TURBINE DISTRIBUTOR SECTOR FOR AIRCRAFT TURBOMACHINERY, WITH IMPROVED ROBUSTNESS

Abstract

The invention relates to a turbine distributor sector (40) for an aircraft turbomachine, comprising a first platform (44a), a plurality of blades (42) projecting from the first platform in a first direction (S1) of a radial direction (R) of this sector, as well as a first end member (50a) projecting from the first platform (44a) in a second direction (S2) of the radial direction, opposite the first direction (S1), the first end member (50a) extending along a circumferential direction (C) of the sector. According to the invention, the sector comprises at least one first mechanical unloading notch (66a) made through the first end member (50a), each first notch (66a) having a radial notch bottom (68a), as well as a radial notch opening (70a) spaced from the radial notch bottom (68a) in the second direction (S2). Figure for abstract: Fig. 3

Description

Title of the invention: TURBINE DISTRIBUTOR SECTOR FOR AN AIRCRAFT TURBOMACHINE, WITH IMPROVED ROBUSTNESS Technical field

[0001] The present invention relates to an aircraft turbomachine, preferably of the turbojet or turboprop type.

[0002] More particularly, the invention relates to the design of a turbine distributor of an aircraft turbomachine, such a distributor being for example known from document FR 2 825 748 A1. State of the prior art

[0003] A turbine distributor of an aircraft turbomachine is generally produced using several distributor sectors, arranged end to end in the circumferential direction. Each sector usually comprises two platforms between which blades are arranged, spaced circumferentially from each other within the sector. Each of the two platforms has a radial delimiting surface of a primary vein of the turbomachine, making it possible to channel a primary flow passing through the turbine, and coming from the combustion chamber.

[0004] Furthermore, on the side radially opposite that of the radial delimiting surface of the primary vein, each platform carries one or more projecting end members. Each projecting end member extends circumferentially, generally over the entire length of the sector. It may, for example, be a lug for attaching the distributor sector to the turbine casing, or a support leg, for example for supporting a sealing member, of the abradable type.

[0005] Within the distributor sector, each platform and its projecting end member(s) together form a radial end structure, subject to significant thermal stresses. Indeed, on the side of the radial delimitation surface of the primary stream, this surface is directly exposed to a very high temperature which comes from the primary flow, while on the opposite side of this radial end structure, the temperature is usually much lower. This latter observation is explained not only by the radial distance from the primary stream, but also by the possible proximity of one or more cooling air cavities.

[0006] Each radial end structure therefore has a high temperature gradient in the radial direction, which may cause a harmful effect for the distributor sector, known as the "bimetallic strip effect". It is characterized by a different thermal expansion ential, between the two aforementioned sides of each radial end structure. On the side of the radial delimitation surface of the primary vein, the elongation of the structure is greater than on the opposite side, called the cold side. The bimetallic effect then materializes by the appearance of high mechanical stresses within the radial end structure, which tends to deform by bending. The blades of the distributor sector being connected to the two radial end structures, they also undergo strong mechanical stresses, by countering the deformation of these radial end structures. Due to the nature of the deformation of these two structures, the blades located at the circumferential ends of the sector are mainly subjected to tensile forces, while the blades located more in the center of the sector are essentially subjected to compressive forces between the two radial end structures.

[0007] These constraints on the blades of the distributor sector have a significant impact on the service life of the sector, in particular due to the risk of cracks appearing on the blades located at the circumferential ends.

[0008] To address this problem, it is possible to use materials that are more resistant to fatigue and / or fining, so as to reinforce the mechanical robustness of the distributor sector. However, this solution proves to be particularly expensive. Another solution lies in the production of distributor sectors with reduced circumferential amplitude, in order to limit the aforementioned bimetallic effect. However, this solution remains penalizing in terms of time and assembly costs of the distributor, as well as increasing the leakage sections between the sectors in greater number.

[0009] There therefore remains a need to optimize turbine distributor sectors, aimed at strengthening their mechanical robustness, while controlling assembly and manufacturing costs. Statement of the invention

[0010] To meet the need expressed above, the invention firstly relates to a turbine distributor sector for an aircraft turbomachine, comprising a first platform, a plurality of blades projecting from the first platform in a first direction of a radial direction of this sector, as well as a first end member projecting from the first platform in a second direction of the radial direction, opposite the first direction, the first end member extending along a circumferential direction of the sector.

