Thin film capacitor external structure for new energy electric vehicle

Abstract

The invention discloses a thin film capacitor external structure for a new energy electric vehicle. Comprising a capacitor core. The shell is arranged to be of a rectangular box body structure, heat dissipation fins are arranged on the top of the shell and comprise the first heat dissipation fins and the second heat dissipation fins, a first heat dissipation space is formed between the shell and the first heat dissipation fins, and a second heat dissipation space is formed between the shell and the second heat dissipation fins. A second heat dissipation space is formed between the first heat dissipation fins and the second heat dissipation fins; the installation support is fixed to the outer side of the shell and used for being connected to a vehicle chassis through a damping structure. The problem of how to improve the heat dissipation efficiency and the vibration resistance can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy vehicles, in particular to an external structure of a film capacitor for a new energy electric vehicle. BACKGROUND

[0002] The working environment of a new energy vehicle is more severe and complex than that of traditional industries or consumer electronics, which poses a high challenge to the environmental adaptability of components. Specifically, the space near the engine compartment or battery pack is small and heat is concentrated, the local environment temperature can be higher than 85°C for a long time under extreme conditions in summer, and the capacitor itself will also generate significant heat under high-frequency and large-current working conditions; the vehicle travels on different road conditions, especially on bumpy sections, which will produce continuous and complex spectrum mechanical vibration and instantaneous impact; the vehicle may face the risk of rain, snow, water splashing, high humidity, and road dust invasion; the vehicle layout is highly integrated, requiring components to achieve high power density and high reliability in limited space.

[0003] In view of the above challenges, the external packaging structure of the traditional film capacitor has obvious limitations. Common structures are simple plastic encapsulation shells or metal can sealing, supplemented by basic epoxy resin or silicone seal. Such traditional structures have the following main problems: the plastic shell has poor thermal conductivity, the metal can can conduct heat but has limited surface area, and the internal filling material has low thermal conductivity, making it difficult to quickly conduct heat, resulting in high capacitor core temperature, accelerating medium aging, significantly shortening the service life, and even causing thermal breakdown failure; the structure is rigid and lacks flexibility, and has poor buffering and absorption capacity for high-frequency vibration and impact, which can easily cause internal electrode lead fatigue fracture, core displacement or package cracking; simple sealing methods cannot maintain stable high-level protection under long-term vibration and temperature cycling, and there is a risk of moisture or dust invasion leading to insulation decline, short circuit or corrosion; the installation method is often single and space-occupying, and lacks standardized and shock-absorbing integrated installation solutions compatible with the vehicle chassis or module frame, and is not convenient for integrated temperature monitoring and other intelligent interfaces.

[0004] To solve the heat dissipation problem, some improvement schemes exist in the prior art, such as adding an independent heat sink or heat sink to the outside of the capacitor, or using high-thermal-conductivity silicone grease for interface filling. However, these schemes often make the overall structure complex, increase the volume and cost, and the additional mechanical connection points may introduce new thermal resistance and vibration hazards. For protection and installation, more expensive fully sealed welded metal shells or complex multi-layer protection designs are also used, but they also face the contradiction between cost control, weight increase and compatibility with the compact space of the electric vehicle.

[0005] It should be noted that the above information is only used to understand the background art of the present inventive concept. SUMMARY

[0006] Aiming at the deficiencies of the prior art, the application discloses a film capacitor external structure for a new energy electric vehicle, which can solve the problems of how to improve the heat dissipation efficiency and vibration resistance.

[0007] To achieve the above object, the application is implemented by the following technical solutions: The film capacitor external structure for the new energy electric vehicle comprises: A capacitor core; An outer shell, which is arranged in a rectangular box structure, is provided with heat dissipation fins on the top, wherein the heat dissipation fins comprise first heat dissipation fins and second heat dissipation fins, a first heat dissipation space is formed between the outer shell and the first heat dissipation fins, and a second heat dissipation space is formed between the first heat dissipation fins and the second heat dissipation fins; and A mounting bracket, which is fixed to the outer side of the outer shell, is used to be connected to a vehicle chassis through a damping structure.

[0008] In the preferred technical solution, an initial ventilation hole is arranged on the surface of the outer shell, a first ventilation hole is arranged on the first heat dissipation fins, and the initial ventilation hole and the first ventilation hole are arranged in a staggered manner.

[0009] In the preferred technical solution, an initial dustproof net is arranged on the initial ventilation hole, the thickness of the initial dustproof net is arranged to be 1-3 mm, a first dustproof net is arranged on the first ventilation hole, and the thickness of the first dustproof net is arranged to be 1-3 mm.

