DE102004063559B4 - Electrochemical cell with good heat dissipation - Google Patents

Abstract

Electrochemical cell,
with a housing (20) and a capacitor winding (10) arranged therein,
a heat dissipator (3) thermally connecting a portion of a side wall of the housing (20) to the capacitor winding (10),
wherein the heat dissipator (3) is formed as a cap, which is placed on the capacitor winding (10),
wherein a terminal (41, 42) of the cell is guided through an opening formed in the cap.

Description

The The invention relates to an electrochemical cell, in particular a Electrolytic capacitor with a cup-shaped housing.

From the publication DE 199 29 598 A1 An electrolytic capacitor with a packaged capacitor winding is known. The capacitor winding can be fixed in the housing in that after insertion of the capacitor winding center beads are produced in the housing, which fix the capacitor winding in the radial direction. These middle beads are subsequently applied, for example by means of a book with an embossing stamp.

By an AC load is placed in an electrochemical cell Generates heat, can affect the electrical parameters of the cell.

Other capacitors with a capacitor winding in a housing are from the publications DE 10251230 A1 JP 2004-304057 A, US 4459641 A . US 6021040 A . DE 1925508 A . DE 7230947 U and GB 379299 known.

A to be solved The object is to provide an electrochemical cell, the for a particularly efficient heat dissipation from the capacitor winding suitable devices.

According to one first preferred embodiment is an electrochemical cell having a housing and disposed therein Capacitor winding specified. The cell has a heat sink on having a section of a side wall of the housing with thermally connecting the capacitor winding. The heat sink is as a cap is formed, which is placed on the capacitor winding. One Connection of the cell is passed through an opening formed in the cap.

According to one second preferred embodiment is an electrochemical cell having a housing and disposed therein Capacitor winding specified. The cell has a heat sink on having a section of a side wall of the housing with thermally connecting the capacitor winding. The heat sink is as a cap is formed, which is placed on the capacitor winding. The Cap has axial slots.

According to one third preferred embodiment is an electrochemical cell having a housing and disposed therein Capacitor winding specified. The cell has a heat sink on having a section of a side wall of the housing with thermally connecting the capacitor winding. The heat sink is between the Sidewall of the housing and the capacitor winding arranged and at least one indentation coupled, which is formed in the side wall of the housing. The heat sink is formed as a separate strip circulating the capacitor winding.

The Inventors have recognized that a capacitor winding due to its Layer structure a low radial thermal conductivity having. Therefore, in the area of a heat sink, with which the capacitor winding to a housing thermally coupled, a heat accumulation arise, what the heat flow from the capacitor winding to the housing prevented. Therefore, a heat sink provided the capacitor winding with a portion of a Sidewall of the housing thermally connects. As a result, the winding is thermally coupled to the housing.

The especially for the radial heat flow effective heat sink is through the contact surface between the heat sink and the housing wall educated. The heat sink, d. H. is a low thermal resistance element So between the winding and the housing wall in the heat sink arranged. The thermal resistance of such a heat sink is preferably smaller than the thermal resistance of the capacitor winding in the radial direction. The heat sink On the one hand has a good thermal contact with the surface of the Capacitor winding. The heat sink on the other hand has a good thermal contact with the housing wall. The good thermal contact is preferably made possible by that the heat sink between the housing wall and the winding is biased or pressed. A good thermal connection is, for example, between an Al case and a soft one Material such. B. Al formed heat sink possible.

With one through the heat sink formed heat path is in particular a heat dissipation of in the radial direction outside lying winding layers possible, because these winding layers near the described heat sink are arranged. More heat sinks for cooling of other areas of the capacitor winding are possible. Especially can the heat from inside winding layers by a z. B. to the housing bottom thermally coupled hub are derived. Furthermore can heat sinks for cooling frontal areas, in particular the bottom area be provided of the winding. The training of heat sinks for Cooling Of different winding areas has the advantage that the heat is substantially derived evenly becomes.

The contact area between the heat sink and the winding is preferably larger than the contact area between the heat sink and the housing wall or the area the heat sink. Thereby will the for the heat transfer effective area the heat sink effectively enlarged. By an enlarged effective area the heat sink is due to the low thermal conductivity of the coil in radial Direction emerging bottleneck of the heat flow balanced. Especially succeeded by such an enlarged effective area of heat sink a fast and even cooling of the lateral surface of the roll. This allows the temperature difference between the winding and the housing be reduced. As a result, condensation processes, i. H. Evaporation of the electrolyte from the heated winding surface and its condensation on the cooler housing wall, be reduced, which is beneficial to the life of the electrochemical Cell affects.

