Patent ID: 7640094
Filing Date: 2009-12-29
Classification: F02B,F02D,F02M,Y02T

Abstract:
1. A diesel engine comprising: a reentrant type cavity depressed in the top of a piston, the cavity having an upper aperture which has a shape that is narrowed down to keep a swirl within the cavity, and having a convex part which rises up formed over the center of the bottom part of the cavity; fuel injection means that inject fuel towards the cavity, an injection angle of the fuel injection means being set within a range of 140° to 165° so that fuel injected near the compression top dead center of the piston reaches the internal wall of the cavity on the outside in a radial direction from the convex part of the cavity; exhaust gas recirculation means that recirculate a part of the exhaust gas into a combustion chamber; and a control device that controls a fuel injection timing by the fuel injection means and an EGR ratio by the exhaust gas recirculation means, wherein, when an engine operating condition is in a low load region, the control device starts fuel injection by the fuel injection means within a range of 14° to 30° before a compression top dead center of the piston so that injected fuel impacts the upper aperture of the cavity and enters into the cavity, and completes the fuel injection before the compression top dead center of the piston, while the control device implements the exhaust gas recirculation by the exhaust gas recirculation means at 50% or higher of the EGR ratio so that the recirculated exhaust gas and the inlet air and fuel entered into the cavity are premixed by the swirl in the cavity, and are ignited near the compression top dead center of the piston after premixing to implement premixed combustion.