Last Updated on April 25, 2023 by You Ling
Piezoelectric materials are intelligent materials that can convert mechanical energy into electrical energy when stress or strain is applied, and vice versa. Currently, automotive technology is the second largest market for piezoelectric products. Piezoelectric technology is used in various automotive industry actuators, fuel injectors, sensors, and various safety systems. Piezoelectric actuators convert electrical signals into mechanical motion, used to adjust mirrors, lenses, and other automotive components. It is said that fuel injectors using piezoelectric technology are more accurate and provide higher fuel efficiency and fewer emissions than similar traditional products. Fuel atomizers, keyless access systems, seat belt buzzers, airbag sensors, airflow sensors, sound alarms, knock sensors, and tire pressure sensors are among the main applications of piezoelectric materials.
Piezoelectric sensors in automotive applications
Piezoelectric materials are used in two ways in the automotive industry: directly and indirectly. Both have had a significant impact on the manufacturing and operation of automobiles, but their applications are quite different.
Direct: Directly applied piezoelectric materials are those materials that are integrated into vehicles to achieve various functions. These can be actuators, injectors, and sensors used to control, adjust, and sense various systems. Our piezoelectric materials are used to manufacture equipment in vehicles that can achieve precise, reliable control after billions of cycles and have repeatability and accuracy. This is a huge advantage for automotive applications, especially in systems related to fuel economy, performance, and safety, where malfunctions can cause significant issues.
Indirect: Indirect use of piezoelectric materials in the automotive industry includes their use in designing, manufacturing, and testing vehicles’ machines and robots. The high precision and accuracy of our piezoelectric materials used in various transducers, sensors, and actuators make them ideal for indirect automotive applications. From equipment used to align headlights to precise positioning of mechanical arms used to install components, piezoelectric technology plays a significant role in the automotive industry.
What are some application cases?
Pressure sensors
Pressure sensors are mainly used for measuring pressure and force and can also be used to measure internal combustion pressure and vacuum in engines. They can measure both large and small pressures, such as absolute pressure sensors for intake manifolds and knock sensors.
Because the electric charge of a piezoelectric pressure sensor after being subjected to an external force can only be preserved when the circuit has an infinitely large input impedance, it can only be used for dynamic stress measurement and not for static measurement. Due to its ability to withstand high temperatures and high humidity, it has been widely used in the automotive industry and other fields.
Knock sensors
The knock sensor is composed of a piezoelectric oscillator, metal sheet, sealed stem, metal shell, etc. The electric charge generated by the piezoelectric oscillator is proportional to the vibration of the engine cylinder, and the voltage produced is fed into the electronic control unit through the shielded wire. The electronic control unit determines the knock intensity based on the voltage size of about 7 kHz vibration, and promptly corrects the ignition advance angle, allowing the engine to work at the ignition moment closest to the point of maximum thermal efficiency and minimum fuel consumption, achieving a knock-free working state and ensuring the engine operates at the maximum possible power and economic index.
Piezoelectric Actuator
Piezoelectric actuators play an important role in many different vehicle components. The actuator converts electrical signals into precise physical motion called displacement. This displacement can fine-tune lenses, reflectors, and other components, it can act as a small volume pump, or trigger a hydraulic valve. You will find piezoelectric automotive actuators in any application that requires simplicity and reliability. Piezoelectric actuators require no maintenance and can operate billions of times without wear or degradation. He-shuai company produces various actuators for automobiles.
Piezoelectric Injector
Fuel injectors that use piezoelectric technology are said to be more accurate than their conventional counterparts. By using piezoelectric elements, the pivot in the fuel injector can open and close faster than traditional fuel injectors, resulting in more precise fuel injection control. It has been proven that fuel injectors using piezoelectric technology can improve fuel economy and reduce emissions. He-shuai company’s hard materials have higher stability and are very suitable for use in the harsh environments found in car engines.
Ultrasonic Sensor
Ultrasonic sensors are used as a car reverse collision warning device, also known as a reverse radar or backup sonar system, especially for large vehicles such as extended loading trucks, heavy-duty trucks, mining vehicles, and other large vehicles. Ultrasonic sensors are typically composed of an aluminum alloy shell, piezoelectric ceramic transducers, sound-absorbing materials, and lead wires. They have a wide horizontal directionality and limited vertical directionality. In principle, it uses the positive and negative piezoelectric effects of PZT piezoelectric ceramics to convert electrical energy into mechanical energy and vice versa. When an electric signal is applied to the piezoelectric ceramics, mechanical motion is generated and ultrasonic waves are emitted. When the ultrasonic waves encounter obstacles during their propagation in the air, they are immediately reflected back. When the reflected waves act on the piezoelectric ceramics, an electrical signal is output, and the distance between the vehicle and the obstacle is calculated and displayed by time difference measurement through data processing. It can accurately detect small obstacles in the rear of the car and the driver’s blind spots, and is very practical. To achieve high transmission efficiency and sensitivity, a combined ultrasonic sensor for transmission and reception is currently the mainstream product on the market, with high transmission efficiency, sensitivity, and sharp directionality. Ultrasonic waves have a certain detection angle and range and can cover the entire rear area of the car. Ultrasonic sensors are also used in car electronic suspension systems to directly monitor the distance between the vehicle’s chassis and the road surface.
Accelerometer
A piezoelectric accelerometer is a commonly used accelerometer. It has the characteristics of simple structure, small size, light weight, and long service life. Piezoelectric accelerometers have been widely used in the measurement of vibrations and impacts in aircraft, automobiles, ships, bridges, and buildings.
Piezoelectric accelerometers are used in automobile safety airbag systems. They use the inertial force generated by collision inertia to produce a proportional electric charge and voltage through the shear force acting on the piezoelectric ceramic body. They have high precision and good reliability. The accelerometer consists of two piezoelectric ceramic sheets bonded together by an internal common electrode, forming a two-stage structure, installed in the direction of motion, forming a cantilever beam, and integrated in a housing with a thick peripheral circuit. When detecting the intensity of low-speed or high-speed collisions of automobiles, it converts the signal into an electrical signal output and meets the requirements of various diagnostic control algorithms, ensuring that the safety airbag opens accurately and timely when the collision intensity is high, improving the safety performance of automobiles.
Using the correct type of sensor in this application will tell the automobile safety system to deploy the safety airbag within a fraction of a second, usually much faster than the front airbag system. This is necessary because the available reaction time can be significantly reduced when the door is close to the passenger compared to the dashboard airbag system. In this case, milliseconds are important.
Trends of Piezoelectric Sensors in the Automotive Industry
With further improvements in fuel economy, safety, and connectivity, the demand for piezoelectric materials and components in the automotive industry will only continue to grow. We see the industry focus in the following main areas:
Fuel economy: Improving fuel economy can be achieved in many ways. Lighter vehicles with more compact sensors and devices help increase fuel mileage. By continuously improving our piezoelectric materials, we can more accurately monitor speed, fuel rates, and operating parameters, as well as make real-time adjustments.
Safety: Improving automobile safety boils down to creating more reliable and faster controls for braking, collision prevention, and safety devices such as airbags. The increasing reliability and repeatability of piezoelectric materials means they will continue to drive automobile safety and further development in the future.
Connectivity: Automotive connectivity offers drivers a new way to experience their vehicles. Piezoelectric sensors and actuators are key components in proximity sensors and autonomous driving features. As automakers turn towards fully autonomous driving vehicles, our piezoelectric materials will continue to prove their importance.
