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US 6,623,247 B2Granted
Method and apparatus for controlling a variable displacement hydraulic pump
AssigneeCaterpillar Inc.
InventorHongliu Du
Life of this patent
Estimating the term…
Abstract
A method and apparatus for controlling a variable displacement hydraulic pump having a swashplate pivotally attached to the pump. The method and apparatus includes determining a desired swashplate angle as a function of a power limit of the pump, determining an actual swashplate angle, determining a value of discharge pressure of the pump, moving a servo valve spool to a desired position as a function of the desired swashplate angle, the actual swashplate angle and the discharge pressure, and responsively moving the swashplate to the desired swashplate angle position.
Claims28
A method for controlling a variable displacement hydraulic pump having a swashplate pivotally attached to the pump, including the steps of:
- determining at least one previous desired swashplate angle;
- determining a desired swashplate angle as a function of a power limit of the pump;
- determining an actual swashplate angle;
- determining a value of discharge pressure of the pump;
- moving a servo valve spool in a servo valve to a desired position as a function of the at least one previous desired swashplate angle, the desired swashplate angle, the actual swashplate angle, and the discharge pressure;
- and
- responsively moving the swashplate to the desired swashplate angle position.
4 more elements
A method for controlling a variable displacement hydraulic pump having a swashplate pivotally attached to the pump, including the steps of:
- determining a desired swashplate angle as a function of a power limit of the pump;
- determining an actual swashplate angle;
- determining a value of discharge pressure of the pump;
- moving a servo valve spool in a servo valve to a desired position as a function of the desired swashplate angle, the actual swashplate angle, and the discharge pressure;
- responsively moving the swashplate to the desired swashplate angle position;
- determining a value of control pressure of hydraulic fluid from the servo valve to a control servo, the control servo being adapted to control the actual swashplate angle;
- wherein moving a servo valve spool in a servo valve to a desired position includes the step of moving the servo valve spool in the servo valve to the desired position as a function of the desired swashplate angle, the actual swashplate angle, the discharge pressure, and the control pressure;
- and
- compensating the desired position of the servo valve spool as a function of an adaptive on-line learning term.
6 more elements
A method for controlling a variable displacement hydraulic pump having a swashplate pivotally attached to the pump, including the steps of:
- determining at least one previous desired swashplate angle;
- determining a desired swashplate angle as a function of a power limit of the pump;
- determining an actual swashplate angle;
- determining a value of discharge pressure of the pump;
- determining a value of control pressure of hydraulic fluid from a servo valve to a control servo, the control servo being adapted to control the actual swashplate angle;
- moving a servo valve spool in the servo valve to a desired position as a function of the at least one previous desired swashplate angle, the desired swashplate angle, the actual swashplate angle, the discharge pressure, and the control pressure;
- and
- responsively moving the swashplate to the desired swashplate angle position.
5 more elements
A method for controlling a variable displacement hydraulic pump having a swashplate pivotally attached to the pump, including the steps of:
- determining a desired swashplate angle as a function of a power limit of the pump;
- determining an actual swashplate angle;
- determining a value of discharge pressure of the pump;
- determining a value of control pressure of hydraulic fluid from a servo valve to a control servo, the control servo being adapted to control the actual swashplate angle;
- moving a servo valve spool in the servo valve to a desired position as a function of the desired swashplate angle, the actual swashplate angle, the discharge pressure, and the control pressure;
- and
- responsively moving the swashplate to the desired swashplate angle position;
- and
- compensating the desired position of the servo valve spool as a function of an adaptive on-line learning term, wherein the adaptive on-line learning term is changed over a period of time in response to uncertainties in parameters associated with at least one of the pump and the servo valve.
6 more elements
An apparatus for controlling a variable displacement hydraulic pump, comprising:
- a swashplate pivotally attached to the pump;
- a control servo operable to control an angle of the swashplate relative to the pump;
- a servo valve having an output port hydraulically connected to the control servo and an input port hydraulically connected to a pump output port;
- means for determining an actual swashplate angle;
- means for determining a value of discharge pressure of the pump;
- and
- a controller electrically connected to the servo valve and adapted to determine at least one previous desired swashplate angle and a desired swashplate angle as a function of a power limit of the pump, and to move a servo valve spool in the servo valve to a desired position as a function of the at least one previous desired swashplate angle, the desired swashplate angle, the actual swashplate angle, and the discharge pressure.
4 more elements
An apparatus for controlling a variable displacement hydraulic pump, comprising:
- a swashplate pivotally attached to the pump;
- a control servo operable to control an angle of the swashplate relative to the pump;
- a servo valve having an output port hydraulically connected to the control servo and an input port hydraulically connected to a pump output port;
- means for determining an actual swashplate angle;
- means for determining a value of discharge pressure of the pump;
- a controller electrically connected to the servo valve and adapted to determine a desired swashplate angle as a function of a power limit of the pump, and to move a servo valve spool in the servo valve to a desired position as a function of the desired swashplate angle, the actual swashplate angle, and the discharge pressure;
- and
- wherein the controller is further adapted to compensate the desired position of the servo valve spool as a function of an adaptive on-line learning term.
5 more elements
An apparatus for controlling a variable displacement hydraulic pump, comprising:
- a swashplate pivotally attached to the pump;
- a control servo operable to control an angle of the swashplate relative to the pump;
- a servo valve having an output port hydraulically connected to the control servo and an input port hydraulically connected to a pump output port;
- means for determining an actual swashplate angle;
- means for determining a value of discharge pressure of the pump;
- means for determining a value of control pressure of hydraulic fluid from the servo valve to the control servo;
- and
- a controller electrically connected to the servo valve and adapted to determine at least one previous desired swashplate angle and a desired swashplate angle as a function of a power limit of the pump, and to move a servo valve spool in the servo valve to a desired position as a function of the at least one previous desired swashplate angle, the desired swashplate angle, the actual swashplate angle, the discharge pressure, and the control pressure.
5 more elements
An apparatus for controlling a variable displacement hydraulic pump, comprising:
- a swashplate pivotally attached to the pump;
- a control servo operable to control an angle of the swashplate relative to the pump;
- a servo valve having an output port hydraulically connected to the control servo and an input port hydraulically connected to a pump output port;
- means for determining an actual swashplate angle;
- means for determining a value of discharge pressure of the pump;
- means for determining a value of control pressure of hydraulic fluid from the servo valve to the control servo;
- a controller electrically connected to the servo valve and adapted to determine a desired swashplate angle as a function of a power limit of the pump, and to move a servo valve spool in the servo valve to a desired position as a function of the desired swashplate angle, the actual swashplate angle, the discharge pressure, and the control pressure;
- and
- wherein the controller is further adapted to compensate the desired position of the servo valve spool as a function of an adaptive on-line learning term, wherein the adaptive on-line learning term is changed over a period of time in response to uncertainties in parameters associated with at least one of the pump and the servo valve.
6 more elements
Dependencies are inferred from the claim text.