High temperature high voltage aluminum electrolytic capacitor

Abstract

This utility model discloses a high-temperature, high-pressure aluminum electrolytic capacitor, which includes an aluminum shell, a rubber sealing plug, and an internal core. This utility model primarily addresses the problems of internal pressure runaway and electrode connection point failure that easily occur in existing products under high temperature and high pressure. Its core improvements are: firstly, a porous insulating buffer gasket is added between the top of the capacitor core and the rubber sealing plug. This design effectively buffers and channels internal gas pressure, enhancing the stability of the core; secondly, a composite connection structure composed of a conductive silver paste layer is used at the connection points between the anode lead and the anode pin, and between the cathode lead and the cathode pin, significantly reducing contact resistance and improving the mechanical and thermal stability of the connection points. This utility model effectively improves the reliability, service life, and electrical performance of aluminum electrolytic capacitors under high temperature and high pressure environments, making it particularly suitable for demanding applications such as solar inverters and industrial frequency converters.

Description

Technical Field

[0001] This utility model relates to the field of capacitor technology, specifically to a high-temperature, high-pressure aluminum electrolytic capacitor. Background Technology

[0002] Aluminum electrolytic capacitors are widely used in various electronic circuits due to their advantages such as small size, large capacitance, and low cost. However, the performance of traditional aluminum electrolytic capacitors deteriorates significantly under harsh operating conditions (such as above 105℃ and above 450V). The main problems include: the electrolyte is prone to evaporation and drying at high temperatures, leading to capacitance decay, increased equivalent series resistance (ESR), and even failure; increased internal gas pressure can easily cause the pressure relief device (explosion-proof valve) to open accidentally or cause the casing to bulge; and the contact resistance and mechanical connection stability between the core and the electrode leads deteriorate under thermal stress, becoming a high-risk point for failure.

[0003] While existing technologies improve electrolyte performance by using high-flash-point solvents and novel electrolytes, or increase withstand voltage by thickening the anode foil oxide film, they fall short in optimizing the internal core structure. In particular, there is still room for improvement in how to coordinate gas generation, pressure release, and the reliability of critical electrical connections. Therefore, there is an urgent need for a high-temperature, high-voltage aluminum electrolytic capacitor with a more robust and reliable internal structure. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-temperature and high-pressure aluminum electrolytic capacitor with an optimized and improved internal structure. This capacitor has higher reliability, longer service life and more stable electrical performance, and is especially suitable for harsh environments with high temperature and high pressure.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a high-temperature, high-pressure aluminum electrolytic capacitor, comprising an aluminum shell, a rubber sealing plug, and a capacitor core sealed within the shell. The core is formed by winding an anode foil, a cathode foil, and electrolytic paper in between. The anode foil and cathode foil are respectively connected to an anode lead and a cathode lead via an anode lead and a cathode lead, respectively. The innovation lies in the following: a porous insulating buffer pad is provided between the top of the capacitor core and the bottom surface of the rubber sealing plug. The insulating buffer pad has a through hole in the middle for the anode lead and the cathode lead to pass through. The connection between the anode lead and the anode lead, and the connection between the cathode lead and the cathode lead, both constitute a multi-layer composite connection structure. The multi-layer composite connection structure includes lead strips, a conductive silver paste layer, and a lead arranged sequentially from the inside out. The conductive silver paste layer completely covers and penetrates the mechanical connection area between the lead strip and the lead.

[0006] Furthermore, the insulating buffer pad is a flexible porous sheet made of polyester nonwoven fabric or aramid paper.

[0007] Furthermore, the mechanical connection method in the multi-layer composite connection structure is riveting or welding.

[0008] Furthermore, the electrolytic paper is a composite fiber paper doped with silica nanoparticles.

[0009] Furthermore, the bottom inner wall of the aluminum casing is provided with a bottom recess for positioning the capacitor core package, and the bottom of the capacitor core package is embedded in the bottom recess.

[0010] The beneficial effects of this utility model after adopting the above structure are as follows: 1. By setting a porous insulating buffer pad, this utility model effectively manages and buffers the internal gas pressure, reduces the risk of malfunction of the explosion-proof valve and the possibility of shell bulging, and improves the safety and reliability of the product under high pressure; the core package is also more securely fixed.

[0011] This invention utilizes conductive silver paste in a multi-layer composite electrode connection structure, which significantly reduces the contact resistance and connection impedance between the lead terminals and the core, resulting in a lower and more stable overall ESR of the capacitor. The stress buffering effect of the silver paste greatly improves the durability of the connection point under high-temperature thermal cycling, fundamentally solving the common failure problem in this area. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model.

