Lexus LS600h in Detail

Press Release

Page 1: Overview
Page 2: Powertrain
Page 3: Dynamics
Page 4: Safety
Page 5: Comfort

Powertrain

Lexus Hybrid Drive employed in the high performance flagship of the Ls model range combines an all new, longitudinally-mounted 5.0 litre V8 petrol engine with a high-output electric motor and a newly designed, large-capacity battery pack. This state-of-the-art hybrid drive system will equip the Ls 600h with an unparalleled balance of performance and environmental efficiency, generating a peak combined power output of over 330 kW (449 hp), while delivering an unparalleled combined fuel consumption of below 9,5 l/00km and combined CO2 emissions below 220 g/km.

Hybrid Drive Components

Derived from the Ls 460’s 4.6 litre powerplant, the new 5.0 litre V8 engine is a showcase of precision engineering, the most technologically advanced internal combustion engine ever developed by Lexus engineers. The painstaking development of high rigidity components, optimum balance in all moving parts, the minimisation of friction and unprecedented precision of assembly award the new V8 benchmark performance in the fields of refinement and quietness.

To reduce the overall weight of the engine, the cylinder block is die-cast from a lightweight, high strength aluminium alloy. The block structure and rib reinforcement design have been finalised through the incorporation of cylinder combustion pressure data to minimise both vibration and noise. in addition the engine head cover is constructed in a lightweight magnesium alloy.

The new V8 features a D-4s (Direct injection 4-stroke superior version) stoichiometric direct injection system, the world’s only automotive injection system to adopt two injectors per cylinder. it combines the strengths of both direct and port injection, realising optimum engine efficiency throughout the power band and improving torque by 7.5% across the rev range, whilst minimising fuel consumption and emissions. D-4s also substantially reduces combustion fluctuations in comparison to any conventional, direct or port injection system.

The 5.0 litre powerplant is also equipped with Lexus’ Dual VVT-i. This optimised, low-pressure loss, variable intake and exhaust valve timing system incorporates VVT-iE, the world’s first electric motor driven intake camshaft, which operates across the full engine revolution and temperature spectrum. The new V8 further features a semi-dual exhaust manifold that reduces interference in the flow of exhaust gases, further improving output and combustion efficiency.

Lexus Hybrid Drive employs a three phase, permanent magnet aC synchronous type motor, operating on a 650-Volt current, delivering more than 60 kW (27 DiN hp). additionally, by changing the magnet distribution, an astonishing operating quietness has been achieved. Further to this, coiling the magnetic alternate, and hence holding the magnetic force, resulted in a smoother, more stable motor rotation.

In addition to both petrol engine and electric motor power sources, the Ls 600h’s Lexus Hybrid Drive further comprises a generator, a high­performance battery, a power split device, which combines and re­allocates power from the engine, electric motor and generator according to operational requirements, and a Power Control Unit (PCU) to govern the high speed interaction of the system components.

To optimise delivery of the Lexus Hybrid Drive’s immense power, a new, mechanical, all-wheel drive system offers superior traction and handling stability, whilst a newly developed, dual stage, electronically controlled continuously variable transmission offers smooth, linear power delivery.

As in the Gs 450h, the Lexus Hybrid Drive’s electric motor, generator, power split planetary gear mechanism and motor-speed reduction gearing are all housed in one lightweight, highly compact transmission casing. The combined installation of these components within a single compact casing is fundamental to the successful installation of Lexus’ sophisticated hybrid drive system in a longitudinal, front-engine sedan platform.

Equipped with E-CVT (Electric Continuously Variable Transmission), the Ls 600h provides a breath-taking, linear acceleration. as the Lexus Hybrid Drive ECU selectively controls the rpm of the engine and electric motor, the E-CVT simulates a continuous variation of the transmission’s current ratio. similar to that of the Gs 450h, the two-stage gearing generates maximum low-gear torque for significantly enhanced acceleration, as well as extended high-gear performance for quiet, high speed cruising with improved fuel efficiency.

Lexus Hybrid 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. Under operating conditions of low engine efficiency such as start up and low to mid-range speeds, the vehicle runs on the electric motors alone, thus eradicating both engine noise and CO2 emissions.

Under normal driving conditions, the ultra-efficient V8 powerplant serves as the main power source. Engine output is divided by a power split device to both drive the wheels directly and power the generator, which, in turn, drives the electric motor and simultaneously charges the high-voltage battery. in these circumstances, power allocation is constantly monitored and adjusted between engine and electric motor to maximise efficiency. When sudden acceleration is required, engine and electric motor again operate in tandem, with extra power supplied from the battery to boost motor response, providing a superlative and linear power delivery.

During deceleration and under braking, the combustion engine switches off and the high-output electric motor acts as a generator to effect regenerative braking. such optimises energy management in the Lexus Hybrid Drive by recovering kinetic energy (normally wasted as heat under braking and deceleration) as electrical energy for storage in the high performance battery.

When the engine is cold and the ignition is switched on, the system will start the engine to warm the unit, running at an engine speed that provides the highest possible efficiency. Thereafter, at rest, the engine stops automatically to conserve fuel. However, if the vehicle is at idle for prolonged periods, the engine will automatically run whenever necessary to charge the high-voltage battery via the generator. Furthermore, under all driving conditions, battery power level is constantly managed via a dedicated ECU that prevents it from reaching extreme levels. The purpose is to maximise the life expectancy of the battery.

The Lexus hybrid powertrain delivers extremely smooth and linear acceleration, with none of the expected ‘jumps’ between gears of a conventional drivetrain. Under every driving condition, at whatever speed, Lexus Hybrid Drive offers a significantly higher level of drivetrain refinement than that of a conventional powerplant.