EMERGENCY LUBRICATION MIST SYSTEM

Abstract: An emergency lubrication mist system (10) is operable in response to a drop in oil pressure in a primary lubrication system for components inside a casing (8). An emergency oil reservoir (16) provides a head of oil for discharge through an air activated misting nozzle (22) sized to dispense an oil in a mist (40) for fogging the inside of the casing (8) and coating the components inside. The misting nozzle (22) has an air passageway (26) normally closed to a source of air (28) and opening to operate the emergency system (10) in response to a drop of pressure in the primary lubricating system.

Description: EMERGENCY LUBRICATION MIST SYSTEM TECHNICAL FIELD OF THE INVENTION This invention relates to lubrication systems, and, in particular, to an emergency lubrication system operable upon failure of a primary lubricator system for providing a mist of lubrication to create an oil rich atmosphere for components within a housing. BACKGROUND OF THE INVENTION Emergency or secondary lubrication systems are well known for providing lubrication to equipment during failure of the primary lubrication system. Sophisticated equipment, such as aircraft, require emergency lubrication systems to lubricate moving parts and to operate for a sufficient period of time to allow continued operation of the equipment. Failure of the primary lubrication system for an aircraft may come from any of a number of events, such as ballistic damage, lubrication pump failure, or loss of lubrication from a system leak. Several types of emergency or secondary lubrication systems have been used to provide needed lubrication to equipment. Lubricating wicks have been provided for lubricating individual components. Lubrication jets have been provided for individual components along with a small recirculation system. An air aspirated nozzle has been used for delivering a stream of oil to an individual component of the equipment. Further, drip pans have been used as a source of emergency lubrication for equipment. These existing emergency lubrication systems have disadvantages when emergency lubrication is required for a high number of moving parts which would require a high number of applicators dedicated to these parts, causing an undesirable weight and loss of space for such a system. Failure of any one of such applicators would cause the loss of lubrication for that part, though other parts may receive lubrication. Prior emergency lubrication systems with dedicated applicators require a large volume of oil to provide a stream of oil to each part. Emergency lubrication systems using drip pans are not usable in various tilt attitudes in gear boxes on board aircraft, and the orifices restricted in size for extending the operating time are subject to clogging. Thus, a need has risen for a secondary or emergency lubrication system which overcomes these problems and provides adequate oil to all parts needing lubrication and further, allows the equipment to operate for an extended time period following loss of the primary lube system. SUMMARY OF THE INVENTION The emergency lubrication system of the present invention provides a mist or fog of lubrication throughout an enclosed volume containing moving parts requiring lubrication, such as a gear box on board an aircraft. Reservoirs of emergency oil are filled by the primary lubrication system during equipment start up and retained during loss of the primary system. Upon loss of oil pressure in the primary system, air is supplied to one or more misting nozzles directed within the gear box for drawing oil from the reservoirs and for atomizing the oil to fill the gear box and lubricate the moving parts with oil. The emergency lubrication mist system of the present invention overcomes the disadvantages noted above for prior emergency lubrication systems. The system of the present invention utilizes less oil to lubricate a number of moving parts than prior systems with a nozzle dedicated to each part. A plurality of mist type nozzles as part of the present invention may provide lubrication to a compartmentalized casing or provide redundancy in the event of failure of one of the emergency mister nozzles. The emergency mist lubrication system of the present invention can operate on the oil supply retained in its reservoirs to extend the operating time of the equipment. The system does not require recirculation to achieve extended operation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and for further advantages thereof, reference is made to the following Description of the Preferred Embodiment taken in conjunction with the accompanying drawings in which: FIGURES 1A and IB illustrate an aircraft rotor gear box assembly including an emergency mist lubrication system of the present invention; FIGURE 2 is a cross-sectional view taken along the line A-A' of FIGURE IB; FIGURE 3 is a partial plan view of the gear box of FIGURE 1; FIGURE 4 is a sectional view of the gear box of FIGURE 3 taken along the line B-B'; and FIGURE 5 is an enlarged cutaway view of a misting nozzle used in the emergency mist system of the present invention. DETAILED DESCRIPTION FIGURES 1A AND IB illustrate a complex prop rotor gear box 8 for a tilt rotor aircraft (not shown) which