1. Sumitomo excavator reverse control loop (energy-saving solenoid valve OFF)
When the control lever 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, passes through the central bypass oil circuit, and passes through the reverse control variable relief valve located at the bottom. , Return to the hydraulic oil discharged from the pilot pump A3, enter the P port of the 5-link solenoid valve, pass through the energy-saving solenoid valve, and supply to the Pnl and Pn2 ports of the control valve to reverse the P1 and P2 control of the relief valve. The set pressure is maintained at 2.55MPa and the reverse control hydraulic oil diverted from the center bypass oil circuit is supplied from the Ps1 and Ps2 ports to the hydraulic pump Pi1Pi2 port, so that the inclination angle of the hydraulic pump is turned to the side of the small flow. Thereby reducing the oil displacement of the hydraulic pump and the reverse control circuit.
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 the joystick of the remote control valve is placed in the neutral position, the travel pilot pressure sensor and the upper body pilot pressure sensor installed on the PT port and PA port of the control valve 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 from the Pl and Pn2 ports of the reverse control relief valve of the control valve is switched, and the hydraulic oil 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, and the discharge pressure of the hydraulic pumps A1 and A2 is further reduced. If this state is maintained, the reverse control signal will be cut off, and the hydraulic pumps P1 and P2 will be cut off. The oil displacement will increase. Therefore, the hydraulic oil from the pilot pump A3 will enter the P port of the 5-link solenoid valve, flow through the energy-saving solenoid valve, and be supplied from the C5 port to the P2 port of the hydraulic pump, making the A2 side hydraulic pump At the same time, the controller sends a signal to the proportional valve for limiting the flow rate of the hydraulic pump Pl. According to this signal, the hydraulic oil discharged from the pilot pump A3 is supplied to the hydraulic pump. Pump P1 port, so that the inclination angle of the hydraulic pump on the A1 side is turned to the minimum flow side, so as to feed the oil displacement of the hydraulic pump and reverse the energy-saving circuit (energy-saving solenoid valve ON)
3. Reverse control loop (bucket closed, energy-saving solenoid valve OFF)
Bucket closing operation: move the remote control valve to the closing side of the bucket, the pilot hydraulic oil is supplied to the pb7 port of the control valve through the damping valve, and the bucket slide valve is switched to the closed side. The hydraulic oil discharged from the hydraulic pump A2 enters the control The valve wide oil port is supplied to the bucket slide valve. Through the switching of the slide valve, the hydraulic oil flows into the bottom of the bucket cylinder. At the same time as the bucket is closed, the pilot pressure sensor signal of the upper body is detected. According to the signal output by the controller, the energy-saving solenoid valve OFF, the pilot hydraulic oil flows into the reverse control relief valve, and the set pressure becomes 2.55MPa. Because the bucket slide 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 from the Ps2 port and turns the tilt angle of the hydraulic pump to the side where the flow rate is increased, thereby increasing the flow rate.
In addition, although the command current flowing into the proportional valve for flow control of the hydraulic pump is reduced, the hydraulic oil flowing from the hydraulic pump A3 is cut off, but the hydraulic oil is reversely controlled to flow from the control valve Ps1 port to the Pil port, so that the hydraulic pump The tilt angle is turned to the minimum flow side, thereby reducing the oil displacement of hydraulic pump A1. Reverse control circuit (bucket closed, energy-saving solenoid valve OFF).
