Hybrid electric vehicle powertrain with four-wheel drive characteristics

A hybrid electric vehicle powertrain comprising an engine, a multiple ratio transmission and a single motor-generator with a stator and a rotor;

• the transmission being a countershaft transmission with gears on a main axis that is common to the engine, to a first torque output shaft connected to one set of traction wheels and to the motor-generator;
• tandem clutches at a torque input side of the transmission for delivering engine torque to the transmission gears as the clutches are selectively engaged;
• the motor-generator being disposed at a torque output side of the transmission;
• planetary gearing including one planetary element drivably connected to the rotor and another planetary element drivably connected to another set of traction wheels;
• and
• a variable capacity brake for providing a torque reaction for the planetary gearing.

A hybrid electric vehicle powertrain comprising an engine, a single motor-generator, a planetary gear unit and a transmission with multiple-ratio gears;

• the transmission including a twin, alternately engageable clutch assembly for establishing and disestablishing power flow paths between the engine and separate power input gears of the transmission;
• the motor-generator having a rotor connected drivably to a sun gear of the planetary gear unit and to an engine starter gear of the transmission;
• the planetary gear unit including a variable capacity friction brake for anchoring a ring gear of the planetary gear unit and a planetary carrier connected drivably to front vehicle traction wheels;
• and
• a four-wheel drive clutch selectively connecting the planetary carrier to front vehicle traction wheels whereby power from the engine is delivered to the front vehicle traction wheels;
• the transmission including selectively engageable ratio changing clutches to effect multiple power flow paths from the twin clutch assembly to the front and rear vehicle traction wheels.

A hybrid electric vehicle powertrain comprising an engine, a single motor-generator, a planetary gear unit and a countershaft transmission with multiple-ratio gears;

• a pair of power input shafts for the transmission;
• a first transmission countershaft;
• a second transmission countershaft concentrically disposed with respect to the first transmission countershaft;
• first and second transmission power input gears drivably connected respectively to the first and second transmission countershaft assemblies;
• a twin clutch assembly including first and second clutches for connecting alternately the engine to the first and second transmission power input gears;
• the motor-generator having a rotor connected to a sun gear of the planetary gear unit;
• a variable capacity brake for anchoring a ring gear of the planetary gear unit;
• a carrier of the planetary gear unit being drivably connected to a driveshaft for front vehicle traction wheels;
• and
• a four-wheel drive clutch for connecting a planetary carrier of the planetary gear unit to rear vehicle traction wheels.