Capacitor and manufacturing method thereof

Abstract

To suppress a decrease in the force that fixes a capacitor element.SOLUTION: A capacitor (2) includes a capacitor element (4) including a cathode foil (12) having a carbon layer (24), and an exterior case (6) that houses the capacitor element. The exterior case includes a protrusion (36) that protrudes toward the inside of the exterior case and contacts a side surface of the capacitor element.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a capacitor and a method for manufacturing the same. [Background technology]

[0002] A capacitor such as an electrolytic capacitor includes, for example, a capacitor element and an exterior case that houses the capacitor element. It is known that a crimping portion is formed on a side of the exterior case, and the capacitor element is fixed by this crimping portion (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-22177 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when hydrogen gas is generated near the cathode foil due to a cathodic polarization reaction, the internal pressure of the capacitor increases, which poses a problem that the force that fixes and holds the capacitor element inside the exterior case (for example, the force applied to the capacitor element from the crimped portion formed on the side of the exterior case) decreases.

[0005] Patent Document 1 does not disclose or suggest such a problem, and the configuration disclosed in Patent Document 1 cannot solve such a problem.

[0006] Therefore, a first object of the present disclosure is, for example, to make it difficult to reduce the force with which the exterior case fixes and holds the capacitor element.

[0007] A second object of the present disclosure is to maintain the vibration resistance of the capacitor, for example by making it difficult for the force with which the exterior case fixes and holds the capacitor element to decrease. [Means for solving the problem]

[0008] In order to achieve the above object, according to a first aspect of the present disclosure, a capacitor includes a capacitor element including a cathode foil having a carbon layer, and an exterior case that houses the capacitor element. The exterior case includes a protrusion that protrudes toward the inside of the exterior case and contacts a side surface of the capacitor element.

[0009] In the above-described capacitor, the outer case may be made of aluminum or a material containing aluminum, and may further include a sealing plate having a plate portion and terminals and disposed inside the opening of the outer case, and the capacitor element may be gripped between a bottom inside the outer case and the sealing plate and held by the convex portion of the outer case.

[0010] In the above capacitor, the capacitor element may be in contact with the terminal and the bottom of the exterior case under pressure.

[0011] In the above capacitor, the exterior case may have a length of 60 mm or more.

[0012] In the above capacitor, the exterior case may have a bottom that is thicker at its periphery than at its center.

[0013] In order to achieve the above object, according to a second aspect of the present disclosure, a method for manufacturing a capacitor includes the steps of making or preparing a capacitor element including a cathode foil having a carbon layer, inserting the capacitor element into an outer case, and forming a convex portion on a side of the outer case that protrudes toward the inside of the outer case and bringing the convex portion into contact with a side of the capacitor element.

[0014] The method for manufacturing the capacitor may include the steps of making or preparing a sealing plate having a plate portion and a terminal, placing the sealing plate inside an opening of the outer case in which the capacitor element is housed, and holding the capacitor element by contacting it under pressure between a bottom of the outer case and the sealing plate and holding it by the convex portion of the outer case. Effect of the Invention

[0015] According to the present disclosure, the following effects can be obtained.

[0016] (1) The carbon layer on the cathode foil suppresses the generation of hydrogen gas, which in turn suppresses the increase in internal pressure of the capacitor. This suppresses the longitudinal deformation of the exterior case due to the increase in internal pressure, and thus suppresses the decrease in the force that holds the capacitor element in place.

[0017] (2) The strength of the capacitor element is prevented from decreasing, so the capacitor element remains fixed, and the capacitor's vibration resistance is maintained for a longer period. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a diagram illustrating an example of a capacitor according to the first embodiment. [Diagram 2] 1A to 1C are diagrams illustrating an example of a manufacturing process for a capacitor. [Diagram 3] FIG. 13 is a diagram for explaining a capacitor when the internal pressure is high. [Figure 4] FIG. 13 is a diagram illustrating an example of a capacitor according to a second embodiment. [Diagram 5] FIG. 13 is a diagram illustrating an example of a capacitor according to a third embodiment. [Figure 6] 13A and 13B are diagrams illustrating examples of capacitors according to modified examples. [Figure 7] FIG. 13 is a diagram showing the results of a usage test of a capacitor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] First Embodiment

[0020] Fig. 1 shows an example of a capacitor according to a first embodiment. In A of Fig. 1, a part of a capacitor element 4 is shown in cross section, and an outer case 6 and a sealing plate 8 are shown in cross section at the center. In B of Fig. 1, an enlarged view of part IB in A of Fig. 1 is shown. The configuration shown in Fig. 1 is only an example, and the technology of the present disclosure is not limited to the configuration shown in Fig. 1.

[0021] Capacitor 2 is, for example, an electrolytic capacitor, and includes, for example, a capacitor element 4, an outer case 6, a sealing plate 8, and an electrolyte. Capacitor element 4 impregnated with the electrolyte is housed inside outer case 6, and sealing plate 8 is disposed and fixed inside opening 30 of outer case 6. Length L of capacitor 2 and outer case 6 may be any length, and may be, for example, 60 to 80 mm, or may be 80 mm or more. Length L is the length from bottom 32 of outer case 6 after crimping to the apex of bent portion 38.

[0022] Capacitor element 4 includes cathode foil 12, anode foil 14, and separator 16. Cathode foil 12, anode foil 14, and separator 16 are stacked and wound to form a wound element such that separator 16 is disposed between cathode foil 12 and anode foil 14. This wound element forms capacitor element 4. Capacitor element 4 has two tabs 20 protruding from element end surface 18-1. Tabs 20 extend from anode foil 14 and cathode foil 12, respectively.

[0023] The cathode foil 12 is an example of an electrode foil, and constitutes the cathode of the capacitor 2. The cathode foil 12 is, for example, a strip-shaped foil, and has a base foil 22 and a carbon layer .

