Stator and progressing cavity pump

Abstract

The invention relates to a stator (4) for a progressing cavity pump, comprising: • a stator liner (2) cast in one piece, the stator liner comprising a sleeve (6) having a longitudinal axis (X-X), a helical inner void (18) intended to be fitted onto a rotor of the progressing cavity pump, and at least two attachment flanges (8, 10, 12, 14, 16) projecting outwards from the sleeve; • a casing comprising at least a first shell and a second shell, the first shell and the second shell each comprising a body in the shape of a cylinder portion, and at least two longitudinal edges, projecting outwards from the body, each attachment flange of the liner of the stator being inserted and compressively attached between an edge of the first shell and an edge of the second shell, the first shell being assembled and attached to the second shell.

Description

[0001] DESCRIPTION

[0002] TITLE: Progressive Cavity Stator and Pump

[0003] Technical field of the invention

[0004] The invention relates to the field of progressive cavity pumps used in the processing of complex fluids in various industrial sectors. In particular, the invention relates to a stator and a progressive cavity pump comprising such a stator.

[0005] Prior art

[0006] In a stator with an elastomer liner, the liner is firmly and permanently attached to the inner wall of the housing to prevent the rotor from rotating it. To bond the liner to the housing, the inner wall of the housing is coated with an adhesive, and then the elastomer is injected against the inner wall of the housing at high temperature and pressure. However, when the liner wears out, it is no longer possible to remove the elastomer from the housing, thus complicating any recycling process. The entire housing and liner assembly must be replaced by the customer. The housing and liner assembly is difficult to recycle because it is a composite material.

[0007] To overcome this drawback, document EP 2176552 proposes a pump with a stator made of several parts assembled together. The casing is formed by assembling several partial half-shells, and the stator is formed by assembling several molded elastomer parts. Furthermore, with a two-part stator liner, a sealing problem between the two liner parts can appear after a certain period of use or under certain operating conditions (low fluid viscosity, temperature, tangential clearance compensation, etc.), leading to the use of expensive and potentially unreliable methods to pressurize the stator liner parts against each other.

[0008] Presentation of the invention The present invention has as its primary aim to offer a more ecological stator which is less expensive to maintain because the liner can be changed very easily when it is worn without changing the casing.

[0009] The present invention has a second objective of proposing a stator that can adapt to changes in the temperature of the pumped fluid without requiring complete disassembly of the stator and the purchase and storage of several rotors having different diameters.

[0010] The present invention has as its third objective to maintain the pumping efficiency of the stator even when the stator jacket is partially worn.

[0011] Summary of the invention

[0012] The present invention relates to a stator comprising:

[0013] - a stator liner for a progressive cavity pump, the stator liner being molded in one piece, the stator liner comprising a sleeve having a longitudinal axis, an internal helical recess intended to be fitted onto a rotor of the progressive cavity pump, and at least two retaining fins extending outwards from the sleeve,

[0014] - a housing comprising at least a first shell and a second shell, the first shell and the second shell each comprising a body in the shape of a portion of a cylinder and at least two longitudinal rims, extending outwards from the body, each fixing fin of the stator sleeving being interposed and fixed by compression between a rim of the first shell and a rim of the second shell, the first shell being assembled and fixed to the second shell.

[0015] Advantageously, the stator jacket is made from a single piece. The jacket offers greater sealing because it does not consist of two pieces assembled along a sealing surface.

[0016] Advantageously, unlike an injected and bonded stator, the stator liner can be easily removed from the housings when worn, without tools, and without scraping the inner surface of a one-piece housing. It is not necessary to replace the entire stator assembly, including the housings and liner.

[0017] Advantageously, the mounting fins allow the stator liner to be attached to the housings. The features described in the following paragraphs can optionally be implemented. They can be implemented independently or in combination:

[0018] - The stator jacket is detachable from said at least a first shell and a second shell by disassembly of said at least first shell and second shell, detachable from the rotor only by displacement of the stator jacket in a direction extending along the longitudinal axis;

[0019] - The sleeve has a longitudinal axis, and said at least two fixing fins are contained in the same radial plane, said at least two fixing fins being aligned along a straight line parallel to the longitudinal axis, with an empty space interposed between said two fixing fins.

[0020] Advantageously, the presence of an empty space between the fixing fins allows the local expansion of the elastomer sleeve in its thickness to be regulated in the event of thermal expansion or in the event of greater crushing of the fixing fins.

[0021] The sleeve has an outer surface of helical shape, each helix having a pitch; and in which each fixing fin is located contiguous to a concave area of ​​the outer surface of the sleeve.

[0022] - Each fixing fin has a length along the longitudinal axis direction of between 20 and 80% of the helicoid pitch dimension.

[0023] - The stator jacket is molded from a material among an elastomer material, a composite material, a silicone, a polyurethane, a polyetheretherketone, a polyphenylene sulfide, a polytetrafluoroethylene.

