Patent Description:
The present invention relates to the use of ducting systems in aircraft structures. Amongst the prior art, it is well known in the art to use high temperature bleed air from the engines for various on-board purposes in a modern aircraft. Typically, a stream of hot air bled from the engines is used to provide an anti-icing function on the leading edge of the wings and empennage of the aircraft and is also used by the air conditioning units to supply fresh air to the passenger cabin. The bleed air must therefore be transported from the engines to various other areas of the aircraft, and this is typically accomplished utilizing insulated metallic ducts ranging in diameter from <NUM>" (<NUM>) to <NUM>" (<NUM>) and ranging in length from at least <NUM>" (<NUM>). The air in the duct can reach pressures up to <NUM> psig (<NUM> kPA) and temperatures of <NUM>°F (<NUM>), but is typically at a pressure of <NUM> psig (<NUM> kPa) and <NUM>°F (<NUM>) in temperature.

The ducts carrying the engine bleed air are insulated to prevent damage to the aircraft. An insulation blanket is wrapped around the exterior of the duct. This insulation blanket may be composed of a material of the type sold under the tradename Q-Felt® and manufactured by the Johns-Manville Corporation of Denver, Colo. The insulation blanket is capable of lowering the exterior temperature of the duct from <NUM>°F (<NUM>) to about <NUM>°F (<NUM>) or less. A fiberglass impregnated silicone-rubber, textured metal foil, or fiberglass impregnated polyimide resin insulation shell is then wrapped around the exterior of the duct to contain the insulation blanket.

The ducts of the type mentioned herein can develop leaks from the cracking of the inner metallic duct. If such cracks go undetected, catastrophic failure of the duct can result. Therefore, it is necessary to have sensors positioned along the length of the duct to detect any leakage from the duct.

Prior art leak detection sensing systems consisted of a vent disk, which is a disk having a hole therein, which allowed a stream of hot air to escape the silicone-rubber, texturized foil, or polyimide resin insulation shell. In the event that a duct developed a crack, hot bleed air will flow from the metallic duct wall through the insulation blanket and to the vent disk, then through the hole in the vent disk. The vent disk hole is designed to spread the flow of hot air in a cone-like spray pattern impinging on a pair of heat detection wires spaced approximately <NUM>" (<NUM>) apart and positioned approximately <NUM>" (<NUM>) to <NUM>" (<NUM>) from the outer circumference of the duct. The heat detection wires are of the type sold under the tradename Firewire® and manufactured by Kidde Graviner Limited of the United Kingdom. The heat sensing wires change their electrical characteristics when exposed to a predetermined temperature. In the case of typical prior art systems used in aircraft, the detection circuit will trip when the wire is exposed to a temperature of approximately <NUM>°F (<NUM>). It is required that both wires of the pair of wires in proximity to the duct be exposed to this temperature before an alarm will be raised to the pilot of the aircraft, to prevent false alarms.

It is desirable that the leak detectors be able to detect a leak in the metallic duct through a crack having the equivalent area of a <NUM> diameter hole. In practice, it has been found that the prior art leak detection systems fail to detect such leaks. The primary reason for the failure of the prior art design is that there is insufficient air flow through the vent disk hole. This results in the hot air stream having insufficient temperature to trip the heat detection wires. First, the temperature of the hot air through the leakage in the metal duct is significantly reduced as the hot air passes through the insulation blanket. Second, the insulation blanket impedes the passage of the hot air from the site of the leak to the vent disk hole, underneath the silicone-rubber, texturized foil, or polyimide resin insulation shell. Further, it has been found that, by the time the air has traversed the distance between the vent disk hole and the sensor wires, it has fallen to a temperature well below the <NUM>°F (<NUM>) necessary to trip the leak detection wires.

Therefore, it is desirable to improve the design of the leak detection system such that a leak through a crack in the metallic duct having an equivalent area of a <NUM> diameter hole is successfully detected. It is also desirable that the new design be able to be economically retrofitted into existing aircraft. In particular, it is desirable that the same existing sensor wires be used and that it not be necessary to remove the existing insulation and to re-insulate the ducts to install the improved leak detection system.

At the joints between adjacent sections of duct, such as bleed air ducts in aircraft wings, the joints are typically constructed by abutting connection flanges between adjacent duct sections, and then by clamping those connection flanges together through the use of a band clamp or similar mechanism. Because this is a clamped arrangement, and not, e.g., a weld or other sealing structure, a certain amount of leakage is permitted and anticipated. Inasmuch as temperature sensor wires and temperature sensing systems have attained a high degree of sensitivity and responsiveness, it is desirable to provide a bleed leak detection system which is capable of discriminating between the low-level leakage that is part of ordinary and acceptable operating conditions, and the higher-level leakage which indicates either a failure of a joint, or failure of the ducting, not necessarily at the joint but in its vicinity, or even at a distance from the joint.

