Connecting arrangement for a turbomachine

Abstract

The present invention relates to a connecting arrangement (1) for a turbomachine (10) comprising a first component (2) with a first opening (2.1), a second component (3), and a round bolt (4). The round bolt (4) extends along a longitudinal axis (X) through the first opening (2.1) and connects the first component (2) to the second component (3) by means of a force-fit connection. Viewed in a section perpendicular to the longitudinal axis (X), a first inner circumferential surface (2.2) defining the first opening (2.1) supports an outer circumferential surface (4.1) of the round bolt (4) at at least three contact points (P1, P2, P3). The first inner circumferential surface (2.2) has a smaller radius of curvature on both sides of the first contact point (P1) than at the first contact point (P1) at least at one of the first of the at least three contact points (P1, P2, P3) with respect to a direction of rotation around the bolt longitudinal axis (X).

Description

Technical field

[0001] The present invention relates to a connecting arrangement for a turbomachine. State of the art

[0002] Turbomachinery typically consists of multiple components that are either permanently or detachably connected. For detachable connection of two components, a through-hole may be provided in each component, into which a bolt engages, thus connecting the components. These components may be flanged components, with the flanges extending radially inwards or outwards from a central axis of the turbomachine and being detachably connected, e.g., housing flanges or flanges on turbine disks of the turbomachine. The (flange) components, particularly in the area of ​​detachable connections, can be subjected to considerable forces due to mechanical and / or thermal stress, which can lead to premature component failure. Description of the invention

[0003] The present invention is based on the technical problem of providing an advantageous connecting arrangement for a turbomachine.

[0004] This is achieved according to the invention with the connecting arrangement according to claim 1. In this arrangement, viewed in a section perpendicular to the longitudinal axis of the bolt, an inner circumferential surface of a first opening supports an outer circumferential surface of a round bolt, for example with a circular cross-section, at at least three contact points; the first inner circumferential surface thus supports the outer circumferential surface of the bolt in a manner comparable to a round hole at the at least three contact points, e.g. with some clearance or in contact. In particular, the clearance between the bolt and the at least three contact points can be minimal at each (with respect to the entire circumferential area between the inner circumferential surface and the outer circumferential surface) and / or contact or contact between the inner circumferential surface and the outer circumferential surface of the bolt can exist at one, two, three or all of the at least three contact points, in particular simultaneously.In this case, the first inner circumferential surface has a smaller radius of curvature on both sides of a first contact point than at that first contact point itself. Put simply, of the at least three contact points, at least one is specially designed: in the area of ​​the first contact point, the inner surface has its smallest radius (locally speaking) at the contact point, and on both sides of this contact point, it has a larger radius (relative to the bolt's longitudinal axis).

[0005] Within the opening of the component, a notch effect can occur on its inner circumferential surface, specifically in an area with a minimal radius of curvature, which can, for example, initiate cracks. If, for instance, a tensile stress also occurs in this area with the minimal radius, the minimal radius of curvature can also locally amplify the stress, thus further intensifying the undesirable notch effect. According to the invention, to avoid this notch effect, the radius of curvature of the inner circumferential surface is smaller on at least both sides of the first contact point (which is preferably located or formed in the area of ​​maximum tensile stress on the inner circumferential surface of the opening) than at the first contact point itself. The inner circumferential surface therefore has a larger average radius in the area around the first contact point, measured relative to the longitudinal axis of the bolt, than at the contact point itself; overall, this results in a smoother radius profile or transition.

[0006] Generally, the contact point is understood to be a point of contact, viewed in a section perpendicular to the bolt's longitudinal axis, between the inner circumferential surface of the opening and the outer circumferential surface of the bolt, preferably with no play. Parallel to the bolt's longitudinal axis, this contact point forms, for example, a line on the bolt's outer circumferential surface, thus extending over a certain length. Contact between the inner circumferential surface of the opening and the outer circumferential surface of the bolt over a certain arc length (e.g., in the case of an interference or press fit, see below) can also be understood as a contact point, as long as, for example, the arc length of the contact surface at the respective contact point (or contact area) does not exceed 20% of the bolt's outer circumference (in the section perpendicular to the bolt's longitudinal axis).In the case of a planar system, the center point of each arc segment, namely its intersection with an angle bisector of the respective arc segment, is defined as the contact point.

