A crack-proof automotive film capacitor

Abstract

The present invention discloses an anti-cracking automotive film capacitor, comprising: a shell, a capacitor element, an encapsulating epoxy resin, and an electrode lead-out terminal. An uneven frosted layer is provided on the inner wall of the shell, and an integrally formed trapezoidal reinforcing rib is provided, which can effectively improve the bonding ability between the shell and the encapsulating epoxy resin; the thermal expansion coefficient of the encapsulating epoxy resin is adjusted, and the electrode lead-out terminal is rounded, so that the encapsulating epoxy resin can still maintain a similar expansion degree as the shell and bonding with the electrode lead-out terminal in a rapidly changing temperature environment, and is not easy to crack, which significantly improves the sealing, reliability and service life of the product.

Description

Technical Field

[0001] The present invention relates to the field of capacitors, and in particular to an anti-cracking automotive-grade film capacitor. Background Art

[0002] Film capacitors are widely used in electronics, home appliances, communications, hybrid vehicles, wind power generation, solar power generation and other fields. With their good electrical properties and high reliability, film capacitors have become an indispensable electronic component to promote the upgrading of the above industries. Due to the different working environments in different fields, there are also different requirements for the physical properties of film capacitors. Therefore, different processes are needed for the corresponding fields to ensure that the operational needs are met.

[0003] In the field of new energy vehicles, issues such as road traffic and driving safety are involved, and the specifications and performance requirements of the film capacitors used are more stringent. Therefore, reliability is also an important indicator that needs to be considered as an automotive capacitor. Among them, the humidity environment has a more obvious impact on the reliability and service life of automotive capacitors. In the design of automotive capacitors, sealing performance should be taken as an important consideration to prevent or reduce the impact of the humidity environment on the reliability and service life of the capacitor itself. During the use of existing automotive capacitor products, there are various forces such as external force extrusion and stress caused by rapid temperature changes, which can easily cause cracking of the capacitor casing and encapsulation epoxy resin, seriously affecting the sealing performance of the product, resulting in a reduction in product life or even product failure. Therefore, it is necessary to adopt a suitable design for automotive capacitors to ensure good bonding between the capacitor casing and the encapsulation epoxy resin, thereby ensuring the sealing of automotive capacitor products. Summary of the invention

[0004] The purpose of the present invention is to provide a crack-resistant automotive film capacitor. By structural design and processing technology of the capacitor shell to effectively enhance the bonding ability between the shell and the encapsulating epoxy resin, the problem of cracking of automotive film capacitor products during use, especially in an environment with rapid temperature changes, which affects the sealing of the product is solved.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A crack-resistant automotive-grade film capacitor comprises a shell and a capacitor element encapsulated in the shell by an encapsulating epoxy resin. The invention is characterized in that: the inner wall of the shell is an uneven frosted layer and is provided with at least one reinforcing rib, the capacitor element is completely encapsulated in the encapsulating epoxy resin, and the reinforcing rib is partially exposed outside the encapsulating epoxy resin.

[0007] Furthermore, the shell is a rectangular parallelepiped, the reinforcing rib is integrally formed with the shell, the length of the reinforcing rib is smaller than the height of the rectangular parallelepiped, and one end of the reinforcing rib is flush with the lower edge of the inner wall of the shell.

[0008] Furthermore, the four inner walls of the shell are all rough frosted layers and are each provided with at least one reinforcing rib.

[0009] Furthermore, two opposite inner walls of the shell having a larger area are respectively provided with five said reinforcing ribs, and two opposite inner walls of the shell having a smaller area are respectively provided with two said reinforcing ribs.

[0010] Furthermore, the five reinforcing ribs on the inner wall of the same shell are arranged in a row and the distances between any two of them are not equal.

[0011] Furthermore, the five reinforcing ribs on the inner wall of the same shell are, from left to right, the first reinforcing rib, the second reinforcing rib, the third reinforcing rib, the fourth reinforcing rib and the fifth reinforcing rib, the distance from the first reinforcing rib to the second reinforcing rib is equal to the distance from the second reinforcing rib to the fourth reinforcing rib, and the distance from the third reinforcing rib to the second reinforcing rib is equal to the distance from the third reinforcing rib to the fourth reinforcing rib.

[0012] Furthermore, the distance between the first reinforcing rib and the second reinforcing rib is greater than the distance between the second reinforcing rib and the third reinforcing rib.

