In order to improve the maneuverability of ships and meet the needs of various operating conditions such as low-speed navigation in narrow waterways and berthing away from docks, side thrusters have been widely used in modern large-scale ocean-going transport ships, port operating ships, offshore engineering ships, offshore oil service ships (three-purpose ships) and other ships with single handle operation (ioystiek). Dynamic Positioning System (Dp) enables the ship to be positioned at a preset position. Relatively speaking, due to the short service time of ship-side thrusters, it is easy to neglect management and lead to various failures. Therefore, according to my long-term practical experience in the use and management of ship thrusters, the following discussion is put forward.
Keywords: ship; Side pusher; Use and management
1, ship propeller
Ship propeller is a tool to provide thrust to the ship. Its function is to convert the power provided by the ship power plant into thrust and push the ship forward. A mechanical device that propels a ship forward. It is an energy converter that converts natural force, manpower or mechanical energy into ship thrust. Propeller can be divided into active type and reactive type according to the mode of action. Fibers and sails (see sailboats) driven by human power or wind are active, while paddles, paddles, paddles, water jet propellers and propellers are passive. Modern transport ships mostly use reactive propellers, among which propellers are the most widely used.
/kloc-in the 1930 s, former Swedish officer John? Ericsson and British engineer Francis? Roland? Mr. and Mrs. Smith both designed ships propelled by propellers. They got inspiration from the ancient Greeks. The ancient Greeks used the Archimedes screw, a device similar to a bottle opener, to lift water. Roland? Smith's experiment succeeded. He built a boat with a wooden propeller, and a part of the propeller suddenly broke. Strangely, the wooden propeller became shorter, but the boat went faster. This shows that the shortened wooden propeller has higher propulsion efficiency.
Inspired by this, brunell engineers used propellers on the "Great Britain" he designed and built. The propeller-propelled ship crossed the Atlantic for the first time in 1845. Propeller propeller is widely used in ships.
Ship propeller is a kind of water propeller, and its principle is that when the propeller rotates, the blades push a lot of water backward continuously, which produces a forward force on the blades, that is, propulsion. The propeller blade is like a short wing, and the forward component of hydrodynamic force on the blade constitutes the pulling force, that is, the ship propulsion.
On the basis of ordinary propellers, in order to improve the performance, better adapt to various navigation conditions and make full use of the main engine power, the following special propellers have been developed. ① Adjustable pitch propeller: referred to as adjustable pitch propeller for short, the pitch can be adjusted as needed to give full play to the power of the main engine; In order to improve the propulsion efficiency, the rotation direction of the main engine cannot be changed when the ship retreats. By mechanically or hydraulically manipulating the mechanism in the hub to rotate each blade, the pitch can be adjusted. Pitch propeller has good adaptability to the change of blade load and is widely used in tugboats and fishing boats. For general transport ships, the ship-engine-propeller can be in a good' matching' state. However, the hub diameter of pitch propeller is much larger than that of ordinary propeller, and the blade root section is thick and narrow. Under normal operating conditions, its efficiency is lower than that of ordinary propeller, and it is expensive and complicated to maintain. (2) Ducted propeller: A circular duct with airfoil section is added to the outer edge of ordinary propeller. This catheter is also called Coriolis catheter. The conduit is fixedly connected with the hull, which is called a fixed conduit. The conduit is connected with the rotating rudder post and also serves as a rudder blade, which is called a rotatable conduit. The duct can improve the propeller's propulsion efficiency, because the velocity in the duct is high and the pressure is low, and the pressure difference inside and outside the duct forms additional thrust on the pipe wall. The gap between the duct and the propeller blade is very small, which limits the flow loss around the blade tip; The duct can reduce the wake contraction behind the propeller and reduce the energy loss. However, the reversing performance of ducted propeller is poor. The fixed duct propeller increases the turning diameter of the ship, and the rotatable duct can improve the turning performance of the ship. Ducted propellers are mainly used to propel ships. ③ Tandem propellers: Two or three ordinary propellers are installed on the same shaft and rotate in the same direction and at the same speed. Under the condition of limited propeller diameter, the blade area can be increased and more power can be absorbed, which is beneficial to vibration reduction or cavitation avoidance. Tandem propellers are heavier in weight, and the propeller shaft protrudes longer, which increases the difficulty of arrangement and installation and is less used. (4) Counter-rotating propellers: Two ordinary propellers are installed on concentric inner and outer shafts in tandem and rotate in opposite directions at the same speed. Because it can reduce the wake rotation loss, the efficiency is slightly higher than that of a single propeller, but its shafting structure is complex and has not been applied to large ships. ⑤ Straight blade propeller: It consists of 4 ~ 8 vertical blades. The upper part of the straight-bladed propeller is disc-shaped, the blades are evenly installed along the periphery of the disc, and the bottom of the disc is flush with the hull plate. When the disc rotates, the blades rotate around the main shaft and swing around their own vertical shafting, thus generating thrust in different directions. Therefore, the ship can rotate in the same place, without steering with the rudder, and there is no need to change the steering of the main engine when the ship retreats. However, due to the complex mechanism, high price and easy damage of blades, it is only used in a few port ships or ships with special requirements for maneuverability.
