Flow control valve, assembly method, and hydraulic system

Abstract

To provide a flow control valve, a method of assembly and a hydraulic system.SOLUTION: An example valve includes: a housing; a sleeve disposed within the housing and having a first end and a second end opposite to the first end, the sleeve including a plurality of sleeve protrusions at the first end and the sleeve having a plurality of fluid flow channels formed between adjacent sleeve protrusions; a seal carrier disposed within the sleeve and having a carrier protrusion that extends from the second end of the sleeve and abuts against an interior surface of the housing; and an end cap mounted to the housing such that the plurality of sleeve protrusions abut against the end cap.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to flow control valves having a multi-function sleeve, and more particularly to flow control valves that control fluid flow to an actuator to move the actuator in a controlled manner. [Background technology]

[0002] A flow control valve directs the flow of a liquid medium, usually oil, through a hydraulic system and controls the fluid flow rate delivered to the actuators. One example of a valve has a movable element, such as a spool, inside a housing or sleeve, and based on the movement of the spool within the sleeve, cross holes defined on the sleeve are opened or closed to achieve a desired flow rate. Summary of the Invention [Means for solving the problem]

[0003] The present disclosure describes examples relating to flow control valves, assembly methods, and hydraulic systems.

[0004] In one aspect, the disclosure describes a flow control valve. The flow control valve comprises 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 comprises a plurality of sleeve projections at the first end, with a plurality of fluid flow paths formed between adjacent sleeve projections. The flow control valve further comprises a seal carrier disposed within the sleeve. The seal carrier extends from the second end of the sleeve and comprises a carrier projection that abuts an inner surface of the housing. The flow control valve also comprises an end cap attached to the housing such that the plurality of sleeve projections abut the end cap.

[0005] In another aspect, the disclosure describes a hydraulic system. The hydraulic system includes a cylinder having a chamber and a flow control valve fluidly coupled to the chamber of the cylinder 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 projections at the first end, with a plurality of fluid flow paths formed between adjacent sleeve projections. The flow control valve further includes a seal carrier disposed within the sleeve. The seal carrier includes a carrier projection extending from the second end of the sleeve and abutting an inner surface of the housing. The flow control valve also includes an end cap attached to the housing such that the plurality of sleeve projections abut the end cap.

[0006] In another aspect, the disclosure describes a method of assembling a flow control valve. The method includes disposing a sleeve within a housing. The sleeve has a first end and a second end opposite the first end, the sleeve comprising a plurality of sleeve projections at the first end, with a plurality of fluid flow paths formed between adjacent sleeve projections. The method also includes disposing a seal carrier within the sleeve. The seal carrier comprises a carrier projection extending from the second end of the sleeve and abutting an inner surface of the housing. The method further includes attaching an end cap to the housing such that the plurality of sleeve projections abut the end cap.

[0007] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, examples, and configurations described above, further aspects, examples, and configurations will become apparent by reference to the figures and the following detailed description.

[0008] The novel features believed characteristic of the illustrative examples are set forth in the appended claims. The illustrative examples, however, as well as their preferred modes of use, other objects and explanations, will best be understood with reference to the following detailed description of illustrative examples of the present disclosure when read in conjunction with the accompanying drawings. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 illustrates an aircraft having a tricycle landing gear configuration, according to an example implementation. [Diagram 2] FIG. 1 is a schematic diagram of a hydraulic system for controlling a main landing gear of an aircraft, according to an example implementation. [Diagram 3] 3 is a schematic diagram of the hydraulic system of FIG. 2 with arrows indicating fluid flow direction in another mode of operation, according to an example implementation. [Figure 4] FIG. 1 is a perspective view of a flow control valve according to an example implementation. [Diagram 5] 5 is a cross-sectional view of the flow control valve of FIG. 4 according to an example implementation. [Figure 6] FIG. 6 is a perspective cross-sectional view of the flow control valve of FIGS. 4 and 5 according to an example implementation. [Figure 7] FIG. 2 is a perspective view of a sleeve according to an example implementation. [Figure 8] 8 is a cross-sectional view of the sleeve of FIG. 7 according to an example implementation. [Figure 9] 1 is a flow diagram of a method for assembling a flow control valve, according to an example implementation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Among other examples, disclosed herein are a flow control valve having a multi-function 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 received within the sleeve. Based on movement of the spool within the sleeve, a cross hole defined by the interaction between the spool and the sleeve is opened or closed to achieve a desired flow rate.

[0011] The sleeve is configured to allow fluid to flow through a fluid flow passage formed therein. The sleeve further includes a slot or void to retain the orifice plug, rather than using a separate lock nut and orifice plate. In this manner, additional parts can be eliminated, and the form of the additional parts is included in the sleeve. Thus, the flow control valve can have a reduced number of parts, and therefore reduced weight and cost, compared to conventional valves.

[0012] Additionally, the orifice plug integrated with the sleeve can act as a safety feature, allowing a certain fluid flow rate (e.g., at least a minimum fluid flow) through the orifice plug when a component operates in an unintended manner that blocks the cross hole. Thus, the valve allows the actuator to operate in each application despite the unintended operation of some components of the valve. By minimizing the fluid flow through the orifice plug when a component operates in an unintended manner, the valve allows the actuator to move to a safe position in some applications. One application in which the valve can be used is a hydraulic system that controls the operation of the main landing gear of an aircraft. However, it should be understood that the flow control valve disclosed herein can be used in other types of actuators and applications.

[0013] 1 illustrates an aircraft 100 having a tricycle landing gear configuration, according to an example implementation. The tricycle landing gear configuration includes a type of aircraft landing gear in which a single nose wheel is located at the front of the aircraft 100 and two main wheels are located slightly aft of the center of gravity of the aircraft 100. For example, the aircraft 100 has a nose gear 102 with wheels at the front. The aircraft 100 also has two main landing gears, main landing gear 104 and main landing gear 106, with associated wheels slightly aft of the center of gravity of the aircraft 100.

[0014] The main landing gear 104 includes an actuator, such as actuator 216 (shown in FIG. 2 ), which has a piston axially movable within a cylinder to deploy the wheels during landing and retract the wheels into the landing gear wells after the aircraft 100 takes off. In an example, the actuator is operated in a controlled manner by controlling the magnitude of fluid flow provided to the actuator to move the piston at a particular desired speed, allowing the actuator to operate and deploy or retract the main landing gear 104 in a safe manner. The main landing gear 106 is similarly configured. An example hydraulic system described below is configured to control the actuator of a main landing gear, such as main landing gear 104 or main landing gear 106.

[0015] 2 illustrates a schematic diagram of a hydraulic system 200 for controlling a main landing gear of an aircraft, according to an example implementation. For example, the hydraulic system 200 controls the main landing gear 104 or the main landing gear 106 of the aircraft 100.

