Diesel Particulate Filter: Info & Details

Politics of particulate filters

Für Peugeot war die Einführung des Partikelfilters bei seinem großen Diesel ein gewaltiger Marketingerfolg. Als solcher sollte der Filter aber auch in die Geschichte eingehen. Die übereifrigen deutschen Hüter der Umwelt jedoch sahen im Partikelfilter einen willkommenen Anlaß, der Welt wieder einmal zu beweisen, daß sie die Größten sind. Wen interessiert schon, daß die Environmental Protection Agency (EPA) in den USA erst im Mai 2002 Dieselabgase von "höchst wahrscheinlich" kanzerogen auf "wahrscheinlich" zurückstufte, weil es eindeutige Beweise für eine Gesundheitsgefährdung trotz der rund 60 Studien noch immer nicht gibt? Und das in den USA mit deren miserablem Dieselkraftstoff, der mindestens 50-mal (!) so viel Schwefel enthält wie der hier zu Lande verkaufte. Denn seit dem ersten Januar enthalten alle Benzinsorten und der Dieselkraftstoff in Deutschland nur noch maximal zehn ppm Schwefel. Schwefel aber gehört zu den Partikel bildenden Substanzen im Abgas. Zudem lagert sich Schwefel in den Katalysatoren ab und beeinträchtigt deren Funktion. Tatsächlich ging der Partikelausstoß mit Einführung der zehn ppm zwischen fünf und zehn Prozent zurück, bei alten Motoren kann es auch etwas mehr sein. Unsere Umweltgötter interessiert auch nicht, daß die Automobilhersteller längst an Entwicklungsprogrammen für die Verbrennung im Motor arbeiten, mit denen Schadstoffe im Abgas erst gar nicht entstehen können. Das Stichwort lautet "homogene Verbrennung". Aber der Weg dorthin ist steinig. Er führt zur Einzelregelung jedes Zylinders und wird von weiter verbessertem Kraftstoff wesentlich unterstützt. So wird die VW-Forschung nicht müde darauf hinzuweisen, daß synthetische Kraftstoffe unter dem Namen "Sunfuel" (aus Biomasse) und "Synfuel" (aus fossilen Grundstoffen) selbst das Abgasverhalten der besten heutigen Diesel um rund 50 Prozent verbessern, und das ohne weitere Maßnahmen an den Motoren. Davon abgesehen haben wir in Europa einheitliche Schadstoffgrenzwerte, die stetig verschärft werden. So Does Euro 4 halve the proportion of...? Stickoxide und Partikel gegenüber der derzeitigen Euro 3 um die Hälfte. VW bewies als erster Hersteller, daß diese Hürde mit innermotorischen Maßnahmen zu schaffen ist Die Wolfsburger bieten bereits drei Euro-4-Diesel an, im Frühjahr kommt ein weiterer hinzu. Ganz neu in diesem Klub ist der 1 ,7-Liter-Vierzyiinder-Diesel von Opel, der ebenfalls den Vorschriften der Euro 4 genügt. Aber auch Fiat legte den neuen 1 ,3-Liter-Diesel für die Euro 4 aus, weitere Motoren werden folgen - und keiner von ihnen braucht dazu einen Partikelfilter. Die Abgasvorschriften begrenzen Ja nicht nur den Partikelausstoß, sondern auch den der Stickoxide und des Kohlenmonoxids (CO). Beim Benziner kommen noch die unverbrannten Kohlenwasserstoffe (HC) hinzu, die der Diesel praktisch nicht ausstößt. Auch beim CO liegt er erheblich besser als der Benziner, dafür hat er Probleme bei Stickoxid und Partikeln, Die Grenzwerte der Euro 4 sorgen dafür, daß der Abstand des Diesels zum Benziner kleiner wird. Danach darf er nur noch maximal 0,25 Gramm pro Kilometer Stickoxide im Abgas enthalten und 0,025 Gramm Ruß (Partikel). Das ist weniger, als er an Schadstoffen, Staub und Schwebstoffen aus der Luft ansaugt. Dieselmotoren waren in der Herstellung schon immer teurer als Benziner. Bei teuren Autos fällt das nicht ins Gewicht, umso mehr bei kleinen und preiswerten. Ihre Einspritzanlagen müssen mit der gleichen Präzision, aus den gleichen teuren Werkstoffen gefertigt werden wie die der großen Motoren. Darum fällt der Preisunterschied zu den Benzinern bei kleinen Motoren viel krasser aus. Für ein Partikelfilter mit der zugehörigen Regelung muß auch bei ihnen mit einem Mehrpreis von rund 