Electrolytic capacitor with safety vent

Abstract

Electrolytic capacitor comprising a housing (2) and a capacitor element (3) mounted in the housing (2) and comprising a safety vent (12) to allow pressure relief, wherein the safety vent (12) is positioned at least partially in a hole (4) of the capacitor element (3), wherein the capacitor (1) comprises terminals (9, 10) and a pin (17), wherein the terminals (9, 10) are positioned on a first side (6) of the capacitor (1), wherein the pin (17) is positioned on a second side (8) opposite the first side (6), and wherein the safety vent (12) is positioned in the pin (17).

Description

[0001] The present invention relates to an electrolytic capacitor with a safety vent. The safety vent is provided to enable pressure relief and thereby, for example, to prevent an uncontrolled explosion of the capacitor.

[0002] The publications DE 28 49 415 A1, US 3 463 969 A, DE 10 2006 038 157 A1, DE 10 2005 033 476 A1, JP 2011-77 181 A, FR 930 703 A, US 9 064 634 B2 and JP H11- 219 869 A each describe capacitors with safety vents.

[0003] An object of the present invention is to provide an electrolytic capacitor with improved safety venting.

[0004] Independent claims 1 and 9 each specify capacitors according to the invention. Furthermore, claim 10 specifies a method for operating the capacitor according to the invention, and claim 13 specifies a mounting arrangement with the capacitor according to the invention. Dependent claims specify advantageous embodiments.

[0005] According to one aspect, the present invention relates to an electrolytic capacitor comprising a housing and a capacitor element mounted in the housing. The housing may be in the form of a can. The capacitor element may be a wound element. The capacitor element may comprise foils, in particular aluminum foils. The capacitor element may be impregnated with an electrolyte, in particular a liquid electrolyte.

[0006] The electrolytic capacitor includes a safety vent to allow pressure relief.

[0007] During operation, the pressure inside the condenser can rise, especially in the event of an overload. The safety vent can be configured to burst when the pressure approaches a critical value. This can prevent an uncontrolled explosion of the condenser.

[0008] In addition, or as an alternative, the safety vent can allow for gradual pressure relief. In particular, continuous gas diffusion can be enabled. Gradual pressure relief can be enabled long before a critical value is reached. During the gradual pressure relief, the safety vent can remain intact.

[0009] The safety vent may comprise an elastic material. For example, the safety vent may comprise a rubber or silicone material. For example, the safety vent is inserted into the housing, for example, into a hole in the housing.

[0010] The safety vent may include a membrane. This allows for gradual diffusion of the gas generated in the condenser.

[0011] According to one embodiment, the safety vent is at least partially positioned in a hole in the capacitor element. The hole may extend along a central axis of the capacitor element. The hole may result from wrapping the foils of the capacitor element around a central axis. Accordingly, the safety vent may be surrounded by foils of the capacitor element.

[0012] The electrolytic capacitor includes terminals for electrically contacting the capacitor. The terminals are positioned on a first side of the capacitor. The terminals may be screw terminals. In other embodiments, the terminals may be configured, for example, in a snap-in design.

[0013] According to the invention, the safety vent is configured to allow pressure relief through the second side of the condenser, the second side being opposite the first side. Accordingly, the safety vent allows the gas to exit the housing through the second side. In one embodiment, the safety vent is positioned closer to the second side of the condenser than to the first side of the condenser.

[0014] By allowing pressure relief on a side remote from the first side, the risk of contamination of terminals and / or other components, such as a printed circuit board or busbar, can be reduced and the service life extended. Such contamination can occur due to electrolyte leakage from the enclosure following a rupture of the safety vent.

[0015] In one embodiment, the condenser is mounted so that the side that allows pressure relief does not face downward. For example, the side faces upward or in a horizontal direction.

[0016] In this case, electrolyte can be effectively prevented from flowing out after the safety vent bursts. Furthermore, electrolyte contamination of the safety vent during normal capacitor operation can also be prevented. This ensures that gradual diffusion is maintained when the safety vent is still intact.

[0017] In one embodiment, the capacitor is mounted with the terminal facing down. Accordingly, the terminals point downward. In another embodiment, the capacitor is mounted with the terminals arranged horizontally. In yet another embodiment, the capacitor is mounted with the terminal facing up.

