Drive-through friction clutch as a drawbar disconnect clutch

Description

TECHNICAL FIELD

[0001] The present disclosure relates to engine cowls and, more particularly, to a drive-through friction clutch as a tensile load disconnect for use in an engine cowl.BACKGROUND

[0002] 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.

[0003] 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.

[0004] US 2019 / 135447 A1 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.

[0005] US 2005 / 040284 A1 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.

[0006] US 2007 / 144846 A1 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.

[0007] US 2003 / 192987 A1 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. US 2020 / 063481 A1 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.

[0008] US 2015 / 267724 A1 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.BRIEF DESCRIPTION

[0009] 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.

[0010] In accordance with additional or alternative embodiments, the actuator includes an electro-mechanical (EM) actuator.

[0011] In accordance with additional or alternative embodiments, the actuator assembly further includes a motor and a gear head to drive operations of the actuator.

[0012] In accordance with additional or alternative embodiments, the sleeve is externally threaded and the nut is internally threaded.

[0013] In accordance with additional or alternative embodiments, one or more sliding fit joints are supportively interposed between the housing and the sleeve.

[0014] 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.

[0015] 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.

[0016] 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.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts: FIG. 1 is a schematic illustration of operations of an actuator assembly for a cowl door in accordance with embodiments; FIG. 2 is a side view of components of an actuator assembly under compressive loads in accordance with embodiments; FIG. 3 is a side view of components of an actuator assembly under no compressive loads in accordance with embodiments; FIG. 4 is a graphical depiction of actuator and hold-open-rod loads over time in conventional cases and in cases in accordance with embodiments; and FIG. 5 is a flow diagram illustrating a method of operating an actuation assembly in accordance with embodiments. DETAILED DESCRIPTION

[0018] 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.

[0019] 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.

[0020] With reference to FIG. 1, an actuator assembly 101 is provided for driving an extension of a cowl door 102, for driving a retraction of the cowl door 102 and for supporting a weight of the cowl door 102 during the extension and the retraction of the cowl door 102.

[0021] As shown in FIG. 1, the actuator assembly 101 includes a housing 110, an actuator 120, a clutch assembly 130 and an HOR 140. The actuator 120 includes a sleeve 121, a nut 122 and a screw shaft 123. The sleeve 121 is coupled with the cowl door 102. The sleeve 121 includes first bearing supports 1211 that are proximate to the cowl door 102 and second bearing supports 1212 that are remote from the cowl door 102. The nut 122 is internally threaded and includes a flange 1221 that is disposed for engagement with the first bearing supports 1211 to drive an extension of the cowl door 102 and with the second bearing supports 1212 to drive a retraction of the cowl door 102. The screw shaft 123 is externally threaded and the nut 122 can be threadably engaged with the screw shaft 123. The screw shaft 123 is rotatable relative to the housing 110, the cowl door 102 and the sleeve 121 to drive the nut 122 in an extension direction or a retraction direction. When the screw shaft 123 is rotated such that the nut 122 is driven in the extension direction, the flange 1221 engages with the first bearing supports 1211 to drive the sleeve 121 in the extension direction and thus to drive the extension of the cowl door 102. Conversely, when the screw shaft 123 is rotated such that the nut 122 is drive in the retraction direction, the flange 1221 engages with the second bearing supports 1212 to drive the sleeve 121 in the retraction direction and thus to drive the retraction of the cowl door 102. The clutch assembly 130 is interposed between the actuator 120 and the housing 110. The clutch assembly 130 is configured to engage a capability of the actuator 120 to drive the retraction of the cowl door 102 when the cowl door 102 compressively loads the actuator 120.

