Centrifugal pump

Claim 2

A centrifugal pump comprising a casing, at least one impeller mounted for rotation in said casing and at least one seal for limiting leakage between the rotating impeller and the casing, said seal having sealing means with at least two faces spaced from each other by a space, a first of said faces being positioned adjacent a highpressure zone and a second of said faces being positioned adjacent a lowpressure zone, said faces forming part of one and the same sealing ring movable transversely to said faces, and said sealing ring having at least one back surface influenced by the pressure of said high pressure zone and at least one back surface influenced by the pressure of said lowpressure zone, said space communicating with a region of pressure considerably lower than the pressure of said high pressure zone.

Claim 3

A centrifugal pump as claimed in claim 1, characterised in that said second face communicates with a control space separated from the low-pressure zone, said control space communicating via throttle means with a control pressure source, said sealing ring having a third back surface influenced by the control pressure of the control space.

Claim 4

A centrifugal pump as claimed in claim 1, characterised in that said space communicates with said low pressure zone.

Claim 5

In a centrifugal pump having a casing and an impeller mounted for rotation in said casing, said impeller including a seal-engageable face leading transversely thereof from a high pressure region of said pump to a low pressure region, and a sealing ring movably carried by said casing for movement toward and away from said seal-engageable face, said sealing ring comprising: a body having a pair of annular faces facing and adapted to engage said seal-engageable face of the impeller, said annular faces being separated by a channel, said body having a pair of rear faces opposite to and parallel with said annular faces, one of said rear faces being exposed to said high pressure region and the other of said rear faces being exposed to said low pressure region; seal means engaging said body between said rear faces thereof for pressure isolating said rear faces from each other; and means for maintaining said channel at a pressure substantially less than that of said high pressure region.

Claim 6

In a centrifugal pump having a casing and an impeller mounted for rotation in said casing, said impeller including a seal-engageable face leading transversely thereof from a high pressure region of said pump to a low pressure region, and a sealing ring movably carried by said casing for movement toward and away from said seal-engageable face, said sealing ring comprising: a body having a pair of annular faces facing and adapted to engage said seal-engageable face of the impeller, said annular faces being separated by a channel, said body having a pair of rear faces opposite to and parallel with said annular faces, one of said rear faces being exposed to said high pressure region and the other of said rear faces being exposed to said low pressure region; seal means engaging said body between said rear faces thereof for pressure isolating said rear faces from each other; and means for maintaining said channel at a pressure substantially less than that of said high pressure region.

Claim 7

In a centrifugal pump as defined in claim 5 wherein the means last mentioned communicates said channel with said low pressure region.

Claim 8

In a centrifugal pump as defined in claim 4 wherein said seal-engageable face is cylindrical.

Claim 9

In a centrifugal pump as defined in claim 4 wherein said seal-engageable face is flat and annular.

Claim 10

In a centrifugal pump as defined in claim 4 wherein the areas of said rear faces and the area of the bottom said channel are balanced with respect to the pressures acting thereon to establish a low residual sealing force pressing said annular faces against said seal-engageable face.

Claim 11

In a centrifugal pump as defined in claim 8 wherein the means last mentioned communicates said channel with said low pressure region.

Claim 12

In a centrifugal pump as defined in claim 8 wherein said seal-engageable face is cylindrical.

Claim 13

In a centrifugal pump as defined in claim 8 wherein said seal-engageable face is flat and annular.

Claim 14

In a centrifugal pump having a casing and an impeller rotatably mounted in the casing whereby fluid tends to leak out of the casing past said impeller due to high pressure developed by said pump, sealing means interposed between the casing and the impeller and movably carried by one of them for moVement normal to the direction in which fluid tends to leak into engagement with the other of said casing and impeller, said sealing means comprising: an annular member surrounding said impeller and having a pair of annular faces adapted to engage said other of said casing and impeller, recess means separating said annular faces for defining a bottom wall area of first selected area, said member having a pair of rear faces opposite from said annular faces one of which is of second selected area and the other of which is of third selected area, said one rear face communicating with a high pressure region in said pump and said other rear face communicating with a low pressure region; seal means for isolating said rear faces from each other; and means for communicating said recess means with low fluid pressure; said first, second and third selected areas being balanced with respect to the pressures acting on them to establish a low residual sealing force pressing said annular faces against said other of said casing and impeller preventing said leakage of fluid past said impeller.

