Development of new filter elements and backflushing method led to a new technology even for these types of engines. Multipass tests do show that an 18 micron mesh has the same retention rate of solids as the paper filter elements in use. BOLL & KIRCH developed a backflushing method which is capable to flush this type of fine mesh. Using fabric or wire mesh brings an additional advantage. It limits the max. particle size which can get to the bearings down to 73 % of that of a paper element. The oil system for high speed engines includes a centrifugal filter and a fine filter which is installed close to the bearings oil supply. The Concept 2000 will replace the paper filter by an automatic filter which may have a sludge checker in the flushing line as an option. The sludge checker prevents solids from the initial engine start to circulate multiply. The automatic backflushing filter which can be used for this size of engine is of the same type as it is used for the medium speed 4-stroke engines operating at MDO, H.F.O and gas, even the system layout is identical. There are two major differences:
The automatic filter has to be mounted directly onto the engine to save assembly costs. The design of these filters face special requirements for cost and technical reasons.
・The target cost must be close to the paper filter solution.
・The design must integrate additional functions to save system costs.
・All components must withstand the vibration on the engine.
・The requirement of the classification has to be fulfilled.
・Servicing must be as easy as a duplex filter.
The common size of an engine for this type of filter is up to a bore size of 40 - 50 cm.
Automatic filter with continuous backflushing
The automatic filter has a new backflushing process. In addition to the state-of-the-art the reverse flow is combined with a cross flow. The cross flow takes place from the top of the candle down to the drain connection. Candle filters have the problem that with the extended length of the elements the reverse flow keeps only 1/3 of the lower part of the candle clean. The cross flow by an injection orifice at the top of the candle improves the surface flushing as well as the reverse flow in the upper end of the candle.
An investigation on candles afier some thousand operating hours shows a significant larger unblocked filter area.
