Torque control of hydrostatic machines via the pivot angle or the eccentricity of said machines

A circuit arrangement for controlling the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure, said circuit arrangement comprising:

• a control element for changing the displacement volume therewith the output torque of the machine, the change in displacement volume being based upon operating parameters corresponding to pressure, speed and temperature;
• control means supplied with a desired torque value for generating a control signal for actuating said control element;
• pick-up means connected to said control means and to said control element for picking up a pivotal angle .alpha. representing an actual displacement volume of said hydrostatic machine,
• wherein the pivotal angle .alpha. is measured in at least one of an analog and a digital manner, and
• wherein, when measured in an analog manner, the desired value of the pivotal angle is .alpha.=M/P, where M is the torque and P is the pressure,
• wherein, when measured in a digital manner, the desired value for the pivotal angle is determined from previously determined measured values, and
• wherein a speed limit value is superimposed onto the torque control, said speed limit value being such that it cannot be exceeded in a error situation of the machine.

A circuit arrangement for controlling the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure, said circuit arrangement comprising:

• a control element for changing the displacement volume which in turn determines the output torque of the machine, the displacement volume being changed based upon operating parameters corresponding to pressure, speed and temperature;
• control means supplied with a desired torque value for generating a control signal for actuating said control element;
• memory means connected to said control means;
• pick-up means connected to said control means and to said control element for picking up a pivotal angle .alpha.representing an actual displacement volume of said hydrostatic machine,
• wherein the pivotal angle .alpha. is measured in at least one of an analog and a digital manner, and
• wherein, when measured in an analog manner, the desired value of the pivotal angle is .alpha.=M/P, where M is the torque and P is the pressure,
• wherein, when measured in a digital manner, the desired value for the pivotal angle is determined from previously determined measured values, and wherein previously determined measured values are stored in said memory means.

A circuit arrangement for controlling the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure, said circuit arrangement comprising:

• a control element for changing the displacement volume which in turn determines the output torque of the machine, the change of displacement volume being based upon operating parameters corresponding to pressure, speed and temperature;
• control means supplied with a desired torque value for generating a control signal for actuating said control element;
• pick-up means connected to said control means and to said control element for picking up a pivotal angle .alpha. representing an actual displacement volume of said hydrostatic machine,
• wherein the pivotal angle .alpha. is measured in at least one of an analog and a digital manner, and
• wherein, when measured in an analog manner, the desired value of the pivotal angle is .alpha.=M/P, where M is the torque and P is the pressure,
• wherein, when measured in a digital manner, the desired value for the pivotal angle is determined from previously determined measured values, and wherein the machine unit comprises one or a plurality of hydrostatic machines with at least some of axial piston arrangements.

A method of controlling the output torque of a hydrostatic machine in a hydraulic system having an impressed operating pressure, said method comprising the following steps:

• representing the actual displacement volume of the machine by an actual displacement signal corresponding to a pivotal angle of said hydrostatic machine,
• determining a control signal for actuating a control element so as to change the displacement volume of the machine which determines the output torque by considering operating parameters for pressure, speed and temperature, wherein
• the pivotal angle is measured in an analog or a digital manner, and
• wherein, when calculated in the analog manner, the desired value of the pivotal angle is calculated, and
• wherein, when calculated in the digital manner, the desired value of the pivotal angle is determined from previously predetermined stored values.

A circuit arrangement for the control of the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure, said circuit arrangement comprising:

• a control element for changing the displacement volume which in turn determines the output torque of the machine, the change of the displacement volume being based upon operating parameters corresponding to pressure, speed and temperature;
• control means supplied with a desired torque value for generating a control signal for actuating said control element;
• pick-up means connected to said control means and to said control element for picking up and an eccentricity E representing an actual displacement volume of said hydrostatic machine,
• wherein the eccentricity E is measured in at least one of an analog and a digital manner, and
• wherein, when measured in an analog manner, the desired value of the eccentricity E=M/P, wherein M is the torque and P is the pressure and
• wherein, when measured in a digital manner, the outputted voltage for the eccentricity is determined from previously determined measured values, and
• wherein the desired value of the eccentricity which is applied to the control member is a corrected desired value, corrected with respect to a speed of the machine unit.

A circuit arrangement for controlling the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure, said circuit arrangement comprising:

• a control element for changing the displacement volume therewith the output torque of the machine, the change in displacement volume being based upon operating parameters corresponding to pressure, speed and temperature;
• control means supplied with a desired torque value for generating a control signal for actuating said control element;
• pick-up means connected to said control means and to said control element for picking up an eccentricity E representing an actual displacement volume of said hydrostatic machine,
• wherein the eccentricity E is measured in at least one of an analog and a digital manner, and
• wherein, when measured in an analog manner, the desired value of the eccentricity is E=M/P, where M is the torque and P is the pressure,
• wherein, when measured in a digital manner, the desired value for the eccentricity is determined from previously determined measured values, and
• wherein a speed limit value is superimposed onto the torque control, said speed limit value being such that it cannot be exceeded in a error situation of the machine.

A circuit arrangement for controlling the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure, said circuit arrangement comprising:

• a control element for changing the displacement volume which in turn determines the output torque of the machine, the displacement volume being changed based upon operating parameters corresponding to pressure, speed and temperature;
• control means supplied with a desired torque value for generating a control signal for actuating said control element;
• memory means connected to said control means;
• pick-up means connected to said control means and to said control element for picking up an eccentricity E representing an actual displacement volume of said hydrostatic machine,
• wherein the eccentricity E is measured in at least one of an analog and a digital manner, and
• wherein, when measured in an analog manner, the desired value of the eccentricity is E=M/P, where M is the torque and P is the pressure,
• wherein, when measured in a digital manner, the desired value for the eccentricity is determined from previously determined measured values, and wherein previously determined measured values are stored in said memory means.

A circuit arrangement for controlling the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure, said circuit arrangement comprising:

• a control element for changing the displacement volume which in turn determines the output torque of the machine, the change of displacement volume being based upon operating parameters corresponding to pressure, speed and temperature;
• control means supplied with a desired torque value for generating a control signal for actuating said control element;
• pick-up means connected to said control means and to said control element for picking up an eccentricity E representing an actual displacement volume of said hydrostatic machine,
• wherein the eccentricity E is measured in at least one of an analog and a digital manner, and
• wherein, when measured in an analog manner, the desired value of the eccentricity is E=M/P, where M is the torque and P is the pressure,
• wherein, when measured in a digital manner, the desired value for the eccentricity is determined from previously determined measured values, and wherein the machine unit comprises one or a plurality of hydrostatic machines with at least some radial piston arrangements.

A method of controlling the output torque of a hydrostatic machine in a hydraulic system having an impressed operating pressure, said method comprising the following steps:

• representing the actual displacement volume of the machine by an actual displacement signal corresponding to an eccentricity of said hydrostatic machine,
• determining a control signal for actuating a control element so as to change the displacement volume of the machine which determines the output torque by considering operating parameters for pressure, speed and temperature, wherein
• the eccentricity is measured in an analog or a digital manner, and
• wherein, when calculated in the analog manner, the desired value of the eccentricity is calculated, and
• wherein, when calculated in the digital manner, the desired value of the eccentricity is determined from previously predetermined stored values.