The Design And Study Of Electronic Control System Of Cylinder Lubricator For Marine Two-stroke Engine

In the recent years, along with the extensive application of highly supercharged long stroke marine diesel engines and the vast use of the fuel oil with high viscosity and high sulfur content, the problem encountered in the engine cylinder lubrication is concerned increasingly. The engine cylinder lubrication takes place between the high speed moving parts under high temperature and high pressure. And the interior circumstances of the cylinder is very particular: Firstly, high temperature of the work surfaces makes the viscosity of the cylinder oil lower and the oil oxidize fast. The high temperature also makes part of oil film on the surface of the cylinder vaporize. Secondly, the reciprocation of the piston in the cylinder liner makes the hydrodynamic lubrication only possible in the middle of the piston stroke, so it is difficult to achieve good lubrication between the cylinder and the piston.In the traditional cylinder lubrication system of internal combustion engines the cylinder oil injection is realized mechanically by the driving cam shaft. The design is a compromise of several factors including cylinder oil consumption, the timing of injection and exhaust pollution. The design also induces low injection pressure, rough injection timing, and the cylinder oil consumption is not adjustable with the change of engine load. The design generally considers engine safety first, and oil consumption is determined on the basis of the maximum engine load by adding a safety margin, that means the injection quantity is excessively high while engine is running at low load. Excessive cylinder oil consumption not only wastes energy, but also adds pollution to the environment, increases workload and the expense to dispose the dirt oil. At the same time, it also adds the dirt in the scavenge box and exhaust pipes, and aggravates the abrasion of the cylinder and piston rings. These may finally lead to various malfunctions.Now, electronic control is widely applied to all aspects of the diesel engine, including control of fuel oil injection, the turbocharger and valves, etc. Electronic injection of the cylinder oil has already come into use, and is popularized swiftly. In China, because of the insufficiency of work done and investment made in the relevant technique development, the level of electronic control in the cylinder oil injection area of the diesel engine is limited, so the development of electronic control in the cylinder oil injection area of the diesel engine is of great practical value.This article describes an electronic control system developed for the cylinder oil injection for two-stroke marine diesel engines. The main work done about this thesis is as follows:1. Study and put forward a control strategy of the system, including oil injection timing and the sketch map of the strategy.2. Accomplish the overall functional design of the system.3. Accomplish the hardware and the software design of functional modules of the controller according to the need of the ship and in line with the relevant regulations of China Classification Society. The FPGA technology and the ARM based intelligence collection module are used to collect and process the input signals, implement the control strategy, and send out control signals.4.Study in depth the actuator of the control system—stepping motor, and preliminarily master the use of stepping motors and learn faults possibly to occur while the stepping motor is running to inject oil.