Compressor or turbine with back-disk seal and vent

Abstract

A turbine or compressor wheel mounted in a housing. The wheel is carried on two radial bearings both mounted in a wall of the housing. The wall has a venting orifice that is not impeded by moving parts such as bearings. The wall also has a circular seal member extending toward a back-disk of the wheel with only a very small clearance. The seal member is composed of a material significantly softer than the material of the wheel.

Claims

1. A turbocharger, comprising: a bearing housing; one or more bearing orifices opening into an interior chamber of the bearing housing, each bearing orifice of the one or more bearing orifices being centered along an axis of rotor rotation, and each bearing orifice of the one or more bearing orifices containing one or more bearings of a plurality of bearings; and a rotor extending through the bearing orifices to pass through the interior chamber of the bearing housing, the rotor being radially restrained by the one or more bearings within the bearing orifices to allow rotation of the rotor along the axis of rotor rotation, the rotor including a rotational pressure-changing wheel outside the interior chamber of the bearing housing, the pressure-changing wheel forming a hub and a plurality of blades, the plurality of blades being positioned to exchange the pressure of gas passing through the blades and rotor kinetic rotational energy, and the hub forming a blade surface that carries and supports the blades, and a back-disk on an axially opposite side of the hub from the blade surface; wherein the bearing housing forms a chamber wall facing the back-disk, the chamber wall and back-disk defining a back-disk chamber, the chamber wall separating the back-disk chamber from the interior chamber of the bearing housing; wherein the chamber wall forms a first bearing orifice of the one or more bearing orifices, the first bearing orifice extending between the back-disk chamber and the interior chamber of the bearing housing; wherein the chamber wall forms an off-center vent orifice extending between the back-disk chamber and the interior chamber of the bearing housing to vent pressure differences across the first bearing orifice through a path unobstructed by the plurality of bearings, the off-center vent orifice not being impeded by moving parts, and the off-center vent orifice being offset from the axis of rotation and separate from the first bearing orifice; and wherein the back-disk chamber forms an annular passageway between the gas passing between the blades and the off-center vent orifice.

2. The turbocharger of claim 1, wherein the turbocharger operates over a range of operating pressures, and wherein the effective size of the off-center vent orifice limits a pressure change of the back-disk chamber through the off-center vent orifice with the turbocharger operating over the range of operating pressures.

3. The turbocharger of claim 1, and further comprising: a back-disk seal member, the back-disk seal member extending substantially between the back-disk and the chamber wall, the back-disk seal member extending circumferentially around the back-disk chamber; wherein the chamber wall is axially supported around its radial periphery, and wherein the back-disk seal member extends from the chamber wall within the radial periphery in which the chamber wall is axially supported.

4. The turbocharger of claim 3, wherein the back-disk seal member forms a plurality of separate sub-protrusions, each separate sub-protrusion extending around the circumference of the rotor at a plurality of radial locations.

5. The turbocharger of claim 4, wherein the plurality of separate sub-protrusions includes at least three separate sub-protrusions extending around the circumference of the rotor at a plurality of radial locations.

6. The turbocharger of claim 5, wherein the turbocharger operates over a range of operating pressures, and wherein the effective size of the off-center vent orifice limits a pressure change of the back-disk chamber through the off-center vent orifice with the turbocharger operating over the range of operating pressures.

7. The turbocharger of claim 3, wherein the back-disk seal member is affixed to and extends from the chamber wall toward the back-disk, and wherein the chamber wall radially supports a first radial-support bearing of the plurality of bearings at a first axial location in the first bearing orifice, and a second radial-support bearing of the plurality of bearings at a second axial location in the first bearing orifice.

8. The turbocharger of claim 7, wherein the back-disk seal member forms a plurality of separate sub-protrusions, each separate sub-protrusion extending around the circumference of the rotor and toward the back-disk at a plurality of radial locations.

9. The turbocharger of claim 8, wherein the plurality of separate sub-protrusions includes at least three separate sub-protrusions extending around the circumference of the rotor at a plurality of radial locations.

