GB2144804A

GB2144804A - Turbomachine starter lubrication system

Info

Publication number: GB2144804A
Application number: GB08418570A
Authority: GB
Inventors: Frank Leo Oppenheimer; Anthony John Kasak
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1983-07-25
Filing date: 1984-07-20
Publication date: 1985-03-13
Also published as: IT1176439B; GB8418570D0; IT8421966A0

Abstract

A system for continuously lubricating the starter 2 of a turbomachine comprises a conduit 26 for delivering lubricant from the lubrication system of the turbomachine to the starter; a conduit 28 for transferring lubricant collected in the sump 24 of the starter to the sump of a gearbox 4 operatively connecting the starter and turbomachine, for subsequent return to the lubrication system of the turbomachine; and a conduit 27 for delivering pressurized air from the turbomachine to the starter to develop a flow of lubricant which varies in accordance with the operating conditions of the turbomachine, subject to limitation by a pressure relief valve (43, Fig. 2) associated with the starter. <IMAGE>

Description

SPECIFICATION System for lubricating the starter of a turbomachine Background of the invention The present invention relates generally to turbomachinery, and more particularly, to improvements in lubrication of the starter assembly associated therewith.

A variety of different mechanisms have been developed for starting various turbomachines. These mechanisms generally include a starter motor or device which is operatively connectable to the turbomachine through a communicating gearbox assembly. Rotation of the starter motor, through the communicating gearbox assembly, in turn causes rotation of the rotor of the turbomachine until such time as the turbomachine is capable of independent operation, whereupon operation of the starter motor is discontinued.

A variety of different prime movers may be used to operate such starter motors. For example, one popular type of starter mechanism is the pneumatically operated starter, which uses pressurized air or gas to operate the starter motor, and in turn, initiate operation of the turbomachine. The pressurized air or gas used to operate the starter motor may be supplied from an external source, or may be derived from another turbomachine in connection with multi-engine applications.

As in any application involving moving parts, proper lubrication of the various components of the turbomachine must be assured to maintain an efficient and durable system. Apart from the maintenance of adequate lubricant supplies, a variety of lubrication systems have been developed which attempt to enhance lubrication both during normal operating conditions, as well as during start-up and shut-down of the turbo machine. In this regard, improvements have also been attempted in connection with lubrication of the starter motor. Irrespective of this, as a result of a variety of practical considerations it has generally been found necessary to replenish starter lubricant supplies at relatively short operating intervals.Such service intervals, ofter on the order of one thousand hours, present a recurring need for maintenance, one which is generally undesirable and even unacceptable in connection with some unattended, remote location applications.

It is therefore a primary object of the present invention to develop an improved lubrication method system for a starter mechanism.

Accordingly, the lubrication system comprises a means for delivering lubricant from the lubrication system of the turbomachine to interior portions of the strater mechanism, and means for subsequently delivering lubricant received in the starter mechanism to the gearbox which connects the starter mechanism to the turbomachine. Also provided may be a means for delivering pressurized air to the interior of the starter mechanism, which pressurized air is again derived from the turbomachine.

In operation, in accordance with the proposed method, lubricant supplied from the lubrication system of the turbomachine is used to lubricate the starter mechanism, whereupon lubricant will collect in the sump of the starter mechanism. Pressurized air supplied to the starter mechanism may be used to produce a differential in pressure between the interior of the starter mechanism and the interior of the gearbox, thereby causing lubricant to flow from the starter mechanism to the gearbox. Since the gearbox of a turbomachine is generally provided with a scavenging system which is capable of recirculating lubricant from the gearbox to the lubrication system of the turbomachine, a continuous flow of lubricant is developed through the starter mechanism using lubricant supplied by the lubrication system of the turbomachine.This eliminates the need to separately service and/or replenish lubricant supplies within the starter mechanism, since such maintenance will be accomodated by the lubrication system of the turbomachine.

Further detail regarding a preferred embodiment of the present invention may be found in the following description, taken in conjunction with the following illustrations.

Brief description of the drawings Figure I is a side elevational view of a turbomachine and associated accessories.

Figure 2 is an enlarged, partial, side elevational view of the region II shown in Fig. 1, showing an exemplary starter mechanism which has been provided with the lubrication system of the present invention, and also showing the associated gearbox.

Figure 3 is an enlarged, partial, side elevational view similar to Fig. 2, portions of which have been broken away to show internal construction detail.

Figure 4 is an end view of the casing of the starter mechanism, showing the collector assembly and the flow-control baffles.

In the several views provided, like reference numerals denote similar structure.

