Stator for a fluid machine, fluid machine comprising such a stator, and method of manufacturing such a stator

Abstract

A stator (1) for a fluid-driven machine (100) comprising: - a volute (11) in the form of a channel defined around the stator (1) and delimited by a side wall comprising a first bottom (111) and a second bottom (112) which define a maximum height (H) of the volute (11), the side wall also comprising an inner periphery (113) and an outer periphery (114) defining a maximum width (L) of the volute (11), - a conduit (12) connected to the volute (11) and delimiting with the volute a fluid flow circuit (5) between an inlet section (3) and an outlet section (4), - an assembly (13) of blade(s) disposed in the fluid flow circuit (5), the volute (11), the conduit (12) and the assembly (13) of blade(s) are made in a single piece by a process (200) of additive manufacturing. Abbreviated figure: Fig. 1

Description

Title of the invention: Stator for a fluid machine, fluid machine comprising such a stator, and method for manufacturing such a stator

[0001] The invention relates to a stator for a fluid machine and a fluid machine comprising such a stator. The fluid machine may be a centripetal turbomachine or a centrifugal compressor.

[0002] The invention also relates to a method of manufacturing such a stator by 3D printing. This may in particular be a method of manufacturing by selective laser.

[0003] A centripetal turbomachine or a centrifugal compressor includes in a known manner a stator and a rotor configured to be in rotational motion relative to the stator.

[0004] The stator comprises a volute and a conduit connected to the volute. The volute and the conduit define a fluid flow circuit between an inlet section and an outlet section. The flow circuit is provided with a set of blade(s).

[0005] In particular, the volute is in the form of a spiral channel defined around a principal axis of the stator and comprises a first bottom and a second bottom opposite the first bottom in a direction parallel to the principal axis. The conduit extends along the principal axis.

[0006] These various stator elements, namely the volute, the conduit, and the blade assembly(ies), represent a significant portion of the manufacturing cost of a radial turbomachine. Indeed, these stator elements, and in particular the volute, have a complex shape whose manufacture requires very high precision and highly advanced techniques.

[0007] For the most common turbochargers, particularly those used in the automotive industry, the stator elements are produced by casting. Molds are then necessary to facilitate mass production and reduce costs. Furthermore, machining may be necessary, or even essential, depending on the casting technique used and the application of the fluid machine. Forging may be considered in certain cases.

[0008] These mold preparation, molding, and grinding steps represent a significant cost that should be reduced.

[0009] For machines custom-made in small quantities, or for machines made for prototyping purposes, manufacturing by molding is not suitable, particularly when these machines are small (< 10 kW). Machining is generally preferred over molding.

[0010] Machining requires precision CNC (multi-axis) machines or electrical discharge machining (EDM) technologies. The use of these manufacturing technologies also entails a certain cost that should be reduced.

[0011] Regardless of the method used (molding followed by machining, precision machining) for manufacturing the stator components, a final assembly step is necessary. Such assembly is generally complex to perform, particularly because it must guarantee a good seal between the assembled components. To this end, specific seals and assembly methods are implemented, resulting in an increase in manufacturing costs.

[0012] In order to reduce this cost, the use of 3D printing appears to be a promising solution. However, despite the progress made in this field in recent years, a number of limitations or challenges remain to be overcome.

[0013] Among these limitations, the first is a low level of precision on parts obtained by 3D printing. Indeed, the tightest tolerances on such parts often remain greater than about 0.1 mm.

[0014] Furthermore, 3D printing manufacturing methods do not always guarantee perfect concentricity and roundness on cylindrical or conical surfaces. This is particularly the case when the manufactured parts have a relatively large diameter (over 30 mm).

[0015] Similarly, 3D printing manufacturing methods, particularly laser melting methods, have the drawback of not ensuring uniform heat distribution throughout the volume of the part being manufactured. Uneven heat distribution leads to unevenness in the parts, thus compromising the sealing of the systems into which these parts are to be integrated.

