2010 Lexus RX450h

Press release

Lexus unveiled the all-new, next generation RX 350 and RX 450h hybrid at a press conference today at the Los Angeles Auto Show. The vehicle that pioneered the car-based luxury utility vehicle segment when it launched in 1998, is completely redesigned and will continue to set new benchmarks in areas that have made it the best-selling luxury utility vehicle: innovation, styling, performance, utility and comfort.

At the heart of the new RX models are two improved powertrains. Entering its second generation, the RX 450h will feature an enhanced Lexus Hybrid Drive system with a 3.5-liter V6 gas engine that runs on a highly efficient Atkinson cycle. Combined with a new, more efficient inverter, the total system output will be 295 horsepower, 27 more horsepower than the current generation RX hybrid.

Another step in the Lexus Hybrid Drive’s evolution is the addition of two new systems that improve its efficiency. The first is an exhaust-heat recovery system that reduces engine warm-up time allowing it to stop earlier, more often, and for longer periods. The result is an improvement in both fuel economy and emissions. The second is a cooled exhaust-gas recirculation system that reduces engine pumping losses, which also helps to improve economy.

The RX 450h features a front-wheel hybrid drive or an electronically driven, part-time all-wheel-drive (AWD) hybrid drive system, which supplies the rear wheels with the optimal amount of torque as conditions demand. Unlike mechanical AWD systems that reduce fuel efficiency via added weight and friction, the RX 450h’s rear-mounted electric motor-generator allows all four wheels to perform regenerative braking, charging the hybrid battery more effectively.

The third generation RX 350 will be powered by an improved 275-horsepower, 3.5-liter V6 engine mated to an electrically controlled, sequential-shift six-speed transaxle. The all-wheel-drive version will feature an Active Torque Control AWD system that optimizes torque depending on driving conditions, resulting in improved efficiency and performance.

Both RX models feature a new, uniquely designed double-wishbone rear suspension that helps provide exceptional agility and control. Its distinctive design also allows for five percent more cargo volume and easier loading. To complement the new rear suspension and provide excellent dexterity and ride comfort, the front McPherson strut geometry was optimized.

The all-new RX models possess a number of Lexus-first technologies that enhance the ownership experience. An available Hard Disk Drive (HDD) navigation system has an all-new "Remote Touch" controller that is both intuitive and ergonomic. Positioned on the center console, Remote Touch is as natural to the driver’s hand as a computer mouse. It can also be customized to the desired level of haptic feedback. While RX will feature voice recognition as standard, the new navigation system will also include a new casual language voice-recognition system that acknowledges conversational commands. Standard XM® satellite-radio capability (requires subscription) is joined by XM NavTraffic and new NavWeather features.

The spacious five-passenger interior includes a new, thoughtfully constructed "dual-zone cockpit" design. This intuitive layout helps the driver navigate the advanced interior of the new RX, which features two distinct yet integrated zones: a "display zone" and an "operation zone."

The "display zone" assists the driver via an eight-inch, navigation display that is set back in the dash for improved visibility. A white Organic LED multi-informational display ensures exceptional readability from a wide angle. An optional Heads-up Display reduces the need for excessive eye movement, and the use of high-intensity LEDs make the display bright enough to be read in direct sunlight.
The "operation zone" provides access and control to a large range of information through the available "Remote Touch" navigation controller and the steering-wheel-mounted multi-information switch.

The exterior of the all-new RX has a strong stance and powerful new body design with the goal of enhancing comfort and maneuverability. The inverted-trapezoid design in the front and the horizontally integrated rear are incorporated together via a pronounced shoulder along the RX’s profile. Stylish molding around the side windows and at the base of the doors provides low-profile strength. Standard 18-inch aluminum-alloy wheels complement the exterior with a strong, sporty look, with optional 19-inch aluminum-alloy wheels providing another styling cue. While it has increased in nearly every dimension, overall aerodynamic advancement was aided by a specially designed undertray, resulting in a segment-topping 0.32 coefficient of drag (Cd).

