In part 2 of the cyclone blog you can read about the early days of the cyclone, about the largest ever MANN+HUMMEL cyclone, about typical truck and industrial applications and future developments.

The principle of the cyclone was already used in Germany in the early 1920s as shown by the development of a cyclone air cleaner for combustion engines by the Delbag company. In the 1940s MANN+HUMMEL started the development of a cyclone pre-separator based on a system from Professor Feifel, which some years later was also used in connection with felt air filters in combination air cleaners.

In the 1960s: combination of cyclone preliminary stage with paper fine filter

In the 1960s MANN+HUMMEL directed attention to the combination of a cyclone preliminary stage and paper fine filters downstream for commercial vehicles and other diesel engines. Already then the purpose of the cyclone as a pre-separator was to lengthen the service interval of the filter insert. At that time there were three design types available for different application conditions:

  • Single-stage air cleaner without cyclone
  • Combination air cleaner with a cased cyclone. Here the flow rotates between the filter element and external casing
  • Combination air cleaner with small, highly effective cyclone cells for extremely heavy dust conditions

The MANN manual on filter technology of 1962 includes a diagram of the “MANN Pico cyclone combination filter type 45”, where a multi-cyclone is combined with a filter element in a metal housing – possibly one of the first multi-cyclones from MANN+HUMMEL. 1967 was the premiere of the MANN Piclon, a dry air cleaner with a cased cyclone at the Frankfurt motor show.

In industrial applications, in addition to the cased cyclones of the Piclon series, multi-cyclone blocks are primarily used. For example, Iqoron 7 from 2003 was the first plastic multi-cyclone on the market, which was produced in one piece in an injection moulding process. Construction and agricultural machines, railway locomotives and military applications are typical application areas for the combination filter. A separation efficiency of up to 99% is achieved.

Iqoron 7 from 2003. The first one-piece plastic multi-cyclone

Iqoron 7 from 2003. The first one-piece plastic multi-cyclone

The largest multi-cyclone produced up to now by MANN+HUMMEL was developed in 2015 for Siemens railway locomotives in the USA. The cyclone wall in the inside of the locomotive consists of 684 parallel cyclone cells which clean 516 cubic metres of air every minute – roughly the volume of two four-room apartments.

Cyclone for a Siemens railway locomotive in the USA. 684 cyclone cells clean up to 516 cubic metres of air every minute

Cyclone for a Siemens railway locomotive in the USA. 684 cyclone cells clean up to 516 cubic metres of air every minute

Mercedes Benz tandem air cleaner

One of the first cyclones which MANN+HUMMEL developed in plastic is the Mercedes Benz tandem air cleaner. The preferred design is the pipe cyclone. Instead of many small cyclones the design makes do with one or two pipe cyclones which are more robust than mini‑cyclones. The small cyclones, however, are easy to integrate in a compact housing when space behind the driver’s cabin is tight.

Record for Trucks: 36 kg dust holding capacity

The tandem air cleaner which MANN+HUMMEL has delivered to Mercedes Benz since 2003 is a highly efficient solution. The air cleaner has two filter elements on board and two pipe cyclones at the top. The pipe cyclone had already been developed in 1996 for the filter produced before it. Together they manage a dust capacity of 36 kg. That still holds the record for truck applications. The cyclone already accounts for 30 kg of this mass. That means this amount is already separated before the air reaches the filter element. The two filter elements then retain a further six kilos before it is necessary to replace the elements. The cyclone itself is maintenance-free and continues to function without replacement and without maintenance.

Dual cyclone on a tandem air cleaner for construction sites and mining operations

Dual cyclone on a tandem air cleaner for construction sites and mining operations

No chance for coarse dust

The current pipe cyclone is a particularly successful development for the truck world. It separates 85% of the coarse dust and only causes a pressure drop of 5 to 6 millibars (see part 1 of this blog). We have fitted two of these advanced cyclones in the intake system of a new application.

Trends with industrial filters

In future in industrial applications the trend will be towards a further increase in the separation efficiency of cyclone cells and cased cyclones. Multi-stage cyclones will become more common with oval instead of round designs. Cabin air cleaners for agricultural machines are an example of a new application area. Ultimately there will be even more specific developments for each application, e.g. new cyclone cells for railway locomotives with an even lower pressure drop.