Piezoelectric ultrasonic actuator WUAkLL000 description - Wischnewskyi Ultrasonic Motors
PRODUCTS
PIEZOELECTRIC ULTRASONIC ACTUATOR WUAKLL000.
Design and description:
The WUAkLL000 piezoelectric ultrasonic actuator (see FIG. 1) includes a WUPe000-3 piezoelectric element with three electrodes (position 1) or a WUPe000-4 piezoelectric element with four electrodes (position 2).
The electrodes are located on the main surfaces of the WUPe000-3 or WUPe000-4 piezoelectric cell.
Both types of piezoelectric elements are made of hard PZT piezoceramics.
The WUPe000-3 piezoelectric element has one common electrode and two excitation electrodes (item 3). The WUPe000-4 piezoelectric element has two common electrodes and two excitation electrodes (item 4).
All electrodes are located symmetrically about the axis Os.
Piezoelectric ceramics between the electrodes of the piezoelectric elements WUPe000-3 and WUPe000-4 are polarized normally to the surface of the electrodes.
One or two WUFe000 friction elements are installed on one or two sides of the WUPe000-3 piezoelectric element or the WUPe000-4 piezoelectric element, symmetrically with respect to the Os axis.
Piezoelectric elements WUPe000-3 and WUPe000-4 with the friction elements WUFe000 installed on them form the piezoelectric actuators WUAkLL000-3-1, WUAkLL000-3-2, WUAkLL000-4-1, WUAkLL000-4-2 (positions 1, 2).
Piezoelectric elements or actuators have a length L width B and thickness D (position 1, 2).
The length L determines the resonant frequency Fr of the actuator and its operating frequency Fw. The width B and the thickness D of the actor depend on its length L.
Position 5 shows a circuit for measuring actuator parameters WUAkLL000-3-1, WUAkLL000-4-1, WUAkLL000-3-2, WUAkLL000-4-2.
In this circuit, the source of exciting electric voltage U1 should be a “voltage source” i.e. It must have low internal resistance (5 ohms or less).
Position 6 shows the generalized frequency response of the actuators WUAkLL000-3-1, WUAkLL000-4-1, WUAkLL000-3-2, WUAkLL000-4-2.
At position 7, the main electrical and mechanical parameters of actuators WUAkLL000-3-1, WUAkLL000-4-1, WUAkLL000-3-2, WUAkLL000-4-2 are presented.
These parameters are measured in a free state of the actuators.
- The resonant frequency Fr.o, at a low level of excitation, is measured at the maximum current Ir.o flowing through the piezoelectric element (actuator).
- The maximum current Ir.o, with a low level of excitation, is set separately for each value of the standardized length L of the actuator.
- The operating frequency Fw.o, at a low level of excitation, is slightly higher than the resonant frequency Fr.o and corresponds to the operating current Iw.o of the actuator, which is approximately 0.8 Ir.o.
- The static capacitance Co of an actor is measured directly at the frequency ten or more times lower than the resonance frequency Fr.o.
- The electrical impedance Re.o of the actuator at a frequency of Fr.o, at a low level of excitation (active resistance of the actuator), is calculated by the formula Re.o = U1 / Ir.o.
- The mechanical quality factor Qm.o of the actuator with a low level of excitation is calculated by the formula Qm.o = Fr.o / (F2-F1).
- The frequencies F1 and F2 are measured at a current of Iq.o = 0.7 Ir.o, on both sides of the frequency Fr.o.
Piezoelectric ultrasonic actuator WUAkLL601-3-1 is shown below.
An assortment of actuators type WUAkLL000.
Wischnewskiy Ultrasonic Motors offers an expanded assortment actuators type WUAkLL000 working on longitudinal acoustic waves for a wide range of applications.
The table below shows the types offered actuators, which may have 3 or 4 electrodes and 1 or two frictional elements. The below table shows the averaged values of the main parameters of the actuators. At the request of the customer, Wischnewskiy Ultrasonic Motors Corporation can manufacture housing for the appropriate actuator size and the friction rail to form the piezoelectric ultrasonic motor.
| Actuator size: | L,mm | Fro,kHz | Co,pF | Vm,m/c | Fm,N |
WUAkLL701 | 70 | 53.15 | 1380 | 0.6 | 50 |
WUAkLL601 | 60 | 62.0 | 1250 | 0.6 | 35 |
WUAkLL501 | 50 | 74.4 | 1000 | 0.6 | 25 |
WUAkLL401 | 40 | 93.0 | 850 | 0.6 | 15 |
WUAkLL301 | 30 | 124.0 | 625 | 0.6 | 9 |
WUAkLL201 | 20 | 186.0 | 420 | 0.6 | 4 |
WUAkLL101 | 10 | 372.0 | 210 | 0.6 | 1 |
