Field

The present disclosure relates generally to lubrication systems . More particularly, the present disclosure relates to an emergency lubrication system.

Background

Lubrication systems, such as those used in aircraft gas turbine engines, supply lubricant to bearings, gears and other engine components that require lubrication. The lubricant, typically oil, cools the components and protects them from wear. A typical oil lubrication system includes conventional components such as an oil tank, pump, filter and oil supply conduits.

If one of the lubrication system components fails malfunctions or sustains damage, the oilssupply to the lubricated component may be disrupted, resulting in potentially irreparable damage to the component and undesirable corollary consequences. For example, if an engine oil pump fails or a supply conduit develops a severe leak, the resulting loss of oil pressure could disable the engine by causing overheating and/or seizure of the bearings that support the engine rotor. An aircraft engine that becomes disabled in flight is obviously a concern, especially for a single engine military aircraft operating in hostile airspace.

It is known to accommodate the possibility of a failure in the oil system by configuring the system so that it continues to supply oil to the lubricated components for a limited time thereby enabling continued temporary operation of the engine. Such a system allows the aircraft crew time to safely shut down the engine or to take other appropriate actions to safeguard the aircraft and its occupants. In a military aircraft, such a system can provide the crew with valuable additional time to return to friendly airspace.

Summary

According to various embodiments, a lubrication system is disclosed. This may be a lubrication oil system of an aircraft such as a helicopter and/or the lubrication of an engine system component and/or the helicopter rotor assembly. A redundant lubricating system may include a reserve lubricating oil tank coupled to a distal portion of a lubricating oil main supply line, at least one supply line coupled to the reserve lubricating oil tank, wherein the supply line couples the reserve lubricating oil tank to at least one engine component, such as a bearing assembly. The reserve lubricating oil tank may be configured to cycle lubricating oil from the lubricating oil main supply line through the reserve lubricating oil tank to the supply line. The lubricating oil may be provided to the engine components, during normal operation based on an oil pressure of the lubricating oil main supply line. The system may include a check valve interposed between the reserve lubricating oil tank and a compressed air source. The system may include a lubricating oil pressure sensor associated with the main supply line. The lubricating oil pressure sensor may be configured to sense the oil pressure of the lubricating oil main supply line and/or a location associated with the lubricating oil main supply line. A check valve may permit compressed air from a compressed air source to be delivered to the reserve tank in response to the lubricating oil pressure sensor reading. A one way valve may be interposed between the reserve lubricating oil tank and the lubricating oil main supply line.

Brief Description of the Drawings

The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements.

FIG. 1 illustrates a representative flow diagram of lubricating oil flow in response to normal operating conditions in accordance with various embodiments;

FIG. 2 illustrates a representative flow diagram of lubricating oil flow in response to emergency conditions in accordance with various embodiments; and

FIG. 3 illustrates a process for providing lubricating oil according to various embodiments.

Detailed Description

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration and their best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the inventions, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the spirit and scope of the inventions. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact.

According to various embodiments and with reference to Figure 1, a representative lubricating oil main supply line 115 is depicted. This oil main supply line 1 15 may be for a vehicle, such as an aircraft. For instance, main supply line 1 15 may supply lubricating oil to a helicopter engine or aircraft engine. Oil supply line 115 delivers oil to elements of a gas turbine engine, such as bearings assemblies generally designated as 1 and 3, and to a reserve tank 120. Bearing assemblies, in general, reduce friction between a rotating engine element and stationary engine components. Oil pump 130, driven by the engine (not shown), pumps oil from a sump/oil supply reservoir 125 through main oil supply line 115 to effect lubrication of the engine system components of the gas turbine engine (e.g. bearings assemblies 1 , 3 and roller bearing 10, and/or the like).

