Engineering News 7600

DN Staff

July 24, 1995

20 Min Read
Engineering News

Electric-vehicle batteries race toward production

Seal Beach, CA--Ever since a brief 15 minutes of fame at the turn of the century, electric vehicles (EV) have been expected to return. Finally, that day is nearing.

Clean Air Initiatives in California, New York, and Massachusetts require 2% of the vehicles sold there to be zero emission by 1998. Trouble is, while the chassis, motor, electronics, and legislation may be ready, the battery is not. Even the best of present-day EV batteries offer performance akin to the "other brand" depicted in Duracell(R) commercials.

"Batteries are the single critical technology in the path of making electric vehicles viable," says Jack Guy, manager of commercialization for electric transportation at the Electric Power Research Institute (EPRI) in Palo Alto, CA. "Without a good battery, vehicles will either be too expensive, under powered, or lack range."

The absence of a perfect battery can't be blamed on lack of trying. John Cooper, an electrochemical researcher at Lawrence Livermore Laboratory, estimates that more than $5 billion has been spent on advanced-battery development over the past few decades. Worldwide, hundreds of companies and research facilities are pursuing an almost equal number of different technologies. Each hopes its is the lottery ticket with all the right numbers.

The United States Advanced Battery Consortium (USABC)--a coalition of Detroit's Big Three, the Dept. of Energy, and EPRI--supports at least a dozen different approaches. "People expect a single one to emerge victorious," says USABC's Chairman of the Technical Advisory Committee, Dave Smith. "But there is no magic bullet. If there were, we'd bet everything on it."

Experts divide EV batteries into three categories according to their near-, mid-, or long-term prospects. Near-term solutions include lead-acid and nickel-cadmium. EPRI, however, considers the expense and toxicity of NiCd to be insurmountable. More promising is Electrosource's (Austin, TX) Horizon(R) lead-acid cell. While lead also poses toxicity issues, the EPA has certified Horizon's production to be zero emission.

Horizon benefits from a proprietary method of co-extruding lead over the top of fiberglass filaments. Originally developed by Tracor, the process alleviates one of lead's greatest drawbacks--it's as heavy as lead.

With an energy density of 42 Wh/kg and power density of 200 W/kg, Horizon exceeds conventional lead-acid batteries by 40% and 100%, respectively. "We'll hit 50 Wh/kg at 1,000 (recharge) cycles within a year," says Bill Craven, Electrosource's VP of sales. Engineers have seen 60 Wh/kg at 400 cycles in the lab. "Energy and power are in equilibrium--increase one, you decrease the other," says EPRI's Guy. "The challenge is to increase both."

The company plans to grow initially by selling Horizons as conventional car starter-batteries. If successful, internal-combustion vehicles may partially fund their own demise.

The next decade. Mid-term batteries--those with the potential for prototype production this year and mass production by year 2000--include nickel-metal hydride (NiMH), sodium-sulfur, sodium nickel-chloride, and refuelable zinc-air.

With numerous patents covering NiMH, Ovonic Battery Corp. (Troy, MI) controls the future of this technology. GM agrees. In 1994, the two companies formed GM Ovonic to focus on problems specific to bringing an EV battery to market. Despite Ovonic's apparent lock on the technology, the USABC has funded Saft America (Cockysville, MD) to develop NiMH as well.

Possessing an energy-density of 80 Wh/kg, NiMH delivers twice the range of lead-acid. It's a powerful and compact battery, too, producing 220+ W/kg and 240 Wh/l. Able to handle 800 to 1,000 cycles at 80% discharge, it should last the life of the car. When recycling time does come, "they're all metal; you can melt them down or disassemble and reuse them," says Subhash Dhar, the company's president. "Even if you throw them out, the EPA defines them as benign."

The two sodium-based designs define a category of controversial "hot batteries." AEG Anglo Battery Gmbh (Ulm, Germany), builds the Zebra, a fully recyclable, sodium and nickel-chloride design that operates at about 300oC. The other contender, Silent Power's (Essen, Germany) sodium-sulfur battery, requires about 50oC more.

Boasting 85 Wh/kg, Zebras gallop well enough. But, at 80 W/kg, they lack the power of lead-acid or NiMH. Silent Power's design provides more power, but unlike the Zebra, it corrodes. "(Silent Power) provides good cycle life, but the corrosion leads to lousy calendar life," says USABC's Smith.

To quell public fears regarding highly reactive sodium, engineers at both companies have put their designs through unprecedented testing. "We've simulated 30-mph crashes into telephone poles, punctured them with spikes, poured water into them, and placed them into raging gasoline fires," says Heinz Hammerling, a business-development manager at AEG Corporation in Basking Ridge, NJ. "Nothing happens."

