Construction machine

Abstract

An object of the present invention is to provide a construction machine that can reduce particulate matter (PM) or nitrogen oxide (NOx) discharged from an internal combustion engine mounted on the construction machine. The construction machine 200 includes a diesel engine 101 controlled based on a torque command, an electric motor 102 mechanically connected to the diesel engine, an electric energy storage device 111 that supplies electric power to the electric motor, and a hydraulic pump 103 . The construction machine performs work by driving the hydraulic pump using the diesel engine and the electric motor. A speed control device 118 controls a speed of the electric motor 102 based on a speed command. A torque limiter 115 obtains the torque command having a rate of change with time limited based on a torque target.

1 . A construction machine including an internal combustion engine controlled based on a torque command, an electric motor mechanically connected to the internal combustion engine, an electric energy storage device that supplies electric power to the electric motor, and a hydraulic pressure generator, the construction machine performing work by driving the hydraulic pressure generator using the internal combustion engine and the electric motor, the construction machine comprising:
 first control means that controls a speed of the electric motor based on a speed command; and   second control means that obtains the torque command having a rate of change with time limited based on a torque target.   
     
     
         2 . The construction machine according to  claim 1 , wherein
 the internal combustion engine is controlled by a first torque command obtained based on the speed command and the speed of the internal combustion engine, and   the first control means
 calculates a second torque command obtained based on the speed command and the speed of the electric motor, 
   further includes a high-pass filter that removes a low-frequency component including a DC component of the second torque command, and   controls the electric motor based on an output of the high-pass filter.   
     
     
         3 . The construction machine according to  claim 1 , wherein
 the electric motor is speed-controlled by the speed command, and   torque of the internal combustion engine is greater than torque of the electric motor when a rate of change with time in torque of the hydraulic pressure generator is low, and the torque of the electric motor is greater than the torque of the internal combustion engine when the rate of change with time in the torque of the hydraulic pressure generator is high.   
     
     
         4 . The construction machine according to  claim 1 , wherein
 the electric motor is speed-controlled by the speed command, and   a change of a rate of change with time in the torque of the internal combustion engine is higher than a change of a rate of change with time in the torque of the hydraulic pressure generator when the rate of change with time in the torque of the hydraulic pressure generator is low, and the change of the rate of change with time in the torque of the internal combustion engine is lower than the change of the rate of change with time in the torque of the hydraulic pressure generator when the rate of change with time in the torque of the hydraulic pressure generator is high.   
     
     
         5 . The construction machine according to  claim 1 , wherein
 the torque target is obtained based on a charge amount of the electric energy storage device.   
     
     
         6 . A construction machine comprising:
 an internal combustion engine;   an electric motor mechanically connected to the internal combustion engine;   an electric energy storage device that supplies electric power to the electric motor and a hydraulic pressure generator;   the construction machine performing work by driving the hydraulic pressure generator using the internal combustion engine and the electric motor;   wherein the electric motor is speed-controlled by a speed command; and   torque of the internal combustion engine is greater than torque of the electric motor when a rate of change with time in torque of the hydraulic pressure generator is low; and the torque of the electric motor is greater than the torque of the internal combustion engine when the rate of change with time in the torque of the hydraulic pressure generator is high.   
     
     
         7 . A construction machine comprising:
 an internal combustion engine;   an electric motor mechanically connected to the internal combustion engine;   an electric energy storage device that supplies electric power to the electric motor and a hydraulic pressure generator;   the construction machine performing work by driving the hydraulic pressure generator using the internal combustion engine and the electric motor;   wherein the electric motor is speed-controlled by the speed command; and   a change of a rate of change with time in torque of the internal combustion engine is higher than a change of a rate of change with time in torque of the hydraulic pressure generator when the rate of change with time in the torque of the hydraulic pressure generator is low; and the change of the rate of change with time in the torque of the internal combustion engine is lower than the change of the rate of change with time in the torque of the hydraulic pressure generator when the rate of change with time in the torque of the hydraulic pressure generator is high.