Patent Description:
A flow control valve directs the flow of a liquid medium, usually oil, through a hydraulic system and controls fluid flow rate provided to an actuator. An example valve has a movable element, e.g., a spool, inside a housing or sleeve and, based on the spool movement in the sleeve, cross-holes defined on the sleeve are opened and closed to achieve the desired flow rate.

<CIT> states that "This invention relates to a flow control device and more particularly to a flow regulating valve operable to maintain a desire constant volume of flow regardless of changes in the pressure of the fluid being controlled. It is the general object of the present invention to produce a new and improved control device of the character described. It is a more specific object of the invention to produce a flow control device having a port and valving means controlling the ports with the valving means being operable to control the area of the ports through which fluid may flow in accordance with changes in fluid pressure so that the volume of flow through the ports is substantially constant.

The present invention relates to a flow control valve, a method of assembly, and a hydraulic system.

In one aspect, the present invention provides a control valve according to claim <NUM>. The flow control valve includes a housing and a sleeve disposed within the housing. The sleeve has a first end and a second end opposite the first end. The sleeve includes a plurality of sleeve protrusions at the first end and a plurality of fluid flow channels are formed between adjacent sleeve protrusions. The flow control valve further includes a seal carrier disposed within the sleeve. The seal carrier includes a carrier protrusion that extends from the second end of the sleeve and abuts against an interior surface of the housing. The flow control valve also includes an end cap mounted to the housing such that the plurality of sleeve protrusions abut against the end cap.

In another aspect, the present invention provides a hydraulic system according to claim <NUM>. The hydraulic system includes a cylinder having a chamber and a flow control valve fluidly coupled to the chamber of the cylinder and configured to control fluid flow to and from the chamber. The flow control valve includes a housing and a sleeve disposed within the housing. The sleeve has a first end and a second end opposite the first end. The sleeve includes a plurality of sleeve protrusions at the first end and a plurality of fluid flow channels are formed between adjacent sleeve protrusion. The flow control valve further includes a seal carrier disposed within the sleeve. The seal carrier includes a carrier protrusion that extends from the second end of the sleeve and abuts against an interior surface of the housing. The flow control valve also includes an end cap mounted to the housing such that the plurality of sleeve protrusions abut against the end cap.

In still another aspect, the invention provides a method according to claim <NUM>.

The method includes positioning a sleeve within a housing. The sleeve has a first end and a second end opposite the first end, and the sleeve includes a plurality of sleeve protrusions at the first end and a plurality of fluid flow channels are formed between adjacent sleeve protrusions. The method also includes positioning a seal carrier within the sleeve. The seal carrier includes a carrier protrusion that extends from the second end of the sleeve and abuts against an interior surface of the housing. The method further includes mounting an end cap to the housing such that the plurality of sleeve protrusions abut against the end cap.

In addition to the illustrative aspects, examples, and features described above, further aspects, examples, and features will become apparent by reference to the figures and the following detailed description.

The novel features believed characteristic of the illustrative examples are set forth in the appended claims. The illustrative examples, however, as well as a preferred mode of use, further objectives and descriptions thereof, will best be understood by reference to the following detailed description of an illustrative example of the present disclosure when read in conjunction with the accompanying Figures.

Within examples, disclosed herein are a flow control valve having a multi-functional sleeve, a hydraulic system, and a method of assembling the flow control valve. The sleeve is disposed within a housing of the flow control valve, and a spool is configured to be slidably accommodated within the sleeve. Based on the spool movement in the sleeve, cross-holes defined by interaction between the spool and the sleeve are opened and closed to achieve the desired flow rate.

The sleeve is configured to allow fluid flow through fluid flow channels formed in the sleeve. The sleeve further has a slot or cavity to hold an orifice plug rather than using a separate lock nut and orifice plate. This way, additional parts can be eliminated while their features are included in the sleeve. As such, the valve can have a reduced number of parts compared to conventional valves, and may thus have reduced weight and cost.

Further, the orifice plug integrated with the sleeve can operate as a safety feature, which allows a particular amount of fluid flow rate therethrough (e.g., at least a minimum fluid flow) when a component operates in an unintended manner that blocks the cross-holes. As such, the valve enables operating an actuator in applications despite unintended operation of certain components of the valve. By providing a minimum fluid flow therethrough when a component operates in an unintended manner, the valves enables movement of the actuator to a safe position in some applications. An example application in which the valve can be used is the hydraulic system configured to control operation of a main landing gear of an aircraft. However, it should be understood that the flow control valve disclosed herein can be used with other types of actuators and applications.

<FIG> illustrates an aircraft <NUM> having a tricycle landing gear configuration, in accordance with an example implementation. The tricycle landing gear configuration includes a type of aircraft landing gear in which a single nose wheel is positioned at a front of the aircraft <NUM> and two main wheels are positioned slightly aft of a center of gravity of the aircraft <NUM>. For example, the aircraft <NUM> has a nose landing gear <NUM> having a wheel in the front. The aircraft <NUM> also has two main landing gears, main landing gear <NUM> and main landing gear <NUM>, with associated wheels slightly aft of the center of gravity of the aircraft <NUM>.

The main landing gear <NUM>, for example, includes an actuator, such as an actuator <NUM> (shown in <FIG>), having a piston axially-movable within a cylinder and configured to deploy the wheels during landing and retract the wheels in a wheel well after takeoff of the aircraft <NUM>. Within examples, the actuator is operated in a controlled manner by controlling the amount of fluid flow rate provided to the actuator to move the piston at a particular desired speed, and to enable the actuator to operate and deploy or retract the main landing gear <NUM> in a safe manner. The main landing gear <NUM> is configured in a similar manner. An example hydraulic system described below is configured to control the actuator of a main landing gear such as the main landing gear <NUM> or the main landing gear <NUM>.

