EP1707759A2 - Housing of a turbomachine - Google Patents

Abstract

A bridge (6) is fastened transverse to the interface (4) of two housing shells (2,3), and includes two sections (7,8) individually bolted or screwed to the shells. The bridge sections and the shells also form complementary contact surfaces (10-13) to facilitate transmission of high moments or forces.

Description

Technical area

The invention relates to a housing for a machine, in particular almost rotationally symmetrical housing, for example for a turbomachine, with a first housing shell, which is connected to a second housing shell along a parting plane, which usually goes through the machine axis (s).

State of the art

In such a housing at least one flange is formed in the region of the parting plane, with which the two housing shells are fastened to one another. Usually, this flange extends in the parting plane and forms there a broadening of the housing, which extends radially with respect to a longitudinal direction of the housing and usually extends over the entire axial length or circumference of the housing. The two housing shells are screwed directly to each other in the region of the flange, wherein the respective screw penetrates the parting plane preferably vertically.

Usually, the housing shells thus have contact surfaces which extend in the parting plane, which lie along the parting plane and which are pressed against each other within the respective flange by the respective screwing.

Furthermore, such a housing, at least in a turbomachine, such as in a turbine or a compressor, have a rotationally symmetric or nearly rotationally symmetrical shape. The radially projecting flanges are a hindrance to such a housing in two respects: on the one hand, the stiffness of the flange area relative to a bending moment in the circumferential direction, for example a thermal moment due to a radial temperature gradient across the wall, locally significantly different from the rest of the circumference, second, the additional masses and the radial extent of the flanges lead to a change in the temperature behavior of the housing in the region of the flange. Both disturbances have a detrimental effect on the deformation behavior of the housing by locally different curvatures and bends occur even when circumferentially constant pressure and / or temperature load. This gives a rotationally symmetrical housing in operation a no longer circular cross-section.

In order to keep the circumferential stiffness constant, the flanges must have a width of about 2 - 3 times the wall thickness. This is contradicted by the fact that they should ideally not protrude beyond the (rotational) contour of the rest of the housing for reasons of uniform thermal behavior as possible and reduction of the size. For these conflicting requirements, on the one hand sufficient bending stiffness in the circumferential direction and on the other hand small radial extent, can be difficult to find a satisfactory compromise with previously known design principles.

In this regard, the various known solutions of the prior art for alternative connection principles of housing flanges not a satisfactory solution in this respect, because they have mainly the goal of increasing the closing forces, partly at the cost of a lower circumferential rigidity and without regard to the necessary installation space.
So describes DE 853'451 Clamps that produce significantly higher closing forces via wedge or toggle mechanisms from relatively small horizontal clamping bolt forces. To be able to apply this closing forces without too large circumferential moments due to circumferential Wandzug and distance of the brackets of the wall center line, the flanges must be kept particularly narrow, which further reduces their circumferential stiffness, yet the necessary radial installation space is quite large.
An alternative proposal with a similar purpose is the subject of Swiss writing CH 319'355 , in which the closing forces are generated by a lever mechanism from lower bolt clamping forces. In contrast to the previous proposed solution, the circumferential rigidity is also increased because of the large radial width of the flange, but at the cost of a large space requirement with correspondingly problematic thermal behavior.
US 2'457'073 represents a combination of the two previously discussed principles: a clamp with a lever mechanism acts on a narrow nose in a cylindrical wall of nearly constant thickness. Thus, transient thermal processes are likely to produce fairly uniform temperature distributions, but the flexural rigidity at the parting plane is minimal.
US 2'276'603 also proposes brackets with a wedge mechanism to increase the searing forces, similar to the aforementioned DE 853'451 , Due to the small remaining vertical contact surfaces between the clamp and the housing half, however, the circumferential stiffening is only slight. The goal is obviously only the greater closing forces.
US 2,169,092 Finally, the use of double T-shaped shrunken tie rods instead of bolts suggests.

Overall, it should be noted that the solutions presented here are directed primarily to a sealing of the housing shells and the generation of high closing forces, the problems of circumferential rigidity and mass distribution and the risk of asymmetric deformation but ignore.
This has the inevitable consequence that a high flexural rigidity in the circumferential direction with the most even mass distribution in the flange area to ensure the highest possible rotational symmetry at high mechanical and thermal capacity is not achieved by these solutions.