Additionally, duct leak detection systems can experience high temperatures and pressures. Under these harsh conditions, manufacturing imperfections-such as small cracks or deformities formed during manufacturing-may become exacerbated, resulting in unintended gas leakage and potentially producing false alarms. Furthermore, high temperatures can cause thermal expansion and warping of certain materials, inundating components of the leak detection system itself-potentially leading to another source of unintended gas leaks.

The conditions that result in a gas leak may vary among systems. In some cases, a minor amount of gas leakage may be considered dangerous. In other cases, a small amount of gas leakage may be acceptable. Additionally, various ducting systems may each experience a different level of gas pressure therein. It is accordingly another objective of the present invention to provide an adjustable duct leak detection system to accommodate different levels of gas pressure.

Where components of the leak detection system itself, such as the elastomeric manifold block insert, can be affected by heat and/or pressure, it is especially important to ensure the integrity and adjustability of these elements to, in turn, ensure their reliability.

These and other objectives and advantages will become apparent from the following detailed written description and figures. Prior art <CIT> discloses ducting systems in aircraft which utilize the flow of hot compressed bleed air from the engines for various on-board functions. Prior art <CIT> discloses bleed air ducting systems of the type used in aircraft and relates particularly to leak detection apparatus used therein.

To produce air flow with adequate velocity, the laws of fluid dynamics dictate the necessity for both air pressure and volume. If sufficient air pressure exists at low volume, air flow velocity cannot be sustained once the volume is quickly depleted. If sufficient air volume is present without pressure, there is practically no movement of air from a high to a low pressure environment.

When the metallic duct develops a crack, the hot air leaks from duct interior to the insulation blanket. The insulation blanket changes the characteristics of the hot air leakage <NUM>) by absorbing the thermal energy and reducing the air temperature; <NUM>) by reducing the effective pressure due to pressure drop; and <NUM>) by reducing the volume by diffusing the air in the annulus between metal duct and insulation shell throughout the length of the duct.

Leak detection devices described herein includes manifold assemblies formed from two or more different materials. An elastomeric manifold body includes one metal rigid plate, which serves to reinforce the elastomer and to maintain the shape of the manifold body under high temperatures, pressures and external loads. The combination of metal and elastomer provides structural integrity, resists deformation due to thermal expansion and other environmental forces, and provides a consistent and robust seal due to the flexibility and compressibility of the elastomer.

According to a first aspect of the present invention, there is provided a manifold assembly as in appended claim <NUM>.

The flow control valve may, in some implementations, include a one-way check valve. The one-way check valve may be a spring-biased ball type valve.

Some manifold assemblies may include a spring pocket adapted to maintain a spring. A coil spring may be disposed in the spring pocket. These manifold assemblies may also include a ball movably disposed between the coil spring and the inlet aperture. The ball may have a maximum diameter that is greater than a diameter of the inlet aperture. The coil spring may be configured to press the ball against the inlet aperture by a predetermined amount of force so as to maintain a substantially fluid-tight seal between the inlet aperture and the one or more gas passages. Gas pressure at the inlet aperture exerting a force against the ball that exceeds the predetermined amount of force causes the ball to move toward and compress the coil spring, thereby permitting gas to flow into the one or more gas passages.

In some examples not falling under the scope of the claims, the at least one rigid aperture plate at the lower end of said manifold block is a bottom aperture plate. In other examples not falling under the scope of the claims, the manifold assembly also includes a top aperture plate. In this example, the top aperture plate includes an elongated cutout, and is disposed substantially proximate to a top end of the manifold block so as to substantially align the elongated cutout with the one or more gas passages. The top aperture plate is also adapted to further maintain the substantial circularity of the inlet aperture.

The manifold assembly may also include a set screw disposed within the manifold block adjacent to the flow control valve. The set screw is operably adjustable to extend and retract toward and from a spring element of the flow control valve, thereby increasing and decreasing respectively the amount of force applied by the flow control valve against the inlet aperture.

The elastomeric manifold block is formed from an elastomeric material, such as a silicone material. The aperture plate is formed from a metallic material such as stainless steel.

The aperture plate may, in some instances, be integrally formed with the lower end of the manifold block. For example, the aperture plate may be inserted into a silicone manifold block, and the aperture plate may adhere to the silicone while it is being cured. In an example not falling under the scope of the claims, the aperture plate may also be disposed within the lower end of the manifold block such that a layer of elastomeric material at least partially covers the bottom surface of the aperture plate.

The flow control valve may include a spring element that causes the component of the flow control valve to exert a first amount of force against inlet aperture. The pressure threshold necessary to open the flow control valve is proportionate to the first amount of force, such that gas pressure that exerts an amount of force exceeding the first amount of force causes the flow control valve to open.

