Mechanical seal with improved leakage control

Claim 2

A mechanical seal assembly for sealing a rotary shaft to a housing containing fluid under pressure and having a shaft opening through which the shaft extends, 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. non-rotatable sealing ring means fixedly mounted on the housing; c. said rotatable and said non-rotatable sealing ring means having opposed, generally radial sealing surfaces disposed in relatively rotatable sealing relationship, said surfaces defining therebetween an annular sealing zone; d. said housing having a support flange surrounding the shaft, said flange supporting said non-rotatable 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 non-rotatable sealing ring means defining therebetween an annular cavity disposed radially outward from said annular surface; f. means for sealing said cavity; g. said non-rotatable 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; i. first fluid passage means extending through said nonrotatable sealing ring means and having, at one of its ends, a first port opening into said annular sealing zone and, at the other of its ends, having a second port opening into said cavity; and j. second fluid passage means in said rotatable sealing ring means having at one end, a plurality of arcuately spaced ports opening into said annular sealing zone, said second fluid passage means communicating, at the other of its ends, with said fluid within the housing.

Claim 3

A mechanical seal assembly as defined in claim 1, wherein said second fluid passage means comprises a plurality of arcuately spaced, radial notches formed in the outer peripheral portion of said rotatable sealing ring means.

Claim 4

A mechanical seal assembly as defined in claim 2, wherein said notches communicate successively with said first port upon rotation of said rotatable sealing ring means.

Claim 5

A mechanical seal assembly as defined in claim 3, wherein said notches communicate with said first port to only partially open the latter.

Claim 6

A mechanical seal assembly as defined in claim 2, wherein said notches have inner end walls that extend axially of said rotatable sealing ring means.

Claim 7

A mechanical seal assembly for sealing a rotary shaft to a housing containing fluid under pressure and having a shaft opening through which the shaft extends, said mechanical seal assembly comprising: a. a rotatable sealing ring mounted on and rotatable with the shaft, said sealing ring having limited movability axially of the shaft; b. a non-rotatable sealing ring fixedly mounted on the housing; c. said sealing rings having opposed, generally radial sealing surfaces disposed in relatively rotatable sealing relationship, said surfaces defining therebetween an annular sealing zone; d. a back-up ring supporting said non-rotatable sealing ring on its side opposite to its generally radial sealing surface; e. said back-up ring and said non-rotatable 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 back-up 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 back-up ring defining therebetween an annular cavity disposed radially outward from said annular surface; h. means for sealing said cavity; i. said back-up 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; k. first fluid passage means extending through said non-rotatable sealing ring and said back-up ring, said first fluid passage means having, a one of its ends, a first port opening into said annular sealing zone and, at the other of its ends, having a second port opening into said cavity; and i. second fluid passage means in said rotatable sealing ring means having at one end, a plurality of arcuately spaced ports opening into said annular sealing zone, said second fluid passage means communicating, at the other of its end, with said fluid within the housing.

Claim 8

A mechanical seal assembly for sealing a rotary shaft to a housing containing fluid under pressure and having a shaft opening through which the shaft extends, said mechanical seal assembly comprising: a. a rotatable sealing ring mounted on and rotatable with the shaft, said sealing ring having limited movability axially of the shaft; b. a non-rotatable sealing ring fixedly mounted on the housing; c. said sealing rings having opposed, generally radial sealing surfaces disposed in relatively rotatable sealing relationship, said surfaces defining therebetween an annular sealing zone; d. a back-up ring supporting said non-rotatable sealing ring on its side opposite to its generally radial sealing surface; e. said back-up ring and said non-rotatable 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 back-up 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 back-up ring defining therebetween an annular cavity disposed radially outward from said annular surface; h. means for sealing said cavity; i. said back-up 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; k. first fluid passage means extending through said non-rotatable sealing ring and said back-up ring, said first fluid passage means having, a one of its ends, a first port opening into said annular sealing zone and, at the other of its ends, having a second port opening into said cavity; and i. second fluid passage means in said rotatable sealing ring means having at one end, a plurality of arcuately spaced ports opening into said annular sealing zone, said second fluid passage means communicating, at the other of its end, with said fluid within the housing.

Claim 9

A mechanical seal assembly as defined in claim 6, wherein said second fluid passage means comprise a plurality of arcuately spaced, radial notches formed in the outer peripheral portion of said rotatable sealing ring.

Claim 10

A mechanical seal assembly as defined in claim 7, wherein said notches communicate successively with said first port means upon rotation of said rotatable sealing ring.

Claim 11

A mechanical seal assembly as defined in claim 8, wherein said notches communicate with said first port to only partially open the latter.

Claim 12

A mechanical seal assembly as defined in claim 7, wherein said notches have inner end walls that extend axially of said rotatable sealing ring.

