1. During the bucket recovery operation of the Kobelco excavator, the pilot switches the bucket spool twice, and at the same time, it is input to the low-pressure pressure sensor (SE-I.SE-2).
2. The output voltage of the low-pressure pressure sensor is input to the electromechanical controller, and the pilot signal processing is performed internally, and the command current corresponding to the input flash is output to the P2 cut-off proportional valve (PSV-B) and the straight-travel proportional valve (PSV-C) , As shown in Figure 3.21
3. P2 cut-off ratio (PSV-B) and straight-travel proportional valve law S№0, output the proportional valve 2 times pressure corresponding to the command current of the electromechanical controller, switch P2 cut-off spool and straight-travel spool,
4. Due to the switching of the bucket spool and P2 cut-off spool, the negative pressure control pressure changes, and this pressure is input to the PI and P2 negative pressure sensors (SE-26, SE-27) and back pressure sensor (SE.28 Dragon
5. The output voltage of the PI and P2 side negative pressure sensor and back pressure sensor is input to the electromechanical controller, and the negative pressure control signal processing is performed internally, and the output is output to the PI pump proportional valve (PSV-PI) and the P2 pump proportional valve (PSV? P2), as shown in Figure 3.23.
6. PI pump proportional valve and P2 pump proportional valve output the proportional pressure of the proportional valve corresponding to the command current of the electromechanical controller twice, so that the displacement of the PI pump and P2 pump changes
7. Switch the dig comma through the pure hydraulic command (pilot 2 times pressure), add the overcurrent hydraulic command (proportional valve 2 times pressure) to switch the straight spool and P2 cut spool. In this way, the discharge pump of the P2 pump is merged into the discharge oil of the PI pump during bucket recovery or lifting operation.