500 Euro gerechnet werden. Er würde dazu führen, daß wegen des zu großen Preisunterschiedes niemand mehr kleine Dieselautos kauft. Ist es das, was die Umweltstrategen anstreben? Ist es ihnen gleichgültig, daß Dieselmoloren rund 30 Prozent weniger verbrauchen als Benziner und damit auch rund 30 Prozent weniger Kohlendioxid ausstoßen? DeCurrently, there is only one manufacturer. für Filter-Monolithen (Ibeden/Japan), ein weiterer wird voraussichtlich hinzukommen. Hier gibt es also ein die Preise diktierendes Monopol, das niemand umgehen kann. Da die Regeneration des Partikelfilters erst bei Temperaturen zwischen 550 und 600 C beginnt, spritzt Peugeot eine Substanz auf der Basis seltener Erden ein. Damit sinkt die Regenerationstemperatur auf 450 bis 500 C. Dennoch sieht Peugeot eine Warnleuchte in der lnstrumententafel vor. Sie leuchtet auf, wenn sich im Filter zu viel unverbrannte Partikelmasse angesammelt hat. Dann empfiehlt die Betriebsanleitung, eine längere Strecke mit höherer Geschwindigkeit zu fahren, damit die Partikel verbrennen und der Filter entlastet wird. Besonders kleine Autos werden meist im Kurzstreckenverkehr gefahren. Wir bitten alle Damen mit Namen Lieschen Müller vorab um Entschuldigung, wenn wir das den "Lieschen-Müller-Fahrzyklus" nennen, bei dem der Motor nie richtig warm wird. Aber auch der Partikelfilter kommt dabei nie auf Regenerationstemperatur, ob nun ein Additiv eingespritzt wird oder nicht. Der Filter wird zunehmend verstopft, der Abgasgegendruck steigt an und damit der Verbrauch. Verstärkt wird dieser Effekt noch durch Späteinspritzung während der Kaltphase, die sich auch bei Peugeot findet Sie dient dazu, das Abgas aufzuheizen, kostet aber zusätzlichen Kraftstoff. Da kann man Interessenten nur raten, einen wesentlich billigeren Benziner zu kaufen, der im Kurzstreckenverkehr nicht mehr verbraucht und keine Filterprobleme kennt. Peugeot schreibt vor, den Partikelfilter nach 80.000 Kilometern zu wechseln. Die Kosten dafür wird der Käufer eines teuren Autos leichter verschmerzen als jener eines preiswerten. Auch diese Kosten können dazu führen, daß kleine Diesel aussterben. In den USA ist eine Haltbarkeit von 1 20.000 Meilen vorgeschrieben, das sind knapp 200.000 Kilometer. Hält ein Partikelfilter das nicht durch, muß der Hersteller die Kosten für den Austausch tragen. ZwGerman automakers, particularly DaimlerChrysler and Volkswagen, are currently trying to...it wieder einmal, den Diesel in den USA populär zu machen, doch einen Partikelfilter darf er nicht haben. Die Stunde der Wahrheit naht in den USA erst 2006, wenn Benziner und Diesel die gleichen Grenzwerte erfüllen müssen. Immer dann, wenn die Politik in der Technik herumpfuscht, ist mit Unheil zu rechnen. Die Ingenieure finden kein Gehör, denn die Profilierungssucht der Politiker hat einen weit höheren Stellenwert. Immerhin formiert sich nun Widerstand. Daß VDA-Präsident Bernd Gottschalk gegen den Partikelfilter wettert, VW-Forscher Wolfgang Steiger diese Art der Abgasnachbehandlung den "Horror jedes Motorenentwicklers" und BMW-Chef Helmut Panke den Partikelfilter eine schlechte Lösung nennt, mag die Politik als Lobbyismus abtun. Nicht so leicht beiseite schieben kann sie jedoch die ablehnende Haltung des ADAC-Präsidenten Peter Meyer. Er hat wie alle lngenieure, die sich gegen die generelle Einführung des Partikelfilters wenden, dafür solide Gründe. Welcher Automobilhersteller auch immer einen Partikelfilter einbauen will oder muß, weil er sonst die Abgasgrenzwerfe der Euro 4 nicht erfüllt, der möge das tun. Wenn andere Hersteller die Grenzwerte ohne Partikelfilter unterschreiten, ist das ihr Verdienst. Sie und die Verbraucher mit einem Zwang zum Partikelfilter zu bestrafen grenzt an Schizophrenie. UAnd we already have far too much of that around us.

