# US 11,028,558 B2 · Work vehicle and control method for work vehicle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,028,558 B2 - Document ID: US11028558B2 - Status: Granted - Kind: B2 - Application number: 16/627,041 - Filed: 2019-01-21 - Published: 2020-04-23 - Granted: 2021-06-08 - Earliest claimed: 2018-02-23 - Assignees: Komatsu Ltd. - Applicants: Komatsu Ltd. - Inventors: Takahisa Oasa - Web page: https://patentgrep.com/patent/US11028558B2 ## CPC - E02F 9/2253: {Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission} - F16H 61/421: Motor capacity control by electro-hydraulic control means, e.g. using solenoid valves - E02F 3/431: {for bucket-arms, front-end loaders, dumpers or the like} - E02F 9/2217: {with energy recovery arrangements, e.g. using accumulators, flywheels} - E02F 9/2235: {including an electronic controller} - E02F 9/2246: {Control of prime movers, e.g. depending on the hydraulic load of work tools} - E02F 9/2289: {Closed circuit} - E02F 9/2292: {Systems with two or more pumps} - E02F 9/2296: {Systems with a variable displacement pump} - F16H 61/425: Motor capacity control by electric actuators - F16H 61/431: Pump capacity control by electro-hydraulic control means, e.g. using solenoid valves - F16H 61/435: Pump capacity control by electric actuators - F16H 61/47: for achieving a target output speed - F16H 55/18: Special devices for taking up backlash {(for gears having orbital motion F16H1/2863)} - F16H 55/44: Sheet-metal pulleys - F16H 2059/366: {Engine or motor speed} - F16H 2059/6861: {the pressures, e.g. high, low or differential pressures} - E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00) - F16H: GEARING ## Abstract A controller determines a compensation factor from an operating amount of an accelerator operating member and a hydraulic pressure of at least one of a first circuit and a second circuit. The controller determines a target vehicle speed from the operating amount of the accelerator operating member. The controller determines at least one of a target displacement of a travel pump and a target displacement of a travel motor from the target vehicle speed and the compensation factor. ## Claims ### Claim 1 A work vehicle comprising: an engine; a hydrostatic transmission including a travel pump configured to be driven by the engine, the travel pump including a first pump port and a second pump port, a travel motor including a first motor port and a second motor port, and a hydraulic circuit connecting the travel pump and the travel motor, the hydraulic circuit including a first circuit connecting the first pump port and the first motor port, and a second circuit connecting the second pump port and the second motor port; a pressure sensor configured to output a signal indicative of a hydraulic pressure in at least one of the first circuit and the second circuit, the pressure sensor including a first pressure sensor configured to output a signal indicative of the hydraulic pressure in the first circuit, and a second pressure sensor configured to output a signal indicative of the hydraulic pressure in the second circuit; an accelerator operating member; an accelerator operating sensor configured to output a signal indicative of an operating amount of the accelerator operating member; and a controller configured to receive signals from the pressure sensor and the accelerator operating sensor, the controller being configured to determine a compensation factor from the operating amount of the accelerator operating member and the hydraulic pressures in at least one of the first circuit and the second circuit, determine a target vehicle speed from the operating amount of the accelerator operating member, determine at least one of a target displacement of the travel pump and a target displacement of the travel motor from the target vehicle speed and the compensation factor, determine a target differential pressure between the first circuit and the second circuit from the operating amount of the accelerator operating member, acquire an actual differential pressure between the first circuit and the second circuit from the signal from the first pressure sensor and the signal from the second pressure sensor, and determine the compensation factor based on the target differential pressure and the actual differential pressure. ### Claim 2 (depends on 1) The work vehicle according to claim 1, wherein the controller is further configured to determine the compensation factor based on a ratio between the target differential pressure and the actual differential pressure. ### Claim 3 (depends on 1) A work vehicle according to claim 1, wherein the controller is further configured to determine a target gear ratio of the hydrostatic transmission from the target differential pressure, determine a corrected target gear ratio based on the target gear ratio and the compensation factor, and determine at least one of the target displacement of the travel pump and the target displacement of the travel motor from the corrected target gear ratio. ### Claim 4 (depends on 3) The work vehicle according to claim 3, wherein the controller is further configured to determine the corrected target gear ratio by dividing the target gear ratio by the compensation factor. ### Claim 5 (depends on 1) The work vehicle according to claim 1, wherein the controller is further configured to determine a corrected target vehicle speed based on the target vehicle speed and the compensation factor, and determine at least one of the target displacement of the travel pump and the target displacement of the travel motor from the corrected target vehicle speed. ### Claim 6 (depends on 5) The work vehicle according to claim 5, wherein the controller is further configured to determine the corrected target vehicle speed by multiplying the target vehicle speed by