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Automotive Industry

No starter. No alternator. No problem

Automotive Design & Production, Oct, 2003 by Christopher A. Sawyer

Oh No, Not Another One!

Yeah, it's a stop-start system, but this one is designed for 12 volts, not 42, and has a high continuous output. Visteon calls it "SpeedStart 12" because it's designed for a 12-volt charging system, and can restart a hot (or cold) engine in 400 milliseconds or less. That's less time than it takes, claims Visteon, to move your foot from the brake to the accelerator. Since Speed-Start 12 produces 65 Nm of torque at the shaft-or 170 to 200 Nm at the crank with pulley ratios of 2.4:1 to 3.0:I-a 2.0-liter inline four is restarted at a speedy 550 rpm.

What Do I Have To lear Up To Use It?

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According to Mike Dowsett, Visteon's manager of Advanced Powertrain Systems, "The system can be implemented on an existing powertrain very, very easily, and eliminates the need for the starter motor, ring gear, and alternator." The biggest change underhood will be tapping into the cooling circuit to keep the three-phase starter-alternator cool in harsh environments. Since SpeedStart 12 replaces the conventional starting system, it's best suited to engines that are 3.0-liters or less.

So There Are Some Caveats.

Whether or not it will work with more than six cylinders and larger displacements depends on an engine's internal friction and compression ratio. Because it eliminates the starter, Visteon needed a rule-of-thumb example of the upper limit, and three liters and six cylinders was it. Plus, Visteon worked with its suppliers to create a special material for the otherwise standard six-fib V-belt. Another addition is a tensioning damper that must work whether the unit is cranking the engine or generating power. Finally, Visteon replaced the standard lead-acid battery with a ball-regulated lead acid unit with low internal resistance that can stand deep discharging and rapid recharging. Dowsett says the net cost to the OEM-depending upon volume and application, of course-is between $150 and $180 for the system.

So What Do I Get In Return?

Fuel economy and C[O.sub.2] improvements of more than 5% in the real world (more in diesel vehicles says Dowsett), near-silent starting, and the elimination of emissions when the vehicle is stationary are the items getting the most emphasis from Visteon. However, the 80% efficient on average) SpeedStart 12 produces a continuous 2.7 kw (burst of up to 3.0 kw are possible for 30 seconds at a time), and delivers 2 kw at idle. That's much better than the I know most alternators (56% efficient on average) can produce at idle, and is enough to let some of the more powerful by-wire systems migrate to 12 volt vehicles. "Our Challenge from the outset," says Dowsett, "was to bridge the gap to 42-volt systems, but I think this may have pushed the move to that standard out by a few years."

Automotive Industry

No starter. No alternator. No problem

Automotive Design & Production, Oct, 2003 by Christopher A. Sawyer

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