Capacitor

Abstract

This capacitor (10) includes a case (20) housing a capacitor element (11), and a pressure valve (25) provided in a bottom surface (first surface) (21) of the case. The pressure valve includes a discharge direction control structure (24) including a first groove (26a) provided in the bottom surface and a second groove (26b) provided in the bottom surface so as to intersect or touch the first groove, the second groove being shallower than the first groove, the discharge direction control structure deforming due to an increase in the internal pressure of the case and opening diagonally relative to the bottom surface by fracturing at least partially.

Description

Technical Field

[0001] The present invention relates to capacitors such as electrolytic capacitors.

Background Art

[0002] Japanese Patent Laid-Open No. 10-149959 describes providing an electrolytic capacitor with improved heat dissipation and excellent ripple resistance. In this document, in an electrolytic capacitor in which a capacitor element is housed in a case and a lid is attached to the case for sealing, the capacitor element is in contact with at least the bottom surface of the case, and an elastic body is coated on at least one of the inner bottom surface of the case or the back surface of the lid, and a protrusion inserted into the winding core of the capacitor element is provided. An electrolytic capacitor is disclosed.

[0003] Japanese Patent Laid-Open No. 2015-177070 describes providing an electronic device that aims at miniaturization and can ensure appropriate heat dissipation and a proper lifespan. The electronic device of this document includes a case, an aluminum electrolytic capacitor, a transformer, and a heat dissipation gel sheet. The case houses the aluminum electrolytic capacitor and the transformer inside. The heat dissipation gel sheet is disposed between the case and the aluminum electrolytic capacitor and is in contact with the case and the aluminum electrolytic capacitor.

[0004] Japanese Patent Publication No. 2017-168778 describes a cooling structure for an electrolytic capacitor and an electrolytic capacitor unit capable of improving heat dissipation. The electrolytic capacitor unit in this document comprises a heat-dissipating resin having a first surface, and a plurality of electrolytic capacitors integrally provided with the heat-dissipating resin, each having an explosion-proof valve, and arranged with the explosion-proof valve facing the first surface, and a heat-dissipating member having a second surface and attached to the first surface so as to be in thermal contact with the second surface, wherein a ventilation path is provided on at least one of the first and second surfaces to allow all of the plurality of explosion-proof valves to be vented to the outside air, and the ventilation path has a ventilation groove that allows at least one of the plurality of explosion-proof valves to be vented to the outside air via at least one other explosion-proof valve.

[0005] Japanese Patent Publication No. 2015-88504 describes how to delay the operation of a pressure valve without increasing the operating pressure of the pressure valve. The capacitor in this document has a groove-shaped pressure valve formed on its bottom surface, and at least three recesses are formed on the bottom surface of the outer case that houses the capacitor element impregnated with electrolyte, in a region that does not overlap with the pressure valve and is inward from the outer edge of the bottom surface of the outer case. [Disclosure of the Invention]

[0006] In recent years, capacitors used in automotive products and other applications have been expected to have higher ripple current, higher heat resistance, and higher capacitance on the input side. When capacitors are used under high ripple current loads, internal heat generation can reduce product lifespan. This phenomenon is particularly pronounced when used at high temperatures. Therefore, efforts are being made to reduce heat generation by reviewing the materials and internal structure of the capacitors themselves. However, to achieve even higher ripple current, technologies that promote heat dissipation from the capacitor on the circuit design or device side are becoming important. For example, a technology has been proposed to improve heat dissipation by providing a heat sink when mounting the capacitor and filling the space between them with heat-dissipating resin. On the other hand, in capacitors such as electrolytic capacitors, a pressure valve (explosion-proof valve) is provided on the bottom of the cylindrical aluminum case. To obtain heat dissipation, it is effective to fill the space between the bottom of the case and the heat sink with heat-dissipating resin, but the discharge resin may interfere with the operation of the pressure valve.

[0007] One aspect of the present invention is a capacitor (condenser) having a case housing a capacitor element and a pressure valve provided on a first surface of the case. The pressure valve includes a discharge direction control structure (part, pattern) that deforms due to an increase in the internal pressure of the case and opens obliquely to the first surface by at least a part of it breaking. The pressure valve (explosion-proof valve) has a lower pressure resistance strength than other parts of the first surface and is further a structure (part) that deforms due to an increase in the internal pressure of the case and a force is applied to the first surface, typically the bottom surface of the case, causing it to be partially or completely cut or broken, and includes a discharge direction control structure (discharge direction control function, discharge direction control mechanism, discharge direction control device) that opens obliquely to the first surface. When the pressure valve is operated due to an increase in the internal pressure of the case, this discharge direction control structure opens obliquely to the first surface and controls the direction of the gas blown out from the pressure valve so that it is blown out mainly obliquely, i.e., along the first surface, rather than perpendicular (axially) to the first surface.

[0008] The pressure valve of the present invention includes a structure (function) that controls the direction of the blown-out gas in a direction along a first surface. Therefore, even if the first surface faces a structure with a heat dissipation function, such as a heat sink, and a heat dissipation resin is filled or coated between them, gas is blown out from the pressure valve in a predetermined direction along the first surface, thereby blowing the heat dissipation resin along the first surface. Thus, even if the pressure valve is covered with heat dissipation resin, the operation of the pressure valve can be ensured. Therefore, the first surface on which the pressure valve is provided, such as the bottom surface of a case, can be connected to the heat sink via the heat dissipation resin and used for heat dissipation (heat transfer) without hindering the operation of the pressure valve. Therefore, it is possible to provide a capacitor that can be safely mounted with high heat dissipation capacity (heat dissipation performance) by actively utilizing a structure with a heat dissipation function, such as a heat sink. In other words, it is possible to provide a capacitor that can be mounted so as to be in contact with a structure including a heat dissipation function via heat dissipation resin.

[0009] The discharge direction control structure may include a linear structural element that controls the direction along the first surface of the opening. This discharge direction control structure causes the gas to be blown out of the pressure valve in a concentrated direction. Therefore, the concentrated gas can more reliably remove a limited area of ​​the heat dissipation resin that is applied or filled during mounting, and a discharge route for the gas blown out of the pressure valve can be secured.