[0011] According to the invention, the distributor sector comprises at least one first mechanical unloading notch made through the first end member, each first notch having a radial notch bottom, as well as a radial notch opening spaced from the radial notch bottom in the second direction.

[0012] Thanks to the presence of one or more mechanical unloading notches, the first end member is segmented into several circumferential portions, thus giving it a certain flexibility of deformation. This flexibility of the coldest side is used to accompany the thermal expansion of the hottest side of the first platform. Advantageously, this makes it possible to drastically reduce the bimetallic effect described above. The deformation to be countered by the blades of the sector is therefore reduced, so that these blades are less mechanically stressed. They can consequently have an increased service life, and require fewer maintenance / replacement operations of the distributor sector.

[0013] In other words, the presence of the mechanical unloading notches makes it possible to limit the variations in curvature between the cold and hot parts of the radial end structure, formed by the first platform and each first end member associated with it. This results in a lower stress on the blades of the distributor sector, the mechanical strength of which is advantageously improved.

[0014] Furthermore, the solution provided makes it possible to further standardize the behavior and stresses of all the blades of the same distributor sector. Moreover, the number of blades per sector can be increased, which advantageously reduces the number of sectors to be assembled end to end in the circumferential direction. Assembly times and costs are therefore reduced, as are aerodynamic performances, due to the reduction in the number of leakage sections per crown. In addition, when the end member is intended to bear on a casing element of the turbine, the contact forces are better distributed on the latter, advantageously leading to a reduction in the risk of matting and leaks at the interfaces. Thanks to this more homogeneous distribution of forces on the casing element, the wear of the latter is reduced, and the risks of tilting of the sector, resulting from such wear, are also reduced.By reducing the sector rocking effect, resulting from wear of the casing element, the distributor sector blades remain in an optimal position with respect to the primary flow, implying increased performance for the turbine.

[0015] Finally, this solution makes it possible to consider the use of less noble materials for the manufacture of the distributor sector, and it also provides mass savings. As such, the invention therefore corresponds to a result of technological research aimed at significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of these aircraft (decarbonization).

[0016] The invention preferably provides at least any one of the following optional technical features, implemented in isolation or in combination.

[0017] Preferably, each first notch opens axially on either side of the first end organ.

[0018] Preferably, each first notch has a radial depth greater than at least 20% of a maximum radial length of the first end member, and more preferably greater than at least 50%, or even 70% of this maximum radial length, while preferably remaining strictly less than this maximum radial length.

[0019] Preferably, the first end member is one of the elements among which:

[0020] - a hooking tab of the distributor sector;

[0021] - a support leg, preferably supporting a sealing member. Al Alternatively, the support leg can be replaced by a leg connecting to another mechanical structural component, such as flange clamps.

[0022] Preferably, the first end member comprises a core projecting from the first platform, as well as a sole carried by the core at a distance from the first platform, each first notch radially passing through the entirety of the sole, and preferably at least part of the core.

[0023] Preferably, the first notch has a circumferential width which narrows from the radial notch bottom to the radial notch opening.

[0024] Preferably, the dispenser sector comprises at least one sealing tab closing at least a portion of the first discharge notch. This advantageously reduces leakage through the discharge notch.

[0025] Preferably, the distributor sector comprises a second platform from which the blades project in the second direction of the radial direction, as well as a second end member projecting from the second platform in the first direction, the second end member extending along the circumferential direction of the sector. In addition, the sector also comprises at least one second mechanical unloading notch made through the second end member, each second notch having a radial notch bottom, as well as a radial notch opening spaced from the radial notch bottom in the first direction. In this regard, it is specified that all the optional features, described previously for the first end member and its first unloading notch(s), are applicable to the second end member and its second unloading notch(s).

[0026] The invention also relates to a turbine distributor for an aircraft turbomachine, comprising at least one such distributor sector, and preferably several of these sectors arranged end to end in the circumferential direction.

[0027] Finally, the invention relates to an aircraft turbomachine, comprising at least one such turbine distributor, for low pressure or high pressure turbine.

