Cummins Centenel System

[conrod]

This one was thrown at me the other day. The installation of a system, developed by Cummins Diesel, for reusing the " old oil " from the crankcase.

Apparently a small amount of the CC oil is removed by a timed metering pump, placed in a tank, and the oil is made up with clean. The old oil is then mixed with the fuel and burnt.

I have hammered away at Cummins web site, but get nothing from it. Can anybody throw me a bone on this one.

[JK]

That is interesting.
You get away from all of the hassles of burning the sludge produced by the purifiers or draining all the oil into a tank then burning it in an incinerator.

But, I wonder what the implications are to a LO condition monitoring program. If you are constantly removing old oil and putting in make-up oil there wouldn't be an accurate reading.

[TxMarEng]

Years ago we used to regularly dump the crankcase oil into the HFO bunker tanks and burn it however, such is not the practice today as the heavily compounded oils and the vast increase in engine ratings indicates this is not a good practice. The detergent additives create a large amount of ash when burned and result in serious fouling of the ring pack area. CAT's tears ago required even a low ash lube. They were one of the first to go to a 3 ring piston in addition to substantial increases in ratings. ISO8217 specs for HFO include a clause banning the inclusion of used lubes in Marine Fuel Oils.

I find it odd that Cummins would recommend the practice in small high speed engines.

[TxMarEng]

I stand corrected: However, I think this system in the long run would have more operational implications than benefits.

From Cummins Website:

Cummins Centinel Available for Aftermarket Purchase

For Immediate Release
March 23, 2005

Las Vegas - Cummins Inc. (NYSE:CMI) announced that the CENTINELTM Advanced Engine Oil Management System is now available as an aftermarket kit for the QSX, QSK19, QSK45 and QSK60 engines rated between 350-3000 (261-2238 kW) horsepower. CENTINEL, formerly only available as a new engine option, can be easily purchased and installed at any Cummins distributor location allowing Cummins powered equipment operators to take advantage of this cost and time saving technology even if the machine did not initially have this capability. Cummins is focused on helping the operator reduce operating costs while maintaining the highest levels of uptime in the industry.

The CENTINEL Advanced Engine Oil Management System enables equipment operators to extend oil change intervals to as much as 4,000 hours. Depending on the platform, the extension equates to removing 15-20 oil changes and thereby reduces maintenance time and expense. CENTINEL integrates with Cummins full authority electronics, allowing the engine to blend lube oil with fuel prior to engine combustion and adjusts the burn rate based on the equipment load factor. The system is available with reserve tanks for continuous oil replenishment.

Further maintenance interval extensions can be achieved with the addition of the ELIMINATORTM oil filtration system, a full-flow and centrifugal system that incorporates a permanent core. By eliminating the need to replace and dispose of used oil filters, lube system maintenance costs are reduced by as much as 90%.

Cummins Inc., a global power leader, is a corporation of complementary business units that design, manufacture, distribute and service engines and related technologies, including fuel systems, controls, air handling, filtration, emission solutions and electrical power generation systems. Headquartered in Columbus, Indiana (USA), Cummins serves customers in more than 160 countries through its network of 550 distributor facilities and more than 5,000 dealer locations. With more than 28,000 employees worldwide, Cummins reported sales of $8.4 billion in 2004. Press releases can be found on the Web at www.cummins.com.

[conrod]

TxMarEng,

Thanks for the info. I have been - several times - onto Cummins web site, but either my desktop has a malfunction or its operator does, because I could not get past the front page. Do you have a user profile and log in...........is that the only way to get info ??

Any way, I appreciate your looking for me, and I am a little wiser for it.

Now this then poses the question.............has anybody sailed with this setup, and have they any feed back on engine condition at overhaul times, and as you said previously, condition monitoring of the oil. I think many owners think that Oil Monitoring, is just to tell them the state of the oil............and forget that the metal content tells a whole bigger picture !

[TxMarEng]

No I just searched Centinel on the search line and it brought up reference articles. Must be working out as there are quite a lot of the Cummins out there in new diesel electric OSV's

[conrod]

TxMarEng,

Thanks. I have found my Javascript is playing up, and half the page does not come up, but I found the newsletter.

As you correctly point out, Cummins have a good chunk of the OSV market.............not quite sure where though, I have never sailed with them, and only know of 1 of our vessels that had them as Gen Sets. But its a big market, so I am sure they are out there.

I would still be interested in hearing some feedback though.

[Dieseldame]

Hey Conrad, welcome back! Thanks for the news on Cummins..very interesting. As to Customer Feedback..found this online. Its a few years old and from the land lubbers but might be helpful....

