1、 Marine hydraulic motor Analysis of current situation of model selection methods
The mechanical equipment on the main deck of a ship plays an extremely important role in the overall performance index of the ship. For example, the mechanical equipment for docking the ship directly affects the safety reliability, safety performance and speed of docking the ship. The cargo lifting machinery and equipment directly affect the working efficiency of cargo handling; Mechanical equipment on the main deck, such as windlass and winch, have a very important direct impact on the use of ships. This kind of main deck mechanical equipment is usually driven by hydraulic system, and the executive parts are basically Hydraulic motor The hydraulic motor has the advantages of large torque, large power volume ratio, stable operation, stepless speed change, good braking performance, and the corresponding overvoltage protection function. According to the difference of ship type and tonnage, the design concept of hydraulic system and the selection of hydraulic motor are not the same. There are many research conclusions and operational practicalities in the design concept and improvement of hydraulic system, such as safety reliability research, energy conservation research, etc. When the hydraulic system is similar, the hydraulic motor is used as the executive component. Scientific and reasonable selection of hydraulic motor is very important to reduce system energy consumption, reduce noise, improve system efficiency and ensure system reliability. The basic parameters of hydraulic motor include working pressure, system flow, displacement, output power, etc. Hydraulic motor selection At this stage, the required output power is usually estimated, and then the torque of the hydraulic motor required for reverse propulsion is determined, and then the displacement and speed ratio of the required hydraulic motor are determined according to the key working conditions (such as the speed of the maximum, minimum and slow speed); It can also calculate the displacement of the hydraulic motor according to the speed ratio of the required hydraulic motor and the flow rate of the hydraulic system, and then select the model and specification according to the displacement, consult the sample, and select the hydraulic motor that meets the requirements. The basic principle of this type of hydraulic motor model selection method is relatively simple and the operation is relatively common, but intuitive estimation and selection with the help of work experience are likely to result in the mismatch between the selected hydraulic motor and key working conditions. The in-depth analysis on the selection of hydraulic motor models is relatively rare at this stage. Usually, the manufacturer gives the product parameters to the user
The selection based on product parameters is also an intuitive model selection method based on work experience. On the premise of the current model selection method of hydraulic motor, this paper proposes a new method to carry out the model selection of hydraulic motor.
2. Selection of hydraulic motor type
Generally, there are many types of hydraulic motors that meet the requirements. To select a suitable hydraulic motor, you need to be familiar with the operation occasions of various types of hydraulic motors. Hydraulic motors can be divided into gear type, vane type, plunger type, cycloid type, steel ball type, etc. According to the speed ratio and torque, it can be divided into the following types: high-speed and low torque motors. The speed ratio is above 500 r/min, and the torque range is tens to hundreds of Nm. The key types include gear high-speed vane motors and axial plunger motors. Their key advantages are high speed ratio, small moment of inertia, convenient starting, braking, speed change and reversing. The disadvantage is that the torque pulsation is relatively large Low working efficiency, small starting torque (only 60%~70% of the rated torque) and poor slow speed stability; The low speed and large torque motor has a speed ratio below 500 r/min, and a very low speed ratio to achieve a few revolutions per minute. The output torque of the low speed hydraulic motor is relatively large, and the torque range can reach thousands to tens of thousands of Nm. The key types are slow vane type, radial plunger type, internal curve type, steel ball type, cycloidal type, etc. The main characteristics of the slow speed hydraulic motor are: large displacement, large volume, low speed ratio, and it can be directly connected with the operation organization without the need for speed reduction device, which greatly simplifies the transmission mechanism and has large rotation speed pulsation. Extremely low and stable rotation speed is an important characteristic of hydraulic motor. The lower the extremely low rotation speed, the wider the application field of hydraulic motor is. Low speed high torque used in shipbuilding Piston Motors There are many kinds of hydraulic motors, such as five-star motors. To select a type of hydraulic motor with suitable working conditions, it is necessary to analyze some characteristics of a specific type of hydraulic motor and select the characteristics of a hydraulic motor with suitable working conditions.
3. On the premise of analyzing the characteristics of hydraulic motor, carry out model selection
The characteristics and application fields of various types of hydraulic motors are briefly described at the front, which is the method for selecting initial models. It can generally confirm the required hydraulic motors, but the characteristics of different hydraulic motors are different. It is necessary to analyze which hydraulic motor to choose from the characteristics of hydraulic motors. The characteristics of hydraulic motors are very harmful to their use. For example, the starting characteristics are described by starting torque and mechanical efficiency. In actual operation, a large starting torque and high mechanical efficiency are expected. In addition, there are also brake characteristics, rate pulsation characteristics, torque pulsation characteristics, and extremely low flat speed. Some types of hydraulic motor characteristics are basically obtained by means of basic theoretical analysis or ideal experiment under necessary conditions, In fact, due to many factors affecting the characteristics of hydraulic motors, there is no detailed formula to calculate the characteristics of a hydraulic motor accurately, which causes trouble in the selection of hydraulic motors. With the development trend of computer technology simulation technology, it has brought -- methods for its characteristic analysis. Low speed stability is an important index value of hydraulic motor Low speed high torque motor Especially in the important. There are many factors endangering the low speed stability of hydraulic motors, not only the structural type of hydraulic motors, such as displacement and pressure pulsation, internal friction torque characteristics, hydraulic oil leakage characteristics, but also other factors besides the hydraulic motors, such as flow pulsation of the system, load characteristics, pipeline characteristics and control methods, compressibility of hydraulic oil, viscosity of hydraulic oil, etc, All of them cause significant harm to the low speed stability of the hydraulic motor.