Drive motor displacement control
AssigneeDoosan Bobcat North America, Inc.
InventorsCharles Young, Marty Carpenter, Scott Becker, Douglas Kallas, Matthew Kaldor, Eric Zabel, Boston Zachmann
Life of this patent
Estimating the term…
Abstract
A power machine can include a control device and a hydraulic circuit that can include a hydraulic pump in communication with a hydraulic motor that is configured to operate with infinitely variable displacement. The control device can be configured to determine a control value based on a commanded travel speed for the power machine and a pressure in the hydraulic circuit, and control a run-time displacement of the hydraulic motor based upon the determined control value.
Claims16
A power machine having a frame, a power source supported by the frame, and a power conversion system including a hydraulic drive system operably coupled to the power source and configured to power at least one tractive element, the hydraulic drive system comprising:
- a hydraulic circuit that includes a hydraulic pump in hydraulic communication with a hydraulic motor, the hydraulic motor being configured to operate with infinitely variable displacement to drive the power machine;
- and
- a control device that is configured to:
- determine a control value based on a commanded travel speed for the power machine and a pressure in the hydraulic circuit, with the pressure in the hydraulic circuit being prioritized over the commanded travel speed such that the control value corresponds to an adjusted travel speed of the power machine that is smaller than the commanded travel speed when the commanded travel speed corresponds to a hydraulic pressure that exceeds a pressure threshold;
- control a run-time displacement of the hydraulic motor based upon the determined control value;
- and
- selectively operate the hydraulic motor in at least a first displacement range and in a second displacement range that overlaps with, but is different from, the first displacement range, wherein operating the hydraulic motor within the first and second displacement ranges includes one or more of:
- based upon the determined control value, preventing a maximum run-time displacement of the hydraulic motor from exceeding a maximum displacement of the first displacement range or a maximum displacement of the second displacement range, respectively;
- or
- preventing a minimum run-time displacement of the hydraulic motor from being below a minimum displacement of the first displacement range or a minimum displacement of the second displacement range, respectively.
A hydraulic drive system for use in a power machine, the hydraulic drive system comprising:
- a hydraulic circuit that includes a hydraulic pump in hydraulic communication with a hydraulic drive motor, the hydraulic drive motor being configured to operate with infinitely variable displacement to drive the power machine;
- and
- a control device that is configured to:
- determine an output torque value associated with the hydraulic drive motor;
- determine that the determined output torque value exceeds a threshold torque value based on determining that a pressure in the hydraulic circuit exceeds a threshold pressure value;
- determine a control value based on a commanded travel speed for the power machine and the determined output torque value, with output torque of the hydraulic drive motor being prioritized over the commanded travel speed such that the control value corresponds to an adjusted travel speed of the power machine that is smaller than the commanded travel speed when the commanded travel speed corresponds to an output torque value that exceeds the threshold torque value;
- and
- control a run-time displacement of the hydraulic drive motor based upon the determined control value.
A method of controlling run-time operation of a drive system of a power machine, the method comprising:
- receiving, at a control device, one or more signals indicating a commanded travel speed for the power machine and an output torque associated with a variable displacement hydraulic pump and a variable displacement hydraulic drive motor of a hydraulic drive circuit of the power machine;
- determining, using the control device, a control value for the hydraulic drive motor, based on the one or more signals, the control value corresponding to an adjusted travel speed of the power machine that is smaller than the commanded travel speed when the commanded travel speed corresponds to an output torque value that exceeds a threshold torque value;
- controlling, using the control device, a run-time displacement of the hydraulic drive motor based upon the determined control value to cause the power machine to travel at the adjusted travel speed;
- and
- selectively operating the hydraulic drive motor within either of a first displacement range or a second displacement range that overlaps with but is different from the first displacement range, including:
- using the control device, adjusting the run-time displacement for the hydraulic drive motor based on the control value and a selected one of the first or second displacement ranges, so that a maximum run-time displacement and a minimum run-time displacement are limited by the selected first or second displacement range.
Dependencies are inferred from the claim text.