1. Closed system oil pump function
1) Supplement leakage in hydraulic pump and motor;
2) Because the externally controlled variable pump solves the problem of over-zero position well, it can provide external control oil to the variable mechanism of the bidirectional variable piston pump and the hydraulic motor brake;
3) Maintain the low pressure side pressure of the main loop of the closed system to prevent cavitation and suction of the large flow system;
4) Fill the cold oil into the system to reduce the system temperature.
2. Installation method of filling oil pump
There are two ways of internal engagement and external engagement. Internal gear pumps are smaller in size and usually have a small displacement.
3.Oil pump pressure setting
The high pressure of the oil pump wastes the power of the system. The pressure of the refill pump is too low, it is easy to empty or the flushing relief valve cannot be opened.
The set pressure of the oil relief valve is generally about 20-25bar, and the peak pressure is 40bar. At the same time, in order to avoid instant sucking, the lowest instantaneous absolute pressure should not be less than 8bar, so on some equipment (such as rotation), in order to prevent sucking, increase the accumulator.
After calculating the flow rate of the refill pump according to the above, part of the flow rate is used to supplement the leakage in the system, and the smaller control flow required by the closed pump control mechanism is removed, and the rest is all used for flushing. Try to avoid the flow of the refill pump from the relief valve overflow, resulting in insufficient flushing, closed system heating serious. Therefore, it is recommended that the set pressure of the flush relief valve is about 6bar-15bar lower than that of the oil refill relief valve. At the same time, in order to prevent the set pressure of the flush relief valve from being too low, most of the hydraulic oil of the refill pump flows away from the flush relief valve, resulting in insufficient oil in the closed system. The flush relief valve is generally 10bar, 14bar, 16bar, and so on.
