# US 11,306,746 B2 · Hydraulic system for working machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,306,746 B2 - Document ID: US11306746B2 - Status: Granted - Kind: B2 - Application number: 16/987,910 - Filed: 2020-08-07 - Published: 2020-11-19 - Granted: 2022-04-19 - Earliest claimed: 2016-12-28 - Assignees: Kubota Corporation - Applicants: Kubota Corporation - Inventors: Yuji Fukuda; Keigo Honda; Ryosuke Kinugawa; Ryuki Nishimoto; Yuji Yamashita; Daisuke Sakurai - Web page: https://patentgrep.com/patent/US11306746B2 ## CPC - F15B 13/021: {Valves for interconnecting the fluid chambers of an actuator} - E02F 9/2203: {Arrangements for controlling the attitude of actuators, e.g. speed, floating function} - E02F 9/2207: {for reducing or compensating oscillations} - E02F 9/2217: {with energy recovery arrangements, e.g. using accumulators, flywheels} - E02F 9/2267: {Valves or distributors (position of valves arrangements on upper-structures E02F9/0875)} - F15B 1/02: Installations or systems with accumulators - F15B 1/26: Supply reservoir or sump assemblies - F15B 11/08: with only one servomotor - F15B 21/0427: Heating - E02F 3/3414: {the arms being pivoted at the rear of the vehicle chassis, e.g. skid steer loader} - F15B 2201/411: having valve means - F15B 2211/30565: having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve - F15B 2211/3127: Floating position connecting the working ports and the return line - F15B 2211/31558: having a single output member - F15B 2211/329: actuated by fluid pressure - F15B 2211/625: Accumulators - F15B 2211/635: Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements - F15B 2211/66: Temperature control methods - F15B 2211/6658: Control using different modes, e.g. four-quadrant-operation, working mode and transportation mode - F15B 2211/8613: the abnormal condition being oscillations - F15B 2211/8616: the abnormal condition being noise or vibration - F15B 2215/30: Constructional details thereof - F16L 55/04: Devices damping pulsations or vibrations in fluids {(F16L55/02 takes precedence)} - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00) - F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL ## Abstract A hydraulic system for a working machine includes a hydraulic actuator having a first fluid chamber and a second fluid chamber, an accumulator, an outputting fluid tube to output an operation fluid, and a switching valve to be switched between a first position and a second position. The first position allows the first fluid chamber and the second fluid chamber to be communicated with the outputting fluid tube and thereby allowing a floating operation. The second position allows the first fluid chamber and the accumulator to be communicated with each other, allows the second fluid chamber and the outputting fluid tube to be communicated with each other, and thereby allows an anti-vibration operation. ## Claims ### Claim 1 A hydraulic system for a working machine, comprising: a hydraulic actuator; a float switching valve to perform a floating operation of the hydraulic actuator; an anti-vibration switching valve to perform an anti-vibration operation of the hydraulic actuator; a control device to stop the anti-vibration operation performed by the anti-vibration switching valve when the float switching valve performs the floating operation; a first switch connected to the control device and configured to issue a first command of the floating operation; and a second switch connected to the control device and configured to issue a second command of the floating operation, wherein when the control device receives the second command, the control device initiates the anti-vibration operation by the anti-vibration switching valve; when the control device receives the first command while the second command is already being received, the control device stops the anti-vibration operation. ### Claim 2 (depends on 1) The hydraulic system for the working machine according to claim 1, comprising an accumulator, wherein the anti-vibration switching valve is configured to be switched between an anti-vibration position and a stop position, the anti-vibration position allowing the accumulator and the hydraulic actuator to be communicated with each other and thereby allowing the anti-vibration operation, the stop position not allowing the accumulator and the hydraulic actuator to be communicated with each other and thereby stopping the anti-vibration operation, wherein the control device is configured to switch the anti-vibration switching valve to the stop position while the float switching valve performs the floating operation. ### Claim 3 (depends on 2) The hydraulic system for the working machine according to claim 2, comprising: a control valve to control operation fluid that is to be supplied to the hydraulic actuator; a first supplying tube connecting the control valve to a first fluid chamber disposed on the hydraulic actuator; a second supplying tube connecting the control valve to a second fluid chamber disposed on the hydraulic actuator; and an outputting fluid tube to output the operation fluid, wherein the float switching valve is configured to be switched between a float position and a block position, the float position allowing the first supplying tube and the second supplying tube to be communicated with the outputting fluid tube, the block position blocking the first supplying tube and the second supplying tube from being communicated with the outputting fluid tube. ### Claim 4 (depends on 1) The hydraulic system for the working machine according to claim 1, comprising: a control valve to control operation fluid that is to be supplied to the hydraulic actuator; a first supplying tube connecting the control valve to a first fluid chamber disposed on the hydraulic actuator; a second supplying tube connecting the control valve to a second fluid chamber disposed on the hydraulic actuator; and an outputting fluid tube to output the operation fluid, wherein the float