Common sense article: Hitachi ZX470LCR-3 excavator hydraulic pump and engine joint control system
Through the joint control of Hitachi excavator hydraulic pump and engine, a high level of power and fuel economy can be achieved. The change of the engine speed causes the engine speed sensor and the throttle control knob output signal to control the current to change accordingly. The hydraulic pump controller counts the output signal and sends the result to the torsion control valve (TvC valve) as a signal to control the flow of the hydraulic pump. In this way, the engine torque can be optimally matched with the driving torque of the hydraulic pump.
1. The control function of working mode selection and power setting selection
Combination of level 4 working mode (HO: heavy duty mode; C.0: general: working mode; F.0: finishing mode; L0: lifting working mode) and 3 power settings (H, S, L) It can be used to determine the driving torque of the hydraulic pump according to the nature of the work, and the engine can be used more effectively while reducing fuel consumption: In general, the working mode is used as the basic mode when the working mode and the power setting are combined, and the power setting can be based on The choice of working method depends on the specific situation.
2, half maximum power control function
When the working mode is set to (HO) or (C.0), press the maximum power switch of the joystick handle h of the working device, no matter which working mode and power setting is selected, the system will switch to HO] and (H, cut-off) The (CO) function is cancelled, and when the pressure is near the overflow pressure value, the flow increases, the pressure of the main overflow valve is increased from 32.5MPa to 34MPa, and the maximum excavation power is increased to give the maximum production capacity. Even if you keep pressing the maximum power switch, the maximum power function will be automatically cancelled after 8.5s, and the system will return to the state before the switch is pressed. When the working mode switch is at (F.0 or (L0), this function does not work. .
3, automatic deceleration control function
(1) The automatic deceleration switch is in the on position.
①The throttle control knob is set at a position higher than 1500r/min, all the joysticks are in the neutral position, and the hydraulic pump controller receives the neutral signal and sends an automatic deceleration signal to the engine throttle controller. After the throttle controller receives this signal, it sends a drive signal to the governor motor. The governor motor returns the fuel injection pump governor lever to the first deceleration position and keeps it for nearly 4s. At this time, the engine speed decreases from the knob position. Around 100r/min
②After the joystick is in the neutral position for 4s, the drive signal is sent from the engine throttle controller to the governor motor again, and the governor rod is pulled back from the first deceleration position and remains at the second deceleration position. At this time, the engine speed is close to 1400/min under deceleration conditions
Operate any joystick, the hydraulic pump excavator receives the signal and cancels the automatic deceleration signal sent to the engine throttle controller. At this time, the ``Engine Oil Wide'' controller sends a drive signal to the governor motor to return the governor lever to the original setting position (2) When the automatic deceleration switch is at the stop position, the engine speed can be set to the throttle control knob. The desired value, even if all the joysticks are in the neutral position, the engine speed will not be reduced by the reduction of the engine speed, reducing fuel consumption and reducing noise.
4, driving speed conversion control function
(1) When the travel speed switch is H (high speed), the travel speed solenoid valve is turned on, and the pilot pressure oil enters the travel hydraulic motor regulator control valve, which reduces the motor swash plate inclination angle, and the system is in a high-speed driving state.
(2) The speed of the engine throttle control knob is set to be less than 1400r/min. When the driving speed switch is driving at the Lo (low speed) position, even if the switch is switched to the H (high speed) position, the driving is still driving at a low speed. When the switch is driving in the H (high speed) position, the driving speed is automatically converted to Io (low speed)
(3) The automatic conversion between H and Lo is carried out according to the outlet pressure of the hydraulic pump. When the driving speed switch is driving in the Hi position, if the excavator is going uphill and the pressure of the walking hydraulic system is higher than 31MPa for more than 1s, the driving speed solenoid valve is closed (not energized), and the driving speed is switched to Lo. The excavator continues to drive at L (the travel speed switch is still in the H position), if it is driven on flat ground or downhill again, and the system pressure is lower than 2MPa for more than 1s, the solenoid valve is opened (energized), and the speed is switched to high speed again .
