Note: Descriptions are shown in the official language in which they were submitted.
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Il EMERGENCY OIL/MIST SYSTEM
1 The subject invention relates to an emergency oil/mist
2 il system embodied in the main lubrication system for a bearing
3 ,l or gear box assembly of a gas turbine engine, and more parti-
4 ¦l~ cularly, to an emergency lubrication supply system for
f, providing a pressurized spray of lubricant so as to create
6 ¦~ extremely small droplets of a uniform distribution of oil on
7 ¦I the bearing for a limited period of time after failure of
8 ¦I the main lubrication supply system.
9 ¦¦ In gas turbine engines, as employed in high speed air-
10 ¦ oraft, the rotational shafts are journalled within bearing
11 ~ b~xes for rotation with respect to the engine frame members,
12 I and thus the bearings must be continually supplied with a
13 stream of lubricant. Generally, the main lubrication supply
14 I system includes a large reservoir of lubricant, and pump means
15 l are provided for distributing the lubricant through conduits
16 ¦ to the various bearings and gear box assemblies. The latter
17 are usually housed wlthin enclosed sumps such that the oil
18 j collected at the bottom of each sump is returned to the main
19 reservoir by scavenging devices, after which the lubricant
20 ¦ is again pumped in a continuous circuit back to the bearings
21 ~ or gea~ box assemblies. As is readily apparent, it is of
1 22 ~ extreme importance that the movable bearings or gear box
23 ¦ assemblies are aontinuously lubricated in order to prevent
24 premature failure by seiaing of the relatively mo~able parts. f
The v~rious components of the main lubrication supply system,
26 because of their size, are generally located external to the
27 engine ca ing ~here they are susceptible to damage, a~ 1n
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1 l, the case of a gas turbine engine as embodied in a military
2 ~l aircraft where the exposed components of the main lubrica-
3 '~ tion supply system are vulnerable to enemy fire. As is
4 i readily apparent, in the case of a rupture or puncture in
'I the oil lines or components in the main lubrication supply
6 ~~ system, the oil pressure and flow to the individual bearings
7 ~l or gear box assemblies will be quickly interrupted, and con-
8 ~, tinued operation o~ the gas turbine engine will rapidly
9 11 result in seizure of the bearings and/or gear box assemblies,
11 resulting in engine failure.
11 ¦ Heretofore in order that the gas turbine engine and the
12 ¦ aixcraft may continue to safely operate for a limited period
13 ~ of time after rupture or puncture of a component in the main
14 I lu~rication supply system, an emergency oil reservoir has been ¦
suggested for providing lubricant to a lubricated part for a
16 limited duration after-failure of the main lubrication supply
17 ~ system. The inclusion of the emergency oil reservoir is of ,,
18 critical importance particularly for military aircraft opera-
19 ting under combat conditions, and generally it has been
suggested that a plurality of emergency oil reservoirs be
21 strategically located throughout the aircraft gas turbine
22 ¦ engine in the vicinity of the bearings and gear box assemblies.j
23 I Generally each e~ergency oil reservoir is filled from the main I
24 oil supply system and may include either a gravity feed drain
25 ~ or an air pressure means for supplying a stream of oil to
26 the bearings, with the supply of oil from each emergency
27 ¦ re~en~oLr e~ng generally closed off by a series of check
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1 valves during normal operation. In the event of a loss of
2 l oil pressure or supply, manual or automatic actuation of the
3 1 check valves is required to open the supply of emergency oil.
4 ¦¦ The disadvantage of such an emergency supply system is that
~I closing off of the emergency oil reservoirs during normal
6 ~i eng~ne operation results in oil stagnation which gradually
7 !l leads to h~at degradation of the oil, and the gravity feed
8 ~ system of most conventional emergency oil supply systems may
9 ~I not provide a sufficient stream of air to adequately lubricate i
¦ the contacting surfaces of the lubricated parts and does not
11 ~ supply a cooling air flow to the lubricated parts.
12 ~t has also been known to provide an emergency lubrica-
13 . t~on supply system.inlcuding an oil reservoir in substantial
14 .p~oximity to the.lubricated parb, with conduit means exten-
ding fxom the emergency reservoir having an outlet located
16 aa jacent the bearing to be lubricated. Pressurized air flow
17 is continuously provided over the emergency reservoir outlet
18 ` means for creating a suction therein for drawing lubricant
19 through the conduit both during normal operation, and during
emergency operation when the main oil source has been disabled.
21 Accordingly, with this emergency lubrication supply system,
22 lubricant within the.emergenay reservoir is continually being
23 depleted during normal operation of the aircraft engine.
