Environmental Engineering Reference
In-Depth Information
split has been known since the early 1970s, particularly in the work by the TRW
group [17]. In Reference 17, Gelb
et al
. describe a dual M/G architecture having
electric machine functions of 'speeder' and 'torquer' in what was then called an
electromechanical transmission.
In this precursor to power split, the speeder M/G acted as a generator and the
torquer M/G as a motor in the driveline. The engine crankshaft was connected to
the sun gear of an epicyclic gear set. Input power to the epicyclic gear set is divided
in direct proportion to the respective speeds of the sun, planets (carrier) and ring
gears. The speeder M/G is connected to the carrier and the torquer is connected to
the ring gear via an additional gear ratio. Figure 2.16 illustrates the mode of
operation of the TRW electromechanical transmission.
R
FD
w
s
Torquer
M/G
Speeder M/G
w
T
C
S
3
f
ICE
w
e
3
f
Battery
pack
Figure 2.16 TRW electromechanical transmission (precursor to power split,
from Reference 17)
The electromechanical transmission has five modes of operation associated
with the engine and both speeder and torquer M/Gs (Figure 2.17).
Mode 1
. Low acceleration events for which engine power exceeds the road
load and the remainder is used to charge the vehicle battery. Torquer and speeder
act as generators sending excess engine power to the battery.
Mode 2
. Engine power equals road load demand but the engine has insufficient
torque. Torquer acts as a motor. The speeder M/G accepts excess engine power and
transfers this power to the torquer and to the battery.
Mode 3
. Road load torque and power exceed the available engine torque and
power. In this mode the battery delivers peaking power to the speeder and torquer
combination.
Mode 4
. Higher speed cruising, the scenario in Mode 3 changes and shifts to
Mode 2 and the speeder is taken out of the loop (locked) and the engine throttled
up. The torquer absorbs or delivers power to the battery.
