Patent Description:
Environmental control systems (ECS) are utilized on various types of aircraft for several purposes, such as in cooling systems for the aircraft. For example, components of the ECS may be utilized to remove heat from various aircraft lubrication and electrical systems and/or used to condition aircraft cabin air. The cabin air conditioner includes one or more cabin air compressors (CACs) which compress air entering the system, from an outside source or from a ram air system. The compressed air is delivered to an environmental control system to bring it to a desired temperature, and then the compressed air is delivered to the aircraft cabin. After passing through the cabin, the air is typically exhausted to the outside. The CACs are typically driven by air-cooled electric motors, which are cooled by a flow of cooling air typically drawn by the ram air system. Conditions of the CAC, such as heating of the components therein during use, are controlled to extend a useful life of the CACs. <CIT> describes thermal and secondary flow management of electrically driven compressors. <CIT> describes a CAC with the features of the preamble of the independent claim.

Disclosed is a cabin air compressor (CAC) of an aircraft environmental control system according to claim <NUM>. The CAC includes inter alia: a CAC case defining a forward end and an aft end axially spaced apart axially from the forward end, wherein the forward end defines a compressor inlet; and a supplemental cooling passage defined by the CAC case, wherein the supplemental cooling passage is configured to direct a supplemental cooling medium through it.

A bearing cooling inlet channel is defined at the aft end of the CAC case, and an aft portion of the supplemental cooling passage surrounds the bearing cooling inlet channel.

The bearing cooling inlet channel is configured to direct cooling air toward a bearing supported within the CAC case.

In a preferred embodiment, the supplemental cooling medium is a liquid.

In a preferred embodiment, an inlet channel of the supplemental cooling passage is formed at the aft portion of the supplemental cooling passage, wherein the inlet channel is configured to direct the supplemental cooling medium into the supplemental cooling passage.

In a preferred embodiment, a forward portion the supplemental cooling passage is defined at a motor portion of the CAC case, wherein the motor portion of the CAC is axially along a rotor and stator of a motor supported within the CAC case.

In a preferred embodiment, the forward portion of the supplemental cooling passage defines a forward passage surrounding the motor portion of the CAC.

In a preferred embodiment, the aft portion of the supplemental cooling passage forms an aft passage surrounding the bearing cooling inlet channel.

In a preferred embodiment, the forward passage and the aft passage of the supplemental cooling passage extend along respective axes that are normal to each other.

In a preferred embodiment, an outlet channel for the supplemental cooling passage is defined at a forward end of the supplemental cooling passage, located adjacent a forward end of the motor portion of the CAC.

In a preferred embodiment, the inlet and the outlet channels respectively include quick release adaptors.

In a preferred embodiment, an inlet portion of the CAC extends aft of the forward end to a diffuser portion of the CAC; the diffuser portion extends aft of the inlet portion to a compressor rotor portion of the CAC; the compressor rotor portion extends aft of the diffuser portion to a forward bearing portion of the CAC; the forward bearing portion extends aft of the diffuser portion to a motor portion of the CAC; the motor portion extends aft of the diffuser portion to an aft bearing portion of the CAC; and the aft bearing portion extends aft of the motor portion to the aft end of the CAC, wherein the supplemental cooling passage extends from the aft bearing portion, and along the motor portion, toward the forward bearing portion of the CAC.

In a preferred embodiment, the supplemental cooling passage surrounds a stator of a motor supported in the motor portion and terminates aft of the forward bearing portion.

In a preferred embodiment, a forward journal bearing of the forward bearing portion is rotationally supported between a forward stationary member of the CAC case and a forward motor shaft operationally connected to a motor; and an aft journal bearing of the aft bearing portion is rotationally supported between an aft stationary member of the CAC case and an aft motor shaft operationally connected to the motor.

In a preferred embodiment, a thrust bearing of the aft bearing portion is rotationally supported between the aft end of the CAC case and the aft motor shaft.

In a preferred embodiment, an aircraft is disclosed, including aspects of the above disclosed CAC.