PS/Christian Bartsch

Source: PS report, February 3, 2003.

'Some people solve it with intelligence and know-how (specifically, by optimizing the injection system), while others use afterburning. Unfortunately, our politicians have jumped on the bandwagon of the less intelligent solution! Sadly, they failed to see that there will likely be disposal problems again when it comes to disposing of the particulate filter, which is supposed to be replaced every 80,000 km. '

Hello,

I wouldn't consider the disposal to be much of a problem; the monoliths are usually made of silicon carbide, the soot already enters the environment, and the rest is mainly oil ash, which is essentially harmless calcium carbonate.
Furthermore, it is supposedly possible to verschandeln the filters and reuse them.

OM611 wrote:

... I wouldn't consider the disposal to be much of a problem. The monoliths are usually made of silicon carbide, the soot already enters the environment, and the rest is mainly oil ash, which is essentially harmless calcium carbonate. Furthermore, it is said that the filters can be cleaned and reused. ...

You can verschandeln them, but the waste from the cleaning process must be disposed of as hazardous waste (please don't ask why, but that's what Peugeot says).


Something else surprises me a lot about this article. A year ago (or even longer ago), the ADAC tested a Peugeot with a particulate filter (permanently) and subsequently demanded the general introduction of particulate filters. When I recently visited the ADAC website again, there was no mention of it anymore. Now, I have to read in the article that the ADAC president, Peter Meyer, is opposed to the general introduction of the particulate filter. ... Very strange... ??!??

It's also noteworthy that BMW and DC, with the currently available CR systems, can only meet the Euro 4 standard either with a particulate filter or (like Opel) with a lean-burn engine. However, it's possible that CR systems are already in development that will achieve this (which I am convinced of). On the other hand, the reduction in sulfur content in diesel fuel counteracts the decrease in soot emissions. I would be interested to know how this affects older diesel vehicles. When the sulfur content was first reduced, pump manufacturers were very concerned because they feared that their pumps wouldn't be able to handle it.

I'm not completely satisfied with the article either.
The lifespan of DPFs (diesel particulate filters) is likely longer than the stated 80,000 km. This figure is probably just a safety measure by the PSA group, as there hasn't been enough long-term observation in normal road traffic yet. Consider the early catalytic converters for gasoline engines; some still have lifespan specifications of 80,000 km, even though they actually function correctly for longer. (My Golf 2 managed over 300,000 km with a catalytic converter and consistently passed emissions tests with flying colors.)

'While increased fuel consumption can be attributed to adjusted injection systems, many exhaust emission control measures also contribute to it, for example, the EGR system.'

DPFs are not a final solution! Automotive manufacturers are working on further measures, but these are not yet ready for mass production or are currently too expensive. Furthermore, the development of DPFs is interesting because older vehicles can be retrofitted with them, making them cleaner.
The problem isn't really Euro 4 as much as it is Euro 5 and the US market.

'Lieschen Müller' is right; the filter needs to be cleaned at specific intervals. This cleaning process occurs through a higher exhaust temperature and takes approximately 10-15 minutes. This cleaning process only starts when the operating temperature is reached. The main problem with the cleaning process is the need to adjust fuel injection, boost pressure, and EGR variables during operation. The customer should not notice this process while driving, but this is difficult to achieve due to the performance losses caused by the cleaning process.
Someone who never reaches the operating temperature will have to deliberately cause it to happen. But let's be honest: how many people buy a diesel car, which is more expensive to purchase and insure, just to drive 5,000 kilometers a year?

The filters are less environmentally harmful than catalysts because they are not coated with any metals or other chemical substances. Filtration occurs simply by the flow of air through the filter pores, where soot particles become trapped. When cleaning, these particles are merely burned off and pass through the pores.

The current trend is towards a cleaning process that doesn't use any additives, but only modifies the combustion parameters at the beginning of the cleaning process. The cleaning then proceeds automatically.


Best regards, ixery.

ixery wrote:

... The lifespan of DPFs (diesel particulate filters) is likely longer than the stated 80,000 km. This figure is probably just a safety measure by the PSA group, as there hasn't been enough long-term observation in normal road traffic yet.

certainly correct

Quote:

Think about the first catalytic converters for gasoline engines; some manufacturers still specify lifespans of 80,000 km (approximately 50,000 miles), even though the catalytic converters can often function correctly for longer. My Golf Mk2 managed over 300,000 km (approximately 186,000 miles) with a catalytic converter, and it consistently passed emissions tests with flying colors.

... that's a fallacy. In the AU (official vehicle inspection), the catalytic converter function is not actually tested; measurements are even taken *before* the catalytic converter. Only the control behavior of the lambda sensor system is checked. You can only assess the actual catalytic converter function on a dynamometer. ADAC (German automobile club) conducted such tests a few years ago, and the results were shocking – some catalytic converters were failing after only 30,000 kilometers!

Quote:

"While increased fuel consumption can be attributed to adjusted injection systems, many exhaust emission control measures also contribute to it, for example, the EGR system." DPFs are not a final solution! Automotive manufacturers are working on further measures, but these are not yet ready for mass production or are currently too expensive. Furthermore, the development of DPFs is interesting because older vehicles can be retrofitted with them, making them cleaner.

It would be great if there were reliable retrofit solutions with DPFs available, but the automotive industry has no interest in them whatsoever.

Quote:

The problem isn't really Euro 4 as much as it is Euro 5 and the US market.

"...and that's precisely where the diesel particulate filter (DPF) cannot be used, because the sulfur content in U.S. fuel is too high, which would damage the filter. The DPF requires extremely low-sulfur diesel."
That's precisely why there is still no universal basic income (UBI) in the United States.