[0010] The discharge direction control structure of the pressure valve may include a first structural element (first part) and a second structural element (second part) that have different pressure resistance strengths and intersect or contact each other. By combining the first and second structural elements, each having a different pressure resistance strength and having a lower pressure resistance strength than other parts of the first surface, a controlled heterogeneous structure can be introduced, providing a structure that opens in a predetermined direction by being partially deformed and partially fractured. These structural elements may be structures that can be introduced into the first surface, such as grooves, protrusions, or steps. The strength of the structural elements may be controlled by changing their length and / or shape, such as depth, width, wall thickness, or cross-sectional shape.

[0011] The discharge direction control structure may include a first groove and a second groove that differ in at least one of their lengths and shapes and intersect or contact each other. The second groove may be shallower than the first groove. In this pressure valve, when operated, the first groove forms an opening, and the second groove can control the direction in which the opening faces. The depth d1 of the first groove, the depth d2 of the second groove, and the thickness t of the portion of the first surface of the case, in addition to the above condition (0), may satisfy the following conditions (1) and (2). 0 <d2 / d1<1 ···(0) 0.3 <d1 / t<0.95···(1) 0.1 <d2 / t<0.85···(2)

[0012] The total length of the first groove may be shorter than the total length of the second groove. The total length of the first groove may be longer than the total length of the second groove. The maximum length L of the straight portion of the first groove and the second groove, and the diameter or diagonal length D of the first surface may satisfy the following condition (3). 0.1 <L / D<0.95···(3) If the first surface is the end face of the case, the strength of the case itself can be easily ensured by making the length of the groove shorter than its diameter or diagonal length. The lower limit of condition (3) may be 0.3, and the upper limit may be 0.7.

[0013] The discharge direction control structure may include a plurality of third structural elements that have lower pressure resistance than other parts of the first surface and intersect or contact each other at the periphery of the first surface. In this discharge direction control structure, at least a portion of the intersecting or contacting third structural elements breaks to form an opening, and by providing the break point at the periphery of the first surface, the opening is oriented diagonally to the first surface due to the difference in strength between the central part of the first surface and the third structural elements, thereby controlling the gas discharge direction. The discharge direction control structure may include a plurality of fourth structural elements that have lower pressure resistance than other parts of the first surface and are in contact at an acute angle. At least a portion of the acute-angled fourth structural elements break to form an opening, and by setting the direction of contact at the acute angle, the gas discharge direction can be controlled. The plurality of fourth structural elements may be arranged to form a plurality of adjacent acute angles. When the plurality of fourth structural elements are adjacent to each other and form three or more acute angles, the angle at which the outermost structural elements of those fourth structural elements are in contact may be 180 degrees or less. The discharge direction control structure may include structural elements that have lower pressure resistance than other parts of the first surface and are rotationally asymmetric with respect to the center of the first surface. The first surface of the capacitor may be provided with a mark indicating the discharge direction of the discharge direction control structure.

[0014] This capacitor may have a filling area for filling with heat dissipation resin during mounting. The filling area may include a region containing a pressure valve. The capacitor may also have a convex structure protruding from the case to define the filling area. The convex structure may be intermittent, and in coordination with the discharge direction control structure, the position where the convex structure is interrupted may coincide with or approximate the discharge control direction by the discharge direction control structure.

[0015] Another aspect of the present invention is an electronic or electrical device, such as a power supply, charging device, or converter, comprising the capacitor described above and a structure including a heat dissipation function, wherein the first surface of the capacitor case is positioned to face the wall surface of the structure, and a heat dissipation resin is filled in a filling area between the first surface and the wall surface. The capacitor comprises a case housing a capacitor element and a pressure valve provided on the first surface of the case, wherein the pressure valve has a lower pressure resistance strength than other parts of the first surface and further includes a portion that opens obliquely to the first surface due to an increase in internal pressure of the case, and the capacitor can be positioned so that the first surface of the case faces the wall surface of the structure including the heat dissipation function, and a heat dissipation resin can be filled between the first surface and the wall surface. [Brief explanation of the drawing]

[0016] [Figure 1] A perspective view illustrating the capacitor's structure. [Figure 2] This diagram schematically illustrates the operation of a pressure valve, with Figure 2(a) showing the valve before operation and Figure 2(b) showing the valve after operation. [Figure 3] Figure 3(a) shows the capacitor in its mounted state, and Figure 3(b) shows the capacitor viewed from the bottom. [Figure 4] Figure 4(a) shows the capacitor in its mounted state, and Figure 4(b) shows the mounted capacitor seen through the heat sink. [Figure 5] Figure 5(a) shows the pressure valve in operation with the capacitor installed, and Figure 5(b) shows the same state as seen through the heat sink. [Figure 6] Figures 6(a) to 6(h) show different examples of discharge direction control structures. [Figure 7] Figures 7(a) to 7(d) show different examples of discharge direction control structures. [Figure 8] A perspective view illustrating the overview of different capacitors. [Figure 9] Figure 9(a) shows different examples of capacitors in a mounted state, and Figure 9(b) shows the mounted capacitors seen through the heat sink. Embodiment of the Invention

[0017] Figure 1 shows an example of a capacitor according to the present invention. This capacitor (capacitor, energy storage device) 10 includes a case 20 housing a capacitor element 11 and a pressure valve 25 provided on the end face (first surface) 21 of the case 20. The pressure valve 25 includes a discharge direction control structure (discharge direction control mechanism, discharge direction control function, discharge direction control device, discharge direction control system) 24 including two types of grooves 26a and 26b of different depths. The discharge direction control structure 24 in this example is formed by a K-shaped groove pattern overall, with two shallow grooves 26b in contact with the approximate center of a deep first groove 26a. In the discharge direction control structure 24 in this example, the first groove 26a and the second groove 26b are a first structural element (first part) 27a and a second structural element (second part) 27b that intersect or contact each other, respectively. These structural elements 27a and 27b have lower pressure resistance than the rest of the end face (first surface) 21, and their respective pressure resistances differ. As a result, the first structural element 27a and the second structural element 27b deform due to the increase in internal pressure of the case 20, and a portion of them fracture, forming an opening oblique to the first surface 21. The difference in pressure resistance between the first structural element 27a and the second structural element 27b can be created by changing their length, shape, such as depth, width, wall thickness, and cross-sectional shape.

