EMP: Press Releases
More Power To The Troops
ESCANABA, MI --
BY MIKE BREZONICK - Diesel Progress, December 2009
When involved in conflict, the U.S. Armed Forces typically learn a lot about the equipment it deploys on the battlefield. A case in point would be the U.S. Army’s M915A3 military linehaul tractor. Built for the Army by Daimler Trucks North America LLC, the vehicle has been used in a range of hauling applications in the Gulf and other regions. And not surprisingly, during the course of those duties, some new requirements have come to light.
In the case of the recent wars in Iraq and Afghanistan, the lessons learned from the deployed M915A3 included a need for heavier armor protection and the availability of more electrical power to run the evermoresophisticated communications gear that has become standard in nearly all military vehicle platforms. Those lessons are being applied in the newest version, the M915A5 military linehaul tractors, 1780 of which were ordered by the Army earlier this year. The new 6x4 workhorse, which will begin deliveries in 2010, incorporates new armor (in the form of an A-kit and B-kit) as well as a higher-output Detroit Diesel Series 60 diesel engine, which has been boosted to 500 hp — a 15% increase in horsepower over the current M915A3.
Being able to accommodate the increased electrical demand was the other major challenge, but the answer proved to be an alternator design
originally developed by Engineered Machined Products (EMP) as part of an advanced cooling system for truck and bus applications. All of the new M915A5 trucks will be equipped with the EMP Power 450 brushless alternator, which delivers up to 450 Amps at 28 Vdc that can be used for communications equipment or any other onboard electrical requirement.
“The Power 450 is effectively four alternators in one,” said Mark Bader, EMP’s director of new products and a technical engineering manager. “It
has four independent stator segments that each feed their own full wave rectifier, and after rectification the power is summed. “The Power 450 has been one of the key enablers of our thermal management systems for transit buses. Because of its success in the transit market, we’re receiving a lot of inquiries about its capability within a variety of applications — everything from wind power generation to marine vessels — and it’s emerging as a highly sought after component on its own.”
The development roots of the Power 450 alternator go back approximately four years to when EMP was looking for a high-output unit that it
could use as part of what became known as the Mini Hybrid engine thermal management system for transit buses. As the Mini Hybrid system
electrifies a number of components more commonly mechanically driven — compressors, pumps and as many as 10 radiator fans — it required
greater capability than most conventional alternators could provide.
“We searched high and low for an alternator, but we quickly learned that the conventional alternators available on the market were not adequate to provide the additional electrical power necessary to drive our fans,” said Bader. “We looked at all of the options and we couldn’t find a cost-effective solution.
“We considered having someone build one for us, but the bus market isn’t that big, about 5500 units a year. So for us to go to one of the alternator manufacturers and tell them we wanted them to go design a new alternator for 5500 units, well there’s really not a good business case for that. So we decided to do it on our own.”
Yet not entirely on its own. In its original hunt for an alternator, one of the machines EMP looked at was an air-cooled design from a Canadian manufacturer. “They had some prototype alternators we looked at and the electrical design was very good,” Bader said. “We did all of our calculations and electronically, all of the rotors and windings were correct and it would do what we needed.”
After reaching an agreement with the company, EMP then went to work optimizing the overall design. “Mechanically, we changed just about everything,” Bader said. “We changed from sand castings to permanent mold castings or high-pressure die castings. We redesigned the air passages and the diode holders. We went from a welded steel fan to a cast aluminum fan.
“We tightened all the clearances and tolerances. We spent a lot of time on the bearings and studied how the air-flow went through the castings. We did CFD and FEA work and even looked at how it would be manufactured. “Ultimately, we touched about every part and it’s probably
about 95% different.”
A specific area of attention focused on the bearings and temperature management. The Power 450 alternator’s bearing set was engineered by EMP and bearing specialist NSK to provide long service life in the most arduous conditions. The outside diameter of the front bearing was increased 25%, providing a 52% higher dynamic load rating. Maximum loads as high as 315 lb. can be accommodated, EMP said. In transit bus applications, this translated to 3.5 times more bearing life, the company said. The rear bearing was similarly beefed up, with a 16% increase in outside diameter that results in a 32% increase in dynamic load capability (up to 75 lb.). Again in the transit application, this has shown double the normal bearing life, according to EMP.
Both bearings also incorporate Viton seals and special high-temperature grease formulated to enhance service life.
Another feature targeting enhanced service life is a remote air intake, which allows air to be drawn from more optimum locations inside or outside of the engine compartment. This, combined with the internal air-flow geometry and materials selected, allows the unit to maximize heat rejection and minimize bearing temperatures, the company said.
