Monitor Tyre Pressure Permanently
Singapore, 22 January 2007 – With automatic tyre pressure control systems, dangerous road-traffic situations due to incorrect tyre pressure can be prevented. For the first time, Hella is presenting a fully-autonomous radio-based system with direct measurement. This system is suitable for retrofitting to almost all passenger-car tyres.
The system consists of four wheel sensors, an electronic control unit and a multi-colour display. The wheel sensors measure permanently the air pressure and the internal temperature of the tyres and transmit this data to the electronic control unit by radio. In the event of sudden pressure loss, the control unit triggers an optical and acoustic alarm via the display positioned in the cockpit. Furthermore, the system also warns of slow loss of pressure and of excess pressure.
To install the system, it is necessary to replace the conventional tyre-pressure valves with wheel sensors with integrated valves from Hella. This is possible only at a specialist garage or at a tyre service centre. The sensors measure air pressure up to a maximum of 5.3 bar. An integrated and especially long-life high-performance battery with a service life of up to ten years serves as the energy source. Data transmission to the electronic control unit in the vehicle takes place via a radio signal at a frequency of 433.92 megahertz (MHz).
The electronic control unit is roughly the size of a cigarette box and can be fitted in a concealed manner at a suitable point on the dashboard. The control unit evaluates permanently the incoming radio signals and, if necessary, provides a warning via the display. In the event of sudden loss of pressure, it gives an acoustic and a red optical alarm, and the affected tyre is indicated in the display. If the air pressure in a tyre sinks to less than 75 percent of the reference value set beforehand, an acoustic and an amber optical warning will be given. If there is only 50 percent or less air in the tyre, there is a red alarm, and the driver should stop the car immediately and check the tyre. In the event of excess pressure up to a maximum of 5.3 bar, the system also gives an optical and acoustic warning via the display. The system is especially important for so-called run-flat tyres, as the outside appearance of this type of tyre does not change in the event of pressure loss or excess pressure.
A unique special feature of the multi-colour display is the facility to choose the colour of the background illumination and to adapt the colour of the display illumination to the vehicle concerned. Seven pre-defined values are available for this: blue, green, white and various red values. Alongside this added-value which, to date, is available only with the Hella system, the display stands out thanks to the completely independent design.
It can be set to European or US measurement variables [Celsius or Fahrenheit, bar, kPa (kilopascal, Great Britain) or psi (pounds per square inch, USA)]. The system is type-approved in accordance with European ECE and American SAE standards. It also meets the strict requirements of the American standard FMVSS 138, according to which such systems are prescribed for new vehicles up to a gross vehicle weight of 4.54 tons. Hella supplies the entire control system with four sensors, the control unit and the display. In addition, a maximum of three sensors (such as for spare tyres), which are offered individually, can be added to the system.
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