[0024] The base foil 22 is the base metal of the cathode foil 12, and is, for example, a valve metal foil such as aluminum foil, tantalum foil, niobium foil, titanium foil, hafnium foil, zirconium foil, zinc foil, tungsten foil, bismuth foil, or antimony foil. The surface of the base foil 22 has irregularities formed, for example, by etching, and the surface area of ​​the base foil 22 is enlarged. The surface of the base foil 22 may include, for example, tunnel-shaped or spongy etching pits, and the tunnel-shaped or spongy etching pits may form the irregularities.

[0025] The carbon layer 24 is disposed, for example, on both sides or one side of the base foil 22, and covers both sides or one side of the base foil 22. The carbon layer 24 partially penetrates into the interior of the unevenness, and therefore adheres closely to and engages with the unevenness of the base foil 22, increasing the strength of the cathode foil 12. The carbon layer 24 suppresses contact between the base foil 22 and the electrolyte, and suppresses gas generation in the vicinity of the cathode foil 12. The carbon layer 24 contains, for example, a carbon material as a main material, and a binder and a dispersant as additives.

[0026] Carbon materials include activated carbon, carbon black, carbon nanohorns, amorphous carbon, natural graphite, artificial graphite, graphitized Ketjen black, mesoporous carbon, and fibrous carbon. Activated carbon is produced from, for example, natural plant tissue such as coconut shells, synthetic resins such as phenol, and fossil fuels such as coal, coke, and pitch. Carbon black includes Ketjen black, acetylene black, channel black, and thermal black. Fibrous carbon includes carbon nanotubes and carbon nanofibers. Carbon nanotubes may be single-walled carbon nanotubes, which have one graphene sheet, or multi-walled carbon nanotubes (MWCNTs), which have two or more graphene sheets rolled coaxially to form multiple tube walls.

[0027] The binder is a resin-based binder such as styrene butadiene rubber, polyvinylidene fluoride, or polytetrafluoroethylene, which binds the carbon material together. The dispersant is, for example, sodium carboxymethylcellulose.

[0028] The anode foil 14 is an example of an electrode foil and constitutes the anode of the capacitor 2. The anode foil 14 is, for example, the valve metal foil described above, and is a strip-shaped foil. An expanded surface portion having a porous structure is formed on the surface of the anode foil 14. The porous structure has, for example, tunnel-shaped pits, spongy pits, or voids between densely packed powder particles formed by etching. The surface of the expanded surface portion includes a dielectric oxide film formed by chemical conversion treatment.

[0029] Separator 16 is disposed between anode foil 14 and cathode foil 12 to prevent shorting between anode foil 14 and cathode foil 12. Separator 16 is an insulating material and includes kraft as a separator material, and may include other separator materials such as manila, esparto, hemp, rayon, cellulose, mixtures thereof, and the like.

[0030] The outer case 6 is, for example, a metal case such as an aluminum case, and is a cylindrical container with a bottom. The outer case 6 stores the sealing plate 8, the capacitor element 4, the electrolyte, and the like inside the outer case 6. The outer case 6 has, for example, an opening 30, a bottom 32, a crimping portion 34, and a protruding portion 36. The crimping portion 34 and the protruding portion 36 are arranged in an annular shape on the side of the outer case 6 and protrude toward the center line CL of the outer case 6. The protruding portion 36 extends, for example, in the circumferential direction of the side of the outer case 6 and protrudes in all directions toward the inside of the outer case 6. The inside of the outer case 6 is defined as the area surrounded by the outer case 6 and the sealing plate 8. The crimping portion 34 is arranged near the opening 30 and near the element end surface 18-1 of the capacitor element 4, and contacts the sealing plate 8 to fix the sealing plate 8. The protruding portion 36 is arranged between the crimping portion 34 and the bottom 32. The protruding portion 36 fixes and holds the capacitor element 4 inside the exterior case 6 by contacting its tip portion or the vicinity thereof with the non-end portion of the capacitor element 4. The non-end portion of the capacitor element 4 is defined, for example, as the side portion of the capacitor element 4 excluding the vicinity of the element end faces 18-1 and 18-2, or as the center portion of the side portion of the capacitor element 4. The protruding portion 36 is distinguished from the crimping portion 34 in terms of its arrangement position and function. The crimping portion 34 and the protruding portion 36 are formed, for example, by pressing the side portion of the exterior case 6 from the outside with a forming piece and bending the side portion of the exterior case 6 toward the center line CL. The exterior case 6 stretches in the pressed portion of the forming piece. For example, the crimping portion 34 and the protruding portion 36 are thinner than the non-crimped portion. The non-crimped portion is defined as the side portion of the exterior case 6 other than the crimping portion 34 and the protruding portion 36. As shown in FIG. 1, in a cross section including the center line CL of the exterior case 6, the shape of the protrusion 36 is trapezoidal, but it may be other shapes such as triangular, semicircular, or semielliptical.

[0031] The opening 30 of the outer case 6 has a bent portion 38, and this bent portion 38 protrudes from the side portion of the outer case 6 toward the center line CL of the outer case 6. This bent portion 38 causes a tip portion 40 of the outer case 6 to be directed toward, for example, the bottom portion 32 of the outer case 6.

[0032] The bottom 32 of the exterior case 6 may include a weakened portion such as an anti-burst valve. The weakened portion has, for example, a thin groove that opens before the internal pressure of the capacitor 2 reaches a burst level, preventing the capacitor 2 from bursting.

[0033] The sealing plate 8 is disposed inside the opening 30 of the outer case 6, between the crimped portion 34 and the bent portion 38. The sealing plate 8 is pressed against the crimped portion 34 by the bent portion 38, and is thereby fixed to the opening 30 of the outer case 6 and seals the opening 30. The sealing plate 8 is also pressed against the inside of the case by the bent portion 38 at the opening 30, for example, to press the capacitor element 4 into the inside of the case via a terminal 44, which will be described later. The sealing plate 8 has a shape according to the shape of the opening 30 of the outer case 6, and has, for example, a disk shape with the same diameter as or close to the circular opening 30. The sealing plate 8 includes, for example, a plate portion 42 formed by stacking a plurality of members with different functions, and, for example, two terminals 44.