DD

American Freightways Says Cummins, CENTINEL Helping to Improve Business
Business Wire, Nov 7, 2000

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Business Editors & Automotive Writers

HARRISON, Ark.--(AutomotiveWire)--Nov. 7, 2000

In just over six months, American Freightways has lightened its load... in a good way. By installing Cummins (NYSE:CUM) CENTINEL(TM) Advanced Engine Oil Management System in 1,275 of its 6,000 line-haul trucks, the company's economic and environmental loads have decreased. And it probably won't need to change those trucks' oil until 2003.

Based in Harrison, Ark., American Freightways (AF) specializes in interstate and interregional LTL loads to 40 states. The company will run a total of some 468 million miles in 2000. At more than 10 gallons of engine oil per Cummins ISM diesel engine the company runs, and recommended oil and oil filter change intervals at 35,000 miles (56,328 km), that's a lot of oil. And it's a lot of downtime.

Related Results
Cummins CENTINEL Oil Management.(Oils and Lubricants)
More Muscle For The Mines

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"We were creating a vast amount of waste in spent oil and filters, plus it was costing us more money and time to replace them than we wanted," said Dan Umphress, AF's vice president of maintenance. On recommendation from its supplier, Cummins Mid-South LLC, Memphis, Tenn., American Freightways found that, with CENTINEL, it could change all of that.

"We went to the CENTINEL system to reduce our stream of waste oil for disposal from our shops, and because we feel we will get longer life from our engines through better oil additive package management. Besides, it is hard to really know and control where that waste oil goes once you release it," said Umphress, whose team is responsible for drains and filter changes. Typically, AF's engine oil is hauled off to blenders for recycling.

How does it work? Cummins CENTINEL reduces downtime by providing heavy-duty truck fleet owners with a convenient, cost-effective way to extend oil change intervals to 525,000 miles (844,906 km) and oil filter changes to 125,000 miles (201,169 km). The patented system slowly burns used engine lube oil at a small percentage of the fuel rate, thereby reducing hazardous waste. There are two versions of the system, one requiring a replenishment tank and the other operating as burn-only.

For owners and fleet managers whose trucks return to the garage every day, like AF, the burn-only system is best. It has no separate oil reservoir as with the replenishing CENTINEL system, and this reduces weight.

"Basically, a burn-only CENTINEL monitors the engine's duty cycle and load factors, and it takes a small amount of used oil out of the lubrication system, sending it down to the fuel tank," explained Duane Dean, account executive, Cummins Mid-South. "We're basically blending that oil in with the diesel fuel to be burned during combustion.

"It's really a brilliant solution for reducing waste oil engine wear and for cutting back on fuel expenses. CENTINEL can save fleets and owner/operators money over the course of a year. You spend less on fuel and oil. And trucks spend more time out on the road," Dean said. "If you think about it, the oil is constantly being refreshed, so not only does it stay clean, but you extend the service life of your Cummins engine."

Umphress said his fleet's oil analyses and amount of waste are evidence of the CENTINEL claim. "We draw an oil analysis on each tractor every 36,000 miles (57,937 km), and we now find the trends of the analyses are flat-lined, meaning the lube oil is clean and well within our tolerances, which helps us to estimate engine wear," he explained. "What's more, we have less waste oil and dirty filters being sent out to recyclers and dumps.

"CENTINEL has really made a difference throughout our company. Our drivers don't mind monitoring or adding the oil, our mechanics can focus more time on more major preventive and repair service, and American Freightways corporate team likes the numbers we're sending. Besides," added Umphress, "we all like knowing we're consuming less oil and polluting less after we use it."

"Cummins," said Dean, "works every day at leading the diesel engine and trucking industries in environmental stewardship. As a company, we prefer to embrace the challenges the EPA presents us and find not only ways to meet future regulations, but ways to improve engine performance to meet drivers' and fleets' wants and needs."

"We've been working with Cummins Mid-South since we sent our first truck out onto the road, in 1982," said Umphress. "They not only provide us with hard-running, long-lasting engines and engine service, but we know we can rely on them for trustworthy, successful solutions to our maintenance and purchasing needs. With high fuel and engine oil costs, increasing customer demands and stricter regulations to come, Cummins has helped us meet our business goals too. Those engines and people are well worth their weight in, well, oil, quite frankly."

