Patent Description:
Commercial jet aircraft typically employ thrust reversal, or reverse thrust, during landings to help slow the aircraft after touch-down. By temporarily diverting either jet exhaust or bypass air forward, thrust reversal can provide rapid deceleration, permitting shorter landing distances and also reducing the wear experienced by brake systems.

There are three major types of thrust reverser systems: Target-type thrust reversers, clam-shell (or cascade) thrust reversers, and cold stream thrust reversers. Each type of system operates by redirecting at least a portion of engine thrust in a substantially forward direction. The target-type thrust reverser employs hydraulic actuators to deploy a pair of 'bucket' type doors that redirect the exhaust stream from the engines forward.

Current thrust reversers employ hydraulic actuators that are fitted with locking mechanisms, in order to prevent inadvertent actuation, and lock indicators so that the status of the actuator lock can be readily determined. Unfortunately, the current actuators are relatively bulky, and include a large number of cooperating parts, creating disadvantages with respect to maintenance and service as well as component weight. In addition, the lock indicator system of the current actuators can in some instances create mechanical wear on the locking mechanism of the actuator, necessitating more frequent service and replacement.

<CIT> mentions in its abstract that "An actuator includes a cylinder and a piston disposed in the cylinder. The piston has a head and a rod. The actuator further includes a collapsible locking member disposed in the head of the piston, and a gas-filled capsule disposed in the cylinder. The gas-filled capsule is in an expanded position when fluid in the cylinder is below a threshold pressure, and the gas-filled capsule is in a collapsed position when fluid in the cylinder is above the threshold pressure. The actuator also includes a lock piston operably connected to the gas-filled capsule. The lock piston engages the collapsible locking member and biases the collapsible locking member radially outward to a locked position when the gas-filled capsule is in the expanded position".

<CIT> mentions in its abstract that "An actuator for a thrust reverser is disclosed which will prevent retraction of the thrust reverser door from its open, reverse thrust position should there be a malfunction in the locking system which locks the thrust reverser door in its closed forward thrust position. Upon deployment of the thrust reverser during a normal aircraft landing, should there be a malfunction in the thrust reverser door locking system, the actuator holds the thrust reverser doors in their opened positions so as to provide a positive, visual indication of such a system malfunction. The actuator has an internal device in the actuator head which, in cooperation with the control rod of the secondary mechanical locking system prevents hydraulic fluid from retracting the actuating piston and rod assembly from their extended positions and thereby prevents retraction of the thrust reverser door from the reverse thrust positions. Since thrust reverser doors are always fitted with position sensors, the failure of the thrust reverser door to return to its forward thrust position will be sensed by the normal aircraft position sensors so as to provide a positive indication to the aircraft crew of a defect in the mechanical locking system".

<CIT> mentions in its abstract that "An actuator comprises a ball nut and a lock housing arranged radially outwardly of the ball nut and overlapping a proximal end of the ball nut when the ball nut is in a stowed position. The lock housing comprises a sleeve in which is located an aperture, and a locking element is retained within the aperture and can move in a radial direction through the aperture. When the ball nut is in the stowed position, the locking element engages with a locking projection on the ball nut, to retain the ball nut in the stowed position".

In a first aspect there is provided a locking linear actuator as defined in claim <NUM> of the appended claims. In a second aspect there is provided a thrust reverser for an aircraft engine, as defined in appended claim <NUM>. In a third aspect there is provided a method of manufacturing a locking linear actuator, as defined in appended claim <NUM>. The present disclosure provides locking linear actuators, thrust reversers employing locking linear actuators, and methods of manufacturing locking linear actuators.

In some examples, the present disclosure relates to locking linear actuators that include an actuator housing that defines an internal longitudinal bore, an actuator piston disposed in the internal longitudinal bore, where the actuator piston is configured to slidably move between a proximal retracted position and a distal extended position, and a lock sleeve disposed in the internal longitudinal bore where the lock sleeve is configured to slidably move between a distal locking position and a proximal unlocked position. In addition, when the actuator piston is in the retracted position and the lock sleeve is in the locking position, a distal portion of the lock sleeve extends into a proximal portion of the actuator piston and prevents the actuator piston from leaving the retracted position.

In some examples, the present disclosure relates to a thrust reverser for an aircraft engine, where the thrust reverser includes an aircraft engine nacelle having at least one deployable thrust reverser, and at least one linear actuator within the aircraft engine nacelle that is coupled to the deployable thrust reverser so that deploying the thrust reverser includes extending the at least one linear actuator. The linear actuator includes an actuator housing that defines an internal longitudinal bore, an actuator piston disposed in the internal longitudinal bore that is configured to slidably move between a proximal retracted position and a distal extended position, and a lock sleeve disposed in the internal longitudinal bore that is configured to slidably move between a distal locking position and a proximal unlocked position. Additionally, when the actuator piston is in the retracted position and the lock sleeve is in the locking position, a distal portion of the lock sleeve extends into a proximal portion of the actuator piston to prevent the actuator piston from leaving the retracted position.

