Turbine wheel and method of manufacturing the same

Abstract

A turbine wheel consists of a first shroud component and a second bladed disc component. The shroud component comprises a shroud structure, a hub structure and a spoke formed integrally therewith and extending between the shroud structure and the hub structure. The bladed disc component comprises a hub member having inner and outer rims, turbine blades disposed on the outer rim, and at least one receiving zone for receiving the spoke, said at least one receiving zone extending radially between the inner and outer rims. The shroud component and the bladed disc component are connected and thus provide the turbine wheel with a shrouded portion. A shrouded turbine wheel can therefore be conveniently assembled starting from at least two components. Further, these components have simplified geometries for easy manufacture, for example using a casting technique, while the overall mechanical performance of the turbine is preserved or improved.

Claims

1. A shrouded turbine wheel comprising: a shroud component; and a bladed disc component; wherein: the shroud and bladed disc components are one received or receivable by the other such that, when one is received by the other, the shroud and bladed disc components co-rotate when the turbine wheel rotates, the shroud, component comprises a shroud structure, a hub structure and at least one spoke extending radially between the shroud structure and the hub structure, the bladed disc component comprises a hub member defining an outer rim, and one or more turbine blades disposed on the outer rim, and the shroud structure provides at least a shrouded portion of the turbine wheel.

2. The turbine wheel of claim 1, wherein the turbine wheel consists of said shroud and bladed disc components.

3. The turbine wheel of claim 1, wherein the hub member defines an inner rim adapted to receive the hub structure.

4. The turbine wheel of claim 1, wherein the shroud structure comprises a shroud ring angularly disposed around at least part of the bladed disc component.

5. The turbine wheel of claim 1, wherein the shroud component and/or the bladed disc component is monolithic.

6. The turbine wheel of claim 1, wherein the at least one spoke comprises a respective shoulder for engaging with a surface of the hub member.

7. The turbine wheel of claim 1, wherein the hub member comprises at least one receiving zone for receiving the at least one spoke.

8. The turbine wheel of claim 7, further comprising at least one joint or connection that connects the spoke to the receiving zone, thereby connecting the bladed disc and shroud components.

9. The turbine wheel of claim 1, wherein the shroud component is press-fitted to the bladed disc component.

10. The turbine wheel of claim 1, wherein the turbine wheel is an axial turbine wheel.

11. The turbine wheel of claim 10, wherein the turbine wheel has an outer diameter smaller than 20 cm.

12. The turbine wheel of claim 1, wherein at least one spoke comprises at least one blade-form element located adjacent the shroud structure.

13. The turbine wheel of claim 12, wherein the at least one blade-form element extends radially between a shoulder of the at least one spoke and the shroud structure.

14. A method of assembling a shrouded turbine wheel, the method comprising: providing a shroud component comprising a shroud structure, a hub structure and at least one spoke extending radially between the shroud structure and the hub structure; providing a bladed disc component comprising a hub member defining inner and outer rims, and one or more turbine blades disposed on the outer rim; wherein the shroud and bladed disc components are one received or receivable by the other such that, when one is received by the other, the shroud and bladed disc components co-rotate when the turbine wheel rotates.

15. The method of claim 14, further comprising mating the shroud and bladed disc components.

16. The method of claim 15, wherein mating the shroud and bladed disc components comprises mating the at least one spoke and a receiving zone defined on the hub member.

17. The method of claim 15, wherein mating the shroud and bladed disc components comprises mating the hub structure and the hub member, or vice versa.

18. The method of claim 16, further comprising joining the shroud and bladed disc components.

19. The method of claim 18, wherein joining the shroud and bladed disc components comprises press-fitting; welding: sintering and/or brazing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure will now be described purely by way of example with reference to the accompanying Drawings in which:

(2) FIG. 1 is a plan view of a spoked shroud component as described herein;

(3) FIG. 2 is a cross-section of FIG. 1 along line A-A;

(4) FIG. 3 is a plan view of a bladed disc component as described herein, complementary to the spoked shroud component shown in FIG. 1;

(5) FIG. 4 is a cross section along line B-B of FIG. 3;

(6) FIG. 5 is a cross section along line C-C of FIG. 3; and

(7) FIG. 6 explains schematically a method of assembling the complementary shroud and bladed disc components of FIGS. 1-5.

DESCRIPTION

(8) A turbine wheel is formed by coupling a shroud component 10 to a bladed disc component 20. The shroud component 10 can be mounted on the bladed disc component 20 or the bladed disc component 20 can be mounted on the shroud component 10. The shroud component 10 and the bladed disc component 20 as assembled form the turbine wheel 100.

(9) As shown in FIGS. 1-2, the shroud component 10 comprises a shroud structure 11, a hub structure 12 and at least one spoke 13a, 13b, 13c, 13d, 13e, 13f extending radially between the shroud structure 11 and the hub structure 12 as shown in FIGS. 1 and 2.

(10) As shown in FIGS. 3-5, the bladed disc component 20 comprises a hub member 21. The hub member 21 defines an outer rim 22. In the illustrated bladed disc component 20, a plurality of turbine blades 23 are disposed on the outer rim 22 as shown in FIGS. 3-5.