[0034] The plate portion 42 includes, for example, a rubber layer 46 and a resin layer 48. The rubber layer 46 has a function of allowing gas to pass through but blocking liquid. The rubber layer 46 is, for example, a rubber material such as ethylene propylene rubber, butyl rubber, or silicone rubber. The resin layer 48 has greater rigidity than the rubber layer 46 and is, for example, a paper phenolic resin. The paper phenolic resin is a synthetic material in which a paper base material is impregnated with a phenolic resin. The resin layer 48 may be a single structure made of paper phenolic resin, or may be a laminate structure in which other materials (not shown) are superimposed. The rubber layer 46 is disposed on the outer side of the sealing plate 8 (i.e., the side of the bent portion 38 of the exterior case 6) and forms the outer surface of the sealing plate 8. The resin layer 48 is disposed on the inner side of the sealing plate 8 (i.e., the side of the capacitor element 4) and forms the inner surface of the sealing plate 8. The plate portion 42 has a through hole through which the terminal 44 passes.

[0035] Terminal 44 includes an electrode terminal 50 and a rivet 52. Electrode terminal 50 is disposed on the outer surface of sealing plate 8, and functions as an anode terminal or a cathode terminal of capacitor 2. Electrode terminal 50 has, for example, an L-shape, and has an upright portion that stands upright on plate portion 42 and is for connecting to an external component, and a flat portion that is disposed parallel to the surface of plate portion 42. The flat portion has a through hole through which rivet 52 passes.

[0036] The rivet 52 penetrates the plate portion 42 and protrudes from the outer surface and the inner surface of the plate portion 42. The rivet 52 has flange portions 54-1, 54-2, 54-3 and a rod portion 56. The flange portion 54-1 is disposed on the outer surface side of the sealing plate 8, and the flange portions 54-2, 54-3 are disposed on the inner surface side of the sealing plate 8. The rod portion 56 is disposed between the flange portions 54-1, 54-2 and between the flange portions 54-2, 54-3, and is integrated with the flange portions 54-1, 54-2, 54-3. The rod portion 56 penetrates the flat portion and the plate portion 42 of the electrode terminal 50, and the flange portions 54-1, 54-2 sandwich the flat portion and the plate portion 42 of the electrode terminal 50. Therefore, the electrode terminal 50 is fixed to the plate portion 42. The rod portion 56 passes through the through-hole of the tab 20, and the flange portions 54-2 and 54-3 sandwich the tab 20. As a result, the tab 20 is fixed to the terminal 44. That is, the rivet 52 is connected to the tab 20 of the capacitor element 4, for example, by pressure welding or sandwiching. The connection portion of the tab 20 to the rivet 52 is integrated with the rivet 52 to form the terminal 44. The rivet 52 is made of a conductive metal material or has a metal-plated surface, and is electrically connected to the electrode terminal 50 and the tab 20.

[0037] The electrolyte is an electrolytic solution, a gel electrolyte, a solid electrolyte containing a conductive polymer, etc. The electrolyte may include an electrolytic solution or a gel electrolyte, and a solid electrolyte containing a conductive polymer to form a so-called hybrid electrolytic capacitor.

[0038] The capacitor 2 can be fabricated, for example, by the following manufacturing process. The configurations shown in the following manufacturing processes are merely examples, and the technology of the present disclosure is not limited to the configurations shown in the following manufacturing processes.

[0039] The manufacturing process of capacitor 2 is an example of a method for manufacturing a capacitor of the present disclosure, and includes, for example, a step of making outer case 6, a step of making sealing plate 8, a step of making capacitor element 4, a step of connecting sealing plate 8 and capacitor element 4, a step of encapsulating capacitor element 4, a crimping step, and a step of fixing capacitor element 4.

[0040] In the process of manufacturing the outer case 6, a metal material such as aluminum is, for example, formed into a bottomed cylindrical shape to manufacture the outer case 6 before forming the crimped portions 34, the protrusions 36, and the bent portions 38. In the process of manufacturing the outer case 6, the outer case 6 before forming the crimped portions 34, the protrusions 36, and the bent portions 38 may be prepared, for example, by purchase.

[0041] The process of producing the sealing plate 8 includes the process of producing the plate portion 42 and the process of attaching the terminal 44 to the plate portion 42.

[0042] In the process of producing the plate portion 42, the above-mentioned rubber material for forming the rubber layer 46 is layered on, for example, a paper phenolic resin for forming the resin layer 48, and the rubber material and the paper phenolic resin are heated and pressed to produce a laminated material. The produced laminated material is punched into the shape and dimensions of the sealing plate 8 by, for example, a press process to produce the plate portion 42. In the press process, the laminated material is cut by, for example, a shear blade of a press machine. A through hole for passing the terminal 44 is formed in the plate portion 42 by a hole-making device such as a drill or a punching device.

[0043] In the process of attaching the terminal 44 to the plate portion 42, the rod portion 56 of the rivet 52, which has a rod portion 56 before being crushed and a flange portion 54-2, is inserted into the through-hole of the plate portion 42 from the resin layer 48 side, and is also inserted into the through-hole of the flat portion of the electrode terminal 50. With the flange portion 54-2 in contact with the resin layer 48, the rod portion 56 protruding from the flat portion of the electrode terminal 50 is crushed to form the flange portion 54-1. The electrode terminal 50, the rivet 52, and the plate portion 42 are integrated by sandwiching the flange portions 54-1 and 54-2. In the state in which the terminal 44 is attached to the plate portion 42, the rivet 52 is made to protrude from the surface of the resin layer 48 so that the tab 20 of the capacitor element 4 can be attached. In the process of producing the sealing plate 8, the sealing plate 8, the plate portion 42, the terminal 44, the rubber layer 46, the resin layer 48, the electrode terminal 50, or the rivet 52 may be prepared, for example, by purchase.

[0044] The process of producing capacitor element 4 includes a step of producing anode foil 14, a step of producing cathode foil 12, a step of producing separator 16, and a lamination step.

