*3.2.3 Sonar equipment*

Sonar Equipment depends especially on piezoelectric sensors to transmit and receive ultrasonic "pings" in the 50-200 kHz range. Along with an ideal frequency response for such applications, piezoelectric transducers have a high power density that enables large amounts of acoustic power to be transmitted from a small package. For instance, a transducer that is only 4″ (100 mm) in diameter may be capable of handling power output greater than 500 watts.

**Figure 3.** *A piezoelectric pressure sensor.*

## **3.3 Piezoelectric actuators in industrial applications**

In this times when piezoelectric sensors are highly valuable to the industrial sector, the industry also makes use of piezoelectric actuators for a variety of applications:

may need to be adjusted (shaped or contoured) in real-time by means of a control system. This will compensate for aberrations that would otherwise

• Some fiber optic converters rely on piezoelectric actuators to modulate the

Piezoelectric Actuators also contribute to ultrasonic cleaning applications. To perform ultrasonic cleaning, objects are immersed in a solvent (water, alcohol, acetone, etc.). A piezoelectric transducer then agitates the solvent. Many objects

Piezoelectric ultrasonic cleansers (**Figure 4**) provide capabilities such as ultrasonic breaking up of kidney stones and removal of dental plaque. They are used to conduct precise measurements to identify flaws and other anomalies detected

One advantage of using piezoelectric materials is that their characteristics are precise and predictable. Thus, expansion and contraction of a piezoelectric actuator can be precisely controlled as long as the supply voltage is controlled. Some motor designs take advantage of this fact by using piezoelectric elements to move a rotor or linear element in precise increments. Precision on the order of nanometers can be achieved with some piezo motor designs. Piezo motors work at a wide range of

In addition to their inherent precision, piezoelectric motors can be used in environments with strong magnetic fields or cryogenic temperature — environments where conventional motors are unlikely to work. These unique challenges are present in MRI machines, particle accelerators, and other similar environments.

Multiple piezoelectric elements will be stacked to replace the displacement achieved for a given voltage. These types of devices are known as stack actuators (**Figure 5**), and they are employed in variety of specialty applications. Compared to

with inaccessible surfaces can be cleaned using this methodology.

between transmitters and receivers of ultrasonic waves.

frequencies but typically work best in a low frequency range.

impede image resolution.

*DOI: http://dx.doi.org/10.5772/intechopen.96154*

*Piezoelectricity and Its Applications*

output of a laser.

*3.3.4 Ultrasonic cleaning*

*3.3.5 Piezoelectric motors*

*3.3.6 Stack actuators*

**Figure 4.**

**81**

*Piezoelectric ultrasonic cleansers.*

### *3.3.1 Diesel fuel injectors*

In the last decade, regulations on emissions from diesel engines have become increasingly stringent. In addition to this, customers continue to demand quieter engines with improved power and torque curves. In order to meet these stringent demands for compliance and performance, engine manufacturers have resorted to using precisely timed and metered injections of fuel during the combustion process [12].

Besides the working of other applications in piezoelectric devices, a single fuel injector may switch fuel flow with pressures exceeding 26,000 psi (1800 bar) on and off several times in rapid succession during a single power stroke. Such precise control of high-pressure fluid is made possible by using piezoelectric actuators controlling small valves within fuel injectors.

Equipment which involves diesel engine emissions have become increasingly stringent, yet customers' demands for quieter engines with improved power output has led the world's leading firms in fuel injection technologies to invest in extensive research and development. To fulfill the customers demands while remaining compliant and ahead of regulatory pressures, Piezo Diesel Injectors were developed to reduce emissions by making the combustion of fuel within the cylinder more efficient. Such technological progress leads a new phase with possibilities of improved performance and reduced emissions through precisely timed and metered injections of fuel during the diesel combustion process.

#### *3.3.2 Fast response solenoids*

Some processes require quick and precise mechanical actuation that is difficult, if it is not satisfied by that process it uses electromagnetic solenoids to achieve. While speed may not always be a concern, power consumption or compactness of size is the most prominent one. In accordance with this, piezoelectric actuators are often able to fill the niche as they provide fast response and low power consumption in small packages, compared to electromagnetic solenoids.

#### *3.3.3 Optical adjustment*

Some optics needs to be adjusted or modulated with a wide frequency response and with a minimum number of moving parts. Piezoelectric actuators are often employed in such applications where they provide fast and accurate control over a long service life:


may need to be adjusted (shaped or contoured) in real-time by means of a control system. This will compensate for aberrations that would otherwise impede image resolution.

• Some fiber optic converters rely on piezoelectric actuators to modulate the output of a laser.
