# US 11,306,445 B2 · Hydraulic system for a working machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,306,445 B2 - Document ID: US11306445B2 - Status: Granted - Kind: B2 - Application number: 16/619,608 - Filed: 2017-06-07 - Published: 2020-05-21 - Granted: 2022-04-19 - Earliest claimed: 2017-06-07 - Assignees: Volvo Construction Equipment AB - Applicants: Volvo Construction Equipment AB - Inventors: Roland Wiktor - Web page: https://patentgrep.com/patent/US11306445B2 ## CPC - E01C 19/286: {Vibration or impact-imparting means; Arrangement, mounting or adjustment thereof; Construction or mounting of the rolling elements, transmission or drive thereto, e.g. to vibrator mounted inside the roll (E01C19/287 and E01C19/288 take precedence)} - E02F 9/2296: {Systems with a variable displacement pump} - E01C 19/28: Vibrated rollers or rollers subjected to impacts, e.g. hammering blows ({E01C19/235, } E01C19/29, {E01C19/41} take precedence; {combined with non-vibrated elastically-deformable rolling elements E01C19/233}) - E01C 21/00: Apparatus or processes for surface {soil} stabilisation for road building or like purposes, e.g. mixing local aggregate with binder ({recycling in place or on the road involving soil stabilisation E01C23/065} ; stabilising soil under existing surfacing E01C23/10; soil-conditioning or soil-stabilising materials C09K17/00; soil consolidation in general E02D3/12) - E02F 9/2235: {including an electronic controller} - E02F 9/2253: {Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission} - E02F 9/2289: {Closed circuit} - E02F 9/2292: {Systems with two or more pumps} - F15B 1/02: Installations or systems with accumulators - F15B 11/161: {with sensing of servomotor demand or load} - F15B 11/20: controlling several interacting or sequentially-operating members - F15B 18/00: Parallel arrangements of independent servomotor systems - F16H 61/425: Motor capacity control by electric actuators - F16H 61/435: Pump capacity control by electric actuators - F15B 2201/00: Accumulators - E01C: CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR (forming roads or like surfaces by compacting or grading snow or ice E01H) - 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 - F16H: GEARING ## Abstract A hydraulic system for a working machine includes a feeding pump; and a plurality of variable displacement hydraulic machines being connected in parallel to the feeding pump; At least one of the variable displacement hydraulic machines is adapted to drive a ground engagement element of the working machine, and at least one of the variable displacement hydraulic machines is adapted to drive a vibrator for vibrating a ground engagement element of the working machine. ## Claims ### Claim 1 A hydraulic system for a working machine, said hydraulic system comprising: a feeding pump: a plurality of variable displacement hydraulic machines being connected in parallel to said feeding pump; a first one of said variable displacement hydraulic machines being adapted to drive a ground engagement element of said working machine, and a second one of said variable displacement hydraulic machines being adapted to drive a vibrator for vibrating the ground engagement element of said working machine; a speed sensor adapted to determine a value indicative of a rotational speed of the first one of the variable displacement hydraulic machines; a displacement sensor adapted to determine a value of an actual displacement of the first one of said variable displacement hydraulic machines; and a control unit configured to operate the first one of the variable displacement hydraulic machines in response to outputs of the speed sensor and the displacement sensor to drive the ground engagement element in order to obtain a desired driving condition. ### Claim 2 (depends on 1) The hydraulic system according to claim 1, wherein said plurality of variable displacement hydraulic machines is connected to said feeding pump in parallel through a circuit conduit assembly; and wherein said circuit conduit assembly comprises a high pressure line and a low pressure line, wherein said feeding pump comprises a high pressure side and a low pressure side, wherein said high pressure line fluidly connects each one of said plurality of variable displacement hydraulic machines to said high pressure side, wherein said low pressure line fluidly connects each one of said plurality of variable displacement hydraulic machines to said low pressure side, wherein said hydraulic system comprises a first pressure sensor and a second pressure sensor, wherein said first pressure sensor is adapted to issue a high pressure signal indicative of fluid pressure in said high pressure line, wherein said second pressure sensor is adapted to issue a low pressure signal indicative of the fluid pressure in said low pressure line. ### Claim 3 (depends on 2) The hydraulic system according to claim 2, wherein said circuit conduit assembly comprises an accumulator. ### Claim 4 (depends on 1) The hydraulic system according