Lexus RX400h - In Detail

Press Release

RX 400h - At a Glance

 

Hybrid Synergy Drive

·          The first-ever 4WD high performance hybrid SUV

·          3.3-litre petrol engine with a front and a rear electric motor, and a maximum system output of 200kW/272 DIN hp

·          Seamless acceleration from 0-100kph in just 7.6 seconds

·          Lowest premium petrol SUV fuel consumption on the market: 8.1l/100 km in combined cycle .

·          Low CO2 emissions: 192gr/km

·          NOx emissions close to zero

 

Safety

·          Segment first application of Vehicle Dynamics Integrated Management (VDIM), the Lexus' unique advanced vehicle stability control system

·          Electronically Controlled Brake system (ECB) to improve braking performance and brake energy regeneration

·          7 Airbags including the segment first driver knee airbag

·          LIFE ON-BOARD

·          Bluetooth® connectivity

 

Prologue

 

 

A close interest in his father's architectural career sowed the childhood seeds of Mr. Sadakata 's desire to become an engineer. After graduating from high school, he went to university to complete a doctorate in Mechanical

Engineering where, not yet qualified, he had already been identified by Toyota as a potential asset to the company.

 

"In Japan, the recruiting system is slightly different" Mr. Sadakata explains. "Especially in university. And companies often approach you in your last year to find out if you're interested in joining them. At the time, I was drawn to Seiko, but I had the opportunity to go and look round the Toyota Motor Corporation plant on an orientation day." One look, and Mr. Sadakata was hooked. "I was amazed by the sheer scale of the undertaking" he recalls. "The complexities of these huge machines performing such delicate, precision operations... it was such a striking counterpoint to the tiny, intricate process of watch manufacture. I thought, wow, this is amazing. And I decided, on the spot, to go for Toyota."

 

From the outset, Mr. Sadakata was fascinated by the rigorous scrutineering processes essential to the production of cars. "My first job was analysing Noise, Vibration and Harshness" he remembers. "And the first car I was directly involved with was the Crown - a model which only sells in our Japanese market. But, because there weren't two separate divisions when I joined Toyota -Lexus was merely a high quality division with the company- I started working on the first ever Lexus, the LS, at the same time. My specialty area was the study of wind noise around the windows."

 

More recently, far from believing himself already an expert in the field of hybrid drive systems, Mr. Sadakata's appointment to the RX 400h project came as something of a surprise. "At

the time, the decision to run with the RX400h project had not yet been made. But, because of a number of seminars I'd attended over the past few years, top management knew I was interested in new directions and thought".

 

Today, asked to choose from the raft of radical engineering solutions and technological breakthroughs encapsulated in one vehicle, Mr. Sadakata is reluctant to highlight any one element of the RX 400h which he considers to be its most impressive attribute. "Rather than picking one small detail, I would highlight the basic concept of the RX 400h, which is that everything is seamless in the driving experience. Every part, every movement must be seamless, and the handling so smooth that the driver remains unaware of the enormously sophisticated technology at work. I like to think of it as unnoticed technology."

 

In its long term management guidelines "Global Vision 2010" announced in 2002, the Toyota Motor Corporation defined its resolve to be a leader in environmental performance as an absolute imperative. As such, it is actively employed in improving fuel efficiency and reducing the exhaust emissions of conventional petrol and diesel engines, modifying engines so they use alternative fuels such as Compressed Natural Gas, and developing and popularising clean energy vehicles. "Howeve r, to fulfil our own company goals as well as satisfying the different, premium sector aspirations the Lexus customer has his car, the answer", avers Mr. Sadakata, "had to be hybrid technology."

 

"I think the use of hybrid technology will grow and spread through the market" considers Mr. Sadakata. "Currently it's all about how to use petrol as efficiently as possible, allied to

the greater horsepower you achieve. And this is behind the fun-to-drive aspect of the RX 400h."

 

"But, on the other hand, there is another technology, the fuel cell. And it's not that we are dividing these two technological fields.", Mr. Sadakata stresses. "It is merely that fuel cell technology is so complex that we see hybrid drive systems as the first essential step to its successful development. You have to have the one before you can achieve the other. In the end, then, it doesn't matter if the power source is petrol, diesel or even hydrogen; the hybrid system serves all sources as the most efficient way of using energy."

 

"Certainly, development of fuel cell technology will continue" he considers of the future. "But, ultimately, circumstances will decide whether that, or petrol, is at the core of the automobile market. The key point is in how you use the limited resources we have. We still don 't know how long the world's oil resources will last. Perhaps we'll develop ever increasingly efficient petrol engines and the oil will last longer than anticipated. So it's impossible to put a time scale on the compulsory shift to other power sources."

 

That such a fuel cell will be developed for mass-market motoring, Mr. Sadakata considers inevitable. "But, at the moment, there is no infrastructure in place for the mass-production of hydrogen. We must also consider", he is quick to point out, "that most of the manufacturing sources for hydrogen are themselves responsible for pollution, even if the fuel cell itself is 'clean'."

 

"And it's not just the technology" he stresses. "Society itself needs to embrace the new technology. Otherwise it will take a great deal of time and be very difficult indeed to make the change."

 

The World's First Performance Hybrid SUV

 

 In the new RX 400h, the Lexus Division engineers have created completely new, SUV oriented hybrid components based on the Hybrid Synergy Drive® concept.

