F2008-06-037
The Effect of the Multiple Fuel Injections to the State of Piston Lubrication in Supercharged Diesel Engine(The Relations that Fuel Adhesion to a Cylinder and Lubrication are in a State)
The fuel injected through multiple injections in a common rail type diesel engine adheres to the cylinder wall and mixes with the lubricating oil around when the piston reaches the top dead center. There is a risk that this could result in worsening the piston lubricating conditions. The aim of this study is to verify the variations in piston lubrication when multiple injection and supercharging are used in a common rail diesel engine with floating liner which is able to measure the piston friction force. Furthermore to compare the overall amount of fuel adhering to the cylinder, the LIF method was used. The findings obtained by the above are as described below. (1) The pilot injection which occurs just before the main injection, worsens the piston lubrication conditions, because it raises the cylinder pressure just before the compression top dead center. Also the earlier pilot injection worsens the piston lubrication conditions, by causing the adhesion of fuel to the cylinder wall. (2) The post injection which is done just after the main injection, worsens the piston lubrication condition, be-cause it raises the cylinder temperature around when the piston reaches top dead center. Also the post injection which is done at the later period, worsen the piston lubrication conditions, by causing the adhesion of fuel to the cylinder wall. (3) The supercharging worsens the piston lubrication condition in the early pilot injection and post injection at the late period. (4) The results of the measurement by the LIF method show that the amount of fuel adhesion to the cylinder wall is increased, when the pilot injection was done earlier and post injection was done later. (5) By the combination of supercharging and pilot injection, the amount of fuel adhesion is decreased. However, by the combination of supercharging and post injection, the amount of fuel adhesion is increased which can be seen here by the increasing of the PMT output.
This abstract is supplemented by a PDF, which can be viewed here.
Session: Fuel Injection I