Environmental Engineering Reference
In-Depth Information
Wheels
OWC
R
ICE
L/U
C
Gearbox
FD
S
M/G
3
Battery
pack
Figure 2.28 IHAT architecture of power split with single M/G
illustrates the IHAT driveline architecture having an M/G connected to the sun
gear, engine at the ring gear and output from the carrier.
The one-way clutch (OWC) grounds the transmission input shaft to chassis for
park and engine cranking by the M/G as well as preventing reverse rotation of the
carrier. The IHAT architecture has six operating modes:
Mode 1
.
Idle-stop
: In this mode, the OWC is activated and M/G torque is
amplified by the basic ratio of the epicyclic gear for cranking the engine.
Mode 2
.
Vehicle launch and creep
: With the ICE running, the M/G torque
reverses to generating quadrant so that reaction torque is applied to the sun gear,
enabling vehicle creep while ICE speed is held constant.
Mode 3
.
Vehicle launch
: When the accelerator pedal is pressed, the engine
produces higher torque, IHAT torque increases in generating mode and engine
torque is applied to the wheels via the ring gear. At some point during launch, the
M/G torque reverses sign and enters motoring quadrant. M/G speed approaches
engine speed. When M/G speed and ICE speed are approximately equal, the lock-
up clutch (L/U) is applied connecting the M/G and ICE to the transmission input
shaft.
Mode 4
.
Power assist and regenerative braking
: The L/U is applied and the
system operates in ISG mode. Power from the ICE is summed with M/G power to
meet the road load requirement. During braking, regenerative power is supplied via
the M/G to the vehicle's traction battery.
Mode 5
.
Generating mode
: With automatic transmission selector lever in N or
P, the L/U engages with the engine running, causing the M/G to generate
electricity.
Mode 6
.
Hill holding
: Again in ISG mode, an issue with non-level terrain is roll
back when the driver attempts to launch the vehicle on a grade following engine
idle-stop mode. In the IHAT system during the time between release of the brake
pedal and application of tractive power, the OWC supplies sufficient hydraulic
pressure to engage the AT gears.