[0018] In one embodiment, the safety vent is configured to allow pressure relief through the first side of the condenser. This can be particularly useful when the condenser is mounted with the port facing upwards.

[0019] The capacitor may be mounted on a mounting element. The mounting element may also provide the electrical connection of the capacitor. As an example, the mounting element may comprise a circuit board or a busbar. Alternatively, the electrical connection may be provided by an additional element to the mounting element. The capacitor may be mounted such that the first side is adjacent to the mounting element. Alternatively, the capacitor may be mounted such that the second side is adjacent to the mounting element. Alternatively, the capacitor may be mounted such that its lateral side is adjacent to the mounting element.

[0020] The capacitor may include a cover element for sealing the housing. The cover element may be positioned on the first side of the capacitor. The terminals may extend through the cover element. The cover element may comprise an elastic material, in particular a rubber material. The cover element may be an element inserted into the housing.

[0021] In one embodiment, the cover element does not have a safety vent. In an alternative embodiment, a safety vent can be positioned at least partially within the cover element.

[0022] In one embodiment, the capacitor may include a centering element extending into the hole of the capacitor element. The safety vent may be positioned in the centering element. The centering element may be provided for centering the capacitor element in the housing.

[0023] The centering element may be positioned near the second side of the capacitor. For example, the centering element may be formed integrally with the second side of the capacitor. The centering element may be formed integrally with a can bottom. For example, the centering element may be formed as a hole in the second side. The centering element may extend in a direction toward the core of the capacitor. The centering element may comprise a metal. Alternatively or additionally, the centering element may be positioned near the first side of the capacitor, for example, beneath a cover element.

[0024] The centering element can be configured to prevent contact of the electrolyte with the safety vent. In particular, the centering element can separate the safety vent from the capacitor element and the electrolyte.

[0025] The centering element may be tubular. The safety vent may be positioned within the tubular cavity. The safety vent may seal the centering element such that electrolyte leakage from the capacitor is prevented during normal operation of the device, particularly as long as the safety vent remains intact. The centering element may be open toward the core of the capacitor.

[0026] In one embodiment, the safety vent is embedded in the capacitor. In particular, the safety vent is positioned at a distance from the outer surfaces of the first and second sides. This can prevent contamination of the outer surfaces of the capacitor due to electrolyte leakage.

[0027] For example, a cavity may be present between the safety vent and a side of the capacitor, particularly the outer surface of the side through which pressure relief is permitted. The cavity may be fillable with electrolyte. In this case, the cavity can absorb any electrolyte leaking through the safety vent.

[0028] In one embodiment, the condenser includes multiple safety vents. For example, a first safety vent may allow pressure relief through the first side, and a second safety vent may allow pressure relief through the second side of the condenser.

[0029] Depending on the mounting orientation of the capacitor, at least one of the safety vents can allow pressure relief through an upwardly or horizontally oriented side. This can ensure gradual pressure relief. The further safety vent can allow pressure relief through a downwardly facing side. In some embodiments, one of the safety vents can be positioned in the hole of the capacitor element. The further safety vent can be positioned entirely outside the capacitor element. The further safety vent can, for example, be positioned in the cover element. Alternatively, both safety elements can be at least partially positioned in the hole of the capacitor element.

[0030] According to the invention, the capacitor comprises a stud bolt. The stud bolt is positioned on the second side of the capacitor. The stud bolt can be provided with a thread. The stud bolt can be used for mounting and, in particular, fixing the capacitor to a mounting element.

[0031] The safety vent is positioned in the stud bolt, particularly in a portion of the stud bolt that extends to the core of the capacitor. The stud bolt can be formed integrally with one side of the capacitor and / or formed integrally with a centering element.

[0032] According to another aspect of the present invention, an electrolytic capacitor comprises a housing, a capacitor element mounted within the housing, and a safety vent that allows for gradual pressure release. The capacitor includes terminals positioned on a first side, with the safety vent allowing pressure release through an opposite, second side of the capacitor. The capacitor may include any functional and structural features of the capacitor described above. As an example, the safety vent may comprise a diaphragm. The safety vent may be positioned in a hole of the capacitor element.

