Mechanism of temperature-induced zero drift on electro-hydraulic servo valve

Abstract

An electro-hydraulic servo valve is objectively asymmetrical in the process of fabrication and assembly, and the zero position is the result of comprehensive adjustment. During the use of the electro-hydraulic servo valve, the rapid rise of temperature will lead to the zero drift phenomenon and the change in the flow state of the servo valve. With the change in temperature, the thicknesses of air gaps, the size of the orifice, the flow coefficient, the armature’s arm of force, the permanent magnets’ reluctances, and the polarization magnetomotive force, the stiffness of the spring tube and feedback rod will act on the property of the torque motor and the pilot stage. Considering the factors of temperature and processing assembly on the zero drift of the electro-hydraulic servo valve, a mathematical theory model describing the temperature zero drift characteristics is constructed. When the temperature range is 20–270 °C, the analysis demonstrated that the control error of the servo valve will exceed the expected 15%. The temperature has the most significant effect on the servo valve through the flow coefficient. The initial installation angle deflection is the domain route on the temperature zero drift, and other factors have less effect. Compared with the experimental results, the temperature-induced zero drift model correctly calculates the control error trend of the servo valve caused by an increase in temperature, and it will contribute to improving the control precision of the servo valve.

Thermally compensated common-path differential interferometer with reduced long-term zero-drifts

“…The zero-drift as a phenomenon has been studied in adjacent areas of engineering (e.g. [16,17]) or as a partial aspect of specific methods (e.g. [18,19]) related to interferometry.…”

Temperature drift mechanism of deflector jet servo valve under temperature shock

“…According to Yan et al 24 and Ma et al, 25 the effect of upper and lower pole pieces and armature in the magnetic circuit are neglected. The four air gap flux of torque motor are…”

“…To analyze the mechanism of temperature action on the deflector jet servo valve, the impact of each route on the control accuracy of the deflector jet servo valve under temperature variation is first considered separately. According to Mao, 23 the range of simulation temperature is set to 20°C–250°C, and the simulation is carried out using the temperature drift model of deflector jet servo valve at the command current of 1 mA; the parameters are shown in Table 4, Table 5 and Ma et al 25…”

“…To analyze the mechanism of temperature action on the deflector jet servo valve, the impact of each route on the control accuracy of the deflector jet servo valve under temperature variation is first considered separately. According to Mao, 23 the range of simulation temperature is set to 20°C-250°C, and the simulation is carried out using the temperature drift model of deflector jet servo valve at the command current of 1 mA; the parameters are shown in Table 4, Table 5 and Ma et al 25 The parameters of equation ( 36), which include the air gaps' thicknesses, armature's arm of force, the polarization magnetomotive force, the permanent magnets' reluctances, the stiffness of the feedback rod, the stiffness of the spring tube, the flow coefficient, the width of deflector, the width of first jet, the width of receiver, the width of shunt wedge, and the length from first jet to the deflector, impact the control accuracy.…”