Abstract: Based on entry/exit pressures of a compressor detected by atmospheric/boost pressure sensors, a pressure ratio of compressor is calculated. Based on mass flow rate and entry temperature of intake air detected by intake air flow-rate/temperature sensors and entry pressure, a volumetric flow rate of intake air is calculated in environmental condition at a detection time using gas state equation, and is corrected into a volumetric flow rate under standard environmental condition thorough multiplication by a corrective coefficient based on entry temperature of intake air. Based on the corrected value and the calculated pressure ratio, a rotational frequency of compressor under standard environmental condition is read out in light of operating characteristic diagram for the compressor.

Abstract: Based on entry/exit pressures of compressor 2a detected by atmospheric/boost pressure sensors 13 and 14, pressure ratio of compressor is calculated. Based on mass flow rate and entry temperature of intake air 4 detected by intake air flow-rate/temperature sensors 15 and 16 and entry pressure, volumetric flow rate of intake air is calculated in environmental condition at detection time using gas state equation, and is corrected into volumetric flow rate under standard environmental condition thorough multiplication by corrective coefficient based on entry temperature of intake air. Based on corrected value and calculated pressure ratio, rotational frequency of compressor under standard environmental condition is read out in light of operating characteristic diagram for compressor.

Abstract: A compression piston ring capable of reducing excessive surface pressure at a gap and adjacent portion thereto during engine operation, and capable of being produced at a low cost. The compression piston ring has generally circular shape without any notched portion. The compression piston ring has a dimensional requirements in that d1/a1 ranges from 40 to 60, and d1/h1 ranges from 30 to 55, in which d1 represents an inner diameter of the piston ring, a1 represents a radial length between inner and outer peripheral surfaces of the piston ring, and h1 represents an axial length of the outer peripheral surface. The compression piston ring is particularly available as a first compression piston ring for a supercharging type diesel engine providing high engine pressure.

Abstract: A cylinder liner and a piston ring adapted to be combined therewith in an internal combustion engine are provided that have excellent abrasion resistance, where iron oxide film is formed at least on a part of the inner circumferential surface of the cylinder liner, and metallic nitride film is formed at least on a sliding surface of the piston ring sliding along the cylinder liner.

Abstract: A compression piston ring capable of reducing excessive surface pressure at a gap and adjacent portion thereto during engine operation, and capable of being produced at a low cost. The compression piston ring has generally circular shape without any notched portion. The compression piston ring has a dimensional requirements in that d1/a1 ranges from 40 to 60, and d1/h1 ranges from 30 to 55, in which d1 represents an inner diameter of the piston ring, a1 represents a radial length between inner and outer peripheral surfaces of the piston ring, and h1 represents an axial length of the outer peripheral surface. The compression piston ring is particularly available as a first compression piston ring for a supercharging type diesel engine providing high engine pressure.