[0024] - The stator includes at least one pair of first removable shims having a rectangular parallelepiped shape, each first shim being mounted between an edge of the first shell and an edge of the second shell, said first shims having a first thickness.

[0025] Advantageously, the shims can be removed when the pumped fluid has a lower temperature or when the stator is worn. Advantageously, the shims prevent the need to replace the rotor when the temperature of the pumped fluid changes significantly, such as by 50°C. Advantageously, when the stator wears and its elastic material is consumed, removing the shims allows the mounting fins to be compressed more significantly, so that the elastic material of the mounting fins flows into the sleeve to compensate for the loss of elastic material caused by wear. Thus, the rotor clamping force can be maintained despite wear. The pump remains efficient for a longer period.

[0026] - The stator includes at least one pair of removable second shims having a rectangular parallelepiped shape, said second shims being arranged between the edges of the first shell and the first set of shims of the second shell, said second shims.

[0027] Advantageously, using a different number of shims allows for precise control of the compression on the mounting fins and therefore the compression on the rotor. Pumping efficiency is ensured for a longer period.

[0028] The stator includes at least one pair of removable secondary shims in the shape of a rectangular parallelepiped, these secondary shims being arranged between the edges of the first shell and the edges of the second shell, these secondary shims having a different thickness than the first. Advantageously, the use of shims of different thicknesses allows for precise control of the compression on the mounting fins and therefore the compression on the rotor. Pumping efficiency is ensured for a longer period.

[0029] - The first thickness is less than 1 millimeter, and preferably equal to 0.6 millimeter.

[0030] The sleeve has a helical outer surface, and this helical outer surface includes at least one first tab having a substantially helical or circular shape, and wherein at least one first shell and / or a second shell comprise at least one first groove complementary in shape to at least one first tab, the at least one first tab being housed within at least one first groove. Advantageously, the fitting of at least one first tab into at least one first groove increases the stator's anchoring to the inner face of the housing.

[0031] - The outer surface of the sleeve comprises at least one second tab having an orientation substantially parallel to the longitudinal axis, and in which at least one first shell comprises at least one second groove of a shape complementary to at least one second tab, the at least one second tab being housed in at least one second groove. - The first shell has a hole oriented in a radial direction with respect to the longitudinal axis, said hole being machined before mounting the stator in the housing.

[0032] - The first shell and the second shell each comprise at least one axial end provided with an external shoulder, and in which the body presents at least one collar in support against the external shoulder of the first shell and the external shoulder of the second shell.

[0033] Advantageously, the collar is mounted against a pump body or a discharge conduit so that it ensures the sealing of the stator against the pump body and / or the discharge conduit to which it is attached.

[0034] Brief description of the figures

[0035] [Fig. 1] is a perspective view of a stator jacket according to the present invention;

[0036] [Fig. 2] is a perspective view of a progressive cavity pump stator according to the present invention;

[0037] [Fig. 3] is a perspective view of a shell of a progressive cavity pump stator according to the present invention;

[0038] [Fig. 4] is a front view along the XX axis of a progressive cavity pump stator according to the present invention;

[0039] [Fig. 5] is a cross-sectional view of a progressive cavity pump stator illustrated in Figure 4, along a vertical cross-sectional plane illustrated in Figure 4;

[0040] [Fig. 6A] is a perspective view of a progressive cavity pump stator shell, the shell being fitted with three wedges;

[0041] [Fig. 6B] is a perspective view of a progressive cavity pump stator shell, the shell being fitted with two wedges;

[0042] [Fig. 7] is a cross-sectional view of a variant of a stator according to a variant of the invention, along a vertical cutting plane;

[0043] [Fig. 8] is a diagram representing the steps in the manufacturing process of a stator jacket.

[0044] Detailed description of the invention

[0045] The invention relates to a progressive cavity pump comprising a rotor 33 and a stator 4. The rotor 33 has a helical shape. It extends around the longitudinal axis X-X. It is adapted to pivot about the longitudinal axis XX. It is visible in Figure 4. The stator 4 comprises a stator sleeve 2. With reference to Figure 1, the stator sleeve 2 comprises a sleeve 6 and retaining fins 8, 10, 12, 14, 16 projecting outwards from the sleeve 6.

[0046] The sleeve 6 has an internal helical recess 18. The sleeve extends around an axis of revolution, hereinafter referred to as the longitudinal axis X-X. The sleeve 6 has a substantially constant thickness.

[0047] Advantageously, this constant thickness allows the elastomer to expand uniformly towards the center of the stator around its entire circumference, resulting in better controlled hydraulic performance over a wide temperature range. Furthermore, higher pressure passes through the pump cavities. Operating torque is reduced, particularly at high temperatures and during start-up.

[0048] The sleeve 6 has an outer surface 20 of substantially helical shape. This outer surface 20 comprises convex areas 24 and concave areas 22.

[0049] In the embodiment illustrated in Figure 1, the sleeve 6 has a flange 26 at each of its axial ends. The flange 26 is molded as a single unit with the sleeve and the retaining fins. The flanges 26 provide a seal between the stator and the pump body on one side, and between the stator and the discharge pipe to which it is attached on the other.

