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From ROAD & TRACK, January 1998 (US car-magazine)
IN THE EARLY days of emissions controls, we ran a droll cartoonshowing a clean air car sucking in smog and emitting crystal-clear exhaust.
Well, guess what? Honda's ZLEV technology, announced at the 1997 Tokyo Motor Show, is very much along these lines. The letters stand for Zero-Level Emissions Vehicle; and, to avoid possible confusion  in  our clean-air alphabet soup, here's Honda's definition: A ZLEV's emissions are the same as those emitted by a state-of-the-art electric utility when the latter is producing the power to propel an electric vehicle the same distance.
The relevant pollutants  are  carbon monoxide (CO), the nitrogen oxides (collectively, NOx) and the non-methane organic gases (NMOG). These last, by the way, are the hydrocarbons (collectively, HC) that actually contribute to smog.
To put ZLEV numbers in perspective, they're typically less than 0.10 of Ultra Low Emissions Vehicle standards, hitherto the lowest promulgated for internal combustion engines. What's more, this is the first time I've seen a quantification of emissions from "Zero" Emissions Vehicles, or ZEVs, when the remote emissions of the electric utility are factored in -- as, of course, they should be.
That is, as I noted a while back, ZEVs would be more logically called REVs, Remote Emissions Vehicles. On the other hand, our clean-air alphabet soup recipe is complex enough as it is, so I rather doubt my suggestion will catch on.
Honda dernonstrated this new technology in a most astounding manner. I got to drive one of the ZLEV cars at its Tochigi, Japan, R&D facility. Its operaüon was utterly transparent, with exemplary driveability and good power. In particular, even on light throttle, 1 sensed no lean-burn hunting whatsoever. A perfectly normal Honda.
Then the car was brought into the emissions lab, hooked to the analyzer and run through the final portion of the U.S. Federal Test Procedure.
Its NMOG for instance, were around 0.5 parts per million; sure enough, equivalent to 0.10 ULEV level. Next, engineers removed the sensor from the ZLEV's tailpipe and exposed it to the lab's ambient air. The NMOG level in the lab measured around  1.6 ppm; quite clean, really; about half of a typical Los Angeles ambient reading -- but also more than three tinies dirtier than the ZLEV's exhaust.
Literally, ZLEV operation imitates that R&T cartoon in cleansing the air.
ZLEV technology is an iteration of Honda's existing ULEV practice. A 32-bit  Electronic Control Unit gives extremely  precise control of the air/fuel ratio. A series of catalytic converters operate at especially high efficiency. And Honda's VTEC variable valve timing hardware plays an important role as well.
lt's a three-stage strategy. First, in cold start, VTEC induces a marked swirl of the  incoming charge to reduce unburned HC. Any HC that is produced gets absorbed downstream on one layer of an innovative dual-bed catalyst. Second, during warmup, the converter residing immediately next to the exhaust manifold quickly reaches its operating temperature. In the meantime, farther downstream, the HC is "de-absorbed" and treated as the threeway portion of the dual-bed catalyst heats up. The gases then travel into an Electrically Heated Catalyst directly downstream of the dual-layer device. The EHC's operation is optimized for highly efficient treatment of this remaining HC.
Third, in normal Operation, the advanced 32-bit Electronic Control Unit offers two benefits in engine management. Emissions are reduced at the source through a more stable combustion process. And an extremely precise control of the air/fuel ratio provides "feed gases" that keep the converters operating in their most efficient range.
It's noteworthy that Honda's ZLEV technology is essentially evolutionary, not particularly radica1. Also, this is an ordinary car burning gasoline, not some exotic alternate fuel.
About two years ago, I drove a prototype of Honda's ULEV Accord. It's now available in selected U.S. markets. Expect a similar lead time for Honda's ZLEV

