Fig. 3 Comparison of in-cylinder cycle (effect of total electronic control)
In the starting mode, the governor is disconnected, the timing of the fuel injection, of the exhaust valve and of the starting valve is returned to the preset value. The nozzle angle of the VG turbocharger, the scavenging air swirl guide blade angle, the feed rate of lubrication oil and the quantity of cooling water are also fixed. After the engine is started, and when the engine speed exceeds the set value, the mode is automatically switched to the map control mode, and the valve opening/closing timing according to the engine speed and the torque, and the set value of each system are calculated by the three-dimensional map. In the vicinity of the mode switching boundary, the control becomes unstable if the engine speed is fluctuated. So, some gap of the switching point is set between on the increasing side and on the decreasing side of the engine speed to provide the hysteresis characteristic.
Table 2 List of controller commands
3. Development of electronic controlled hydraulic-driven fuel injection system and exhaust valve system
As described above, to satisfy the high efficiency and low pollution at each operational condition, the sophistication of the fuel control function is important. The conditions for fuel injection control include (a) under the appropriate in-cylinder air condition, (b) at the appropriate timing, (c) with appropriate quantity, (d) in a short time and (e) in an easily-combustible atomized condition. In this study, the fuel injection system of the electronically controlled hydraulic driven type to satisfy these requests are developed.
3.1 Possibility of accumulator and control valve type injection system
For the fuel injection system to cope with the requests for further lower NOx and lower fuel consumption in future, the more sophisticated control of the injection rate will be required. For the control of the injection process to optimize the combustion, the three-dimensional control according to the data at each crank angle is requested.
