Electromagnetic drive/receiver unit for field devices in automation technology

Abstract

The invention relates to an electromechanical transducer unit (12) for a field device (1) in automation technology, and to a device (1) having an electromechanical transducer unit (12) according to the invention. The transducer unit (12) comprises at least one membrane (14) displaceable to perform mechanical oscillations, at least three rods (15a, 15b, 15c) perpendicular to the membrane ( The base area (A) of 14) is fixed to said membrane (14), housing (13), wherein said membrane (14) forms at least a part of the wall of said housing (13), and wherein said rod (15a, 15b, 15c) extending inside the housing, at least three magnets (16a, 16b, 16c), wherein in each case one of the magnets (16a, 16b, 16c) is held away from the membrane (14) fixed to each of said at least three rods (15a, 15b, 15c) in the end region of said at least three rods (15a, 15b, 15c), and a coil (17), said coil having a magnetic core (18) and enclosed in said magnets (16a, 16b, 16c) fixed inside the housing (13), wherein the coil (17) can be supplied with an alternating current alternating current signal. The coil (17) is implemented to generate a magnetic field which, via the magnet (16a, 16b, 16c), causes the rod (15a, 15b, 15c) to perform a mechanical oscillation, wherein the rod (15a, 15b, 15c) is fixed to the membrane (14) in such a way that the oscillations of the membrane (14) are generated by the oscillations of the rods (15a, 15b, 15c). According to the invention, at least one of said rods (15a, 15b, 15c) is fixed to said membrane (14) substantially at a position (22, 23) on said base region (A) of said membrane (14) , at said position (22, 23), the second derivative of the deflection of said membrane (14) from a rest position is substantially zero, depending on the position on the base region (A) of said membrane (14).

Description

technical field [0001] The invention relates to an electromechanical transducer unit for a field device in automation technology and to a device for determining and / or monitoring at least one process variable of a medium in a container and having an electromechanical transducer unit according to the invention . Process variables are, for example, the fill level or the flow rate of the medium or even its density or viscosity. The medium is located, for example, in containers, tanks or even pipes. Background technique [0002] In automation technology, various field devices are used to determine and / or monitor at least one process variable, in particular a physical or chemical process variable. For example, level measuring devices, flow measuring devices, pressure and temperature measuring devices, pH-oxidation-reduction potential measuring devices, conductivity measuring devices, etc., which record the corresponding process variables, material level, flow, pressure, tempera...

AI Technical Summary

Problems solved by technology

However, since there is no force-transmitting connection, the efficiency is usually significantly lower than in the case of piezo drive / receiver units

Although the electromagnetic drive / receiver unit is capable of generating relatively high forces in the region of the membrane, the deflection of the oscillating fork due to the non-force-transmitting connection between the membrane and the driver is relatively small

As a result, electromagnetic drive / receiver units require more energy than piezoelectric drive / receiver units, which makes it problematic to use the corresponding sensors in explosion-hazardous areas

Images