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US 6,269,635 B1Granted
Control and hydraulic system for a liftcrane
AssigneeManitowoc Crane Group, Inc.
InventorArthur G. Zuehlke
Life of this patent
Estimating the term…
Abstract
A control system for a liftcrane that utilizes a closed loop hydraulic system that utilizes feed back and feed forward control architecture to provide responsiveness normally associated with systems that do not require feedback.
Claims18
A control system for a liftcrane, the control system comprising:
- a hoist actuator powered by a hydraulic pump, said hoist actuator connected to said pump by a closed hydraulic loop;
- a brake mechanism having an engaged state and a disengaged state;
- hoist system sensors operable to detect pressure in said closed loop and speed of said hoist actuator and said pump, and output signals indicative thereof;
- an operator control sensor operable to output signals representative of an operator command;
- and
- a programmable controller coupled to said brake mechanism, said hoist system sensors, said pump and said operator control sensor, said programmable controller adapted to run a routine operable to output signals to said pump and said brake mechanism for the operation thereof based upon the signals output by said hoist system sensors and said operator control sensor, wherein said routine includes a pressure mode operable to output a first pump control current signal ip to said pump when said brake mechanism is in its engaged state, the operator control sensor indicates that motion of the hoist is desired, and the detected system pressure is less than a load induced pressure, wherein said pump control current signal ip is determined by adding a threshold value Io to an error signal indicative of the difference between the detected system pressure and the load induced pressure.
3 more elements
In a liftcrane that includes a hoist powered by a closed loop hydraulic system and controls for outputting signals for operating the hoist, a control system comprising:
- a programmable controller adapted to run a routine operable to output a pump control current signal ip to a pump in the closed loop hydraulic system for operation thereof wherein said routine comprises a pressure mode and a motion mode, wherein said pressure mode and said motion mode operate exclusively of each other, and wherein said pressure mode calculates a pump control current signal ip needed to build system pressure equal to a load induced pressure and said motion mode calculates a pump control current signal ip needed for a hoist actuator to reach a commanded speed,
- and wherein in the pressure mode said pump control current signal ip is determined by adding a threshold value Io to an error signal indicative of the difference between the detected system pressure and the load induced pressure.
In a liftcrane that includes at least one hoist powered by a hoist actuator connected to a pump by a closed loop hydraulic system and controls for outputting signals for operating the hoist, a control system for operation of the hoist comprising:
- a programmable controller responsive to the controls and coupled to the pump and a brake mechanism, the controller including a routine adapted to control the hoist actuator to define operation of the hoist;
- sensors coupled to the controller for providing information about the status of the hoist to the controller wherein the sensors are capable of detecting pressure in the closed loop hydraulic system and speed of the hoist actuator and the pump;
- and further in which the routine that the programmable controller is adapted to run is further characterized as a routine that includes a pressure mode adapted to monitor and enable operation of the hoist when an operator commands motion of the hoist and the brake mechanism is in an engaged state and the pressure of the closed loop hydraulic system does not equal a load induced pressure;
- and
- wherein in the pressure mode a pump control current signal ip is determined by adding a threshold value Io to an error signal indicative of the difference between the detected system pressure and the load induced pressure.
2 more elements
A control system for a liftcrane, the control system comprising:
- a hoist actuator powered by a hydraulic pump, said hoist actuator connected to said pump by a closed hydraulic loop;
- a load holding device having an engaged state and a disengaged state;
- hoist system sensors operable to detect pressure in said closed loop and speed of said hoist actuator and said pump, and output signals indicative thereof;
- an operator control sensor operable to output signals representative of an operator command;
- and
- a programmable controller coupled to said load holding device, said hoist system sensors, said pump and said operator control sensor, said programmable controller adapted to run a routine operable to output signals to said pump and said load holding device for the operation thereof based upon the signals output by said hoist system sensors and said operator control sensor, wherein said routine includes a pressure mode operable to output a first pump control current signal ip to said pump when said load holding device is in its engaged state, the operator control sensor indicates that motion of the hoist is desired, and the detected system pressure is less than a load induced pressure, wherein said pump control current signal ip is determined by adding a threshold value Io to an error signal indicative of the difference between the detected system pressure and the load induced pressure.
3 more elements
In a liftcrane that includes at least one hoist powered by a hoist actuator connected to a pump by a closed loop hydraulic system and controls for outputting signals for operating the hoist, a control system for operation of the hoist comprising:
- a programmable controller responsive to the controls and coupled to the pump and a load holding device, the controller including a routine adapted to control the hoist actuator to define operation of the hoist:
- sensors coupled to the controller for providing information about the status of the hoist to the controller wherein the sensors are capable of detecting the pressure in the closed loop hydraulic system and speed of the hoist actuator and the pump;
- and further in which the routine that the programmable controller is adapted to run is further characterized as a routine that includes a pressure mode adapted to monitor and enable operation of the hoist when an operator commands motion of the hoist and said load holding device is in an engaged state and the pressure of the closed loop hydraulic system does not equal a load induced pressure;
- and
- wherein in the pressure mode a pump control current signal ip is determined by adding a threshold value Io to an error signal indicative of the difference between the detected system pressure and the load induced pressure.
2 more elements
Dependencies are inferred from the claim text.