[0018] An example of a capacitor 10 is an electrolytic capacitor. An example of a capacitor element 11 is a capacitor element wound with a separator made of electrolytic paper or the like interposed between an anode foil and a cathode foil. An example of an anode foil is an aluminum foil having an oxide film layer on both sides, and the anode foil and cathode foil are each connected to a pair of terminals 12 via lead tabs. The capacitor element 11 is housed in an outer case 20 with an electrolyte impregnated in it, and the opening is sealed by a sealing body 15 with the terminals 12 protruding. The capacitor 10 may be a solid electrolytic capacitor, for example a conductive polymer aluminum solid electrolytic capacitor (conductive polymer capacitor), or an electric double-layer capacitor. The capacitor 10 that is the subject of the present invention may be any type of capacitor (capacitor) that is provided with a pressure valve 25.

[0019] An example of the outer case 20 is a bottomed cylindrical shape and is formed of a metal such as aluminum. The capacitor 10 has a pressure valve (explosion-proof valve, safety valve) 25 provided on the outer surface of the central portion of the end face (bottom face, first face) 21 of the case 20. The capacitor 10 typically self-heats due to the current (ripple current, ripple current) flowing when the load current to the IC fluctuates in a power supply circuit or the like. Therefore, in order to provide a capacitor 10 capable of handling high ripple, it is desirable to improve the heat dissipation ability (heat dissipation function). Further, it is important to prevent the capacitor 10 from collapsing by discharging the gas or liquid inside the case 20 from the pressure valve 25 before the sealing body 15 is broken when the internal pressure of the case 20 exceeds a predetermined value due to self-heating.

[0020] Therefore, the capacitor 10 has a pressure valve 25 that operates at a stage where the internal pressure of the case 20 is lower than the stage where the sealing body 15 is deformed. For example, the valve operating pressure of the pressure valve 25 is set to 10 to 200 N / cm 2 The pressure valve 25 is provided such that, at a stage lower than the stage where the sealing body 15 is deformed, the groove portions 26a and 26b, which are structural elements, are deformed and a part thereof is broken (destroyed), thereby generating cracks in the groove portions 26a and / or 26b to suppress the increase in the internal pressure of the case 20. In the case of the cylindrical case 20, typically, the diameter D is 10 to 40 mm and the axial length is 15 to 100 mm. However, the size of the case 20 of the capacitor 10 is not limited to these values.

[0021] Fig. 2 schematically shows the operation of the discharge direction control structure 24 of the pressure valve 25. Fig. 2(a) schematically shows the cross-sectional structure of the portion of the discharge direction control structure 24 of the pressure valve 25. This capacitor 10 includes a pressure valve 25 including a discharge direction control structure 24 composed of grooves 26a and 26b formed by pressing or the like on the circular bottom surface (first surface) 21 of the case 20. The width W of the grooves 26a and 26b may be in the range of 0.2 to 2 mm, or may be in the range of 0.3 to 1 mm. The widths W of the grooves 26a and 26b may be the same or different. The depth d1 of one groove (first groove) 26a constituting the discharge direction control structure 24 is larger than the depth d2 of the other groove (second groove) 26b. Therefore, the pressure resistance strength of the first structural element (first portion) 27a including the first groove 26a is lower than the pressure resistance strength of the second structural element (second portion) 27b including the second groove 26b.

[0022] As shown in Fig. 2(b), when the internal pressure of the case 20 of the capacitor 10 rises and reaches the design pressure of the pressure valve 25, the discharge direction control structure 24 causes the first groove 26a and the second groove 26b to deform and partially break. In this example, the first groove 26a breaks to form an opening 22, and the second groove 26b deforms without breaking and controls the direction in which the opening 22 opens. That is, in the pressure valve 25, due to the discharge direction control structure 24, the opening 22 does not open perpendicular (axial direction) to the bottom surface 21 due to the increase in the internal pressure of the case 20, but opens in a direction oblique to the bottom surface 21. Therefore, when the pressure valve 25 operates in the capacitor 10 of this example, the ejecta 19 such as gas generated inside the case 20 is blown out in a direction along the bottom surface 21 rather than in the axial direction perpendicular to the bottom surface 21 through the opening 22 controlled by the discharge direction control structure 24.

[0023] Conventional pressure valves with multiple grooves break all the grooves to form an opening, causing gas to be blown out in a nearly vertical direction. The pressure valve 25 of the present invention includes a discharge direction control structure 24. The discharge direction control structure 24 in this example includes two types of structural elements 27a and 27b, one of which (the second structural element) 27b does not break but controls the direction in which the opening 22 opens. Therefore, the first structural element 27a, which has low pressure resistance, functions as the pressure valve 25, while the second structural element 27b, which has high pressure resistance, is a structure for controlling the direction of the opening 22 and acts as a dummy structural element in the pressure valve 25.

[0024] Specifically, the second groove 26b of the K-shaped discharge direction control structure 24 is shallower than the first groove 26a and is a dummy pattern that does not actually function as a pressure valve 25 to reduce the internal pressure of the case 20. The dummy pattern second groove 26b controls the orientation (opening direction) of the opening 22 formed by the first groove 26a and controls the discharge direction of the ejected material (gas, steam, fluid) 19 that caused the increase in internal pressure of the case 20. Furthermore, the second groove 26b is a linear structural element that extends in the circumferential direction and controls the opening 22 formed by the first groove 26a to face the circumferential direction (outward) of the bottom surface 21. As a result, the ejected material 19 is mainly (concentrated) discharged from the opening 22 in a direction that is almost perpendicular to the first groove 26a in the circumferential direction.