[0033] According to another aspect of the present invention, a method of operating an electrolytic capacitor including a safety vent is disclosed. The safety vent may allow gradual pressure relief through one side of the capacitor. The capacitor may be operated in an orientation where the side allowing pressure relief does not face down. For example, the side faces up or horizontally. The capacitor may include any functional and structural features of the capacitor described above. For example, the safety vent may include a diaphragm. The safety vent may be positioned in a hole of the capacitor element.

[0034] According to another aspect of the present invention, a mounting assembly is provided, the mounting assembly comprising at least one of the capacitors described above and a mounting element. The capacitor is mounted on the mounting element. In one embodiment, the mounting element may also enable electrical connection of the capacitor. In one embodiment, the mounting element may not serve to electrically connect the capacitor. The capacitor and the mounting element may include any functional and structural features of the capacitor and mounting element as described above.

[0035] The present disclosure encompasses several embodiments and aspects of an invention. Each feature described with respect to one of the capacitors, the mounting arrangement, and / or the method is also disclosed herein with respect to the respective other embodiments and aspects, even if the respective feature is not explicitly mentioned in connection with the specific embodiment or aspect.

[0036] Further features, developments and practicalities will become apparent from the following description in conjunction with the figures. Fig. 1 to 3 show non-inventive examples. Fig. 1 shows a schematic cross-sectional view of a capacitor according to a first example. Fig. 2 shows a view of a second side of the capacitor according to the first example. Fig. 3 shows a view of a first side of the capacitor according to the first example. Fig. 4 shows a schematic cross-sectional view of a capacitor according to an embodiment.

[0037] Similar elements, elements of the same type and elements with identical effects may be provided with the same reference numerals in the figures.

[0038] Fig. 1 shows an electrolytic capacitor 1. The capacitor 1 comprises a housing 2 and a capacitor element 3 mounted in the housing 2. The capacitor element 3 has a coiled shape. The capacitor element 3 has a cylindrical shape with a hole 4 running along its central axis. The capacitor element 3 may comprise foil, in particular aluminum foil. The capacitor element 3 is impregnated with a liquid electrolyte. The housing 2 may have the shape of a circular cylinder. The housing 2 may comprise a metal. As an example, the housing 2 may comprise aluminum. The housing 2 may have the shape of a cup.

[0039] The capacitor 1 comprises a first side 6, a lateral side 7, and a second side 8. The second side 8 is opposite the first side 6. The second side 8 can be formed by a base 5 of the housing 2. The base 5 can comprise a metal. The base 5 can be formed integrally with the lateral side 7.

[0040] On the first side 6, the capacitor 1 includes terminals 9, 10 for electrical connection of the capacitor. The terminals 9, 10 can be configured as screw terminals.

[0041] The capacitor 1 can be configured for mounting with the terminals facing downward, i.e., with the terminals 9, 10 pointing toward the center of the earth. Alternatively, the capacitor 1 can be mounted horizontally, i.e., with the terminals 9, 10 pointing in a horizontal direction. Alternatively, the capacitor 1 can be mounted with the terminal facing upward.

[0042] The capacitor 1 can be mounted on a mounting element (not shown). The mounting element can serve to fix the capacitor 1. Furthermore, the mounting element can serve to electrically connect the terminals 9, 10. In this case, the mounting element can comprise, for example, a printed circuit board or a busbar.

[0043] On the first side 6, the housing 2 is closed by a cover element 11. The cover element 11 can be in the shape of a disc. The cover element 11 can seal the housing 2. The cover element 11 can comprise a rubber material or another elastic material. The connections 9, 10 are guided through the cover element 11.

[0044] The condenser 1 includes a safety vent 12. The safety vent 12 allows for controlled pressure relief. During operation of the condenser 1, gas generation and pressurization may occur within the condenser 1, which may be caused by electrochemical reactions. The safety vent 12 may allow the gas to be released if the internal pressure reaches a critical value. This may prevent an uncontrolled explosion of the condenser 1. For example, the safety vent 12 may be designed to burst in the event of a critical pressure.

[0045] Additionally or alternatively, the safety vent 12 can allow gradual diffusion of the gas to the environment during operation of the electrolytic capacitor 1. This allows the internal pressure to be gradually reduced. The safety vent 12 can comprise a membrane 13. The membrane 13 can comprise a rubber or silicone material.

