Patent Description:
Aircraft engine cowls are used to allow aircraft engines to be serviced and can be fully opened by actuators and kept in the open position until a maintenance operation is completed, at which time they are closed. Hydraulic actuators are generally used for this purpose. Cowl doors are opened by fluid being supplied to the hydraulic actuators and the cowl doors are allowed to retract at a controlled rate under the weight of the cowl doors (i.e., the cowl load). Cowl loads are thus always compressive loads with respect to the hydraulic actuators. When the cowl doors are opened, hold-open-rods (HORs) are manually engaged and the hydraulic actuators are slightly retracted under the cowl load. During retraction, the cowl load is transferred onto the HOR thus relieving the hydraulic actuator of the load. Then, with no cowl load on the hydraulic actuator, the retraction halts and the hydraulic actuators act as secondary load path members.

Electro-mechanical actuators can replace existing hydraulic actuators and could be designed to power both extension and retraction operations. In such an architecture, after the extension sequence, when the cowl load is transferred to the HOR, the operator can continue to command the actuator to retract.

<CIT> discloses a system for controlling the movement of an aircraft engine cowl door including an actuator assembly having a housing and a screw shaft arranged at least partially within a hollow interior of the housing. A nut is engaged with the screw shaft and a piston rod having a rod end mounted thereto connecting the nut to the cowl door of the engine. The nut is translatable relative to the screw shaft to transition the cowl door between a first position and a second position.

<CIT> discloses a thrust reverser system actuator assembly that includes a torque limiter to limit the amount of torque that may be applied to the actuator assembly.

<CIT> discloses a telescopic actuator comprising a cylinder in which a main rod is mounted to slide telescopically along a sliding axis between a retracted position and an extended position.

<CIT> discloses an electric control system and method for operating the cowl doors of an aircraft engine that includes one or more electric motors that are energized to move the cowl doors to the open position. The motor is deenergized and the cowl doors are allowed to close under their own weight, driving the motor and causing it to operate as a generator. <CIT> discloses a cowl door actuator arranged between a head end and a rod end connected to a cowl door in an aircraft. The cowl door includes a piston rod that is axially moveable between the head end and the rod end.

<CIT> discloses a hold open rod including an inner tube assembly coupled to an outer tube assembly, the inner tube assembly movable within the outer tube assembly, a lock body coupled to the outer tube assembly, and an inner collar coupled to the lock body, the inner collar having a lock groove and unlock groove.

According to an aspect of the disclosure, an actuator assembly for a cowl door is provided. The actuator assembly includes a housing, an actuator configured to drive cowl door extension and cowl door retraction and to support the cowl door during the cowl door extension and the cowl door retraction wherein the actuator includes a sleeve coupled with the cowl door and including first and second bearing supports, a nut including a flange for engagement with the first bearing supports to drive cowl door extension and with the second bearing supports to drive cowl door retraction and a screw shaft on which the nut is threadably engaged. The screw shaft is rotatable to drive the nut such that the flange engages with the first or second bearing supports, respectively, to drive the cowl door extension or the cowl door retraction, respectively. The actuator assembly also includes a clutch assembly interposed between the actuator and the housing wherein the clutch assembly includes a gear head, a friction disc pack interposed between the gear head and a screw shaft of the actuator and an elastic element interposed between the gear head and the housing. When the cowl door loads the actuator, the gear head impinges against the housing and, when the cowl door does not load the actuator, the elastic element forms a gap between the gear head and the housing. The clutch assembly is configured to engage a capability of the actuator to drive the cowl door retraction when the cowl door loads the actuator. The actuator assembly also includes a hold-open-rod (HOR) to support the cowl door once the cowl door is at least partially extended. The clutch assembly is configured such that a capability of the actuator to drive the cowl door retraction when the HOR supports the cowl door is limited to a preload level of the clutch assembly.

In accordance with additional or alternative embodiments, the actuator includes an electro-mechanical (EM) actuator.

In accordance with additional or alternative embodiments, the actuator assembly further includes a motor and a gear head to drive operations of the actuator.

In accordance with additional or alternative embodiments, the sleeve is externally threaded and the nut is internally threaded.

In accordance with additional or alternative embodiments, one or more sliding fit joints are supportively interposed between the housing and the sleeve.

In accordance with additional or alternative embodiments, the cowl door is opened by the actuator driving the cowl door extension. The HOR is manually engaged and the actuator drives the cowl door retraction until the HOR supports the cowl door.

According to an aspect of the disclosure, a method of operating an actuator assembly of a cowl door is provided. The method includes activating an actuator to drive cowl door extension, engaging a hold-open-rod (HOR), activating the actuator to drive cowl door retraction until the cowl door is supported by the HOR and reducing a capability of the actuator to drive the cowl door retraction when the cowl door is supported by the HOR.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed technical concept. For a better understanding of the disclosure with the advantages and the features, refer to the description and to the drawings.

