Abstract: An exhaust gas recirculation control device controls an exhaust gas recirculation device that includes an exhaust gas recirculation passage adapted to circulate a portion of exhaust gas of an internal combustion engine from an exhaust passage downstream of a turbine of a turbo supercharger along an exhaust flow to an intake passage upstream of a compressor of the turbo supercharger along an intake flow and downstream of an air flow meter along the intake flow, and a recirculation control valve adapted to adjust an amount of exhaust gas circulated to the intake passage. Furthermore, the exhaust gas recirculation control device includes recirculation ratio setting means adapted to set a lower target recirculation ratio for a smaller intake air amount of the internal combustion engine.

Abstract: An EGR control device includes an estimate EGR ratio calculating portion adapted to calculate an estimate EGR ratio from a fresh air flow amount at a joining portion with the EGR passage of an intake passage and an EGR gas amount passing through the EGR valve, and a joining portion EGR ratio estimating portion adapted to correct an estimate EGR ratio on the basis of a gaseous state inside the introduction passage when the EGR valve switches from a closed state to an open state, to calculate a joining portion EGR ratio being a proportion of an EGR gas amount with respect to fresh air in the joining portion.

Abstract: An EGR control device includes an estimate EGR ratio calculating portion adapted to calculate an estimate EGR ratio from a fresh air flow amount at a joining portion with the EGR passage of an intake passage and an EGR gas amount passing through the EGR valve, and a joining portion EGR ratio estimating portion adapted to correct an estimate EGR ratio on the basis of a gaseous state inside the introduction passage when the EGR valve switches from a closed state to an open state, to calculate a joining portion EGR ratio being a proportion of an EGR gas amount with respect to fresh air in the joining portion.

Abstract: An exhaust gas recirculation control device controls an exhaust gas recirculation device that includes an exhaust gas recirculation passage adapted to circulate a portion of exhaust gas of an internal combustion engine from an exhaust passage downstream of a turbine of a turbo supercharger along an exhaust flow to an intake passage upstream of a compressor of the turbo supercharger along an intake flow and downstream of an air flow meter along the intake flow, and a recirculation control valve adapted to adjust an amount of exhaust gas circulated to the intake passage. Furthermore, the exhaust gas recirculation control device includes recirculation ratio setting means adapted to set a lower target recirculation ratio for a smaller intake air amount of the internal combustion engine.

Abstract: An optical disc comprising a disc having a signal- recording layer, wherein a treated layer having a surface electric resistance of from 1.times.10.sup.3 to 1.times.10.sup.13 .OMEGA. is formed on the signal-recording layer, and the surface of the treated layer is subjected to electrophotographic printing. The optical disc can be desirably used as an optical disc, in which digital signals can be recorded, reproduced or erased, such as a digital audio disc, such as a compact disc, a video disc, or a CD-ROM.