Difference between electro hydraulic servo valve and proportional servo valve

Introduction of ATOS proportional valve

——Atos proportional valve, also known as ATOS electro-hydraulic proportional valve, is an electro-hydraulic control element between on-off control and servo control. According to the electric signal, it can control the pressure, flow and direction of the hydraulic system continuously and proportionally, and can prevent the hydraulic impact. Because of its structure design, process performance and price are between on-off control element and servo control, it has been widely used in recent years. The electro-hydraulic proportional valve is that the input voltage signal of proportional electromagnet in the valve generates corresponding action, which makes the valve core of the working valve produce displacement and the size of the valve port change. The spool displacement can also be fed back in the form of mechanical, hydraulic or electrical.

——The electro-hydraulic proportional valve has many advantages, such as various forms, easy to form, using electrical and computer to control various electro-hydraulic systems, high control accuracy, flexible installation and use, strong anti pollution ability and other advantages, so its application field is increasingly widened. In recent years, R & D and production of plug-in proportional valve and proportional multi-channel valve fully consider the use characteristics of construction machinery, with the functions of pilot control, load sensing and pressure compensation. It is of great significance to improve the overall skill level of mobile hydraulic machinery. In particular, the electric control pilot operation, wireless remote control and wired remote control operation show a good application prospect.

——The types and forms of electro-hydraulic proportional valve of construction machinery include proportional flow valve, proportional pressure valve and proportional directional valve. According to the characteristics of hydraulic operation of construction machinery, there are two main types of electro-hydraulic proportional valves: one is screw cartridge proportional valve, the other is spool proportional valve. The screw cartridge proportional valve is a component on which the solenoid proportional cartridge is fixed on the oil circuit manifold block by screw thread. The screw cartridge valve has the characteristics of flexible application, saving pipeline and low cost. In recent years, it is more and more widely used in construction machinery. The commonly used spiral cartridge proportional valve has two-way, three-way, four-way and multi-way forms. The two-way proportional valve is the main proportional throttle valve, which often forms a composite valve together with other components to control the flow and pressure; the three-way proportional valve main proportional reducing valve is also a more widely used proportional valve in the mobile mechanical hydraulic system, which mainly operates the pilot oil circuit of the hydraulically operated multi-channel valve. The three-way proportional pressure reducing valve can replace the traditional manual pressure reducing pilot valve, which has more maneuverability and higher control precision than manual pilot valve.

——The four-way or multi-way spiral cartridge proportional valve can control the working device independently. Slide valve type proportional valve, also known as distribution valve, is one of the basic components of the mobile mechanical hydraulic system, which can realize the direction and flow regulation of the composite valve. The electro-hydraulic slide valve type proportional multi-channel valve is an ideal electro-hydraulic conversion control element. It saves the basic function of the manual multi-channel valve, and increases the control means such as position electric feedback proportional servo operation and load sensing. It is an updated product of distribution valve of construction machinery. Due to the consideration of manufacturing cost and the low requirement of control precision of construction machinery, the displacement sensor is not equipped in the proportional multi-channel valve, which has the function of electronic detection and error correction. The displacement of the valve core is easily affected by the pressure fluctuation caused by the load change, so it is necessary to ensure the completion of the operation in the process of operation. The influence of external interference should be paid more attention to during the operation of electronic control and remote control. In recent years, with the development of electronic technology, more and more displacement sensors such as LDVT are used to detect the position of valve core, so as to realize closed-loop control of valve core displacement. This highly integrated proportional valve is composed of electromagnetic proportional valve, position feedback sensor, driving amplifier and other electronic circuits. It has a certain correction effect. It can effectively overcome the shortcomings of general proportional valve and improve the control accuracy.

——The load sensing and pressure compensation technique of electro-hydraulic proportional multi-channel valve can save energy, reduce oil temperature and improve control accuracy. At the same time, the synchronous action of several executive elements does not interfere with each other. Now load sensing and pressure compensation techniques are used in engineering machinery. Load sensing and pressure compensation is a very similar concept. Both of them use the pressure change caused by load change to adjust the pressure and flow of pump or valve to meet the working requirements of the system. Load sensing for the quantitative pump system is to lead the load pressure load sensing oil circuit to the remote pressure regulating relief valve. When the load is small, the setting pressure of the relief valve is also small; when the load is large, the setting pressure is also large, but there is always a certain overflow loss. The variable displacement pump system introduces the load sensing oil circuit into the variable pump mechanism, so that the pump output pressure increases with the increase of the load pressure (always a small fixed pressure difference), so that the pump output flow is equal to the actual demand flow of the system, without overflow loss, and energy saving is realized. Pressure compensation is a guarantee measure to improve valve holding performance. The load pressure behind the valve port is introduced into the pressure compensation valve. The pressure compensation valve adjusts the pressure in front of the valve port to make the pressure difference between the front and the back of the valve port as a constant value. In this way, the flow rate of the throttle port flow through the valve port is only related to the opening of the valve port, and is not affected by the load pressure.

——The technical progress of pilot control of electro-hydraulic proportional valve and remote control electro-hydraulic proportional valve and other special devices makes the electrical control of various systems such as gear, steering, braking and working devices of construction vehicles come true. In general, the displacement output mechanism can be completed by using the similar proportional servo control manual multi-channel valve driver. Electrical operation with fast response, cloth