“Instead of just drawing superheated air from somewhere under the hood, we can draw from a cooler area,” said Kurt Wasilewski, EMP’s electrical engineering supervisor and another technical manager of the Power 450 development. “In most cases, we suggest that the alternator’s air supply be sourced outside the engine compartment. “However, in the military truck, we worked very closely with Freightliner to identify where that air intake was going to come from. In the end, they did decide to draw the air from within the engine bay, but our testing showed that
it was still within our reasonable limits.”
The Power 450 alternator has an operating temperature range of -40° to 203°F and has a maximum operating speed of 6500 rpm. In emergency situations, the unit can withstand intermittent speeds up to 8000 rpm for as long as 30 seconds, the company said.
Physical dimensions (15 in. long with a 10.25 in. diameter and weighing 100 lb.) are in line with many conventional alternators, and the fact that it can use a standard cradle mount assembly and pulley means it can be used as a drop-in retrofit for conventional alternators, EMP said. It also can be specified with optional overrunning clutch pulley kits and Syklone air cleaner kits for the remote air intake.
Assembly of the Power 450 alternator begins outside the U.S., and the final assembly, which includes specific mounting or pulley configurations,
as well as testing, is done at EMP’s Escanaba, Mich., facilities.
While EMP has only recently looked to market the Power 450 alternator as a discrete component, the company already has a significant amount of experience with it. More than 500 units have racked up in excess of 5 million miles in Mini Hybrid pilot programs in the transit industry. Along with that, EMP can point to the additional testing it did with Daimler for the M915A5 truck program.
“We’ve spent a lot of time and money getting it to this point,” said Bader. “And as I mentioned, we’re starting to get a lot of inquiries for applications like fire trucks and ambulances. We’re also involved with a major truck fleet in the U.S. that is working on an anti-idling program and is looking at using Power 450's to charge supercapacitors.
“One thing that has caught a lot of attention is the fact that you can have 280 Amps at idle. We’ve done studies with some municipalities on battery life, and there is a real benefit to having that kind of power down low. Transit buses spend a lot of time where they’re just sitting at idle, but they’re still operating signs and air conditioning and there is still a huge electrical load. What we’ve seen is, with being able to have that kind of power at idle, it can provide a huge improvement in battery life. That’s something a lot of people are interested in.”
When involved in conflict, the U.S. Armed Forces typically learn a lot about the equipment it deploys on the battlefield. A case in point would be the U.S. Army’s M915A3 military linehaul tractor. Built for the Army by Daimler Trucks North America LLC, the vehicle has been used in a range of hauling applications in the Gulf and other regions. And not surprisingly, during the course of those duties, some new requirements have come to light.
In the case of the recent wars in Iraq and Afghanistan, the lessons learned from the deployed M915A3 included a need for heavier armor protection and the availability of more electrical power to run the evermoresophisticated communications gear that has become standard in nearly all military vehicle platforms. Those lessons are being applied in the newest version, the M915A5 military linehaul tractors, 1780 of which were ordered by the Army earlier this year. The new 6x4 workhorse, which will begin deliveries in 2010, incorporates new armor (in the form of an A-kit and B-kit) as well as a higher-output Detroit Diesel Series 60 diesel engine, which has been boosted to 500 hp — a 15% increase in horsepower over the current M915A3.
Being able to accommodate the increased electrical demand was the other major challenge, but the answer proved to be an alternator design
originally developed by Engineered Machined Products (EMP) as part of an advanced cooling system for truck and bus applications. All of the new M915A5 trucks will be equipped with the EMP Power 450 brushless alternator, which delivers up to 450 Amps at 28 Vdc that can be used for communications equipment or any other onboard electrical requirement.
“The Power 450 is effectively four alternators in one,” said Mark Bader, EMP’s director of new products and a technical engineering manager. “It
has four independent stator segments that each feed their own full wave rectifier, and after rectification the power is summed. “The Power 450 has been one of the key enablers of our thermal management systems for transit buses. Because of its success in the transit market, we’re receiving a lot of inquiries about its capability within a variety of applications — everything from wind power generation to marine vessels — and it’s emerging as a highly sought after component on its own.”
The development roots of the Power 450 alternator go back approximately four years to when EMP was looking for a high-output unit that it
could use as part of what became known as the Mini Hybrid engine thermal management system for transit buses. As the Mini Hybrid system
electrifies a number of components more commonly mechanically driven — compressors, pumps and as many as 10 radiator fans — it required
greater capability than most conventional alternators could provide.