Engineers also say their designs' high temperatures have drawn unwarranted scrutiny. "Every battery--not just hot ones--will need insulation and a thermal-management system to account for temperature extremes," says Hammerling. The sodium batteries may even have an advantage. In winter, they can be used to store excess heat to warm passengers, without impacting range.

Most unorthodox of the mid-term batteries may be refuelable zinc-air. Under separate development at Lawrence Livermore National Laboratory (Livermore, CA) and Electric Fuel (Jerusalem, Israel), these batteries require a physical replacement of the reactants instead of a recharge. The advantage: Refueling takes less than ten minutes, not hours. "You can drive the vehicle 24 hours a day if you want," says Livermore's Cooper.

The two approaches differ in their method of refueling. Electric Fuel extracts spent battery cassettes and sends them to a central plant for regeneration. Cooper's design simply drains and replaces a slurry of zinc pellets entrained in electrolyte. The spent fuel is reprocessed on location in a small reprocessing system.

As inexpensive as lead-acid, Livermore's battery generates 142 Wh/kg, more than three times that of the Horizon battery. In addition, the DOE has classified zinc-air as the safest advanced battery, since it consists of nothing but zinc, zinc-chloride, and air.

Both methods lend themselves to fleet operations with organized support systems. But because of the extensive infrastructure that would have to be created to use these batteries with passenger cars, the USABC has given zinc-air a thumbs down.

In the long term--sometime in the next century--experts envision some form of lithium battery. Number three on the periodic chart, it's light and very reactive. "The challenge will be controlling it in a big, high-voltage system," says Smith. Organizations working on lithium-polymer batteries include two USABC-funded teams. One combines W.R. Grace (Boca Raton, FL), Johnson Controls, and several smaller firms. The other matches 3M (St. Paul, MN) with Hydro-Quebec. Both have produced prototypes with unannounced capabilities.

The biggest challenge with each battery technology, however, isn't range or power, but price. "You talk to anybody, it's cost, cost, and cost," says Ovonic's Dhar. Nickel batteries face particular problems due to the expense of the raw material. By contrast, zinc and sodium are much less costly. Lead is both inexpensive and the beneficiary of a well-established infrastructure. Lithium, derived from sea water, may ultimately prove the cheapest of all.

Even so, tomorrow's "super-batteries" may find today's near- and mid-term designs to be moving targets that won't die easily. "We see lead-acid as a big competitor," says Dhar. "They have about a 190-year head start."

What this means to you

  • Advanced batteries are starting to make EVs viable

  • The "ultimate" battery hasn't yet been found

  • Cost is the most critical factor

--Mark A. Gottschalk, Western Technical Editor

British aircraft gets a nose job

Isle of Wight, England--Pilatus Britten-Norman (PBN), a manufacturer of lightweight, twin-engine, civil and military aircraft, faced the challenge of standardizing as much tooling as possible when redesigning its Defender airplane for improved operational capability. As a result, the company reduced the number of parts needed to achieve customization.

PBN needed to increase the volume of the Defender's (now called Defender 4000) nose-cone assembly to accommodate more avionics equipment. It also sought to increase the aircraft's payload, reinforce the wing structure, and double fuel capacity.

Crucial to the redesign: making the new nose-cone shape fit the contour of the fuselage while accommodating the existing nose-wheel mounting, keeping the landing gear common with other aircraft models. PBN chose ANVIL-5000(R) from Manufacturing and Consulting Services, Inc., Scottsdale, AZ, because it was a PC-based system that "could handle the type of modeling we needed to accurately represent the aircraft's double curvature external surfaces," according to Bob LeGoff, CAD Supervisor at PBN.

To produce tooling for the 3-D GRP molds, designers used the offset-surface option from ANVIL-5000's Extended Geometry module to generate exact profiles, allowing for skin thickness.

According to Legoff, the easy transfer of geometric data from the CAD design to CAM functions was a tremendous time saver and productivity enhancer. "We've drawn some uniquely large assemblies in ANVIL-5000, then extracted the detailed components from those assemblies and sent them on to be produced on our NC machines," he explains. "We didn't have to remake any of the parts, because they had all come from a common ANVIL-5000 CAD model."

