GAS TURBINE, IN PARTICULAR A JET ENGINE

Abstract

The invention relates to a gas turbine (10), in particular a jet engine, comprising an intake (11), which supplies air to a compressor (12) for burning with a fuel, whereby a propulsion jet can be produced by the gas turbine, the compressor (12) being arranged on a shaft (15) of the gas turbine (10) for rotation therewith, and comprising a starter arrangement, which has an auxiliary unit (20) designed as an electrical starter/generator, which starts the turbine (10) and drives the compressor (12) by way of the shaft (15) until a minimum rotational speed is reached, a coupling means (30) being provided between an output-side shaft (25) of the auxiliary unit (20) and the shaft (15) of the gas turbine (10) as respective parts to be coupled, which coupling means (30) couples the parts to be coupled contactlessly. It is characteristic of the present invention that one of the parts to be coupled is designed as a magnetic disk (35) with a plurality of magnets (38) and the other part to be coupled is designed as a driver disk (32) of a metal with high electrical conductivity, so that a relative movement of the magnetic disk (35) with respect to the electrically conductive driver disk (32) allows the effect of inducing in the driver disk (32) eddy currents that produce magnetic fields opposed to the outer magnetic field and as a result produce a force effect between the magnetic disk (35) and the driver disk (32).

Claims

1. A gas turbine (10), comprising an intake (11) and a compressor (12), the intake (11) supplies air to a compressor (12) for burning with a fuel, whereby a propulsion jet is produced by the gas turbine, the compressor (12) being arranged on a shaft (15) of the gas turbine (10) for rotation therewith, and comprising a starter arrangement, which has an auxiliary unit (20) designed as an electrical starter/generator, which is adapted to start the turbine (10) and drive the compressor (12) by way of the shaft (15) until a minimum rotational speed is reached, a coupling element (30) provided between an output-side shaft (25) of the auxiliary unit (20) and the shaft (15) of the gas turbine (10) as respective parts to be coupled, said coupling element (30) couples the parts to be coupled contactlessly, wherein one of the parts to be coupled has a magnetic disk (35) with a plurality of magnets (38) and the other part to be coupled has a driver disk (32) of a metal with high electrical conductivity, so that a relative movement of the magnetic disk (35) with respect to the electrically conductive driver disk (32) induces in the driver disk (32) eddy currents that produce magnetic fields opposed to an outer magnetic field and as a result produce a force effect between the magnetic disk (35) and the driver disk (32).

2. The gas turbine as claimed in claim 1, wherein the magnetic disk (35) is assigned to the auxiliary unit (20) as the part to be coupled.

3. The gas turbine as claimed in claim 1, wherein the electrically conductive driver disk is produced from copper or from aluminum.

4. The gas turbine as claimed in claim 1, wherein the parts to be coupled are arranged in a position for use face-to-face with one another, and a movement of the one part to be coupled causes movement of the other part to be coupled.

5. The gas turbine as claimed in claim 1, wherein the magnetic disk (36) is provided with an annular arrangement.

6. The gas turbine as claimed in claim 1, wherein the magnetic disk (35) has a carrier (36) with a number of receptacles (37) corresponding to a number of the magnets (38), in which the magnets (38) are accommodated.

7. The gas turbine as claimed in claim 1, wherein the magnetic disk (35) is connected on a side facing away from the other part to be coupled to a soft-magnetic return disk (39) of a same diameter.

8. The gas turbine as claimed in claim 1, wherein the driver disk (32) is arranged in a position for use in a receptacle (34) that is arranged at an end of the turbine shaft (15) that is facing the propulsion system, the receptacle (34) being provided at an end face on a shaft nut (19) that secures the compressor (12) in an axially fixed manner.

9. The gas turbine as claimed in claim 8, wherein the shaft nut (19) and the driver disk (32) are held on the end of the turbine shaft (15) for rotation therewith by a common securing element means.

10. The gas turbine as claimed in claim 1, wherein the auxiliary unit (20) is operable as a motor and as a generator.

11. The gas turbine as claimed in claim 1, wherein the auxiliary unit (20) is formed by a brushed electric motor or by a three-phase synchronous machine.

12. The gas turbine as claimed in claim 1, wherein the coupling element (30) is provided at the compressor-side end of the turbine shaft (15).

13. The gas turbine as claimed in claim 1, wherein further comprising a plurality of struts (21) that carry the auxiliary unit (20) provided at an opening of a turbine casing (13) that forms the intake (11) of the turbine (10), the struts projecting inwardly in a direction of a longitudinal axis of the power unit, and are arranged spaced apart on an edge of the opening.

