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Miniature sensors that regulate automobile

Miniature sensors that regulate automobile performance are designed in a very particular way to operate properly while housed directly on moving automobile tires. They need to have the sensitivity to pick up measurements while in motion and the durability to withstand the elements.

Tire pressure is the unsung hero of automobile performance. When inflated to the proper pressure, tires are the exact shape that the designers intended. As air pressure decreases, the tires need more energy to move. Drivers can easily forget to maintain their tire pressure in the day-to-day routine of moving from one place to another. Punctures can take place and go completely unnoticed. That is why having an onboard sensor that alerts the driver when it’s time to add more air makes all the difference. Creating these sensors requires careful consideration of all the fine details, and simulation provides the tools for finding just the right design.

Tire Pressure Sensors Shape Driving Experience

Schrader Electronics manufactures 45 million sensors annually and provides sensors to leading automotive companies including GM, Ford, and Mercedes. For a sensor to survive road conditions throughout the life of a vehicle, reliability and durability are key. Consideration is given to shock, vibration, pressure, humidity, temperature, and various dynamic forces when designing for the necessary functions, geometry, and materials. Christabel Evans, an engineer with the Schrader Electronics mechanical design team, has been using finite element analysis (FEA) and multiphysics simulation to build successful, efficient tire sensors for all kinds of vehicles.

Designing Better Sensors with FEA

Schrader Electronics has been creating sensors for almost 20 years, but Christabel Evans and her colleagues wanted a more efficient approach for product design and testing. They simulated their designs using FEA and iterated the process—this allowed them to minimize experimental cost and to evaluate design performance during development. Schrader Electronics found that the existing FEA software options were expensive if they wanted to deploy it to their entire team. They turned to using the Structural Mechanics Module and the CAD Import Module of COMSOL Multiphysics®. They started with a series of tests, comparing standardized samples with simulations to validate the software and build confidence in the results.

Improving Sensitivity and Durability with Better Simulation

the researchers began incorporating more natural parameters into their simulations, from dynamic loads such as centrifugal force, to environmental stresses such as temperature change, to static factors such as pressure and crush load. The Hi-Speed Snap-In TPMS consists of a transmitter made up of a circuit housed in an enclosure and attached to a valve stem with a cap. The valve stem connects to the tire rim and allows air to pass through. On the Hi-Speed TPMS, the valve geometry includes a rib that helps retain the assembly in the rim hole.

The researchers at Schrader were able to learn COMSOL Multiphysics software much faster than similar simulation packages, and deployment through the organization was easier because of flexible licensing options. According to Evans, “COMSOL is user-friendly and it is fast to learn—the engineers picked it up right away.”

At the moment, Schrader plans to spend most of their focus on design and growth, with some emphasis on failure analysis, but they hope to improve their development-focused approach with the aid of simulation tools. They are working hard to improve driver comfort, environmental impact, and road safety with each new design.