MITICS (Mechanically Integrated Timing and Injection Control System)
BRIEF EXPLANATION OF EMISSION AND ELECTRICAL CONTROL SYSTEMMITICS (Mechanically Integrated Timing and Injection Control System)
The Mechanically Integrated Timing and Injection rate Control System (MITICS) utilizes mechanical control, in comparison with TICS systems which utilize electronic control.
MITICS is equipped with the RLD-M type governor, which contains a pre-stroke control mechanism With this, pre-stroke position (i.e., beginning of static injection) can be varied to control injection timing and injection rate (i.e., the fuel injection quantity injected from the nozzle per cam angle degree).
This enables high injection rates 1 in the low and medium speed ranges through a short Injection interval, thus contributing to higher engine torque and cleaner exhaust.
MITICS was developed in response to the demands of medium sized diesel engines for low cost low fuel consumption, high output and cleaner emissions.
High injection rates using a short injection interval.
- The speed at which the injection pump plunger rises slows as engine speed decreases and the pressure inside the injection pipe decreases. Because of this, the nozzle spray deteriorates and makes it impossible to obtain the proper fuel
- air mixture.
To obtain the proper mixture at low and medium speeds it is necessary to increase the pressure inside the injection pipes using a short injection interval.
- The left hand figure shows plunger speed and cam lift in relation to cam angle. It can be seen from the graph that plunger speed increases together with cam lift.
MITICS varies the beginning of injection position at low and medium speeds so that injection occurs when the plunger speeds increases during the latter half of cam lift (shown by the bold line). At high speeds, injection is performed when the plunger speed decreases during the first half of cam lift to prevent an excessive increase in injection pipe pressure.
This enables high pressures at low and medium speeds with a fast plunger speed. Thus, a fine fuel oil spray is injected into the cylinder from the nozzles within a short time to provide the proper mixture for combustion helping to increase torque and keep exhaust emissions clean
GOVERNOR (MODEL RLD-M)
The RLD-J type governor can be used with the MI, MITICS injection pumps, and was designed to have better control and endurance than the previous RLD type governor.
Although the basic construction is identical to that of the RLD type governor, the RLD-M type is larger to match the applicable pumps larger size.
FEATURES
1. Variable speed control governor with decreased lever reaction force
As with the previous RLD type governor, RLD-M governor control is accomplished using the speed control lever to change the fulcrum of the internal link mechanism.
Consequently, as the reaction force of the governor spring does not act directly on the speed control lever, only a very small lever reaction force is exerted on the accelerator pedal
2. Set torque characteristics through internal torque cam
At full load, the tip of the sensor lever traces the face of the torque cam to determine the full load rack position and control the full load injection quantity.
Consequently, the torque characteristics demanded by the engine can be freely set by changing the shape of the torque cam face.
3. Improved control through internal guide plate
When the speed control lever is operated, the 2nd supporting lever's pin moves along the guide plate. The floating lever connected to the pin thus moves to change the ball joint fulcrum positions.
In the intermediate to high speed ranges, the guide plate causes the floating lever to move to increase the lever ratio continuously from 1.1 (idling) 6 (full speed). This increase in the lever ratio in the intermediate to high speed range improves speed droop.
VSS (Variable Swirl System)
The Variable Swirl System (VSS) is designed to adjust the intensity of swirl by allowing or not allowing air to flow through a sub-port (or bypass) the runs in parallel with the intake port for each cylinder. The swirl intensifies when the is no air flow through the sub-port, and vice versa.
The air flow is controlled by the on-off valve at the inlet to the sub-port and the valve in turn is turned on and off by computer signals which are dependent on engine speed, load and coolant temperature. Basically, the air is cut off at low speeds to maintain high swirl and is allowed to flow at high speeds to maintain low swirl.