But asymmetric deformation of the housing is problematic, especially in turbomachinery, since the housing is typically used to support vanes and sealing zones for blades. By an asymmetric deformation of the housing, the flow through the turbomachine is disturbed. In particular, radial gaps between the blades and the housing-side sealing zones and between the guide vanes and rotor-side sealing zones can form or increase, which leads to a flow around the blades at the tip. However, the efficiency of a turbomachine is significantly reduced when the high-energy flow flows around the blades at the tip and thereby does not transfer any work to the respective blade.

Presentation of the invention

This is where the invention starts. The invention, as characterized in the claims, deals with the problem of providing an improved embodiment for a housing of the type mentioned, in particular significantly improves the dimensional stability of the housing by the circumferential stiffness in the region of the parting plane almost constant equal to the Remainder of the housing periphery is, and at the same time the radial extent in the area the parting plane can be largely adapted to the rest of the rotational contour of the housing.

According to the invention, this problem is solved by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea, instead of the respective particular horizontal flanges to attach at least one bridge, which extends perpendicular to the parting plane and the both sides of the parting plane in each case in a corresponding bridge portion both with one housing shell and with the other housing shell firmly and bending moment stiff in Circumferential direction is connected. Such a bridge forms transversely to the parting plane an anchor which connects the two housing halves in the parting plane adjacent to each other firmly together. In this case, the local bending stiffness achievable with the aid of the bridge at the parting plane can be made almost ideally equal to the remainder of the circumference. In addition, if necessary, the tensile strength of the bridge by a corresponding dimensioning and / or additional structural elements be many times greater than in a conventional screw which penetrates the flange perpendicular to the parting plane. However, the most important feature is the bending moment stiff connection in the circumferential direction while reducing the radial extent in the parting plane.

The bridge can be screwed or otherwise connected to the respectively associated housing half at one of the bridge sections or at both bridge sections. With the aid of such a screw connection, by means of a suitable selection of the screw locations with regard to positioning and / or number and / or dimensioning, a particularly high flexural rigidity and, if necessary, can be achieved also strength for the respective connection between the respective housing shell and the respective bridge section are produced.

Likewise, it is basically possible to integrate one of the two bridge sections in the associated housing shell, that is, the bridge then forms an integral part of the respective housing shell. In this way, a fixed connection between the housing shell and the bridge formed integrally thereon or integrally or in one piece is particularly simple, and only one side of the bridge is detachably connected to the other housing shell.

Additionally or alternatively, at least one of the bridge sections may be connected via a form-locking connection with the associated housing shell. Suitable form-fitting connections are, for example, a dovetail coupling, a hammerhead coupling or a clip coupling. By positive engagement, particularly high moments and forces can be transmitted directly between the bridge and the respective housing shell, which basically can be dispensed screws for transmitting pairs of forces of circumferential moments and / or shear forces between the bridge and the respective housing shell.

Other important features and advantages of the housing according to the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

Brief description of the drawings

Fig. 1 bis 9

jeweils einen Querschnitt durch ein erfindungsgemäßes Gehäuse im Bereich der Trennebene der Gehäuseschalen bei unterschiedlichen Ausführungsformen.

Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components. Show, in each case schematically,

Fig. 1 to 9

in each case a cross section through an inventive housing in the region of the parting plane of the housing shells in different embodiments.

According to FIGS. 1 to 9, a housing 1 according to the invention comprises a first housing shell 2 and a second housing shell 3. The two housing shells 2, 3 bear against each other along a parting plane 4. The housing 1 is the housing 1 of a machine, preferably a turbomachine, such as a turbine, a gas turbine, a steam turbine, a compressor or a compressor. The housing 1 is rotationally symmetrical in the embodiments shown here. This is not obligatory. The application of this invention to other types of packages or types of machines is also possible. During operation of the respective machine, the housing 1 may be internally or externally loaded with an overpressure. Likewise, the housing 1 may be thermally loaded internally or externally. Accordingly, the housing shells 2, 3 exposed to strong deformation forces.
In order to fasten the two housing shells 2, 3 to one another, at least one bridge 6 is provided in the region of the parting plane 4. This bridge 6 is also exposed to particularly high loads due to the above-mentioned heavy loads of the housing 1. The bridge 6 can basically extend in the axial direction over the entire length of the housing 1. It is also possible to arrange several such bridges 6 in the axial direction of the housing 1 one behind the other. Furthermore, it is clear that the housing 1 in the diametrically opposite parting plane 4 can also have at least one such bridge 6.

