What are the technical processes for the production of liquid-cooled plates for power lithium batteries?

The heat dissipation design is accurate and avoids excessive temperature difference in the system. This is due to the performance requirements of the lithium battery. The performance and aging of the battery are closely related to the working temperature. The liquid cold plate production process is more complicated than the general air-cooled heat sink. The liquid cooling heat dissipation has high requirements on the process reliability, so the manufacturers with strong technical precipitation can provide reliable technical support. The general liquid cold plate production technology has the following several techniques.

Buried tube process

The buried pipe process is the most widely used liquid-cooled radiator liquid-cooled plate manufacturing process. Generally, the aluminum substrate is buried in a copper tube, that is, the aluminum substrate is machined by a CNC, and then the punched copper tube is bent. It is pressed onto an aluminum substrate, brazed and then processed into a water-cooled plate.

The buried tube type liquid cooling plate generally has three forms: one is a shallow buried liquid cold plate; the other is a deep buried liquid cold plate; the third is a welded pipe process; and the fourth is a double-sided pinch process liquid cold plate. The three forms of crafts are not much different, and the difficulty of processing is the same. Some of the original liquid cooling principles designed for high-power switching devices can also be used for reference in power battery cooling systems.

Shallow tube process: It is suitable for single-sided installation. After the copper tube is flattened and the aluminum plate is milled at the same time, it is beneficial to the high thermal conductivity of the copper tube to take away the heat. The use of aluminum lightweight plays the role of weight reduction and cost control.

Deep buried pipe process: The filler is made of high thermal conductivity epoxy resin imported from the United States. When the temperature difference of the cooling device is not high, it can be installed on both sides, because the thickness of the copper pipe is not processed twice and the filler protection can provide application, safety especially suitable for cold plates with refrigerant as medium.

Welded pipe process: suitable for copper plate + copper pipe, in order to reduce the thickness of the plate to reduce weight.

Double-sided pinch process: two-sided mounting device, simple process and low cost; aluminum plate + aluminum tube & copper tube & stainless steel tube.

Profile + welding

Liquid-cooled heat sinks processed on the basis of profiles. These heat sinks are more shaped and have more types, such as plate type, channel type, and combined type. The general production principle is based on profiles. Processing and welding, the profile and the joint pipe are combined into a whole liquid cooling radiator.

The cold plate flow path is directly formed by the extrusion process, and then the cycle is opened by the machining method, and the welding process is usually performed by friction welding, brazing welding, etc., the process has high production efficiency and low cost; and is not suitable for excessive heat dissipation density. The application is not suitable for applications where the surface has too many screw holes to limit the water course or reduce reliability. Mainly used in: power battery water cooling heat sink, water separator and standard power module integrated heat sink products.

Machining + welding

The water-cooled plate adopts the machine-added mode, and the internal flow channel size and path can be freely designed. It is suitable for thermal management products with large power density, irregular heat source layout and limited space. It is mainly used in: wind power converters, photovoltaic inverters. The design of heat dissipation products in the fields of IGBTs, IGBTs, motor controllers, lasers, energy storage power supplies, and supercomputers is less used in power battery systems.

The microchannel heat sink is also a heat sink manufactured by combining machining and welding processes. It is more complicated to manufacture than other heat sinks. Microchannel heat sinks are generally used on machines with large heat dissipation and concentrated heat dissipation. The way of the channel is because the water channel is wider and more uniform, and it can quickly take away the concentrated heat.

However, the micro-channel liquid-cooled heat sink manufacturing process is also relatively complicated, generally using a machined microchannel, and then using a friction welding process for welding, and the manufacturing cost is also high.

Die casting + welding

The die-casting process is a very mature and widely used forming method. With the rapid development of new energy vehicles, it has become the first choice for mass production of motor controllers, power battery pack trays and heat-dissipating boxes, but it is necessary to control die-casting impurities in the process. Problems such as stomata, conservative use of sealing ring method or friction welding all need to improve the reliability of the process to avoid water leakage.

Die-casting and re-welding, good process control, stable process, and batch delivery capability. In addition to the friction welding process, some water-cooled plates are also brazed or vacuum brazed.

This kind of water-cooled plate can be considered together with the battery-packed die-casting box. The AudiQ7PHEV lower-layer water-cooled plate is such a usage. At the Beijing Auto Show two days ago, the molded sample display has been seen.

Typical model water-cooled plate

In the power battery system, there are many ways to take heat away from the surface of the battery. Only in the scope of action, it can be divided into a battery-level water-cooled plate integrated inside the module and a module-level water-cooled design outside the module. board. The following are a number of pictures from the public number of "power battery Thermal Management Technology" to illustrate the application of water-cooled panels in actual cases.

Module level water cooled plate

As a whole, the water-cooled plate acts on one or more battery modules. As the component of the whole battery pack, instead of the components of the battery module, we put it under the head of the module-level water-cooled plate.

Square battery liquid cooling system, most of which use module-level water-cooled plate, and is generally placed at the bottom of the battery box; soft-pack battery liquid cooling, the module is integrated with small water-cooled plates, and there are integrated aluminum plates in the module. The outside of the group is set in the form of a module-level liquid-cooled plate; the cylindrical battery, the serpentine tube headed by Tesla is the main liquid cooling radiator.

The page contains the contents of the machine translation.