GB2176540A - Bearing and mounting arrangement in a gas turbine engine - Google Patents

Abstract

The engine comprises a turbine casing 10, an air intake housing 11, intake support structure 15, an exhaust system 30 and a fluid passage formed through the housing for fluidly connecting the air intake to the exhaust outlet. The stubs 19,21 of an air compressor 18 are rotatably mounted by bearing assemblies 20,22 to support housing 12 while the forward end of the air compressor 18 is open to the air intake 14. Turbine stages 36,38 are positioned within the exhaust passageway 30 and are secured to the rear stub 21 of the compressor 18 by a cone headed turbine bolt 48 so that the bearing assemblies 20, 22 which rotatably mount the compressor stubs 19, 21 to the housing 12 also rotatably mount the turbine stages 36,38 to the housing. The turbine stages 36,38 are located to each other and the compressor by labyrinth sleeves 60,61. The cantilevered mounting of the turbine allows the bearing assemblies 20,22 to be located in a relatively cool zone of the engine thus preventing rapid deterioration of lubricant. <IMAGE>

Description

SPECIFICATION Turbine engine The present invention relates generally to turbine engines and, more particularly, to a turbine engine with cantilevered turbine stages.

The previously known turbine engines typically comprise an intake system, support housing and exhaust passageway. An air compressor is rotatably mounted within the turbine engine housing and, upon rotation, inducts air into the air intake, compresses the air and discharges the compressed air through a diffuser assembly to a combustion chamber.

Fuel is mixed with the compressed air with the combustion chamber and the mixture is ignited. Following combustion of the fuel within the combustion chamber, the hot and expanding combustion products expand out through an exhaust passageway and out through the exhaust outlet. At least one and usually more turbine stages each have an aerofoil positioned within the exhaust passageway which are rotatably driven by the flow of the gas stream through the exhaust passageway.

The turbine stages are drivingly connected with the compressor so that, as the turbine stages are rotatably driven by the exhaust gas stream, the turbine stages rotatably drive the compressor. Typically, the compressor and turbine stages are axially aligned with each other and both are secured to a common main shaft. This main shaft is rotatably mounted to the engine housing by at least two and sometimes more bearing assemblies at axially spaced positions along the entire length of the shaft.

One disadvantage of this previously known turbine engine construction is that at least one bearing assembly is positioned between the main shaft and the engine housing within the turbine section of the engine which is subjected to the high heat loads present in the turbine section of the engine. The proper lubrication of such bearings is both difficult and expensive to accomplish. Furthermore, the high heat loads rapidly deteriorate the lubricant for the bearing assembly thus necessitating frequent changing of the lubricant in order to prevent bearing failure. The prevention of bearing failure is of the utmost importance since a bearing failure can result in the destruction of the entire turbine engine.

The present invention provides a turbine engine construction which overcomes the abovementioned disadvantages of the previously known engines.

According to the invention, a turbine engine comprises a turbine casing having an air intake defined by an intake housing having an intake support structure, a support housing and an exhaust outlet; an air compressor, one end of said air compressor being open to said air intake; means for rotatably mounting said compressor to said intake support structure within said turbine casing; fluid passage formed through said turbine casing for fluidly connecting said air intake to said exhaust outlet, said fluid passage means comprising an exhaust passageway which terminates at said exhaust outlet; at least one turbine stage having an aerofoil positioned in said exhaust passageway, and means for securing at least one turbine stage to said air compressor so that at least one turbine stage is rotatably mounted in said turbine casing solely by said compressor mounting means.

In brief, the turbine engine of the present invention comprises an intake system, an exhaust outlet and a fluid passage means formed through the housing for fluidly connecting the air intake to the exhaust outlet. An air compressor with rear stub is rotatably mounted by a bearing assembly within the support housing while the forward end of the air compressor is open to the air intake. The forward end of the air compressor also includes a stub which is rotatably mounted by a bearing to the intake housing. The air compressor discharges compressed air through a diffuser assembly to a combustion chamber where the compressed air is intermixed with fuel and ignited. The combustion products from the combustion chamber then exhaust one through an exhaust passageway and out through the exhaust outlet.

At least one and preferably two turbine stages each having aerofoils, i.e., turbine blades, which are positioned within the exhaust passageway so that the gas stream flow through the exhaust passageway rotatably drives the turbine stages. Unlike the previously known turbine engines, however, the turbine stages are secured to the rear stub of the air compressor by a cone headed turbine bolt so that the turbine stages are cantilevered from the compressor and thus rotatably mounted to the housing solely by the air compressor bearing assemblies. The turbine stages are located to each other and to the compressor by labyrinth sleeves. The air compressor bearing assemblies are contained within a cooler zone of the engine than the turbine stage so that lubrication of the bearing assemblies is relatively simple and inexpensive to accomplish.

A better understanding of the present invention will be had upon reference to the accompanying drawing which is a fragmentary longitudinal sectional view illustrating a preferred embodiment of the invention.

With reference to the drawing, a preferred embodiment of the turbine engine construction of the present invention is thereshown and comprises a turbine structure casing 10 having an air intake 14 and an exhaust outlet 16.

