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ACURA's Virtual-AWD ...who knew?

5K views 16 replies 6 participants last post by  2b2 
#1 ·
I don't follow Acura (my stomach gets queasy to easily for that
) so I was quite surprised while watching PBS MotorWeek this morning, to find out that ACURA is going full speed ahead with *my* long-ranted-for Virtual-AWD via electrics on the non-petrol-driven wheels, connected/co-ordinated by sensors-&-software rather than a mechanical transmission ...also coming on the NSX!!
Any help finding better articles about it, greatly appreciated!


sub(super)title: LINCOLN LOSES - LATE AGAIN
2014 Acura RLX Sport Hybrid [w/video] - Autoblog
A Wolf In Sheep's Clothing

By Jonathon Ramsey
Posted Dec 18th 2013


...(the RLX) bodywork hides a reversed rendition of the powertrain we'll get in the coming NSX: a 3.5-liter V6 up front shifts through a seven-speed dual-clutch transmission, aided by an electric motor for driving the front wheels and two electric motors in back propelling the rear wheels.

The seven-speed dual-clutch transmission is packaged with a 35-kilowatt (47-hp) motor that boosts power to the front wheels, as well as gathers regenerative energy from the front wheels and the engine to juice up the 72-cell, 1.3-kW lithium-ion battery pack in the trunk.

The Twin Motor Unit in back is two 27-kW (36-hp) electric motors separated by a clutch, each motor driving one of the rear wheels and able to operate separately. They can send positive (accelerating) and negative (decelerating) torque to either wheel and boast a torque differential wider than that of the mechanical SH-AWD setup, increasing the sedan's handling abilities and gathering energy for the battery pack. All three motors are ruled by the Power Drive Unit 'brain' under the center console, and the two in back operate independently of the 3.5-liter V6.

Trunk space is somewhat compromised compared to the standard RLX, with the Intelligent Power Unit located behind the rear seats dropping cargo space from 15.3 cubic feet to 12, but there is underfloor storage that provides another 0.4 cubic feet.

Instead of 310 horsepower and 272 pound-feet of torque in the gas-only RLX, the Sport Hybrid gets 377 total system horsepower and 377 lb-ft. The result is a much quicker car in a straight line – Acura doesn't go in for official 0-60 mile-per-hour times, so we're not sure by how much yet – and through corners, and better gas mileage thanks to assists from the electric-motor-enabled EV mode, cylinder deactivation during steady-state driving and idle stop. The standard RLX gets 21 city, 31 highway and 24 combined miles per gallon, while the RLX Sport Hybrid gets 28 city, 32 highway and 30 combined.

The RLX Sport Hybrid gets .... a center of gravity that is eight millimeters lower and a different weight distribution because of the battery pack and Twin Motor Unit: whereas its FWD sibling has a front-rear balance of 61 percent to 39 percent, the Sport Hybrid is slightly more balanced at 57-43 front-to-rear.

More... with *WARNING*photos*WARNING*
 
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#2 ·
2014 Acura RLX Sport Hybrid moves forward with three electric motors - Newsday
Originally published: January 3, 2014
Updated: January 4, 2014
By MALCOLM GUNN Wheelbase Media


Honda finally has its hybrid groove on...
...the new RLX Sport Hybrid SH-AWD blazes a fresh trail.


For most hybrids, the common industry practice is to use a single electric-motor assist (for each pair of driving wheels) that can function independently or in tandem with the gas engine, as the need arises. But in the all-wheel-drive Sport Hybrid's case, Acura has developed a unique three-electric-motor system.

To begin with, the rear-drive Twin Motor Unit (TMU) uses two 36-horsepower electric motors (one for each wheel). They operate exclusively as the RLX begins to slowly advance from a stop and during low-speed cruising for up to two miles. Then the 310-horsepower V6 engine (also used in the standard RLX) is engaged.

When accelerating slowly, both the V6 and the 35-kilowatt (47-horsepower) electric-motor companion in front take over from the TMU.

But when you aggressively depress the go pedal, the V6 and the three electric motors bring a combined 377 horsepower into play to drive all four wheels. The all-wheel-drive mode also seamlessly kicks in whenever slippery conditions are detected.

When decelerating, the electric motors convert braking energy to electricity, which is fed to the 360-volt lithium-ion battery pack located behind the rear seat. No worries, it consumes only a modest amount of trunk space.

The TMU also assists during cornering by apportioning additional torque to the outside rear wheel and at the same time eliminating or even reversing torque supplied to the inside wheel. This torque-vectoring effect noticeably helps the RLX pivot with certain precision, especially at higher speeds.

The V6 is assisted by a seven-speed automated manual transmission (with paddle shifters and no clutch pedal) that's integrated with the electric motor.

