By John McHale
LITTLETON, Mass. — Engineers at Lau Technologies in Littleton, Mass., have shipped about 62,000 of their custom-designed vehicle control units (VCU) for use in U.S. Army High Mobility Multi-purpose Wheeled Vehicles (HMMWVs) during the last two years. About 40,000 of the devices are actually in fielded vehicles.
The Lau devices replaced a protective control box in the HMMWVs that measured and controlled the power in a HMMWV engine, thereby turning off the glow plugs when they overheated in cold conditions such as those during Bosnian winters, says Phil Hamilton, vice president of marketing at Lau. Glow plugs raise the temperature of the fuel and air mixture in diesel engines when the engine is not hot enough to create combustion.
The VCU uses microcircuitry to regulate the temperature and humidity of the glow plug to prevent failures and extend product life, Hamilton says. Glow plugs only last for two and a half minutes in the intense heat of starting, so the device also has a timing function to keep the device from failing during multiple starts, he continues.
"The problem is that soldiers will often turn the ignition on and off repeatedly when they try to start a HMMWV on a cold day," said Frank Hoeper, Assistant Secretary of the Army to a meeting of the Association of the United States Army Annual Meeting in 1998. "This confused the electronics on our HMMWVs and allowed the glow plugs to reach 2,000 degrees Fahrenheit when they burned out."
The Lau VCU has a failure rate of .03 percent compared to 38.5 percent for the previous box, Hamilton claims. The solid-state VCU also has redundancy built in, Hamilton says. It uses eight separate channels — one channel for each glow plug — he explains. The previous box only had one channel for all the glow plugs, so if the channel failed the whole system failed, Hamilton adds.
The only failures Lau has faced are due to grounding problems, Hamilton says. There is a ground point location on the instrument panel and a grounding strap connected to the frame; when either one fails it shoots a current through the VCU, shorting it out, he explains.
Lau engineers made software and hardware modifications on the VCU to mitigate the problem, but the grounding problem on the HMMWVs still has not been corrected, Hamilton says. Corrosion and paint near the grounding straps continue to cause failures, he adds.
The old box worked more than half the time, but the technology used to design it was from the early 1980s, Hamilton explains. So about two years ago Army officials decided they needed a more efficient control box, he adds.
"To solve this problem, our Tank Automotive and Armaments Command (TACOM) formed a team comprising [Tank-Automotive Research Development and Engineering Center] TARDEC, the Acquisition Center, the HMMWV program manager and the Integrated Material Management Center to analyze the problem," Hoeper said. "To get the solution in the field TACOM teamed with Lau Technologies. The result is a new, solid-state device based on state-of-the-art commercial technologies. The form factor is exactly the same so replacement is easy."
Despite the low failure rate, Army officials say they will put a solicitation notice out to potential vendors to rebid the contract because they want a less expensive device, Hamilton says. The Lau device currently sells at about $372 for the VCU box and harness, he adds.
Lau officials believe they knock about $100 off that price by negotiating better rates with their vendors and reducing engineering and circuitry cost, Hamilton says. The cost were high originally because the Army needed them right away to fix vehicles deployed in Bosnia — the demand was high, therefore so was the price, he explains.
For more information on the VCU and Lau Technologies contact Phil Hamilton by phone at 978-952-2024 or on the World Wide Web a http://www.lautechnologies.com.