Reserve tank 120 may be empty (and/or less than full) of oil on engine start-up. Reserve tank 120 may be located towards and/or at the distal end of the path of lubricating oil main supply line 1 15. As lubricating oil is delivered through main supply line 1 1 under pressure, reserve tank 120 may gradually fill with lubricating oil. Stated another way, as lubricating oil is delivered through main supply line 1 15 under pressure, the amount of lubricating oil in reserve tank 120 tends to increase. This filling of reserve tank 120 may occur in concert with lubricating oil being delivered to bearings assemblies 1, 3. As reserve tank 120 fills and pressure within reserve tank 120 increases, oil may be delivered from reserve tank 120 through supply lines 135 and 145 to bearings assemblies 1, 3 respectively. This delivery circulates the lubricating oil from reserve tank 120. Thus, lubricating oil is not trapped in reserve tank 120 until needed. Reserve oil is consistently being circulated via supply lines 135 and 145. Stated another way, this system continuously circulates oil through and from a reserve tank. "Continuously" in this context may refer exchanging/cycling lubricating oil in the reserve tank 120 without trapping the lubricating oil in the reserve tank 120 for an extended period of time. Trapping oil in a reserve tank may degrade the quality of the oil, lead to build up in lines, and may be otherwise undesirable. Additionally, no additional force application, such as through compressed air or additional pump is used to circulate oil from reserve tank 120 during normal operating conditions. Normal operating conditions as used herein may be when main supply line 1 15 comprises adequate oil pressure to deliver lubricating oil to the system. During normal operating conditions, an air check value 150 coupled to a compressed air supply 155 may be in a closed position and/or restrict compressed air in the compressed air supply 155 from entering the reserve tank 120. A valve, such as a one-way valve 160, may be located between a distal end of main supply line 1 15 and reserve lubricating oil tank 120, such that lubricating oil delivered by main supply line 1 15 may not exit reserve tank 120 via main supply line 1 15. A sensor, such as oil pressure sensor 170, may be located along and/or coupled to main supply line 1 15 to measure and/or determine that the oil pressure in main supply line 1 15 is above a predetermined normal operation oil pressure threshold. In the event that the main lubricating oil supply line 1 1 5. pump 130 or other elements of the normal lubricating system should be damaged or fail for any reason, the various bearings, such as bearing assemblies 1 , 3 of the engine would be starved for oil and catastrophic failure of the engine may occur. This is undesirable.

Integrated emergency lubrication system, generally designated as system 200 in FIG.

2, is designed to cope with such a situation and sustain substantially uninterrupted and/or uninterrupted lubrication of bearing assemblies 1, 3 and continued safe operation of the engine for a predetermined amount of operational time and at a predetermined rate of power. This may occur during emergency oil conditions (e.g. in response to the oil pressure of main supply line 1 15 dropping below the normal operation oil pressure threshold). The predetermined amount of time may be any suitable amount of time. According to various embodiments, the predetermined amount of time is between about 15 and 180 seconds, between about 4 and 8 minutes, and between about 1 and 9 minutes. In various embodiments, the predetermined amount of operational time for uninterrupted lubrication of emergency oil during emergency conditions is six minutes. The predetermined rate of power may be any suitable rate of power. According to various embodiments, the predetermined rate of power is between about 50-90% normal operational power, between about 60-85% normal operational power, and between about 70-80%) normal operational power. According to various embodiments, the predetermined rate of power is full normal operational power and/or between about 60-100%) normal operational power. In various embodiments, the predetermined rate of power is about 75% normal operational power. During that time, (e.g. emergency oil conditions), the engine's operator can reduce power to the engine and take other appropriate emergency measures.

According to various embodiments and with reference to FIG. 2, based on a measured loss of oil pressure in main lubricating oil supply line 1 15, such as via a detection by sensor 170, check valve 1 50 may open. Thus, compressed air from compressed air supply 155 may be delivered via compressed air supply line 180 to reserve tank 120. FIG. 2 depicts loss of lubricating oil flow through main lubricating oil supply line 1 15. This loss of lubricating oil delivery is depicted by an "X" over the lubricating oil paths from main supply line 1 15 to bearings assemblies 1 and 3, roller bearing 10 and through lubricating oil supply line 1 15 itself. The loss of one or more path of lubricating oil delivery may be associated with an emergency oil condition. During loss of lubricating oil delivery, oil is not supplied to bearings assemblies 1 and 3, roller bearing 10 and/or a decreased amount of oil is being supplied to bearings assemblies 1 and 3, roller bearing 10 via the main oil supply line.

Compressed air from compressed air supply 155 may provide the force/pressure to deliver lubricating oil in reserve tank 120 to elements of engine, such as bearings assemblies 1 and 3. According to various embodiments, the pressure of the lubricating oil supplied is less than about 60 pound-force per square inch gauge (PSIG) (4.136854368 bar). In this way, buffer air may pressurize the reserve tank 120. In response to reaching an emergency oil operational pressure level, lubricating oil may be delivered through supply lines 135 and 145 to bearing assemblies 1 and 3. In emergency oil conditions, lubricating oil may be delivered from reserve tank 120 to bearing assemblies 1 and 3 in a jet or mist. Thus, compressed air and/or buffer air may be used during emergency conditions but jet and/or mist delivery is not intended for long term use in normal operating conditions. Stated another way, compressed air is not used to deliver lubricating oil from the reserve tank 120 during normal operating conditions. In this way, inefficient use of compressed/buffer air is reduced. Moreover, in this embodiment, a piston is not utilized to deliver emergency oil to various engine components.

