HONDA electric/gas hybrid

New Milestones Along the Alternative Highway
Several designs continue quest for cleaner motive power

-- Richard Mandel

Our love affair with our vehicles is no longer a matter of individual choice. It's become a cultural tradition, rather like the litany "finish college, find a partner, settle down" has been for many people. Not owning some sort of motorized transportation today elicits suspicion or, at the least, pity. We depend on them -- not just to go places, but as tangible evidence of status, which is why matter transport devices, like those popularized on Star Trek, will never catch on. Besides the need to dispense with several basic laws of physics, they're just not sexy.

While the Great Depression did its part to eliminate many manufacturers, it also saw the end of companies that produced electric- or steam-powered vehicles. They were complex and expensive to produce, so the companies making them didn't survive when money became tight. Despite the return to large internal-combustion engines in behemoths like the Ford Excursion and the V-10s in the Dodge Ram line, there are many consumers who wistfully wonder why there isn't room again for the Baker Electric and the Stanley Steamer.

Honda's "helper" motor design.

The good news is, the design work of the last 10-20 years in vehicle design has shown sufficient progress to establish production lines. LNG, propane and electric vehicles are available in fleet service vehicles, and the General Motors EV-1, with whatever imperfections the automotive world finds in it, has bravely led the non-commercial batteried pack. Here's a progress report on several other technologies now under way. 

A Fresh "Insight"

Honda's newest car results from a concept that has been explored since the gas-crisis days of the 1970s -- producing a hybrid vehicle that combines a small gasoline engine with an electric motor "assist." Their Insight, the first production vehicle of its kind to be sold in the US, is not only the marriage of the two motive methods, but brings in many innovative engineering concepts that have developed in the last five years.

Dual-powered vehicles were originally supposed to share propulsion duties -- the gas engine would handle acceleration and hills, while the electric motor would take over during the steady-state cruise mode. In the IMA (Integrated Motor Assist) system, Honda's engineers instead elected to use the electric motor as an assist, adding an on-demand 25 lb-ft to the engine's output. This idea evolved into a permanent magnet motor only 2.3-in. thick, installed between the engine and the transmission (reminiscent of the magneto in the Ford Model T), eliminating a separate motor-and-drive assembly. This high-efficiency unit can output 10 kilowatts at 3000 rpm, generating current for the system's battery pack during deceleration and braking, thus eliminating the need to stop and recharge the car on long trips. The IMA system's compact 144 VDC battery is comprised of 120 nickel-metal hydride cells, with an output of 6.5 amp-hours.

The IMA motor is the primary starter for the gas engine (a separate 12 VDC starter motor and battery are on hand for back-up). The electric motor's starter abilities are also applied in another feature -- when the driver puts the car in Neutral and takes their foot off the clutch, as at a traffic light, the gasoline engine temporarily shuts off. When the clutch pedal is depressed and the transmission is re-engaged, the IMA motor immediately restarts the engine, reducing fuel use and exhaust emissions. The feature is bypassed if the air conditioning is on or the IMA system battery is low. Additionally, the motor serves as a damper against engine-idle vibration, through the application of reverse torque to the crankshaft.

The gasoline engine itself is the culmination of many engineering developments. The 1.0 liter, 12 valve, 3 cylinder unit uses a plastic intake manifold, valve cover and water pump pulley, as well as a magnesium-alloy oil pan, for weight savings. The exhaust manifold is integrated into the cylinder head casting, a further reduction of weight and components. The combination of friction-reduction technologies with Honda's Variable Valve Timing and Lift Electronic Control (VTEC) system, lean-burn fuel injection and the assistance of the electric motor, create a power system with a total torque of 91 lb-ft at 2000 rpm, at an estimated fuel mileage of 70 mpg.