[0007] The inventors recognized that the system, with at least three, preferably no more than four, contact points, achieves precise positioning of the round bolt relative to the first opening, while the aforementioned radius profile still allows for a tensile stress-optimized first opening. The smaller radius of curvature on both sides compared to the first contact point (i.e., the larger radius measured along the bolt's longitudinal axis), resulting in a smoother overall radius profile in the area around the first contact point, reduces the notch effect without negatively impacting the positioning of the round bolt relative to the first opening. This allows for a defined position of the round bolt relative to the first opening, as is often required, particularly in turbomachinery, while simultaneously reducing the tensile stress load on the first component.In this context, "defined" means that the bolt is held in a fixed position in the opening via the at least three contact points in directions perpendicular to the longitudinal axis of the bolt, preferably without play.

[0008] Preferred embodiments are found throughout the disclosure and particularly in the claims, whereby the description of the features does not always differentiate in detail between the different claim categories. For example, if the connection arrangement for the turbomachine is described, this is to be understood simultaneously as a disclosure for a corresponding method for producing a connection between components of the turbomachine and a corresponding use, and vice versa.

[0009] According to a preferred embodiment, the first inner circumferential surface has a smaller radius of curvature on both sides of the second contact point than at the second contact point, at least at a second of the at least three contact points, relative to a rotational direction around the longitudinal axis of the bolt. In simplified terms, the second contact point also exhibits the radius profile according to the invention; that is, the radius of curvature on both sides of the second contact point is smaller than at the contact point itself. Thus, the occurrence of local stress peaks at the at least two contact points can be reduced, and the round bolt can still be reliably positioned (relative to the first component).

[0010] According to a preferred embodiment, the first inner circumferential surface, at all contact points with the bolt when viewed in cross-section, has a smaller radius of curvature on both sides of the contact points, relative to the direction of rotation around the bolt's longitudinal axis, than at the respective contact point itself. Thus, all of the at least three contact points exhibit the radius profile according to the invention, which reduces the formation of local stress maxima and the associated undesirable notch effect at each contact point. Overall, this results in a first component optimized for tensile stress, the opening of which can nevertheless be manufactured using conventional milling methods, e.g., circular milling.

[0011] According to a preferred embodiment, viewed in a vertical section, the first inner circumferential surface of the first component supports the outer circumferential surface of the round bolt at a maximum of four contact points. Thus, there is contact between the first inner circumferential surface and the outer circumferential surface of the round bolt at at least three and at most four contact points.

[0012] According to a preferred embodiment, the first inner circumferential surface, viewed in the perpendicular section, has a superelliptical shape, namely, it satisfies the equation with respect to two perpendicular axes z,y. z a p + y b p = 1 where b − a b < 5 % and whereby p > 2 is.

[0013] The variables a and b denote the semi-axes of the ellipse; these are preferably identical, but can generally differ from each other by at most 5% (or 4%, 3%, 2%, or 1%). With increasing exponent p, the superellipse approaches a rectangle with rounded corners, the radius of curvature of these rounded corners preferably not falling below a minimum value of 50% of the radius of the round bolt.

[0014] According to a preferred embodiment, in a vertical section, the outer diameter of the round bolt is larger than the inner diameter defined by the at least three contact points. Consequently, there is an interference fit between the outer circumferential surface of the round bolt and the at least three contact points. This interference fit secures the round bolt against loosening or falling out, thus increasing the positioning accuracy of the components relative to each other during assembly and consequently simplifying the assembly process.

[0015] As will become clear in detail below, the connecting arrangement can be used for a variety of different components of the turbomachine, for example, for connecting housing flanges, such as those of a turbine, in particular a low-pressure turbine, or, for example, flanges on a turbine disk. Therefore, the invention also relates to a module for a turbomachine, which defines at least a section of a gas channel of the turbomachine, and comprises a connecting arrangement according to one of the aforementioned aspects. In this arrangement, the first contact point, with respect to a longitudinal axis of the module, is located at a radially outer or inner position.