[0045] In the process of producing the anode foil 14, for example, an enlarged surface portion having a porous structure is formed on the surface of the valve metal foil described above, and a dielectric oxide film is formed on the surface of the valve metal foil on which the enlarged surface portion is formed by chemical conversion treatment. The enlarged surface portion is formed by direct current etching, alternating current etching, or by vapor deposition or sintering of metal particles on the valve metal foil. In direct current etching or alternating current etching, a direct current or alternating current is typically applied to the valve metal foil immersed in an acidic aqueous solution containing halogen ions such as hydrochloric acid. The valve metal foil on which the dielectric oxide film is formed is cut to produce the anode foil 14.

[0046] In the process of producing the cathode foil 12, for example, unevenness is formed on the surface of the valve metal foil described above by etching to produce the base foil 22. The etching of the base foil 22 may be the same as or different from the etching of the anode foil 14. The carbon layer 24 is formed on the base foil 22, and the base foil 22 and the carbon layer 24 are cut into strips to produce the cathode foil 12.

[0047] The carbon layer 24 is formed, for example, as follows: The carbon material, binder, and dispersant described above are added to a diluent, and these are mixed by a dispersion process such as a mixer, jet mixing (jet collision), ultracentrifugation, or ultrasonic treatment to form a slurry. The diluent is, for example, alcohol, a hydrocarbon solvent, an aromatic solvent, an amide solvent, water, or a mixture thereof. The alcohol is, for example, methanol, ethanol, or 2-propanol. The amide solvent is, for example, N-methyl-2-pyrrolidone (NMP) or N,N-dimethylformamide (DMF).

[0048] The slurry is applied to the base foil 22, the solvent is volatilized to form the carbon layer 24, and the carbon layer 24 is pressed. The pressing can, for example, force the carbon material into the pores of the unevenness, or, if the carbon material is larger than the pores of the unevenness, can deform the carbon material along the uneven surface of the unevenness. By forcing the carbon material into the pores of the unevenness or deforming the carbon material along the uneven surface of the unevenness, for example, the adhesion and fixation between the carbon layer 24 and the base foil 22 can be improved.

[0049] In the process of producing the separator 16, the separator member described above is cut to produce the separator 16.

[0050] In the lamination process, the anode foil 14, the cathode foil 12, and the separator 16 are stacked so that the separator 16 is disposed between the anode foil 14 and the cathode foil 12, and the anode foil 14, the cathode foil 12, and the separator 16 are wound to produce the capacitor element 4. Before or during the winding, the anode foil 14 and the cathode foil 12 are each connected to a tab 20, and the tab 20 protrudes from the element end surface 18-1. In the process of producing the capacitor element 4, the cathode foil 12, the anode foil 14, the separator 16, or the capacitor element 4 may be prepared, for example, by purchase.

[0051] In the process of connecting the sealing plate 8 and the capacitor element 4, the rod portion 56 protruding from the inner surface of the sealing plate 8 is inserted into the through hole of the tab 20. With the flange portion 54-2 in contact with the tab 20, the rod portion 56 protruding from the tab 20 is crushed to form the flange portion 54-3. The tab 20 and the terminal 44 are integrated by being sandwiched between the flange portions 54-2 and 54-3.

[0052] 2A, in the process of encapsulating the capacitor element 4, the capacitor element 4 impregnated with an electrolyte is inserted into the inside of the exterior case 6, and a sealing plate 8 is placed at the opening 30 of the exterior case 6. At this time, the tab 20 may be folded into the gap between the sealing plate 8 and the capacitor element 4 for storage.

[0053] In the crimping process, as shown in Fig. 2B, crimping portion 34 is formed by crimping, and crimping portion 34 comes into contact with sealing plate 8 to fix the position of sealing plate 8. Also, as shown in Fig. 2C, the end of opening 30 of exterior case 6 is bent to form bent portion 38. By forming bent portion 38, sealing plate 8 is pressed against crimping portion 34 and fixed.

[0054] In the process of fixing the capacitor element 4, convex portion 36 is formed as shown in B of Fig. 2. Convex portion 36 comes into contact with the side surface of the capacitor element 4 to fix the capacitor element 4. Note that the crimping process and the process of fixing the capacitor element 4 may be performed in that order, or the crimping process and the process of fixing the capacitor element 4 may be performed simultaneously so that crimped portion 34 and convex portion 36 are formed simultaneously.

[0055] Fig. 3 is a diagram for explaining a capacitor when the internal pressure is high. In Fig. 3, the same parts as in Fig. 1 are given the same reference numerals. Capacitor 902 shown in Fig. 3 is similar to capacitor 2 except for capacitor element 4. Capacitor 902 includes capacitor element 904 instead of capacitor element 4. Capacitor element 904 is a capacitor element 904 that uses a general cathode foil that does not include carbon layer 24. In Fig. 3, the outline arrows represent pressure, and the dashed arrows represent the extension or movement of exterior case 6, crimping portion 34, or protrusion 36.

[0056] In the vicinity of a typical cathode foil, for example, hydrogen gas is generated by a cathodic polarization reaction, and the internal pressure of the capacitor 902 increases. The exterior case 6 and the sealing plate 8 are subjected to pressures P91 and P92 from the inside to the outside of the capacitor 902. The bottom 32 of the exterior case 6 is subjected to pressure P91, and the side of the exterior case 6 is pulled in the direction of the dashed arrow shown in FIG. 3. As already described, the exterior case 6 at the crimped portion 34 and the protrusion 36 is thinner than the exterior case 6 at the non-crimped portion, for example. Therefore, when the thin crimped portion 34 and the protrusion 36 stretch, the protruding distance D of the crimped portion 34 and the protrusion 36 becomes smaller. In the capacitor 902, for example, in response to an increase in the internal pressure, it can be assumed that the exterior case 6 expands in the length direction, causing the crimped portion 34 and the protrusion 36 to stretch, or that the exterior case 6 stretches in the length direction due to the influence of the stretching of the crimped portion 34 and the protrusion 36.

[0057] Additionally, the side of the exterior case 6 is subjected to pressure P92. Pressure P92 applies a force to the side of the exterior case 6 in the opposite direction to the pressing force applied by the forming piece. This causes the crimped portion 34 and the protrusion 36 to move outward, and the crimped portion 34 and the protrusion 36 to extend along the center line CL. In other words, the action of pressures P91 and P92 causes the crimped portion 34 and the protrusion 36 to extend along the center line CL, and the protruding distance D of the crimped portion 34 and the protrusion 36 becomes smaller.

