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 Últra Low Emission Vehicle (SÚLEV) 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. (concept carz) 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 SÚLEV 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 power-delivery characteristic most noticeable and most useful during 30-to-50 mph passing and in traffic-merging maneuvers.
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. Fuel efficiency ratings for the LS hybrid are on par with many AWD 3.0-liter V6 luxury sedan engines and is certified with an SÚLEV emissions rating while the luxury sedan renders a tranquility that is apparent whether at idle or high speeds.
The LS hybrid's 389-horsepower, 5.0-liter V8 engine (2ÚR) 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 ÚR engine family, along with the LS 460's 4.6-liter V8 (1ÚR), 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 1ÚR, 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.
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 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 Torsen® center-differential 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 all-wheel-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 Mercedes-Benz 4matic system, the Torsen® LSD displays advanced traction and corner-tracing 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.
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.Source - Lexus
Lexus RX 400h: Industry's First Hybrid Luxury Utility Vehicle
The Lexus RX 400h, launched in 2006 and featuring Lexus Hybrid Drive technology, set a new benchmark for environmental compatibility in a luxury-utility vehicle. Lexus is the only luxury brand to offer three hybrid vehicles, the RX 400h, the GS 450h sport sedan, and the all-new LS 600h L flagship sedan. (concept carz)
Significant both for being the first Lexus hybrid vehicle as well as for launching a new era in luxury vehicles, the RX 400h has sold more than 50,000 units since its launch RX 400hand now accounts for nearly 20 percent of all RX model sales . Lexus last year broadened the RX 400h's appeal with the addition of a new front-wheel-drive model and revised both standard and optional equipment. For 2008, the RX 400h is distinguished by detail trim changes including a new grille finish, chrome door handles and new blue hybrid emblems. The blue badge color is a consistent feature on all Lexus hybrid models. A body-color rear-gate spoiler adds a sporty new styling touch, and the available five-spoke, 18-inch alloy wheels feature a new finish. The RX 400h is available in seven new colors for 2008. Inside, Black Bird's Eye Maple wood trim is available with the Light Gray leather interior.
'Lexus has shown with the RX 400h that a luxury utility vehicle can be made more environmentally compatible while still delivering the performance, luxury and utility that make these vehicles so popular,' said Jim Farley, Lexus group vice president and general manager.
A leap forward in hybrid technology with its enhanced-performance capability, the RX 400h hybrid combines the power of a 3.3-liter V6 gasoline engine with that of an electric drive motor to deliver performance on par with some V8-powered luxury SÚVs – but with better fuel efficiency. The all-wheel-drive RX 400h's EPA-estimated city/highway rating is 26/24 mpg. The RX 400h front-wheel-drive model has an EPA-estimated fuel-economy rating of 27 mpg city/24 mpg highway (For model year 2008, the EPA has revised the way the estimated fuel economy rating is determined. Actual mileage will vary).
The RX 400h achieves Super Últra Low Emission Vehicle (SÚLEV) certification in California (Tier 2-Bin 3 in other states), producing nearly 70 percent fewer smog-forming emissions than the average new car. The RX 400h is also certified as a zero-evaporative emissions vehicle in California and those states adopting California standards. ( posted on conceptcarz.com)
Seamless power delivery of the hybrid powertrain is another plus for the RX 400h. The generous combination of engine and electric-motor torque makes city and highway driving seem effortless, with particularly impressive 30-50 mph passing power.
Visually, the RX 400h differs from the conventionally powered RX 350 model in subtle ways. The RX 400h features a unique grille design, a different front fascia with additional air intake and round fog lamps, and Light Emitting Diode (LED) tail lamps. Specific suspension tuning gives the RX 400h sportier handling than the RX 350. Inside, in place of a tachometer, a power meter displays the level of power generated by the hybrid powertrain. The driver can also monitor the gas-electric power distribution on the multi-information display or on the optional navigation system's seven-inch touch panel display screen. Traditional RX Luxury
The RX 400h closely follows the RX 350 in terms of standard and optional equipment, featuring a standard high-quality fabric interior, with leather trim available in several option packages. Ten-way power front seats are standard and feature a power lumbar adjustment. In addition to the standard brushed aluminum interior accents, customers can also specify wood trim with any interior color.
