Two electric motors and a plug, coming soon to an Accord near you.January 2011
BY MICHAEL AUSTIN
While in Japan for the 2011 Tokyo Motor Show, we visited Honda’s Twin Ring Motegi racing facility to see some of the company’s future products. Among them was a plug-in hybrid system, a prototype of which was installed in a current-generation Accord. While the car we drove is just a development mule, we can confidently say that a hybrid like this one will be part of the lineup when the next-generation Accord debuts for the 2013 model year.
Honda’s new plug-in system is totally different from the single-motor IMA drivetrain found in the Insight, CR-Z, and Civic hybrids. The main powertrain components are a 2.0-liter Atkinson-cycle inline-four and two electric motors—one to charge the battery pack and one to spin the wheels. The gas engine puts out 134 hp and 111 lb-ft of torque; the drive motor is good for 161 hp, and the generator is rated at 100 kW.
We first saw this system previewed at the 2010 L.A. auto show, and the specifications are largely unchanged. EV mode works up to 62 mph for 10 to 15 miles. The gasoline motor can spin the drive wheels directly, bypassing the electric motor and returning highway fuel economy closer to that of conventional cars, which typically fare better than hybrids at high speeds. How this works is the curious part. My exchange at a powertrain display stand with a Honda engineer who was barely conversant in English:
“So how does the transmission work?”
“No, no transmission.”
“Yeah, okay, so the motors make a CVT like in the Prius? How does that work here?”
“No, the motor is direct drive.”
We went back and forth in this manner for about five minutes. When I then asked how the gasoline engine works at highway speeds, he told me that there’s a single ratio with no transmission. Take this with a grain of salt, as Honda’s specification sheet says the car uses an “electric CVT.” Later follow-up didn’t provide a more clear answer, so a better explanation down the road could prove the above to be inaccurate.
Going back to the engineer’s explanation, multiple clutches allow the system to work in full-EV mode, full-gas mode, or a mix of the two. When driving the wheels, the engine is always using a tall highway ratio, and the electric motor uses a single-speed gear reduction as well. At slow vehicle speeds, the electric motor can work on its own or feed in to provide assist. Conversely, in cases where the battery’s charge is depleted, the gas engine can produce juice using the generator, which then sends power to the drive motor; in effect, this means that the engine would indirectly drive the wheels.
Our test drive of the Accord was limited to a few miles at low speeds, but the system looks very promising. You can get a decent amount of power without activating the combustion engine (we were unable to determine, and Honda isn’t willing to share, the parameters that allow for EV operation). When the engine does kick in, though, its speed isn’t relative to vehicle speed, and it drones a bit—but Honda has plenty of time to rectify that before we see such a system in production. There is a slight delay between pressing the pedal and the gas engine kicking in, a feeling that reminds us of the Chevrolet Volt.
The Honda’s all-electric range is much shorter than the Volt’s. On the upside, its 6-kWh battery is lighter than that car’s. And the charging time, at around two hours on a 120-volt source, is a lot more attractive than the 10 a Volt needs from the same outlet. Honda didn’t provide any fuel-economy targets or estimates for the system.
Toyota, Ford, and Hyundai all have hybrids in the mid-size-sedan segment, and Nissan will soon return with a new Altima hybrid. Ford’s current Fusion in particular is very nicely executed and decent to drive; the 2013 Fusion will become the first to offer a plug-in option with the Energi model. So far, though, no one has figured out a similar solution for improving highway fuel economy in a hybrid. For a company that sold the first hybrid in the U.S. market and has since been eclipsed by its competitors, it’s nice to see some innovative thinking from Honda.
Source;
http://www.caranddriver.com/reviews/honda-accord-plug-in-hybrid-prototype-drive-review