Cabin air filter
Cabin air filter , also under the names of indoor or pollen filter known to be in air conditioning systems used by vehicles. These filters were developed in the late 1970s, were able to establish themselves in the 1990s and are now standard equipment in modern vehicles. Combination filters, consisting of a textile filter and adsorbent , have been used in the automotive sector since the mid-1990s ; it was used earlier in the agricultural sector.
Basics
When this filter class was launched on the market, two German companies in particular (besides the inventor Saab Automobile ) stood out. The Freudenberg company was a pioneer in the field of pure particle and pollen filters, and Mann + Hummel interior filters GmbH (formerly helsa-automotive GmbH) was in charge of the development and market launch of the combination filter (for the simultaneous separation of harmful gases). Other important manufacturers of cabin air filters are the companies Hengst , 3M and Mahle .
Market information
Even if cabin air filters have only been around for around 30 years, this product has already achieved enormous economic importance. Almost all new vehicles in Europe are equipped with a cabin air filter and 21 million vehicles are manufactured in this region. Over 44 million cars and light trucks are manufactured in Asia, North and South America, although the number of cabin air filters is lower there. The OEM market for cabin air filters is therefore currently valued at just under 50 million filters. If you add the OES and IAM requirements in addition to the OEM quantities , the global market for cabin air filters is likely to be over 200 million filters a year.
Manufacturing / technology
A cabin air filter usually consists of a pleated (folded) filter medium and a frame. In the case of a pure particle filter, the filter medium consists of synthetic melt-blown fleece , which is able to filter dust thanks to its electrostatic properties. Thanks to its integrated layer of activated carbon, the combination filter can filter not only dust and particles but also odors and harmful gases. The combination filter therefore offers greater convenience.
As a rule, two variants are preferred for the frame. One of these two solutions is an injection-molded frame made of plastic, whereby the medium can be injected directly or hooked into a plastic frame as a pre-formed filter insert. The textile frame, in which the pleated filter medium is held in shape with hotmelt and a narrow circumferential strip of fleece, is in many cases the more cost-effective and elegant solution for filter shaping. The efficiency of a cabin filter is adjusted by the choice of media, media area and fold geometry. This adaptability is important because the automobile manufacturers set varying priorities in the requirements. Only a few well-known filter manufacturers succeed in presenting an ideal compromise to the OEM in all cases. A combination filter is defined by 4 classic properties:
These four core properties of a combination filter influence each other, which makes the difficulty of finding an inexpensive solution understandable.
At the global motor shows and trade fairs in 2014/15, a trend towards functional coatings on cabin filters was noted. Filter manufacturers try to give the filter an even better effect by using, for example, "anti-allergenic" or "antimicrobial" coatings. This extends the range of effectiveness and the comfort character of modern cabin filters. It will be very interesting to see whether these trends continue and prevail. At Volkswagen, an allergenic filter option is already available as part of a so-called 3-zone air conditioning system.
Effect / handling / benefit
A high-quality cabin filter is able to remove or reduce almost all types of pollutants from the air. Especially in extreme weather conditions ( winter smog , summer smog ), during the pollen season , in heavy traffic, in tunnels, in sections with construction site operations or in traffic jams , the air contains a lot of impurities and it is precisely then that a cabin filter shows its full effect against aerosols and gases. Even in the situations mentioned, the cabin filter allows comfortable travel.
However, the efficiency of a cabin air filter deteriorates over time. As the dust load increases, the filter slowly becomes clogged and the so-called filter cake is formed . The consequences of this are:
- The pressure drop increases and less air is conveyed.
- As the load increases, the particle filter fleece loses its electrostatic properties and thus its dust filter performance.
- Due to the exhaust gas loading of the combination filter, its gas filtration and pollutant reduction are weaker.
- Heavily loaded filters become a burden for people and air conditioning in the long run.
For the reasons mentioned, it is important to change the filter regularly. The manufacturer's specifications in the service booklet differ here.
application
New vehicles of any kind are either fitted with a cabin filter as standard or can be optionally equipped with one. The spectrum ranges from cars , light trucks , trucks , construction machinery , agricultural machinery to special vehicles. The filters not only differ between the vehicle classes, but with almost every model series from a manufacturer there is also a different filter and then the workshop or the consumer still has the choice between a pure particle filter or a combination filter. The number of different cabin filters is over 500.
For a few years now, there has been a trend among car manufacturers towards ever larger platforms, which also means that a filter model can be used for more and more vehicles. Of course, this trend does not affect the fleet that is already in operation, which comprises more than 600 million vehicles.
literature
- Hans-Hermann Braess, Ulrich Seiffert: Vieweg manual automotive technology. 2nd Edition. Friedrich Vieweg Verlag, Braunschweig / Wiesbaden 2001, ISBN 3-528-13114-4
- Karl-Heinz Dietsche, Thomas Jäger, Robert Bosch GmbH: Automotive pocket book. 25th edition. Friedr. Vieweg & Sohn Verlag, Wiesbaden 2003, ISBN 3-528-23876-3
Individual evidence
- ↑ qsl.net
- ↑ autobild.de
- ↑ saabhistory.com
- ^ F. Schmidt, U. Sager, E. Däuber: Dynamic adsorption behavior of cabin air filters . In: Filtration & Separation . tape 39 , no. 7 , September 2002, p. 42-47 , doi : 10.1016 / S0015-1882 (02) 80210-5 .