Gearboxes are located under the car and during operating are subjected to rapid temperature fluctuations, for example when the car drives with a hot gearbox through water. This leads to fast temperature and pressure changes within the gearbox; pressure changes that need to be compensated and equilibrated with the outside atmosphere. All automotive gearboxes use some kind of breather system to allow this pressure stabilization. The breather needs to keep all oil inside the gearbox and simultaneous must keep all water (underbody splash, mist) out of the gearbox under all operating conditions (high speed, fast accelerations, slopes). These requirements make the design and validation of a breather a very resource consuming task that usually requires multiple hardware loops. With current automotive gearboxes required to handle ever increasing speeds (like for electric and hybrid cars) and suitable areas to place the breather becoming scarcer, the company is looking for novel ideas or materials that simplify the breather design yet assure all functionality. Possible approaches might include, but are not limited to: -New designs that allow air to pass through but keeps water out and oil in -New compensation volumes and designs (e.g. expandable reservoirs inside or outside the gearbox) -Chemicals that react to compensate pressure variations. -Active systems like externally controlled power consuming pumps, vents, volume modifiers, etc. are not of interest.
Technical Specifications / Specific technical requirements of the request:
The successful technology will: -Be applied on a gearbox with a typical inside volume of 3 liter consisting of 0.75 liter of transmission oil and 2.25 liter of air. During operation liquid, foam and gas phases are co-existing. -Be functional between -40°C and +150°C -Allow for a maximum pressure difference to the outside atmosphere of 0.3 bar (pressure delta that the rotary sliding seals on the drive and input shaft can handle) -Allow for more than 100.000 heating/cooling cycles without loss of functionality -Be able to withstand temperatures gradients like those defined in the following test: Heat the gearbox unit to 125°C for 5 hours Immerse the unit in ice water within 5 seconds and immerse it completely for 1 second Immerse up to the breather for 45 seconds Take out the unit and inspect the lubricating oil for water content Repeat the test 20 times -Be able to handle sudden shocks from stones (if placed on the outside of the gearbox) -Be compatible with a variety of transmission oils and other materials typically used in a gearbox (like plastics or composites) -Be suitable for mass production at low cost (<5€).
List of Keywords:
· Design of Vehicles
· Hybrid and Electric Vehicles