In some examples, the present disclosure relates to a method of manufacturing a locking linear actuator. The method includes manufacturing an elongate actuator housing, where the actuator housing defines an internal longitudinal bore, installing an actuator piston within the internal longitudinal bore, so that the actuator piston is slidably moveable between a proximal retracted position and a distal extended position, and installing a lock sleeve within the internal longitudinal bore proximal to the actuator piston, so that the lock sleeve is slidably moveable between a distal locking position and a proximal unlocked position, so that when the actuator piston is in the retracted position and the lock sleeve is in the locking position, a distal portion of the lock sleeve extends into a proximal portion of the actuator piston to prevent the actuator piston from leaving the retracted position.

Features, functions, and advantages can be achieved independently in various examples of the present disclosure, or can be combined in yet other examples, further details of which can be seen with reference to the following description and drawings.

Various aspects and examples of locking linear actuators, thrust reverser systems incorporating the locking linear actuators, and methods of manufacturing locking linear actuators are described below and illustrated in the associated drawings. The following description of various examples is merely illustrative in nature and is in no way intended to limit the examples, their applications, or their uses. Additionally, the advantages provided by the examples and embodiments described below are illustrative in nature and not all examples and embodiments provide the same advantages or the same degree of advantages.

This Detailed Description includes the following sections, which follow immediately below: (<NUM>) Definitions; (<NUM>) Overview; (<NUM>) Examples, Components, and Alternatives; (<NUM>) Methods of Manufacture; (<NUM>) Additional Examples; (<NUM>) Advantages, Features, and Benefits; and (<NUM>) Conclusion.

The following definitions apply herein, unless otherwise indicated.

"Substantially" means to be predominantly conforming to the particular dimension, range, shape, concept, or other aspect modified by the term, such that a feature or component need not conform exactly, so long as it is suitable for its intended purpose or function.

"Comprising," "including," and "having" (and conjugations thereof) are used interchangeably to mean including but not necessarily limited to, and are open-ended terms not intended to exclude additional, unrecited elements or method steps.

Terms such as "first", "second", and "third" are used to distinguish or identify various members of a group, or the like, in the order they are introduced in a particular context and are not intended to show serial or numerical limitation, or be fixed identifiers for the group members.

"Coupled" means to be in such relation that the performance of one influences the performance of the other, may include being connected, either permanently or releasably, whether directly or indirectly through intervening components, and is not necessarily limited to physical connection(s).

The locking linear actuators of the present disclosure may offer enhanced utility in any application where a linear hydraulic actuator is utilized, and in particular those applications where it may be advantageous to employ a hydraulic linear actuator having a smaller profile, fewer moving parts, an enhanced locking mechanism, and an enhanced lock sensor. Selected representative applications can include manufacturing, construction, agriculture, and commercial transportation, particularly the use of linear actuators in commercial aircraft. Although the locking linear actuators of the present disclosure will primarily be discussed in the context of thrust reverser systems of commercial aircraft, this should not be considered to limit the utility or applicability of the present locking linear actuators in any way.

The rear nozzle portion of a representative turbofan jet engine nacelle <NUM> is shown in <FIG>. The representative jet engine nacelle <NUM> includes a target-type thrust reverser system <NUM> that has two thrust reverser doors or panels <NUM> as shown in their retracted or stowed positions in <FIG>, and in their actuated or deployed positions in <FIG>. The thrust reverser panels <NUM> are coupled to jet engine <NUM> of nacelle <NUM> by one or more locking linear actuators <NUM>, as depicted semi-schematically in <FIG>, and the overall performance of the thrust reverser can be improved by incorporation of one or more aspects of the construction and features of the presently disclosed locking linear actuators.

A representative locking linear actuator <NUM> is depicted in <FIG>, as a longitudinal and vertical cross-section view. The locking linear actuator <NUM> includes an elongate actuator housing <NUM> that encloses and secures the linear actuator mechanism. Actuator housing <NUM> has a distal end <NUM> and a proximal end <NUM>, where proximal end <NUM> is directly or indirectly attached to jet engine <NUM> and/or a jet engine nacelle <NUM>. An actuator piston <NUM> is disposed within an internal longitudinal bore <NUM> defined by actuator housing <NUM>, and having a longitudinal bore axis <NUM>. A distal end <NUM> of actuator piston <NUM> can be directly or indirectly coupled to a panel <NUM> of a thrust reverser system <NUM>. Actuator piston <NUM> can be configured so that the actuator piston is slidably disposed within internal longitudinal bore <NUM>, and is therefore capable of slidably moving between a proximal position, corresponding to thrust reverser panel <NUM> being retracted or stowed, and a distal position, corresponding to thrust reverser panel <NUM> being extended or deployed.