<FIG> illustrates a schematic representation of a hydraulic system <NUM> configured to control main landing gear of an aircraft, in accordance with an example implementation. For example, the hydraulic system <NUM> controls the main landing gear <NUM> or the main landing gear <NUM> of the aircraft <NUM>.

The hydraulic system <NUM> includes a cylinder (e.g., cylinder <NUM> described below) having a chamber (e.g., the chamber <NUM> described below). The hydraulic system <NUM> also includes a flow control valve (e.g., the flow control valve <NUM>) fluidly coupled to the chamber of the cylinder and configured to control fluid flow to and from the chamber.

An example configuration of the flow control valve <NUM> is described below with respect to <FIG>. In examples, the hydraulic system <NUM> includes other components as described below.

The hydraulic system <NUM> receives pressurized fluid <NUM> from a landing gear transfer valve that is fluidly coupled to a source of fluid (e.g., a pump, an accumulator, or another valve from a different part of a hydraulic circuit of the aircraft). The pressurized fluid <NUM> is then provided to an inlet fluid line <NUM>. The hydraulic system <NUM> provides return fluid flow through a return fluid line <NUM> to the landing gear transfer valve, which then provides the return fluid to a fluid reservoir, or a different part of the hydraulic circuit of the aircraft.

The hydraulic system <NUM> includes a landing gear selector valve <NUM> that is fluidly coupled to the inlet fluid line <NUM> and the return fluid line <NUM>. In an example, the landing gear selector valve <NUM> is configured as a directional control valve.

The landing gear selector valve <NUM> is actuatable via an electric actuator (e.g., solenoid actuator), a fluidic actuator, or a mechanical actuator, as examples. For instance, the landing gear selector valve <NUM> has a spool within a valve body and the spool is movable in a first linear direction or a second direction opposite the first direction based on an actuation signal to the landing gear selector valve <NUM> (e.g., actuation signal to one of two solenoids of an solenoid actuator). Based on the direction of movement of the spool, the landing gear selector valve <NUM> provides pressurized fluid to a fluid line <NUM> while the return flow is received via a fluid line <NUM>, or the landing gear selector valve <NUM> provides pressurized fluid to the fluid line <NUM> while the return flow is received via the fluid line <NUM>.

The fluid line <NUM> can be referred to as a down pressure fluid line, whereas the fluid line <NUM> can be referred to as up pressure fluid line. "Down pressure" refers to the fluid line receiving pressurized fluid when the main landing gear is deployed (moving down from the wheel well in the aircraft in preparation for landing), whereas "up pressure" refers to the fluid line receiving pressurized fluid when the main landing gear is retracted (moving up toward the wheel well in the aircraft after takeoff). As illustrated by the key of <FIG>, fluid lines with circles therein represent fluid lines involved in retracting the main landing gear, and the fluid lines with cross-hatching represent fluid lines involved in deploying the main landing gear.

The hydraulic system <NUM> includes a volume fuse <NUM>. The volume fuse <NUM> is configured to allow a particular amount of fluid volume to pass therethrough in a single operative cycle. If such amount of fluid volume is exceeded, the volume fuse <NUM> shuts off fluid flow. In this example, the volume fuse <NUM> protects the hydraulic system <NUM> from line rupture in the hydraulic system <NUM> as described below, while resetting after every operative cycle when less than the predetermined volume flows therethrough.

The hydraulic system <NUM> also includes a flow control valve <NUM>, which can be referred to as a flow regulator, configured to control fluid flow rate provided to and discharged from a main landing gear actuator <NUM>. The flow control valve <NUM> is fluidly coupled to a transfer cylinder <NUM> and a frangible fitting <NUM>. As descried below, the frangible fitting <NUM> works with the volume fuse <NUM> to provide a safety feature for the hydraulic system <NUM>, and the transfer cylinder <NUM> is configured as a time delay element to allow a locking mechanism of the main landing gear to be released prior to deploying or retracting the main landing gear.

The main landing gear actuator <NUM> includes a cylinder <NUM> and a piston <NUM> slidably accommodated within the cylinder <NUM>. The term "slidably accommodated" is used herein to indicate that a first component (e.g., the piston <NUM>) is positioned relative to a second component (e.g., the cylinder <NUM>) such that the first component is able to move relative to the second component.

The piston <NUM> includes a piston head <NUM> and a piston rod <NUM> extending from the piston head <NUM> along a central longitudinal axis direction of the cylinder <NUM>. The piston head <NUM> divides the inside or internal space of the cylinder <NUM> into a chamber <NUM> and a chamber <NUM>. The chamber <NUM> can be referred to as a cap chamber or head chamber, whereas the chamber <NUM> can be referred to as a rod chamber.

The piston rod <NUM> is configured to be coupled to the main landing gear. For example, the end of the piston rod <NUM> is configured to be coupled to a strut or other mechanism coupled to the wheel assembly of the main landing gear. The main landing gear actuator <NUM> is configured such that when the piston <NUM> extends (e.g., moves to the left in <FIG>), the main landing gear and the wheels are retracted or withdrawn into the wheel well after takeoff. On the other hand, when the piston <NUM> retracts (e.g., moves to the right in <FIG>), the main landing gear and the wheels are deployed from the wheel well in preparation for landing.