[0016] Finally, with 3D printing manufacturing methods, the construction of undercut surfaces, i.e., unsupported surfaces, is often complicated. One solution to this problem involves using supports distributed throughout the part's build area. These supports are designed to hold layers of material.

[0017] However, after forming a part by 3D printing and using supports, removing them from the resulting part can be difficult, especially when these supports are positioned at the undercut areas of the part.

[0018] One object of the invention is to remedy at least in part the disadvantages listed above.

[0019] To this end, according to a first aspect, the invention relates to a stator for a fluid machine, such as a centripetal turbomachine or a centrifugal compressor.

[0020] The stator comprises a volute and a conduit connected to the volute. The conduit and the volute define a fluid flow circuit between an inlet section and an outlet section. The stator also comprises a set of blade(s) arranged within the fluid flow circuit.

[0021] In particular, the volute is in the form of a channel defined around a main axis of the stator and delimited by a lateral wall. The conduit extends along the main axis of the stator.

[0022] The side wall of the volute comprises a first bottom and a second bottom opposite the first bottom in a direction parallel to the main axis. The side wall of the volute also comprises an inner periphery adjacent to the main axis and an outer periphery opposite the inner periphery in a direction perpendicular to the main axis.

[0023] The first and second bottoms define a maximum height of the volute. The inner and outer peripheries define a maximum width of the volute.

[0024] According to this first aspect of the invention, the volute, the conduit, and the blade assembly(ies) are produced in a single piece by an additive manufacturing process. Furthermore, the ratio between the maximum width and the maximum height of the volute's side wall is less than or equal to 30%. Finally, except for a portion of the second bottom and a portion of the first bottom, each having a chord length less than or equal to 70% of the maximum width, any plane tangent to the volute's side wall forms an angle of less than 45° with the stator's main axis.

[0025] By “chord”, we mean the distance between the ends of the first base (respectively second base). Furthermore, by “tangent plane” we mean a tangent plane defined with respect to an internal face of the lateral wall of the volute.

[0026] Thus, the invention according to this first aspect makes it possible to reduce the manufacturing cost of the stator by integrating the volute, the conduit, and the blade assembly(ies) into a single manufacturing process. The invention therefore eliminates the need to assemble different stator elements obtained separately, as is the case in the prior art. In this way, the invention eliminates the risk of leakage inherent in a part obtained by assembling separate elements.

[0027] Furthermore, by setting a certain maximum angle between any plane tangent to the side wall of the volute and the main axis of the stator, and by setting a chord length for the first and second ends less than or equal to a predetermined threshold value less than the maximum width of the side wall of the volute, the invention eliminates the risk of sagging of any of these ends during the manufacturing of the stator by 3D printing. Each of the ends is thus self-supporting.

[0028] Furthermore, embodiments of the invention according to this first aspect of the invention may include one or more of the following features: - the volute delimits a volume intended for the passage of fluid and housing a set of reinforcement(s) extending between the first and second bottoms, - the reinforcements are distributed angularly within the volute around the main axis, - the conduit comprises a first end connected to the side wall of the volute and a second free end forming the stator inlet section or the stator outlet section, - the first end of the conduit is connected to the inner perimeter of the volute, - the blade assembly(ies) is located near the first end of the duct, - the blade assembly(ies) extends along a circle defined by the first end of the duct around the main axis of the stator, - the lateral wall of the volute comprises a first portion forming a loop extending around the main axis, and a second straight portion tangent to the first portion, - the second portion forms the input or output section of the stator, - the lateral wall of the volute has a variable cross-section along a guideline of the lateral wall of the volute, - the maximum height and / or maximum width of the side wall of the volute are variable along the guideline. - the cross-section of the lateral wall of the volute has a general elliptical shape with a major axis corresponding to the maximum height and a minor axis corresponding to the maximum width, - the volute is equipped with a base extending from the first bottom in a direction parallel to the main axis and opposite to the conduit, - the base extends from the first portion of the volute's lateral wall along a circle defined by the guideline, - the volute, the conduit and the blade assembly(ies) form the first part of the stator, - The stator includes a second part designed to cooperate with the first part to allow the mounting of a rotor within the stator. - The first and second parts of the stator are made separately, - the second part of the stator is configured to be received in an opening formed by the base, - the stator includes a seal positioned between the first part and the second part, - the first part and the second part of the stator are made in one piece by the additive manufacturing process. - the cross-section of the lateral wall of the volute has a characteristic dimension that varies along the guideline, - the volute is equipped with a base extending from the first bottom in a direction parallel to the main axis and opposite to the conduit, - the base extends from the first portion of the volute's lateral wall along a circle defined by the guideline, - the volute, the conduit and the blade assembly(ies) form the first part of the stator, - The stator includes a second part designed to cooperate with the first part to allow the mounting of a rotor within the stator. - The first and second parts of the stator are made separately, - the second part of the stator is configured to be received in an opening formed by the base. - the stator includes a seal positioned between the first part and the second part, - the first part and the second part are made in one piece by the additive manufacturing process.

