Patent Application
20070164163
1. Field of the Invention
This invention relates generally to store carriers for mounting a releasable store on an aircraft and, more particularly, to a stores ejection system from which a store is released with ejective force applied pressurized gas, such as air.
2. Background Description
Pneumatic stores carriage/ejector systems have been developed that utilize high-pressure (e.g., 6,000 psi) gas stored in a pressure vessel to eject stores, such as bombs, missiles, and the like. An example of such a system is disclosed in U.S. Pat. No. 5,583,312, the entirety of which is hereby incorporated by reference herein.
These pneumatic stores carriage/ejector systems may use an integral valve/accumulator module to store the pressure in an accumulator affixed to a valve. Examples of such systems are disclosed, for example, in U.S. Pat. Nos. 6,347,768 and 5,857,647, the entirety of which are hereby incorporated by reference herein. Such systems operate generally as follows: when electrically triggered, a large dump valve is opened; the opening of the dump valve simultaneously provides pressure to a hook opening system and the ejector rams which force the store away.
Although these systems provide a clean and effective means of ejecting stores, a deficiency exists in the technology which limits the operation use of the systems. The deficiency is that the current state-of-the-art seals do not reliably seal at extremely low temperatures, thereby limiting the deployment envelope of the systems.
The aforementioned stores carriage/ejection systems provide weapons release by storing and appropriately releasing energy in the form of very high pressure (e.g., 6,000 psi) gas. The systems use seals that are typically made from resilient materials, such as rubber, or alternatively synthetic elastomer materials.
In basic terms, sealing is achieved by the resilient material distorting or flowing under pressure into the gap area between mating parts, forming a seal. At extremely cold temperatures, seal materials tend to get hard and in this hardened state can not reliably distort or flow to seal gaps.
When pressurized at ambient temperatures the integral valve/accumulator module system can be transitioned to extreme cold temperatures (e.g., −65° F.) without seal degradation. However, when attempting to fill these systems from empty at very low temperatures (e.g., below −30° F.) the seals are too rigid and do not reliably and repeatably seal. This cold start condition may occur, for example, when attempting to fill an empty military weapon release system in an Arctic environment.
The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.
This disclosure provides a means of pre-heating the seals of an unpressurized gas-powered stores ejection system to allow the seals to be more pliable at low temperature and thus reliably seal during Arctic cold start environments. According to one aspect of the invention, a stores ejection system is provided for mounting a jettisonable store on an aircraft which includes an on-board source of pressurized non-pyrotechnic gas, at least one release mechanism for releasably mounting the store, an actuation system for the release mechanism, and a heater for ensuring that seals associated with the stores ejection system remain pliable at extremely low temperatures. The heater advantageously may provide that the seals remain pliable even when the stores ejection system is unpressurized at low temperatures.
The features, functions, and advantages can be achieved independently in various embodiments of the present invention or may be combined in yet other embodiments.
This disclosure adds a heater element into an integrated accumulator valve/release piston system. In an Arctic environment, the heater element may be used to preheat an accumulator valve module prior to high pressure gas being supplied. With the mass on the materials being pre-heated, the seals remain resilient and can properly flow into a sealing position at the time the high pressure gas is added.
With reference initially to
Each dump value 28 may include one or more seals, such as O-ring seals 35a and 35b (
With further reference to
A heater element 51 (that may be an electrical resistance type heater) and a thermocouple 53, that each may be operatively connected to the pressure logic controller 24 via control lines 90 and 92, respectively, may be embedded within each dump valve 28 for heating the O-ring seals 35a, and 35b, in a controlled manner, as may be required prior to pressurization. For example, each heater element 51 may be embedded within the material (e.g., steel) of the housing 33, and the heat produced by each heater element 51 may be conducted through the material of the housing 33 to the O-ring seals 35a and 35b.
Alternatively or additionally, each heater element 51 and/or each thermocouple 53 may be operatively connected to the control unit 50, as indicated by dashed control lines 94 and 96, respectively, in
While the pressurization unit 36 shown and described is preferred, many alternate embodiments are possible. For example, the filter unit 40 is utilized to minimize wear to the system due to impurities in the ambient air, but is not required. Furthermore, the compressor 44 could alternatively be driven hydraulically or may be driven by or comprise a portion of the main aircraft engines. Also, while air is preferred, any known clean gas could be used, and the pressurization unit 36 could actually comprise part of an onboard oxygen or nitrogen generating system. Dry air is desirable in order to minimize system corrosion and because water freezes at high altitude ambient temperatures, resulting in further corrosive conditions within the system. Thus, the use of a drying unit, such as the coalescer and vent solenoid valve unit 54, is preferred. However, the system could be operated without such a unit, albeit with increased required maintenance. Finally, while a single gas generator 36 operated to supply gas to plural S & RE modules is preferred, independent generators for each S & RE module could be used as well, particularly since many available gas generating systems are relatively light and miniaturized, so that undue weight and space penalties are not imposed.
Now with reference to
Structurally, the compressor feed line 58 (
In operation, each S & RE module 12, 14 is initially in an unpressurized state. Loading of a store onto an S & RE module 12, 14 triggers a “store present” signal on a store present switch 76 provided in each module 12, 14. This signal is transmitted by a control line 78 to the pressure logic controller 24, which further transmits it through a second control line 80 to the control unit 50. When the aircraft electrical system is powered up, the “store present” signal causes the pressure logic controller 24 to activate the heaters 51, if necessary due to low ambient temperature, and upon heating of the O-ring seals 35a, 35b, 35c, and 35d to an adequate temperature, based on readings from thermocouples 53, as processed by the pressure logic controller 24, to initiate the pressurization unit 36 by starting the compressor 44, to pressurize each module 12, 14. The pressure logic controller 24 maybe programmed to cycle the heaters 51 on and off, as necessary in order to ensure that the O-ring seals 35a, 35b, 35c, and 35d are maintained at a temperature at which the O-ring seals 35a, 35b, 35c, and 35d are pliable. Pressurized air thus flows through the manifold conduit 34 and into each of the S & RE modules 12, 14 through feed lines 58. When pressure in the accumulator 22 reaches a prescribed pressure, which in the preferred embodiment is approximately 6,000 psi, as detected by the pressure logic controller 24 via a third control line 82, the enable valve 26 (which is preferably a solenoid-operated check valve) closes, isolating the S & RE module 12, 14. When all S & RE modules reach the prescribed pressure, the remotely located pressurization system 36 is shut down. Each S & RE monitor and control system 24 continuously monitors accumulator pressure and periodically activates the pressurization system 36 or vents the accumulator through the over-pressure valve 30 and over-pressure vent 32 to maintain the prescribed pressure.
The aircraft stores management system (SMS) 84, which is preferably of a type well known in the art, controls stores release. On the release command by the SMS 84, through a fourth control line 86, the pilot pressure-actuated high flow rate ejection dump valve 28 is actuated to an open position, permitting pressurized air from the accumulator 22 to flow through port 72 (
Other aspects and features of the present invention can be obtained from a study of the drawings, the disclosure, and the appended claims.