Of the heat sink carry further to a higher one Vibration resistance of the electrochemical cell, as the heat sink ensures a better fit of the coil in the region of the indentation. Of the heat sink absorbs a tension force exerted by the indentation and distributes it these over a larger area, taking the surface pressure increases the winding surface across from a cell without a heat sink reduced.

In In a preferred variant, an electrochemical cell is indicated. the one cup-shaped casing having a capacitor winding arranged therein. In a Sidewall of the housing an indentation is formed. Between the capacitor winding and the indentation is a heat sink arranged, the at least one for a high heat conduction having effective layer. The heat sink has in the region of the indentation a side wall of the housing contacting Contact area where the heat from the capacitor winding to the housing wall transferred directly can be. Through the con tact surface between the housing cup and the winding creates a thermal coupling of the housing and of the coil in the radial direction. The heat sink has a low thermal resistance and improves this thermal coupling.

In a preferred embodiment has the heat sink in both axial directions about this Contact area extending sections, so that the total length of the Heat sink the Length of the Exceeds contact area.

The electrochemical cell - for example capacitor, Battery or accumulator - is preferably formed as an electrolytic capacitor. The capacitor winding has z. As two trained as metal foils electrodes, the by a spacer z. B. of electrolyte-impregnated paper from each other separated and wrapped together to a wrap. The electrodes are in contact with an electrolyte.

The preferably has winding surface formed by the spacer a comparatively high thermal resistance on. The above the contact area extending portions of the heat sink In the sense of a heat path, they are "dead ends" because they have no have direct contact with the housing wall. But they point a low thermal resistance on and are called heat sinks suitable. These sections of the heat sink extend the heat path across from the actual contact area, the heat does not catch only locally in the contact area, but about large areas the surface of the roll and lead the heat to the contact area without a large heat resistance. This succeeds a good thermal coupling between the capacitor winding and the housing.

at a designed as an aluminum electrolytic capacitor electrochemical Cell, the electrodes consist of an aluminum cathode foil and an aluminum anode foil which has a dielectric effect Has oxide layer. Between the slides is a spacer, For example, a single or multi-ply layer of paper, the with an electrolyte solution waterproof is. The assembly may be in the form of a wound around a core Wickels are present, which is inserted into the cup-shaped Al housing becomes. The winding core of a material with good heat conduction properties formed and with the case back be brought into contact, so that the heat flow from the capacitor winding over the Winding core allows towards the ground is. The capacitor winding is preferably in the axial direction braced to better heat transfer z. B. from the protruding Cathode film towards the housing bottom to reach.

The cup shaped casing is completed in a preferred variant at the top by a lid, on the electrical connections are arranged. Preferably, both connections are from the housing cup through the housing cover electrically insulated from an insulating material. The can connections electrically conductive, for example by means of metal strips, respectively an electrode foil of the capacitor winding electrically connected be. In a variant, it is possible that through the lid a single, z. B. connected to the anode foil Connection passed through is, wherein the cathode foil is connected to the housing cup.

The Cathode film can, for. B. have a total thickness between 10 microns and 40 microns. A surface the cathode foil may be roughened or otherwise modified, wherein a thin formed thereby surface layer a significantly lower thermal conductivity than the rest (unmodified) layer (= base layer) has. The material the surface layer may in particular have a lower density than the base material the cathode foil or the material of the base layer. for example can at a 15 microns thick cathode film, the base layer of Al about 10 microns thick and the modified surface layer approx. 5 μm be fat. The effective thickness of the cathode foil, its section as a heat sink is used is preferably at least 30 μm.

Under an effective thickness d of a film associated with the heat sink Metal foil, in a variant cathode foil, is the thickness of the unmodified, high heat conduction having and therefore for a high heat conduction effective base layer of this film understood.

The effective thickness d of for a high heat conduction effective layer of the heat sink is preferably at least 30 μm. The thickness of the heat sink is preferably in the range between 40 and 500 microns, which is approx. 10 to 100% of the strength the housing wall is. The thickness of the heat sink can also be bigger than the strenght the housing wall be. It is possible, by a suitably chosen Thickness of the heat sink a capacitor winding with a too small diameter on a - by the shape of the housing cup or given by the inside diameter of the indentation - minimum diameter bring to.

