1. Reverse control circuit of Sumitomo excavator (energy-saving solenoid valve OFF)
When the joystick of the remote control valve is in the neutral position, the hydraulic oil discharged from the hydraulic pumps A and A2 passes through the control valve PI and P ports, through the center bypass oil passage, and through the reverse control variable relief valve at the bottom , Return to the hydraulic oil discharged from the pilot pump A3, enter the P port of the 5 solenoid valve, pass the energy-saving solenoid valve, and supply the Pnl and Pn2 ports of the control valve to reverse the P1 and P2 to control the relief valve. The set pressure is maintained at 2.55 MPa. The reverse control hydraulic oil shunted through the center bypass oil channel is supplied from the Ps1 and Ps2 ports to the hydraulic pump Pi1Pi2 port, so that the tilt angle of the hydraulic pump is turned to the small flow side. The reverse control circuit diagram to reduce the oil discharge of the hydraulic pump is shown in Figure 3-21.
2. Reverse control energy-saving circuit (energy-saving solenoid valve ON)
The control loop can reduce the back pressure according to the reverse control signal to reduce fuel consumption during standby.
After placing the joystick of the remote control valve in the neutral position, the walking pilot pressure sensor installed on the PT port and PA port of the control valve and the pilot pressure sensor on the upper body send the non-operating state signal to the controller. After about 1s, according to the signal output by the controller, the energy-saving solenoid valve is turned on, and the hydraulic oil flowing out of the Pl and Pn2 ports of the reverse control relief valve of the control valve is switched, passes through the energy-saving solenoid valve, and returns to the hydraulic oil tank. As a result, the set pressure of the reverse control relief valve is switched to a low pressure, further reducing the discharge pressure of the hydraulic pumps A1 and A2.If this state is maintained all the time, the reverse control signal will be cut off and the hydraulic pumps P1 and P2 The oil displacement will increase.Therefore, the hydraulic oil from the pilot pump A3 will enter the P port of the 5 solenoid valve, flow through the energy-saving solenoid valve, and be supplied from the C5 port to the P2 port of the hydraulic pump, so that the A2 side hydraulic pump The inclination angle of the valve is turned to the minimum flow side, thereby reducing the oil discharge of the hydraulic pump.At the same time, the controller sends a signal to the proportional valve for the flow limitation of the hydraulic pump Pl. According to this signal, the liquid discharged from the pilot pump A3 is supplied to the hydraulic pressure. Pump P1 oil port, the tilt angle of the hydraulic pump on the A1 side is turned to the minimum flow side, so that the oil discharge amount of the hydraulic pump is reversed to control the energy-saving circuit (energy-saving solenoid valve ON).Figure 3-22 shows
3. Reverse control circuit (bucket closed, energy-saving solenoid valve OFF)
Bucket closing operation: Move the remote control valve to the bucket closing side, the pilot hydraulic oil is supplied to the pb7 port of the control valve through the shock valve, switch the bucket spool valve to the closing side, and the hydraulic oil discharged from the hydraulic pump A2 enters the control The valve has a wide oil port, which is supplied to the bucket spool valve.Through the switching of the spool valve, hydraulic oil flows into the bottom of the bucket cylinder.At the same time, the bucket is closed, and the signal of the pilot pressure sensor of the upper body is detected. OFF, the pilot hydraulic oil flows into the reverse control relief valve, and the set pressure becomes 2.55MPa.Because the bucket spool valve is switched, the hydraulic oil downstream of the center bypass oil path is cut off, so the hydraulic pump Pi2 reverse control hydraulic oil will not It flows out of the Ps2 oil port and turns the tilt angle of the hydraulic pump to the side where the flow increases, thereby increasing the flow.
In addition, although the command current flowing into the flow control proportional valve of the hydraulic pump is reduced, the hydraulic oil flowing out of the hydraulic pump A3 is cut off, but the reverse control hydraulic oil flows from the control valve Ps1 port to the Pil port to make the hydraulic pump The inclination angle is turned to the minimum flow side, thereby reducing the oil discharge of the hydraulic pump A1. The reverse control circuit (bucket closed, energy-saving solenoid valve OFF) is shown in Figure 3-23.