Elastomer stretches hoodseal's edge

Holyoke, MA --Advanced Elastomer Systems (AES), L.P. recently joined forces with Mitsubishi Motor Co. to supply a water-foamed grade of Santoprene(R) thermoplastic rubber for the hoodseal of the Pajero Mini, a recreational vehicle introduced in Japan late last year. It marked the first successful use of a thermoplastic elastomer (TPE) hoodseal, according to AES officials.

Traditionally, hoodseals consist of EPDM (ethylene-polypropylene-diene terpolymer) rubber. However, such vulcanized materials cannot be recycled. Santoprene is said to retain at least 80% of its material properties after recycling. Moreover, because the TPE is foamed with water, its manufacture produces a minimal environmental impact.

The material also offers the advantage that it can be molded or extruded using conventional thermoplastic processing equipment. This is much faster than vulcanizing and more efficient, says Mark Wright, director of AES' North America automotive sales. The processing scrap can be reground and reprocessed, he adds.

In addition, parts made from the TPE usually weigh less than comparable parts made from vulcanized materials. For example, the Pajero Mini hoodseal added only 113g to the vehicle's weight, providing an estimated weight saving of 16% over the EPDM counterpart. And, tests have shown that seals made from the water-foamed TPE have equal heat-resistance and equal or better compression set than those made from EPDM.

"AES will accelerate its introduction of water-foamed Santoprene rubber to the global automotive market due to the new grade's success in Japan," says Wright. "We anticipate it will become one of our top-selling products, particularly in North America." Other targeted applications: doorseals and trunkseals.

Geo Metro gains cylinder

Newton, MA--I've spent two weeks tooling around in the 1995 Geo Metro sedan, and I'm impressed. I had expected some under-powered box of a car, but I got a surprisingly spacious, peppy, fun-to-drive set of wheels.

Propelling the sedan is a new 1.3-liter, four-cylinder SOHC engine--the first for a Metro, which usually sports only three cylinders. The electronically fuel-injected engine supplies 70 hp at 5,500 rpm and 74 foot-pounds of torque at 3,000 rpm. It delivers 40% more horsepower than the discontinued hatchback's standard engine, say company officials. Geo estimates the sedan's mileage at 39 mpg city and 43 mpg highway.

Geo engineers also increased the car's overall size, interior space, and trunk; made daytime running lamps standard; and stiffened the body by adding a rigid cross-car beam under the instrument panel. At five feet four inches, I was comfortable in the driver's seat, but so was my dad, who tops six feet wearing a hat.

Shifting the 5-speed manual transmission was easy. I drove the Geo at up to 70 mph on the highway without feeling I was pushing the car to its limits. The car took corners well and the steering was fine, although the suspension was a little rough. Safety features include driver and front passenger-side air bags, rear-door child security locks, and optional antilock brakes. All in all, a great deal--and a lot of fun--for $9,795.

--Julie Anne Schofield, Associate Editor

Copier redesign focuses on disabled users

Rochester, NY--Using everyday products can be a major challenge for someone with a disability, and office copiers are no exception. To address the problem, a special engineering team at Eastman Kodak Co. set out to design copier features that would increase accessibility for persons with disabilities.

"There is a mismatch between what a user can do and what a product expects a user to be able to do," says Douglas Beaudet, director of the ACCESS research program at Kodak's Design Resource Center. The engineering team set out to find the "universal design" that would serve the greatest number of people. One result: A reconfigured version of the 1575 copier-duplicators.

The model 1575 uses digital technology and operates at 70 images per minute. To assist people who use wheelchairs, the 1575's marking engine can be separated from the unit that contains the feeder control panel and scanner. This unit is placed on a separate table at a convenient level for both standing and seated users.

Other modifications were made to allow greater ease-of-use for persons with limited movement. For example, the "clamshell" design of the paper transport system enables easy access to the paper path. Additionally, the access lid can be lifted using only one hand. Following that idea, a latch was fitted to the finisher access door so retrieving paper from that area is also a one-handed operation.

Low-g accelerometer sports high resolution

Norwood, MA--Following up its success with the ADXL50 silicon micromachined 50g accelerometer--which General Motors uses for airbag deployment in some 1995 cars--Analog Devices has introduced a plus or minus g version with 0.005g resolution. Applications for the ADXL05 include virtual-reality headsets, seismic instruments, automotive antilock braking systems and suspension control, and embedded shipping recorders.

With a new technology like MEMS (MicroElectroMechanical Systems), sometimes there's an acceptance and education problem with new products,' says Elizabeth Schumann, a market analyst with SEMI Corp., Mountain View, CA. She credits the ADXL50 as starting th education process and predicts that the new part will give the market a boost.

