طراحی، مدلسازی و ساخت شیر پیزوالکتریک نیوماتیک مبتنی بر مکانیزم منعطف جهت کنترل فشار هوا

High-frequency pneumatic on/off (digital) valves are widely used in industrial automation. Similar to servo and proportional valves, the function of these valves is to continuously adjust the flow rate or pressure as a function of the input signal. On/off valves use solenoid actuators, which may have drawbacks such as high response time delay due to the electrical signal delay in the coil and reduced response speed, as well as the digital nature of these actuators (on/off operation). To solve this issue, piezoelectric actuators are used instead of solenoids. Due to the limited displacement amplitude of piezoelectric actuators, a rhombus-type compliant mechanism is used to amplify the displacement amplitude of the piezoelectric actuator. Next, a method for the kinetostatic and dynamic analysis of compliant mechanisms is presented, where the static results obtained from this method are in good agreement with the finite element method results, and the rhombus mechanism has the highest amplification at angles around 2 degrees. Additionally, the error in the obtained natural frequencies is less than 15.5%. The performance of the piezoelectric valve is then examined. To ensure that the piezoelectric valve can control different pressures, three sinusoidal reference signals with different frequencies and pressure amplitudes were applied to it. After one period, the output pressure can accurately follow the target signal. A step signal with a pressure amplitude of 1 bar was also applied to the piezoelectric valve, where the time required for the pressure to rise from 10% to 90% of 1 bar is 8.3 milliseconds. This behavior indicates that the response speed of the piezoelectric actuator combined with the compliant mechanism can be very suitable for this valve.