Detailed description of the preferred embodiment Although specific forms of the invention have been selected for illustration in the drawings, and the following description is drawn in specific terms for the purpose of describing these forms of the invention, this description is not intended to limit the scope of the invention which is defined in the appended claims.

Figs. 1 and 2 generally illustrate a turbomachine 1 and a starter mechanism 2 which have been provided with a continuous lubrication system 3 in accordance with the present invention. In the embodiment illustrated, the starter 2 is operatively connected to the turbomachine 1 through a communicating gearbox 4, such as the accessory gearbox which is conventionally associated with many turbomachine designs.

For the purposes of discussion, the starter 2 selected for illustration in the drawings is a pneumatic type starter. With particular reference to Fig.

3, such starters generally include a main casing 5 having inlet and mounting apertures 6, 7, respectively, and a manifold 8 which overfits the inlet end 9 of the casing 5 as shown. A turbine shaft 10 is journaled for rotation within the inlet end 9 of the casing 5, and the outermost terminating end of the shaft 10 is provided with a turbine 11 including a rotor portion 12 attached to the end of the shaft 10 and a plurality of blades 13 radially disposed about the periphery of the rotor portion 12 as shown. It will be seen that the turbine 11 is fitted within the manifold 8 so that air or gas entering the area 14 will impinge upon the blades 13 of the turbine 11, for subsequent discharge through a series of exhaust ports 15 disposed about the casing 5 and between the manifold 8 and casing 5 as shown.It will be understood that when appropriately pressurized air or gas is applied to the inlet 6, rotation of the turbine 11 will result, in turn rotating the shaft 10.

The remaining end of the shaft 10 is operatively connected, through a reduction gear assembly 16 and clutch 17, to an output shaft 18 which is journaled for rotation within the mounting aperture 7 of the casing 5. The terminating end 19 of the shaft 18 extends into the gearbox 4 and engages a gear drive (not shown) associated with the gearbox 4 so that operation of the turbine 11 will, in turn, cause rotation of the rotor (not shown) of the turbomachine 1 in the conventional manner, upon selective activation of the clutch 17.

It will be understood that the foregoing description has been provided for illustrative purposes and only briefly describes the structure and operation of one type of starter mechanism. However, the present invention will also find applicability in connection with other configurations or types of starter mechanisms, as well as other turbomachines and turbomachine interfaces.

It will further be understood that the various rotating components previously described must be appropriately journaled for rotation, and appropriately supplied with lubricant to assure correct operation over an extended period of time. For example, the shaft 10 and shaft 18 previously described are journaled within the casing 5 by the bearings 20, 21, and it is therefore essential to assure correct supplies of lubricant to the bearings 20, 21, as well as to any other components of the starter mechanism 2 which may require lubrication to assure their correct operation. To accommodate this need, as well as the lubrication needs of the gearbox 4, both the starter 2 and the gearbox 4 are provided with sumps 24, 25 for receiving lubricant therein.

Generally, the gearbox 4 is provided with a scavenging system which provides communication between the sump 25 of the gearbox 4 and the lubrication system of the turbomachine 1, while a separate lubricant supply is maintained within the sump 24 of the starter 2. This has resulted in the need for frequent replenishment and/or servicing of starter lubricant supplies in the sump 24. To overcome this deficiency, and in accordance with the present invention, the lubrication system 3 provided is capable of continuously supplying lubricant to the starter 2, drawing this lubricant from the primary lubrication system associated with the turbomachine 1.

The lubrication system 3 illustrated generally comprises a series of conduits 26, 27, 28 associated with the starter 2. A first conduit 26 extends between the turbomachine 1 and the casing 5 of the starter 2 and is operatively associated with the lubrication system of the turbomachine 1 to serve as a means for supplying lubricant to the starter 2.

A second conduit 27 also extends between the turbomachine 1 and the casing 5 of the starter 2 and serves as a means for supplying pressurized air to the starter 2. This supply of pressurized air may be derived from the turbomachine 1 in a variety of ways.

For example, such pressurized air may be drawn from an accessory air pump associated with the turbomachine 1, if desired. However, such pressurized air is preferably drawn from the compressor stage of the turbomachine (compressor discharge pressure), since this pressure will vary in accordance with engine speed for purposes which will be more fully described below. A third conduit 28 extends between the sump 24 of the starter 2 and the sump 25 of the gearbox 4, and serves as a means for transferring lubricant from sump to sump in accordance with the present invention.

