Optimizing the Cylinder Running Surface / Piston System of Internal Combustion Engines Towards Lower Emissions 2012-32-0092
Rising fuel prices and more stringent vehicle emissions
requirements are increasing the pressure on engine manufacturers to
utilize technologies to increase efficiency and reduce emissions.
As a result, interest in cylinder surface coatings has risen
considerably in the past few years. Among these are SUMEBore®
coatings from Sulzer Metco. These coatings are applied by a
powder-based air plasma spray (APS) process. The APS process is
very flexible, and can process materials which wire-based methods
cannot, particularly metal matrix composites and pure ceramics.
Applications range from small 2-stroke engines, motorcycles, and
lightweight passenger car engines, up to high-speed diesel truck
engines and medium-speed diesel engines.
The compositions of the coatings can be tailored to the specific
challenges in an engine, e.g., excessive abrasive wear, scuffing,
corrosion caused by adulterated fuel, improved heat transfer from
the combustion chamber into the water jacket, etc. A number of
engines have been tested successfully. Most of them exhibited
significant reductions in lube oil consumption (LOC), reduced fuel
consumption, very low wear rates and corrosion resistance on the
liner surfaces. This coating solution has been commercialized in
various markets. It has proven to be suitable for mass production
on both new engine blocks and liners, and for repair of worn-out
parts. Such coatings will continue to play an important role when
it comes to reductions of weight and emissions in internal
combustion engines. An example of such a coating solution will be
outlined. It has been carried out in collaboration with BRP
Powertrain in Austria on a 1.5L 3-cylinder aluminum engine and
together with the adjustment of the ring package and the piston a
reduction of 35% in LOC was achieved. This engine will go into
production in September 2012 with limited numbers coated in the
Sulzer Metco Wohlen facility in Switzerland, until an engineered
coating system is ready on site to start large series production.
More details on the engine performance and design changes made to
the cast aluminum block in order to take full advantage of the
coating on the cylinder running surfaces is presented in the paper
from Zorn et al.