According to a second aspect there is provided a joint cover apparatus having a manifold assembly as described abovefor transporting high temperature pressurized gases, for covering a joint between abutting duct sections, wherein the ducting system is provided with a leak detection system using one or more temperature-responsive sensor wires and a joint cover apparatus as set out according to the first aspect above.

In these embodiments, the upper ends of said one or more gas passages are configured to direct leaking gas toward one or more respective gas detectors. The joint cover apparatus may further include a flow control valve disposed within the manifold block between the inlet aperture and the one or more gas passages. The flow control valve may be configured to maintain a closed state in which a component of the flow control valve engages in a sealing manner with the inlet aperture to preclude gas at the inlet aperture from flowing into the one or more gas passages until said gas reaches a pressure corresponding to a pressure threshold. Additionally, the joint cover apparatus includes at least one aperture plate having a substantially circular opening. The at least one aperture plate is disposed substantially proximate to a lower end of the manifold block in substantial alignment with the inlet aperture of the manifold block. The aperture plate is adapted to maintain the substantial circularity of the inlet aperture, to in turn ensure a substantially fluid-tight seal between the inlet aperture and the one or more gas passages until said gas reaches said pressure threshold.

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

For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which:.

There will now be described by way of examples, several specific modes of the invention as contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

The examples shown in <FIG>, <FIG>, <FIG>, <FIG> and <FIG> do not fall within the scope of the claims, but are considered useful for understanding the invention.

Leak detection devices of the present application may be integrated within a joint cover for a ducting system. When two separate ducts abut, an annular "cuff" may be secured around the joint. The two separate ducts may be secured together in various ways, such as with clamps or flanges. In some instances, the joint cover or cuff may protrude radially outward, forming an annular chamber that surrounds the joint. A joint cover may have integrated therein a manifold assembly that includes a flow control device-such as a check valve-that fluidly interfaces with this annular chamber.

Although the two separate ducts are intended to be adjoined in a sealing manner, so that gas passing from one duct to the other remains within the inner walls of the ducts, the adjoining means may not provide a complete seal that causes some gas to leak out from within the ducts into the annular chamber of the joint cover. As gas pressure builds within the annular chamber, an increasing amount of force may be applied against the flow control device. Once this force exceeds an amount of opposing force applied by the flow control device, that device may move into the manifold assembly and permit gas to flow through an inlet aperture of the manifold assembly and, in turn, into one or more gas passages within the manifold assembly.

The manifold assembly may be configured to maintain one or more temperature sensors positioned within or proximate to the one or more gas passages. In circumstances where the duct carries hot gas, such as hot exhaust gases, the temperature sensors detect the presence of gas passing through the one or more gas passages. In this manner, reading out the temperature measurements may serve as a basis for detecting a gas leak from the duct joint.

Leak detection devices described herein may utilize a check valve situated between an inner chamber of a joint cover and one or more gas passages fluidly coupled to temperature sensors. When pressure within the joint cover chamber exceeds a threshold pressure, gas therein may apply a force against the check valve that causes it to open or otherwise permit the flow of gas into the one or more gas passages. In some applications, such as aircraft ducting, the gas is hot relative to the environmental temperature. As this hot gas flows past the check valve and into the one or more gas passages, the temperature sensors are heated and thus detect the presence of the gas.

A check valve may operate by pressing an object against an aperture with some amount of pressure. For example, a check valve may include a spring that presses a ball against a substantially circular aperture or valve seat. In order to function properly, the dimensions of the ball complement the shape of the aperture, such that the ball pressing against the aperture forms an annular seal around the edge of the aperture.

If the dimensions of the ball does not fully complement the shape of the aperture, small gaps may exist that permit gas to flow past the check valve while it is in the closed position. For instance, where an aperture is either elliptical or ovoid as a result of either wear or manufacture, may preclude the ball from forming a complete seal around the aperture. In some cases, the material with which the aperture is constructed may deform, warp, expand, or otherwise change shape when subjected to high pressures, temperatures, and/or vibration. Even if the ball forms a complete seal around the aperture during manufacturing or testing, such deformation during operation can also result in unintended gas flow past the check valve in the closed position.

Some materials resist deformation or are less susceptible to thermal expansion. However, constructing a leak detection device using such materials may require expensive and overly-precise manufacturing. Other materials, including elastomers such as silicone, are flexible and compressible, allowing them to form a seal within some manufacturing tolerances. However, those materials may change shape under high temperatures and pressures.

Manifold assemblies described herein include a combination of compressible or flexible materials, and rigid or metallic materials. In some examples, a manifold body is constructed from an elastomer, such as silicone, that integrates therein one or more metal aperture control plates. A check valve ball may be seated within an elastomeric inlet aperture that is supported by and reinforced with a metal aperture control plate. As the ball presses into the aperture, the elastomer may compress, bend, or flex against the metal plate thereunder. A portion of the elastomer at the inlet aperture may conform to the opening of the metal plate, forming a seal at the interface of the ball and elastomer.

