Patent Description:
On some aircraft, the cabin and/or other areas are pressurized by an electrically-driven cabin air compressor (CAC). The CAC takes in air flow at atmospheric pressure from outside the aircraft and compresses the airflow to a comfortable pressure for the aircraft cabin. This compressed air flow is then directed into the cabin.

In some operating conditions, erosion damage occurs to a bearing support housing downstream of the compressor impeller. This erosion damage occurs when foreign object particles bypass a labyrinth seal between the impeller and the bearing support housing and subsequently impact the bearing support housing. Such erosion of the bearing support housing shortens the service life of the bearing support housing specifically and the cabin air compressor in general. <CIT> describes an erosion mitigating two piece labyrinth seal mating ring.

In one embodiment of the claimed invention, a centrifugal compressor assembly includes an impeller rotatable about a central axis and a seal assembly. The seal assembly includes a labyrinth seal defining a seal interface with a sealing element of the impeller and a seal support ring into which the labyrinth seal is installed. The seal support includes a deflector ramp fluidly downstream of the seal interface. The deflector ramp is configured to turn an airflow leaking through the seal interface radially inwardly toward the central axis. A plurality of tortuous pathways are formed in a downstream surface of the seal support ring and are configured to diffuse a tangential component of the airflow.

Additionally, in this or other embodiments the plurality of tortuous pathways is circumferentially spaced.

According to the claimed invention, a tortuous pathway of the plurality of tortuous pathways includes a pathway inlet and a pathway outlet. The pathway inlet is located radially inboard of the pathway outlet.

According to the claimed invention, a tortuous pathway of the plurality of tortuous pathways is one of S-shaped, multiple S-shaped or Z-shaped.

Additionally, in this or other embodiments the labyrinth seal is formed from a first, relatively soft material and the seal support ring is formed from a second, relatively hard material.

Additionally, in this or other embodiments a shaft is operably connected to the impeller, and a bearing assembly includes a bearing supportive of the shaft and a bearing support housing into which the bearing assembly is installed. The seal support ring is located axially between the impeller and the bearing support housing.

Additionally, in this or other embodiments the deflector ramp deflects the airflow from impacting on the bearing support housing.

Additionally, in this or other embodiments the seal support ring is installed to the bearing support housing.

Additionally, in this or other embodiments the sealing element of the impeller is located at a sealing flange of the impeller extending axially from the impeller.

In another embodiment, a cabin air compressor includes a compressor housing having an inlet and an outlet, and a centrifugal impeller located in the housing. The impeller is rotatable about a central axis and is configured to compress an airflow directed through the inlet and direct the compressed airflow to the outlet. A seal assembly includes a labyrinth seal defining a seal interface with a sealing element of the impeller and a seal support ring into which the labyrinth seal is installed. The seal support includes a deflector ramp fluidly downstream of the seal interface. The deflector ramp is configured to turn an airflow leaking through the seal interface radially inwardly toward the central axis. A plurality of tortuous pathways are formed in a downstream surface of the seal support ring and configured to diffuse a tangential component of the airflow.

Additionally, in this or other embodiments a shaft is operably connected to the impeller. A bearing assembly includes a bearing supportive of the shaft and a bearing support housing into which the bearing assembly is installed. The seal support ring is located axially between the impeller and the bearing support housing.

Additionally, in this or other embodiments an electrical motor is operably connected to the shaft to drive rotation of the impeller about the central axis.

Additionally, in this or other embodiments the compressed airflow is directed from the outlet to a cabin of an aircraft.

A detailed description of one or more embodiments of the disclosed apparatus are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring now to <FIG>, illustrated is a schematic illustration of an embodiment of a cabin air compressor <NUM>. The cabin air compressor <NUM> includes a compressor housing <NUM> in which a compressor impeller <NUM> is located. The compressor impeller <NUM> is driven by a shaft <NUM>. The shaft <NUM>, in turn, is driven by a power source, which in some embodiments is an electric motor <NUM>. Airflow <NUM> at ambient pressure enters the cabin air compressor <NUM> at an inlet <NUM> and is urged across the compressor impeller <NUM> and compressed. The compressed airflow <NUM> then is directed through an outlet <NUM> to a selected location, for example, aircraft cabin <NUM>. The shaft <NUM> and compressor impeller <NUM> are supported by a bearing <NUM>, which is installed in a bearing support housing <NUM> located in the compressor housing <NUM>. A labyrinth seal <NUM> is located at an impeller outer perimeter <NUM> to prevent airflow from leaking past the impeller outer perimeter <NUM>. The labyrinth seal <NUM> is installed in and supported by a labyrinth seal mating ring <NUM> installed to the bearing support housing <NUM>. As will be discussed in greater detail below, this labyrinth seal mating ring <NUM> includes features to prevent erosion of the bearing support housing <NUM>.