The ADXL05 contains all the signal-processing blocks of a complete acceleration system. It combines a micromachined sensor, modulator, demodulation, voltage reference, signal conditioning, amplification, and on-command self-test circuitry on one polysilicon die.

An internal buffer lets users set the device's sensitivity and zero output to accommodate different applications. Adding external capacitors provides one or two poles of filtering. No additional components are needed to interface the device to most analog-to-digital converters and microcontrollers, company officials say.

The accelerometer comes in a germetic 10-pin TO- 1000 metal can. Versions are available for the commercial, industrial, automotive, and military temperature ranges. Production volumes are available now for $9.55 each in 10,000-piece quantities.

Foams help protect minivan occupants

Detroit, MI--Knee bolsters made from an energy-absorbing foam are helping one automaker's best selling vehicle meet federal front-impact requirements.

The vehicle, Chrysler's Plymouth Voyager/Dodge Caravan minivan, provides both driver- and passenger-side airbags for protection. But an airbag system is only one component in the passive-safety puzzle, says the car manufacturer.

In order to meet the government's MVSS-208 standard for vehicles with passive restraint systems, Chrysler had to provide protection for areas that an airbag may not reach. Knee bolsters were designed to reduce damage to the legs, especially the femur, in the event of a frontal collision.

"Due to the unique crash pulse of the minivan," says Chrysler Product Engineer Jim Stephens, "a material was needed with high energy-absorbing capabilities." The material of choice was Bayfill EA-35 foam from Bayer (formerly Miles).

"Right off the shelf, the Bayfill foam worked better than anything else we tested," he states.

Foam panels in the knee bolsters are molded by Tennessee-based Foamex and incorporated into the instrument panel by Aeroquip/Trinova.

According to Eldon Hall, plant manager for Molded Products at Foamex, the Bay-fill EA foam can be molded into complex shapes or molded in place.

"As side-, front-, and head-impact regulations are implemented, we expect automakers will be using more and more energy-absorbing foams," notes Hall. Possible applications include polyurethane foam liners on A, B, and C pillars and panels of foam built into doors.

2.5-inch disk drives break 1-Gbyte barrier

Newton, MA--A disk drive can never be "too thin or too rich"--in storage, that is, according to Integral Peripherals. The drive maker, which pioneered the 1.8-inch PCMCIA disk drive, is now applying its technology to thin, 2.5-inch drives for high-end notebook computers. Int'gral's 12.7-mm-thick Platinum/1010 stores 1 Gbyte of data, joining a new drive from Toshiba in the 2.5-inch, over-1-Gbyte category. Toshiba's drive, the 1.35-Gbyte MK-2720F is thicker, however, measuring 19 mm. Both companies also make 2.5-inch drives in other capacities.

Ruggedness is a key feature of the new disk drives, with both Int'gral and Toshiba claiming 100g operating shock tolerance. Integral's drives incorporate dynamic head loading, parking the heads safely off the disk media when the drive isn't operating and thus reducing the possibility of "head slap." Also, because the heads don't park on the media, there's no concern about overcoming the start-up sticking friction, or "stiction," that occurs between heads and ultrasmooth media. As a result, Int'gral's drives can use untextured media, allowing the disk heads to fly close to the media and thus increase storage density.

The drives have spin rates of 4,200 rpm. Integral's drives have a Fast ATA-2 interface; Toshiba's drives come with either a Fast ATA or a SCSI-2 interface. Integral's drives have a media-transfer rate of 8 Mbytes/sec and an interface-transfer rate as high as 16 Mbytes/sec. Toshiba quotes data-transfer rates from 6 to 16.6 Mbytes/sec, depending on interface and mode. Average seek times are 12 msec for Int'gral and 13 msec for Toshiba. Integral's 1-Gbyte drive costs $795 in sample quantities; Toshiba's 1.35-Gbyte drive goes for $1500.

MPEG decoders go single-chip

Newton, MA--After seeming to languish, the MPEG-1 video-compression standard is now seeing a flurry of activity among IC developers. At least three single-chip MPEG-1 decoders have recently appeared on the market. Target applications: PC video, set-top boxes, and video conferencing.

SGS-Thomson's STi3430, the first such product to appear, performs both audio and video decoding for pictures as large as 352x288 pixels. It separates audio from video before decoding, and can further separate multiple audio and video streams. It can accept quadruple-speed serial CD-ROM data and 16-bit parallel data and performs real-time error correction. SGS-Thomson also introduced the STi3520 MPEG-.50 decoder, which handles images to 720x480 pixels, at 60 Hz for set-top boxes.