[0016] Hydraulic system 200 includes a cylinder (e.g., cylinder 222, described below) having a chamber (e.g., chamber 230, described below). Hydraulic system 200 also includes a flow control valve (e.g., flow control valve 214) fluidly coupled to the chamber of the cylinder to control fluid flow to and from the chamber.

[0017] One example configuration of the flow control valve 214 is described below with respect to Figures 4 through 8. In the example, the hydraulic system 200 includes other components as described below.

[0018] Hydraulic system 200 receives pressurized fluid 201 from a landing gear transfer valve that is fluidly coupled to a fluid source (e.g., a pump, an accumulator, or another valve from a different portion of the aircraft's hydraulic circuit). The pressurized fluid 201 is then provided to an inlet fluid line 202. Hydraulic system 200 provides a return fluid flow via return fluid line 204 to the landing gear transfer valve, which then provides the return fluid to a fluid reservoir or another portion of the aircraft's hydraulic circuit.

[0019] Hydraulic system 200 includes a landing gear selector valve 206 fluidly coupled to an inlet fluid line 202 and a return fluid line 204. In one example, landing gear selector valve 206 is configured as a directional control valve.

[0020] The landing gear selector valve 206 can be actuated by, for example, an electrical actuator (e.g., a solenoid actuator), a fluid actuator, or a mechanical actuator. For example, the landing gear selector valve 206 has a spool within a valve body that 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 206 (e.g., an actuation signal to one of two solenoids of a solenoid actuator). Based on the direction of movement of the spool, the landing gear selector valve 206 either supplies pressurized fluid to fluid line 208 while return flow is received via fluid line 210, or the landing gear selector valve 206 supplies pressurized fluid to fluid line 210 while return flow is received via fluid line 208.

[0021] Fluid line 208 may be referred to as a down pressure fluid line, whereas fluid line 210 may be referred to as an up pressure fluid line. "Down pressure" refers to the fluid line that receives pressurized fluid when the main landing gear is deployed (moving downward from a landing gear well within the aircraft in preparation for landing), whereas "up pressure" refers to the fluid line that receives pressurized fluid when the main landing gear is retracted (moving upward toward a landing gear well within the aircraft after takeoff). As illustrated in the key of FIG. 2, the fluid lines with circles therein represent fluid lines needed to retract the main landing gear, and the fluid lines with cross-hatching represent fluid lines needed to deploy the main landing gear.

[0022] Hydraulic system 200 includes a volume fuse 212. Volume fuse 212 is configured to allow a certain volume amount of fluid to pass through the volume fuse in a single operating cycle. If such volume amount of fluid is exceeded, volume fuse 212 stops the fluid flow. In this example, volume fuse 212 resets every operating cycle when less than a predetermined volume flows through the volume fuse while protecting hydraulic system 200 from a line burst in hydraulic system 200 as described below.

[0023] The hydraulic system 200 also includes a flow control valve 214, sometimes referred to as a regulator, that controls the flow of fluid supplied to and exhausted from the main landing gear actuators 216. The flow control valve 214 is fluidly coupled to a transfer cylinder 218 and a frangible fitting 220. As described below, the frangible fitting 220 in conjunction with the volume fuse 212 provides a safety function to the hydraulic system 200, and the transfer cylinder 218 is configured as a time delay element to allow the main landing gear locking mechanism to be released before the main landing gear is deployed or retracted.

[0024] The main landing gear actuator 216 includes a cylinder 222 and a piston 224 slidably accommodated within the cylinder 222. The term "slidably accommodated" is used herein to indicate that a first component (e.g., the piston 224) is positioned relative to a second component (e.g., the cylinder 222) such that the first component can move relative to the second component.

[0025] The piston 224 includes a piston head 226 and a piston rod 228 that extends from the piston head 226 along a central longitudinal axis of the cylinder 222. The piston head 226 divides the interior space of the cylinder 222 into a chamber 230 and a chamber 232. The chamber 230 is sometimes referred to as a cap chamber or a head chamber, while the chamber 232 is sometimes referred to as a rod chamber.

[0026] The piston rod 228 is configured to be coupled to the main landing gear. For example, an end of the piston rod 228 is configured to be coupled to a strut or other mechanism coupled to a wheel assembly of the main landing gear. The main landing gear actuator 216 is configured such that when the piston 224 extends (e.g., moves to the left in FIG. 2), the main landing gear and wheels are retracted or retracted into the landing gear well after takeoff. Meanwhile, when the piston 224 retracts (e.g., moves to the right in FIG. 2), the main landing gear and wheels are deployed from the landing gear well in preparation for landing.

[0027] As mentioned above, the main landing gear has a locking mechanism that is released before allowing the main landing gear to be retracted or deployed. The locking mechanism is coupled to and releasable by the down lock actuator 234 and the up lock actuator 236. For example, the down lock actuator 234 locks the main landing gear in position when the main landing gear is deployed. The down lock actuator 234 is then actuated to release the locking mechanism before the main landing gear is retracted. Meanwhile, the up lock actuator 236 locks the main landing gear in position when the main landing gear is retracted in the landing gear well. The up lock actuator 236 is then actuated to release the locking mechanism before the main landing gear is deployed.

[0028] The down lock actuator 234 and the up lock actuator 236 are generally configured similarly to the main landing gear actuator 216. The down lock actuator 234 includes a cylinder 238 and a piston 240 slidably housed within the cylinder 238. The piston 240 includes a piston head 242 and a piston rod 244 extending from the piston head 242 along the central longitudinal axis of the cylinder 238. The piston head 242 divides the interior space of the cylinder 238 into a chamber 246 and a chamber 248.

[0029] Similarly, uplock actuator 236 includes a cylinder 250 and a piston 252 slidably received within cylinder 250. Piston 252 includes a piston head 254 and a piston rod 256 that extends from piston head 254 along a central longitudinal axis of cylinder 250. Piston head 254 divides the interior space of cylinder 250 into chamber 257 and chamber 258.

[0030] Hydraulic system 200 is also illustrated to include other components. For example, hydraulic system 200 includes several restrictor check valves, including restrictor check valve 260, restrictor check valve 262, and restrictor check valve 264. The restrictor check valves are configured to allow free fluid flow (e.g., with minimal pressure drop) in one direction (in the direction of the arrow depicted on the restrictor check valve symbol) and restrict fluid flow in the reverse direction (where a restrictor is depicted on the restrictor check valve symbol).

[0031] Hydraulic system 200 may further include relief valves that release pressurized fluid if the pressure level in a particular chamber or fluid line exceeds a particular threshold pressure value. For example, hydraulic system 200 includes relief valve 266 that opens and provides a fluid path for fluid in chamber 246 of downlock actuator 234 if the pressure level of the fluid in that chamber exceeds a threshold value.

