Electro-hydraulicsMCTR 907
Dr. Eng. Taher Salah Eldin
Assignment # 1
Due Date: 11th of November
(To be submitted in this form in Eng. Nour’s Office C3.208)
Name
ID #
Group
Problem 1
Given:
For the shown electro hydraulic circuit:
𝑥 ∶ 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛
𝑥 ∶ 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦
𝑥 ∶ 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛
𝑦 ∶ 𝑣𝑎𝑙𝑣𝑒 𝑜𝑝𝑒𝑛𝑖𝑛𝑔 ,
𝑢𝑣 ∶ 𝑣𝑎𝑙𝑣𝑒 𝑣𝑜𝑙𝑡𝑎𝑔𝑒
𝑝0 ∶ 𝑠𝑦𝑠𝑡𝑒𝑚 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒
𝑝𝑇 ∶ 𝑇𝑎𝑛𝑘 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒
𝑝𝐴 , 𝑝𝐵 ∶ 𝑐ℎ𝑎𝑚𝑏𝑒𝑟 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒
Required:
1- Convert the shown open loop control circuit into closed loop control circuit.
2- For a proportional valve in a closed loop position control circuit with double rod
cylinder with zero laped spool and linear flow signal function = 𝑄(𝑦, ∆𝑝 = 𝑐𝑜𝑛𝑠𝑡) .
Prove that (1) p0 = pA + pB
(2) pA&pBas function in (p0 )
3- For the valve type 4WRZE16E150-7X/6EG24N9
- Determine the nominal flow rate at ∆𝑝 = 10 bar for spool displacement y =
ymax(100 % command signal)
- Calculate the flow rate under the same pressure drop at different spool
displacement values y = 20 % , 50 % , 75 % and determine the spool overlap
type
Solution:
Problem 2
The shown schematic represents the basic circuit of hydraulic drive unit.
Components:
123456-
Control valve
Motor
Brake
Short circuit brake valve
Throttle valve
Drive reducer
Given:
Suction volume of motor
Total dead volume in the piping A and B in the motor
System pressure
Produced load moment in the motor
Motor volumetric efficiency
Hydraulic mechanical efficiency of the motor
Total reduced mass moment of inertia according to motor load at motor
shaft
Bulk modulus of compressibility for the pressure media
Proportional valve (1)
QN = 20 dm3/min by ∆𝑝N = 70 bar
V2 = 16 cm3
VT = 14 cm3
P0 = 210 bar
M2eff = 40 Nm
η2vol = 0.96
η2hm = 0.934
J = 0.004 kgm2
Eoil= 15000 bar
The control edges for the proportional valve are symmetric.
Further pressure losses in pipelines and valves are ignored.
Required:
1- Calculate the load pressure pL = pA– pB at the motor taking into consideration the
hydraulic mechanical efficiency. (pL=168 bar)
2- Calculate the pA&pB produced in operation mode (pA = 189 bar, pB=21 bar)
3- Calculate the motor speed n2 at energizing signal for proportional valve 1 equal 50
% of the maximum signal under the same loading conditions. (n2 = 465 min-1)
Solution:
Problem 3:
The figure below represents the entry side guide mechanism of an emergency shear
mechanism of a Hot Strip Mill (HSM) production line, which is composed of two differential
cylinders, driven by a proportional valve with symmetrical control edges in a closed loop
control circuit. The cylinder is working against an opposite force of 20 kN, the system
pressure p0 is 210 bar.
Given:
F = 20 kN
Cylinder dimension in mm = 100 / 56 x 320
Required:
1- Calculate the relationship pA&pBin terms of
2- Maximum cylinder speed Vmax at a
maximum flow rate QomaxA =14.3 l/min (fully
opened conditions).
p0.
Solution: