The control function of Hitachi excavator hydraulic pump controller. According to the stroke of the joystick, the displacement of the pump is controlled to reduce the neutral loss and fine control loss. The half-flow mode of the stick automatically set by the working mode provides a fine control function. Cut-off function, cut-off function cancellation and 2-level overflow function together provide a guarantee for reducing overflow loss and increasing excavation power.
1. Flow control function
When the control lever is in the neutral position, the electric signal is sent to the hydraulic pump excavator through the oil pressure switch of the pilot control valve, and the microcomputer in the controller processes the driving signal and sends the driving signal to the hydraulic pump system to make the hydraulic pump capture The amount is controlled to the minimum to reduce the power loss when the control valve is in the neutral position. When the joystick is pulled, the oil pressure switch sends the electrical signal of the corresponding flow command to the hydraulic pump controller according to the stroke of the joystick. The microcomputer in the controller sends the corresponding drive signal to the hydraulic pump system after processing, and the corresponding response is obtained from the surface. The hydraulic pump displacement fine digging performance is improved and the power loss is reduced.
2. Cutoff (C0) function
When the load increases during operation, the outlet pressure of the hydraulic pump rises. When the pressure is close to the overflow pressure, the oil pressure sensor at the outlet sends out a corresponding electrical signal to the controller and sends the corresponding drive signal to the hydraulic pump system after processing by the microcomputer in the controller. , The cut-off (CO) valve performs the cut-off function to reduce the displacement of the hydraulic pump and reduce the overflow loss.
3. Cut-off (CO) cancellation function
The opening or canceling of the cut-off function is automatically determined by the three switches of the maximum power switch, the walking joystick and the rotary lock switch, or one of them is off. When the maximum power switch is in the open position (the working mode switch must be in (HO) or GO), when the walking operating lever is in the operating position and the four-turn locking switch is in the open position, their signal current is sent to the hydraulic pump controller. After the machine is buried, the corresponding drive signal is sent to the hydraulic pump system to make Cut-off (CO) cancels the solenoid valve energization cut-off function. As the load increases during work, the outlet pressure of the hydraulic pump rises and approaches the overflow pressure, and the discharge of the hydraulic pump will not decrease. In this way, the flow rate can be guaranteed. It can also prevent speed reduction.
4. Stick half-flow control function
When the working mode switch is (FO or (L0), the electric signal of the working mode switch of the monitor panel is sent to the hydraulic pump controller. After processing by the microcomputer, the corresponding driving signal is sent to the arm half-flow solenoid valve to make the main operation The operation of the "stick-high speed" operation valve of the four-way reversing valve in the valve stops, and the stick cylinder is only supplied by a single pump at this time, which improves the precision of fine control and finishing operations. This action is limited to the simultaneous action of the boom and the stick, and the half-flow control function does not work when the stick is extended and the bucket is operated at the same time.
5.2 level overflow control function
When the maximum power switch is pushed to the open position (only when the working mode switch is in (HO) or (GO), or the walking joystick is in the operating position, or the rotary lock switch is in the open position, their electrical signals are sent to the hydraulic pump control After processing by the microcomputer, the drive signal is input to the 2-stage overflow C0 to cancel the solenoid valve, at this time the solenoid valve is opened, the cut-off function is canceled, and the pilot pressure oil from the pilot pump flows into the main overflow valve. The pressure is increased from 32.5 MPa to 34 MPa, increasing the digging power and walking force.
6. The control function when the TVC standby switch is on
If the controller or sensor is abnormal, the direct current flows from the battery to the twist control valve. At this time, the displacement of the hydraulic pump is controlled according to the pressure at the outlet of the hydraulic pump. This function can be used to control the driving torque of the hydraulic pump.
7. Turn lock and turn brake control function
When the rotary lock switch is in the OHF position, the rotary brake acts nearly after the rotary joystick is placed in the neutral position. When the rotary joystick is operated, the rotary brake is released and the turntable can rotate freely. When the rotary lock switch is ON In the position, the turntable is braked by the turning brake, even if the joystick is operated, the turning brake will not be eliminated, so the turntable cannot be turned to prevent hydraulic drift after stopping the turning.
When the hydraulic pump controller is abnormal and the rotary brake function is abnormal, the rotary lock backup switch cancels the rotary brake shaft to perform the rotary operation.
When the rotary lock switch is turned to the ON position, the cut-off (CO) function is cancelled. In this case, if the hydraulic system of the working device is in an overflow state, the temperature of the hydraulic oil rises rapidly to reduce the warm-up time.