Of the Contact area of the recess and the heat sink has a length k, wherein in a variant k is between 0.3 mm and 3 mm. The heat sink has in both axial directions beyond this contact area Sections on, whose length each preferably at least 2d. In a preferred variant the above the contact area extending portions of the heat sink each one length between 5d and 100d on. The measured in the axial direction total length of heat sink is therefore preferably at least k + 2d and in a variant between k + 10d and k + 200d. The total length of the heat sink can also be more than k + 200d.

In In an advantageous variant, the heat dissipator has a preferably to the capacitor winding facing adhesion-promoting layer, wherein the for. the high heat conduction effective layer of the heat sink turned to the indentation and the inner surface of the indentation directly contacted. The primer layer provides good thermal contact of the heat sink to the housing wall.

The for the high heat conduction effective layer of the heat sink is preferably made of aluminum. But this layer can as well made of an electrically insulating material with good heat conduction properties be formed.

One for the formation of heat sinks suitable composite material, preferably an aluminum adhesive tape can z. B. be present as a band which is a carrier layer made of Al (Al foil) and having an adhesion promoting layer applied thereto. alternative Is it possible, an existing as Al-band heat sink in sections, z. B. at least one end of the tape with an adhesive layer to provide. An aluminum tape can, for example, with a Total thickness of 40 to 60 microns can be provided. The Thickness of the adhesion-promoting layer is z. B. 10 to 50% of Total thickness of the aluminum adhesive tape.

Of the heat sink can alternatively tubular, d. H. be formed without a slot.

Of the heat sink can by an outside Be formed portion of the cathode foil, preferably around the Capacitor winding revolves at least once.

Of the heat sink may alternatively be formed as a separate strip, the circulates the capacitor winding at least once. The heat sink can have multiple layers have, wherein z. B. the strip is wound several times around the capacitor winding is. By repeated wrapping and the resulting increase in the Thickness of the heat conductor in particular, its thermal conductivity in the radial direction be improved.

Of the heat sink may be formed as a cap on the capacitor winding is preferably placed from above. The cap or another Cap can also be placed from below.

The Cap can have several, preferably at regular intervals arranged axial slots exhibit. At least one opening can be arranged in the bottom of the cap be that larger diameter as an implementing element has, z. B. the external connection the cell with the anode foil or cathode foil of the capacitor winding connects electrically. So there is no electrical contact between the connections and the cap.

The electrochemical cell may be in a Va be formed as a double-layer capacitor. In this case, the capacitor winding consists of a dielectric carrier foil coated with electrode layers on both sides.

The Dent can be in the housing side wall at any height, z. B. in the upper and / or lower area. The indentation can also be arranged in the central region of the housing wall. It can at different heights several heat sinks according to a predetermined number of on different Heights trained Einbuch lines be provided.

The Dent is preferably formed as a circumferential bead. Possible it is also to form several "punctiform" or flat indentations, which are preferably arranged side by side in the circumferential direction. In principle, the such indentations arbitrarily over the lateral surface and possibly floor space of the housing be distributed. Preferably, between each indentation and the Wrap a heat sink arranged. Possible it is also that a heat sink by several z. B. arranged at different heights indentations is contacted.

in the The following is the invention with reference to embodiments and the associated figures explained in more detail. The Figures show diagrammatic and not true to scale representations different embodiments the invention. The same or equal parts are denoted by the same reference numerals designated. It show schematically

1 an electrochemical cell having a heat sink disposed between side surfaces of the capacitor winding and the housing;

2A a tubular heat sink;

2 B a band-shaped heat sink;

3A Contact area between indentation and heat sink;

3B an exemplary construction of a heat sink;

4 an electrochemical cell having a capped heat sink;

5A a capped heat sink;

5B a capped heat sink having axial slots;

6 an electrochemical cell having a heat sink formed by a portion of the cathode foil.

1 shows an electrochemical cell with a cup-shaped housing 20 in which a capacitor winding 10 is arranged. The housing 20 is from the top with a lid 5 completed. Between the crimp of the housing 20 and the lid 5 is a sealing ring 6 arranged. In the lid 5 Two openings are provided, through each one connection 41 . 42 passed through. The connection 41 is z. B. to anode foil 12 and the connection 42 on cathode foil 11 the capacitor winding 10 connected. The cathode foil 11 is from the anode foil 12 through an electrically insulating spacer 13 separated.

