The actuator as a power device, not only been widely used in various valve drive control, but also being more user applications in almost any need power-driven parts. If the words of the type of actuator drive device can be divided into three categories of electric actuators, pneumatic actuators and electro-hydraulic actuators.
Most used electric and pneumatic actuators, the reason for the small size and easy-to-use electric actuators can achieve modulating control, pneumatic actuators simple structure in the gas source, but they also have not overcome its own shortcomings , such as electric actuators to achieve large driving force is difficult, and there is life and maintenance issues; pneumatic actuators stability and control accuracy is not high.
Electro-hydraulic actuators (including high-precision electro-hydraulic servo control actuators) can easily achieve a large driving force control, high-precision adjustment control and fast switching control, then why is this drive applications much? The main reason is the electro-hydraulic actuator often requires supporting the use of a hydraulic station or with a servo control system resulting in bulky, often there are problems such as leakage, and high cost (energy consumption and maintenance costs). Thus only a few require a large driving force or high-precision adjustment control before use.
A new production by the United States KOSO REXA integrated electro-hydraulic actuator has entered the Chinese market, and in many areas has been the application, REXA electro-hydraulic actuator is an intelligent machine, electrical, hydraulic actuator integration, It has two series Xpac and Mpac, of which The Xpac An actuator is a dedicated adjusted, controlled by the microprocessor of integrated electro-hydraulic actuators. The adjustment of the performance can be compared with our common electro-hydraulic servo implementing agency. Mpac is dedicated to switch control of the electro-hydraulic actuator, excellent stability and reliability. REXA actuators because of its highly integrated design change the bulky traditional electro-hydraulic actuator shortcomings, the excellent control performance of electro-hydraulic actuator has been to ensure and improve. The following is a brief look at the composition of the the Xpac series actuators, principles and performance characteristics.
REXA actuator actuator (integrated with the hydraulic cylinder and electro-hydraulic power pack) and a control box part consists of two parts. Use actuators installed on the drive unit, control box needed remote or the nearest installation, both connected by a cable, cable including power cables, control cables and feedback cables up to 150 meters in length, convenient to achieve remote control.
The part of the core of the actuator is electrically fluid power module, which are paired by a motor, gear pump, flow valves, storage tanks, electric heaters and bypass solenoid valve (spring failure unit endemic). Five sizes B, C, 1/4D, 1/2D and D power module. These specifications of the power modules are a pressure of 2000psi (13.78Mpa) passes the oil to the hydraulic cylinder, while due to its internal pump and motor combinations produce different maximum flow and thereby causes the actuator to produce different maximum stroke speed. To obtain a greater speed can be used a plurality of power modules together method or by REXA of unique booster system. This module forms the structure not only improves the versatility to ensure the stability of the product, but also reduce the amount of spare parts inventory.
Then REXA Xpac actuators is how to achieve high performance regulator control it? Its patented flow matching (Flow Match System) system (see below) hydraulic control technology can not fail to mention here. The system allows the positioning of the internal fluid pressure of the actuator can be kept constant independent of the magnitude and direction of the external load, the actuator can be on the control signal to respond quickly, the output smoothing, so that the system of the precise operation to obtain other way is extremely difficult to achieve effects . Flow matching system allows Xpac positioning increments manner, the motor and pump only action is needed in the implementation of the operation, once the cylinder output reaches a predetermined position, the pump motor to stop working, traffic pairing system ensures Xpac situ lock system regulation tasks from pump a Mada Qi, stop or reverse the effects.
The control box includes a position control processors, power supplies, motor drives, fuse, filters, and a terminal, the location processor (PCP) consists of an 8-bit 80C52 microprocessor, a 32KB EEPROM memory for program storage, one for data stored 2KB EEPROM, a 12-bit A / D converter and a 3-key 5 display board. PCP while providing two to install the optional I / O interface board connector.
Xpac control processor (PCP) by the position control. In PCP settings automatically, set and on-site three operating mode. Adjustment operation, PCP is in automatic mode. In setting mode, the user can use the keyboard and display panel can control various parameters such as signal speed, stroke, dead set through some simple steps. In the live mode, allows using PCP keyboard manual operation.
The course of action of the actuator stroke and the signal range of the actuator according to the setting determined when, PCP fed by the external control signal converted to the target position, the current position of the actuator is determined by the feedback components is mounted on the actuator. The difference between the target position and the current position of the control deviation. If the deviation exceeds the dead (set by the user), the PCP will start the motor recalibration.
Bidirectional gear pump through two traffic pair the valve (FMV1 and FMV2 of) one either side of double-acting cylinder is pressurized, the piston moves to the left, through the A port the FMV2 pressurized, the spool in the pressure differential under the left to open the check valve, hydraulic oil can flow from port D to B from port A to E in the hydraulic flow from D under the piston moves to the left. Is shown the running direction of the piston and the load direction opposite to the case, due to the low pressure of the B, C port is almost the atmospheric pressure, then FMV2 also functions as the throttle valve so that D cavity maintaining appropriate back pressure, thus ensuring the system running smoothly. When the cylinder output reaches the specified position when the pump stops working, the two check valves are closed, and the hydraulic oil in the cylinder, the motor does not require operation can make the position of the hydraulic cylinder can be maintained.
Xpac actuator output form of linear displacement or angular displacement. Linear displacement thrust from 0.9 tons to 53 tons; angular displacement torque from 68Nm to 45194Nm sufficient to meet the most control over the requirements. Linear displacement speed varies according to the different modules and contribute 8896Nm output of up to 101mm / s; angular displacement speed is also in accordance with the different modules and contribute and 282Nm output of up to 0.55s/90 °. Deadband: 0.1%, can be used PCP adjusted between 0.1% -0.5%. The positioning accuracy of less than 0.15% of the whole trip. Linearity is less than 0.05% of the full stroke. Repeat accuracy of less than 0.10% of the whole trip. Normal operating temperature: -12 ~ 90 ℃. For some special and difficult applications, such as minimum control point set, flow characterization and water hammer suppression (double speed) and surge control the, REXA can provide optional software or hardware configuration.
With such complex control functions and excellent control characteristics REXA actuator installation is very simple and convenient. It can be very relaxing and a variety of valve supporting the use, can replace the complex servo control mechanism, and easily achieve a variety of precision control requirements. The currently REXA actuators in the power plant equipment, petrochemical, pipeline, metallurgy equipment, water treatment plants adjust the valve as well as a variety of gas-powered pipeline valve has been more and more applications.
The In In short, REXA actuator is an integrated electric ease of operation, the driving force of the hydraulic fast, and the reliability of the solid-state electronics and user configuration flexibility of operation, thereby simplifying the use of the hydraulic system, regulating the revolutionary technology of the diagnostic and maintenance this technology is worth promoting and applications.
