3. Simplification model of LMHP system's BIM 23127 dissipation
LMHP system is generally different from small-sized one with particular distinguishing features, such as complicated structure, large output force and large flux. Though LMHP may be different from each other in machine type, manufacturer or technological parameters, the structural features can be summed up as follows:(1)Plunger cylinder is the first choice of main working cylinder, while piston cylinder is generally selected as auxiliary cylinder.(2)Control valves group consist of a logical assembly of two-way cartridge valves (TWCVs) and pilot controlling valves, while valve port of TWCV is the main channel of hydraulic oil(3)Several pumps in parallel are usually used in pump station, and sometimes redundant standby pumps are used to improve the system reliability.
So the calculation process of LMHP system's energy dissipation can be simplified by ignoring the units with a relatively small proportion of energy consumption, such as oil filter, prefill valves, pilot controlling valve, pressure sensors and flow sensors. Then, the simplified model of control valve group can be seen in the dashed box of Fig. 3, where a(i), b(i), c(i) ≥ 0 respectively represent the number of working TWCVs in pressure limiting circuit, inlet oil channel, outlet oil channel in the “i” stage of the process.