[0025] The depth d1 of the first groove 26a and the depth d2 of the second groove 26b, which constitute the discharge direction control structure 24 of the pressure valve 25, and the thickness t of the bottom surface (first surface) 21 of the case 20 may satisfy the following conditions (1) and (2), in addition to the condition (0) above that depth d1 is deeper than depth d2. 0 <d2 / d1<1 ···(0) 0.3 <d1 / t<0.95···(1) 0.1 <d2 / t<0.85···(2) The lower limit of condition (1) may be 0.4, and the upper limit of condition (2) may be 0.3. For example, the thickness t of the bottom surface 21 may be 0.3 to 0.7 mm, the depth d1 of the first groove 26a may be 0.3 to 0.47 mm, and the depth d2 of the second groove 26b may be 0.2 to 0.4 mm. The remaining wall thickness td1 of the portion of the first groove 26a (first structural element) 27a may be 0.02 to 0.1 mm, or 0.03 to 0.06 mm. Also, the remaining wall thickness td2 of the portion of the second groove 26b (second structural element) 27b may be 0.05 to 0.15 mm, or 0.07 to 0.13 mm. The difference between the remaining wall thickness td1 of the portion of the first groove 26a and the remaining wall thickness td2 of the portion of the second groove 26b is necessary but may be small.

[0026] For example, instead of grooves 26a and 26b that are engraved from the outside of the case 20, the discharge direction control structure 24 may be constructed by protrusions (convex parts) that are engraved from the inside of the case 20, or by a structure that involves steps or other thinning (thickening). In that case, the remaining thickness td1 of the first structural element 27a is smaller than the remaining thickness td2 of the second structural element 27b, and furthermore, the following conditions (0') to (2') may be satisfied. 0 <td1 / td2<1 ···(0´) 0.05 <td1 / t<0.7···(1´) 0.15 <td2 / t<0.9···(2´)

[0027] By making a dummy pattern of sufficient depth to satisfy condition (2) a part of the discharge direction control structure (groove type) 24 that constitutes the pressure valve 25, the reduction in the strength of the case 20 can be suppressed by providing the pressure valve 25. As a result, the thickness of the case 20, especially the thickness of the bottom surface 21, can be reduced, and a lighter and lower-cost capacitor 10 can be provided.

[0028] Figure 3 shows the assembly of a device including a capacitor 10, for example, a power supply unit 1. The power supply unit 1 may be a charging device, a converter, or an electronic or electrical device including these. As shown in Figure 3(a), the power supply unit 1 includes a structure with a heat dissipation function, for example, an outer wall or heat sink 5, a capacitor 10, and a circuit board 3 on which the capacitor 10 is mounted. The capacitor 10 is positioned such that the bottom surface (first surface) 21 of the case 20 faces the wall surface 5a of the heat sink 5, which is the structure. The bottom surface 21 is provided with a pressure valve 25 including a discharge direction control structure 24 consisting of a first groove 26a and a second groove 26b, as shown in Figure 2(b).

[0029] The discharge direction control structure 24 in this example has a roughly K-shaped pattern in which two shallow second grooves 26b are in contact with one first groove 26a. In the discharge direction control structure 24 in this example, the total length (2 × M) of the second grooves 26b is longer than the total length L of the first groove 26a (the total length L of the first groove 26a is shorter than the total length (2 × M) of the second grooves 26b). In this discharge direction control structure 24, the first groove 26a constitutes a first structural element 27a with low pressure resistance strength, and becomes an opening 22 when the pressure valve is operated. In contrast, the second structural element 27b, which is composed of the second grooves 26b which are a dummy pattern, has relatively high pressure resistance strength and is easily deformed when the pressure valve is operated. By making the distance between them relatively large (long), the direction of the opening 22 can be controlled to open in a predetermined direction, for example, obliquely to the bottom surface 21, and further toward a predetermined direction (radial direction) around the periphery (around) of the bottom surface 21.

[0030] The second structural element 27b, which is deformed by the second groove 26b constituting the discharge direction control structure (pattern) 24, may be shorter than the first structural element 27a, which is deformed or opens by the first groove 26a. The first groove 26a may be provided along the periphery of the first surface 21, and a relatively wide opening 22 may open along the periphery of the first surface 21, from which the gas 19 is blown out along the periphery of the first surface 21. The total length of the first groove 26a may be longer than the total length of the second groove 26b.

[0031] Furthermore, the maximum length of the straight portion of the first groove 26a and the second groove 26b, in this example the length L of the first groove 26a, and the diameter or diagonal length D of the bottom surface (first surface) 21 may satisfy the following condition (3). 0.1 <L / D<0.95···(3) The lower limit of condition (3) may be 0.3, and the upper limit may be 0.7. The pressure valve 25 is often provided on the bottom surface (end surface, first surface) 21 of the case 20, and if the length of the structural element (groove) of the discharge direction control structure 24 is about the same as the diameter D, the structural element may reach the boundary portion between the bottom surface 21 and the side surface or its vicinity, which may cause a decrease in the strength of the case 20. For example, the diameter D of the bottom surface 21 may be 6 to 40 mm, and the length L of the first groove 26a may be 3 to 30 mm.

[0032] Figure 4 shows an assembled device including a capacitor 10, such as a power supply unit 1. The capacitor 10 has a filling area 28 into which heat dissipation resin 50 is filled during mounting, and the filling area includes a pressure valve 25 on the first surface 21. As shown in Figures 4(a) and (b), the heat sink 5 of the power supply unit 1 is positioned so that its wall surface 5a faces the bottom surface 21 of the capacitor 10, and the heat dissipation resin 50 is filled between the filling area 28 including the pressure valve 25 on the bottom surface 21 of the case 20 and the wall surface 5a of the heat sink 5. Examples of heat-dissipating resins 50 include silicone resins, olefin resins, synthetic rubber, etc. The physical properties of the resin 50 may be such that the breaking strength is 3 MPa or less according to the measurement method (JIS K 6251), and the Young's modulus may be in the range of 0.2 to 8 MPa or 0.5 to 3 MPa. The resin may be soft, for example, a resin whose glass transition temperature (Tg) is in the region of 0°C or below. The resin may also be a resin whose glass transition temperature (Tg) is in the region of -20°C or below, or in the region of -30°C or below, or in the region of -40°C or below. For example, the glass transition temperature (Tg) of silicone rubber is -123°C, that of polyethylene is -125°C, that of polyurethane is -20°C, and that of polyvinylidene fluoride is -35°C, and all are sufficiently soft at room temperature.

