BACKGROUND

The present disclosure is generally related to environmental control, and more particularly to air cycle machines for environmental control systems such as on vehicles.

Vehicles, such as aircraft, commonly employ environmental control systems with air cycle machines to provide conditioned air to environmentally controlled spaces on the vehicle. Such air cycle machines generally provide conditioned air using an air cycle conditioning process, typically by successively cooling, compressing, further cooling, and thereafter expanding the compressed air. Once conditioned the air is routed to the environmentally controlled spaces on the vehicle, where the conditioned air renews the atmosphere within the space by displacing a portion of the atmosphere from the space.

In some applications the overboard air flow displaced by the conditioned air is pressurized relative to the external environment external to the vehicle. In such applications a scavenging turbine can be employed to extract work from the overboard air flow prior to return of the overboard air flow environment external to the vehicle, limiting the energy required to operate the air cycle machine and improving efficiency of the air cycle machine. Routing the overboard air flow to and from the scavenging turbine is typically accomplished with external ducting. The external ducting is typically arranged outside the air cycle machine to route the overboard airflow exiting the scavenging turbine to an ambient air duct located within the air cycle machine.

Such systems and methods have generally been suitable for their intended purpose. However, there remains a need in the art for improved air cycle machines, environmental control systems, and methods of communicating fluid within air cycle machines.

BRIEF DESCRIPTION

An air cycle machine is provided. The air cycle machine includes a housing with an exterior wall defining therethrough an overboard air inlet, an ambient air inlet, and an ambient air outlet, a scavenging turbine arranged within the housing and supported for rotation about a rotation axis and in fluid communication with the overboard air inlet, and an ambient air fan. The ambient air fan is arranged within the housing, is supported for rotation about the rotation axis within the housing, and has a radially inner spoked portion and radially outer bladed portion. The bladed portion fluidly couples the ambient air inlet to the ambient air outlet and the spoked portion fluidly couples the scavenging turbine to the ambient air fan within the housing.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the ambient air fan includes an annular portion extending about the rotation axis, the radially outer bladed portion extending radially outward from the annular portion of the ambient air fan.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include a fan housing seated in the housing along the rotation axis and supporting the ambient air fan, the fan housing extending circumferentially about the radially outer bladed portion of the ambient air fan.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the fan housing defines an ambient air channel fluidly coupling ambient air inlet of the housing to the ambient air outlet of the housing, the radially outer bladed portion of the ambient air fan rotatably disposed within the ambient air channel.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the fan housing defines a turbine exhaust channel fluidly coupling the scavenging turbine to the ambient air outlet, the spoked portion of the ambient air fan rotatably disposed within the turbine exhaust channel.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the ambient air fan is fixed in rotation relative to the scavenging turbine.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the housing has an interior wall defining therethrough a turbine-fan port, the turbine-fan port fluidly coupling the scavenging turbine to the ambient air fan.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the interior wall divides an interior of the housing into a turbine chamber and a fan chamber, the turbine-fan port fluidly coupling the turbine chamber with the fan chamber.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the scavenging turbine is arranged within the turbine chamber.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the ambient air fan is arranged within the fan chamber.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include a shaft arranged within the housing and connecting the scavenging turbine to the ambient air fan.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include an expansion turbine arranged in the housing and fixed in rotation relative to the ambient air fan by the shaft.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include a compressor arranged within the housing and fixed in rotation relative to the ambient air fan by the shaft.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include an overboard air duct connected to the overboard air inlet defined by the exterior wall of the housing.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the air cycle machine has no ducting external to the housing fluidly coupling the scavenging turbine to the ambient air fan.

In addition to one or more of the features described above, or as an alternative, further examples of the air cycle machine may include that the scavenging turbine is a radial flow turbine, wherein the ambient air fan is an axial flow fan, and further comprising a bearing arrangement supporting the radial flow turbine and the axial flow fan for rotation about the rotation axis.

An environmental control system is also provided. The environmental control system includes an air cycle machine as described above, the housing has an interior wall defining therethrough a turbine-fan port, the turbine-fan port fluidly coupling the scavenging turbine to the ambient air fan; and wherein the air cycle machine has no ducting external to the housing fluidly coupling the scavenging turbine to the ambient air fan.

In addition to one or more of the features described above, or as an alternative, further examples of the environmental control system may include an expansion turbine arranged in the housing and fixed in rotation relative to the ambient air fan and a compressor arranged within the housing and fixed in rotation relative to the ambient air fan.

In addition to one or more of the features described above, or as an alternative, further examples of the environmental control system may include that the an environmentally controlled space fluidly coupled to the overboard air inlet defined by the housing of the air cycle machine and a compressed air source fluidly coupled by the environmentally controlled space by the overboard air inlet.

A fluid communication method is additionally provided. The method includes, at an air cycle machine as described above, receiving an overboard air flow at the overboard air inlet, receiving an ambient air flow at the ambient air inlet, and extracting work from the overboard air flow with the scavenging turbine. The ambient air fan is rotated using the work extracted by the scavenging turbine, the ambient air flow received at the ambient air inlet driven to the ambient air outlet with the radially outer bladed portion of the ambient air fan, and the overboard air flow communicated to the ambient air outlet through the radially inner spoked portion of the ambient air fan.

Technical effects of the present disclosure include air cycle machines that allow the use of turbines that exhaust directly into the ambient air fan circuit of the air cycle machine. In certain examples the present disclosure provides air cycle machines having relatively small rotative assembly length, allowing relatively higher speed operation and/or increased shaft system bending mode. In accordance with certain examples the present disclosure provides air cycle machines with relatively efficient turbine outlets and relatively small numbers of ducts and duct length. It is also contemplated that, in accordance with certain examples, air cycle machines described herein have relatively small size and/or which are lightweight.