Under the Insight hood

But high mileage is not merely a function of powertrain alone. The Honda body and chassis engineers borrowed from their experience in manufacturing the NSX sports car, and created the Insight's body from aluminum, using stamped sheets, extrusions and die-castings. The independent front suspension has forged aluminum alloy steering knuckles and lower suspension arms, and cast aluminum wheels. The rear suspension does not use the lightweight metal, but instead uses a curved, flattened beam (called a twist beam) that also functions as the stabilizer bar, reducing weight by eliminating the separate component. Rear brake drums are made of aluminum, and there are also aluminum engine mounts, sub-frames, side-frame members, lower body sills, crossmembers and floor frame members. The fuel tank is made of plastic resin. Overall, the entire curb weight of the Insight is just 1,856 lbs. The body's shape has a drag coefficient of 0.25 which, when combined with the flat underbody, contributes to the Insight's requiring approximately 30 percent less power to maintain highway speeds than most conventional automobiles.

Power-assisted steering is abetted by an electric motor, rather than the traditional hydraulic pump, reducing the power loss on the engine and the number of failure-prone components. The steering motor has a microprocessor that senses vehicle speed and steering torque, making adjustments to steering boost accordingly.

While Insight's acceleration won't win speed records, its aluminum components expensive to repair, and the luggage space limited to several small grocery bags and a postage stamp, consumer appreciation of Honda's new car may provide incentive for other companies to build competing versions that will be as fuel-conscious or better.

Fast Charge

Nickel metal hydride batteries are swiftly replacing lead-acid cells in experimental vehicles. They are more compact, and they offer more peak power, high rate discharge, and higher energy densities than other batteries. The increased density allows for immediate power when the motor is engaged. NiMH batteries don't have a "memory" like NiCad units, and they offer greater range than lead-acid. Additionally, they offer better performance in low temperatures, and are generally better for the environment.

DWRA's "White Lightning"

In October 1999, the electric streamliner "White Lightning," built by Dempsey's World Record Associates, reached a top speed of 254 mph, shattering the previous record for an electric vehicle. Power was provided by an 800 lb. NiMH battery unit built by Moltech Power Systems, a spin-off from the Energizer Corporation. The Moltech assembly contained over 6,000 sub-C size cells, producing 400 volts at the start of the run. As the vehicle sped down the measured mile, the battery settled into producing 800 amps at 250 volts to drive two 200 hp AC induction motors at 10,000 rpm, which translates to 200,000 watts of power. The 21 ft. long vehicle weighed 2,450 lbs. and had a drag coefficient of 0.131. Cargo space was not reported, but is likely much less than that of the Honda Insight.

Haulers and Movers

The alternative energy systems developed for commuter vehicles have had little effect on those in the diesel industry, who have high confidence that the diesel engine is a major candidate to become the power plant of the future. Heavy trucks, urban buses, and industrial equipment are powered almost exclusively by diesel engines all over the world. In Europe, diesel-powered cars have become increasingly popular.

While diesel engines are presently the most efficient power plant among all known types of internal combustion engines, further progress in diesel emission control is needed. Diesel particulates and nitrogen oxides, the two most troublesome components of diesel exhaust emissions, have a dramatic, damaging impact on the environment and on our health. The new 2004 emission standards in the U.S. as well as the tightening regulations in Europe and East Asia reflect the growing concern with these emissions.

As previously reported in Designfax (Feb. 99, Technology Spotlight), Westport Innovations, Inc., Vancouver, B.C., Canada, has developed a high pressure, direct injection nozzle for diesel engines that combines natural gas with a small amount of diesel fuel. Directly injected into the combustion chamber at 3,000 psi near the end of the compression stroke, the reconfigured engines tested out as having the same power and torque output as a standard diesel, but with a 25 percent reduction in CO₂ emissions, and improvements in nitrogen oxide and particulate matter emissions.

In November, Westport announced a project in conjunction with Cummins Engine Company, Inc., Columbus, IN, to adapt three heavy-duty trucks to liquefied natural gas operation. According to Tom Kieffer, Cummins executive director of automotive marketing, "Cummins engines are the cleanest in the market today, and we plan to maintain our environmental leadership." Westport will retain the first prototype in Vancouver for demonstration purposes, and deliver the other two to fleet operators for commercial hauling before the end of this year.

For more information:

Circle 410 - American Honda Motor Company

Circle 411 - Moltech Power Systems

Circle 412 - Westport Innovations, Inc.