Showing papers on "Piezoelectric sensor published in 1979"

Piezoelectric element for incorporation in pressure, force or acceleration transducers

Abstract: A piezoelectric element for incorporation in pressure, force or acceleration transducers, in which at least two piezoelectric flat plates loaded in shear mode are arranged on both sides of a central support and are retained under compressive pre-tension by pressure distribution members bearing externally on the piezoelectric plates; a compression form member provided with a location hole for the support, the piezoelectric plates and the pressure distribution members is fitted over the pressure distribution members by direct or indirect shrinking the pressure distribution members are preferably made of two exact fitting cylindrical segments transmitting the tension forces evenly over the piezoelectric plates.

Oscillation sensor, particularly combustion engine knock sensor

Abstract: In order to detect the occurrence of engine knock (pinging, detonation), a piezoelectric sensor is mounted on the engine in a location where the oscillations due to engine knock are readily transmitted. The detector is a strip or strips of piezoelectric material mounted in cantilevered configuration in a clamping device. An advantageous location for the sensor is a bore within one of the cylinder head bolts of the engine. A variety of embodiments is described including the provision of seals for permitting the introduction of a damping fluid in the receiver bore for the sensor.

Low pressure piezoelectric transducer for e.g. blood containers - has deformation compensation electrodes and detachable pressure chamber

Abstract: The low pressure piezoelectrical measurement transducer for blood containers or vegetable and animal cells, comprises a piezoelectric body which has electrodes providing a measurement voltage corresponding to the pressure exerted and the resulting deformation of the body. The device eliminates the errors occurring with known instruments by virtue of the compression of the measurement fluid, and does not involve a pressure drop associated with a medium flowing out. The piezoelectric sensor body has additional electrodes to which are fed an electrical voltage for compensation of the deformation. The deformation compensating voltage is regulated using the measurement voltage. A pressure chamber with a capillary input tube is detachably mounted on the piezoelectric body. It has a filter and shut-off valve.

Electrical pulses produced by cavitation bubbles

Abstract: It is shown that an electrical sensor, plunged in water in which ultrasonic cavitation is produced, generates pulses whose amplitude may reach several hundred microvolts. By using this sensor jointly with a piezoelectric sensor, the author demonstrates the simultaneity of the electrical pulses and the pressure pulses produced by the collapses of the cavitation bubbles.

Measured value converter with piezooelectricity measuring element

Abstract: A transducer with a flexible sensor element for measurement of mechanical values, at least one flexible piezoelectric sensor element being provided for piezoelectrical or capacitive measurement, the opposite surfaces of the sensor element being at least partially connected to electrically leading contact surfaces.

Contacting of integrated circuits - uses circuit emitted sound for quality check, evacuated by piezoelectric sensor as sound receiver

Abstract: System supports are used for wiring of integrated circuits to the wiring system of the respective device or apparatus. The connecting legs of the system support are then connected to the corresponding connecting spots of the integrated circuit. For this purpose the contacting of the integrated circuit uses a sound emission of the circuit. The emission is detected by a receiver and evaluated for quality checking, particularly for detection of cracks or other defects in the silicon crystal. Preferably an unattenuated piezoelectric sensor is used as the detector in indirect connection to the integrated circuit. The detector may be connected to a recording device via a frequency filter and an amplifier.

Use of piezoelectric multicomponent force measuring devices in fluid mechanics

Abstract: The characterisitics of piezoelectric multicomponent transducers are discussed, giving attention to the advantages of quartz over other materials. The main advantage of piezoelectric devices in aerodynamic studies is their ability to indicate rapid changes in the values of physical parameters. Problems in the accuracy of measurments by piezoelectric devices can be overcome by suitable design approaches. A practical example is given of how such can be utilized to measure rapid fluctuations of fluid forces exerted on a circular cylinder mounted in a water channel.