IMA, an electronic turbo

THE SECOND MAJOR innovation shown by Honda at Tokyo was its IMA, Integrated Motor Assist. This hybrid powerplant combines a 1.0 litre 3-cylinder VTEC Gasoline Direct Injection engine, an electric motor/generator linked to in ultracapacitor, and a continuously variable drive.
It's a parallel hybrid, with each power source contributing to propulsion on demand; this, as opposed to a series  hybrid, where one power source feeds the other, which, in turn, drives the wheels.
In fact, think of the IMA as a small displacement gasoline engine augmented by electric supercharging.
An ultracapacitor is a largish condenser, an electrical device storing its charge between internal plates. The IMA´s ultracapacitor array is about the volume of a Suitcase -- decidedly smaller and lighter than any EV battery pack. On the other hand, it's purely for intermittent use: IMA's fully charged gizmo offers perhaps 13 seconds of boosted operation.
The IMA's high  efficiency comes from several interacting strategies.

Honda's integrated Motor Assist sandwiches a high torque electric motor between its  direct-injection gasoline engine and CVT gearbox. The result is 70 mpg in Japan city mode testing.

First, under light load, the gasoline engine and CVT operate in regimes of GDI lean-burn high efficiency. (For details of Gasoline Direct Injection, see "Technology Update: The Last Internal-Combustion Engine?" December 1997.) VTEC promotes this light-load combustion with high-swirl-inducing valve timing. Also, the small displacement of the IMA engine translates into reduced frictional and pumping losses.
Second, gradual demands for power are met essentially by the gasoline engine alone, its VTEC valve hardware changing over to optimize engine performance at higher revs.
Third, to invoke immediate power, IMA calls on the ultracapacitor. Its charge is routed to the electric motor/generator nestled between the engine and CVT. This DC brushless motor is derived from Honda EV Plus technology. Also, its controller is programmed to invoke a subtle reverse torque on the gasoline engine's output, thus reducing torque fluctuation of its configuration.
Fourth, in braking, the motor/generator operates regeneratively, charging the ultracapacitor for its next boost.
Neat, eh?
What's more, all this hybrid activity happens essentially transparently to the driver. I had an opportunity to tool around Tochigi in an IMA powered Honda Life city car and can report that an "Assist" light on the dash was the only way I could sense any transition from gasoline power to ultracapacitor boost.
Honda says the basic gasoline engine produces some 70-80 bhp, with the electric motor contributing another 50. The entire package weighs  about 110lb.  more than a conventional 1.5-liter powerplant, this latter actually yielding somewhat less performance. Also, the IMA's control strategy is designed to optimise the high rpm power of the VTEC GDI engine with the high torque available from an electric motor on demand.
An important benefit is IMA fuel efficiency (and hence its reduced CO2 production). Fuel economy is said to be better than 70 mpg on the Japanese city mode test. The IMA package is part of Honda's J-VX sports coupe exhibited at Tokyo (see Ampersand). This hybrid technology is likely to appear on the roads of Japan within two to three years and here as well in time.


At Honda, the theme was "Small is Smart." And this 2+2 JV-X concept car looks smart indeed, sort of a CRX for the next millenium. Beneath the hood of this California styled front driver is a totally new power unit, a lightweight, clean-burning, direct-injected, VTEC-aided 1.0-litre inline-3 that has an ultrathin motor/generator mounted between it and the continuously variable transmission. This motor/generator serves as an extra power source for the JV-X when it's accelerating. Honda says that, thanks to IMA (the Integrated Motor Assist system), the JV-X accelerates like it has a 1.5-litre engine rather than a 1.0.
IMA also helps make the JV-X's fuel economy excellent, a heady 70 mpg. Under braking and deceleration, the motor/generator transforms kinetic energy into electric power. Of note, the electricity is stored in (and quickly released from) huge capacitors, which weigh 66 lb.
Power capacitors (Ultracapacitors) from:

Maxwell Technologies
Energy Products
4949 Greencraig Lane
San Diego, CA 92123
Tel 619-496-4123
Fax 619-576-7672