Patent Description:
Aircraft typically include movable control surfaces for directional control in flight. Known control surfaces include ailerons for roll control, elevators for pitch control, and rudders for yaw control. Additionally, various jet transport aircraft include leading edge slats and trailing edge flaps on the wings, which may be used to generate high lift during takeoff and landing when the aircraft is traveling at relatively low air speeds.

Power drive units (PDUs) are typically used to drive high lift surfaces on transport aircraft. Each surface is driven by two drive stations. A single drive line is routed from a PDU to actuators on both sides of the aircraft. In the event of a mechanical jam, or when the system is inadvertently driven into an over-travel stop, all the available PDU torque concentrates into the point of the jam. Torque limiters and torque brakes are often employed to limit the maximum amount of torque that may be delivered to specific points in the drive system.

In addition to local torque brakes at each actuator, half system torque brakes are sometimes used to limit the amount of torque delivered to one wing, thereby allowing a reduction in the size of drive line components between the PDU and the point of the jam. When an actual jam occurs at one or more points downstream of the half system torque brake, a second jam occurs in the drive line between the motor and the half system torque brake after the half system torque brake locks.

In general, a magnitude of the jam torque experienced by the drive system is equal to the stall torque of the primary mover (such as a hydraulic or electric motor) plus the torque supplied by the kinetic energy of the motor rotor. The kinetic torque is influenced by the driveline stiffness between the motor rotor and the point of the jam. With half system torque limiters, the distance between the motor and the torque brake is relatively short. Indeed, the two devices are typically mounted to the same housing. As such, the stiffness between the torque brake and the motor is relatively high, which leads to an induced kinetic torque to also be relatively high. Often, the kinetic torque approaches or exceeds the value of the motor stall torque. In order to reduce the magnitude of the kinetic torque, the motor rotor is decelerated over a period of time (generally, the longer the deceleration time, the less than magnitude of the kinetic torque). One method of decelerating the motor rotor is to introduce compliance in the drive line path between the motor and the torque brake.

Known half system torque brakes often utilize shock absorbers that include ring springs (also known as Fedder springs). With these shock absorbers, when torque in a first output shaft exceeds a predetermined level, a ball rolls up ramps machined into cam plates, thereby compressing Belleville springs and clamping brake plates. When the output shaft of the PDU stops rotating, substantial kinetic energy is still present in the motor rotor, which leads to additional kinetic torque that causes an input cam plate to continue to rotate with respect to an output cam and the ball to roll farther up the ramps. The continued motion of the ball causes the output cam to axially move, thereby compressing ring springs. In general, a shock absorber is operatively connected to each torque brake. Further, if the ring springs resonate, the cam plate may be susceptible to reversing direction and unlock the torque brake, thereby allowing excess torque to bleed through to the output shaft.

<CIT>, in accordance with its abstract, states that a first transmission component is axially supported in a second axial direction with respect to a hub. Through a third support arrangement the second transmission component is supported in the second axial direction with respect to the first transmission component.

<CIT>, in accordance with its abstract, states a torsional vibration damper for damping torsional vibrations, in particular in the drive train of motor vehicles, with a primary mass and a secondary mass is arranged coaxially to the primary mass and rotatable relative to the primary mass, which has at least one rolling element which couples the primary mass with the secondary mass, a first mass of primary mass or secondary mass has a first path oriented in the radial direction and the second mass of secondary mass or primary mass has an arcuately curved second path, the rolling element having two elements that can be rotated relative to one another, so that when the primary mass and secondary mass are rotated relative to one another, one of the elements of the rolling element rolls on the first track and the other of the elements of the rolling element rolls on the second track.

<CIT>, in accordance with its abstract, states an input damper for coupling to a torque-generating mechanism. The damper includes an outer cover, a hub, and a carrier assembly coupled to the hub. The carrier assembly is movably disposed within the cover. A clutch assembly moves between an engaged position and a disengaged position and is biased towards the engaged position. The input damper further includes an angular displacement mechanism operably coupled to the clutch assembly for moving the clutch assembly between the engaged position and disengaged position. The outer cover is coupled to the carrier assembly in the engaged position.

<CIT>, in accordance with its abstract, states that a drive assembly is operable to move control surfaces on wings of an aircraft. The drive assembly may include a gear reduction assembly which is driven by a pair of motors. The drive assembly has output members which are connected with the control surfaces on the wings of the aircraft. Torque limiting brake assemblies are operable between an engaged condition in which they are effective to prevent rotation of output members and a disengaged condition in which the brake assemblies are ineffective to prevent rotation of the output members. Actuator assemblies are connected with the torque limiting brake assemblies. The actuator assemblies are operable to effect operation of the torque limiting brake assemblies from a disengaged condition to an engaged condition in response to transmission of predetermined torques through the actuator assemblies to the output members. The drive assembly may also include one or more shock absorbing clutch assemblies which absorb the kinetic energy of the motors when the torque limiting brake assemblies are actuated to the engaged condition preventing rotation of the output members.

