Patent Application
20080202510
The present invention relates to on-board oxygen generating systems (OBOGS) and, more specifically, to an OBOGS system including a drain valve assembly.
Aircraft on-board oxygen generating systems (OBOGS) have been developed for producing oxygen-enriched air that serves as breathing gas for one or more aircraft occupants (e.g., a pilot). The OBOGS includes an oxygen concentrator, which contains one or more particle beds commonly referred to as sieves. The sieves contain an adsorbent (e.g., zeolite) having a high affinity for nitrogen. As the OBOGS directs airflow through the oxygen concentrator, the sieves remove nitrogen from the air and the air's oxygen content is consequently increased. The resulting oxygen-enriched air is then routed to, for example, an oxygen breathing mask of the type worn by the pilot of a jet.
The air supplied to the OBOGS may be warm and moist. As this warm, moist air cools, condensation forms within the ducting of the OBOGS. Over time, this condensation may pools and wet the sieves. Wetting of the sieves may significantly degrade their performance. In addition, wetting may decrease the sieves' operational lifespan and, thus, require premature OBOGS unit replacement. It is thus desirable to prevent the wetting of the sieves by minimizing the formation or preventing the collection of condensation within the OBOGS.
Certain devices have been developed that may minimize the formation of condensation within the ducting of the OBOGS. For example, a cyclonic separation device may be employed that rotates the pressurized air flowing through the OBOGS at a high rate of speed. This causes the moisture droplets carried by the air to spiral into a tubular cyclone filter, which then removes the moisture from the OBOGS. While cyclonic separation devices of this type are fairly reliable at reducing air moisture content, the cyclone filter permits a substantial loss of pressurized air (“air leakage”) during operation of the OBOGS, which negatively impacts the efficiency of the OBOGS system.
As an alternative to a cyclone separation device, a mixing valve may instead be employed within the OBOGS to minimize the formation of condensation. The mixing valve introduces hot, dry air from an upstream source into the warm, moist air entering the OBOGS. The hot, dry air mixes with the warm, moist air thereby reducing the moisture content thereof, consequently decreasing the formation of condensation within OBOGS ducting. Although such a mixing valve may effectively reduce the volume of collected condensation over a given period of time, the inclusion of such a mixing valve adds considerable weight and cost to the OBOGS system.
It should thus be appreciated that it would be desirable to provide an on-board oxygen generating system configured to minimize retained condensation. In particular, it would be desirable to provide a drain valve assembly that may be employed within an OBOGS that permits condensation to drain therefrom. Furthermore, it would be advantageous for such a drain valve assembly to automatically close when the OBOGS is activated so as to minimize the loss of pressurized air. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
An on-board oxygen generating system is provided, which includes an air supply duct, a breathing gas duct, and an oxygen generator fluidly coupled between the air supply duct and the breathing gas duct. The oxygen generator is configured to enrich the oxygen content of air flowing from the air supply duct to the breathing gas duct. A drain valve assembly is fluidly coupled to the air supply duct and configured to move between: (i) an open position wherein condensation may drain from the air supply duct, and (ii) a closed position.
The preferred exemplary embodiment of the present invention will hereinafter be described in conjunction with the appended drawings, where like designations denote like elements, and:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.
For the purposes of the present invention, oxygen concentrator 28 may comprise any device suitable for enriching the oxygen content of the pressurized air received from air supply duct 24. In the illustrated exemplary embodiment, in particular, oxygen concentrator 28 includes first and second particle beds, or sieves, 34 and 36. Sieves 34 and 36 are each fluidly coupled to concentrator inlet 30, and thus to air supply duct 24, by way of a bifurcated inlet passageway 38. Sieves 34 and 36 each contain an adsorbent (e.g., clay-bound activated zeolite), which chemically binds nitrogen while permitting oxygen and other inert gases (e.g., argon) to flow therethrough. Thus, as the pressurized air flows through sieves 34 and 36, the relative oxygen content of the air increases to, for example, 60 to 90 percent. The oxygen-enriched air then exits sieves 34 and 36 through a bifurcated outlet passageway 42, which is fluidly coupled to concentrator outlet 32. Bifurcated outlet passage 42 includes first and second legs 44 and 46, which may be coupled to sieves 34 and 36, respectively. To permit cross-flow, legs 44 and 46 may be connected by way of a passageway 48. A flow restrictor 50 may be coupled to passageway 48 as indicated in
A bifurcated vent passageway 52 fluidly couples each of sieves 34 and 36 to a vent (e.g., an ambient pressure source). Two solenoid valves 55 are coupled to bifurcated vent passageway 52. Similarly, two solenoid valves 57 are coupled to bifurcated inlet passageway 38. During the operation of oxygen concentrator 28, solenoid valves 55 and 57 cycle open and shut such that one sieve enriches the oxygen content of air flowing from inlet passageway 38 to outlet passageway 42, while the other sieve routes pressurized air from inlet passageway 38 to vent passageway 52 in a self-cleaning process. For example, while sieve 34 may receive air from inlet passageway 38 and deliver oxygen-enriched air to leg 44 of outlet passageway 42, sieve 36 may route pressurized air from inlet passageway 38 to vent passageway 52. In this manner, oxygen concentrator 28 may maintain the optimal performance of sieves 34 and 36 while continually supplying oxygen-enriched air to breathing gas duct 26.