Cummins, headquartered in Columbus, Ind., is the world's largest producer of diesel engines above 200 horsepower. The company provides products and services for customers in markets worldwide for engines, power generation and filtration. In 1999, Cummins reported sales of $6.6 billion. Press releases by fax may be requested by calling News on Demand (toll-free) at 888/329-2305. Cummins home page on the Internet can be found at www.cummins.com.

[Dieseldame]

Hey C, found this too..there is an email address at the bottom of a guy who used to work at Cummins and apparently knows the system.

DD

Inside Look

Managing the addition of oil to a diesel engine's fuel-oil mix turns out to be a tricky problem. Here's one design that worked well.

Welcome to the first edition of Inside Look, a periodic column that takes an in-depth look at the design of a successful, unsuccessful, or just plain interesting embedded system. This isn't a marketing pitch. We're scrutinizing the technical aspects of the design, to find out what went right, what went wrong, and what would go differently if the designers had the opportunity to do it all over again.

This month features a device called Centinel, a system that works to eliminate oil changes for big diesel trucks and other diesel powered equipment. This product has been an amazing success, and chances are you've passed or been passed by trucks with this hardware built in. Enjoy the inside look.

Centinel

The Centinel Advanced Oil Management System is an embedded system that extends oil change intervals on electronically controlled diesel engines by periodically removing a small amount of used oil from the engine's crankcase and replacing it with fresh oil. The used oil is sent to the engine's fuel tank, where it is blended with the fuel and burned during normal combustion.

Centinel allows diesel-powered trucks, tractors, generators, and other equipment to spend more time at work, and less time in the shop for oil changes and other routine maintenance. And by burning the used oil as fuel, Centinel also saves money and reduces environmental damage by eliminating the need to dispose of used oil. This idea is not new. Mechanical systems with similar functionality have been around for years, but today's sophisticated engine controllers and strict air quality standards make an all-mechanical solution impractical. Centinel is better than mechanical systems at maintaining engine oil quality because it contains a sophisticated algorithm that replaces oil at a rate proportional to the engine's workload, and also because it adds fault detection logic that cannot be implemented mechanically.

Problems to solve

From the beginning, Centinel's designers knew that the device needed to be reliable. Significant damage can occur to an engine if the oil quality deteriorates or the oil level drops, and since Centinel removes oil from an engine, it must take precautions to ensure that the oil level and quality are maintained throughout the process. This problem was trickier than it sounds, because inexpensive oil level sensors capable of surviving the harsh conditions found inside of a diesel engine did not exist at the time. Centinel also had to be durable. On-highway diesel trucks routinely travel as many as 200,000 miles a year in all types of climates and conditions, and industrial machinery, like construction equipment, often goes without maintenance for months at a time (although this is not generally considered a good idea). Furthermore, commercial diesel applications seek to maintain the highest productivity possible, which means they cannot stand idle while an "accessory" like Centinel is down for repairs. Centinel's software quality was also an issue, since the microcontroller would be an one-time-programmable part: the firmware could not be updated once the system was manufactured. A defect in software found after production would result in the replacement of all existing Centinel units.

Finally, the product had to be affordable. The first Centinel units were to be offered as an aftermarket, owner-installed device, meaning its sales price had to be significantly less than the savings it could achieve. This made for an aggressive cost target.

Approach

Centinel is an electromechanical design featuring a TMS370 microcontroller, an SAE J1587 automotive datalink interface, a mechanical valve assembly to transfer oil in and out of the engine, sensors to measure oil levels, and a tank to hold fresh oil.

During normal operation, the microcontroller reads engine information from the J1587 datalink to determine the engine's current workload and to detect the occurrence of various engine- and oil-related system faults. This information is used to calculate an oil burn rate, which is then trnaslated into a series of electrical pulses that cause the oil transfer valve assembly to transfer used oil from the engine's crankcase to the fuel tank. The oil transfer valve's design combines the used and fresh oil pistons into the same mechanical package, yielding a device that reliably transfers a fixed, known quantity of used oil to the fuel tank, and replaces it with an identical quantity of fresh oil on the return stroke. The valve and related plumbing are heated by the engine, which helps keep the oil flowing even in the coldest climates.

A sensor indicates when the fresh oil reservoir is empty, and Centinel will postpone pulses until additional oil is provided. The engine operator must still monitor the dipstick in the engine's crankcase, and manually add oil as necessary to replace the small amount the engine burns internally during normal operation.

Details

Texas Instruments' TMS370 microcontroller forms the foundation of the design. This controller was selected for its low price, high integration, and availability (at the time, competing chips from other vendors had lead times that were beyond the intended project completion date). Other chip selection criteria included temperature range, number of onboard timers, amount of memory (RAM, ROM, and EEPROM), and the chip's packaging options.