the compensation factor. ### Claim 7 (depends on 1) The work vehicle according to claim 1, wherein the controller is further configured to determine a target rotation speed of the engine from the operating amount of the accelerator operating member, determine a corrected target rotation speed based on the target rotation speed of the engine and the compensation factor, and determine at least one of the target displacement of the travel pump and the target displacement of the travel motor from the corrected target rotation speed. ### Claim 8 (depends on 7) The work vehicle according to claim 7, wherein the controller is further configured to determine the corrected target rotation speed by dividing the target rotation speed of the engine by the compensation factor. ### Claim 9 (depends on 1) The work vehicle according to claim 1, further comprising: a work implement operating member; and a work implement operating sensor configured to output a signal indicative of an operating amount of the work implement operating member, the controller being further configured to receive the signal from the work implement operating sensor, determine a target input horsepower of the hydrostatic transmission from the operating amount of the accelerator operating member, determine the target rotation speed of the engine from the target input horsepower and the operating amount of the work implement operating member, determine a pump target differential pressure indicative of a target value of the differential pressure between the first circuit and the second circuit for the travel motor, from the target input horsepower and the target rotation speed of the engine, determine a motor target differential pressure indicative of a target value of the differential pressure between the first circuit and the second circuit for the travel motor, from the target vehicle speed and the target output horsepower, and determine a larger of the pump target differential pressure and the motor target differential pressure as the target differential pressure. ### Claim 10 A work vehicle comprising: an engine; a hydrostatic transmission including a travel pump configured to be driven by the engine, the travel pump including a first pump port and a second pump port, a travel motor including a first motor port and a second motor port, and a hydraulic circuit connecting the travel pump and the travel motor, the hydraulic circuit including a first circuit connecting the first pump port and the first motor port, and a second circuit connecting the second pump port and the second motor port; a pressure sensor configured to output a signal indicative of a hydraulic pressure in at least one of the first circuit and the second circuit; an accelerator operating member; an accelerator operating sensor configured to output a signal indicative of an operating amount of the accelerator operating member; and a controller configured to receive signals from the pressure sensor and the accelerator operating sensor, the controller being configured to determine a compensation factor from the operating amount of the accelerator operating member and the hydraulic pressures in at least one of the first circuit and the second circuit, determine a target vehicle speed from the operating amount of the accelerator operating member, determine at least one of a target displacement of the travel pump and a target displacement of the travel motor from the target vehicle speed and the compensation factor, determine a primary target value of the displacement of the travel pump from the target vehicle speed, and determine the target displacement of the travel pump based on the primary target value and the compensation factor. ### Claim 11 (depends on 10) The work vehicle according to claim 10, wherein the controller is further configured to determine the target displacement of the travel pump by multiplying the primary target value by the compensation factor. ### Claim 12 A work vehicle comprising: an engine; a hydrostatic transmission including a travel pump configured to be driven by the engine, the travel pump including a first pump port and a second pump port, a travel motor including a first motor port and a second motor port, and a hydraulic circuit connecting the travel pump and the travel motor, the hydraulic circuit including a first circuit connecting the first pump port and the first motor port, and a second circuit connecting the second pump port and the second motor port; a pressure sensor configured to output a signal indicative of a hydraulic pressure in at least one of the first circuit and the second circuit; an accelerator operating member; an accelerator operating sensor configured to output a signal indicative of an operating amount of the accelerator operating member; and a controller configured to receive signals from the pressure sensor and the accelerator operating sensor, the controller being configured to determine a compensation factor from the operating amount of the accelerator operating member and the hydraulic pressures in at least one of the first circuit and the second circuit, determine a target vehicle speed from the operating amount of the accelerator operating member, determine at least one of a target displacement of the travel pump and a target displacement of the travel motor from the target vehicle speed and the compensation factor, determine a primary target value of the displacement of the travel motor from the target vehicle speed, and determine the target displacement of the travel motor based on the primary target value and the compensation factor. ### Claim 13 (depends on 12) The work vehicle according to claim 12, wherein the controller is further configured to determine the target displacement of the travel motor by dividing the primary target value by the compensation factor.