Method for ascertaining the target rotational speed of a drive machine of a work machine comprising a continuously variable transmission and a working hydraulic system

A method of determining a setpoint rotational speed (n_soll) of a prime mover of a work machine, having a continuously variable transmission and power hydraulics, the setpoint rotational speed (n_soll) of the prime mover being determined, by a control unit or vehicle bus, based on operating state information of the power hydraulics, the method comprising:

• attempting to detect the operating state information of the power hydraulics with sensors of a sensor system;
• if the operating state information of the power hydraulics is unavailable, determining the setpoint rotational speed (n_soll) of the prime mover (6) based on basic engine speed settings and excluding consideration of a current operating state of the power hydraulics;
• if the operating state information of the power hydraulics is known, determining the setpoint rotational speed (n_soll) of the prime mover based on either:
• a combination of the basic engine speed settings and one of a low engine speed setting and a high engine speed setting or
• one of the low engine speed setting and the high engine speed setting;
• wherein the setpoint rotational speeds (n_soll) of the prime mover determined from the low engine speed settings alone is lower than the setpoint rotational speeds (n_soll) of the prime mover determined from either the basic engine speed setting or the combination of the basic engine speed setting and the low engine speed setting;
• wherein the setpoint rotational speeds (n_soll) of the prime mover determined from the high engine speed settings alone is higher than the setpoint rotational speeds (n_soll) of the prime mover determined from either the basic engine speed setting or the combination of the basic engine speed setting and the high engine speed setting;
• each of the low engine speed setting, the basic engine speed setting and the high engine speed setting being represented by a setpoint rotational speed range (n_soll_bo and n_soll_bu, n_soll_lo and n_soll_lu, n_soll_ho and n_soll_hu) of the prime mover plotting the setpoint rotational speed ranges as a function of a reciprocal transmission range (i_rez) of the continuously variable transmission;
• weighting, with a logic function, at least two variables which correlate to the operating state of the power hydraulics;
• further determining the setpoint rotational speed (n_soll) of the prime mover based on the weighting of the at least two variables and one of:
• the low engine speed setting,
• the basic engine speed setting,
• the high engine speed setting,
• the combination of the low engine speed setting and the basic engine speed setting, and
• the combination of the high engine speed setting and the basic engine speed setting;
• and
• controlling the rotational speed of the prime mover based on the determined setpoint rotational speed of the prime mover.