[0010] In the preferred technical solution, the height difference between the upper surface of the outer shell and the lower surface of the first heat dissipation fins is arranged to be 10-20 mm, and the height of the first heat dissipation space is arranged to be 10-20 mm.

[0011] In the preferred technical solution, a first ventilation hole is arranged on the first heat dissipation fins, and a second ventilation hole is arranged on the second heat dissipation fins, and the first ventilation hole and the second ventilation hole are arranged in a staggered manner.

[0012] In the preferred technical solution, a second dustproof net is arranged on the second ventilation hole, and the thickness of the second dustproof net is arranged to be 1-3 mm.

[0013] In the preferred technical solution, the height difference between the upper surface of the first heat dissipation fins and the lower surface of the second heat dissipation fins is arranged to be 5-10 mm, and the height of the second heat dissipation space is arranged to be 5-10 mm.

[0014] In the preferred technical solution, the damping structure comprises a first damping pad and a second damping pad, the first damping pad is arranged at the bottom of the mounting bracket, and the second damping pad is arranged at the bottom of the first damping pad.

[0015] Preferably, the first damping pad is arranged to extend horizontally outward of the mounting bracket, and the second damping pad is arranged to extend horizontally outward of the first damping pad.

[0016] Preferably, a temperature sensor interface is integrated on the mounting bracket for connecting a temperature sensor to monitor the temperature of the capacitor in real time.

[0017] The application discloses a film capacitor external structure for a new energy electric vehicle, which has the following advantages. The unique double-layer staggered heat dissipation fin design greatly optimizes the heat dissipation air duct and heat dissipation area, and has high heat dissipation efficiency and good dustproof effect. The double-layer horizontally extending damping pad design provides excellent anti-vibration and buffering performance. The overall structure is compact, has high protection level, and is easy to integrate into a narrow and vibrating installation space of a new energy vehicle, thereby significantly improving the reliability and service life of the capacitor in a harsh vehicle environment. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below.

[0019] Figure 1 is a schematic view of the embodiment of the present application in the top view direction; Figure 2 is a schematic view of the embodiment of the present application in the front view direction; Figure 3 is an enlarged schematic view of the embodiment of the present application in the top view direction; Figure 4 is an enlarged schematic view of the embodiment of the present application in the front view direction. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below.

[0021] The film capacitor external structure for a new energy electric vehicle protected by the present application mainly comprises a capacitor core 1, a shell 2 and a mounting bracket 3.

[0022] The shell 2 is made of aluminum alloy with good thermal conductivity by pressure casting or machining molding, and has a whole rectangular box structure, for example, with a size of 150mmx80mmx50mm. The inner cavity of the shell 2 is used to accommodate the film capacitor core 1, and the gap between the two is filled with high-thermal-conductivity silica gel with a thermal conductivity coefficient ≥2.5W / m·K, so as to ensure that the heat generated by the capacitor core 1 can be effectively conducted to the shell 2.

[0023] The improvement of the core lies in the heat dissipation structure on the top of the shell 2. Above the top wall of the shell 2, a first heat dissipation fin 21 and a second heat dissipation fin 22 are integrally formed or fixedly connected. The first heat dissipation fin 21 is located close to the top wall of the shell 2, and the second heat dissipation fin 22 is located above the first heat dissipation fin 21. Thus, between the outer surface of the top wall of the shell 2 and the lower surface of the first heat dissipation fin 21, a first heat dissipation space S1 is formed; between the upper surface of the first heat dissipation fin 21 and the lower surface of the second heat dissipation fin 22, a second heat dissipation space S2 is formed. In a preferred embodiment, the height difference H1 between the upper surface of the shell 2 and the lower surface of the first heat dissipation fin 21 is set to 15 mm, i.e. the height of the first heat dissipation space S1 is about 15 mm. The height difference H2 between the upper surface of the first heat dissipation fin 21 and the lower surface of the second heat dissipation fin 22 is set to 8 mm, i.e. the height of the second heat dissipation space S2 is about 8 mm. This double-layer and spaced heat dissipation fin design significantly increases the heat dissipation surface area and utilizes the two heat dissipation spaces to guide air convection, thereby improving the heat dissipation efficiency in a limited space.