The conduits 26, 27 preferably each communicate with the starter 2 through an orifice 29, 30 of specified construction to regulate the entry of lubricant and air into the interior portions 31 of the starter 2. In the preferred embodiment, the orifice 29 associated with the lubricant supplying conduit 26 preferably has a diameter of approximately 0.030 inches and preferably develops a flow of lubricant on the order of 0.2 gpm at the system's normal rated speed. The orifice 30 associated with the air supplying conduit 27 preferably has a diameter on the order 0.060 inches and preferably develops an air flow on the order of 0.1 Ib/min at the system's normal rated speed.

A first end 32 of the conduit 28 is operatively associated with a collector 33 located within the casing 5 of the starter 2 as shown. The collector 33 generally comprises a collector plate 34 which is essentially horizonally disposed along upper (fluid surface shown at rest in Fig. 3) portions of the sump 24, and a standpipe 35 attached to and communicating between an aperture 36 in the collector plate 34 and an aperture 37 in the casing 5 of the starter 2. The terminating end 38 of the standpipe 35 is connected to the end 32 of the conduit 28, the remaining end 39 of the conduit 28 being connected to a fitting 40 associated with the gearbox 4. A screen 41 is preferably provided at the fitting 40 to filter lubricant transferred from the sump 24 of the starter 2 to the sump 25 of the gearbox 4, to isolate wear particles for example.

In operation, lubricant is delivered from the lubrication system of the turbomachine 1 (at varying temperature and pressure) to the interior portions 31 of the starter 2 via the conduit 26 and through the orifice 29. This lubricant will be distributed throughout the interior portions 31 of the starter 2, assisted by rotation of the gearing 16, impinging upon the bearings 20, 21, the reduction gearing 16, and other components as necessary. The flow of lubricant through the interior portions 31 of the starter 2 may be enhanced by providing a series of baffles 23 which are associated with and radially disposed about the casing 5 of the starter 2, as is best illustrated with reference to Fig. 4 of the drawings. Lubricant (with entrained air) will then collect within the sump 24 of the starter 2 until the fluid collected in the sump 24 reaches the level of the collector plate 34.The collector 33 will then draw fluid from the uppermost levels of the sump 24 for transfer through the conduit 28, along with excess air, to the sump 25 of the gearbox 4. The scavenging system of the turbomachine will then serve to return recovered lubricant to the lubrication system of the turbomachine 1 after separating air from the lubricant in the conventional manner.

As a means for assuring a positive flow of lubricant through the lubrication system 3, pressurized air is supplied via the conduit 27 and through the orifice 30 to develop a differential in pressure between the interior portions 31 of the starter 2 and the interior portions 42 of the gearbox 4. As previously mentioned, it is preferred that this pressurized air be drawn from the compressor stage of the turbomachine 1, at a compressor stage discharge pressure, so that the partial pressure developed within the starter 2 will vary in accordance with engine operation conditions (engine speed), accordingly varying the flow of lubricant through the lubrication system 3 in response to these conditions. As a result of this variation, under certain circumstances it may be possible for excess pressures to develop within the interior portions 31 of the starter 2.However, since conventional starters generally incorporate a pressure relief valve, illustrated at 43, the dissipation of such excess pressures is automatically provided by properly adjusting the pressure relief valve 43 to release such excess pressures and thereby avoid potential damage to the starter 2.

It will therefore be seen that the lubrication system 3 of the present invention serves well to satisfy each of the objectives previously set forth, and that such a system will continuously provide adequate starter lubrication over the entire range of engine operation. As a result, service intervals for the starter 2 are capable of being significantly extended beyond those intervals which are presently required in connection with prior art starter lubrication systems.

It will also be understood that the foregoing description has been provided for illustrative purposes only, and that the lubrication system of the present invention will also find applicability in connection with other starter systems and turbomachine designs, as well as other accessories associated with the turbomachine. To accomodate these variations, the configuration of the conduits 26, 27, 28, the size of each orifice 29, 30, and the flow rates developed through the various portions of the lubrication system 3 may be varied to suit a particular application, In doing so, it is generally preferred that the size of the orifice 29 be matched to the size of the orifice 30 as previously indicated.

The configuration of the collector 33 used to receive and transfer fluid (and air) from the sump 24 of the starter 2 to the sump 25 of the gearbox 4 as previously described may also be varied. Although preferred, use of the baffles 23 is optional, and if used, the configuation of the baffles 23 may be varied to suit a particular application. Also capable of variation is the manner in which lubricant and pressurized air are derived from the turbomachine.

Other variations are also clearly possible.

It will therefore be understood that various changes in the details, materials and arrangement of parts which have been herein described and illustrated in order to explain the nature of this invention may be made by those skilled in the art within the principle and scope of the invention as expressed in the following claims.

