Page 458 - Mechatronics with Experiments

JWST499-Cetinkunt
JWST499-c07
444 MECHATRONICS Printer: Yet to Come October 9, 2014 8:41 254mm×178mm
Mech. power

Inlet Outlet
port Pump port

Actuator Pump control
system
Amp. Sensed variable
Command signal
P
P d Control logic Sensor s
Q d Q
(P - P ) P - P
S
L
S L d
FIGURE 7.33: Control system block diagram for a variable displacement pump. The pump can
be controlled to regulate the output pressure, flow, or other derived variable. The control
element is the swash plate angle positioning mechanism of the pump.
100 16

Volumetric efficiency
14
Overall efficiency

80 12 Horsepower (HP)

10

Efficiency (%) 60 Input horsepower - 1800 rpm 8

6
Flow rate - 1800 rpm

40 4 Delivery ( GPM)

30 2

0
1000 2000 3000 4000 5000
Pressure psi
FIGURE 7.34: Steady-state performance characteristics of a pump: flow rate, power, and
efficiency as a function of its operating pressure range at different input shaft speeds.