[0016] The "module" can, for example, be part of the compressor, in which case the "gas channel" could be the compressor gas channel; alternatively, the module can be part of the turbine, in which case the gas channel could be the hot gas channel. Regardless, the module can, for example, comprise at least one stage, i.e., a guide vane ring and a rotor blade ring; typically, it can have multiple stages.

[0017] According to a preferred embodiment, the first component has a flange extending radially outwards or inwards with respect to the longitudinal axis of the module, and the first opening is provided in the flange; particularly preferably, the flange extends radially outwards. The first and / or the second component are thus designed with flanges, which extend radially outwards or inwards, particularly preferably radially outwards. If, for example, a tensile stress occurs at a radial outer edge of this flange, the opening can be provided in the flange such that at least the first contact point with the radius profile according to the invention is arranged or formed in the radially outer region of the opening.

[0018] According to a preferred embodiment, the second component has a second opening through which the round bolt at least partially passes. For example, the second component has an internal thread into which an external thread, formed at least partially on the round bolt, engages. Alternatively, the round bolt completely passes through the first opening of the first component and a second opening of the second component; these are therefore through holes.

[0019] The invention further relates to a use of the connecting arrangement according to one of the aforementioned aspects in a turbomachine, in particular a jet engine. Brief description of the drawings

[0020] The invention will be explained in more detail below using several exemplary embodiments, whereby the individual features within the scope of the dependent claims may also be essential to the invention in other combinations and no distinction will be made in detail between the different claim categories.

[0021] In detail, it shows Figure 1 is a schematic representation of a turbofan engine, illustrating an advantageous application environment; Figure 2 is a sectional view through two components along a bolt longitudinal axis; Figure 3 is a sectional view of a round bolt orthogonal to the bolt longitudinal axis with a first opening according to a first embodiment; Figure 4 is a sectional view from Figure 3 , however, with the first opening according to a second embodiment. Preferred embodiment of the invention

[0022] Fig. 1Figure 10 shows a turbomachine 10, specifically a turbofan engine, in axial section. The turbomachine 10 is functionally divided into compressor 10a, combustion chamber 10b, and turbine 10c. Both the compressor 10a and the turbine 10c are each composed of several stages. Each stage consists of a guide vane ring and a rotor blade ring, each comprising a plurality of guide vanes 15 and rotor blades 16, respectively.

[0023] In the compressor 10a, the intake air is compressed and then combusted with added kerosene in the downstream combustion chamber 10b. The connecting arrangement discussed below can be intended for use in such a turbomachine 10; it can, for example, be a module for the turbomachine 10 that defines an axial section of the gas channel 18 of the turbomachine 10, e.g., a high-pressure or low-pressure turbine module.

[0024] In Figure 1In addition, a generic housing module 17 can be identified, which in this example radially surrounds the turbine 10c with respect to a module center axis M.

[0025] Fig. 2 shows a section through two components 2, 3 along a bolt longitudinal axis X of a round bolt 4, as these can be used in the turbomachine 10.

[0026] In the example shown, the round bolt 4 is designed as a screw. Starting from a screw head 4.2, it has a cylindrical outer circumferential surface 4.1 axially adjacent to the bolt's longitudinal axis X, followed by a threaded section 4.3. The latter engages in a nut 4.4 located at an end of the round bolt 4 opposite the screw head 4.2. As a result of the nut 4.4 rotating about the bolt's longitudinal axis X and in the direction of the screw head 4.2, a force-fit connection is created with the intermediate components, namely a first component 2 and a second component 3.

[0027] Fig. 3 shows a top view of the connecting arrangement 1 in the direction of the bolt longitudinal axis X, namely in relation to Figure 2 Viewed from the left. To simplify the illustration, in Figure 3The round bolt 4 is shown cut orthogonally to its longitudinal axis X, so that its cylindrical outer circumferential surface 4.1 forms a circular disk. As in Figure 3 As can be seen, the first component 2 has a first opening 2.1 into which the round bolt 4 is inserted. Specifically, a first inner circumferential surface 2.2 defining the first opening 2.1 is such that exactly three contact points P1, P2, P3 exist between the first inner circumferential surface 2.2 and the outer circumferential surface 4.1 of the round bolt 4; thus, the first inner circumferential surface 2.2 supports the outer circumferential surface 4.1 at precisely these three contact points P1, P2, P3.

