Page 602 - Mechatronics with Experiments

JWST499-Cetinkunt
JWST499-c07
588 MECHATRONICS Printer: Yet to Come October 9, 2014 8:41 254mm×178mm
Controller
DC P.S.
DSP Amp
Cylinder
Operator command
input device

B
Pump

M/E
P T
Motor/Engine
A

Tank Valve

FIGURE 7.116: Independently metered valve (IMV) concept. Valve flow orifices are
independently controlled and defined in real-time control software.

There are several patents on this concept [15]. The valve flow–orifice–pressure differential
relationships are still the same, except that in the case of IMV each flow rate can be
independently metered,
√
Q PA = C ⋅ A (i ) (P –P ) (7.765)
PA 1
A
P
d
√
Q = C ⋅ A (i ) (P –P ) (7.766)
PB d PB 2 P B
√
Q = C ⋅ A (i ) (P –P ) (7.767)
AT d AT 3 A T
√
Q = C ⋅ A (i ) (P –P ) (7.768)
BT d BT 4 B T
√
Q PT = C ⋅ A (i ) (P –P ) (7.769)
PT 5
T
P
d
√
(i ) (P –P )
Q AB = C ⋅ A AB 6 A B (7.770)
d
Since each solenoid pair is independently controlled, each orifice area can be controlled
and their relationship to each other, like the case in single spool valve, can be defined in
software. Therefore, the same IMV valve can be controlled to behave like a valve with a
different geometry by changing the control software. In other words, the effective valve
geometry is defined in software. For instance, if the IMV control is to emulate a standard
closed center valve, then i , i should be controlled such that
5 6
A (i ) = 0 A AB 6 (7.771)
(i ) = 0
PT 5
If open-center valve emulation is desired, then i should be controlled such that
6
A (i ) = 0 (7.772)
AB 6
If regenerative power capability is desired in a closed-center valve emulation, then i , i
5 6
should be controlled such that
A (i ) = 0 A AB 6 (7.773)
(i ) ≠ 0
PT 5