The combination of compressible and rigid materials cooperate with each other to provide a check valve seal that resists deformation under high temperatures and/or high pressures. The rigidity of an aperture control plate may help maintain the substantial circularity of an elastomeric inlet aperture, while the elastomer provides a flexible and compressible material against which the check valve can press to form a seal. Thus, the combination of metal and elastomer diminishes the drawbacks otherwise inherent in manifolds made of a single material.

In some implementations, multiple aperture control plates may be integrated within the manifold assembly, to further prevent deformation of the elastomer. Additional aperture control plates may also serve to maintain a consistent shape of the elastomer while it is being cured, during manufacture.

The conditions under which a manifold assembly is detecting a gas leakage may vary, depending on the specific system. Accordingly, some manifold assembly embodiments of the present invention include a set screw in mechanical communication with the check valve spring. As the set screw is turned, it extends into a pocket within which the spring is seated. The set screw may press against a plate or disk within this pocket, compressing the spring and increasing the amount of force that the ball presses against the inlet aperture. The set screw can likewise be retracted to decrease the spring bias or pressure. Such an arrangement permits an operator to adjust the force applied by the spring-and therefore the amount of gas pressure required to push the ball up and open the check valve-without having to disassemble or replace the manifold assembly.

As described herein, "heated," "hot," "chilled," "cooled," or any other term describing the temperature of a fluid or object refers to the relative temperature of that fluid with respect to a reference temperature, such as the temperature of the environment. The actual temperatures of gases and liquids may vary, depending upon the specific circumstances.

A typical duct assembly of the type with which the invention is intended to be used comprises an inner metal duct, typically composed of steel, and <NUM>" (<NUM>) to <NUM>" (<NUM>) in diameter, covered by an insulation blanket, and secured by an outer insulation shell. The insulation blanket and outer insulation shell are composed of materials as previously discussed.

A cuff may be positioned circumferentially around outer insulation shell of a duct assembly. Preferably, the cuff is composed of multiple plies of silicone rubber impregnated with fiberglass (to limit stretch), and, in the most preferred embodiment, three plies are used to avoid having the cuff rupture due to excessive pressure build-up when installed in situ around the duct assembly. Before securing the cuff to the duct assembly, an outer insulation shell may be cut circumferentially around the duct assembly. A small amount of an outer insulation shell may also be removed to form a narrow gap in the outer insulation shell.

To secure the cuff to the duct assembly, the cuff may be situated circumferentially around the portion of the duct assembly in which the cut in the outer insulation shell has been made, with a tongue and groove arrangement at the ends of the cuff.

The cuff may include a raised middle portion and shoulders on either side thereof. Shoulders will rest against outer insulation shell of duct assembly while raised middle portion remains above insulation shell thereby defining an annular-shaped void thereunder. The cuff is secured to the duct by wrapping the shoulders and the adjoining area of the outer insulation shell with a heat-resistant, silicone-rubber compound tape. One example of an appropriate heat-resistant, silicone-rubber tape is sold under the tradename MOX-Tape™ and manufactured by Arlon Corporation of Santa Ana, Calif. In lieu of heat resistant tape, any known method of securing cuff to duct assembly may be used, as long as the passage of air through insulation layer to the void under cuff is not restricted. The cuff should be situated on the duct assembly such that hole is in a convenient orientation with respect to the position of existing sensor wires such that air escaping hole will impinge on both of the sensor wires. Because pressures within the inner metal portion of duct assembly can reach substantially high pressures, it can be expected that pressure within the void created between cuff and duct assembly may also experience some fraction of the substantial pressure. As a result, it is possible that the middle portion of cuff may deform because of bowing due to pressure buildup in the void inside cuff. As a result, it is also possible that hole may not direct the air escaping therefrom to impinge onto sensor wires when middle portion of cuff is deformed.

In ducting structures of the type described herein, the specifications for the ducts allow for a small amount of leakage, particularly at the locations where the two sections of duct are joined together by a coupling. Accordingly, in order to prevent false alarms resulting from such small, accounted for leakage, it is desirable to provide a way to prevent leaking gases from reaching the highly sensitive temperature sensing wires, unless and until the volume and/or pressure of the leaking gases exceed a preselected value.

Therefore, coupling covers employed in accordance with the principles of the present invention, particularly those covering duct couplings, may be provided with a check valve, which is biased in a closed position, against leakage gas pressures which are below a preselected threshold level.