24 ~ ¦ ~ccordingly, it i:s an object of the subject invention
¦ to provide a new and improved emergency oil supply system for
26 ¦ provLding, for a limited duration after failure of the main
2 7 lub~ lca~i n supply zyutez, a ~ e ssurized spray of lubr i-ant
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1 `/ mist to the bearing in the form of small droplets of a uniform
2 , distribution of oil on the bearing for preventing seizure of
3 ,I the relatively movable parts, thereby precluding catastrophic
4 1, engine failure.
1l It is a further object of the subject invention to
6 , provide an emergency oil supply system wherein the emergency
7 1ll oil reservoir is disposed in the circuit extending between
8 il ,the main lubrication supply and the bearing, such that the
9 ¦i oil within the emergency reservoir is continually recircula-
ili ted, and thus is not susceptible to becoming stagnant.
11 I It is still a further object of the subject invention to
12 ~ provide an emergency oil supply system wherein the oil is
13 ¦ aspirated from an emergency oil reservoir and is sprayed under
14 ~I high,pressure in order to form extremely small droplets of oil
~hich are unifo~mly distributed over the bearing, thereby
16 , expanding the period of time during which the emergency oil
17 system is operative.
18 It is another object of the subject invention to provide
19 an emergency oil supply system which is fully operative fol-
20 I lo~ng failure o~ the main lubrication supply system.
21 The above and other objects and advantages of the inven-
22 tion ar,e ac,hieved by the subject emergency oil/mist system
23 embodied-in the main,lubrication system of an aircraft gas
24 ¦ turbine engine and including an auxiliary reservoir which is
25 ll operatively conneated in the conduit means extending between
26 ¦~ the main source of pressurized lubricant and the nozzle for
27 applying oil onto a bearing or gear box assembly. ~he noszle
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1 is capable of either directing a stream of oil to the bearing
2 ` (when the main lubrication system is fully operative) or a
3 ~ mist of lubricant comprised of lubricant aspirated from the
4 fl emergency reservoir and high pressure air (when the main
(~ supply lubrication supply system has failed). A control
6 ~I piston valve interconnects the emergency reservoir to an
7 ~ atmospheric vent, and also connects a source of pressurized
8 ~¦ a~r to the air aspirator nozzle. Upon failure of the main
9 ~l lubrication system, the control valve is actuated such that
~ pressurized air is provided to the nozzle and, by air aspir-
~ ation, withdraws oil remaining in the emergency reservoir.
12 ! The ~alve also connects the emergency reservoir to the
13 ~ atmospheric vent thereby providing an effective control on
14 ¦ the amount of oil aspirated from the emergency reservoir. By
l this arrangement, the emergency oil/mist lubrication system
16 l prGvides an ultrasonic impingement of droplets of oil as it
17 leaves the nozzle, thereby creating extremely small droplets
18 ¦ of uniform distribution of oil on the bearing or gear box
19 assembly. Actuation of the control valve may be effected by
the pressure balance piston type or solenoid valves triggered
21 by low oil pressure in the main supply system or by excessive
22 bearing or gear box temperatures.
23 Further objects and advantages of the invention will
24 become apparent from a reading of the following detailed des-
~ cription of a preferred embodiment of the subject invention
26 ¦ taken in conjunction with the drawings in which:
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1 ~ FIG. 1 is a schematic view of the emergency oil/mist
2 , lubrication system of the subject invention when the main
3 1 lubrication system is fully operational;
4 , FIG. 2 is a schematic illustration of the control valve
~ of the subject invention ~hen the main lubrication supply
6 I s~stem is fully operational as-in FIG. l;
7 I FIG. 3 is a schematic illustration of the subject
8 lii, e~ergency oil-~mist lubrication system when the main supply
g ll system is disabled and the emergency lubrication supply
I system is fully operational~ and
11 ¦ FIG. 4 is a schematic illustration of the control valve
12 ~ of the subject invention during the time when the emergency
13 lu~rication supply system is operational as in FIG. 3.
14 Referring to FIG5. 1 and 2, the lubrication supply
lS system of the subject invention is generally designated by
16 the numeral 10 and is operative to provide lubricant to a
17 . bearing 12 which supports rotating shaft 14 of, for example,
18 a gas turbine engine of an aircraft. The bearing 12 may be
19 encased within a bearing cavity (.not shown) having an oil
scavenging line for recirculating lubricant provided to the
21 bearing 12 to the ma~in reservoir (.not shown~ for the lubrica-
22 t~on supply system 10. Although the lubrication supply system
23 of the subject invention is described in relation to an engine
24 bearing, it is under~tood to have substantially broader appli-
25 - cation and may be applied to any engine part requiring
26 lubricat~ n.
