Hydrodynamic lubricant seal for drill bits

A circular sealing member forming a lubricant side at one axial extremity and a contaminant side at the opposite axial extremity and providing a contaminant barrier and lubricated seal between relatively rotatable surfaces in communication with a supply of liquid lubricant at one axial extremity thereof and a contaminant at the opposite axial extremity thereof comprising:

• (a) a circular body of resilient sealing material defining inner and outer peripheral sealing surfaces, one of said peripheral sealing surfaces disposed for static sealing engagement with one of said relatively rotatable surfaces and the opposite one of said peripheral sealing surfaces defining a relatively rotatable sealing interface with the other of said relatively rotatable surfaces;
• (b) a contaminant interface surface being formed by said circular body of sealing material and intersecting said other of said relatively rotatable surfaces in such angular relation as to form an abrupt circular scraping edge, upon relative rotary and axial movement of said relatively rotatable surfaces said abrupt circular scraping edge providing a scraping function preventing contaminants from entering the seal interface between said sealing surface and said other of said relatively rotatable surfaces, said contaminant interface surface developing substantially no hydrodynamic back feeding pumping activity at said contaminant interface upon relative rotational movement of said circular body of sealing material and contaminant material;
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• (c) a tapered convoluted surface being formed by said circular body of sealing material on said lubricant side and disposed for contact with said liquid lubricant, said tapered convoluted surface acting cooperatively with said liquid lubricant during relative rotation of said opposite one of said peripheral surfaces and said other of said relatively rotatable surfaces to develop a hydrodynamic lubricant pumping activity inducing net unidirectional flow of lubricant in said seal interface from said convoluted surface of said lubricant side toward said abrupt circular scraping edge of said contaminant side.

A lubricant seal member for establishing sealing between a housing and a shaft extending through the housing, wherein one of the housing and shaft is a rotating member and forms annular sealing surface means, said lubricant seal member adapted to establish a sealed partition between said housing and shaft and forming a lubricant side at one axial extremity for contact with liquid lubricant and a contaminant side at the opposite axial extremity for contact with any contaminant present at said contaminant side and comprising:

• (a) a circular body of resilient sealing material defining inner and outer peripheral surface means, one of said inner and outer peripheral surface means adapted to establish a dynamic sealing interface with said annular sealing surface means;
• (b) convoluted lubricant face surface means being defined by said circular body of resilient sealing material at said lubricant side and being of a tapered wave-like configuration developing a hydrodynamic lubricant wedging activity upon relative rotation of said housing and shaft with said liquid lubricant in contact with said lubricant face surface means, said hydrodynamic lubricant wedging activity developing net unidirectional lubricant film pumping at said dynamic sealing interface from said lubricant side to said contaminant side;
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• (c) a contaminant face at said contaminant side being defined by said circular body of sealing material opposite said lubricant face and being of a configuration developing substantially no hydrodynamic back feeding pumping activity responsive to relative rotation of said housing and shaft with contaminant material and lubricant in contact with said contaminant face and thereby preventing the development of contaminant and contaminated lubricant migration in said sealing interface from said contaminant side to said lubricant side.