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Diesel cylinder deactivation achieved in Cummins X15


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Tom Quimby, Commercial Carrier Journal (CCJ)  /  April 22, 2020

The prospect of cylinder deactivation in diesel engines got a lot more interesting today as Cummins and propulsion software company Tula announced a successful demonstration of diesel Dynamic Skip Fire (dDSF) in a Cummins Efficiency Series X15 engine.

Silicon Valley-based Tula has seen its Dynamic Skip Fire software controls go to work in gasoline engines including the 2019 Chevy Silverado and 2019 GMC Sierra which GM reported can improve fuel efficiency by as much as 15 percent.

But diesel has been a more challenging space for cylinder deactivation technology where fleets are interested in more than just fuel savings. That’s where Dynamic Skip Fire can really shine through its ability to increase fuel savings and lower emissions in larger diesel engines which are up against a growing tide of regulations, particularly in California.

“The primary objective has been to evaluate what we will be able to bring to future emissions legislation,” said Lisa Farrell, Cummins’ director of advanced system integration. “The key advantage that this technology brings is to improve after-treatment temperature at low loads which is one of the areas that diesel engines—because they are so efficient—they have very low exhaust temperatures and so they’re very challenged to maintain NOx conversion efficiency at low load and under low load operation.

“And so that’s where this technology really shines because it improves the temperature, improves the aftertreatment NOx conversion and also simultaneously gives you a fuel economy benefit,” Farrell continued.

Cummins and Tula began working on diesel cylinder deactivation in early 2019. Tula’s proprietary software control algorithms play the role of all-important conductor by managing carefully measured and timed doses of fuel and air mixtures along with controlling precise intake and exhaust valve closings that can shut down unneeded cylinders to save fuel and increase exhaust temperatures in low-load conditions which in turn burns off more NOx.

The technology also achieves CO2 reductions through improvements in combustion and reductions in pumping work.

“Demonstrating the capability to improve fuel efficiency while also achieving very effective emissions control is extremely important for all diesel engine applications in the future,” said R. Scott Bailey, president and CEO of Tula Technology. “Our partnership with Cummins has given us the opportunity to expand our DSF technology beyond its success in gasoline engines.”

But software would be nothing if not for the hardware that it relentlessly seeks to optimize.

“We have actually been working with both Eaton and Jacobs Vehicle Systems as suppliers of the hardware that would allow you to deactivate the cylinders on an event by event basis which is one of the requirements to fully optimize with the Tula algorithm,” Farrell explained.

So far, testing on Cummins dDSF X15 has been relegated mostly to the lab but plans are in the works to put it to work on the road.

“We have a vehicle that has the technology. As soon as we can get into the vehicle to actually test it we’ll be putting miles on it,” Farrell said.

As testing continues, performance figures relative to fuel efficiency and emissions will be released. In the meantime, Farrell is feeling confident about Skip Fire technology.

“I think it’s a very promising technology and obviously Cummins and Tula are investing a lot in this development program and we wouldn’t be doing that unless we saw a future for it,” she said.

That future might also include predictive mapping.

“We have done some studies and some DOE projects that focused on autonomous drive, predictive routes and the influence and impact it can have on Dynamic Skip Fire techniques,” said John Fuerst, Tula’s senior vice president of engineering. “It was a gasoline-focused study but your hunch is right on. There really are significant benefits if you can think about it just in engine parameters in advance and not just reacting instantaneously but having a broader strategy to take advantage of the various parameters that you can adjust. So I think it’s an area for future study in the diesel arena much as we’ve done so far on the gasoline side. But it’s work to be done in the future.”

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Cummins, Tula to test cylinder deactivation on diesels

Richard Truett, Automotive News  /  April 22, 2020

A cylinder-deactivation system now used in many General Motors gasoline-powered light trucks could be applied to commercial diesel trucks.

Tula Technology Inc. and diesel engine manufacturer Cummins plan to begin testing a six-cylinder semitruck diesel engine outfitted with a version of the technology, called Dynamic Skip Fire.

The system is being tested first on Cummins 6.7-liter inline turbo six X15 semi-truck engine. If testing yields positive results and it moves into production, the technology likely will appear on semitrucks.

There is also a path for commercializing the technology for diesel engines that are used in consumer pickup trucks.

The development is notable because it points in a different direction from most of the auto industry at the moment.

Powertrain programs around the world are currently focused on electrification strategies. The idea of applying Dynamic Skip Fire to commercial trucks suggests that automakers and truckmakers see future potential in working with internal combustion engines — diesel engines at that — to stake out fuel efficiency gains in the future.

"When you look at commercial applications, electrification isn't practical for most long-haul trucks," said Tula CEO Scott Bailey. "From an environmental standpoint, you have to do everything possible to clean up the current engine.

"Every major country and region around the globe has NOx and C02 reduction on the books or legislation pending. This is the segment that needs attention first," Bailey said.

