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Hybrid construction machine

  • US 10,006,473 B2
  • Filed: 06/03/2015
  • Issued: 06/26/2018
  • Est. Priority Date: 06/05/2014
  • Status: Active Grant
First Claim
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1. A hybrid construction machine comprising:

  • a swing structure;

    a hydraulic pump;

    a hydraulic swing motor driving the swing structure using hydraulic fluid from the hydraulic pump;

    an electric swing motor driving the swing structure in conjunction with the hydraulic swing motor;

    a boom cylinder operated simultaneously with the swing structure at times and driven by the hydraulic fluid from the hydraulic pump;

    first sensors to detect a presence or absence of a boom raising operation by the boom cylinder;

    second sensors to detect a presence or absence of a swing operation of the swing structure;

    a first directional control valve for meter-in control controlling flow of the hydraulic fluid supplied from the hydraulic pump to the hydraulic swing motor;

    a second directional control valve for meter-out control controlling the flow of the hydraulic fluid returning from the hydraulic swing motor;

    at least one pressure reducing valve regulating operation of the first directional control valve for meter-in control; and

    a controller for controlling the at least one pressure reducing valve;

    wherein, the controller, upon judging that a combined swing operation is performed in which the boom cylinder is operated simultaneously with the swing structure based on a detection result by the first and the second detectors, prevents the operation of the first directional control valve for meter-in control with the at least one pressure reducing valve, thereby causing the swing structure to be driven by the electric swing motor alone, andthe flow of the hydraulic fluid returning from the hydraulic swing motor is controlled by a switching operation of the second directional control valve for meter-out control.

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