Structural characteristics and working principle of ATOS servo valve

Introduction: ATOS servo valve mainly refers to electro-hydraulic servo valve, which outputs modulated flow and pressure after receiving electrical analog signals. It is both an electro-hydraulic conversion component and a power amplification component, capable of converting low-power weak electrical input signals into high-power hydraulic energy (flow and pressure) output.

ATOS servo valve
When the ATOS servo valve is activated, the baffle moves to the right, which enhances the throttling effect of the right nozzle, reduces the flow rate, and increases the back pressure on the right side; At the same time, the throttling effect of the left nozzle decreases, the flow rate increases, and the left back pressure decreases. The force at both ends of the valve core is unbalanced, causing the valve core to move to the left. High pressure oil flows from S to C2 and is delivered to the load. The load return oil flows through the return port C1 and enters the oil tank. The displacement of the spool is proportional to the input current of the torque motor, and the hydraulic pressure acting on the spool is balanced with the spring force. Therefore, in the equilibrium state, the differential current of the torque motor is proportional to the displacement of the spool. If the input current is reversed, the flow rate is also reversed. The table shows the classification of servo valves.
ATOS servo valves are mainly used as actuators in electrical hydraulic servo systems (see hydraulic servo systems). In servo systems, hydraulic actuators have the characteristics of good speed, high output power per unit weight, smooth transmission, and strong resistance to force compared to electrical and pneumatic actuators. On the other hand, electrical components are often used in servo systems to transmit signals and correct characteristics. Therefore, modern high-performance servo systems also use electro-hydraulic methods, and servo valves are essential components of such systems.
ATOS servo valves have a complex structure, high cost, and high requirements for oil quality and cleanliness. New types of servo valves are attempting to overcome these drawbacks, such as servo valves that utilize electrostrictive elements to greatly simplify their structure. Another direction is to develop special working oils (such as electrical viscous oils). This type of working oil can change its viscosity coefficient under the action of electromagnetic force. By utilizing this property, oil flow can be directly controlled through electrical signals.
The ATOS servo valve belongs to a two-stage valve. The first stage is a nozzle baffle plate, which is controlled by a control signal to regulate its outlet pressure. The second stage is a slide valve, which controls the pressure from the control stage to the brake cylinder. When there is no signal, due to the effect of the oil pressure at the outlet of the pressure nozzle, the servo valve baffle is pressed against the return oil nozzle. At this time, the oil pressure at the pressure port acts on the spool valve core, directly connecting the brake port with the metering oil port. The pressure at the brake port is equal to the metering oil pressure controlled by the pilot. When the wheel angular velocity detects a deviation between the sliding speed and the reference sliding speed, the torque motor receives a deviation electrical signal. At this time, the torque motor drives the gear plate to deflect towards the pressure nozzle, causing the oil pressure acting on the upper end of the spool to decrease. Under the action of the oil pressure at the lower end of the spool, the spool moves upward, closing the metering pressure oil port. This will cause the control port pressure to decrease. When the control port pressure drops to a certain value, there is corresponding braking pressure.
ATOS servo valve mainly refers to electro-hydraulic servo valve, which outputs modulated flow and pressure after receiving electrical analog signals. It is both an electro-hydraulic conversion component and a power amplification component, capable of converting low-power weak electrical input signals into high-power hydraulic energy (flow and pressure) output.