http://www.goauto.com.au/mellor/mellor.nsf/story2/66C9741E5EA06DB4CA257C2E000BDF33
Quote.
Rotary club: Mazda’s compact rotary-powered range-extender provides a
surprisingly compact recharging unit for future generations of electric
vehicles that could spin off from the Mazda2 EV.
25 November 2013
By BARRY PARK
<http://www.goauto.com.au/mellor/mellor.nsf/writers?readform&author=Barry%20Park>
in TOKYO
The roll-out of battery-electric vehicles throughout the world has given
rise to a new phenomenon known as range anxiety, where electric car
drivers worry about how far their batteries will carry them, and fret
that they will run out of juice short of their destination.
Takashi Suzuki, Mazda’s program manager for advanced powertrains, said
that since the launch of a battery-powered version of the Mazda2 in
Japan last year, seven out of 10 customers said they were either
“dissatisfied, or very dissatisfied”, with the car’s 200km range,
despite the availability of quick recharging services.
“That is a problem with many EV users today,” Mr Suzuki said. “We needed
to solve the problem from the automotive side; we could either increase
the amount of battery storage, or think about range extenders.”
Those fears have already spurred a generation of long-range plug-in
hybrid electric vehicles such as BMW’s forthcoming i8 sports car and
Mitsubishi’s Outlander soft-roader, and the Holden Volt hatchback, as
well as range-extended electric vehicles as BMW’s i3 city car.
The idea for cars such as BMW’s i3 is to add a small petrol motor that
acts as a generator, recharging batteries on the fly to double the range
of the vehicle compared with just battery power alone.
While BMW has fitted the i3 with a motorcycle engine, Mazda has taken a
less conventional approach – fitting a compact, horizontally mounted
rotary engine to a generator that can sandwich into a tight space.
According to Mazda, the beauty of the 330cc rotary engine, aside from
its compact form, is the engine’s ability to run on a number of
different fuels such as butane and propane, the key ingredients in LPG,
and not just petrol. It also has fewer moving parts, making it cheaper
to manufacture than a conventional engine.
Pointing more towards its future application, the car-maker has run a
fleet of rotary-engined RX-8 sports coupes for almost a decade using
hydrogen as a fuel, and producing only water as a by-product.
Now, it has expanded the technology to a one-off Mazda2 concept car
called the TPEV.
Mazda has taken a plug-in battery electric version of its city-friendly
Mazda2, hooked the rotary engine up to a 20kW alternator, and hung it
off the chassis where the fuel tank would normally sit. (26 HP)
The idea is that the plug-in Mazda2 will run just like an electric
vehicle until the batteries fall to a certain level of charge. Once that
threshold is reached, the rotary engine will fire up to recharge them,
doubling the range of the Mazda2 to about 400km.
(250 miles)
In theory, that’s not all that fuel efficient. The current car has a
nine-litre fuel tank, which means the average fuel economy over the
400km range is an impressive 2.25L/100km – although nowhere near the
Holden Volt’s official 1.2L/100km average.
(62 miles on .6 gallon or 104 MPG)
However, this is a prototype engine, and Mazda says the production
version of the range-extended Mazda2 would need to either match or
better the BMW i3’s 0.6L/100km average.
To look at, the range-extended Mazda2 is surprisingly normal. It sits on
tiny 14-inch alloys clad in Yokohama Aspec rubber.
Instead of a fuel flap for the petrol tank down the rear, the Mazda2 EV
features a flap on the front guard that opens up to a standard electric
vehicle recharging plug.
Down the rear is a bit different, though. Instead of a factory diffuser
below the rear bumper, engineers have patched on a low-hanging black
plastic panel that features a block of small holes drilled out of it to
provide ventilation for the rear-mounted recharging unit.
For testing purposes, Mazda has set up the rotary recharger to kick in
at speeds above 10kmh – handy given that our test loop is two laps of a
100-metre length of narrow tarmac squeezed in between a building and a
chainlink fence.
The joy of electric motors is that they are well suited to accelerating,
taking very little time to reach maximum torque. It’s the same in the
electric Mazda2.
The car builds speed quickly, reaching 10kmh within seconds. There’s a
slight shudder, and then a noise like a leaf blower from down the back
of the Mazda2 as the rotary-engined generator fires into life.
According to Mr Suzuki, the electric motor only needs to use about 80kW
of electric power when accelerating. However, at other times the motor
was using far less power, so all the range extender had to do was
provide the average range of power, about 20kW.
(80KW = 107 HP)
To account for the system’s baseline need, the 330cc rotary produces
22kW at 4500rpm, stepping up to 28kW at 6000rpm.
(28KW= 37 HP. Not much as an AIXRO kart rotary is 50 HP.)
Because the engine is mounted horizontally in the 100kg recharging unit,
Mazda was able to use softer mounts to isolate more noise and vibration
from the cabin.
Accelerating in the Mazda2, once the shudder of the rotary’s start-up
has gone, the range extender’s operation is smooth to the point of
unnoticeable.
However, instead of the noise from the EV’s normal operation disguising
the noise of the generator unit, as Mr Suzuki suggested it would, the
rotary provides a constant drone akin to a leaf blower.
Slow down again, and as the speed drops below 10kmh the rotary engine
cuts out, producing another slight shudder as the batteries become the
only source of power for the motor mounted between the front wheels.
Mazda’s plans for the range-extender run beyond just its automotive
application. Mr Suzuki said the unit could become a source of
electricity in the event of a natural disaster, and could even make its
way into commercial portable power generators thanks to its compact form
that gives huge weight advantages over existing units.
Even better, Mr Suzuki said because the range extender was a bolt-on
unit that fed to the batteries via a couple of cables, it would be
possible to retrofit it to existing Mazda2 EVs.
Mazda is well aware that the rotary engine celebrates the 50th
anniversary of its introduction of the technology under the Japanese
car-maker’s bonnets.
Mr Suzuki admits the rotary range extender is still years away from
production, even if it ticks all the boxes in terms of being fit for
purpose.
End quote.
I edited out some of the BS.
The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
You Tube
http://tinyurl.com/beqqxas
Copyright 1998-2013 All world wide rights reserved.