With a cowl door rested on an HOR after the cowl door is opened and the HOR is manually engaged, an electro-mechanical (EM) actuator can continue to retract automatically or on command. This could forcibly pull the HOR-restrained cowl door towards closure. As a result, the EM actuator could exert a stall load onto the cowl door which will be transferred to the HOR. Thus, the HOR needs to be sized to be sized to be robust against the cowl load and the additional load generated by the EM actuator.

As will be described below, a cowl door assembly is provided with a gain-based friction disc clutch that drives the actuator when compressive load exists. When the load is moved off and onto an HOR, the actuator capability is limited to a preload on a clutch pack. This results in reduced axial load capability of actuator which in turn results in reduced compressive force being applied by the cowl door onto the HOR. The HOR can therefore be reduced in sized as it no longer needs to be capable of bearing the weight of the cowl door and the additional load generated by the actuator.

With reference to <FIG>, an actuator assembly <NUM> is provided for driving an extension of a cowl door <NUM>, for driving a retraction of the cowl door <NUM> and for supporting a weight of the cowl door <NUM> during the extension and the retraction of the cowl door <NUM>.

As shown in <FIG>, the actuator assembly <NUM> includes a housing <NUM>, an actuator <NUM>, a clutch assembly <NUM> and an HOR <NUM>. The actuator <NUM> includes a sleeve <NUM>, a nut <NUM> and a screw shaft <NUM>. The sleeve <NUM> is coupled with the cowl door <NUM>. The sleeve <NUM> includes first bearing supports <NUM> that are proximate to the cowl door <NUM> and second bearing supports <NUM> that are remote from the cowl door <NUM>. The nut <NUM> is internally threaded and includes a flange <NUM> that is disposed for engagement with the first bearing supports <NUM> to drive an extension of the cowl door <NUM> and with the second bearing supports <NUM> to drive a retraction of the cowl door <NUM>. The screw shaft <NUM> is externally threaded and the nut <NUM> can be threadably engaged with the screw shaft <NUM>. The screw shaft <NUM> is rotatable relative to the housing <NUM>, the cowl door <NUM> and the sleeve <NUM> to drive the nut <NUM> in an extension direction or a retraction direction. When the screw shaft <NUM> is rotated such that the nut <NUM> is driven in the extension direction, the flange <NUM> engages with the first bearing supports <NUM> to drive the sleeve <NUM> in the extension direction and thus to drive the extension of the cowl door <NUM>. Conversely, when the screw shaft <NUM> is rotated such that the nut <NUM> is drive in the retraction direction, the flange <NUM> engages with the second bearing supports <NUM> to drive the sleeve <NUM> in the retraction direction and thus to drive the retraction of the cowl door <NUM>. The clutch assembly <NUM> is interposed between the actuator <NUM> and the housing <NUM>. The clutch assembly <NUM> is configured to engage a capability of the actuator <NUM> to drive the retraction of the cowl door <NUM> when the cowl door <NUM> compressively loads the actuator <NUM>.

The HOR <NUM> can be manually engaged to support the cowl door <NUM> once the cowl door <NUM> is at least partially extended by the actuator <NUM> or otherwise. That is, the cowl door <NUM> is opened by the actuator <NUM> driving the extension of the cowl door <NUM>, the HOR <NUM> being manually engaged and the actuator <NUM> subsequently driving the retraction of the cowl door <NUM> until the HOR <NUM> supports the cowl door <NUM> (about <NUM>" of retraction). At this point, if the actuator <NUM> were to continue to drive retraction of the cowl door <NUM>, the actuator <NUM> will be effectively prevented from doing so. This is because the clutch assembly <NUM> is configured such that a capability of the actuator <NUM> to drive the retraction of the cowl door <NUM> when the HOR <NUM> already supports the cowl door <NUM> is limited to a preload level of the clutch assembly <NUM>.

A situation in which the actuator <NUM> is made to attempt to drive the retraction of the cowl door <NUM> when the HOR already supports the cowl door <NUM> can occur when an operator mistakenly commands the actuator <NUM> to retract the cowl door <NUM> while the HOR <NUM> is in place. In these or other cases, the clutch assembly <NUM> effectively reduces a capability of the actuator <NUM> to retract the cowl door <NUM>. As a result, the HOR <NUM> can be sized to support the weight of the cowl door <NUM> but need not be sized to support the additional weight associated with the actuator <NUM> retracting the cowl door <NUM> onto the HOR <NUM>. Thus, the HOR <NUM> can be reduced in size and weight, which can have an effect of reducing an overall size and weight of the corresponding engine nacelle.