10. The turbocharger of claim 9, wherein the turbocharger operates over a range of operating pressures, and wherein the effective size of the off-center vent orifice limits a pressure change of the back-disk chamber through the off-center vent orifice with the turbocharger operating over the range of operating pressures.

11. A turbocharger, comprising: a bearing housing forming a chamber wall defining a boundary of an interior chamber within the bearing housing, wherein the chamber wall forms a bearing orifice extending through the chamber wall into the interior chamber; a rotor radially extending through the bearing orifice, and being restrained within the bearing housing along an axis of axial rotor rotation, the rotor including a rotational pressure-changing wheel outside the bearing housing, the pressure-changing wheel forming a hub and a plurality of blades, the plurality of blades being positioned to exchange the pressure of gas passing through the blades and rotor kinetic rotational energy, the hub including a blade surface that carries and supports the blades, and the hub further including a back-disk on an axially opposite side of the hub from the blade surface, wherein the bearing housing chamber wall faces the back-disk, the chamber wall and back-disk defining a back-disk chamber, the chamber wall separating the back-disk chamber from the interior chamber; and a back-disk seal member, the back-disk seal member extending from the chamber wall toward the back-disk between the back-disk and the chamber wall, the back-disk seal member extending circumferentially around the back-disk chamber; wherein the chamber wall is axially supported around its radial periphery, and wherein the back-disk seal member extends from the chamber wall within the radial periphery in which the chamber wall is axially supported; wherein the chamber wall forms a first flange around the bearing orifice, the first flange axially extending the bearing orifice; and wherein the chamber wall radially supports the rotor with a first radial-support bearing at a first axial location, and with a second radial-support bearing at a second axial location, the first axial location being within the first flange.

12. The turbocharger of claim 11, wherein the back-disk seal member is affixed to and seated in a circumferential groove in the chamber wall.

13. The turbocharger of claim 11, wherein the back-disk seal member forms a plurality of separate sub-protrusions, each separate sub-protrusion extending around the circumference of the rotor at a plurality of radial locations.

14. The turbocharger of claim 13, wherein the plurality of separate sub-protrusions includes at least three separate sub-protrusions extending around the circumference of the rotor at a plurality of radial locations.

15. The turbocharger of claim 11, wherein the back-disk seal member is composed of a material softer than the material of the hub.

16. The turbocharger of claim 15, wherein the back-disk seal member forms a plurality of separate sub-protrusions, each separate sub-protrusion extending around the circumference of the rotor at a plurality of radial locations.

17. The turbocharger of claim 16, wherein the plurality of separate sub-protrusions includes at least three separate sub-protrusions extending around the circumference of the rotor at a plurality of radial locations.

18. The turbocharger of claim 11, wherein the first flange axially extends the bearing orifice toward the internal chamber.

19. The turbocharger of claim 18, wherein the chamber wall forms a second flange around the bearing orifice, wherein the second flange axially extends the bearing orifice away from the internal chamber, and wherein the second axial location is within the second flange.

20. The turbocharger of claim 11, wherein: the chamber wall forms a second flange around the bearing orifice, the second flange axially extending the bearing orifice away from the first flange; the second axial location is within the second flange; and the chamber wall radially supports the rotor with a third radial-support bearing at a third axial location, the third axial location being within the first flange.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a cross-sectional view of a turbine or compressor wheel mounted to a wall of a bearing housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(2) The invention summarized above and defined by the enumerated claims may be better understood by referring to the following detailed description, which should be read with the accompanying drawings. This detailed description of particular preferred embodiments of the invention, set out below to enable one to build and use particular implementations of the invention, is not intended to limit the enumerated claims, but rather, it is intended to provide particular examples of them.

(3) Typical embodiments of the present invention reside in a rotary machine equipped with a rotational pressure-changing wheel (e.g., a compressor wheel or a turbine wheel) having adaptations that limit and/or tune the axial forces produced by that wheel during normal operational conditions (i.e., over a range of operating conditions for which the wheel was designed to operate).

(4) With reference to FIG. 1, in a first embodiment of the invention, a rotary machine is formed from a housing 101 and a rotor 103. The rotor is configured to rotate within the housing along an axis of rotor rotation 105. The rotor includes a rotational pressure-changing wheel 107 (e.g., a compressor wheel or a turbine wheel) configured with a hub 111 and a plurality of blades 113.

