Patent ID: 8869928

Claim:
A construction machine comprising: an engine ( 10 ) as a prime mover; an exhaust gas purifying apparatus ( 16 ) that is provided in an exhaust side of said engine ( 10 ) to purify an exhaust gas; a regeneration apparatus ( 35 , 36 ) for executing a regeneration process to said exhaust gas purifying apparatus ( 16 ); a hydraulic pump ( 13 ) that is driven by said engine ( 10 ) to suck operating oil in a tank and discharge pressurized oil; at least one hydraulic actuator ( 24 ) that is driven by the pressurized oil discharged from said hydraulic pump ( 13 ); a directional control valve ( 25 ) that is provided between said hydraulic actuator ( 24 ) and said hydraulic pump ( 13 ) to control supply of the pressurized oil to said hydraulic actuator ( 24 ); a rotational speed instruction apparatus ( 29 ) that instructs a rotational speed (N) of said engine ( 10 ); an automatic idle selection unit ( 30 ) configured to lower said rotational speed of said engine ( 10 ) to a predetermined automatic idle rotational speed (Nai); and an engine control device ( 34 ) that regularly controls said rotational speed (N) of said engine ( 10 ) according to an instruction value by said rotational speed instruction apparatus ( 29 ) and, when said directional control valve ( 25 ) is in a neutral position, controls said rotational speed (N) of said engine ( 10 ) to said automatic idle rotational speed (Nai) by said automatic idle selection unit ( 30 ) regardless of said instruction value, characterized in that: said engine control device ( 34 ) comprises: a regeneration determining unit configured to determine whether or not said regeneration process to said exhaust gas purifying apparatus ( 16 ) is executed by said regeneration apparatus ( 35 , 36 ), at the time of controlling said rotational speed (N) of said engine ( 10 ) to said automatic idle rotational speed (Nai) by said automatic idle selection unit ( 30 ); and an engine rotational speed increasing unit configured to increase said rotational speed (N) of said engine ( 10 ) to a regeneration processing rotational speed (N1) higher than said automatic idle rotational speed (Nai), when it is determined that said regeneration process is executed by said regeneration determining unit.