Prior art coupling cover <NUM> is shown in perspective view in <FIG>, in the form of a split ring, having, at the split, a first inner portion <NUM> that is overlapped by a second outer portion <NUM> in the vicinity of the split. First inner portion <NUM> has wedge-shaped or ramp-shaped outer contours. Coupling cover <NUM> is held in place by band clamps <NUM>. Each band clamp may be in the form of a conventional hose-type clamp, having a band <NUM>, and a screw drive section <NUM>. As band clamps <NUM> are tightened, second outer portion <NUM> is forced to ride up first inner portion <NUM>, creating a binding fit, so as to inhibit the leakage of gases therebetween. Coupling cover <NUM> is preferably fabricated from a silicone rubber impregnated fiberglass cloth, which may be pre-molded, and cured in a temperaturecontrolled environment. Opening <NUM> in coupling cover <NUM> permits manifold block <NUM> to be inserted therethrough from the inside, and held in place, e.g., by an RTV ("Room Temperature Vulcanization") adhesive. In preferred embodiments of the invention, coupling cover <NUM> is fabricated from the same material and cured in the same manner as the cuff.

<FIG> is a lengthwise or longitudinal sectional view of a prior art duct joint surrounded by a coupling cover <NUM>. Duct sections <NUM>, <NUM> are connected to one another by joint flanges <NUM> affixed to the ends of the respective duct sections <NUM>, <NUM>. Joint flanges <NUM> are, in turn, held together by V-band coupling <NUM>, formed from V-band <NUM> and strap <NUM>. V-band coupling will have a screw drive section (not shown), such as used with band clamps <NUM>, to tighten strap <NUM>, to create radially inwardly directed clamping pressure against flanges <NUM>. Standoffs <NUM> are used to provide radial spacing between duct sections <NUM>, <NUM>, and insulation shells <NUM>. Insulation (not shown) may typically be provided in the annular gap between insulation shells <NUM> and duct sections <NUM>, <NUM>.

<FIG> illustrate various views of example manifold assemblies. These views may or may not be drawn to scale, and are provided for explanatory purposes. For example, actual aperture control plates may be thinner or thicker relative to other portions of the manifold assembly; however, those aperture control plates are drawn with sufficient thickness to be illustrated in the figures. One of ordinary skill would appreciate that the dimensions of the components in the figures are intended to help facilitate understanding of the manifold assembly, and may or may not necessarily reflect the physical geometry or proportions in actual implementations.

<FIG> is an elevated cross-sectional side view of an example manifold assembly <NUM>. Manifold assembly <NUM> includes body <NUM>-<NUM>, which include voids therein that define gas passages <NUM> and <NUM>, a pocket within which spring <NUM> is maintained, and an inlet aperture <NUM>. Body <NUM>-<NUM> may be a continuous elastomeric housing, or may be two or more separate pieces that are fixed relative to each other. The inlet aperture <NUM> may serve as a seat for ball <NUM> which, under some conditions, maintains a seal preventing gas from flowing through inlet aperture <NUM> and into gas passages <NUM> and <NUM>. Spring <NUM> may be situated above the ball and opposite to inlet aperture <NUM>, so as to provide a downward force against ball <NUM>.

Manifold assembly <NUM> also includes manifold block <NUM>, together with aperture control plate <NUM>. Manifold block <NUM> may be formed from an elastomeric material, and may include grooves or depressions extending longitudinally on opposite sides of ball <NUM>. Manifold block <NUM> includes an substantially cylindrical inlet aperture within which ball <NUM> is seated. Manifold assembly <NUM> also includes aperture control plate <NUM>, which includes an opening proximate to inlet aperture <NUM>. Aperture control plate <NUM> may be adhered to or integrated with the lower end of manifold block <NUM>, such that an opening of aperture control plate <NUM> is substantially in alignment with the inlet aperture <NUM>. Aperture control plate <NUM> may be formed from a rigid metal material, such as stainless steel.

As shown in <FIG>, inlet aperture <NUM> of manifold block <NUM> varies in diameter along the vertical axis. At the upper end near gas passages <NUM> and <NUM>, the diameter of inlet aperture <NUM> is wider, compared to the diameter of inlet aperture <NUM> at the lower end near aperture control plate <NUM>. The narrower diameter near the bottom of inlet aperture <NUM> may allow ball <NUM> to compress a portion of the manifold block <NUM> against aperture control plate <NUM>. The portion of manifold block <NUM> compressed between ball <NUM> and aperture control plate <NUM> forms a seal that prevents gas from flowing into gas passages <NUM> and <NUM>, until the bias of spring <NUM> is overcome to urge ball <NUM> upwardly. As described herein, the "inlet aperture" may generally refer to the bottom portion of the substantially cylindrical void of manifold body <NUM> against which ball <NUM> presses.

