Hybrid Synergy Drive Gives Camry Extra Boost

HYBRID SYNERGY DRIVE

GIVES CAMRY EXTRA BOOST

As its name implies, Hybrid Camry features two power sources - a 2.4 litre four cylinder petrol engine and an electric motor generator, plus a hybrid battery that stores electrical energy.

The combination of petrol and electric power delivers a maximum of 140kW of power, making Hybrid Camry the most powerful Camry in New Zealand.

Toyota New Zealand's General Manager of Sales and Operations, Steve Prangnell said Hybrid Synergy Drive will take Camry's efficiency to a new level.

"Hybrid Camry will save motorists hundreds of dollars a year in fuel - and the more you drive, the more you'll save on fuel," Mr Prangnell said.

Hybrid Camry has a combined fuel consumption of only 6.0 litres per 100 kilometres, while emitting 142 grams of CO2 per kilometre when tested to the Australian Design Rule standards.

Toyota's Hybrid Synergy Drive has the potential to perform better than either a stand-alone petrol vehicle, or a fully electric vehicle.

In Hybrid Camry, the electric drive motor is used for take-off and for low to mid-range speeds.

In normal cruising, both the engine and the electric drive motor drive the wheels, with any surplus engine power routed to the generator to recharge the hybrid battery.

Under hard acceleration, the battery supplies additional energy, while the engine and motor give smooth, seamless acceleration.

When the driver brakes or slows down, the motor recovers the kinetic energy that is normally lost as heat and converts it into electricity to store in the hybrid battery - this feature is known as regenerative braking.

The petrol engine automatically switches off when the car is stationary or coasting, to save fuel and reduce exhaust emissions.

HYBRID DRIVETRAIN

Hybrid Camry's driveline consists of a 2.4 litre petrol engine, two sets of planetary gears and two electric motors/generators, with a counter gear to drive the differential.

The petrol engine is based on the petrol VVT-i equipped Camry engine, which has been modified to use a different operating cycle known as the Atkinson cycle. This optimises fuel economy while delivering 110kW of power and 187Nm of torque.

Hybrid Camry's first electric motor acts primarily as a generator, storing surplus petrol engine power in the hybrid battery. It also acts as a starter motor for the petrol engine.

The second motor acts primarily as an electric drive motor, but also acts as a generator during regenerative braking.

The first planetary gear set acts as a power-split device, dividing petrol engine power between the generator and the counter gear.

The second planetary gear set is a reduction gear for the 105kW electric drive motor. The reduction gear set allows Hybrid Camry to use a more efficient and compact electric motor while optimising acceleration.

The compound planetary gear also acts as an electronically controlled continuously variable transmission (ECVT) that seamlessly changes the transmission ratio for optimum performance, driveability and fuel economy.

It does this by controlling the generator's revolutions, doing away with the need for a conventional transmission.

Hybrid Camry has a gated gear shift lever which is designed to look and operate like a conventional automatic transmission gear shift. Shift positions are "P"," R", "N" and "D" as per a standard automatic transmission, plus "B" which provides additional braking when required - such as when driving downhill - using Hybrid Camry's unique regenerative braking system.

When the Hybrid Camry decelerates, the kinetic energy of the vehicle is converted into electrical energy and stored in the high voltage battery. This process is known as regenerative braking and helps to reduce mechanical brake wear by approximately 20-30%.

NOT ALL HYBRIDS ARE CREATED EQUAL

The basic concept of all hybrid vehicles is the same - a combination of two technologies, in this case a petrol engine and an electric motor - that work together to power the vehicle. But not all hybrids are created equal.

Hybrid power trains differ in the way they combine the motor and engine.

A 'full hybrid' is the only system that can operate on electric or petrol power alone, or a combination of the two. Full hybrids run on electric only at low speeds, on petrol and electric drive in traffic, and on petrol alone at higher speeds. The hybrid system automatically coordinates the motor and engine for the best balance of responsive performance, fuel economy and lower exhaust emissions.

With full hybrids, the petrol engine shuts off when coming to a stop and restarts the engine as needed when moving off again. This helps prevent wasted energy from idling and starting from a dead stop, two times when a vehicle's engine is most inefficient.

The batteries also recover energy back from the drive train through regenerative braking, reducing vehicle speed by converting some of its kinetic energy into a storable form of energy instead of dissipating it as heat as with a conventional brake. The captured energy is stored in the hybrid battery for future use.

Toyota's Hybrid Synergy Drive system is a 'full hybrid' system and is found in the Hybrid Camry and Prius.

Power-assist, or 'mild', hybrid systems rely on the petrol engine to power the vehicle at all times. The electric motor only assists the engine when required for more power or greater efficiency. As such, the electric motors and batteries used in mild hybrids are less powerful than in full hybrids.

HYBRID SYSTEM COMPONENTS

Component

Role

Petrol engine

2.4 litre 2AZ-FAE Atkinson cycle petrol engine with 110kW of power at 6,000rpm and 187Nm of torque at 4,400rpm. Meets Euro IV emission standards.

(Located under the bonnet)

Hybrid Transaxle

A compact arrangement of two high output electric motors. Incorporates a number of components:

Motor generator 1 (MG1) - acts primarily as a generator to convert excess petrol engine power to the hybrid battery. Also acts as the starter motor.

Motor generator 2 (MG2) - acts as a drive motor with 105kW of power and 270Nm of torque. Also acts as a generator during regenerative braking.

Power split device - splits the engine power to drive the wheels as well as allowing MG1 to act as a power generator.

Other gear systems allow MG2 to run for efficiently, increasing torque output.

The hybrid transaxle works as an Electronic Continuously Variable Transmission (ECVT).

(Located under the bonnet)

Inverter

Converts direct current (DC) from the hybrid battery into alternating current (AC) and supplies it to the motor/generator.

DC-DC converter

Converts power generated by the motor/generator from DC244V to DC12V and supplies power to auxiliary devices (such as the power steering, electric water pump, air conditioning or headlights) and charges the 12V auxiliary battery.

(Located in the luggage compartment)

Step-up converter

Increases the voltage of the hybrid battery from DC244V to a maximum of DC650V to drive the high voltage motor and generator. Also converts DC650V from the generator to DC244V for storage in the battery.

Hybrid battery

This sealed nickel metal hydride (Ni-MH) battery stores the energy used to proper the vehicle and is charged and discharged throughout the driving cycle.

(Located in the luggage compartment)

Hybrid control computer

Coordinates the petrol engine, electric motor, battery and brakes to ensure optimum output based on the driver's demands.