Quote:

... The filters are less environmentally harmful than catalysts because they are not coated with any metals or other chemical substances. Filtration occurs simply by the flow of air through the filter pores, where soot particles become trapped. When cleaning, these particles are merely burned off and pass through the pores.

Currently, additives are still needed, and this turns it into a "toxic kitchen."

Quote:

The current trend is towards a cleaning process that doesn't use any additives, but only modifies the combustion parameters at the beginning of the cleaning cycle. The cleaning then proceeds automatically.

Let's hope for the best. If I look at the particle values for that Peugeot, they are surprisingly low.

That is a fallacy. In the AU (Abgasuntersuchung - exhaust emissions test), the catalytic converter function is not actually checked; in fact, measurements are taken before the catalytic converter. Only the control behavior of the lambda system is checked. You can only assess the catalytic converter function on a dynamometer.

I cannot let this stand. At the emissions test (AU), the catalytic converter (KAT) is definitely measured after it, as the probe is inserted into the exhaust pipe. That connector, which is only found on VAG engines, was originally for diagnostic and basic setting purposes. And I can confirm from my own experience as an AU inspector that it is certainly possible for a catalytic converter to last 200,000 or 300,000 kilometers and still easily meet the measurement requirements.
Best regards,
Dominique.

The important pollutant values of NOx and CH, which are crucial for testing the catalytic converter (KAT) function, are not actually measured during the vehicle inspection (AU). Only the CO content is measured there, and that provides little information about the functionality of the catalytic converter.

"Sure, a KAT (catalytic converter) can last for 200,000 km or more, but the NOx and CH values will then be far beyond acceptable limits. The emissions test for gasoline engines is just as ridiculous as the one for diesel engines. In both cases, only numbers are measured that provide no information about the condition of the catalytic converter or other exhaust aftertreatment systems. Or can I determine the NOx content of diesel exhaust based on its opacity? No! However, it is possible to assess the condition of the DPF (diesel particulate filter) using the emissions test."
Furthermore, the responsiveness of the catalytic converter deteriorates with increasing mileage, which is not measured during the emissions test. An extensive test drive would be essential (using a dynamometer), but who should pay for it?

The AU is Absolutely Useless!

By the way, the oxygen sensor before the catalytic converter used to be mandatory. I always have problems with my Jetta because none of them are installed!

The important pollutant values of NOx and CH, which are crucial for testing the catalytic converter (KAT) function, are not actually measured during the vehicle inspection (AU). Only the CO content is measured there, and that provides little information about the catalytic converter's function.


Hello.

The catalytic converter burns both carbon monoxide (CO) and hydrocarbons (HC). Therefore, the CO reading can provide an indication (albeit approximate) of the condition of the catalytic converter.
But of course, it's not as good as the newer OBD systems that use a second oxygen sensor behind the catalytic converter to check the oxygen storage capacity and thus the aging of the catalytic converter. (For gasoline engines)
If the CO level is elevated, it could also be that only the oxygen sensor (lambda sensor) is faulty, which would then cause the catalytic converter to not function properly.

With a diesel engine, even if the CO level is elevated, one might suspect the catalytic converter, but of course, that doesn't say anything about its response behavior, as you mentioned.
Unfortunately, the biggest fundamental problem is the NOx emissions, which cannot be processed by a catalytic converter due to the lean-burn operation of the diesel engine.

Therefore, a catalytic converter (KAT) is not as crucial for a diesel engine as it is for a gasoline engine. Exhaust gas recirculation and particulate filters are even more important. And if I had to bet, I would wager that the constantly tightening emission regulations will eventually force the Volkswagen Group (VAG) to adopt this filter as well.

Best regards,
Certainly! Please provide the German text you would like me to translate into English. I will only provide the translation.

Ernst S. wrote:

The catalytic converter burns both carbon monoxide (CO) and hydrocarbons (HC). Therefore, the CO reading can provide an indication (albeit approximate) of the condition of the catalytic converter.

... or it's concluded that there's a wrong engine setting, and simply reversed (made leaner or richer), which masks a defective catalytic converter, and that's it.

Quote:

But of course, it's not as good as the newer OBD systems that use a second oxygen sensor behind the catalytic converter to check the oxygen storage capacity and thus the aging of the catalytic converter. (For gasoline engines)

That should at least work better than the current system. Because measuring only on one side of the catalytic converter is absolute nonsense!
I know of cars that pass the emissions test easily by using a catalytic converter simulator.

Quote:

If the CO level is elevated, it could also be that only the oxygen sensor (lambda sensor) is faulty, which would then cause the catalytic converter to not function properly.

... this becomes apparent during the emission control system test... provided that the exhaust system is properly sealed, which is often questionable in older cars.