C-Cube Microsystems also offers a single-chip MPEG-1 decoder--the CL480PC. This $31 device targets the PC add-in-card market and provides a direct interface to graphics chips and CD-ROM. The device needs only a 4-Mbit DRAM to combine with the graphics chip into a video-playback unit. C-Cube and Auravision Corp jointly developed a $3500 reference design, which includes MPEG playback, video capture, and TV tuner.

Most recently, AT&T released its third-generation AVP-III audio/video processor chip for video-conferencing applications. The $78 device handles MPEG-1 audio and video encoding and decoding for 352x240-pixel images, and supports the H.320 and H.324 video-compression standards for use over digital and analog telephone lines, respectively.

Swiss consortium supports superconductor transformer design

Zurich, Switzerland--The world's first transformer to use high-temperature superconductors (HTS) will be designed and built by ABB with technology and components from American Superconductor Corp., Westborough, MA.

The team will design, manufacture, and test a 630-kVA transformer as the first step toward developing larger, commercially viable transformers. The design will use liquid nitrogen as both a coolant and a dielectric fluid. Transformers that use HTS coils instead of copper coils should be smaller and have lower energy losses.

"HTS technology has advanced to where we expect it to become cost-competitive with conventional power transformer technology by the end of the decade," says Dr. Anton Demarmels, project manager for ABB. "This prototype will allow us to quantify the benefits and begin proving the reliability of the technology."

Award sponsors help highlight engineering achievements

Newton, MA--Leading OEM suppliers are once again showing their strong commitment to the Design News Engineering Awards.

The Torrington Co. continues to back the Engineer of the Year Award for $20,000, for a ninth year. The award honors a distinguished engineer chosen by Design News readers. The reader's choice for 1995, Jerome Lemelson, an independent inventor and design engineer, holds more than 500 patents, including critical patents in machine vision and robotics.

"Design News and its readership are helping to lead the way in the reemergence of science and engineering throughout America," says T.J. Rosinski, marketing communications manager, The Torrington Co. "Our critical institutions--the university system, the scientific community, and the business sector--all understand the importance of having to compete technologically as we approach the 21st century."

For the sixth consecutive year, NTN Bearing Corp., Des Plaines, IL, is sponsoring a $15,000 grant that goes to a college specified by the winner of the Design News Special Achievement Award. The magazine's editors choose the recipient based on outstanding lifetime achievement in the engineering field. The 1995 recipient, Lester T. Davis, supplied the technical vision that helped Cray Research dominate the supercomputer industry.

Supporting this award program helps everyone to see the design engineer as a role model for future generations, says William C. Hayes, president of NTN Bearing Corp. and a trustee of the Engineering Education Foundation. "It is our hope that other companies for whom the talented engineer is essential will join us and contribute to this foundation."

The Engineering Quality Award, a third major award, is being endorsed for the seventh year by Schneeberger, Inc., a producer of precision bearings based in Bedford, MA. This past year's winner, Amar Bose, Bose Corp., revolutionized audio technology. Schneeberger raised their 1996 contribution from $12,000 to a $15,000 grant for the engineering school of the Quality winner's choice.

"We trust that the increasing awareness resulting from this joint effort by media and industry will motivate and inspire young people to pursue careers in this exciting profession," says Andy Fischer, Executive vice president & managing director. "It is an honor for Schneeberger, Inc. to be part of this great program."

For the eighth straight year, Computervision will provide three $5,000 prizes to the top award winners of the Excellence In Design Contest, which draws entries from engineers from all over the U.S. "Programs such as this, which work to further develop the United States' strengths in science and math, are more critical than ever as the struggle for dominance in these disciplines continues," says Attilio Rimoldi, vice president of research and develoment for Computervision Corp.

The second place awards in the Excellence contest, now in its 16th year, come courtesy of NMB Technologies Inc. The firm sponsors five $2,500 awards to engineer contestants.

"In maintaining the high caliber of work as demonstrated by the engineering team at NMB, we feel a strong commitment to return our thanks to the engineering community by providing awards for those individuals who have exhibited excellence and ingenuity in the field of design engineering," says Myron Jones, president of NMB Technologies Inc.

Edmund Scientific Co., New York, NY, also supports the Excellence in Design program with a donation of five Astroscan telescopes.

Many of these awards will be presented at the annual Design News Engineering Awards banquet in Chicago on March 19, 1996. The event is held in conjunction with the National Design Engineering Show.

"Once again, Design News is deeply indebted to our award sponsors," says Publisher Steve Thompson. "Their generosity enables us to honor some of engineering's top talents."

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