During operation, gas pressure may build up in a chamber situated below ball <NUM>. Once that gas pressure exerts enough force to overcome the force of spring <NUM>, ball <NUM> moves upwardly toward the pocket in which spring <NUM> is maintained. Once this seal between ball <NUM> and manifold block <NUM> has been disengaged, some of the built up gas flows into gas passages <NUM> and <NUM> and up toward channels <NUM> and <NUM>, respectively. Channels <NUM> and <NUM> may be configured to maintain temperature sensors (e.g., thermocouples, temperature-sensitive wires, etc., not illustrated in <FIG>) capable of detecting the presence of heated gas at channels <NUM> and <NUM>. Channels <NUM> and <NUM> may also permit gas to vent into the surrounding aircraft environment, for example, in a wing or fuselage, depending upon the specific implementation.

Techniques other than temperature sensing may be used to detect the presence of gas within the manifold. For example, pressure transducers secured to channels <NUM> and <NUM> may modulate when gas flows in gas passages <NUM> and <NUM>. Other types of sensors may also be used to detect the presence of gas, which utilize electrochemical processes, sense photoionization, detect infrared light, and semiconductors whose impedance modulates in the presence of certain gases, ultrasonic transducers that detect the flow rate of gases, among other types of sensors. Although embodiments described herein refer to temperature sensing methods, one or ordinary skill would appreciate that a variety of sensing techniques may be used to detect the presence of gas.

In some implementations, manifold body <NUM> and manifold block <NUM> are integrally formed. In other implementations, manifold block <NUM> is a separate element that is inserted into or adhered to manifold body <NUM>. Although manifold body <NUM> and manifold block <NUM> are drawn with different shading in <FIG>, manifold body <NUM> and manifold block <NUM> may be formed from a single piece of material (e.g., silicone cured in a manifold body mold).

<FIG> is an enlarged cross-sectional view of manifold assembly <NUM> in <FIG>, focusing on the inlet aperture <NUM> region. As illustrated in <FIG>, the lower portion of manifold <NUM> forming the inlet aperture <NUM> compresses against aperture control plate <NUM>. As a result of the spring force applied against ball <NUM>, the compressed portion of inlet aperture <NUM> conforms to the shape of ball <NUM>. In this manner, the compressed portion of inlet aperture <NUM> forms a seal between the opening of aperture control plate <NUM> and ball <NUM>, thereby preventing gas from flowing into gas passages <NUM> and <NUM>.

The specific shape and dimensions of the inlet aperture may or may not be drawn proportionally, and may not represent the actual shape of the compressed material. Any inaccuracies or exaggerations are provided for explanatory purposes, to show how an elastomer compresses between ball <NUM> and aperture control plate <NUM> to form a seal.

<FIG> is an elevated cross-sectional side view of an example manifold assembly <NUM>, which is similar to manifold assembly <NUM> shown in <FIG>. However, in <FIG> the diameter of the opening of aperture control plate <NUM> is larger than of aperture control plate <NUM>. As shown in <FIG>, the diameter of inlet aperture <NUM> is less than the diameter of the opening of aperture control plate <NUM>. As a result, an annular ring <NUM> of elastomer from manifold block <NUM> extends radially inward, past the lip 504a of the opening of aperture control plate <NUM>.

Depending on the downward force applied by the spring onto ball <NUM>, annular ring <NUM> of manifold block <NUM> may deform and migrate downwardly into the opening of aperture control plate <NUM>. <FIG> illustrate different stages of this migration for manifold assembly <NUM> in <FIG>.

In <FIG>, ball <NUM> is in a first position and applies little or no downward force onto annular portion <NUM> of elastomer, such that little or no migration into opening <NUM> occurs. At stage <NUM>, annular portion <NUM> extends radially inward past the outer circumference of opening <NUM>, but does not extend downward into opening <NUM>.

In <FIG>, ball <NUM> is in a second position and applies some downward force onto annular portion <NUM> of elastomer, causing partial migration into opening <NUM>. At stage <NUM>, annular portion <NUM> partially deforms or warps, conforming to the shape of ball <NUM> and forming a seal. An upward force produced by gas pressure, for example, may cause ball <NUM> to move upward toward or above the first position shown at stage <NUM>, allowing gas to flow between a narrow passageway between ball <NUM> and annular portion <NUM>.

In <FIG>, ball <NUM> is in a third position and applies an even greater downward force onto annular portion <NUM> of elastomer, causing even greater migration into opening <NUM>. At stage <NUM>, annular portion <NUM> deforms and compresses, conforming to the shape of ball <NUM> and extending to the lower surface of opening <NUM>. As a result, a seal between ball <NUM> and annular portion <NUM>-reinforced by aperture control plate <NUM>-is formed. A sufficiently strong upward force produced by gas pressure, for example, may cause ball <NUM> to move upward toward or above the first position shown at stage <NUM>, allowing gas to flow between a narrow passageway between ball <NUM> and annular portion <NUM>.

