[SystemSafety] The VW Saga

Mike Ellims michael.ellims at tesco.net
Mon Oct 12 13:10:20 CEST 2015


> I assume that VW are expert at making diesel engines. So are other
companies. I expect that all engine manufacturers
> routinely examine competitors' engines extremely carefully and learn from
what they find.
> So it must be difficult to achieve far better performance than your
competitors unless you have patent protection for some breakthrough.

Companies share engines quite widely e.g. Peugeot specializes in small
engines which as (or at least where) used by Ford in Europe. Manufactures
share "platforms" as well, for example I think that the current Ford Fiesta
is basically a Fiat Punto in drag, it's also done widely within companies
e.g. the Audi TT is basically a VW Golf. They more or less all have a pretty
good knolage about what each other is doing; but not perfect knowledge.

The problem with diesel and to a lesser extent petrol engines is that what
you get out of the tailpipe is a strong function of the combustion
temperature. In a nutshell high combustion temperatures give you, low
hydrocarbon & particulate emissions but good fuel economy and high NOx
output. To lower the NOx output you have to lower the combustions
temperature which means that other emissions and fuel economy get worse. The
peak points for all everything are of course all in different places...
making for an interesting optimization problem. Then there is the issue that
the load and speed are continuously changing.

It's of course much more complex than that and also depends on injection
pressure, injection timing, number of injections per firing (3/firing is
common), cylinder temperature, fuel mixing (swirl) which in turn depends on
the inlet ports and shape of the piston and head etc. etc. etc.

Various techniques are also used to tailor the combustion environment e.g.
ERG feeds CO2 back into the cylinder to drop peak temperature, adding
ethanol to petrol makes and extra oxygen atom available. Demand management
is also used, e.g. when loads are high the air condition pump and the
alternator are turned off for short periods. When all else fails external
equipment can be added e.g. catalectic converts and particulate trap. All of
which adds complexity and cost.

>From a technology perspective the basic problem is that it gets harder and
harder to make the next set of improvements required by the regulators
expect that the regulators make it easier than it could be to pass the
tests, in that they have specific drive cycles that engines can be optimized
for.

> It seems that one (at least) of VW's engines was very much worse in
emissions than the regulations allowed.
> None of their competitors have been caught yet with the same problem.

All the information at the moment seems to point to the fact that many
(most?) of the vehicles tested on the road do worse than the regulations
allow e.g. four times the NOx allowed which isn't surprising given that the
engine only has to meet the regulation drive cycles. However VW were caught
with their pants down in they added a "defeat device" i.e. a hack to
specifically defeat the test procedure in the USA. 

> So, do all the competitors have some patented technology that gives them a
huge advantage?

No single major advantage, lots of small advantages put together and
optimized in company specific ways to produce a package.


-----Original Message-----
From: systemsafety-bounces at lists.techfak.uni-bielefeld.de
[mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de] On Behalf Of
Martyn Thomas
Sent: 12 October 2015 10:07
To: systemsafety at lists.techfak.uni-bielefeld.de
Subject: Re: [SystemSafety] The VW Saga


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Hash: SHA512

I assume that VW are expert at making diesel engines. So are other
companies. I expect that all engine manufacturers routinely examine
comtetitors' engines extremely carefully and learn from what they find.
So it must be difficult to achieve far better performance than your
competitors unless you have patent protection for some breakthrough.

It seems that one (at least) of VW's engines was very much worse in
emissions than the regulations allowed.

None of their competitors have been caught yet with the same problem.

So, do all the competitors have some patented technology that gives them a
huge advantage?

Martyn


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