Learning Hydraulic Servo Valve

SERVO VALVE BASICS UNDERSTANDING
Objective: You can identify servo valve designs and requirment the device.

Activity: Check and verify to Interpret catalogue data and operational specifications.

The debate over the control of hydraulic servo-valve was interesting. But the whole debate revolves around the ability to digital control of analog servo valve control. There are other considerations in the application of hydraulic servo valves for industrial applications.

Both the hydraulic cylinders and hydraulic servo-driven actuators have limited benefits of oil in compression (in the fall of oil). For cylinders the length of the race determines the oil trapped under the compression will be, and this determines the resonance will be hydraulically. A figure of merit than the resonance of not less than 200 rad / sec for a stable servant.

Hydraulic resonance = square root (2B ^ Dm 2/Jt Ve)
where B = compressibility = lb / in ^ 2
Dm = Motor displacement = ^ 3/rad
Jt = total inertia of the motor = lb-in-sec ^ 2
Ve = volume of oil under compression in ^ 3 =

To rotary actuators in which the valve of the servo is directly connected to the engine through a manifold, can hold around 60 Hz or more without a load on the engine. Most of the hydraulic servo can not bear any lateral load on the bearings in the end, the motor shaft. Therefore, a coupling device such as a Thomas joints needed to deviation from the crankshaft to minimize the load shaft. These links are much larger inertia inertia of the crankshaft. This requirement reflects the load inertia of the machine is connected to the engine also reduces the hydraulic resonance. The result of this tax, yet reduces the bandwidth of servo-hydraulic machine industry for about 15 to 20 Hz

In general, if a servo-drive is a requirement which he was very torquey power is not enough torque, the hydraulic servo-course. The unity of the criteria for sizing hydraulic servos found resonance hydraulic high enough. The servo-valve is a 2-stage device. The output stage is the placement of the coil of the motor. The input stage is one of a range torque electric motor and a very high impedance which must be accompanied in the servo valve controller. The servo valve amplifier can be designed in house if you know what you do or suppliers capable of this amp