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l . The lubrication supply system 10 includes a main source
1 of pressurized fluid, such as from a main supply reservoir
3 i~ (not shovn) and suitable pump means (not shown) which are
4 1 indicated in FIG. l as "oil flow" to the conduit 20 which
~ extends to an air aspirating nozzle 22. The latter is loca-
6 1, ted in proximity to the bearing 12 for providing a stream 26
7 I o~ oil to the bearing 12. The air aspirating nozzle 22 is of
8 I generally tubular construction and includes two elongated
9 passageways 28 and 30 lèading to an enlarged outlet 32.
l Conduit 20 is connected to passageway 28 and during normal
ll . operation of the lubrication supply system 10, pressurized
12 ~ oil is passed through the conduit 20, through passageway 28
13 ¦ of nozzle 22, and onto the bearing 12.
14 ~ ~rhe emergency oil/mist lubrication system of the sub-
¦ ject invention is embodied in and forms a portion of the
16 ¦ lubrication supply system 10 and includes an emergency oil
17 ¦ reservoir 40 that is disposéd in series in the conduit 20.
18 ~ kccordingly, during normal operation of the lubrication
19 ¦ supply system 10, pressurized lubricant provided through the
¦ conduit 2;0 is likewise passed through the emergency oil
21 ¦ reservoir 40 and then to the passageway 28 of the air aspira-
22 ¦ ting noz~le 22, and is sprayed a~ stream 26 onto the bearing
23 l 12. Accordingly, the lubricant within the emergency oil
24 ¦ - reservoir 40 is constantly being replenished and depleted,
25 ¦ thereby precluding. stagnation of lubricant within reservoir
26 ¦ 40 aue to heat developed within the engine. Preferably,
27 emergency oil reservoir 40 is located in proximity to the
28 : bea ing 12, and is of a zize in order to hold a q:antity of
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1 , approximately 100 cubic centimeters of oil whereby the
2 ' emergency oil reservoir 40 is of sufficiently small size to
3 ' be readily positioned within the confines of the engine
4 ,, housing. The emergency oil/mist lubrication system also
'', includes an emergency control valve means 50 (see FIGS. 1 and
6 ~ 2) which may be of the piston valve type. Piston ~alve 50
7 ~I may be of the pressure balance piston type and includes an
8 1! outer cylindrical housing 52 in which piston 54 is slidably
9 ~ movable, One end 56 of the cylindrical housing 52 includes
an opening 58 which is in communication via conduit 21 with
11 the source of pressurized o~l from the main supply reservoir.
12 Opening 58 leads into th~ inner chamber of the cylinder and
13 1~ be~rs against the let hand end 60 of piston 54. The opposite
14 end of piston 54 includes an extension 62 having a single
I through aperture 64. Cylindrical portion 52 of the piston
16 I valve includes two through passageways 70 and 72, as well as
17 ¦ an a~perture 53 interconnecting passageway 70 with the chamber
18 on the right hand end of piston 54.
19 ~ During normal operatïon of the lubrication supply system
¦ 10, the pressurized oil flow from the main supply source bears
21 ¦ against the end 60 of the piston æuch that the piston is
22 seated as æho~n in FIG. 2 and the piston extension 62 effec-
23 t~vely closes off the passageways 70 and 72. At such time,
24 the force of the pressurized oiI against the end 60 of piston
54 i6 greater than the force o the pressurized air applied to
26 t~e right hand end of piston 54 through aperture 53. The
27 ¦ upper end 70A of passageway 70 is connected to a source of
28 presSuriz d air vie suppiy conduit 84, while the lo~er por-
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1 ~ tion 70B of passageway 70 is connected via a conduit 86 to
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2 l the elongated passageway 30 in the air aspirating nozzle 22.
3 The upper portion 72A of passageway 72 is connected via a
4 j, conduit 80 to the atmosphere, while the lower portion 72B .
'~ is connected via line 82 to the emergency oil reservoir 40.
6 ~1 As indicated above, during normal operation of the main
7 ~ lubrication/supply system lO, the extension 62 of the piston
8 ¦ 54 is disposed as shown in FIG. 2.so as to block passageways
9 ¦ 70 and 72, thereby preventing the emergency oil reservoir
~ from being vented to the atmosphere via conduits 80 and 82,
11 and also preventing the source of pressurized air flow from
.12 ¦ condu~t 84 from being provided to the air aspirating nozzle
13 1 22.
14 In the event of an emergency, such as a puncture or
rupture in the main oil reservoir or the pump means for pres- I
16 surizing the main source of lubricant flaw, pressure and flow
17 in the c.onduit 20 will rapidly decrease. The possibility of
18~ a rupture-or puncture in any component of.the main oil supply
19 .system is of particular conaern to military aircra~t flying
j combat missions where the oil supply components, which are
21 generally situated external to the engine casing, are more
22 vulnerable to damage from enemy fire. Without lubrication,
23 . it i5 apparent that the high speed rotating shaft 14 would
24- quickly seize, or the bearing 12 will become damaged thereby
25 ~ possibly resulting.in catastrophic engine failure. The
26 emergency oil/mist supply sytem of the subject invention is 1.
