Lexus LS 600h
Overview
LS 600h - launched 2007
The all-wheel drive LS 600h is the world's first vehicle to feature a full hybrid V8 powertrain. Combining an all-new five-litre V8 petrol engine with large, high-output electric motors and a newly designed large-capacity battery pack, this advanced combination provides the LS 600h with a peak combined output rating of more than 435 bhp.
By Osamu Sadakata, Chief Engineer of the Lexus LS 600h
“The LS 600h is made possible by Lexus’s state-of-the-art technology and embodies the evolution of the premium car to confidently accommodate changes in customers’ lifestyles and values, while meeting society’s demands for safe and environmentally friendly product designs. That evolution has given rise to a new dimension in performance that is unmatched by any other car, a pinnacle of technological accomplishment reached as the result of the Lexus pursuit of the ideal premium car.”
Performance
- 0-62mph acceleration - 6.3 seconds
- Top speed - 155mph
- Combined cycle driving - 30.4mpg
- CO2 - 219g/km
Lexus Hybrid Drive
The LS 600h is a full hybrid, capable of operating in both petrol or electric modes alone, as well as a combination of both. The system comprises a 5.0-litre V8 petrol engine, electric motor, generator, high performance battery, power split planetary gear mechanism and Power Control Unit, which governs the high-speed interaction of the different components. The electric motor, generator power split device and motor speed reduction gearing are housed in a single, compact and lightweight transmission casing.
Hybrid Synergy Drive In Operation
Over the course of any journey, Lexus Hybrid Drive operates in several different modes to maximise the LS 600h’s overall efficiency. In low efficiency conditions, such as at start-up and low to mid-range speeds, the vehicle runs on the electric motors alone, eradicating both engine noise and carbon dioxide emissions.
In normal conditions, the V8 engine serves as the main power source. Engine output is divided by the power split device, both to drive the wheels directly and power the generator, which in turn charges the high-voltage battery. In these circumstances, power allocation is constantly monitored and adjusted between the engine and electric motor to maximise efficiency.
When full acceleration is required, engine and electric motor again work in tandem, with extra power supplied from the battery to boost acceleration.
During deceleration, the engine switches off as the driver lifts off the throttle and the electric motor acts as a second generator to effect regenerative braking. This optimises energy management in the hybrid system by recovering kinetic energy, normally wasted as heat under braking and deceleration, as electrical energy for storage in the battery.
When the footbrake is simultaneously engaged, the hybrid system automatically co-ordinates both energy regeneration and braking, prioritising the former to achieve efficient energy regeneration even at low vehicle speeds. Allied to the LS 600h’s all-wheel drive, this function operates on all four wheels, not only improving fuel efficiency by charging the hybrid battery under deceleration, but also improving vehicle stability under braking. At lower speeds, for instance, most of the brake force is actually provided by the regenerative braking function. When the engine is cold and the ignition is switched on, the system will start the engine to warm the unit and the catalytic converters. After that the engine will stop automatically when the vehicle is at rest, to conserve fuel. However, if the vehicle is at idle for prolonged periods, the engine will automatically crank up whenever necessary to charge the high-voltage battery via the generator.
Furthermore, in all driving conditions, the level of battery power is constantly managed by a dedicated ECU, preventing it from reaching extremes.
The Lexus hybrid powertrain delivers smooth, linear acceleration, avoiding the familiar ‘jumps’ between gears that occur in a conventional drivetrain, and in all conditions and at all speeds, it delivers a significantly higher level of refinement.