Avl Gesellschaft Fur Verbrennungskraftmaschinen Und Messtechnik M.b.h.

Other

Avl List Gmbh

Akubio Limited

Peter W Krempl

Wolfgang Schindler

Gunter Engel

Uwe Posch

Helmut List

Wolfgang Wallnofer

Alfred Enko

Klaus-Christoph Harms

Herbert Thanner

Christian Reiter

Erich J Schiefer

Leopold Faschingleitner

Peter Claassen

Rudolf Zeiringer

Ferdinand Krispel

Johann Stubenberg

Gerhard Woess

Friedrich Radke

Engel Gunter

Joseph Moik

Wolfgang Walln&ouml;fer

Gabriele Voborsky

Roland Selic

Alfred Nitsch

Wolfgang Singer

Guenther Wegscheider

A piezoelectric resonator element of crystallographic point group 32, which can be operated as a thickness shear resonator contacting a carrier medium includes a singly rorated Y-cut (S,S) that is essentially rotated through an angle &#x3c6;about the crystallographic x-axis, which differs from crystal cuts that are temperature-compensated in air or vacuum, wherein the cut has a negative temperatue coeffcient of the resonace frequency f(T) in a predetermined temperature range, preferably between 10&#xb0; C. and 40&#xb0; C., when there is no contact with the carrier medium, while the value of the linear temperature coeffcient a of resonance frequency in the same temperature range is less than 1 ppm/&#xb0; C., preferably less than 0.5 ppm/&#xb0; C. when the resonator is inb contact with the carrier medium. The resonator element () can additionally be provided with at least one layer sensitive to the parameter to be measured.

Piezoelectric resonator element of cyrstallographic point group 32

The invention relates to a method for determining the non-volatile component of aerosol particles in a gas sample, especially in the exhaust gas of internal combustion engines, where the aerosol particles are deposited on an oscillating sensor () of at least one crystal microbalance (), and the change in at least one oscillation parameter of the oscillating sensor is employed as measurement variable. According to the invention the oscillating sensor () of at least one crystal microbalance () is maintained at a temperature of more than 200&#xb0; C. during deposition of the aerosol particles, and preferably between 250&#xb0; C. and 350&#xb0; C.

Method and apparatus for determining the non-volatile component of aerosol particles in a gas sample

A process to determine aerosol particles in gaseous samples, specifically in the exhaust of diesel motors, includes the at least indirect deposit of aerosol particles on a piezoelectric oscillating crystal and the determination of the oscillation parameters of the piezoelectrically stimulated oscillation of the crystal. In order to assure the required reproducibility reliably and independently of the type of aerosol particles, and thus to achieve a high quality of measurements, the piezoelectric crystal is charged to oscillation during less than half the period of deposit of aerosol particles.

Method for the measurement of aerosol particles in gaseous samples

To obtain large, high-quality crystals of a metal orthophosphate, in particular GaPO or AlPO , from a nutrient solution with the use of seeds, a seed crystal is used having at least two rod- or wafer-shaped legs which form an angle with each other and define a main growth region, and which are positioned eccentrically in the single crystal grown. Contagious faces of two seed legs, which have been chosen for crystal growing, enclose an angle <180&deg;. In this way the yield of the high-quality crystal region will be increased.

Method for the growing of single crystals

To improve temperature compensation of a piezoelectric element measuring mechanical variables, such as pressure, force, and acceleration, with two or more piezoelectric crystal elements, at least one of the crystal elements differ from the other crystal element(s) either physically or chemically, the positive temperature coefficient of a piezo-coefficient of at least one piezoelectric crystal element compensating the negative temperature coefficient of the other crystal element(s), so that the overall piezoelectric sensitivity of the measuring element will remain essentially constant within a given temperature interval.

Piezoelectric measuring element for measuring mechanical variables

A piezoelectric crystal element for surface acoustic wave applications with a quartz substrate with at least one substantially planar quartz surface, the planar quartz surface having an epitaxially grown layer of a quartz-isomorphous crystal with the total molecular formula ABO.sub.4, A standing for Al or Ga, and B for P or As, and the quartz surface and the epitaxial layer having approximately the same crystallographic orientation.

