Dr. Manfred Duernholz, Joint Managing Director, Bosch Ltd.

Bosch already has a common-rail diesel injection system for cars on the market. How would you explain the enduring popularity of your mechanical inline pumps in the CV industry?
It’s very simple — our A inline pump is extremely robust and simple to maintain. We also have high-end inline pumps, the P-type, for real heavy-duty applications. You can now exchange the A for a P, which we have to do in the one or the other case, but what are the volumes? I have my strong doubts. And this is not only true for India. It is true for China, it is also true for Brazil and other markets. The situation is simply different. And therefore a mechanical system, even if you have to make some compromises, for example in power output, surely not in driveability, is not a bad idea for these kinds of markets, not to say a good idea. Cummins, for example, has taken more or less the same view.

Do you plan to introduce a common-rail fuel system for trucks soon?
Bosch India has built a special common-rail for trucks which are not in the highest power range — something lower than 25kW per litre. This corresponds to the typical Indian truck engine with swept volume of one litre per cylinder. This fuel injection system will have pressures between 1400 and 1600 bar. We have the first prototypes running, and I’m personally convinced this system will find its way back to our home market in Europe. Not for the highest-end products, but at least for the volume market. At the moment I’m sure people don’t want to discuss this in Europe. But once they see Indian truck OEMs do here similar things to what has been accomplished with the Nano, they will no longer think it is a stupid thing, that they do not in every case need 1800 bar or 2000 bar. Surely higher pressure helps, always. But high pressure doesn’t come for free; you have to pay for it.

How then will you meet the emission norms in Europe with such a system? We are talking about Euro 5…
Here we are talking at the moment of BS4. I don’t want to say we are doing it easily. But we could demonstrate to one customer on two engines, with a 1400 bar system and an open particulate filter, that we could meet BS4 with reasonable specific power output. And that is the important thing here. This is an engine which is not a high-end engine. It’s a typical Indian engine, only two valves per cylinder, with only a limited peak pressure capability. So the OEM can simply take its BS3 engine, make some modifications on the charging side and in the combustion, and using our support with this value-engineered common-rail system and an open filter, have a BS4 solution.

What kind of additional cost would this entail?
Our target is that this common-rail, at least for a six-cylinder engine, stays in the same price range as an electronic distributor pump. An electronic distributor pump is more expensive than a mechanical pump, that’s clear, but that is the target. We aren’t there yet, but we are fighting to get there. I would say that with this system we have translated our Nano knowhow to trucks.

Bosch was responsible for developing a number of high-pressure fuel injection systems, including common-rail. Are these purely tech-driven, or in response to customer requirements?
My team and I, we try to develop for the needs of the market. Therefore we have to have some knowledge also on the engine side. It’s no longer the case that Bosch simply develops an injection system and sells it to the market, the market takes it and puts it onto an engine, and the engine is fine. You have to develop engine and injection system in parallel; otherwise you don’t end up with the best solution. And to do so, as an injection systems supplier you have to have a certain knowledge also of engines. For example, you know, if your engine doesn’t have a relatively high peak firing pressure capability, you cannot use – at least in a meaningful way – 2000 bar. You can use it, but you’re not getting value for your money. Only if you increase boost pressure and peak firing pressure increase can you also use also high injection pressure. As an injection systems supplier, you have to know these simple boundary conditions.

Have you worked in collaboration with any particular truck or engine manufacturer?
All of them. We worked with MAN to develop the common-rail for heavy duty application.

Why is it now that everybody is moving to common-rail? Volvo still has unit injectors but Daimler is moving to common-rail. What are the advantages in a heavy duty environment?
There are quite big arguments for both. First of all, and that makes the story a little difficult, you always have quite a lot of experienced people in different companies. And in addition, each company has its own technology philosophy. For example, for a long time Volkswagen used unit injectors in its passenger car diesel engines. And that was okay, by the way. They were a good, robust product. But there were also some strong arguments against unit injectors — for example combustion noise, vibration, and harshness that couldn’t compare to the refinement of a common-rail. On the other hand, VW was the first carmaker that could meet the Euro 4 norm without a particulate filter. It was a good engine, but it was a little noisy, so they had to switch to common-rail. They had to give up some positive things to improve for example on the noise. And that is the simplest thing on the truck side. You have lots of arguments in favour of either technology, but my personal opinion is that, if you are thinking in terms of using aftertreatment, especially a closed particulate filter – as all who want to go to the US have to do, – I think you have a big advantage with the common-rail because of its flexibility. If you don’t have this step, you can still survive with one system or the other, but it will be very, very difficult. So while I cannot say that common-rail is the only way, surely with respect to acoustics – and this is becoming more and more important – it does have distinct advantages.

