SU928233A1 - Piezoelectric measuring converter of acceleration - Google Patents

Description

I

The invention relates to the measurement of motion parameters, in particular, piezoelectric transducers, designed to measure shock accelerations, and can be used to measure forces and pressures.

Known measuring transducers of accelerations have a relatively low immunity due to the fact that the electrodes of the piezoelectric elements are directly connected to the connecting cable, the length of which, and hence the level of interference, may be significant.

Closest to the proposed technical essence and the achieved results is a device containing the mass of the sensing element mounted on a piezoelectric element mounted in the housing, and a connecting cable tZ.

A disadvantage of this device is the relatively low sensitivity in remote measurement of shock accelerations due to the large capacitance introduced by the connecting cable and low noise immunity.

The aim of the invention is to improve the noise immunity.

The goal is achieved by

10 that the device and the resistor connected in series with the electrodes are connected in series with the device, and the connecting cable is connected to the resistor.

ts

Figure 1 shows a simplified structural diagram of a piezoelectric measuring transducer; 2 is his electrical circuit.

Piezoelectric measuring

Claims (1)

20, the acceleration transducer see Fig. 1) contains a base 1 of the housing on which piezoelectric element 2 is placed, made in the form of a washer and loaded with a mass 3, which simultaneously performs the function of the electrode of the piezoelectric element 2, 3, and the grooves of mass 3 have a resistor (and Unicycle 5 insulated from mass 3 with the help of tubes 6 made of insulating material. One end of the resistor is electrically connected to the base of the housing 1 and the other with the central pin connector 7 and simultaneously with one of the electrodes of the discharge element 5. Mass 3, piezoelectric element 2, and base 1 to The second is also the second electrode of the piezoelectric element, glued together. There is a cavity 8 for balancing the mass 3. To eliminate 8J and the external environment, the cover 9 is attached to the base 1 of the converter. Discharger 5 can be vacuum or gas-filled. Before the measurement The converter is screwed into a threaded hole prepared in advance in the object. The hole aperture coincides with the direction of the measured acceleration component. To the connector 7, the response time of the connector of the connecting cable is invoked (not shown in FIG. 2). Another connector of the power cable connects to the amplifier and matching unit. Piezoelectric measuring transducer accelerations is as follows. In the presence of acceleration W (see Fig. 1), piezoelectric element 2 experiences inertial action from mass 3. When a deformation of piezotlement 2 occurs, electric charges appear on its surface. Since the measured acceleration cannot change instantaneously, as it increases, the charge and potential difference between the electrodes 10 of the piezoelectric element 11 (see, Fig.2) and, consequently, on the electrodes of the discharge sensor 12, increase proportionally. Resistance The sensor 12 before the onset of the breakdown is equal to the insulation resistance, which is several orders of magnitude greater than the resistance value of the resistor 13. Therefore, the voltage on the discharge electrodes is almost equal to the voltage on the piezoelectric electrodes. 8 moment of exceeding the value of 9 4 pro (of the voltage of the discharge voltage, the spark discharge occurs. 8 moment of discharge, the resistance of the discharge current 12 drops sharply, and a short circuit current flows through it, resulting in a short-term voltage pulse across the resistor 13. The pulse duration is determined by the time of the breakdown, which stops as soon as the potential difference between the electrodes 10 does not decrease until the voltage of the extinguishing of the discharge signal 12, flo as the charge acceleration increases further on the electrodes 10 and the sweat difference The accelerations will increase again until the next spark discharge in discharge 12. The described process will repeat as the shock acceleration increases. Thus, during the acceleration rise time on the resistor 13 through vit7 with a series of short pulses of voltage through the connecting cable 14 are fed to the matching amplifier and then to the measuring equipment (not shown in figure 2.) The number of pulses and the time intervals between them carry information about the measured shock acceleration. Due to the relatively high pulse power compared to the signal power with direct continuous measurement of the charge on the electrodes, the noise immunity of the measurements is improved, while it is possible to measure shock accelerations with significant removal of the measuring equipment from the installation site of the piezoelectric measuring transducer. Claims of the Invention A piezo-electric acceleration transducer containing a mass of a sensing element mounted on a piezoelectric element fixed in a housing and a connecting cable, characterized in that, in order to increase the noise immunity, a series-connected rider and resistor connected to the electrodes are inserted into it, and the connecting cable is connected to the resistor.