Hybrid Strategy: Divide and Conquer

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BOTH Honda and Toyota are far more committed to the hybrid car than to the battery electric vehicle, a fact that Toyota made clear this month when it scaled back its Scion iQ electric car project. And Honda is so enthusiastic about hybrids that, as its chief executive, Takanobu Ito, outlined in a recent speech, it will have three separate systems with up to three electric motors.

Honda is broadening its hybrid strategy. It is improving its existing single-motor system to make it simpler and less expensive. It is adding a new two-motor system to challenge the Chevrolet Volt and add plug-in hybrid capability to its arsenal. And it is developing a three-motor system aimed at high performance and improved handling.

Does Honda need three hybrid systems? It makes sense if the company can build exciting cars to take advantage of the engineering. A range of solutions matches costs to market realities: simpler systems at the lower end and more complex designs upmarket, where higher prices can absorb the added costs.

The venerable Integrated Motor Assist system, as seen in various guises on cars like the Insight and Civic Hybrid, relies mainly on the gasoline engine, drawing on the electric motor for extra power during acceleration. When the car slows, the slim electric motor, sandwiched between the gas engine and the transmission, turns into a generator to send electricity to the battery pack.

Honda has been using variations of this formula since introducing the original Insight of 1999 -- the first modern hybrid car offered in the United States. Though Honda was a hybrid pioneer, it has been, compared with Toyota, an also-ran in sales.

It could become more competitive. A spokesman, Paul Seredynski, said Honda would soon announce a breakthrough in the form of a more efficient Integrated Motor Assist system.

"The goal is for it to be very simple, very inexpensive and very lightweight," he said. Mr. Ito said the improvements would include better performance from the motor output and battery, as well as a new transmission.

For the most part, the integrated-motor hybrids that Honda offers today cannot be driven in all-electric mode, a feature that buyers seem to like. But the company will address that issue with the 2014 Accord Plug-In Hybrid, which incorporates Honda's new two-motor hybrid system. At the heart of this layout is a 124-kilowatt electric motor coupled to a 6.7-kilowatt-hour lithium-ion battery pack, which does the main work of driving the wheels.

This so-called traction motor is large by hybrid standards, and it can carry the plug-in Accord at highway speeds without assistance from the 2-liter 4-cylinder engine, though the engine will start up in some situations. The plug-in Accord, which will be on the market in early 2013, has up to 15 miles of all-electric range.

A second electric motor acts as a generator, gathering energy from the gas engine to replenish the batteries or provide additional electric power when needed. In addition, under certain conditions at highway speeds, a clutch engages the Atkinson-cycle gas engine to directly run the car.

The Accord also offers a console-mounted HV (for "hybrid vehicle") button that returns the car to standard hybrid operation, conserving the remaining electric range for when it's most effective (in stop-and-go traffic, for instance). That setting maintains the battery level where it was before the button was pushed. Hold the button longer and you enter HV Charge mode, which fully recharges the battery.

Less is known about the three-motor hybrid system that will be in the 2014 Acura RLX Sport-Hybrid SH-AWD and, later, revised for a midengine design, in the new Acura NSX sports car.

According to Mr. Seredynski, the all-wheel-drive RLX hybrid, unveiled as a design study at the New York auto show in April, uses an electric motor embedded in the 7-speed dual-clutch automated manual transmission at the front axle; the gas engine is a 3.5-liter V-6. At the rear, a transaxle houses electric motors for each wheel. Under hard acceleration, all three electric motors engage, turning the front-drive car into all-wheel drive.

The RLX will be capable of all-electric driving around town. At higher speeds, the gas engine will engage; power will also flow to the rear motors for extra acceleration. The pièce de résistance may be Honda's bilateral torque-adjustable control system, which can send power individually to the rear wheels to help with cornering. It can also turn a rear motor into a generator to provide drag at one wheel.

A close-to-production version of the RLX will be shown in Los Angeles in December and go on sale late next year. The NSX comes later, probably in 2015.

autonews

This article originally appeared in The New York Times.


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