Electrolytic capacitors

Abstract

This invention provides an electrolytic capacitor that can improve the ease of inserting lead tabs into the sealing body. [Solution] The electrolytic capacitor 1 comprises a capacitor element 11, an outer case 12 having an opening 12a and housing the capacitor element 11 inside, a sealing body 13 that seals the opening 12a of the outer case 12 and has a through hole 131 that penetrates from a first end face 13a on the side facing the capacitor element 11 to a second end face 13b on the opposite side of the capacitor element 11, and lead tabs 14 and 15 that are connected to the capacitor element 11 and inserted through the through hole 131. The inner wall of the through hole 131 is provided with a slit 132 that extends from the first end face 13a toward the second end face 13b.

Description

Technical Field

[0001] The present invention relates to an electrolytic capacitor provided with a sealing body for sealing an opening of an exterior case in which a capacitor element is housed.

Background Art

[0002] Conventionally, a lead tab for drawing out an electrode to the outside is connected to an electrode foil of a capacitor element. One end portion (flat portion) of the lead tab is connected to the electrode foil in a flat shape, and the other end portion (round bar portion) of the lead tab is inserted through the sealing body. And it is common that a terminal is drawn out to the outside of the exterior case through a through hole (terminal insertion hole in Patent Document 1) formed in the sealing body by a lead wire connected to the lead tab. For example, in Patent Document 1, a sealing plug body having a slit portion with a radial cut is provided so as to close the through hole. Then, by pushing the lead wire into the slit portion, the sealing plug body is changed from a closed state to an open state, the lead wire is inserted, and the lead wire is drawn out to the outside of the sealing body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the lead wire of the capacitor element is drawn out to the outside of the sealing body, the round bar portion of the lead tab is inserted through the through hole of the sealing body. At this time, when the round bar portion of the lead tab is pushed into the through hole of the sealing body, excessive stress is generated on the lead tab, and it may be difficult to insert the lead tab into the through hole.

[0005] Therefore, an object of the present invention is to provide an electrolytic capacitor capable of improving the insertability of the sealing body.

Means for Solving the Problems

[0006] The electrolytic capacitor of the present invention comprises a capacitor element, an outer case having an opening and housing the capacitor element inside, a sealing body that seals the opening of the outer case and has a through hole that penetrates from a first end face on the side facing the capacitor element to a second end face on the opposite side of the capacitor element, and a lead tab connected to the capacitor element and inserted through the through hole. The inner wall of the through hole is provided with a first slit extending from the first end face toward the second end face.

[0007] According to the above configuration, when inserting a lead tab through the through-hole of the sealing body, the slit formed from the side facing the capacitor element (first end face) to the opposite side (second end face) widens, thereby improving the ease of inserting the lead tab into the sealing body.

[0008] Furthermore, in the electrolytic capacitor of the present invention, the slit does not have to penetrate to the second end face.

[0009] With the above configuration, since the slit does not penetrate to the end face (second end face) of the sealing body opposite to the capacitor element, it is possible to reduce the leakage of electrolyte impregnated into the capacitor element through the slit in the outer case.

[0010] Furthermore, in the electrolytic capacitor of the present invention, a second slit extending from the second end face toward the first end face may be further formed in the inner wall of the through hole.

[0011] Some sealing bodies have a symmetrical shape so that either the first or second end face can face the capacitor element. Therefore, by forming slits on both sides of the sealing body that can face the capacitor element, the slits are present on the capacitor element side regardless of which side is positioned on the capacitor element side, thus improving the ease of inserting the lead tab into the sealing body.

[0012] Furthermore, in the electrolytic capacitor of the present invention, the number of first slits per through-hole is eight or more.

[0013] The above configuration improves the ease with which the lead tab can be inserted into the sealing body. [Effects of the Invention]

[0014] According to the present invention, the ease of inserting the lead tab into the sealing body is improved. [Brief explanation of the drawing]

[0015] [Figure 1] This is a cross-sectional view showing the configuration of electrolytic capacitor 1. [Figure 2] This is a perspective view showing the capacitor element 11 of the electrolytic capacitor 1. [Figure 3] This is an explanatory diagram showing the lead tabs 14 and 15 of electrolytic capacitor 1. [Figure 4] This is an explanatory diagram showing how to insert lead tabs 14 and 15 into the sealing body 13. [Figure 5] This is an explanatory diagram showing an embodiment in which slits are provided on both sides of the sealing body 13. [Modes for carrying out the invention]

[0016] The electrolytic capacitor 1 according to this embodiment will be described below with reference to the attached drawings.