[0028] Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows. Brief description of the drawings

[0029] The following detailed description refers to the attached drawings in which:

[0030] [Fig-1] is a schematic axial sectional view of a turbojet according to the invention

[0031] [Fig.2] is an axial half-sectional view of a portion of a turbine stage of the tur- machine shown in the preceding figure, the turbine stage comprising a distributor in the form of a preferred embodiment of the invention;

[0032] [Fig.3] is an enlarged perspective view of a distributor sector, forming part of the distributor shown in [Fig.2];

[0033] [Fig.4] is a sectional view of a portion of the sector shown in [Fig.3], showing more specifically a first mechanical unloading notch;

[0034] [Fig.5] is a sectional view of a portion of the sector shown in [Fig.3], showing more specifically a second mechanical unloading notch;

[0035] [Fig.6] is a perspective view of part of the sector shown in [Fig.3], showing more specifically a first mechanical unloading notch, closed by sealing tabs;

[0036] [Fig.7] is a sectional view of the portion of the sector shown in [Fig.6], the sectional plane passing through the sealing tabs;

[0037] [Fig.8] is a perspective view of a portion of the sector shown in [Fig.3], showing more specifically another first mechanical unloading notch, closed by sealing tabs;

[0038] [Fig.9] is a sectional view of the portion of the sector shown in [Fig.8], the sectional plane passing through the sealing tabs. Detailed description of embodiments

[0039] The figures include a reference frame L, R and C respectively defining longitudinal, radial and circumferential directions orthogonal to each other, these directions corresponding to those of an aircraft turbojet engine 1 according to the invention.

[0040] [Fig.l] shows the aircraft turbojet engine 1, preferably having a twin-spool, twin-flow design. However, other types of turbojet engines are possible, as are turbomachines other than turbojets, such as turboprops.

[0041] Subsequently, the terms “upstream” and “downstream” are defined with respect to a main direction DI of gas flow through the turbojet 1, when the latter is in direct thrust operation. The direction DI is parallel to the longitudinal direction L, and also parallel to a longitudinal axis A1 of the turbojet, around which its various components extend. In this case, from upstream to downstream of the turbojet 1, these are a fan 4, a low-pressure compressor 5, a high pressure compressor 6, a combustion chamber 7, a high pressure turbine 8 and a low pressure turbine 9.

[0042] During operation of the turbojet engine 1, an air flow 10 enters the turbojet engine 1 through an air inlet 3, passes through the fan 4, and then divides into a central primary flow 10A and a secondary flow 10B. The primary flow 10A flows in a main gas circulation vein 11A passing through the compressors 5 and 6, the combustion chamber 7, and the turbines 8 and 9. The secondary flow 10B flows in a secondary vein 11B surrounding the main vein 11A, also called the primary vein, or aerodynamic flow vein.

[0043] In a manner known per se, a turbine such as the high-pressure turbine 8 or the low-pressure turbine 9 comprises one or more stages 12. Each stage 12 comprises a stator assembly 12A comprising a distributor 29, also called a stator bladed ring, and a moving wheel 12B, arranged directly downstream of the assembly 12A. Such a stage 12 is shown in [Fig.2].

[0044] Referring now to Figures 2 to 5, the turbine distributor 29 will be described, here preferably integrated into the high-pressure turbine 8, and centered on the axis AL. The distributor 29, in the form of a crown, is crossed in its center by one or more drive shafts 30, also centered on the axis AL.

[0045] The distributor 29 is made up of several distributor sectors 40, arranged end to end along the circumferential direction C. Each sector 40, corresponding to an angular sector of the crown, comprises two platforms between which blades 42 are arranged, circumferentially spaced from each other within the sector. The sector 40 may, for example, comprise a number of blades 42 of between two and ten. Only one of the sectors 40 will be described below, but it is noted that the other sectors 40 of the crown may have an identical or similar design.

[0046] The two platforms of the sector 40 correspond respectively to a radially external platform, called the first platform 44a, as well as to a radially internal platform, called the second platform 44b. A reverse arrangement is also conceivable, without departing from the scope of the invention.

[0047] The blades 42 are thus projecting from the first platform 44a in a first direction SI of a radial direction R of the sector, while these same blades 42 are projecting from the second platform 44b in a second direction S2 of the radial direction R, opposite to the first direction SL. Here, the first direction SI of the direction R goes radially from the outside to the inside, and vice versa for the second direction S2.

