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PRESS INFORMATION
Lexus Hybrid Drive Evolution Includes World’s First Full V8 Hybrid and All-Wheel Drive
With the launch of the 2008 LS 600h L, the continued evolution of the Lexus Hybrid
Drive system has achieved an unparalleled combination of acceleration performance and
superior quietness. Featuring the world’s first full hybrid V8 powertrain and full-time all-wheel
drive (AWD), this latest Lexus Hybrid Drive was created to smoothly transmit its exceptional
torque with instantaneous power and minimal noise, vibration and harshness (NVH).
Lexus' ongoing commitment to hybrid technology has its roots in an expanding hybrid
lineup. The first Lexus Hybrid Drive system arrived in April 2005 with the launch of the RX
400h, the world’s first gas-electric hybrid-powered luxury utility vehicle. It commenced with an
electric four-wheel-drive system, and later added a front-wheel-drive hybrid powertrain, with a
3.3-liter V6 engine and two high-capacity motor-generators (MG1 and MG2).
The RX 400h AWD also included a rear motor-generator (MGR) that drives the rear
wheels when traction demands, such as during acceleration or tire slip. The RX’s hybrid drive
features an Electronically controlled Continuously Variable Transmission (ECVT) with a
reduction device, providing smooth yet powerful acceleration on par with 4.0-liter V8 gas
engines. It comes with fuel-efficiency ratings comparable to compact sedans while attaining
Super Ultra Low Emission Vehicle II (SULEV II) certification, producing nearly 70-percent
fewer smog-forming emissions than the average new car.
In April 2006, the GS 450h debuted as the world’s first hybrid-powered performance
luxury sport sedan. With an innovative new longitudinal hybrid transmission and V6 engine, the
GS 450h offers 4.5-liter V8-like performance, fuel efficiency ratings nearly 30 percent better
than some V8 models, and carries a SULEV II certification.
In the GS 450h, the Lexus Hybrid Drive powertrain evolved to combine a new 3.5-liter
V6 engine with a compact, permanent magnet electric motor within the transmission, all driving
the rear wheels. The hybrid powertrain collectively produces 340 horsepower and effortlessly
accelerates the GS 450h from zero-to-60 mph in just 5.2 seconds. Just as impressive is how
quickly and powerfully torque is delivered during mid-range acceleration. The hybrid system’s
electric-drive motor delivers maximum torque immediately upon demand, a unique powerdelivery characteristic most noticeable and most useful during 30-to-50 mph passing and in
traffic-merging maneuvers.
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Power from the gas engine and electric drive motor (MG2) is distributed to the rear drive
wheels via a planetary gear-type Electronically controlled Continuously Variable Transmission
(ECVT). This unique transmission, which eliminates specific gear ratios, features a dual-range
torque-multiplication device that allows drivers to select from among three driving modes: power,
normal and snow.
The arrival of the LS 600h L brings with it 10 years of hybrid technological progression
dating back to the launch of the first Prius in Japan. This new luxury hybrid sedan has the
world’s most advanced gas-electric hybrid system and is one of the most highly developed
automobiles to date. Through an all-new V8 engine, high-output electric motors and a newly
designed, large-capacity battery pack, this latest Lexus Hybrid Drive system brings with it
superior acceleration, quietness, fuel efficiency and emissions.
The LS hybrid’s iteration of Lexus Hybrid Drive
carries with it some impressive new feats. The coupling
of the LS 600h L’s potent all-new V8 to a high-output
electric motor and dual-range motor speed-reduction
device that utilizes the overall power at a wide range of
speeds and AWD, achieves acceleration performance on
par with V12 engines. The combined gas engine and kW
capacity of the hybrid-battery output produces a total of
438 overall system horsepower. While the luxury sedan renders a tranquility that is apparent
whether at idle or high speeds, fuel efficiency ratings for the LS hybrid are on par with many
AWD 3.0-liter V6 luxury sedan engines and it is certified with an SULEV II emissions rating.
The LS hybrid’s 389-horsepower, 5.0-liter V8 engine (2UR) was part of a unique
development process new to Lexus with performance, fuel efficiency and emissions targets
establishing the displacement. The V8 is a part of the UR engine family, along with the
LS 460’s 4.6-liter V8 (1UR), and has a 6.5-mm stroke increase. During its development,
emphasis was placed on reducing NVH and weight, while still increasing power.
In order to achieve its performance goals, the new V8, in comparison to the 1UR,
required changes to the pistons, crankshaft, connecting rods, damper pulley, VVT-iE, exhaust
manifold, oil pan and mounting bracket areas. For example, the crankshaft was made of forged
steel and polished to a mirror finish with oil-hole smoothing in order to reduce friction and
improve quietness.
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An innovative Variable Valve Timing with intelligence and Electronically controlled
intake cam system (VVT-iE), with an electric-motor-controlled intake cam, improves engine
output and start-up performance, increases power output, improves fuel efficiency and reduces
emissions. The VVT-iE delays the intake valve timing to lower compression, which reduces
engine vibration to create an extremely quiet and smooth engine restart when the vehicle is at
rest or being powered by the electric motor-generator.
NVH was also minimized by placing sound-isolating material around the head cover,
using a dual-mass-type pulley with a TORSION and bending damper, and by utilizing a dynamic
damper-engine mount.
The 5.0-liter V8 features a hollow camshaft with forged lobes for higher strength and
lighter weight to improve power and fuel efficiency. Camshafts, piston pins and the crankshaft
are polished to a mirror finish to reduce friction areas and power loss. In addition, a unique
cylinder honing was performed at a 30-degree crosshatching for reduced friction and mechanical
loss. An electric relief valve on the fuel-delivery line better regulates fuel pressure to assist in
delivering lower emissions and better fuel efficiency, while a dual-pipe air intake allows for a
lower-profile hood design and reduces high- and low-frequency noise.
