Test circuit of proportional hydraulic pump

Test circuit of proportional hydraulic pump

The dynamic requirements and accuracy level of the test system of the electro-hydraulic proportional hydraulic pump for the test oil, test instruments, meters and test devices are similar to that of the electro-hydraulic proportional pressure valve test system. Only the oil source of the test system is the tested proportional hydraulic pump itself.

The electro-hydraulic proportional control pump has two categories: bidirectional and unidirectional. Its test circuit also has two forms: closed and open, as shown in Figure 48 and figure 49.

(1) Closed test circuit. In Figure 48, the tested hydraulic pump 3 is a two-way proportional hydraulic pump, the hydraulic pump 6 is a makeup oil pump, 16 is a high-pressure flowmeter, the proportional overflow valve 11 and the proportional throttle valve 12 are loading valves, the valves 11, 12 and the fast switching valve 13.1 form a load step loading unit, and the four check valves 9 are directional elements that form the function of a two-way closed loop.

The difference between the closed circuit and the open circuit is that the oil at the outlet of the tested pump in the closed circuit does not return to the oil tank after being loaded, but directly returns to the tested pump population. Therefore, the tested hydraulic pump does not need to suck oil directly from the oil tank. In order to stabilize the system pressure, the overflow oil should be led back to the oil tank. Due to the leakage and loss of pipelines and hydraulic components, the return oil flow cannot meet the requirements of the oil absorption of the tested hydraulic pump, and the differential flow of this part needs to be provided by the auxiliary hydraulic pump 6. Obviously, the flow of the auxiliary hydraulic pump is much smaller than that of the tested hydraulic pump, and the volume of the oil tank is also relatively reduced.

(2) Open test circuit. The tested hydraulic pump 1 shown in Figure 49 is an electro-hydraulic proportional load sensitive variable piston pump with self-priming capacity.

1) The electro-hydraulic proportional overflow valve 14 (equipped with a manual pilot valve used as a safety valve) is a standing loading valve. If necessary, it can be replaced with a manual pilot overflow valve 14.1 to manually adjust the load pressure. The function of the system safety valve is realized by the loading proportional relief valve 14 with the pilot safety valve.

2) Electrohydraulic proportional throttle valve 13 is another standing loading valve, which can also be replaced with manual loading throttle valve if necessary.

3) The dynamic flowmeter 12.1 is integrated into the loading valve block 16 to reduce the cavity between the outlet of the hydraulic pump and the loading valve, so as to improve the pressure rise rate of the oil inlet cavity.

4) 15.1 and 15.2 are combined to form a fast switching valve unit, and 12.1, 13 and 14 in the loading valve block 16 and the fast switching valve unit 15 form a load step loading device.

开式回路是被试液压泵直接从油箱吸油，试验油液经负载单元后回油箱。这样，油液在油箱中可充分沉淀和逸散气泡，油温相对可以稳定一些，此回路适宜于自吸能力较强的液压泵。对于自吸能力弱的液压泵，需另加低压供油辅助液压泵（或使油箱油面高于泵的吸油口水平面），供油液压泵的流量至少要为被试液压泵流量的1.25倍。