Construction machine

A construction machine comprising:

• an engine (10) to which injection fuel is supplied by an electronically controlled fuel injection device (12);
• a temperature state detector (30) for detecting a temperature state of said engine (10);
• a rotation detector (31) for detecting a rotational speed (N) of said engine (10);
• a rotational speed setting device (32) for setting a target rotational speed (Nset) of said engine (10);
• a control device (34) for driving/controlling said engine (10) on the basis of signals from said temperature state detector (30), said rotation detector (31), and said rotational speed setting device (32);
• a variable displacement type hydraulic pump (13) which is driven by said engine (10) so as to deliver pressurized oil and is subjected to torque limitation control;
• and
• a hydraulic actuator (24) driven by the pressurized oil delivered from said hydraulic pump (13), characterized in that:
• said control device (34) includes;
• a start temperature determining processing unit configured to determine whether or not a temperature (T) at start of said engine (10) has lowered to a predetermined temperature (Tw1) determined in advance on the basis of a detection signal outputted from said temperature state detector (30);
• a start control processing unit configured to perform start control of said engine (10) in accordance with a set value of said target rotational speed (Nset) by said rotational speed setting device (32) when it is determined by the start temperature determining processing unit that said temperature (T) is equal to or lower than said predetermined temperature (Tw1);
• a pump cavitation limit rotational speed as a limit value at which possibility of generation of air bubbles in the hydraulic oil and of occurrence of cavitation becomes higher when said hydraulic pump (13) rotates at a low-temperature start of said engine is determined in advance as a threshold value (Nca);
• in case the set value of said target rotational speed (Nset) by said rotational speed setting device (32) is equal to or less than said threshold value (Nca), said start control processing unit starts said engine (10) in accordance with the set value at this time;
• and
• in case the set value of said rotational speed setting device (32) is higher than said threshold value (Nca), said start control processing unit stops the start of said engine (10) or performs the start control of said engine (10) in accordance with a temporary set value (Ntem) for engine start set in advance.