[0022] The HOR 140 can be manually engaged to support the cowl door 102 once the cowl door 102 is at least partially extended by the actuator 120 or otherwise. That is, the cowl door 102 is opened by the actuator 120 driving the extension of the cowl door 102, the HOR 140 being manually engaged and the actuator 120 subsequently driving the retraction of the cowl door 102 until the HOR 140 supports the cowl door 102 (about 2" of retraction). At this point, if the actuator 120 were to continue to drive retraction of the cowl door 102, the actuator 120 will be effectively prevented from doing so. This is because the clutch assembly 130 is configured such that a capability of the actuator 120 to drive the retraction of the cowl door 102 when the HOR 140 already supports the cowl door 102 is limited to a preload level of the clutch assembly 130.

[0023] A situation in which the actuator 120 is made to attempt to drive the retraction of the cowl door 102 when the HOR already supports the cowl door 102 can occur when an operator mistakenly commands the actuator 120 to retract the cowl door 102 while the HOR 140 is in place. In these or other cases, the clutch assembly 130 effectively reduces a capability of the actuator 120 to retract the cowl door 102. As a result, the HOR 140 can be sized to support the weight of the cowl door 102 but need not be sized to support the additional weight associated with the actuator 120 retracting the cowl door 102 onto the HOR 140. Thus, the HOR 140 can be reduced in size and weight, which can have an effect of reducing an overall size and weight of the corresponding engine nacelle.

[0024] With reference to FIGS. 2 and 3, further details of the actuator 120 and the clutch assembly 130 will now be described. As shown in FIGS. 2 and 3, the actuator 120 can include or be provided as an electro-mechanical (EM) actuator and the actuator 120 can include a motor 1201 and a gear head 1202 to drive operations of the actuator 120. The actuator assembly 101 can further include one or more sliding fit joints 150 (see FIG. 2) that are supportively interposed between the housing 110 and the sleeve 121. The clutch assembly 130 includes a gear head 131, which can be coupled with or otherwise connected to the gear head 1202, a friction disc pack 132 that is interposed between the gear head 131 and the screw shaft 123 and an elastic element 133, such as a preloaded spring, which is interposed between the gear head 131 and an insert feature 134 of the housing 110. When the cowl door 102 compressively loads the actuator 120, the gear head 131 impinges against the insert feature 134 of the housing 110. This permits the transmission of torque from the clutch assembly 130 to and through the actuator 120. Conversely, when the cowl door 102 does not compressively load the actuator 120, the elastic element 133 forms a gap 135 between the gear head 131 and the insert feature 134 of the housing 110 and no torque is transmitted from the clutch assembly 130 to the actuator 120.

[0025] With reference to FIG. 4, 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 102 is supported by the HOR 140 in a case where the conventional actuator is commanded (mistakenly or otherwise) to continue to retract the cowl door 102 in a conventional assembly, the reduced load of the actuator 120 in the present invention avoids this result. As used herein, the term "stall" refers to the actuator 120 no longer translate because it is restrained by the cowl door 102 which in turn is held by the HOR 140.

[0026] With reference to FIG. 5, a method of operating an actuator assembly of a cowl door as described above is provided. As shown in FIG. 5, the method includes activating an actuator to drive cowl door extension (501), engaging an HOR manually or otherwise (502), activating the actuator to drive cowl door retraction until the cowl door is supported by the HOR (503) and reducing a capability of the actuator to drive the cowl door retraction when the cowl door is supported by the HOR (504).

[0027] 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.

[0028] 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.

[0029] While the preferred embodiments to the disclosure have been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the disclosure first described.