Claim 13

A staged, rotary, mechanical fluid pressure seal assembly for sealing a rotary shaft to a housing containing fluid under high pressure and having a shaft opening through which the shaft extends for progressively reducing the pressure through the seal stages, said assembly including: low pressure final stage sealing means and at least one preliminary stage sealing means exposed to the high pressure fluid in said housing, said preliminary stage sealing means 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. non-rotatable sealing ring means fixedly mounted on the housing; c. said rotatable and said non-rotatable sealing ring means having opposed, generally radial sealing surfaces disposed in relatively rotatable sealing relationship, said surfaces defining therebetween an annular sealing zone; d. said housing having a support flange surrounding the shaft, said flange supporting said non-rotatable 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 non-rotatable sealing ring means defining therebetween an annular cavity disposed radially outward from said annular surface; f. means for sealing said cavity; g. said non-rotatable sealing ring means having 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; i. first fluid passage means extending through said non-rotatable sealing ring means and having, at one of its ends, a first port opening into said annular sealing zone and, at the other of its ends, having a second port opening into said cavity; and j. second fluid passage means in said rotatable sealing ring means having at one end, a plurality of arcuately spaced ports opening into said annular sealing zone, said second fluid passage means communicating, at the other of its ends, with said fluid within the housing.

Claim 14

A staged, rotary, mechanical fluid pressure seal assembly for sealing a rotary shaft to a housing containing fluid under high pressure and having a shaft opening through which the shaft extends for progressively reducing the pressure through the seal stages, said assembly including: low pressure final stage sealing means and at least one preliminary stage sealing means exposed to the high pressure fluid in said housing, said preliminary stage sealing means 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. non-rotatable sealing ring means fixedly mounted on the housing; c. said rotatable and said non-rotatable sealing ring means having opposed, generally radial sealing surfaces disposed in relatively rotatable sealing relationship, said surfaces defining therebetween an annular sealing zone; d. said housing having a support flange surrounding the shaft, said flange supporting said non-rotatable 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 non-rotatable sealing ring means defining therebetween an annular cavity disposed radially outward from said annular surface; f. means for sealing said cavity; g. said non-rotatable sealing ring means having 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; i. first fluid passage means extending through said non-rotatable sealing ring means and having, at one of its ends, a first port opening into said annular sealing zone and, at the other of its ends, having a second port opening into said cavity; and j. second fluid passage means in said rotatable sealing ring means having at one end, a plurality of arcuately spaced ports opening into said annular sealing zone, said second fluid passage means communicating, at the other of its ends, with said fluid within the housing.

Claim 15

A staged, rotary, mechanical fluid pressure seal assembly for sealing a rotary shaft to a housing containing fluid under high pressure and having a shaft opening through which the shaft extends for progressively reducing the pressure through the seal stages, said assembly including: low pressure final stage sealing means and at least one preliminary stage sealing means exposed to the high pressure fluid in said housing, said preliminary stage sealing means comprising: a. a rotatable sealing ring mounted on and rotatable with the shaft, said sealing ring having limited movability axially of the shaft; b. a non-rotatable sealing ring fixedly mounted on the housing; c. said sealing rings having opposed, generally radial sealing surfaces disposed in relatively rotatable sealing relationship, said surfaces defining therebetween an annular sealing zone; d. a back-up ring supporting said non-rotatable sealing ring on its side opposite to its generally radial sealing surface; e. said back-up ring and said non-rotatable 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 back-up 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 back-up ring defining therebetween an annular cavity disposed radially outward from said annular surface; h. means for sealing said cavity; i. said back-up 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 said of said peripheral portion and exposed to the pressure of fluid within the housing; k. first fluid passage means extending through said non-rotatable sealing ring and said back-up ring, said first fluid passage means having, at one of its ends, a first port opening into said annular sealing zone and, at the other of its ends, having a second port opening into said cavity; and l. second fluid passage means in said rotatable sealing ring means having at one end, a plurality of arcuately spaced ports opening into said annular sealing zone, said second fluid passage means communicating, at the other of its end, with said fluid within the housing.

Claim 16

A staged, rotary, mechanical fluid pressure seal assembly for sealing a rotary shaft to a housing containing fluid under high pressure and having a shaft opening through which the shaft extends for progressively reducing the pressure through the seal stages, said assembly including: low pressure final stage sealing means and at least one preliminary stage sealing means exposed to the high pressure fluid in said housing, said preliminary stage sealing means comprising: a. a rotatable sealing ring mounted on and rotatable with the shaft, said sealing ring having limited movability axially of the shaft; b. a non-rotatable sealing ring fixedly mounted on the housing; c. said sealing rings having opposed, generally radial sealing surfaces disposed in relatively rotatable sealing relationship, said surfaces defining therebetween an annular sealing zone; d. a back-up ring supporting said non-rotatable sealing ring on its side opposite to its generally radial sealing surface; e. said back-up ring and said non-rotatable 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 back-up 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 back-up ring defining therebetween an annular cavity disposed radially outward from said annular surface; h. means for sealing said cavity; i. said back-up 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 said of said peripheral portion and exposed to the pressure of fluid within the housing; k. first fluid passage means extending through said non-rotatable sealing ring and said back-up ring, said first fluid passage means having, at one of its ends, a first port opening into said annular sealing zone and, at the other of its ends, having a second port opening into said cavity; and l. second fluid passage means in said rotatable sealing ring means having at one end, a plurality of arcuately spaced ports opening into said annular sealing zone, said second fluid passage means communicating, at the other of its end, with said fluid within the housing.