ThyssenKrupp Magazin

30 ASSEMBLED CAMSHAFTS
To anyone who says he doesn’t have to deal with the camshaft,
you can only agree: you’re right! But it would be worth your while
nonetheless. Because in recent years much has happened regarding
this component so important in combustion engines. Right up
with the leaders is the company ThyssenKrupp Presta. In just a few
short years it has earned itself a good reputation with the manufacturing
of “assembled camshafts” – very precisely purpose-built components
that are now an indispensable feature of modern engine
manufacturing.
There is a camshaft working away in practically every vehicle with
a combustion engine. Four-stroke petrol and diesel aggregates need
them like the air to breathe, otherwise the fuel-oxygen mixture would
not reach the combustion chamber nor would the exhaust gases get
out. Only clattering two-strokes do without such a precisely manufactured
gem in their housings.
If you ask drivers about their desires regarding the modern vehicle,
two answers are heard well ahead of all others: the car should be
economical and ecological. In addition to all the factors that play a role
here, naturally the engine is of great significance: if its consumption is
low, the owner is happy. The advances in engine technology in recent
years have been immense – diesel and petrol direct injection are just
two major catchwords that broadly describe what has happened in and
around the combustion chambers. And the around part includes the
camshaft. Because all elements of an engine work as a team to ensure
that the entire engine runs even more precisely and efficiently and that
the fuel is better utilized. A combustion engine works like this: a gas-air
mixture is conducted into a round space, the cylinder. This is closed off
Breathing with the shaft
ThyssenKrupp Presta supplies a specialty
for modern engines: assembled camshafts
By Rüdiger Abele | Photo Andreas Böttcher
on one side by a movable damper, the piston. When the gas is ignited,
it expands suddenly and pushes the piston away, whose sliding movement
is transformed by a mechanism into a revolution of the crankshaft,
which in turn is conducted to the wheels. The vehicle moves. The combusted
gas mixture is conducted out of the cylinder through another
valve. The camshaft comes into effect at the valves: in the rhythm of the
engine it controls the opening of the valves: open – mixture in; closed –
exhaust out. You thus need at least two valves per cylinder, but for better
combustion e.g. four valves have long since established themselves
(“Four-Valve”). Because a car engine, for instance, seldom only has
one cylinder, but rather in most cases four, it has four valves which need
to be controlled, in a corresponding six cylinder engine there are 24 already
– the calculation could be carried on accordingly.
WELDED STEEL MEETS PRECISION STEEL
Back to the camshaft: it consists of a tube on which the cams are fixed,
whose shape is similar to a longitudinally cut chicken egg. It rotates
continuously over the push rod; at its highest point it pushes the valve
shut, at all other points of its rotational path it is slightly to completely
open and lets the cylinder breathe. For every combustion chamber, at
least one cam is responsible for two valves and ensures incoming and
outgoing air. For better control, these days two camshafts per engine
have already become widespread (one for the input and one for the output
valves) and some aggregates already have four shafts.
“Of course we are delighted at the increasing numbers,” says
Hermann Weissenhorn, the divisional manager responsible for
camshafts at ThyssenKrupp Presta. Particularly as their specialty, the
TK Magazine | 1 | 2004 |