2, the classification of ship lateral thrust device
According to the installation position of the side thruster on the ship, the side thruster is installed on the bow of the ship, which is called the bow side thruster. Side thruster is installed in the hull, which is called stern side thruster. Number of side thrusters: one side thruster, mostly on the ship's side; Two side thrusters, one crisp and one silent, or two along the ship; Three side thrusters, two on the ship's side and one on the ship's side; Four side pushes, two simply, two vividly. According to the driving mode of the lateral thruster, it can be divided into electrically driven lateral thrusters. Diesel-driven side thrusters can be divided into fixed pitch thrusters and variable pitch thrusters according to whether the pitch is variable or not. The side thrusters of modern ships are mostly adjustable propellers, which are flexible to operate. It is only necessary to change the pitch angle of the blade to change the left and right direction and adjust the lateral force. In this paper, the side thruster is discussed according to two classification characteristics: whether the pitch propeller is variable and the driving mode. This paper mainly discusses the electrically driven fixed-distance side thruster and the electrically driven variable-distance side thruster. The side thruster driven by diesel engine is not discussed and analyzed here.
3, working characteristics and fault analysis
3. 1 electric pitch propeller
The lateral propeller is driven by a motor and transmits the propeller action through a gear box. It is characterized by fixed pitch and step-by-step speed change forward and backward. Simple structure and convenient management. Main faults:
(1) Abnormal bearing noise during operation
Cause: Bearing damage: There is no oil in the gearbox and no air in the system.
(2) Sudden stop during operation
Cause: The thermal protection link plays a role (high temperature protection, thermal protection relay action) due to power failure or blown fuse.
(3) can't reverse, can't change speed.
Cause: The braking device is not loosened, and the DC speed regulation is invalid (contactor, time relay and other components are faulty).
3.2 electric variable pitch propeller side propeller
The lateral propeller is controlled by bridge remote control/local start, motor power output and hydraulic pitch control. The device consists of five basic components: pitch-adjustable propeller, transmission shaft, pitch-adjustable mechanism, hydraulic system and control system.
The adjustable pitch propeller comprises rotatable blades, propeller blades and a blade rotating mechanism installed in the propeller blades for rotating the blades. The blade rotating mechanism of pitch control propeller is a mechanism that converts the reciprocating motion of power cylinder into the rotating motion of rotating blades.
The transmission shaft is connected with the vertical shaft by a motor (large motor) through a coupling, and the vertical shaft is meshed with the transmission shaft through a gear.
The pitch adjusting mechanism comprises a servo cylinder, a servo piston, an oil distributor for distributing pressure oil to the servo cylinder, a device for positioning the blades and feeding back the positions of the blades and auxiliary equipment thereof. Its main tasks are pitch adjustment, pitch stability and pitch feedback and indication.
Servo cylinder, servo piston, oil distributor for distributing pressure oil to servo cylinder, blade position positioning and feedback device and its auxiliary equipment, etc. Its main tasks are pitch adjustment, pitch stability and pitch feedback and indication.
