Working machine lifting control device

A lifting control device of a working machine for controlling movements of a lifting device, the lifting device including a fluid pressure actuator configured to lift and lower a working machine installed on a work vehicle, and a solenoid valve configured to control a flow of working fluid supplied to and discharged from the fluid pressure actuator, the lifting control device comprising:

• a position acquisition portion configured to acquire an extended and contracted position of the fluid pressure actuator;
• a target setting portion configured to set a target position of the fluid pressure actuator according to an operational input by a worker;
• a control portion configured to control an energized amount of the solenoid valve;
• and
• an input judging portion configured to judge whether the operational input is an opening command to perform an opening control in which an opening degree of the solenoid valve is made to be a predetermined set opening degree regardless of an extended or contracted position of the fluid pressure actuator or is a positional control command to perform a positional control in which the opening degree of the solenoid valve is made to be a smaller opening degree than the set opening degree according to an operational input amount, to control the extended or contracted position of the fluid pressure actuator,
• wherein the control portion is configured to perform a proportional integral control on the basis of a position deviation between the target position set by the target setting portion and an actual position acquired by the position acquisition portion, and a non-integral type control performing no integration of the position deviation,
• wherein when the operational input is judged as the positional control command by the input judging portion, a position within a stroke region between a most extended position and a most contracted position is set as the target position according to the operation input amount by the target setting portion, and the positional control is performed due to the proportional integral control by the control portion, and
• wherein when the operational input is judged as the opening command by the input judging portion, a position exceeding the most contracted position from the stroke region is set as the target position by the target setting portion, and the opening control is performed due to the non-integral type control by the control portion.