Hydraulic flow priority system
AssigneeCaterpillar Inc.
InventorStephen V. Lunzman
Life of this patent
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Abstract
A hydraulic system for a construction machine includes a pump for delivering fluid under pressure from a fluid reservoir to at least first and second main valves. First and second input devices are included for producing first and second control signals that are indicative of a desired operation of the hydraulic system. A controller responsive to at least the first and second control signals is provided and produces a compensating signal in response to the first and second control signals. The second main valve is operated in response to both the second control signal and the compensating signal.
Claims6
A hydraulic system for a construction machine comprising a pump for delivering fluid under pressure from a fluid reservoir to at least first and second main valves, said second main valve including first and second pilot valves, comprising:
- first and second input means for producing first and second control signals, respectively, said first and second control signals being indicative of a desired operation of the hydraulic system, said second input means being moveable in two directions;
- first modulation means for producing first and second actuator signals as a function of said first control signal, said first and second actuator signals being delivered to control said first main valve;
- second modulation means for producing third and fourth actuator signals as a function of said second control signal, said third actuator signal being delivered to a first pilot valve associated with said second main valve in response to said second input means being moved in a first direction and said fourth actuator signal being delivered to a second pilot valve in response to said second input means being moved in a second direction;
- means for producing a first compensating signal in response to said second input means being moved in a first direction, said first compensating signal being a function of said first and second actuator signals and said fourth actuator signal, said first compensating signal being delivered to a second pilot valve associated with said second main valve;
- means for producing a second compensating signal in response to said second input means being moved in a second direction, said second compensating signal being a function of said first and second actuator signals and said third actuator signal, said second compensating signal being delivered to a first pilot valve associated with said second main valve.
A method for controlling a hydraulic system said hydraulic system including a hydraulic pump, first and second input device, first and second main valves, said second main valve including first and second pilot valves, comprising the steps of:
- producing first and second control signals in response to movement of said first and second input device, respectively, said second input device being moveable in two directions;
- producing first and second actuator signals in response to said first control signal;
- controlling said first main valve in response to said first and second actuator signals;
- producing third and fourth actuator signals in response to said second control signal;
- delivering said third actuator signal to said first pilot valve associated with said second main valve in response to said second input device being moved in a first direction and delivering said fourth actuator signal to said second pilot valve associated with said second main valve in response to said second input device being moved in a second direction;
- producing a first compensating signal in response to said second input device being moved in a first direction, said first compensating signal being a function of said first and second actuator signals and said fourth actuator signal;
- delivering said first compensating signal to said second pilot valve associated with said second main valve;
- producing a second compensating signal in response to said second input device being moved in a second direction, said second compensating signal being a function of said first and second actuator signals and said third actuator signal;
- delivering said second compensating signal to said first pilot valve associated with said second main valve;
- and
- controlling said second main valve in response to said first and second pilot valves.
Dependencies are inferred from the claim text.