The Lexus Navigation System with rear back-up camera integrates Bluetooth® wireless capability and voice activation and is now offered in an option package with the Mark Levinson® Premium Audio system. Customers can order High Intensity Discharge (HID) headlamps with the Adaptive Front-lighting System (AFS), which helps to illuminate a turn or curve as the driver steers into it. Lexus Hybrid Drive Technology
The Lexus Hybrid Drive system is one of the most advanced powertrains in the world, yet it operates so seamlessly that it enhances the luxury experience rather than calling attention to itself. The system combines a V6 engine with a high-torque electric drive motor-generator. In the all-wheel-drive model only, an additional, rear-mounted electric-drive motor/generator provides on-road, all-wheel-drive capability.
With a combined system output of approximately 268 horsepower, and 3,500 lb.-ft. of axle torque at launch, the RX 400h delivers rapid acceleration. At 7.3 seconds (7.5 for the all-wheel drive model), acceleration from zero to 60 mph is better than some V8-powered competitors.
The RX 400h is a 'full hybrid,' which means it can operate in electric-only or gas-engine-only modes as well as a mode that combines the power of the gas engine and electric motor. Lexus Hybrid Drive technology allows extended electric-mode operation during low speed or stop-and-go driving conditions, reducing fuel consumption and noise.
Energy is stored by a 288-volt DC Nickel Metal Hydride (Ni-MH) battery pack that fits neatly under the rear seat. The battery's power is directed through a 'boost converter' that efficiently raises voltage to 650V DC. An inverter changes this to 650V AC, providing its elevated power to a front-mounted 123-kW electric motor that turns as high as 12,400 rpm.
The RX 400h front-wheel-drive model's hybrid powertrain employs two motor-generators. Known as MG1 and MG2, each one performs specific functions and each does double duty as a motor and a generator (although MG1 is a starter and provides no motive force). The engine-driven generator (MG1) can charge the battery pack or power other electric motors as needed. The all-wheel-drive RX 400h adds a third motor-generator, MGR, to drive the rear wheels. Advanced Hybrid Transmission
Power from the gas engine and front electric drive motor (MG2) is distributed to the drive wheels via a planetary gear-type continuously variable transmission, which eliminates specific gear ratios. Two planetary gear units are used in the system. The Power-Split unit divides the engine's drive force two ways: one to drive the wheels and the other to drive MG1 so it may function as a generator. The Motor Speed Reduction unit reduces the speed of MG2 and increases its drive torque, significantly boosting acceleration performance.
MG2 produces peak torque from zero-to-1,500 rpm, giving the RX 400h powerful and instantaneous response in low- and mid-speed performance, especially in 30-50 mph merging and passing maneuvers. In addition to its motor/generator duties, MG1 also functions as a starter motor for the gas engine and as a regulator for the amount of electrical power it generates.
MG1 controls the output speed of the transaxle through the planetary gear set, without clutches or a viscous coupling. This is one of the key elements of the Lexus Hybrid Drive powertrain and is how it eliminates the 'shift shock' that is typically felt as even the most refined modern automatic transmissions change gears.
The all-wheel-drive RX 400h model uniquely generates rear-wheel power with a separate 50-kW electric motor (MGR) that provides up to 650 lb.-ft. of additional drive torque on demand. Thus, the RX 400h does not require power-transfer gearing or a driveshaft from the front. The system electronically varies front and rear torque distribution depending on traction conditions. Fuel-Conserving Partners
The power-steering pump, water pump and air-conditioning compressor are driven electrically rather than by the engine. This feature is necessary because the gas engine often shuts down – a fuel-saving benefit of the hybrid system – especially when the vehicle is stopped or driven slowly through traffic. Driving these components electrically also reduces parasitic losses to the engine and improves fuel consumption.
A regenerative-braking system further boosts efficiency. When the RX 400h is coasting or its brakes are applied, the electric motors function as generators, capturing kinetic energy that would normally be lost as heat through the brakes and transforming it into useable electricity to recharge the batteries. VDIM: Beyond Stability Control
The RX 400h was the first Lexus model to feature Vehicle Dynamics Integrated Management (VDIM). This vehicle stability control system goes well beyond conventional controls that simply react to challenging conditions. Instead, VDIM anticipates loss of traction in a turn and can help make corrections while allowing higher dynamic capability.
Electronically Controlled Brakes (ECB) are a vital element of VDIM. This advanced braking system translates brake pedal stroke speed and pressure and generates the precise amount of combined electric regeneration and hydraulic pressure needed for virtually any driving condition.
Únder guidance from VDIM, such precise brake control at individual wheels helps allow optimized operation of the vehicle's dynamic handling systems that employ the brakes, including the Anti-lock Braking System (ABS), Brake Assist, Vehicle Stability Control (VSC) and Traction Control (TRAC). VDIM also interfaces with the electronic throttle control system, allowing it to control vehicle power when needed, and an electric power steering system. The compact steering unit contributes to fuel economy by eliminating the traditional power-steering pump and by providing computer-controlled assist only when called for by the driver.