[0029] According to a second aspect, the invention relates to a fluid machine comprising a stator according to any one of the embodiments of the first aspect described above. The machine also comprises a rotor disposed inside the stator.

[0030] According to a third aspect, the invention relates to a method for manufacturing a stator by 3D printing according to any one of the embodiments of the first aspect described above.

[0031] Furthermore, embodiments according to this third aspect of the invention may include one or more of the following features: - the process includes a 3D printing manufacturing step of a blank having a shape similar to that of the finished stator and an average thickness greater than that of the finished stator, - The process also includes a step of grinding the blank to achieve a desired average thickness on the finished stator, - the rough includes a preform of the volute, a preform of the conduit, and a preform of the blade assembly(ies). - the preform of the conduit is provided with an extension along the main axis, the extension being configured to facilitate handling of the blank during the grinding stage. - the blank manufacturing stage includes an operation to determine a chord of a first base and a chord of a second base of the volute preform as a function of an average thickness of a wall delimiting the volute preform, - The blank manufacturing stage includes an operation to determine a chord of a first bottom and a chord of a second bottom of the volute preform according to parameters of the additive manufacturing process, such as the orientation of a laser beam relative to a powder bed, the melting temperature of the powder, - The blank manufacturing stage includes an operation to determine a minimum distance between two consecutive reinforcements based on an average thickness of a wall delimiting the preform of the volute, - The blank manufacturing stage includes an operation to determine a minimum distance between two consecutive reinforcements based on a duct diameter, - The blank manufacturing stage includes an operation to determine a minimum distance between two consecutive reinforcements based on parameters of the additive manufacturing process, such as the orientation of a laser beam relative to a powder bed, the melting temperature of the powder and the material used, - The 3D printing manufacturing stage of the blank includes a layering operation of powder, including a lower layer intended to form a free end of the duct preform and an upper layer intended to form a first base of the volute preform, - the lower layer is formed before the upper layer so that at the end of the blank manufacturing stage, the preform of the conduit is turned downwards and the preform of the volute is turned upwards.

[0032] Other features and advantages will become apparent from the description below, made with reference to the following figures in which:

[0033] [Fig. 1] is an isometric cross-sectional view illustrating an example of a fluid machine according to a first embodiment of the invention, the machine being illustrated in a front view and comprising a stator and a rotor.

[0034] [Fig.2] is an isometric front cross-sectional view illustrating the stator of the machine represented in [Fig.1].

[0035] [Fig.3] is an isometric cross-sectional view illustrating the stator of the machine shown in [Fig.1], the stator being shown from below.

[0036] [Fig.4] is an isometric top view illustrating a second embodiment of the fluid machine according to the invention.

[0037] [Fig. 5] is an isometric cross-sectional view illustrating the stator of the machine shown in [Fig.4], the stator is illustrated from a bottom view.

[0038] [Fig.6] is an isometric cross-sectional view illustrating the stator of the machine shown in [Fig.4], the stator is illustrated in a front view.