As mentioned above, the main landing gear has a locking mechanism that is released prior to allowing the main landing gear to be retracted or deployed. The locking mechanism is coupled to and releasable by a downlock actuator <NUM> and an uplock actuator <NUM>. For example, the downlock actuator <NUM> locks the main landing gear in place when the main landing gear is deployed. The downlock actuator <NUM> is then actuated to release the locking mechanism prior to retracting the main landing gear. On the other hand, the uplock actuator <NUM> locks the main landing gear in place when the main landing gear is retracted in the wheel well. The uplock actuator <NUM> is then actuated to release the locking mechanism prior to deploying the main landing gear.

The downlock actuator <NUM> and the uplock actuator <NUM> are generally configured similar to the main landing gear actuator <NUM>. The downlock actuator <NUM> includes a cylinder <NUM> and a piston <NUM> slidably accommodated within the cylinder <NUM>. The piston <NUM> includes a piston head <NUM> and a piston rod <NUM> extending from the piston head <NUM> along a central longitudinal axis direction of the cylinder <NUM>. The piston head <NUM> divides an internal space of the cylinder <NUM> into a chamber <NUM> and a chamber <NUM>.

Similarly, the uplock actuator <NUM> includes a cylinder <NUM> and a piston <NUM> slidably accommodated within the cylinder <NUM>. The piston <NUM> includes a piston head <NUM> and a piston rod <NUM> extending from the piston head <NUM> along a central longitudinal axis direction of the cylinder <NUM>. The piston head <NUM> divides an internal space of the cylinder <NUM> into a chamber <NUM> and a chamber <NUM>.

The hydraulic system <NUM> is also illustrated to include other components. For example, the hydraulic system <NUM> includes several restrictor check valves including restrictor check valve <NUM>, restrictor check valve <NUM>, and restrictor check valve <NUM>. A restrictor check valve is configured to allow free fluid flow (e.g., with minimal pressure drop) in one direction (in the direction of an arrow depicted in the symbols of the restrictor check valves) while restricting fluid flow in the other direction (where a restrictor is depicted in the symbols of the restrictor check valves).

The hydraulic system <NUM> can further include relief valves to release pressurized fluid if pressure level in a particular chamber or fluid line exceeds a particular threshold pressure value. For example, the hydraulic system <NUM> includes a relief valve <NUM> configured to open and provide a fluid path for fluid in the chamber <NUM> of the downlock actuator <NUM> if pressure level of fluid therein exceeds a threshold value.

The hydraulic system <NUM> is operable in a first mode of operation associated with extending the piston <NUM> of the main landing gear actuator <NUM> (e.g., moving the piston <NUM> to the left in <FIG>), which corresponds to retracting the main landing gear back into the wheel well after takeoff of the aircraft. The hydraulic system <NUM> is operable in a second mode of operation associated with retracting the piston <NUM> of the main landing gear actuator <NUM> (e.g., moving the piston <NUM> to the right in <FIG>), which corresponds to deploying the main landing gear from the wheel well in preparation for landing the aircraft.

The hydraulic system <NUM> is depicted in <FIG> with arrows illustrating fluid flow directions in the first mode of operation. In this first mode of operation, the landing gear selector valve <NUM> provides fluid flow to the fluid line <NUM>. In an example, the fluid line <NUM> is fluidly coupled to an alternate brake system <NUM> via a fluid line <NUM> as depicted in <FIG>. The alternate brake system <NUM> is configured to become active when a normal brake system of the aircraft is faulty and/or low hydraulic pressure is detected in the normal braking system. As such, if the normal braking system is faulty, pressurized fluid is provided via the fluid line <NUM> to the alternate brake system <NUM> to brake the wheels and stop their spinning while retracting the main landing gear, thereby preventing damage to components within the wheel well of the aircraft.

Pressurized fluid is provided via the fluid line <NUM> to the volume fuse <NUM>, which allows fluid to flow therethrough as long as the fluid volume does not exceed a particular capacity of the volume fuse <NUM>. Fluid is then provided to the flow control valve <NUM>, which operates to control the amount of fluid flow rate provided to the main landing gear actuator <NUM> so as to move the piston <NUM> in a controlled manner, e.g., at a desired speed.

Fluid passing through the flow control valve <NUM> then flows to the transfer cylinder <NUM>. The transfer cylinder <NUM> is configured to delay providing fluid to the chamber <NUM> until the locking mechanism of the main landing gear is released. Particularly, the transfer cylinder <NUM> is configured as a time-delay element that allows fluid flow to be provided to the downlock actuator <NUM> to release the locking mechanism of the main landing gear prior to retracting the main landing gear. For example, the transfer cylinder <NUM> includes a piston <NUM> that divides the inner space of the transfer cylinder <NUM> into two chambers.

Fluid is provided to the transfer cylinder <NUM> from the flow control valve <NUM> and causes the piston <NUM> to move (e.g., to the left in <FIG>). As long as the piston <NUM> is moving and fluid is filling the transfer cylinder <NUM>, fluid is not provided to the main landing gear actuator <NUM>. Once the piston <NUM> reaches the end of its stroke within the transfer cylinder <NUM>, fluid is diverted to the restrictor check valve <NUM> and the main landing gear actuator <NUM>.

While the piston <NUM> of the transfer cylinder <NUM> is moving, fluid is being provided from the volume fuse <NUM> through a restrictor <NUM> to the chamber <NUM> of the downlock actuator <NUM>. Fluid provided to the chamber <NUM> causes the piston <NUM> to extend (e.g., move to the left in <FIG>). As the piston <NUM> of the transfer cylinder <NUM> reaches the end of its stroke, the piston <NUM> has also extended sufficiently to release the locking mechanism and allow the main landing gear to retract.