<CIT>, in accordance with its abstract, states a clutch disc with a torsional vibration damper, in which a control plate is used which, after a specified angle of rotation, comes into contact with the aperture of a spring element. Additional friction surfaces can be activated as a result of the presence of a control plate, which is capable of coming into contact on one of the components, i.e. the input part or the output part, with a friction element which is connected non-rotationally to the other of the two components.

As can be appreciated, using a shock absorber with respect to each torque limiter adds costs to the overall system. Further, each shock absorber includes numerous parts, such as the individual ring springs, thereby adding weight and expense to the system.

Accordingly, a need exists for a more efficient system and method of absorbing shocks within a PDU.

There is provided a shock absorber assembly according to claim <NUM>. The shock absorber assembly includes a first hub, a second hub, and a bull gear having at least a portion sandwiched between the first and second hubs. The bull gear is configured to rotate independently of the first and second hubs a controlled distance in response to a mechanical malfunction of the PDU. The first hub may be a mirror image of the second hub.

The shock absorber assembly also includes brake lining secured to one or more of the first hub, the second hub, and the bull gear. The brake lining provides a frictional interface between the bull gear and the first and/or second hubs. The brake lining provides a coefficient of friction that causes the bull gear to rotate along with the first and second hubs during normal operation of the PDU. The brake lining dissipates at least a portion of torque energy during the mechanical malfunction. In at least one embodiment, the brake lining may include one or more of engineered paper, asbestos-based brake lining material, bronze on steel, steel on steel, or paper on steel.

Each of the first hub, the second hub, and the bull gear may include a plurality of channels. The channels of the first hub align with the channels of the second hub and those of the bull gear. The channels retain force-resisting elements that are configured to dissipate at least a portion of torque energy during the mechanical malfunction. For example, the force-resisting elements may be or include helical springs.

The shock absorber assembly may also include one or more bearings. The bull gear may be rotatably secured to the bearing(s). At least one of the bull gear and the one or more bearings may include a shaft channel. The drive shaft is configured to be secured within the shaft channel.

The first and second hubs may be securely fixed together in order to prevent the first hub from rotating relative to the second hub. In contrast, the bull gear may include a plurality of fastener channels. Each of the fastener channels slidably retains a portion of a fastener that securely fastens the first hub to the second hub.

Certain embodiments of the present disclosure provide an aircraft that may include a fuselage, and wings securely fixed to the fuselage. Each of the wings includes a plurality of control surfaces, and a power drive unit (PDU) coupled to a drive shaft that is operatively coupled to one or more of the plurality of control surfaces. The PDU includes first and second torque brakes operatively coupled to the drive shaft. The aircraft also includes a shock absorber assembly operatively coupled to the drive shaft between the first and second torque brakes. The shock absorber assembly may include a first hub, a second hub, and a bull gear having at least a portion sandwiched between the first and second hubs. The bull gear is configured to rotate independently of the first and second hubs in response to a mechanical malfunction of the PDU.

The foregoing summary, as well as the following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural of the elements or steps, unless such exclusion is explicitly stated. Further, references to "one embodiment" are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments "comprising" or "having" an element or a plurality of elements having a particular property may include additional elements not having that property.

Embodiments of the present disclosure provide a shock absorber assembly that may include a bull gear having at least a portion sandwiched between two hubs, which may be lined with brake material. The bull gear may be mounted on a pair of rolling element bearings connected to the hubs. Torque may be transmitted from the bull gear to the hubs via helical compression springs, for example. The springs may be sized so that they do not bottom out when subjected to a stall torque plus a kinetic torque provided by the motor. The amount of damping may be controlled by a radius of the brake lining material between the bull gear and the hubs, and the clamping force therebetween.

In at least one embodiment, the damping (that is, the shock absorption) may be set to zero if desired (for example, no brake material or clamping pressure). The springs may be trapped in the assembly with simple covers to prevent migration within the PDU in the event of a spring failure.

Because the shock absorber assembly may be positioned within a load path of a PDU before it is split (such as between left and right wings), a single shock absorber assembly may be used, thereby reducing part count in comparison to previously known systems. The stiffness of the load path may be dominated by the spring stiffness and may not be affected by a coefficient of friction (in contrast to shock absorbers using ring springs).

