Hybrid architectures - Propulsion Systems for Hybrid Vehicles - page 92

choice of ratios and operating the vehicle in slow traffic. The power split operating
modes are explained:
Mode 1. Vehicle launch: The engine is off, carrier speed is zero and only the
M/G propels the vehicle. Battery power is discharged through M/G to the wheels.
This mode persists to approximately 20 kph.
Mode 2. Normal cruise: Engine power is delivered to the wheels via the pla-
netary gear. S/A operates as a generator and the M/G operates as a motor. The
battery does not participate in propulsion. S/A electrical power is summed at the
driveline by the M/G.
Mode 3. Full throttle acceleration: Conditions are the same as for Mode 2 with
the exception of M/G power being augmented by input power from the battery. The
battery discharges in this mode.
Mode 4. Deceleration/regenerative braking: Engine is stopped, S/A is stopped
and kinetic energy from the vehicle is recuperated via the M/G back to the battery.

Example 4: Using the 2010 Camry Hybrid eCVT powertrain architecture shown in
Figure 2.23 and given that the maximum angular speed of MG1 = 1,465.8 rad/s,
what is V WOT =?

2010 Camry Hybrid e CVT

Final drive

axle

R

78 Diff

57

23

18

80 23 55

g fd = 3,542
P215/60R17

54

C 1 C 2

ICE

30

23

S 2

S 1

MG2

MG1

E 2

E 1

Batt

P b P cir

Figure 2.23 Camry Hybrid eCVT architecture

Solution: In Figure 2.23 the applicable gear ratios are defined as follows:

78
30 ¼ 2 : 60; E 2: k E 2 ¼

57
23 ¼ 2 : 478;

E 1: k E 1 ¼

55
54

¼ 3 : 542

80
23

Final drive : g fd ¼

Using the defined gearing (Table 2.5), the tyre characteristics and the stated
maximum speed of the main traction M/G, MG1 yields

r W w MG 1
g fd k E 2

V WOT ¼ ¼ 59 : 29m = s ¼ 132 : 6mpg