Claims

1. An actuator assembly (101) for a cowl door (102), the actuator assembly (101) comprising: a housing (110); an actuator (120) configured to drive cowl door (102) extension and cowl door (102) retraction and to support the cowl door (102) during the cowl door (102) extension and the cowl door (102) retraction, wherein the actuator (120) comprises: a sleeve (121) configured to be coupled with the cowl door (102) and comprising first (1211) and second bearing supports (1212); a nut (122) comprising a flange (1221) for engagement with the first bearing supports (1211) to drive cowl door (102) extension and with the second bearing supports (1212) to drive cowl door (102) retraction; and a screw shaft (123) on which the nut is threadably engaged, the screw shaft (123) being rotatable to drive the nut (122) such that the flange (1221) engages with the first (1211) or second bearing supports (121), respectively, to drive the cowl door (102) extension or the cowl door (102) retraction, respectively; a clutch assembly (130) interposed between the actuator (120) and the housing (110), wherein the clutch assembly (130) comprises: a gear head (131); a friction disc pack (132) interposed between the gear head (131) and a screw shaft (123) of the actuator (120); and an elastic element 133 ) interposed between the gear head (131) and the housing (110), wherein, when the cowl door (102) loads the actuator (120), the gear head (131 ) impinges against the housing (110), and, when the cowl door (102) does not load the actuator (120), the elastic element (133) forms a gap (135) between the gear head (131) and the housing (110), and the clutch assembly (130) being configured to engage a capability of the actuator (120) to drive the cowl door (102) retraction when the cowl door (102) loads the actuator (120); and a hold-open-rod (140) to support the cowl door (102) once the cowl door (102) is at least partially extended, wherein the clutch assembly (130) is configured such that a capability of the actuator (120) to drive the cowl door (102) retraction when the hold-open-rod (140) supports the cowl door (102) is limited to a preload level of the clutch assembly (130).

2. The actuator assembly (101) according to claim 1, wherein the actuator (120) comprises an electro-mechanical (EM) actuator.

3. The actuator assembly (101) according to claim 1 or 2, further comprising a motor (1201) and a gear head (1202) to drive operations of the actuator (120).

4. The actuator assembly (101) according to any of claims 1, 2 or 3, wherein the sleeve (121) is externally threaded and the nut (122) is internally threaded.

5. The actuator assembly (101) according to any preceding claim, further comprising one or more sliding fit joints (150) supportively interposed between the housing (110) and the sleeve (121).

6. The actuator assembly (101) according to any preceding claim, wherein the actuator (120) driving the cowl door (102) extension is configured to open the cowl door (102), the hold-open-rod (140) being configured to be manually engaged and the actuator (120) being configured to drive the cowl door (102) retraction until the hold-open-rod (140) supports the cowl door (102).

7. A method of operating an actuator assembly (101) of a cowl door (102), the method comprising: activating (501) an actuator (120) to drive cowl door (102) extension, wherein the actuator (120) comprises: a sleeve (121) coupled with the cowl door (102) and comprising first (1211) and second bearing supports (1212); a nut (122) comprising a flange (1221) for engagement with the first bearing supports (1211) to drive cowl door (102) extension and with the second bearing supports (1212) to drive cowl door (102) retraction; and a screw shaft (123) on which the nut is threadably engaged, the screw shaft (123) being rotatable to drive the nut (122) such that the flange (1221) engages with the first (1211) or second bearing supports (121), respectively, to drive the cowl door (102) extension or the cowl door (102) retraction, respectively, wherein a clutch assembly (130) is interposed between the actuator (120) and a housing (110) of the actuator assembly (101), wherein the clutch assembly (130) comprises: a gear head (131); a friction disc pack (132) interposed between the gear head (131) and a screw shaft (123) of the actuator (120); and an elastic element (133) interposed between the gear head (131) and the housing (110), wherein, when the cowl door (102) loads the actuator (120), the gear head (131) impinges against the housing (110), and, when the cowl door (102) does not load the actuator (120), the elastic element (133) forms a gap (135) between the gear head (131) and the housing (110); engaging (502) a hold-open-rod (140) to support the cowl door (102) once the cowl door (102) is at least partially extended; activating (503) the actuator (120) to drive cowl door (102) retraction until the cowl door (102) is supported by the hold-open-rod (140); and reducing (504) a capability of the actuator (120) to drive the cowl door (102) retraction when the cowl door (102) is supported by the hold-open-rod (140), wherein the clutch assembly (130) is configured such that a capability of the actuator (120) to drive the cowl door (102) retraction when the hold-open-rod (140) supports the cowl door (102) is limited to a preload level of the clutch assembly (130).