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

<FIG> illustrates an example of a commercial aircraft <NUM> having aircraft engines surrounded by (or otherwise carried in) a nacelle <NUM> housing therein a gas turbine engine. The aircraft <NUM> includes two wings <NUM> that can each include one or more slats <NUM> and one or more flaps <NUM>. The aircraft may further include ailerons <NUM>, spoilers <NUM>, horizontal stabilizer trim tabs <NUM>, horizontal stabilizer <NUM> and rudder <NUM>, and vertical stabilizer <NUM> (the tail structure being collectively referred to as an and empennage) each of which may be typically referred to as "control surfaces" as they are movable under aircraft power systems. The aircraft <NUM> may include an environmental control system (ECS) <NUM>, illustrated schematically, which conditions air that is delivered to the passenger cabin <NUM> of the aircraft <NUM>. The ECS <NUM> may receive compressed air from a cabin air compressor (CAC) <NUM>, as indicated above.

The components of a CAC <NUM> are shown in <FIG> and include a CAC case <NUM> extending from a case forward end <NUM> to a case aft end <NUM>, where the case aft end <NUM> is spaced apart from the case forward end <NUM> in an axial aft direction <NUM>. An inlet portion <NUM> (otherwise referred to as a compressor inlet portion), shown schematically, is defined by the CAC <NUM>, aft of the case forward end <NUM>. The inlet portion <NUM> extends in the axial aft direction <NUM> from the case forward end <NUM> to an add heat portion <NUM> of the CAC <NUM>. The inlet portion <NUM> of the CAC <NUM> receives, for example, air from outside the aircraft, e.g., from a ram air system of the aircraft <NUM>.

The add heat portion <NUM> is defined by the CAC <NUM>, aft of the inlet portion <NUM>. The add heat portion <NUM> extends in the axial aft direction <NUM> from the inlet portion <NUM> to a compressor rotor portion <NUM> of the CAC <NUM>.

The compressor rotor portion <NUM> is defined by the CAC <NUM>, aft of the add heat portion <NUM>. The compressor rotor portion <NUM> extends axially aft from the add heat portion <NUM> to a forward bearing portion <NUM>. A compressor rotor <NUM> is housed within the compressor rotor portion <NUM>. The compressor rotor <NUM> rotates about a compressor drive rod <NUM> (or center drive rod) that extends in the axial aft direction <NUM> from the compressor rotor <NUM>, toward the case aft end <NUM>, and rotates about a rotation axis <NUM> (or center rotation axis).

The forward bearing portion <NUM> is defined by the CAC <NUM>, aft of the compressor rotor portion <NUM>. The forward bearing portion <NUM> extends in the axial aft direction <NUM> from the compressor rotor portion <NUM> to a motor portion <NUM>. The compressor drive rod <NUM> extends axially through the forward bearing portion <NUM> of the CAC <NUM>. A forward motor shaft <NUM> within the forward bearing portion <NUM> supports the compressor drive rod <NUM> via a forward drive rod support <NUM> that extends in the radial outer direction <NUM> between the forward motor shaft <NUM> and compressor drive rod <NUM>. A forward journal bearing <NUM> (or forward motor support bearing) within the forward bearing portion <NUM> is rotationally positioned between a forward case structure <NUM> (stationary member) and the forward motor shaft <NUM>.

The motor portion <NUM> of the CAC <NUM> is defined by the CAC <NUM>, aft of the forward bearing portion <NUM>. The motor portion <NUM> extends in the axial aft direction <NUM>, from the forward bearing portion <NUM> to an aft bearing portion <NUM>. A motor <NUM>, including a motor stator <NUM> and a motor rotor <NUM>, is housed within the motor portion <NUM>. The motor stator <NUM> is radially exterior to and axially aligned with the motor rotor <NUM>. The compressor drive rod <NUM> extends axially through the motor portion <NUM> of the CAC <NUM> and is operationally connected to the motor rotor <NUM>, e.g., to drive the compressor rotor <NUM>.