[0048] The first platform 44a comprises two opposite surfaces in the radial direction R, namely a first radial delimitation surface 46a of the primary vein 1 IA oriented in the direction SI, as well as a first external surface 48a of the sector, oriented in the direction S2. Similarly, the second platform 44b comprises two opposite surfaces in the radial direction R, namely a second radial delimiting surface 46b of the primary vein 1 IA oriented in the direction S2, as well as a second external surface 48b of the sector, oriented in the direction SI.

[0049] The distributor sector 40 comprises, at a radial end thereof, at least one first end member 50a, projecting from the first outer surface 48a, in the second direction S2 of the direction R. Each first end member 50a preferably extends along the circumferential direction C of the sector 40, and more preferably all along the latter. These are two tabs 50a for attaching the distributor sector 40 to one or more turbine casing elements 52, as shown in [Fig. 2]. These hooking lugs 50a cooperate in a conventional manner with associated hooks provided on the turbine casing elements 52. The upstream hooking lug 50a has a hook shape towards the upstream, while the other downstream hooking lug 50a has a hook shape towards the downstream.Between these legs 50a, for example, a cooling air cavity 54 is defined, delimited radially inwardly by the first outer surface 48a of the first platform 44a. It is noted that this first platform 44a forms, with the two hooking legs 50a, a first radial end structure, subject to differential thermal expansion for the reasons explained previously. In this regard, it is noted that the hooking leg(s) 50a could not be hook-shaped, and have a simpler shape serving to press their end against the casing.

[0050] Similarly, the distributor sector 40 comprises, at a radial end thereof, at least one second end member 50b projecting from the second outer surface 48b, in the first direction SL. Each second end member 50b preferably extends along the circumferential direction C of the sector 40, and more preferably all along the latter. This is a leg 50b supporting an abradable 56 of a labyrinth seal type seal, as shown in [Fig.2]. The support leg 50b radially crosses a free space defined between two axial spoilers 58 provided respectively on the two mobile turbine wheels 12B located on either side of the distributor 29. Also, at least a part of this leg 50b is housed in a cooling air cavity 60, and / or participates in delimiting one or more cavities of this type.Alternatively, the support leg 50b could be replaced by a leg connecting to another structural part, for example by being inserted into a flange clamp.

[0051] It is noted that the second platform 44b forms, with the support leg 50b, a second radial end structure, also subject to differential thermal expansion, for the reasons explained previously.

[0052] As best seen in [Fig. 4], each attachment lug 50a comprises a core 62a projecting in the direction S2 from the first outer surface 48a of the first platform 44a. This core 62a is radially oriented, or inclined relative to the radial direction. In addition, each attachment lug 50a also comprises a sole 64a carried by the core 62a, at a distance from the platform, and axially or substantially axially oriented. The core 62a and the sole 64a together constitute a member with a generally L-shaped section, the angle between the core and the sole possibly being of the order of 90°, or of a higher value, for example of the order of 100 to 150°, as is the case for the upstream member 50a.

[0053] Similarly, as best seen in [Fig. 5], the support leg 50b comprises a core 62b projecting in the direction SI from the second outer surface 48b of the second platform 44b. This core 62b is radially oriented, or substantially radially oriented. In addition, the support leg 50b may also comprise a sole 64b carried by the core 62b, at a distance from the platform, and axially or substantially axially oriented. The core 62b and the sole 64b together constitute a member with a generally T-shaped section, the angle between the core and the sole being able to be of the order of 90°, or of a different value.

[0054] In order to avoid or significantly limit the bimetallic effect described above on the two radial end structures of the distributor sector 40, one of the particular features of the invention lies in the production of one or more mechanical unloading notches.

[0055] More precisely, as can be seen in [Fig. 3], each hooking tab 50a is crossed by at least one first mechanical unloading notch 66a, and preferably by several notches 66a spaced circumferentially from each other. Each first notch 66a has a radial notch bottom 68a, as well as a radial notch opening 70a spaced from the radial notch bottom 68a in the second direction S2.

[0056] Each first notch 66a is a through notch, in the sense that it opens axially on either side of the attachment tab 50a on which it is made. Here, each notch 66a radially passes through the entirety of the sole 64a, and preferably at least a portion of the core 62a, on which the radial notch bottom 68a is therefore located.