[0017] As shown in Figure 1, the electrolytic capacitor 1 includes a capacitor element 11, an outer casing 12, a sealing body 13, and lead tabs 14 and 15.

[0018] As shown in Figure 2, the capacitor element 11 consists of an anode foil (anodic aluminum foil) 14a and a cathode foil (cathode aluminum foil) 15a, which have been etched and subjected to dielectric oxide film formation treatment, wound in a cylindrical shape via a separator 16, and secured with element fixing tape 21 (see Figure 1). This capacitor element 11 is housed in an outer case 12 (see Figure 1).

[0019] The exterior case 12 is a bottomed cylindrical case. A sealing body 13 is attached to the opening 12a of the exterior case 12, and the opening 12a has a structure sealed by necking. Thus, the sealing body 13 seals the opening 12a of the exterior case 12. For example, the sealing body 13 is an elastic body. More specifically, for example, the sealing body 13 is a rubber elastic body. For example, the sealing body 13 may be natural rubber or synthetic rubber.

[0020] The lead tabs 14 and 15 are drawn out from the capacitor element 11. Lead wires 14b and 15b are welded to the lead tabs 14 and 15 respectively. The lead wires 14b and 15b are formed with a smaller diameter than the lead tabs 14 and 15. The lead wires 14b and 15b are drawn out to the outside through the sealing body 13. At this time, the lead tabs 14 and 15 are in a state of being inserted through the sealing body 13. The insertion state of the lead tabs 14 and 15 in the sealing body 13 will be described in detail later. The exterior case 12 is covered by a sleeve 22 (see FIG. 1).

[0021] The lead tab 14 is a lead tab on the anode side connected to the anode foil 14a by a method such as caulking or welding. The lead tab 15 is a lead tab on the cathode side connected to the cathode foil 15a by a method such as caulking or welding.

[0022] As shown in FIG. 3, the lead tab 14 on the anode side has a round bar portion 141 protruding from the end face on the side of the sealing body 13 of the capacitor element 11 (see FIG. 2), and a flat portion 142 formed at one end of the round bar portion 141 to which the anode foil 14a is connected. For example, the lead tab 14 may be formed by pressing one end of a round bar-shaped member made of aluminum by a predetermined length to form the flat portion 142, and making the remaining portion the round bar portion 141. The lead wire 14b is welded to the tip end portion (the end portion opposite to the flat portion 142) of the round bar portion 141.

[0023] Furthermore, the cathode-side lead tab 15, like the anode-side lead tab 14, has a round bar portion 151 that protrudes from the end face of the capacitor element 11, and a flat portion 152 formed at one end of the round bar portion 151 to which the cathode foil 15a is connected. The lead wire 15b is welded to the tip of the round bar portion 151 (the end opposite to the flat portion 152). In Figure 3, the components of the lead tab 15 are indicated by the symbols in parentheses.

[0024] As shown in Figure 4, the sealing body 13 has two through holes 131-131 for inserting the lead tabs 14-15. That is, the sealing body 13 has through holes 131 that penetrate from the end face facing the capacitor element 11 (first end face 13a) to the end face opposite the capacitor element 11 (second end face 13b). For example, the diameter of the through holes 131 is set to be smaller than that of the lead tabs 14-15. Also, the diameter of the through holes 131 is kept constant.

[0025] Furthermore, the inner wall of the through-hole 131 is provided with a slit 132, which is a first slit extending from the first end face 13a to the second end face 13b. That is, a notch is formed in the inner wall of the through-hole 131, cut radially outward from the sealing body 13. For example, in the example shown in Figure 4, four slits 132 are formed in one through-hole 131. The slits 132 may or may not face each other in the through-hole 131.

