Capacitor

Abstract

having capacitor a capacitor cup (KB) for receiving a capacitor winding (W), comprising - at least three ribs (R) projecting into the cup, which are located in the condenser cup (KB) at a transition from a cup wall (BW) to a cup bottom (BB), and a capacitor winding (W) arranged in the capacitor can (KB), wherein the capacitor winding (W) is deformed by the ribs (R), wherein the capacitor winding (W) comprises a cathode (KT) and the cathode (KT) is made of aluminum, wherein the cathode (KT) of the capacitor winding (W) projects towards the can bottom (BB), wherein the projecting cathode (KT) creates a contact between the projecting cathode (KT) of the capacitor winding (W) and the ribs (R) of the capacitor can (KB), wherein the contact is designed to transport a quantity of heat away from the capacitor winding (W) via the ribs (R), wherein the capacitor can (KB) has at least one bead in the can wall (BW), which extends around the can and stabilizes the capacitor winding (W) in its position in the capacitor can (KB), wherein at least one of the ribs (R) is shaped such that it projects radially into the capacitor can (KB) at the can base (BB) and uniformly loses radial extent with increasing height above the can base (BB) until it merges into the can wall (BW), and that it extends into a region between the can base (BB) and the capacitor winding (W) and contacts several cathode layers of the protruding cathode (KT), wherein the rib (R) projects into the capacitor can (KB) at the can base (BB) over a distance (r) which is smaller than the radius of the capacitor can (KB).

Description

[0001] The application relates to a capacitor having a capacitor cup for receiving a capacitor winding.

[0002] According to the state of the art, capacitor windings are typically not centered for insertion into a capacitor can. In one case, the capacitor winding is held in place using a copper wire, which is used as a welding electrode and is located in a central hole in the capacitor winding. The capacitor winding is fastened centrally to the base of the capacitor can by welding. Since only very weak leverage can be exerted by the copper wire and the electrode when inserted into the capacitor can, only extreme asymmetries can be avoided during insertion. For example, the capacitor winding installed in the capacitor can is often not positioned in the center or is diagonally positioned to the housing axis. By axially fixing the capacitor winding between the base of the can and the cover disk, it remains in the asymmetrical position. This influences the quality of the fastening and thus also the vibration strength of the capacitor.

[0003] DE 101 52 342 A1, US 3 386 014 A, JP 2011- 204 724 A and DE 92 03 739 U1 each show capacitors in which a winding element is arranged in a can.

[0004] The object of the present invention is to provide a capacitor with a capacitor can for improved accommodation of a capacitor winding. For example, the capacitor can can allow the capacitor winding to be radially centered within the capacitor can during installation.

[0005] The object is achieved by a capacitor according to the present claim 1. Dependent claims specify advantageous embodiments.

[0006] The proposed solution is a capacitor with a capacitor can for accommodating a capacitor winding. This capacitor can comprises at least three ribs that protrude into the capacitor can and are located at a transition from a can wall to a can base.

[0007] The ribs allow a capacitor winding to be radially centered in the capacitor can when it is inserted into the capacitor can. By locally pressing the capacitor winding into the capacitor can by ribs during insertion and due to the fact that the circumference of the capacitor winding is constant, the capacitor winding can be pushed outwards between the ribs. This way, when inserted into a capacitor can with, for example, four ribs, the capacitor winding can be deformed from its original cylindrical shape to a more cuboidal shape. Such deformation by ribs can be advantageous because the radius of the capacitor winding can be subject to production-related fluctuations and space problems can arise in a capacitor can without ribs if the radius of the capacitor winding, for example,is too large or the capacitor winding is not correctly radially centered in the capacitor can without ribs, if the radius of the capacitor winding is too small.

[0008] A capacitor can as defined above can be a container in the shape of a hollow cylinder with a base, with the wall of the hollow cylinder being referred to as the can wall and the base as the can base. This capacitor can can serve as the body of a capacitor. The capacitor winding can be a winding of a stack of layers. This can include conductive foils, which serve as capacitor electrodes, and insulating intermediate elements, which serve as the dielectric. The ribs can be understood as web-like elevations that protrude into the interior of the capacitor can.