So that the bridge 6 does not lead to an asymmetrical deformation of the housing 1 due to the occurring loads, it should have substantially the same strength and stiffness values and in particular the same thermal properties (mass, wall thickness, radial extent) as the remaining area of the housing shells 2, 3 ,
This bridge 6 extends perpendicular to the parting plane 4 and is arranged so that it penetrates the parting plane 4. Accordingly, the bridge 6 has a first bridge section 7, which is located on the same side of the parting plane 4 as the first housing shell 2. Furthermore, the bridge 6 has a second bridge section 8, which, like the second housing shell 3 on the other side of Parting level 4 is located. The first bridge section 7 is firmly connected to the first housing shell 2. The second bridge section 8 is firmly connected to the second housing shell 3.

In the embodiment according to FIG. 1, both bridge sections 7 and 8 are screwed to the associated housing shell 2, 3. Corresponding fittings 9 are indicated by dash-dotted lines in Fig. 1. The number and / or positioning and / or dimensioning of the screw 9 is selected depending on the forces and moments to be transmitted.

In order to be able to transfer particularly high moments and also forces between the bridge 6 and the housing shells 2, 3, an associated contact surface is provided on the respective bridge section 7, 8, namely a first contact surface 10 on the first bridge section 7 and a second contact surface 11 on the second bridge section 8. Complementarily, the first housing shell 2 has a first mating contact surface 12, while the second housing shell 3 has a second mating contact surface 13. In the assembled state, the contact surfaces 10, 11 lie flat against the respective mating contact surface 12, 13. The connection of the bridge 6 to the housing shells 2, 3 is expediently such that the respective contact surface 10, 11 against the respective mating contact surface 12, 13 is pressed. This is achieved in the variant of FIG. 1 by a corresponding tension between the bridge 6 and housing shells 2, 3 perpendicular to the contact surfaces 10, 11 and mating contact surfaces 12, 13, which is produced by means of the screw 9. By wide contact surfaces and increased by a multi-row arrangement of the screw a good transmission of circumferential moments is achieved even at relatively low bolt forces. The bracing additionally results in a force transmission between the contact surfaces 10, 11 and the mating contact surfaces 12, 13, ie between the housing shells 2, 3 via the bridge 6 by shear forces. In order to increase the transmittable shear forces, it may be expedient to provide the surfaces of the contact surfaces 10, 11 and / or the surfaces of the mating contact surfaces 12, 13 with an increased coefficient of friction. For example, the friction coefficients can be increased by an increased roughness of the respective surface.

In the embodiment shown here, the contact surfaces 10, 11 and the mating contact surfaces 12, 13 extend in a plane 14, which stands on the parting plane 4. In the embodiment shown here, this plane 14 is perpendicular to the parting plane 4. According to the invention are embodiments with slightly inclined contact surfaces, in particular with the symmetry plane of the housing mirror-inverted contact surfaces similar to a Aushebeschräge, in particular simplify the assembly and disassembly process (Fig. 2a and 4a).

In the embodiment according to FIG. 1, the housing shells 2, 3 in the region of the parting plane 4 are also directly connected to one another with a further screw connection, which can offer advantages in machining, assembly and operation, in particular with regard to the tightness of the housing connection. This gland is indicated by dotted lines and designated 15. In this case, this screw 15 is arranged in a conventional manner so that it penetrates the parting plane 4, preferably vertically. In order to save radial installation space and especially when the additional conventional screw only serves for machining or assembly, conventional screws and the bridges can alternate locally one behind the other in the axial direction.

Fig. 1 thus shows an embodiment in which the bridge 6 can be grown with comparatively little effort to a basically conventionally designed flange to improve in this way the rigidity of the flange 5 considerably. Such an embodiment is in particular retrofittable.