Hello,

For EU 5 compliance, diesel engines will require a catalytic converter and particulate filter. By combining this with an excellent fuel injection system, such as common rail technology, it's possible to regulate the exhaust emissions so that they are cleaner than the air being drawn in.

Hello everyone!

The important pollutant values of NOx and CH, which are crucial for testing the catalytic converter (KAT) function, are not actually measured during the vehicle inspection (AU). Only the CO content is measured there, and that provides little information about the catalytic converter's function.


The catalytic converter burns both CO and HC. Therefore, the CO value can provide an (approximate) indication of the condition of the catalytic converter.

Now, let's move on to more facts and details about the technology used in AU measurement devices and catalysts.

1. How does a catalytic converter work in a gasoline engine?

Assuming an optimal air-fuel ratio of Lambda 1, both reduction and oxidation processes occur in the catalytic converter when it reaches its optimal operating temperature of 400-800 degrees Celsius. During oxidation, carbon monoxide (CO) and hydrocarbons (CH, typically indicated as HC on the measuring device) are converted into carbon dioxide (CO2) and water vapor (H2O) in the presence of oxygen (O2). During reduction, nitrogen oxides (NO, NO2) are converted to nitrogen (N2) using carbon monoxide (CO) as a reducing agent, and the remaining CO is reduced to CO2. The formula for this process is as follows:
2 CO + O2 -> 2 CO2
2 C2H6 + 7 O2 -> 6 H2O
2 NO + 2 CO -> N2 + 2 CO2

2. What does an AU tester measure, or why are these devices called '4-gas testers'?

In a modern, nowadays required exhaust testing system for gasoline engines, carbon monoxide (CO), carbon dioxide (CO2), unburned hydrocarbons (CH or HC), and the residual oxygen content in the exhaust are measured. From these 4 gases, the lambda value, which is the 5th measurement, is calculated. This should definitely make it clear that all exhaust components are relevant for the emissions test, and that a defective catalytic converter would indeed be detected during the test. During the testing process, it becomes very apparent when the effectiveness is no longer sufficient. Most often, the CO content will then be astronomically high in the partial load range.

That should at least work better than the current system. Because measuring only on one side of the catalyst is absolute nonsense!
I know of cars that pass the emissions test easily by using a catalytic converter simulator.

... this is noticeable during the emission control system test... provided that the exhaust system is properly sealed, which is questionable in older cars.

Absolutely not! You can only pass a proper G-KAT (catalytic converter) inspection with a fake catalytic converter at idle speed, if at all. During the partial load measurement, the CO values will easily reach 6% with a defective or missing catalytic converter, making it impossible to pass the inspection. Furthermore, a leaky exhaust system has no effect on the testing of the control loop; while the upper and lower measured values may vary compared to a sealed exhaust system, the change is always exactly the same. In addition, checking the exhaust system is just as important for a thorough inspection as checking the fuel system for leaks.

The AU is absolutely nonsense!

Yes and no. Regarding gasoline engines, I believe that both the purpose and quality of the inspection are well worth the effort, as the measurement is quite capable of providing an accurate assessment of exhaust emissions during operation. With diesel engines, opinions diverge greatly... I have even managed to get TDI models with 50000 km on them in 6 years (what was that test called again? The Lieschen-Müller cycle ) onto the tester, which only passed the emission test after the 8th or 9th injection pulse (!), in the 3rd attempt (!!). These vehicles were actually in excellent condition, just properly broken in in terms of performance, but they had been subjected to harsh conditions in city traffic. In addition, I believe that the so-called 'free acceleration' test is like reading tea leaves; one should really measure emissions using a vehicle with a large fuel tank going uphill at a 5-7% gradient, as that's when you really produce exhaust!

Best regards,

Dominique.

D. Kurz wrote:

...Never and ever! You can only pass a real G-KAT exhaust test with a fake catalytic converter at idle! During the partial load measurement, the CO values will easily reach 6% with a defective or missing catalytic converter, making it impossible to pass the test. And a leaky exhaust system has no effect whatsoever on the testing of the control loop; while the upper and lower measured values may vary compared to a sealed exhaust system, the change is always exactly the same.

For example:
A poorly sealing exhaust manifold gasket allows outside air to enter the exhaust system, and this reduces the CO emissions under partial load conditions (as measured), but not at idle. This works great – I've tried it myself.
By the way, several cars initially failed the emissions test because the exhaust manifold gasket wasn't completely sealed. This defect was not audible but could be measured with the emissions testing equipment. Simply tightening the exhaust manifold bolts a bit more and the emissions test became no problem.
Do you really believe that every competition car with a catalytic converter passes the emissions test legally, considering all the engine modifications? Rally cars also have to pass an emissions test because they are registered (at least in Germany).
It will not be possible to detect the malfunctioning of the catalytic converters on any exhaust emission tester. If you place the parts on a dynamometer and run the Euro cycle (under load), you can use a standard exhaust emission tester to prove the absence of the catalyst.

