Housing of DuPontT Zytel HTN for map-controlled thermostat
Behr Thermot-tronik worked closely with DuPont to choose and optimize the welding process. - This housing for the map-controlled thermostat for the BMW N43-series motor is, as far as we know, the first component of its kind to be vibration-welded - comments Andreas Oldeweme, who works in Automotive Market Development at DuPont. - Accordingly, the preparatory work was very thorough before this process was integrated into volume production. First of all, in comprehensive tests carried out in DuPont`s European Technical Centre in Geneva we compared various welding processes, including laser welding. It finally turned out that friction-welding offered definite application-related advantages. Working together with the welding equipment manufacturer, Behr Thermot-tronik then converted our test-specimen results into practice with the real thermostat housing and thus ensured rapid and reliable production of the part.
To simplify installation, Behr Thermot-tronik`s map-controlled thermostat is executed as a module in an integral construction method. Apart from the thermostat itself, it includes the connecting leads to the cooling system and the electric contact between the map-control system and the heating resistance. This ensures optimum coolant flow as well as a dependable electricity supply for the heating resistance. Yet it takes up hardly more space than conventional integral thermostats.
- As a result of DuPont`s extensive application-related support and the good results we have had to date with the processing, Behr Thermot-tronik is now using Zytel HTN for further map-controlled thermostats of which some are in development and others already in production - says Frunzetti.
What is the electronic Map-Controlled Thermostats?
In conventional cooling systems a wax element keeps the coolant temperature close to about 90°C. This control method ensures that the motor does not overheat even under extreme conditions, such as very high vehicle speeds, very high ambient temperatures and heavy loads. However, in normal conditions a petrol engine can generally be operated at 110°C without danger. This high temperature improves tribological conditions in the motor, which in turn reduce friction losses, fuel consumption and exhaust emissions. An electronic map-controlled thermostat can satisfy such variable requirements, because it can adapt the coolant temperature to the motor`s operating conditions within broader limits. With the motor at partial load it maintains the coolant temperature at a consistently high level; at full load, high engine speeds or high outside temperatures it reduces the temperature and thus ensures performance characteristics which match these conditions.