[0026] The length of the slit 132 in the direction from the first end face 13a to the second end face 13b is set to be shorter than the thickness of the sealing body 13. In other words, the slit 132 does not penetrate to the second end face 13b. This reduces the leakage of the electrolyte used to impregnate the capacitor element 11 in the outer case 12 through the slit 132. Thus, the slit 132 is provided on the first end face 13a side. Also, as shown in Figure 5, the slit 132 may be provided on both the first end face 13a and the second end face 13b. That is, in addition to the slit 132 as the first slit, a second slit 133 extending from the second end face 13b to the first end face 13a may be further formed on the inner wall of the through hole 131. This allows the lead tabs 14 and 15 to be inserted through the through hole 131 with the slit 132 regardless of which side is facing the capacitor element 11.

[0027] The width (width in the direction horizontal to the first end face 13a) and depth (length from the first end face 13a to the second end face 13b) of the slit 132 may be as follows. Specifically, when the diameter of the round bar portion of the lead tabs 14 and 15 is set to 1, the upper limit of the width of the slit 132 is preferably 0.85, and the lower limit of the width of the slit 132 is preferably 0.5. Also, when the thickness of the sealing body 13 is set to 1, the upper limit of the depth of the slit 132 is preferably 0.30, and the lower limit of the width of the slit 132 is preferably 0.14. If the width and / or depth of the slit 132 exceeds the above upper limits, the sealing body 13 becomes more prone to deformation, reducing its sealing ability, and the deformation of the sealing body 13 makes it easier for the electrolyte to leak, which may affect the product life. Furthermore, if the width and / or depth of the slit 132 is smaller than the lower limit mentioned above, the stress when inserting the lead tabs 14 and 15 may not be sufficiently relieved.

[0028] As described above, the electrolytic capacitor 1 comprises a capacitor element 11, an outer case 12 having an opening 12a and housing the capacitor element 11 inside, a sealing body 13 that seals the opening 12a of the outer case 12 and has a through hole 131 that penetrates from a first end face 13a on the side facing the capacitor element 11 to a second end face 13b on the opposite side of the capacitor element 11, and lead tabs 14 and 15 that are connected to the capacitor element 11 and inserted through the through hole 131. The inner wall of the through hole 131 is provided with a slit 132 that extends from the first end face 13a toward the second end face 13b.

[0029] According to the above configuration, when inserting the lead tabs 14 and 15 into the through-hole 131 of the sealing body 13, the slit 132 formed from the side facing the capacitor element 11 (first end face 13a) to the opposite side (second end face 13b) widens, thereby improving the ease with which the lead tabs 14 and 15 can be inserted into the sealing body 13.

[0030] Furthermore, in the electrolytic capacitor 1 of the present invention, the slit 132 does not have to penetrate to the second end face 13b.

[0031] With the above configuration, since the slit 132 does not penetrate to the end face (second end face 13b) of the sealing body 13 on the opposite side of the capacitor element 11, it is possible to reduce the leakage of electrolyte impregnated into the capacitor element 11 through the slit 132 in the outer case 12.

[0032] Furthermore, in the electrolytic capacitor 1 of the present invention, the slit 132 may be formed on the first end face 13a and the second end face 13b. That is, in addition to the slit 132 as the first slit, a second slit 133 extending from the second end face 13b toward the first end face 13a may be further formed on the inner wall of the through hole 131.

[0033] The sealing body 13 generally has a symmetrical shape so that either the first end face 13a or the second end face 13b can face the capacitor element 11. Therefore, by forming slits 132 and 133 on both sides of the sealing body 13 that can face the capacitor element 11, the slit 132 is present on the capacitor element 11 side regardless of which side is positioned facing the capacitor element 11, improving the ease with which the lead tabs 14 and 15 can be inserted into the sealing body 13.

[0034] Although embodiments of the present invention have been described above, these are merely illustrative examples and do not particularly limit the present invention. Specific configurations and other aspects can be modified as appropriate. Furthermore, the actions and effects described in the embodiments of the invention are merely a list of the most preferred actions and effects resulting from the present invention, and the actions and effects according to the present invention are not limited to those described in the embodiments.

