초록 ▼

A hydraulic system for a machine is disclosed. The hydraulic system may have a tank configured to hold a supply of fluid, a pump configured to draw fluid from the tank and pressurize the fluid, a first cylinder operatively connected between a first side of a work tool and an undercarriage of the mac

A hydraulic system for a machine is disclosed. The hydraulic system may have a tank configured to hold a supply of fluid, a pump configured to draw fluid from the tank and pressurize the fluid, a first cylinder operatively connected between a first side of a work tool and an undercarriage of the machine, and a second cylinder operatively connected between a second side of the work tool and the undercarriage of the machine. The hydraulic system may also have a first electro-hydraulic valve associated with the first cylinder and configured to selectively regulate a flow of pressurized fluid to the first cylinder independently of the second cylinder, and a second electro-hydraulic valve associated with the second cylinder and configured to selectively regulate a flow of pressurized fluid to the second cylinder independently of the first cylinder.

대표청구항 ▼

1. A hydraulic system for a machine, comprising: a tank configured to hold a supply of fluid;a pump configured to draw fluid from the tank and pressurize the fluid;a first cylinder operatively connected between a first side of a work tool and a first undercarriage assembly of the machine;a second cy

1. A hydraulic system for a machine, comprising: a tank configured to hold a supply of fluid;a pump configured to draw fluid from the tank and pressurize the fluid;a first cylinder operatively connected between a first side of a work tool and a first undercarriage assembly of the machine;a second cylinder operatively connected between a second side of the work tool and a second undercarriage assembly of the machine;a first electro-hydraulic valve associated with the first cylinder and configured to selectively regulate a flow of pressurized fluid to the first cylinder independently of the second cylinder;a second electro-hydraulic valve associated with the second cylinder and configured to selectively regulate a flow of pressurized fluid to the second cylinder independently of the first cylinder;an operator interface device configured to generate signals that are indicative of desired work tool movement when manipulated by an operator, anda controller in communication with each of the first and second electro-hydraulic valves and the operator interface device, the controller being configured to: selectively generate valve position commands directed to the first and second electro-hydraulic valves that result in a single-action left tilt, a dual-action left tilt, a single-action right tilt, a dual-action right tilt, a pitch, and a combination tilt/pitch of the work tool;receive a first signal indicative of a desired tilting of the work tool and a second signal indicative of a desired pitching of the work tool;generate combined valve position commands directed to the first and second electro-hydraulic valves that are functions of the first and second signals;normalize the first and second signals and sum normalized values of the first and second signals to determine the combined valve position commands;reference sums of the normalized values with a relationship map stored in memory to determine the combined valve position commands;reduce the valve position commands by an amount when the first and second signals are received separately; andreduce the combined valve position commands by a lower amount when the first and second signals are received simultaneously. 2. The hydraulic system of claim 1, wherein: the first electro-hydraulic valve includes: a first main spool that is pilot-operated to move between a first position at which pressurized fluid from the pump is directed to a head-end of the first cylinder and fluid from a rod-end of the first cylinder is directed to the tank, a second position at which pressurized fluid from the pump is directed to the rod-end of the first cylinder and fluid from the head-end of the first cylinder is directed to the tank, and a third position at which fluid flow through the main spool is inhibited; andat least a first solenoid-operated valve element movable from a first position at which an end of the first main spool is connected to pressurized pilot fluid, and a second position at which the end of the first main spool is connected to the tank; andthe second electro-hydraulic valve includes: a second main spool that is pilot-operated to move between a first position at which pressurized fluid from the pump is directed to a head-end of the second cylinder and fluid from a rod-end of the second cylinder is directed to the tank, a second position at which pressurized fluid from the pump is directed to the rod-end of the second cylinder and fluid from the head-end of the second cylinder is directed to the tank, and a third position at which fluid flow through the second main spool is inhibited; andat least a second solenoid-operated valve element movable from a first position at which an end of the second main spool is connected to pressurized pilot fluid, and a second position at which the end of the second main spool is connected to the tank. 3. The hydraulic system of claim 2, wherein: each of the first and second main spools are spring-biased toward the third position; andeach of the first and second solenoid-operated valve elements are spring biased toward the second position. 4. The hydraulic system of claim 2, wherein: the end of the first main spool is a first end;the end of the second main spool is a first end;each of the first and second main spools includes a second end opposite the first end;the at least a first solenoid-operated valve element includes: a first solenoid-operated valve element associated with the first end of the first main spool; anda second solenoid-operated valve element associated with the second end of the first main spool; andthe at least a second solenoid-operated valve element includes: a first solenoid-operated valve element associated with the first end of the second main spool; anda second solenoid-operated valve element associated with the second end of the second main spool. 5. The hydraulic system of claim 4, further including: a first pre-pressure compensating valve associated with the first main spool; anda second pre-pressure compensating valve associated with the second main spool. 6. The hydraulic system of claim 2, further including a pilot pump configured to draw fluid from the tank, pressurize the fluid, and direct pressurized fluid to the at least a first solenoid-operated valve and to the at least a second solenoid operated valve. 7. The hydraulic system of claim 1, wherein the work tool is a blade mounted to a front end of the machine. 8. The hydraulic system of claim 1, wherein the operator interface device includes a joystick pivotal to generate the first signal and having a thumb roller movable to generate the second signal. 9. A method of moving a work tool, comprising: receiving a first signal indicative of desired work tool tilting;receiving a second signal indicative of desired work tool pitching;determining valve position commands based on the first and second signals;reducing the valve position commands by an amount when the first and second signals are received separately;reducing the valve position commands by a lower amount when the first and second signals are received simultaneously; andsimultaneously tilting and pitching the work tool based on the valve position commands,wherein determining the valve position commands includes normalizing the first and second signals, summing normalized values of the first and second signals, and referencing sums of the normalized values with a relationship map stored in memory. 10. The method of claim 9, further including separately implementing a single-action left tilt, a dual-action left tilt, a single-action right tilt, a dual-action right tilt, and a pitch based on the first and second signals.