With help from a Bodine electric motor, the Sunsetters team from North Dakota State University placed first in a 2,300-mile solar vehicle race.

North Dakota may not be the sunniest place on the map, but that didn’t stop the Sunsetters, a solar race team from North Dakota State University, from placing first in the Stock class of the American Solar Challenge in July. The 10-day, 2,300- mile race — the world’s longest solar vehicle race — took the students from Chicago to Los Angeles along Route 66. Teams participated in either the Open or Stock class of the race, which is comparable to professional and amateur, respectively.

The NDSU vehicle, Prairie Fire GT, was the only solar racer with an electric motor built by a conventional motor manufacturer, Bodine Electric Co. of Chicago. All the other teams used electric motors specifically built for solar racing, which can cost as much as $17,000 each. The Bodine Electric e-TORQ motor is a high-torque industrial servomotor typically used in packaging and converting machinery and medical equipment. The 14-in.- diameter motor produces about 10 hp with more than 90% energy efficiency. (See It’s in the gap.)

“The e-TORQ motor helped us achieve our goal of building a cost-effective car. It performed flawlessly while other teams had numerous problems with their motors,” said Keith Richtman, the Sunsetters mechanical engineering team leader and co-driver.

It’s in the gap

Features
• Zero cogging at low speeds
• High accuracy
• High torque (up to 100 lb-in. at 6,000 rpm)
• Quiet, smooth operation
• Alternative to planetary gearmotors
• High torque linearity

There’s more than one way to convert electrical current into mechanical torque. Most motors pass current through a coil, generating an electromagnetic force that acts across a radial air gap — the space between a cylindrically shaped rotor and its corresponding stator. This classic design is a reflection of Michael Faraday’s early work in electromagnetism and how he envisioned magnetic fields.

Select figure to enlarge.

Another way to produce torque is to arrange the current-carrying coils into the form of a disc. The corresponding electromagnetic force propels a discshaped rotor, acting across the space between the facing flat surfaces of the rotor and stator. Such axial-gap motors employ principles developed by H.A. Lorentz.

Although radial-gap motors are the most common, they are not the most efficient. Their magnetic and mechanical forces are in a constant state of contention, always trying, in a sense, to “reshape” the motor. By contrast, the forces that drive axial-gap motors are more optimally aligned, resulting in almost no mechanical energy loss. Energy optimization, in turn, means that axialgap motors can produce high peak torque, eliminating the need for gearheads in certain applications.

In the case of Bodine Electric Co.’s e-TORQ motors, optimization goes one step further. Instead of an iron core, e-TORQ stators consist of wire and nonferrous materials. This eliminates iron saturation common in most other motors, and allows the motor to run smoothly at extremely low speeds, even when powered by a standard drive.

Packed in Las Vegas

There was a lot more than usual to see in Las Vegas Oct. 13 to 15, as more than 800 companies parading the latest in packaging technology — and 17,000 people wanting to see them — filled the Las Vegas Convention Center for Pack Expo 2003. The exposition showcased state-of-the-art advances in packaging machinery, converting machinery, materials, packages, and containers.

In addition to the show floor, the Pack Expo Las Vegas/Food Processing Machinery Expo 2003 sponsored a conference that covered RFID technology, FDA packaging regulation initiatives under the Bioterrorism Preparedness Act, and trends in food cans, closures, meat and poultry trays, and glass packaging.

Pack Expo, a biennial event held on odd-numbered years, is sponsored and produced by the Packaging Machinery Manufacturers Institute.

Continue on page 2