Engine changes to allow the cylinder deactivation would center around modifying the valvetrain to allow the valves to stay closed when a cylinder is shut down.

"It's applicable to any diesel engine, and we intend to apply to it any size engine in any application," Bailey told Automotive News.

Tula, a Silicon Valley software controls company, is backed by Delphi Technologies, General Motors and several venture capital firms.

Bailey estimates that, if development of Dynamic Skip Fire continues with no snags, the system could be ready for production as early as 2024. He believes the rollout will be driven by tightening by global emissions standards.

In the GM vehicles where it is now used, cylinder deactivation is intended to improve fuel economy. For diesel engines, the fuel gains are expected to be more modest — around 1.5 percent to 3 percent. Early testing has shown that a semi-truck such as a Freightliner could save around $1,800 a year in fuel costs.

But the reduction in tailpipe emissions is significant.

Bailey said that precise management of exhaust gas temperatures allows an engine's aftertreatment systems to operate more efficiently more of the time.

"At low loads, we can increase the exhaust temperature by anywhere from 58 to 90 degrees Celsius, which keeps the aftertreatment systems exactly where it wants to be from a peak emissions standpoint.

"What we end up is huge reductions on C02 and NOx reductions," he said.

In computer testing that simulates EPA drive cycles, a Cummins X15 engine running with Dynamic Skip Fire showed reductions in NOx emissions ranging from 45 percent to 66 percent and C02 reductions of 1.5 percent to 3.7 percent, the company said.

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I just hope it doesn't cause all the valve train failures it is causing the 5.7 Hemi and the 5.3 GM engines.

I have been seeing an alarming number of new X15 Performance Series with melted pistons and holes in the block, reminiscent of the old Signature 600. I wonder what is going on there? Seems to be mostly the 565 rating.

 

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6 hours ago, Bullheaded said:

 

I have been seeing an alarming number of new X15 Performance Series with melted pistons and holes in the block, reminiscent of the old Signature 600.

 

How common is this on the Signature 600? I'm just curious because the truck I am currently driving has one.

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1 hour ago, sbrem said:

How common is this on the Signature 600? I'm just curious because the truck I am currently driving has one.

I've seen 3 local and my friend in Australia has sent me lots of pics of Signatures with external pistons, LOL

 

I have no idea the cause or how widespread? Of the 3 local I have seen I can say one is a guy that does zero maintenance. One was turned up and the other was stock.

Don't know anything about the Australian ones other than they were pulling road trains.

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1 minute ago, Bullheaded said:

I don't wanna freak you out sbrem. I've just seen a few, not sure why.

Not really a huge deal to me, I just drive it I don't own it. LOL. I do try my best to take care of it though.  I was just wondering because  my boss had also heard of some  blowing up(at fairly close to the miles and hours ours is at), but not really with any first had knowledge of what had actually happened. I will say it is definitely a nice running motor as long as it holds together.

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They were alright to drive. I drove one when they came out in the CL. A tuned Signature still won't touch a tuned E9 Mack though. Except for engine braking. NOTHING has a Jake as strong as a Signature or an ISX.

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4 minutes ago, Bullheaded said:

Except for engine braking. NOTHING has a Jake as strong as a Signature or an ISX.

I have never had the fortune to drive an E9 but I agree with you about the Jake on the Signature for sure! While I have by no means driven every engine out there(not even close), nothing else that I have driven will hold back even close to how that Cummins will.

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My Detroit DD's are close, but Cummins Jake still has an edge.

Does your truck have the 6 position Jake? One of CL's I drove had that 6 position switch. After driving Mack Dynatard and Jake's, the first time I was coming up to an intersection with that Cummins I hit the Jake.......then had to get back on the throttle to make it to where I had to stop, LOL

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No, this one just has a regular 3 stage switch. Sometimes the 3rd stage will act up and it only comes on medium (It's actually at the shop getting fixed now), but I think even on just 4 cylinders it works at least as good as the E7 I used to drive did on high!

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Our  mp 10 engine brakes are as strong as our cummins x15's. well tbe mp 10 actually hold back better in the low rpm and will bring you to complete stop almost with out using the air brakes . The cummins work a tad better in the higher rpm but cut out in the lower rpm . Our titans all have original brake shoes and drums , and all of them have over 300k miles loaded heavy all the time.

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One of these days some smart guy is going to figure out how to operate an engine's valves with electro-hydraulic solenoids and get rid of the camshaft altogether.  Then you could have completely variable valve timing, cylinder deactivation on any cylinder at any time, better emissions, and extremely fast and effective engine braking.  I give it about 10 more years.  

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4 hours ago, RoadwayR said:

One of these days some smart guy is going to figure out how to operate an engine's valves with electro-hydraulic solenoids and get rid of the camshaft altogether.  Then you could have completely variable valve timing, cylinder deactivation on any cylinder at any time, better emissions, and extremely fast and effective engine braking.  I give it about 10 more years.  

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