As the locking mechanism is released, fluid is provided through the restrictor check valve <NUM> to the chamber <NUM> of the main landing gear actuator <NUM>, causing the piston <NUM> to extend (e.g., move to the left in <FIG>), thereby retracting the main landing gear toward the wheel well after takeoff. The braking system of the aircraft is configured to brake the wheels and prevent the wheels from spinning prior to reaching the wheel well so as to avoid damage to the wheel well. In an instance where the wheels keep spinning, the hydraulic system <NUM> is configured to stop the main landing gear from retracting further (i.e., stop the piston <NUM> from extending) as a safety feature to avoid damage to the wheel well.

In particular, the frangible fitting <NUM> has a lever <NUM>. The frangible fitting is configured such that the lever <NUM> breaks if the wheels of the main landing gear continue to spin as the wheels retract. When the lever <NUM> breaks, fluid from the flow control valve <NUM> flows through the frangible fitting <NUM>, then to an outside environment of the hydraulic system <NUM>, e.g., to a low pressure volume, as fluid flows through a path of least resistance. As a result, the fluid flow rate flowing through the volume fuse <NUM> can increase and exceed its capacity, and responsively the volume fuse <NUM> shuts off fluid flow therethrough.

This way, fluid is not provided to the flow control valve <NUM> and the piston <NUM> stops extending to preclude the main landing gear from retracting further. However, the piston <NUM> is allowed to retract so as to cause the main landing gear to deploy and the aircraft to land safely.

As mentioned above, the hydraulic system <NUM> is also operable in the second mode of operation associated with retracting the piston <NUM> of the main landing gear actuator <NUM> (e.g., moving the piston <NUM> to the right in <FIG>), which corresponds to deploying the main landing gear from the wheel well in preparation for landing the aircraft.

<FIG> illustrates the schematic representation of the hydraulic system <NUM> with arrows illustrating fluid flow directions in the second mode of operation, in accordance with an example implementation. In this second mode of operation, the landing gear selector valve <NUM> provides fluid flow to the fluid line <NUM>. Pressurized fluid flowing through the fluid line <NUM> flows through a fluid line <NUM> through the restrictor check valve <NUM>, then to the transfer cylinder <NUM>. As depicted in <FIG>, the fluid line <NUM> is also connected to the chamber <NUM> of the uplock actuator <NUM> via a restrictor <NUM>.

The transfer cylinder <NUM> operates in a manner similar to its operation in the first mode of operation, but the piston <NUM> moves in the other direction (e.g., to the right in <FIG>). As such, the transfer cylinder <NUM> operates as a time-delay element that allows fluid flow to be provided to the uplock actuator <NUM> to release the locking mechanism of the main landing gear prior to deploying the main landing gear. As the piston <NUM> moves and the fluid provided through the restrictor check valve <NUM> fills the transfer cylinder <NUM>, fluid is not provided to the chamber <NUM> of the main landing gear actuator <NUM>. Once the piston <NUM> reaches the end of its stroke within the transfer cylinder <NUM>, fluid is provided to the chamber <NUM> of the main landing gear actuator <NUM>.

While the piston <NUM> of the transfer cylinder <NUM> is moving, fluid is being provided from the fluid line <NUM> through the restrictor <NUM> to the chamber <NUM> of the uplock actuator <NUM>. Fluid provided to the chamber <NUM> causes the piston <NUM> to retract (e.g., move to the left in <FIG>). As the piston <NUM> of the transfer cylinder <NUM> reaches the end of its stroke, the piston <NUM> has also extended sufficiently to release the locking mechanism and allow the main landing gear to deploy.

Fluid discharged from the chamber <NUM> as the piston <NUM> retracts flows through fluid line <NUM> to a shimmy damper <NUM> and the return fluid line <NUM>. Shimmy is an oscillation in a landing gear that generates undesirable vibration and loads on a structure of the landing gear. The shimmy damper <NUM> dampens oscillations that might occur in movement of the piston <NUM> to ensure smooth operation of the hydraulic system <NUM>.

As the locking mechanism is released, fluid is provided to the chamber <NUM> of the main landing gear actuator <NUM>, causing the piston <NUM> to retract (e.g., move to the right in <FIG>), thereby deploying the main landing gear from the wheel well in preparation for landing the aircraft. Fluid discharged from the chamber <NUM> as the piston <NUM> retracts flows through the restrictor check valve <NUM>, then to the flow control valve <NUM>. The flow control valve <NUM> controls the amount of fluid flow rate discharged from the main landing gear actuator <NUM> so as to move the piston <NUM> in a controlled manner, e.g., at a desired speed.

Particularly, the flow control valve <NUM> generates a back pressure in the chamber <NUM> as flow control valve <NUM> controls fluid flow therethrough, thereby causing the piston <NUM> to retract in a controlled manner. Fluid exiting the flow control valve <NUM> flows through the volume fuse <NUM> and the landing gear selector valve <NUM> to the return fluid line <NUM>. As such, the flow control valve <NUM> is configured to cause the piston <NUM> of the main landing gear actuator <NUM> to move in a controlled manner.

<FIG> illustrates a perspective view of the flow control valve <NUM>, <FIG> illustrates a cross-sectional view of the flow control valve <NUM>, and <FIG> illustrates a perspective cross-sectional view of the flow control valve <NUM>, in accordance with an example implementation. <FIG> are described together.