[0032] The hydraulic system 200 is operable in a first mode of operation associated with extending the piston 224 of the main landing gear actuator 216 (e.g., moving the piston 224 to the left in FIG. 2 ), corresponding to retracting the main landing gear back into the landing gear well after the aircraft has taken off. The hydraulic system 200 is operable in a second mode of operation associated with retracting the piston 224 of the main landing gear actuator 216 (e.g., moving the piston 224 to the right in FIG. 2 ), corresponding to deploying the main landing gear from the landing gear well in preparation for the aircraft to land.

[0033] Hydraulic system 200 is shown in FIG. 2 with arrows indicating fluid flow direction in a first mode of operation. In this first mode of operation, landing gear selector valve 206 provides fluid flow to fluid line 210. In one example, fluid line 210 is fluidly coupled to alternate braking system 268 via fluid line 270 as shown in FIG. 2. Alternate braking system 268 is configured to activate when a normal braking system of the aircraft fails and / or low hydraulic pressure is detected in the normal braking system. Thus, in the event that the normal braking system fails, pressurized fluid is provided to alternate braking system 268 via fluid line 270 to brake the wheels and stop them from spinning during retraction of the main landing gear, thereby preventing damage to components within the landing gear wells of the aircraft.

[0034] Pressurized fluid is supplied via fluid line 210 to a volume fuse 212, which allows fluid to flow through the fluid line as long as the fluid volume amount does not exceed a particular capacity of the volume fuse 212. The fluid is then supplied to a flow control valve 214, which operates to control the amount of fluid flow supplied to a main landing gear actuator 216 to move a piston 224 in a controlled manner, such as at a desired speed.

[0035] The fluid that passes through the flow control valve 214 then flows to the transfer cylinder 218. The transfer cylinder 218 is configured to delay the supply of fluid to the chamber 230 until the main landing gear locking mechanism is released. In particular, the transfer cylinder 218 is configured as a time delay element that allows the fluid flow to be supplied to the downlock actuator 234 to release the main landing gear locking mechanism before the main landing gear is retracted. For example, the transfer cylinder 218 includes a piston 272 that divides the interior space of the transfer cylinder 218 into two chambers.

[0036] Fluid is supplied from the flow control valve 214 to the transfer cylinder 218, moving a piston 272 (e.g., to the left in FIG. 2). While the piston 272 is moving and fluid is filling the transfer cylinder 218, fluid is not supplied to the main landing gear actuator 216. When the piston 272 reaches the end of its stroke in the transfer cylinder 218, fluid is directed to the restrictor check valve 262 and the main landing gear actuator 216.

[0037] While the piston 272 of the transfer cylinder 218 is moving, fluid is being supplied from the volume fuse 212 through the restrictor 273 to the chamber 246 of the downlock actuator 234. The fluid supplied to the chamber 246 causes the piston 240 to extend (e.g., move to the left in FIG. 2). When the piston 272 of the transfer cylinder 218 reaches the end of its piston stroke, the piston 240 has also extended sufficiently to release the locking mechanism and allow the main landing gear to retract.

[0038] When the locking mechanism is released, fluid is provided through restrictor check valve 262 to chamber 230 of main landing gear actuator 216 to extend piston 224 (e.g., move to the left in FIG. 2 ), thereby retracting the main landing gear towards the landing gear well after takeoff. The aircraft's braking system is configured to brake the wheels and prevent them from spinning before reaching the landing gear well to avoid damage to the landing gear well. If the wheels continue to spin, hydraulic system 200 is configured to stop the main landing gear from retracting further (i.e. stop piston 224 from extending) as a safety feature to avoid damage to the landing gear well.

[0039] In particular, the frangible fitting 220 has a lever 274. The frangible fitting is configured such that if the main landing gear wheels continue to spin as the wheels retract, the lever 274 breaks. When the lever 274 breaks, fluid from the flow control valve 214 flows through the frangible fitting 220 as the fluid follows the path of least resistance, and then to the environment external to the hydraulic system 200, e.g., to the low pressure volume. As a result, the fluid flow rate through the volume fuse 212 increases and may exceed the capacity of the volume fuse, and in response, the volume fuse 212 shuts off the fluid flow through the volume fuse.

[0040] In this manner, fluid is not provided to the flow control valve 214 and the piston 224 ceases to extend, preventing further retraction of the main landing gear. However, the piston 224 can retract to deploy the main landing gear and safely land the aircraft.

[0041] As mentioned above, the hydraulic system 200 is also operable in a second mode of operation associated with retracting the piston 224 of the main landing gear actuator 216 (e.g., moving the piston 224 to the right in FIG. 2 ), corresponding to deploying the main landing gear from the landing gear well in preparation for landing of the aircraft.

[0042] 3 illustrates a schematic diagram of hydraulic system 200 with arrows indicating fluid flow direction in a second mode of operation, according to an example implementation. In this second mode of operation, landing gear selector valve 206 provides fluid flow to fluid line 208. Pressurized fluid flowing in fluid line 208 flows through fluid line 300 through restrictor check valve 260 and then to transfer cylinder 218. As shown in FIG. 3, fluid line 300 is also connected to chamber 258 of uplock actuator 236 via restrictor 302.

[0043] The transfer cylinder 218 operates similarly to the operation of the transfer cylinder in the first mode of operation, but the piston 272 moves in the opposite direction (e.g., to the right in FIG. 3). Thus, the transfer cylinder 218 operates as a time delay element that allows the fluid flow to be supplied to the uplock actuator 236 to release the locking mechanism of the main landing gear before the main landing gear is deployed. As the piston 272 moves and the fluid supplied through the restrictor check valve 260 fills the transfer cylinder 218, no fluid is supplied to the chamber 232 of the main landing gear actuator 216. When the piston 272 reaches the end of its stroke in the transfer cylinder 218, fluid is supplied to the chamber 232 of the main landing gear actuator 216.

[0044] While the piston 272 of the transfer cylinder 218 is moving, fluid is being supplied from a fluid line 300 through a restrictor 302 to the chamber 258 of the uplock actuator 236. The fluid supplied to the chamber 258 causes the piston 252 to retract (e.g., move to the left in FIG. 3). When the piston 272 of the transfer cylinder 218 reaches the end of its piston stroke, the piston 252 has also extended sufficiently to release the locking mechanism and allow the main landing gear to deploy.

[0045] Fluid discharged from chamber 257 as piston 252 retracts flows through fluid line 304 to shimmy damper 306 and return fluid line 204. Shimmy is a vibration within the landing gear that creates undesirable vibrations and loads on the landing gear structure. Shimmy damper 306 damps vibrations that may occur as piston 252 moves, ensuring smooth operation of hydraulic system 200.

