Air cycle machine turbine seal plate

A turbine seal plate includes an inner rim with a labyrinth seal land that defines a central bore having a labyrinth seal diameter. The turbine seal plate also includes a housing coupling ring arranged radially outward of the inner rim. A housing pilot extends axially from the housing coupling ring and substantially parallel to the labyrinth seal land with respect to a radially inner portion of the housing pilot. The housing pilot has a housing pilot thickness, and a ratio of the housing pilot thickness to the labyrinth seal diameter is between 0.08 and 0.14. A frusto-conical body extends between the radially inner portion of the housing pilot and the inner rim of the turbine seal plate.

BACKGROUND

The present disclosure generally relates to aircraft environmental control systems and, more particularly, to a turbine seal plate of an air cycle machine utilized as part of an aircraft environmental control system.

Conventional aircraft environmental control systems (ECS) incorporate an air cycle machine (ACM), also referred to as an air cycle cooling machine, for cooling and dehumidifying air supplied to an aircraft cabin. ACMs commonly include at least one turbine and a compressor spaced axially at intervals on a common shaft. The turbine(s) and compressor are supported for rotation about the axis of the shaft by one or more bearing assemblies.

On aircraft powered by turbine engines, the air to be conditioned in the air cycle machine is typically compressed air bled from one or more compressor stages of a turbine engine. In conventional systems, this bleed air is passed through the air cycle machine compressor, where it is further compressed, then passed through a condensing heat exchanger to cool the compressed air. The heat exchanger sufficiently condenses moisture thereby dehumidifying the air. The dehumidified compressed air is then expanded in one of the turbines to extract energy from the compressed air so as to drive the shaft and also to cool the expanded turbine exhaust air as it is supplied to the cabin as conditioned cooling air.

ACM components are typically sized to minimize leakage of pressurized airflow. In some instances, pressure differentials within the ACM can distort or deflect ACM components, which can result in excess rubbing of ACM components and reduced efficiency. Increasing clearances between ACM components can result in excess leakage and reduced thermodynamic performance.

BRIEF DESCRIPTION

According to one embodiment, a turbine seal plate includes an inner rim with a labyrinth seal land that defines a central bore having a labyrinth seal diameter. The turbine seal plate also includes a housing coupling ring arranged radially outward of the inner rim. A housing pilot extends axially from the housing coupling ring and substantially parallel to the labyrinth seal land with respect to a radially inner portion of the housing pilot. The housing pilot has a housing pilot thickness, and a ratio of the housing pilot thickness to the labyrinth seal diameter is between 0.08 and 0.14. A frusto-conical body extends between the radially inner portion of the housing pilot and the inner rim of the turbine seal plate.

According to another embodiment, an air cycle machine assembly is provided. The air cycle machine assembly includes a shaft, a turbine housing, a compressor housing, and a turbine seal plate. The turbine seal plate includes an inner rim with a labyrinth seal land that defines a central bore having a labyrinth seal diameter. The shaft forms a labyrinth seal with respect to the labyrinth seal land. The turbine seal plate also includes a housing coupling ring arranged radially outward of the inner rim, where the housing coupling ring is coupled to the turbine housing and the compressor housing. The turbine seal plate further includes a housing pilot that contacts the turbine housing and the compressor housing. The housing pilot extends axially from the housing coupling ring and substantially parallel to the labyrinth seal land with respect to a radially inner portion of the housing pilot. The housing pilot has a housing pilot thickness, and a ratio of the housing pilot thickness to the labyrinth seal diameter is between 0.08 and 0.14. A frusto-conical body of the turbine seal plate extends between the radially inner portion of the housing pilot and the inner rim.

A method of installing a turbine seal plate in an air cycle machine includes aligning a housing coupling ring of a turbine seal plate with a turbine housing and a compressor housing. A housing pilot of the turbine seal plate is placed in contact with the turbine housing and the compressor housing. The housing pilot extends axially from the housing coupling ring and substantially parallel to a labyrinth seal land with respect to a radially inner portion of the housing pilot. The turbine housing and the compressor housing are coupled to the turbine seal plate through the housing coupling ring. A shaft is arranged within an inner rim of the turbine seal plate to form a labyrinth seal with respect to the labyrinth seal land. The inner rim includes the labyrinth seal land that defines a central bore having a labyrinth seal diameter. A frusto-conical body extends between the radially inner portion of the housing pilot and the inner rim, and a ratio of a housing pilot thickness to the labyrinth seal diameter is between 0.08 and 0.14.

DETAILED DESCRIPTION

Referring now toFIG. 1, an air cycle machine (ACM)10includes a first turbine20, a second turbine40, and a compressor60. The ACM10includes a housing assembly12manufactured from multiple housing portions to provide a desired clearance for the compressor60and the turbines20,40. The ACM housing assembly12includes a first turbine housing22, a compressor housing62, and a second turbine housing42. The ACM housing assembly12also includes first and second turbine shrouds23and43, and a compressor shroud63. The first turbine housing22and the second turbine housing42are connected to the centrally located compressor housing62.