[0058] If the protruding distance D of the protrusion 36 becomes small, the function of the protrusion 36 for fixing the capacitor element 904 is reduced.

[0059] According to the first embodiment, for example, the following effects can be obtained.

[0060] (1) Since cathode foil 12 includes carbon layer 24, for example, gas generation is suppressed, and an increase in the internal pressure of capacitor 2 is suppressed.

[0061] (2) Suppressing an increase in internal pressure suppresses elongation of crimped portion 34 and protrusion 36 and a reduction in protrusion distance D of protrusion 36. Suppressing a reduction in protrusion distance D allows protrusion 36 to continue to fix and hold capacitor element 4.

[0062] (3) The vibration resistance of the capacitor 2 is maintained, or the period during which the vibration resistance of the capacitor 2 is maintained is extended.

[0063] (4) When length L of capacitor 2 is increased due to an increase in the capacitance of capacitor 2 and limitations on the arrangement space, the area of ​​the electrode foil becomes large, making it easier for gas to be generated. In addition, capacitor element 4 also becomes longer, making capacitor element 4 heavier. However, because cathode foil 12 includes carbon layer 24, gas generation is suppressed, and the fixation of capacitor element 4 by convex portion 36 is maintained, so that even if capacitor 2 has length L of, for example, 80 mm or more, capacitor 2 can maintain its vibration resistance. Second Embodiment

[0064] Fig. 4 shows an example of a capacitor according to the second embodiment. In Fig. 4, the same parts as in Fig. 1 are given the same reference numerals. The configuration shown in Fig. 4 is only an example, and the technology of the present disclosure is not limited to the configuration shown in Fig. 4.

[0065] Capacitor 102 includes, for example, a capacitor element 4, an outer case 6, a sealing plate 8, and an electrolyte. Capacitor element 4, outer case 6, sealing plate 8, and electrolyte are similar to those of capacitor 2 described above, and description thereof will be omitted.

[0066] In the capacitor 102, a part of the terminal 44 of the sealing plate 8 is pressed into the element end surface 18-1 of the capacitor element 4. The capacitor element 4 is fixed to the bottom 32 of the exterior case 6 and the sealing plate 8 by the pressing of the terminal 44. The pressing of the terminal 44 generates a pressure P1 from the sealing plate 8 to the capacitor element 4 and a pressure P2 from the bottom 32 of the exterior case 6 to the capacitor element 4. The pressure P2 is a repulsive force of the pressure P1. When the amount of pressing of the terminal 44 is smaller than the protruding distance of the terminal 44, as shown in FIG. 4, the element end surface 18-1 is separated from the sealing plate 8 in the portion other than the terminal 44. However, the amount of pressing of the terminal 44 may be larger than the protruding distance of the terminal 44, and the element end surface 18-1 may contact the sealing plate 8 in the portion other than the terminal 44.

[0067] Tab 20 pressed against at least terminal 44 of sealing plate 8 is pushed into capacitor element 4. As a result, element end surface 18-1 and element end surface 18-2 of capacitor element 4 are brought into contact with sealing plate 8 and bottom 32 of exterior case 6 under pressure, respectively, and capacitor element 4 is fixed by sealing plate 8 and bottom 32 of exterior case 6.

[0068] The manufacturing process of capacitor 102 is an example of a manufacturing method of a capacitor of the present disclosure, and includes, for example, a step of making exterior case 6, a step of making sealing plate 8, a step of making capacitor element 4, a step of connecting sealing plate 8 and capacitor element 4, a step of encapsulating capacitor element 4, a crimping step, and a step of fixing capacitor element 4. Except for the crimping step, the manufacturing process of capacitor 102 is the same as the manufacturing process of capacitor 2 described above, and therefore description thereof will be omitted.

[0069] In the crimping process, the attachment position of sealing plate 8 and the formation position of crimped portion 34 are determined so that a part of tab 20 or terminal 44 is pressed into capacitor element 4. The attachment position and the formation position may be determined by calculation processing, or the relationship between the attachment position and the formation position and the presence or absence of pressing in capacitor element 4 or the amount of compression may be determined from a previously manufactured capacitor 102.

[0070] In the crimping process, crimped portion 34 is formed at the determined formation position by crimping, and crimped portion 34 comes into contact with sealing plate 8 to fix the position of sealing plate 8. The end of opening 30 of exterior case 6 is bent to form bent portion 38. By forming bent portion 38, sealing plate 8 is pressed against crimped portion 34 and fixed, and terminal 44 is pressed into capacitor element 4, so that capacitor element 4 is fixed between bottom 32 of exterior case 6 and sealing plate 8.

[0071] According to the second embodiment, for example, the following effects can be obtained.

[0072] (1) The same effects as those of the first embodiment can be obtained.

[0073] (2) The terminal 44 of the sealing plate 8 or the tab 20 is pressed into the capacitor element 4, generating a compressive stress in the capacitor element 4, and the capacitor element 4 can be fixed by the exterior case 6 and the sealing plate 8 in the direction along the center line CL. The vibration state of the tab 20 can be made as close as possible to the vibration state of the capacitor element 4. Damage to the tab 20 occurs when stress is applied to the tab 20. The application of stress to the tab 20 may be caused by the tab 20 and the capacitor element 4 vibrating separately. The vibration of the capacitor 2 may cause the tab 20 and the capacitor element 4 to vibrate separately or cause vibration resonance. When the tab 20 is exposed to such swinging or vibration resonance, excessive vibration stress is concentrated on the tab 20. As a result, the tab 20 may be damaged. However, by integrating the tab 20 and the capacitor element 4 by generating a compressive stress, vibration resonance can be suppressed and the stress on the tab 20 can be reduced.

