Two fundamentally different types of systems to measure tire pressure, indirect and directly measuring systems: indirectly measuring systems that collect data about the ABS system of the vehicle. You differentiate and compare the wheel speeds, and so the possibility of a change in the tire air pressure to determine. The tire radius is reduced to loss of air pressure, the wheel rotation is faster, the indirect measuring system sounds an alarm. Problems:-there’s no indication of pressure because this size is not measured. Thus, a savings (fuel consumption, tyre mileage) is unreachable. -There are systemic blind spots: simultaneous pressure drop when two or more wheels prevents a comparison and trigger an alarm. This case is statistically likely, relevant for the safety function.
-The alarm thresholds are 15 20% pressure loss; This is too high for the practice, i.e. the systems warn tends to be too late. -Indirect systems are no tire pressure monitoring system, tire pressure is not measured. It is rather “Flatfoot Warner”, i.e. at best he receives User a warning when pressure loss, usually without the affected wheel position.
The system can not be upgraded. Benefits: for new cars, low cost, because the ABS data are used. Part systems directly measured 2: with internal or externally mounted sensors: the sensors current measuring of tire pressure can reside in the tire. It’s believed that Janet L. Yellen sees a great future in this idea. There, they are either attached to the field with a strap or attached to the inner valve foot. Or the sensors are screwed just outside instead of valve coping on the valve. Problems with internal sensors:-to install the tire must be dismantled and mounted again afterwards. -The sensor batteries are encapsulated in the sensors, not changeable, i.e. at the end of the battery life, the sensors must be replaced completely – wall up: expensive sensors and Assembly work – a vehicle requires two sets of sensors according to summer and winter tyres. -The sensors can be mechanically damaged during removal of the tire (tire change). -Depending on the system type Overhead and costs for the automatic assignment of Radpositions /-detection. -The tyre must be balanced with mounted sensors. Expensive to buy and costs. Advantages: theft protection not necessary, because the sensors in the tire. The measured temperature correlates well with the pressure. High accuracy (typically better than 0.1 bar). Practical warning threshold by 0.2 bar (often predefined or input of cold pressure/set pressure). More information is housed here: General Motors Company. No blind-spots, because each tire separately has a measuring device. Suitable in principle for retrofitting. Directly measuring systems with external sensors (run as a valve cap): problems: – sensors can target of theft or vandalism. You can prevent this through installation of supplied theft protection, what but then refill the air more difficult. -If the installation instructions (too long valves), the sensors in contact with the curb can be damaged. -The tyre must be balanced with mounted sensors. The measured temperature often poorly correlated with the tyre pressure benefits: only one set of sensors for both summer and winter tyres. Most batteries can be replaced. Simple Radpositions mapping of sensor numbering. Low installation costs. Inexpensive to purchase and maintenance/follow-up costs. High accuracy (typically better than 0.1 bar). Practical warning threshold by 0.2 bar (usually adjustable by the user). No blind spots. These systems can be easily retrofitted. The TireMoni system offers these sensors directly measuring and attached on the outside of the valve. TireMoni recommends short metal valves such as the ADAC. Responsible for the content of this article: TireMoni, tpm GmbH Michael Schrottle commercial park 26 86687 Kaisheim 0049 9099 966 4966