Lexus Launches New AWD V8 Hybrid LS600h

Lexus LS600hL and LS600h (Photo: Toyota)NEW VEHICLES
Lexus Launches
New AWD V8 Hybrid LS600h TOKYO - Toyota has launched its new Lexus LS600h flagship in Japan. Available in both a standard and 120mm-longer wheelbase version (LS600hL), the $124,000 base-priced LS600h is expected to be introduced into the American market later this year. Driving performance The Lexus LS600h features the world's first All-Wheel-Drive (AWD) gasoline-hybrid system, says Toyota. It combines a D-4S 5.0-liter V8 engine, high-output electrical motor and an electronically controlled continuously variable transmission (ECVT) that provides up to 430 horsepower at peak capacity.

The LS600h features a new 5.0L V-8 engine, high-output electrical motor, electronically controlled continuously variable transmission and large-capacity, nickel-hydrate battery pack. (Photo: Toyota)

The new D-4S direct dual injection four-stroke gasoline engine combines direct fuel injection with port fuel injection. The marriage delivers stable cruising across all speed ranges, reduced gasoline consumption and lower CO2 emissions. Other advanced technologies, including an electric motor-driven Variable Valve Timing-intelligent Electric (VVT-iE) installed on the intake side of the Dual VVT-i (Dual Variable Valve Timing-intelligent) controller, also help to maximize the performance of this V8 engine.

The vehicle is fitted with four-wheel regenerative braking that converts the kinetic energy released during deceleration and braking to electricity and stores it in the battery for later use. Coordinated control of front and rear wheels' regenerative braking and hydraulic braking raises energy recovery efficiency and cuts gasoline consumption to help realize a substantial reduction in emissions. This coordinated control also delivers more reliable braking power with a natural braking feel.

The high-output motor in the hybrid transmission is coupled with a two-stage motor speed reduction device and operates across a wide band of speeds, from low to high, within the motor's efficient range. When starting and accelerating at low speeds, the low gear is used to provide instant torque for strong acceleration, while at medium and high speeds, the high gear is used for high-speed cruising.

New DS4 5.0L V8 Engine
(Photo: Toyota)

The hybrid system's large-capacity battery enjoys enhanced cooling performance through cooling control based on cabin air and cool air from the rear air conditioner. Compact and with high density, it is accommodated in the luggage space behind the rear seat. The power control unit uses a newly configured cooling mechanism to cool its power semiconductor module, which converts direct current to alternating current and vice versa. This mechanism is designed to cool both sides of the module surface to increase cooling performance and realize more compact dimensions and higher output density of the control unit.

Horses with cleats The combination of a smooth and highly responsive hybrid transmission with the full-time all-wheel drive efficiently transmits acceleration power through all four wheels to the road surface. It is designed to deliver stable cruising performance in all road conditions. Lexus says the LS600h delivers zero to 100 km per hour standstill acceleration in just 5.5 seconds, and 40 to 70 km per hour passing acceleration in 2.5 seconds.Doing More with Less DENSO Corp. developed the high-output power control unit (PCU) and battery cooling system for the new Lexus.

The PCU consists of a boost converter that raises the main battery voltage (288V) up to the maximum system voltage (650V) - up 60 percent per unit volume - and two inverters that convert direct current (DC) into alternate current (AC) to drive the main traction motors.

The new PCU is designed to produce the same output as the conventional technology, but is reduced approximately 30 percent in size and approximately 20 percent in volume.

In conventional battery cooling systems, the battery blower draws only cabin air to cool a hybrid vehicle's main battery. In the LS600h, DENSO's new system can use cooled air from the cooling unit of the rear air conditioning system, as well as use cabin air to cool the main battery.

As a result, the new battery cooling system provides comparable cooling performance with approximately half the amount of air required by previous models. This reduces noise from blowing air by approximately 30 percent, contributing to the quieter vehicle cabins.

The newly developed full-time AWD is equipped with a newly developed Torque Sensing Limited Slip Differential (TORSEN LSD) transfer device, which automatically and instantaneously distributes optimum drive power according to road conditions to both the front and rear wheels. During normal cruising, the TORSEN LSD distributes drive power to the front and rear based on a 40/60 split that favors the rear wheels, but can also instantaneously select a 50/50 or a 30/70 split in drive power distribution to match road conditions.

