Construction Machine, Hybrid Hydraulic Excavator, And Output Torque Control Method For Motor Generator

Abstract

A construction machine includes a swing speed detection unit that detects an actual swing speed of an upper structure, a lever command speed calculation unit that calculates a lever command speed based on an operation amount of a swing lever for swinging the upper structure, a torque command value calculation unit that calculates a torque command value based on a command speed based on the calculated lever command speed, a command value output unit that outputs a command torque to a rotary motor generator based on the torque command value calculated by the torque command value calculation unit and the swing speed detected by the swing speed detection unit, and a command value output restriction unit that restricts the output of the torque command value from the command value output unit under predetermined conditions.

1 . A construction machine comprising:
 an undercarriage;   an upper structure swingably provided to the undercarriage and driven by a motor generator;   working equipment provided to the upper structure;   a swing speed detection unit configured to detect an actual swing speed of the upper structure;   a lever command speed calculation unit configured to calculate a lever command speed based on an operation amount of a swing lever configured to swing the upper structure;   a torque command value calculation unit configured to calculate a torque command value based on a command speed based on the calculated lever command speed;   a command value output unit configured to output the torque command value to the motor generator based on the torque command value calculated by the torque command value calculation unit and the swing speed detected by the swing speed detection unit; and   a command value output restriction unit configured to restrict the output of the torque command value from the command value output unit when:   the actual rotation speed detected by the rotary speed detection unit is smaller than a first threshold;   a deviation between the lever command speed calculated by the lever command speed calculation unit and the actual swing speed detected by the swing speed detection unit is greater than a second threshold; and   the lever command speed calculated by the lever command speed calculation unit is smaller than a predetermined value.   
     
     
         2 . The construction machine according to  claim 1 , wherein
 the command value output restriction unit is configured to restrict the output of the torque command value when the lever command speed calculated by the lever command speed calculation unit is zero.   
     
     
         3 . The construction machine according to  claim 1 , further comprising:
 a jerk command speed calculation unit configured to calculate a jerk command speed including a gradient for an acceleration or deceleration of the upper structure based on the lever command speed calculated by the lever command speed calculation unit, wherein   the command value output restriction unit restricts the output of the torque command value from the command value output unit when the jerk command speed calculated by the jerk command speed calculation unit is smaller than a third threshold.   
     
     
         4 . The construction machine according to  claim 3 , further comprising:
 a reaction-force control command speed calculation unit configured to calculate a reaction-force control command speed usable for a position control of the upper structure with reference to a current position of the motor generator, wherein   the command value output restriction unit restricts the output of the torque command value from the command value output restriction unit when the reaction-force control command speed calculated by the reaction-force control command speed calculation unit is smaller than the jerk command speed calculated by the jerk command speed calculation unit.   
     
     
         5 . A hybrid hydraulic excavator comprising:
 an undercarriage;   an upper structure swingably provided to the undercarriage and driven by a motor generator; and   working equipment provided to the upper structure, the working equipment comprising a boom swingably provided to the upper structure, an arm swingably provided to the boom, and a bucket swingably provided to the arm, wherein   an electric power is transferred between the motor generator and a rechargeable battery or a generator motor, and   the boom, the arm, and the bucket are hydraulically driven, the hybrid hydraulic excavator further comprising:   a swing speed detection unit configured to detect an actual swing speed of the upper structure;   a lever command speed calculation unit configured to calculate a lever command speed based on an operation amount of a swing lever configured to swing the upper structure;   a torque command value calculation unit configured to calculate a torque command value based on a command speed based on the calculated lever command speed;   a command value output unit configured to output the torque command value to the motor generator based on the torque command value calculated by the torque command value calculation unit and the swing speed detected by the swing speed detection unit; and   a command value output restriction unit configured to restrict the output of the torque command value from the command value output unit when:   the actual rotation speed detected by the rotary speed detection unit is smaller than a first threshold;   a deviation between the lever command speed calculated by the lever command speed calculation unit and the actual swing speed detected by the swing speed detection unit is greater than a second threshold; and   the lever command speed calculated by the lever command speed calculation unit is smaller than a predetermined value.   
     
     
         6 . An output torque control method for a motor generator performed in a construction machine comprising: an undercarriage; an upper structure swingably provided to the undercarriage and driven by the motor generator; working equipment provided to the upper structure; and a controller, the method comprising steps below performed by the controller of the construction machine:
 detecting an actual swing speed of the upper structure;   calculating a lever command speed based on an operation amount of a swing lever configured to swing the upper structure;   calculating a torque command value based on the calculated lever command speed;   outputting the torque command value to the motor generator based on the calculated torque command value and the detected actual swing speed of the upper structure; and   restricting the output of the torque command value to the motor generator when:   the detected actual swing speed is smaller than a first threshold;   a deviation between the calculated lever command speed and the detected actual swing speed is greater than a second threshold; and   the calculated lever command speed is smaller than a predetermined value.