In city driving, the Sport Hybrid's fuel thriftiness earns a 28-mpg rating compared to 20 mpg for the front-wheel-drive gas-engine RLX, even though the hybrid weighs an extra 350 pounds. In highway driving, the Sport Hybrid improves on the base RLX's 31-mpg number by just a single mpg.

The powertrain is controlled through a nifty floor-console-mounted gear selector that replaces the traditional shifter. It includes buttons and switches for Drive, Neutral and Reverse and there's an electronic e-brake switch.

Whether in electric-only or gas-electric mode, the cabin is luxury-car quiet and comfortable under normal driving conditions. It's only when you unleash the powertrain's potency with your right foot that an aggressive engine growl becomes apparent.

The car's inherently sporty nature can be further amplified by pushing the "Sport" button on the gear-selector console, thus changing the RLX's orientation from fuel sipper to quasi-performance machine. At this point the entire powertrain springs into action, resulting in brisker acceleration and crisper shifts from the transmission, including throttle-blipping (rev-matching) downshifts. In fact, the transmission seems to "sense" the correct gear to select based on velocity and braking parameters so you're ready to go when getting back on the gas.

Speaking of braking, they're not as grabby as in other hybrids.

At an estimated base price in the low-$60,000 range, including an impressive assortment of luxury and safety bells and whistles, the Acura Sport Hybrid will cost at least $10,000 more than the base RLX when the hybrid arrives in early 2014. That's competitive with similar premium hybrids on the market, but on its technological merits alone, the Sport Hybrid shows the way forward...

...One of the most advanced and complex hybrid powertrains on the market; Hybrid system similar that of upcoming NSX sports car; Fuel economy particularly impresses in city driving; Torque vectoring system aids turning...
 
#4 ·
^ just-imho, that isn't the point, torino429
note the 40% mpg improvement while making over 100hp more. also
My ranting (& thread title) point to AWD withOUT origami driveshafts...


Acura RLX Sport Hybrid SH-AWD - Car&Driver
Honda is finally bridging the hybrid-technology gap.

December 2013
BY K.C. COLWELL


...the industry released ever more intricate and efficient [electrified] designs ... with the Chevrolet Volt plug-in coming in as the hybrid-tech high-water mark. Well, until now...

...When the subject of this story, the Acura RLX Sport Hybrid SH-AWD—or “SH SH-AWD” for short—was announced, many thought that it would share its hybrid guts with the NSX, only in reverse. That isn’t the case, except perhaps philosophically. The only common bit between the two cars is what Acura calls the twin motor unit (TMU). In the RLX SH SH-AWD, the TMU is fixed to a rubber-isolated subframe at the rear axle and is what enables the RLX hybrid to offer four-wheel drive via two identical 36-hp electric motors that are coupled together by a planetary gearset and produce 54 lb-ft of torque.

Below 78 mph, each motor can supply torque to its assigned wheel independently via yaw-inducing torque vectoring, or the two can work in concert to contribute thrust or braking. Above 78 mph, the TMU can still perform the torque-vectoring trick, but it ditches its acceleration and deceleration duties. Controlled via electronics and connected to the rest of the powertrain only via wires, the TMU means there’s no driveshaft. It’s unique among torque-vectoring differentials in that it can deliver torque to one tire while the other pulls torque (or, put another way, produces negative torque) and feeds the energy into the regenerative braking system.

As you dive for an apex, you feel the SH SH-AWD’s TMU fend off understeer and revector the car just as well as the mechanically based SH-AWD (Super Handling All-Wheel Drive) system did in the old RL, which was replaced by the RLX. The TMU is doing the lifting at every step away from a stop; the RLX hybrid can operate as a pure electric, rear-wheel-drive car up to about 50 mph provided you’re gentle on the throttle. (So, no, you can’t do lurid drifts.) Another caveat to RWD awesomeness: Range in this mode is limited to a mile or two from the 1.3-kWh lithium-ion battery. If it doesn’t deliver fun or long, silent cruises in the moonlight, the EV mode does allow the 4350-pound Acura to score highly on the EPA’s city mileage test, where it notched 28 mpg. That’s an improvement of 40 percent over the front-drive, nonhybrid RLX. The hybrid’s 32-mpg EPA highway rating is 1 mpg better than that of its conventionally powered sibling, which is to be expected, given that a hybrid is most beneficial in urban driving where it can recapture and use electrical energy more often...

...Acura says the transformation to hybrid adds 357 pounds, including extra standard content such as a head-up display and LED fog lamps. From a dynamic standpoint, the extra mass isn’t noticeable to the driver, thanks in part to the torque vectoring and in part because 198 pounds—132 of which are assigned to the TMU and 66 to the battery—are piled atop the rear axle, shifting the fore-to-aft weight balance from 61/39 percent to 57/43...
 
