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US RE51,031 E1Granted
Hydraulic system for work machine, and work machine
AssigneeKubota Corporation
InventorsYuji Fukuda, Kazuyoshi Arii
Life of this patent
Estimating the term…
Abstract
A hydraulic system for a work machine includes a hydraulic pump to supply a pilot fluid, and a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure. The pilot pressure is a pressure of the pilot fluid supplied from the hydraulic pump. The hydraulic system includes a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions. The hydraulic system includes a pressure applying device to apply a second pilot pressure to the hydraulic switch valve. The second pilot pressure is lower than the first pilot pressure.
Claims38
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- and
- a pressure applying device to apply a second pilot pressure to the hydraulic switch valve, the second pilot pressure being lower than the first pilot pressure,
- wherein the pressure applying device includes
- a second fluid tube connecting the direction switch valve to the hydraulic switch valve,
- a fourth fluid tube connecting the hydraulic pump to the direction switch valve, and
- a fourth throttle to set the pilot pressure in the direction switch valve to the second pilot pressure.
6 more elements
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- and
- a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure,
- wherein the speed reducing device includes
- a second fluid tube connecting the direction switch valve to the hydraulic switch valve,
- a second throttle to reduce the pilot pressure in the second fluid tube,
- a third fluid tube connecting the hydraulic switch valve to a tank to which the pilot fluid is to be discharged from the hydraulic switch valve, and
- a third throttle to reduce an amount of the pilot fluid flowing in the third fluid tube,
- wherein the second throttle and the third throttle reduce the speed of changing the pilot pressure.
8 more elements
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- a pressure applying device to apply a second pilot pressure to the hydraulic switch valve, the second pilot pressure being lower than the first pilot pressure;
- and
- a speed reducing device to reduce a speed of changing the pilot pressure, the pilot pressure being to be applied to the hydraulic switch valve and to be changed to the first pilot pressure.
3 more elements
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- a pressure applying device to apply a second pilot pressure to the hydraulic switch valve, the second pilot pressure being lower than the first pilot pressure;
- a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
- a fourth fluid tube connecting the hydraulic pump to the direction switch valve;
- and
- a discharge fluid tube which is connected to the direction switch valve and through which the pilot fluid in the second fluid tube is to be introduced from the direction switch valve,
- wherein the direction switch valve is switchable between a first position and a second position, the direction switch valve being switched to the first position such that the second fluid tube communicates with the discharge fluid tube to relieve the pilot fluid in the second fluid tube, the direction switch valve being switched to the second position such that the fourth fluid tube communicates with the second fluid tube to apply the first pilot pressure to the hydraulic switch valve.
6 more elements
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure;
- a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
- a fourth fluid tube connecting the hydraulic pump to the direction switch valve;
- and
- a discharge fluid tube which is connected to the direction switch valve and through which the pilot fluid in the second fluid tube is to be introduced from the direction switch valve,
- wherein the direction switch valve is switchable between a first position and a second position, the direction switch valve being switched to the first position such that the second fluid tube communicates with the discharge fluid tube to relieve the pilot fluid in the second fluid tube, the direction switch valve being switched to the second position such that the fourth fluid tube communicates with the second fluid tube to apply the first pilot pressure to the hydraulic switch valve.
6 more elements
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- a pressure applying device to apply a second pilot pressure to the hydraulic switch valve, the second pilot pressure being lower than the first pilot pressure;
- and
- a second fluid tube connecting the direction switch valve to the hydraulic switch valve,
- wherein the direction switch valve is a proportional valve to change an aperture to change a pilot pressure that is a pressure of the pilot fluid flowing in the second fluid tube,
- and wherein the pressure applying device is to set the aperture of the proportional valve to maintain the pilot pressure in the second fluid tube to be less than the first pilot pressure.
5 more elements
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure;
- a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
- and
- a speed controller to control a speed of changing the pilot pressure to be changed to the first pilot pressure,
- wherein the direction switch valve is a proportional valve to change an aperture to change the pilot pressure in the second fluid tube,
- and wherein the speed controller includes the speed reducer to change a speed of changing the aperture of the proportional valve to reduce the speed of changing the pilot pressure to be changed to the first pilot pressure.
6 more elements
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure;
- a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
- and
- a speed controller including the speed reducer to change a speed of changing the pilot pressure to be changed to the first pilot pressure;
- and
- a first travel sensor to detect a travel speed,
- wherein the direction switch valve is a proportional valve to change an aperture to change the pilot pressure in the second fluid tube,
- wherein the speed controller is to set a speed of changing the aperture of the proportional valve to a first changing speed corresponding to a first speed when the travel speed is the first speed, and to set the speed of changing the aperture of the proportional valve to a second changing speed corresponding to a second speed when the travel speed is the second speed,
- and wherein the first changing speed is lower than the second changing speed.
9 more elements
A hydraulic system for a work machine, comprising:
- a hydraulic pump to supply a pilot fluid;
- a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
- a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
- a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure;
- a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
- a speed controller including the speed reducer to change a speed of changing the pilot pressure to be changed to the first pilot pressure;
- and
- a second travel sensor to detect an operation being in traveling and an operation being in non-traveling,
- wherein the direction switch valve is a proportional valve to change an aperture to change the pilot pressure in the second fluid tube,
- wherein the speed controller is to set a speed of changing the aperture of the proportional valve to a third changing speed corresponding to a state of traveling and to a fourth changing speed corresponding to a state of non-traveling,
- and wherein the third changing speed is lower than the fourth changing speed.
