Brazing process for making battery packge cooling plate

Battery packge liquid cold plate

New energy vehicles are the development direction of future automobiles. The battery pack is one of the core key components of new energy vehicles. The strength, waterproofness, fire resistance, corrosion resistance and heat exchange performance of battery packs are very important, which are related to new energy vehicles. safety and mileage. 

After search and investigation, the current battery pack liquid cold plate is mainly made of aluminum, and the liquid cold flow channel is made by stamping, inflation, extrusion and other processing methods, and is connected by brazing process and flange structure. Steel structural parts are connected.

Generally speaking, the aluminum battery pack liquid cold plate has the characteristics of high heat exchange efficiency. The existing liquid-cooling plate is mainly made of stamped aluminum plate, and its heat dissipation area is determined by the area of the punching channel. The area of the water channel is used to take away a lot of heat. After we determine the heating power of the battery, the simulation software is used to calculate the water-cooling plate The size and the length of the water channel, that is, the heat exchange volume.

Since battery packs, especially power battery packs, have stricter requirements on weight, stamping plates are generally used, and the required water exchange channels are punched out by using the principle of molds. The water channels can be connected in parallel or in series. The thickness of a water channel is generally about 2.0mm. The aluminum cover plate and the aluminum bottom of the punched water channel are welded together by a brazing process. After nitrogen test and water pressure test, it can be used for battery packs without leakage. cooling components.

Process characteristics of stamping plate water cooling plate:

  1. The mold of the liquid cold plate in the stamping process is relatively simple. Using the principle of mechanical pulling, the material is stretched and finally made into the required water channel size. However, considering the water pressure strength of the water channel, the thickness of the material is usually It is clearly stipulated that, for example, the depthof the 2mm aluminum sheet should not be higher than 2mm, otherwise the material will be cracked and there is a riskof water leakage. At the same time, the general hydraulic test is 0.5-0.8Mpa, too thin and defective stamping. Waterways are also at risk of deformation.

  2. The liquid cold plate stamped from the aluminum plate must be made of 3003 series materials, because the special welding brazing material is conducive to high-strength  weldability.

  3. he strength of the aluminum material is low, and the yield strength of the welded liquid-cooled plate is less than 100mpa. The liquid cold plate is likely to cause fluid leakage  when bumped or impacted, and then corrode the battery core. Therefore, the weight and mechanical structure of the battery protection is very necessary.

  4. Secondly, the melting point of aluminum is low, only 600 ℃, and its fire and explosion resistance is far from meeting the increasingly stringent battery pack design requirements. Therefore, the aluminum water-cooling plate must rely on the high-safety water-cooling plate structure design and reliability. battery pack system protection.

  5. Consider the corrosiveness of the water-cooling plate. Generally speaking, the refrigerants in the liquid cooling system of the battery pack mainly include solutions such as water and ethylene glycol. The liquid-cooling plate is easily corroded by them, which is easy to cause electrochemical corrosion. Therefore, the surface treatment of the water-cooling plate, especially the surface treatment of the flow channel, is very important. Generally speaking, our Wit is treated with the original color of the anode, which can achieve the purpose of anti-oxidation and protection.