14. The gas turbine as claimed in claim 13, preceding claims, wherein along at least one of the struts (21) there extend electrical connectors, which provide motor current at phases of the auxiliary unit (20) or take off generator current at the phases of the auxiliary unit (20) or, at an end of the auxiliary unit (20) that is facing away from the shaft (15) of the turbine (10), the phase terminals of auxiliary unit are led to the outside.

15. The gas turbine as claimed in claim 1, wherein the auxiliary unit (20) is assigned at least one controller (50) of the starter arrangement (1) that controls a commutation of the auxiliary unit (20) in motor operation or controls a charging of at least one electrical storage device (56) that is connected to the auxiliary unit and is chargeable in a generator operation of the auxiliary unit (20).

16. A method for operating a starter arrangement (1) provided on a gas turbine as claimed in claim 1, wherein the coupling element is provided between the output side of the auxiliary unit (20) and the shaft (15) of the power unit as respective parts to be coupled, comprising the following method steps contactlessly coupling the output side of the auxiliary unit (20) to the shaft (15) of the power unit (20); starting the power unit (10) by the auxiliary unit (20) as an electrical drive; reaching the minimum rotational speed of the power unit (10); changing over operation of the auxiliary unit (20) to generator operation without a switching device; and charging at least one electrical storage device (56) with a charging current by way of a controller (50).

17. The method as claimed in claim 16, wherein a control signal (PWM) by which an electrical switching element is pulse-width-modulated is produced by the controller (50).

18. The gas turbine as claimed in claim 5, wherein the permanent magnets are provided and are formed as neodymium magnets.

19. The gas turbine as claimed in claim 6, wherein the receptacles (37) extend through the carrier in an axial direction.

20. The gas turbine as claims in claim 1, wherein the auxiliary unit (10) is accommodated in a housing (22).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The invention is explained in more detail below on the basis of exemplary embodiments in the partly schematic drawing, in which:

[0045] FIG. 1 shows a planar end-on view of a first exemplary embodiment of the starter arrangement from the side of the inlet into the turbine with an auxiliary unit arranged in front of the compressor;

[0046] FIG. 2 shows a perspective side view of the power unit with the starter arrangement from FIG. 1;

[0047] FIG. 3 shows a perspective view of a starter arrangement from FIGS. 1 and 2 comprising a turbine shaft with a turbine wheel, a compressor, an auxiliary unit and a flare of the inlet;

[0048] FIG. 4 shows a perspective view of the starter arrangement from FIG. 3 from a different viewing angle, in which the flare of the inlet and the struts have been omitted;

[0049] FIG. 5 shows an exploded, planar side view of the starter arrangement from FIG. 4,

[0050] FIG. 6 shows an exploded, perspective side view of the starter arrangement from FIG. 5; and

[0051] FIG. 7 shows a basic diagram of the way in which an exemplary embodiment of the control means of a starter arrangement functions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] In FIGS. 1 to 6, a starter arrangement denoted as a whole by 1 can be seen on a power unit formed by a gas turbine 10. The gas turbine 10 has an intake 11, which supplies air to a compressor 12 for burning with a fuel, whereby a propulsion jet can be produced by the power unit. The compressor 12 is arranged on a shaft 15 of the turbine 10 for rotation therewith. The starter arrangement 1 has an auxiliary unit 20, which starts the turbine 10 and drives the compressor 12 by way of the shaft 15 until a minimum rotational speed is reached. A coupling means 30 is provided between an output-side shaft 25 of the auxiliary unit 20 and the shaft 15 of the turbine 10 as respective parts to be coupled. The auxiliary unit 20 is in this case designed as an electrical starter/generator, and the coupling means 30 couples the parts to be coupled contactlessly.

[0053] FIGS. 1 and 2 show here the gas turbine 10 comprising the starter arrangement 1 as a whole with a turbine casing 13, arranged at the end of which that is facing away from the starter arrangement 1 is a nozzle 16 for the outlet of the propulsion jet that is produced in the gas turbine 10 by way of a combustion process and is not represented any further. In FIG. 1, the viewer is looking end-on at the intake 11 of the gas turbine 10, which opens out into the compressor 12 and has a flare 14 tapering in the axial direction. Positioned in the intake is the auxiliary unit 20 of the starter arrangement 1, which is suspended with its housing 22 on three struts 21, spaced apart at equal angular intervals, in front of the compressor 12 in the viewing direction, the longitudinal axes of the gas turbine 10 and the auxiliary unit 20 being arranged coaxially in relation to one another. The struts 21 project from the edge of the opening of the flare 14 in the direction of the longitudinal axis and thereby away from the compressor 12.

