Mechanical face seal with a reverse trapezoidal face pattern

A mechanical seal ring having a hydrodynamic face pattern formed on seal face extending between first and second seal ring diameters, said face pattern comprising:

• a primary face pattern along said first ring diameter and a secondary face pattern along said second ring diameter, said primary face pattern being operable on a normally higher pressure side of said seal ring to create lift under normal operating conditions, said primary face pattern comprising a plurality of hydrodynamic primary grooves which are circumferentially spaced apart by lands, said primary grooves having one circumferential edge opening from said first ring diameter and extending radially to a primary groove edge which is spaced radially from said second ring diameter to define an annular dam region on said seal face;
• and
• said secondary face pattern being provided on said second ring diameter towards a normally lower pressure side of said seal face and being operable under reverse pressure conditions wherein said higher and lower pressures switch from one of said first and second ring diameters to the other to create lift under reversed pressure conditions where the normally lower pressure side reaches a higher pressure than the normally higher pressure side, said secondary face pattern comprising circumferentially separated secondary grooves formed as sinusoidal waves;
• and
• said primary grooves being formed with a reverse trapezoidal face pattern comprising a plurality of said primary grooves recessed in said seal face of said seal ring and having a reverse trapezoid shape to generate a fluid film over said seal face, said primary groove edge of each said primary groove being defined by side edges extending radially so as to angle away from each other in opposite circumferential directions, and by narrower and wider circumferential edges extending circumferentially between said side edges wherein said wider circumferential edge intersects with said side edges to define circumferentially spaced corner areas of said primary groove, said narrower circumferential edge being located at said first ring diameter of said seal ring to receive higher pressure fluid therein, and said wider circumferential edge being spaced radially from said second ring diameter, said primary groove having a sine wave depth profile extending circumferentially between said side edges with a deepest depth being provided in a central region of said primary groove at said narrower circumferential edge and shallowest depths being disposed along said side edges, said depth profile being progressively shallower radially from said narrower circumferential edge toward said wider circumferential edge, wherein said depth profile defines a variable depth amplitude which varies radially and circumferentially such that said depth profile is circumferentially narrowest at said narrower circumferential edge and circumferentially widens toward said wider circumferential edge so that said depth profile has a maximum circumferential width spaced radially away from said narrower circumferential edge and extending into said corner areas.

A mechanical seal ring having a hydrodynamic face pattern, said seal ring having inner and outer ring diameters and seal face extending radially therebetween, said face pattern comprising:

• a reverse trapezoidal face pattern comprising at least one hydrodynamic lift groove recessed in said seal face to generate a fluid film over said seal face, each said groove being defined by outer side edges which extend radially and angle circumferentially away from each other, and by narrower and wider circumferential edges extending circumferentially between said side edges wherein said wider circumferential edge intersects with each of said side edges to define circumferentially spaced corner areas of said groove, said narrower circumferential edge being located at one of said inner and outer ring diameters to receive pressurized fluid therein, and said wider circumferential edge being spaced radially between said inner circumferential edge and the other of said inner and outer ring diameters, said groove having a sine wave depth profile extending circumferentially between said side edges with a deepest depth being provided in a central region of said groove and shallowest depths being disposed along said side edges, said depth profile defining a variable depth amplitude which varies radially and circumferentially such that said depth profile is circumferentially narrowest at said narrower circumferential edge and circumferentially widens away from said wider circumferential edge so that said depth profile has a maximum width spaced radially away from said narrower circumferential edge and extending into said corner areas, said depth profile being progressively shallower radially from said narrower circumferential edge toward said wider circumferential edge and wherein a deepest depth amplitude is defined in a central contour located centrally in said central region of said groove at said narrower circumferential edge, and said depth profile varies radially and circumferentially across progressively shallower contours with said shallowest depth being defined along said side edges circumferentially spaced from said central contour and within said corner areas, said progressively shallower contours becoming progressively wider from said narrower circumferential edge toward said wider circumferential edge so that each of said contours is narrowest at said inner circumferential edge and becomes wider away from said inner circumferential edge.