to claim 1, wherein the first one of said variable displacement hydraulic machines is adapted to operate both as a hydraulic pump and as a hydraulic motor. ### Claim 5 (depends on 1) The hydraulic system according to claim 1, wherein said hydraulic system comprises a set of displacement control devices, each displacement control device being adapted to control the displacement of one of said variable displacement hydraulic machines. ### Claim 6 (depends on 5) The hydraulic system according to claim 5, wherein the control unit is adapted to issue a signal to each displacement control device in said set of displacement control devices. ### Claim 7 (depends on 1) The hydraulic system according to claim 1, wherein the ground engagement element is a compactor drum. ### Claim 8 (depends on 1) The hydraulic system according to claim 1, wherein said feeding pump has a variable displacement. ### Claim 9 (depends on 1) A powertrain comprising a power source and a hydraulic system according to claim 1, said power source being operably connected to said feeding pump of said hydraulic system. ### Claim 10 (depends on 1, 9) A working machine comprising a powertrain according to claim 9 and/or a hydraulic system according to claim 1. ### Claim 11 (depends on 10) The working machine according to claim 10 comprising a set of ground engagement elements, wherein said set of ground engagement elements comprises at least one of a wheel and a compactor drum. ### Claim 12 A method for operating a working machine comprising a powertrain which in turn comprises a power source and a hydraulic system, said hydraulic system comprising: a feeding pump operably connected to said power source; a plurality of variable displacement hydraulic machines being connected in parallel to said feeding pump; at least a first one of said variable displacement hydraulic machines being adapted to drive a ground engagement element of said working machine, and at least a second one of said variable displacement hydraulic machines being adapted to drive a vibrator for vibrating a ground engagement element of said working machine, wherein said hydraulic system comprises a speed sensor adapted to determine a value indicative of a rotational speed of the first one of said variable displacement hydraulic machines and a displacement sensor adapted to determine a value of an actual displacement of the first one of said variable displacement hydraulic machines, said method comprising: determining a desired driving condition of said working machine, receiving inputs from said speed sensor and said displacement sensor, and operating at least said power source and each one of said variable displacement hydraulic machines being adapted to drive a ground engagement element in response to said inputs from said speed sensor and said displacement sensor in order to obtain said desired driving condition. ### Claim 13 (depends on 12) The method according to claim 12, wherein said plurality of variable displacement hydraulic machines is connected to said feeding pump in parallel through a circuit conduit assembly, and wherein said circuit conduit assembly comprises an accumulator, said method further comprising: upon determination that said desired driving condition of said working machine is braking said working machine, controlling at least one of said variable displacement hydraulic machines that is adapted to drive a ground engagement element of said working machine so as to operate as a hydraulic pump for feeding fluid to said accumulator. ### Claim 14 A control unit for operating a working machine comprising a powertrain which in turn comprises a power source and a hydraulic system, said hydraulic system comprising: a feeding pump operably connected to said power source; a plurality of variable displacement hydraulic machines being connected in parallel to said feeding pump; at least a first one of said variable displacement hydraulic machines being adapted to drive a ground engagement element of said working machine, and at least a second one of said variable displacement hydraulic machines being adapted to drive a vibrator for vibrating a ground engagement element of said working machine, wherein said hydraulic system comprises a speed sensor adapted to determine a value indicative of a rotational speed of the first one of said variable displacement hydraulic machines and a displacement sensor adapted to determine a value of an actual displacement of the first one of said variable displacement hydraulic machines, said control unit being adapted to: receive information indicative of a desired driving condition of said working machine, receiving inputs from said speed, sensor and said displacement sensor, and issue a signal to at least said power source and to each one of said variable displacement hydraulic machines being adapted to drive a ground engagement element in response to said inputs from said speed sensor and said displacement sensor so that they are operated in order to obtain said desired driving condition.