The bridge 6 can be particularly easily dimensioned so that the transferable tensile forces are significantly greater than tensile forces that can be transmitted by conventional glands. In addition, the moment stiffness is increased. At the same time, such a bridge 6 builds comparatively compact, whereby the outer contour of the housing 1 is not or only slightly disturbed in terms of its symmetry.

The bridge 6 may for example be designed as a plate. It is also possible to design the bridge 6 as a rod. In a plate-shaped bridge 6, a longitudinal dimension of the bridge 6, which is measured in the parting plane 4 and in the longitudinal direction of the housing 1, greater than a transverse dimension of the bridge 6, which is measured transversely to the parting plane 4, ie along the plane 14. A plate-shaped bridge 6 can be anchored by a corresponding number of screw 9 with sufficient strength to the housing shells 2, 3. In contrast, in the case of a rod-shaped bridge 6, the longitudinal dimension of the bridge 6 is in any case smaller than the transverse dimension of the bridge 6. The longitudinal dimension of the bridge 6 is preferably one bar-shaped bridge 6 in the region of a thickness which is measured in the parting plane 4 and transversely to the longitudinal direction of the housing 1.

According to FIG. 2, another advantageous embodiment is obtained when the position of the plane 14 is selected so that the bridge 6 is completely or almost completely within the rotationally symmetrical outer contour 16 of the housing 1. In order to achieve this shape integration of the bridge 6, a corresponding recess 20 is formed on the two housing shells 2, 3, in which the bridge 6 is inserted with their bridge sections 7, 8. The contact or mating contact surfaces 10, 11 and 12, 13 are in Fig. 2 all in one plane, which may be advantageous for processing, however, means relatively large bridges 6 in large housing radii. Alternatively, in such cases, the size of the bridge 6 can be reduced to the required for the moment and power transmission Mass by according to Fig. 2a, the contact or mating contact surfaces 10, 11 and 12, 13 are no longer left in a plane. Either the contact surfaces may indeed remain flat, but be arranged in the form of a blunt wedge or otherwise describe any mathematically continuous or discontinuous waveform, such as a circular arc.

The design of the bridge 6 preferably takes place in such a way that a substantially constant mass distribution results in the cross-section of the housing 1 in the circumferential direction of the housing 1 over the region of the parting plane 4. In this way, the housing has a substantially constant bending stiffness and moreover substantially the same thermal properties over the entire circumference, whereby a symmetrical deformation of the housing 1 is achieved particularly easily at the loads occurring during operation of the machine.

While Fig. 1 shows such an embodiment of the invention, in which the bridge 6 can be attached to a housing with a basically conventionally designed flange 5, the variants of FIG. 2 and Fig. 2a and all subsequent variants according to the invention, of common Constructions according to the prior art very different housing designs.

FIG. 3 shows a very similar embodiment to FIG. 2, in which, however, the bridge 6 is not completely integrated into the outer contour 16 of the housing 1, but projects slightly beyond the housing contour 16 in the radial direction. As a result, a little more radial space for an optimal arrangement of the screw connection and a further optimization of the bending stiffness curve is obtained at the expense of a somewhat larger installation space and a slightly deteriorated thermal behavior.

In the embodiment according to FIG. 4, the second bridge section 8 of the bridge 6 forms an integral part of the second housing shell 3. That is to say, the bridge 6 does not form a separate component in this embodiment but is in one piece or in one piece on one of the housing shells 2 or 3. here on the second housing shell 3, formed.
Similar to FIG. 2 a, the contact surface according to FIG. 4 a can also be oblique or curved in the case of the bridge 6 integrated in one of the housing shells 2 or 3.

In the embodiments of FIGS. 5 to 8 form-fitting connections 17 are provided, with the aid of which the respective bridge sections 7, 8 are fixedly connected to the associated housing shells 2, 3. In this case, these form-locking connections 17 are each designed so that they fix the two housing shells 2, 3 along the parting plane 4 adjacent to each other. The means that the positive-locking connections 17 prevent a relative movement between the two housing shells 2, 3 transversely to the parting plane 4.
Such additional form-locking connections 17 are advantageous if, in addition to the circumferential torques, even high forces have to be transmitted. In particular, they allow to dimension the screw only according to the torque transmission - which usually only relatively small bolts because of the relatively large height of the contact surfaces and thus large screw distances - without having to consider surcharges because of additional shear stress of the screws.

