US 8,011,885 B2Granted

Turbocharger sealing arrangement

AssigneeCummins Turbo Technologies Limited

InventorMatthew J. Purdey

Life of this patent

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Abstract

A turbocharger has a sealing arrangement between the turbocharger shaft and the bearing housing adjacent to the turbine and/or the compressor housings to restrict leaking of gas into the bearing housing. At least a pair of spaced sealing rings project from an annular surface of the bearing housing into corresponding annular recesses formed on the shaft. The trailing face of the second ring or the opposite surface of the recess has a plurality of radial grooves that define leak passages that serve to maintain a very small flow of gas from the turbine or compressor housing into the bearing housing. Alternatively there is a slot in the second ring to provide the leak passage. This ensures that there is a minimum gas flow so that a large pressure gradient is not applied across the second seal thereby avoiding wear, overheating and collapse of the ring.

Claims23

Dependent claims

A method for sealing a shaft of a turbocharger to a housing in which it is mounted for rotation about an axis so as to restrict gas flow across the sealing from a relatively high pressure area to a relatively low pressure area within the turbocharger, the method comprising the steps of arranging a plurality of axially spaced seals in sealing engagement with said housing so as to provide a restriction to gas flow and such that they project into recesses provided in the shaft by recess walls with axial and radial clearance to allow passage of gas across the seals from the high pressure to the low pressure area, the seals comprising a downstream seal that is closest to the low pressure area and an upstream seal, each seal being movable axially relative to its respective recess between a first position in which there is an axial clearance between said wall of the recess and the respective seal so as to allow gas to flow in the clearance past the seal from the high pressure area to the low pressure area and a second position in which the seal sealingly engages said wall so as to close said axial clearance, and allowing gas to leak through at least one leak flow passage associated with the downstream seal so as to permit gas to leak past the downstream seal in a direction towards the low pressure area when the seal is in said second position thereby maintaining a gas flow across the seals that is sufficient to ensure there is a pressure drop across the upstream seal, wherein the leak flow passage is provided by a slot in the downstream seal, the leak flow passage in the downstream seal being larger than that in any upstream seal.

A turbocharger comprising:

a turbocharger shaft rotatable about an axis;
a turbine wheel provided at one end of the shaft for rotation about said axis within a turbine housing;
a compressor wheel mounted to the other end of the shaft for rotation about said axis within a compressor housing;
the shaft being rotatable on at least one bearing assembly housed within a bearing housing located between the compressor housing and the turbine housing;
an annular passage defined between an inner surface of the bearing housing and said shaft, and between the bearing assembly and the compressor or turbine housing;
a seal arrangement in said annular passage, the arrangement comprising a downstream seal that is nearest to the bearing assembly and an upstream seal, each seal sealingly engaging said inner surface of the bearing housing and extending across the annular passage so as to provide a restriction to gas flow in said passage, the downstream seal being received in a downstream recess defined in the shaft and the upstream seal being received in an upstream recess defined in the shaft, each recess being defined in the shaft by a recess wall, each seal being movable axially relative to its respective recess between a first position in which there is an axial clearance between said wall of the recess and the respective seal so as to allow gas to flow in the clearance past the seal and a second position in which the seal sealingly engages said wall so as to close said axial clearance, wherein there is provided one or more leak passages associated with the downstream seal that permit(s) gas to leak past the downstream seal in a direction towards the bearing housing when the seal is in said second position, wherein said passage(s) associated with the downstream seal presents an effective total cross sectional area for gas flow in the annular passage that is greater than the effective total cross sectional area presented to the annular passage for gas flow by the upstream seal and/or by any such leak passages associated with the upstream seal when it is in the second position.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/631,817Filed 5 Dec 2009 · continuation
Priority: GB 0710911.97 Jun 2007
Published: US 2010/0143114 A110 Jun 2010
Granted: 6 Sep 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

F01D 11/001
Preventing or minimising internal leakage of working-fluid, e.g. between stages: for sealing space between stator blade and rotor
F16J 15/3272
Mounting of sealing rings: the rings having a break or opening, e.g. to enable mounting on a shaft otherwise than from a shaft end
F16J 15/441
Free-space packings: with floating ring
F16J 15/443
Free-space packings: provided with discharge channels