The flow control valve <NUM> includes a housing <NUM>, a sleeve <NUM> disposed within the housing <NUM>, and the sleeve <NUM> has a proximal or first end and a distal or second end opposite the first end. The sleeve <NUM> includes a plurality of sleeve protrusions <NUM>-<NUM> at the first end and a plurality of fluid flow channels <NUM>-<NUM> (e.g., fluid flow channel <NUM>, <NUM>, <NUM>, and <NUM> for a total of four fluid flow channels) are formed between adjacent sleeve protrusions of the sleeve protrusions <NUM>-<NUM>. The flow control valve <NUM> also includes a seal carrier <NUM> disposed within the sleeve <NUM>, and the seal carrier <NUM> includes a carrier protrusion <NUM>, <NUM> that extends from the second end of the sleeve <NUM> and abuts against an interior surface of the housing <NUM>. The flow control valve <NUM> also includes an end cap <NUM> mounted to the housing <NUM> such that the plurality of sleeve protrusions <NUM>-<NUM> abut against the end cap <NUM>.

The housing <NUM> is generally cylindrical and having a longitudinal cylindrical cavity defined therein. Components of the flow control valve <NUM> are disposed in the longitudinal cylindrical cavity of the housing <NUM>. The housing <NUM> has a first port <NUM> (e.g., an opening) at a distal end <NUM> of the housing <NUM>. The first port <NUM> allows fluid flow therethrough into and out of the flow control valve <NUM>. For instance, the first port <NUM> can be fluidly coupled to the transfer cylinder <NUM>, the frangible fitting <NUM>, and the restrictor check valve <NUM>.

The end cap <NUM> is coupled to the housing <NUM> at a proximal end <NUM> thereof. For example, the end cap <NUM> is threadedly coupled to the housing <NUM> via external thread in the end cap <NUM> and internal threads in the housing <NUM> at threaded region <NUM>. The end cap <NUM> can keep the flow control valve <NUM> intact and free of chatter and vibrations that can cause components of the flow control valve <NUM> to shift internally.

The end cap <NUM> has a second port <NUM> (e.g., an opening) at a proximal end <NUM> of the flow control valve <NUM> opposite the first port <NUM>. The second port <NUM> allows fluid flow therethrough into and out of the flow control valve <NUM>. For instance, the second port <NUM> can be fluidly coupled to the volume fuse <NUM>. The flow control valve <NUM> is bi-directional and allows fluid flow therethrough from the first port <NUM> to the second port <NUM> or from the second port <NUM> to the first port <NUM>.

The flow control valve <NUM> includes a seal <NUM> (e.g., an O-ring) disposed in in an exterior annular groove formed in the end cap <NUM> and configured to form a fluid seal between the end cap <NUM> and the housing <NUM> to prevent leakage to an outside environment of the flow control valve <NUM>. In an example, the seal <NUM> is interposed between backup rings. Backup rings can be used, for example, to reduce the likelihood of extrusion of the seal <NUM> as pressurization and depressurization/pressure cycling occurs within the flow control valve <NUM>.

The sleeve <NUM> is fixedly disposed within the housing <NUM>. The sleeve <NUM> is generally cylindrical and includes a respective longitudinal cylindrical cavity therein.

<FIG> illustrates a perspective view of the sleeve <NUM>, and <FIG> illustrates a cross-sectional view of the sleeve <NUM>, in accordance with an example implementation. <FIG> are described together.

The sleeve <NUM> has a plurality of sleeve protrusions such as sleeve protrusion <NUM>, sleeve protrusion <NUM>, sleeve protrusion <NUM>, and sleeve protrusion <NUM> disposed at a proximal end <NUM> of the sleeve <NUM>. In an example, the sleeve protrusions <NUM>-<NUM> are disposed in an array such as a circular array as depicted in <FIG>. However, other array configurations (e.g., rectangular array, square array, etc.) can be used.

Further, in examples as depicted in <FIG>, the sleeve protrusions <NUM>-<NUM> are arcuate in shape. However, in other examples, the sleeve protrusions <NUM>-<NUM> have other shapes, e.g., they can be straight or rectangular. Regardless of the configurations of the sleeve protrusions <NUM>-<NUM>, the sleeve protrusions <NUM>-<NUM> form fluid flow channels therebetween, such as fluid flow channel <NUM>, fluid flow channel <NUM>, fluid flow channel <NUM>, and fluid flow channel <NUM>.

The sleeve <NUM> includes a hole <NUM> (e.g., a stepped hole) that defines several steps or shoulders by the interior surface of the sleeve <NUM> at the proximal end <NUM> of the sleeve <NUM> to accommodate other components of the flow control valve <NUM>. In other words, an internal diameter of the sleeve <NUM> varies to define cavities therein having different sizes. For example, a cavity <NUM>, which is a portion of the hole <NUM>, is configured to receive an orifice plug as described below. A shoulder <NUM> is defined by a transition in the internal diameter of the sleeve <NUM>, and the shoulder <NUM> is configured to support a spring washer as described below. The shoulder <NUM> can prohibit a direct flow of fluid from one chamber to another, and directs fluid to flow through the cross-holes, as described below.

The sleeve <NUM> includes a first set of cross-holes disposed in an array about a wall of body of the sleeve <NUM>, such as cross-hole <NUM> and cross-hole <NUM>. For example, the first set of cross-holes is disposed in a circular array about the sleeve <NUM>. The sleeve <NUM> further includes a second set of cross-holes also disposed in an array (e.g., a circular array) about the wall of the sleeve <NUM>, such as cross-hole <NUM> and cross-hole <NUM>. The second set of cross-holes is axially-spaced from the first set of cross-hole along a length of the sleeve <NUM>. The term "cross-hole" is used herein to indicate a hole that crosses a path of, or is formed transverse relative to, another hole, cavity, or channel.

