Electro-hydraulic servo valve is the key component and interface of electro-hydraulic servo system, with high control accuracy, fast response speed, high output power, compact structure and many other advantages, has been widely used in military industry and other industrial control fields. Servo valve debugging process as the final link in the whole production cycle, its key links quality control to ensure that the servo valve dynamic and static performance, improve the stability and reliability of the work is of great significance.
1. Servo valve working principle
Electro-hydraulic servo valve is an important control element in the electro-hydraulic servo control system, plays a role in the system of electro-hydraulic conversion and power amplification, it can be a small power of the electrical signal into the valve's movement, so as to realize the hydraulic servo system actuator flow and pressure control.
Take the two-stage electro-hydraulic servo valve widely used in the engineering field as an example, the servo valve is generally composed of a torque motor, a pre-stage hydraulic amplifier and a power stage slide valve. Figures 1 and 2 show the schematic diagrams of nozzle baffle-type and biased jet-type electro-hydraulic servo valves, respectively. Torque motor by the permanent magnet, conductor, coil and spring tube, armature, feedback lever, baffle, etc., feedback lever ball inserted in the middle of the spool groove; pre-stage hydraulic amplifier by the throttle orifice, nozzle (or jet disk), return oil damper and other components.
When the coil input control current signal, electromagnetic torque, so that the armature drive its rigid connection of the baffle to produce deflection. When the pressure difference between the two nozzle chambers is changed, the valve spool is driven by the pressure difference, driving the ball movement so that the elastic feedback rod deformation, so as to apply a feedback torque to the armature assembly until this feedback torque and the electromagnetic torque of the torque motor is balanced, and the armature stays at a corresponding deflection angle. At this time, the deformation of the feedback rod causes the stopper to be partially pulled back to the neutral position, and finally the driving force of the spool is balanced with the hydraulic force, and the spool stays at the corresponding displacement, and at this time, the servo valve outputs a corresponding flow rate, realizing the control of the output flow rate by the control current [1].
2. servo valve debugging process key links and their
Control method
Servo valve as a high-precision, high-sensitivity hydraulic control components, requires better static and dynamic characteristics and stability, and the complexity of the structure of the servo valve, but also determines the refinement of the commissioning process, in order to ensure that the performance of the servo valve to meet the requirements of the need for the commissioning process of the valve affects the dynamic and static performance of the entire valve to identify the key links and control, servo valve debugging process of the key links are mainly The following points.
Oil circuit flushing
At present, the electro-hydraulic servo valves used in aerospace, in order to adapt to the aerospace model of light weight, small installation space, the demand for harsh working environment to take the integrated, compact structure design, which throttle holes, jet discs and other core components of small size, with precision micro-hole and tiny cavity structure features, as shown in Figure 3, Figure 4, the size of the general between 0.10 ~ 0.80mm; valve sleeve parts are precision deep holes and with Valve sleeve parts are precision deep holes and have oil ring groove, sealing groove structure, as shown in Figure 5; shell parts are mostly complex shaped shaped grooves, blind holes, slanted holes, stepped holes and so on.