[0028] In the example shown, the round bolt 4 is inserted into the first opening 2.1 with an interference fit. Its outer diameter D1, measured in the unloaded state and at room temperature, is therefore larger than the inner diameter D2 (also measured in the unloaded state) defined by the three contact points P1, P2, P3. Such interference or interference fits are known to those skilled in the art and can be achieved, for example, by cooling the round bolt 4 significantly and heating the first component 2 before installing the round bolt 4 into the first opening 2.1. In the example shown, this is, for instance, a pairing of tolerance classes H6 / n6 according to DIN EN ISO 286-2.

[0029] Overall, it can be seen that contact between the first inner circumferential surface 2.2 of the first opening 2 and the outer circumferential surface 4.1 of the round bolt 4 occurs over a certain arc length, but this arc length is small. Furthermore, it can be seen that the first inner circumferential surface 2.2 has a smaller radius of curvature RK on both sides of the first contact point P1 (relative to a rotational direction around the bolt's longitudinal axis X) than at the first contact point P1 itself (in Figure 3 (labeled RP); the smallest radius in the area around contact point P1 (relative to the bolt's longitudinal axis X) is therefore present at this first contact point P1. Conversely, the radius of curvature RP is maximal at the first contact point P1, but smaller in the area on both sides of the first contact point P1.

[0030] In the example shown, the first component 2 is a flange 6 extending radially outwards (i.e., in the positive Y-direction) with respect to a module center axis M, in which the first opening 2.1 is provided. In the radially outer (in the Figure 3 Tensile stress forces F act on the area above, which generate a certain notch effect, particularly at the first contact point P1. The smaller radius of curvature RK in the area around the first contact point P1, compared to the radius at the first contact point P1 itself, reduces the notch effect occurring at the first contact point P1; this extends both the fatigue strength and the endurance limit of the first component 2.

[0031] Fig. 4 shows another example of the connection arrangement 1, namely a top view of the first component 2 in the direction of the bolt longitudinal axis X (similar to in Figure 3In the example shown, the first opening 2.1 (viewed in a section perpendicular to the bolt's longitudinal axis X) has the form of a superellipse, since it satisfies the equation with respect to two perpendicular axes z, y. z a p + y b p = 1 where b = a and whereby p > 2 is.

[0032] Here, the variables a and b each denote a semi-axis of the superellipse; in the example shown, these are identical.

[0033] Out of Figure 4It can also be seen that the first inner circumferential surface 2.2, which defines the first opening 2.1, supports the outer circumferential surface 4.1 of the round bolt 4 at exactly four contact points P1, P2, P3, P4. In the example shown, the outer diameter D1 of the round bolt 4 and an inner diameter D2 defined by the four contact points P1, P2, P3, P4 coincide. Nevertheless, there is a point contact (viewed in section) between the first inner circumferential surface 2.2 and the outer circumferential surface 4.1, namely at the four contact points P1, P2, P3, P4. These four contact points P1, P2, P3, P4 form a linear contact (viewed along the x-axis, which runs orthogonally to the section plane), thus extending over a certain length in the x-direction.

[0034] At each of the four contact points P1, P2, P3, P4, the first inner circumferential surface 2.2 (relative to the direction of rotation around the bolt longitudinal axis X) has a smaller radius of curvature RK on both sides of the contact points P1, P2, P3, P4 than at the respective contact point P1, P2, P3, P4 (in Figure 4 (marked RP) itself. Overall, the round bolt 4 is uniquely defined in the plane spanned by the axes z and y (i.e., the section view shown) via the four contact points P1, P2, P3, P4, and is therefore mounted without play in this plane. REFERENCE MARK LIST