[0046] When the locking mechanism is released, fluid is supplied to chamber 232 of main landing gear actuator 216 causing piston 224 to retract (e.g., move to the right in FIG. 3), thereby deploying the main landing gear from the landing gear well in preparation for landing the aircraft. Fluid discharged from chamber 230 as piston 224 retracts flows through restrictor check valve 262 and then to flow control valve 214. Flow control valve 214 controls the amount of fluid flow discharged from main landing gear actuator 216 to move piston 224 in a controlled manner, such as at a desired speed.

[0047] In particular, the flow control valve 214 creates back pressure in the chamber 230 as the flow control valve 214 controls the fluid flow therethrough, thereby causing the piston 224 to retract in a controlled manner. Fluid exiting the flow control valve 214 flows through the volume fuse 212 and the landing gear selector valve 206 to the return fluid line 204. Thus, the flow control valve 214 is configured to move the piston 224 of the main landing gear actuator 216 in a controlled manner.

[0048] Figure 4 illustrates a perspective view of a flow control valve 214 according to an example implementation, Figure 5 illustrates a cross-sectional view of a flow control valve 214 according to an example implementation, and Figure 6 illustrates a perspective cross-sectional view of a flow control valve 214 according to an example implementation. Figures 4 through 6 will be described together.

[0049] The flow control valve 214 includes a housing 400 and a sleeve 412 disposed within the housing 400, the sleeve 412 having a proximal or first end and a distal or second end opposite the first end. The sleeve 412 includes a plurality of sleeve protrusions 700-706 at the first end, with a plurality of fluid flow paths 708-714 (e.g., fluid flow paths 708, 710, 712, 714 for a total of four fluid flow paths) formed between adjacent ones of the sleeve protrusions 700-706. The flow control valve 214 also includes a seal carrier 424 disposed within the sleeve 412, the seal carrier 424 including carrier protrusions 426, 428 extending from the second end of the sleeve 412 and abutting an inner surface of the housing 400. The flow control valve 214 also includes an end cap 404 attached to the housing 400 such that the multiple sleeve projections 700 - 706 abut the end cap 404 .

[0050] The housing 400 is generally cylindrical and has a longitudinal cylindrical cavity defined therein. The components of the flow control valve 214 are disposed within the longitudinal cylindrical cavity of the housing 400. The housing 400 has a first port 402 (e.g., an opening) at a distal end 403 of the housing 400. The first port 402 permits fluid flow into and out of the flow control valve 214 through the first port. For example, the first port 402 can be fluidly coupled to the transfer cylinder 218, the frangible fitting 220, and the restrictor check valve 262.

[0051] An end cap 404 is coupled to the housing 400 at a proximal end 401 of the housing. For example, the end cap 404 is threadedly coupled to the housing 400 at a threaded region 406 via male threads in the end cap 404 and female threads in the housing 400. The end cap 404 can keep the flow control valve 214 intact and free of chatter and vibration that can cause components of the flow control valve 214 to shift internally.

[0052] The end cap 404 has a second port 408 (e.g., an opening) at the proximal end 401 opposite the first port 402 of the flow control valve 214. The second port 408 allows fluid flow into and out of the flow control valve 214 through the second port 408. For example, the second port 408 may be fluidly coupled to the volume fuse 212. The flow control valve 214 is bidirectional, allowing fluid flow from the first port 402 to the second port 408 through the flow control valve, or from the second port 408 to the first port 402.

[0053] The flow control valve 214 includes a seal 410 (e.g., an O-ring) disposed in an outer annular groove formed in the end cap 404 and forming a fluid seal between the end cap 404 and the housing 400 to prevent leakage of the flow control valve 214 to the external environment. In one example, the seal 410 is disposed between backup rings. The backup rings can be used, for example, to reduce the likelihood of the seal 410 being extruded when pressurization and depressurization / pressure cycling occurs within the flow control valve 214.

[0054] Sleeve 412 is fixedly disposed within housing 400. Sleeve 412 is generally cylindrical and includes a longitudinal cylindrical cavity therein.

[0055] Figure 7 illustrates a perspective view of sleeve 412 according to an example implementation, and Figure 8 illustrates a cross-sectional view of sleeve 412 according to an example implementation. Figures 7 and 8 will be described together.

[0056] The sleeve 412 has a plurality of sleeve protrusions, such as sleeve protrusion 700, sleeve protrusion 702, sleeve protrusion 704, and sleeve protrusion 706, disposed at the proximal end 401 of the sleeve 412. In one example, the sleeve protrusions 700-706 are arranged in an array, such as a circular array, as shown in Figure 7. However, other array configurations (e.g., a rectangular array, a square array, etc.) may also be used.

[0057] 7, the sleeve protrusions 700-706 are arcuate in shape. However, in other examples, the sleeve protrusions 700-706 may have other shapes, such as linear or rectangular. Regardless of the configuration of the sleeve protrusions 700-706, the sleeve protrusions 700-706 form fluid flow paths between them, such as fluid flow path 708, fluid flow path 710, fluid flow path 712, and fluid flow path 714.

[0058] The sleeve 412 includes a bore 716 (e.g., a stepped bore) at the proximal end 401 of the sleeve 412 that defines several steps or shoulders by the inner surface of the sleeve 412 to accommodate other components of the flow control valve 214. In other words, the inner diameter of the sleeve 412 varies to define cavities having different sizes within the sleeve. For example, a cavities 718 that are part of the bore 716 are configured to receive an orifice plug, as described below. A shoulder 720 is defined by the transition of the inner diameter of the sleeve 412, and the shoulder 720 is configured to support a spring washer, as described below. The shoulder 720 can prevent the forward flow of fluid from one chamber to the other, as described below, and direct the fluid to flow to a cross hole.

[0059] The sleeve 412 includes a first set of cross holes, such as cross holes 722 and 724, arranged in an array about the wall of the body of the sleeve 412. For example, the first set of cross holes are arranged in a circular array about the sleeve 412. The sleeve 412 further includes a second set of cross holes, such as cross holes 726 and 728, also arranged in an array (e.g., in a circular array) about the wall of the sleeve 412. The second set of cross holes are axially spaced from the first set of cross holes along the length of the sleeve 412. The term "cross-hole" is used herein to denote a hole that intersects the path of or is formed transversely to another hole, void, or channel.

[0060] Sleeve 412 also includes first and second flange portions 730, 732 that form a groove 734, e.g., an outer annular groove, between first and second flange portions 730, 732. Outer surfaces of first and second flange portions 730, 732 interface with an inner surface of housing 400 (as shown in FIGS. 5 and 6), and groove 734 is configured to receive a seal and a backup ring therein, as described below.

[0061] 8, the inner diameter of the sleeve 412 increases near the distal end 403 of the sleeve to form a shoulder 736 and a gap 738. The gap 738 is configured to receive the seal carrier 424 against the shoulder 736.