[0039] [Fig.7] is an isometric front view illustrating a rough draft of the machine stator represented in [Fig.4], the draft being obtained by 3D printing.

[0040] [Fig.8] illustrates steps in a process for manufacturing the stator of the machine according to the invention.

[0041] With reference to [Fig. 1] and [Fig. 4], the invention relates to a fluid machine 100 such as a centripetal turbomachine or a centrifugal compressor. The machine 100 comprises a stator 1 and a rotor 2 configured to rotate relative to the stator 1. The rotor 2 is visible in [Fig. 1].

[0042] In particular, the rotor 2 comprises a set 21 of blade(s) arranged around an axis 22. The rotational movement of the set 21 of blade(s) makes it possible to accelerate the flow velocity of the fluid through the stator 1. It should be noted that the axis 22 of the rotor 2 can be connected to an actuator controlled, for example, via an electronic control system.

[0043] The stator 1 comprises a first part IA and a second part IB which cooperate to hold the rotor 2 in position within the stator 1. The second part IB has a relatively simple structure. It can be manufactured using any technique known to those skilled in the art. In contrast, the first part IA has a more complex structure. It is the subject of the present invention and the detailed description that follows.

[0044] With reference to [Fig. 3] and [Fig. 4], the first part IA of the stator 1 comprises a volute 11 and a conduit 12 connected to the volute 11. The volute 11 and the conduit 12 each define a fluid inlet section 3 or a fluid outlet section 4. Furthermore, the volute 11 and the conduit 12 together delimit a fluid flow circuit 5 within the stator 1. The flow circuit 5 is visible in particular in [Fig. 2].

[0045] The flow circuit 5 extends between the inlet section 3 and the outlet section 4. In addition, the flow circuit 5 is provided with an assembly 13 of blade(s) which can be distributed angularly around the principal axis X. The assembly 13 of blade(s) is visible in particular in [Fig. 3].

[0046] To ensure the sealing of the stator 1, particularly between the first part IA and the second part IB, the stator 1 comprises a set of seal(s) 6 (illustrated in [Fig. 1]). In particular, a first polymer seal and a second metallic seal may be provided. The material of the metallic seal may be chosen according to the application. It may be indium, which retains a certain flexibility at cryogenic temperatures.

[0047] With further reference to [Fig. 3] and [Fig. 4], the volute 11 is in the form of a channel defined around a principal axis X of the fluid machine 100. The channel is delimited by a lateral wall which defines a first volume 5a of the flow circuit 5. In the illustrated example, the volute 11 extends in a spiral around the principal axis X.

[0048] In more detail, the side wall of the volute 11 comprises a first portion lia which extends in a closed loop around the main axis X, and a second portion 11b which is straight and tangent to the first portion 1la. The second portion 11b forms the inlet section 3 (in the case of a turbine) or the outlet section 4 (in the case of a compressor).

[0049] Furthermore, the lateral wall of the volute 11 has a first bottom 111 (called the base) and a second bottom 112 opposite the first bottom 111 along a direction parallel to the principal axis X. The first bottom 111 and the second bottom 112 define a maximum height H of the lateral wall of the volute 1. The second bottom 112 is convex. It is said to be suspended relative to the first bottom 111.

[0050] By “sustentation,” we mean the fact that the second bottom 112 is located at a certain distance from the first bottom 111, and that its projection onto the latter is not reduced to a single point. In other words, when virtually isolated from the rest of the lateral wall of the volute 1, the second bottom 112 is suspended relative to the first bottom 111.

[0051] With reference to [Fig.5], the first bottom 111 is located in a principal plane ir of the stator 1. In addition, the first bottom 111 defines a crown 111a formed by the first portion 1 la of the lateral wall of the volute 11.

[0052] It should be noted that the principal plane ir of the stator 1 is perpendicular to the principal axis X. In addition, the principal plane ir of the stator 1 contains a spiral-shaped guideline D.

