Showing papers on "Piezoelectric sensor published in 1985"

Underwater piezoelectric arrangement

Abstract: Underwater piezoelectric arrangement in which it comprises two piezoelectric elements made of piezoelectric ceramic-polymer composites and juxtaposed to form a single layer structure, one of the element(s) having larger hydrophone constant than that of the other element(s), and by noise cancelling of the piezoelectric assembly there can be selectively detected only charges or voltages generated by acoustic waves which acts on each element.

Reinforced piezoelectric transducer and pressure sensor using such a transducer

Abstract: A piezoelectric transducer including a polarized piezoelectric material film, which also has a reinforcing material incorporated into the mass and which prevents any deformation of the film in certain given directions. The invention also relates to a pressure sensor using such a transducer. This sensor can be used both as a pressure sensor and as a pressure gradient measuring device.

Piezoelectric ratio weighing device

Abstract: A piezoelectric device is used to determine a ratio of a second weight with an original weight where the second weight is less than the original weight. A piezoelectric driver is resiliently attached to a base that is isolated from vibrations. A piezoelectric receiver and a reed are resiliently attached to the piezoelectric driver so that (1) the read is moved in response to motion of the piezoelectric driver, and (2) the piezoelectric receiver gives an electric signal out proportional to motion of the system. The entire system is set to operate on the leading edge of the resonant frequency for the system. By applying an oscillating sine wave voltage, such as 140 hertz, to the piezoelectric driver, and by applying an unknown mass to the tip of the reed, a first output is obtained from the piezoelectric receiver which represents the original weight. Next by removing part of the mass by any convenient means, such as heat, a second output is obtained that represents the second weight. By a ratio of the second output/first output (or a signal equivalent to the weights being measured), the percent of the mass remaining is determined.

Automated System for Measuring the Constants of Low-Q Piezoelectric Materials

Abstract: We have implemented a new system for extracting the relevant constants of unloaded piezoelectric resonators from impedance measurements. This system utilizes the facility of computer controlled acquisition systems to obtain large quantities of data, and a least-squares fitting procedure to interpret the data in an optimal way. This method is especially valuable for low-Q piezoelectric materials which are not treated accurately by many standard measurement techniques. It also facilitates the collection of data from a large number of "identical" disks, for studying their piece-to-piece variations, or for quality control in transducer production.

Peak combustion pressure timing detector for internal combustion engine

Abstract: Apparatus for sensing the timing of peak combustion pressure in an internal combustion engine includes a capacitive piezoelectric element adapted for flexure in response to variations in combustion chamber pressure and connected in parallel with a first resistance, a constant current generator connected to establish a predetermined voltage across the first resistance and thereby across the piezoelectric element when the capacitance of the latter remains constant, a second resistance, a source of the predetermined voltage, and an operational amplifier effective to compare the voltage across the piezoelectric element with the predetermined voltage and source or sink current through the second resistance to maintain the predetermined voltage across the piezoelectric element. The output voltage of the operational amplifier is an analog of the current through the second resistance and thus of the rate of change of capacitance of the piezoelectric element. The crankshaft angle after ignition at which this voltage crosses the predetermined reference corresponds to the timing of peak combustion pressure. In order to reduce noise in the 6 to 9 kilohertz range, the first and second resistances may be reduced, the second resistance bypassed at high frequencies and the output voltage amplified with low pass filtering.

Piezoelectric electroacoustic transducing device

Abstract: PURPOSE:To inexpensively mass-produce a piezoelectric electroacoustic transduc er which is small in size, light in weight, high in reliability, and good in manufac turing yield with high performance having constant quality, by forming an enclosure and sound producing and receiving element of the same material integrally. CONSTITUTION:A piezoelectric plate 11 for sound production or sound reception, electrodes 12 and 12', elastic plate 13, and box body 15 are united integrally and the parts except the electrodes 12 and 12' are constituted of a piezoelectric ceramic material. At the time of sound production, AC electric signals are inputted to electrode terminals 14 and 14' and the piezoelectric plate 11 put between the electrodes 12 and 12' tends to extend and shrink in the lateral direction due to a piezoelectric effect. Since the piezoelectric plate 11 is joined to the piezoelectric inert elastic plate 13 integrally, the piezoelectric plate, electrodes 12 and 12', and elastic plate 13 are deformed by bending upward or downward integrally. Thus input electric signals are converted into acoustic energy and sounds are transmitted to the outside through through-holes 16 provided in the upper part of the enclosure 15.

Method for manufacturing a piezoelectric composite material

Abstract: This process consists in making the composite material from a mixture of powder of piezoelectric ceramic of a particle size less than 400 m and of a hardenable liquid dielectric binder placed, during hardening of the binder, in a mould provided with orifices 44 for liquid overflow and installed between the plates 45, 46 of a press exerting on it a pressure greater than 40 bars. The figure gives an example of mould for making a piezoelectric composite disc according to the method. This mould, placed between the plates 45, 46 of a press, comprises an annular lateral wall 41, a matching bottom 42 and a lid 43 fitted with orifices 44 for liquid overflow. By virtue of the method, a piezoelectric composite material is obtained which is particularly advantageous for making a piezoelectric sensor sensitive to hydrostatic pressures.

Tool abrasion monitoring method

Abstract: PURPOSE:To discriminate the condition of abrasion of a tool, by comparing the output of a pressure sensor during cutting, which is disposed between a holder for a cutting tool and a tool main body or between the tool main body and the tip of the tool, with the output of the pressure sensor which is previously st as a value upon normal cutting CONSTITUTION:A cutting tool 10 is secured to a piezo sensor 1 laid on a bed for the tool 10 A force from a workpiece is exerted to the tip of the tool due to the resistance of cutting, and is also applied to a pressure sensor 1, and an electric charge in proportional to the force is generated This electric charge is compared with an electric charge which has been obtained beforehand upon normal cutting Accordingly, if the electric charge abruptly increases, it is indicated that any fault takes places in the tip, and further, the more the frequency of increases in the electrical charge, the more the abrasion of the tool progresses