[0062] 5 and 6, along with Figures 7 and 8, the flow control valve 214 includes an orifice plug 414 disposed within a cavity 718 of the sleeve 412. The orifice plug 414 is configured with an orifice 416 formed therein, e.g., drilled into the orifice plug, to allow a particular fluid flow rate to pass through the orifice plug.

[0063] 5 and 6, sleeve 412 is disposed within housing 400 such that a first chamber 418 is formed between an outer surface of sleeve 412 and an inner surface of housing 400. Similarly, a second chamber 420 is formed between an outer surface of sleeve 412 and an inner surface of housing 400. First chamber 418 is separated from second chamber 420 by flange portions 730 and 732 of sleeve 412.

[0064] Additionally, the flow control valve 214 includes a seal 422 disposed in a groove 734 in the sleeve 412 to seal the first chamber 418 from the second chamber 420. A backup ring may be disposed around the seal 422 to reduce the likelihood of the seal 422 being extruded within the groove 734 in the sleeve 412 when pressurization / depressurization cycling occurs within the flow control valve 214.

[0065] The seal carrier 424 is disposed within the cavity 738 of the sleeve 412. Similar to the sleeve 412, the seal carrier 424 has a plurality of carrier protrusions, such as carrier protrusion 426 and carrier protrusion 428, that form fluid flow paths, such as fluid flow path 430, between the carrier protrusions. By way of example, the carrier protrusions 426, 428 are arc-shaped and arranged in a circular array. However, other configurations are possible. Additionally, the seal carrier 424 includes a seal 432 (e.g., an O-ring) disposed in an outer annular groove formed in the seal carrier 424 that forms a fluid seal between the seal carrier 424 and the sleeve 412 to prevent fluid leakage between the seal carrier and the sleeve. A backup ring may also be used in conjunction with the seal 432.

[0066] The seal carrier 424 is further configured to receive an orifice plug 434 similar to the orifice plug 414. The orifice plug 434 has an orifice 436 formed therein to allow a particular fluid flow rate through the orifice plug.

[0067] 5 and 6, the sleeve projections 700-706 abut the distal end 403 of the end cap 404. Thus, the sleeve 412 is axially secured proximally through the end cap 404.

[0068] Additionally, seal carrier 424 is proximally secured via shoulder 736 (see FIG. 8 ) of sleeve 412. Additionally, carrier protrusions (e.g., carrier protrusions 426, 428) extend from distal end 403 of sleeve 412 and abut an inner surface of housing 400, such that seal carrier 424 is axially secured distally by housing 400. In this configuration, sleeve 412 and seal carrier 424 are longitudinally secured within housing 400 via their own features (sleeve and carrier protrusions, and shoulders) and no additional components (e.g., spacers) are used.

[0069] The flow control valve 214 further includes an axially movable spool 438 that is slidably received within the longitudinal cylindrical cavity of the sleeve 412. The spool 438 is hollow and defines a spool shoulder 440, which is a ring-like projection or annulus having a hole 442 therethrough.

[0070] 5 and 6, the spool 438 is configured to receive therein a first spring 444 and a second spring 446. In particular, the first spring 444 has a proximal end 401 that rests against a spring washer 448, which in turn rests against a shoulder 720 (see FIG. 8) of the sleeve 412, while the distal end 403 of the first spring 444 rests against one side of a spool shoulder 440 of the spool 438. Meanwhile, the proximal end 401 of the second spring 446 rests against the other side of the spool shoulder 440, while the distal end 403 of the second spring 446 rests against a shoulder formed by the seal carrier 424.

[0071] In this configuration, the first spring 444 exerts a first spring force distally on the spool 438, and the second spring 446 exerts a second spring force proximally on the spool 438. The spring forces maintain the spool 438 in a centered position. However, if the fluid pressure level on one side of the spool shoulder 440 differs from the fluid pressure level on the other side of the spool shoulder 440, the spool 438 will move axially against the spring force of one of the springs, as described below.

[0072] 5 and 6, the proximal end 401 of the spool 438 overlaps with the first set of cross holes (e.g., cross holes 722 and 724), while the distal end 403 of the spool 438 overlaps with the second set of cross holes (e.g., cross holes 726 and 728). When the spool 438 is moved distally, the second set of cross holes becomes more restricted (more of the cross holes are blocked, decreasing the size of the openings of the cross holes that allow fluid flow) while the first set of cross holes becomes more exposed (more of the cross holes are uncovered, increasing the size of the openings of the cross holes that allow fluid flow).

[0073] On the other hand, when the spool 438 moves proximally, the first set of cross holes becomes more restricted (more blocked, decreasing the size of the cross hole openings that allow fluid flow) while the second set of cross holes becomes more exposed (more uncovered, increasing the size of the cross hole openings that allow fluid flow). In this configuration, fluid flow rate and pressure levels are adjusted during operation as the spool 438 moves axially within the sleeve 412.

[0074] For example, if the direction of fluid flow is from second port 408 to first port 402, fluid is received at second port 408 and then flows through end cap 404 to proximal end 401 of sleeve 412. Fluid then flows radially outward through the fluid flow paths of sleeve 412 (i.e., fluid flow paths 708-714 shown in FIGS. 7 and 8) to first chamber 418. Fluid then flows radially inward through a first set of cross holes (e.g., cross holes 722 and 724) to a spool chamber having first spring 444 within spool 438.

[0075] The fluid then flows through holes 442 in the spool shoulder 440 into a spool chamber containing a second spring 446. As the fluid flows through the holes 442, a pressure drop occurs (a decrease in the pressure level of the fluid due to flow through the fluid restriction caused by the holes 442). This pressure drop increases the fluid force acting distally on the spool 438 relative to the fluid forces acting proximal to the spool 438, causing the spool 438 to move distally. As the spool 438 moves distally, the second spring 446 is compressed and the first spring 444 is relaxed.

[0076] Additionally, as the spool 438 moves distally, the second set of cross holes becomes restricted while the first set of cross holes becomes more exposed. Fluid within the spring chamber of the second spring 446 flows radially outward through the second set of cross holes (now more restricted) to the second chamber 420. From the second chamber 420, the fluid flows radially inward through the fluid flow paths (e.g., fluid flow path 430) of the seal carrier 424 and then out of the flow control valve 214 through the first port 402.

[0077] While a portion of the fluid received at the second port 408 flows through the paths described above (i.e., the fluid flow path, the annular chamber between the sleeve 412 and the housing 400, and each set of cross holes), another portion of the fluid flows through the orifice plug 414 and the orifice 416, then through the orifice plug 434 and the orifice 436 to the first port 402 and out the flow control valve 214. This configuration provides a safety feature that allows a specific flow rate to be provided through the flow control valve 214 in the event of an unexpected problem. The safety feature may be useful, for example, to allow a specific amount of fluid to flow through the flow control valve 214 so that the main landing gear actuators 216 can still operate if a problem occurs.

