OBJECTIVESAfter studying Chapter 13, the reader should be able to:1. Explain the operation of a Ford/Mercury hybrid electric vehicle (HEV).2. Describe the features of a Ford/Mercury HEV.3. Discuss the safety precautions to be followed whenever working on a Ford/Mercury HEV.4. Explain how the electronically controlled continuously variable transmission (eCVT) allows the Ford/Mercury HEV to achieve maximum efficiency.5. Describe the service procedures for Ford/Mercury HEVs.
The Ford Escape and Mercury Mariner share most of the same components and, except for trim and other non-hybrid related features, are basically the same.
Interior differences include:Center console gearshiftUnique interior trimOffers seating for up to five and includes the same 60/40 split folding rear seatEfficient packaging of the hybrid technology, such as locating the battery pack at the rear cargo floorA unique gauge package features an economy indicator with green zone that shows when the vehicle is operating on battery power.
The Escape/Mariner hybrid power train system includes the following components: A 2.3-liter four-cylinder gasoline ICE featuring Atkinson-cycle combustion and producing 133 horsepower at 6,000 RPMA 70-kilowatt (equivalent to 93 horsepower) electric traction motorA generator-motor that recharges the batteries, starts the engine, and controls the CVT function of the transaxleA special electronically controlled continuously variable transmission (eCVT) used to drive the front wheels in a front-wheel-drive Escape/Mariner or all four wheels with the optional Intelligent 4WD System™A 330-volt nickel-metal-hydride battery pack located in the rear cargo floor
An electronic vehicle system controller manages charging, drive assist, and engine starting functions such as the idle stop function.
The Ford/Mercury Hybrid uses a lightweight 2.3-liter four-cylinder ICE.The engine also features:Double-overhead-cam design with four valves per cylinder Pent-roof combustion chambers, and centrally located spark plugs Direct-acting mechanical bucket tappets that require no lash adjustment during a 10-year, 150,000-mile service life Four orifice-type fuel injectors that provide a better spray pattern and finer atomization than is possible with more common single-orifice injectors Butterfly valves positioned in the intake runners that restrict airflow at low speeds to induce tumble as the fuel-air mixture enters the combustion chamber Counter-rotating balance weights that help eliminate vibration
The Ford/Mercury hybrid ICE uses a special Atkinson combustion cycle for improved efficiency. This consists of a 12:1 compression ratio for maximum efficiency and late-closing intake valves to reduce pumping losses.
The air inlet to the Ford/Mercury hybrid ICE uses a charcoal filter to trap any hydrocarbons that may be in the intake manifold when the engine is turned off. When the engine starts, airflow through the charcoal draws out the hydrocarbons, which are then burned in the cylinders rather than being released into the atmosphere.
The transaxle also routes a portion of the power produced by the engine to a generator. The transaxle includes the following components: 36-kW permanent magnet AC generator motor70-kW permanent magnet AC traction motorPlanetary gear and final drive gearsIntegrated power electronics/voltage inverter
Four Modes of OperationThe transaxle operation takes place in one of four modes, as follows:Series Mode.1. Used only when the vehicle is not moving and the ICE is running. The transaxle will not enter this mode when it is placed in the “neutral” position. 2. The ICE is running to charge the batteries or for climate control reasons. The ICE may also be running to keep the catalytic converter warm.
Positive Split Mode.1. The ICE is running and driving the generator motor to produce electricity. 2. Power from the ICE is split between the direct path to the drive wheels and the path through the generator motor.3. This is the mode that is normally used while under cruise conditions.
Negative Split Mode.1. The ICE is on and the generator motor is being used to consume electrical energy to reduce engine speed.2. The traction motor can operate as a motor or a generator.3. This mode is used during highway driving when the ICE has to be on but the HV battery pack does not need to be charged.
Electric Mode.1. The vehicle is being propelled using stored electrical energy only using the traction motor.2. This is the preferred mode whenever the required power is low enough for the electrical system to handle.3. This mode is used in reverse because the ICE cannot deliver reverse torque through the transaxle.