The aft bearing portion <NUM> of the CAC <NUM> is defined by the CAC <NUM>, aft of the motor portion <NUM>. The aft bearing portion <NUM> extends in the axial aft direction <NUM>, from the motor portion <NUM> to the case aft end <NUM> of the CAC case <NUM>. The compressor drive rod <NUM> extends the axial aft direction <NUM>, into the aft bearing portion <NUM> of the CAC <NUM>. An aft motor shaft <NUM> (or thrust shaft) extends in the axial aft direction <NUM> from the motor rotor <NUM> to a thrust plate <NUM> at the case aft end <NUM> of the CAC case <NUM>. The aft motor shaft <NUM> supports the compressor drive rod <NUM> via an aft drive rod support <NUM> that extends in the radial outer direction <NUM> between the aft motor shaft <NUM> and compressor drive rod <NUM>. An aft journal bearing <NUM> is within the aft bearing portion <NUM>, rotationally supported between the aft motor shaft <NUM> and an aft support structure <NUM> (stationary member) of the CAC case <NUM>, thereby supporting the compressor drive rod <NUM>. A thrust bearing <NUM> engages the thrust plate <NUM> at the aft end of the CAC case <NUM>. The aft journal bearing <NUM> and thrust bearing <NUM> may together be considered aft motor support bearings.

A bearing cooling circuit <NUM> is defined in the CAC <NUM> for directing a bearing cooling flow <NUM> of air through the CAC <NUM>. The cooling air may also be from a primary heat exchanger of the aircraft or may be from a different source. The bearing cooling circuit <NUM> includes a bearing cooling inlet channel <NUM>, formed as an inlet passage in the aft bearing portion <NUM> of the CAC case <NUM>. A cooling outlet channel <NUM> is formed as an outlet passage in the forward bearing portion <NUM> of the CAC case <NUM>. The CAC <NUM> is configured so that bearing cooling flow <NUM> is directed around the thrust bearing <NUM>, over the aft journal bearing <NUM>, between the compressor drive rod <NUM> and the motor rotor <NUM>, over the forward journal bearing <NUM>, and out of the cooling outlet channel <NUM>. From there, the air may be directed overboard or utilized for other purposes. The bearing cooling inlet channel <NUM> may extend along a bearing cooling inlet channel axis <NUM> that is normal to the rotation axis <NUM> for the compressor rotor <NUM>. This configuration is not intended on limiting an orientation of the bearing cooling inlet channel <NUM>.

A motor cooling circuit <NUM> is defined in the CAC <NUM> for directing a motor cooling flow <NUM> of air through the CAC <NUM>. The motor cooling circuit <NUM> includes a motor cooling inlet channel <NUM> formed in the aft bearing portion <NUM> of the CAC <NUM>. The motor cooling inlet channel <NUM> receives the motor cooling flow <NUM> via a motor cooling duct <NUM> connected to a bleed channel <NUM> that is tapped off of the inlet portion <NUM> of the CAC <NUM>. The CAC <NUM> is configured so that motor cooling flow <NUM> is directed between the motor rotor <NUM> and motor stator <NUM>, between the motor stator <NUM> and the CAC case <NUM>, and out of the cooling outlet channel <NUM>. The motor cooling inlet channel <NUM> may extend along a motor cooling inlet channel axis <NUM> that is normal to the rotational axis <NUM> for the compressor rotor <NUM>, and e.g., parallel to bearing cooling inlet channel axis <NUM>. This configuration is not intended on limiting an orientation of the bearing cooling inlet channel <NUM>.

CAC motor reliability is dependent on the motor and bearings operating efficiently, meaning at least in part that the components are prevented from overheating. The CAC motor, as indicated above is cooled at least partially by cooling airflows, which under certain conditions may be insufficient to provide the desired cooling levels to the motor components. This may have a direct impact on system performance.

