1. Flow control
As shown in Figure 3-37, the pump's oil displacement can be arbitrarily controlled according to the pilot pressure P
(1) Flow reduction
After the pilot pressure P increases, the pilot piston moves to the right and stops at a position where the pilot spring force and hydraulic pressure balance. The pin fixed on the rod 2 is embedded in the groove part of the pilot piston, and as the pilot piston moves, the rod 2 rotates with the part B (the fulcrum cock and the pin fixed) as a fulcrum. The pin fixed to the feedback lever 2 protrudes from the large hole portion (position C) of the lever 2 and the pin moves to the right.
The pin fixed on the rotating pin used to move the swash plate is embedded in the two wide faces (part D) of the feedback lever. Therefore, as the pin (897) moves, the feedback lever rotates around the part D as a fulcrum. Since the spool valve is connected to the feedback lever via a pin, the spool valve moves to the right.
After the spool valve moves, the oil discharge pressure P mountain passes through the spool valve and Cl port and is introduced into the large piston bore chamber of the servo piston. The oil discharge pressure is introduced into the small-diameter chamber of the servo piston at any time. As a result, due to the difference in the area of the large and small-diameter chamber, the servo piston moves to the right. After the flow servo piston moves to the right, the part D also moves to the right. A return spring is installed on the spool, and the spring force pulls the spool to the left at any time, so the pin is pushed to the large hole portion (position C) of the rod 2. Therefore, with the movement of part D, the feedback lever rotates with part C as the fulcrum, and the spool moves to the left. Through this movement, the openings of the sleeve and the slide valve begin to close slowly, and the servo piston stops moving at the position where the opening is completely closed.
(2) Increased flow
After the pilot pressure P is reduced, the pilot piston is moved to the left by the force of the pilot spring, and the rod 2 rotates with the part B as a fulcrum. The pin is pressed into the large hole part (C part) of the lever 2 by the return spring through the spool, pin and feedback lever, so as the lever 2 rotates, the feedback lever rotates with the D part as a fulcrum, and the spool moves to the left After the valve moves, the CI port opens to the tank port, the pressure of the large bore chamber of the servo piston is evacuated, and the oil discharge pressure Pa of the small bore area moves the servo piston to the left, causing the flow rate to increase as the servo piston moves The D part also moves to the left, the feedback lever rotates with the C part as the fulcrum, and the spool moves to the right. The servo piston will keep moving until the opening of the spool and the sleeve is completely closed.
(3) High voltage selection function
The pilot pressure P is used as a flow control signal.From the multiple command pressures, the selected KR3G9Y04IVV can be introduced through the shuttle valve auxiliary valve to select high pressure from P1 and the proportional valve secondary pressure, while KR3G9X04HV is selected from P2 and the external command pressure P2 Choose high pressure
1. Output power control
Output power control is shown in Figure 3-38. After the load pressure is increased, the inclination angle of the pump is reduced to avoid overloading the prime mover. The regulator is a synchronous full output power control method, and the tilt angle (working volume) of the two pumps is controlled by the same value.
The operation of output power control is the same as that of flow control. The following is a brief description.
(1) Prevent overload operation
When the oil discharge pressure Pa1 of the self-pump or the oil discharge pressure P of the other pump rises, since Pt and Pa act on the stepped portion of the compensation piston, the compensation connecting rod is pushed to the right and moves to the spring of the outer spring and the inner spring The position where the force and hydraulic pressure are balanced. The movement of the compensation link is transmitted to the lever 1 through the pin, and the lever 1 rotates around the pin (part E) fixed on the housing. The pin fixed on the feedback lever protrudes from the large hole part (part F) of the lever 1. As the lever 1 rotates, the feedback lever rotates with the part D as a fulcrum, which causes the slide valve to move to the right.
After the spool valve moves, the oil discharge pressure Pa1 is introduced into the large-bore part of the servo piston through the CI port.The servo piston moves to the right to reduce the pump's oil discharge and prevent the movement of the servo piston from overloading the prime mover. When it is transmitted to the feedback lever, the feedback lever rotates with the F part as a fulcrum, and the slide valve moves to the left. The servo piston will keep moving until the openings of the spool and sleeve are completely closed and will stop moving
(2) Fully automatic flow recovery
After the discharge pressure P4 of the pump or the discharge pressure Pa2 of the force pump is reduced, the outer spring and the inner spring push the compensating connecting rod back to the original position, and the rod 1 rotates around the E part. As the lever 1 rotates, the feedback lever rotates with the part D as a fulcrum, and the slide valve moves to the left. Therefore, the CI oil port is opened to the tank oil port, the pressure of the servo piston large bore chamber is evacuated, the servo piston moves to the left, the pump's oil discharge flow increases the rotation of the servo piston, and is transmitted to the spool valve through the feedback mechanism. The openings of the spool valve and the sleeve continue to rotate before fully closing.
3. Priority structure of low tilt rotation (low flow) command
As mentioned above, the flow control and output power control tilt rotation commands are transmitted to the feedback lever and the spool valve through the large hole parts (C and F parts) of lever 1 and lever 2, but the φ5 pin protrudes in C and F The structure of the large hole (middle 9) of the part, so that the pin only contacts the rod that can make the inclination smaller, and does not contact the 9 hole of the rod on the side of the larger tilt command state. According to this mechanical selection method, the low-incline side commands of flow control and output control can be prioritized
4. Power switching control (control to reduce output power)
As shown in Fig. 3-39, the set output power of the pump can be arbitrarily controlled according to the power switching pressure P.
After the power switching pressure P increases, the compensation link is moved to the right by the pin and the compensation piston. Therefore, as described above to prevent the output power from being overloaded, the inclination angle of the pump can be reduced, thereby reducing the output power setting value. On the contrary, if the power switching pressure P decreases, the output power value will rise.
The working principle of the Sumitomo excavator regulator is shown in Figure 340.
