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Hitachi excavator upper structure and the working principle of the main pump and the sensor

Visits:Date:2017/4/14 15:30:30

Pump system includes main pump (HPV091DW) and pilot pump (HV/ZFS11/16.8L) two kinds. The main pump for variable displacement axial piston type can be bent, the main hydraulic system of hydraulic oil is transported to the mechanical and hydraulic components when all.
gear type pilot pump is a fixed displacement pump. The pilot pump delivers the oil to the pilot system and the main pump as shown in figures 2, 30 and 1.

1 main pump
engine drive shaft drives 7 pistons. When the shaft and the piston assembly rotate, the piston is reciprocating in the cylinder of the cylinder block, and the oil is supplied to each part. The piston receives oil from the suction port of the valve and then exits the drain. The angle of the
cylinder set can be varied from 2 to 4 degrees to control the flow of oil.
as shown in Figure 2, 31, there are two sets of cylinders in the casing of the main pump.

2. draws the action
, if the cylinder turns, the oil is sucked into the cylinder (through the piston D to the piston A), and all the pistons move up and down the cylinder. The working direction of the rotation direction of the cylinder block is shown in figures 2, 32 and 1.

3? 6? 1
transmission when the cylinder piston group continues to rotate through the cylinder cylinder G position to the E position, the piston valve plate through the output port will transfer to the oil hydraulic oil system. The movement of the conveying and the rotation of the cylinder block are shown in figures 2, 33 and 1.

4. output increase and decrease action
, depending on the servo piston movement, can make the cylinder group angle from 2 degrees to 24 degrees. The servo piston is connected to the valve plate and attached to the cylinder block. At 2 degrees, the tilt angle of the pump is minimum, the flow is minimal; at 24 degrees, the swashplate angle is the largest and the flow rate is the largest. The minimum angle to the maximum angle can be adjusted at will. The structure of the

5 regulator (current), the
regulator circuit, and each of the components are shown in figures 2, 35, and 1.
3 sensors input signals to the controller. The controller passes the electrical signal to the pump displacement solenoid valve, turns on or closes the solenoid valve, transfers the oil to the servo piston, and controls the swashplate angle of the pump.
the axial angle of the pump is minimum and the minimum flow rate is minimum.
when the pump discharge valve No. 1 (ON), open the pump discharge solenoid valve No. 2 closed path side from pilot pump oil into the servo piston, open the oil into the tank in a large diameter side, so the pump swashplate angle becomes minimum.
pump axial tilt angle maximum flow to the maximum. When the solenoid valve No 2 opens and the pump displacement solenoid valve No 1 opens, the oil from the pilot pump flows into the maximum diameter side and the minimum diameter side of the servo piston. As the maximum diameter side pressure is greater than the minimum diameter, the servo piston begins to move.
the axial angle of the front pump must be constant. Two displacement solenoid valve are closed, the oil stopped injecting, the big diameter side of the piston does not move, constant flow.

6. N (speed) of the sensor structure (Figure 2 a 36) speed control of engine and pump input
N sensor, which is equal to the velocity of the magnetic sensor, calculated the number of teeth of the flywheel, the AC pulse signal transmitted to the controller.

pulse number; t (s): AC
Zo: pulse time; disk drive gear. The structure of the
7. P (pressure) sensor
P sensor structure is shown in figures 2, 37, and 1.
P sensor (pressure) function is to detect the pressure on the membrane to withstand the actual pressure (pump output pressure), and into the current signal, passed to the controller (PVC), pump tilt control.

8. A (pump axial tilt) sensor structure,
A sensor structure, as shown in Figure 2, one, 38. The

A sensor changes the axial tilt angle of the pump into a current signal by passing the connecting rod of the valve plate and passes it to the controller PVC. The structure of the
9. DP DP (differential pressure) sensor structure is shown in figures 2, 39, and 1. The DP sensor is mounted on the control valve. The

DP sensor is controlled by two pressure signals. A signal (A) is the signal of the pump output pressure; another signal (B) is the signal transmitted by the shuttle valve in the control valve, which is the maximum actuator load pressure. The DP sensor converts the differential pressure to the current signal and then passes the signal to the controller (PVC). When the
10. control rod is in neutral position, the output voltage of the DP sensor is neutral, and the actuator load pressure is ON [Pa. The pump output pressure is set at 26 XG. Sxlo at unloading valve at the control valve at a. As shown in Figure 2, 40, the pressure difference exceeds 26 * 9.8 x 104Pa, and the DP sensor passes to the controller with a signal of 4.5V, and the controller indicates that the pump becomes the minimum flow. A port is oMPa, and B port is (30, 40) XG, 8 x 1 o4Pa, differential pressure exceeds 26 x, 9.8 x 4Pa-, the sensor output voltage of 4.5V. The control rod in the operating position, mining control loop makes the pump to maintain output voltage of the actuator pressure is greater than, if the control valve, actuator pressure and pump output pressure is almost equal, then the output of the DP sensor is very low. The
controller senses the low signal, which increases the pump flow and keeps the differential pressure at 13x9.8xlo4Pa, while the


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