Embodiments of the present disclosure do not require an additional degree of freedom for the torque brake input cam (for example, axial movement), thereby reducing the possibility of dynamic instability and providing a simple and efficient shock absorber assembly.

Certain embodiments of the present disclosure provide a shock absorber assembly that provides shock absorption or damping between a bull gear and hubs, such as through brake lining secured to interface surfaces of the bull gear and/or hubs. The shock absorber assembly may be configured to transmit a radial load component from the bull gear to the hub.

<FIG> illustrates a partially schematic, top perspective view of an aircraft <NUM> having a control surface drive system <NUM>, according to an embodiment of the present disclosure. The aircraft <NUM> may include a fuselage <NUM> and wings <NUM> (shown as first and second wings 106a and 106b) securely fixed to the fuselage <NUM>. Each wing <NUM> may include a number of movable control surfaces for controlling the aircraft <NUM> during flight. The control surfaces may include trailing edge flaps <NUM>, leading edge slats <NUM>, and ailerons <NUM>. The trailing edge flaps <NUM>, which are shown as an inboard flap 108a and an outboard flap 108b, are used for generating increased lift during takeoff and landing of the aircraft <NUM>.

The trailing edge flaps <NUM> may be powered by the control surface drive system <NUM>, which may include a drive shaft (not shown in <FIG>) that extends longitudinally inside the wings <NUM>, for example. The drive shaft may be coupled to a central power drive unit (PDU). One or more shock absorber assemblies, as described below, may be operatively connected to the drive shaft of the PDU, for example.

In operation, the control surface drive system <NUM> may move the flaps <NUM> between a retracted position (shown by solid lines) and an extended position (shown by dashed lines). In the extended position, aerodynamic forces may be exerted on the flaps <NUM>. The control surface drive system <NUM> is configured to hold the flaps <NUM> in the extended position against the aerodynamic forces without any input by the pilot of the aircraft <NUM>, even in the event of a general power failure. The control surface drive system <NUM> may be configured to lock the flaps <NUM> in the extended position, the retracted position, or any intermediate position therebetween against the aerodynamic forces, as described in <CIT>, entitled "Aircraft Control Surface Methods," which is hereby incorporated by reference in its entirety.

<FIG> illustrates a perspective front view of a shock absorber assembly <NUM>, according to an embodiment of the present disclosure. The shock absorber assembly <NUM> includes a bull gear <NUM> rotatably connected to a first hub <NUM> through a first bearing <NUM> (such as an outer or outboard bearing). The first hub <NUM> may be an outer or outboard hub (in relation to a central longitudinal axis <NUM> of the shock absorber assembly <NUM>). The bull gear <NUM> includes a main body <NUM> having an interior portion that is sandwiched between a portion of the first hub <NUM> and a portion of a second hub (hidden from view in <FIG>), such as an inner or inboard hub (in relation to the central longitudinal axis <NUM>). The first hub <NUM> and the second hub may be mirror images of one another and sandwich the interior portion of the bull gear <NUM> therebetween. That is, the shapes of the first and second hubs may mirror each other (not that one of the hubs is a literal mirror image of the other).

The bull gear <NUM> may be formed of metal. An outer annular edge <NUM> radially extends from the main body <NUM>. An upstanding annular ridge <NUM> may outwardly extend from the main body <NUM> inboard (that is, closer to the central longitudinal axis <NUM>) from the edge <NUM>. The annular ridge <NUM> may define an inboard recessed area within the main body <NUM> that in which the first bearing <NUM> is positioned between an interior surface of the ridge <NUM> and an exterior annular edge <NUM> of the first hub <NUM>. The main body <NUM> of the bull gear <NUM> may also be slidably supported by a second bearing <NUM> (such as an interior or inboard bearing) having a circumferential base <NUM>, which may be disposed between the first hub <NUM> and an inner collar <NUM> of the bull gear <NUM>.

A shaft channel <NUM> is formed through the inner collar <NUM>. The shaft channel <NUM> is configured to securely connect to an outer surface of a drive shaft <NUM> of a PDU. The bull gear <NUM>, the bearing <NUM>, the first hubs <NUM>, the second hub, and the bearing <NUM> may be concentric with the central longitudinal axis <NUM> of the shock absorber assembly <NUM>. That is, the central longitudinal axes of the bull gear <NUM>, the bearing <NUM>, the first hub <NUM>, the second hub, and the bearing <NUM> may be axially aligned and coincident with the central longitudinal axis <NUM>.