[0009] In a comparative form not yet claimed, the fins run perpendicular to the cup base. In this form, it would be possible to manufacture the capacitor cup, including the fins, in a single step of an extrusion process, which would allow for cost-effective production of the capacitor cup.

[0010] The fins can be arranged symmetrically in the capacitor can. This allows the capacitor winding to be centered in the capacitor can with evenly distributed force.

[0011] At least one of the ribs projects radially into the can base and decreases in radial extension evenly with increasing height above the can base until it merges into the can wall at a maximum height above the can base. The maximum radial extension of the rib at the cup base can have a length of 1.0 mm to 2.0 mm, for example 1.5 mm. The height above the cup base at which the rib merges into the cup wall can be between 2.0 mm and 4.0 mm, for example 3.0 mm. This allows the rib to have a triangular cross-section in a plane that includes the axis of the capacitor winding. This shape of the rib allows the capacitor winding to be radially centered in the capacitor can when it is inserted into the capacitor can. This also means that a deviation from the radially centered position of the capacitor winding can be corrected during insertion into the capacitor can.

[0012] In a further embodiment, at least one of the ribs is designed such that it extends radially into the capacitor can at the can base and uniformly decreases in radial extent with increasing height above the can base. In this embodiment of the capacitor can, the rib can have a flattened area parallel to the can base at a maximum height above the can base. The maximum radial extent of the rib at the can base can have a length of 1.0 mm to 2.0 mm, for example 1.5 mm. The height above the can base at which the rib has the flattened area parallel to the can base can be between 1.0 mm and 3.0 mm, for example 2.0 mm. Based on this embodiment, the rib can have a trapezoidal cross-section in a plane that includes the axis of the capacitor winding, the base sides of which are parallel to the can base.This design of the capacitor can saves material, and the smaller size of the ribs reduces the forces acting on the production tool during the production of the capacitor can, resulting in more cost-effective manufacturing. This design also allows a capacitor winding to be radially centered in the capacitor can.

[0013] According to a further possible embodiment, at least one of the ribs on the can base projects radially into the capacitor can. The radial extent of the rib can remain constant up to a first height above the can base. From this first height, the radial extent of the rib can decrease uniformly until the rib merges into the can wall at a second height above the can base. The radial extent of the rib can be between 1.0 mm and 2.0 mm, for example 1.5 mm. The first height above the cup base can be between 1.0 mm and 3.0 mm, for example 2.0 mm. The second height above the cup base can be between 4.0 mm and 6.0 mm, for example 5.0 mm. In this embodiment, the rib can have a trapezoidal cross-section in a plane that includes the axis of the capacitor winding, the base sides of which are parallel to the can wall.Such a design can allow axial or rotational relative movement of the capacitor winding in the capacitor can without losing radial centering. This can be advantageous if the capacitor winding is fixed to the top of the capacitor can, e.g., by a rubber plug. In such a case, thermal expansion can lead to relative movement between the capacitor winding and the capacitor can. Despite a possible change in the axial position of the capacitor winding in the capacitor can, the capacitor winding could still be supported by the ribs. This could enable the capacitor winding to remain radially centered and provide additional stability for the capacitor when mechanical vibrations occur.

