Mechanical seal assembly with leakage control

Claim 2

A mechanical seal assembly for sealing a rotary shaft to a housing having a shaft opening through which the shaft extend, said mechanical seal assembly comprising: a. rotatable sealing ring means mounted on the shaft for rotation therewith, said rotatable sealing ring means having limited movability axially of the shaft; b. nonrotatably sealing ring means; c. said rotatable and said nonrotatable sealing ring means having opposed, generally radial sealing surfaces disposed in relatively rotatable sealing relationship; d. said housing having a support flange surrounding the shaft, said flange supporting said nonrotatable sealing ring means on its side opposite to its said generally radial sealing surface and along an annular surface spaced radially inward from its outer periphery; e. said flange and said nonrotatable sealing ring means defining therebetween an annular cavity disposed radially outward from said annular surface; f. means for sealing said cavity; g. said nonrotatable sealing ring means having a cantilevered peripheral portion that is free to flex into said cavity; h. said peripheral portion having a first, generally radial annular surface contiguous to said cavity and exposed to the pressure of fluid therein, and a second generally radial surface on the opposite side of said peripheral portion and exposed to the pressure of the fluid within the housing; and i. fluid passage means extending through said nonrotatable sealing ring means and opening, at one of its ends, into the space between said sealing surfaces and, at the other of its ends, into said cavity.

Claim 3

A mechanical seal assembly for sealing a rotary shaft to a housing having a shaft opening through which the shaft extends, said mechanical seal assembly having: a. a rotatable sealing ring mounted on the rotatable with the shaft, said sealing ring having limited movability axially of the shaft; b. a nonrotatable sealing ring; c. said sealing rings having opposed, generally radial surfaces in relatively rotatable sealing relationship; d. a backup ring supporting said nonrotatable sealing ring on its side opposite to its generally radial surface; e. said backup ring and said nonrotatable sealing ring having opposed, generally radial sealing surfaces in stationary sealing relationship; f. said housing having a support flange surrounding the shaft, said flange supporting said backup ring on its side opposite to its said generally radial sealing surface, and along an annular surface spaced radially inward from its outer periphery; g. said flange and said backup ring defining therebetween an annular cavity disposed radially outward from said annular surface; h. means for sealing said cavity; i. said backup ring having a cantilevered peripheral portion that is free to flex into said cavity; j. said peripheral portion having a first, generally radial annular surface Contiguous to said cavity and exposed to the pressure of fluid therein, and a second, generally radial surface on the opposite side of said peripheral portion and exposed to the pressure of fluid within the housing; and k. fluid passage means extending through said nonrotatable sealing ring and said backup ring, said fluid passage means opening, at one of its ends, into the space between said opposed, generally radial surfaces in relatively rotatable sealing relationship and, at the other of its ends, into said cavity.

Claim 4

A mechanical seal assembly for sealing a rotary shaft to a housing having a shaft opening through which the shaft extends, said mechanical seal assembly having: a. a rotatable sealing ring mounted on the rotatable with the shaft, said sealing ring having limited movability axially of the shaft; b. a nonrotatable sealing ring; c. said sealing rings having opposed, generally radial surfaces in relatively rotatable sealing relationship; d. a backup ring supporting said nonrotatable sealing ring on its side opposite to its generally radial surface; e. said backup ring and said nonrotatable sealing ring having opposed, generally radial sealing surfaces in stationary sealing relationship; f. said housing having a support flange surrounding the shaft, said flange supporting said backup ring on its side opposite to its said generally radial sealing surface, and along an annular surface spaced radially inward from its outer periphery; g. said flange and said backup ring defining therebetween an annular cavity disposed radially outward from said annular surface; h. means for sealing said cavity; i. said backup ring having a cantilevered peripheral portion that is free to flex into said cavity; j. said peripheral portion having a first, generally radial annular surface Contiguous to said cavity and exposed to the pressure of fluid therein, and a second, generally radial surface on the opposite side of said peripheral portion and exposed to the pressure of fluid within the housing; and k. fluid passage means extending through said nonrotatable sealing ring and said backup ring, said fluid passage means opening, at one of its ends, into the space between said opposed, generally radial surfaces in relatively rotatable sealing relationship and, at the other of its ends, into said cavity.

Claim 5

A mechanical seal assembly as defined in claim 2, wherein said means for sealing said cavity comprise O-ring gasket means for sealing the rim of said cantilevered peripheral portion to said flange.

Claim 6

A mechanical seal assembly as defined in claim 3, wherein said means for sealing said cavity further includes second O-ring gasket means for sealing said backup ring to said flange adjacent to said annular surface that is spaced radially inward from the outer periphery of said backup ring.

Claim 7

A mechanical seal assembly as defined in claim 2, wherein said fluid passage means includes means providing an annular collector groove opening into said generally radial sealing surfaces in stationary sealing relationship between said backup ring and said nonrotatable sealing ring, a plurality of passageways in said nonrotatable sealing ring for communicating the space between said relatively rotatable sealing surfaces with said collector groove, and a further passageway communicating said collector groove with said cavity.