Also disposed within internal longitudinal bore <NUM>, in a position that is proximal to actuator piston <NUM>, is a lock sleeve <NUM>. Similar to actuator piston <NUM>, lock sleeve <NUM> is configured to slidably translate within internal longitudinal bore <NUM> between a distal locking position and a proximal unlocked position.

With reference to <FIG>, the actuator piston <NUM> and the lock sleeve <NUM> are configured such that, when the actuator piston <NUM> is in the retracted position and the lock sleeve <NUM> is in the locking position, a distal portion <NUM> of the lock sleeve extends into a proximal portion <NUM> of the actuator piston to prevent the actuator piston <NUM> from leaving the retracted position.

At least a proximal portion <NUM> of actuator piston <NUM> defines a substantially cylindrical piston sidewall <NUM>. Cylindrical piston sidewall <NUM> defines at least one lock aperture <NUM> that extends through the cylindrical piston sidewall. A locking tab <NUM> is movably disposed in the lock aperture <NUM>, and both locking tab <NUM> and lock aperture <NUM> are sized and shaped so that locking tab <NUM> can readily translate radially within lock aperture <NUM>. As shown for a circular cross-section of cylindrical piston sidewall <NUM> in <FIG>, locking tab <NUM> can translate inwardly and/or outwardly along a radius of the circle defined by the cross-section. In the illustrative example of <FIG>, representative cylindrical piston sidewall <NUM> defines three lock apertures <NUM> that are disposed <NUM> degrees apart. As shown, the three corresponding locking tabs <NUM> are in their radially outermost positions.

Cylindrical piston sidewall <NUM> is surrounded by an inner surface <NUM> of internal longitudinal bore <NUM> in actuator housing <NUM>. As shown in <FIG>, inner surface <NUM> can be configured to define a step <NUM>, where step <NUM> is defined as any feature that a corresponding locking tab <NUM> can positively interact with while in their radially outermost positions. As shown for representative and exemplary locking linear actuator <NUM>, step <NUM> can have the form of a circumferential ledge around the entire inner surface <NUM>, and the defined step <NUM> can include a surface orthogonal to longitudinal bore axis <NUM>, or can be angled with respect to longitudinal bore axis <NUM>, as shown. Step <NUM> can be continuous or intermittent, provided that a step is disposed at the one or more positions suitable for interacting with locking tabs <NUM>. Any configuration of step <NUM> and locking tabs <NUM> that provides a positive interaction between actuator piston <NUM> and actuator housing <NUM> can be a useful configuration.

Step <NUM> can be positioned and shaped so that when actuator piston <NUM> is in the proximal and retracted position, and locking tab <NUM> is disposed radially outwardly sufficiently, that an outer edge of locking tab <NUM> extends sufficiently beyond lock aperture <NUM> that outer edge <NUM> engages step <NUM> in inner surface <NUM>. As locking tab <NUM> is engaged with step <NUM>, and actuator piston <NUM> is engaged with locking tab <NUM> via lock aperture <NUM>, actuator piston <NUM> is prevented from translating out of the proximal and retracted position. In this configuration, actuator piston <NUM> is locked in place, and linear actuator <NUM> as a whole can be described as being locked.

Locking tab <NUM>, and its outer edge <NUM>, may also have any suitable shape and configuration. In the example depicted in <FIG> and <FIG>, outer edge <NUM> of locking tab <NUM> is curved so as to provide a strong interaction with the curve of step <NUM>. The outer edge can be more or less curved, or even exhibit no curvature, provided locking tab <NUM> can engage positively with step <NUM>. As shown in greater detail in <FIG>, locking tab <NUM> also defines an outer face <NUM>, an inner face <NUM>, a distal face <NUM> and a proximal face <NUM>. Locking tab <NUM> can further include an outer chamfered edge <NUM>, that can be angled to be complementary to the angle of step <NUM>. Additionally, when locking tab <NUM> is urged outwardly during locking, the interaction of outer chamfered edge <NUM> with step <NUM> helps to seat actuator piston <NUM> in the locked configuration. Similarly, locking tab <NUM> can include an inner chamfered edge <NUM>, that can be angled to be complementary to a chamfered edge <NUM> on lock sleeve <NUM>, so that an interaction between chamfered edge <NUM> of the lock sleeve and inner chamfered edge <NUM> of the locking tab when lock sleeve is being urged in the distal direction will help to seat locking tab <NUM> against step <NUM>.

