Transmission General Description

WARNING: This page is about a different variant/trim than selected.

The 5ET50 is a fully automatic, front wheel drive transaxle containing an electronically-controlled continuously-variable electric transmission. It includes an input flange, a torque dampener assembly with a rotating friction clutch, one stationary and one rotating friction clutch assemblies, a hydraulic pressurization and control system, a power inverter (and control) module, an electric fluid pump, two planetary gear sets and two electric drive motor-generators. Drive motor-generator A (1) is 55 kW and drive motor-generator B (2) is 76 kW.

The torque damper is internal to the transmission, bolted to the input flange and contains coil springs and a damper bypass clutch. The torque damper acts as a spring coupling to smoothly transmit shaft power from the engine to the input planetary gear set in the transmission and as a direct mechanical coupling from the transmission to the engine using the damper bypass clutch during engine starting and engine stopping.

The power inverter module is under the angled top cover and includes a control circuit board, solid-state switches, capacitors and other electronic components. The power inverter module receives and monitors driver commands and various other electronic sensor inputs and uses this information to vary the torque and speed of each electric motor-generator and to command the engine controller and engine operation. The power inverter module is connected with each of the two drive motor-generators through three internal terminal posts for transmitting variable-frequency, high-voltage, three-phase alternating-current (AC) electricity. The power inverter module is also electrically connected with the battery pack through a high-voltage, high-power connector and cable assembly for transmitting direct-current (DC) electricity.

The hydraulic system includes a high pressure electric fluid pump driven by an electric motor supplied with high-voltage current from the power inverter module, shift solenoid valves, a variable line pressure control solenoid valve and control wiring harness. All of the shift solenoids and the transmission fluid temperature sensor are packaged into a self-contained control solenoid valve assembly under the front cover. The electric pump maintains working pressure and control of the clutches when the engine is on and when the engine is off.

The two planetary gear sets, electric motor-generators and other clutches together provide all-electric propulsion, continuously-variable hybrid transmission ratios and a single fixed mechanical transmission ratio. When the vehicle is operating all-electrically, the stationary mechanical clutch reacts torque from motor-generator A to the output in the forward direction and the stationary friction clutch assembly can react torque from motor-generator B to the output. When the engine is in use, the stationary and rotating friction clutch assemblies are controlled by the power inverter module using hydraulic shift solenoids to select from a variable lower range of hybrid transmission ratios, a fixed mechanical transmission ratio and a variable higher range of hybrid transmission ratios.

The transmission may be operated in any of the following gear ranges:

P (PARK): This position locks the wheels and prevents the vehicle from rolling either forward or backward. PARK is the best position to use when starting the vehicle. Because the transmission utilizes a shift lock control system, it is necessary to fully depress the brake pedal before shifting out of PARK. For safety reasons, use the parking brake in addition to the PARK position.
R (REVERSE): This position allows the vehicle to be operated in a rearward direction. There is no separate reverse clutch or gearing in the transmission. All of the torque for reverse comes from motor-generator B.
N (NEUTRAL): In this position, the propulsion system does not provide power to the wheels.
D (DRIVE): Drive range should be used for all normal driving conditions for maximum efficiency and fuel economy. Drive position allows the transmission to operate all-electrically using one or both motor-generators when sufficient battery power and energy are available or using the engine when the battery is not sufficient.
L (Low): When the shift lever is placed in low (L) the driver shift request, also known as the tap shift function, is activated. The driver shift request allows the vehicle operator to switch from L2 to L1 by pressing the minus (-) button and back to L2 by pressing the plus (+) button. This position is used for the "feel" of engine braking and can be used for the slowing of the vehicle once the throttle is lifted. While in the position the vehicle will slow quicker and use the drive motor generator B to more aggressively collect energy during a regenerative braking event.