The size of the reserve tank 120 may affect the length of time lubricating oil is applied to engine elements during an emergency oil condition. Reserve tank 120 may be sized to accommodate any desired length of time to provide lubricating oil during emergency conditions. Lubricating oil may be delivered to bearing assemblies 1 and 3 substantially simultaneously. For instance, a single port in reserve tank 120 may split and form an inlet to each supply line 135 and supply line 145. According to various embodiments, supply line 135 and supply line 145 may be individually coupled to reserve tank 120, such as by two distinct couplings. The volume of reserve tank 120 and/or desired rate of flow may determine the pressure of the compressed air supplied. Also, the gauge and length of travel of supply line 135 and/or supply line 145 may determine the pressure of the compressed air supplied. The pressure of the air supplied may be any desired pressure. According to various embodiments, the pressure of the compressed air is about 50 pounds per square inch (about 3.447 x 10 ⁵ N/m ² ) absolute (PSIA) air. This pressure may be selected based on the length of time and volume of lubricating oil desired to be delivered to engine elements. Similarly, the diameter/gauge and/ length of supply lines 135 and 145 may be sized to accommodate a desired pressure, length of time to deliver oil, and/or rate of power. Determining a rate of compressed air delivered by the compressed air source 155 may be based on at least one of a length of the supply line 135, 145, a gauge of a portion of the supply line 135, 145, a nozzle selected for the distal end of the supply line, and/or a volume of the reserve tank 120. Moreover, a distal nozzle of supply lines 135 and 145 feeding lubricating oil to engine elements, such as bearing assemblies 1 and 3, may be sized to accommodate a desired pressure, length of time to deliver oil, and/or rate of power.

In response to oil pressure in main oil supply line 1 15 being restored to normal operating conditions (over the normal operating condition threshold), reserve tank 120 may be refilled and the emergency oil system may be ready for utilization in an emergency condition. For instance, in response to normal operating conditions being restored, sensor 170 may detect normal oil pressure from oil supply 125. In response, sensor 170 may trigger check valve 150 to close and compressed air may be discontinued from being provided to reserve tank 120. Oil will continue to circulate through the system and through reserve tank 120, without additional force provided by the pressure accumulated through compressed air source 155. The system described herein may maintain operation for at least 30 minutes once main oil supply has been restored.

According to various embodiments and with reference to Figure 3, a method of managing oil supply is described. Oil is delivered through main supply line 1 15 under pressure to engine components, such as bearing assemblies 1 and 3 (Step 310). As reserve tank 120 is located at the distal end of main supply line 1 15, the volume of lubricating oil in reserve tank 120 increases in response to lubricating oil being introduced to/through main supply line 1 15 (Step 320). Reserve tank 120 may be empty or partially full on startup. Lubricating oil is delivered through supply lines 135 and 145 to engine components based on oil pressure of reserve tank 120 (Step 330). The oil pressure is measured at a location, such as in main supply line 1 15, engine elements, and/or delivery tracks from main supply line 1 15 (Step 340). A determination is made that oil pressure at a measurement location is at least one of more than or less than a threshold (Step 350). In response to the oil pressure is more than the threshold normal operations continue (Step 353). In response to the oil pressure of main supply line and/or at a measurement location being less than a normal operation threshold, compressed air is provided to reserve tank 120 from a compressed air source 155 through check valve 150 (Step 355, 360). Oil Pressure in reserve tank 120 increases (Step 370). The rate of flow of lubrication oil delivered through supply lines 135, 145 increases based on the oil pressure increase of reserve tank 120 (Step 380). Measurements are continued to determine if normal operating conditions are restored.

Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the inventions. The scope of the inventions is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." Moreover, where a phrase similar to "at least one of A, B, or C" is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

Systems, methods and apparatus are provided herein. In the detailed description herein, references to "one embodiment", "an embodiment", "various embodiments", etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.

Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. Different cross-hatching may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials. No claim element herein is to be construed under the provisions of 35 U.S.C. 1 12, sixth paragraph, unless the element is expressly recited using the phrase "means for." As used herein, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.