The RX 450h hybrid will have its own unique styling features, including an exclusive grille, hybrid badging including blue-trimmed Lexus logos, unique front bumper, a special 19-inch optional wheel design, blue-tinted headlamps and taillamps, and optional LED headlamps.

The new RX is available with a selection of luxury and sport option packages, which include features like Lexus’ exclusive Mark Levinson® Surround Sound system, a dual-screen rear-seat entertainment system, dynamic radar cruise control, and a Sports Package featuring a sport-tuned suspension.

The all-new RX will offer a wide-angle side view monitor. With a camera located under the passenger side-view mirror, the driver can check hard-to-view areas on the passenger side of the vehicle by simply selecting a button on the navigation screen or the steering wheel and view the camera image on the navigation screen.

True to its heritage, the RX’s active and passive safety systems continue to be among the vehicle’s most impressive features. Lexus’ available Vehicle Dynamics Integrated Management (VDIM) seamlessly integrates individual systems like Vehicle Stability Control (VSC), Anti-lock Braking System (ABS), Hill Assist Control (HAC) and Traction Control (TRAC). It operates in a smooth proactive way via throttle, steering and braking to help prevent skids while cornering before the vehicle reaches its operating limits on slippery roads or other challenging conditions.

The available Pre-Collision System (PCS) relies on millimeter-wave radar technology to recognize a possible frontal collision and primes the brake assist and retracts the driver’s and front passenger’s seat-belt in anticipation of the crash. An intelligent Adaptive Front-lighting System (AFS) is available with HID low- and high-beam headlamps on both models, while the RX 450h also offers the AFS with LED low-beam and Halogen high-beam headlamps. Both anticipate the vehicle’s location based on vehicle speed and steering angle, swiveling the front headlamps into the turn. An optional new automatic high-beam system detects light from oncoming vehicles, preceding vehicles or ambient sources and automatically switches from high to low beams.

Passive safety features include a class-leading 10 standard airbags on the new RX, including dual-stage driver and front-passenger airbags (including the Lexus exclusive twin-chamber front-passenger airbag), driver and front-passenger knee airbags, front and rear seat-mounted side airbags, and side-curtain airbags. It is also equipped with Lexus’ front-seat active headrests, designed to help reduce a possible whiplash injury when in certain lower speed collisions from the rear.

The all-new 2010 RX 350 will go on sale next February, while the 2010 RX 450h will reach dealerships nationwide in the spring.

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Hybrid Drivetrain

With each iteration, and now generation, of its Hybrid Drive system, Lexus continues to push forward its hybrid technology to increase efficiency and performance of its vehicles. Now, nearly four years after the debut of the RX 400h, the world’s first hybrid-powered luxury vehicle, the new Lexus RX 450h brings a broad range of improvements designed raise the bar in the luxury sport utility class once again.

With improved efficiency as their first priority for the new RX, Lexus engineers also actively pursued better acceleration and enhanced drivability. Another key goal was to improve fuel economy in cold temperature driving, an area traditionally difficult for vehicles using batteries as a primary or supplementary power source.

“The Lexus Hybrid Drive in the new RX is a perfect example of how Lexus uses kaizen to improve its vehicles,” said Lexus Vice President and General Manager Mark Templin. “The engineers found ways to improve the efficiency in virtually every aspect of hybrid system. And when you improve efficiency, performance often follows.”

The new RX 450h gains improvements in fuel economy with EPA-estimated ratings of 32 mpg in the city and 28 mpg in highway (30 mpg city on AWD) driving. Gains are even larger in cold weather driving conditions. Plus, there are tangible benefits to drivability, with torque increases where they are most beneficial and a new transmission control strategy that helps keep the engine in the most effective rpm range.

