Shopping Cart
(Your shopping cart is empty)

TPMS Links

Find TPMS by Manufacturers

Wholesale & Training

Online Payment Service
Home > TPMS News > Direct TPMS in Days of Development

In the early days of development TPMSs were implemented using radio frequency technology, to avoid expensive and rather complicated rotating contact wiring, together with an electronic control unit fitted inside the vehicle, which provides the necessary processing functionality to interpret pressure data coming from battery powered sensor transmitters within tire cavities. The system delivers alerts and warnings to the driver. Companies like Schrader Electronics designed first generation TPMSs using battery powered radio transmitters, with sensors mounted on a standard tire valve, and a chassis mounted radio frequency receiver, whose functions can also be integrated in other radio-frequency units mounted on the vehicle, such as Remote Keyless Entry receivers, and Body Control Units. Typical RF TPM systems employ four or five battery powered transmitter-sensors,[9] one RF receiver (either stand-alone or integrated in other vehicle electronics), and some other satellite hardware which can perform the function of identifying the tire position involved in the inflation anomaly. Each tire pressure sensor can periodically trigger a transmission of pressure status, or be polled continuously on demand. The most technologically challenging part of the system is the conservation of battery power used by the RF transmitter-sensor. Most RF based TPM sensors on the market today use a battery, a silicon-based pressure sensor, and an RF oscillator (either SAW- or PLL–based). Automakers require a battery lifespan of between seven and ten years, so TPMS system designers use power saving techniques to extend the battery life. The heart of the sensor is a silicon application-specific integrated circuit (ASIC) chip, which can manage critical power saving algorithms and other functions of the sensor. However, there remains the fundamental problem that all batteries eventually become exhausted with the result that the consumer is faced with flat battery problems as well as flat tire problem. The battery represents safety and replacement cost issues for the consumer. Vehicle manufacturers are also concerned about costly warranty claims and litigation that may result if injury and loss of property occur as a consequence of RF based TPMS battery failures.[9] In the US, there are approximately 16 million new passenger vehicles manufactured annually, which must ultimately comply with the legislative requirements of the TREAD Act, and be fitted with TPMS. If each vehicle has four or five wheels fitted with battery-powered RF TPMS wheel modules there could be more than 65 million batteries introduced annually into the environment. Disposal of the batteries in such a widespread consumer application is a minor environmental concern compared to the other wastes from automobile operation. To overcome the battery issues a new generation of batteryless TPMS is being developed by two companies using quite different technologies. Transense is promoting a SAW-based technology. VisiTyre is using an electromagnetic close-coupling technology to effectively eliminate the battery. VisiTyre batteryless TPMS is in pre-production preparation for supply and integration into model year 2009 vehicle platforms. Transense has licenced its technology to several automotive companies but it is not yet commercially available for OEM passenger vehicles. Other developments with TPMS include research into the use of energy harvesting devices which may lead to future types of batteryless TPMS. Recently STE Engineering, a company based in the North of Italy, introduced a new class of OEM oriented TPMS tire stem whose concept is basically the integration of a simple hybrid ceramic circuit inside the body of a standard tire stem, as opposed to traditional TPMS which have an electronic PCB located in a dedicated plastic box, just beneath the tire stem itself [10]. Advantages of this solution are obviously connected to the use of an ISO-TS qualified tire stem, as normally used in the automotive market, allowing huge cost savings and enabling standardization of remote direct TPMS. Due to extremely reduced power consumption, measured to be about three orders of magnitude low power less than standard technologies, this new application allows use of reduced size battery cells— in fact, now a 12.5 mm diameter standard cell can replace the 20 mm cell normally used. STE says that, being able to "survive" fed by the very small energy harvesters devices are able to generate, this new technology approaches the highly desirable "Battery-less" operating condition; Other benefits are: reduced overall weight, mechanical robustness, cost reduction, and extended temperature range (-40° +125°C).STE concept introduces a new methodology which sees in-stem electronics rather than "attached-to-the-stem" technology: the high grade of integration has been achieved through a substantial reduction of components with benefits in terms of costs savings and enhanced mechanical robustness. The PM17, that's the name of the new concept of tire stem, has demonstrated to be able to improve supply chain performances with regards of production planning and logistics: the similarity of PM17 tire stem to traditional mechanical valves normally available on the market, well support OEM's planning of risks reduction due to non-conformal mounting processes, after-market and after-sales strategies: the procedure of installing a PM17 TPMS wheel unit clearly avoids weird procedures used to couple tire's bid with rims when mounting standard "butterflied" TPMS. The PM17 tire stem has been recently demonstrated during the IVth international Intelligent Tire Technology conference in Wiesbaden (October 2008)