The control block diagram of the Kobelco excavator arm recovery cavitation prevention system is shown in Figure 3.9.
1. When performing the arm recovery operation, the pilot pressure switches the arm spool twice, and at the same time, it is input to the low pressure sensor.
The engine speed command output through the throttle potentiometer is input to the electromechanical controller.
The output voltage of the low-pressure pressure sensor is input to the electromechanical controller, which performs pilot signal processing internally, and outputs the command current corresponding to the input voltage to the small arm variable regeneration proportional valve (PSV-A), as shown in Figure 3.10.
In addition, the command current corresponding to the input voltage from the throttle potentiometer is output to the arm variable regeneration proportional valve
(PSV-A), as shown in Figure 3.11.
The arm variable regeneration proportional valve outputs the secondary pressure of the proportional valve corresponding to the command current from the electromechanical controller to switch the arm variable regeneration spool.
2. P2 side negative pressure sensor (SE-27) and back pressure sensor Qiao E. 28) The output voltage is input to the electromechanical controller, and the negative pressure control signal processing is performed internally, and the command current corresponding to the input voltage is output to the P2 pump proportional country (PSV-P2), as shown in Figure 12
3. The proportional valve of the P2 pump outputs the secondary pressure of the proportional valve corresponding to the command current from the electromechanical controller, and the discharge volume of the P2 pump changes.
The variable regeneration valve arm of the arm is controlled by the direction stroke corresponding to the number of engine revolutions, and the engine speed is reduced by changing the regeneration rate
4. Cavitation will not occur when the discharge volume of the P2 pump is reduced. 0 In addition, during the arm recovery operation, the excitation signal from the electromechanical integrated controller to the rotary parking brake solenoid valve (SV-I) is cut off. , The rotary stop brake is released. Note: 0 and 0 carry out the pilot signal processing in the electromechanical controller, the signal is selected by the high bit. Output to the arm variable regeneration proportional valve.