The variant of the TMS370 chosen sports 256 bytes of onboard RAM, 8KB of OTPROM, 256 bytes of EEPROM, a serial communications interface (SCI), two 16-bit counters, 23 digital inputs, an 8-channel analog-to-digital converter (ADC), and a 12MHz system clock. Additional components in the Centinel design include power conditioning and power failure detection circuitry, and an SAE J1587 datalink interface (similar to an RS-485 network) to connect to the engine's communications datalink.

To improve reliability and durability, all of Centinel's data inputs are extensively qualified in both hardware and software before the values are used. Clever hardware detects open and short circuits on inputs and outputs, and careful range checking of all input values prevents improper operation in the event of tampering or electrical failure. The primary control algorithm runs on a fixed 20ms interval, and combines engine workload, climate, and other information received from the engine datalink to compute the proper oil burn rate. The oil replacement rate, therefore, varies in real time, and seeks to maintain oil quality at a level that approximates a typical 20,000 mile oil change interval, regardless of the engine's actual duty cycle.

Once the proper oil burn rate is calculated, the value is passed to a second algorithm that computes the rate at which pulses must be sent to the oil transfer valve assembly in order to actually burn and replace the requested volume of oil. The logic at this stage is challenging, because pulses are postponed when the fresh oil tank is empty, the oil is cold, or a system fault is detected. When the operator refills the fresh oil tank, the oil warms, or the fault is fixed, pulses are sent at an accelerated rate in order to "catch up" to the requested volume.

To minimize air pollution concerns, EPA guidelines limit the amount of oil that can be burned as fuel in an automotive diesel engine. To prevent Centinel from exceeding this limit, a third algorithm restricts the maximum pulse rate sent to the oil transfer valve under all circumstances, so much so that in extreme cases, the recovery of delayed pulses can take hours, or even days to complete.

Software architecture

On startup, the software configures the microcontroller's I/O hardware, timers, serial communications port, ADC, and other peripherals. It then enters an endless do-nothing loop. Interrupt service routines contain the bulk of Centinel's code, a common approach in applications that need multithreaded behavior yet lack an operating system scheduler.

A periodic timer interrupt initiates the main control loop code, which resets a hardare watchdog timer only on successful completion. By resetting the watchdog timer at the end of the computation, a natural immunity to overruns is imposed: if the code ever takes too long to execute, the watchdog reset code gets interrupted by the next iteration of the algorithm, and eventually the watchdog timer expires.

Another interrupt service routine receives engine datalink information from the serial port. This code includes a simple state machine to parse the data and checksum fields of the incoming packets; packets with invalid checksums or out-of-range data are discarded. A timer measures the duration between successfully received packets and halts the burn rate computation if an excessive delay-indicating a cut datalink cable-is detected. This prevents Centinel from transferring oil when it lacks the engine information needed to determine what the proper burn rate should be.

Other interrupt service routines force periodic sampling of the TMS370's onboard ADCs, and notify Centinel of an impending power failure induced when the operator shuts down the engine (Centinel is powered by the ignition switch).

Unused interrupt vectors are filled with pointers to the startup function, essentially rebooting the system when an unexpected interrupt is detected.

Centinel's EEPROM is used to store important persistent data, like the number of oil pulses needed vs. the number actually sent. Unfortunately, these values cannot be updated on every iteration of the control loop, because doing so would surpass the EEPROM's write cycle limit well before the end of Centinel's expected lifetime. Instead, data is mirrored in RAM and written to EEPROM only at shutdown, during a 200ms holdup provided by capacitors built into Centinel's power supply circuitry.

The holdup time provides a good balance between reliability and cost (longer values would require more capacitance), but is critically close to the EEPROM's write cycle time, which means that there is virtually no room for unexpected delays during the shutdown process. And since the EEPROM contains vital information about the state of the oil burning process, its contents must be maintained under all real-world conditions other than outright device failure.

The shutdown and EEPROM updating process was reviewed and revised almost continuously during development. Particular attention was given to the logic that induced the writing process, the order in which bytes were written, checksums, and how much data was queued before writing began, to make sure that the amount of time required to perform the write operation was absolutely bounded, and to help assure that the system would reawaken in a safe state if an unanticipated error or early power failure somehow did occur.

