Hitachi excavator EC case analysis of motor failure three

Case three

Models: Hitachi EX200-5HHE

Fault phenomenon: after the excavator replaced MC, when the engine started, press the control panel, engine speed, gear button, the EC motor did not move.

Check:

(1) check the new replacement MC, model and so on, accord with the original car, check the MC plugs are connected well.

(2) check the EC motor coil and position sensor resistance are normal.

(3) disconnect the EC motor control line, press the engine speed, the gear button, and use the oscilloscope to measure the waveform of the MC output voltage, and the result is no voltage output.

Handling: MC engine learning program;

(1) turn off the air conditioning switch

(2) switch the key switch to the off position (when the key switch goes to the off position, if the engine does not turn off, it can pull the fuel cut-off handle located below the operator's seat to cause the engine to stall.)

(3) wait for 5 seconds.

(4) wait for 5 seconds after the MC engine switch is switched to the on position.

(5) switch the key to the on position and wait for 5 seconds.

(6) switch the key to the off position and wait for 5 seconds.

(7) switch the MC engine learning switch to the off position.

So far, MC engine learning program is completed, restart the engine, EC motor work properly.

 Analysis: in this case, the EC motor and the MC motor and its control system did not fail, but it showed that the EC motor did not work properly. Originally in this machine and other MC engine learning function of the excavator has this requirement, when the following three cases, MC engine learning program should be carried out: first, removal, maintenance or replacement of MC after. Replacement of EC motor or EC motor is removed and reinstalled. After adjusting the idle speed of engine. Therefore, the operator and maintenance personnel must be familiar with the performance requirements of the machine, can not be a blind demolition of a failure.