Measuring and testing – Fluid pressure gauge – Vibration type
Patent
1990-12-26
1993-06-22
Woodiel, Donald O.
Measuring and testing
Fluid pressure gauge
Vibration type
7386241, 73862, 73 59, 73DIG4, 310338, G01L 116
Patent
active
052208362
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention is directed to a measuring method for identifying or, respectively, for monitoring mechanical and/or physical quantities, whereby a sensor containing at least one piezoelectric transducer element is exposed to the quantity to be identified or, respectively, monitored and an electrical sensor signal influenced by this quantity is evaluated as measured signal. The invention is also directed to a measuring arrangement comprising a sensor containing at least one piezoelectric transducer element and comprising a measuring amplifier in communication therewith via a signal line together with electrical return; the invention is also directed to advantageous employments of such an inventively equipped measuring arrangement.
PRIOR ART
Methods and arrangements of the said species are known in the greatest variety of contexts and are being employed to an increasing degree. Thus, Austrian Patent 276,810 discloses a piezoelectric sensor that, for example, can be employed for monitoring the combustion process in the combustion chamber of an internal-combustion engine. To this end, the sensor is introduced in sealing fashion into an indicator bore of the wall of the combustion chamber and a suitable measuring amplifier is connected to the signal output of the measured value pick-up, this evaluating the measured signals generated by the piezoelectric transducer element via the direct piezoeffect given pressure fluctuations in the inside of the combustion chamber. The disadvantage of this known arrangement or, respectively, of the measuring method appertaining thereto is comprised therein that the piezoelectric transducer elements can have relatively pronounced zero shifts due to the resistances and leakage currents that are always present, so that measurements of practically only dynamic pressure changes--or, respectively, of changes of quantities to be measured having a defined frequency--can be meaningfully implemented and that, correspondingly, no absolute or static measurements can be carried out. Further, there is also no possibility of checking or, respectively, adjusting the sensor in the measuring chain with respect to its correct function, so that there are always certain uncertainties in view of the measured result.
Further, piezoelectric sensors are also known which are suitable for static or, respectively, quasi-static measurements due to the nature and arrangement of their transducer elements or, respectively, due to the execution of the measuring method and the nature of the interpretation of the measured signals. Thus, for example, Austrian Patent 353,506 discloses a piezoelectric sensor with which various quantities such as, for example, temperature or pressure can be identified or, respectively, monitored via the change in the resonant behavior of a piezoelectric resonator arranged in the sensor. Such sensors have an extremely high resolution but usually have only an extremely low dynamics because of the high counting rates required therefor. In addition, the disadvantage that the sensor cannot be monitored or adjusted in view of its function in the measuring chain continues to exist given these arrangements or, respectively, methods.
Finally, Austrian Patent 369,900 also discloses, for example, a piezoelectric sensor that contains transducer elements of the above-recited type combined both for static as well as for dynamic measurements, high resolution and dynamics on the one hand and employability for static or, respectively, quasi-static measurements on the other hand being therewith achieved. Disadvantages thereby derive insofar as the sensor itself must be constructed in a relatively complicated way due to the two transducer elements together with independent feeds or, respectively, signal lines and thus does not come into consideration for many applications. Further, the measuring amplifiers respectively required for the two separately sequencing measuring methods must be offered, connected, etc., this increasing the measuring outlay overall and producing further pos
REFERENCES:
patent: 4297872 (1981-11-01), Ikeda
patent: 5000050 (1991-03-01), Hetrick
Harms Klaus-Christoph
Krempl Peter W.
Moik Joseph
AVL Gesellschaft fur Verbrennungskraftmaschinen und Messtechnick
Woodiel Donald O.
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