[0053] With further reference to [Fig. 1] and [Fig. 2], the side wall of the volute 11 has an inner perimeter 113 adjacent to the principal axis X and an outer perimeter 114 opposite the inner perimeter 113 in a direction perpendicular to the principal axis X. The outer perimeter 114 surrounds the inner perimeter 113. The inner perimeter 113 and the outer perimeter 114 define a maximum width L of the side wall of the volute 11.

[0054] In more detail, the inner perimeter 113 of the lateral wall of the volute 11 is formed by the first portion 1la. Furthermore, the inner perimeter 113 of the lateral wall of the volute 11 is in the form of a cylindrical band defined around the principal axis X. Finally, the inner perimeter 113 of the lateral wall of the volute 11 has an opening 115 intended to ensure fluidic communication between the volute 11 and the conduit 12. The opening 115 is visible in [Fig.1].

[0055] In the illustrated example, the opening 115 extends along the entire length of the inner perimeter 113 of the lateral wall of the volute 11. In addition, the opening 115 is formed near the first bottom 111.

[0056] The outer edge 114 of the side wall of the volute 11 is in the form of a band that is folded back on itself to describe a shape of “6”. Part of the outer edge 114 of the side wall of the volute 11 is formed by the first portion 1a of the volute 11. Another part of the outer edge 114 of the side wall of the volute 11 is formed by the second portion 11b of the side wall of the volute 11.

[0057] With reference to [Fig.4], the volute 11 can be provided with a block 116 intended to receive various probes (pressure, temperature, rotation speed) in the volume 5a delimited by the lateral wall of the volute 11. Advantageously, this block 116 is formed at the level of the second bottom 112 of the lateral wall of the volute 11.

[0058] With reference to [Fig. 5], the side wall of the volute 11 has a cross-section G (also called a generatrix) which can be closed or semi-closed. In other words, the side wall of the volute 11 is generated by the path of the generatrix G along the guideline D defined in the principal plane ir of the stator 1.

[0059] The generatrix G can have a variable characteristic dimension along the guideline D. The characteristic direction can here be the maximum height H of the side wall of the volute 11, or the maximum width L of the side wall of the volute 11.

[0060] With reference to [Fig. 1] to [Fig. 4] and [Fig. 6], the conduit 12 extends along the principal axis X of the stator 1. Furthermore, the conduit 12 delimits a second volume 5b of the flow circuit 5. The second volume 5b communicates with the first volume 5a delimited by the lateral wall of the volute 11. Finally, the conduit 12 has a first end 121 and a second free end 122.

[0061] In the example illustrated in particular in [Fig. 2] and [Fig. 6], the conduit 12 generally has a flared shape at the ends 121, 122. In particular, the first end 121 of the conduit 12 is connected to the inner circumference 113 of the volute 11. Moreover, the first end 121 forms a ring that extends parallel to the first bottom 111. This ring carries the blade assembly 13. Furthermore, the second end 122 forms the inlet section 3 or the outlet section 4 of the stator 1.

[0062] As illustrated in [Fig.1], [Fig.2], and [Fig.6], the side wall of the volute 11 is advantageously provided with a base 14.

[0063] In particular, the base 14 extends from the first bottom 111 in a direction parallel to the main axis X and opposite to the conduit 12. More specifically, the base 14 extends from the ring 111a defined by the first bottom 111. Furthermore, the base 14 has an outside diameter greater than the outside diameter of the first portion 1a of the volute 11. Finally, the base 14 forms an opening intended to receive the second part IB of the stator 1.

[0064] According to a first embodiment of the invention, the volute 11, the conduit 12 and the assembly 13 of blade(s) are made in a single piece obtained by an additive manufacturing process 200.

[0065] Thus, the invention reduces the manufacturing cost of the stator 1 by integrating the volute 11, the conduit 12, and the blade assembly 13 into a single manufacturing process. Furthermore, the invention eliminates the need to assemble different stator components that would otherwise be obtained separately, as is the case in the prior art. In this way, the invention eliminates the risk of leakage inherent in a part obtained by assembling separate elements.

