A new type of self-initializing and direct-measuring tire pressure monitoring system (TPMS) is being introduced by Johnson Controls at the 63rd International Motor Show (IAA) in Frankfurt, Germany.
“This system automatically detects the sensors and determines their positions,” explains Krister Gamaggio, the company’s product director of body electronics.
At the heart of the innovation is a patented auto-train/auto-learn algorithm integrated into the TPMS receiver, he says. It automatically calculates the positions of each tire sensor, analyzing signal input from the ABS and ESP control unit at the start of a journey. There is no need for a manual learning procedure, even after a tire change.
“This is new because in the past, changing wheels with comparable systems would have necessitated each new tire pressure sensor to be assigned to its respective position. And this is a manual initialization procedure requiring skilled authorized service center personnel,” Gamaggio reports.
A new set of tires can be localized within two to three minutes. The system can also permanently save another four sensor IDs, increasing the speed with which an additional set of “known” tires, such as snow tires, is positioned, he says. After the system detects these saved IDs, the sensors are localized quicker, even if the tires are mounted in different positions than before.
The system reports low pressure just as precisely for one individual tire as for all four tires, according to Gamaggio. The sensor technology can even detect a minimal 70 mbar change in pressure.
When pressure is constant, the current value is sent to the receiver once per minute. But if the system detects any abnormality, it moves to a faster mode: The sample rate is increased so that the sensor now takes a measurement several times per minute. If a pressure difference exists, the sensor immediately sends a sequence to the receiver with the new values. The transmission pattern ensures that even a marginal pressure loss during a journey is indicated within 10 seconds, or as soon the car is started after being parked. And even when the vehicle is parked, the tire pressure is still measured regularly, but at a lower frequency for energy-saving purposes, he points out.
The sensor battery has a lifespan of about nine years.
Unlike comparable direct-measuring system systems, he notes, it only uses a single antenna that is integrated directly into the TPMS control unit. “This reduces component costs while eliminating the need for additional cabling. The patented algorithm is the key to this cost-optimized solution, since it enables the definitive localization of the sensors without additional components. Because the software in the receiver is used to calculate all of the information needed to analyze the signals, no other components apart from the tire sensors are required. Like the antenna, all analytical components are integrated compactly into the receiver unit,” Gamaggio says.
The technology is available for all vehicle segments.
For more information, visit www.johnsoncontrols.com.