[0046] In particular, the safety vent 12 may comprise a thin rubber membrane. The membrane 13 may be permeable or semi-permeable to gas.

[0047] The safety vent 12 can be configured to allow pressure relief through the second side 8 of the condenser 1. In particular, pressure relief is allowed through a hole 14 in the bottom 5 of the housing 2. The safety vent 12 is positioned at a shorter distance from the second side 8 than from the first side 6 of the condenser 1.

[0048] Such an arrangement of the safety vent 12 can be particularly advantageous when the condenser 1 is mounted with the side that allows pressure relief facing upward. If pressure relief is enabled through the second side 8, this orientation corresponds to a mounting orientation with the connection facing downward. This design can be advantageous both in the event of a bursting of the safety vent 12 and for gradual pressure relief with the safety vent 12 intact.

[0049] If the safety vent 12 is intact, this design can prevent the safety vent 12 from becoming covered with electrolyte. If the safety vent 12 is positioned at a bottom of the capacitor 1, electrolyte may cover the safety vent 12 due to gravity, thus blocking diffusion. This can lead to cumulative pressurization until the safety vent 12 ruptures. This phenomenon can reduce the effectiveness of the safety vent 12. If the safety vent 12 is positioned at a top of the capacitor 1, it can be kept free of electrolyte, thus maintaining gradual diffusion.

[0050] The capacitor 1 comprises a centering element 15, which protrudes into the hole 4 of the capacitor element 3 on the second side 8. The centering element 15 serves to center the capacitor element 3 in the housing 2. The centering element 15 can be designed as a pin. The centering element 15 can be hollow. The centering element 15 can be formed integrally with the bottom 5 of the housing 2.

[0051] The safety vent 12 is positioned in the centering element 15. This allows the two functions of winding fixation and pressure relief to be combined. The centering element 15 separates the safety vent 12 from the condenser element 3.

[0052] The safety vent 12 is positioned in the hole 4 of the capacitor element 3. The safety vent 12 can be surrounded by the windings of the capacitor element 3. Accordingly, the safety vent 12 is positioned in the core of the capacitor 1.

[0053] The safety vent 12 is positioned at a distance from the bottom 5 of the housing 2. In particular, the safety vent 12 is positioned in a recessed position relative to the bottom 5. This allows the safety vent 12 and, in particular, the membrane 13 to be protected against mechanical damage.

[0054] For example, a cavity 16 may exist between the safety vent 12 and the base 5. This cavity may help prevent electrolyte from leaking to the outside of the capacitor 1. For example, the cavity 16 may accommodate a small amount of electrolyte leaking from the capacitor 1 after the safety vent 12 bursts. This may prevent the base 5 from becoming contaminated by the electrolyte.

[0055] With the disclosed safety vent 12, the capacitor 1 can be filled with an excess amount of electrolyte, which helps provide stable electrical parameters. This can prevent parameter drift during a long operating life. For example, drying out of the windings can be prevented. In a standard capacitor, the electrolyte reservoir can be restricted to prevent free-flowing liquid electrolyte within the capacitor and thereby prevent electrolyte leakage. With the improved safety vent 12, electrolyte leakage can be prevented even with a large amount of electrolyte.

[0056] In a further embodiment, the capacitor 1 may alternatively or additionally comprise a centering element positioned near the first side 6. For example, the capacitor 1 may protrude from the cover element 11 into the hole 4 of the capacitor element 3. Additionally or alternatively, a safety vent may be positioned near the first side 6 in the centering element.

[0057] If the condenser 1 comprises two safety vents, one of the safety vents being positioned near the first side 6 and the other on the second side 8, gradual diffusion can always be ensured, at least through one of the safety vents. In particular, gradual diffusion can be ensured in any orientation of the condenser. As an example, the condenser 1 can have a safety vent 12 on the second side 8, as shown in Fig. 1, and a further safety vent positioned in the cover element 11. The further safety vent may also comprise a rubber or silicone material, in particular a membrane.