[0066] According to a second embodiment in combination with the first embodiment described above, and as better illustrated in [Fig. 2], the ratio between the maximum width L and the maximum height H of the side wall of the volute 11 is less than or equal to 30%. Furthermore, except for a portion of the second bottom 112 and a portion of the first bottom 111, each having a chord dl of length less than or equal to 70% of the maximum width L, any plane [3] tangent to the side wall of the volute 11 forms with the principal axis X an angle α less than 45° in absolute value.

[0067] By “chord”, we mean the distance between the ends of the first bottom 111 (respectively second bottom 112). Furthermore, by “tangent plane”, we mean a tangent plane defined with respect to an internal face of the lateral wall of the volute 11.

[0068] By fixing a certain maximum angle between any plane [3 tangent to the side wall of the volute 11 and the main axis X of the stator 1, and by fixing for the first end 111 and the second end 1122 a chord length dl less than the maximum width L of the side wall of the volute 11, the invention eliminates the risk of sagging of any of these ends 111, 112 during the manufacture of the stator 1 by 3D printing. Each of the ends 111, 112 is thus self-supporting.

[0069] It should be noted that for this second embodiment of the invention, different profiles can be envisaged for the generatrix G of the lateral wall of the volute 11 provided that the angle a remains less in absolute value than the predetermined maximum angle, and that the chord dl of the first bottom and the second bottom 112 remains less than or equal to the predetermined threshold value.

[0070] In the example illustrated in [Fig.2], the generatrix G has essentially the shape of a semi-open ellipse. This ellipse has a major axis which corresponds to the maximum height H, and a minor axis which corresponds to the maximum width L.

[0071] The major axis decreases along the guideline D from the second portion 11b of the volute 11 towards the first portion 1la of the volute 11. Due to this variation of the major axis along the guideline D, the second bottom 112 of the volute 11 is inclined with respect to the main plane ir of the stator 1.

[0072] According to a third embodiment of the invention in combination with the first embodiment, and as better illustrated in [Fig.6], the volute 11 is provided with a set 15 of reinforcement(s) which extends between the first bottom 111 and the second bottom 112.

[0073] Thus, the reinforcement assembly 15 is configured to support the second bottom 112 or the first bottom 111, particularly during the additive manufacturing of the stator 1. In other words, the reinforcement assembly 15 prevents any sagging of the second bottom 112 or the first bottom 111 during the additive manufacturing.

[0074] In the case of a plurality of reinforcements 15, these are arranged angularly in the circuit 5 delimited by the volute 11 and the conduit 12. A predefined minimum angular distance may be provided between two consecutive reinforcements 15.

[0075] The generatrix G of the lateral wall of the volute 11 according to this third embodiment can have a circular shape as illustrated in particular in [Fig.6], and not necessarily an elliptical shape as is the case in the second embodiment illustrated in [Fig.2].

[0076] For manufacturing the stator 1 according to any one of the embodiments described above, the invention introduces a new method 200 described below. This is a manufacturing method using 3D printing.

[0077] The process 200 includes a step S1 of manufacturing a blank 1-bis by 3D printing, which has a shape similar to that of the finished stator 1 and an average thickness greater than that of the finished stator 1. The process 200 also includes a step S3 of grinding the blank 1-bis to achieve the desired average thickness of the finished stator 1.

[0078] With reference to [Fig.7], the blank 1-bis comprises a preform 11-bis of the volute 11 and a preform 12-bis of the conduit 12. The preform 12-bis of the conduit 12 is connected to the preform 11-bis of the volute 11. The two preforms 11-bis, 12-bis delimit a preform (not illustrated) of the fluid flow circuit 5 which extends between a preform 3-bis of the inlet section 3 and a preform 4-bis of the outlet section 4.

[0079] Draft 1-bis also includes a set (not illustrated) of blade preforms 13. This set of blade preforms 13 is arranged in the circuit preform 5.

[0080] In particular, the preform 11-bis of the volute 11 comprises all the features of the volute 11 as previously described. The preform 11-bis of the volute 11 includes, in particular, a preform 14-bis of the base 14. The preform 11-bis of the volute 11 may also include a set of reinforcement preforms 15 (for the stator according to the third embodiment).