During the operation of OBOGS 20, warm air having a relatively high moisture content may be drawn in to air supply duct 24. As this air cools, condensation may form within the ducting of OBOGS 20 (e.g., on the interior surface of air supply duct 24). As explained above, the effectiveness and/or operational lifespan of sieves 34 and 36 may be significantly decreased if the condensation is permitted to pool and wet sieves 34 and 36. Thus, to prevent the wetting of sieves 34 and 36, OBOGS 20 is equipped with a drain valve assembly 22. Drain valve assembly 22 may be fluidly coupled to the ducting of OBOGS 20. For example, as illustrated in
A moisture inlet 72 and a moisture outlet 74 are provided in housing body 62 of drain valve assembly housing 60. A fitting 76 may be coupled to moisture inlet 72 to facilitate the attachment of, for example, a flexible hosing. A valve 80 is mounted within drain valve assembly housing 60 and movable between (i) an open position wherein moisture may flow from moisture inlet 72 to moisture outlet 74, and (ii) a closed position. As indicated in the illustrated exemplary embodiment, drain valve assembly 22 is preferably a poppet-type valve assembly, and valve 80 is preferably a plug or plunger and will thus be referred to as such herein. This example notwithstanding, it should be understood that drain valve assembly 22 and valve 80 may assume any form suitable for selectively draining condensation from OBOGS 20 (e.g., a butterfly valve assembly and a butterfly valve plate, respectively).
Plunger 80 may be slidably coupled to housing body 62 of housing 60. In particular, plunger 80 may be disposed within a tubular channel 82 provided within housing body 62. To prevent pressurized airflow through channel 82, the outer diameter of plunger 80 may be substantially equivalent to the inner diameter of channel 82, and a seal 84 (e.g., a spring-loaded omni-seal) may be disposed around portion of plunger 80 and sealingly engage an inner surface of channel 82. When plunger 80 descends into the closed position (
A control pressure inlet 88 is provided through cover 64. A fitting 90 may be coupled to inlet 88 to facilitate the attachment of, for example, a flexible hosing, which may form pneumatic passageway 56 (
Plunger 80 includes a second end portion 100, which may have an area of enlarged outer diameter (e.g., an annular collar) 102. A diaphragm cup 104 (e.g., stainless steel), which helps to guide the movement of diaphragm 92, may be disposed between collar 102 and the underside of diaphragm 92. A washer 106 is threaded over end portion 100 of plunger 80. Washer 106 may be held against an upper surface of diaphragm 92 by a nut 108, which may be threadably coupled to end portion 100. In this manner, end portion 100 may be attached to flexible diaphragm 92 such that plunger 80 may move between its open and closed positions as diaphragm 92 flexes upward and downward, respectively. In the open position (
A spring 112 may be disposed within vented chamber 96. The first end of spring 112 may contact an inner portion of housing body 62, and the second end of spring 112 may contact the underside of diaphragm cup 104. Spring 112 biases diaphragm 92 toward the upward position shown in
As indicated above, drain valve assembly 22 may be configured to automatically close and minimize the loss of pressurized air when OBOGS 20 is activated. As explained previously, control pressure chamber 94 may be fluidly coupled to breathing gas duct 26 by way of passageway 54 (
Drain valve assembly 22 may include one or more mounting features. For example, as shown in
In view of the above, it should be appreciated that an on-board oxygen generation system has been provided that minimizes retained condensation. In addition, it should be appreciated that a drain valve assembly has been provided that may be employed within such an OBOGS, which permits the drainage of condensation while minimizing the loss of pressurized air during the OBOGS operation. Of course, it should be understood that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.
This invention was made with Government support under Contract No. N00019-02-C-3002 awarded by Lockheed Martin. The Government has certain rights in this invention.