[0033] This capacitor 10 can be mounted in a stable state by filling the space between the heat sink 5 and the bottom surface 21 of the case 20 with heat dissipation resin 50, and the heat sink 5 and the bottom surface 21 can be connected (closely attached) in a way that allows heat transfer via the heat dissipation resin 50. As a result, the heat sink 5 and the case 20 can be mounted in a state with good thermal conductivity, and the heat generated by the capacitor 10 can be efficiently released (dissipated) through the heat sink 5.

[0034] Figure 5 shows the state when the pressure valve 25 is operating. As indicated by the arrows 55 in Figures 5(a) and (b), when the pressure valve 25 is operating, the discharge direction control structure 24 controls the direction in which the opening 22 opens, and the ejected material 19 is blown out along the bottom surface (first surface) 21. As a result, the heat dissipation resin 50, which is relatively low in strength, highly flexible, viscous, or nonplastic, is discharged (blowed out) out of the filling area 28 of the bottom surface 21 by the pressure of the gas or liquid (ejected material) 19 released from the pressure valve 25, or together with the ejected material 19.

[0035] More specifically, when the pressure valve 25 operates, the first groove 26a and the second groove 26b of the discharge direction control structure 24 work together, causing the opening 22 formed by the first groove 26a to open obliquely to the bottom surface 21 and in the circumferential direction. As a result, the ejected material 19 is blown out along the bottom surface 21 in the circumferential direction. The ejected material 19 pushes (blows out) the heat dissipation resin 50 filled between the bottom surface 21 and the heat sink 5 along the bottom surface 21 in the circumferential direction. Therefore, even though the pressure valve 25 is covered with the heat dissipation resin 50, when the internal pressure of the case 20 rises due to heat generation or the like and reaches a predetermined pressure, the pressure valve 25 operates normally (as designed) without being affected by the heat dissipation resin 50.

[0036] In recent years, there has been a demand for higher ripple current and higher capacitance capacitors 10 used on the input side of automotive products and the like. To increase the ripple current of the capacitor 10, efforts have been made to reduce self-heating by reviewing the materials and internal structure of the capacitor 10 in order to suppress the reduction in product life due to internal heat generation. Furthermore, in order to provide a capacitor 10 that can handle high ripple current, matching or collaborating with the circuit design side, such as the power supply unit 1, on heat dissipation technology is important. One way to do this is to improve the heat dissipation effect by injecting or inserting a heat dissipation resin (heat dissipation resin) 50 between the heat sink 5 and the capacitor 10. At the same time, when applying resin to the capacitor 10 or when applying resin to a part of the capacitor 10, it is necessary to ensure that the operation of the pressure valve 25 is not obstructed.

[0037] The pressure valve 25 partially reduces the strength of the capacitor 10's case 20. Therefore, it is desirable that it be installed in a structurally stable part of the case 20. For example, if the case 20 is a cylindrical aluminum case, the bottom surface 21 of the case 20 is one of the suitable locations (surfaces) for installing the pressure valve 25. When applying heat dissipation resin 50 to the case 20, it is desirable that the filling area 28 is a stable shape, such as a flat surface, that can secure a contact area with the heat sink 5. In the case of a cylindrical case 20, the flat bottom surface 21 is the most suitable surface for setting the filling area 28. However, conventionally, applying resin 50 to the bottom surface 21 has not been done because it would be applied over the pressure valve 25, which would interfere with the operation of the pressure valve 25.

[0038] The capacitor 10 in this example overturns the conventional idea described above, and makes it possible to blow away the resin 50 applied on the pressure valve 25 by the operation of the pressure valve 25. That is, by including a discharge direction control structure 24 in the pressure valve 25 provided on the bottom surface 21 of the capacitor 10, the opening 22 opens diagonally to the bottom surface 21 due to the increase in internal pressure of the case 20, rather than opening perpendicular or axially to the bottom surface 21. As a result, the heat dissipation resin 50 is removed from above the pressure valve 25 by the operation of the pressure valve 25. Therefore, even if the pressure valve 25 is covered with heat dissipation resin 50, the operating range of the pressure valve 25 is secured, and a capacitor 10 is provided that can operate the pressure valve 25 normally. For this reason, a capacitor 10 can be provided that can be implemented in a way that further promotes heat dissipation through the bottom surface 21 on which the pressure valve 25 is provided, and safety is also ensured.

[0039] The heat dissipation resin 50 applied to the heat sink 5 on the pressure valve 25 of the capacitor 10 to an arbitrary thickness may be 0.5 mm or more, 1 mm or more, or 4 mm or less. The operating condition of the pressure valve 25 is 200 N / cm 2 In this case, the heat dissipation resin 50 applied to the heat sink 5 on the pressure valve 25 of the capacitor 10 to an arbitrary thickness is compressed by the displacement of the case 20 when the pressure valve 25 is operated, and the rebound pressure after compression is 200 N / cm 2 The following materials may also be used.

[0040] The discharge direction control structure 24 of the pressure valve 25 only needs to be able to control the gas discharge direction to the horizontal direction, that is, along the bottom surface 21. An example of the discharge direction control structure 24 may include a structure (pattern) that is symmetrical with respect to only one of the countless lines passing through the center of the disc-shaped bottom surface 21 of the capacitor case 20, and asymmetrical with respect to the other lines. An example of the discharge direction control structure 24 may be symmetrical as a whole, but if it includes multiple types of grooves 26a and 26b with different pressure resistance strengths, the distribution or arrangement of the pressure resistance strengths may be asymmetrical. An example of the discharge direction control structure 24 may include structural elements that have lower pressure resistance strength than other parts of the first surface 21 and are rotationally asymmetrical with respect to the center of the first surface 21. The roughly K-shaped discharge direction control structure 24 described above is one example that satisfies the above conditions. Further examples of different discharge direction control structures 24 will be described below.

