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AssigneeHitachi Construction Machinery Co., Ltd.
InventorsHirotsugu Kasuya, Yutaka Watanabe, Masami Ochiai
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In a pump fault diagnostic apparatus for a hydraulic drive system, it is possible to make a fault diagnosis of hydraulic pumps automatically during an actual operation of a working machine and to detect a fault when there is a problem with horsepower limiting control of the hydraulic pumps as well. A controller 50 performs horsepower limiting control for a plurality of variable displacement hydraulic pumps 1 to 6. Measuring units 21 to 26 each equipped with a pressure sensor 221a and displacement sensor 221b are provided in delivery lines of the hydraulic pumps 1 to 6, and the controller 50 measures a pump delivery pressure and pump delivery rate of each hydraulic pump when the pump delivery rate reaches a maximum during operation of the hydraulic drive system based on their detected values, collects the measured values as fault diagnostic data, and calculates a target pump delivery rate of horsepower limiting control corresponding to the collected pump delivery pressure of each hydraulic pump, and then compares the target pump delivery rate and the collected pump delivery rate to decide fault of the hydraulic pump.
A pump fault diagnostic apparatus for a hydraulic drive system having at least one variable displacement hydraulic pump (1 to 6) and horsepower limiting control means (1a to 6a, 11 to 16, 50) for controlling said hydraulic pumps such that a maximum pump delivery rate is reduced as a delivery pressure of said hydraulic pump increases, wherein said apparatus comprises:
A pump fault diagnostic apparatus for a hydraulic drive system having a plurality of variable displacement hydraulic pumps (1 to 6) and horsepower limiting control means (1a to 6a, 11 to 16, 50) for controlling the plurality of hydraulic pumps such that respective maximum pump delivery rates are reduced as respective delivery pressures of said hydraulic pumps increase, wherein said apparatus comprises:
A display unit (60) of a pump fault diagnostic apparatus for a hydraulic drive system having a plurality of variable displacement hydraulic pumps (1 to 6) and horsepower limiting control means (1a to 6a, 11 to 16, 50) for controlling a plurality of hydraulic pumps such that a maximum pump delivery rate is reduced as delivery pressures of these hydraulic pumps increase, wherein:
Dependencies are inferred from the claim text.