The locked configuration of linear actuator <NUM>, as shown in <FIG> and <FIG>, can be secured and maintained by an appropriate positioning of lock sleeve <NUM>. A distal portion <NUM> of lock sleeve <NUM> can define a cylindrical sleeve sidewall <NUM> that is sized and shaped so that cylindrical sleeve sidewall <NUM> can be inserted, or nested, concentrically within cylindrical piston sidewall <NUM> of actuator piston <NUM> when lock sleeve <NUM> is in the distal and locked position. In this configuration, cylindrical sleeve sidewall <NUM> prevents each locking tab <NUM> from moving radially inward within its respective lock aperture <NUM>, and therefore prevents each locking tab <NUM> from disengaging with step <NUM> in inner surface <NUM> of internal longitudinal bore <NUM>. Lock sleeve <NUM> can be kept in the distal and locking position by any appropriate lock sleeve biasing mechanism <NUM>, for example such as a lock sleeve biasing spring that can be positioned between a proximal surface <NUM> within internal longitudinal bore <NUM> and lock sleeve <NUM>, and therefore acts by continuously urging lock sleeve <NUM> in a distal direction and therefore toward the locking position, keeping linear actuator <NUM> locked, and preventing the actuator from deploying.

Actuator housing <NUM> defines an internal hydraulic space <NUM> that is in fluid communication with internal longitudinal bore <NUM>, as shown in <FIG>. Hydraulic space <NUM> encloses a synchronization screw <NUM> that can regulate the flow of pressurized hydraulic fluid into hydraulic space <NUM> from a suitable source, such as a large hydraulic system providing power to multiple aircraft systems, or a smaller, closed-circuit hydraulic system dedicated to the thrust reverser system, or to even a single linear actuator.

Actuator housing <NUM> can additionally define one or more channels <NUM> in fluid communication with both hydraulic space <NUM> and a region <NUM> of internal longitudinal bore <NUM> that includes the one or more steps <NUM>, as shown in <FIG>. When linear actuator <NUM> is locked, region <NUM> encloses the proximal portion <NUM> of actuator piston <NUM>, including the outer faces <NUM> of the one or more locking tabs <NUM>, which are being retained in engagement with step <NUM> by the presence of cylindrical sleeve sidewall <NUM> of lock sleeve <NUM>. As long as lock sleeve <NUM> maintains the distal locking position, locking tabs <NUM> are prevented from moving inwardly, and actuator piston <NUM> remains in the locked configuration.

In order to unlock and deploy linear actuator <NUM>, hydraulic pressure can be increased within hydraulic space <NUM>. As hydraulic pressure within hydraulic space <NUM> increases, the increased pressure urges lock sleeve <NUM> to translate in the proximal direction against the force applied by lock sleeve biasing mechanism <NUM>. As the increased hydraulic pressure becomes greater than the force applied against lock sleeve <NUM> by lock sleeve biasing mechanism <NUM>, lock sleeve <NUM> is urged in the proximal direction. Distal cylindrical sleeve sidewall <NUM> of lock sleeve <NUM> is therefore retracted from its nested position within cylindrical actuator piston cylindrical piston sidewall <NUM>. <FIG> shows linear actuator <NUM> with lock sleeve <NUM> urged into the proximal unlocked configuration.

Due to the presence of channel <NUM>, the pressure in hydraulic space <NUM> also creates increased pressure in region <NUM> of internal longitudinal bore <NUM>. This increased pressure urges actuator piston <NUM> in the distal direction within internal longitudinal bore <NUM>, which urges locking tabs <NUM> to move inwardly, as well as exerting pressure on outer face <NUM> of each locking tab <NUM> directly. Once lock sleeve <NUM> has translated to the unlocked configuration it no longer prevents the inward motion of locking tabs <NUM>, and each locking tab <NUM> moves inwardly until stopped. For the illustrative apparatus of <FIG>, for example, each locking tab <NUM> can move inwardly until it abuts an internal stop <NUM> defined by lock aperture <NUM>. Locking tab <NUM> is configured and sized so that once it is in contact with internal stop <NUM>, locking tab <NUM> no longer protrudes from lock aperture <NUM>, and is no longer engaged with step <NUM>, as shown in <FIG> and <FIG>.

As soon as locking tabs <NUM> are fully disengaged from step <NUM>, the increased hydraulic pressure existing within hydraulic space <NUM> immediately urges actuator piston <NUM> in the distal direction, resulting in the translation of actuator piston <NUM> to the distal position, resulting in the thrust reverser panel <NUM> that is coupled to actuator piston <NUM> being deployed, as shown in <FIG>.