The first bearing <NUM> may be formed of metal and may include an annular rim <NUM> that is positioned within the recessed area between the ridge <NUM> of the bull gear <NUM> and the exterior annular edge <NUM> of the first hub <NUM>. The first bearing <NUM> is configured to constrain relative motion and reduce friction between the bull gear <NUM> and the first hub <NUM>. For example, the bearing <NUM> may be configured to restrain radial shifts in the directions of arrows A, for example, between the bull gear <NUM> and the first hub <NUM>. As explained below, however, in the event of a mechanical jam, for example, the bearing <NUM> allows the bull gear <NUM> to axially rotate (that is, rotate in a direction about the central longitudinal axis <NUM> of the shock absorber assembly <NUM>) in the direction of arc B relative to the first hub <NUM> and/or the second hub.

The first hub <NUM> includes a planar annular rim <NUM> having the exterior annular edge <NUM>. A recessed area <NUM> extends inwardly from the annular rim <NUM>, and is recessed below a planar outer surface <NUM> of the annular rim <NUM>. The recessed area <NUM> includes a plurality of spring channels <NUM> that are axially aligned with spring channels formed in the main body <NUM> of the bull gear <NUM> and spring channels formed in the second hub. The axially aligned spring channels, including the spring channels <NUM>, are configured to receive and retain respective springs <NUM>, such as helical coil springs. In general, the spring channels <NUM> align and cooperate with spring channels of the bull gear <NUM> and the second hub to provide spring channels that retain the springs <NUM>.

As shown, the shock absorber assembly <NUM> includes six springs <NUM> retained in a respective number of aligned spring channels. The spring channels <NUM> (and the spring channels of the bull gear <NUM> and the second hub) may be regularly spaced around the shock absorber assembly <NUM> as shown. Alternatively, more or less springs channels that retain more or less springs than shown may be used. In at least one embodiment, the shock absorber assembly <NUM> may not include any springs <NUM>.

The bearing <NUM> may be formed of metal and the circumferential base <NUM> may be positioned between an inner circumferential edge <NUM> (for example, an inner diameter) of the first hub <NUM> and an outer circumferential edge <NUM> (for example, an outer diameter) of the inner collar <NUM> of the bull gear <NUM>. The first hub <NUM> may be securely and fixedly fastened to the second hub through fasteners (for example, bolts), such that they may not axially rotate in relation to one another. Alternatively, in the event of a mechanical jam, the first hub <NUM> and the second hub may be configured to axially rotate a controlled distance relative to one another.

As shown, fastener holes <NUM> may be regularly spaced about the first hub <NUM>. The fastener holes <NUM> are configured to align with expanded channels (hidden from view in <FIG>) within the bull gear <NUM> and fastener holes (hidden from view in <FIG>) of the second hub. The diameter of the fastener holes <NUM> of the first hub <NUM> and the fastener holes of the second hub may be sized to threadably or otherwise securely retain and axially and radially fix in position fasteners, such as bolts. In this manner, when fastened together, the first and second hubs may not axially rotate or radially shift relative to one another. Further, when the hubs are fastened together through bolts, for example, the hubs exert a clamping force into the bull gear <NUM> to compressively sandwich the bull gear <NUM> between the hubs. Notably, however, the expanded channels of the bull gear <NUM>, through which shafts of the fasteners pass, may provide arcuate, radial openings that are larger than the diameters of the fastener shafts, thereby providing the bull gear <NUM> the ability to axially shift or rotate in relation to the first and second hubs <NUM> and <NUM> over a controlled distance.

The controlled distance may be less than a full <NUM> degree rotation. For example, the controlled distance may be a rotation that does not exceed <NUM> degrees. In at least one embodiment, the controlled distance may be a rotation of less than <NUM> degrees.

<FIG> illustrates a perspective front view of the shock absorber assembly <NUM> with the first hub <NUM> (shown in <FIG>) removed, according to an embodiment of the present disclosure. As noted above, the main body <NUM> of the bull gear <NUM> includes a plurality of regularly-spaced fastener channels <NUM>. The fastener channels <NUM> may be expanded openings formed through the main body <NUM> and aligned with fastener holes <NUM> of the second hub <NUM> and the fastener holes <NUM> (shown in <FIG>) of the first hub <NUM>. Each of the fastener channels <NUM> may slidably retain a portion of a fastener that securely fastens the first hub <NUM> to the second hub <NUM>. That is, during a system malfunction in which the bull gear <NUM> rotates in relation to the first and second hubs <NUM> and <NUM>, portions of the fasteners that fix the first hub <NUM> to the second hub <NUM> slide through the fastener channels <NUM> in an arcuate direction, as defined by the shape of the fastener channels <NUM>. For example, each fastener channel <NUM> may include an arcuate segment aligned around the central longitudinal axis <NUM>.