[0035] Connection arrangement 1 first component 2 first opening 2.1 first inner circumferential surface 2.2 second component 3 second opening 3.1 round bolt 4 External perimeter 4.1 screw head 4.2 Threaded section 4.3 Mother 4.4 first point of contact P1 second point of contact P2 third contact point P3 Bolt longitudinal axis X Outer diameter of the bolt D1 (Inner circle diameter defined by contact points) D2 Radius of curvature at the first contact point RP Radius of curvature on both sides of the first contact point RK Turbomachine 10 compressor 10a combustion chamber 10b turbine 10c vane 15 Running shovel 16 Gas canal 17 Module center axis M

Claims

1. Connecting arrangement (1) for a turbomachine (10) comprising: a first component (2) with a first opening (2.1); a second component (3); and a round bolt (4) which extends along a bolt longitudinal axis (X) through the first opening (2.1) and which connects the first component (2) to the second component (3) in a force-fit manner, wherein, viewed in a section perpendicular to the bolt longitudinal axis (X), a first inner circumferential surface (2.2) defining the first opening (2.1) supports an outer circumferential surface (4.1) of the round bolt (4) at at least three contact points (P1, P2, P3), and wherein the first inner circumferential surface (2.2) has a smaller radius of curvature on both sides of the first contact point (P1) at at least one of the at least three contact points (P1, P2, P3) with respect to a direction of rotation around the bolt longitudinal axis (X) than at the first contact point (P1).

2. Connecting arrangement (1) according to claim 1, wherein the first inner circumferential surface (2.2) has a smaller radius of curvature on both sides of the second contact point (P2) at least at a second of the at least three contact points (P1, P2, P3) with respect to a direction of rotation around the longitudinal axis (X) of the bolt than at the second contact point (P2).

3. Connecting arrangement (1) according to claim 1 or 2, wherein the first inner circumferential surface (2.2) at all of the at least three contact points (P1, P2, P3) has a smaller radius of curvature on both sides of the respective contact point (P1, P2, P3) than at the respective contact point (P1, P2, P3) itself, with respect to a direction of rotation around the longitudinal axis of the bolt (X).

4. Connecting arrangement (1) according to one of claims 1 to 3, wherein, viewed in the vertical section, the first inner circumferential surface (2.2) of the first component (2) supports the outer circumferential surface (4.1) of the round bolt (4) at a total of no more than four contact points (P1, P2, P3, P4).

5. Connecting arrangement (1) according to one of claims 1 to 4, wherein, viewed in the vertical section, the first inner circumferential surface (2.2) has a superelliptical shape, namely, with respect to two vertical axes z, y, the equation z a p + y b p = 1 fulfilled, whereby b − a b < 5 % and whereby p > 2 is.

6. Connection arrangement (1) according to one of claims 1 to 5, wherein, viewed in the vertical section, an outer diameter (D1) of the round bolt (4) is larger than an inner circle diameter (D2) defined by the at least three contact points (P1, P2, P3) and consequently an interference fit exists between the outer circumferential surface (4.1) of the round bolt (4) and the at least three contact points (P1, P2, P3).

7. Module for a turbomachine (10) which defines at least a section of a gas channel (18) of the turbomachine (10) and has a connecting arrangement according to one of claims 1 to 6, wherein, with respect to a module longitudinal axis (M), the first contact point (P1) is arranged in a radially outer or inner position.

8. Module for a turbomachine (10) according to claim 7, wherein the first component (2) has a flange (6) extending radially outwards or inwards with respect to the longitudinal axis (M) of the module, and wherein the first opening (2.1) is provided in the flange.

9. Module for a turbomachine (10) according to claim 8, wherein the flange (6) extends radially outwards.

10. Module for a turbomachine (10) according to one of claims 7 to 9, wherein the second component (3) has a second opening (3.1) which the round bolt (4) passes through section by section.

11. Module for a turbomachine (10) according to one of claims 7 to 9, wherein the round bolt (4) completely passes through the first opening (2.1) of the first component (2) and a second opening (3.1) of the second component (3).

12. Use of a connecting arrangement (1) according to one of claims 1 to 6 in a turbomachine (10), in particular a jet engine.

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