(11) The shroud structure 11 provides at least a shrouded portion 111 of the final or complete turbine wheel 100. In the described arrangement, however, the shroud structure 11 provides the entire shroud 111 of the shrouded turbine wheel 100.

(12) In the illustrations, the turbine wheel 100 is assembled from only two parts 10, 20. However, it would be possible, for example, to provide the bladed disc component 10 as a single part, in much the same manner as described herein, and multiple shroud components 20 also generally of the type described herein, but modular so as to form the complete shroud 111 around the turbine wheel 100 using two or more similar shroud components.

(13) Similarly, it would be possible to provide the shroud component 20 as a single part as described herein, and mount multiple modular bladed disc components 10 generally of the kind described herein on the shroud component 20. These modular arrangements are less preferred and are thus not described in detail herein.

(14) The hub member 21 defines an inner rim 24 adapted to receive the hub structure 12. In the described arrangement, the hub structure 12 in the form of a hub ring 14. The inner rim 24 is circumferential and adapted to mate with the hub ring 14 for receiving, locating or connecting the shroud component 10 on the bladed disc component 20.

(15) As used herein, “to receive” and its related terminology means at least a relation of close proximity between for example two “received” parts.

(16) “To mate” and its related terminology means at least a relation of contact between for example two “mating” parts.

(17) “To join” or “to connect” and their related terminology means instead a relation that involves exchange and/or transmission of forces between two parts, so that the parts are “joined” or “connected”.

(18) The shroud and bladed disc components 10, 20 described herein, therefore, are one received or receivable by the other, involve mating surfaces when one is received by the other and may be joined or connected to some more or less permanent degree so as to form the complete turbine wheel 100.

(19) In the described arrangement, the shroud structure 11 is in the form of a shroud ring 15 angularly disposed around the entire hub structure 12 of the shroud component 10. Accordingly, the shroud component 10 is able to provide the entire shroud 111 of the turbine wheel 100.

(20) Another characteristic of the described parts 10, 20 is that they are ‘monolithic’. This means that each part is formed as a solid volume of material, for example by a casting or moulding process such as investment casting or metal injection moulding. Alternatives are possible, however, such as 3D printing or metal sintering. It will be observed that these parts 10, 20 are considerably less difficult to manufacture as single pieces than the entire turbine wheel 100 as a single piece.

(21) In the described arrangement, each spoke comprises a shoulder or projection 16a, 16b, 16c, 16d, 16e, 16f for engaging with the hub member 21. In particular, each shoulder 16a-f comprises a corresponding axially extending wall 17a, 17b, 17c, 17d, 17e, 17f that mates with the outer rim 22 of the hub member 21. This zone is considered to be suitable for joining the parts 10, 20 by welding and/or brazing as explained in more detail below.

(22) In the described arrangement, each spoke 13a-f also comprises a respective blade-form element 18a, 18b, 18c, 16d, 18e, 18f located adjacent the shroud structure 11.

(23) The blade-form elements 18a-f, which are aerodynamic elements much like the turbine blades 23, depend from the shroud ring 15 radially inwardly and are disposed at regular angular intervals of 60 degrees in the described turbine wheel. Different angular configurations of the spokes 13a-f, and therefore the blade-form elements 18a-f, would however be possible.

(24) Further, in the arrangement shown in FIGS. 1 and 2 each spoke 13a-f has one and only one respective blade-form element 18a-f. In alternative arrangements, however, there could be more than one blade-form elements associated to the same spoke. For example, each spoke could be angularly wider than shown in the accompanying Figures and encompass two blade-form elements. These arrangements, however, are less preferred and are therefore not described herein in detail.

(25) Returning to the illustrations of FIGS. 1-5, six blade-form elements 18a-f extend radially from the respective shoulders or projections 16a-f to the shroud ring 15 at equal angular intervals of 60 degrees. The blade-form elements 18a-f are in this design integral with the spokes 13a-f and complement the number of blades 23 provided on the outer rim 22 of the bladed disc component 20.

(26) Turning now to the bladed disc component 20 represented in FIGS. 3-5, the hub member 21 comprises six receiving zone 25a, 25b, 25c, 25d, 25e, 25f for receiving the six spokes 13a-f of the shroud component 10.

(27) In the described arrangement, the receiving zones 25a-f extend to comprise respective spaces 29a, 29b, 29c, 29d, 29e, 29f identifiable on the outer rim 22 of the hub member 21 for receiving the blade-form elements 18a-f of each spoke 13a-f.

(28) Portions 26a, 26b, 26c, 26d, 26e, 26 of the receiving zones 25a-f are identifiable on a radial wall 27 of the hub member 21 and extend radially between the inner and outer rims 22, 24.

(29) Each receiving zone 25a-f comprises at least one axially extending recess 30a, 30b, 30c, 30d, 30e, 30f formed axially on the hub member 21 whose cross-section section is visible on the radial wall 27 of the hub member 21 as shown in FIGS. 3-5.