As noted, the second hub <NUM> may be a mirror image of the first hub <NUM>, with at least a portion of the main body <NUM> of the bull gear <NUM> sandwiched therebetween. The fastener holes <NUM> and <NUM> may have a diameter that is large enough to receive a shaft of a fastener, such as a bolt, but prevent it from axially or radially shifting therein. In contrast, the expanded fastener channels <NUM> are larger than the diameter of the fastener shafts. Accordingly, while the fasteners may securely connect the first and second hubs <NUM> and <NUM> together and prevent axial and radial shifting therebetween, the fasteners may shift through the channels <NUM> a controlled distance defined by the length of the channels <NUM>. Accordingly, the bull gear <NUM> may axially shift in relation to the first and second hubs <NUM> and <NUM> a controlled distance defined by the arcuate distance of each channel <NUM> in the axial directions of arcs C.

<FIG> illustrates a front view of the shock absorber assembly <NUM>, according to an embodiment of the present disclosure. <FIG> illustrates a cross-sectional view of a shock absorber assembly <NUM> through line <NUM>-<NUM> of <FIG>. Referring to <FIG> and <FIG>, the main body <NUM> of the bull gear <NUM> includes an interior recessed planar portion <NUM> that is received and retained within a reciprocal slot <NUM> formed through the bearing <NUM>. The interior recessed planar portion <NUM> may be sandwiched between the mirror image hubs <NUM> and <NUM>. The planar portion <NUM> extends through an outer separating gap <NUM> formed between the first hub <NUM> and the second hub <NUM>, through the aligned spring channels <NUM>, and into an inboard circumferential slot <NUM> formed through between the hubs <NUM> and <NUM> proximate to the drive shaft <NUM>.

The interior surfaces of the first and second hubs <NUM> and <NUM> that define the slots <NUM> and <NUM> may be lined with a frictional component (for example, a component, such as a lining, that increases friction between two components), such as a brake lining <NUM>. Optionally or additionally, the brake lining <NUM> may be secured to an outer surface of the planar portion <NUM> of the main body <NUM> of the bull gear <NUM> that interfaces with the first and second hubs <NUM> and <NUM>. The brake lining <NUM> may include engineered paper, asbestos-based brake lining material, bronze on steel, steel on steel, paper on steel, and/or the like. In general, the brake lining <NUM> is formed to provide a controlled coefficient of friction. The brake lining <NUM> may be a thin layer of material. For example, the brake lining <NUM> may be <NUM>. <NUM>" thick. Alternatively, the brake lining <NUM> may be thinner or thicker than <NUM>.

In general, the amount of damping (for example, torque dissipation) may be controlled by a thickness of the brake lining <NUM> between the bull gear <NUM> and the hubs <NUM> and <NUM>, as well as the clamping force exerted by the hubs <NUM> and <NUM> into the bull gear <NUM>. Further, with increased clamping force on the brake lining <NUM>, the greater the amount of force that is needed to overcome its coefficient of friction in order to independently rotate the bull gear <NUM> in relation to the hubs <NUM> and <NUM>.

During normal operation of the shock absorber assembly, an actuator rotates the bull gear <NUM>. Normal operation refers to operation of a system, such as a PDU, without any system malfunctions, such as mechanical jams. The brake lining <NUM> between the bull gear <NUM> and the first and second hubs <NUM> and <NUM> ensures that the first and second hubs <NUM> and <NUM> rotate along with the bull gear <NUM>. For example, torque from a motor or actuator is transferred or otherwise transmitted from the bull gear <NUM> to the hubs <NUM> and <NUM> through the interface of the brake lining <NUM> therebetween and/or the springs <NUM>. The brake lining interface and/or the spring force ensures that the bull gear <NUM> and the hubs <NUM> and <NUM> remain securely connected to one another during normal operation such that all three components rotate along with one another (such that the rotation of all three components may be in synchronization).

However, during a mechanical jam or other malfunction, such as when the drive shaft <NUM> immediately ceases, locks, or otherwise stops, the energy of the motor imparted into the bull gear <NUM> causes it to continue to rotate. During the system malfunction, the brake lining <NUM> is configured to allow the bull gear <NUM> to rotate in relation to the first and second hubs <NUM> and <NUM> over the controlled distance as defined by the fastener channels <NUM> in order to dissipate the torque energy exerted by the motor. As the bull gear <NUM> rotates relative to the first and second hubs <NUM> and <NUM>, the springs <NUM> are compressed within the aligned spring channels <NUM>. The springs <NUM> exert a resistive force into the edges of the bull gear <NUM>, the first hub <NUM>, and the second hub <NUM> that define the aligned spring channels <NUM>. In this manner, torque energy may also be dissipated by the springs <NUM>, which also prevents internal structures of the bull gear <NUM> from colliding with internal structures of the first and second hubs <NUM> and <NUM>. The springs <NUM> also provide a restorative force to reposition the bull gear <NUM> to a neutral position with respect to the hubs <NUM> and <NUM> after the system malfunction ends and the system operates in a normal fashion.

