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Providing clean air even in heavy traffic

The smart cabin air filter system from MANN+HUMMEL provides clean air and simultaneously reduces power consumption – a perfect concept for electric vehicles, such as for example Zoe, the best-selling EV model from Renault.

Smart cabin air filter system

At 7.30 each morning the traffic towards the city center is inevitably heavy. The ambient air is strongly polluted with nitrogen dioxide, fine particulate matter, pollen and soot. This is a scenario which repeats itself in cities every day around the world. In the meantime, the climate debate has become more intense and therefore research and development specialists are also urgently looking for solutions for clean mobility, with many discussions focusing on electric mobility. One aspect which is crucial for the acceptance of electric mobility is the driving range of the vehicles. Regarding air conditioning concepts for electric vehicles, manufacturers therefore have to consider solutions which require less power, but which still ensure excellent air quality within the cabin. Renault has also pursued this approach and is currently working together with MANN+HUMMEL on a smart, switchable and multi-stage cabin air filter system which is specially designed for the Zoe.

Three filters for best air quality

The Smart cabin air filter system developed in 2017 by MANN+HUMMEL has a pioneering three-stage concept. In addition to the cabin air filter, an ambient air filter in the form of a NO2 fine dust combi-filter retains fine particulate matter, pollen and harmful gases from the incoming air. When necessary, a high efficiency particulate air filter (HEPA) removes ultra‑fine particles such as soot or brake dust.

An important part of the system is an intelligent algorithm which ensures the most efficient use of the re-circulated air inside the vehicle. As a result, the system fresh air intake adds only the lowest required amount of fresh air into the vehicle and adjusts the temperature to match that of the current cabin condition. This saves energy and therefore extends the driving range of electric vehicles. In addition, in order to ensure the ideal air quality in all environmental situations, sensors continually monitor the air quality inside the vehicle cabin. These sensors monitor for example the levels of CO2, particle concentrations and relative air humidity in the vehicle cabin. If the prescribed limit values are reached, the intelligent cabin air filter system increases the intake of fresh air. Sensors detect the quality of the added air and provide data which the system analyzes and then decides which of the three filters the air will flow through. Due to the fact that the filtration experts at MANN+HUMMEL specialize in developing filter elements integrating many varied types of activated carbon, the Smart cabin air filter system always guarantees the optimal solution, regardless of the requirements. The system therefore reliably protects occupants of the vehicle at all times against undesired odors or harmful gases and maintains the CO2 content at a comfortably low level. These are good examples of requirements which in view of car-sharing are becoming increasingly important.

MANN+HUMMEL smart cabin air filter system

1 Prefilters


3 HEPA filter


A concept suitable for customization

In the Renault Zoe a HEPA filter is installed in a housing below the windscreen. When the pollution level is high, a flap opens and the HEPA filter is activated. The switching function of the HEPA filter is based on the current air quality demands and extends the life of the filter as much as possible. Extensive simulations were carried out to confirm the feasibility of the concept. Various tests and field trials showed that the system is able to filter out up to 98 percent of all particles smaller than a micrometer from the ambient air. The driver can view the quality of the air inside the vehicle on the media display at any time.

The whole system was specially adapted to the compact package space present in the Renault Zoe. Innovative pleating and manufacturing processes helped to considerably reduce the dimensions of the HEPA filter. The engineers put a strong focus on a robust yet inexpensive sealing of the HEPA filter. Nanofibers in the filter media of the ambient air filter effectively retain ultra‑fine particles and at the same time lengthen the service interval of the HEPA filter. The project is an important step forward and shows the firm commitment of MANN+HUMMEL with regard to the protection of vehicle occupants. It is also a big step towards clean mobility.