[0081] Advantageously, the preform 12-bis of the conduit 12 is provided with an extension 12a-bis which extends along a principal axis identical to the principal axis X of the finished stator 1. This extension 12a-bis is intended to facilitate handling of the blank 1-bis during the grinding step S3, for example by a chuck of a machine tool.

[0082] Advantageously, the manufacturing step of the blank 1-bis can include an operation of determining a chord of a first bottom 111-bis and a chord of a second bottom 112-bis of the preform 11-bis of the volute 11 as a function of an average thickness of a wall delimiting the preform 11-bis of the volute 11, or as a function of the parameters of the additive manufacturing process 200.

[0083] Advantageously, the manufacturing step of the blank 1-bis can include an operation to determine the minimum angular distance between two consecutive preforms of the set of reinforcement preforms 15. This minimum angular distance is determined as a function of an average thickness of a wall delimiting the preform 11-bis of the volute 11, or as a function of a diameter of the preform 12-bis of the conduit 12, or as a function of the parameters of the additive manufacturing process 200.

[0084] Among the process parameters taken into account to determine the chord of the first bottom 111-bis or the second bottom 112-bis of the preform 11-bis of the volute 11, or the minimum angular distance between two consecutive preforms of the set of reinforcement preforms 15, we can mention the orientation of a laser beam with respect to a powder bed, the melting temperature of the powder, the material of the powder, etc.

[0085] By diameter of the preform 12-bis of the conduit 12, we mean the hydraulic diameter given by Dh =4A / P where A is the cross-section of the passage of the preform 12-bis of the conduit 12 and P is the wetted perimeter of this section.

[0086] Advantageously, step SI of the 3D printing fabrication of the blank 1-bis comprises a series of operations involving the depositing of powder layers one on top of the other. Among these layers, a lower layer is intended to form a free end of the preform 12-bis of the conduit 12. An upper layer is intended to form a first bottom of the preform 11-bis of the volute 11.

[0087] The lower layer is deposited before the upper layer so that at the end of step SI of manufacturing the blank 1-bis, the preform 12-bis of the conduit 12 is facing downwards while the preform 11-bis of the volute 11 is facing upwards top. Thanks to this inverted manufacturing process, the entire set of preforms for the 13 blades is not undercut

[0088] Between step SI of manufacturing the blank 1-bis by 3D printing and step S3 of grinding the blank 1-bis, a step S2 of depowdering the blank 1-bis may be included. This involves removing the excess unmelted powder after the 3D printing step SI.

[0089] In order to facilitate this depowdering, the blank 1-bis of the stator 1 can be manufactured in two separate parts: a first part forming a preform of the first part IA of the stator 1, and a second part forming a preform of the second part IB of the stator 1.

[0090] If the depowdering does not present any difficulties, the blank 1-bis of the stator 1 can be manufactured in one piece. For this purpose, the geometry and / or the number of preforms of the blades 13 can be modified accordingly to give these preforms of the blades 13 a support function for the levitating portions.

[0091] The powder can be made of aluminum, stainless steel, Inconel (registered trademark) or titanium. The choice of material depends on the nature of the application and the physical operating conditions of the fluid-based machine (thermodynamic, thermal, mechanical and vibrational).

