Honda as re-embraced four-wheel steering, a feature the company pioneered back for mass-produced cars in 1987 then abandoned soon after the Japanese bubble economy burst in the 1990s.
The new 4WS system, using electric motors on the rear wheels, was among a suite of technology showcased at the Earth Dreams summit at the company’s rebuilt head R&D Centre at Tochigi in Japan last month during the 2013 Tokyo motor show.
Also demonstrated were lightweight bodies, new safety and autonomous driving technology, and a trio of turbo engines.
The centre was severely damaged – with one fatality and many injuries – during the earthquake that accompanied the 2011 tsunami.
The new 4WS system, first released on the RLX Acura in the US, does without any solid connectors from front to rear. Electric motors can alter the angle of the rear wheels in either direction, even independently of each other.
The steering angle change is only 3 degrees (1.5 degrees in each direction), less than the old Prelude, so some of the engineers refer to it as active toe-control. Active rear steering systems are becoming increasingly common in new vehicles – from Peugeots to Porsches – in an effort to improve dynamics and stability.
However, the Honda system is made far more effective by a new hybrid version of the car demonstrated at the research and development facility.
In this vehicle, two electric motors, generating 27kW between them, each power a rear wheel and can provide torque vectoring. This means one rear wheel can push out more power than the other to assist stability or cornering, or can brake to feed power back into the electrical system. And that’s as well as changing angle.
These electric motors work in league with a conventional petrol engine upfront that powers the front wheels in what is rather excruciatingly called the Acura RLX SH-AWD Super Handling (with the SH standing for “Sport Hybrid”).
A drive on a tight handling circuit showed the system dramatically improved the turn-in of what is otherwise a softly sprung US-style luxury sedan.
Project leader of the model, Mr Aoki, confirmed that improved handling and driving enjoyment was the main target, the added safety a by-product.
He wouldn’t confirm whether such a system will be extended to sports models, but did confirm the RLX hybrid system uses the same principles as that in the forthcoming Honda NS-X supercar.
That however, will drive the rear wheels with a mid-engined turbocharged V6 engine (of unspecified power), and use its electric motors on the front wheels.
Under a slew of slogans – Earth Dreams, Blue Skies for our Children, Safety for Everyone and the “man-maximum, machine-minimal” design philosophy – Honda also presented the Accord Hybrid that is on the shopping list for Australia, and a plug-in version rated at a remarkable 2.05L/100km, which is not.
Also presented were Honda engineers own take on other features available from competitors, including collision avoidance technology, blind spot monitoring, unmanned self-parking and autonomous driving.
The chance to be chauffeured by a self driving Accord around a test track – and to watch it brake or swerve for pedestrians and motorcycles – was fascinating.
The system uses V2V (vehicle to vehicle) and V2I (vehicle to infrastructure) communications as well as on-board sensors, but will require much government cooperation on the infrastructure side before being unleashed on public roads. With this in mind, Honda demonstrated the system two weeks ago to the Japanese prime minister, Shinzo Abe.
Honda R&D boss Yoshiharu Yamamoto says the company might have an autonomous driving car on sale by 2018, though admits it won’t be a so-called Stage 4 car, which is to say fully self-driving.
Steer-by-wire was recently released on the Infiniti Q50. Honda’s system gives a remarkably traditional feel with some real advantages over conventional systems, including no kickback even on a tight bumpy circuit possibly designed specifically to incite kickback.
Mr Yamawaki, the engineer in charge, said “the technology can be suitable for all cars, but we are not sure yet which cars we will apply it to”.
Unfortunately there are no weight savings. The lack of a steering shaft and rods is countered by the mechanical back-up system installed in case of failure.
We also had the chance to punt around the same course a prototype CR-Z coupe built around a carbon fibre tub. Said to halve the normal body weight, this also adds a million yen premium at this stage of the development. That’s about $10,700.
The main problem is that it was necessary to step over a Lotus Elise-style doorsill to get into the cockpit. This sill was so high, that when the doors were opened, an additional portal in the roof lifted to give more access.
With lots of exposed carbon-fibre and uncovered wiring, the car was very loud and raw, making the Lotus comparison even stronger.
Although using the standard drivetrain, it was in another league to the everyday CR-Z: fast, responsive and great fun.
Also on display were full electric cars, including a new micro commuter known as the MC-Beta, and three engines that show a new interest in turbocharging from Honda.
These include a three-cylinder 1.0-litre producing 95kW and 200Nm, a 1.5-litre four-cylinder (150kW/260Nm) and a 2.0-litre (206kW/400Nm), which is slated for a future Civic Type-R hot hatch.
Executive Toshihiko Nonaka said the CVT, or continuously variable transmission, will be the main choice for Honda vehicles of the future, but the company also showed an ingenious double clutch automated manual.
This eight-speeder is the first double clutch transmission with a torque convertor, incorporated to overcome the main criticism of such units as VW’s DSG: roughness at city speeds.
Whether it can achieve similar efficiency as well, isn’t clear. Nor alas, is there any information on when it will go on sale.
Source;
http://news.drive.com.au/drive/motor-news/fourwheelsteer-returns-for-honda-20131211-2z4z7.html