But on the heavy duty side? Acoustics is not the most important criterion there…
Acoustics is also an argument. In addition, that was especially for my Indian customers a long time ago a difficult issue for BS3, where you normally don’t have exhaust gas recirculation. With cam-driven systems, for example, like a distributor pump or an A pump, or a PF pump, where a cam drives a plunger, you normally have an injection rate that begins smoothly and then the pressure rises. This kind of injection rate is the right way to go with respect to NOx emission control especially. The injection rate of a common-rail – and we are talking about BS3 – where you have a high pressure and near instantaneous opening and closing of the nozzles, is good for particulates, but not so positive for NOx. That is the situation without EGR for BS3.Again, this is not black and white. You can change this injection rate of common-rail again with pilot injection to come near to the cam-driven system and you can reach the same results, but simply spoken a cam-driven characteristic is simply a good one. And now, for BS4, you add EGR. And then, in an EGR atmosphere in the combustion chamber, all of a sudden the injection rate of a common-rail is better. Because there is less oxygen in the combustion chamber, and then the injection rate is no longer dominant. Here the injection pressure, and the particulate-reduction potential, of common-rail is better and therefore, because more or less all of them are doing now EGR, the higher pressure especially in part load gives you benefits. <\br><\br>I’ve been in this business now for 25 years, and I remember when we first talked to European truck customers 20 years ago about EGR, they did not accept it. They simply told us it was not possible because it would lower the durability of the engine. This has changed completely in the so-called modern world. And that is an argument – with aftertreatment and EGR – for common-rail.

But nowadays truck customers in Europe seem to be moving more towards Selective Catalytic Reduction. Is that solution, in which you reduce NOx in the aftertreatment, a simpler solution from the engine architecture perspective?
Yes and no. If you have a modern European high-end Euro 3 or BS3 engine, all of these more or less are electronically governed four-valve engines which can be tuned with combustion measures and with injection system measures to lowest particulates so that you fulfill BS4 particulate-wise, not NOx-wise. And the NOx you can reduce via SCR. So yes, you can take these high-end engines, and meet BS4 and even BS5 with SCR. And you can do this because you tune the engine for higher NOx, with better fuel consumption.But you have to keep in mind that for the SCR solution you need a urea distribution infrastructure. This was the subject of a long, long debate in Europe. And in the meantime, the bigger fleets have found a solution. The fuel consumption advantage is a pro, especially considering the Maut, the emissions-level-dependent motorway tolls we have in Germany. SCR was more or less the only solution to have an early fulfillment of this. And in spite of the fact that an SCR system for a modern truck is an expensive thing – a few thousand euros for the whole system, catalysts and all, – it pays off, because of the fuel consumption advantage. What is necessary is that the engine is capable of meeting the particulate levels.

Which do you see is the better path to BS4 — in-engine measures using your common-rail system and EGR, or the Denoxtronic SCR system?
We have both. Again, it is up to our customer to decide. I would like to answer this in a simple way. If the customer here has an engine similar to European standard or even better – and we have customers that are developing completely new engines, – they can go this way (SCR) if they want. If you have an older engine, an existing BS3 engine with two valves, you want to stay with – and maybe that is not a wrong decision, but that’s not up to me to decide – then an EGR and open filter solution in my opinion is the better way.My point is, that is our vision. I feel a mechanical system, especially with the inline pump, because of its robustness, would be a good product and a good system for this market. We developed quite a lot for BS4 for common-rail on the combustion side, we took the filter, we took the charging into account, and we could demonstrate two engines that fulfil the BS4 norm. If we take this knowledge, on the combustion side especially, and on the air side, and marry this knowledge with a mechanical pump, then BS3 is feasible. Cummins, for example, is doing it with a Bosch VP14 mechanical distributor pump.