Regenerative braking is automatically controlled by the PCM along with the Brake System Control Module (BSCM). This electric regenerative braking represents a major part of the hybrid’s efficiency advantage over conventional vehicles.
GENERATOR MOTORThe generator motor handles three tasks:1. The primary responsibility is generating electric current.2. The second task is restarting the ICE after shutdown, after a stop, or after coasting.3. The generator is also used to control the drive ratio in the transaxle's planetary gearset so that the ICE operates at its most efficient load and RPM.
HIGH-VOLTAGE BATTERY PACKThe HV battery pack consists of 250 nickel-metal-hydride D-size cells connected in series, packaged under the cargo floor.
The high-voltage charging system is a floating ground system. A floating ground system means that the neither the power side nor the return side of the circuit is electrically connected to chassis or body ground.
Battery Temperature ControlThe high-voltage (traction) battery pack works best if it is not too cold or too hot. The system is configured so that fresh air can be brought in for battery cooling, or air can be recirculated through the battery pack housing. Cooling fans are located inside the traction battery module and these circulate air over the high-voltage battery and the electronics located in the battery case.
Total battery capacity is 5.5 ampere-hours (Ah); operating voltage varies between 216 and 397 volts. In the discharge mode, the battery pack can deliver up to 39 kilowatts of power and its maximum recharge rate is 31 kilowatts.
Use the 12-Volt Battery to Charge the High-Voltage BatteriesThis is achieved by sending the 12 volts to a special DC-DC converter located in the traction battery case, where the voltage is increased and then sent to the high-voltage batteries. The switch used to start this recharging procedure is located behind a panel on the driver’s side kick panel. When the switch is turned on, the 12-volt battery will charge the high-voltage batteries.
12-Volt BatteryThe 12-volt battery is a conventional lead-acid automotive battery.The battery has three major functions:Storage of electricity for later use Voltage stabilizer for the electrical system Temporary power when electrical loads exceed the DC-DC converter output currentThe 12-volt battery is located under the hood.
ELECTRONIC CONTROLLERAn onboard electronic device (AC to DC converter) inside the transmission control module (TCM) converts the AC current produced by the generator motor and the traction motor to DC voltage suitable for recharging the battery pack.
DC-DC ConverterThe DC-DC converter is controlled by the PCM and is located under the hood on the passenger side of the vehicle in front of the shock tower.
ELECTRIC POWER ASSIST STEERING (EPAS)The electric power assist steering (EPAS) system consists of:Power steering control module Electric motor Torque sensor Rack-and-pinion steering gear
The electrical power steering system powers itself down within three seconds after the key is moved to the OFF position.
If the vehicle speed is missing or out of range, the power steering control module defaults to a reduced level of assist. If the vehicle speed returns to the correct in-range values, the power steering control module adjusts the steering assist level accordingly.
REGENERATIVE BRAKING SYSTEM (RBS)The Ford Escape and Mercury Mariner are equipped with a regenerative braking system (RBS). The brake system used on the Ford/Mercury hybrid is a series regenerative braking systemin which power train braking is used first, up to the limits of the power train torque capacity and battery capacity.
SERVICE PROCEDURESThe Ford/Mercury hybrid vehicles are serviced the same as conventional vehicles except for certain precautions.
Remove the service disconnect plug and place in the servicing shipping (3) position.
Wear high-voltage linesman’s gloves with leather gloves over them whenever working on the high-voltage circuits.Always wear a face shield.Have available a fiberglass hook outside the buffer zone so that a technician can be pulled to safety in the event of electrocution.
Inspection and Verification1. Verify the customer concern.2. Visually inspect for obvious signs of mechanical or electrical damage.3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.4. If the cause is not visually evident, connect the diagnostic tool to the data link connector and select the vehicle to be tested from the diagnostic tool menu. 5. Carry out the diagnostic tool data link test.
Brake Fluid Replacement1. Adequate voltage to the HCU module is required during the system bleed. Connect the diagnostic tool.2. Access the service bleed function on the diagnostic tool and follow the directions.