TURBINE ENGINE ROTATING AT HIGH SPEEDS

Abstract

The present invention relates to a turbine engine comprising a wheel, (2) mounted on a shaft (4), and a disk (18), adjacent to the wheel (2) and mounted on the same shaft while being rotated by the latter. The disk (18) is made of a material having a density greater than that of the material used to manufacture the wheel (2). The invention is of use in a compressor/turbine.

Claims

1-15. (canceled)

16. A turbomachine, comprising: a wheel (2) made from a first material having a first density and being mounted on a shaft (4); and a disk (18) demountably mounted to the shaft adjacent the wheel and being rotationally driven thereby, the disk made from a second material having a second density greater than the first density of the first material of the wheel.

17. The turbomachine of claim 16, wherein the first material of the wheel comprises an aluminum-based alloy.

18. The turbomachine of claim 16, wherein the second material of the disk comprises a density greater than 15.

19. The turbomachine of claim 18, wherein the second material of the disk comprises a material selected from the group consisting of tungsten, and a tungsten-based alloy.

20. The turbomachine of claim 16, wherein the disk is clamped between the wheel and the shaft.

21. The turbomachine of claim 16, wherein a first connection between the shaft and the disk is similar to a second connection between the disk and the wheel, such that the wheel can be connected to the shaft without the disk being present.

22. The turbomachine of claim 16, further comprising a radial toothset (20) connecting the disk to the wheel, wherein the radial toothset comprises Hirth-type teeth.

23. The turbomachine of claim 16, further comprising a radial toothset connecting the disk to the shaft, wherein the radial toothset comprises Hirth-type teeth.

24. The turbomachine of claim 16, wherein a diameter of the disk is less than a diameter of the wheel.

25. The turbomachine of claim 16, wherein the disk and the wheel are mounted on an end of the shaft.

26. The turbomachine of claim 25, further comprising: a stud (8) including a threaded end and being fixed to the shaft to laterally extend said shaft; and a nut (14) screwed to the threaded end of the stud at an opposite end of the shaft to damp the disc and wheel to the shaft.

27. The turbomachine of claim 26, further comprising: a frontal face for the shaft; a tapped blind axial housing (10) opening on to the frontal face; wherein the stud is threaded into the tapped blind axial housing for the shaft to accept the disk.

28. The turbomachine of claim 27, further comprising a profiled endpiece (16) covering the nut.

29. A compressor turbine, comprising at least one turbomachine, the at least one turbomachine comprising: a wheel made from a first material having a first density and being mounted on a shaft (4); and a disk demountably mounted to the shaft adjacent the wheel and being rotationally driven thereby, the disk made from a second material having a second density greater than the first density of the first material of the wheel.

30. The compressor turbine of claim 29, further comprising three centrifugal compressors and one turbine mechanically connected by a gearset to a common motor.

Description

[0019] Details and advantages of the present invention will become better apparent from the description which follows, which is given with reference to the attached schematic drawing in which:

[0020] The single FIGURE illustrates a compressor according to the present invention.

[0021] This FIGURE reveals a centrifugal wheel 2, for example made from an aluminum-based light alloy, mounted on a shaft which is, for example, a drive shaft 4 (in instances in which the energy is supplied to the centrifugal wheel: it could also be a shaft driven by the centrifugal wheel if the latter corresponds to a turbine). The drive shaft 4 is for example connected to an engine or motor (not illustrated) by means of a gearset referred to hereinafter as a gearbox (not depicted).

[0022] The centrifugal wheel 2 is mounted on the drive shaft 4, on the end of the shaft, using a stud 8. The latter has a threaded first end screwed into a longitudinal tapped hole 10 made in the end of the drive shaft 4 and thus extends the drive shaft 4 axially. The other end of the stud 8 is likewise threaded and accepts a nut 14. As this nut 14 is screwed on to the stud 8, tension is applied to the stud 8, allowing the centrifugal wheel 2 to be mounted with preload. A profiled endpiece 16, also referred to as a nose cone, covers the nut 14 to encourage the flow of fluid at the centrifugal wheel 2. Such a setup is an example of a setup known to those skilled in the art but other known ways of mounting a wheel on a shaft could be used here.

