The first principle of pump selection conditions is satisfied begged system, and on this basis, determine the output of the pump, operating pressure and the type of construction.

(1)

Conclude additional pump flow pump flow should be satisfied with the implementation of elements begged maximum speed, the output of the pump flow rate qp should be based on the maximum flow rate and the desired amount of leaked system to determine that qp≥Kqmax where qp

A pump output flow (L / min) leak coefficient K a system, usually K = 1.1 ~ 1.3 (whichever is greater line length, line short take a small value); qmax maximum flow element individually to implement the required internship (L / min).

Resulting from the accounting flow, use pumps have the following situation:

① maximum speed assumed by a single pump supplying a system element embodiment, the device of the press begged selected pump.

② system consists of a hydraulic pump oil to the implementation of several components, the flow rate should be accounted for in each period for each element required for the implementation of traffic, make traffic circulation map, selected according to the maximum flow rate of the pump.

③ assumed system consists of double pumps, press the top job feed work into begged speed, use low flow pump; active oil feed together by a double pump, should be active feed rate begged obtained active feed the oil demand, subtract job feeding low flow pump flow pump is a large flow of traffic.

④ more embodiments of the elements act together, along with the maximum flow should implement elements of the operation and determine the pump flow.

⑤ assume that the system has the power to make compensation accumulator element embodiment, the pump flow Standard Optional smaller.

About ⑥ job process has been used to save the governor valve system, in determining the flow rate of the pump, it should be added to the minimum flow relief valve overflow (usually taken to 3L / min). Pump output flow is obtained, the sample selected by commodity additional traffic is equal to or slightly larger than the accounting of the pump flow rate qp.

It is noteworthy that:

First, the choice of an additional pump flow rate not too much more than the big job placement flow, to avoid excessive pump overflow

Constituting greater power away.

Second, due to the influence of leaked when thinking conclude pump additional traffic, so additional traffic than the desired flow accounting to be bigger, so will the speed of practice may be slightly larger.

(2)

Job pressure pump conclude additional pressure pump should be based on the maximum operating pressure of the hydraulic cylinder to conclude that

Pp≥Pmax + ΣΔp or pp≥kPmax wherein Pp a pump operating pressure (Pa); the maximum operating pressure (Pa) Pmax one embodiment of a device ΣΔp into oil and oil back to throw a total pressure (Pa> . at first count, speed and relatively simple to save the desirability of oil (0.2 ~ 0.5) MPa; intake passage is provided on control valve and piping system, the more cluttered desirable (0.5 ~ 1.5> MPa.K a coefficient Thinking pump element to the implementation of the pipeline pressure to throw away, take K = 1.3 ~ 1.5. hydraulic merchandise samples, indicating that the extra pressure and maximum pressure of the pump. after calculating Pp, should additional pressure to pick pump should be selected so that the pump pressure is equal to or higher than the additional accounting value in use, just a short time overload situations, or commodities clarify the book exceptionally articulated plan before agreeing to the selection of high-pressure hydraulic press.

(3)

Selected detailed structure type hydraulic pump when the output flow and pressure of the hydraulic pump to determine the job, you can pick the type of detailed structure of the pump. The has determined the value of Pp and qp, with extra pressure and extra traffic to pick hydraulic pump nameplate conduct cf, the numerical nameplate is equal to or slightly greater than Pp

And qp value can (do not pay attention too much big> Under normal conditions, when additional pressure 2.5MPa, should be used in gear pump; The additional pressure of 6.3MPa, the vane pump should be used; if the higher operating pressures, the selected piston; assuming the machine load is large, and there are active jobs and slow travel, the choice limited pressure variable displacement vane pump or double vane pump; adjuvant used in machine tool equipment, such as feeding and clamping and other unimportant occasions, the choice of inexpensive gear pump; the choice is saved when the governor, the choice of a metering pump; power is assumed to be the case, when the governor is saving volume speed or volume, have to choose variable pump; low pressure system chosen blade variable pump; high-pressure piston pump system selection; in the case of exceptionally fine, such as the mirror grinders, begged supply ripple is very small, the choice of screw.

(4)

Determine the type and speed of standard hydraulic pump when determined, the pump speed shall be the speed selected in the sample commodity rules.