The Role of the Stopper in the Mechanics of Combustion Seals

Many gaskets have constructions that combine structures of varying compressive stiffness. Low stiffness features may be used for coolant and oil seals; while, extremely stiff components could be used around a fastener as a load stop or around a combustion opening as part of a combustion seal. The use of a high stiffness stopper as part of a combustion seal has a significant effect on the overall behavior of the gasket. The stopper influences the distribution of total bolt load over the entire gasket by concentrating load toward the combustion opening. In the case of multi-layer steel gaskets, fluctuating loads on the combustion seal such as the head lifting force that is generated from the cylinder firing pressure are split between high stiffness stoppers and lower stiffness embosses that surround the combustion opening. In this paper, we will look at the basic mechanics of combustion seal stoppers and consider the effect of the stopper on combustion seal performance. A review of some of the current stopper combustion seal designs will be presented.