[0024] In order to further enhance heat dissipation and prevent dust from entering, initial ventilation holes 23 are provided on the side walls of the shell 2, first ventilation holes 211 are provided on the side walls of the first heat dissipation fin 21, and second ventilation holes 221 are provided on the side walls of the second heat dissipation fin 22. The key point is that these ventilation holes are arranged in a staggered manner. Specifically, from the outside, the initial ventilation holes 23 and the first ventilation holes 211 do not overlap in horizontal projection, and external air needs to pass through a tortuous path to enter the first heat dissipation space S1. Similarly, the first ventilation holes 211 and the second ventilation holes 221 are also arranged in a staggered manner, so that the path for air to enter the second heat dissipation space S2 from the first heat dissipation space S1 is also not straight. This labyrinthine air duct design is beneficial to reduce the amount of dust carried by high-speed airflow and prolong the contact time of air with the heat dissipation surface.

[0025] On the inner side or outer side of each ventilation hole, a dust screen is covered. Specifically, an initial dust screen 231 is provided at the initial ventilation holes 23, a first dust screen 212 is provided at the first ventilation holes 211, and a second dust screen 222 is provided at the second ventilation holes 221. These dust screens can be woven from stainless steel or high-temperature resistant nylon materials, and the mesh size is preferably 0.1-0.2 mm. Their thickness is set in the range of 1-3 mm, which ensures ventilation and dust interception while having sufficient structural strength.

[0026] The mounting bracket 3 is an L-shaped structure made of aluminum alloy profile and is fixed to both sides of the shell 2 by bolts or welding. The mounting bracket 3 is used to mount the entire capacitor structure to the vehicle chassis or power module frame.

[0027] In order to effectively isolate the vibration and impact from the vehicle driving, a double-layer damping structure is arranged between the mounting bracket 3 and the vehicle mounting surface. The damping structure includes a first damping pad 31 and a second damping pad 32. The first damping pad 31 is fixed to the bottom mounting surface of the mounting bracket 3 by adhesion or buckling. The second damping pad 32 is fixed to the bottom of the first damping pad 31. The first damping pad 31 and the second damping pad 32 can be made of elastomeric materials with different hardness or damping characteristics, for example, the first damping pad 31 is made of high-hardness polyurethane for absorbing high-frequency micro-vibration, and the second damping pad 32 is made of low-hardness silicone rubber for absorbing low-frequency large impact.

[0028] An important feature is that the first damping pad 31 extends horizontally to the outside of the mounting bracket 3, forming a protruding edge. Similarly, the second damping pad 32 further extends horizontally to the outside of the first damping pad 31. This stepped horizontal extension design increases the contact area and buffer moment of the damping pad with the vehicle mounting surface, improves the ability to resist torsional and shear vibration, and makes the installation more stable and reliable.

[0029] On one of the mounting brackets 3, a temperature sensor interface 33 is integrated. The interface can be a standardized socket or terminal for connecting a negative temperature coefficient thermistor. The probe of the thermistor can be inserted into the interior of the shell or closely attached to the inner wall of the shell for real-time monitoring of the working temperature of the capacitor core. The temperature signal can be connected to the battery management system or the vehicle controller of the electric vehicle, and when the temperature exceeds the preset safety threshold, the system can issue an alarm or take protective measures such as power reduction.

[0030] During the operation of the electric vehicle, the heat generated by the operation of the capacitor core 1 is conducted to the aluminum alloy shell 2 through the heat-conducting silicone. The heat of the shell 2 is dissipated through the wall surface itself, and more importantly, is transferred to the first and second heat dissipation fins 21 and 22 on the top. The natural wind or forced air flow brought by the vehicle driving enters the first and second heat dissipation spaces S1 and S2 in sequence from the staggered initial vent hole 23, first vent hole 211, and second vent hole 221. Due to the circuitous path formed by the staggered vent holes, the airflow generates turbulence in the heat dissipation space, and after sufficient heat exchange with the fin surface, it is discharged from the other side of the vent hole, efficiently taking away the heat. At the same time, the dust screen effectively blocks most of the dust from entering the heat dissipation channel. The vibration of the vehicle is effectively absorbed and isolated by the double-layer, horizontally-extending damping structure at the bottom of the mounting bracket 3, protecting the internal capacitor core and electrical connections.