“We searched high and low for an alternator, but we quickly learned that the conventional alternators available on the market were not adequate to provide the additional electrical power necessary to drive our fans,” said Bader. “We looked at all of the options and we couldn’t find a cost-effective solution.
“We considered having someone build one for us, but the bus market isn’t that big, about 5500 units a year. So for us to go to one of the alternator manufacturers and tell them we wanted them to go design a new alternator for 5500 units, well there’s really not a good business case for that. So we decided to do it on our own.”
Yet not entirely on its own. In its original hunt for an alternator, one of the machines EMP looked at was an air-cooled design from a Canadian manufacturer. “They had some prototype alternators we looked at and the electrical design was very good,” Bader said. “We did all of our calculations and electronically, all of the rotors and windings were correct and it would do what we needed.”
After reaching an agreement with the company, EMP then went to work optimizing the overall design. “Mechanically, we changed just about everything,” Bader said. “We changed from sand castings to permanent mold castings or high-pressure die castings. We redesigned the air passages and the diode holders. We went from a welded steel fan to a cast aluminum fan.
“We tightened all the clearances and tolerances. We spent a lot of time on the bearings and studied how the air-flow went through the castings. We did CFD and FEA work and even looked at how it would be manufactured. “Ultimately, we touched about every part and it’s probably
about 95% different.”
A specific area of attention focused on the bearings and temperature management. The Power 450 alternator’s bearing set was engineered by EMP and bearing specialist NSK to provide long service life in the most arduous conditions. The outside diameter of the front bearing was increased 25%, providing a 52% higher dynamic load rating. Maximum loads as high as 315 lb. can be accommodated, EMP said. In transit bus applications, this translated to 3.5 times more bearing life, the company said. The rear bearing was similarly beefed up, with a 16% increase in outside diameter that results in a 32% increase in dynamic load capability (up to 75 lb.). Again in the transit application, this has shown double the normal bearing life, according to EMP.
Both bearings also incorporate Viton seals and special high-temperature grease formulated to enhance service life.
Another feature targeting enhanced service life is a remote air intake, which allows air to be drawn from more optimum locations inside or outside of the engine compartment. This, combined with the internal air-flow geometry and materials selected, allows the unit to maximize heat rejection and minimize bearing temperatures, the company said.
“Instead of just drawing superheated air from somewhere under the hood, we can draw from a cooler area,” said Kurt Wasilewski, EMP’s electrical engineering supervisor and another technical manager of the Power 450 development. “In most cases, we suggest that the alternator’s air supply be sourced outside the engine compartment. “However, in the military truck, we worked very closely with Freightliner to identify where that air intake was going to come from. In the end, they did decide to draw the air from within the engine bay, but our testing showed that
it was still within our reasonable limits.”
The Power 450 alternator has an operating temperature range of -40° to 203°F and has a maximum operating speed of 6500 rpm. In emergency situations, the unit can withstand intermittent speeds up to 8000 rpm for as long as 30 seconds, the company said.
Physical dimensions (15 in. long with a 10.25 in. diameter and weighing 100 lb.) are in line with many conventional alternators, and the fact that it can use a standard cradle mount assembly and pulley means it can be used as a drop-in retrofit for conventional alternators, EMP said. It also can be specified with optional overrunning clutch pulley kits and Syklone air cleaner kits for the remote air intake.
Assembly of the Power 450 alternator begins outside the U.S., and the final assembly, which includes specific mounting or pulley configurations,
as well as testing, is done at EMP’s Escanaba, Mich., facilities.
While EMP has only recently looked to market the Power 450 alternator as a discrete component, the company already has a significant amount of experience with it. More than 500 units have racked up in excess of 5 million miles in Mini Hybrid pilot programs in the transit industry. Along with that, EMP can point to the additional testing it did with Daimler for the M915A5 truck program.
“We’ve spent a lot of time and money getting it to this point,” said Bader. “And as I mentioned, we’re starting to get a lot of inquiries for applications like fire trucks and ambulances. We’re also involved with a major truck fleet in the U.S. that is working on an anti-idling program and is looking at using Power 450's to charge supercapacitors.
“One thing that has caught a lot of attention is the fact that you can have 280 Amps at idle. We’ve done studies with some municipalities on battery life, and there is a real benefit to having that kind of power down low. Transit buses spend a lot of time where they’re just sitting at idle, but they’re still operating signs and air conditioning and there is still a huge electrical load. What we’ve seen is, with being able to have that kind of power at idle, it can provide a huge improvement in battery life. That’s something a lot of people are interested in.”
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