One unexpected surprise during early field testing was that the excessively high-powered (in some cases illegally so) CB radios favored by many truckers could induce voltage swings of nearly 30V peak-to-peak on the truck's main power system (typically a 12V DC supply). These voltage spikes would trip Centinel's impending-power-failure circuitry, triggering excessive EEPROM writes and generally compromising system performance. To combat this, additional hysteresis code had to be added to Centinel's already extensive set of signal analysis logic, to prevent false power fail indications from initiating an avalanche of EEPROM updates when the radio was in use.

Process was key

One lesson that the Centinel development team learned was the benefits of good software design and process. Development tools were unexpectedly late in arriving, which gave the team further opportunity to refine Centinel's implementation on paper before coding began. Structured design tools were employed, along with use-case analysis and failure mode studies, so that by the time coding started the requirements were fairly complete.

By resisting the urge to start writing code too early, Centinel's software team produced an application that was remarkably free from defects and missed requirements, and even contained unspecified, supplemental logic to combat what were viewed to be the most likely bugs, such as the EEPROM overrun example mentioned previously. What might have been perceived as a costly delay actually produced a better quality product in the end, with minimal long-term impact to the project schedule.

A peer review process was also employed, and all work products like code and circuit designs were studied by other developers before they became part of the final solution. These "extra eyes" not only helped uncover bugs and missed requirements, it also fostered a sense of teamwork that let more people within the company participate in Centinel's success.

The results

Centinel is one of Cummins Engine Company's most successful products, apart from their award-winning family of electronically controlled diesel engines. Even after more than five years of production, the Centinel system has yet to need major improvements or revisions.

The Centinel design won an OEMmie award from OEM Off-Highway Magazine, and is largely regarded within Cummins as an example of how their continuous improvements in system engineering practices are yielding superior products. In fact, the design is so successful, it has served as a platform for several other new products, some of which will undoubtedly be featured in future Inside Looks.

Bill Gatliff is an independent embedded systems consultant, a former Cummins employee, and a contributing editor to ESP. If you have a product you would like to see featured in a future Inside Look, please contact him at [email protected]

Paul Cantrell is a management consultant with Pittiglio, Rabin, Todd, and McGrath. He is a former employee of Cummins Engine Company, and was the chief architect and developer of Centinel's firmware.

The authors wish to acknowledge the efforts of Andy Pajakowski, Alex Knight, and Gary Gron, all of Cummins Engine Company, for their assistance in preparing this article.

[conrod]

DD,

Thanks for the info. It makes interesting reading, but I think the underlying statement is that it saves them having to deal with gallons of waste oil, labour costs - mechanics to change it - and on the road down time. Very little of what was said relates to machinery monitoring.

With the lower power engines, when would you expect to change bottom ends and mains ? I've not given it much thought.

I would guess that 20,000 hours is not unreasonable on a medium speed marine unit, 40,000 for mains. For an OSV, that pretty close to 4 years of running for the bottom ends. High speed diesels I am sure are a tad different, but again I have not given it much thought or research..........YET !!

But I think my initial query has been answered, the system is out there, and some people think its the best thing since sliced bread. I still wonder if it really has a place on prime movers, in the marine field.

[Dieseldame]

Hey Conrad, don't know if I'm off base here but I was thinking about your comments on oil analysis and wondered something. If you keep the oil cleaner by sipping small bits all the time do you think it would have an impact on component wear?

DD

[JK]

If a company skid mounted these packages and planned to just pull them when the hours were up and put in a recon unit, I could see it being beneficial. Run them til they die idea.
But if you are using LO condition based monitoring as part of your regulatory extended machinery survey, then I couldn't see it is beneficial.

[conrod]

JK<

My argument entirely with the proposal. I am not a big fan I must admit. I go for condition monitoring anyday, but unfortunately I think disposal of the oil is the problem here................not the machine !!

[The Dieselduck]

I remember Wartsila pitching us a similar plan, they had a system in place and I am pretty sure I have the sales brochure for it somewhere, but right now I am on the boat and internet is scarce.

Anyways, if I remember correctly, it address several issues that were a concern to us with 12V46 running HFO380. 1 - The "manpower" of removing and replacing a cube or two of oil per engine per week to maintain proper TBN. 2 - This program they had would take care of this, then feed the "sipping" from the crankcase into the fuel inlet to burn in the engine. 3 - waste oil disposal cost.

I will see if I can find the brochure and further info on this and post it.

[JK]

I admit that I skimmed the description of the LO siphoning process, I kept thinking that todays marine engineer better have a darn solid back ground in electronics to keep the engines running with everything that hangs off them. Can you imagine this going TU on a rough night?