On the lateral surface of the housing 20 is a preferably circumferential indentation 21 provided, on the one hand for fixing the capacitor winding 10 in the radial direction and on the other to dissipate the heat generated in the capacitor winding. The direction of the heat flow is indicated by arrows in the figures.

Between the dent 21 and the capacitor winding 10 is a heat sink 3 arranged, the tubular according to 2A or strip-shaped according to 2 B can be trained. The in 2 B schematically shown heat sink 3 may also be a slotted, preferably dimensionally stable tube. The circumference of the tube in this case is smaller than the circumference of the coil, so that a continuous slot 35 remains.

The heat sink 3 can be in an in 3B shown variant effective for a high heat conduction layer 310 and a primer layer applied thereon 320 exhibit. The adhesive layer 320 is in particular for bonding between the heat sink 3 and the surface of the capacitor winding 10 suitable.

A band-shaped heat sink 3 can be in several layers on the capacitor winding 10 be applied to z. B. a relative to the inner diameter of the housing in the region of the recess 21 too small diameter of the capacitor winding 10 to adapt to the inner diameter of the housing in this area. This ensures a good interference fit of the capacitor winding in the housing and improves the dissipation of heat from the capacitor winding in the direction of the housing wall.

In 3A is one to the indentation 21 adjacent contact area 300 of the heat sink 3 and spaced from the housing wall areas 301 . 302 of the heat sink 3 shown. Through the contact area 300 of the heat sink can the heat from the capacitor winding 10 be transferred to the housing wall. The areas 301 . 302 each represents a "dead end" for the heat flow. The contact area 300 has the length k, the dead end area 301 the length s1 and the dead end area 302 the length s2. The heat sink 3 has a thickness d. The total length L of the heat sink 3 in the axial direction L = k + s1 + s2. The lengths s1, s2 may be the same in one variant. The lengths s1, s2 can be different from each other in another variant. The length s1 or s2 is preferably at least 2d, ie twice the thickness of the heat sink 3 , The length s1 or s2 is preferably greater than 10d. It is sufficient, but not necessary, if the length s1 or s2 is a maximum of 100d.

In 4 a further electrochemical cell is shown having a cap-shaped heat sink - in 4 . 5A . 5B as a cap 30 characterized - has. In the 5A and 5B shown cap can be slipped over the winding on the terminal side of the roll. In the bottom surface of the cap 30 are two openings 31 . 32 for carrying out electrical connections between electrode foils 11 . 12 and in the lid 5 arranged connections 41 . 42 intended.

The height of the indentation is chosen so that the lateral surface of the cap 30 through the inner surface of the indentation 21 can be contacted.

With the cap 30 it is possible, the heat path in addition to the (here upper) end face of the capacitor winding 10 to extend.

Another, not shown here cap can on the capacitor winding 10 put on from below and similar to the upper cap 30 be contacted by a (further, provided in the lower region of the housing side wall) indentation.

In 5B a cap-shaped heat sink is shown, whose lateral surfaces are slotted in the axial direction. The slots 33 facilitate the production of the indentation 21 ,

6 shows an electrochemical cell in which the heat sink 3 by a on the surface of the capacitor winding 10 lying free end 111 the cathode foil 11 is formed. The free end 111 the cathode foil 11 can the capacitor winding 10 at least partially circulating. The free end 111 the cathode foil 11 can the capacitor winding 10 completely or even repeatedly.

A not shown here winding core made of a material with a good thermal conductivity, eg. As aluminum, can for an additional heat path from the capacitor winding 10 Ensure to the case back.

The Invention is not limited to the exemplary embodiments shown in FIGS. the number or shape of the displayed elements or the specified ones Limited materials. The housing is not necessarily cup-shaped, but can also be tubular and be completed on both sides by a lid.