In detail, the variant shown in FIG. 5 is a form-locking connection 17, which represents a clamp coupling. This clip coupling has the advantage that it is radially mountable with respect to the longitudinal direction of the housing 1. In this case, end sections 18 of the bridge 6 engage over end sections 19 of the housing shells 2, 3.

In the variant according to FIG. 6, the form-locking connection 17 is designed in the manner of a dovetail coupling, with the end sections 18 of the bridge 6 also engaging behind the end sections 19 of the housing shells 2, 3. The bridge 6 shown in Fig. 6 must be mounted axially with respect to the longitudinal direction of the housing 1.

In the embodiment of FIG. 7, the positive connection 17 is designed in the manner of a hammer head coupling. Again, the end portions 19 of the housing shells 2, 3 as in the variant of FIG. 6 undercuts which engage behind the end portions 18 of the bridge 6. Again, the bridge 6 is axially mountable.
The screw 9 could basically account for this type of positive connection 17 or be further reduced, if you put either the positive connection about in the middle of the respective contact surfaces, so that the moment can be transmitted by the planar support to both sides, or by placing a second row of such compounds closer to the parting plane 4 in their place, so that the pairs of forces transmitted from the circumferential torques by suitable Ausschlussverbindungen in the radial direction over the contact surfaces can be (Fig. 7a).

In the embodiment according to FIG. 8, the form-locking connection 17 is formed by form-locking contours transmitting shear forces on the contact surfaces 10, 11 and on the mating contact surfaces 12, 13. A detail A shows a variant in which these form-fitting contours form a type of toothing, wherein the respective contact surface 10 is provided with axial rows of teeth which engage in complementary rows of teeth which are formed on the mating contact surface 12. In contrast, the detail B shows another embodiment in which the form-fitting contours are wavy. The respective contact surface 11 in this case has a multiplicity of waves which extend essentially axially and which engage in complementary waves which are formed on the associated countercontact surface 13. In this embodiment, the screw 9 are required to clamp the contact surfaces 10, 11 against the mating contact surfaces 12, 13.

It is clear that the embodiments of the form-fitting contours shown in Fig. 8 are purely exemplary, so that in principle other suitable form-fitting contours can be used.

While in the embodiments of Figs. 1 to 8, the contact surfaces 10, 11 and the mating contact surfaces 12, 13 are each in the plane 14, Fig. 9 shows an embodiment in which the contact surfaces 10, 11 and the mating contact surfaces 12, 13 a curved Have course and accordingly extend along a curve. This curvature is concave toward the interior of the housing 1. Preferably, this curvature extends Coaxial with a curvature of the housing shells 2, 3, that is coaxial with a curvature of the housing 1 in the region of Trennebebe 4. As in the variant according to FIG. 2, a recess 20 is also in the embodiment of FIG. 9 on the housing shells 2, 3 provided, in which the bridge 6 is inserted. In the present case, bridge 6 and recess 20 are also coordinated so that the bridge 6 is recessed in the recess and in particular within the outer contour 16 of the housing 1 extends.

The embodiments shown here are purely exemplary and thus without limitation of generality. Thus fall other than rotationally symmetrical housing designs as well under the invention. Although such designs with a horizontal parting plane and vertical, so vertical, arranged bridges, although a very common embodiment, while any other spatial orientation is also possible, for example, a vertical parting line and horizontal bridges.
Furthermore, it goes without saying that individual features of one embodiment can be combined with features of the other embodiments, without departing from the scope of the invention. In particular, the additional features explained with reference to FIG. 1, such as further screw connection 15, increased coefficients of friction in the contact surfaces 10, 11 and mating contact surfaces 12, 13, shaping of the bridge 6, positioning, dimensioning and number of screw connections 9, are readily apparent transferable to other embodiments.
In particular, the different form-locking connections 17 and the screw connections 9 can be combined. For example, one bridge section 7, 8 may be provided with a first form-locking connection 17, while the other bridge section 8 or 7 is fastened to the respective housing shell 2, 3 with a second form-locking connection 17 or only with screw connections 9.