The sleeve <NUM> also includes a first flanged portion <NUM> and a second flanged portion <NUM> that form a groove <NUM>, e.g., an exterior annular groove, therebetween. The exterior surfaces of the first flanged portion <NUM> and the second flanged portion <NUM> interface with the interior surface of the housing <NUM> (as shown in <FIG>), and the groove <NUM> is configured to receive a seal and backup rings therein as described below.

As depicted in <FIG>, the internal diameter of the sleeve <NUM> enlarges near its distal end <NUM> to form a shoulder <NUM> and a cavity <NUM>. The cavity <NUM> is configured to receive the seal carrier <NUM>, which abuts against the shoulder <NUM>.

Referring to <FIG> along with <FIG>, the flow control valve <NUM> includes an orifice plug <NUM> disposed in the cavity <NUM> of the sleeve <NUM>. The orifice plug <NUM> is configured to have an orifice <NUM> formed therein, e.g., drilled therein, to allow a particular amount of fluid flow rate therethrough.

As shown in <FIG>, the sleeve <NUM> is disposed within the housing <NUM> such that a first chamber <NUM> is formed between the exterior surface of the sleeve <NUM> and the interior surface of the housing <NUM>. Similarly, a second chamber <NUM> is formed between the exterior surface of the sleeve <NUM> and the interior surface of the housing <NUM>. The first chamber <NUM> is separated from the second chamber <NUM> by way of the flanged portion <NUM> and the flanged portion <NUM> of the sleeve <NUM>.

Further, the flow control valve <NUM> includes a seal <NUM> disposed in the groove <NUM> of the sleeve <NUM> to seal the first chamber <NUM> from the second chamber <NUM>. Backup rings can be disposed about the seal <NUM> to reduce the likelihood of extrusion of the seal <NUM> in the groove <NUM> of the sleeve <NUM> as pressurization and de-pressurization/pressure cycling occurs within the flow control valve <NUM>.

The seal carrier <NUM> is disposed in the cavity <NUM> of the sleeve <NUM>. Similar to the sleeve <NUM>, the seal carrier <NUM> has a plurality of carrier protrusions, such as carrier protrusion <NUM> and carrier protrusion <NUM>, which form fluid flow channels therebetween such as fluid flow channel <NUM>. As examples, the carrier protrusions <NUM>, <NUM> are arcuate in shape and are disposed in a circular array. However, other configurations are possible. Further, the seal carrier <NUM> includes a seal <NUM> (e.g., an O-ring) disposed in an exterior annular groove formed in the seal carrier <NUM> and configured to form a fluid seal between the seal carrier <NUM> and the sleeve <NUM> to prevent fluid leakage therebetween. Backup rings can be used with the seal <NUM> as well.

The seal carrier <NUM> is further configured to receive an orifice plug <NUM> that is similar to the orifice plug <NUM>. The orifice plug <NUM> has an orifice <NUM> formed therein to allow a particular amount of fluid flow rate therethrough.

As shown in <FIG>, the sleeve protrusions <NUM>-<NUM> abut against a distal end <NUM> of the end cap <NUM>. As such, the sleeve <NUM> is secured axially in the proximal direction via the end cap <NUM>.

Further, the seal carrier <NUM> is secured in the proximal direction via the shoulder <NUM> of the sleeve <NUM> (see <FIG>). Also, the carrier protrusions (e.g., the carrier protrusions <NUM>, <NUM>) extend from the distal end <NUM> of the sleeve <NUM> and abut against an interior surface of the housing <NUM>, and thus the seal carrier <NUM> is secured axially in the distal direction by the housing <NUM>. With this configuration, the sleeve <NUM> and the seal carrier <NUM> are longitudinally secured within the housing <NUM> via their own features (the sleeve and carrier protrusions, and shoulders) and no additional components (e.g., a spacer) are used.

The flow control valve <NUM> further includes a spool <NUM> slidably accommodated and axially-movable within the longitudinal cylindrical cavity of the sleeve <NUM>. The spool <NUM> is hollow and forms a spool shoulder <NUM>, which is a ring-shaped protrusion or annulus, having a hole <NUM> therethrough.

Also, as shown in <FIG>, the spool <NUM> is configured to receive a first spring <NUM> and a second spring <NUM> therein. Particularly, the first spring <NUM> has a proximal end <NUM> resting against a spring washer <NUM>, which in turn rests against the shoulder <NUM> of the sleeve <NUM> (see <FIG>), whereas a distal end <NUM> of the first spring <NUM> rests against one side the spool shoulder <NUM> of the spool <NUM>. On the other hand, a proximal end <NUM> of the second spring <NUM> rests against the other side of the spool shoulder <NUM>, whereas a distal end <NUM> of the second spring <NUM> rests against a shoulder formed by the seal carrier <NUM>.

With this configuration, the first spring <NUM> applies a first spring force on the spool <NUM> in a distal direction, and the second spring <NUM> applies a second spring force on the spool <NUM> in the proximal direction. The spring forces maintain the spool <NUM> in a center position. However, if pressure level of fluid at one side of the spool shoulder <NUM> is different from pressure level of fluid on the other side of the spool shoulder <NUM>, the spool <NUM> moves axially against the spring force of one of the springs as described below.

When the spool <NUM> is in the centered position shown in <FIG>, the proximal end <NUM> of the spool <NUM> partially overlaps the first set of cross-holes (e.g., the cross-hole <NUM> and the cross-hole <NUM>), whereas the distal end <NUM> of the spool <NUM> partially overlaps the second set of cross-holes (e.g., the cross-hole <NUM> and the cross-hole <NUM>). If the spool <NUM> moves in a distal direction, the second set of cross-holes are restricted further (more of the cross-holes is blocked and the opening sizes of the cross-holes that allow fluid flow decrease), whereas the first set of cross-holes are exposed more (more of the cross-holes is uncovered and the opening sizes of the cross-holes that allow fluid flow increase).