10

capacitor winding

11

cathode foil

111

wound around the capacitor winding portion of the cathode foil 11

12

anode foil

13

spacer

20

casing

21

indentation

3

heat sink

310

for a high heat conduction effective layer

320

Bonding layer

30

cap-shaped heat sink

31 32

openings

33

slots

35

continuous slot

41 42

connections

5

cover

6

sealing ring

Claims (21)

Electrochemical cell, with a housing ( 20 ) and a capacitor winding arranged therein ( 10 ), with a heat sink ( 3 ), a portion of a side wall of the housing ( 20 ) with the capacitor winding ( 10 ) thermally connecting the heat sink ( 3 ) is formed as a cap, which on the capacitor winding ( 10 ), wherein a connection ( 41 . 42 ) of the cell is guided by an opening formed in the cap. Electrochemical cell, with a housing ( 20 ) and a capacitor winding arranged therein ( 10 ), with a heat sink ( 3 ), a portion of a side wall of the housing ( 20 ) with the capacitor winding ( 10 ) thermally connecting the heat sink ( 3 ) is formed as a cap, which on the capacitor winding ( 10 ), the cap having axial slots. Electrochemical cell, with a housing ( 20 ) and one in it th capacitor winding ( 10 ), with a heat sink ( 3 ), a portion of a side wall of the housing ( 20 ) with the capacitor winding ( 10 ) thermally connecting the heat sink ( 3 ) between the side wall of the housing ( 20 ) and the capacitor winding ( 10 ) is arranged and at least one indentation ( 21 ), which is formed in the side wall of the housing, wherein the heat sink is formed as a separate strip, which circumscribes the capacitor winding. Electrochemical cell according to one of claims 1 to 3, wherein the contact surface of the heat sink ( 3 ) with the side wall of the housing ( 20 ) forms a heat sink, wherein the heat sink ( 3 ) at least one effective for a high heat conduction layer ( 310 ) having. An electrochemical cell according to claim 4, wherein the thermal resistance of the high thermal conductivity layer ( 310 ) smaller than the thermal resistance of the capacitor winding ( 10 ) is in the radial direction. An electrochemical cell according to claim 4 or 5, having a in the side wall of the housing ( 20 ) formed indentation ( 21 ), wherein the heat sink by the contact surface between the indentation ( 21 ) and the heat sink ( 3 ) is formed. An electrochemical cell according to claim 6, wherein the heat sink ( 3 ) one the inside of the indentation ( 21 ) contacting contact area ( 300 ) and in at least one direction beyond this contact area sections ( 301 . 302 ) having. An electrochemical cell according to any one of claims 4 to 7, wherein the thickness of the high heat conduction layer ( 310 ) has a value d, the sections ( 301 . 302 ) of the heat sink ( 3 ) each have a length of at least 2d. An electrochemical cell according to claim 8, wherein the sections ( 301 . 302 ) of the heat sink ( 3 ) each have a length between 5d and 100d. An electrochemical cell according to any one of claims 4 to 9, wherein the thickness of the high heat conduction layer of the heat sink ( 3 ) is at least 30 microns. An electrochemical cell according to any one of claims 1 to 10, wherein the heat sink ( 3 ) one to the capacitor winding ( 10 ) attentive layer ( 320 ) having. An electrochemical cell according to any one of claims 4 to 11, wherein the heat sink ( 3 ) comprises a layer of aluminum. An electrochemical cell according to any one of claims 4 to 11, wherein the high heat conduction layer ( 310 ) is electrically insulating. An electrochemical cell according to any one of claims 3 to 13, wherein the heat sink ( 3 ) is formed as a cap, which on the capacitor winding ( 10 ) is attached. An electrochemical cell according to claim 1 or 14, wherein the heat sink ( 3 ) axial slots ( 33 ) having. An electrochemical cell according to claim 1 or 2, wherein a terminal ( 41 . 42 ) of the cell is guided by an opening formed in the cap. An electrochemical cell according to claim 3, wherein the heat sink ( 3 ) is designed as a tube. Electrochemical cell according to one of claims 6 to 17, wherein the indentation ( 21 ) is formed as at least one of the circulation of the side wall of the housing following bead. Electrochemical cell according to one of Claims 6 to 17, with several indentations ( 21 ), which are arranged side by side in the circumferential direction. An electrochemical cell according to any one of claims 6 to 18, comprising a plurality of circumferential recesses formed in the side wall of the housing at different heights ( 21 ), whereby between each indentation ( 21 ) and the capacitor winding in each case a heat sink ( 3 ) is arranged. An electrochemical cell according to any one of claims 1 to 20, wherein the housing ( 20 ) comprises an Al cup whose side wall forms the side wall of the housing to which the heat sink ( 3 ) is coupled.