These substantial improvements are courtesy of several important changes to the RX’s Hybrid Drive system, each having prioritized goals (shown in parentheses) including:

• Basic engine improvements (increased power and fuel economy)
• Adoption of the Atkinson combustion cycle (improved fuel economy)
• Addition of a cooled exhaust gas recirculation (EGR) system (improved fuel economy)
• A new exhaust heat recovery system (improved fuel economy)
• Reduced friction losses in the hybrid transaxle (improved fuel economy)
• Artificial Intelligence (AI) Shift control (improved performance/drivability)
• A new power control unit [inverter and DC/DC converter] (improved performance and fuel economy)
• Increased motor torque on front (MG2) and rear (MGR) motor/generators (increased performance)
• New ECO driving mode (improved fuel economy)

 

Engine of Change

 

The RX 450h takes advantage of engine improvements shared with the new RX 350, such as roller rocker arms that reduce friction and give designers more freedom with camshaft profiles. These and other changes yield a nearly 20 percent increase in power.

Notable improvements in fuel economy came with several key changes that specifically benefit the hybrid system. The change to the Atkinson cycle and the cooled EGR are two of the keys.

With conventional four-cycle engines, there are times when fuel enrichment becomes necessary to cool the exhaust gases to prevent degradation or destruction of the catalytic converters. With the Atkinson cycle, the expansion/power stroke is longer than the compression stroke so that combustion energy can more effectively used for production of engine power. This results in lower exhaust gas temperatures.

In the process of re-circulating exhaust gas, the cooled EGR system increases the specific heat capacity, also resulting in lower exhaust gas temperature. Regulating the amount of EGR can also control the exhaust gas temperature.

The combination of the Atkinson cycle and cooled EGR minimizes the need for fuel enrichment. The benefit is significant reduction of fuel consumption, especially during high-load driving (e.g.: hill climbs and freeway driving).

The cooled EGR system allows precisely metered and spent exhaust gas to enter the intake system, lowering exhaust gas temperature while also reducing engine pumping losses via decreased intake vacuum. An EGR delivery manifold ensures even distribution of the exhaust gasses to all cylinders. The high-capacity EGR cooling system can reduce the gas temperatures from about 880˚ C to 150˚ C, improving volumetric efficiency. The cooled EGR also eliminated the need for exhaust VVT-i.

Calling All BTUs

Another key to improvements in fuel economy comes from the Exhaust Heat Recovery System. An important part of the hybrid control strategy is to stop the engine when it’s not needed, for example in low power demand conditions in city driving. But in winter driving, engine heat is needed to warm the interior cabin and demand on the electric drive motors will be naturally higher in these conditions, especially during warm-up. When temperatures drop below 0˚ C, battery output is also reduced and drive motor performance suffers accordingly.

To counter this challenge, Lexus developed an efficient system that recovers exhaust heat to quickly raise coolant temperature during warm-up. This allows the engine to stop sooner, helping to improve fuel economy during this phase. For example, testing at -5˚ C on a typical driving pattern (below) showed that the engine could be stopped a full 1,000 seconds (over 15 minutes) earlier than the previous model.

Exhaust heat is recaptured from the exhaust pipe just downstream of the catalyst where a recovery unit is mounted directly on the exhaust system. A thermostatically controlled valve forces part of the exhaust gas to re-circulate in a chamber, heating the surrounding coolant quickly. A spring in the valve allows it to open during full acceleration. When engine coolant warms sufficiently, the valve opens to allow exhaust gas to bypass the heat recovery system.

Hybrid Transaxle Gains Efficiency & Performance, Loses Noise and Vibration

 
Lexus’ elegantly simple and effective hybrid transaxle incorporates several improvements to support the goals for the new RX 450h. On the mechanical side, the adoption of an oil slinger and tuning/profiling of a number of components reduces drive losses; low friction bearings are installed in key locations; an oil cooler is now fitted. These changes combine to increased torque capacity and overall transaxle efficiency.

An improved flywheel damper employing a two-stage torque absorbing mechanism has been developed for the RX. The damper absorbs torque fluctuations as well as the shock created when the engine starts and stops. The new damper significantly reduces vibration and noise, especially in city driving when the engine starts/stops more frequently.

