GB2414769A

GB2414769A - Turbo-machine with impeller containment assembly.

Info

Publication number: GB2414769A
Application number: GB0511257A
Authority: GB
Inventors: Walter Augustin; Thomas Winter
Original assignee: MAN B&W Diesel GmbH
Current assignee: MAN B&W Diesel GmbH
Priority date: 2004-06-05
Filing date: 2005-06-02
Publication date: 2005-12-07
Anticipated expiration: 2025-06-02
Also published as: CN1707123A; CN1707123B; FR2871201A1; FR2871201B1; GB0511257D0; CH698256B1; KR20060046301A; DE102004027594B4; DE102004027594A1; JP2005344713A; GB2414769B

Abstract

A turbo-machine with an impeller containment assembly includes a compressor having a casing 8 formed from an outer spiral housing 10 and an inner housing insert piece 12. The spiral housing 10 is fixed to a bearing housing 1 by a first fixing 18, and the insert piece 12 is fixed to the spiral housing 10 by a second fixing 17. At least one of the spiral 10 or the insert 12 is formed from a material whose elongation at break is 5% or more. The second fixing 17 may be formed from at least one necked bolt which has an elongation at break of 10% or more. Each bolt may be associated with a resilient sleeve (not shown) to improve energy absorption. The second fixing 17 may also be flexible in an axial direction and may be formed such that it breaks more easily than the first fixing 18. The insert 12 may be attached to an inner cylinder 15 of the spiral housing 10 to form a hollow space 16.

Description

Turbo-machine having a compressor wheel with radial flow The invention

relates to a turbo-machine having a compressor wheel, through which there is radial flow, in accordance with the preamble of claim 1.

The basic structure and the mode of operation of such turbo-machines, such as, for example, a radial flow compressor of a turbocharger, are known per se and do not therefore require any further explanation in this connection. EP 1 233 190 Al discloses a turbo-machine with a compressor wheel, through which there is radial flow, that has all the features of the preamble of claim 1.

It is possible that after a long operation under unfavourable operating conditions the compressor wheel of such a turbo-machine will have weakened as a result of corrosion, erosion and ageing to such a great extent that rupture of the compressor wheel cannot be precluded. In the case of breakage of a compressor wheel, where the wheel breaks at least into two or three large sections, these individual parts are thrown outwards as a result of considerable centrifugal forces. In this case, fragments can emerge from the compressor housing. In this connection, the compressor wheel blades are completely destroyed and the hub body that remains becomes jammed between the bearing housing and the compressor housing.

As a result of the shaping of the hubs, a wedge effect then develops that exerts considerable pulse-like axial forces on the housings.

Small turbo-machines can reliably take up the above loads or forces as a result of the relatively large wall thicknesses and the rigid housing portions. In the case of large turbo-machines, however, the housing wall thicknesses are mostly reduced for reasons of casting practice, as a result of which in the case of such a strain the breaking limit of the stock or material is reached rapidly and housing-breakages can result. In this connection, fragments or sections of the compressor wheel can emerge out of the turbo-machine, something which can cause considerable subsequent damage. As a result of the emergence of fragments or sections of the compressor wheel, the so-called containment security of the whole turbo-machine is impaired. This must be avoided.

In order to guarantee the containment security of turbo- machines whilst dispensing with an additional form of protection against rupture outside the spiral housing, EP l 233 190 Al proposes that the compressor housing be formed in two parts, from an outer spiral housing and an inner housing insert piece, with the inner housing insert piece being attached to the outer spiral housing by way of a flexible fixation. This flexible fixation, which is used to secure the housing insert piece to the spiral housing, is formed so that it is less break-proof than a rigid fixation of the compressor housing, namely the outer spiral housing, on the bearing housing of the turbo machine. As a result, through the prior art in accordance with EP l 233 190 Al a spiral housing with a "crumple zone" is provided with which any emergence of a fragment or section of a ruptured impeller can already be reliably avoided. The kinetic energy of fragments of a rupturing compressor wheel can be completely converted into deformation energy and heat within the turbo- machine.

With turbo-machines as shown in EP l 233 190 Al there is the risk that the flexible fixation of the inner housing insert piece on the outer spiral housing can fail during the energy absorption and that as a result the inner housing insert piece will be accelerated in the axial direction. Components arranged in the axial direction in front of the housing insert piece, a silencer for example, may be destroyed under these circumstances. Emergence of fragments or sections of the compressor wheel is then also possible and the containment security of the turbo-machine is no longer guaranteed.

The present invention aims to provide a new type of turbo- machine having a compressor wheel, through which there is radial flow, that has increased containment security.

The invention is defined in claim 1. In accordance with embodiments of the invention at least the outer spiral housing and/or the inner housing insert piece are/is formed from a material whose elongation at break amounts to at least 5%.

For the purposes of the present invention it is proposed that the assemblies of the turbo-machine that are on the stator side or are fixed or non-rotating, namely at least the outer spiral housing and/or the inner housing insert piece, be produced from a material whose elongation at break amounts to at least 5%. The elongation at break is a characteristic quantity of strength of materials that can be determined in a tension test. The elongation at break is expressed in percent and is the change in length that remains after a sample of material has broken relative to the initial length measured.

