When it comes to foods and beverages, the suffix “light” often suggests there is less of something – less fat or calories, for instance. In the DIAvent product family from Freudenberg Sealing Technologies (FST), this term suggests a focus on a single function: pressure compensation, that is, the way electronic devices “breathe.” In DIAvent products, “light” also stands for state-of-the-art, automated production technology.
DIAvent, FST’s patented pressure compensation valve, combines two functions in a single component for the lithium ion batteries that power electric vehicles. First of all, it provides ventilation during normal operation, and thus pressure compensation in the battery housing. The batteries are true power packs and have to be continually aerated and vented, for example, to balance out fluctuations in air pressure while vehicles are driven uphill and downhill – or as a battery heats up or cools. The goal is to prevent the deformation of the battery housing.
The second DIAvent function deals with “thermal runaway” in a battery cell. This is an emergency situation. If a cell is damaged, the Freudenberg valve responds with very high venting rates, quickly reducing the massive overpressure resulting from the incident. With DIAvent Highflow, the second member of the DIAvent product family that was introduced in 2020, this emergency venting is achieved very quickly.
No “Double Life” required
Like batteries, electric motors and their power electronics have to “breathe” continually. Inverters are one example; they transform the direct current from the battery into alternating current for use by the motor. But they do not require “emergency degassing.” Furthermore, not all battery manufacturers want this “double life,” the integration of two functions into a single component.
With this in mind, the Lead Center Diaphragms in Reichelsheim, Germany, developed the “DIAvent Light.” The newest family member is totally focused on pressure compensation during normal operation, in batteries, electric motors, and inverters. The first series order for DIAvent Light from a leading automaker has been signed and sealed. In the fourth quarter of this year, series production in Reichelsheim will begin in grand style, with very high volumes from the outset. The prototypes manufactured on new equipment in the spring left little to be desired.
DIAvent Light is totally focused on pressure compensation during the normal operation of batteries, electric motors and inverters.
Checked-out and traceable
The production cell for DIAvent Light has a special feature. Its operation is completely automated. The new component consists of four individual elements that the system assembles into a functioning unit using ultrasonic welding, among other techniques, without human intervention. That’s not all. This high-tech system checks the functionality of each part in a completely automatic process. Is it watertight? Is the air flow rate within the narrowly prescribed limits? And then the automatic visual inspection takes place. With these checks in place, only parts that operate flawlessly reach the customer.
Some special features of DIAvent Light: To firmly anchor it in the housing, it is affixed with novel filigree clips. Its radial seal is unique in the market, providing the pressure compensation element with reliable protection against the penetration of water, dust and other media from outside. The core feature of the component is its air-permeable, watertight diaphragm made of expanded polytetrafluoroethylene (ePTFE). The material stands out for its high resistance to chemicals and extreme temperatures, among other qualities.
The protective cover is laser-engraved with the customer’s logo and product data while it is still in the automated manufacturing cell. That means individual components can be clearly identified and traced. The design of DIAvent Light has been standardized, so it can be used on the current customer’s other platforms or on those of other manufacturers.
Welcome to “DIAland”
FST is producing the first two DIAvent generations as well the new light version in Reichelsheim. And the DIAvent family is continuing to expand there. DIAvent Light will be getting an oil-resistant sibling, adding the word “oil” as a suffix to the name. It is designed for use in so-called “wet,” or oil-lubricated, gearboxes, axles and differentials.
“DIAvent’s growth has been very dynamic. The business is booming and the demand from customers has been huge. Internally, employees even have a tongue-in-cheek name – ‘DIAland’ – for the steadily growing production area for the family,” said Daniel Uhl, Manager, Product Marketing, Lead Center Diaphragms. “Our role is changing with products of this type. We are not providing individual diaphragms or seals. We are integrating several components into finished parts that perform important functions in electric powertrains. This takes us one step higher in the value creation chain.”
Christian Kleinke, manager, Product Development, Lead Center Diaphragms, adds: “Products such as DIAvent are posing new challenges for our product development activities and process technologies. Today we are working with production technologies in Reichelsheim that we were not involved with just a few years ago. We have largely developed the skills that we need on our own.”
In line with these developments, the production technology for the first DIAvent generation will be automated and modernized in Reichelsheim in several months.