The control system is mainly composed of console, control and indication system. Its function is to adjust the pitch to control the pitch of the propeller according to the predetermined control program, so as to obtain the required working conditions. Job characteristics: flexible operation and quick response, but complex structure and relatively high management requirements. Main faults:
(1) During the operation, the spacing between the side push plates cannot be changed or moved.
Causes: the solenoid valve is stuck or leaks oil, the safety valve jumps or leaks oil, the car works normally when it is cold, but it can't work when it is hot, which is mainly caused by the oil leakage of the distribution valve.
(2) Push to one side.
Cause: The solenoid valve is stuck, the feedback potentiometer circuit is damaged or the insulation is poor.
(3) During operation, the lateral thrust suddenly stops.
Cause: overload protection stops when the load exceeds the set value; Motor high temperature protection shutdown; The pitch limit cam stops; The filter is dirty and blocked, and the vehicle stops at low pressure.
(4) The lateral thrust failed to start.
Reason: The motors are out of phase; The power supply voltage is too low; Non-zero pitch start; Low oil pressure protection; The star-delta switching time relay failed during the start-up; There are foreign bodies in the blades (there are foreign bodies stuck underwater); Push sideways and start with load (if not used for a long time, marine life grows on the leaves.
(5) The lateral thrust is started successfully, but the vehicle can not pitch when it is cold, but can move when it is hot.
Cause: The ambient temperature is too low, and there is no heat preservation. The selected oil is not suitable for the ambient temperature, that is, the viscosity-temperature characteristics are poor.
(6) Low motor insulation
Cause: The sea breeze and seawater were sucked into the vent of the side-pushing cabin, and the cabin exhaust fan turned wrong and became an exhaust fan, and the wet drying device of the motor failed.
4. Suggestions for management
Because the ship's side thruster is large in size and underwater, how to use and manage it correctly, accurately judge the fault point and remove the fault to reduce the time of ship's suspension and docking repair, save the cost of ship maintenance and reduce the pollution to the marine environment will certainly play an important role in ensuring the safety of ship navigation and improving the operation rate.
4. 1 used for electrically driven propeller;
(1) Maintain the control box regularly;
(2) Strengthen cabin ventilation:
(3) Maintain the normal liquid level of the gear box;
(4) After repair, the gearbox exhausts when refueling;
(5) Keep the gearbox breathing freely.
4.2 For electric variable pitch propeller.
(1) Maintain the control box regularly.
(2) Keep the cabin well ventilated;
(3) Start side pushing according to the operating procedure;
(4) Clean the hydraulic oil filter regularly and release air after cleaning;
(5) Regularly test oil samples, or replace system oil in combination with dock repair;
(6) Select the appropriate oil products according to the regional operating environment temperature;
(7) Especially in winter, such as operation in Bohai Bay area, the anti-freezing and thermal insulation of the cabin should be strengthened;
(8) For ships with multiple side thrusters, due to different working conditions, one side thruster that has not been used for a long time should be operated at any time to prevent marine life from overgrowth;
(9) Regularly check the screw fastening of the small oil cylinder and potentiometer;
(10) For the side thruster controlled by resin LC, attention should be paid to the management of standby power supply (battery).
5. Conclusion
In this paper, some basic knowledge of ship propeller is analyzed theoretically, and some fault reasons of ship propeller are emphatically analyzed, and some methods and means of troubleshooting are put forward, and some views on the management of ship propeller are put forward. Due to my limited level, there may be some omissions in these opinions, and I will correct them in my future work and study.
refer to
[1] Shen Yongshan. Research on brushless DC motor and control system for propeller of twin-rotor underwater vehicle [D]: Shenyang University of Technology; In 2006
Li daijin. Research on closed-loop control of underwater thermal propulsion system [D]: Northwestern Polytechnical University; In 2006
Qian Cheng. Scheme design and maneuverability analysis of pentapod propulsion system [D]; Shanghai Jiao Tong University; In 2007