In view of the identified concerns, a supplemental cooling passage <NUM> is formed in the CAC case <NUM>. The supplemental cooling passage <NUM> is formed in an outer shell <NUM> of the CAC <NUM>. The supplemental cooling passage <NUM> extends from the aft bearing portion <NUM> to the motor portion <NUM> of the CAC <NUM>. The supplemental cooling passage <NUM> includes a forward portion <NUM>, which may be a forward passage, that is formed to surround the motor <NUM> in the motor portion <NUM>. The supplemental cooling passage <NUM> includes an aft portion <NUM>, which may be an aft passage, that is formed to surround the bearing cooling inlet channel <NUM>. The forward and aft portions <NUM>, <NUM> may be fluidly coupled via an intermediate portion <NUM> of the supplemental cooling passage <NUM> that is axially aligned with the motor cooling inlet channel <NUM>. The forward portion <NUM> and the aft portion <NUM> of the supplemental cooling passage <NUM> may be disposed on mutually normal axes. This is because, as indicated, the bearing cooling inlet channel <NUM> is normal to the rotation axis <NUM> of the motor <NUM>.

An inlet channel <NUM> for the supplemental cooling passage <NUM> is formed in the bearing cooling inlet channel <NUM>. An outlet channel <NUM> for the supplemental cooling passage <NUM> is formed aft of the forward bearing portion <NUM>. That is, the outlet channel <NUM> is formed in the motor portion <NUM>, at a forward end <NUM> (or axial forward end) of the forward portion <NUM>, e.g., adjacent a forward end <NUM> (or axial forward end) of the motor portion <NUM> of the CAC <NUM>. The inlet channel <NUM> and the outlet channel <NUM> for the supplemental cooling passage <NUM> may be configured with respective quick release adaptors <NUM>, <NUM>, to enable a quick release of respectively connected inlet and outlet conduits <NUM>, <NUM>.

A liquid flow, e.g., as a supplemental cooling medium <NUM>, may be flushed through the supplemental cooling passage <NUM> to further cool the bearing cooling flow <NUM> and the motor <NUM>, prolonging the useful life of the bearings and motor. For example, it is within the scope of the disclosure to utilize existing liquid cooling loops in an aircraft <NUM> to provide the liquid cooling flow to the CAC <NUM> to increase CAC reliability. Utilizing liquid loops as an additional source of cooling, e.g., to cool the bearing cooling flow <NUM> and cool the CAC case <NUM> around the motor <NUM>, may greatly reduce motor and bearing temperatures. With the above embodiments, a primary heat removal circuit includes heat being removed from the motor portion <NUM>, including the motor <NUM> therein, and the forward and aft bearing portions <NUM>, <NUM>, the bearings therein, including the forward and aft journal bearings <NUM>, <NUM>, and the thrust bearing <NUM>, via convection by the motor cooling flow <NUM>, and then by the motor cooling flow <NUM> being cooled by convection against the case <NUM>. In turn, the case <NUM> conducts heat to the supplemental cooling passage <NUM>, which removes heat by convection via fluid flowing in the supplemental cooling passage <NUM>.

Claim 1:
A cabin air compressor (CAC) of an aircraft environmental control system, the CAC comprising:
a bearing cooling circuit (<NUM>) defined in the CAC (<NUM>) for directing a bearing cooling flow (<NUM>) of air through the CAC (<NUM>), and a motor cooling circuit (<NUM>) defined in the CAC (<NUM>) for directing a motor cooling flow (<NUM>) of air through the CAC (<NUM>);
a CAC case (<NUM>) defining a forward end and an aft end axially spaced apart axially from the forward end, wherein the forward end defines a compressor inlet; wherein
a bearing cooling inlet channel (<NUM>) is defined at the aft end of the CAC case (<NUM>) and is configured to direct cooling air toward a bearing supported within the CAC case (<NUM>),
characterized in that
a supplemental cooling passage (<NUM>) is defined by the CAC case (<NUM>), wherein the supplemental cooling passage (<NUM>) is configured to direct a supplemental cooling medium through it; and wherein an aft portion (<NUM>) of the supplemental cooling passage (<NUM>) surrounds the bearing cooling inlet channel (<NUM>).