Quote:

In addition, the inspection of the exhaust system is an integral part of a thorough vehicle inspection and includes not only checking the emissions but also inspecting the fuel system for leaks.

Do you believe it? Even the TÜV (German technical inspection agency) is not capable of doing that (see above).

Quote:

"... In addition, in my opinion, so-called "free acceleration" is like reading tea leaves; what you really need to do is measure the exhaust output using a dynamometer on an uphill slope with a gradient of 5-7%, because that's when you really see some exhaust being produced!"

Unfortunately, the same applies to gasoline engines. The "free acceleration" feature is definitely nonsense!

@ D. Sure.

How do you calculate the lambda value? As far as I know, you need fuel mass, the carbon-to-hydrogen ratio, and engine speed for that calculation (residual oxygen is then not needed). When measuring after the catalytic converter, the error would likely be quite high due to the already low values.

I just read a report stating that Peugeot has increased the lifespan of its DPFs to 120,000 km. It was in a Luxembourgish automotive magazine.

ixery

On the other hand, the reduction in sulfur content in diesel fuel also contributes to a decrease in soot emissions. However, I would like to know what this means for 'older' diesel vehicles. When the sulfur content was first reduced, pump manufacturers were very concerned because they feared that their pumps would not be able to handle it.

the pumps also keep breaking down one after another .



Wear problems with sulfur-low diesel fuel.
Compliance with standards is crucial for injection systems.

Bosch research has set a global standard with a reliable method for predicting wear in diesel fuel. / By Klaus Meyer (FV/FLM)
To reduce the harmful components in diesel exhaust, the sulfur content in diesel fuel will be reduced globally in the coming years. Laws and regulations for a phased approach are already in effect. Low-sulfur fuel can cause wear problems in the injection system. In order to protect even the many millions of systems that have already been sold...
To ensure adequate lubrication, diesel fuel must possess good lubricating properties through the use of special additives. Over many years, the Tribology Working Group of the Department of Technical Mechanics at the Research Center on Schillerhöhe, in collaboration with the Diesel Injection Equipment business unit, has developed a testing procedure for the lubricity of diesel fuel, which has now become a globally recognized standard.
Tribology is the study of friction and wear, which can occur as independent phenomena, for example, at the contact point between a roller and a plunger in an injection pump. The term 'lubricity' of a fuel refers to its wear characteristics, which are essential for achieving the required quality and lifespan of components.
Mit der etwa zeitgleichen Einführung von stark entschwefelten Dieselkraftstoffen in Schweden und Kalifornien Anfang der 90er-Jahre, traten bei Verteilereinspritzpumpen aller Hersteller Pumpenausfälle und deutliche Verschlechterungen des Einspritzverhaltens auf. Aus Untersuchungen an Flugturbinenkraftstoffen war bekannt, dass die guten Verschleißeigenschaften von Dieselkraftstoffen mit den Eigenschaften der erst bei höherer Temperatur verdampfenden Anteile zusammenhängen. Es
These are polar chemical compounds whose molecules readily adsorb onto metal surfaces. They reduce friction and wear. However, this was not taken into account when establishing the legal requirements for fuel. Consequently, during the desulfurization of diesel fuels, these polar molecules were also removed, significantly worsening their wear characteristics. Because this problem could recur, it is necessary to ensure the proper functioning of injection systems through a tribological testing method that is valid worldwide.
Before a method could be defined, it was necessary to first analyze the tribologically relevant components in fuel injection pumps and derive the critical wear stress from this analysis. Because establishing a reliable correlation between the behavior of the fuel in the product and in laboratory tests has always been and remains paramount. In particular, the oil industry suggested eliminating this problem through appropriate materials or coatings. However, it was overlooked that all systems already in use worldwide...
approximately 50 million vehicles need to be protected from failure caused by diesel fuel with poor lubricating properties.
For more than six years, methods for evaluating fuels have been investigated, focusing on stress tests that must simulate conditions far exceeding those of a standard pump test or a fleet test with thousands of vehicle accelerations. These goals were developed under the leadership of Bosch in working groups within the international standardization organization ISO, the CEC (a European council for testing lubricants and fuels), and the European Committee for Standardization (CEN), with participation from the oil and additive industries.
Criteria for selecting a testing method include correlation with long-term field tests, short test duration, the ability to differentiate and classify all diesel fuels, a quantifiable wear measurement, suitability for use in refineries for fuel release approval, sufficient reproducibility, and exposure to contact stress during mixing. During mixing, relatively moving components experience both solid contact and...
Fluid friction, within the field of hydrodynamics. The higher the proportion of solid-body contact, the greater the risk of critical wear processes. Conversely, if fluid friction dominates, wear-reducing lubricating films form between the components. In this case, the...
The viscosity of the fuel plays a crucial role. In diesel injection systems lubricated by fuel, solid friction dominates, which must be considered in testing methods. Wear tests that simulate sliding or oscillating movements often use modeling techniques. These tests typically employ test specimens with simple geometries, such as spheres and disks. In measurements independent of the testing machine, wear can be easily quantified after a short period. Unfortunately, the results usually do not correspond to the stresses experienced in actual component contact.
Following extensive studies and international collaborative trials, for which Bosch alone invested several million Deutschmarks, the so-called HFRR method was introduced at the end of 1997 as the CEC method for Europe and as the ISO standard ISO 12156-1 worldwide.
HFFR bedeutet „High Frequency Reciprocating Rig„. Bei dieser Methode gleitet eine festgespannte Kugel unter Belastung über eine Platte schnell hin und her. Beide Prüfkörper sind vollständig von erhitztem Dieselkraftstoff bedeckt. An der Kugel bildet sich eine Verschleißkalotte. Ihre Größe wird als WS1,4-Wert - von englisch wear scar - bezeichnet. Je größer dieser Abtrag ist, umso schlechter ist die Schmierfähigkeit des Dieselkraftstoffs.Diese Methode allein genügt jedoch nicht, den Ausfall von Einspritzsystemen zu verhindern. Ein Grenzwert für die zulässige Schmierfähigkeit und gleichbedeutend das zulässige Verschleißverhalten von Pumpen waren festzulegen: die sogenannte Assessed Pump Wear Rating Number (AWR). Über eine Gewichtung beschreibt sie das Gesamtverschleißverhalten einer Verteilereinspritzpumpe. Ihr
GThe critical value is 3.5. Bosch's competitors defined this parameter in a similar way, allowing for a system-wide assessment.