[0013] Explanation of reference numerals in the attached figures: 1-Aluminum casing, 2-Rubber sealing plug, 3-Capacitor core, 4-Anode lead bar, 5-Cathode lead bar, 6-Anode guide pin, 7-Cathode guide pin, 8-Insulating buffer pad, 9-Conductive silver paste layer, 10-Bottom recess. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings.

[0015] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present utility model and are not intended to limit the present utility model.

[0016] like Figure 1As shown, the present invention provides a high-temperature, high-pressure aluminum electrolytic capacitor, which adopts a cylindrical aluminum shell 1 and is sealed at the top with a rubber sealing plug 2. Inside the shell 1 is a sealed capacitor core 3, which is formed by winding an anode foil, a cathode foil, and electrolytic paper.

[0017] One of the key improvements is the insertion of a porous insulating buffer gasket 8 made of polyester nonwoven fabric between the top of the core package 3 and the rubber sealing plug 2. The anode guide pin 6 and cathode guide pin 7 pass through a through-hole in the center of this gasket. This gasket is breathable, insulating, and constrains the position of the core package. It allows the gas generated inside to flow smoothly through its micropores to the explosion-proof valve of the sealing plug, while also providing mechanical cushioning and positioning for the core package, preventing it from shaking within the housing and reducing the pressure of the gas instantaneously impacting the explosion-proof valve.

[0018] The second core improvement: The anode lead-out strip 4 and the anode guide pin 6 are connected by riveting or welding, and the cathode lead-out strip 5 and the cathode guide pin 7 are similarly riveted or welded. A high-performance conductive silver paste layer 9 is coated in their connection area, forming a multi-layered composite connection structure (this structure, from the inside out, consists of: a metal foil (lead-out strip), a conductive silver paste layer, and a metal guide pin). The conductive silver paste layer 9 completely encapsulates and penetrates the metal connection interface, forming a strong and highly conductive connection after curing. This structure utilizes the excellent conductivity and flexibility of the conductive silver paste to effectively fill connection gaps, reduce contact resistance, and absorb thermomechanical stress generated by temperature cycling, preventing the connection point from cracking due to fatigue.

[0019] The preferred anode foil is a high-pressure anode foil with a corrosion coefficient higher than 100, and its surface has a dense oxide medium layer.

[0020] In addition, a bottom recess 10 is formed by stamping the bottom inner wall of the outer shell 1, and the bottom of the core package 3 is embedded in it to achieve axial positioning.

[0021] In the production process, after the core package is impregnated with high-temperature electrolyte, it is placed into the outer shell, buffer pads are placed in sequence, and then the guide pin is pressed in and sealed by a rubber stopper. Finally, aging and testing are carried out.

[0022] The above description is only used to illustrate the technical solution of this utility model and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. A high-temperature, high-pressure aluminum electrolytic capacitor, comprising an aluminum casing, a rubber sealing plug, and a capacitor core sealed within the casing, wherein the core is formed by winding an anode foil, a cathode foil, and electrolytic paper interposed therebetween, and the anode foil and cathode foil are respectively connected to an anode lead and a cathode lead via an anode lead strip and a cathode lead strip, characterized in that: A porous insulating buffer pad is provided between the top of the capacitor core and the bottom surface of the rubber sealing plug. The insulating buffer pad has a through hole in the middle for the anode and cathode leads to pass through. The connection between the anode lead and the anode lead, as well as the connection between the cathode lead and the cathode lead, constitute a multi-layer composite connection structure. The multi-layer composite connection structure includes lead bars, conductive silver paste layer and lead pins stacked sequentially from the inside to the outside. The conductive silver paste layer completely covers and penetrates the mechanical connection area between the lead bar and the lead pin.

2. The high-temperature high-voltage aluminum electrolytic capacitor according to claim 1, characterized in that: The insulating buffer pad is a flexible porous sheet made of polyester nonwoven fabric or aramid paper.

3. The high-temperature high-voltage aluminum electrolytic capacitor according to claim 1, characterized in that: The mechanical connection method in the multi-layer composite connection structure is riveting or welding.

4. The high-temperature high-voltage aluminum electrolytic capacitor of claim 1, wherein: The electrolytic paper is a composite fiber paper doped with silica nanoparticles.

5. The high-temperature high-voltage aluminum electrolytic capacitor of claim 1, wherein: The bottom inner wall of the aluminum casing is provided with a bottom recess for positioning the capacitor core package, and the bottom of the capacitor core package is embedded in the bottom recess.

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