[0057] The first notches 66a provided on one of two hooking tabs 50a may be circumferentially offset relative to the first notches 66a provided on the other of the two hooking tabs 50a.

[0058] Similarly, the support leg 50b may be crossed by at least one second mechanical unloading notch 66b, and preferably by several notches 66b spaced circumferentially from each other. Each second notch 66b has a radial notch bottom 68b, as well as a radial notch opening 70b spaced from the radial notch bottom 68b in the first direction SI.

[0059] Each second notch 66b is a through notch, in the sense that it opens axially on either side of the support leg 50b on which it is made. Here, each notch 66b radially crosses the entirety of the sole 64b, and preferably at least a portion of the core 62b, on which the radial notch bottom 68b is therefore located.

[0060] Whatever the notch concerned 66a, 66b, it has a radial depth Pr greater than at least 20% of a maximum radial length Lrmax of its associated end member 50a, 50b, and more preferably greater than at least 50%, or even 70% of this maximum radial length Lrmax. However, the radial notch depth Pr, measured in the radial direction R between the bottom 68a, 68b and the point of the radial notch opening 70a, 70b furthest from this bottom in this direction R, preferably remains strictly less than this maximum radial length Lrmax, also measured in the direction R, from the outer platform surface 48a, 48b.

[0061] It is noted that the radial depth Pr of the notches 66a, 66b preferably remains greater than or equal to the thickness of the flanges 64a, 64b, when such flanges, usually of axial or substantially axial orientation, are provided. In other words, each notch 66a, 66b extends sufficiently deeply to pass through at least the flange 64, 64b, and preferably also at least a portion of the core 62a, 62b.

[0062] The number of notches 66a, 66b per member 50a, 50b may vary, for example from two to ten, depending on the circumferential length of the sector 40.

[0063] The shape of the notches 66a, 66b can be adapted according to the needs and constraints encountered. For example, as shown in one of the first notches 66a of [Fig. 3], its circumferential width Le narrows from the radial notch bottom 68a to the radial notch opening 70a. This principle can be applied to some or all of the mechanical unloading notches 66a, 66b.

[0064] As indicated previously, the presence of the mechanical unloading notches 66a, 66b makes it possible in particular to limit the variations in curvature between the cold and hot parts of each of the two radial end structures, formed by the platform 44a, 44b and its end member 50a, 50b associated with it. This results in a lower stress on the blades of the distributor sector, the mechanical strength of which is advantageously improved, and the service life increased. Indeed, thanks to the presence of the mechanical unloading notches, the end members 50a, 50b are each segmented into several circumferential portions, thus giving them a certain flexibility of deformation. This flexibility of the colder side is used to accompany the thermal expansion of the hotter side of the platforms 44a, 44b. The bimetallic effect described previously is thus largely reduced. In addition, the solution according to the invention makes it possible to further standardize the behavior and stresses of all the blades 42 of the same sector 40. The number of blades 42 per distributor sector 40 can thus be increased, which reduces the number of sectors to be assembled end to end in the circumferential direction C. Assembly times and costs are therefore reduced, as are aerodynamic performances, due to the reduction in the number of trailing sections per crown.

[0065] In addition, with the first end members 50a bearing on the casing elements 52 of the turbine, the contact forces are better distributed over these elements 52, advantageously resulting in a reduction in the risk of matting and leaks at the interfaces with the sector 40. Thanks to this more homogeneous distribution of forces on the casing elements 52, the wear of the latter is reduced, and the risks of tilting of the sector, resulting from such wear, are also reduced. By reducing the tilting effect of the distributor sector 40, the blades 42 of the distributor sector 40 remain in an optimal position with respect to the primary flow, implying increased performance for the turbine.

[0066] Referring now to Figures 6 and 7, there is shown the upstream hooking tab 50a, within which one or more of the discharge notches 66a is at least partially closed by a sealing tab, in order to prevent leaks through these notches.

[0067] In the embodiment shown, two sealing tabs 72, 74 are provided for each notch 66a. The tab 72 is dedicated to closing the part of the notch 66a through the core 62a, while the other tab 74 is dedicated to closing the part of the notch 66a through the sole 64a. Each of these tabs 72, 74 is guided and held at its two opposite circumferential ends in slots in the form of rails 76, made in the opposite circumferential sides of the notch 66a.