Artificial Intelligence (AI) shift control is implemented for the first time on a hybrid vehicle. The system estimates whether the vehicle is travelling uphill or downhill by comparing vehicle speed with accelerator pedal angle. Depending on the estimation, the transmission selects the appropriate shift range (from 3rd to 6th) to maintain engine rpm at an optimum speed for either acceleration uphill or engine braking when travelling downhill.

Lubricating Electrons

One of the most important developments that greatly improves the RX 450h’ efficiency is a new power control unit. Also known as an inverter, the power control unit has been called the heart of the hybrid system as it has a number of important functions and must work quickly and efficiently. Key functions include:

• Boosts hybrid battery voltage from 288 V to 650 V DC
• Converts hybrid battery voltage from DC to AC to power the drive motors
• Controls motor/generator operation
• Converts voltage of the hybrid battery to 14 V to supply accessory power and charge the auxiliary battery

The control unit uses a new, more efficient “stacked” cooling structure to greatly increase power density (40 percent) and contribute to reductions in unit volume (from about 30 liters to 18.2 liters) and weight mass (30 kg to 22 kg). Overall control unit losses are also reduced by 10 percent.
Changes in the operation circuit switching frequency reduce switching losses which also helps to improve fuel economy. Additionally, the higher operation frequencies reduce inverter noise.
 

Drive Motors Muscle Up

The electric drive motors in a hybrid drive system have the crucial dual roles of providing motive force and charging the battery pack. Both of the RX 450h drive motors have increases in maximum torque and torque range, contributing to improved acceleration and drivability. These improvements are in part facilitated by the new power control unit.

The front motor/generator (MG2) sees a small increase (2 Nm) of maximum torque but more importantly, the range of maximum torque is extended by 15 km/h. The rear motor/generator (MGR) receives a notably larger increase of torque (9 Nm) and extends its range even further—by 35 km/h.

The hybrid battery pack is also modified and although its structure and output is carried over, the total package is smaller and lighter than the previous unit. The more compact design improves packaging and minimizes changes between the RX 450h and the standard RX 350.

Three Modes for Different Moods

Three different driving modes add options for varied driving situations and individual desires:

• A new ECO mode provides a modified throttle action and air conditioning control to support efficient driving. This mode changes the relationship between pedal movement and system output to help the driver avoid aggressive acceleration and achieve smoother operation. The A/C load on the engine is also reduced more aggressively upon acceleration. Both these factors provide improved fuel economy.
• An EV drive mode, under certain conditions, allows operation of the vehicle with only the electric motors in order to reduce noise when driving in quiet areas and limit exhaust emissions in closed quarters such as parking garages.
• A sequential shift mode is also available by moving the transmission shift selector to the “S” position. In this mode, the driver can select any of six speeds to provide more responsive performance or to add engine braking assistance.

 

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Technologies

Lexus has long been recognized as a leader in the design and implementation of new user-friendly technology as well as control systems in its vehicles. Practical, simple and even elegant solutions to the operation of its cars and SUVs have been a virtual “holy grail” that Lexus has diligently pursued from its very beginning. The rationale for following this path is simple: The easier a vehicle is to operate, the easier and more pleasurable it is to drive.

The new RX also makes it easier for the driver to stay connected – whether it’s communication with family and friends, communing with your favorite tunes or finding what you want when you want it. Now, let’s take a look at some of the technology found in the 2010 RX.

Constant Connection

Bluetooth® technology now comes standard on the RX, and when paired with Hands-free voice recognition, makes it easier to complete phone calls without using a headset or even holding the phone. With the touch of a button, RX vehicles equipped with the navigation system can connect with phones that are capable of Phone Book Access Protocol (PBAP), and can wirelessly transmit up to a total of 1,000 contacts to the vehicle, for up to four phones.