Stages <NUM>, <NUM>, and <NUM> of elastomeric deformation at the inlet aperture <NUM> may not necessarily be drawn to scale. Some aspects of <FIG> may be exaggerated for explanatory purposes to illustrate the migration of annular portion <NUM> into opening <NUM>. The actual manner of deformation, compression, and/or migration of elastomer may depend on the particular elastomer used and the specific dimensions of the manifold assembly.

<FIG> is an elevated cross-sectional side view of an example manifold assembly <NUM>, which is similar to manifold assembly <NUM> shown in <FIG>. In <FIG>, the diameter of the opening of aperture control plate <NUM> is larger than that of aperture control plate <NUM>. Additionally, the elastomer at the inlet aperture <NUM> extends downward into the opening of aperture control plate <NUM>, such that an annular ring of elastomeric material lines the circumference of the opening, prior to the exertion of pressure by ball <NUM> against manifold assembly <NUM>.

Depending on the downward force applied by the spring onto ball <NUM>, this annular ring of elastomer may likewise deform, and compress against the opening of aperture control plate <NUM>. <FIG> illustrate different stages of this migration for manifold assembly <NUM> in <FIG>.

In <FIG>, ball <NUM> is in a first position and applies little or no downward force onto annular portion <NUM> of elastomer, such that little or no compression between ball <NUM> and aperture control plate <NUM> occurs. At stage <NUM>, annular portion <NUM> is substantially not compressed, which may form a thin seal between the upper edge of annular portion <NUM> and ball <NUM>.

In <FIG>, ball <NUM> is in a second position and applies some downward force onto annular portion <NUM> of elastomer, causing partial compression against aperture control plate <NUM>. At stage <NUM>, annular portion <NUM> partially deforms and compresses against aperture control plate <NUM>, conforming to the shape of ball <NUM> and forming a seal. An upward force produced by gas pressure, for example, may cause ball <NUM> to move upward toward or above the first position shown at stage <NUM>, allowing gas to flow between a narrow passageway between ball <NUM> and annular portion <NUM>.

In <FIG>, ball <NUM> is in a third position and applies an even greater downward force onto annular portion <NUM> of elastomer, causing even greater compression against aperture control plate <NUM>. At stage <NUM>, annular portion <NUM> deforms and compresses, conforming to the shape of ball <NUM>. As a result, a seal between ball <NUM> and annular portion <NUM>-reinforced by aperture control plate <NUM>-is formed. A sufficiently strong upward force produced by gas pressure, for example, may cause ball <NUM> to move upward toward or above the first position shown at stage <NUM>, allowing gas to flow between a narrow passageway between ball <NUM> and annular portion <NUM>.

Stages <NUM>, <NUM>, and <NUM> of elastomeric deformation at the inlet aperture <NUM> may not necessarily be drawn to scale. Like <FIG>, some aspects of <FIG> may be exaggerated for explanatory purposes to illustrate the compression of annular portion <NUM> against aperture control plate <NUM>. The actual manner of deformation and/or compression of elastomer may depend on the particular elastomer used and the specific dimension of the manifold assembly.

<FIG> is a cross-sectional side view of an example manifold assembly <NUM>, which is similar to manifold assembly <NUM> shown in <FIG>. However, in <FIG> aperture control plate <NUM> is embedded within the lower portion of manifold block <NUM>, to expose assembly portion 903a beneath. When bonding manifold block <NUM> to its final position within the main manifold body, another layer of silicone may be used. This layer of silicone may bond better to layer 903a than to aperture control plate <NUM>.

<FIG> is a cross-sectional side view of an example manifold assembly <NUM>, which is similar to manifold assembly <NUM> shown in <FIG>. However, in <FIG>, manifold assembly <NUM> includes two aperture control plates: top aperture control plate <NUM> and bottom aperture control plate <NUM>. Similar to bottom aperture control plate <NUM>, top aperture control plate <NUM> provides additional rigidity and support to manifold block <NUM>, resisting deformation and warping that might otherwise occur in a fully elastomeric manifold assembly.

Just as bottom aperture control plate <NUM> serves to maintain the substantial circularity of inlet aperture <NUM>, top aperture control plate <NUM> may also serve to maintain the shape of the upper end of manifold block <NUM>. In some instances, it may be desired to maintain the shape of the upper end of manifold block <NUM> to ensure that ball <NUM> travels in a substantially upward direction, without being biased toward gas passage <NUM> or gas passage <NUM>. Top aperture control plate <NUM> may also serve to maintain the shape of manifold block gas passages, and to prevent biasing of ball <NUM>. Preventing biased flow may be desired in implementations where sensors within gas passages <NUM> and <NUM> require parity or mirrored measurements.