[0014] In an alternative embodiment of the capacitor, at least one of the ribs on the cup base extends radially into the capacitor cup and has a flattened portion at the cup base. In this embodiment, the rib can decrease in radial extent with increasing height above the cup base until it merges into the cup wall at a maximum height. The rib can extend between 1.0 mm and 2.0 mm, for example 1.5 mm, from the inside of the cup wall radially into the capacitor cup. The maximum height at which the rib merges into the cup wall can be between 2.0 mm and 4.0 mm, for example 3.0 mm. The flattened portion can extend from the cup wall between 2.0 mm and 3.0 mm, for example 2.5 mm, radially into the capacitor cup. The height that the flattened portion rises above the cup base can be between 1.0 mm and 2.0 mm, for example 1.5 mm.This flattening allows a gap to remain between the capacitor winding and the base of the can when the capacitor winding is inserted. An electrical connecting wire can be inserted into this gap from the capacitor winding to the capacitor electrode. The connecting wire can be designed to be flexible, thus better accommodating relative movements of the capacitor winding to the capacitor can. This can lead to a longer capacitor lifespan.

[0015] A capacitor with two or more differently shaped fins is also possible. It is irrelevant whether the differently shaped fins or the different shapes of the fins are combined to create a greater advantage for the function and stability of the final capacitor.

[0016] In an alternative embodiment of the capacitor, the fins are located in a lower area of ​​the capacitor can. Where "bottom" refers to the side of the hollow cylinder where the base is located. All fins can be located in a lower fifth of the height of the capacitor can. Preferably, all fins are located in a lower tenth of the height of the capacitor can. If the fins are arranged in a lower area of ​​the capacitor can, the centering of the capacitor winding can only take place at the end of the insertion process, which offers an advantage in the process flow. By centering later, more flexibility could be left when calibrating the machine position responsible for inserting the capacitor winding. From a manufacturing perspective, if the fins are arranged in the lower area of ​​the capacitor can, the advantage of producing the fins using the extrusion process would arise.For example, the capacitor can, which has the fins in its lower section, could be manufactured in a single extrusion step. A separate process step for producing the fins is not required. This can save manufacturing time and costs.

[0017] The capacitor further comprises a capacitor winding. The capacitor according to one of the above embodiments can benefit from its advantages in terms of stability, durability, and cost-effective production.

[0018] The capacitor has at least one bead in the can wall of the capacitor can. The bead or beads can be arranged symmetrically across the height of the capacitor can. The at least one bead extends around the circumference of the capacitor can. The bead stabilizes the capacitor winding in its position within the capacitor can. This can increase the stability of the capacitor and create a thermal bridge between the outer layers of the capacitor winding and the capacitor can. The thermal bridge can allow temperature equalization with the surroundings of the capacitor.

[0019] The term “bead” introduced above refers to a depression or notch in the capacitor can wall that results from a deformation of the capacitor can wall in the radial direction.

[0020] The capacitor can be made of aluminum. Choosing aluminum as the material can facilitate production using the extrusion process, thus opening up the possibility of cost-effective manufacturing.

[0021] A cathode of the capacitor winding also contains aluminum. Furthermore, the cathode of the capacitor winding protrudes from the capacitor winding towards the bottom of the can. In such a case, the wound layers of the protruding cathode can be pressed radially inwards by the ribs when inserted into the capacitor can. This creates thermal contact between the individual layers of the protruding cathode and between the layers of the protruding cathode and the ribs. Due to the electrically and thermally insulating layers in the capacitor winding, heat flow occurs predominantly along the electrodes in the capacitor winding, in a vertical direction. At a contact point between the protruding cathode and the bottom of the can, an amount of heat can be transferred from the capacitor winding to the capacitor can.If contact between the protruding cathode and the can bottom is lost due to thermal expansion or manufacturing reasons, heat can still be dissipated via the fins. The connected layers also allow heat to be transported from the interior of the capacitor winding to the capacitor can, regardless of whether there is contact between the capacitor winding and the can bottom.

[0022] For capacitor operating frequencies above 1 MHz, the contact surfaces of the protruding cathode can also form an electrical contact all the way to the fins, reducing the capacitor's inductance. This electrical contact can occur because there may be a capacitive oxide layer on the cathode, which can become conductive over the described frequency range.

[0023] Both the different designs of the capacitor can and the variants of the capacitor winding can be suitable for the production of an electrolytic capacitor.