Audio to Please Both the Amateur and the Audiophile

 

The new RX is available with three different levels of audio. The RX comes standard with a six-disc CD changer and 9-speaker audio system. Each front door is configured with a 3-way speaker setup consisting of a woofer, a mid-range and a tweeter, each carefully positioned to provide a rich and clear sound. A 12-speaker audio system is available with the navigation package, adding a tweeter to each rear door as well as a box subwoofer in the luggage compartment for added bass. The new six-disc DVD changer and available 330-watt 15-speaker Mark Levinson® premium surround sound system allows users to enjoy 7.1-channel surround sound on select CDs and DVDs. The Mark Levinson® system adds a center channel coaxial speaker with an additional speaker on each D pillar to provide the right and left surround sound channels. Also part of the package is a Mark Levinson amplifier that powers the enclosed subwoofer in the luggage compartment. All channels are driven from 20Hz-20,000Hz at 0.1% THD.

The new RX also tries to provide as many ways to listen to the driver’s preferred music as there are ways to store and broadcast it. In addition to AM/FM and CD Changer, the new RX features integrated XM satellite radio (subscription required after free trial) and three auxiliary inputs to connect the driver to their music: a mini-jack, standard Bluetooth AVP (Audio/Video-Profile) and an available USB/iPod connector. Bluetooth AVP-enabled devices, such as cell phones, can be wirelessly connected to the audio system and the music that is stored in the device can be played through the RX’s audio system. The USB/iPod connector will not only play the music on the device, it will display information on the navigation screen such as artist, album and track. The USB/iPod connector will even charge the multimedia device at the same time. Both the Bluetooth AVP and the USB/iPod connector allow the driver to control their music by using the onboard audio controls found on the steering wheel, dashboard and on the navigation screen allowing the driver to focus more on the road ahead. The RX also features an available Dual-Screen, Rear Seat Entertainment system with a 12-speaker audio system.

Tuned In To Your Drive

For the first time on a Lexus vehicle, the RX will feature available XM® NavWeather in addition to XM® NavTraffic (subscriptions required). XM® NavWeather provides near real-time weather conditions as well as a forecast of the days to come, both based on official National Weather Service data and overlays a map of those weather conditions on the current chosen route.

When en route to the user’s chosen destination, XM® NavTraffic informs the driver of current traffic conditions with real-time traffic displays. When traffic problems are detected, the navigation system alerts the driver so the route can be adjusted to avoid them. These data services are just one of the many ways Lexus has improved the navigation system for the new RX.

Next Generation HDD Navigation System

The available new navigation system on the RX can be controlled in two ways: a Lexus casual speech voice recognition system, or our new Remote Touch navigation controller.

Vehicles equipped with Navigation Package feature a new casual-speech voice recognition system that allows the use of more flexible, conversational commands for easier access and control. Voice command software enhances standard voice recognition and functions “on top” of the existing voice recognition system.

Without voice command, users need to speak commands in order, e.g., “Phone > Dial by Name > Bob,” in this specific order. With the navigation system’s voice command, this same task can be completed simply by saying, “Call Bob at home.” The voice command system also controls many functions of the audio system and climate control, like, “Make it cooler,” “Let’s find XM channel 150,” “Gimme a Japanese restaurant,” or “Where’s the nearest gas station along my route?” The system makes tasks easier to accomplish - and in fewer steps – with more flexible speech, allowing the driver to focus more on the road ahead.

Freeing the Eyes and Mind for More Important Tasks

Known simply as Remote Touch, the new navigation controller helps address the competing objectives of minimizing driver distraction while providing a range of options for customizing the driving experience. With constantly increasing feature content and complexity of today’s cars, finding ways to simply access and use them is a growing challenge. Concerns about driver distraction and the ability of users to learn to use the myriad features has limited their application in some cases. Other car makers have tried various solutions to these issues, with decidedly mixed results.
 
Faced with the same challenges, Lexus assembled a working group that included members from its product development, design, ergonomics and other engineering groups and charged them with creating and optimizing a new navigation system interface. Their efforts yielded a way to categorize the vehicle interior into two separate and distinct zones: display zone and operation zone. This perspective keeps the driver within comfortable reach of all controls while optimizing display and placement of information.

Designers placed the screen well forward and higher on the instrument panel, helping to notably reduce eye movement and refocusing from the road ahead to the screen—saving time better spent watching the road. The new screen, which also supports climate, audio, phone and other functions, is large, bright and clear. All are great benefits for the driver, but the team didn’t stop there.

