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- Direct drive servo valve (DDV) is an electro-hydraulic servo valve that uses a high-power, large stroke force motor or linear motor to directly drive the movement of the power stage spool valve core. It eliminates the complex pilot stage hydraulic amplifier (such as nozzle baffle or jet pipe mechanism) in traditional servo valves, achieving single-stage direct conversion of electrical signals to hydraulic power.
Detailed explanation of the core working principle
The core design philosophy of DDV is to simplify the structure and enhance reliability. Its working principle can be decomposed into:
1. Electrical mechanical converter (large stroke force motor)
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Composition: A specially designed high-power, high output permanent magnet force motor or voice coil motor. Its output force is sufficient to overcome the hydraulic force, friction force, and reset spring force acting on the power stage valve core.
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Function: Receive electrical signals from servo amplifiers (usually ± 10V or ± 40mA) and generate an output force proportional to the signal. This force directly acts on the power stage valve core, pushing it to move. Due to its high output force, its stroke is also sufficient to meet the full stroke motion requirements of the power level valve core.
2. Single stage hydraulic amplifier (power slide valve)
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Composition: A precision four-way slide valve (valve core and valve sleeve).
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Working process:
one
The armature of the power motor is rigidly connected to the power stage valve core (or directly integrated).
two
The input electrical signal directly controls the output force of the force motor, which directly pushes (or pulls) the valve core to move inside its valve sleeve.
three
The displacement of the valve core changes the opening and closing state of the oil port, thereby directly controlling the pressure oil flow direction and flow rate from the oil source (P) to the actuator (A, B) and the return oil (T).
four
The displacement of the valve core is usually detected in real-time by a displacement sensor (LVDT or Liner Variable Differential Transformer) and fed back to the internal electronic controller, forming an electric closed-loop position control system to ensure that the valve core position accurately follows the input command