Alternatively, instead of the springs <NUM>, other force-resisting elements may be positioned within the channels <NUM>. For example, blocks of open cell foam may be positioned within the channels. As another example, blocks or rubber may be positioned within the channels. Further, the channels <NUM> and the force-resisting elements, such as the springs <NUM>, therein may be covered, such as with shrouds, casings, or the like, which prevent the force-resisting elements from ejecting from the channels <NUM>.

<FIG> illustrates a perspective front view of the spring channel <NUM> of the bull gear <NUM> sandwiched between the first and second hubs <NUM> and <NUM> of the shock absorber assembly <NUM>, according to an embodiment of the present disclosure. For the sake of clarity, a spring is not shown within the spring channel <NUM>, which is defined by the three aligned spring channels of the bull gear <NUM>, the first hub <NUM>, and the second hub <NUM>. As shown, the planar portion <NUM> of the main body <NUM> of the bull gear <NUM> is sandwiched between the first and second hubs <NUM> and <NUM>, and may include inwardly-directed protuberances <NUM>, such as tabs, barbs, studs, posts, fins, or the like, that are coplanar with the planar portion <NUM>. The protuberances <NUM> extend into the spring channel <NUM> and are configured to retain the spring at either end. For example, respective ends of the spring may wrap around the protuberances <NUM> to secure the spring in position.

As noted, when the bull gear <NUM> axially shifts (for example, rotates) in relation to the first and second hubs <NUM> and <NUM> in the directions of arc C, the springs <NUM> (shown in <FIG>) exert a resistive force into the edge portions of the bull gear <NUM> and the first and second hubs <NUM> and <NUM> that dissipates torque energy and prevents the bull gear <NUM> from rotating into the hubs <NUM> and <NUM> a distance that may cause portions of the bull gear <NUM> to undesirably impinge upon portions of the first and/or second hubs <NUM> and <NUM>.

<FIG> illustrates a transverse cross-sectional view of the shock absorber assembly <NUM> secured to the drive shaft <NUM> of a PDU <NUM>. The outer circumferential edge <NUM> of the bull gear <NUM> may be operatively connected to pinion gears <NUM>, each of which is operatively connected to a motor (not shown). Alternatively, the bull gear <NUM> may be operatively connected to only one pinion gear <NUM>.

The shock absorber assembly <NUM> is operatively secured to the drive shaft <NUM> between first and second torque brakes <NUM> and <NUM>. For example, the drive shaft <NUM> may be secured within the collar <NUM> of the bull gear <NUM>, and/or within a central passage defined by the bearing <NUM>. A single shock absorber assembly <NUM> is operatively connected to the PDU <NUM> between the torque brakes <NUM> and <NUM>, instead of each torque brake <NUM> and <NUM> being coupled to a separate and distinct shock absorber.

During normal operation, the motors drive the bull gear <NUM> to rotate about a central longitudinal axis <NUM> of the drive shaft <NUM>. As the bull gear <NUM> rotates, the first and second hubs <NUM> and <NUM> rotate in response thereto. The brake lining interface between the bull gear <NUM> and the first and second hubs <NUM> and <NUM> provides a coefficient of friction that ensures that the hubs <NUM> and <NUM> rotate along with the bull gear <NUM> during normal operation.

During a system malfunction, however, such as when the drive shaft <NUM> immediately ceases moving (for example, a mechanical jam in the system), the motors continue to operate and generate torque. The energy of the motors, as translated into the bull gear <NUM> through the pinion gears <NUM>, is dissipated by the frictional material interface, such as the brake lining <NUM> and/or the springs <NUM>, between the bull gear <NUM> and the hubs <NUM>, <NUM>. The torque exerted into the bull gear <NUM> may cause the bull gear <NUM> to axially shift in relation to the hubs <NUM> and <NUM> when the drive shaft <NUM> is locked in place. The torque energy of the motor is dissipated by the brake lining. The coefficient of friction of the brake lining may be such as to allow the bull gear <NUM> to axially shift so that the bull gear <NUM> rotates independently of the hubs <NUM> and <NUM>. The hubs <NUM> and <NUM> may be securely fastened together, such as through bolts, so as not to be able to rotate relative to each other. Also, during a system malfunction, the springs <NUM> also dissipate a portion of the torque energy, and compress lengthwise, thereby exerting a resistive force that resists the rotational motion of the bull gear <NUM> between the first and second hubs <NUM> and <NUM>.