The air intake 14 is defined by an intake housing 11 having an intake support structure 15. An air compressor 18 having a front stub 19 is rotatably mounted within the intake housing 15 by a front bearing assembly 20.

Similarly, the compressor 18 includes a rear stub 21 which is directly rotatably mounted by a bearing assembly 22 to the support housing 12. The support housing 12 is secured to the intake support structure 15 within the air intake housing 11. The front of the compressor 18 is open to the air intake 14, and upon rotation of the air compressor 18, the compressor 18 inducts air into the air intake 14 and discharges compressed air through a diffuser assembly 26 and to an annular combustion chamber 28 formed within the turbine casing 10.

Fuel is intermixed with the compressed air within the combustion chamber 28 and ignited in the conventional fashion. The resulting hot and expanding combustion products from the combustion chamber 28 exhausts out through an exhaust passageway 30 and the out through the exhaust outlet 16. A high pressure nozzle 32 and a lower pressure nozzle 34 extend across the exhaust passageway 30 to aerodynamically shape the gas stream flow through the exhaust passageway 30.

At least one and preferably two turbine stages 36 and 38 are contained within the housing 12. Each turbine stage 36 and 38 comprises a disc shaped hub 40 and 41, respectively, with an aerofoil or turbine blades 42 secured around its outer periphery and positioned within the exhaust passageway 30.

As shown in the drawing, the first turbine stage 36 is a high pressure turbine stage and positioned in between the high pressure and low pressure nozzles 32 and 34. The second turbine stage is a low pressure turbine stage and its aerofoil or turbine blades 42 are positioned within the exhaust passageway 30 behind or downstream from the low pressure nozzle 34.

An axial throughbore 46 is formed through the hubs 40 and 41 of each turbine stage 36 and 38. A cone headed turbine bolt 48 having external threads at one end 50 is then positioned through the hub bores 46 and the bolt end 50 threadably engages an internally threaded axial bore 52 in the rear compressor stub 21. Labyrinth sleeves 60 and 61 are positioned between the turbine hubs 40 and 41 and the compressor stub 21 and hub 40, respectively to locate and align the turbine stages 36 and 38 and compressor 18 together.

The cone end 56 of the bolt 48 locates against the rear surface of the low pressure turbine stage 38 so that, upon tightening, the bolt 48 secures the turbine stages 36 and 38 to the air compressor 18. Consequently, the turbine stages 36 and 38 rotate in unison with the air compressor 18.

An important feature of the present invention is that the turbine stages 36 and 38 are cantilevered from the compressor 18 and rotatably mounted within in the turbine structure casing 10 solely by the air compressor bearing assemblies 2 0 and 22. Since the air compressor bearing assemblies 20 and 22 are spaced inwardly and upstream from the exhaust passageway 30, the bearing assemblies 20 and 22 are contained in a relatively cool zone of the engine. Lubrication of the bearing assemblies in the engine cool zone is relatively simple and does not result in rapid deterioration of the lubricant.

Claims (12)

1. A turbine engine comprising a turbine casing having an air intake defined by an intake housing having an intake support structure, a support housing and an exhaust outlet; an air compressor, one end of said air compressor being open to said air intake; means for rotatably mounting said compressor to said intake support structure within said turbine casing; fluid passage formed through said turbine casing for fluidly connecting said air intake to said exhaust outlet, said flange passage means comprising an exhaust passageway which terminates at said exhaust outlet; at least one turbine stage having an aerofoil positioned in said exhaust passageway, and means for securing at least one turbine stage to said air compressor so that at least one turbine stage is rotatably mounted in said turbine casing solely by said compressor mounting means.

2. The invention as defined in Claim 1 and comprising at least two turbine stages.

3. The invention as defined in Claim 1 wherein said turbine stage is disc shaped and wherein said securing means comprises a bolt attached at one end to said compressor and holding said turbine stage at its other end.

4. The invention as defined in Claim 3 wherein said one end of said bolt is externally threaded and threadably engages an internally threaded bore in said end of said compressor.

5. The invention as defined in Claim 3 wherein said bolt is a cone headed bolt.

6. The invention as defined in Claim 1 wherein said rotatably mounting means comprises a bearing assembly.

7. The invention as defined in Claim 6 wherein said bearing assembly is positioned upstream from said exhaust passageway.

8. The invention as defined in Claim 1 and comprising a labyrinth sleeve between said turbine stage and said compressor.

9. The invention as defined in Claim 2 and comprising a first labyrinth sleeve between said compressor and one of said turbine stages and a second labyrinth sleeve between said turbine stages.

10. The invention as defined in Claim 1 wherein said compressor comprises a stub at one end and wherein said rotatable mounting means comprises a bearing assembly between said intake structure and said compressor stub.

11. The invention as defined in Claim 1 wherein said compressor comprises a stub at one end wherein said rotatable mounting means comprises a bearing assembly between said support housing and said compressor stub.

12. A turbine engine constructed and arranged substantially as described herein and shown in the accompanying drawings.