[0074] (3) When outer case 6 expands due to gas generation, pressures P1 and P2 in capacitor element 4 decrease, and the force with which outer case 6 and sealing plate 8 fix capacitor element 4 in the direction along center line CL decreases. However, because cathode foil 12 includes carbon layer 24, gas generation is suppressed and an increase in the internal pressure of capacitor 2 is suppressed. This suppresses expansion of outer case 6 and a decrease in compressive stress in capacitor element 4. In other words, the capacitor element 4 can be maintained in a fixed position by outer case 6 and sealing plate 8 in the direction along center line CL.

[0075] (4) Because capacitor 102 has crimped portion 34 and protrusion 36, the amount of stretch of exterior case 6 is greater than in a capacitor having only crimped portion 34. When the amount of stretch of exterior case 6 increases, the pressing of tab 20 into capacitor element 4 becomes weaker. However, because cathode foil 12 includes carbon layer 24, the stretch of exterior case 6 is suppressed. Even though capacitor 102 includes protrusion 36, the pressing of tab 20 into capacitor element 4 is maintained, and capacitor element 4 can continue to be fixed in place in the direction along center line CL.

[0076] (5) Since the fixation of capacitor element 4 in the direction along center line CL is sustained, the vibration resistance of capacitor 2 can be maintained even if capacitor 2 has length L of, for example, 80 mm or more. Third embodiment

[0077] Fig. 5 shows an example of a capacitor according to the third embodiment. In Fig. 5, the same parts as in Fig. 1 or 4 are given the same reference numerals. The configuration shown in Fig. 5 is only an example, and the technology of the present disclosure is not limited to the configuration shown in Fig. 5.

[0078] Capacitor 202 includes, for example, capacitor element 4, exterior case 206, sealing plate 8, and an electrolyte. Capacitor element 4, sealing plate 8, and electrolyte are similar to those of capacitors 2 and 102 described above, and description thereof will be omitted.

[0079] The capacitor 202 includes an exterior case 206 instead of the exterior case 6. The exterior case 206 is similar to the exterior case 6 described in the first and second embodiments except for the bottom portion 32. The exterior case 206 includes a bottom portion 232 instead of the bottom portion 32. The bottom portion 232 includes a central portion 232-1 and a peripheral portion 232-2 disposed around the central portion 232-1. The peripheral portion 232-2 is thicker than the central portion 232-1. Therefore, in a case where the central portion 232-1 of the bottom portion 232 has a weak portion such as a rupture prevention valve, for example, the thick peripheral portion 232-2 suppresses deformation around the weak portion.

[0080] The manufacturing process of capacitor 202 is an example of a manufacturing method of a capacitor of the present disclosure, and includes, for example, a step of making outer case 206, a step of making sealing plate 8, a step of making capacitor element 4, a step of connecting sealing plate 8 and capacitor element 4, a step of sealing capacitor element 4, a crimping step, and a step of fixing capacitor element 4. Except for the step of making outer case 206, the manufacturing process of capacitor 202 is the same as the manufacturing process of capacitor 2 or capacitor 102 described above, and therefore a description thereof will be omitted.

[0081] In the process of producing exterior case 206, a metal material such as aluminum is, for example, formed into a bottomed cylindrical shape to produce exterior case 206 before forming crimped portion 34, protrusion 36, and bent portion 38. In the process of producing exterior case 206, exterior case 206 before forming crimped portion 34, protrusion 36, and bent portion 38 may be prepared, for example, by purchase.

[0082] According to the third embodiment, for example, the following effects can be obtained.

[0083] (1) The same effects as those of the capacitor 2 according to the first embodiment or the capacitor 102 according to the second embodiment can be obtained.

[0084] (2) When the central portion 232-1 of the bottom portion 232 has a weak portion, for example, the thick peripheral portion 232-2 can suppress deformation around the weak portion.

[0085] (3) When the peripheral portion 232-2 of the bottom portion 232 of the exterior case 206 is thick, the rigidity of the bottom portion 232 is increased. Therefore, the bottom portion 232 is less likely to bulge outward, and the exterior case 206 has a structure that is more likely to stretch along the center line CL due to an increase in internal pressure than the exterior case 6 according to the first and second embodiments. Therefore, it is expected that the protruding distance D of the convex portion 36 is more likely to be reduced. However, in the capacitor 202, the cathode foil 12 includes the carbon layer 24, so that, for example, gas generation is suppressed and an increase in the internal pressure of the capacitor 202 is suppressed. That is, even if the peripheral portion 232-2 of the bottom portion 232 of the exterior case 206 is thick, the cathode foil 12 including the carbon layer 24 suppresses the reduction in the protruding distance D of the convex portion 36. The suppression of the reduction in the protruding distance D provides a particularly remarkable effect of maintaining the fixation of the capacitor element 4. EXAMPLES

[0086] As an example of the capacitor of the present disclosure, a usage test including a vibration experiment was performed to verify the vibration resistance. In this verification, a comparative example (not shown) is presented, and the results of the comparison of the change in state of the protrusion 36 and the vibration resistance due to the vibration experiment are shown. 7 is a diagram showing the results of a test of a capacitor in use. The results and measurements in FIG. 7 are merely examples, and the technology of the present disclosure is not limited to the contents of this figure.

[0087] <Example> The capacitor of the embodiment is any one of the capacitors 2, 102, and 202 of the present disclosure, and as described above, a capacitor element 4 formed by laminating and winding an anode foil 14 having tunnel-shaped pits, a cathode foil 12 having a carbon layer 24 on the surface of a base foil 22 such as an aluminum foil, and a separator 16 made of a craft material is housed in an exterior case 6. A crimping portion 34 and a protrusion 36 are formed in the exterior case 6. The capacitor is a substrate-free type, and is formed with a diameter of 35 [mm] and a height of 60 [mm]. Furthermore, the protrusion 36 is formed in the circumferential direction at a height of 13 [mm] from the bottom surface. The diameter formed at the tip of the protrusion 36 is 28.74 [mm].

[0088] <Comparative Example> The comparative example is a capacitor in which a capacitor element formed by winding an anode foil and a cathode foil with a separator interposed between them is housed in an exterior case, the opening of the case is sealed with a sealing member, and similarly to the embodiment, a protrusion for fixing and holding the capacitor element is provided around the exterior case. In the capacitor according to the comparative example, the cathode foil forming the capacitor element is made of aluminum foil that does not include the carbon layer 24. In the comparative example, the diameter and height of the capacitor, and the height and diameter of the formed protrusion are set to be the same or approximately the same.

