Get to Know the 2011 Chevrolet Volt
• Electric Only/Combined Engine On (EV)
• Regenerative Braking • Engine Start • Reverse Let’s take a closer look at each of
these operating modes.
Modes of Operation Electric Only/Engine Off (EV)
— In this mode, the transmission oper- ates in full electric mode for about 25-50 miles (depending on tempera- ture, terrain, and driving habits) with- out starting the gas engine. DC power from the battery flows
to the PIM, where it’s converted into 3-phase AC power. In this mode, the variable low and 1-2 reverse clutch is applied and generator/drive-motor B provides output torque to drive the wheels. The high voltage auxiliary pump provides fluid pressure to the transmission control system and lubri- cation system. Electric Only/Combined Engine
Off — Depending on driver demands and road conditions, the vehicle may enter combined mode. During this mode, the variable high and 2-3-4 clutches are applied, allowing genera- tor/drive-motor A and/or generator/ drive-motor B to provide output torque to the wheels as needed. Electric Only/Engine On or
Extended Range — Once the battery has reached minimum reserve power, the engine starts. Then the system oper- ates in electrically variable mode: the engine drives generator/drive-motor A to generate electricity, which, in turn, drives generator/drive-motor B to drive the wheels. The energy generated by genera- tor/drive-motor A is either stored in the battery or delivered to generator/ drive-motor B for vehicle propulsion. The engine operates at the best speed to optimize fuel consumption while main- taining output power requirements. Electric Only/Combined Engine
On — Depending on driver demands and road conditions, the vehicle can enter Combined Engine On mode. During this mode, engine electrical power combines with battery power to the generator/drive-motors to provide the output torque needed to move the vehicle. In this mode, the 1-3 reverse
8
Figure 4
Figure 5
clutch and the variable high 2-3-4 clutches are applied. Regenerative Braking — During
braking, the drive-motor/generators are used to decelerate the vehicle. By applying negative torque to the wheels, the generator/drive-motors generate electricity. The 3-phase AC power gen- erated by the drive-motor/generators is converted to high-voltage DC that’s then stored in the battery. Engine Start — Once the high
voltage battery has dropped below a cer- tain charge level, generator/drive-motor
GEARS January/February 2012
A starts the engine. During engine start mode, the 1-3 reverse clutch is applied and generator/drive-motor A cranks the engine. Reverse — With the shifter in
reverse, the variable low and 1-2 reverse clutches are applied and the generator/ drive-motor B spins backward, provid- ing reverse movement. With a basic understanding how
the 4ET50 transmission operates, it’s time to look inside the transmission.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71