A New Twist on Turbo

Electronics integration changes turbocharger technology.


Integrating electronic systems in every new truck is something that is happening more frequently, so it shouldn't be a complete surprise that turbocharger technology is advancing in this direction as well. To many medium-duty fleet maintenance managers, it is also new. According to Zack Ellison, director of customer technical support and industrial OEM support with Cummins, most technicians and managers have not encountered this kind of technology before.

"It's sort of a new world for maintenance people as far as turbos are concerned because they have never in the past had to worry about electronic fault codes for turbochargers, but today they do," Ellison says.

He adds that the electronically actuated turbocharger technology is on all of their medium-duty 2007 engines. It has what he calls a 'coolant-cooled bearing housing', with the center section of the turbocharger essentially cooled by engine coolant.

Ellison says this helps to reduce the turbocharger bearing temperatures, which is good for the life of the turbocharger.

"Maintenance managers need to understand that if you do a good job changing oil and using good engine oil filters, that actually takes care of the turbocharger," Ellison says. He also adds that part of the maintenance equation includes using quality multi-viscosity oil such as 15W-40 and a quality filter, just as it is also very important for technicians to follow maintenance manual procedures from the manufacturer.

Ellison explains that the turbocharger is actually the first component receiving oil filtered by the oil filter. "An oil line runs directly to the bearing," he says, "so there isn't any lag at start up and it feeds good oil to the bearings during shutdown."

Because the turbocharger is of an electronically actuated variable geometry (VG) variety, there will inevitably be the need for troubleshooting because of the electronic fault codes related to the operation and the actuation of the unit.

Cummins provides 'troubleshooting trees' or detailed information for technicians to follow in order to pinpoint problems based on fault codes.

"In some cases, they could get a fault code that could be related to the turbocharger operation, and go to the troubleshooting trees that give them step-by-step instructions to find where the problem is with that turbocharger," says Ellison.

'DIFFERENT' CAN BE GOOD

"It's a little bit different, but the benefits of the electronic controlled variable geometry turbocharger are pretty spectacular," he says.

Another aspect to this technology is better driveability, according to Ellison. That is when the turbocharger "spools up" or gets up to speed very quickly to provide engine boost levels almost as quickly as the throttle pedal is depressed.

The turbocharger also has the capability to perform as an exhaust brake to give the engine the maximum exhaust back pressure to help slow down the vehicle. Ellison says that this capability is built in to every electronically controlled VG turbocharger. Cummins no longer allows the addition of external exhaust brakes, which is a change from the past. It is also a major cost-savings, and saves the operator installation fees that could run anywhere from $700 to $1000. All of this is achieved with electronic technology, without affecting engine durability or reliability.

TROUBLE-FREE EFFICIENCY

"The turbocharger is actually one of the most important components for improving engine efficiency," Ellison says. He adds that because of engine efficiency, the amount of energy recovered from the exhaust via the turbocharger is also related to fuel economy.

"It's important when a turbocharger spools up quickly and maintains accurate boost levels throughout the engine RPM range. All of that goes to improve fuel economy," he says.

"Combined with the electronically controlled VG turbocharger and other improvements we made for '07 in the mid-range product line, it has enabled us to increase fuel economy by a few percentage points," Ellison continues.

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