11/11/2023 0 Comments Mini piezo igniterPiezo elements shaped as benders serve widely in pneumatic valves. Stack transducers can be found in liquid valves, such as those used in diesel fuel-injectors and micro positioning. This allows only short strokes-a maximum of 0.2% of the overall height-but with actuating forces of up to several kilonewtons. In contrast to disc transducers, operation is not triggered by bending the composite material but by expansion in the direction of the field. Stack transducers (piezo stacks) are towers of stacked piezo discs connected mechanically in series but electrically in parallel. Overall, the disc bends spherically, letting them be used in high-frequency loudspeakers, sensors, micro pumps, fans and ultrasound generators, such as are often used in automobile distance sensors. If a voltage is applied to the top surface and the ceramic disc, the ceramic expands and the disc becomes thicker with a smaller diameter. To generate an electric field, the flat area on the disc’s top surface must be metalized. This increases its performance and lets it operate across a wider temperature ranges, thanks to its symmetry.īender actuators are used in circular knitting machines, reading devices for those with bad eyesight (Braille modules) and pneumatic valves-especially proportional valves for pressure and flow control.Ī disc transducer consists of a thin ceramic disc bonded to a metal substrate. It has a second ceramic layer sandwiching the substrate. One variation on the bender actuator is called the trimorph. Typical characteristics include deflection of several tenths of a millimeter and forces up to 1 N. One end of the actuator is usually fixed, so motion gets converted to a bending movement.īender actuators can be designed to have a range of possible forces and motions, and they are well-suited for use in pneumatic valves. This piece is also joined all along one side to a conductive substrate. Piezo elements can be crafted into several types of actuators, depending on what the needs are: disc transducers, bender actuators or piezo stacks.īender actuators are rectangular with a piece of piezo ceramic material that has been rendered conductive on both surfaces. In applications that need to be extremely energy-efficient, it is even possible to recover the charging energy when the drive is reset and then use it again for the next charging operation. Electrical power is calculated as voltage × current, so the power is zero if no more current flows. Current only flows while the capacitor is charging, and flow drops to zero when charging is complete. In electrical terms, a piezo element is a capacitor consisting of two electrically conductive plates and the ceramic piezo material between them acting as a dielectric. This is one advantage of piezoelectric valves and drives. These shape changes can be harnessed to power a drive and be created using almost zero power. Using strong electric fields, engineers can give some ceramics piezoelectric properties that make them change shape when a voltage is applied. They found some materials, usually ceramics with conductive surfaces, convert electrical energy into mechanical energy and vice-versa. The piezoelectric effect (from the Greek word for “pressing”) was discovered in 1880 by the brothers Jacques and Pierre Curie, the latter being the husband of Marie Curie.
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