According to a report by the International Energy Agency, after a decade of rapid growth, the number of electric cars on the roads worldwide hit 10 million in 2020, representing 1 percent of all cars. By 2025, the report predicts there will be 70 million electric vehicles and 230 million in 2030, representing 12 percent of all cars.
The fast-paced eMobility market is characterized by emerging technologies and players, a lack of clearly defined standards and established solutions. In addition, there is an extremely high innovation rate, and great pressure to bring the right products to market quickly. Original Equipment Manufacturers (OEMs) and their suppliers face a plethora of ever changing challenges and requirements.To keep pace with industry momentum, OEMs need to partner with suppliers that are reliable, competent, and agile.
To meet the needs of OEMs, suppliers need to move speedily from design to product development, prototyping, and into serial production. Solutions providers, for example, can help engine and battery OEMs reduce noise, friction and vibration through the development of lightweight, high-performance seals and damping materials.
Using their innovative technologies, research and development expertise, and know-how from other industries, suppliers can help OEMs reduce the time to develop products and manufacture functional prototypes.
The challenges for sealing are similar in almost every type of eMobility vehicle application, including trucks, buses, passenger cars, and motorcycles. The battery requires seals to protect it from the vibration of other components, like the drive motor and pumps, which operate at high speeds. Additionally, battery seals protect against environmental influences such as dirt, dust, water, and salt. If the systems are lubricated, they must also be compatible with the lubricant.
When it comes to cars, the requirements for seal performance in an electric motor are generally greater than for seals in a combustion engine. E-motors operate at significantly higher speeds and temperatures. Their components must also have a high level of media compatibility and be able to stand up to difficult environmental influences. The seals must deliver minimum frictional torque while offering static and dynamic sealing functions, regardless of the direction of the rotation.
It’s important for OEMs to partner with their suppliers continually to develop high-quality solutions for such demanding eMobility applications. These range from specialized rotary seals to advanced compounds and components for the electric motor and electric battery. Rotary seals should be engineered to efficiently run at the high speeds required to minimize power losses and maximize the available distance the car can travel on a single charge.
Component suppliers also need to ensure important properties such as insulation, thermal and electrical conductivity, and electromagnetic shielding around the battery. The compounds must withstand the high temperatures typically found in electric motors. Fluid compatibility is particularly complex as the media used in the electric motor differs from that used in gasoline and diesel engines, which have established and proven sealing solutions.
A good parts manufacturer will create battery seals for customer-specific applications. The battery cover should not only protect the battery from moisture but also provide resistance to high-pressure water spray during testing and real-world conditions in which tires spray water at the seals while operating in the rain. Additional functional features such as venting, fire protection and damping add value for the automotive manufacturer.
When electric cars were developed, many people thought the noisy world of the internal combustion engine would soon be history. While electric and hybrid-electric automobiles are quieter, it doesn’t mean they’re silent. The noise of a typical combustion engine is no longer there to mask other structure-borne noises from the gearbox housing and other components.
Electric drivetrains have vibrations and noises that range in loudness and severity. Tier 2 suppliers help reduce these noise, vibration, and harshness issues to acceptable levels for OEMs. In the electric vehicles’ drivetrain, for example, power inverters are one of the main contributing sources of noise. This is worrisome to automotive OEMs and their suppliers because the last thing they need is a noisy car that puts off potential consumers.
When an inverter manufacturer had a power inverter noise issue, the solution was based on the same basic technology used for brake shims. It’s called Applied Damping Material (ADM), a constrained layer of damping material that consists of metal layers vulcanized together with rubber to produce a strong and durable laminate. Together, the polymers, rubber and adhesive effectively absorb mechanical energy and the vibrations that radiate noise.
ADM works on all sorts of vibrating structures in automotive drivetrains, but for this situation a new variant of ADM was needed. By combining different metal and polymer thicknesses, the ADM supplier created a greater level of damping at a wider noise frequency and higher temperature. While the exact material composition is proprietary, the polymers are based on nitryl butadiene rubber (NBR). The adhesive is typically an acrylic, though other materials can be used.
It’s critically important that the ADM contains no loose metal particles past a certain size, as these can enter the engine or even the electronics and cause a short circuit. For this reason, the ADM supplier worked diligently to control the level of particles—often invisible to the naked eye at tenths of a millimeter in size—on the parts it supplies to the engine OEM.
The interest in electric cars and eMobility is ever growing, and the technology is quickly changing to keep up with demand. As the market evolves, it will be critical for OEMs to partner with suppliers that can react rapidly to provide innovative, high-quality solutions at all stages of the production process. Properties such as insulation, thermal and electrical conductivity, and electromagnetic shielding need to be considered.
To ensure a smoother, quieter journey, OEMs must find ways to combat noise, vibration, and harshness with material innovations like variations of ADM.
Harlan Hart is technical manager-new business development of Trelleborg Sealing Solutions.
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