Ford Escape: Automatic Transmission - Automatic Transmission – HF45 / Description and Operation - Transmission Description - System Operation and Component Description

System Diagram

System Operation

Component Description

Sensors and Actuators

The TFT sensor is a thermistor located on the internal transmission harness. It sends a voltage signal to the ISC (inverter system controller). The voltage signal varies with TFT . The TFT sensor can not be serviced in vehicle, the transmission must be removed and disassembled.

The park lock actuator is an internally mounted actuator. The park lock actuator engages the park pawl with the park gear when commanded by the ISC. The park lock actuator cannot be serviced in vehicle, the transmission must be removed and disassembled. The PCM uses the park lock actuator signal for range selection, torque calculation and reverse lamp operation.

Park

Power flow

In electric mode, torque flows from the electric motor to the transfer shaft and to the final drive ring gear. When the engine is off, the planetary carrier is held and the planetary ring gear is driven by the transfer shaft. This action causes the sun gear and the generator/starter to rotate. Under certain conditions, the SOBDMC will command the generator/starter to produce electricity for the electric motor and to charge the batteries.

Engine Starting Power flow

To start the engine, the final drive works as a holding element to the ring gear in the planetary assembly. The generator/starter turns the sun gear to start the engine.

Engine Charging Power flow

To charge the batteries, the final drive works as a holding element to the ring gear in the planetary assembly. The engine turns the carrier. This actions allows the generator/starter to produce current to charge the batteries and power the electric motor.

Regenerative Braking

When additional torque is needed to propel the vehicle, the generator/starter works as a holding element to the planetary sun gear. The flow of torque from the transfer shaft to the planetary ring gear is reversed and torque from the engine combines with the electric motor torque at the transfer shaft.