[0078] In particular, if the first spring 444 or the second spring 446 does not operate as intended, the spool 438 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., cross holes 722 and 724) or the second set of cross holes (e.g., cross holes 726 and 728). As a result, fluid flow through the cross holes to and from the first chamber 418 or the second chamber 420 is blocked. However, fluid still flows through the orifice 416 of the orifice plug 414 and the orifice 436 of the orifice plug 434. In this example, at least a certain amount of fluid flow is provided through the flow control valve 214 to operate the main landing gear actuator 216.

[0079] As an illustrative example, flow control valve 214 has a fluid flow capacity of approximately 8 gallons per minute (GPM). A portion of that amount (e.g., half or 4 GPM) flows through fluid flow paths 708-714, first chamber 418, first set of cross holes, second set of cross holes, second chamber 420, and fluid flow paths (e.g., fluid flow path 430) of seal carrier 424. The remaining portion (e.g., the remaining half or 4 GPM) flows through orifice 416 and orifice 436. In this example, at least 4 GPM is provided from second port 408 to first port 402 in the event of an unintended operation within flow control valve 214.

[0080] The flow control valve 214 is a bidirectional valve as described above, which also allows for fluid flow in the reverse direction, i.e., from the first port 402 to the second port 408. In particular, fluid is received at the first port 402 and then flows radially outward from the fluid flow passages (e.g., fluid flow passages 430) of the seal carrier 424 to the second chamber 420. The fluid then flows radially inward through the second set of cross holes (e.g., cross holes 726 and 728) to a spool chamber having a second spring 446 within the spool 438.

[0081] The fluid then flows through holes 442 in the spool shoulder 440 into a spool chamber containing a first spring 444. As the fluid flows through holes 442, a pressure drop occurs. This pressure drop increases the fluid force acting distally on the spool 438 relative to the fluid force acting proximally on the spool 438, causing the spool 438 to move proximally. As the spool 438 moves proximally, the first spring 444 is compressed and the second spring 446 is relaxed.

[0082] Additionally, as the spool 438 moves proximally, the first set of cross holes becomes restricted while the second set of cross holes becomes more exposed. Fluid within the spring chamber of the first spring 444 flows radially outward through the first set of cross holes (now more restricted) and into the first chamber 418. From the first chamber 418, the fluid flows radially inward through the fluid passages 708-714 of the sleeve 412 and then out the flow control valve 214 through the second port 408.

[0083] While a portion of the fluid received at first port 402 flows through the pathways described above (i.e., the fluid flow passages, the annular chamber, each set of cross holes), another portion of the fluid flows through orifice plug 434 and orifice 436, then through orifice plug 414 and orifice 416 to second port 408 and out flow control valve 214. This configuration provides a safety feature that ensures a specific flow rate is provided through flow control valve 214 in the event of unintended operation, as described above.

[0084] In an example, the configuration of flow control valve 214 can provide several advantages over conventional valves. For example, sleeve 412 is configured as a multi-function sleeve with features integrated into the sleeve instead of having additional components. For example, rather than using a second seal carrier (in addition to seal carrier 424) at proximal end 401 of sleeve 412, features of such an additional seal carrier are integrated into sleeve 412.

[0085] In particular, fluid flow passages 708-714 are integrated into sleeve 412, orifice plug 414 is fixed within sleeve 412, and no seals or backup rings are used. In this example, the elimination of the additional seal carrier and its associated components (seals, backup rings, etc.) may reduce the cost and weight of flow control valve 214, as well as increase reliability by reducing the number of operating components.

[0086] Additionally, sleeve projections 700-706 abut end cap 404, and therefore no additional spacers are used to axially secure sleeve 412 within housing 400. Thus, the multi-functionality of sleeve 412 eliminates another component.

[0087] FIG. 9 is a flow diagram of a method 900 for assembling a flow control valve 214 according to an example implementation. The method 900 includes one or more operations or actions, as illustrated by one or more of blocks 902-916. Although the blocks are shown, for example, in sequential order, the blocks may be performed in parallel and / or in a different order than described herein. Also, for example, various blocks may be combined into fewer blocks, divided into additional blocks, and / or removed based on the desired implementation. In this and other processes and methods disclosed herein, it should be understood that the flow diagram illustrates the functions and operations of one possible implementation of the examples of the invention. As will be appreciated by those skilled in the art, alternative implementations are included within the scope of the examples of the present disclosure in which functions are performed in a different order than that shown or discussed, including substantially simultaneously or in reverse order, depending on the functionality involved.

[0088] At block 902, the method 900 includes disposing a sleeve 412 within the housing 400, the sleeve 412 having a first end (e.g., proximal end 401) and a second end (e.g., distal end 403) opposite the first end. The sleeve 412 includes sleeve protrusions 700-706 at the first end, with a plurality of fluid flow paths 708-714 formed between adjacent sleeve protrusions, e.g., between the sleeve protrusions 700-706.

[0089] At block 904 , the method 900 includes disposing a seal carrier 424 within the sleeve 412 , the seal carrier 424 including carrier protrusions 426 , 428 extending from a second end of the sleeve 412 and abutting an inner surface of the housing 400 .

[0090] At block 906, the method 900 optionally includes a step of installing an orifice plug 434 in the cavity in the seal carrier 424, the orifice plug 434 including an orifice 436 therein to allow fluid to flow through the orifice plug 434.

[0091] At block 908 , the method 900 optionally includes disposing a spool 438 within the sleeve 412 , the spool 438 being slidably received within the sleeve 412 and including a spool shoulder 440 .

[0092] At block 910 , the method 900 optionally includes attaching a first spring 444 between the spool shoulder 440 and the shoulder 720 of the sleeve 412 .

[0093] At block 912 , the method 900 optionally includes attaching a second spring 446 between the spool shoulder 440 and the seal carrier 424 .

[0094] At block 914, the method 900 optionally includes a step of installing an orifice plug 414 in the cavity 718 of the sleeve 412, the orifice plug 414 including an orifice 416 therein to allow fluid to flow through the orifice plug 414.

[0095] At block 916 , the method 900 includes attaching the end cap 404 to the housing 400 such that the sleeve projections 700 - 706 abut the end cap 404 .

[0096] The above detailed description, with reference to the accompanying figures, describes various aspects and operations of the disclosed system. The exemplary implementations described herein are not meant to be limiting. Certain aspects of the disclosed system can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

[0097] Additionally, unless the context indicates otherwise, the features shown in each of the figures may be used in combination with one another. Thus, the figures should generally be considered as aspects of components of one or more overall implementations, with the understanding that not all illustrated features are required for each implementation.