[0035] (Examples) Next, electrolytic capacitors for the comparative example and the example were fabricated, and each electrolytic capacitor was evaluated. The electrolytic capacitors used in the comparative example and the example below have a rated voltage of 25V, a rated capacitance of 1000μF, and a product size of φ12.5 × 13.5L (mm).

[0036] Conventional examples used sealing bodies without slits. Furthermore, Example 1 used a sealing body with two slits per through-hole. Example 2 used a sealing body with four slits per through-hole. Example 3 used a sealing body with eight slits per through-hole. Example 4 used a sealing body with twelve slits per through-hole. Example 5 used a sealing body with sixteen slits per through-hole. In the example shown in Figure 4, the number of slits per through-hole is four (Example 2).

[0037] (Evaluation method) As shown in Figure 4, the lead tabs 14 and 15 of the capacitor element 11 were actually inserted through the through-hole 131 of the fixed sealing body 13. Specifically, using a testing machine (not shown), the lead wires 14b and 15b were pulled until the entire round bar portions 141 and 151 of the lead tabs 14 and 15 entered the through-hole 131 of the sealing body 13. The force exerted by the round bar portions 141 and 151 on the sealing body 13 was then measured.

[0038] The tensile speed of the testing machine was 10 mm / min. The diameter of the two through holes in the sealing body was set to 1.4 ± 0.05 mm. The diameter of the round bar sections 141 and 151 was set to 1.5 ± 0.05 mm. The width of the slits in Examples 1 to 5 (width in the direction horizontal to the first end face 13a) was set to 0.75 mm each. The depth of the slits in Examples 1 to 5 (length from the first end face 13a to the second end face 13b) was set to 0.5 mm. The thickness of the sealing body was 3.5 mm. Table 1 shows the results of evaluations using 10 capacitor elements for each of the conventional example and Examples 1 to 5. Note that, in order to make the evaluation results easier to understand, the ratio of the diameter of the through holes to the diameter of the round bar section was made smaller than in typical designs applied to products. In other words, the conventional examples and embodiments performed evaluations such that when the round bar portion is inserted through the through hole of the sealing body, the stress applied to the electrode foil via the lead tab from the sealing body becomes higher than usual.

[0039] [Table 1]

[0040] Table 1 shows that the force required to insert the lead tabs into the sealing body in Examples 1-5 was lower than in the comparative examples, indicating improved insertability of the sealing body. This demonstrates the effectiveness of providing slits in the through-holes of the sealing body. In particular, when the number of slits per through-hole was 8 or more, the force required to insert the lead tabs into the sealing body remained consistently low, confirming remarkable effectiveness. Furthermore, the same effect as in the examples was obtained even when slits were formed on the second end face. From the above examples, it can be seen that the force required to insert the lead tabs into the sealing body when the number of slits is between 4 and 8 is in the range of 12N to 6N. [Explanation of symbols]

[0041] 1: Electrolytic capacitor 11: Capacitor element 12: Outer case 12a:Aperture 13: Sealing body 13a: First end surface 13b: Second end surface 14: Lead Tab 14a: Anode foil 14b: Lead wire 15: Lead Tab 15a: Cathode foil 15b: Lead wire 16: Separator 21: Element fixing tape 22: Sleeves 131: Through hole 132: Slit (First Slit) 133: Slit (Second Slit)

Claims

1. Capacitor element and An outer casing having an opening and housing the capacitor element inside, A sealing body that seals the opening of the outer case and has a through hole that penetrates from the first end face on the side facing the capacitor element to the second end face on the opposite side of the capacitor element, A lead tab connected to the capacitor element and inserted through the through hole, Equipped with, The inner wall of the through hole is provided with a first slit extending from the first end face toward the second end face. Electrolytic capacitor.

2. The electrolytic capacitor according to claim 1, The first slit does not penetrate to the second end face. Electrolytic capacitor.

3. An electrolytic capacitor according to claim 1 or 2, A second slit is further formed in the inner wall of the through hole, extending from the second end face toward the first end face. Electrolytic capacitor.

4. An electrolytic capacitor according to claim 1 or 2, The number of the first slits per through hole is eight or more. Electrolytic capacitor.

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