# US 11,078,646 B2 · Shovel and control valve for shovel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,078,646 B2 - Document ID: US11078646B2 - Status: Granted - Kind: B2 - Application number: 16/259,034 - Filed: 2019-01-28 - Published: 2019-06-06 - Granted: 2021-08-03 - Earliest claimed: 2016-07-29 - Assignees: Sumitomo(S.H.I.) Construction Machinery Co., Ltd. - Applicants: Sumitomo(S.H.I.) Construction Machinery Co., Ltd. - Inventors: Tomoki Kurokawa - Web page: https://patentgrep.com/patent/US11078646B2 ## CPC - E02F 9/22: Hydraulic or pneumatic drives {(for dipper or bucket arm position control E02F3/43, for blade position control for graders E02F3/844; for turntables E02F9/121; for fork-lift trucks B66F9/22)} - E02F 3/301: {with more than two arms (boom included), e.g. two-part boom with additional dipper-arm} - F15B 11/00: Servomotor systems without provision for follow-up action {; Circuits therefor}(F15B3/00 takes precedence) - F15B 11/02: Systems essentially incorporating special features for controlling the speed or the actuating force of an output member - F15B 11/16: with two or more servomotors - F15B 2211/205: Systems with pumps - F15B 2211/20576: with multiple pumps - F15B 2211/3059: having multiple valves for multiple output members - F15B 2211/30595: with additional valves between the groups of valves for multiple output members - F15B 2211/3116: the pump port being open in the centre position, e.g. so-called open centre - F15B 2211/405: characterised by the type of flow control means or valve - F15B 2211/41554: being connected to a return line and a directional control valve - F15B 2211/41563: being connected to a pressure source and a return line - F15B 2211/45: Control of bleed-off flow, e.g. control of bypass flow to the return line - F15B 2211/7142: the output members being arranged in multiple groups - E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00) - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR ## Abstract A shovel includes a hydraulic pump, multiple hydraulic actuators, a center bypass oil passage supplied with hydraulic oil discharged from the hydraulic pump, multiple directional control valves, and a bleed-off valve. The directional control valves are arranged in tandem in the center bypass oil passage and configured to supply the hydraulic actuators with the hydraulic oil from the center bypass oil passage. At least a directional control valve other than the most downstream directional control valve in the center bypass oil passage among the directional control valves opens the center bypass oil passage. The bleed-off valve is connected to part of the center bypass oil passage upstream of at least one of the directional control valves. ## Claims ### Claim 1 A shovel comprising: a hydraulic pump; a plurality of hydraulic actuators; a center bypass oil passage supplied with hydraulic oil discharged from the hydraulic pump; a plurality of directional control valves arranged in tandem in the center bypass oil passage and configured to supply the plurality of hydraulic actuators with the hydraulic oil from the center bypass oil passage, wherein at least a directional control valve other than a most downstream directional control valve in the center bypass oil passage among the plurality of directional control valves opens the center bypass oil passage; and a bleed-off valve connected to a part of the center bypass oil passage upstream of at least one of the plurality of directional control valves. ### Claim 2 (depends on 1) The shovel as claimed in claim 1, wherein the most downstream directional control valve blocks the center bypass oil passage. ### Claim 3 (depends on 1) The shovel as claimed in claim 1, wherein the center bypass oil passage is blocked on a downstream side of the most downstream directional control valve. ### Claim 4 (depends on 1) The shovel as claimed in claim 1, wherein the center bypass oil passage includes an extra oil passage further downstream of the plurality of directional control valves, and a selector valve configured to switch an open state and a blocked state is provided in the extra oil passage. ### Claim 5 (depends on 1) The shovel as claimed in claim 1, wherein the bleed-off valve is connected to a part of the center bypass oil passage between a first directional control valve and a second directional control valve among the plurality of directional control valves, the first directional control valve corresponding to a hydraulic actuator preferentially caused to operate among the plurality of hydraulic actuators, the second directional control valve being placed downstream of and adjacent to the first directional control valve. ### Claim 6 (depends on 1) The shovel as claimed in claim 1, wherein a spool is included in one of the plurality of directional control valves, a cylinder port connected to one of the plurality of hydraulic actuators, a bridge oil passage connected to the cylinder port in such a manner as to switch between an open state and a closed state in accordance with a change in a position of the spool, and the center bypass oil passage configured to supply the hydraulic oil from the hydraulic pump to the bridge oil passage are formed in the one of the plurality of directional control valves, and the spool is placed in the center bypass oil passage. ### Claim 7 (depends on 6) The shovel as claimed in claim 6, wherein the center bypass oil passage communicates with the bridge oil passage regardless of the position of the spool. ### Claim 8 (depends on 1) The shovel as claimed in claim 1, wherein a directional control valve for traveling configured to supply the hydraulic oil to a traveling hydraulic motor is placed in the center bypass oil passage, and the bleed-off valve is connected to a part of the center bypass oil passage downstream of the directional control valve for traveling. ### Claim 9 (depends on 1) The shovel as claimed in claim 1, wherein, regardless of a position of a spool included in one of the plurality of directional control valves, the hydraulic oil discharged from the hydraulic pump is supplied to another one of the plurality of directional control valves placed downstream of the one of the plurality of directional control valves in the center bypass oil passage. ### Claim 10 A control valve for a shovel, causing a plurality of hydraulic actuators to operate using hydraulic oil discharged from a hydraulic pump, the control valve comprising: a center bypass oil passage supplied with the hydraulic oil discharged from the hydraulic pump; a plurality of directional control valves arranged in tandem in the center bypass oil passage and configured to supply the plurality of hydraulic actuators with the hydraulic oil from the center bypass oil passage, wherein at least a directional control valve other than a most downstream directional control valve in the center bypass oil passage among the plurality of directional control valves opens the center bypass oil passage; and a bleed-off valve connected to a part of the center bypass oil passage upstream of at least one of the plurality of directional control valves. ### Claim 11 (depends on 10) The control valve as claimed in claim 10, wherein the most downstream directional control valve blocks the center bypass oil passage. ### Claim 12 (depends on 10) The control valve as claimed in claim 10, wherein the center bypass oil passage is blocked on a downstream side of the most downstream directional control valve. ### Claim 13 (depends on 10) The control valve as claimed in claim 10, wherein a spool is included in one of the plurality of directional control valves, a cylinder port connected to one of the plurality of hydraulic actuators, a bridge oil passage connected to the cylinder port in such a manner as to switch between an open state and a closed state in accordance with a change in a position of the spool, and the center bypass oil passage configured to supply the hydraulic oil from the hydraulic pump to the bridge oil passage are formed in the one of the plurality of directional control valves, the spool is placed in the center bypass oil passage, and the center bypass oil passage communicates with the bridge oil passage regardless of the position of the spool. ### Claim 14 (depends on 10) The control valve for the shovel as claimed in claim 10, wherein a directional control valve for traveling configured to supply the hydraulic oil to a traveling hydraulic motor is placed in the center bypass oil passage, and the bleed-off valve is connected to a part of the center bypass oil passage downstream of the directional control valve for traveling.