Continuously Variable Transmission/Transaxle: Description and Operation

Transaxle Description

Transaxle Components

The Electronically Controlled Continuously Variable Transmission (eCVT) has the following internal components:

- Traction motor
- Generator
- Planetary gearset


Range Selection





Park

With the range selector in PARK:

- the parking pawl locks the output shaft to the case.
- the ignition key can be removed.
- the ignition switch can be cycled from OFF to START or RUN. The ready indicator light will illuminate on the Instrument Cluster (IC) when the ignition switch is cycled to the START position.

The ready indicator light is located on the lower right hand corner of the IC.

Ready Indicator Light





Reverse

With the range selector in REVERSE:

- the vehicle may be operated in a rearward direction.
- reversing lamps are illuminated.
- if the ready indicator light is not illuminated, which lights when the ignition switch is cycled to the START position, there is no reverse gear engagement.

Neutral

With the range selector in NEUTRAL:

- no power flows through the transmission.
- the output shaft is disengaged from the drive wheels.

Drive

The range selector DRIVE position provides:

- low speed driving.
- acceleration.
- cruise conditions.
- deceleration.
- maximum fuel economy during normal operation.

If the ready indicator light is not illuminated, which lights when the ignition switch is cycled to the START position, there is no forward gear engagement.

Low

The range selector LOW position provides:

- engine braking.
- improved traction on slippery roads.

If the ready indicator light is not illuminated, which lights when the ignition switch is cycled to the START position, there is no forward gear engagement.

Brake Shift Interlock System

The brake shift interlock system prevents a shift out of PARK unless the brake pedal is depressed. The brake shift interlock system has a Brake Shift Interlock Actuator (BSIA) mounted on the floor selector lever assembly. If the ignition switch is in the RUN position, the BSIA is continually on unless the brake pedal is depressed.

External Controls

The external control of the eCVT is mechanically controlled by a selector lever cable connected to the floor selector lever. The floor selector lever position determines PARK, REVERSE, NEUTRAL, DRIVE and low modes.

Motor Electronics Cooling System (MECS)

The vehicle uses a pump driven cooling system, referred to as the Motor Electronics Cooling System (MECS) pump, to transfer heat generated by the eCVT and the Hybrid Electric Vehicle (HEV) DC/DC converter to the atmosphere. The system uses a coolant-to-air radiator design.

The MECS pump is an electric pump that runs any time the ignition is in the ON position. Unlike traditional cooling systems, there is no thermostat in the MECS, so coolant flow should be continuous and considerably less than traditional powertrain cooling systems.

The flow direction is from the DC/DC converter to the MECS pump through the eCVT, then through the MECS cooler from the LH to RH side of the vehicle back to the DC/DC converter.

The MECS cooling pump will make an audible noise if it is running and a slight vibration may be felt by touch.

The MECS cooling system has a coolant expansion tank mounted on top of the transaxle.