Take Kawasaki hydraulic pump as an example, Kawasaki hydraulic pumps are commonly used in Kobelco, 31, Sumitomo (5 Series) and other brands of excavators.
Kawasaki hydraulic pump
The next picture is a schematic diagram of the Kawasaki K3V series hydraulic pump. Basically, there are several parts, such as the front pump, the middle pump body, the rear pump, the pilot pump, the regulator and so on. The pump is made up of two plunger pumps and a pilot gear pump connected in series. The pump is equipped with a pilot safety valve, a plunger pump displacement: 110mL/r x 2, a pilot pump displacement: 10mL/r.
The front and rear pumps control the left and right side of the excavator to walk in one walk to supply oil for the walking motor; the large arm cylinder is a double pump confluent, the middle arm and the middle arm are two pump confluence, and the bucket and rotation are one of the pumps in the front and back pumps for oil supply. The pilot pump is to provide control pressure for the combined valve.
1. Regulator
The regulator is to change the inclination of the inclined plate by adjusting the adjusting bolts on the pump body and the valve plate of the regulator to change the plunger stroke to change the maximum flow rate, the minimum flow rate, the power control and the control degree of the flow.
Adjuster changes inclination angle of inclined disk (single pump)
In the servo piston size head cavity all the limited bit screw, so by adjusting the limit screw can adjust the maximum or minimum stroke of the servo piston, to adjust the maximum flow of the pump or the minimum flow effect. As shown in the picture, the green circle is a limited screw with small head (near the driving shaft), and the blue one is a large head fiber screw.
By adjusting the size screw, the pump flow can be increased or reduced.
Two, proportional solenoid valve
Proportional solenoid valve variable control process: engine speed sensor, electronic controller, proportional solenoid valve and proportional solenoid valve output oil pressure into the main pump variable plunger to control the output flow of the pump. At any speed, the power of the hydraulic pump is basically the same as that of the engine.
The proportional solenoid valve control signal is the current signal, the input oil pressure is the leading pressure oil; the higher the speed, the greater the control current, the smaller the output pressure of the proportional solenoid valve, the greater the output flow of the pump.
Let's take an example to illustrate the principle of proportional electromagnetism. For example, when a excavator suddenly meets a high load (such as a large rock suddenly dug at the beginning of the dredger, the regulator does not have the time to control the flow of the pump quickly, and the excavator can be choked out. " The symptom of flameout is that the actual engine speed is reduced. When the engine speeds the engine speed below the throttle knob through the engine speed sensor, the proportional solenoid valve is immediately controlled to use the pilot pressure to quickly reduce the flow of the hydraulic pump and ensure that the engine will not hold the car to extinguish the fire.