As shown, lock sleeve <NUM> is permitted a smaller range of travel between the locking and unlocked positions than is required for actuator piston <NUM> when translating from proximal position to distal position. As a result, under the influence of hydraulic pressure lock sleeve <NUM> can translate very quickly to the unlocked configuration. The movement of actuator piston <NUM> is typically slower, due to its greater size and mass, and greater range of travel.

The locking linear actuator <NUM>, and therefore its associated thrust reverser panel <NUM>, can be returned to the stowed configuration by reducing the pressure of the hydraulic fluid being provided to hydraulic space <NUM>. With the reduction of internal pressure, actuator piston <NUM> is urged back to the original proximal position by the action of an actuator piston biasing mechanism <NUM>, which can be any suitable biasing mechanism, such as an actuator piston biasing spring, among others. Actuator piston biasing mechanism <NUM> can be at least somewhat stronger than lock sleeve biasing mechanism <NUM> for lock sleeve <NUM> in order to help ensure that actuator piston <NUM> returns to the proximal position before lock sleeve <NUM> is urged into the distal, locked position. As shown in <FIG>, actuator piston <NUM> has been returned to the proximal position, but locking tabs <NUM> remain within lock apertures <NUM>. As lock sleeve <NUM> is urged by lock sleeve biasing mechanism <NUM> to the locked position, the chamfered edge <NUM> of lock sleeve <NUM> can interact with chamfered edge <NUM> of locking tab <NUM>, which then urges each locking tab <NUM> outward to engage with step <NUM>.

The operation of locking linear actuator <NUM> can be coordinated with one or more additional locking linear actuators using a synchronization coupling <NUM>. Synchronization coupling <NUM> (<FIG>, <FIG>) can include a flexible-shafted cable <NUM> (<FIG>) that couples the operation of synchronization screw <NUM> (<FIG>, <FIG>) with the synchronization screws of those additional locking linear actuators in order to coordinate operation. The synchronization coupling <NUM> can be configured to ensure that where multiple locking linear actuators are operating in a single thrust reverser system, that the thrust reverser panels are moved in a substantially synchronized manner. That is, when one thrust reverser panel is moved, any other thrust reverser panel in the same thrust reverser system is moved an equivalent distance at substantially the same time. Other mechanical systems to synchronize linear actuator operation can include any other appropriate linkage in order to coordinate operation of coupled linear actuators.

The operation of locking linear actuator <NUM> can be monitored by a sensor <NUM> disposed adjacent the proximal end <NUM> of actuator housing <NUM>, where sensor <NUM> can be configured to detect an associated sensor target <NUM> that can be coupled to proximal end <NUM> of lock sleeve <NUM>. Various combinations of sensor and sensor target can be useful in the context of the present disclosure. Any suitable sensing technology can be used for the sensor target and sensor of locking linear actuator <NUM>, such as capacitive sensing, inductive sensing, optical sensing, magnetic sensing, among others.

Sensor target <NUM> can include two sensor activation regions <NUM> and <NUM>, and a sensor deactivation region <NUM>. As illustrated in <FIG>, sensor <NUM> can be a type of metal detector, and sensor target <NUM> can include two metallic disks which, when adjacent to sensor <NUM> (i.e. centered beneath the sensor) can activate or trigger the sensor. Deactivation region <NUM> then corresponds to a region between the metallic disks, which when disposed adjacent to sensor <NUM> does not trigger the sensor.

When linear actuator <NUM> is in the locked configuration, as shown in <FIG>, sensor <NUM> is aligned with and adjacent to deactivation region <NUM>. Sensor <NUM> is not activated, and the result is a signal that the locking linear actuator is in the locked configuration. In practical terms, this configuration can signal to a flight crew that the thrust reverser system coupled to the linear actuator is stowed and locked.

When linear actuator <NUM> is the unlocked configuration, as shown in <FIG>, lock sleeve <NUM> is in the proximal unlocked position, and sensor activation region <NUM> is aligned with and adjacent to sensor <NUM>. Sensor <NUM> is activated, and the result is a signal indicating that the locking linear actuator is in the unlocked configuration, and is deploying. This configuration can signal the flight crew that the thrust reverser system coupled to the linear actuator is deployed or in the process of deploying.

Because lock sleeve <NUM> is more responsive to changes in hydraulic pressure, and able to translate more rapidly than actuator piston <NUM>, when linear actuator <NUM> is in the process of being stowed or retracted, lock sleeve <NUM> may be urged in the distal direction beyond the locked configuration, until the actuator piston <NUM> is seated in the locked configuration and urges lock sleeve <NUM> into the locked configuration. This configuration of sensor target <NUM> is shown in <FIG>. As sensor activation region <NUM> is adjacent to sensor <NUM>, sensor <NUM> generates a signal indicating that the locking linear actuator is in the unlocked configuration, but is being stowed or retracted. Once the locking linear actuator is fully retracted and locked, sensor <NUM> should again align with sensor deactivation region <NUM>, and signal that the linear actuator is locked and stowed.

