Honda Motor Co. in Tokyo, Japan recently announced it has developed a new all-wheel drive system — and it’s apparently intended for high-performance sedan application. Dubbed in true Japanese fashion as a Super-Handling All-Wheel-Drive system, or SH-AWD, Honda claims their latest take on the all-wheel-drive technology is a world’s first, as the SH-AWD combines front to rear torque distribution control, plus an independently regulated torque distribution to the left and right rear wheels as well. Thus, depending on the driving conditions, the optimum amount of torque going to all four wheels is ensured.
Honda added that the SH-AWD will provide cornering performance that responds faithfully to driver input, resulting in superb vehicle control. The good news is SH-AWD will already be available on production models, specifically the new Acura RL that’s sold in North America and in the Legend sedan in homecourt Japan.
The SH-AWD system is composed of sensors that detect steering angle, lateral g-forces, and sundry vehicle information, and an ECU plus the rear differential. The direct electromagnetic clutches inside the rear differential — another world’s first, as Honda crows — employs electromagnets to obtain precise control over the multi-plate clutches. Built-in search coils monitor the gaps between the electromagnets and the magnetic body to achieve precise, continuously variable torque regulation.
And yet another world’s first can be found on the SH-AWD system’s rear differential, according to Honda, which the company says is a built-in acceleration device.
As engineers and most gearheads have known through the years, the track of a vehicle’s outside rear wheel normally fall outside the track of the front wheels when cornering. That’s because the outside rear wheel does not rotate fast enough to keep up with the front wheels, thereby preventing efficient transmission of torque. To correct this characteristic inherent on most vehicles, the SH-AWD acceleration device will alter its gearing in order to speed up the outside rear wheel’s rotation relative to the front wheels’. This, Honda claims, reduces torque losses and significantly improves vehicle maneuverability. At least, that’s what in theory it should do.
Honda said the rear differential’s direct electromagnetic clutches continuously regulate and vary front wheels-to-rear wheels torque distribution between ratios of 30:70 and 70:30, and the distribution between the left and right rear wheels to ratios of 100:0 and 0:100. Needless to say, here, torque is used not only for propulsion but for cornering as well.
The new SH-AWD system also features what Honda calls "feed-forward" control, which again sounds truly Japanese in cryptic anime/sci-fi genre fashion. What this thing does is it utilizes the degree of driver input to determine appropriate torque distribution. Honda says this results in a "super-neutral steering feel that responds with optimal faithfulness to the driver’s handling of the steering wheel, realizing outstanding driving comfort and stability", which now sounds more like anime/Zen — if only such a thing exists.
But Honda asserts this is necessary, as "driving pleasure is regarded as one of the most important factors in vehicle development." Taking the company’s word for it, then the already delightful Civic should be utterly scrumptious if it gets the SH-AWD treatment.