The task of hydraulic system parameter design and calculation is to determine the structural scheme of the hydraulic system on the basis of the preliminary determination of the main parameters of the system: working pressure and maximum flow rate, so as to determine the form and specifications of the executive element and hydraulic pump. In this paper, Dahlan hydraulic editor will briefly talk about the determination of hydraulic system pressure and flow parameters.
I. the working pressure of the executive element
In order to ensure that the hydraulic pump has a high working efficiency, but also a certain pressure reserve, generally take the working pressure of the hydraulic system pp for the hydraulic pump rated pressure (0.85 -1) times, taking into account the pressure loss of the pipeline and the hydraulic valve, the working pressure of the implementation of the element p should be less than the working pressure of the system pp, the preliminary design can be taken pp = 1.1 p. The size of the working pressure, the relationship between the system involved in the economic rationality or not. The size of the working pressure is related to whether the system involved is economically rational. The lower the pressure is selected, the larger the structure size (such as the working cylinder piston area), the greater the weight, the system requires a large flow; pressure is selected on the high side, the manufacturing accuracy of the components, sealing performance and system maintenance requirements also increase, and make the volumetric efficiency is reduced.
II. Maximum flow rate of the actuator
The maximum flow rate of the actuating element and the structural parameters of the actuating element (the effective working area of the hydraulic cylinder A or the displacement of the hydraulic motor VM) and the speed of the movement, so that qmax can only be determined after the A or VM is determined.
The effective working area A of the hydraulic cylinder must satisfy the maximum load force F, in addition to the minimum steady flow qvmin of the flow control valve. Therefore, it is necessary to carry out trial calculations and checks on the effective working area A until the requirements are met. In the calculation, take into account the seal size and the relevant standards for cylinder bore rounding.
Determine the displacement of the hydraulic motor should be considered to meet the requirements of the load torque T, and together with the selected working pressure p rounded to determine the specifications of the hydraulic motor. If necessary (e.g., in the case of volumetric throttling), the displacement of the hydraulic motor must also be calculated according to the requirements of the minimum motor speed nmin.
When the load force of the hydraulic system is determined, the hydraulic system working pressure and the maximum flow rate has become two interdependent factors, increase the working pressure of the liquid can reduce the flow rate, increase the flow rate of the liquid can reduce the working pressure of the system, the selection of the calculation should be considered comprehensively.