[0024] In the following, the invention is explained in more detail using a selection of embodiments and the associated schematic figures. Fig. 1 shows a schematic plan view of a capacitor winding clamped between four ribs in the capacitor can. Fig. Figure 2 shows a sectional view of a capacitor can from the perspective with two ribs positioned at an angle of 90 degrees to each other. Fig. Figure 3 shows a schematic sectional view of a capacitor can with capacitor winding and rib, where the rib is designed for axial guidance of the winding. Fig. Figure 4 shows a schematic sectional view of a capacitor can with capacitor winding and fin, wherein the fin has a flattening on the side remote from the can bottom. Fig. Figure 5 shows a schematic sectional view of a capacitor can with a capacitor winding with a contact band and ribs with a spacing function. Fig. Figure 6 shows a schematic sectional view of a radial capacitor with rubber plugs and long fins. Fig. Figure 7 shows a schematic sectional view of a capacitor with a cathode projecting towards the bottom of the cup and heat flow via the fins. Fig. Figure 8 shows a schematic sectional view of a capacitor in soldering star design with a bead and sketched electrical current flow. Fig. 9 shows the arrangement of fins in a minimal design in the schematic top view of the capacitor can. Fig. 10 shows the arrangement of two different fins in a schematic top view of the capacitor can. Fig. Figure 11 shows a schematic sectional view of a capacitor in a special design with fins and the sketched current flow.

[0025] The Fig. 1 shows a schematic plan view of a capacitor winding W. This is clamped between ribs R, whereby a capacitor can KB in the figure is designed with four ribs R. The capacitor winding W comprises an aluminum foil and can be deformed by the ribs R when inserted into the capacitor can compared to its originally almost cylindrical body, whereby its circumference is retained as a conserved quantity. When the capacitor winding W is inserted into the capacitor can KB, the ribs R press the capacitor winding W locally towards the center of the capacitor can and a bulge of the capacitor winding W occurs between the ribs R. In this way, the spiral-shaped capacitor winding W can be forced by four ribs, for example, from its rounded cross-section to a more square cross-section. The ribs R enable axial centering of the capacitor winding W in the capacitor can KB.

[0026] Fig. 2 shows a perspective schematic sectional view of a capacitor can KB with ribs R in one possible embodiment. In this embodiment, the ribs R on the can base BB extend radially into the capacitor can KB. The ribs R on the can base BB can extend into the capacitor can KB over a distance r. The distance r can have a length between 1.0 mm and 2.0 mm, for example 1.5 mm. With increasing height above the can base BB, the ribs R lose radial extension. At a maximum height h1 above the can base BB, the ribs R merge into the can wall BW. The maximum height h1 can have a length between 2.0 mm and 4.0 mm, for example 3.0 mm. As a result, the ribs R have a triangular cross-section in a plane that includes the axis of the capacitor winding W.

[0027] The ribs R are arranged at equal radial angles α to each other at the transition from the can wall BW to the can bottom BB of the capacitor can KB. Due to the triangular cross section of the ribs R and their regular arrangement, the capacitor winding W is axially centered in the capacitor can KB when inserted. As if through a funnel T, a radially symmetrical force acts on the capacitor winding W towards the center of the capacitor can KB when inserting the capacitor winding W. A funnel T comparable to the ribs R is Fig. 2 shown in dashed lines. The funnel forms a surface for the inward-facing surfaces of the fins. Since the fins R only locally press the capacitor winding W toward the center of the capacitor can KB, the capacitor winding W can bulge outward between the fins R and thus retain its circumference. This is an advantage over a funnel T attached to the can base BB of the capacitor base KB, since the radius of the capacitor windings W can be subject to production-related fluctuations, which would then no longer fit exactly into the funnel or would result in unacceptable deformation of the capacitor winding W.

