Back to results
US 4,768,340 AGranted
Automatic displacement control for variable displacement motor
AssigneeAllied-Signal Inc.
InventorPaul U. Hamilton
Life of this patent
Estimating the term…
Abstract
A variable displacement motor control responsive to the pressure differential across the motor, with provisions for reverse motor operation and for aiding load conditions.
Claims25
A hydraulic system comprising:
- first and second ducts adapted to be connected respectively to a source of fluid pressure and a low pressure fluid return;
- a variable displacement motor having a pair of ports;
- a reversing valve interposed between said motor and said first and second ducts for selectively reversing connections between said pair of ports and said first and second ducts to selectively drive said motor in opposite directions;
- displacement control means operably associated with said motor for altering the displacement thereof, said displacement control means including opposed fluid chambers operably communicating with said pair of ports for impressing the pressure differential between said pair of ports upon said displacement control means to adjust the latter;
- biasing means engaging said displacement control means for urging the latter in a direction reducing displacement of said motor;
- and
- shuttle valve means, responsive to said pressure differential between said pair of ports, for automatically reversing communication between said opposed fluid chambers and said pair of ports whereby said pressure differential always urges said displacement control means in a direction increasing displacement of said motor.
4 more elements
A hydraulic system comprising:
- first and second ducts adapted to be connected respectively to a source of fluid pressure and a low pressure fluid return;
- a variable displacement motor having a pair of ports;
- a reversing valve interposed between said motor and said first and second ducts for selectively reversing connections between said pair of ports and said first and second ducts to selectively drive said motor in opposite directions;
- displacement control means operably associated with said motor for altering the displacement thereof, said displacement control means including a fluid chamber arranged whereby pressure therein urges said displacement control means only in a direction increasing displacement of said motor;
- biasing means engaging said displacement control member for urging the latter in a direction decreasing displacement of said motor;
- and
- means, responsive to the pressures in said pair of ports, for automatically controlling communication of said fluid chamber with said pair of ports in a manner assuring that said fluid chamber always communicates with the one of said pair of ports carrying the higher pressure fluid.
4 more elements
A hydraulic system comprising:
- first and second ducts adapted to be connected respectively to a source of fluid pressure and a low pressure fluid return;
- a variable displacement hydraulic motor having a pair of ports and a displacement control member shiftable to alter the displacement of said motor between minimum and maximum displacement positions;
- a reversing control valve communicating with said first and second ducts and said pair of ports for selectively reversing connection of said first and second ducts with said pair of ports to selectively drive said motor in opposite directions of rotation;
- a hydraulic actuator including a piston operably connected to said displacement control member for shifting the latter, and a pair of opposed fluid chambers on opposite sides of said piston operably communicating with said pair of ports at locations downstream of said reversing control valve for impressing the pressure differential between said pair of ports across said piston;
- biasing means engaging said piston for urging the latter to move said displacement control member toward said minimum displacement position;
- and
- shuttle valve means, responsive to said pressure differential between said pair of ports, for automatically reversing the communication between said opposed fluid chambers and said pair of ports whereby said pressure differential always urges said piston to move said displacement control member toward said maximum displacement position.
4 more elements
A hydraulic system comprising:
- first and second ducts adapted to be connected respectively to a source of fluid pressure and a low pressure fluid return;
- a variable displacement hydraulic motor having a pair of ports and a displacement control member shiftable to alter the displacement of said motor between minimum and maximum displacement positions;
- a reversing control valve communicating with said first and second ducts and said pair of ports for selectively reversing connection of said first and second ducts with said pair of ports to selectively drive said motor in opposite directions of rotation;
- hydraulic actuator means for shifting said displacement control member, including a pair of opposed fluid chambers operably communicating with said pair of ports for impressing the pressure differential between said pair of ports upon said actuator means;
- biasing means engaging said actuator means for urging the latter to move said displacement control member toward said minimum displacement position;
- and
- means, responsive to said pressure differential, for automatically reversing communication between said pair of opposed fluid chambers and said pair of ports whereby said pressure differential always urges said actuator means to move said displacement control member toward said maximum displacement position.
4 more elements
In a hydraulic system having a source of fluid pressure, a low pressure fluid return, and a variable displacement motor having a pair of ports, a control system comprising:
- a reversing valve shiftable between positions connecting one and the other of said pair of ports with said source of fluid pressure;
- displacement control means associated with said motor for varying the displacement of said motor, said displacement control means including a pair of fluid chambers arranged to communicate with said pair of ports such that the pressure differential between said pair of ports acts to adjust said displacement control means;
- biasing means for urging said displacement control means in a direction reducing displacement of said motor;
- and valve means responsive to said pressure differential for automatically reversing communication of said pair of ports with said pair of fluid chambers such that said pressure differential always acts to urge said displacement control means in a direction increasing displacement of said pump.
1 more element
In a hydraulic system having a source of pressurized fluid and a low pressure fluid return, a method for controlling operation of a variable displacement hydraulic motor having a pair of fluid ports and a hydraulically responsive displacement control member shiftable between minimum and maximum positions respectively developing minimum and maximum motor displacement, said method comprising the steps of:
- selectively reversing communication of said pair of ports with said source and said return to drive said motor in opposite directions;
- sensing the magnitude and the direction of the pressure differential between said pair of ports;
- adjusting the displacement control member in relation to the sensed magnitude of the pressure differential;
- reversing flow of pressurized actuating fluid to the displacement control member in relation to the sensed direction of the pressure differential such that the displacement control member is always urged toward said maximum position in relation to said sensed magnitude during said adjusting step regardless of said sensed direction of the pressure differential;
- and
- continuously biasing the displacement control member toward said minimum position.
3 more elements
In a hydraulic system having a source of pressurized fluid and a low pressure fluid return, a method for controlling operation of a variable displacement hydraulic motor having a pair of fluid ports and a hydraulically responsive displacement control member shiftable between minimum and maximum positions respectively developing minimum and maximum motor displacement, said method comprising the steps of:
- selectively reversing communication of said pair of ports with said source and said return to drive said motor in opposite directions;
- impressing the pressure differential between said pair of ports upon the displacement control member to adjust motor displacement in relation to the magnitude of the pressure differential;
- automatically reversing communication between said pair of ports and the displacement control member such that the pressure differential always urges the displacement control member toward said maximum position;
- and
- continuously biasing the displacement control member toward said minimum position.
2 more elements
A hydraulic system comprising:
- first and second ducts adapted to be connected respectively to a source of fluid pressure and a low pressure fluid return;
- a variable displacement motor having a pair of ports;
- displacement control means operably associated with said motor for altering the displacement thereof, said displacement control means including a fluid chamber arranged whereby pressure therein urges said displacement control means only in a direction increasing displacement of said motor;
- biasing means engaging said displacement control member for urging the latter in a direction decreasing displacement of said motor;
- and
- means, responsive to the pressures in said pair of ports, for automatically controlling communication of said fluid chamber with said pair of ports in a manner assuring that said fluid chamber always communicates with the one of said pair of ports carrying the higher pressure fluid.
3 more elements
Dependencies are inferred from the claim text.