incorporates the emergency mist lubrication system of the present invention. A plurality of mist nozzles 22 are generally indicated where they are located in the gear box 8. A plurality of misting nozzles 22 are provided as part of the emergency mist system to the prop rotor gear box 8. The compartmentalization of the prop rotor gear box and the size of the gear box and components to be lubricated make it suitable for a plurality of misting nozzles 22. Multiple oil reservoirs 16 (see FIGURE 4) are located throughout the gear box 8 and in close proximity to the misting nozzle 22. Due to the disbursement of fine droplets in oil mist 40, oil mist circulates with the movement of the air and the moving components throughout the interior of the gear box 8. The number of misting nozzles 22 create an oil rich atmosphere of fine droplets disbursed by the misting nozzles 22 to provide for redundancy in the system. FIGURE 2 is a cross-sectional view of the gear box 8 taken along the line A-A 7 of FIGURE IB. Referring to FIGURES 3 and 4, FIGURE 3 is a partial plan view of gear box 8 and FIGURE 4 is an enlarged sectional view taken along line B-B of FIGURE 3 to illustrate in greater detail the emergency mist system of the present invention, generally identified by the reference numeral 10. The emergency mist system 10 provides lubrication to moving parts inside a complex prop rotor gear box 8 for use in a tilt rotor aircraft (not shown) . During normal operation, lubricating oil from a main lubricating line 14 fills an emergency oil reservoir 16 built into the gear box 8. An inlet 18 is located at the top of the oil reservoir 16 so that lubricating oil is retained within the reservoir 16 after loss of the primary source of lubrication. A screened restrictor 20 is located at the reservoir inlet 18 to restrict the flow of oil to prevent low oil pressure during engine start up and to provide a filter to prevent any debris from entering the reservoir 16. In one embodiment, the restrictor 20 allows the reservoir 16 to fill up during a period of one minute after engine start up. A mist nozzle 22 is fitted into the bottom of the reservoir 16 so that oil will drain from the reservoir 16 back into the primary supply during engine shut down. The mist nozzle 22 is positioned to draw oil from the bottom of the reservoir 16 during all intended attitudes of the prop rotor gear box 8 and is located to aim oil mist at critical areas for lubrication so that oil mist will condense on these critical areas as the first component contacted by the oil mist. The oil is dispersed as a mist from the mist nozzle 22 and fills the entire interspace 24 of the gear box 8, producing an oil rich atmosphere. The gears and bearings of the gear box 8 move air through them, causing the gear box components to be lubricated as they move the oil mist inside gear box 8. The misting nozzle 22 produces a mist under the action of air supplied through a case passage 26 having engine air bleed 28 as the air source. Of course, other suitable air sources could be supplied to the misting nozzle 22 to provide suitable oil mist. As an example, auxiliary compressors on board the aircraft or special compressors added to the aircraft could be used to provide a suitable air source. The introduction of engine air bleed 28 may be manually controlled by the pilot of the aircraft upon receiving indication of low pressure in the primary lubricating system, or the air source after may be automatically activated upon predetermined drop of oil pressure in the primary system. FIGURE 5 illustrates a misting nozzle 22 of the emergency mist system 10 of the present invention. The misting nozzle 22 is an air atomizing nozzle operated when air is applied to air inlet 30 which passes to air cap 32 and out the air annulus 34. Air passing out the annulus 34 creates a low pressure region at the opening 36 of the oil feed line 38, drawing oil from the reservoir 16 (not shown) and the oil feed line 38 where it is atomized by the air flow passing through the air annulus 34. As a result, an oil mist 40 of a solid conical pattern of included angle of approximately 30° is provided for fogging the interior of an equipment casing. The size of oil droplets in the mist is in the range of 0.5 to 10 microns in diameter. A final nozzle filter 42 is sized to filter particles in the reservoir 16 from reaching the orifice 36. The design of the misting nozzle 22 is important to the operation of the emergency mist system 10. The air annulus 34 is sized small enough to maintain low air flow of approximately 0.05 lb./min. The misting nozzle operates at 7 p.s.i.g., a relatively low pressure. The orifice 36 of the oil feed 38 is sized to provide 25 inches 3 /hour of oil flow under nominal operating conditions of the mist system 10. The oil flow rate will vary with the oil inlet 18 head. The oil flow rate of misting nozzle 22 varies from 10 to 40 inches 3 /hour while the inlet head varies from -2.0 to +10.0 inches of oil in one embodiment of the system 10. While the present invention has been described with respect to a specific embodiment thereof, various changes and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes and modifications as fall within the scope of the appended claims.