#5 ·
AWD isn't the cure all for FWD dynamics as it cannot solve the overwhelming front weight bias. Even if a car could be set up to push itself out of corners with a rear bias its still going to plow through them given the bias. On the other hand if they were to move the front axle forward, creating almost a front mid-engine platform the packaging benefits of FWD would be largely lost. Like most things in life it's a choice, develop for the masses or the fringe enthusiasts and mass market brands like Ford have to aim for the largest target market. Unfortunately the current generation are largely auto-enthusiast free so I suspect the move will continue away from perfect sporting machines to perfect appliances.
 
#6 ·
Technology like this really is the future. Gone soon will be the days of heavy and bulky gears/chains/differentials linked mechanically to both drive systems. Sophisticated electronics, viscous coupling, secondary drive motors, etc. are not only used for traction, but linked to safety too with TC and ABS, etc. and can compensate and readjust in the tiniest fractions of a second. Wait until you get a feel of torque vectoring with an AWD system that somehow pulls you into the corner instead of pushing you out. I think Ford is offering it on the MKC first.
 
#7 ·
AWD isn't the cure all for FWD dynamics as it cannot solve the overwhelming front weight bias. Even if a car could be set up to push itself out of corners with a rear bias its still going to plow through them given the bias. On the other hand if they were to move the front axle forward, creating almost a front mid-engine platform the packaging benefits of FWD would be largely lost. Like most things in life it's a choice, develop for the masses or the fringe enthusiasts and mass market brands like Ford have to aim for the largest target market. Unfortunately the current generation are largely auto-enthusiast free so I suspect the move will continue away from perfect sporting machines to perfect appliances.
by No means do I think HondAcura has this completely figured out
AND they're not even the first to try some form of Virtual-AWD
Volvo has an S60-Hybrid (not available in the US afaik) and I saw snippets about a Nissan doing it quite some time ago (again afaik not on a US model)
...but...
consider if HA hadn't gone high-power (again) and instead had substituted a smaller turbo petrol engine = instant weight distribution closer to 50/50 (or whatever proves best)
((and
with electrics producing instant torque... ))
I foresee electric-HP equalling fuel-HP in leading hybrids before the end of this decade
(as I proposed for some of my Mission2020: The RETURN Of MERCURY models!!! )
 
#8 ·
While I certainly appreciate the technology of the electric motors and a beautiful dual clutch trans, the package in which its in is so boring. The RLX is just doesn't say anything, it looks like it could be a bigger Accord and that's not a good thing IMO.
 
#9 ·
While I certainly appreciate the technology of the electric motors and a beautiful dual clutch trans, the package in which its in is so boring. The RLX is just doesn't say anything, it looks like it could be a bigger Accord and that's not a good thing IMO.
CUV's like the RLX typically follow a function over form design theme, but the RLX leans more toward form while sacrificing some roomy function. Not a bad thing, just not very popular based on sales.
 
#10 ·
CUV's like the RLX typically follow a function over form design theme, but the RLX leans more toward form while sacrificing some roomy function. Not a bad thing, just not very popular based on sales.
RLX is not a CUV ?? The RLX is the brand's flagship and a flagship needs to at least have presence. RDX and MDX are the crossovers.

The mistake is acceptable and highlights Acura's awful naming strategy.
 
#15 ·
was thinking....
Car&Driver(redux) said:
...When the subject of this story, the Acura RLX Sport Hybrid SH-AWD—or “SH SH-AWD” for short—was announced, many thought that it would share its hybrid guts with the NSX, only in reverse. That isn’t the case, except perhaps philosophically. The only common bit between the two cars is what Acura calls the twin motor unit (TMU). In the RLX SH SH-AWD, the TMU is fixed to a rubber-isolated subframe at the rear axle and is what enables the RLX hybrid to offer four-wheel drive via two identical 36-hp electric motors that are coupled together by a planetary gearset and produce 54 lb-ft of torque...
this^
sounds like the NSX won't have much more than the "377 total system horsepower and 377 lb-ft" of the RLX

imho that'd make a nice "middle-model"
but afaik that's the only setup it'll get...

...a LincStang with a reasonably tuned Nano-EB (maybe even without my "electrification") oughta CREAM it
:rock:
 
#16 ·
was thinking....
this^
sounds like the NSX won't have much more than the "377 total system horsepower and 377 lb-ft" of the RLX

imho that'd make a nice "middle-model"
but afaik that's the only setup it'll get...

...a LincStang with a reasonably tuned Nano-EB (maybe even without my "electrification") oughta CREAM it
:rock:
The NSX will have a twin turbo V6, not the naturally aspirated unit like in the RLX.
 
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