# US 2017/0284064 A1 · Construction machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0284064 A1 - Document ID: US20170284064A1 - Status: Published application - Kind: A1 - Application number: 15/506,894 - Filed: 2015-03-16 - Published: 2017-10-05 - Earliest claimed: 2015-03-16 - Assignees: Hitachi Construction Machinery Co., Ltd. - Applicants: Hitachi Construction Machinery Co., Ltd. - Inventors: Seiji HIJIKATA; Kouji ISHIKAWA; Yasutaka TSURUGA; Masatoshi HOSHINO; Kiwamu TAKAHASHI - Web page: https://patentgrep.com/patent/US20170284064A1 ## CPC - E02F 9/2217: {with energy recovery arrangements, e.g. using accumulators, flywheels} - E02F 9/2228: {including an electronic controller} - E02F 9/2267: {Valves or distributors (position of valves arrangements on upper-structures E02F9/0875)} - E02F 9/2285: {Pilot-operated systems} - E02F 9/2296: {Systems with a variable displacement pump} - F15B 1/024: {used as a supplementary power source, e.g. to store energy in idle periods to balance pump load} - F15B 13/0433: {the pilot valves being pressure control valves (F15B13/0435, F15B13/0436, F15B13/0438 take precedence)} - F15B 21/14: Energy-recuperation means - E02F 9/2012: {Setting the functions of the control levers, e.g. changing assigned functions among operations levers, setting functions dependent on the operator or seat orientation} - E02F 9/2225: {using pressure-compensating valves} - F15B 2013/0428: {with switchable internal or external pilot pressure source} - F15B 2211/20546: variable capacity - F15B 2211/212: the pressure sources being accumulators - F15B 2211/50536: using unloading valves controlling the supply pressure by diverting fluid to the return line - F15B 2211/50554: the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing valve - F15B 2211/6316: the pressure being a pilot pressure - F15B 2211/6355: having valve means - F15B 2211/67: Methods for controlling pilot pressure - F15B 2211/88: Control measures for saving energy - 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 The construction machine includes: a control valve that switchingly supplies hydraulic fluid from a hydraulic pump to a hydraulic actuator; a control valve drive device that supplies pilot secondary hydraulic fluid to the control valve in accordance with an operation of an operation lever device; a pilot hydraulic pump that supplies pilot primary hydraulic fluid to the control valve drive device; a pressure accumulation device that recovers return hydraulic fluid returned from the hydraulic actuator. The construction machine further includes: a check valve provided in a line between the pilot hydraulic pump and the control valve drive device; a pressure reducing valve that supplied the hydraulic fluid accumulated in the pressure accumulation device; a flow rate reduction device; and a controller that controls the flow rate reduction device in accordance with the pressure in the line between the check valve and the control valve drive device. ## Claims ### Claim 1 A construction machine comprising: a hydraulic actuator; a hydraulic pump that supplies hydraulic fluid to the hydraulic actuator; a control valve that switchingly supplies the hydraulic fluid from the hydraulic pump to the hydraulic actuator; an operation lever device that switchingly operates the control valve; a control valve drive device that supplies pilot secondary hydraulic fluid to the control valve in accordance with an operation of the operation lever device; a pilot hydraulic pump that supplies pilot primary hydraulic fluid to the control valve drive device; and a pressure accumulation device that recovers return hydraulic fluid returned from the hydraulic actuator, wherein the construction machine further comprises: a check valve provided in a line between the pilot hydraulic pump and the control valve drive device; a pressure reducing valve that supplies the hydraulic fluid accumulated in the pressure accumulation device to a line between the check valve and the control valve drive device; a flow rate reduction device capable of reducing flow rate of the hydraulic fluid delivered by the pilot hydraulic pump; a pressure detection device capable of detecting pressure in the line between the check valve and the control valve drive device; and a controller that controls the flow rate reduction device in accordance with the pressure detected by the pressure detection device. ### Claim 2 (depends on 1) The construction machine according to claim 1, wherein the flow rate reduction device is an unloading valve provided in a line between the pilot hydraulic pump and a tank, and the unloading valve is controlled by a command signal from the controller. ### Claim 3 (depends on 1) The construction machine according to claim 1, further comprising a pressure increasing device that increases the pressure in the pressure accumulation device by leading the hydraulic fluid delivered by the pilot hydraulic pump to the pressure accumulation device. ### Claim 4 (depends on 1) The construction machine according to claim 1, further comprising a regeneration control valve that is provided in a line between the hydraulic actuator and the pressure accumulation device and has an opening controlled by the controller, wherein the controller closes the opening of the regeneration control valve when an abnormal high pressure exceeding a preset pressure is detected by the pressure detection device.