On the other hand, if the spool <NUM> moves in a proximal direction, the first set of cross-holes are restricted further (more of the cross-holes is blocked and the opening sizes of the cross-holes that allow fluid flow decrease), whereas the second set of cross-holes are exposed more (more of the cross-holes is uncovered and the opening sizes of the cross-holes that allow fluid flow increase). With this configuration, as the spool <NUM> moves axially within the sleeve <NUM>, fluid flow rate and pressure levels are modulated during operation.

For example, if the direction of fluid flow is from the second port <NUM> to the first port <NUM>, fluid is received at the second port <NUM> then flows through the end cap <NUM> to the proximal end <NUM> of the sleeve <NUM>. Fluid then flows radially outward through the fluid flow channels of the sleeve <NUM> (i.e., the fluid flow channels <NUM>-<NUM> shown in <FIG>) to the first chamber <NUM>. Fluid then flows radially inward through the first set of cross-holes (e.g., the cross-hole <NUM> and the cross-hole <NUM>) to the spool chamber having the first spring <NUM> within the spool <NUM>.

Fluid then flows through the hole <NUM> of the spool shoulder <NUM> to the spool chamber having the second spring <NUM>. As fluid flows through the hole <NUM>, a pressure drop occurs (a decrease in pressure level of fluid occurs due to flowing through a fluid restriction caused by the hole <NUM>). This pressure drop causes the fluid force acting on the spool <NUM> in the distal direction to increase relative to the fluid force acting on the spool <NUM> in the proximal distal direction, causing the spool <NUM> to move in the distal direction. As the spool <NUM> moves in the distal direction, the second spring <NUM> is compressed and the first spring <NUM> is relaxed.

Further, as the spool <NUM> moves in the distal direction, the second set of cross-holes are restricted, whereas the first set of cross-holes are exposed more. Fluid in the spring chamber of the second spring <NUM> flows radially outward through the second set of cross-holes (that are now more restricted) to the second chamber <NUM>. From the second chamber <NUM>, fluid flows radially inward through the fluid flow channels of the seal carrier <NUM> (e.g., the fluid flow channel <NUM>), then through the first port <NUM> and out of the flow control valve <NUM>.

While a portion of the fluid received at the second port <NUM> flows through the above-described path (i.e., through the fluid flow channels, the annular chambers between the sleeve <NUM> and the housing <NUM>, the sets of cross-holes), another portion of the fluid flows through the orifice plug <NUM> and the orifice <NUM>, then through the orifice plug <NUM> and the orifice <NUM> to the first port <NUM> and out of the flow control valve <NUM>. This configuration provides a safety feature where a particular amount of flow is provided through the flow control valve <NUM> in an event of unexpected issues. The safety feature is beneficial, for example, to allow the particular amount of fluid flow through the flow control valve <NUM> so as to allow the main landing gear actuator <NUM> to operate despite any issues.

Particularly, if the first spring <NUM> or the second spring <NUM> does not operate as intended, the spool <NUM> is biased all the way in one direction by the other spring, thereby completely or substantially blocking the first set of cross-holes (e.g., the cross-hole <NUM> and the cross-hole <NUM>) or the second set of cross-holes (e.g., the cross-hole <NUM> and the cross-hole <NUM>). As a result, fluid flowing through the cross-holes to and from the first chamber <NUM> or the second chamber <NUM> is blocked. However, fluid flows through the orifice <NUM> of the orifice plug <NUM> and the orifice <NUM> of the orifice plug <NUM>. In this example, at least a certain amount of a fluid flow is provided through the flow control valve <NUM> to operate the main landing gear actuator <NUM>.

As an example for illustration, the flow control valve <NUM> has a fluid flow rate capacity of about <NUM> gallons per minute (<NUM> GPM = <NUM>,<NUM>/s).

A portion of that amount (e.g., half or <NUM> GPM = <NUM>,<NUM>/s) flows through the fluid flow channels <NUM>-<NUM>, the first chamber <NUM>, the first set of cross-holes, the second set of cross-holes, the second chamber <NUM>, and the fluid flow channels of the seal carrier <NUM> (e.g., the fluid flow channel <NUM>). The remaining portion (e.g., the other half or <NUM> GPM = <NUM>,<NUM>/s) flows through the orifice <NUM> and the orifice <NUM>. In this example, at least <NUM> GPM (<NUM>,<NUM>/s) are provided from the second port <NUM> to the first port <NUM> if any unintended operation occurs within the flow control valve <NUM>.

The flow control valve <NUM> is a bi-directional valve as mentioned above and also allows for fluid flow in the other direction, i.e., from the first port <NUM> to the second port <NUM>. Particularly, fluid is received at the first port <NUM> then flows radially outward from the fluid flow channels of the seal carrier <NUM> (e.g., the fluid flow channel <NUM>) to the second chamber <NUM>. Fluid then flows radially inward through the second set of cross-holes (e.g., the cross-hole <NUM> and the cross-hole <NUM>) to the spool chamber having the second spring <NUM> within the spool <NUM>.

Fluid then flows through the hole <NUM> of the spool shoulder <NUM> to the spool chamber having the first spring <NUM>. As fluid flows through the hole <NUM>, a pressure drop occurs. This pressure drop causes the fluid force acting on the spool <NUM> in the distal direction to increase relative to the fluid force acting on the spool <NUM> in the proximal distal direction, causing the spool <NUM> to move in the proximal direction. As the spool <NUM> moves in the proximal direction, the first spring <NUM> is compressed and the second spring <NUM> is relaxed.

