Ｐ3＋Ｐ2２４M２Ｑ１１１１４≒２６.９ＬＳＶａｍＶＷＶ1＝ ＝Ｐ２●Volume calculation exampleIn advance, using the amount of hydraulic fluid that is charged in the accumulator, calculate the accumulator volume required for activating the cylinder.Specification conditionsDi :Cylinder bore = 300 mm (cross-sectional area (A) = 706.5 cm2)S :Cylinder stroke = 380 mmV :Cylinder speed = 0.75 m/secFc :Required cylinder power = 1,000 kNP :Pressure loss in piping etc. = 0.84 MPaP3 :Maximum working pressure = 20 MPaP2 :Minimum working pressure = Fc / A x 10 + P = 15 MPa(Pay attention to the pressure loss P between the accumulator and actuator)Q :Oil discharge volume from pump = 90 L/minWorking temperature = 20 to 80ºC Service fluid = Petroleum hydraulic oil *In calculation, convert all assigned pressure to the absolute pressure (MPa · abs).1) Find the required oil volume to be discharged from accumulator Vw (required cylinder oil amount).2) Considering the change in temperature during operation, find the gas charging pressure (P1) in the following steps.i) For Max. P1 at the maximum working temperature (80ºC), set the gas charging pressure ratio to 85%. (The gas charging pressure ratio can be up to 90% in consideration of the temperature change.) ii) Find Min. P1 at the minimum working temperature (20ºC) by the "Formula for gas charging pressure actual change due to temperature change". 3) Find the gas charging pressure ratio (e) at the minimum working temperature.Max. P1 = 0.85 · P2= 0.85 x 15.1013 MPa · abs= 12.84 MPa · absMin. P1 = 10.11 MPa · abs4) Find the polytropic exponent (m, n).· Find the oil charge time from Vw (the amount charged in the accumulator) and the pump flow rate.accumulator oil discharge time.· From the nitrogen gas polytropic exponent list on page 205) Find the oil discharge coefficient (F) .6) Find the accumulator gas volume (V1). π・Ｄi２Ｖ＝ ・Ｓ・１０－６π・３００２＝ ×３８０×１０－６ｅ＝ ＝Ｐ１10.11（１５＋０.１０１３）≒０.６7Average working pressureOil Charge TimeOil Discharge Time(Ｐａ )＝ ＝（Ｔｍ）＝ ＝ＶＷ（Ｔｎ）＝ １０-３＝ ×１０-３ｍ＝１.９０ ｎ＝１.９６20.10131.9615.1013ａ －１ｎＦ＝ ＝20.10131.9015.1013ｅ・η・Ｆ０.６7×０.９５×０.１３５≒３13Ｌ２０.１０１３＋１５.１０１３≒ １７.６ＭＰａ・ａｂｓ２６.９９０/６０≒ １７.９sec· The cylinder operation time becomes the ３８００.７５≒０.５sec－１≒0.135２６.９22Relief Valve160˚CFP
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