[0098] Moreover, recitations of elements, blocks, or steps in the specification or claims are for clarity purposes and, therefore, such recitations should not be construed as requiring or implying that those elements, blocks, or steps follow a particular arrangement or be performed in a particular order.

[0099] Further, in examples, the device or system is used or configured to perform the functions presented in the figures above. In some cases, each component of the device and / or system is configured to perform the above functions such that the component is actually configured and structured (using hardware and / or software) to enable such performance. In other examples, each component of the device and / or system is adapted to perform a function, capable of performing a function, or arranged to be suitable to perform a function, such as when operated in a particular manner.

[0100] Furthermore, the present disclosure includes implementations according to the following examples. Example 1. A flow control valve comprising: a housing; a sleeve disposed within the housing, the sleeve having a first end and a second end opposite the first end, the sleeve comprising a plurality of sleeve protrusions at the first end, wherein a plurality of fluid flow paths are formed between adjacent sleeve protrusions; a seal carrier disposed within the sleeve, the seal carrier comprising carrier protrusions extending from the second end of the sleeve and abutting an inner surface of the housing; and an end cap attached to the housing such that the plurality of sleeve protrusions abut the end cap.

[0101] Example 2. The flow control valve of example 1, wherein the housing comprises a first port and the end cap comprises a second port opposite the first port.

[0102] Example 3. The flow control valve of example 1 or 2, further comprising a spool slidably received within the sleeve.

[0103] Example 4. The flow control valve of example 1 or 2, wherein the sleeve further comprises a first set of cross holes disposed about the sleeve and a second set of cross holes disposed about the sleeve, the second set of cross holes being axially spaced from the first set of cross holes along the length of the sleeve.

[0104] Example 5. The flow control valve of Example 4, further comprising a spool slidably received within the sleeve, a proximal end of the spool partially overlapping the first set of cross holes and a distal end of the spool partially overlapping the second set of cross holes.

[0105] Example 6. The flow control valve of Example 4 or 5, further comprising a first chamber formed between an outer surface of the sleeve and an inner surface of the housing, the first chamber fluidly coupling a plurality of fluid flow paths of the sleeve to a first set of cross holes of the sleeve, and a second chamber formed between the outer surface of the sleeve and an inner surface of the housing, the second chamber fluidly coupling a second set of cross holes of the sleeve to a distal end of the seal carrier.

[0106] Example 7. The flow control valve of any one of Examples 1 to 6, wherein the sleeve further comprises a first flange portion and a second flange portion forming a groove between the first flange portion and the second flange portion, and the flow control valve further comprises a seal disposed within the groove of the sleeve.

[0107] Example 8. The flow control valve of any one of Examples 1 to 7, further comprising an orifice plug disposed within the cavity of the sleeve and having an orifice formed therein.

[0108] Example 9. The flow control valve of any one of Examples 1 to 8, further comprising an orifice plug disposed within the seal carrier and having an orifice therein.

[0109] Example 10. A flow control valve as described in any one of Examples 1 to 9, wherein a plurality of sleeve protrusions are arranged in an array at the first end of the sleeve such that a plurality of fluid flow paths are formed between the plurality of sleeve protrusions.

[0110] Example 11. The flow control valve of example 10, wherein the multiple sleeve protrusions are arc-shaped.

[0111] Example 12. The flow control valve of example 10 or 11, wherein the plurality of sleeve protrusions are arranged in a circular array at the first end of the sleeve.

[0112] Example 13. A hydraulic system comprising: a cylinder having a chamber; and a flow control valve fluidly coupled to the chamber of the cylinder for controlling fluid flow to and from the chamber, the flow control valve comprising: a housing; a sleeve disposed within the housing, the sleeve having a first end and a second end opposite the first end, the sleeve comprising a plurality of sleeve projections at the first end, a plurality of fluid flow paths being formed between adjacent sleeve projections; a seal carrier disposed within the sleeve, the seal carrier comprising a carrier projection extending from the second end of the sleeve and abutting an inner surface of the housing; and an end cap, the end cap attached to the housing such that the plurality of sleeve projections abut the end cap.

[0113] Example 14. The hydraulic system of example 13, wherein the housing includes a first port fluidly coupled to the chamber of the cylinder, and the end cap includes a second port opposite the first port fluidly coupled to a fluid line to receive fluid from the first port or supply fluid to the first port.

[0114] Example 15. The hydraulic system of example 14, further comprising a volume fuse fluidly coupled to the second port, the volume fuse configured to interrupt fluid flow to the flow control valve when a fluid flow rate through the volume fuse exceeds a capacity of the volume fuse.

[0115] Example 16. The hydraulic system of example 14 or 15, further comprising a transfer cylinder fluidly coupled to the first port of the housing, the transfer cylinder configured to receive fluid from the flow control valve and delay supplying fluid to the chamber of the cylinder.

[0116] Example 17. The hydraulic system of any one of Examples 13 to 16, further comprising a restrictor check valve disposed between the flow control valve and the chamber of the cylinder, the restrictor check valve configured to allow free fluid flow into the chamber and restrict fluid flow out of the chamber.

[0117] Example 18. The hydraulic system of any one of Examples 13 to 17, wherein the cylinder is included in an actuator of an aircraft landing gear, and the flow control valve controls fluid flow to and from the chamber to retract and deploy the landing gear.

[0118] Example 19. A method for assembling a flow control valve, the method including the steps of: disposing a sleeve within a housing, the sleeve having a first end and a second end opposite the first end, the sleeve comprising a plurality of sleeve protrusions at the first end, a plurality of fluid flow paths being formed between adjacent sleeve protrusions; disposing a seal carrier within the sleeve, the seal carrier comprising carrier protrusions extending from the second end of the sleeve and abutting an inner surface of the housing; and attaching an end cap to the housing such that the plurality of sleeve protrusions abut the end cap.

[0119] Example 20. The method of example 19, wherein the sleeve comprises a void within the sleeve, and the method further comprises the step of mounting an orifice plug within the void of the sleeve, the orifice plug comprising an orifice within the orifice plug to allow fluid to flow through the orifice plug.

[0120] The term "substantially" means that the recited characteristic, parameter, or value need not be achieved exactly, but rather that deviations or variations including, for example, tolerances, measurement errors, measurement accuracy limits, and other factors known to those of ordinary skill in the art, will occur in an amount that does not eliminate the effect that the characteristic was intended to provide.

[0121] The arrangements described herein are for purposes of example only. Thus, those skilled in the art will appreciate that other arrangements and other elements (e.g., machines, interfaces, operations, sequences, and groupings of operations, etc.) can be substituted, and that some elements may be omitted entirely, depending on the desired results. Furthermore, many of the described elements are functional entities that may be implemented as separate or distributed components, or with other components, in any suitable combination and location.

