Patent ID: 7941263

Claim:
An engine controller for a work vehicle connected to: an operation position detection sensor configured to detect an operation position of an acceleration manually operating device; a rotational speed sensor configured to detect a rotational speed of an engine; and a fuel injection control unit configured to control a fuel injection amount in the engine, the controller comprising: a first mode control module configured to perform a first mode control in which the fuel injection amount is obtained based on a first torque-engine rotational speed characteristic; a second mode control module configured to perform a second mode control in which the fuel injection amount is obtained based on a second torque-engine rotational speed characteristic in which a change in rotational speed along with a change in torque is smaller than that of the first torque-engine rotational speed characteristic; a control mode management unit configured to make a selection between the first mode control and the second mode control; a difference computing unit configured to compute a difference in rotational speed between a non-load engine rotational speed for the operation position detected by the operation position detection sensor and the engine rotational speed from the rotational speed sensor, the non-load engine rotational speed being defined for each operation position; a first engine load estimation part configured to estimate an engine load based on the difference in rotational speed, while the first mode control is performed, and a second engine load estimation part configured to estimate an engine load based on the fuel injection amount, while the second mode control is performed.