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Analysis and Solution of Malfunction of Marine Hydraulic Valve
With the continuous development and improvement of ship automation technology, hydraulic control remote control valves are more and more widely used in ships. The main advantage of the valve driven by the hydrodynamic unit lies in the simple structure, compactness and small volume; the transmission is stable and reliable; the larger output torque can be obtained; one or several power operations can still be performed with the accumulator in case of a sudden power interruption , Which is important for automatic emergency shut-off valve and wellhead discharge valve. Valve hydraulic device hydraulic circuit is mainly composed of power hydraulic source, control valve and actuator three parts, and these valve hydraulic circuit with other hydraulic equipment in parallel or in series to form a hydraulic system control circuit, that is, modern marine hydraulic The system is generally composed of a number of hydraulic circuits, both close links between the circuits, but also relatively independent, constitute a more complex, so there will often appear on the action of mutual interference and malfunction. Occurrence of interference or misoperation often leads to large faults or accidents, which may endanger the safety of the ship. One-way valve is one of the simplest and most effective hydraulic components in circuit anti-interference. It is very important to develop a one-way valve with simple structure and convenient installation to install one-way valve on the existing hydraulic system. 1 Phenomenon and Analysis of the reasons Marine hydraulic system, the hydraulic machine and hydraulic cylinder hydraulic system by the whole ship to provide power source, the hydraulic machine and hydraulic cylinder have their own control circuit, the control circuit consists of basic hydraulic components, such as electromagnetic commutation Valves, throttle, relief valve and so on. Hydraulic system due to the loop and hydraulic components of the quality or functional characteristics of different reasons, the hydraulic system in practice often have mutual interference or malfunction. Take a marine hydraulic system to produce misoperation as an example (see Figure 1), the figure 1 and 2 ball valve cylinder and No. 1 and No. 2 hydraulic machine in parallel, ball valve cylinder φ32mm caliber small tank by two Four-way solenoid valve to control the switching oil, so that the action of the cylinder, the control is simple, rapid manipulation; hydraulic machine φ80mm large diameter cylinder, controlled by the three-way valve switching circuit, the hydraulic machine action. Figure 1 and 2 hydraulic machine or pressure relief unloading pressure generated by the reservoir will cause a sudden increase in pressure back to the oil pressure exceeds P, the ball valve cylinder movement or movement trend, and the ball valve operating torque than Small, easy to cause valve malfunction; hydraulic solenoid valve for the spool-type O-type function, the median there is a certain amount of internal leakage, such as the standard GB / T13852 in the O-type three-way four-way valve leakage The maximum amount of 130ml / min. From P to A, P to B, A to T, B to T are the amount of leakage, but the amount of different, P to A and P to B is difficult to equal the amount of leakage, so that leakage of hydraulic oil through the pipeline into the 1 No. 2 and hydraulic cylinder, can lead to a fuel tank chamber energy accumulation, so that the hydraulic machine drift, causing hydraulic machine driven valve action. In addition, the hydraulic machine driven by the sea valve or butterfly valve, the load pressure can also cause valve malfunction. Figure 1 Local principle of a ship hydraulic system 2 Countermeasures and Measures 2.1 Improvement measures of ball valve malfunction The ball valve only has two positions on and off and the control valve is a two-position electromagnetic reversing valve. To eliminate the pressure fluctuation of the oil return pipe Impact on the impact of the cylinder. One of the improvement measures is to install a one-way valve on the T port of the ball valve (see Figure 2) to improve the independence and anti-interference ability of the hydraulic remote control device relative to the system. However, due to the layout and spatial relationship of the hydraulic piping on the ship, the standard one-way valve on the market can not be installed and the pipeline has been completed with string oil. It is difficult to rearrange the pipeline construction. Figure 2 Improved hydraulic schematic diagram To this end, the design of a pipe-type check valve (see Figure 3), combined with marine standard CB356 fittings size, the hydraulic check valve components placed in the pipe fittings, the use of tapered valve head , The interface is a standard hydraulic pipe joints, but with hydraulic check valve function, marine hydraulic system has a certain versatility. According to the position of the hydraulic remote control device in the system, it does not affect the original installation interface and space, and the pipe joint with the check valve is installed in the oil inlet pipe or the oil return pipe of the hydraulic remote control equipment cylinder. It can be either a termination type or an intermediate type. The check valve is convenient to install and compact in structure, and can be applied not only to the improvement of the original marine hydraulic system control pipeline, but also to the newly designed hydraulic remote control valve equipment control system to improve the anti-interference of the hydraulic remote control valve system ability. Figure 3 tube-type check valve structure 2.2 hydraulic machine malfunction action measures to improve one, according to the internal leakage is caused by hydraulic machine malfunction the main reason, so long as the electromagnetic valve to eliminate the internal leakage, can prevent the hydraulic cylinder drifts . Domestic leakage-free electromagnetic valve to seldom, the cut-off solenoid valve has been abroad, but not many, such as the Harvard VBVP type, the internal seat for the cone, the figure can be directly in Figure 1 O-type three-way valve replaced by the median cut-off three four-way solenoid valve. However, the higher end of the directional valve, the general slide valve is more than 10 times the price. Of course, economy must be based on a safe, applicable and reliable economy. Not only the price of the product, but also give priority to its function and quality, as well as the cost of installing maintenance and other accessories. Measure two, install liquid-controlled one-way valve between the liquid cylinder and the changeover valve (as shown in Fig. 2), should change the median function O type of three-position four-way directional valve into the intermediate function Y type, thus form The typical hydraulic lock circuit (see Figure 4), the use of pilot-operated check valve return valve its central position should not be used O-type, and should be used H or Y-type function valve, so that when the median , The control pressure of the pilot operated check valve is immediately released, the check valve is immediately closed, the piston motion of the hydraulic cylinder is stopped, and the interference of the load changes can be stood up. Figure 4 Typical Hydraulic Lock Circuit The pilot operated check valve is a superpositioned pilot operated check valve (Figure 5). This is also an improvement over the existing marine hydraulic system that closes both ports for a leak-free seal. Flow from A1 to A2 or B1 to B2 free circulation, the reverse is cut off, such as from A1 to A2, the pressure oil on the spool, the spool moves to the right to open the valve head to leave the valve seat, one-way valve is When the control oil is on, oil can flow from B2 to B1, pressure is relieved in chamber B1, and the check valve opens. In order to ensure that the two check valves in the valve when the valve can be reliably closed, the valve A1, B1 port and return line connectivity. So that the hydraulic cylinder relatively closed two chambers, locking the location of the driven valve to prevent valve malfunction. Figure 5 superimposed pilot check valve structure (1 spool, 2 check valve) 3 Conclusion To sum up, marine remote control valve control loop to increase the check valve and pilot check valve to prevent the implementation of the liquid Device malfunction is the easiest and most effective method. In the design of hydraulic system, it is necessary to carry out effective logical integration of each independent subsystems, and to pre-determine and evaluate the possible failure modes. [2], take effective technology to avoid, effectively improve the system's safety, reliability, so as to ensure the safety of the ship.