[0054] In FIG. 3, the same starter arrangement 1 can be seen, without the turbine casing 13, so that the turbine shaft 15 of the gas turbine 10 and also, at its end facing away from the compressor 12, the turbine wheel can be seen. Also shown in FIG. 3 are the struts 21, which are connected to the edge of the opening of the flare 14 and suspended on which is the auxiliary unit 20 accommodated in its housing 22.

[0055] By contrast with FIG. 3, the flare 14, the struts 21 and the housing 22 of the auxiliary unit 20 are not shown in FIG. 4, so that now the compressor 12, arranged on the turbine shaft 15 for rotation therewith and in an axially fixed manner, and also the BLDC motor 23 of the auxiliary unit 20 can be seen well. The coupling means 30, at which the turbine shaft 15 and the shaft 25 of the auxiliary unit 20 as parts to be coupled are coupled to one another contactlessly, and therefore softly, and at the same time are separated by the gap 31, can now also be seen.

[0056] FIGS. 5 and 6 show well in particular the contact-free coupling of the parts to be coupled of the coupling means 30, which due to the exploded representation is readily understandable. Respectively beginning on the side that is on the left for the viewer, in the representations the turbine wheel 17 arranged at the end there of the turbine shaft 15 can be seen. On the turbine shaft 15 there can also be seen two bearing elements 18, on which the turbine shaft 15 is mounted. Between the right of the two bearing elements 18 and a shaft nut 19, the compressor 12 is arranged on the turbine shaft 15 in an axially fixed manner.

[0057] The coupling element 30 contactlessly connects the turbine shaft 15 and the output-side shaft 25 of the auxiliary unit 20, which forms the motor shaft of the BLDC motor 23, as parts to be coupled. Provided for this on the shaft nut 19 is a receptacle 34, which receives the driver disk 32. The driver disk 32 is held on the shaft nut 19 by a screw 33 as fastening means and is enclosed by the edge of the receptacle 34.

[0058] Spaced apart from the driver disk 32 by the gap 31, the other part to be coupled can be seen on the coupling means 30 in the form of the magnetic disk 35, which is formed by a non-magnetic magnet carrier 36, in the axial passages 37 of which twelve permanent magnets 38 are accommodated. The magnet carrier sits with a flange 41 on the output-side shaft 25 of the auxiliary unit 20 and is secured there for rotation therewith. Coming from the direction of the gap 31, arranged behind the magnet carrier 36 is a return disk 39, with the same two-dimensional extent as the magnet carrier 36, of a soft iron alloy.

[0059] In FIG. 7, a basic diagram on the basis of which the operating modes of the auxiliary unit 20 can be explained well can be seen. In the diagram, the motor/generator 23 of the starter arrangement 1 can be schematically seen. In motor operation/starter operation, the turbine shaft 15 of the gas turbine 10 rotates at a lower rate than the output-side shaft 25 of the auxiliary unit 20 with the motor 23, which commutates the three motor phases by way of the controller 50 with commutating signals 51 in such a way that the motor 23 is set in rotation, whereby the turbine 10 can be started. The charging function of generator operation is in this case not functioning, there is no PWM signal.

[0060] Once the turbine 10 has been started, the motor 23 can be operated in generator operation. In generator operation, in which the output-side shaft 25 of the auxiliary unit 20 as the generator shaft is rotated at a lower rate than the turbine shaft 15, the voltage induced in the motor phases is rectified by a diode network 35, formed of six diodes D1 to D6. The motor commutation described above by means of commutation signals 51 for starter operation is deactivated in this operating mode.

[0061] As soon as the rectified voltage UG is greater than the voltage UA of the electrical storage means 56 designed as a rechargeable battery, the charging current symbolized by the arrow 52 begins to flow by way of the diode D7 and the shunt R1 into the storage means 51.

[0062] The control of the final charging voltage of the storage means 51 and the limitation of the maximum charging current take place solely by way of the pulse-width-modulated control signal PWM that is produced by the control means 50 and pulse-width-modulates a transistor T1. If the charging current and/or the rechargeable battery voltage become too great, the duty cycle of the control signal PWM is increased slowly by way of the controller 50 from zero by means of a PI controller of the control means 50 that is not represented any further. As a result, part of the generator current symbolized by the arrow 53 is discharged by way of the transistor T1 by the control current symbolized by the arrow 54.