The first turbine20has an inlet24, a nozzle125, and an outlet26. The second turbine40has an inlet44, a nozzle145, and an outlet46. The compressor60also includes an inlet64, a diffuser165, and an outlet66. The compressor60is driven by the first and second turbines20and40. The first turbine20includes a first turbine rotor28, the second turbine40includes a second turbine rotor48, and the compressor60includes a compressor rotor68. The first and second turbine rotors28,48and the compressor rotor68are coupled to a shaft70for rotation about an axis A. In one embodiment, the shaft70is hollow and is supported within the ACM housing assembly12by bearings72, such as hydrodynamic journal bearings, for example. The shaft70may include a plurality of apertures (not shown) such that a cooling flow enters into the shaft70to cool the bearings72. Thrust bearings76are coupled to the shaft70to support axial loads in the ACM10.

A first seal plate80separates air flow between the first turbine20and the compressor60. A second seal plate90separates air flow between the compressor60and the second turbine40. The first seal plate80is coupled to the first turbine housing22and the compressor housing62. The second seal plate90is coupled to the second turbine housing42and the compressor housing62. The first seal plate80is also coupled to a thrust plate100to constrain axial movement of the thrust bearings76. A backing plate102may be installed between the diffuser165of the compressor60and the first seal plate80. A plurality of fasteners50, such as bolts, may be used to secure the seal plates80and90. The illustrated ACM10is an example and other configurations known to a person skilled in the art are within the scope of this disclosure. A combination of two or more components of the ACM10is referred to generally as an ACM assembly.

The second seal plate90in the example ofFIG. 1is also referred to as turbine seal plate90, as further described herein. An end portion170of shaft70interfaces with the turbine seal plate90to form a labyrinth seal190with respect to a labyrinth seal land202of the turbine seal plate90, as best seen inFIGS. 2 and 3.FIG. 2is a view of the turbine seal plate90of the ACM10ofFIG. 1according to an embodiment.FIG. 3is a cross-section of the turbine seal plate90taken along line B-B ofFIG. 2.FIG. 4is a detailed view of an area C of the turbine seal plate90as seen inFIG. 3.

In reference toFIGS. 1-4, the turbine seal plate90includes an inner rim200with the labyrinth seal land202that defines a central bore204having a labyrinth seal diameter D3of about 1.9685 inches (5.0 cm). The turbine seal plate90also includes a housing coupling ring206arranged radially outward of the inner rim200. The housing coupling ring206includes a plurality of apertures207through which fasteners50ofFIG. 1, such as bolts, can be secured. The housing coupling ring206is coupled to the turbine housing42and the compressor housing62. A housing pilot208extends axially from the housing coupling ring206and substantially parallel to the labyrinth seal land202with respect to a radially inner portion210of the housing pilot208. The housing pilot208has a housing pilot thickness D1of about 0.105 inches (0.2667 cm). A frusto-conical body212extends between the radially inner portion210of the housing pilot208and the inner rim200of the turbine seal plate90. In one embodiment, the frusto-conical body212has the shape of a cone with the narrow end, or tip, removed and has a conical angle of about 66 degrees.

The housing pilot208has a turbine housing pilot214defined by a first radially outer portion215of the housing pilot208having a turbine housing pilot diameter D2of about 7.8935 inches (20.05 cm). The turbine housing pilot214of the housing pilot208contacts the turbine housing42. The housing pilot208also includes a compressor housing pilot216defined by a second radially outer portion217of the housing pilot208having a compressor housing pilot diameter D4of about 7.876 inches (20.005 cm). The compressor housing pilot216of the housing pilot208contacts the compressor housing62. In an embodiment, a ratio of the housing pilot thickness D1to the labyrinth seal diameter D3is between 0.08 and 0.14. A ratio of the housing pilot thickness D1to the turbine housing pilot diameter D2is between 0.0101 and 0.0177. A ratio of the turbine housing pilot diameter D2to the labyrinth seal diameter D3is between 4.006 and 4.014. A ratio of the housing pilot thickness D1to the compressor housing pilot diameter D4is between 0.0102 and 0.0178. A ratio of the turbine housing pilot diameter D2to the compressor housing pilot diameter D4is between 1.001 and 1.003. A ratio of the labyrinth seal diameter D3to the compressor housing pilot diameter D4is between 0.249 and 0.251.

A process for installing the turbine seal plate90in the ACM10ofFIG. 1is described in reference toFIGS. 1-4. The sequence of assembly during installation of the turbine seal plate90in the ACM10can vary in embodiments. The process includes aligning a housing coupling ring206of the turbine seal plate90with a turbine housing42and a compressor housing62. A housing pilot208of the turbine seal plate90is placed in contact with the turbine housing42and the compressor housing62. The housing pilot208extends axially from the housing coupling ring206and substantially parallel to a labyrinth seal land202with respect to a radially inner portion210of the housing pilot208. The turbine housing42and the compressor housing62are coupled to the turbine seal plate90through the apertures207of the housing coupling ring206, e.g., using fasteners50, such as bolts. A shaft70(with end portion170) is arranged within an inner rim200of the turbine seal plate90to form a labyrinth seal190with respect to the labyrinth seal land202. Additional elements described with respect toFIG. 1can also be installed in the ACM10before or after installation of the turbine seal plate90.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate in spirit and/or scope. Additionally, while various embodiments have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.