VDIM continuously calculates vehicle motion based on signals from a yaw rate and deceleration sensor, speed sensor and steering sensor. Úsing these inputs, VDIM controls all of the vehicle's dynamic handling systems and can employ them collectively and seamlessly, which can allow it to quickly detect and then correct the onset of a loss of traction in turns and help. The ability to operate proactively means that corrections to vehicle handling are typically faster, more accurate and subtler than traditional systems, making VDIM feel smoother and essentially transparent to the driver. Comprehensive Safety Systems
The RX 400h features the same passive-safety protection for occupants as the RX 350 model. A high-strength cabin design and comprehensive Supplemental Restraint System (SRS) are designed to help provide a high level of crash-energy management for the occupants.
SRS includes advanced front airbags for the driver and passenger, a knee airbag for the driver and front-seat-mounted side airbags. Side-curtain airbags are designed to help offer additional crash energy-management for the front- and rear-seat occupants. A roll sensor signals the side- curtain airbags to inflate if a predetermined threshold of vehicle tip-up is detected.Lexus Luxury and Impressive Útility
The RX 400h does not sacrifice space, comfort or versatility to deliver the benefits of hybrid technology. The rear seatbacks feature a versatile 40/20/40-split design, and the seats offer both sliding and reclining adjustments. The approximately 38-cubic-foot rear-cargo capacity expands to nearly 85 cubic feet with the rear seatbacks folded down. An automatic retracting tonneau cover adds a measure of security and convenience to the cargo area.
Lexus craftsmanship and renowned attention to detail provide true luxury by design. Standard features include dual-zone automatic climate control and 10-way power front seats with memory. The steering wheel features easy-to-use integrated controls for the audio system, trip computer and multi-information display in the speedometer. A rear back-up camera, part of the available navigation package, projects a color image of what the camera lens can detect behind the vehicle onto the navigation screen when reverse gear is engaged.
Because Lexus luxury also means outstanding convenience, the RX 400h comes equipped as standard with an auto-dimming rearview mirror with an integrated digital compass; auto-dimming, heated exterior mirrors; a power-rear lift gate, and integrated HomeLink® transmitter. Comfort and convenience extend to the smallest details in the RX 400h, such as adjustable lights in the visor vanity mirrors and illuminated front cup holders. A water-repellant surface on the front side windows helps to bead rainwater.
The RX 400h can be enhanced by a number of luxury options available separately or in packages. Some include power tilt/telescope steering wheel with memory, power tilt/slide moonroof with one-touch open/close feature and jam protection, memory for driver's seat and outside mirrors, towing-preparation package, roof rack and roof rails, and Dynamic Laser Cruise Control, which measures and helps maintain a set distance from a vehicle traveling ahead.
The standard Lexus Premium Audio system features an in-dash, six-disc CD changer. For the audiophile, the quiet interior of the RX 400h provides an ideal environment to enjoy the optional Mark Levinson® Premium Audio system that plays through 11 speakers. A sound-positioning feature optimizes speaker usage depending on occupant location. Rear-seat passengers can enjoy the optional rear-seat DVD entertainment system with individual wireless headphones and a large nine-inch LCD screen. Lexus Navigation System
The optional Lexus Navigation System allows the driver to input a desired destination by voice command while driving. A central VGA screen features a high resolution 800x480 pixel display in 32,000 colors. On-screen details are crisp and clean, and maps and roads include 3D shadow effects.
Text-display choices include English, Spanish and French, and the user can select the language preference at system start-up. System functions include multiple route calculation, route preview, simplified highway-junction graphics and a dual-map screen mode. The DVD map database contains more than five million points of interest. The database for Chicago, Detroit, Los Angeles, and New York includes a 'building footprint' display feature that can show graphic representations of buildings and structures to help the driver identify surroundings.
The navigation system also integrates Bluetooth® wireless technology. When combined with a compatible phone, Bluetooth allows the driver to transfer personal phone books to the navigation system and make hands-free phone calls through its touch-screen control panel.Premium Protection
All new Lexus vehicles come with a 48-month/50,000-mile basic limited warranty with roadside assistance for 48-months/unlimited miles. Powertrain and restraint system coverage is provided for 72 months/70,000 miles. Corrosion perforation protection is covered for 72 months, regardless of mileage. The hybrid-related components, including the HV battery, battery control module, hybrid control module and inverter with converter, are covered for eight years/100,000 miles.Source - Lexus