27 designed to provide a limLted period during which an emergency
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1 ultrasonic spray of high pressure lubrlcant is provided to
2 . the bearing 12, as well as pressurized air flow capable of
3 ~ cooling the bearing 12 during the limited emergency period of
4 ~. the pressurized lubrication spray.
" During an emergency condition, the pressurized flow
6 il provided to the opening 58 of valve 50 rapidly decreases,
7 ~l. thereby enabling the pressure balance piston 54 to be actuated
8 il toward the left, to the position as.illustrated in FIG. 4, by
9 ~¦ virtue of the pressurized ~low provided through aperture 53.
~¦ Alternatively, actuation of piston valve 50 may be solenoid
11 ~ controlled in response to the rapid decrease in pressure of
12 ~ the main oil supply or a temperature sensor may be provided in
13 - ¦- the vicinity of the bearing.12 and may provide a triggering
14 ! signal to a suitable solenoid operated valve for actuating
~ . piston 54 to the position as shown in FIG~ 4. At such time,
16 as shown in.FIGS. 3 and 4, the emergency oil/mist lubrication
17 system i8 operational, and the passageways 70 and 72 are
18 opened, ~ith aperture 64 being aligned with passageway 70.
19 ¦ At such t~me, the emergency oil reservoir 40 is vented to
I the atmosphere via conduits 82 and 80 which extend through
2I passage~ay 72. In addition, pressurized air flow is provided
22 ¦ via conduit 84, through.passageway 70 to aperture 53 and also
23 : ¦ to conduit 86 leading to the passageway 30 in the air aspir-
24 ating nozzle 22. The high pressurized air flowing through
~ t~he passageway 30 emerges into the enlarged outlet 32 thereby
26 I .effectively creating a partial vacuum in the nozzle 22 for
27 ~ aspirating lubricant from the emergency oil reservoir 40 via
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l conduit 20 and passageway 28. The fact that the emergency
2 oil reservoir 40 is vented to the atmosphere assures that the
3 il withdrawal of the emergency oil from the reservoir 40 is at
4 ' a controlled rate in order to prolong emergency lubrication
, to the bearing 12 for a sufficient period of time to enable
6 i the pilot of the aircraft to make the necessary emergency
7 1I maneuvers. The intermixture of the pressurized air and the
8 ~l oil aspirated from the emergency oil reservoir 40 results in
g !l a fine mist of small droplets of oil 90 (see FIG. 3) provided
lO ~I to the bearing 12. The emergency lubrication mist 90 auto-
matically continues to flow and impinge on the contacting
12 ¦I bearing surfaces 12 at a slow metered rate until the emergency
13 ~¦ o~l reservoir 40 is emptied. It is estimated that with an
14 ~ emergency oil reservoir 40 having a capacity of approximately
lS ~ lO0 cubic centimeteræ of oil, the emergency oil/mist system
16 ~ill be capable of operating for approx~matèly one-half of
17 ll an hour during which time high pressurized mist 90 provided
18 ~¦ to the bearing 12 would be sufficient lubrication for continued
l9 ll operation of the bearing 12. In addition, the pressurized air
is effective to aid ln cooling of the bearing.
21 Accordingly, there is provided a new and improved ',
22 e~ergency oil~mist lubrication system which is formed as an
23 ~ integra~l part of the main lubrication system of a gas turbine
24 ¦ engine and is designed to function as a mist lubricant gener-
¦ ato~ in the event of failure of the main lubrication system.
26 .~ The e~ergency oil~mist lubrication system may be employed for
27 ~¦ ~earings or gear box assemblies of a gas turbine engine, and
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1 ~ the auxiliary or emergency reservoir has sufficient capacity
2 `~ to provide lubrication to the bearing assem~ly for approxi-
3 ~ mately thirty minutes following failure of the main lubrica-
4 ' tion system. The subject system produces an ultrasonic
impingement of the oil as it leaves the air aspirating
6 1I nozzle 22 thereby creating extremely small droplets of
7 ¦~ uniform distribution of lubricant over the bearing. In
8 ~l addition, the flow of pressurized air to the bearing is
9 j effecti~e in cooling the bearing during the emergency
~l operation. The emergency oil/mist supply sytem can be
11 il actuated by a pressure balance piston-type valve or a suit-
12 ¦ able solenoid valve triggered by low oil pressure in the main
13 ~ supply system, or a solenoid valve which is triggered by suit-
14 able sensors for sensing excessive bearing temperatures.
~hile the invention has been described with respect to
16 a specific embodiment thereof, it is readily apparent that
17 ~ various modifications, alterations, or the like may be appa-
18 rent to those skilled i~ the art, and thus the invention is
19 not to be limited by the illustrative embodiment, ~ut by the
spirit and scope of the fo1iowing appended claims.
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