Accordingly, the torque energy generated by the motors during a mechanical malfunction of the PDU <NUM>, such as a mechanical jam in which the drive shaft <NUM> locks in place, is absorbed by the rotational motion of the bull gear <NUM> with respect to the first and second hubs <NUM> and <NUM>. Consequently, damage to components of the PDU <NUM>, such as the torque brakes <NUM> and <NUM>, is prevented by the single shock absorber assembly <NUM> disposed between the torque brakes <NUM> and <NUM>. As shown, the shock absorber assembly <NUM> is disposed directly in a load path of the PDU <NUM>, such as between the torque brakes <NUM> and <NUM>.

Embodiments of the present disclosure provide a shock absorber assembly that reduces the part count for half system torque brakes, for example. Because the shock absorber assembly <NUM> is disposed within the load path of the PDU before the load path splits between right and left portions (such as right and left wings of an aircraft, for example), only a single shock absorber assembly may be used (instead of attaching separate and distinct shock absorbers to separate and distinct torque brakes). Further, in contrast to an automotive clutch or torque limiters, the shock absorber assembly is capable or reacting to radial loads imposed by gears, for example.

As described above, embodiments of the present disclosure provide a shock absorber assembly that may include a bull gear having at least a portion sandwiched between two hubs. The hubs and/or the bull gear may be lined, coated, covered, or the like with frictional material, such as brake lining. For example, brake lining may be bonded to an interior planar portion of the bull gear, and/or portions of one or both hubs that interface with the bull gear. A pair of rolling element bearings may be mounted on the bull gear that allow it to smoothly and evenly axially shift with respect to the hubs in the event of a system malfunction, such as when a drive shaft of a PDU locks or otherwise jams in position. One or more springs may be used to transmit torque from the bull gear to the hubs, for example.

Further, unlike previous shock absorbers used with PDUs, embodiments of the present disclosure provide shock absorber assemblies that do not include steel rings as a damping medium. Instead, embodiments of the present disclosure provide shock absorber assemblies that include brake lining between one or more interfaces between a bull gear and one or more hubs. The brake lining is lighter and more cost-effective than steel rings. Further the brake lining provides a consistent coefficient of friction, unlike a plurality or steel rings.

While various spatial and directional terms, such as top, bottom, lower, mid, lateral, horizontal, vertical, front and the like may be used to describe embodiments of the present disclosure, it is understood that such terms are merely used with respect to the orientations shown in the drawings. The orientations may be inverted, rotated, or otherwise changed, such that an upper portion is a lower portion, and vice versa, horizontal becomes vertical, and the like.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments of the disclosure without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments of the disclosure, the embodiments are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments of the disclosure should, therefore, be determined with reference to the appended claims.

In the appended claims, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein. " Moreover, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their.

This written description uses examples to disclose the various embodiments of the disclosure, including the best mode, and also to enable any person skilled in the art to practice the various embodiments of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art.

Further, the disclosure relates to:
There is disclosed a shock absorber assembly configured to be operatively connected to a drive shaft of a power drive unit (PDU) of an aircraft, the shock absorber assembly comprising:.

Preferably, the shock absorber further comprises brake lining secured to one or more of the first hub, the second hub, and the bull gear, wherein the brake lining provides a frictional interface between the bull gear and one or both of the first and second hubs, wherein the brake lining provides a coefficient of friction that causes the bull gear to rotate along with the first and second hubs during normal operation of the PDU, and wherein the brake lining dissipates at least a portion of torque energy during the mechanical malfunction.

Preferably, each of the first hub, the second hub, and the bull gear comprises a plurality of channels, wherein the plurality of channels of the first hub align with the plurality of channels of the second hub and the bull gear, wherein the plurality of channels retain force-resisting elements that are configured to dissipate at least a portion of torque energy during the mechanical malfunction.

Preferably, the force-resisting elements comprise helical springs.

Preferably, the shock absorber assembly further comprises one or more bearings, wherein the bull gear is rotatably secured to the one or more bearings.

Preferably, at least one of the bull gear and the one or more bearings comprises a shaft channel, wherein the drive shaft is configured to be secured within the shaft channel.

Preferably, the first and second hubs are securely fixed together in order to prevent the first hub from rotating relative to the second hub.

Preferably, the bull gear includes a plurality of fastener channels, wherein each of the plurality of fastener channels slidably retains a portion of a fastener that securely fastens the first hub to the second hub.