Piezoelectric crystal element

In order to obtain large, high-quality crystals or crystal layers of a me orthophosphate, in particular, GaPO.sub.4 or AlPO.sub.4, from a nutrient solution with the use of a seed plate, the proposal is put forward that in the initial phase of the growth process a seed plate of alpha-quartz (.alpha.-SiO.sub.2) be introduced into the nutrient solution, and that fluoride ions (F.sup.-) be added to this solution, at least for formation of the primary crystal layer on the quartz seed plate.

Hydrothermal process for growing large crystals or crystal layers

For surface acoustic wave devices temperature-compensated piezoelectric crystal elements with one or more planar faces are used. An improvement in temperature stability may be expected if the crystal element is made from GaPO.sub.4 and the planar face is defined by Euler angles .lambda. in the range of 0.degree., .mu. in the range of 40.degree. to 75.degree., i.e. preferably 50.degree. to 60.degree., and .theta. in the range of 0.degree..

Method and arrangement for piezoelectric measurement

In order to prevent crystal seeds with retrograde solubility from dissolving in the hydrothermal growing solution at the beginning of the growing process, and to protect the finished crystal at the end of the growing process, and in order to reach the thermodynamic growth equilibrium as soon as possible, the proposal is put forward that the growing solution be prepared, pre-saturated and pre-heated to a temperature close to saturation temperature outside of the growing tank, and that, for the growing process proper, the hot growing solution be added to the pre-heated growing tank provided with crystal seeds, where it should be further heated to a temperature at which the crystals start growing, and, further, that the hot growing solution be quickly removed from the growing tank as soon as the growing process has been completed.

Apparatus for growing homogeneous crystals

A charge amplifier circuit comprising an operational amplifier unit whose signal output is back to a signal input of the amplifier unit via a capacitative feedback element, the signal output of the operational amplifier unit also being coupled to an input of a following, further transmission unit that has a proportional, integrating transfer characteristic with a break-over frequency that is at least approximately equal to the break-over frequency of the operational amplifier unit, this being at least in the proximity of the break-over frequency defined by the feedback element of the operational amplifier unit. The feedback element of the operational amplifier unit can be optimized independently of the operating frequency range, this, allowing for a low resistance value for the feedback element given a transfer behavior that remains linear, this despite the low capacitor value that increases the charge sensitivity.

Charge amplifier circuit

In order to improve the temperature stability of piezoelectric and elastic properties of piezoelectric crystal elements based on GaPO.sub.4, preferably for resonator applications, and to facilitate alignment when the crystal elements are cut from the raw crystal bars, the proposal is put forward that the principal plane H of the crystal element be parallel to a cutting plane, which is generated by rotating a hexagonal prism face of a raw crystal bar, which lies parallel to the optical axis, around one of the two-fold crystallographic symmetry axes a.sub.1, a.sub.2 or a.sub.3 through an angle .theta. of -5.degree. to -22.degree..

Piezoelectric crystal element on the basis of GAPO.sub.4

A method and device for delay-free measurement of the air/fuel ratio of combustion systems, especially internal combustion engines, by measuring individual components of the fuel, the ambient air used for fuel combustion, and the exhaust gas, wherein the water vapor concentrations of the exhaust gas and, preferably, the ambient air or the gas supplied for fuel combustion are measured, and wherein the air/fuel ratio are computed by the obtained values and data on fuel composition.

Method and a device for measuring the air/fuel ratio of an internal

Method of growing homogeneous crystals

In piecoelectric measuring elements comprising two or more crystal elements that are jointly subject to the mechanical variable to be measured and are provided with electrically conductive electrodes on opposite surfaces located essentially normal to the electric (x) axes of these crystal elements, disadvantages arising from shearing stresses can be prevented by using crystal elements (2) from crystals of point group 32, in which exist two opposite types of enantiomorphism, l and r, in which part of the crystal elements used belong to one of the two enantiomorphic types l or r, and have one of the two absolute orientations of the x-axis, .alpha..sub.1 or .alpha..sub.2, while the remaining crystal elements belong to the opposite enantiomorphic type and have the opposite orientation of the x-axis.

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Graz/Ragnitz, Austria

Peter W Krempl