Claim 15

In a centrifugal pump having a casing and an impeller rotatably mounted in the casing whereby fluid tends to leak out of the casing past said impeller due to high pressure developed by said pump, sealing means interposed between the casing and the impeller and movably carried by one of them for moVement normal to the direction in which fluid tends to leak into engagement with the other of said casing and impeller, said sealing means comprising: an annular member surrounding said impeller and having a pair of annular faces adapted to engage said other of said casing and impeller, recess means separating said annular faces for defining a bottom wall area of first selected area, said member having a pair of rear faces opposite from said annular faces one of which is of second selected area and the other of which is of third selected area, said one rear face communicating with a high pressure region in said pump and said other rear face communicating with a low pressure region; seal means for isolating said rear faces from each other; and means for communicating said recess means with low fluid pressure; said first, second and third selected areas being balanced with respect to the pressures acting on them to establish a low residual sealing force pressing said annular faces against said other of said casing and impeller preventing said leakage of fluid past said impeller.

Claim 16

In a centrifugal pump as defined in claim 12 wherein said sealing means engages said impeller, said impeller having a cylindrical surface portion with which said annular faces are engaged.

Claim 17

In a centrifugal pump as defined in claim 12 wherein said sealing means engages said impeller, said impeller having a flat annular surface portion with which said annular faces are engaged.

Claim 18

In a centrifugal pump as defined in claim 12 wherein said member is provided with a third rear face of selected area disposed between said one and said other rear faces; said seal means isolating all three of said rear faces from each other; and means for maintaining a control pressure on said third rear face.

Claim 19

In a centrifugal pump as defined in claim 15 including passage means in said member communicating said third rear face with one of said annular faces.

Claim 20

In a centrifugal pump having a casing and an impeller rotatably mounted in said casing whereby to generate a fluid high pressure region within said casing which tends to leak fluid past said impeller, and sealing means for preventing such leakage, said impeller having an annular surface across which fluid tends to leak and cooperating with said sealing means and said sealing means being movably carried by said casing for movement perpendicular to such surface into and out of engagement therewith, said sealing means comprising: a ring having a pair of annular surfaces opposed to said annular surface of the impeller, one of which is disposed on a high fluid pressure side of the sealing means and the other of which is disposed on a low fluid pressure side of the sealing means; recess means separating said annular surfaces for defining a fluid pressure relief when said annular faces are out of engagement with said annular surface of the impeller; passage means for communicating said recess means with a region of low pressure whereby when said annular faces are out of contact with said annular surface of the impeller leakage fluid may flow only past said one annular surface into said recess means to establish a pressure gradient across said one annular face while the recess means and said other annular face are subjected only to that low pressure with which said recess means is communicated thereby imposing but little force tending to separate said sealing means from said annular surface of the impeller; said sealing ring having a pair of rear faces opposite from said annular faces, one of said rear faces being continuously exposed to high fluid pressure and the other of said rear faces being continuously exposed to low fluid pressure; seal means engaging said sealing ring for pressure isolating said rear faces from each other; and the areas of said rear faces being such as tends always to override any separating force between the annular surface of the impeller and said sealing means while produciNg a low residual force pressing said annular faces against said annular surface of the impeller.

Claim 21

In a centrifugal pump having a casing and an impeller rotatably mounted in said casing whereby to generate a fluid high pressure region within said casing which tends to leak fluid past said impeller, and sealing means for preventing such leakage, said impeller having an annular surface across which fluid tends to leak and cooperating with said sealing means and said sealing means being movably carried by said casing for movement perpendicular to such surface into and out of engagement therewith, said sealing means comprising: a ring having a pair of annular surfaces opposed to said annular surface of the impeller, one of which is disposed on a high fluid pressure side of the sealing means and the other of which is disposed on a low fluid pressure side of the sealing means; recess means separating said annular surfaces for defining a fluid pressure relief when said annular faces are out of engagement with said annular surface of the impeller; passage means for communicating said recess means with a region of low pressure whereby when said annular faces are out of contact with said annular surface of the impeller leakage fluid may flow only past said one annular surface into said recess means to establish a pressure gradient across said one annular face while the recess means and said other annular face are subjected only to that low pressure with which said recess means is communicated thereby imposing but little force tending to separate said sealing means from said annular surface of the impeller; said sealing ring having a pair of rear faces opposite from said annular faces, one of said rear faces being continuously exposed to high fluid pressure and the other of said rear faces being continuously exposed to low fluid pressure; seal means engaging said sealing ring for pressure isolating said rear faces from each other; and the areas of said rear faces being such as tends always to override any separating force between the annular surface of the impeller and said sealing means while produciNg a low residual force pressing said annular faces against said annular surface of the impeller.

Claim 22

In a centrifugal pump as defined in claim 17 wherein said annular surface of the impeller is in the form of a cylindrical surface.

Claim 23

In a centrifugal pump as defined in claim 17 wherein said annular surface of the impeller is flat.

Claim 24

In a centrifugal pump as defined in claim 17 including a third rear face on said sealing ring between the first two mentioned rear faces, said seal means pressure isolating all of said rear faces from each other; and means communicating said third rear face with a source of control pressure.