Claims

Demands

1. A stator (1) for a fluid-driven machine (100), such as a centripetal turbomachine or a centrifugal compressor, the stator (1) comprising: - a volute (11) in the form of a channel defined around a principal axis (X) of the stator (1) and delimited by a side wall comprising a first bottom (111) and a second bottom (112) opposite the first bottom (111) in a direction parallel to the principal axis (X), the side wall also comprising an inner periphery (113) adjacent to the principal axis (X) and an outer periphery (114) opposite the inner periphery (113) in a direction perpendicular to the principal axis (X), the first bottom (111) and the second bottom (112) defining a maximum height (H) of the volute (11), the inner periphery (113) and the outer periphery (114) defining a maximum width (L) of the volute (11), - a conduit (12) connected to the volute (11) and extending along the main axis (X),the conduit (12) and the volute (11) delimiting a fluid flow circuit (5) between an inlet section (3) and an outlet section (4), - an assembly (13) of blade(s) arranged in the fluid flow circuit (5), characterized in that the volute (11), the conduit (12) and the assembly (13) of blade(s) are made in a single piece by an additive manufacturing process (200), in that the ratio between the maximum width (L) and the maximum height (H) of the volute (11) is less than or equal to 30%, and in that, except for a portion of the second bottom (112) and a portion of the first bottom (111) each having a chord (dl) of length less than or equal to 70% of the maximum width (L), any plane (|3) tangent to the lateral wall of the volute (11) forms an angle with the principal axis (X). (a) less than 45° in absolute value.

2. Stator (1) according to the preceding claim, wherein the conduit (12) comprises a first end (121) connected to the side wall of the volute (11) and a second free end (122) forming the stator (1) input section (3) or stator (1) output section (4).

3. Stator (1) according to any one of the preceding claims, wherein the side wall of the volute (11) comprises a first portion (lia) forming a loop extending around the main axis (X), and a second portion (11b) straight and tangent to the first portion (lia), the second portion (11b) forming the inlet section (3) or the outlet section (4) of the stator (1).

4. Stator (1) according to any one of the preceding claims, wherein the side wall of the volute (11) has a cross section (G) that varies along a guide line (D) of the side wall of the volute (11).

5. Stator (1) according to any one of the preceding claims, wherein the volute (11) is provided with a base (14) extending from the first bottom (111) in a direction parallel to the main axis (X) and opposite to the conduit (12).

6. Stator (1) according to any one of the preceding claims, wherein the volute (11), the conduit (12) and the blade assembly (13) form a first part (IA) of the stator (1), the stator (1) comprising a second part (IB) intended to cooperate with the first part (IA) to enable the mounting of a rotor (2) in the stator (1).

7. Stator (1) according to the preceding claim, wherein the first part (IA) and the second part (IB) of the stator (1) are made separately.

8. Stator (1) according to any one of claims 6 or 7, comprising a seal (6) disposed between the first part (IA) and the second part (IB).

9. Stator (1) according to claim 6, wherein the first part (IA) and the second part (IB) are made in one piece by the additive manufacturing process (200).

10. Fluid machine (100), such as a centripetal turbomachine or a centrifugal compressor, comprising a stator (1) according to any one of the preceding claims and a rotor (2) disposed inside the stator (1).

11. Method (200) of manufacturing a stator (1) according to any one of claims 1 to 9 by additive manufacturing.

12. A method (200) according to the preceding claim, comprising a step (S1) of manufacturing by 3D printing a blank (1-bis) having a shape similar to that of the finished stator (1) and an average thickness greater than that of the finished stator (1), the method (200) also comprising a step (S3) of grinding the blank (1-bis) to achieve a desired average thickness on the finished stator (1).

13. Method (200) according to the preceding claim, wherein the blank (1-bis) comprises a preform (11-bis) of the volute (11), a preform (12-bis) of the conduit (12), and a preform of the blade assembly (13).

14. Method (200) according to the preceding claim, wherein the preform (12-bis) of the conduit (12) is provided with an extension (12a-bis) along the principal axis (X), the extension (12a-bis) being configured to facilitate handling of the blank (1-bis) during the grinding step (S3).

15. A method (200) according to any one of claims 13 or 14, wherein the 3D printing manufacturing step (SI) of the blank (1-bis) comprises a layering operation of powder, comprising a lower layer intended to form a free end of the preform (12-bis) of the conduit (12) and an upper layer intended to form a first bottom (111) of the preform (11-bis) of the volute (11), the lower layer being formed before the upper layer so that at the end of the manufacturing step (SI) of the blank (1-bis), the preform (12-bis) of the conduit (12) is turned downwards and the preform (11-bis) of the volute (11) is turned upwards.

Images