(5) The blades 113 are configured to exchange energy between the potential energy of the pressure of a stream 115 of gas passing through the blades and rotor 103 kinetic rotational energy. For example, if the wheel 107 is a compressor wheel, the wheel may be configured to take ambient air and pressurize it using the rotational kinetic energy of the rotor. Similarly, if the wheel is a turbine wheel, the rotor is configured to take pressurized air (such as an exhaust stream) and lower its pressure, converting its potential energy into kinetic energy of the rotor.

(6) The hub 111 includes a blade surface 121 on one axial side of the hub. The blade surface carries and supports the blades 113. The hub further includes a back-disk 123 (surface) on an axially opposite side of the hub from the blade surface. The back-disk faces a chamber wall 125 of a bearing housing, which is a sub-housing of the housing 101. The chamber wall in turn faces the back-disk. Between them, the chamber wall and back-disk define boundaries of a back-disk chamber 127, which is the clearance area between the back-disk and the chamber wall.

(7) The chamber wall 125 forms one or more off-center orifices 131 that open the back-disk chamber 127 into an interior chamber of the bearing housing with an environment having a different pressure from the back-disk chamber during normal operational conditions of the wheel. Typically, this environment is ambient pressure air. Preferably, each orifice is not impeded by moving parts such as bearing parts that can vary the resistance to the flow of gas through the orifice. More preferably, each orifice is a calibrated hole in the chamber wall. The one or more orifices are calibrated for a desired pressure drop between the back-disk chamber and the environment having a different pressure from the back-disk chamber during normal operational conditions. Thus, the effective size of the one or more orifices is selected to limit the pressure change of the back-disk chamber through the one or more orifices during normal operation. The pressure drop may therefore be tuned for a desired pressure level in the back-disk chamber.

(8) The rotary machine further includes a back-disk seal member 141 that extends substantially between the back-disk 123 and the chamber wall 125. The back-disk seal member preferably protrudes axially from the chamber wall and extends circumferentially around the back-disk chamber 127 forming a circularly symmetric protrusion that defines the radial extent (boundary) of the back-disk chamber.

(9) The back-disk seal member is composed of a material significantly softer than the materials of the hub and the chamber wall. If the back-disk seal member comes into contact with the opposing surface (e.g., the back-disk), it will immediately wear away without significantly affecting the performance of the rotary machine. This feature allows for the clearance between the back-disk seal member and the opposing surface to be extremely tight, Preferably, the back-disk seal member is composed of a plastic material that will be rapidly worn away if it comes in contact with an opposing surface (e.g., if it is mounted to the chamber wall and comes into contact with the metal of the hub back-disk, or if it is mounted to the back-disk and comes into contact with the metal of the chamber wall.

(10) The back-disk seal member 141 forms a plurality of separate circular axial sub-protrusions 143. Each separate sub-protrusion extends around the circumference of the rotor and toward the back-disk at a plurality of different radial locations. This feature allows for different amounts of wear on different sub-protrusions while minimizing the total pressure loss across the whole back-disk seal member.

(11) To minimize the clearance between the back-disk seal member and its opposing wall, and to minimize the wearing of the back-disk seal member, the chamber wall radially supports a first radial-support bearing 151 at a first axial location, and a second radial-support bearing 153 at a second axial location. The first and second radial-support bearings radially support the rotor while freely allowing it to rotate. The housing is adapted such that the chamber wall 125 is configured to off-axially flex during off-axis motion of the rotor. As such, the back-disk seal member 141 will deflect with off axis motion of the rotor. This feature will minimize contact between the back-disk seal member and its opposing surface (e.g., the back-disk), while minimizing the clearance distance between the two,

(12) While particular forms of the invention have been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention. Thus, although the invention has been described in detail with reference only to the preferred embodiments, those having ordinary skill in the art will appreciate that various modifications can be made without departing from the scope of the invention. Accordingly, the invention is not intended to be limited by the above discussion, and is defined with reference to the following claims.