[0041] Figure 6 shows several examples of the discharge direction control structure (pattern) 24. The discharge direction control structure (pattern) 24a shown in Figure 6(a) has a first groove 26a that forms an opening 22 and a shallow second groove 26b that is a dummy pattern, and these are combined to form a cross that is biased toward the circumferential side (outside). The discharge direction control structure (pattern) 24b shown in Figure 6(b) has a first groove 26a that forms an opening 22 and a second groove 26b that is a dummy pattern, and these are combined like a bow and arrow toward the circumferential side (outside). The discharge direction control structure (pattern) 24c shown in Figure 6(c) has a first groove 26a that forms an opening 22 and a second groove 26b that is a dummy pattern, and these are combined in a T shape toward the circumferential side (outside). The discharge direction control structure (pattern) 24d shown in Figure 6(d) has a first groove 26a which forms an opening 22 and a second groove 26b which is a dummy pattern, and these are arranged in an anchor shape facing circumferentially (outward). Each of the grooves 26a and 26b that make up these discharge direction control structures 24a to 24d may be straight, curved, or bent. These discharge direction control structures (patterns) 24a to 24d have a first groove 26a and a second groove 26b of different strengths, which intersect or contact each other, and the first groove 26a is controlled by the second groove 26b to open circumferentially outward, blowing out the ejected material 19 in the direction of arrow 55. As a result, the heat dissipation resin 50 applied on the pressure valve 25 can be pushed out circumferentially from the bottom surface 21.

[0042] The discharge direction control structure (pattern) 24e shown in Figure 6(e) is an example of a structure in which two first grooves 26a intersect or contact each other at the periphery of the bottom surface 21. In this discharge direction control structure (pattern) 24e, the multiple grooves 26a form multiple third structural elements 27c that intersect or contact each other at the periphery of the bottom surface (first surface) 21, where the pressure resistance strength is lower than that of other parts of the bottom surface (first surface) 21. In the discharge direction control structure 24e, the area where the multiple grooves 26a intersect or contact each other has the lowest strength. Therefore, when the pressure valve 25 operates, the area where the multiple grooves 26a of the discharge direction control structure 24e intersect or contact each other opens outward in the circumferential direction at an eccentric position on the bottom surface 21, and ejects the ejected material 19 in the direction of arrow 55, similar to the pattern described above.

[0043] The discharge direction control structure (pattern) 24f shown in Figure 6(f) has two first grooves 26a and one second groove 26b of a dummy pattern, which are arranged at equal intervals (equal angles) so as to intersect or contact at the center of the bottom surface 21. The discharge direction control structure (pattern) 24g shown in Figure 6(g) has three first grooves 26a and one second groove 26b of a dummy pattern, which are arranged at equal intervals (equal angles) so as to form a cross so as to intersect or contact at the center of the bottom surface 21. In these discharge direction control structures 24f and 24g, a plurality of third structural elements 27c consisting of two or three first grooves 26a intersect or contact each other, and the portion where they intersect or contact each other becomes an opening. At the same time, the opening faces the direction of the one second groove 26b of the dummy pattern, forming an opening that is inclined circumferentially with respect to the bottom surface 21. As a result, the ejected material 19 is blown out in the direction of arrow 55. These discharge direction control structures (patterns) 24f and 24g are examples of structures in which the total length of the first groove 26a is longer than the total length of the second groove 26b, and the direction in which the ejected material 19 is ejected can be controlled by changing the lengths of the first groove 26a and the second groove 26b.

[0044] The discharge direction control structures (patterns) 24f and 24g are rotationally symmetrical as a whole with respect to the center of the bottom surface 21, provided that the first groove 26a and the second groove 26b are common grooves. However, the first groove 26a and the second groove 26b, which is a dummy pattern, have different depths and are not the same groove. Therefore, the respective discharge direction control structures 24f and 24g are rotationally asymmetrical. The discharge direction control structures 24f and 24g are located at the center of the bottom surface 21, away from its periphery. As a result, they have little impact on the strength of the peripheral part of the bottom surface 21, and it is easier to suppress a decrease in the strength of the case 20.

[0045] The discharge direction control structure (pattern) 24h shown in Figure 6(h) is the same K-shaped pattern as the pattern shown in Figure 1, but the arrangement of the first groove 26a and the second groove 26b is reversed. In this discharge direction control structure 24h, an opening is formed by multiple first grooves 26a, and its direction is controlled by the second groove 26b, which is a dummy pattern. Therefore, the ejected material 19 can be controlled to be blown out in the direction of the arrow 55. If the blowing direction is not easily determined at a glance, for example, in a capacitor 10 having discharge direction control structures 24f, 24g and 24h, a mark 57 indicating the blowing direction may be provided on the bottom surface (first surface) 21, as shown in Figures 6(f), 6(g), and 6(h). The shape of the mark 57 is not limited to the arrow in this example, but can be a triangle, a dot, or anything that indicates direction. In addition, the capacitor 10 may be provided with a mark 57 indicating the blowing direction along with all of the discharge direction control structures 24.

[0046] Figure 7 shows several other different examples of the discharge direction control structure 24. The discharge direction control structure 24i shown in Figure 7(a) includes a plurality of first grooves 26a which have a lower pressure resistance than other parts of the first surface 21 and form an opening when the internal pressure of the case 20 increases, and includes a plurality of fourth structural elements 27d which are in contact with an acute angle 29. The angle α of the acute angle 29 may be less than 90° (90 degrees) and may be less than 80°. The plurality of fourth structural elements 27d forming the acute angle 29 become the starting point of the opening. Therefore, when the internal pressure of the case 20 increases, the apex of the acute angle 29 becomes the starting point for forming an opening, and the ejected material 19 is released in the direction of arrow 55, which in turn makes it easier for the ejected material 19 to be further released to the outside by rupturing the heat dissipation resin.