8 more elements
A hydraulic system for a work machine, comprising:
- a first hydraulic pump to output an operation fluid;
- a second hydraulic pump to output the operation fluid;
- a third hydraulic pump to output the operation fluid;
- a control valve connected to the first hydraulic pump to control a hydraulic actuator by supplying the operation fluid to the hydraulic actuator through a supply tube connecting and extending between the control valve and the hydraulic actuator, in response to a first pilot pressure applied on a first pressure receiver of the control valve;
- an operation valve connected to the third hydraulic pump to regulate the first pilot pressure;
- a high flow valve connected to the second hydraulic pump to supply the operation fluid to the hydraulic actuator through the supply tube and an increasing fluid tube connecting and extending between the high flow valve and the supply tube, in response to a second pilot pressure applied on a pressure receiver of the high flow valve;
- a switch valve connected to the high flow valve to regulate the second pilot pressure;
- a first fluid tube for connection between an interlocking fluid tube and a second fluid tube, the interlocking fluid tube connecting between the switch valve and the operation valve, and the second fluid tube connecting between the switch valve and the high flow valve;
- and
- a first throttle is provided in the first fluid tube,
- wherein the switch valve is connected to the operation valve and the first pressure receiver of the control valve, and switches between an applying position and a non-applying position which applies and does not apply the second pilot pressure on the pressure receiver of the high flow valve, respectively, and
- wherein the pressure receiver of the high flow valve is applied with a pressure greater than zero and less than the second pilot pressure which switches the high flow valve to the increasing position, when the switch valve is in the non-applying position.
9 more elements
A hydraulic system for a work machine, comprising:
- a first hydraulic pump to output an operation fluid;
- a second hydraulic pump to output the operation fluid;
- a third hydraulic pump to output the operation fluid;
- a control valve connected to the first hydraulic pump to control a hydraulic actuator by supplying the operation fluid to the hydraulic actuator through a supply tube connecting and extending between the control valve and the hydraulic actuator, in response to a first pilot pressure applied on a first pressure receiver of the control valve;
- an operation valve connected to the third hydraulic pump to regulate the first pilot pressure;
- a high flow valve connected to the second hydraulic pump to supply the operation fluid to the hydraulic actuator through the supply tube and an increasing fluid tube connecting and extending between the high flow valve and the supply tube, in response to a second pilot pressure applied on a pressure receiver of the high flow valve;
- a switch valve connected to the high flow valve to regulate the second pilot pressure;
- a second fluid tube for connection between the switch valve and the high flow valve;
- and
- a second throttle is provided in the second fluid tube,
- wherein the switch valve is connected to the operation valve and the first pressure receiver of the control valve, and switches between an applying position and a non-applying position which applies and does not apply the second pilot pressure on the pressure receiver of the high flow valve, respectively, and
- wherein a changing rate of the second pilot pressure is reduced upon switching the switch valve to the applying position.
9 more elements
A hydraulic system for a work machine, comprising:
- a first hydraulic pump to output an operation fluid;
- a second hydraulic pump to output the operation fluid;
- a third hydraulic pump to output the operation fluid;
- a control valve connected to the first hydraulic pump to control a hydraulic actuator by suppling the operation fluid to the hydraulic actuator through a supply tube in response to a first pilot pressure applied on a first pressure receiver of the control valve;
- an operation valve connected to the third hydraulic pump to regulate the first pilot pressure;
- a high flow valve connected to the second hydraulic pump to supply the operation fluid to the hydraulic actuator through an increasing fluid tube and the supply tube in response to a second pilot pressure applied on a pressure receiver of the high flow valve;
- a switch valve connected to the high flow valve to regulate the second pilot pressure;
- a first fluid tube for connection between an interlocking fluid tube and a second fluid tube, the interlocking fluid tube connecting between the switch valve and the operation valve, and the second fluid tube connecting between the switch valve and the high flow valve;
- and
- a first throttle is provided in the first fluid tube,
- wherein the switch valve is connected to the operation valve and the first pressure receiver of the control valve, and switches between an applying position and a non-applying position which applies and does not apply the second pilot pressure on the pressure receiver of the high flow valve, respectively, and
- wherein the pressure receiver of the high flow valve is applied with a pressure greater than zero and less than the second pilot pressure which switches the high flow valve to the increasing position, when the switch valve is in the non-applying position.
9 more elements
A hydraulic system for a work machine, comprising:
- a first hydraulic pump to output an operation fluid;
- a second hydraulic pump to output the operation fluid;
- a third hydraulic pump to output the operation fluid;
- a control valve connected to the first hydraulic pump to control a hydraulic actuator by supplying the operation fluid to the hydraulic actuator through a supply tube in response to a first pilot pressure applied on a first pressure receiver of the control valve;
- an operation valve connected to the third hydraulic pump to regulate the first pilot pressure;
- a high flow valve connected to the second hydraulic pump to supply the operation fluid to the hydraulic actuator through an increasing fluid tube and the supply tube in response to a second pilot pressure applied on a pressure receiver of the high flow valve;
- a switch valve connected to the high flow valve to regulate the second pilot pressure;
- a second fluid tube for connection between the switch valve and the high flow valve;
- and
- a second throttle is provided in the second fluid tube,
- wherein the switch valve is connected to the operation valve and the first pressure receiver of the control valve, and switches between an applying position and a non-applying position which applies and does not apply the second pilot pressure on the pressure receiver of the high flow valve, respectively, and
- wherein a changing rate of the second pilot pressure is reduced upon switching the switch valve to the applying position.
9 more elements
Dependencies are inferred from the claim text.