 

This ground breaking development features the world's first hybrid system to employ a high power front and rear electric motor and a highly efficient petrol engine working in optimum collaboration both to provide an 'intelligent' electric 4-wheel drive capability and significantly improve low to mid-speed acceleration and fuel efficiency, whilst minimising CO2 emissions.

 

RX400h Hybrid Synergy Drive in Action

 

The Lexus RX 400h's exceptionally powerful Hybrid Synergy Drive® system combines the following characteristics to provide both superior fuel efficiency and driving performance:

 

·          First, energy loss reduction -the system automatically stops the engine at low vehicle speed and at idle, thus reducing expenditure of energy that would normally be wasted.

·          Second, energy recovery and re-use -the kinetic energy that would normally be wasted as heat during deceleration and braking is recovered as electric energy, which is then used to power the starter and the electric motor.

·          Third, motor assist -the electric motor assists the engine during acceleration.

·          Fourth, high efficiency operational control -the system maximises the vehicle's overall efficiency by using the electric motor to run the vehicle under operating conditions in which the engine's efficiency is low, and by generating electricity under operating conditions in which the engine's efficiency is high.

·          And fifth, seamless acceleration via electric, Continuously Variable Transmission.

 

Over the course of any journey, the new Hybrid Synergy Drive® system operates in several different modes to maximise the RX 400h's overall efficiency. When the engine is cold and the ignition is switched on, the system will start the engine to warm the unit. Thereafter, at rest, the engine stops automatically to conserve fuel.

 

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 CO2 emissions.

 

Under normal driving conditions, engine output is divided by a power split device both to drive the wheels directly and power the generator which, in turn, drives the electric motors and simultaneously charges the high-voltage battery. In these circumstances, power allocation is constantly monitored and adjusted between engine and motors to maximise efficiency. When sudden acceleration is required, engine and electric motors again operate in optimum collaboration with extra power supplied from the battery to boost motor response.

 

Unique to the RX 400h's Hybrid Synergy Drive®, the vehicle's rear wheels are driven by a rear electric motor to provide 'E-four' -Lexus' innovative Electric 4-Wheel Drive system- under various driving conditions. Controlled by the Vehicle Dynamics Integrated Management (VDIM) system, 4-wheel drive is automatically engaged via constantly adjusted front and rear electric motor torque under hard acceleration (both from a standstill and through the gears), when driving through corners and whenever the front wheels lose traction.

 

Moreover, during deceleration and under braking, the engine switches off and front and rear high-output electric motors act as high-output generators driven by all four wheels. This regenerative braking system optimises energy management in the new RX 400h's Hybrid Synergy Drive® system by recovering kinetic energy (normally wasted as heat under braking and deceleration) as electric energy for storage in the high performance battery. Furthermore, under all driving conditions, battery power and energy transfer levels are constantly managed via the engine driven generator obviating any requirement to recharge the system from an external source.

 

At all speeds, the RX 400h's Hybrid Synergy Drive® system monitors itself for optimum performance and fuel efficiency with minimum emissions, either running the electric motors in isolation, the engine in isolation or a combination of both. Details of this appear on a multi-information display in the driver's instrument binnacle. In cars fitted with the satellite navigation system, comprehensive data on power flow and the status of the high voltage battery appear on a 7", full colour monitor.

 

*1 This is calculated by combining the maximum output of the only two independent energy generating sources within the Hybrid Synergy Drive® system, the petrol engine and the battery. Hence the 155kW/211 DIN hp maximum power output of the 3.3 litre V6 combines with the 45kW/61 DIN hp output of the battery.

 

Performance

 

Producing a maximum power output of 200kW/272DIN*1 hp, the second generation Hybrid Synergy Drive® system gives the Lexus RX 400h a maximum speed of 200kph. Via continuously variable transmission, it will accelerate seamlessly from 0-100kph in just 7.6 seconds with none of the expected 'jumps' between the gears.

 

Proving substantially more frugal than rival models of a similar power output, the RX 400h boasts fuel efficiency levels never before achieved in a luxury SUV, returning 9.1l/100km under urban driving conditions, 7.6l/100km on the motorway, and a combined figure of 8.1l/100km.

 

Compliant with EURO IV emission standards, the new Lexus generates NOx emissions close to zero, and returns a CO2 emission figure of just 192g/km in the combined cycle. This represents a substantial reduction of 36% over the emissions of premium sector, V6 SUV competitors. Driving an RX 400h can reduce CO2 emissions by up 2.6 tons per annum*2.

 

*2 Calculation based on the combined EC cycle of SUV competitors V6 petrol engines, with 24,000 km driving a year.

 

"All car manufacturers will have some form of hybrid very soon -or are now planning something.", considers Karl Schlicht, Vice President, Lexus Europe. "And I think it's fair to say that Lexus' dedication to hybrid technology, and our early success, has surprised some other established manufacturers. It only makes sense that when NOx standards start to bite, diesels will become more expensive and hybrids even more attractive.", he continues. "The NOx story has been avoided in Europe, and this needs to change. There is a reason why in other markets, like North America or Japan, NOx standards are stricter than in Europe. Level the standards for particulate emissions globally, and hybrids become very attractive."

 

"Add the performance element offered by the RX 400h, and the proposition becomes even more interesting" says Schlicht. "When you consider global economies of scale, this again tilts the balance towards hybrids. Simplify the standards and take NOx into account, then let the consumer decide… Hybrids will represent a core technological advantage for Lexus. And as for its SUV application in the RX 400h; it's like letting you enjoy a chocolate sundae, but without the guilt."