[0028] Fig. 3 shows the schematic sectional view of a capacitor can KB with ribs R and a capacitor winding W. In this unclaimed embodiment, all ribs R on the can base BB extend radially into the capacitor can KB. The ribs R on the can base BB can extend into the capacitor can KB over a distance r. The distance r can have a length between 1.0 mm and 2.0 mm, for example 1.5 mm. Only from a height h2 above the can base BB do the ribs lose radial expansion. The maximum height h2 can have a length between 1.0 mm and 3.0 mm, for example 2.0 mm. At a maximum height h1 above the can base BB, the ribs R merge into the can wall BW. The maximum height h1 can have a length between 4.0 mm and 6.0 mm, for example 5.0 mm.

[0029] The sectional view reveals the cross-section of the ribs R, which has the area of ​​a trapezoid whose parallel bases run perpendicular to the can base BB. By using a capacitor can KB with the rib shape shown, the capacitor winding W is in a radially centered position when inserted into the capacitor can KB before it reaches the can base BB. Even with an axial relative movement of the capacitor winding W to the capacitor can KB, e.g., due to thermal expansion, the capacitor winding W remains radially centered in the capacitor can KB.

[0030] In Fig. 4 shows a schematic sectional view of a capacitor can KB with ribs R and a capacitor winding W. In this unclaimed embodiment, all ribs R on the can base BB project radially into the capacitor can KB. The ribs R on the can base BB can project into the capacitor can KB over a distance r. The distance r can have a length between 1.0 mm and 2.0 mm, for example 1.5 mm. With increasing height above the can base BB, the ribs R uniformly lose radial extension. At a maximum height h1 above the can base BB, the ribs have a flattened area that runs parallel to the can base BB. The maximum height h1 can have a length between 1.0 mm and 3.0 mm, for example 2.0 mm.

[0031] The sectional view reveals the cross-section of the ribs R, which has the area of ​​a trapezoid. The base sides defined by the trapezoid run parallel to the can base BB. They are formed by a flattened portion A of the ribs R and the can base. By using ribs R of this design, material can be saved on the capacitor can KB. The use of these flattened ribs R is possible if the capacitor winding W was already approximately centered to the capacitor can KB during insertion.

[0032] Fig. 5 shows a schematic sectional view of a possible embodiment of the capacitor can KB with capacitor winding W and ribs R. In this embodiment, the ribs R on the can base BB extend radially into the capacitor can KB. The ribs R on the cup base BB can extend into the capacitor can KB over a distance r. The distance r can have a length between 1.0 mm and 2.0 mm, for example 1.5 mm. With increasing height above the cup base BB, the ribs R evenly lose radial expansion. At a maximum height h1 above the cup base BB, the ribs R merge into the cup wall BW. The maximum height h1 can have a length between 2.0 mm and 4.0 mm, for example 3.0 mm. In addition, the ribs R comprise a flattened area A on the cup base BB, which has a maximum height h3 above the cup base BB. The maximum height h3 can have a length between 1.0 mm and 3.0 mm, for example 2.0 mm.

[0033] With the flattened area A, the ribs R form a lower stop for the capacitor winding W when the capacitor winding W is axially positioned. This creates a gap Z between the can base BB and the capacitor winding W. The flattened area A can be designed in such a way that the resulting gap Z offers sufficient space for a movable contact strip B without excessively deforming it. The contact strip B serves as the electrical connection between the capacitor winding W and the can base BB. With the movable contact strip B, an electrical contact is maintained between the capacitor winding W and the can base, even if, for example, small rotational movements occur in the capacitor winding W, which lead to a displacement of the contact strip B.

[0034] Fig. 6 shows a schematic sectional view of a radial capacitor with rubber plug G. The rubber plug G closes the capacitor can KB at its open side and additionally fixes the capacitor winding W. This fixes the capacitor winding W relative to the rubber plug G and movements of the capacitor winding W relative to the capacitor can KB are possible. With this design of the capacitor K, the position of the capacitor winding W is determined by the position of the rubber plug G because electrical contact pins KS of the capacitor winding W are fastened in it, the contact pins KS are electrically conductively connected to the capacitor winding W and are guided in the axial direction through the rubber plug G. In the event of thermal expansion, the capacitor winding W follows the rubber plug G and a relative movement of the capacitor winding W relative to the capacitor can KB can occur.

