3. Issues to be noted in the selection of hydraulic pumps and hydraulic motors
3.1 Issues that need to be paid attention to
when selecting a hydraulic pump, it is necessary to comprehensively consider various factors such as application scenarios, hydraulic pump types, and rated pressures, effectively reduce the input power of the prime mover, improve mechanical energy conversion efficiency, and enhance the reliability and durability of the hydraulic system.
(1) In the selection of hydraulic pump types, the focus should be on the application scenario. In indoor working environments, it is advisable to focus on improving mechanical efficiency, usually using blade type hydraulic pumps; In outdoor work environments such as road construction, ports, buildings, and other small engineering machinery systems, it is advisable to focus on improving their stability, and gear hydraulic pumps are usually chosen; For high-power mechanical hydraulic systems such as forging equipment and metallurgical equipment, durability should be emphasized, and plunger hydraulic pumps are usually selected.
(2) In the selection of hydraulic oil, the focus should be on the hydraulic working conditions and usage conditions, such as temperature range, humidity, etc. Especially for environments that are prone to fire, consideration should be given to using flame-retardant or fire-resistant hydraulic oil such as phosphate esters.
(3) In the selection of rated pressure and flow rate for hydraulic pumps, it is required that their rated pressure must be higher than the nominal pressure of the actuator. To ensure the reliability of the hydraulic system, the rated pressure of the hydraulic pump should be at least 1.5 times the nominal pressure of the actuator (such as the hydraulic cylinder); The rated flow rate of the hydraulic pump should be higher than the maximum sum of the flow rates required by the instantaneous motion actuators. Considering situations such as hydraulic oil leakage, overflow valve or throttle valve diversion, the rated flow rate of the hydraulic pump should be at least 1.2 times the maximum flow rate.
(4) In terms of selecting the volumetric efficiency of hydraulic pumps, the volumetric efficiency of hydraulic pumps will decrease to a certain extent after a period of use. Taking axial piston hydraulic pumps as an example, the indicators in Table 2 can be comprehensively considered. If a variable displacement pump is selected, all indicators can be 1% lower than those of a fixed displacement pump with the same displacement.