The manufacture of an illustrative locking linear actuator <NUM> may be accomplished according to flowchart <NUM> of <FIG>. The method of manufacture includes manufacturing an elongate actuator housing, as shown at step <NUM> of flowchart <NUM>.

The elongate actuator housing can be manufactured so as to define an internal longitudinal bore, an internal hydraulic space in fluid communication with the internal longitudinal bore, and a step on the inner surface of the internal longitudinal bore.

The method of manufacture further includes installing an actuator piston within the internal longitudinal bore as shown at step <NUM> of flowchart <NUM>, so that the actuator piston is slidably moveable between a proximal retracted position and a distal extended position.

The install actuator piston can be configured so that at least a proximal portion of the actuator piston includes a cylindrical piston sidewall defining at least one lock aperture.

The method of manufacture further includes installing a lock sleeve within the internal longitudinal bore proximal to the actuator piston, shown at step <NUM> of flowchart <NUM>, so that the lock sleeve is slidably moveable between a distal locking position and a proximal unlocked position, such that when the actuator piston is in the retracted position and the lock sleeve is in the locking position, a distal portion of the lock sleeve extends into a proximal portion of the actuator piston to prevent the actuator piston from leaving the retracted position.

The method of manufacture can further include installing a locking tab in the at least one lock aperture, as shown at step <NUM> of flowchart <NUM>, such that the locking tab can translate radially within the lock aperture, and when the locking tab extends radially beyond an outer surface of the actuator piston the locking tab engages the step in the inner surface of the internal longitudinal bore and prevents the actuator piston from leaving the retracted position, and the locking tab is in fluid communication with the hydraulic space, such that an increase in hydraulic pressure within the hydraulic space would urge the locking tab inward within the lock aperture, and when the actuator piston is in the retracted position and the lock sleeve is in the locking position, a distal portion of the lock sleeve extends into a proximal portion of the actuator piston and prevents the locking tab from moving inwardly and disengaging from the step in the inner surface of the internal longitudinal bore, and an increase in hydraulic pressure within the internal hydraulic space will urge the lock sleeve in a proximal direction and urge the actuator piston in a distal direction.

When the resulting locking linear actuator is in use, by increasing the hydraulic pressure within the hydraulic space the lock sleeve will translate in a proximal direction, permitting the locking tab to move inwardly in the lock aperture under the urging of the increased hydraulic pressure and disengage from the step, permitting the actuator piston to move from the retracted position to the extended position under the urging of the increased hydraulic pressure.

The method of manufacture further includes installing an actuator piston biasing mechanism to urge the actuator piston in a proximal direction within the internal longitudinal bore and can optionally further include installing a lock sleeve biasing mechanism configured to urge the lock sleeve in a distal direction in the internal longitudinal bore, as shown at step <NUM> of flowchart <NUM>, such that upon a decrease in the hydraulic pressure in the hydraulic space the actuator piston will return to the retracted position, the lock sleeve will returned to the locking position, and the locking tab will engage with the step, locking the linear actuator.

The method of manufacture can alternatively and optionally further include attaching a sensor adjacent to a proximal end of the actuator housing, and attaching an associated sensor target to a proximal end of the lock sleeve, as shown at step <NUM> of flowchart <NUM>, such that movement of the lock sleeve from one of the locking position and unlocked position to the other results in a movement of the sensor target that is detectable by the sensor and provides an indication that the linear actuator is locked or unlocked.

The method of manufacture can alternatively and optionally further include coupling the hydraulic space to a source of pressurized hydraulic fluid, as shown at step <NUM> of flowchart <NUM>.

The method of manufacture can alternatively and optionally further include coupling the actuator housing to an aircraft engine and coupling the actuator piston to a thrust reverser, as shown at step <NUM> of flowchart <NUM>.

The method of manufacture can alternatively and optionally further include coupling the thrust reverser to one or more additional linear actuators, and linking the plurality of linear actuators with a synchronization mechanism so that an operation of the plurality of linear actuators is synchronized, as shown at step <NUM> of flowchart <NUM>.

This section describes additional examples and features of the disclosed thrust reversers employing locking linear actuators, and methods of manufacturing locking linear actuators, presented without limitation as a series of paragraphs.

