capacitor according to any one of claims 4 to 6, wherein an outer terminal (7) by means of laser welding to a housing (41, 42) of a capacitor (I ₇ 2, 21) is connected.

8. A capacitor according to any one of claims 4 to 6, in which an external connection (7) is part of a housing (41, 42) of a capacitor (1, 2, 21).

9. A capacitor according to any one of claims 4 to 8, wherein an outer terminal (7) has a projection (71) which engages in a recess (8) of a connection element (3).

10. A capacitor according to claim 9, wherein the recess (8) of a connecting element (3) is a hole.

11. A capacitor according to any one of claims 5 to 10, wherein the laser welding points (6) are arranged along a line.

12. A capacitor according to any one of claims 5 to 11, wherein the number of welding points (6) is adapted to a predetermined current carrying capacity.

13. A capacitor according to any one of claims 4 to 12, wherein an outer terminal (7) is a flow press.

14. A capacitor according to any one of claims 1 to 13, wherein a connecting element (3) is a flow press.

15. A capacitor according to any one of claims 1 to 14, wherein an outer terminal (7) and a connection element (3) contain aluminum.

16. A capacitor module, comprising a plurality of capacitors (1, 2, 21) according to any one of claims 1 to 15, by one or more Connection elements (3) are interconnected in a series or parallel connection.

17. A capacitor, comprising: at least one outer terminal (7) formed with at least one fixing element (71), at least one connecting element (3) which is fastened to the outer terminal, and has a circular recess (8) into which the

Locking element engages.

18. A capacitor according to claim 17, wherein the connecting element (3) by means of a welding, soldering or laser welding connection to the outer terminal (7) is attached.

19. A capacitor according to claim 17, wherein the fixing element of the outer terminal engages in the connection element in such a way that when the outer connection is held, a rotation of the capacitor about its longitudinal axis is made possible.

20. A capacitor according to any one of claims 17 to 19, wherein the connecting element (3) with the outer terminal (7) is latched.

21. A capacitor according to claim any one of claims 17 to 20, wherein at least a part of the fixing element

(71) is elastic.

22. A capacitor according to claim 21, wherein the elastic part of the fixing elements (71) is connected to the connection element (3).

23. A capacitor according to any one of claims 17 to 22, wherein the fixing element (71) is a projection.

24. A capacitor according to any one of claims 17 to 23, wherein the fixing element (71) has an outwardly directed hook.

25. A capacitor according to any one of claims 17 to 24, wherein the outer terminal comprises a plurality of fixing elements (71).

26. A capacitor according to claim 25, wherein the fixing elements (71) are arranged concentrically around a central longitudinal axis of the capacitor.

27. A capacitor according to any one of claims 17 to 26, wherein the outer terminal (7) is arranged on an upper side of a housing (41) of the capacitor.

28. A capacitor according to any one of claims 17 to 27, wherein a further outer terminal (7) is arranged on a bottom side of a housing (41) of the capacitor.

29. A capacitor according to any one of claims 17 to 28, wherein a bus bar (3 ^Λ ) on the bottom side of the housing (41) is fixed.

30. capacitor assembly comprising: a first and a second capacitor (1, 2), the first capacitor (1) having at least one outer terminal (7) formed with at least one fixing element (71), at least one connecting element (3)

- Is attached to the outer terminal of the first capacitor and the second capacitor (2), and

- At least one circular recess (8), in which engages the fixing element of the first capacitor.

31. The capacitor arrangement according to claim 30, wherein the fixing element of the first capacitor engages in the recess in such a way that, when the connection element is held stationary, a rotation of the capacitor about its longitudinal axis is made possible.

32. The capacitor arrangement according to claim 30, wherein the second capacitor has at least one outer terminal formed with at least one fixing element, the connecting element has a second circular recess which engages the fixing element of the second capacitor.

33. The capacitor arrangement according to claim 32, wherein the fixing element (71) engages in the recess (8) in such a way that, when the connection element (3) is held stationary, a rotation of the second capacitor (2) about its longitudinal axis is made possible.

34. Capacitor arrangement according to one of claims 30 to

33, wherein the fixing element (71) is a projection.

35. Capacitor arrangement according to one of claims 30 to

34, wherein the outer terminal (7) has a plurality of fixing elements (71).

36. A capacitor assembly according to claim 35, wherein the fixing elements (71) are arranged concentrically about a central axis.