[0023] In the example illustrated, it will be noted that there is a disk 18 present between the drive shaft 4 and the centrifugal wheel 2. This disk 18 is made from a material having a density higher than that of the material used to make the centrifugal wheel 2.

[0024] In the preferred embodiment illustrated, the disk 18 is inserted between the drive shaft 4 and the centrifugal wheel 2 and the clamping of the centrifugal wheel 2 thus clamps the disk 18. The assembly formed by the disk 18 and the wheel 2 may be assembled as explained hereinabove using a stud 8 and by clamping using a nut 14. This then yields an assembly that is entirely demountable so that the disk 18 and/or the wheel 2 can easily be changed.

[0025] Transmission of torque between the centrifugal wheel 2 and the drive shaft 4 is via the disk 18. There are various alternatives possible here. In the setup proposed here in which the disk 18 is clamped between the centrifugal wheel 2 and the drive shaft 4, a simple friction drive is possible. For preference, the coupling used between the disk 18 and the centrifugal wheel 2 and between the drive shaft 4 and the disk 18 is the same as the coupling provided originally (without the disk 18) between the centrifugal wheel 2 and the drive shaft 4. In the embodiment illustrated, the coupling each time uses radial toothsets 20, also known by the name of Hirth teeth. Thus, Hirth teeth are made, on the one hand, between the drive shaft 4 and the disk 18 and, on the other hand, between the disk 18 and the centrifugal wheel 2. This type of coupling allows excellent drive and also good alignment of the components.

[0026] The disk 18 is made from a material that is dense, having a density higher for example than 15 (which means to say a mass per unit volume higher than 15 kg/dm.sup.−3). It is, for example, manufactured from a tungsten-based alloy.

[0027] In order to be able to be incorporated into the turbomachine without any concerns and in order to limit friction due to the disk, provision is made for the diameter of the disk 18 to remain smaller than the outside diameter of the centrifugal wheel 2.

[0028] The presence of the disk 18 allows the natural frequencies of the rotary assembly to be tuned so as to tune the critical rotational speeds and notably avoid the nominal operating range of the machine including such critical rotational speeds.

[0029] The centrifugal wheel 2 is intended to run at high speeds, in excess of 20 000 rev.Math.min.sup.−1, or even in excess of 40 000 rev.Math.min.sup.−1. By attaching the additional disk 18 thereto, it is possible to lower the first bending mode that corresponds to the first critical speed to below the range of operation of the rotary machine by changing the physical properties of the rotary assembly or rotor. Of course, for such rotational speeds, a balancing, preferably a dynamic balancing, of each element of the assembly formed by the disk 18 and the centrifugal wheel 2 is performed.

[0030] Using a dense material from which to make the disk 18 makes it possible to limit the size of the disk 18 and therefore of the mounted assembly and also makes it possible to limit friction losses when using the rotary machine.

[0031] It is possible to use an already existing compressor or expander wheel with a given gearbox without having to do anything to the wheel (or to the gearbox). All that is required is the addition of the additional disk as described above to adapt the dynamic properties of the rotor thus obtained to suit the intended conditions of use.

[0032] In the embodiment described hereinabove, it is appropriate to choose a disk of suitable mass and a stud that is long enough to accept both the additional disk and the wheel. The latter is then mounted on the drive shaft in the same way as it is without the disk, the only exception being that it is merely appropriate not to omit to interpose this disk between the drive shaft and the wheel when mounting the latter.

[0033] It may also be pointed out that only the stud used in the embodiment described hereinabove needs to be modified in order to mount the wheel in comparison with a setup without the additional disk.

[0034] A compressor or a turbine with a centrifugal wheel and an inertial disk may for example be used in a compressor-turbine also referred to as a compander. A centrifugal wheel then corresponds to each compression and expansion stage and all the wheels are driven by a gearbox common to all the stages. In such a compander there are, for example, three compression stages and one expansion stage.

[0035] Of course, the present invention is not restricted to the preferred embodiment described hereinabove and illustrated in the drawing but also relates to all the alternative forms mentioned and throe within the competence of a person skilled in the art within the scope of the claims which follow.