In accordance with an advantageous further development of the invention, the second fixation, which is used to secure the housing insert piece to the spiral housing, is formed in such a way that the second fixation can absorb at least 0.2% of the maximum kinetic energy of the compressor wheel and at least 1.0% of the deformation energy that is taken up by the housing insert piece. To this end, the second fixation can be formed from at least one necked-down bolt with an elongation at break of at least 10%. Alternatively, or in addition, it is possible for a resilient sleeve to be associated with each necked- down bolt in order to increase the energy absorption.

For a better understanding of the invention, embodiments of it will now be described by way of example with reference to the accompanying drawings, in which Figure 1 shows a detail portion from a turbo-machine with a compressor wheel, through which there is radial flow.

Figure 1 shows a partial longitudinal section through a turbo-machine in accordance with the invention in the form of a radial flow compressor with a shaft 2 which in its central longitudinal area is mounted in a bearing housing 1 and carries at its ends that project beyond the mounting a turbine wheel, which is not shown here, and a compressor wheel 3, which is diagrammatically represented in Figure 1 and through which there is radial flow.

The compressor wheel 3 has a hub 4 which is received in a rotationlocking manner on the shaft 2 driven by the turbine wheel and is occupied by radially protruding blades 5 on the periphery. An outer contour 6 of the hub 4 delimits, with an inner contour 7 of a compressor housing 8, an outwardly narrowing flow channel 9 which is deflected from the axial direction A into the radial direction B and whose cross section corresponds to the configuration of the blades 5. The compressor housing 8 is secured to the bearing housing 1 by means of a first rigid fixation 18. The diameter of the hub 4 and the blades 5 increases from the flow inlet to the flow outlet, resulting in a longitudinal cross-section that is asymmetrical with respect to the central transverse plane of the compressor wheel 3 and accordingly also a mass distribution that increases over the length of the compressor wheel 3.

The compressor housing 8 is formed from an outer spiral housing 10, which is fastened on the bearing housing 1 by means of the rigid fixation 18, and an inner housing insert piece 12. The spiral housing 10 comprises a channel section 11 of the flow channel 9 that is turned outwardly in the radial direction B. The inner housing insert piece 12 is positioned between the outer spiral housing 10 and the compressor wheel 3 in the radial direction B. The inner contour 13 of the housing insert piece 12 together with the outer contour 6 of the hub 4 of the compressor wheel 3 forms a channel section 14 of the flow channel 9 that extends substantially in the axial direction A. The compressor housing 8 is set on the bearing housing 1 by way of the outer spiral housing 10, forming a separating line 22, in such a way that the outer spiral housing 10 comprising the turned-out or deflected channel section 11 is drawn inwards past the rigid fixing point 18 of the compressor housing 8 on the bearing housing 1 in the radial direction B; the rigid fixture 18 is thus arranged so that it lies further outwards in the radial direction B than the separating line 22 between the spiral housing 10 and the bearing housing 1. This configuration or arrangement of the separating line 22 ensures that the rigid fixture 18 of the compressor housing 8 on the bearing housing 1 is hardly loaded by any fragments that might possibly become wedged in the flow channel 9, as a result of which the compressor housing 8 can be prevented from breaking away. The distance between the separating line 22 and the shaft 2 is preferably smaller than the distance of the area centre 23 of the greatest cross- sectional area 24 through the diverted channel section 11 in the spiral housing 10 to the shaft 2.

The spiral housing 10 is constructed with an inner cylinder 15 that surrounds the inner housing insert piece 12 at least in part and to which the housing insert piece 12 is attached by means of a second fixture 17 in order to form a hollow space or circumferential cavity 16.

The fixture 17 is flexible in the axial direction A and is realized so that it is considerably less break-proof than the fixture 18 of the spiral housing 10 on the bearing housing 1. The rigid fixture 18 of the compressor housing 8 or the spiral housing 10 on the bearing housing 1 is realized by means of a fixed flanged connection of the spiral housing 10 on the bearing housing 1. The flexible fixture 17 of the inner housing insert piece 12 on the outer spiral housing 10 is realized by means of a necked-down bolt arrangement in the axial direction A through the inner cylinder 15 of the spiral housing 10.

A wall 19 of the bearing housing 1 that co-operates with the rigid attachment 18 is arranged so that it is drawn down in the radial direction B until it comes over an outer tip 20 of the outer contour 6 of the hub 4 of the compressor wheel 3, whilst forming a gap 21. The spiral housing 10 is constructed with the diameter of the flow channel 9 becoming increasingly smaller inwards in the direction of the compressor wheel 3.

In order to improve the containment security of the turbo machine described above, for the purposes of the present invention it is proposed that at least the outer spiral housing 10 and/or the inner housing insert piece 12, that is, non-rotating or fixed components of the turbo-machine, be formed from a material whose elongation at break amounts to at least 5%. Preferably both the outer spiral housing 10 and the inner housing insert piece 12 are formed from a material with an elongation at break of at least 5%. It is a finding of the present invention that by using materials for the non-rotating components of the turbo-machine that have an elongation at break of at least 5% it is possible to improve the containment security of the turbo-machine.