This allows outstanding cruising stability realized by the full-time AWD and produces natural handling characteristics, without the feeling of understeer that is often experienced with traditional AWD vehicles. Additionally, the combination of full-time AWD with the Vehicle Dynamics Integrated Management (VDIM) system delivers greater active safety performance and vehicle stability as well as smooth starting, acceleration, and cornering on all road surfaces.

The transmission features Sequential Shiftmatic, which allows for selection of one of eight different levels of engine braking power depending on driving conditions, and offers greater responsiveness to pressure on the accelerator. The Mode Select feature permits the driver to select from three driving modes - normal, power and snow - according to driver preference and road conditions.

An environmental conscience The new Lexus complies with Toyota's proprietary Eco-Vehicle Assessment System (Eco-VAS), implemented to achieve the overall reduction of environmental impact throughout the vehicle's entire lifecycle. In addition to using highly recyclable materials, greater attention has been paid to the environment by, among other means, reducing the use of substances of concern such as lead, mercury, cadmium and hexavalent chromium, achieving the Japanese automobile industry's voluntary goals of eliminating the use of these substances. With the aim of reducing CO2 emissions, the new vehicles boast a fuel efficiency of 12.2km/liter, in accordance with the 10 to 15 test cycle required by the Japanese Ministry of Land, Infrastructure and Transport. Fuel efficiency is at least 20 percent better than the level called for by the Japanese 2010 standards, and the LS600h's low 190.3g/km of CO2 emissions are just half those of a conventional 6-liter engine powered vehicle. In the United States, the LS600h is expected to be SULEV-rated. In addition, both nitrogen oxides (NOx) and non-methane hydrocarbons (NMHC) have been cut, achieving emissions levels 75 percent lower than the 2005 standards under the Ministry of Land, Infrastructure and Transport's Approval System for Low-emission Vehicles. Integrated safety and stability The LS600h is designed and engineered in line with the Toyota's Integrated Safety Management Concept, with the goal of creating in the future a vehicle that does not cause accidents. The safety package integrates an advanced Precrash Safety System, which features a vehicle-front pedestrian detection system, collision-avoidance steering support and an optional safety function covering vehicles approaching from the rear. In addition to the impact-absorbing body and high-strength passenger cabin, the new Lexus features Supplemental Restraint System (SRS) airbags. Dual-stage twin-chamber upper body, knee and side-curtain airbags are provided for both driver and front passenger seats. Rear-seat SRS side airbags are standard on the LS600h, while the LS600hL with a special "separate rear seat package" is fitted with a rear-seat SRS seat cushion airbag as standard. In the event of a frontal collision, these seat cushion airbags raise the front part of the cushion, reducing the forward motion of the occupant and combining with the seatbelt action to increase the protective effect on the occupant's entire body. The VDIM system, which integrates control of drive power, steering and braking to realize high vehicle stability and high active safety performance, appears in a newly developed version in the new Lexus, representing a further evolution adapted to full-time AWD.

LED Low Beams and Precrash Safety System Sensors
(Photo: Toyota)

Additionally, electrically operated active stabilizers are minutely controlled to respond to linear cruising, cornering and a range of other operating situations, which minimizes vehicle roll and allows stable cruising. Low-beam headlights are made up of projector lamps in a three LED-lamp configuration, the world's first to use both an LED light source and small parabolic reflectors.

For the front and rear multilink suspension, an exclusive AWD-adapted front suspension was newly developed, while the rear suspension underwent optimal tuning. Combined with the electronically controlled air suspension system fitted with Adaptive Variable Suspension (AVS), this provides superior handling and cruising stability and a smooth and even ride.Interior amenities The instrument panel is covered with real leather and features a hybrid system status multi-information display that indicates fuel-efficient driving criteria, including an energy monitor showing the energy flow and an instantaneous fuel gauge. Actual wood is used on assist-grips, the gear lever knob and the overhead console ornament.

Rear Passenger Comfort
(Photo: Toyota)

Automatic four zone air-conditioning allows independent automatic temperature control for all occupants. Utilizing an electrically operated inverter/compressor not only ensures comfort by controlling temperature and humidity, but also contributes to fuel efficiency. It can be used even when the engine is switched off.

(Sources: Toyota Motor Corp., DENSO Corp.)