[0122] While various aspects and implementations are disclosed herein, other aspects and implementations will be apparent to those skilled in the art. The various aspects and implementations disclosed herein are for illustrative purposes only and are not intended to be limiting, with the true scope being set forth in the following claims, along with the full scope of equivalents to which such claims are entitled. Additionally, the terms used herein are for the purpose of describing particular implementations only and are not intended to be limiting. [Explanation of symbols]

[0123] 100 aircraft 102 Front legs 104 Main landing gear 106 Main landing gear 200 Hydraulic System 201 Pressurized Fluid 202 Inlet fluid line 204 Return fluid line 206 Landing gear selector valve 208 Fluid Line 210 Fluid Line 212 Volume Fuse 214 Flow Control Valve 216 Actuator 218 Transfer Cylinder 220 Fragile Fixtures 222 Cylinder 224 Piston 226 Piston Head 228 Piston rod 230 Chamber 232 Chamber 234 Down Lock Actuator 236 Uplock Actuator 238 Cylinder 240 Piston 242 Piston Head 244 Piston rod 246 Chamber 248 Chamber 250 cylinder 252 Piston 254 Piston Head 256 Piston rod 257 Chamber 258 Chamber 260 Restrictor check valve 262 Restrictor check valve 264 Restrictor check valve 266 Relief valve 268 Alternative Brake Systems 270 Fluid Line 272 Piston 273 Restrictor 274 Lever 300 Fluid Lines 302 Restrictor 304 Fluid Line 306 Shimmy Damper 400 Housing 401 Proximal end 402 First Port 403 Distal end 404 End Cap 406 Thread Area 408 Secondary Port 410 Seal 412 Sleeve 414 Orifice plug 416 Orifice 418 First Chamber 420 Second Chamber 422 Seal 424 Seal Carrier 426 Carrier protrusion 428 Carrier protrusion 430 Fluid Flow Path 432 Seal 434 Orifice Plug 436 Orifice 438 Spool 440 Spool shoulder 442 holes 444 First Spring 446 Second Spring 448 Spring washer 700 Sleeve protrusion 702 Sleeve protrusion 704 Sleeve protrusion 706 Sleeve protrusion 708 Fluid Flow Path 710 Fluid flow path 712 Fluid Flow Path 714 Fluid Flow Path 716 hole 718 Cavity 720 Shoulder 722 Cross Hall 724 Cross Hall 726 Cross Hall 728 Cross Hall 730 First flange portion 732 Second flange part 734 Groove 736 Shoulder 738 Cavity 900 ways

Claims

1. A housing (400); a sleeve (412) disposed within said housing (400), said sleeve (412) having a first end and a second end opposite said first end, said sleeve (412) including a plurality of sleeve projections (700-706) at said first end, said plurality of fluid flow paths (708-714) being formed between adjacent sleeve projections (700-706); a seal carrier (424) disposed within the sleeve (412), the seal carrier (424) including carrier projections (426, 428) extending from the second end of the sleeve (412) and abutting an inner surface of the housing (400); an end cap (404) attached to the housing (400) such that the plurality of sleeve projections (700-706) abut against the end cap (404); A flow control valve (214).

2. The flow control valve (214) of claim 1, wherein the housing (400) comprises a first port (402) and the end cap (404) comprises a second port (408) opposite the first port (402).

3. The sleeve (412) a first set of cross holes (722, 724) disposed about said sleeve (412); a second set of cross holes (726, 728) disposed about said sleeve (412), said second set of cross holes (726, 728) being axially spaced from said first set of cross holes (722, 724) along a length of said sleeve (412); The flow control valve (214) of claim 1 or 2, further comprising:

4. a spool (438) slidably received within said sleeve (412), a proximal end of said spool (438) overlapping a first set of cross holes (722, 724) and a distal end of said spool (438) overlapping a second set of cross holes (726, 728); The flow control valve (214) of any one of claims 1 to 3, further comprising:

5. a first chamber (418) formed between an outer surface of the sleeve (412) and the inner surface of the housing (400), the first chamber (418) fluidly coupling the plurality of fluid flow paths (708-714) of the sleeve (412) to the first set of cross holes (722, 724) of the sleeve (412); a second chamber (420) formed between the outer surface of the sleeve (412) and the inner surface of the housing (400), the second chamber (420) fluidly coupling the second set of cross holes (726, 728) of the sleeve (412) to a distal end of the seal carrier (424); The flow control valve (214) of claim 3 or 4, further comprising:

6. 6. The flow control valve (214) of any one of claims 1 to 5, wherein the sleeve (412) further comprises a first flange portion (730) and a second flange portion (732) forming a groove (734) between the first flange portion (730) and the second flange portion (732), and the flow control valve (214) further comprises a seal (422) disposed in the groove of the sleeve (412).

7. 7. The flow control valve (214) of any one of claims 1 to 6, wherein the plurality of sleeve protrusions (700-706) are arranged in an array at the first end of the sleeve (412) such that the plurality of fluid flow paths (708-714) are formed between the plurality of sleeve protrusions (700-706).

8. a cylinder (222) having a chamber (230); a flow control valve (214) fluidly coupled to the chamber (230) of the cylinder (222) and configured to control fluid flow to and from the chamber (230), the flow control valve (214) comprising: A housing (400); a sleeve (412) disposed within said housing (400), said sleeve (412) having a first end and a second end opposite said first end, said sleeve (412) including a plurality of sleeve projections (700-706) at said first end, said plurality of fluid flow paths (708-714) being formed between adjacent sleeve projections; a seal carrier (424) disposed within the sleeve (412), the seal carrier (424) including carrier projections (426, 428) extending from the second end of the sleeve (412) and abutting an inner surface of the housing (400); an end cap (404) attached to the housing (400) such that the plurality of sleeve projections (700-706) abut against the end cap (404); A flow control valve (214) comprising: A hydraulic system (200).

9. A method (900) for assembling a flow control valve (214), the method (900) comprising: a step (902) of disposing a sleeve (412) within a housing (400), the sleeve (412) having a first end and a second end opposite the first end, the sleeve (412) comprising a plurality of sleeve projections (700-706) at the first end, a plurality of fluid flow paths (708-714) being formed between adjacent sleeve projections (700-706); placing (904) a seal carrier (424) within the sleeve (412), the seal carrier (424) including carrier projections (426, 428) extending from the second end of the sleeve (412) and abutting an inner surface of the housing (400); attaching (916) an end cap (404) to the housing (400) such that the plurality of sleeve projections (700-706) abut the end cap (404); The method (900).

10. 10. The method (900) of claim 9, wherein the sleeve (412) comprises a void (718) within the sleeve (412), the method (900) further comprising the step of installing (1000) an orifice plug (414) within the void (718) of the sleeve (412), the orifice plug (414) comprising an orifice (416) within the orifice plug (414) to allow fluid to flow through the orifice plug (414).

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