[0089] <Experimental Method> In this experiment, the capacitors of the embodiment and comparative examples were subjected to 1) a usage condition test in which 450 V was applied for a specified period of time in an environment of 105°C, up to a maximum of 4000 hours, and the change in the length of the capacitor and the change in the diameter of the convex portion 36 were measured, and 2) a vibration experiment was performed on the capacitors after 4000 hours had passed.

[0090] This vibration test complies with "4.8 Vibration" of the Japanese Industrial Standards (JIS) C5101-4:2019 "Fixed capacitors for electronic equipment - Part 4: General rules for each type - Fixed aluminum solid (MnO2) and non-solid electrolytic capacitors" and "4.17 Vibration" of the JIS C5101-1:2019 "Fixed capacitors for electronic equipment - Part 1: General rules for each type". The conditions for the standard vibration test are as follows. The sweep direction is set assuming a state in which the capacitor is mounted on a substrate or the like at terminal 44 of capacitor 2, and in this state, the front and back of the plane are set as the X direction (a direction intersecting a virtual line connecting the anode terminal 44 and cathode terminal 44 of capacitor 2), the left and right are set as the Y direction (a direction parallel to the virtual line connecting the anode terminal 44 and cathode terminal 44 of capacitor 2), and the height is set as the Z direction (the height direction of capacitor 2). Vibration frequency: in the range of 10 to 55 Hz. Amplitude or acceleration: Single amplitude 0.75 [mm] or 98 [m / s 2 ] (whichever is looser) as the standard, the amplitude width will be made stricter in the order of 2 times (single amplitude 1.5 [mm]), 3 times (single amplitude 2.25 [mm]), and 4 times (single amplitude 3.0 [mm]). Sweep rate: 10Hz-55Hz-10Hz (approximately 1 minute) Sweep direction and test time: (sweep direction) first Z direction, then Y direction, and finally X direction (Test time) 2 hours for each direction (total 6 hours)

[0091] In this vibration test, first, vibration load is applied in Z, Y, and X directions with an amplitude twice that of the JIS standard. After the vibration test in each sweep direction is completed, a characteristic measurement is performed to determine whether the capacitor operates normally or is in a fault state. If it is in a fault state, the test is terminated. If it is normal, a vibration test is performed in the next sweep direction and characteristic measurements are performed. If the characteristic measurement is performed at the end of the vibration test in the X direction and the capacitor is normal, the vibration load condition is raised by one rank, and vibration tests and characteristic measurements are repeated in different sweep directions as in the vibration test with an amplitude twice that of the JIS standard. In other words, the vibration is performed in Z, Y, and X directions in sequence with an amplitude three times that of the JIS standard, and characteristic measurements are performed at the end of the vibration test in each direction to determine whether the capacitor operates normally or is in a fault state. If it is in a fault state, the test is terminated. If it is normal, the vibration test is repeated in the next sweep direction.

[0092] <Usage test results and evaluation results> Regarding this usage state test, FIG. 7A shows the comparison results of the change in the case length direction, and FIG. 7B shows the comparison results of the change in the diameter of the protrusion forming portion. In A and B of FIG. 7, the predetermined time t is taken as an example, and the passage of time is shown every 1000 [hours].

[0093] (1) As shown in Fig. 7A, the length of the case in the first measurement after the start of the experiment was close to that of the example and the comparative example, but the amount of swelling in the length direction of the case in the comparative example using aluminum foil as the cathode foil increased rapidly over time. In contrast, in the capacitor of the example using the cathode foil 12 having the carbon layer 24, the change in the length direction of the case became small after the second measurement. The amount of swelling in the length direction of the case shown in Fig. 7A is indicated by a scale of, for example, 0.05 mm increments. (2) As shown in Fig. 7B, the diameter of the convex portion is larger in the comparative example than in the working example, and the amount of change increases rapidly with time. The amount of change in the working example increases slightly with time, but even after t4 = 4000 [hours] has passed, the diameter increases slightly. The value of the diameter of the convex portion shown in Fig. 7B is indicated, for example, by a scale of 0.05 [mm]. (3) The experimental results show that, in the comparative capacitor using aluminum foil, the pressure inside the case increases significantly over time, whereas, in the capacitor of the present disclosure using cathode foil 12 having carbon layer 24, the generation of gas inside the case is suppressed, and the increase in internal pressure is kept low. In the comparative capacitor, the diameter of the protrusion increases as the exterior case swells in the length direction. In contrast, in the embodiment of the present disclosure, the change in diameter of the portion where protrusion 36 is formed decreases as the exterior case swells in the length direction.

[0094] <Vibration test results and evaluation> Regarding the vibration test, the results of the characteristic measurements of the capacitors according to the comparative example and the embodiment are shown in Table 1. In the table, the cathode foil 12 having the carbon layer 24 is referred to as the carbon foil.

[0095] [Table 1]

[0096] (1) In vibration tests, as shown in the examples of the present disclosure, by using a cathode foil having a carbon layer, the capacitor operates normally even when the amplitude is increased to 3.0 mm, which is four times the JIS standard. In contrast, in a comparative example in which an aluminum foil is used for the cathode foil, the capacitor operates normally up to an amplitude of 1.5 mm, which is twice the JIS standard. However, when the vibration condition was set to an amplitude of 2.25 mm, which is three times the JIS standard, the capacitor was confirmed to be in a faulty state in the characteristic measurement at the end of the first Z-direction vibration test. (2) The results of the usage test and the vibration test show that the use of a cathode foil having a carbon layer suppresses the expansion of the outer case in the longitudinal direction and the extension of the convex parts due to an increase in the internal pressure of the case. As a result, the fixed retention of the capacitor element 4 inside the case is maintained by the sealing plate 8 that holds the convex parts 36 and the rivets 52, and the bottom of the case. By maintaining the fixed retention of the capacitor element 4 in this way, even if a vibration load is applied to the capacitor 2, it is possible to suppress the movement of a part or all of the capacitor element 4 inside the case, and prevent the capacitor 2 from breaking down.