Based on ring tests and field trials, fuel injection system manufacturers required a laboratory value of WS1.4, with a maximum viscosity of 460 micrometers, to ensure proper lubrication. Multinational oil companies strongly protested this requirement, as it would necessitate adding expensive chemical additives to their fuels to meet the standard. Bosch and its competitors prevailed: This value has been in effect within the European Union since February 1998 and worldwide since October 1998. However, some European countries took nearly two years to implement the regulation. Regular fuel quality checks also reveal the poor quality of diesel fuel in the United States, where the standard is not yet enforced.

With increased performance in existing systems and the introduction of new ones, the requirements for diesel fuel have become more stringent. Therefore, the standardized viscosity now represents only a minimum requirement. Very low-sulfur or sulfur-free diesel fuels will soon dominate even in developing countries.

The management team of the Diesel Injection Technology division has therefore established a task force to identify and assess critical fuel properties early on. In close collaboration with the development departments, the central technical mechanics department is working on new methods, such as mixing sensors, and making a significant contribution to the global definition of the tribological properties of future fuels.

**Racing Against Regulations**
Emission Requirements / By Hermann Grieshaber (K5/EMF3)

The demand for high-quality diesel fuel primarily stems from worldwide emission regulations, which already impose very low pollutant emissions in industrialized countries and will become even more stringent. Developing countries will follow suit with their laws approximately every five years.

Engine and vehicle manufacturers are developing engines with reduced emissions and vehicles that consume less fuel. Fuel injection equipment manufacturers are developing high-pressure injection systems with increased performance. To achieve this, the petroleum industry must supply diesel fuel of high quality. The criteria include a high cetane number (describing ignition quality), density and viscosity with low variability, a distillation curve with a low boiling point, a low aromatic content, and a low sulfur content or sulfur-free status, defined as a maximum of ten parts per million (ppm) of sulfur. For long service life and consistent function of the injection systems, good lubricity, no free water, and a low level of contaminants are also important.

Most of these criteria are specified in the European Union's diesel fuel standard EN 590 and are generally met. What is still lacking is a regulation for the introduction of sulfur-free diesel fuel. So far, only the introduction of diesel fuel with a maximum of 50 ppm of sulfur in 2005 has been decided. However, this is too high for most exhaust aftertreatment systems.

For other reasons as well, a sustainable reduction in the sulfur content from today's up to 350 ppm in the EU is desirable. Approximately 98 percent of the sulfur is emitted as sulfur dioxide, which contributes to acid rain, affecting plant growth. Without a catalyst, approximately two percent of the sulfur is emitted as sulfate particles, and significantly more with a catalyst and high exhaust temperatures. By reducing the sulfur content from previously 1500 ppm to 500 ppm, Germany has already reduced sulfur dioxide emissions by approximately 40,000 tons per year and sulfate particle emissions by approximately 3,000 tons per year.