Further, as the spool <NUM> moves in the proximal direction, the first set of cross-holes are restricted, whereas the second set of cross-holes are exposed more. Fluid in the spring chamber of the first spring <NUM> flows radially outward through the first set of cross-holes (that are now more restricted) to the first chamber <NUM>. From the first chamber <NUM>, fluid flows radially inward through the fluid flow channels <NUM>-<NUM> of the sleeve <NUM>, then through the second port <NUM> and out of the flow control valve <NUM>.

While a portion of the fluid received at the first port <NUM> flows through the above-described path (i.e., through the fluid flow channels, the annular chambers, the sets of cross-holes), another portion of the fluid flows through the orifice plug <NUM> and the orifice <NUM>, then through the orifice plug <NUM> and the orifice <NUM> to the second port <NUM> and out of the flow control valve <NUM>. This configuration provides a safety feature where a particular amount of flow is provided through the flow control valve <NUM> if any unintended operation occurs as described above.

Within examples, the configuration of the flow control valve <NUM> can offer several advantages over conventions valves. For example, the sleeve <NUM> is configured as a multi-functional sleeve that integrates features therein instead of having additional components. For instance, rather than using a second seal carrier (in addition to the seal carrier <NUM>) at the proximal end <NUM> of the sleeve <NUM>, the features of such an additional seal carrier are integrated into the sleeve <NUM>.

Particularly, the fluid flow channels <NUM>-<NUM> are integrated in the sleeve <NUM>, the orifice plug <NUM> is secured within the sleeve <NUM>, and no seal or backup rings are used. In this example, by eliminating an additional seal carrier and its associated components (seals, backup rings, etc.) a cost and weight of the flow control valve <NUM> are can be reduced, and also the reliability can be increased by reducing the number of components in operation.

Further, the sleeve protrusions <NUM>-<NUM> abut the end cap <NUM>, and therefore no additional spacer is used to secure the sleeve <NUM> axially within the housing <NUM>. As such, another component is eliminated by the multi-functionality of the sleeve <NUM>.

<FIG> is a flowchart of a method <NUM> for assembling the flow control valve <NUM>, in accordance with an example implementation. The method <NUM> includes one or more operations, or actions as illustrated by one or more of blocks <NUM>-<NUM>. Although the blocks are illustrated in a sequential order, in example, these blocks are performed in parallel, and/or in a different order than those described herein. Also, in example, the various blocks are combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation. It should be understood that for this and other processes and methods disclosed herein, flowcharts show functionality and operation of one possible implementation of present examples. Alternative implementations are included within the scope of the examples of the present invention in which functions are executed out of order from that shown or discussed, including substantially concurrent or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art.

At block <NUM>, the method <NUM> includes positioning the sleeve <NUM> within the housing <NUM>, and the sleeve <NUM> has a first end (e.g., the proximal end <NUM>) and a second end (e.g., the distal end <NUM>) opposite the first end. The sleeve <NUM> includes the sleeve protrusions <NUM>-<NUM> at the first end and the plurality of fluid flow channels <NUM>-<NUM> are formed between adjacent sleeve protrusions, e.g., between the sleeve protrusions <NUM>-<NUM>.

At block <NUM>, the method <NUM> includes positioning the seal carrier <NUM> within the sleeve <NUM>, and the seal carrier <NUM> includes the carrier protrusion <NUM>, <NUM> that extends from the second end of the sleeve <NUM> and abuts against an interior surface of the housing <NUM>.

At block <NUM>, the method <NUM> optionally includes mounting the orifice plug <NUM> in the cavity of the seal carrier <NUM>, and the orifice plug <NUM> includes the orifice <NUM> therein to allow fluid flow therethrough.

At block <NUM>, the method <NUM> optionally includes positioning the spool <NUM> within the sleeve <NUM>, and the spool <NUM> is slidably accommodated within the sleeve <NUM> and includes the spool shoulder <NUM>.

At block <NUM>, the method <NUM> optionally includes mounting the first spring <NUM> between the spool shoulder <NUM> and the shoulder <NUM> of the sleeve <NUM>.

At block <NUM>, the method <NUM> optionally includes mounting the second spring <NUM> between the spool shoulder <NUM> and the seal carrier <NUM>.

At block <NUM>, the method <NUM> optionally includes mounting the orifice plug <NUM> in the cavity <NUM> of the sleeve <NUM>, and the orifice plug <NUM> includes the orifice <NUM> therein to allow fluid flow therethrough.

At block <NUM>, the method <NUM> includes mounting the end cap <NUM> to the housing <NUM> such that the sleeve protrusions <NUM>-<NUM> abut against the end cap <NUM>.

Claim 1:
A flow control valve (<NUM>) comprising:
a housing (<NUM>);
a sleeve (<NUM>) disposed within the housing (<NUM>), wherein the sleeve (<NUM>) has a first end and a second end opposite the first end, wherein the sleeve (<NUM>) comprises a plurality of sleeve protrusions (<NUM>-<NUM>) at the first end and a plurality of fluid flow channels (<NUM>-<NUM>) are formed between adjacent sleeve protrusions (<NUM>-<NUM>);
an end cap (<NUM>);
characterized by
a seal carrier (<NUM>) disposed within the sleeve (<NUM>), wherein the seal carrier (<NUM>) comprises a carrier protrusion (<NUM>, <NUM>) that extends from the second end of the sleeve (<NUM>) and abuts against an interior surface of the housing (<NUM>); and
the end cap (<NUM>) mounted to the housing (<NUM>) such that the plurality of sleeve protrusions (<NUM>-<NUM>) abut against the end cap (<NUM>).