Referring now to <FIG>, the labyrinth seal mating ring <NUM> is shown in more detail. The labyrinth seal mating ring <NUM> is a ring structure, having a ring outer surface <NUM>, which mates to the bearing support housing <NUM>. While illustrated as a complete ring, in some embodiments the labyrinth seal mating ring <NUM> may be a circumferentially segmented structure. The labyrinth seal <NUM> is located at a ring inner surface <NUM>, substantially opposite to the ring outer surface <NUM>. In some embodiments, the labyrinth seal mating ring <NUM> is formed from a relatively hard material, while the labyrinth seal <NUM> is formed from a relatively soft material.

Referring now to <FIG>, when installed, the labyrinth seal <NUM> is located at a corresponding impeller sealing surface <NUM> of the compressor impeller <NUM>. In some embodiments, the impeller sealing surface <NUM> is located at a sealing flange <NUM> extending from a downstream side <NUM> of the compressor impeller <NUM> opposite an upstream side <NUM> relative to the location of the inlet <NUM>. The labyrinth seal <NUM> and the impeller sealing surface <NUM> define a seal interface <NUM>. The labyrinth seal mating ring <NUM> includes a deflector ramp <NUM> extending radially inboard from the ring inner surface <NUM>. The deflector ramp <NUM> also extends radially inboard of a radial location of the seal interface <NUM>. In some embodiments, the deflector ramp <NUM> is curvilinear such as shown in <FIG>, while in other embodiments, the deflector ramp <NUM> may be another shape, such as linear or some combination of curvilinear and linear.

In operation, air flow <NUM> that leaks past the seal interface <NUM> as leakage airflow <NUM> is diverted radially inwardly by the deflector ramp <NUM>, to reduce impact of the leakage airflow <NUM> and any included particles or foreign objects on a support wall <NUM> of the bearing support housing <NUM>. Such diversion of the leakage airflow <NUM> by the deflector ramp <NUM> reduces erosion of the bearing support housing <NUM>.

The leakage airflow <NUM> typically has a significant tangential or circumferential velocity component due to rotation of the compressor impeller <NUM>. Referring now to <FIG>, illustrated is a downstream side <NUM> of the labyrinth seal mating ring <NUM>. The downstream side <NUM> includes a plurality of tortuous pathways <NUM> formed into the downstream side <NUM>. The plurality of tortuous pathways <NUM> are circumferentially spaced along the downstream side <NUM>, and in some embodiments are equally circumferentially spaced. The tortuous pathways <NUM> each have a pathway inlet <NUM> and a pathway outlet <NUM>, and ,according to the claimed invention, the pathway inlet <NUM> is located radially inboard of the pathway outlet <NUM>. According to the claimed invention, the tortuous pathway <NUM> extends between the pathway inlet <NUM> and the pathway outlet <NUM> with an S-shape, a multiple S-shape, a Z-shape.

In operation, the leakage airflow <NUM> at the downstream side <NUM> encounters the tortuous pathways <NUM>, and at least a portion of the leakage airflow <NUM> is diverted into the tortuous pathways <NUM> via the pathway inlets <NUM>. Along the tortuous pathway <NUM>, the leakage airflow <NUM> is slowed and diffused such that the velocity of the leakage airflow <NUM> is greatly reduced as the leakage airflow <NUM> exits the tortuous pathways <NUM> at their respective pathway outlets <NUM>.

The tortuous pathways <NUM> thereby reduce the tangential velocity component of the leakage airflow <NUM> to reduce the erosion of the bearing support housing <NUM>.

The labyrinth seal mating ring <NUM> described herein reduces erosion of the bearing support housing <NUM> of the cabin air compressor <NUM>, thus extending the service life of the bearing support housing <NUM> and the cabin air compressor <NUM> overall. Further, the labyrinth seal mating ring <NUM> is configured to be retrofittable into existing cabin air compressors <NUM>, without the need to modify surrounding components.

Claim 1:
A centrifugal compressor assembly, comprising:
an impeller (<NUM>) rotatable about a central axis; and
a seal assembly including:
a labyrinth seal (<NUM>) defining a seal interface with a sealing element of the impeller (<NUM>);
a seal support ring into which the labyrinth seal (<NUM>) is installed, the seal support including a deflector ramp (<NUM>) fluidly downstream of the seal interface, the deflector ramp (<NUM>) configured to turn an airflow leaking through the seal interface radially inwardly toward the central axis; and
a plurality of tortuous pathways formed in a downstream surface of the seal support ring and configured to diffuse a tangential component of the airflow;
characterized in that a tortuous pathway of the plurality of tortuous pathways includes a pathway inlet and a pathway outlet, the pathway inlet disposed radially inboard of the pathway outlet, and wherein a tortuous pathway of the plurality of tortuous pathways is one of S-shaped, multiple S-shaped or Z-shaped.