The Joy(stick) of Feedback

Through their exhaustive research, the team realized that physical (and aural) feedback in the control system was a crucial step towards helping to reduce the “mental load” on drivers. This led designers to adopt a haptic device, or a device that provides force feedback to the user as the cursor moves over the screen. In this application, it helps make driving easier and more pleasurable by helping the driver locate the desired on-screen button by feel and sound.

The Remote Touch takes the shape of a moveable knob or joystick mounted in the controller. In order to control the pointer on the display screen, the operator moves the Remote Touch knob with his/her fingers, much like a mouse on a computer screen.

The feedback in the Remote Touch knob is most noticeable when moving the pointer over icons or “buttons” on the screen (example below left). When close enough, the haptic control “pulls” the pointer toward the center of the button with a feeling that is similar to rolling a ball over a flat surface and into a depression (below right).

Resistance is also generated in proportion to the speed used in Remote Touch knob operation, with resistance on the map screen higher than other screens. When the pointer is near the screen edge, force is generated to move the pointer toward the inside of the screen.

The force feedback is generated by two tiny motors on two axes of the joystick controller. The amount of force feedback can easily be adjusted through the setup menu.

The Lexus of Remote Controls

The Lexus team performed countless trials of prototype Remote Touch shapes and functionality of its switches. Initial designs condensed all of the switch functions into the Remote Touch knob, but this proved to be a disadvantage as it was prone to error. The final design of the Remote Touch is a model of comfort, simplicity and intuitive operation.

Remote Touch Functions:

• MENU switch – Displays the start
• Rocker switch – Zooms map screen and enables basic operations such as page scrolling
• MAP switch – Displays the map screen and current location
• Remote Touch knob – Controls the pointer on the screen
• Enter switch – Selects the icon or “button“as pointed by the haptic knob. Their location allows use of the thumb to operate, reducing the risk of errors. Can also be used by the passenger.
• Enter switch – Selects the icon or “button“as pointed by the haptic knob. Their location allows use of the thumb to operate, reducing the risk of errors. Can also be used by the passenger.
• DISP switch – Leaves the current screen and displays the screen effects screen

New Graphic User Interface Is Vibrant and Simple

The RX’s new graphic user interface (GUI) will be familiar to current Lexus owners, inheriting much the same visual structure as in previous Lexus Navigation systems. This helps speed users’ transition to the new system. Additionally, the new display is larger, brighter and features a higher contrast.

Importantly, the pointer is also easy to see, since your hand isn’t blocked by the screen. After about six seconds following the last Remote Touch knob operation, the pointer will disappear. When the knob is operated again, the pointer appears larger for about 0.3 seconds to assist visual location on the screen. When the pointer comes near an icon, a frame will appear around the icon to visually confirm it before selection. The size and shape of the pointer are customizable.

Sound feedback is used to enhance the ease of use of the new system. “Beep” sounds are used to indicate various operations, including:

• Enter – The enter switch is pressed with the cursor displayed and the operation is accepted.
• Selection – When pointer is moved and the cursor scrolls over an icon.
• Failure – When the switch is pressed and the operation is not accepted.

If the driver is confident in operation without the sound feedback, the sounds can easily be turned off.

Tailored for Individuals

 
Other controllers require the user to change their style in order to operate the system. The Remote Touch is just the opposite because it allows the user to customize the system to work best for them. Knowing well that a human’s ability to see, feel and hear inevitably varies, Lexus built in a number of customization options such as feedback force, the pointer size and shape, and the character and volume of operational beep sounds. Lexus is also aware that not all users are the same and that some might prefer additional methods of control. Knowing this, Lexus did its best to make sure that between the steering wheel controls, hard buttons and knobs, and the voice recognition system, the driver could control virtually every task without even using the Remote Touch at all. Even though a driver could potentially function without using the Remote Touch, Lexus is confident that the controller is so intuitive and user-friendly that it will quickly be integrated into the lives of its users.