The emission regulations have led to a reduction of approximately twelve percent in the main pollutants (nitrogen oxides, hydrocarbons, and particles) within 15 years compared to Euro 1 standards from 1992. The Euro-5 limits and their implementation dates are currently being discussed. The Euro 4 level can be achieved in 2005 for small and medium-sized passenger cars without exhaust aftertreatment. However, for Euro 5 and the California LEV 2 (low emission vehicle) standard, which will apply to approximately 25 percent of new vehicles in 2004, particulate filters or nitrogen oxide catalysts, or both, are required. The particulate filter could be, for example, a continuously regenerating separator in which carbon particles react with nitrogen dioxide and are converted into carbon dioxide, forming nitrogen monoxide. Since both the particulate filter and the NOx storage catalyst rely on catalytic action, vehicles equipped with these systems must operate on sulfur-free diesel fuel. Otherwise, instead of nitrogen oxide conversions, undesirable reactions would occur, leading to the formation of sulfur compounds, which would partially or completely 'poison' the catalyst and render it inoperable for the required exhaust aftertreatment.inThe limit value is 3.5. Competitors of Bosch defined this parameter in a similar way. This allows for a cross-system evaluation.Based on ring tests and field trials, injection system manufacturers demanded a laboratory value of WS1.4, with a maximum of 460 micrometers, for lubricity. This was strongly protested by multinational oil companies, as they had to add chemical additives to their fuels at considerable cost to achieve this. Bosch and its competitors prevailed: Since February 1998, this value has been in effect in the European Union, and since October 1998, worldwide. However, some European countries took almost two years to implement the standard. Regular fuel monitoring also reveals the poor...Quality of diesel fuels in the United States, where the standard has not yet been met.With the performance enhancements of existing systems and the introduction of new ones, the...Requirements for diesel fuel are becoming stricter. Therefore, the standardized lubricating properties now represent only a minimum requirement. Very low-sulfur or sulfur-free diesel fuels will soon dominate even in developing countries.The management team of the Diesel Injection Technology division has therefore established a task force to identify and evaluate critical fuel properties at an early stage. In close collaboration with the development departments, the Central Technical Mechanics department is working on new methods, such as mixing friction sensors, and making a significant contribution to the global definition of the tribological properties of future fuels.Racing against the law.Emission regulations / By Hermann Grieshaber (K5/EMF3)The demand for high-quality diesel fuel primarily stems from global emission regulations, which already mandate very low levels of pollutant emissions in industrialized countries and will become even stricter in the future. 'Emerging' or 'developing' countries will also gradually adopt similar legislation, roughly every five years, mirroring the standards set by industrialized nations.Engine and vehicle manufacturers are developing engines with low emissions and vehicles that offer good fuel efficiency. Manufacturers of injection systems are developing high-performance high-pressure injection systems. To achieve this, the mineral oil industry must supply diesel fuel of high quality. The criteria include a high cetane number (which describes ignition quality), density, and viscosity with minimal variation.A boiling point range with a low maximum value, a low aromatic content, and a low sulfur content or sulfur-free composition (defined as a maximum of ten parts per million (ppm) of sulfur) are important. Furthermore, good lubricity, the absence of free water, and a low level of contaminants are also crucial for ensuring a long service life and consistent performance of the injection systems.Most of these criteria are defined in the European Union's diesel fuel standard EN 590 and are generally met. What is still lacking is a regulation for the introduction of sulfur-free diesel fuel. So far, only a decision has been made to introduce diesel fuel with a maximum of 50 ppm of sulfur in 2005. However, this is too much for most exhaust aftertreatment systems.For various reasons, a sustainable reduction of the sulfur content from today's levels to up to 350 ppm in the EU is desirable. Approximately 98 percent of the sulfur is emitted as sulfur dioxide.This contributes to the formation of acid rain, which impairs plant growth. Without a catalyst, approximately two percent of the sulfur is emitted as sulfate particles; with a catalyst and high exhaust temperatures, significantly more is released. By reducing the sulfur content from 1,500 ppm to 500 ppm, Germany has already reduced sulfur dioxide emissions by approximately 40,000 tons per year.Emitted 3,000 tons less of sulfate particles.The emission regulations have resulted in a reduction of the main pollutants, nitrogen oxides, hydrocarbons, and particulate matter, by approximately twelve percent and six percent respectively, compared to the Euro 1 standards of 1992. The Euro 5 limits and their implementation date are currently still under discussion. The Euro 4 standard was introduced in 2005 for small and medium-sized passenger cars without...To achieve exhaust aftertreatment, while Euro 5 and the California border value require a LEV 2 (low emission vehicle, level 2) standard, which will apply to an average of 25 percent of new vehicles starting in 2004. This requires either a particulate filter or a nitrogen oxide catalyst, or even both. The particulate filter could, for example, be a continuously regenerating separator in which the carbon particles react with nitrogen dioxide, thereby converting them into carbon dioxide and forming nitrogen monoxide.The particulate filter and the NOx storage catalyst both rely on catalytic action, so vehicles equipped with these components must be operated using sulfur-free diesel fuel. Otherwise, instead of the desired NOx conversion reactions, undesirable reactions would occur that produce sulfur compounds, which would partially or completely 'poison' the catalyst, rendering it ineffective for its intended exhaust gas treatment function.CU Gremlin.