[0047] The discharge direction control structure 24j shown in Figure 7(b) includes two fourth structural elements 27d, each composed of two first grooves 26a that are in contact with the acute angle 29. The discharge direction control structure 24k shown in Figure 7(c) includes three fourth structural elements 27d, each composed of three first grooves 26a that are in contact with the acute angle 29. The angle α of the acute angle 29 formed by each of the fourth structural elements 27d may be less than 50° or less than 45°.

[0048] The discharge direction control structure 24l shown in Figure 7(d) has four first grooves 26a that form four fourth structural elements 27d, which are in contact with each other to form three acute angles 29. The number of first grooves 26a (fourth structural elements 27d) that are in contact to form acute angles 29 may be four or more, and the number of acute angles 29 formed by them being adjacent may be three or more. In a discharge direction control structure 24l that includes multiple (n+1) fourth structural elements 27d to form n acute angles 29, the angle β at which the outermost structural elements of those fourth structural elements 27d (first grooves 26a) are in contact may be 180 degrees or less in order to control the discharge direction with precision.

[0049] Figures 8 and 9 show different examples of the capacitor 10. This capacitor 10 has a convex structure 30 formed along the outer circumference of the bottom surface 21 of a cylindrical case 20. As shown in Figure 8, this capacitor 10 can be mounted with high heat dissipation capacity by positioning the convex structure 30 on the bottom surface 21 of the case 20 to make contact with the wall surface 5a of a structure 5 that includes a heat dissipation function, and filling the filling area 28 between the bottom surface 21 and the wall surface 5a with a heat dissipation resin 50. The convex structure 30 may be formed by press-forming a plurality of wall-like protrusions 33 so that a part of the periphery of the bottom surface 21 of the case 20 protrudes, or it may be molded from resin. Examples of resins for molding the protrusions 33 include epoxy resin, olefin resin, acrylic resin, polyimide resin, polyamide-imide resin, phenolic resin, photosensitive resin, and thermosetting resin.

[0050] The convex structure (convex structure) 30 rising from the bottom surface 21 may include a plurality of wall structures (walls) 33 that rise intermittently in a wall-like manner with intervals 34 along a portion of the outer circumference of the bottom surface 21 of the case 20. The capacitor 10 may include a pressure valve 25 with a K-shaped discharge direction control structure 24 on the bottom surface 21, and the convex structure 30 may surround the area 28 including the pressure valve 25 on the bottom surface 21, defining the area inside the convex structure 30 as an area 28 for filling with heat dissipation resin.

[0051] The convex structure 30 may have one of the interrupted positions (gaps) 34 coincide with or approximate the discharge control direction 55 by the discharge direction control structure 24. When the pressure valve 25 operates, gas or liquid (spurt) 19 is released from the pressure valve 25 in the direction 55 controlled by the discharge direction control structure 24, and due to the pressure, or together with the spurt 19, the heat dissipation resin 50 is released or pushed outward through a part of the gap 34 in the wall structure 33, which becomes the outlet 35. For this reason, even though the pressure valve 25 is covered with the heat dissipation resin 50, when the internal pressure of the case 20 rises due to heat generation or the like and reaches a predetermined pressure, the pressure valve 25 can operate normally.

[0052] The maximum protrusion of the convex structure 30 from the bottom surface (first surface) 21 may be 0.1 to 4.0 mm. Since the filling area 28 is surrounded by the convex structure 30, a relatively low-strength, highly flexible, viscous, or non-plastic heat dissipation resin 50, such as a grease-like or gel-like silicone resin, can be stably filled between the heat sink 5 and the bottom surface 21 of the case 20. This makes it easier to ensure good adhesion between the heat sink 5 and the bottom surface 21, and provides a capacitor 10 that connects the heat sink 5 and the case 20 in a state of good thermal conductivity. Furthermore, the capacitor 10 can be mounted in a state where self-heating can be efficiently dissipated via the heat sink 5.

