Most of Daewoo excavators are equipped with K3V112DT-11GR hydraulic pumps produced by Japan's Kawasaki Company; DH400LC-3 excavators are equipped with K3V180DTH1 hydraulic pumps.
K3V system hydraulic pump is a drive shaft series swash plate type axial variable piston pump, which is composed of two main pumps, a gear pump and the corresponding hydraulic pump regulator. The input shaft of the main pump is connected to the engine through a flexible coupling, and the displacement of the two variable pumps is adjusted by their respective regulators. The gear pump is installed on the main pump at the back. It supplies oil to the hydraulic pump regulator and also supplies oil to the remote pilot control valve.
1. Structure and function
The main pump is composed of cylinder block assembly, swash plate assembly and valve plate assembly. The cylinder assembly is composed of a drive shaft, a cylinder block, a plunger, a sliding shoe pressure plate, a ball head and a ball seat. The swash plate assembly is composed of a friction swash plate, a swash plate support shaft and a servo piston, etc. The displacement and pressure are changed by changing the inclination angle of the swash plate by the regulator. The valve plate assembly is composed of a valve body, an oil distribution plate and an oil distribution plate pin, etc., and is provided with an oil suction port and an oil discharge port.
The drive shaft of the hydraulic pump rotates at the same speed as the engine, and the cylinder and plunger rotate together to suck and discharge oil.
When the inclination angle of the swash plate is 0°, the piston has no stroke and no oil discharge action; when the inclination angle of the swash plate is increased (that is, a increases), the stroke of the piston increases, and the oil suction/discharge volume increases. Sliding friction is used between the cylinder block and the oil distribution plate (the oil distribution plate is fixed while the cylinder body rotates), and the reciprocating movement of the plunger continuously performs oil suction and discharge actions.
2. Hydraulic pump regulator [KR3H(G)-HNOP]
The functions of the hydraulic pump regulator mainly include;
(1) The power control follows the main pump's own oil discharge pressure p and the main pump connected in series with the oil discharge pressure p. Ascent, the hydraulic pump regulator can automatically reduce the swash plate inclination of the hydraulic pump (that is, reduce the displacement), and control the input torque below a certain value (when the speed is fixed, the input power is controlled to a certain value).
(2) An electromagnetic proportional pressure reducing valve is attached to the power shift control regulator, and the power setting can be changed by changing the command current value of the valve. Only the secondary pressure pr (power shift pressure) of the electromagnetic proportional pressure reducing valve is transmitted to the power adjustment mechanism of each hydraulic pump controller through the internal passage, and the respective power setting values will change at the same time. Therefore, the output power of the hydraulic pump can be arbitrarily changed to achieve the best operating state according to the operating conditions.
(3) Reverse flow control by hydraulic control pressure. The hydraulic control pressure generated by the slide valve stroke of the hydraulic control valve (the size of this pressure depends on the stroke of the slide valve) automatically controls the displacement of the hydraulic pump, that is, the slide valve is in In the neutral position, the flow in the central parallel passage of the main control valve is the largest, and when the spool valve stroke is the largest, the flow in the central parallel passage of the main control valve is the smallest. Introduce the hydraulic control pressure into the hydraulic pump regulator. When the hydraulic control pressure is high (the spool valve is neutral and the flow is maximum), the inclination angle of the hydraulic pump swash plate becomes smaller and the displacement decreases; when the hydraulic control pressure is low (the spool valve stroke increases Larger), the inclination angle of the swash plate of the main pump becomes larger, and the displacement increases. This is the principle of reverse flow control.