<FIG> is a cross-sectional side view of an example manifold assembly <NUM>, which is similar to manifold assembly <NUM> shown in <FIG>. However, manifold assembly <NUM> also includes set screw <NUM> and spring disk <NUM>. In this example, manifold body <NUM> includes screw threading disposed above spring pocket <NUM> within which spring <NUM> is maintained. As set screw <NUM> is rotated in one direction, the lower end of set screw <NUM> extends downwardly into spring pocket <NUM>, causing spring disk <NUM> to move downward, to increase the spring bias. Likewise, as set screw <NUM> is rotated in the opposite direction, the lower end of set screw <NUM> retracts upwardly from spring pocket <NUM>, causing spring disk <NUM> to move upward, to decrease the spring bias. Spring disk <NUM> contacts spring <NUM>, and its position serves to set the rest compression length of spring <NUM>. In this manner, set screw <NUM> permits the strength of the spring force against ball <NUM> to be adjustable-for selection as desired depending upon a desired gas pressure threshold.

<FIG> is an exploded perspective view of an example manifold insert <NUM>. Manifold insert <NUM> includes top aperture control plate <NUM>, manifold block <NUM>, and bottom aperture control plate <NUM>. Top aperture control plate <NUM> includes a void <NUM> shaped as a circle with elongated arms extending longitudinally therefrom, to accommodate the gas passages. Manifold block <NUM> includes void <NUM> that at least partially defines one or more gas passages within a manifold assembly, which are shaped substantially similarly to void <NUM> and are aligned with void <NUM>. Bottom aperture control plate <NUM> includes a substantially circular opening <NUM> which is substantially in alignment with the cylindrical portion of void <NUM>.

<FIG> is an assembled perspective view of an example manifold insert <NUM> with two elongated voids extending longitudinally along the manifold insert <NUM> to partially define gas passages. The circular or cylindrical void at the center of manifold insert <NUM> may serve as a seat for a check valve ball.

<FIG> is a front cross-sectional perspective view <NUM> of an example manifold assembly <NUM> integrated with a joint cover <NUM> for a ducting system. The ducting system includes duct <NUM> abutting against <NUM>, which are joined together with a clamp or flange. Joint cover <NUM> surrounds this joint, which forms an annular chamber <NUM> around the joint. Manifold assembly <NUM> is integrated with the joint cover <NUM>, having an inlet aperture <NUM> in fluid communication with annular chamber <NUM>. Also shown are top aperture control plate <NUM> and bottom aperture control plate <NUM>.

As gas pressure leaking from within ducts <NUM> and <NUM> fill annular chamber <NUM>, gas pressure increases therewithin. Once that gas pressure exerts enough force against ball <NUM> to overcome the opposite force applied by spring <NUM> against ball <NUM>, ball <NUM> moves upwardly to permit gas to flow through inlet aperture <NUM>. Elongated gas passages (disposed in front and behind ball <NUM> from the perspective shown in <FIG>, and not illustrated in <FIG>) direct that gas toward the one or more gas sensors.

Although certain example methods and apparatus have been described herein, the scope of coverage of this patent is not limited to any such example methods and apparatus unless the same are expressly incorporated into the subject matter of the appended claims.

It should be understood that arrangements described herein are for purposes of example only. Further, many of the elements that are described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location, or other structural elements described as independent structures may be combined.

Claim 1:
A manifold assembly (<NUM>-<NUM>) configured for integration with a joint cover apparatus in a ducting system to detect leaking gas, the manifold assembly comprising:
an elastomeric manifold (<NUM>, <NUM>) block having a substantially circular inlet aperture (<NUM>) and one or more gas passages having upper ends, said one or more gas passages being fluidly coupled to the inlet aperture, wherein the upper ends of said one or more gas passages are configured to direct leaking gas toward one or more respective gas detectors; and
a flow control valve (<NUM>, <NUM>) disposed within the manifold block between the inlet aperture and the one or more gas passages, said flow control valve configured to maintain a closed state in which a component of the flow control valve sealingly engages with the inlet aperture to preclude gas at the inlet aperture from flowing into the one or more gas passages until said gas reaches a pressure corresponding to a pressure threshold;
characterized in that said manifold assembly further comprises at least one aperture plate (<NUM>, <NUM>) having a substantially circular opening, said at least one aperture plate being formed from a rigid metallic material, said at least one aperture plate being rigid for maintaining the substantial circularity of the inlet aperture and being disposed substantially proximate to a lower end of the manifold block, said circular opening of the at least one aperture plate being in substantial alignment with the inlet aperture of the manifold block,
said elastomeric manifold block including an annular portion (<NUM>, <NUM>) extending radially inward of the circular opening that is configured to deform and compress against the circular opening of the aperture plate by said component of the flow control valve, to yield a fluid tight seal between the inlet aperture and the one or more gas passages until said gas reaches said pressure threshold, wherein the diameter of the inlet aperture of the elastomeric manifold block at the annular portion is less than the diameter of the circular opening of the aperture plate.