Polaris, a manufacturer of snowmobiles and off-road vehicles, including ATVs (all-terrain vehicles), side-by-side vehicles and motorcycles, has been providing customers with reliable transportation in even the harshest environments for decades. For almost two decades, Freudenberg-NOK Sealing Technologies (Freudenberg-NOK) engineers have contributed their expertise and resources to create diaphragms and introduce materials and design improvements to extend the life of these important components.
Polaris snowmobiles run on a two-stroke engine, where the diaphragms (there are two per engine, one per cylinder) use cylinder pressure to actuate the variable exhaust valve mechanisms. If the diaphragm fails, the variable exhaust valve will not actuate at the designated engine revolutions per minute (RPM). The result is that the engine will not reach its peak power and peak power RPM, which reduces the machine’s performance.
Engineers identified a further concern: Inferior diaphragms might fail completely, causing the variable exhaust mechanism to malfunction. When this occurs, the engine runs at a significantly reduced power level. If both diaphragms fail in rapid succession, the machine experiences further performance losses.
Collaboration between Polaris and Freudenberg-NOK has resulted in the design and production of a virtually maintenance-free diaphragm that lasts as long as the sled itself. Engineers optimized the design for Polaris by incorporating fabric reinforced high temperature meta-aramid fabric (Nomex) to withstand extended high temperature in the exhaust system where the diaphragm is used and temperatures can often exceed 300°F.
The company also added a RFN coating to reduce friction by up to 70%, allowing the diaphragm to move effortlessly along the surfaces of the mating hardware. Finally, the design was changed from a dome shape to a convoluted shape to decrease potential assembly issues, as well as allow for proper movement of the diaphragm and incorporated small rubber ribs to the fabric side to protect it from abrasion. The durability improvements to the diaphragm reduced the maintenance required by the customer.