(30) The radial recesses 26a-f on the radial wall 27 of the hub member 21 essentially conform to portions of the spokes 13a-f so that the spokes 13a-f are received therein. This spatial relationship between the spokes 13a-f and the corresponding portions 26a-f of the receiving zones 25a-f, when the first part 10 is coupled to the second part 20 to form the turbine wheel 100, is in this arrangement a transient or location fit. Press or interference fit would however also be possible. Where registration in place of the shroud component 10 on the bladed disc component 20 is performed elsewhere, then a clearance fit could alternatively be specified.

(31) The turbine wheel 100 may be provided as a kit of disassembled parts 10, 20. The one or more shroud components 10 and the one or more bladed disc components 20 can subsequently be assembled to form a complete axial turbine wheel 100 in readiness for mounting as part of a system such as a waste heat recovery system (not shown) for automotive applications.

(32) In the described turbine wheel 100, respective weld lines 33 connect each spoke 13a-f with the corresponding portions 26a-f of the hub receiving zone 25a-f, thereby creating or reinforcing the connection between the shroud and bladed disc components 10, 20.

(33) In the described turbine wheel 100, the shroud component 10 is also press-fitted to the bladed disc component 20 via the hub structure 12 and corresponding inner rim 24 and opening on the hub member 21. This also creates a permanent connection between the shroud and bladed disc components 10, 20.

(34) Further, each shoulder or projection 16 is press fitted to a corresponding shoulder receiving recess 30 provided on the hub member 21. In particular, in the described turbine wheel 100 each shoulder or projection 16 defines two opposed radially extending walls 19 which are press fitted to two corresponding opposed radially extending walls 31 of the hub member 21.

(35) While in the present description the complete turbine wheel 100 is an axial turbine wheel, it will be appreciated that the present design can be applied in principle to any shrouded turbine wheel. The shown turbine wheel 100 has an outer diameter of 10 cm, but a range of different outer diameters are possible. The described design of turbine wheel is, however particularly suitable to small turbine wheels, having an outer diameter of 20 cm or less, or 10 cm or less.

(36) The described shroud component 10 is made of a steel alloy and is manufactured by a casting technique, namely investment casting, as a monolithic piece. Other techniques are however possible such as metal injection moulding, direct laser sintering and/or 3D printing.

(37) The described bladed disc component 20, is made of the same steel alloy as the shroud component 10, but is obtained via a metal injection moulding process, also as a monolithic piece. Other techniques are however possible just like for the shroud component 10, and encompass at least investment casting, direct metal laser sintering and 3D printing.

(38) Investment casting is preferred for the shroud component 10 and metal injection moulding is preferred for the bladed disc component 20.

(39) Referring now to FIG. 6, a method of mounting the shroud component 10 described herein onto the bladed disc component 20 described herein is schematically illustrated. The coupling of the shroud component 10 to the bladed disc component 20 is only schematically referred to by the arrow of FIG. 6.

(40) The components 10, 20 are first laid out on the plane defined by the sheet of paper in the same orientations shown in FIGS. 1 and 3. The shroud component 10 is then mounted to, i.e. brought into mating engagement with, the bladed disc component 20, (which is instead kept still) as if the sheet of paper was folded in half, so that the right-hand half thereof folds over the left-hand half.

(41) It would also be possible, conversely, to fit the bladed disc component 20 onto the shroud component (while this is kept still) or move both parts 10, 20 so as to couple them.

(42) As the shroud component 10 is brought into mating engagement with the bladed disc component 20: the hub structure 12 is received into the opening defined by the inner rim 24 of the hub member 21 and a connection is made by interference; the spokes 13 are received into the corresponding spoke-receiving recesses 26 formed on the hub member 21, and this coupling is by transition fit; the shoulders or projections 16 of the shroud component 10 are received into the respective shoulder receiving recesses 30 formed in the hub member 21 and couple therewith. The opposed radially extending walls 19 of the projections or shoulders couple by interference with the corresponding radial walls 31 of the recesses 30; the blade-form elements 18 are received with clearance into the corresponding blade-form element receiving spaces 29 defined on the outer rim 22 of the hub member 21; the axially extending surfaces 17 of the shoulder or projections 16 mate (i.e. a transition fit is specified here) with the corresponding axially extending surfaces on the hub recesses 30; and, importantly, the shroud ring 15 is also received and precisely locates, although with some clearance, over the tips 32 of the blades 23 of the bladed disc component 20.

(43) The shroud component 10 and the bladed disc component 20 are then permanently joined by applying weld or braze lines, as the case may be, along opposed radial lines 33 at the interface between the spokes 13a-f and the corresponding spoke-receiving recesses 26a-f.

(44) Additionally, welding or brazing can be performed at or around the interface between the axially extending surfaces 17a-f and hub recesses 30a-f.

(45) The described technique is also compatible with brazing and/or welding at the blade tip sections on or around the interface between the blades and the shroud, as done in the prior art.

(46) As a further alternative, the shroud component 10 and the bladed disc component 20 may be formed as un-sintered (or ‘green’) parts. These green parts can then be mated and subsequently fused together during a sintering process.

(47) The disclosure has been described above purely by way of example. It is intended, however, that different turbine wheels and related parts than those described herein be covered, within the scope of the appended claims.