switching valve is configured to be switched between a float position and a block position, the float position allowing the first supplying tube and the second supplying tube to be communicated with the outputting fluid tube, the block position blocking the first supplying tube and the second supplying tube from being communicated with the outputting fluid tube. ### Claim 5 A hydraulic system for a working machine, comprising: a hydraulic actuator; a float switching valve to perform a floating operation of the hydraulic actuator; and an anti-vibration switching valve to perform an anti-vibration operation of the hydraulic actuator; wherein the float switching valve or the anti-vibration switching valve includes: a solenoid valve to which the operation fluid serving as a pilot fluid is supplied; a pressure-receiving portion to receive the pilot fluid from the solenoid valve; an inner fluid tube to connect the solenoid valve to the pressure-receiving portion; and an outputting fluid tube branched from the inner fluid tube, the outputting fluid tube being configured to drain the pilot fluid from the pressure-receiving portion. ### Claim 6 (depends on 5) The hydraulic system for the working machine according to claim 5, comprising: a first switch to issue a first command of the floating operation; a second switch to issue a second command of the anti-vibration operation; and a control device, wherein the control device is configured to: switch the float switching valve to a first position or to a second position in accordance with the first command; switch the anti-vibration switching valve to the first position or to the second position in accordance with the second command; and not to switch, in warming up of operation fluid, the float switching valve and the anti-vibration switching valve in accordance with the first command and the second command. ### Claim 7 (depends on 6) The hydraulic system for the working machine according to claim 6, wherein the float switching valve or the anti-vibration switching valve includes a three-position switching valve, the three-position switching valve including a spool, and wherein the pressure-receiving portion includes: a first pressure-receiving portion arranged on one side of the spool in a longitudinal direction of the spool; and a second pressure-receiving portion arranged on the other side of the spool in the longitudinal direction, and wherein the pilot fluid is applied to the first pressure-receiving portion and the second pressure-receiving portion. ### Claim 8 (depends on 5) The hydraulic system for the working machine according to claim 5, wherein the float switching valve or the anti-vibration switching valve includes a three-position switching valve, the three-position switching valve including a spool, and wherein the pressure-receiving portion includes: a first pressure-receiving portion arranged on one side of the spool in a longitudinal direction of the spool; and a second pressure-receiving portion arranged on the other side of the spool in the longitudinal direction, and wherein the pilot fluid is applied to the first pressure-receiving portion and the second pressure-receiving portion. ### Claim 9 A hydraulic system for a working machine, comprising: a hydraulic actuator; a float switching valve to perform a floating operation of the hydraulic actuator; and an anti-vibration switching valve to perform an anti-vibration operation of the hydraulic actuator, wherein the float switching valve or the anti-vibration switching valve includes: a solenoid valve to which pilot fluid is supplied; a pressure-receiving portion to receive of the pilot fluid from the solenoid valve; a spool; and an outputting port, wherein the spool includes an outputting portion, and the outputting portion connects the pressure-receiving portion to the outputting port, and drains the pilot fluid in the pressure-receiving portion through the outputting port. ### Claim 10 (depends on 9) The hydraulic system for the working machine according to claim 9, comprising: a first switch to issue a first command of the floating operation; a second switch to issue a second command of the anti-vibration operation; and a control device, wherein the control device is configured to: switch the float switching valve to a first position or to a second position in accordance with the first command; switch the anti-vibration switching valve to the first position or to the second position in accordance with the second command; and not to switch, in warming up of operation fluid, the float switching valve and the anti-vibration switching valve in accordance with the first command and the second command. ### Claim 11 (depends on 10) The hydraulic system for the working machine according to claim 10, wherein the float switching valve or the anti-vibration switching valve includes a three-position switching valve, the three-position switching valve including the spool, and wherein the pressure-receiving portion includes: a first pressure-receiving portion arranged on one side of the spool in a longitudinal direction of the spool; and a second pressure-receiving portion arranged on the other side of the spool in the longitudinal direction, and wherein the pilot fluid is applied to the first pressure-receiving portion and the second pressure-receiving portion. ### Claim 12 (depends on 9) The hydraulic system for the working machine according to claim 9, wherein the float switching valve or the anti-vibration switching valve includes a three-position switching valve, the three-position switching valve including the spool, and wherein the pressure-receiving portion includes: a first pressure-receiving portion arranged on one side of the spool in a longitudinal direction of the spool; and a second pressure-receiving portion arranged on the other side of the spool in the longitudinal direction, and wherein the pilot fluid is applied to the first pressure-receiving portion and the second pressure-receiving portion.