Kistler Holding Ag

K.k. Holding Ag

Roland Sommer

Claudio Cavalloni

Kurt Vollenweider

Reto Calderara

Stefan Brechb&uuml;hl

A measuring element for measuring dynamic pressure, temperature and/or static pressure includes a body made of a piezoelectric material and having opposing side surfaces carrying electrodes. The piezoelectric material of the body is selected in such a manner that a thrust coefficient of the piezoelectric e-tensor is not equal to zero, with the result that the inverse piezoelectric effect can be used, and a transverse coefficient of the piezoelectric d-tensor is not equal to zero and/or a longitudinal coefficient of the piezoelectric d-tensor is not equal to zero, with the result that the transverse piezoelectric effect can be used in the transverse direction and/or the longitudinal piezoelectric effect can be used in the longitudinal direction in a simultaneous manner with the inverse piezoelectric effect.

Piezoelectric measuring element for measuring the dynamic and static pressure and/or the temperature

A piezoelectric measuring element () consists of at least two piezoelectric crystals () showing a transversal effect for the measurement of axially acting forces and/or pressures as well as to a pressure or force sensor comprising said element. The crystals () with transversal effect having an opposite polarization () to each other are attached to each other by means of a lateral electrode (). In this manner, if n crystals () are attached to each other, a single multi-layer measuring element () is obtained with a stability under load which is n-times that of an individual crystal. Preferably, the electrodes extend alternately into the two force-absorbing end faces () of the crystals. Such measuring elements can be fabricated from wafers () in a cost-effective manner. A compact multi-layer measuring element prepared in this way can be easily mounted in a sensor, particularly a force or pressure sensor, without the risk of inclination.

Multi-layer piezoelectric measuring element, and pressure sensor or force sensor comprising such a measuring element

A piezoelectric crystal with transversal effect comprising: at least one plate; and, at least one base at an angle to the at least on plate, the at least one base projecting laterally beyond a thickness of the least one plate on at least one side of the at least one plate. A piezoelectric sensor, for detecting one or more of force, pressure, acceleration, moments and strain signals, comprising at least one of the piezoelectric crystals with transversal effects. A method for producing the piezoelectric crystals with transversal effect is disclosed.

Crystal element for piezo sensors

The detector arrangement comprises a measuring rail with a number of individual elements each having a sensor mounted on a bottom rail and include rectangular elements as force introduction flanges, whose length in the direction of travel is a multiple of their width in the axial direction of the rail. The measuring rail is part of a measuring arrangement for detecting the tire pressures of vehicles in motion. The arrangement includes also at least one contact rail placed ahead of the measuring rail in the direction of travel, and a data acquisition facility. The vehicle speed is determined with the help of the contact rail. The measured values from the sensors yield a tire contact surface with an isobar pattern. From these two, the data acquisition can determine underinflation, normal pressure and overinflation of the individual wheels besides axle loads and vehicle weights, whereby underinflation and overinflation at least are displayed as faults.

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Neftenbach, Switzerland

Roland Sommer