Subaru VIZIV diesel plug-in hybrid concept debuts at Geneva; independent-rear-motor-driven symmetrical AWD
06 March 2013
|VIZIV Concept. Click to enlarge.|
Fuji Heavy Industries Ltd. (FHI), the manufacturer of Subaru automobiles, introduced the VIZIV (“Vision for Innovation”) hybrid crossover concept at the Geneva Motor Show.
The powertrain is a plug-in hybrid system that combines a 2.0-liter Subaru Boxer diesel engine and high-torque-compatible Lineartronic continuously variable transmission (CVT) with a single front motor that provides both vehicle drive and power generation, and two independent rear motors for vehicle drive only. The 100% motor-driven rear wheels eliminate the need for a propeller shaft, creating a lower floor that offers ample legroom for rear seat occupants despite its compact size.
The VIZIV Concept features an independent-rear-motor-driven symmetrical AWD (all-wheel drive) system which points to a future generation of Subaru AWD technology. The independent-rear-motor-driven symmetrical AWD system provides fine-tuned control of the four wheels.
The two motors control the rear right and left drive power independently. By independently controlling the drive power applied to the left and right rear wheels, the rear drive system provides more torque to the outside rear wheel and less to the inside rear wheel when cornering to generate inner-directed yaw momentum on the vehicle and achieve extremely quick and smooth on-the-rail cornering.
Coordinated management system of the front and rear motor controls the division of drive power between the front and rear wheels. Turning the steering wheel increases the drive power applied to the rear, creating a handling characteristic that responds nimbly to driver operations. Turning the steering wheel back increases the drive power applied to the front, creating a handling characteristic that emphasizes stability.
The powertrain selects the best time to use each power unit according to its strengths and the driving application. The motors start and drive the vehicle during low-speed or city driving, while the diesel engine and high-efficiency Lineartronic take over on the highway.
The “Hybrid SI-DRIVE” system has an “Eco-Cruise” mode that provides coordinated control in conjunction with the “EyeSight” driving assistance system in addition to “Intelligent” and “Sports” modes. Engine and motor power are subjected to control according to the travel conditions captured and detected by the EyeSight’s stereo camera.
The 100% motor-driven rear wheels eliminate the need for a propeller shaft, creating a lower floor that offers ample legroom for rear seat occupants despite its compact size.
Posted by: SJC | 06 March 2013 at 07:51 AM
This could become a winner for people who really need AWD and reduced fuel consumption.
May be ideal for cold snowy winter days when AWD is a real asset.
By using the e-motors ONLY for the first few Km, one may be able to hide the noisy use of diesel ICE?
Posted by: HarveyD | 06 March 2013 at 08:02 AM
Many AWD designs use the Haldex coupling which is a wet multiplate clutch engaged by electronics and hydraulics. It is not AWD all the time, but the engine has to drive a transfer case and drive shaft all the way to the rear coupling at the differential.
This idea will be on the Audi A4 in 2014. A motor/alternator in front and TWO motors in back, one driving each wheel for vectored thrust propulsion. Good designs are finally making it to the market...finally.
Posted by: SJC | 06 March 2013 at 09:16 AM
This is only a concept but I would agree that having an electric only drive for the rear on an AWD vehicle when you only need AWD occasionally makes a lot of sense. It also lets you recover energy from rear wheel braking which most of the current hybrid vehicles do not do.
Posted by: sd | 06 March 2013 at 03:34 PM
Diesel + hybrid = good. But why no MPG numbers? Come in Subaru, we are dying to know.
Posted by: Jus7tme | 06 March 2013 at 05:09 PM
>>It also lets you recover energy from rear wheel braking.
Apparently not in this vehicle, though, since the article says "and two independent rear motors for vehicle drive only."
Too bad. On the other hand, recovery from front wheels is more significant anyway (due to uneven front/back force distribution, especially while braking).
Posted by: Jus7tme | 06 March 2013 at 05:14 PM
Energy recovery is typically a function of the size (power) that the motor/generator and battery can handle, not how much torque the front wheels can handle.
But using electric motors for the rear (even forsaking the efficiencies the multi-speed transmission provides) has a certain charm.
Posted by: ToppaTom | 07 March 2013 at 06:51 PM