In accordance with a preferred further development of the present invention, the fixture 17, which is used to secure the inner housing insert piece 12 to the spiral housing 10, is formed in such a way that it can absorb at least 0.2% of the maximum kinetic energy of the compressor wheel 3 and at least 1.0% of the deformation energy that is taken up by the inner housing insert piece 12. As a result, it is guaranteed that failure of the inner fixture 17 is precluded throughout the process of energy absorption.

As already mentioned, the fixture 17 between the spiral housing 10 and the inner insert 12 is realized as a necked-down bolt arrangement. The fixture 17 accordingly comprises at least one necked-down bolt, with the or each necked-down bolt being formed from a material with an elongation at break of at least 10%, preferably at least 13%.

Likewise it is within the ambit of the present invention to associate a resilient sleeve, which is not shown in Figure 1, with the or each neckeddown bolt of the fixation 17. With such resilient sleeves it is possible to achieve a situation where the fixation 17 can absorb a greater quantity of energy. The resilient sleeves are then preferably formed from a material whose elongation at break amounts to at least 10%, in particular at least 13%.

In addition to choosing a suitable material for the resilient sleeves, it is possible, furthermore, to configure the resilient sleeves in such a way structurally that the same can absorb a sufficient quantity of kinetic energy. Furthermore, it is possible to increase the quantity of energy that can be absorbed by the fixture 17 by enlarging the deformation volume of the reduced shaft of the necked-down bolts.

With the aid of the present invention it is possible to improve in a distinct way the containment security of the turbo-machine that is known from EP 1 233 190 Al. It is possible to dispense with a form of protection against rupture outside the spiral housing. A further reduction in the wall thickness of the housing components and thus a reduction in weight and costs of the turbo-machine is possible.

List of reference numerals 1 Bearing housing 2 Shaft 3 Compressor wheel 4 Hub Blade 6 Outer contour 7 Inner contour 8 Compressor housing 9 Flow channel Spiral housing 11 Channel section 12 Housing insert piece 13 Inner contour 14 Channel section Inner cylinder 16 Hollow space 17 Fixture 18 Fixture 19 Wall Tip 21 Gap 22 Separating line 23 Centre of area 24 Cross section ) 9

Claims

Claims 1. A turbo-machine having a compressor wheel (3), adapted for

radial flow and received on a shaft (2) mounted in a bearing housing (1) and arranged in a compressor housing (8) with a helical flow channel (9), with the outer contour (6) of the hub (4) of the compressor wheel (3) and the inner contour (7) of the compressor housing (8) forming the flow channel (9) which is diverted from the axial direction into a radial direction, wherein the compressor housing (8) is formed from an outer spiral housing (10) and an inner housing insert piece (12), the outer spiral housing (10) including a channel section (11) of the flow channel (9) that is diverted outwards into the radial direction and is fixed by means of a first fixture (18) on the bearing housing (1), and wherein the inner housing insert piece (12), by way of its inner contour (13), forms with the outer contour (6) of the hub (4) of the compressor wheel (3) a channel section (14) of the flow channel (9) that extends substantially in the axial direction, is arranged between the spiral housing (10) and the compressor wheel (3), and is fixed by means of a second fixture (17) on the spiral housing (10), characterized in that at least one of the outer spiral housing (10) and the inner housing insert piece (12) is formed from a material whose elongation at break amounts to at least 5%.
2. A turbo-machine according to claim 1, in which both the outer spiral housing (10) and the inner housing insert piece (12) are formed from a material whose elongation at break is at least 5%.
3. A turbo-machine according to claim 1 or 2, in which the second fixture (17), which is used to secure the housing insert piece (12) to the spiral housing (10), is formed in such a way that it can absorb at least 0.2% of the maximum kinetic energy of the compressor wheel (3) and at least 1.0% of the deformation energy that is taken up by the housing insert piece (12).
4. A turbo-machine according to any preceding claim, in which the second fixture (17) is formed from at least one necked-down bolt with an elongation at break of at least 10%.
5. A turbo-machine according to claim 4, in which the elongation at break of the or each necked-down bolt is at least 13%.
6. A turbo-machine according to any preceding claim, in which the second fixture (17) is formed from at least one necked-down bolt, with a resilient sleeve being associated with each necked-down bolt in order to increase the energy absorption.
7. A turbo-machine according to claim 6, in which the or each resilient sleeve is formed from a material whose elongation at break is at least 10%.
8. A turbo-machine according to claim 7, in which the elongation at break of the or each resilient sleeve is at least 13%.
9. A turbo-machine according to any preceding claim, in which the spiral housing (10) is constructed with an inner cylinder (15) which surrounds the housing insert piece (12) at least in part and to which the housing insert piece (12) is attached by means of the second fixture (17) in order to form a hollow space (16).
10. A turbo-machine according to any preceding claim, in which the second fixture (17) is flexible in the axial direction and is formed so that it is less break-proof than the first fixture (18).
11. A turbo-machine substantially as described herein with reference to the attached drawings.