[0068] Here, the tongue 72 is for example first slid into its associated rails 76 from the outside of the sole 64a, then once at the bottom of its rails, it is the other tongue 74 which is slid into its associated rails 76 from the outside of the core 62a, also to the bottom of its rails. In the final position, the tongue 74 extends sufficiently to cover the tongue 72, and thus prevent the latter from being extracted by sliding along its rails 76. The tongue 72 therefore does not require any other means of holding it in position, while the tongue 74 can be held in its rails 76 by one or more welding points 78, one of which has been shown diagrammatically on the [Fig.7].

[0069] The tabs 72, 74 may be made of any material, chosen so that the tabs do not affect the flexibility of the radial end structure once installed. They have a thickness less than that of its associated member 50a, 50b and serve only for sealing purposes, to limit leakage through the notches 66a, 66b.

[0070] Figures 8 and 9 show another embodiment on the downstream attachment lug 50a, with a principle similar to two tabs 72, 74. The tab 74 is no longer held in its rails 76 by a weld point, but by a stop member 80 outside the sector 40, for example formed by an adjacent ferrule, or any other stator element.

[0071] Other technical solutions for holding the tabs can be envisaged, such as folding these tabs. Furthermore, it is noted that this principle of sealing tabs can also concern the notches 66b of the support leg 50b, without departing from the scope of the invention.

[0072] Of course, various modifications may be made by those skilled in the art to the invention which has just been described solely by way of non-limiting examples, and within the limits of the scope of the appended claims.

Claims

Claims

1. Turbine distributor sector (40) for an aircraft turbomachine, comprising a first platform (44a), a plurality of blades (42) projecting from the first platform in a first direction (S1) of a radial direction (R) of this sector, as well as a first end member (50a) projecting from the first platform (44a) in a second direction (S2) of the radial direction, opposite to the first direction (S1), the first end member (50a) extending along a circumferential direction (C) of the sector, characterized in that it comprises at least one first mechanical unloading notch (66a) made through the first end member (50a), each first notch (66a) having a radial notch bottom (68a), as well as a radial notch opening (70a) spaced from the radial notch bottom (68a) in the second direction (S2).

2. Distributor sector according to claim 1, characterized in that each first notch (66a) opens axially on either side of the first end member (50a).

3. Distributor sector according to claim 1 or 2, characterized in that each first notch (66a) has a radial depth (Pr) greater than at least 20% of a maximum radial length (Lrmax) of the first end member (50a), and more preferably greater than at least 50%, or even 70% of this maximum radial length (Lrmax), while preferably remaining strictly less than this maximum radial length (Lrmax).

4. Distributor sector according to any one of the preceding claims, characterized in that the first end member is one of the elements among which: - a tab (50a) for hooking the distributor sector; - a support leg (50b), preferably supporting a sealing member (56).

5. Distributor sector according to any one of the preceding claims, characterized in that the first end member (50a) comprises a core (62a) projecting from the first platform (44a), as well as a sole (64a) carried by the core at a distance from the first platform (44a), each first notch (66a) passing radially through the entirety of the sole (64a), and preferably at least part of the core (62a).

6. Distributor sector according to any one of the preceding claims, characterized in that the first notch (66a) has a circumferential width (Lr) which narrows going from the radial notch bottom (68a), to the radial notch opening (70a).

7. Dispenser sector according to any one of the preceding claims, characterized in that it comprises at least one sealing tab (72, 74) closing at least part of the first unloading notch (66a).

8. Distributor sector according to any one of the preceding claims, characterized in that it comprises a second platform (44b) from which the blades (42) project in the second direction (S2) of the radial direction (R), as well as a second end member (50b) projecting from the second platform (44b) in the first direction (SI), the second end member (50b) extending along the circumferential direction (C) of the sector, and in that it also comprises at least one second mechanical unloading notch (66b) made through the second end member (50b), each second notch (66b) having a radial notch bottom (68b), as well as a radial notch opening (70b) spaced from the radial notch bottom (68b) in the first direction (SI).

9. Turbine distributor (29) for an aircraft turbomachine, comprising at least one distributor sector (40) according to any one of the preceding claims.

10. Aircraft turbomachine (1), comprising at least one turbine distributor (29) according to the preceding claim.

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