[0053] In the above, for the purpose of explaining the present invention, a capacitor 10 equipped with a pressure valve 25 including several different discharge direction control structures 24 is given as an example. However, the configuration of the capacitor 10 included in the present invention is not limited to the above and is as described in the claims. This disclosure includes the following aspects: <Aspect 1> A case containing a capacitor element, The case has a pressure valve provided on the first surface of the case, A capacitor, wherein the pressure valve includes a discharge direction control structure that deforms due to an increase in internal pressure of the case, causing at least a portion of it to break and open obliquely to the first surface. <Aspect 2> In Embodiment 1, The discharge direction control structure includes a capacitor with a linear structural element that controls the direction along the first surface of the opening. <Aspect 3> In embodiment 1 or 2, The discharge direction control structure includes a capacitor comprising a first structural element and a second structural element having different pressure resistance strengths and intersecting or in contact with each other. <Aspect 4> In embodiment 1 or 2, The discharge direction control structure includes a capacitor comprising a first groove and a second groove that differ in at least one of their lengths and shapes and intersect or contact each other. <Aspect 5> In embodiment 4, The second groove is shallower than the first groove, and is a capacitor. <Aspect 6> In aspect 5, A capacitor in which the depth d1 of the first groove, the depth d2 of the second groove, and the thickness t of the first surface of the case satisfy the following conditions. 0.3 <d1 / t<0.95 0.1 <d2 / t<0.85 A capacitor that satisfies the requirements. <Aspect 7> In embodiment 5 or 6, A capacitor in which the total length of the first groove is shorter than the total length of the second groove. <Aspect 8> In embodiment 5 or 6, A capacitor in which the total length of the first groove is longer than the total length of the second groove. <Pattern 9> In any of aspects 5 to 8, A capacitor in which the maximum length L of the straight portion of the first groove and the second groove, and the diameter or diagonal length D of the first surface satisfy the following conditions. 0.1 <L / D<0.95 <Aspect 10> In embodiment 1 or 2, A capacitor wherein the discharge direction control structure includes a plurality of third structural elements that have lower pressure resistance than other parts of the first surface and intersect or contact each other at the periphery of the first surface. <Aspect 11> In embodiment 1 or 2, The discharge direction control structure includes a plurality of fourth structural elements that have lower pressure resistance than other parts of the first surface and are in contact at an acute angle to the capacitor. <Aspect 12> In embodiment 11, A capacitor in which the plurality of fourth structural elements are in contact with each other at least three acute angles, and the angle at which the outermost structural elements of these fourth structural elements are in contact is 180 degrees or less. <Aspect 13> In embodiment 1 or 2, The discharge direction control structure includes a capacitor having a lower pressure resistance strength than other parts of the first surface and a structural element that is rotationally asymmetric with respect to the center of the first surface. <Aspect 14> In any of the embodiments 1 to 13, A capacitor having a mark on the first surface indicating the discharge direction of the discharge direction control structure. <Aspect 15> In any of the embodiments 1 to 14, A capacitor having a filling area for filling with heat dissipation resin during mounting, wherein the filling area includes the pressure valve. <Aspect 16> A capacitor in embodiment 15, further having a convex structure protruding from the case so as to define the filling area. <Aspect 17> In embodiment 16, A capacitor in which the convex structure is intermittent, and the position where the convex structure is interrupted coincides with or approximates the discharge control direction by the discharge direction control structure. <Aspect 18> In any of embodiments 15 to 17, A capacitor is mounted so as to be in contact with a structure that includes a heat dissipation function, via the heat dissipation resin. <Aspect 19> A capacitor according to any one of embodiments 1 to 14 and a structure including a heat dissipation function, An apparatus in which the first surface of the case of the capacitor is positioned to face the wall surface of the structure, and a heat dissipation resin is filled in the filling area between the first surface and the wall surface.

Claims

1. A case containing a capacitor element, The case has a pressure valve provided on the first surface of the case, The pressure valve includes a discharge direction control structure that deforms due to the increase in internal pressure of the case, causing at least a portion to break and open obliquely to the first surface. The discharge direction control structure includes a plurality of fourth structural elements that have lower pressure resistance than other parts of the first surface and are in contact at an acute angle. The aforementioned plurality of fourth structural elements are in contact with each other in such a way that they form at least three acute angles, and the angle at which the outermost structural elements of these fourth structural elements are in contact is 180 degrees or less. Capacitor.

2. A case housing a capacitor element, The case has a pressure valve provided on the first surface of the case, The pressure valve includes a discharge direction control structure that deforms due to the increase in internal pressure of the case, causing at least a portion to break and open obliquely to the first surface. The first surface has a mark indicating the blowing direction of the discharge direction control structure, Capacitor.

3. A case housing a capacitor element, A pressure valve provided on the first surface of the case and A capacitor having, The pressure valve includes a discharge direction control structure that deforms due to the increase in internal pressure of the case, causing at least a portion to break and open obliquely to the first surface. The discharge direction control structure includes a first groove and a second groove that differ in at least one of their lengths and shapes and intersect or contact each other. The second groove is shallower than the first groove, A capacitor that satisfies any of the following conditions (i) to (v): (i) The discharge direction control structure is formed in a K-shaped groove shape overall, with two second grooves in contact with the center of the first groove; (ii) The first groove and the second groove are arranged to form a cross that is biased toward the circumferential side; (iii) The first groove and the second groove are arranged in a T-shape toward the circumferential side; (iv) The three first grooves and the one second groove are arranged at equal intervals to form a cross shape, intersecting or in contact with the center of the first surface; (v) The discharge direction control structure is formed in a K-shaped groove shape overall, with two first grooves in contact with the center of the second groove.

4. In claim 3, A capacitor in which the depth d1 of the first groove, the depth d2 of the second groove, and the thickness t of the first surface of the case satisfy the following conditions. 0.3<d1 / t<0.95 0.1<d2 / t<0.85 A capacitor that satisfies the requirements.

5. In claim 3 or 4, A capacitor in which the total length of the first groove is shorter than the total length of the second groove.

6. In claim 3 or 4, A capacitor in which the total length of the first groove is longer than the total length of the second groove.

7. In claim 3 or 4, A capacitor in which the maximum length L of the straight portion of the first groove and the second groove, and the diameter or diagonal length D of the first surface satisfy the following conditions. 0.1<L / D<0.95

8. In any of claims 1 to 4, The discharge direction control structure includes a capacitor with a linear structural element that controls the direction along the first surface of the opening.

9. In claim 2 or 3, The discharge direction control structure includes a capacitor comprising a first structural element and a second structural element having different pressure resistance strengths and intersecting or in contact with each other.

10. In claim 2 or 3, A capacitor comprising a plurality of third structural elements having lower pressure resistance than other parts of the first surface and intersecting or in contact with each other at the periphery of the first surface.

11. In claim 2 or 3, The discharge direction control structure includes a capacitor having a lower pressure resistance strength than other parts of the first surface and a structural element that is rotationally asymmetric with respect to the center of the first surface.

12. In any of claims 1 to 4, A capacitor having a filling area for filling with heat dissipation resin during mounting, wherein the filling area includes the pressure valve.

13. The capacitor according to claim 12, further having a convex structure protruding from the case so as to define the filling area.

14. In claim 13, A capacitor in which the convex structure is intermittent, and the position where the convex structure is interrupted coincides with or approximates the discharge control direction by the discharge direction control structure.

15. In claim 12, A capacitor is mounted so as to be in contact with a structure that includes a heat dissipation function, via the heat dissipation resin.

16. A capacitor according to any one of claims 1 to 4, and a structure including a heat dissipation function, An apparatus in which the first surface of the case of the capacitor is positioned to face the wall surface of the structure, and a heat dissipation resin is filled in the filling area between the first surface and the wall surface.

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