The inventive subject matter relates to valves and more particularly, to valve assemblies having valve flowbodies and methods of manufacturing fiber composite flowbodies.
An air distribution system may be used to direct air from one portion of an aircraft to another. In some aircraft configurations, the air distribution system includes an inlet duct that receives air from an air source and two or more outlet ducts that exhaust the received air to a desired area within the aircraft, such as, for example, to an aircraft cabin or an underfloor section of the aircraft. Conventionally, a flow splitter is positioned between the inlet and outlet ducts to distribute the air between the ducts.
The flow splitter typically includes a valve assembly that is made up of a valve flowbody and a butterfly plate. The valve flowbody is disposed between the ducts. The butterfly plate is rotationally mounted within the flowbody and is configured to open and close the valve assembly in response to pressure differentials thereacross. During operation, when the valve is closed, the air may circulate through a first system that includes the inlet duct and one of the outlet ducts. When the valve is fully or partially open, the air circulates through a second system that includes the inlet duct and another one of the outlet ducts.
Although the above assembly performs adequately, it may be improved. For example, many conventional valve assemblies are typically made from metal alloys and thus, may be relatively heavy. More recently, valve assemblies have incorporated lighter weight metal alloys, such as aluminum, to reduce weight; however, the demand for even lighter aircraft components continues to increase.
Hence, there is a need for valve assemblies that are more lightweight than conventional valve assemblies. Moreover, there is a need for valve assemblies that are relatively inexpensive and simple to manufacture. Additionally, it is desirable for the valve assemblies to be capable of being retrofitted into existing systems and functioning at temperature extremes.
Methods are provided for forming valve flowbodies. Valve assemblies are also provided.
In an embodiment, by way of example only, the method includes disposing a first fiber composite fabric piece in a cavity of a first half of an outer mold and placing a foam piece over a portion of the first fiber composite fabric piece. A cylinder is placed in the outer mold first half over the foam piece and the first fiber composite fabric piece, where the cylinder is made of a second fiber composite fabric piece. The first half of the outer mold is assembled with a second half of the outer mold to enclose the cylinder, the foam piece, and the first fiber composite fabric piece therebetween. The assembled outer mold is heated to cure resin impregnated in the first and the second fiber composite fabric pieces to form the valve flowbody.
In another embodiment, by way of example only, the method includes disposing a first fiber composite fabric piece in a cavity of a first half of an outer mold, the outer mold first half cavity including a depression therein, the first fiber composite fabric piece including a protrusion and a depression woven therein, the protrusion disposed in the outer mold first half cavity depression. A ring-shaped foam piece is positioned over a portion of the first fiber composite fabric piece. A cylinder is placed in the outer mold first half over the foam piece and the first fiber composite fabric piece, where the cylinder is made of a second fiber composite fabric piece. The first half of the outer mold is assembled with a second half of the outer mold to enclose the cylinder, the foam piece, and the first fiber composite fabric piece therebetween. The assembled outer mold is heated to cure resin impregnated in the first and the second fiber composite fabric pieces to form the valve flowbody.
In yet another embodiment, and by way of example, a valve assembly is provided that includes a valve flowbody, an inner layer, an outer layer, and a foam material. The valve flowbody has an inner surface defining a channel, an outer surface, and a support flange extending from the outer surface. The inner layer forms at least a portion of the flowbody inner surface and includes a first fiber composite material. The outer layer forms at least a portion of the flowbody outer surface and the support flange, and the outer layer includes a second fiber composite material. The foam material is disposed between a portion of the inner layer and a portion of the outer layer forming a portion of the support flange.
Other independent features and advantages of the inventive subject matter will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the inventive subject matter.
The following detailed description of the inventive subject matter is merely exemplary in nature and is not intended to limit the inventive subject matter or the application and uses of the inventive subject matter. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the inventive subject matter or the following detailed description of the inventive subject matter.
To decrease the weight of the valve assembly 110, the valve flowbody 118 may be made of a fiber composite material and/or foam material. In particular, the valve flowbody 118 may include an inner layer 140 and an outer layer 142 that are each made of fiber composite material. For example, the fiber composite material may be a woven, unidirectional, or triaxial braided carbon fiber of predetermined modulus and may be capable of withstanding temperatures of at least 200° C. Examples of suitable fiber composite materials include, but are not limited to carbon, fiberglass, Kevlar, and ceramic fibers. Additionally, the support flanges 130, 132 may include portions made of foam 144, 146. Suitable foam materials include, but are not limited to polymethacrylimide and bismaleimide.
Having provided a description of the valve flowbody 118, a method 300 for forming the valve flowbody 118 will now be provided.
As briefly mentioned above, an inflatable mandrel and a two-piece outer mold are obtained, step 302.