[0035] However, in the case of strong vibration loads on the capacitor K, the one-sided fastening of the capacitor winding W is disadvantageous. This can lead to breakage of the contact pins KS. The capacitor can has ribs that Fig. 3. The ribs enable axial guidance of the capacitor winding. The ribs exert a force on the capacitor winding that acts radially toward the center of the capacitor winding. This dampens any vibration of the capacitor winding. These ribs R have the cross-sectional shape of a trapezoid, with their bases running parallel to the can wall BW. The ribs R are designed such that the axially acting holding forces are smaller than the permissible tensile forces of the contact pins KS.

[0036] Since the capacitor winding W can slide both axially and rotationally on the ribs, no destructive loads occur on the contact pins KS when the capacitor winding W moves in the capacitor can KB. The relative movements of the capacitor winding relative to the capacitor can KB can be caused by the fact that the capacitor winding W is firmly connected to the rubber plug G and that the capacitor can KB heats up and therefore expands more quickly than the capacitor winding W.

[0037] Fig. 7 shows a section of a schematic sectional view of a capacitor can KB with ribs R and a capacitor winding W with a protruding cathode KT. Due to the protruding cathode KT, the ribs R not only provide mechanical fastening and alignment of the capacitor winding W, but also effective thermal contact. Heat flow from the capacitor winding W to the capacitor can KB occurs primarily via the aluminum cathode KT and an anode of the capacitor winding W. Furthermore, the heat flow is inhibited by the insulation between the capacitor electrodes, whereby heat transport preferably occurs vertically in the capacitor winding W. Heat flow can only occur radially at a point of contact between the cathode KT and the can base BB.A direct aluminum-to-aluminum contact offers good heat transfer and is durable due to the mechanical prestressing of the protruding cathode (KT), which maintains contact even during thermal expansion. This is because even if the cup base bulges outward due to heating and thus loses contact with the protruding cathode (KT), the ribs push it inward. Unlike a center bead, which thermally contacts only the outermost cathode layer at most, the combination of the protruding cathode (KT) and the ribs (R) thermally contacts multiple cathode layers, thus greatly improving thermal contact with the interior of the capacitor winding.Due to an oxide layer that forms on the cathode KT, the contact surface between the protruding cathode KT and the fins R only forms an electrical contact at a frequency range above 1 MHz, which can reduce the inductance of the capacitor K. The electrical contact is formed because the otherwise capacitive oxide layer becomes conductive in the described frequency range.

[0038] In Fig. Figure 8 shows a schematic sectional view of a capacitor K in soldering star design with bead S. The left half is shown with ribs R and the right half in the previous design. Without the use of ribs R, there can be two bottlenecks E1 and E2 in the capacitor K where an increased current density occurs. When the capacitor K is in operation, an increased magnetic field occurs at these bottlenecks E1, E2. By using ribs R, the current flow at the can base BB of the capacitor can KB can be split between the cathode connection at E2 and the ribs R, generating a smaller magnetic field and only the bottleneck E1 remains.

[0039] Fig. Figure 9 shows a schematic top view of a capacitor can KB with fins R in a minimal design. Three fins R are arranged at an angle of 120° to each other on the can base BB. This design is minimal because at least three fins R are required to axially center a capacitor winding W in the capacitor can KB. This design is particularly suitable for small capacitors because the forces acting on the capacitor winding W are minimal due to the small number of fins.