In a first example there is disclosed a thrust reverser for an aircraft engine, including an aircraft engine nacelle including at least one deployable thrust reverser; at least one locking linear actuator within the aircraft engine nacelle coupled to the deployable thrust reverser such that deploying the thrust reverser includes extending the at least one linear actuator; where the linear actuator includes: an actuator housing defining an internal longitudinal bore; an actuator piston disposed in the internal longitudinal bore, the actuator piston being configured to slidably move between a proximal retracted position and a distal extended position; a lock sleeve disposed in the internal longitudinal bore, the lock sleeve being configured to slidably move between a distal locking position and a proximal unlocked position; where when the actuator piston is in the retracted position and the lock sleeve is in the locking position, a distal portion of the lock sleeve extends into a proximal portion of the actuator piston to prevent the actuator piston from leaving the retracted position.

Optionally, at least a proximal portion of the actuator piston defines a cylindrical piston sidewall, with the cylindrical piston sidewall defining a lock aperture within the cylindrical piston sidewall; a locking tab is disposed in the lock aperture, such that the locking tab can translate radially within the lock aperture; an inner surface of the internal longitudinal bore defines a step, where the step is positioned so that when the actuator piston is in the retracted position and the locking tab within the lock aperture extends beyond the cylindrical piston sidewall of the actuator piston the locking tab engages the step in the inner surface and the actuator piston is thereby prevented from leaving the retracted position; and when the actuator piston is in the retracted position and the lock sleeve is in the locking position, a distal portion of the lock sleeve extending into the proximal portion of the actuator piston prevents the locking tab from moving inwardly and disengaging from the step in the inner surface of the internal longitudinal bore.

Optionally, the actuator housing additionally defines a hydraulic space disposed between the actuator piston and the lock sleeve, such that an increase in hydraulic pressure within the hydraulic space urges the lock sleeve in a proximal direction and urge the actuator piston in a distal direction; and the hydraulic space is in fluid communication with a portion of the internal longitudinal bore defining the step, such that an increase in hydraulic pressure within the hydraulic space would urge the locking tab inward within the lock aperture; such that increasing the hydraulic pressure within the hydraulic space translates the lock sleeve in a proximal direction and the distal portion of the lock sleeve therefore moves from the locking position to the unlocked position, permitting the locking tab to move inwardly in the lock aperture under the urging of the increased hydraulic pressure and to disengage from the step, permitting the actuator piston to move from the retracted position to the extended position under the urging of the increased hydraulic pressure.

The thrust reverser further includes an actuator piston biasing spring configured to urge the actuator piston in a proximal direction within the internal longitudinal bore, such that upon a decrease in the hydraulic pressure in the hydraulic space the actuator piston is returned to the retracted position; and optionally, the thrust reverser further includes a lock sleeve biasing spring configured to urge the lock sleeve in a distal direction in the internal longitudinal bore, such that upon a decrease in the hydraulic pressure in the hydraulic space the lock sleeve is returned to the locking position.

Optionally, the thrust reverser further includes a plurality of linear actuators, where each of the plurality of linear actuators includes a source of hydraulic fluid that is coupled to a synchronization mechanism that is coupled to each other linear actuator, so that the synchronization mechanism is configured to coordinate a simultaneous operation of the plurality of linear actuators when deploying the thrust reverser. Optionally, the synchronization mechanism of each linear actuator includes a flexible-shafted cable that extends through an interior of each actuator piston and couples to a synchronization screw that controls hydraulic pressure within that linear actuator.

Optionally, the thrust reverser further includes a sensor disposed adjacent to a proximal end of the actuator housing, the sensor configured to detect an associated sensor target that is coupled to a proximal end of the lock sleeve, such that movement of the lock sleeve from the locking position to the unlocked position is detectable by the sensor.

In a second example there is disclosed a method of manufacturing a locking linear actuator, including manufacturing an elongate actuator housing, where the actuator housing defines an internal longitudinal bore; installing an actuator piston within the internal longitudinal bore, so that the actuator piston is slidably moveable between a proximal retracted position and a distal extended position; and installing a lock sleeve within the internal longitudinal bore proximal to the actuator piston, so that the lock sleeve is slidably moveable between a distal locking position and a proximal unlocked position; such that when the actuator piston is in the retracted position and the lock sleeve is in the locking position, a distal portion of the lock sleeve extends into a proximal portion of the actuator piston to prevent the actuator piston from leaving the retracted position.

