Sealing arrangement with pressure responsive diaphragm means

A seal construction for sealing a rotating shaft against passage of a fluid along a central axis of said rotating shaft, said seal construction comprising:

• a) a sealing flange means fixedly mounted on said shaft and rotatable therewith about said central axis, said sealing flange having a forward and rear surface, each of said surfaces central axis, said forward surface of said flange being exposed to said fluid to be sealed against and
• a stationary sealing means for creating a fluid seal between said rear surface of said rotatable sealing flange and said stationary sealing means, said stationary sealing means comprising:
• an engaging member having a first forward surface located for sealing engagement with said rear surface of said sealing flange and a second rearward surface, said engaging member being spaced radially outwardly from and extending circumferentially around said rotating shaft,
• biasing means for normally urging said first forward surface of said engaging member into sealing engagement with said rear surface of said sealing flange,
• a fluid passageway communicating said fluid to be sealed with said second rearward surface of said engaging member, and
• a diaphragm means extending across said fluid passageway for determining the amount of force placed on the said second rearward surface of said engaging member by said fluid to be sealed, said diaphragm means being attached across said fluid passageway in such a way that any increase in pressure of said fluid to be sealed upon said diaphragm will cause said diaphragm to flex radially inwardly, thereby increasing the surface area of said second rearward surface of said engaging member exposed to the pressure of said fluid to be sealed, the net effect of said radially inward flexing of said diaphragm means being to further urge said first forward surface of said engaging member into sealing engagement with said rear surface of said sealing flange.