[0031] The application also describes a method for preparing the external structure of a thin-film capacitor for a new energy electric vehicle. Specifically: Firstly, material preparation is carried out. The 6063 aluminum alloy plate with a thickness of 2 mm is selected as the main body of the shell. At the same time, the matching aluminum alloy profile for forming the heat dissipation fin is prepared. The sealing material is selected as silicone rubber, and the damping material is prepared as polyurethane block with Shore A hardness of 70 and silicone rubber block with Shore A hardness of 40. The protective material is selected as a stainless steel woven dust screen with a thickness of 2 mm and a mesh size of 0.15 mm. The internal filling material is selected as high thermal conductivity silicone gel with a thermal conductivity not less than 2.8 W per meter Kelvin. The sensor component is prepared as a standard NTC thermistor and a connector interface matched therewith.

[0032] Subsequently, the processing and surface treatment stage of the shell main body is entered. The aluminum alloy plate is punched and bent by using a numerical control machine tool to form a rectangular box blank with a length of 150 mm, a width of 80 mm, and a height of 50 mm. The blank is subjected to anodic oxidation treatment to form a dense oxide layer with a thickness of about 25 μm to improve corrosion resistance. At the predetermined position of the top wall of the shell, the mounting base of the first heat dissipation fin is fixed by welding process. The design of the base makes the lower surface and the outer surface of the top wall of the shell form a clear gap with a height of 15 mm, which is the first heat dissipation space. Then, a series of first heat dissipation fins with a height of 15 mm, a thickness of 2 mm, and a neighboring interval of 6 mm are precisely milled on the base. On the four side walls of the shell, a plurality of circular holes with a diameter of 3 mm are uniformly opened by laser drilling process, which are defined as initial ventilation holes.

[0033] Next is the production of mounting bracket and damping structure. The L-shaped mounting bracket is processed by using aluminum alloy profile, and the surface is subjected to plastic spraying treatment. The first damping pad made of polyurethane material is adhered to the bottom mounting plane of the mounting bracket by using high-performance epoxy resin structural adhesive. During the adhesion process, the first damping pad is intentionally made to extend 5 mm beyond the outer edge of the mounting bracket in the horizontal direction to form the first level of horizontal extension buffer structure. The second damping pad made of silicone rubber material is also adhered to the bottom surface of the first damping pad by using epoxy resin adhesive. During the adhesion, the second damping pad is made to extend 5 mm beyond the outer edge of the first damping pad in the horizontal direction to form the second level of horizontal extension buffer structure. After the adhesion is completed, it needs to be cured for 24 hours in a normal temperature environment to ensure the connection strength.

[0034] The fine assembly and dustproof structure construction of the heat dissipation system are key steps. The prefabricated second heat dissipation fin assembly is fixed above the first heat dissipation fin assembly through insulating support columns, and a uniform gap of 8 mm is maintained between the upper and lower surfaces of the two, which constitutes the second heat dissipation space. First ventilation holes are opened in the corresponding positions of the side walls of the first heat dissipation fin assembly, and second ventilation holes are opened in the corresponding positions of the side walls of the second heat dissipation fin assembly. It must be ensured that the center lines of the initial ventilation hole, the first ventilation hole and the second ventilation hole do not coincide on the vertical projection plane, that is, they are arranged staggered. In specific implementation, the center line of the first ventilation hole can be horizontally offset by 4 mm relative to the center line of the initial ventilation hole directly below, and the center line of the second ventilation hole can also be horizontally offset by 4 mm relative to the center line of the first ventilation hole directly below, to form a non-straight zigzag airflow channel. Then, on the inner side of all ventilation holes, high-temperature-resistant and elastic adhesive is used to respectively paste and fix the initial dustproof net, the first dustproof net and the second dustproof net, and the thickness of each dustproof net is controlled to be 2 mm.

[0035] After the completion of the external structure, the packaging and internal assembly of the capacitor core are carried out. The standard thin film capacitor core with a nominal capacity of 100 μF and a rated voltage of 800 VDC is carefully placed in the center of the inner cavity of the shell. After the high-thermal-conductivity silicon gel is stirred and defoamed in a vacuum environment, it is slowly injected into the inner cavity of the shell until the capacitor core is completely immersed. Then the entire assembly is placed in a vacuum chamber for 30 minutes to ensure that all internal bubbles are effectively removed. Finally, a waterproof sealing ring made of silicone rubber is accurately pressed into the pre-set sealing groove at the bottom of the shell.

[0036] Then the external assembly and electrical function integration are carried out. The mounting bracket with double-layer shock-absorbing structure is symmetrically fastened to the two side walls of the shell using stainless steel bolts. High-voltage input and output terminals are installed on the front panel of the shell, and the terminal material is silver-plated copper alloy. The installation and fastening torque is controlled at 6 Nm. A temperature sensor interface socket is installed at the specified position of one of the mounting brackets, and the lead wire of the NTC thermistor is reliably connected to the socket. At the same time, the temperature sensing head of the thermistor is firmly attached to the sensitive area of the inner wall of the shell using heat-conducting glue.