Do you see this pump continuing to be used into BS4 or will you have to go common-rail in India?
The first thing I had to learn in my life was, to never say never. Honestly, if years ago we had discussed a mechanical system for BS3 you would also have heard ‘never’. But now we have it. And if we discussed BS4 with 1400 bar common-rail, you would also hear ‘never’, and now we have it. So I want to be careful. But let me put it this way: reasonable power output and BS3, with different types of mechanical systems, is our next goal. The following step, BS4 for the volume market, is a value common-rail system because of EGR. Maybe one or the other would try, let us think aloud, an aftertreatment and a mechanical pump for BS4 also — with reduced power output, for example. But that is a little far away at the moment. My personal opinion is that the value common-rail system at 1400 or 1600 bar, with EGR and open filter, is the volume solution for this market.

Which of the two options available to reduce NOx – EGR in the engine or SCR in the aftertreatment – do you see a preference for in this market?
I would answer it this way. We have seen different phases. Two or three years ago, the decision of one of the biggest was very clear: only SCR, because of the fuel consumption advantage. If you take this view and say, in principle I do not change anything to my engine, I only adopt an SCR system, then the question that arises is that of infrastructure, and of whether my engine is really able to do BS4 particulate-wise. Does this mean I have to redesign my engine to higher peak pressures, but in that case I have a new engine? Is my end-customer happy with refilling? Is that really the best solution? So there are many questions, and in the meantime I think everybody is discussing everything and also trying out everything.

Wouldn’t higher peak firing pressures necessitate a stronger engine block?
The engine has to have the capability that if I simply retune it to higher NOx levels, it has to react with very low particulates — so low that the particulates are lower than the BS4 values. If that is not the case – and for some of the engines here in India it is not the case, without major changes – then you need in addition to the SCR system an open filter. But then the system is really expensive. In this case I would prefer only an open filter and EGR, despite the fact that fuel consumption is not as good. So you see, there is no black and white. And you really have to look deep, to your production line, to your production, to the capability of your engine, and all these things, and then decide what is the best for your customers and for your segment in which your sell your trucks. Bosch builds solutions for both, but it’s my private opinion that EGR will be the dominant solution at BS4.

In that environment, what will Bosch’s contribution be?
The 1400/1600 bar common-rail. You can get higher pressures also, but then you have the typical European truck system.

Is Bosch working on a mechanical solution for BS4 as well? What would it take to meet that norm with a purely mechanical fuel injection system?
I’ll give you another example, it’s nothing to do with trucks. You have here this three-wheeler market. And you have a four-wheeler in development, comparable to three-wheelers but with four wheels. Both approaches are smaller than Ace and really low-cost approaches. These will normally have a single-cylinder engine, because it has to be cheap. Up until now you have a mechanical injection system, the PF pump and injector. It is a very robust and also price-wise very interesting system. Now these vehicles, especially the four-wheelers, have to fulfil BS4 norms in future. This would mean that if we think black and white, it is not feasible with a single-cylinder engine. Even not with common-rail because air is missing. This would mean you would not have this segment in the future at BS4.But if the pressure is sufficiently high, people will begin to think about what they can do with a single-cylinder to make it BS4-compliant. And in this atmosphere, people will be willing to think about upsizing the engine, for example. Nobody would think in this direction before this. Or in terms of reducing specific power output to values nobody would accept before, only to keep it a single cylinder.What I want to say is that the pressure and the pain has to be high and then the community is willing to think about compromises. And that is the same also in 2010 and 2014, when BS4 will come in for trucks. And then, I promise, we will find, together with our customers, solutions people at the moment would call stupid.For example, perhaps also a mechanical system for trucks with BS4. Why not? But at the moment if I go to my customer and tell him, not 15 kW but let us think about 10 kW a litre, he would throw me out. Nobody would buy that. But if the pain is big enough and if they see the alternative is a few thousand euros for this and aftertreatment for that, and electronics for that — they will be willing to think, and for this we have to be prepared. And this is what we are doing.

But OEMs typically want to downsize, with smaller engines producing higher outputs. What you are suggesting is counter to that?
That’s clear. If I were free to design a new, smaller engine with high peak pressure, high turbocharger boost, maybe two turbochargers, that would be great. This is technically the right way. This is exactly what is happening in Europe. Some are also doing this in India. But somebody has to pay for this. I personally doubt – and for this I had to come here and see what is going on here and to discuss with a lot of customers – that that is the volume way for India. You will see it here, but not in volumes. All OEMs are proud to develop high-end engines, but what happens as soon as the end customer realises that those engines are going to cost more than he is used to paying? The willingness to pay for this, even for some benefits, really is limited. And then the OEM says, can’t I stay with my old engine? I can immediately give you 10 examples. And this is a market we cannot neglect.