A new Hydrocarbon Adsorber and Catalyst (HCAC) system acts as a storage system in
the exhaust system for hydrocarbons produced immediately following a cold start. HCAC
adsorbs hydrocarbons during and following cold starts and holds them until the engine and
catalytic converter reach operating temperature, contributing to fewer emissions and better fuel
efficiency.
The LS 600h L’s Lexus Hybrid Drive system
contains the world’s first all-wheel-drive Electronically
controlled Continuously Variable Transmission (ECVT).
It is an evolution of the world’s first longitudinal hybrid
transmission on the GS 450h and consists of two
planetary gear sets with a dual-range reduction device
that controls high and low ranges for optimum torque output.
The LS’ hybrid powertrain includes two motor generators, MG1 and MG2, which are
water-cooled and have a maximum system output of 650V DC. Like the GS 450h, MG1 starts
the gas engine when needed and acts as a generator to recharge the hybrid battery. MG2 features
a three-magnet structure, as opposed to the two-magnet layout of the GS 450h’s MG2, which
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optimizes the magnet position and enables a smoothing out of the changes in magnetic force
during rotation to help suppress vibration and reduce associated noise.
The LS 600h L’s MG2 turns the transfer-input shaft connected to the TORSION® centerdifferential transfer case where the power is split between the front and rear wheels. When
acting as a generator, it converts kinetic energy to electricity to recharge the hybrid battery when
coasting or braking. MG2 has a maximum output of 165 kW (221 hp) as compared to the
GS 450h’s 147 kW (197 hp).
To reduce NVH as much as possible, the transmission’s gear teeth and areas where the
gears engage were finished in the micron range, with the teeth being polished as well. Gear
noise is also minimized by controlling the drive gears’ rotation speed at the transition moment.
An acoustic analysis of the hybrid transmission was conducted and as a result, unique acoustic
covers were created in targeted areas to shield the passenger compartment from as much NVH as
possible.
The LS 600h L’s hybrid drive creates full-time
mechanical all-wheel drive via a new compact TORSEN®
limited slip differential (LSD) that is integrated with the
rear-output shaft. It operates when a wheel-speed
difference occurs between the front and rear wheels to
optimally distribute the motive force from the hybrid
ECVT. This gives the LS 600h L excellent traction
during acceleration, at high speeds and when cornering.
It has a 40/60 power split during normal driving conditions and is capable of a near 30/70 power
split.
As demanded by this ultra quiet hybrid luxury sedan, further NVH reduction was
engineered in a number of areas. In addition to smoothing the gear teeth, the integration of the
TORSEN® LSD provides rigidity and reduced noise creation. Overall, the LS 600h L’s allwheel-drive system is lighter, more compact, and quieter than the GS 350 AWD and the
competition while providing superior capabilities. It has a 30-percent reduction in size and is 11
pounds lighter as compared to the GS 350 AWD, while lending 50 percent more capacity. A
gear-driven LSD, as opposed to the chain-driven GS 350 AWD, reduces weight and NVH.
The LS 600h L’s AWD system is smaller and more compact than the Mercedes-Benz
4matic and the Audi Quattro. While gear-teeth smoothing helps make it quieter than the
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Mercedes-Benz 4matic system, the TORSEN® LSD displays advanced traction and cornertracing capabilities versus both the Mercedes-Benz 4matic and the Audi Quattro.
This new Lexus Hybrid Drive system provides three modes: hybrid for everyday driving,
power for improved acceleration and response, and snow for enhanced control on slippery
surfaces. An eight-speed sequential engine braking system allows greater control on downhill
grades.
The LS 600h L features a new 240-cell, 288V,
nickel-metal hydride (Ni-MH) hybrid battery. The
package includes two DC/DC converters for the auxiliary
equipment and Electric Power Steering battery, and for
the optional Active Stabilizer Power Suspension System
battery. The converters are built on the side of the hybrid
battery for a more compact layout. While the surrounding cabin air cooled the hybrid battery on
previously models, for the first time the hybrid battery can also be cooled via the rear air
conditioning unit, with a dedicated fan circulating cool air. Speed sensors enable the fan to slow
or stop as the LS 600h L slows down, helping to ensure maximum cabin quietness.
A new smaller and lighter inverter, which
converts the current from AC to DC and back depending
on whether the vehicle is accelerating or in a
braking/recharge mode, has been made more efficient
with lower NVH. By utilizing the same dedicated
cooling system as MG1 and MG2, the inverter’s output
has increased by 13 percent. Its structure has also been
reinforced to minimize the noise and vibration normally created by high-frequency vibrations
associated with inverters or transformers.
A new Electric Vehicle (EV) mode has been
created for the LS 600h L. The EV mode, which can be
engaged under certain conditions via a dedicated button,
will keep the vehicle in electric-only mode at speeds
below 25 mph for up to six-tenths of a mile. This will
help emissions and efficiency in low-speed circumstances,
such as when driving in residential areas or in parking garages.
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The LS 600h L also has a new power meter located on the IP displaying total system
output in three ranges: Power, Eco and Charge. The Power reading will indicate acceleration,
the Charge reading will register during regenerative braking or charging, and the Eco reading
will indicate an efficient normal cruising rate. In addition to the new power meter, for the first
time the Lexus Hybrid Drive provides a dedicated tachometer for the gas engine’s rpm output.
The LS 600h L’s newest evolution of the Lexus
Hybrid Drive system achieves a new level of innovation
and sophistication not found in its competitors. It is a
seemingly contradictory combination of engine
performance, fuel efficiency and clean emissions not
often found on the road today.
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