Patent ID: 8590517

Claim:
A diesel engine for a vehicle, comprising: an engine body to be mounted in the vehicle and supplied with fuel containing diesel fuel as its main component, a geometric compression ratio ε being set within a range of 12:1 to 15:1, wherein the engine body includes: an intake valve for opening and closing an intake port communicating an intake passage with a cylinder; an exhaust valve for opening and closing an exhaust port communicating an exhaust passage with the cylinder; and an exhaust gas re-circulation passage communicating the intake passage with the exhaust passage and for partially re-circulating exhaust gas to the intake passage; wherein, when the engine body is at least in an operating state with comparatively low load and low rotation speed, the exhaust valve is opened during an intake stroke so that the exhaust gas is partially introduced into the cylinder and the intake passage is choked; wherein the exhaust valve that is opened during the intake stroke is closed before the intake valve is closed in a later stage of the intake stroke; and wherein an opening area S E [mm·deg] of the exhaust valve, that is defined by a lift curve of the exhaust valve in the intake stroke, is set so that a ratio S E /S I of the opening area S E of the exhaust valve to an opening area S I [mm·deg] of the intake valve, that is defined by a lift curve of the intake valve, meets a relation of: 0.01×(15−ε)+0.02 ≦S E /S I ≦0.17, with respect to the geometric compression ratio ε of the engine body.