Referring also to
A first fiber composite fabric piece is disposed in the outer mold first half 502 and a foam piece is placed over a portion of the first fiber composite fabric piece to form the support flange 130 of the flowbody 118, step 304. The first fiber composite fabric piece makes up a portion of the flowbody outer layer 142. In an embodiment, the first fiber composite fabric piece is a woven preform. For example, the woven preform may be a substantially flat piece of woven fiber composite material. The material may have any thickness or harness count and may or may not be pre-impregnated with a thermosetting resin. An embodiment of a first fiber composite fabric piece 600 is depicted in
In an embodiment, the foam piece is disposed over the first fiber composite fabric piece 600. The foam piece may be made of polymethacrylimide or bismaleimide and may be capable of withstanding temperatures of at least about 200° C. Additionally, the foam piece may have any shape suitable for providing structure to the valve flowbody support flanges (e.g., support flanges 130, 132 in
Referring again to
It will be appreciated that steps 304 and 305 may be used to form the other support flange 132 of the flowbody 118. For example, another fabric piece 700 (such as shown in
A cylinder comprising a second fiber composite fabric piece is placed in the outer mold first half over the foam piece and the first fiber composite fabric piece, step 306. The cylinder makes up the inner layer 140 of the flowbody 118 and may be formed or disposed around the inflatable mandrel 400. In an embodiment, the cylinder is made by wrapping the second fiber composite fabric piece or “ply” and other fabric plies around the inflatable mandrel 400. The plies may be pre-impregnated with a thermosetting resin, such as, for example, bismaleimide; alternatively, they may not be.
In another embodiment, the cylinder 800 may be made using a woven fabric preform. In particular, the second fiber composite fabric piece may be formed by weaving fiber composite threads into a hollow cylinder or sock and the inflatable mandrel 400 is inserted therein. The woven preform may or may not be pre-impregnated with a thermosetting resin. No matter the particular method of fabrication, the cylinder 800 is then placed in the outer mold first half 502 over the foam piece and the first fiber composite fabric.
Referring again to
The assembled outer mold 500 is heated to cure a selected resin system (e.g., a preimpregnated fabric or non-impregnated fabric by resin transfer molding) in the fiber composite fabric pieces to form the fiber composite valve flowbody 118, step 310. In an embodiment, the assembled outer mold 500 may be placed in an oven or may be heated using heating elements that may be included as part of the outer mold 500. The assembled outer mold 500 may then be heated to a cure temperature and pressure of the selected resin system.
In an embodiment, the assembled outer mold 500 may undergo multiple cure cycle steps before the resin therein fully cures. For example, the assembled outer mold 500 may be heated to about 100° C. to about 120° C. at a steady rate. A vacuum may then be applied. To ensure the inner surface of the cylinder 800 remains suitably shaped, the mandrel 400 is inflated via its end 402 to a pressure. In an embodiment in which a non-preimpregnated fabric is used, the mandrel 400 may be inflated to a pressure that exceeds the resin injection pressure by between about 0 psi and about 100 psi. In an embodiment in which preimpregnated fabric is used, the mandrel may be inflated to a pressure of between about 0 psi and about 45 psi. If the assembled outer mold 50 is under vacuum, the vacuum is then removed. If a non-preimpregnated fabric is employed, the selected resin system is injected into the cavities of the outer mold 500 within a pressure range of between about 60 psi to about 300 psi at a resin temperature of between about 20° C. and about 140° C.
The assembled outer mold 500 is maintained at a temperature that is between about 100° C. and about 120° C. at a selected mandrel pressure for about 45-60 minutes. Pressure on the mandrel may then be increased an additional 0 psi to 100 psi and air and excess resin may be removed from the mold 500. The temperature of the assembled outer mold is then increased at a steady rate to between about 180-200° C., while maintaining the increased mandrel pressure for about 2-6 hours. The assembled outer mold 500 is then cooled at a steady rate to about 50-65° C. Pressure in the mandrel 400 is released and a vacuum is applied to collapse the mandrel.
The assembled outer mold is disassembled and the mandrel is removed to facilitate removal and inspection of the fiber composite valve flowbody 118 therein. After inspection, the flowbody 118 may be subjected to a post-cure step where the valve flowbody is heated to a temperature between about 180° C. and about 225° C. for about 6 hours.
The valve flowbody 118 may undergo a final machining step, step 312. For example, in an embodiment, the valve flowbody 118 may be mounted to a fixture and excess material thereon may be trimmed away. In embodiments in which the flowbody 118 includes protrusions and depressions on its support flanges 130, 132, sleeves 138, 139 may be inserted into the depressions to provide additional structural support for the support flanges 130, 132. The sleeves 138, 139 may be press-fit into the depressions or may be adhered thereto. In embodiments in which the flowbody 118 does not include protrusions and depressions, holes may alternatively be machined at least partially through the flowbody 118. The sleeves 138, 139 may then be inserted into the flowbody holes. A valve plate 128 may be rotationally mounted within the valve flowbody 118.
Valve assemblies have now been provided that may be more lightweight than conventional valve assemblies. Moreover, the valve assemblies may be relatively inexpensive and simple to manufacture and operate over at extreme temperature ranges. Additionally, the valve assemblies may be capable of being retrofitted into existing aircraft systems.
While the inventive subject matter has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the inventive subject matter. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the inventive subject matter without departing from the essential scope thereof. Therefore, it is intended that the inventive subject matter not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this inventive subject matter, but that the inventive subject matter will include all embodiments falling within the scope of the appended claims.