[0013] Furthermore, the cross-section of the reinforcing rib in the horizontal direction is an isosceles trapezoid, and the side surface corresponding to the short side thereof is in close contact with the inner wall of the shell.

[0014] Furthermore, the capacitor element has two electrode lead ends extending out of the encapsulating epoxy resin, and each edge of the electrode lead ends is provided with a chamfer.

[0015] Furthermore, the thermal expansion coefficient of the encapsulating epoxy resin is consistent with the thermal expansion coefficient of the shell.

[0016] Compared with the prior art, the present invention provides an integrally formed reinforcing rib on the inner wall of the shell, which can increase the shell's anti-deformation strength and prevent deformation of the shell caused by external forces such as extrusion and impact. The reinforcing rib is designed to be trapezoidal, and an uneven frosted layer is provided on the inner wall of the shell to further increase the bonding strength between the encapsulating epoxy resin and the inner wall of the shell. In addition, the thermal expansion coefficient of the encapsulating epoxy resin is adjusted so that the expansion degree of the shell and the encapsulating epoxy resin is consistent when the product is in use, and the electrode lead end is rounded to increase the bonding area with the encapsulating epoxy resin, so that the encapsulating epoxy resin is less likely to crack with the shell and the electrode lead end, thereby ensuring the sealing performance and service life of the automotive capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the shell of the automotive-grade film capacitor;

[0018] Figure 2 This is a schematic diagram of the bottom surface of the automotive film capacitor housing;

[0019] Figure 3 This is a schematic diagram of the reinforcement ribs of automotive film capacitors;

[0020] Figure 4 This is a schematic diagram of the frosting treatment and electrode lead-out terminals of automotive-grade film capacitors;

[0021] Figure numerals: 1. Shell; 11. Outer wall; 12. Inner wall; 13. Bottom surface; 14. Reinforcing rib; 141. First reinforcing rib; 142. Second reinforcing rib; 143. Third reinforcing rib; 144. Fourth reinforcing rib; 145. Fifth reinforcing rib; 2. Encapsulating epoxy resin; 3. Electrode lead terminal; 31. Electrode plane; 32. Electrode side surface. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is now further described in conjunction with the accompanying drawings and specific implementations:

[0023] like Figure 1 As shown, the present invention proposes an anti-cracking automotive-grade film capacitor, including a shell 1, an encapsulating epoxy resin 2 filled in the shell 1, and an electrode lead terminal 3.

[0024] like Figure 1 , Figure 2 , Figure 3 As shown, in the automotive-grade film capacitor of the present invention, the shell 1 is in the shape of a rectangular parallelepiped, and a space is formed inside to accommodate the capacitor element, and the capacitor element is completely encapsulated in the encapsulating epoxy resin 2. The inner wall 12 of the shell 1 has a plurality of reinforcing ribs 14 integrally cast with the shell 1, and the reinforcing ribs are all cylindrical and vertically arranged perpendicular to the bottom surface 13 of the shell 1. The length of the reinforcing ribs is less than the height of the rectangular parallelepiped of the shell, and one end thereof is flush with the lower edge of the inner wall 12; specifically, the two opposite inner walls with larger areas in the inner wall 12 are each provided with five of the reinforcing ribs 14, such as Figure 3From left to right in the figure are the first reinforcing rib 141, the second reinforcing rib 142, the third reinforcing rib 143, the fourth reinforcing rib 144, and the fifth reinforcing rib 145, wherein the five reinforcing ribs are arranged in a row, and the distances between any two of them are not the same. Specifically, the distance from the first reinforcing rib 141 to the second reinforcing rib 142 is equal to the distance from the second reinforcing rib 142 to the fourth reinforcing rib 144, the distance from the third reinforcing rib 143 to the second reinforcing rib 142 is equal to the distance from the third reinforcing rib 143 to the fourth reinforcing rib 144, and the distance from the first reinforcing rib 141 to the second reinforcing rib 142 is greater than the distance from the second reinforcing rib 142 to the third reinforcing rib 143; two of the reinforcing ribs are each provided on the two opposite inner walls with smaller areas. By reinforcing the shell 1, the anti-deformation strength of the shell 1 can be effectively increased. Even if the outer wall 11 of the shell 1 is affected by the stress caused by external force extrusion and rapid temperature changes, the shape of the shell 1 can still be maintained unchanged, so that cracks will not be formed at the junction of the inner wall 12 and the encapsulating epoxy resin 2 to destroy the overall sealing of the automotive-grade film capacitor product, thereby significantly enhancing the reliability of the product.