Optionally, the actuator housing further defines an internal hydraulic space in fluid communication with the internal longitudinal bore and a step on an inner surface of the internal longitudinal bore; where at least a proximal portion of the actuator piston includes a cylindrical piston sidewall defining at least one lock aperture; where the method further includes installing a locking tab in the at least one lock aperture, such that the locking tab can translate radially within the lock aperture, and when the locking tab extends radially beyond an outer surface of the actuator piston the locking tab engages the step in the inner surface of the internal longitudinal bore and prevents the actuator piston from leaving the retracted position, and the locking tab is in fluid communication with the hydraulic space, such that an increase in hydraulic pressure within the hydraulic space would urge the locking tab inward within the lock aperture; where when the actuator piston is in the retracted position and the lock sleeve is in the locking position, the distal portion of the lock sleeve extended into the proximal portion of the actuator piston prevents the locking tab from moving inwardly and disengaging from the step in the inner surface of the internal longitudinal bore; and an increase in hydraulic pressure within the internal hydraulic space will urge the lock sleeve in a proximal direction and urge the actuator piston in a distal direction; such that by increasing the hydraulic pressure within the hydraulic space the lock sleeve will translate in a proximal direction, permitting the locking tab to move inwardly in the lock aperture under the urging of the increased hydraulic pressure and disengage from the step, permitting the actuator piston to move from the retracted position to the extended position under the urging of the increased hydraulic pressure.

The method of the preceding paragraph further includes installing an actuator piston biasing mechanism to urge the actuator piston in a proximal direction within the internal longitudinal bore, and optionally a lock sleeve biasing mechanism configured to urge the lock sleeve in a distal direction in the internal longitudinal bore, such that upon a decrease in the hydraulic pressure in the hydraulic space the actuator piston will return to the retracted position, the lock sleeve will returned to the locking position, and the locking tab will engage with the step, locking the linear actuator. Optionally, the method further includes attaching a sensor adjacent to a proximal end of the actuator housing, and attaching an associated sensor target to a proximal end of the lock sleeve, such that movement of the lock sleeve from one of the locking position and unlocked position to the other of the locking position and unlocked position results in a movement of the sensor target that is detectable by the sensor and provides an indication that the linear actuator is locked or unlocked.

Optionally, the method of either of the two preceding paragraphs further includes coupling the hydraulic space to a source of pressurized hydraulic fluid.

Optionally, the method of the preceding paragraph further includes coupling the actuator housing to an aircraft engine and coupling the actuator piston to a thrust reverser.

Optionally, the method of the preceding paragraph further includes coupling the thrust reverser to one or more additional linear actuators, and linking each of the coupled linear actuators with a synchronization mechanism so that an operation of the coupled linear actuators is synchronized.

The locking linear actuators disclosed herein, thrust reverser systems that can include one or more of the disclosed locking linear actuators, and methods of manufacturing the disclosed locking linear actuators, provide significant benefits when compared to prior linear actuator designs, particularly with respect to the actuation of aircraft engine thrust reversers.

The presently disclosed locking linear actuators require fewer parts, and cheaper parts, than existing linear actuators. The new actuators exhibit reduced internal wear, and the improved mechanism is simpler to manufacture than previous actuator designs. For example, the actuator cylinder is slimmer and simpler, and does not have to be machined from a large initial piece of stock, reducing costs. Like the actuator cylinder, the lock sleeve of the disclosed locking actuator is smaller and more streamlined than in previous linear actuators, resulting in savings on materials and a decrease in overall actuator size and weight, which results in fuel savings.

The slimmer and smaller geometry of the disclosed linear actuators also permits them to be fitted into aircraft that could not accommodate the larger existing linear actuators, or they will require smaller housings when installed.

The mechanism for lock engagement in the disclosed linear actuators is simpler, but both stronger and more reliable than existing locking mechanisms. The new locking mechanism additionally eliminates sources of potential wear that were created in previous linear actuators. The improved lock sensor system provides both a visual confirmation of lock engagement at the actuator itself, as well as an electronic confirmation within the aircraft cockpit.

Further, the disclosed linear actuators are configured so that disengagement of the lock sleeve, unlocking the linear actuator, can occur very quickly, and the lock sleeve becomes completely disengaged before the actuator piston can begins to move.

The presently described locking linear actuators are smaller, simpler in operation and manufacture, provide a more robust lock engagement, and are less expensive than previously disclosed locking linear actuators, particularly for those used in thrust reverser systems.

Claim 1:
A locking linear actuator (<NUM>), comprising:
an actuator housing (<NUM>) defining an internal longitudinal bore (<NUM>);
an actuator piston (<NUM>) disposed in the internal longitudinal bore (<NUM>), the actuator piston being configured to slidably move between a proximal retracted position and a distal extended position; and
a lock sleeve (<NUM>) disposed in the internal longitudinal bore (<NUM>), the lock sleeve being configured to slidably move between a distal locking position and a proximal unlocked position; and
an actuator piston biasing mechanism (<NUM>) configured to urge the actuator piston (<NUM>) in a proximal direction in the internal longitudinal bore (<NUM>), toward the retracted position;
wherein when the actuator piston (<NUM>) is in the retracted position and the lock sleeve (<NUM>) is in the locking position, a distal portion (<NUM>) of the lock sleeve extends into a proximal portion (<NUM>) of the actuator piston (<NUM>) to prevent the actuator piston from leaving the retracted position.