2、Classification of piezoelectric actuators
According to the different driving voltages:
High-voltage piezoelectric ceramic actuators
The internal structure of a high-voltage piezoelectric ceramic actuator is driven by a high-voltage stack of piezoelectric ceramics, with a driving voltage generally as high as 500V or 1000V. High-voltage piezoelectric actuators have lower static capacitance and generally higher output than low-voltage piezoelectric actuators.
Low-voltage piezoelectric ceramic actuators
The internal structure of a low-voltage piezoelectric ceramic actuator is driven by a low-voltage piezoelectric ceramic, with a driving voltage generally around 150V.
According to different appearances and performances:
Piezoelectric stack actuators - piezo stacks (multi-layered piezoelectric ceramics)
Stripe actuators (bending actuators)
Longitudinal actuators
Shear actuators
Tubular actuators - tube actuators
Contracting actuators
3、Working principle of piezoelectric actuators
Piezoelectric actuators convert electrical energy into mechanical energy by making most of the displacement attributable to the reverse piezoelectric effect. They are widely used in the field of industrial products for electronic and mechatronics integration. According to the working principle, they can be divided into two categories:
a) Motion-type products driven by piezoelectricity
These products use piezoelectric ceramics as the power source to produce linear or curved motion. They can be either the piezoelectric ceramics themselves, encapsulated piezoelectric ceramics, or piezoelectric ceramic motion platforms. This type of piezoelectric actuator is characterized by the term "motion", which refers to the piezoelectric ceramic product that produces motion.
b) Electrical control products driving piezoelectric motion products
These products are controllers that control the motion of piezoelectric motion products. They are characterized by the term "electrical", as they can output voltage and adjust the voltage and frequency to control the motion speed and amplitude of the piezoelectric ceramics. Based on this feature, they can be divided into various types such as modular, small-sized, integrated, USB-based, and board-based.
4、Components of piezoelectric actuators
Piezoelectric actuators (also known as piezoelectric ceramic actuators or mechanically packaged piezoelectric ceramics) use stack piezoelectric ceramics as the core driving source and are designed with special mechanical structures, including a movable end, a fixed end, a housing, and a flexible hinge pre-tightening structure connected to the stack piezoelectric ceramics. These stack piezoelectric ceramics are carefully assembled into the mechanical structure, forming the mechanically packaged piezoelectric ceramics.
5、How to produce piezoelectric actuators
Piezoelectric actuators consist of a piezoelectric element with at least one pair of electrodes formed on a piezoelectric ceramic plate, a holding part for holding the piezoelectric element, a bonding element or a restricting element such as a spring that restricts the piezoelectric element from leaving the holding part, and lead wires for applying voltage to the piezoelectric element, as well as electrical insulation elements such as resin or silicone oil coated on a pair of electrodes. In the piezoelectric actuator, the piezoelectric element of the piezoelectric ceramic plate is bonded, molded, or restricted by a spring. Although there is no applied voltage, a mechanical force (preset load) is applied by the restriction. In the piezoelectric actuator, when voltage is applied, the piezoelectric element moves as the voltage increases, increasing the mechanical force (load) due to the preset load and load increase. Therefore, the displacement of the piezoelectric actuator is relatively small compared to the displacement performance of the piezoelectric element itself.
The operating and driving conditions of the piezoelectric actuator include parameters such as temperature, driving electric field strength, driving waveform, driving frequency, and driving mode, which can be continuous or intermittent. The temperature range depends greatly on the environmental temperature variation of the product in use. The lower limit of the temperature range is equal to or higher than -40℃ and its upper limit is equal to or lower than approximately 160℃.
For piezoelectric buzzers, sonars, and piezoelectric speakers, the amplitude of the driving electric field strength is equal to or less than 500V/mm. For ultrasonic motors, piezoelectric transformers, etc., this value is equal to or less than 1000V/mm. For laminated piezoelectric elements, this value is equal to or less than 3000V/mm. In addition, when using resonance driving as the driving mode, the driving waveform is a sine wave. For other driving modes, the driving waveform can be any of various waves, that is, sine waves, trapezoidal waves, triangular waves, square waves, and pulse waves. In addition, the driving frequency for ultrasonic motors, sonars, and piezoelectric ultrasonic transducers is equal to or greater than 20kHz, while the driving frequency for other products is below 20kHz.
6、Machine equipment for producing piezoelectric actuators.
| API (AMERICAN) | www.americanpiezo.com |
| KEMET | https://www.kemet.com |
| PI | www.piceramic.com |
| EPCOS AG-tdk | https://www.tdk.com/ |
| belongs to CTS | www.noliac.com |
| Thorlabs, Inc. | https://www.thorlabs.com/ |
| Piezosystem | https://www.piezosystem.com/ |
| murata | www.murata.com |
| HE SHUAI | https://www.he-shuai.com/ |