With reference to <FIG>, further details of the actuator <NUM> and the clutch assembly <NUM> will now be described. As shown in <FIG>, the actuator <NUM> can include or be provided as an electro-mechanical (EM) actuator and the actuator <NUM> can include a motor <NUM> and a gear head <NUM> to drive operations of the actuator <NUM>. The actuator assembly <NUM> can further include one or more sliding fit joints <NUM> (see <FIG>) that are supportively interposed between the housing <NUM> and the sleeve <NUM>. The clutch assembly <NUM> includes a gear head <NUM>, which can be coupled with or otherwise connected to the gear head <NUM>, a friction disc pack <NUM> that is interposed between the gear head <NUM> and the screw shaft <NUM> and an elastic element <NUM>, such as a preloaded spring, which is interposed between the gear head <NUM> and an insert feature <NUM> of the housing <NUM>. When the cowl door <NUM> compressively loads the actuator <NUM>, the gear head <NUM> impinges against the insert feature <NUM> of the housing <NUM>. This permits the transmission of torque from the clutch assembly <NUM> to and through the actuator <NUM>. Conversely, when the cowl door <NUM> does not compressively load the actuator <NUM>, the elastic element <NUM> forms a gap <NUM> between the gear head <NUM> and the insert feature <NUM> of the housing <NUM> and no torque is transmitted from the clutch assembly <NUM> to the actuator <NUM>.

With reference to <FIG>, it is apparent that actuator load is reduced as a result of the embodiments described herein and that, while a conventional actuator would stall once the cowl door <NUM> is supported by the HOR <NUM> in a case where the conventional actuator is commanded (mistakenly or otherwise) to continue to retract the cowl door <NUM> in a conventional assembly, the reduced load of the actuator <NUM> in the present invention avoids this result. As used herein, the term "stall" refers to the actuator <NUM> no longer translate because it is restrained by the cowl door <NUM> which in turn is held by the HOR <NUM>.

With reference to <FIG>, a method of operating an actuator assembly of a cowl door as described above is provided. As shown in <FIG>, the method includes activating an actuator to drive cowl door extension (<NUM>), engaging an HOR manually or otherwise (<NUM>), activating the actuator to drive cowl door retraction until the cowl door is supported by the HOR (<NUM>) and reducing a capability of the actuator to drive the cowl door retraction when the cowl door is supported by the HOR (<NUM>).

Technical effects and benefits of the present disclosure are the provision of a cowl door assembly that eliminates the use of electronic intelligence to sense cowl or actuator position to override operator input and reduces an overall weight of a nacelle as HORs can be sized for cowl loads only.

The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the technical concepts in the form disclosed. The embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.

Claim 1:
An actuator assembly (<NUM>) for a cowl door (<NUM>), the actuator assembly (<NUM>) comprising:
a housing (<NUM>);
an actuator (<NUM>) configured to drive cowl door (<NUM>) extension and cowl door (<NUM>) retraction and to support the cowl door (<NUM>) during the cowl door (<NUM>) extension and the cowl door (<NUM>) retraction, wherein the actuator (<NUM>) comprises:
a sleeve (<NUM>) configured to be coupled with the cowl door (<NUM>) and comprising first (<NUM>) and second bearing supports (<NUM>);
a nut (<NUM>) comprising a flange (<NUM>) for engagement with the first bearing supports (<NUM>) to drive cowl door (<NUM>) extension and with the second
bearing supports (<NUM>) to drive cowl door (<NUM>) retraction; and
a screw shaft (<NUM>) on which the nut is threadably engaged, the screw shaft (<NUM>) being rotatable to drive the nut (<NUM>) such that the flange (<NUM>) engages with the first (<NUM>) or second bearing supports (<NUM>), respectively, to drive the cowl door (<NUM>) extension or the cowl door (<NUM>) retraction, respectively;
a clutch assembly (<NUM>) interposed between the actuator (<NUM>) and the housing (<NUM>), wherein the clutch assembly (<NUM>) comprises:
a gear head (<NUM>);
a friction disc pack (<NUM>) interposed between the gear head (<NUM>) and a screw shaft (<NUM>) of the actuator (<NUM>); and
an elastic element <NUM> ) interposed between the gear head (<NUM>) and the housing (<NUM>),
wherein, when the cowl door (<NUM>) loads the actuator (<NUM>), the gear head (<NUM> ) impinges against the housing (<NUM>), and, when the cowl door (<NUM>) does not load the actuator (<NUM>), the elastic element (<NUM>) forms a gap (<NUM>) between the gear head (<NUM>) and the housing (<NUM>), and the clutch assembly (<NUM>) being configured to engage a capability of the actuator (<NUM>) to drive the cowl door (<NUM>) retraction when the cowl door (<NUM>) loads the actuator (<NUM>); and
a hold-open-rod (<NUM>) to support the cowl door (<NUM>) once the cowl door (<NUM>) is at least partially extended,
wherein
the clutch assembly (<NUM>) is configured such that a capability of the actuator (<NUM>) to drive the cowl door (<NUM>) retraction when the hold-open-rod (<NUM>) supports the cowl door (<NUM>) is limited to a preload level of the clutch assembly (<NUM>).