Claims: AMENDED CLAIMS [received by the International Bureau on 12 March 1991 (12.03.91); original claims 2-5 cancelled ; original claims 1, 6-10 replaced by amended claims 1, 3-8 new claims 2, 9-25 added (6 pages)] 1. An emergency mist lubrication system for lubricating moving components housed within a casing, upon a drop in oil pressure in a primary lubrication system for lubricating the moving components, comprising: an oil reservoir for holding a supply of lubricating oil; means for filling said oil reservoir from the primary lubrication system; means for metering the flow of oil from the primary lubrication system to said oil reservoir such that the primary lubrication system does not experience pressure drop during start¬ up; and an oil mist nozzle having an oil passageway formed therethrough for receiving oil from said oil reservoir at one end and discharging an oil mist at an orifice formed at the opposite end, said oil mist nozzle having an air passageway open at said opposite end of said oil mist nozzle and having at said one end a normally closed connection to a source of air, such that when said oil mist nozzle is activated by opening said air passageway connection to the source of air, an oil mist is dispersed from said oil mist nozzle creating an oil rich atmosphere to lubricate the moving components in the casing. 2. The emergency mist lubrication system of Claim 1 wherein said means for metering the flow of oil from the primary lubrication system to said oil reservoir comprises a restrictor. 3. The emergency mist lubrication system of Claim 1 wherein said source of air is aircraft engine bleed air. 4. The emergency mist lubrication system of Claim 1 wherein said source of air is an auxiliary air compressor. 5. The emergency mist lubrication system of Claim 1 wherein said air passageway at said opposite end of said oil mist nozzle is an annulus surrounding said orifice of said oil mist nozzle. 15 9. An emergency mist lubrication system for lubricating moving components housed within a casing upon a drop in oil pressure in a primary lubrication system for lubricating the moving components, comprising: an oil reservoir for holding a supply of lubricating oil; means for filling said oil reservoir from the primary lubrication system; and an oil mist nozzle positioned at the bottom of said oil reservoir and having an oil passageway formed therethrough for receiving, at one end of said oil mist nozzle, oil draining from said oil reservoir and for discharging oil into the casing at an orifice formed at the opposite end of said oil mist nozzle, said oil mist nozzle having an air passageway open at said opposite end and having at said one end a normally closed connection to a source of air, such that when said oil mist nozzle is activated by opening said air passageway connection to said source of air, an oil mist is dispersed from said orifice creating an oil rich atmosphere to lubricate the moving components in the casing. 10. The emergency mist lubrication system of Claim 9 further including means for metering the flow of oil from the primary lubrication system during the filling of said oil reservoir such that the primary lubrication system does not experience a pressure drop. 11. The emergency mist lubrication system of Claim 10 wherein said means for metering the flow of oil from the primary lubrication system to said oil reservoir comprises a restrictor. 12. The emergency mist lubrication system of Claim 9 wherein said source of air is aircraft engine bleed air. 13. The emergency mist lubrication system of Claim 9 wherein said source of air is an auxiliary air compressor. 17 18. An emergency mist lubrication system for lubricating moving components housed within a casing upon a drop in oil pressure in a primary lubrication system for lubricating the moving components, comprising: an oil reservoir for holding a supply of lubricating oil; means for filling said oil reservoir from the primary lubrication system; and an oil mist nozzle having an oil passageway formed therethrough and positioned for receiving, at one end of said oil mist nozzle, oil from said oil reservoir and for discharging an oil mist into the casing at an orifice formed at the opposite end of said oil mist nozzle, said oil mist nozzle having an air passageway open at said opposite end and forming an annulus surrounding said orifice and having at said one end a normally closed connection to a source of air such that when said oil mist nozzle is activated, by opening said air passageway to the source of air, an oil mist is dispersed from said orifice creating an oil rich atmosphere to lubricate the moving components in the casing. 19. The emergency mist lubrication system of Claim 18 further including means for metering the flow of oil from the primary lubrication system during the filling of said oil reservoir such that the primary lubrication system does not experience a pressure drop. 20. The emergency mist lubrication system of Claim 19 wherein said means for metering the flow of oil from the primary lubrication system to said oil reservoir comprises a restrictor. 21. The emergency mist lubrication system of Claim 18 wherein said source of air is aircraft engine bleed air. 22. The emergency mist lubrication system of Claim 18 wherein said source of air is an auxiliary air compressor.

Inventors: DUELLO CHARLES LEE, DUELLO, CHARLES, LEE
Applicants: BELL HELICOPTER TEXTRON INC, BELL HELICOPTER TEXTRON INC.
Application year: 1990
Main classification: F01M1
IPC codes: F01D25, F16N7, F16N29