[0040] Fig. Figure 10 shows a schematic top view of a capacitor can KB in a possible embodiment with two different types of ribs R and RT, where each type of rib R, RT is present three times and the individual ribs R, RT are arranged at an angle of 60° to each other. For centering the capacitor winding W, a minimal design with three ribs R would be sufficient. To increase the fixing forces and the thermal coupling between the capacitor winding W and the capacitor can KB, additional ribs RT can be attached, which are smaller in volume and height and thus require less effort and cost. Such additional ribs RT can be designed in the cross-sectional shape of a trapezoid, like those shown in Fig. 4, whose base sides are aligned parallel to the cup bottom BB, or have a flattening near the cup bottom BB as in Fig. 5.

[0041] In Fig.Figure 11 shows a capacitor K with a capacitor can KB and capacitor winding W in a special horizontal design. The capacitor can comprises a bead S and ribs R. With this design of the capacitor K, the ribs R have an even stronger influence on the current flow and thus on the magnetic field. Without the ribs R, a current loop occurs near the can base BB. By using a capacitor can KB with ribs R for the horizontal capacitor K, a current loop can be avoided. This can result in an even greater reduction in the magnetic field. List of reference symbols: A flattening B Contact tape BB cup bottom BW cup wall E1 Bottleneck 1 E2 Bottleneck 2 G rubber stopper K capacitor KB capacitor can KS contact pin KT cathode LG local magnification LK local reduction R ribs RT ribs with trapezoidal cross-section S bead T funnel W capacitor winding Z space

Claims

[1] Capacitor having a capacitor cup (KB) for receiving a capacitor winding (W), comprising - at least three ribs (R) projecting into the cup, which are located in the condenser cup (KB) at a transition from a cup wall (BW) to a cup bottom (BB), and a capacitor winding (W) arranged in the capacitor can (KB), wherein the capacitor winding (W) is deformed by the ribs (R), wherein the capacitor winding (W) comprises a cathode (KT) and the cathode (KT) is made of aluminum, wherein the cathode (KT) of the capacitor winding (W) projects towards the cup bottom (BB), wherein the projecting cathode (KT) creates a contact between the projecting cathode (KT) of the capacitor winding (W) and the ribs (R) of the capacitor cup (KB), wherein the contact is designed to transport a quantity of heat away from the capacitor winding (W) via the ribs (R), wherein the capacitor can (KB) has at least one bead in the can wall (BW), which extends around the can and stabilizes the capacitor winding (W) in its position in the capacitor can (KB), wherein at least one of the ribs (R) is shaped such that it projects radially into the capacitor can (KB) at the can base (BB) and uniformly loses radial extension with increasing height above the can base (BB) until it merges into the can wall (BW), and that it extends into a region between the can base (BB) and the capacitor winding (W) and contacts several cathode layers of the projecting cathode (KT), wherein the rib (R) at the can base (BB) projects into the capacitor can (KB) over a distance (r) which is smaller than the radius of the capacitor can (KB). [2] A capacitor according to claim 1, wherein the fins are arranged symmetrically. [3] A capacitor according to one of the preceding claims, wherein at least one of the ribs (R) on the cup bottom (BB) projects radially into the capacitor cup (KB) and uniformly loses radial extension with increasing height above the cup bottom (BB) until it has a flattening parallel to the cup bottom (BB). [4] A capacitor according to one of the preceding claims, wherein at least one of the ribs (R) on the cup bottom (BB) extends radially into the capacitor cup (KB) and only loses radial expansion uniformly from a certain height above the cup bottom (BB) until it merges into the cup wall (BW). [5] A capacitor according to one of the preceding claims, wherein at least one of the ribs (R) is shaped such that it projects radially into the capacitor can (KB) at the can bottom (BB) and uniformly loses radial extension with increasing height above the can bottom (BB) until it merges into the can wall (BW) and the rib (R) additionally comprises a flattening (A) near the bottom. [6] A capacitor according to any one of the preceding claims, comprising at least two differently shaped fins. [7] A capacitor according to any one of the preceding claims, wherein the ribs (R) are located in the lower fifth of the capacitor can (KB), preferably in the lower tenth of the capacitor can (KB). [8] A capacitor (K) according to one of the preceding claims, wherein the capacitor can (KB) is made of aluminum.

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