LIST OF REFERENCE NUMBERS

1

casing

2

first housing shell

3

second housing shell

4

parting plane

5

flange

6

bridge

7

first bridge section

8th

second bridge section

9

screw

10

first contact surface

11

second contact surface

12

first mating contact surface

13

second mating contact surface

14

level

15

screw

16

outer contour

17

Positive connection

18

End section of 6

19

End section of 2 or 3

20

recess

Claims (10)

Housing for a machine, in particular for a turbomachine,
with a first housing shell (2) which bears against a second housing shell (3) along a parting plane (4), and wherein the two housing shell (2, 3) are fastened to one another in the region of the parting plane (4),
characterized,
in that at least one bridge (6) is arranged in the region of the separating plane (4), which extends transversely to the dividing plane (4) and which is connected to the first housing shell (2) on one side of the dividing plane (4) in a first bridge section (7) ) and on the other side of the parting plane (4) in a second bridge portion (8) with the second housing shell (3) is firmly connected. Housing according to claim 1,
characterized, - That at least one of the bridge sections (7, 8) with the associated housing shell (2, 3) is screwed, and / or - That this screw or other connection is particularly suitable for the transmission of bending moments in the circumferential direction, and / or - That one of the bridge sections (7, 8) is an integral part of the associated housing shell (2, 3), and / or - That at least one of the bridge sections (7, 8) with the associated housing shell (2, 3) via a positive connection (17) is connected, and / or - That at least one of the bridge sections (7, 8) within a cylindrical outer contour (16) of the housing (1) extends, and / or - That at least one of the bridge sections (7, 8) extends within a recess (20) formed on the associated housing shell (2, 3). Housing according to claim 1 or 2,
characterized,
that is formed on at least one of the bridge sections (7, 8) has a contact surface (10, 11) with which the bridge portion (7, 8) against an opposite contact surface (12, 13) lies flat, which at the associated housing shell (2, 3 ) is trained. Housing according to claim 3,
characterized, - That the bridge (6) is connected to the housing shells (2, 3), that the respective contact surface (10, 11) against the associated mating contact surface (12, 13) is pressed, and / or - That the respective contact surface (10, 11) and / or the associated mating contact surface (12, 13) has / have a surface with an increased coefficient of friction, and / or - That the respective contact surface (10, 11) and the associated mating contact surface (12, 13) shear forces transmitting, mutually complementary form-fitting contours, and / or - That the respective contact surface (10, 11) and the associated mating contact surface (12, 13) in a plane (14) extend, which, in particular perpendicular, on the parting plane (4), and / or - That the respective contact surface (10, 11) and the associated mating contact surface (12, 13) along a to the interior of the housing (1) out concave curvature, in particular coaxial with a curvature of the housing shells (2, 3) in the area the parting plane (4) extends. Housing according to one of claims 1 to 4,
characterized,
that the two housing shells (2, 3) in the region of the parting plane (4) are fastened to one another exclusively via the respective bridge (6). Housing according to one of claims 1 to 4,
characterized,
that the housing shells (2, 3) in the region of the parting plane (4) are additionally bolted directly together. Housing according to claim 6,
characterized,
that the respective screw (15) penetrates the parting plane (4). Housing according to one of claims 1 to 7,
characterized, - That the housing (1) is formed axially symmetrical and / or cylindrical and / or rotationally symmetrical, and / or - That the housing (1) during operation of the machine internally or externally overloaded and / or thermally loaded. Housing according to one of claims 1 to 8,
characterized, - That at least one such bridge (6) is designed as a plate whose longitudinal dimension measured in the parting plane (4) and in the longitudinal direction of the housing (1) is greater than their transversely to the parting plane (4) measured transverse dimension, and / or - That at least one such bridge (6) is designed as a rod whose measured in the parting plane (4) and in the longitudinal direction of the housing (1) Longitudinal dimension is smaller than its transversely to the parting plane (4) measured transverse dimension. Housing according to one of claims 1 to 9,
characterized,
that the housing shells (2,3) are designed in the region of the parting plane (4) and the respective bridge (6) so that over the entire casing circumference thereof an at least approximately constant mass distribution results.

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