[0097] Regarding the embodiment described above, characteristics and modifications thereof will be listed below.

[0098] (1) The capacitor element 4, the exterior case 6, the sealing plate 8, the electrolyte, etc. are not limited to those described in the embodiment. These materials may be other materials used in aluminum electrolytic capacitors or similar capacitors. The capacitor element 4 may be, for example, a laminated element in which a plurality of flat cathode foils 12, anode foils 14, and separators 16 are laminated. The material of the carbon layer 24 is not limited to those described in the embodiment. The material forming the carbon layer 24 may be any conductive member containing carbon. The state of adhesion or engagement of the carbon layer 24 with the substrate foil 22 is not limited to those described in the embodiment.

[0099] (2) The exterior case 6, 206 may include a plurality of protrusions 36 that contact the non-end portion of the capacitor element 4. The plurality of protrusions 36 can fix the capacitor element 4, and can improve the vibration resistance of the capacitor 2, 102, 202. It is expected that an increase in the number of protrusions 36 makes the exterior case 6, 206 more likely to stretch along the center line CL due to an increase in internal pressure. However, because the cathode foil 12 includes the carbon layer 24, gas generation is suppressed, and the stretching of the exterior case 6, 206 is suppressed.

[0100] (3) In the embodiment, the outer case 6, 206 has an annular protrusion 36. However, as shown in FIG. 6, the outer case 6, 206 may have one or more recesses 62 formed in a concave shape with a predetermined size instead of the protrusion 36. One or two recesses 62 may be formed on the outer surface of the side of the outer case 6, 206. Three or more recesses 62 may be formed on the outer surface of the side of the outer case 6, 206. The recess 62 is, for example, a dimple. The shape of the recess 62 is not limited to a specific shape, and may be, for example, a partial spherical shape or a parabolic shape formed by rotating a parabola. The protrusion formed by the recess 62 has a smooth surface such as a spherical surface, and contacts the capacitor element 4 to fix the capacitor element 4. The protrusion formed by the recess 62 contacts the capacitor element 4 intermittently in the circumferential direction of the capacitor element 4, so that the application of more mechanical stress than necessary to the capacitor element 4 is suppressed.

[0101] (4) In the embodiment or modification, the convex portion formed by convex portion 36 or concave portion 62 comes into contact with capacitor element 4, thereby fixing capacitor element 4. However, the convex portion formed by convex portion 36 or concave portion 62 may press capacitor element 4 to the extent that capacitor element 4 is not electrically affected. Pressing capacitor element 4 further improves the vibration resistance of the capacitor.

[0102] (5) In the embodiment, the electrode terminal 50, the rivet 52, and the plate portion 42 are integrated together by sandwiching the flange portions 54-1 and 54-2, and the tab 20 and the terminal 44 are integrated together by sandwiching the flange portions 54-2 and 54-3. However, the tab 20 may be attached to the rivet 52 by, for example, cold welding.

[0103] (6) The bent portion 38 of the exterior case 6 may simply be bent.

[0104] (7) In capacitor 202 according to the third embodiment, similar to capacitor 102, a portion of terminal 44 of sealing plate 8 is pressed into element end surface 18-1 of capacitor element 4. However, in capacitor 202, terminal 44 does not have to be pressed into element end surface 18-1.

[0105] As described above, the most preferred embodiment of the present disclosure has been described. The technology of the present disclosure is not limited to the above description. Various modifications and changes are possible for those skilled in the art based on the gist of the disclosure described in the claims or disclosed in the specification. It goes without saying that such modifications and changes are included in the scope of the present disclosure. [Industrial Applicability]

[0106] INDUSTRIAL APPLICABILITY The technology of the present disclosure is useful in that it can provide a capacitor having vibration resistance or durability. [Explanation of symbols]

[0107] 2, 102, 202, 902 capacitors 4, 904 Capacitor element 6, 206 Outer case 8 Sealing plate 12 Cathode foil 14 Anode foil 16 Separator 18-1, 18-2 Element end face 20 Tabs 22 Base foil 24 Carbon Layer 30 Opening 32, 232 bottom 34 Crimping part 36 Convex 38 Bending section 40 Tip 42 Board part 44 terminals 46 Rubber layer 48 Resin layer 50 electrode terminal 52 Rivet 54-1, 54-2, 54-3 Flange 56 Rod part 62 Depression 232-1 Central part 232-2 Surrounding area

Claims

1. a capacitor element including a cathode foil having a carbon layer; an exterior case that houses the capacitor element; Equipped with The exterior case includes a protrusion that protrudes toward the inside of the exterior case and contacts a side surface of the capacitor element. Capacitor.

2. the exterior case is made of aluminum or a material containing aluminum, a sealing plate having a plate portion and a terminal and disposed inside the opening of the exterior case; 2. The capacitor according to claim 1, wherein the capacitor element is gripped between a bottom portion inside the outer case and the sealing plate, and is held by the protruding portion of the outer case.

3. 3. The capacitor according to claim 2, wherein the capacitor element is in contact with the terminals and the bottom of the exterior case under pressure.

4. 4. The capacitor according to claim 1, wherein the exterior case has a length of 60 mm or more.

5. 4. The capacitor according to claim 1, wherein the outer case has a bottom whose periphery is thicker than its central portion.

6. making or providing a capacitor element comprising a cathode foil having a carbon layer; inserting the capacitor element into an exterior case; forming a protrusion on a side of the outer case so as to protrude toward the inside of the outer case, and bringing the protrusion into contact with a side surface of the capacitor element; A method for manufacturing a capacitor comprising the steps of:

7. A step of producing or preparing a sealing plate having a plate portion and a terminal; placing the sealing plate inside an opening of the exterior case in which the capacitor element is housed; a step of gripping the capacitor element by contacting it under pressure between a bottom portion of the exterior case and the sealing plate and holding it by the protruding portion of the exterior case; The method for producing a capacitor according to claim 6, comprising:

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