[0058] Fig. 2 shows a view of the second side 8 of the capacitor 1 according to Fig. 1 after a pressure relief test. The pressure relief test was conducted with reversed polarity according to the IEC-60384-1 (2008) standard. During this test, gas generation occurs relatively quickly due to the reversed polarity. This resulted in high pressure being generated in condenser 1.

[0059] As in Fig. As can be seen in Figure 2, the membrane 13 of the safety vent 12 has burst. The capacitor 1 was mounted with the terminal facing downward. The second side 8, in particular the base 5, is not covered with electrolyte.

[0060] Fig. Figure 3 shows a view of the first side 6 of the capacitor 1 according to Fig. 1 after the pressure relief test.

[0061] The first side 6, in particular the cover element 11, is not covered with electrolyte. In the embodiment shown, the cover element 11 does not have a safety vent.

[0062] Fig. 4 shows an embodiment of a capacitor 1 according to the invention, which corresponds to the Fig. 1, Fig. 2 and Fig. 3, but additionally includes a stud bolt 17 for mounting the capacitor 1. The stud bolt 17 is positioned on the second side 8 of the capacitor 1.

[0063] The stud bolt 17 can be threaded for screwing the capacitor 1 to a mounting element (not shown). The terminals 9, 10 can be connected, for example, to a circuit board or a busbar.

[0064] The stud bolt 17 can be formed integrally with the base 5 and / or the centering element 15. Reference symbol 1 capacitor 2 housings 3 Capacitor element 4 holes 5 Floor 6 first page 7 lateral side 8 second page 9 Connection 10 Connection 11 Cover element 12 Safety vent 13 Membran 14 holes 15 Centering element 16 cavity 17 stud bolts

Claims

[1] An electrolytic capacitor comprising a housing (2) and a capacitor element (3) mounted in the housing (2) and comprising a safety vent (12) for enabling pressure relief, the safety vent (12) being positioned at least partially in a hole (4) of the capacitor element (3), the capacitor (1) comprising terminals (9, 10) and a stud bolt (17), the terminals (9, 10) being positioned on a first side (6) of the capacitor (1), the stud bolt (17) being positioned on a second side (8) opposite the first side (6), the safety vent (12) being positioned in the stud bolt (17). [2] An electrolytic capacitor according to claim 1, wherein the safety vent (12) comprises a membrane (13). [3] An electrolytic capacitor according to any one of claims 1 to 2, comprising a cover member (11) for sealing the casing (2), wherein the cover member (11) comprises an elastic material and wherein the cover member (11) does not comprise a safety vent (12). [4] An electrolytic capacitor according to any one of claims 1 to 3, configured so that the electrolyte in the capacitor (1) is not in contact with the safety vent (12). [5] An electrolytic capacitor according to any one of claims 1 to 4, comprising a centering element (15) extending into the hole (4) of the capacitor element (3), the safety vent (12) being positioned in the centering element (15). [6] Electrolytic capacitor according to claim 5, wherein the centering element (15) is positioned near the first side (6) or the second side (8) of the capacitor (1). [7] Electrolytic capacitor according to one of claims 1 to 6, wherein the safety vent (12) is embedded in the capacitor (1). [8] Electrolytic capacitor according to one of claims 1 to 7, wherein a cavity (16) is present between the safety vent (12) and an outer side of the capacitor (1). [9] An electrolytic capacitor comprising a housing (2), a capacitor element (3) mounted in the housing (2) and a safety vent (12) for enabling gradual pressure release, wherein the capacitor (1) comprises terminals (9, 10) positioned on a first side (6) of the capacitor (1), pressure release being enabled by an opposite, second side (8) of the capacitor (1), and wherein the capacitor (1) comprises a stud bolt (17) positioned on a second side (8) opposite the first side (6) and provided with a thread for fixing the capacitor (1) to a mounting element, wherein the safety vent (12) is positioned in the stud bolt (17). [10] A method of operating the electrolytic capacitor according to any one of the preceding claims, wherein the capacitor (1) is operated in an orientation in which the second side (8) does not face downwards. [11] Method according to claim 10, wherein the second side (8) faces upwards. [12] Method according to claim 10, wherein the second side (8) points in a horizontal direction. [13] A mounting arrangement comprising the capacitor according to any one of claims 1 to 9 and a mounting element, wherein the capacitor (1) is mounted on the mounting element.

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