Servo valve is one of the core control components in hydraulic system, which is widely used in industrial automation, aerospace, construction machinery and other fields. Among them, the two-way servo valve is widely used in the control system that needs high precision and quick response because it can control the forward and backward motion of the hydraulic actuator. This paper will focus on the theme of “how to reverse the two-way servo valve” and introduce its working principle and reversing process in detail.
First, the basic structure and working principle of two-way servo valve
Bidirectional servo valve is a high-precision hydraulic control valve which can control the flow direction, pressure and flow rate of hydraulic oil according to the input electrical signal. Its interior usually consists of torque motor (or electromagnetic coil), nozzle baffle mechanism, slide valve assembly and feedback mechanism.
The working principle of servo valve is based on electromagnetic control and hydraulic amplification mechanism. When a current or voltage signal is input, the electromagnetic coil generates corresponding magnetic force to drive the baffle to move, thus changing the pressure difference between the two ends of the nozzle; The change of pressure difference further pushes the slide valve to move and changes the on-off state of the hydraulic circuit, thus controlling the running direction and speed of the actuator (such as hydraulic cylinder or hydraulic motor).
Second, the reversing principle of two-way servo valve
The so-called “reversing” means that the movement direction of hydraulic actuator (such as hydraulic cylinder) changes. By controlling the position change of the slide valve, the two-way servo valve realizes the switching of the oil inlet and outlet, thus realizing the commutation.
1. Signal input changes
When the controller sends a new control signal (for example, from a positive voltage to a negative voltage), the current direction in the electromagnetic coil changes, and the direction of the generated magnetic field also changes, which drives the deflection direction of the baffle to reverse.
2. The pressure difference drives the slide valve to move.
The change of baffle position causes the pressure difference between the two sides of the nozzle to change, pushing the slide valve to move in the opposite direction. The displacement of the slide valve changes the connection relationship of the oil circuit, so that the high-pressure oil enters the actuator from one direction and the return oil flows out from the other direction.
3. The direction of the actuator changes.
With the change of oil path direction, the rotation direction of hydraulic cylinder piston or hydraulic motor also changes, realizing commutation control.
4. Feedback adjustment ensures accuracy.
Most servo valve systems are equipped with position or force feedback devices to monitor the state of the slide valve or actuator in real time, compare the feedback signal with the input signal, and automatically adjust the output to ensure the accuracy and stability of the commutation process.
Iii. Factors affecting commutation performance
-Response speed: The dynamic response ability of the servo valve directly affects the speed and accuracy of commutation.
-Control signal accuracy: The resolution and stability of the input signal are very important for commutation control.
-Cleanliness of hydraulic oil: impurities in the oil may affect the action of the slide valve, resulting in insensitive reversing or failure.
-Temperature and pressure fluctuation: The temperature and system pressure changes in the working environment will also affect the stable reversing ability of the servo valve.
Fourth, application examples
In the numerical control machine tool, the servo valve controls the hydraulic cylinder to change direction accurately, and the workpiece is fed and retracted. In the aircraft flight control system, the servo valve controls the deflection direction of the rudder surface and realizes the flight attitude adjustment. These applications all depend on the efficient and stable reversing function of servo valve.
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To sum up, the two-way servo valve controls the direction of hydraulic oil flow through electromagnetic signals, thus realizing the reversing control of the actuator. Its characteristics of high precision and high speed response make it an indispensable key component in modern hydraulic control system. In practical application, the reasonable selection and maintenance of servo valve equipment is of great significance for improving the performance and reliability of the system.