[0037] Finally, the product verification and test phase is entered. The fully assembled capacitor module is subjected to air tightness detection, and no pressure decay is found after being kept under 0.5 Bar pressure for 30 minutes. The protection level test is performed by immersing the capacitor module in 1-meter-deep water for 30 minutes, and no water ingress is found inside. The mechanical reliability test is performed on an electric vibration test bench to simulate the vehicle-mounted environment, and the frequency range is 10-500 Hz, the acceleration is 5g, and the structure is checked after 2 hours of test, and no loosening is found, and the electrical performance parameters do not drift. The heat dissipation performance is evaluated on a special load test bench, and the rated ripple current is applied under the rated voltage, and the maximum working temperature of the capacitor core is stabilized at 68 degrees Celsius in an environment temperature of 40 degrees Celsius, and the heat dissipation performance is remarkable. The temperature monitoring system function is verified synchronously, and when the simulated temperature rises to 85 degrees Celsius, the set threshold value, the external overheat protection circuit accurately responds and performs the protection action immediately.

[0038] The product obtained by the preparation method of the embodiment fully realizes the technical features described in the application, has excellent heat dissipation performance, high-level protection capability, excellent anti-vibration characteristics and intelligent monitoring interface, fully meets the demand of new energy electric vehicles for high-reliability thin film capacitors, and the preparation process is stable and suitable for large-scale production.

[0039] The above is an embodiment for illustrating the technical scheme of the application.

Claims

1. The external structure of a film capacitor used in new energy electric vehicles, comprising: Capacitor core; The outer casing is configured as a rectangular box structure, and the top of the outer casing is provided with heat dissipation fins, the heat dissipation fins including a first heat dissipation fin and a second heat dissipation fin, wherein a first heat dissipation space is formed between the outer casing and the first heat dissipation fin, and a second heat dissipation space is formed between the first heat dissipation fin and the second heat dissipation fin; and Mounting bracket, which is fixed to the outside of the housing, is used to connect to the vehicle chassis via a shock-absorbing structure.

2. The external structure of the thin-film capacitor for new energy electric vehicles according to claim 1, wherein, An initial ventilation hole is provided on the surface of the outer shell, and a first ventilation hole is provided on the first heat dissipation fin. The initial ventilation hole and the first ventilation hole are staggered.

3. The external structure of the thin-film capacitor for new energy electric vehicles according to claim 2, wherein, An initial dustproof net is provided in the initial ventilation hole, and the thickness of the initial dustproof net is set to 1-3mm. A first dustproof net is provided in the first ventilation hole, and the thickness of the first dustproof net is set to 1-3mm.

4. The external structure of the film capacitor for new energy electric vehicles according to claim 1, wherein, The height difference between the upper surface of the outer shell and the lower surface of the first heat dissipation fin is set to 10-20mm, and the height of the first heat dissipation space is set to 10-20mm.

5. The external structure of the thin-film capacitor for new energy electric vehicles according to claim 5, wherein, The first heat dissipation fin has a first ventilation hole, and the second heat dissipation fin has a second ventilation hole, which are staggered.

6. The external structure of the thin-film capacitor for new energy electric vehicles according to claim 1, wherein, A second dustproof net is provided in the second ventilation hole, and the thickness of the second dustproof net is set to 1-3mm.

7. The external structure of the film capacitor for new energy electric vehicles according to claim 1, wherein, The height difference between the upper surface of the first heat dissipation fin and the lower surface of the second heat dissipation fin is set to 5-10 mm, and the height of the second heat dissipation space is set to 5-10 mm.

8. The external structure of the thin-film capacitor for new energy electric vehicles according to claim 1, wherein, The shock absorption structure includes a first shock absorption pad and a second shock absorption pad. The first shock absorption pad is disposed at the bottom of the mounting bracket, and the second shock absorption pad is disposed at the bottom of the first shock absorption pad.

9. The external structure of the thin-film capacitor for new energy electric vehicles according to claim 8, wherein, The first damping pad is configured to extend horizontally outward from the mounting bracket, and the second damping pad is configured to extend horizontally outward from the first damping pad.

10. The external structure of the thin-film capacitor for new energy electric vehicles according to claim 1, wherein, A temperature sensor interface is integrated on the mounting bracket for connecting a temperature sensor to monitor the capacitor temperature in real time.

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