VICKERS hydraulic servo valve

VICKERS hydraulic servo valve

EATON VICKERS is a hydraulic brand under the Fluid Power division of Eaton Group. Its main products include hydraulic pumps, motors, hydrostatic transmission products, valves, steering gears, cylinders, power units, accessories, filters, etc. VICKERS is a hydraulic brand under the Fluid Power Division of Eaton Group, whose main products include hydraulic pumps, motors, cylinders, hydraulic valves, etc. Eaton's fluid power products are widely used, including earthmoving machinery, agriculture, construction, aviation, mining, forestry, public facilities, and material handling. Eaton is a diversified industrial product manufacturer with a reputation for technology and reliable quality in the global industrial sector. We have 55000 employees in over 125 countries across 6 continents worldwide. The annual sales revenue is 9.8 billion US dollars. The products cover various fields such as automobiles, trucks, heavy equipment, residential areas, telecommunications and data transmission, industrial equipment and public facilities, commercial institutions and government agencies, as well as sports and entertainment.

Hydraulic 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 In the electro-hydraulic servo system, it connects the electrical part with the hydraulic part to achieve the conversion of electro-hydraulic signals and hydraulic amplification The electro-hydraulic servo valve is the core of the electro-hydraulic servo system control.

Hydraulic servo is an actuator that converts electrical signals into high-power pressure or flow pressure signals for output in a servo system. It is an electro-hydraulic conversion and power amplification component. Servo valves have high sensitivity and good speed, and can convert small electrical signals (such as 10 milliamps) into large hydraulic power (such as tens of horsepower or more), which can drive various types of loads. In the past, hydraulic amplification devices such as nozzle baffle valves, jet pipes, or slide valve servo motors were included in the scope of servo valves. Since the 1970s, servo valves generally only refer to electro-hydraulic servo valves.

A typical servo valve consists of a permanent magnet torque motor, nozzle, baffle, valve core, valve sleeve, and control chamber (see figure). When the input coil is connected to the current servo valve

When the baffle moves to the right, the throttling effect of the nozzle on the right is strengthened, the flow rate decreases, and the back pressure on the right increases; 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.

Servo valves are mainly used as actuating components in electro-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 anti-interference ability 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. Servo valves have complex structures, high costs, 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

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