[0025] like Figure 2 , Figure 3 As shown, the reinforcing rib 14 is provided with a column whose cross-sectional shape is designed as an isosceles trapezoid, wherein the short side corresponding to the isosceles trapezoid is the connection end with the inner wall 12, which is close to the inner wall 12 of the shell 1, and the long side corresponding to the surface is a convex portion; the encapsulating epoxy resin 2 is filled in the rectangular space inside the shell 1, specifically, it can be filled in the space between the capacitor element and the inner wall 12, so as to keep the capacitor element stably placed to avoid impacts such as collision with the inner wall and thus reduce stability; and because the short side corresponding to the reinforcing rib 14 The side surface is connected to the inner wall 12, and the corresponding surface of the long side is protruding. The encapsulating epoxy resin 2 is in a wrapped state and connected to the reinforcing rib 14. Specifically, the encapsulating epoxy resin 2 is in contact with the inner wall 12, the bottom surface 13, and the corresponding surfaces of the long sides and two waist surfaces of the reinforcing rib 14. When the encapsulating epoxy resin 2 attempts to crack with the inner wall 12, the two symmetrical waist surfaces of the trapezoidal reinforcing rib 14 will generate a reaction force to increase the difficulty of cracking the inner wall 12 and the encapsulating epoxy resin 2, so that the shell 1 as a whole and the encapsulating epoxy resin 2 do not crack and maintain the original sealing shape. In addition, since different contact areas and contact forms will lead to different degrees of bonding inside the encapsulation epoxy resin 2, the encapsulation epoxy resin 2 does not completely wrap the reinforcing ribs 14, but exposes the upper part of the reinforcing ribs 14 outside the encapsulation epoxy resin 2, so that the encapsulation epoxy resin 2 can maintain a consistent degree of bonding with the inner wall 12 and the reinforcing ribs 14 at all heights, and will not cause cracks on the upper side or even cause cracks on the lower side due to different degrees of bonding at different heights, thereby affecting the actual use of automotive-grade thin film capacitors.

[0026] In addition to the above-mentioned reinforcement ribs 14, Figure 4 As shown, the present invention also performs sandblasting on all surfaces of the inner wall 12 of the shell 1, so that the entire surface of the inner wall 12 of the shell presents a layer of uneven frosted layer. This uneven surface structure greatly increases the contact area between the inner wall 12 of the shell and the encapsulating epoxy resin 2, thereby significantly improving the bonding degree between the shell 1 and the encapsulating epoxy resin 2. Compared with the case where the inner wall of the same shell is not treated, the frosted layer has a very obvious effect on improving the bonding ability between the inner wall 12 and the encapsulating epoxy resin 2 compared to the original smooth surface.

[0027] In addition, due to the expansion or contraction caused by the heat generated during use or the decrease in temperature, and due to the different materials used between different components, the degree of expansion or contraction of different components may also be different, which makes cracking more likely to occur; therefore, in order to maintain the overall stability of the automotive-standard film capacitor, a special adjustable formula is also adopted for the encapsulating epoxy resin 2, and the ratio is adjusted so that the thermal expansion coefficient of the obtained encapsulating epoxy resin 2 is consistent with the thermal expansion coefficient of the shell 1. When the automotive-standard film capacitor encounters a rapid temperature change during use, since the thermal expansion coefficient of the encapsulating epoxy resin 2 is consistent with that of the shell 1, the contraction and expansion degree of the shell 1 and the encapsulating epoxy resin 2 can be basically synchronized. On the premise that the uneven frosted layer on the inner wall 12 improves the bonding degree with the encapsulating epoxy resin 2, the overall structure of the automotive-standard film capacitor can be kept more stable without cracking and deformation.

