The hottest new type of intelligent electro-hydrau

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A new type of intelligent electro-hydraulic integrated actuator

actuator, as a power device, has not only been widely used in the drive and control of various valves, but also is being used by more users in almost any part that needs power drive. According to the type of actuator driving device, it can be divided into three categories: electric actuator, pneumatic actuator and electro-hydraulic actuator

at present, the electric actuator and pneumatic actuator are used most. The reason is that the electric actuator is small and easy to use, and it can realize adjustment and control. The pneumatic actuator has simple structure under the condition of air source, but they also have their own insurmountable shortcomings. For example, it is difficult for the electric actuator to achieve large driving force, and there are problems of service life and maintenance; The pneumatic actuator has the problems of low stability and control accuracy

while electro-hydraulic actuator (including high-precision electro-hydraulic servo control actuator) can easily realize large driving force control, high-precision adjustment control and fast switching control, so why is this kind of driver not widely used? The main reason is that in the past, electrohydraulic actuators often needed to use a hydraulic station or a set of servo control system, resulting in huge volume, leakage and other problems, and high use costs (energy consumption and maintenance costs). Therefore, it is only used when a few need large driving force or high-precision regulation and control

at present, a new rexa electro-hydraulic integrated actuator produced by American Koso company with low noise has entered the Chinese market and has been applied in many fields. Rexa electro-hydraulic actuator is an intelligent mechanical, electrical and hydraulic integrated actuator. It has two series of XPAC and MPAC, of which XPAC actuator is an integrated electro-hydraulic actuator specially used for regulation and controlled by microprocessor. Its regulation performance is comparable to that of our common electro-hydraulic servo actuator. MPAC is an electro-hydraulic actuator specially used for switch control, which has excellent stability and reliability. Because of its highly integrated design, rexa actuator has changed the shortcomings of the traditional electro-hydraulic actuator, which is bulky, while the excellent control performance of the electro-hydraulic actuator has been guaranteed and improved. The composition, principle and performance characteristics of XPAC series actuators are briefly introduced below

rexa actuator is mainly divided into two parts: actuator (integrated hydraulic cylinder and electro-hydraulic power components) and control box, which recommend new material products of civilian units to military users. In use, the actuator is installed on the driven device, and the control box can be installed remotely or nearby as required. The two are connected by cables, including power cables, control cables and feedback cables, with a length of up to 150 meters, which is convenient for remote control

The core of the actuator part is the electro-hydraulic power module, which is composed of motor, gear pump, flow matching valve, oil storage tank, electric heater and bypass solenoid valve (unique to spring failure unit). The power module has five specifications: B, C, 1/4D, 1/2D and D. The power modules of these specifications transmit oil to the hydraulic cylinder at the pressure of 2000psi (13.78mpa). Due to different combinations of pumps and motors inside, different maximum flow rates and thus different maximum stroke speeds of the actuator are generated. Greater speed can be achieved by combining several power modules or by using rexa's unique booster pump system. This modular structure not only improves the versatility, ensures the stability of product performance, but also reduces the inventory of spare parts

how does rexa XPAC actuator achieve high-performance regulation and control? Here, we cannot fail to mention its patented flow match system (see the figure below), the latest technology in hydraulic control. The system makes the internal fluid pressure of the actuator remain constant independent of the size and direction of the external load. The actuator can respond quickly to the control signal and output smooth and accurate operation, so that the system can achieve a positioning effect that is extremely difficult to achieve in other ways. The flow matching system allows XPAC to be positioned in an incremental manner, and the motor and pump operate only when they perform their required actions. Once the oil cylinder output reaches the predetermined position, the pump motor stops working. The flow matching system can ensure that XPAC is locked in place, and the adjustment task of the system is not affected by the start, stop or reverse rotation of the pump motor

the control box includes a position control processor, power supply, motor driver, fuse, filter and a terminal. The position processor (PCP) includes an 8-bit 80C52 microprocessor, a 32KB EEPROM memory for program storage, a 2KB EEPROM memory for data storage, a 12 bit a/d converter and a 3-key 5-bit display board. PCP also provides two connectors for installing the optional i/o interface board

xpac is controlled by the position control processor (PCP). There are three operation modes in PCP operation settings: automatic, setting and field. During the adjustment operation, PCP is in automatic mode. In the setting mode, the user can use the keyboard and display board to set various parameters such as speed, stroke, deadband controllable signal through some simple operation steps. In field mode, manual operation with PCP keyboard is allowed

the action process of the actuator is that the PCP converts the externally sent control signal into the target position according to the stroke and signal range determined during the setting of the actuator, and the current position of the actuator is measured by the feedback component installed on the actuator. The difference between the target position and the current position is the control deviation. If the deviation exceeds the dead band (set by the user), PCP will start the motor for recalibration

the two-way gear pump pressurizes either side of the double acting cylinder through one of the two flow pairing valves (fmv1 and fmv2). In order to move the piston to the left, pressurize fmv2 through port a. the valve core moves left under the action of differential pressure. Open the check valve, and the hydraulic oil can flow from port d to B, from port a to E. under the action of the oil pressure flowing out of port D, the piston moves left. It should be noted that when the running direction of the piston in the figure is opposite to the load direction, because the pressure at ports B and C is very low, almost atmospheric pressure, fmv2 also acts as a throttle valve to maintain an appropriate back pressure in chamber D, so as to ensure the smooth operation of the system. When the output of the oil cylinder reaches the specified position, the pump stops working, the two check valves are closed, and the hydraulic oil remains in the cylinder. The motor can maintain the position of the hydraulic cylinder without operation

the output form of XPAC actuator can be linear displacement or angular displacement. Linear displacement thrust from 0.9 tons to 53 tons; Angular displacement torque ranges from 68nm to 45194nm, which is sufficient to meet most control force requirements. The linear displacement speed varies according to different modules and output. For example, the maximum output of 8896nm can reach 101mm/S; The angular displacement speed is also different according to the reason why some tensile testing machines are cheap and the output. For example, when the output is 282nm, it can reach 0.55s/90 °. Dead band: 0.1%, which can be adjusted by PCP between 0.1% and 0.5%. The positioning accuracy is less than 0.15% of the full stroke. The linearity is less than 0.05% of the full stroke. The repetition accuracy is less than 0.10% of the full stroke. Normal working temperature: - 12 ~ 90 ℃. For some special and difficult applications, such as minimum control point setting, flow characteristic description, water hammer suppression (two speed) and surge control, rexa can provide optional software or hardware configurations

rexa actuator with such complex control functions and excellent control characteristics is very simple and convenient to install and use. It can be easily used with various valves, and can also replace complex servo control mechanisms to easily achieve various precision control requirements. At present, rexa actuators have been more and more used in power plant equipment, petrochemical pipelines, metallurgical equipment, water treatment plant control valves and various gas power pipeline valves

in a word, rexa actuator is a revolutionary technology that integrates the simplicity of electric operation, the fast power of hydraulic pressure, the reliability of solid-state electronics and the flexibility of user configuration and operation, thus simplifying the use, regulation, diagnosis and maintenance of hydraulic system. This technology is worthy of great promotion and application


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