Claims

1. A system for lubricating a starter means operatively connected to a turbomachine through a communicating gearbox, said turbomachine having a lubrication system, and said gearbox having a lubricant receiving sump and including first delivery means for delivering lubricant received within the sump of said gearbox to the lubrication system of said turbomachine, said starter lubricating system comprising: (a) second delivery means for delivering lubricant from the lubrication system of said turbomachine to said starter means, for use in lubricating said starter means; and (b) third delivery means for delivering lubricant from said starter means to said gearbox, for subsequent return to the lubrication system of said turbomachine by said first delivery means.

2. The system of claim 1 wherein said lubricating system is capable of operation over the entire range of turbomachine operation.

3. The system of claim 1 wherein said starter means has hollow interior portions including a lubricant receiving sump.

4. The system of claim 3 wherein said second delivery means communicates with the interior portions of said starter means through an orifice having a predetermined diameter.

5. The system of claim 4 wherein said predetermined diameter is approximately 0.030 inches.

6. The system of claim 4 wherein the flow rate of lubricant through said orifice varies as a function of the operating speed of said turbomachine.

7. The system of claim 6 wherein said flow rate is approximately 0.2 gpm.

8. The system of claim 3 wherein said third delivery means communicates between the sump of said starter means and the sump of said gearbox.

9. The system of claim 8 wherein said third delivery means comprises a collector means located along upper surface portions of said sump; a standpipe having a first end attached to said collector means and a second end associated with casing portions of said starter means, and communicating between said collector means and the ex terior of said starter means; and conduit means attached to and communicating between the second end of said standpipe and said gearbox.

10. The system of claim 8 wherein said third delivery means comprises a filtering means operatively associated therewith.

11. The system of claim 3 further comprising means for developing a flow of lubricant from said starter means to said gearbox.

12. The system of claim 11 wherein said flow developing means is pressurized air.

13. The system of claim 12 further comprising fourth delivery means for delivering pressurized air from said turbomachine to said starter means.

14. The system of claim 13 wherein said fourth delivery means communicates with the interior portions of said starter means through an orifice having a predetermined diameter.

15. The system of claim 14 wherein said predetermined diameter is approximately 0.060 inches.

16. The system of claim 14 wherein said second delivery means communicates with the interior portions of said starter means through an orifice having a predetermined diameter matched to the predetermined diameter of said orifice of said fourth delivery means.

17. The system of claim 14 wherein said air is delivered to said starter means at a pressure and flow which varies in accordance with the operating speed of said turbomachine.

18. The system of claim 17 wherein said flow rate is approximately 0.1 Ib/min.

19. The system of claim 17 wherein said pressure is greater than the pressure developed within said gearbox.

20. The system of claim 13 further comprising a pressure relief valve associated with said starter means for releasing excess pressures developed in the interior portions of said starter means.

21. The system of claim I further comprising baffle means operatively associated with interior portions of said starter means for directing lubricant through said interior portions.

22. The system of claim I wherein said first delivery means is a scavenge system associated with the lubrication system of said turbomachine.

23. The system of claim 1 wherein said starter lubricating system develops a continuous supply of lubricant to said starter means.

24. A method for lubricating a starter means operatively connected to a turbomachine through a communicating gearbox, said turbomachine having a lubrication system, and said gearbox having a lubricant receiving sump and means for delivering lubricant received within said sump of said gearbox to the lubrication system of said turbomachine, said method comprising the steps of: (a) delivering lubricant from the lubrication system of said turbomachine to said starter means, providing lubricant for lubricating said starter means; and (b) delivering lubricant used in lubricating said starter means from said starter means to said gearbox, for subsequent return to the lubrication system of said turbomachine.

25. The method of claim 24 wherein lubricant is continuously provided to said starter means.

26. The method of claim 24 further comprising the steps of providing interior portions of said starter means with associated baffle means and directing lubricant received from said turbomachine through said starter means using said baffle means.

27. The method of claim 24 further comprising the step of developing a flow of lubricant from said starter means to said gearbox.

28. The method of claim 27 wherein said flow developing comprises the step of delivering pressurized air from said turbomachine to interior portions of said starter means, developing a pressure differential between the interior portions of said starter means and said gearbox.

29. The method of claim 28 further comprising the step of releasing excess pressures developed within said starter means during said delivery of pressurized air thereto.

30. A lubrication system substantially as hereinbefore described with reference to and as illustrated in the drawings.

31. A lubrication method substantially as hereinbefore described.