Engine starting device

An engine starting device for starting an engine supplied with fuel by a fuel injection device and ignited by an ignition device, comprising:

• a starter generator that includes a rotor having a magnetic field and directly connected to a crankshaft of said engine, a stator having a polyphase armature coil, and a Hall sensor that detects a polarity of a magnetic pole of said rotor on the side of said stator to detect a rotational angle position of said rotor, operates as a starter motor when a driving current is supplied to said armature coil according to a detected output of said Hall sensor, and operates as a generator when said rotor is driven by said engine;
• a manual starter that is manually driven to perform cranking for starting said engine;
• a battery capacity monitoring portion that estimates a remaining capacity of a battery that supplies the driving current to said starter generator;
• a start mode switching portion that switches a start mode of said engine between a normal start mode and a manual start mode;
• a start time starter driving portion that operates said starter generator as the starter motor and supplies the driving current from said battery to said starter generator according to the output of said Hall sensor for causing the cranking of said engine when said start mode is the normal start mode;
• and
• a display portion that displays that the cranking for starting said engine is to be performed by said manual starter when said start mode is switched to the manual start mode,
• wherein said start mode switching portion is comprised so as to set the start mode to the normal start mode and cause said start time starter driving portion to start supplying the driving current to said starter generator when a start command of said engine is given, then keep the start mode of said engine in the normal start mode when the remaining capacity of the battery estimated by said battery capacity monitoring portion is checked and the remaining capacity of said battery is equal to or larger than a capacity required for said starter generator to start said engine, and prohibit the driving of said starter motor by said starter driving portion and switch the start mode of said engine to the manual start mode when the remaining capacity of said battery estimated by said battery capacity monitoring portion is smaller than the capacity required for starting said engine.