[0063] The following two things happen as a result: firstly, there is a reduction in the charging current into the storage means 56 and secondly there is a slight drop in the rotational speed of the generator (motor) 23, since the eddy current coupling of the coupling means 30 develops more slip as a result of the altogether increased current loading of the generator 23. An increased motor current means a greater torque, which in turn increases the slip of the coupling means, whereby the rotational speed of the generator 23 then falls

[0064] In an extreme case, if the control signal PWM has been set to 100%, which would be tantamount to a shorting of the generator 23, the rotational speed of the generator 23, and consequently also its output voltage, would drop to very low values, the rotational speed to a few revolutions. Although a constant current would still flow by way of the transistor T1 and the motor windings, there would altogether be very small power losses, since the motor voltage and the rotational speed would settle at almost zero as a result of the short-circuit operation.

[0065] This is attributable to the slipping clutch effect of the coupling means 30 as an eddy current coupling. At the operating point just described, no charging current would then flow any longer into the storage means 56, and moreover the generator/motor 23 in particular would be relieved of stress with respect to its mounting, since it runs with only a few revolutions. What then becomes warmer at this operating point is the copper driver disk 32 on the turbine shaft 15; however, this is in any case always extremely cooled by the air stream into the turbine 10 as a result of the air speeds in the intake of the turbine 10 in the range of several hundred km/h.

[0066] The invention described above accordingly relates to a starter arrangement 1 on a gas turbine 10 or a similar power unit, for example on a jet engine, comprising an intake 11, which supplies air to a compressor 12 for burning with a fuel, whereby a propulsion jet can be produced by the power unit, the compressor 12 being arranged on a shaft 15 of the turbine 10 for rotation therewith, and comprising an auxiliary unit 20, which starts the turbine 10 and drives the compressor 12 by way of the shaft 15 until a minimum rotational speed is reached. In this case, a coupling means 30 is provided between an output-side shaft 25 of the auxiliary unit 20 and the shaft 15 of the turbine 10 as respective parts to be coupled. In order to make a starter arrangement 1 that is robust and can be handled well available, according to the invention the auxiliary unit 20 is in this case designed as an electrical starter/generator, and the coupling means 30 couples the parts to be coupled contactlessly.

[0067] In comparison with known coupling possibilities, which with a rigid coupling have to allow the parts to be coupled to run at the same rotational speed, a robust and soft coupling of the parts to be coupled is thus provided and at the same time charging of an energy storage means in generator operation of the auxiliary unit 20 is made possible.

[0068] Several advantages are obtained as a result. This is so because, with the comparatively low rotational speeds achieved by the auxiliary unit 20 during operation, the starter arrangement 1 according to the invention is unproblematic with regard to its service life, and cooling and lubrication can be easily realized. Moreover, problems that occur with rigid, mechanical coupling, such as vibrations, resonances or wearing of a disconnecting coupling, are avoided. The starter arrangement 1 according to the invention is also not sensitive to the axial offset/angular offset of the turbine shaft 15 and the output-side shaft 25 of the auxiliary unit 20, that is to say the motor/generator shaft, so that it is possible to dispense with a highly precise alignment of the two axes. Moreover, it is also not sensitive to contamination. Moreover, it is possible to dispense with switched-mode power supplies or to dispense with DC converters for charge control, so that savings can be made in terms of its space requirement/weight/costs and no interference emission takes place from the converter. The charge control can take place by means of a transistor T1. The starter arrangement 1 also functions even in the case of extremely high rotational speeds of the turbine shaft 15 of several 100,000 revolutions/minute and makes power generation/coupling of a generator 23 possible even in the case of extremely small turbines 15 and very high rotational speeds.

LIST OF DESIGNATIONS

[0069] 1 Starter arrangement [0070] 10 Gas turbine [0071] 11 Intake [0072] 12 Compressor [0073] 13 Turbine casing [0074] 14 Flare [0075] 15 Turbine shaft [0076] 16 Nozzle [0077] 17 Turbine wheel [0078] 18 Bearing element [0079] 19 Shaft nut [0080] 20 Auxiliary unit [0081] 21 Strut [0082] 22 Housing of auxiliary unit [0083] 23 BLDC motor/generator [0084] 25 Output-side shaft of the auxiliary unit [0085] 30 Coupling means [0086] 31 Gap [0087] 32 Driver disk [0088] 33 Screw [0089] 34 Receptacle [0090] 35 Magnetic disk [0091] 36 Magnet carrier [0092] 37 Receptacle for permanent magnets [0093] 38 Permanent magnet [0094] 39 Return disk of soft-iron alloy [0095] 41 Flange of the magnet carrier [0096] 50 Controller [0097] 52 Arrow as symbol of the charging current [0098] 53 Arrow as symbol of the generator current [0099] 54 Arrow as symbol of control current passed by way of transistor [0100] 55 Diode network [0101] 56 Electrical storage means [0102] Dx Diode of the diode network [0103] PWM Control signal [0104] R1 Shunt [0105] T1 Transistor