[0028] like Figure 4As shown, the present invention also performs rounding on the electrode lead-out terminal 3. The traditional electrode lead-out terminal is not rounded and is in the shape of a flat and thin rectangular parallelepiped, wherein the contact area between the four right angles of the electrode sheet and the encapsulation epoxy resin is small, the bonding ability between the two is relatively limited, and the temperature changes rapidly at the sharp corners, which is easy to cause the large temperature difference between the sharp corners and the encapsulation epoxy resin, resulting in the encapsulation epoxy resin as a whole, especially the internal shrinkage being asynchronous, resulting in cracking at the junction of the encapsulation epoxy resin and the electrode sheet; while in the present invention, the electrode lead-out terminal 3 has an electrode plane 31 and an electrode side 32, wherein the electrode plane 31 and the electrode side 32 are arranged in a direction perpendicular to the bottom surface 13 of the shell 1, and the bottom thereof is in contact with the encapsulation epoxy resin 2 Sealed connection, in which the electrode side 32 is rounded to form a shape structure in which the electrode sheet is flat in the middle and arc-shaped at both ends. The junction between the electrode side 32 and the electrode plane 31 is smooth, which not only increases the contact area and bonding ability between the electrode lead terminal 3 and the encapsulating epoxy resin 2, but also has no sharp corners. When the automotive-grade film capacitor product is in use, the overall temperature change of the electrode lead terminal 3 is relatively smooth and stable, avoiding a large temperature difference that may cause cracking of the electrode lead terminal 3 and the encapsulating epoxy resin 2. The larger contact area also makes the bond with the encapsulating epoxy resin 2 more stable at the contact point, reducing the possibility of cracking due to external forces.

[0029] In view of the problem that, when traditional automotive-grade film capacitors are affected by temperature changes, the shell 1 and the encapsulating epoxy resin 2 have insufficient bonding, resulting in easy cracking and poor sealing, the present invention proposes to provide reinforcing ribs 14, design the shape and structure of the reinforcing ribs, sandblast the inner wall 12, adjust the thermal expansion coefficient of the epoxy resin 2, and round the electrode lead end 3, so as to effectively improve the bonding ability between the shell 1 and the encapsulating epoxy resin 2, thereby significantly improving the sealing, reliability and service life of the product.

[0030] The above description is only a description of the preferred embodiment of the present invention, and does not limit the scope of the present invention. Various equivalent substitutions or improvements made by those skilled in the art based on the technical solutions and concepts of the present invention should be included in the protection scope determined by the claims of the present invention.

Claims

1. Anti-cracking automotive film capacitor, The invention comprises a shell, a capacitor element encapsulated in the shell by an encapsulating epoxy resin, wherein the inner wall of the shell is an uneven frosted layer and is provided with at least one reinforcing rib, the capacitor element is completely encapsulated in the encapsulating epoxy resin, and the reinforcing rib is partially exposed outside the encapsulating epoxy resin; The shell is a rectangular parallelepiped, the reinforcing rib is integrally formed with the shell, the length of the reinforcing rib is smaller than the height of the rectangular parallelepiped, and one end of the reinforcing rib is flush with the lower edge of the inner wall of the shell; The four inner walls of the shell are all rough frosted layers and are each provided with at least one reinforcing rib; The two inner walls of the shell having a larger area and facing each other are respectively provided with five reinforcing ribs, and the two inner walls of the shell having a smaller area and facing each other are respectively provided with two reinforcing ribs; The five reinforcing ribs on the inner wall of the same shell are arranged in a row and the distances between any two of them are not equal; The five reinforcing ribs on the inner wall of the same shell are, from left to right, the first reinforcing rib, the second reinforcing rib, the third reinforcing rib, the fourth reinforcing rib and the fifth reinforcing rib, the distance from the first reinforcing rib to the second reinforcing rib is equal to the distance from the second reinforcing rib to the fourth reinforcing rib, and the distance from the third reinforcing rib to the second reinforcing rib is equal to the distance from the third reinforcing rib to the fourth reinforcing rib; The distance between the first reinforcing rib and the second reinforcing rib is greater than the distance between the second reinforcing rib and the third reinforcing rib; the cross-section of the reinforcing rib in the horizontal direction is an isosceles trapezoid, and the side surface corresponding to the short side is close to the inner wall of the shell, and the corresponding surface of the long side is a convex part; the encapsulating epoxy resin is in contact with the inner wall, the bottom surface, and the corresponding surface of the long side of the reinforcing rib and the two waist surfaces; the capacitor element has two electrode lead ends extending out of the encapsulating epoxy resin, and each edge of the electrode lead end is provided with a chamfer.

2. The automotive grade film capacitor according to claim 1, characterized in that: The thermal expansion coefficient of the epoxy resin is consistent with the thermal expansion coefficient of the shell.

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