Abstract
This paper describes the effects of the asymmetricity of a pneumatic cylinder on the frequency characteristics of a valve-controlled cylinder system. Theoretical analysis is carried out on the system, wherein a valve, which has lap unevenness (i) and mean underlaps ( Δ, Δ'), is used, and an asymmetric cylinder which has an intertia load with Coulomb and viscous frictions is used, where the flow rate versus the pressurec haracteristicsc urvesf or the valve are approximatedp artiallya s polynomialso f degree 3 of the pressure ratio.
The effects of ratio of piston effective areas (ram), lap unevenness, amplitude of the input sinusoidal spoold isplacement( yo)and Coulomb friction of the asymmetric cylinder on the frequency responses of the system are studied.
Even though the valve has even underlaps, a suitableb ias ( δ) is necessary to the spoold isplacemen to keep the mean piston position of the asymmetric cylinder at some fixed point. The normalized value of bias (δo) changesa ccording to the changes of ram, yo and i. The(δo) versus frequency characteristics are studied. For an underdamped system, the value of δo has a peak around a resonance frequency.