Also, there is disclosed an aircraft comprising: a fuselage; wings securely fixed to the fuselage, wherein each of the wings includes a plurality of control surfaces; a power drive unit (PDU) coupled to a drive shaft that is operatively coupled to one or more of the plurality of control surfaces, wherein the PDU includes first and second torque brakes operatively coupled to the drive shaft; and a shock absorber assembly operatively coupled to the drive shaft between the first and second torque brakes, wherein the shock absorber assembly comprises: (a) a first hub; (b) a second hub; and (c) a bull gear having at least a portion sandwiched between the first and second hubs, wherein the bull gear is configured to rotate independently of the first and second hubs in response to a mechanical malfunction of the PDU.

Preferably, the bull gear comprises an outer annular edge that is operatively coupled to at least one pinion gear that is configured to be operatively connected to at least one motor.

Preferably, at least one of the first and second hubs is lined with brake lining that interfaces with the bull gear, wherein the brake lining provides a coefficient of friction that causes the bull gear to rotate along with the first and second hubs during normal operation of the PDU, and wherein the brake lining dissipates at least a portion of torque energy during the mechanical malfunction.

Preferably, the first and second hubs are securely fixed together in order to prevent the first hub from rotating relative to the second hub, wherein the bull gear includes a plurality of fastener channels, wherein each of the plurality of fastener channels slidably retains a portion of a fastener that securely fastens the first hub to the second hub.

Further, there is disclosed a shock absorber assembly configured to be operatively connected to a drive shaft of a power drive unit (PDU) of an aircraft, the shock absorber assembly comprising: a first hub; a second hub that is a mirror image of the first hub, wherein the first and second hubs are securely fixed together in order to prevent the first hub from rotating relative to the second hub; a bull gear having at least a portion sandwiched between the first and second hubs, wherein the bull gear is configured to rotate independently of the first and second hubs a controlled distance in response to a mechanical malfunction of the PDU; one or more bearings, wherein the bull gear is rotatably secured to the one or more bearings, wherein at least one of the bull gear and the one or more bearings comprises a shaft channel, wherein the drive shaft is configured to be secured within the shaft channel; and brake lining secured to one or more of the first hub, the second hub, and the bull gear, wherein the brake lining provides a frictional interface between the bull gear and one or both of the first and second hubs, wherein the brake lining provides a coefficient of friction that causes the bull gear to rotate along with the first and second hubs during normal operation of the PDU, and wherein the brake lining dissipates at least a portion of torque energy during the mechanical malfunction.

Claim 1:
A shock absorber assembly (<NUM>) configured to be operatively connected, between first and second torque brakes (<NUM>, <NUM>), to a drive shaft (<NUM>) of a power drive unit, PDU, of an aircraft (<NUM>), the shock absorber assembly (<NUM>) comprising:
a first hub (<NUM>);
a second hub (<NUM>);
a brake lining (<NUM>) between a
bull gear (<NUM>) and the first and second hubs (<NUM>, <NUM>); and
the bull gear (<NUM>) having at least a portion (<NUM>) sandwiched between the first and second hubs (<NUM>, <NUM>), wherein the bull gear (<NUM>) and the first and second hubs (<NUM>, <NUM>) are concentric with a central longitudinal axis (<NUM>) of the shock absorber assembly (<NUM>), wherein the central longitudinal axis (<NUM>) extends axially, wherein a radially extending outer annular edge (<NUM>) of the bull gear (<NUM>) is configured to operatively connect to at least one pinion gear (<NUM>), each of which is operatively connected to at least one motor, wherein, when the shock absorber assembly is secured to the drive shaft (<NUM>), the bull gear (<NUM>) is rotated during normal operation of the shock absorber assembly, by the at least one motor, and is configured to rotate independently of the first and second hubs (<NUM>, <NUM>) a controlled distance in response to a mechanical malfunction of the PDU (<NUM>) when the drive shaft (<NUM>) immediately ceases moving, locks, or otherwise stops while the at least one motor continues to operate and generate torque;
wherein the brake lining (<NUM>) is secured to one or more of the first hub (<NUM>), the second hub (<NUM>), and the bull gear (<NUM>), wherein the brake lining (<NUM>) provides a frictional interface between the bull gear (<NUM>) and one or both of the first and second hubs (<NUM>, <NUM>), wherein the brake lining (<NUM>) provides a coefficient of friction that causes the bull gear (<NUM>) to rotate along with the first and second hubs (<NUM>, <NUM>) during the normal operation of the PDU such that rotation of the first hub (<NUM>), the second hub (<NUM>) and the bull gear (<NUM>) is in synchronization, and wherein the brake lining (<NUM>) dissipates at least a portion of torque energy during the mechanical malfunction.