[0050] Preferably, the outer helical surface 20 of the sleeve includes first tabs 28 intended to be housed in first grooves 30 of a housing 32 of the stator 4. Here, the first tabs have a helical shape and extend around the longitudinal axis XX.

[0051] Preferably, some first tabs 28 are arranged along the concave areas 22. Other first tabs 28 are arranged along the convex areas 24 of the outer surface of the sleeve.

[0052] Advantageously, the outer surface 20 of the sleeve 6 includes one or more second tabs 34 having an orientation substantially parallel to the longitudinal axis XX. The second tab(s) 34 are intended to be housed in one or more second grooves 36 of complementary shape in the stator housing, as explained below. The interaction of the first tabs 28 with the first grooves 30 strengthens the anchoring of the stator liner 2 to the inner face of the housing and prevents the stator liner from rotating relative to the housing during rotor rotation. The mounting fins 8, 10, 12, 14, and 16 are contained within the same first radial plane P1. In particular, several mounting fins, here three mounting fins, are located on each side of the stator liner.More specifically, several fixing fins are located on each side of a second radial plane P2 perpendicular to the first radial plane P1 and passing through the longitudinal axis XX. The fixing fins located on the same side of the second plane P2 are aligned along a straight line D parallel to the longitudinal axis XX. A gap 38 is interposed between each pair of adjacent fixing fins.

[0053] Advantageously, the presence of a void 38 between two adjacent retaining fins allows for the regulation of local expansion of the elastomer sleeve in its thickness in the event of thermal expansion or greater compression of the retaining fins, particularly when the shims 60A and 60B are removed. The retaining fins 10, 12, which are used for angular immobilization of the sleeve, also represent excess material. Under temperature conditions or in the event of increased compression of the retaining fins, this excess material expands and tends to locally alter the internal dimension of the elastomer sleeve. To avoid this phenomenon, the invention provides the gaps 38, which are voids in material and which will "compensate" for the expansion of the retaining fins under temperature conditions or during increased compression of the retaining fins, and will thus help to preserve the hydraulic performance of the pump.

[0054] Preferably, each mounting fin 8, 10, 12, 14, 16 of the stator jacket 2 is located adjacent to a concave area of ​​the outer surface of the sleeve. Each mounting fin 8, 10, 12, 14, 16 has a length L along the direction of the longitudinal axis XX. The length L is between 20% and 80% of the pitch dimension P of the stator helix measured on the inner surface of the sleeve. Half a pitch P is shown in Figure 5.

[0055] The stator cladding 2 is molded in one piece from an elastic material. In this patent application, a material is said to be "elastic" when its modulus of elasticity is between 1 megapascal and 90 gigpascals.

[0056] Preferably, the stator jacket is molded from an elastomeric material. Alternatively, the stator jacket 2 is molded from a composite material, such as silicone, polyurethane, polyetheretherketone (PEEK), polyphenylene sulfide (PPS), or polytetrafluoroethylene (PTFE).

[0057] The stator sleeving 2, made in one piece, is fitted onto the rotor. Then, the stator sleeving is inserted into the housing and detached from the housing without tools.

[0058] Advantageously, unlike an injected and bonded stator liner, the stator liner according to this invention can be removed from the housing and replaced when worn. It is not necessary to replace the entire housing and stator liner assembly. This results in considerable environmental and economic savings.

[0059] Advantageously, the stator jacket is not glued into the housing, which helps to limit possible defects and bonding failures, especially when the glue is applied in contact with difficult-to-bond elastomers such as fluorinated elastomers (for example, fluorinated rubber or fluorocarbon rubber, generally designated by the acronym "FKM", and perfluorinated rubber, generally designated by the acronym "FFKM") or difficult-to-bond plastic materials (for example, polytetrafluoroethylene, generally designated by the acronym "PTFE").

[0060] Advantageously, the absence of gluing avoids quality problems related to chemical incompatibilities between the glue and the pumped fluid, which can generate bonding defects at the ends of the stator jacket in particular.

[0061] Furthermore, and advantageously, this stator jacket is leak-proof. This stator jacket remains leak-proof along the entire longitudinal axis XX, even when worn. There is no fluid leakage along the seam between the two stator jacket sections.

[0062] With reference to figure 2, the stator 4 according to the invention comprises the stator jacket 2 described above and illustrated in figure 1 and a housing 32.

[0063] The casing 32 comprises a first shell 40 and a second shell 42 fixed to each other.

[0064] With reference to Figure 3, the first shell 40 comprises a body 44 and two longitudinal rims 46, 48 extending outwards from the body. The body 44 has the shape of a portion of a cylinder.

[0065] In particular, in the embodiment shown, the body 44 has the shape of a half-shell. In other words, the body 44 has the general shape of a cylinder divided along a plane passing through the longitudinal axis XX and perpendicular to a radial plane.

[0066] The longitudinal flanges 46, 48 extend along the longitudinal edges of the body 44. The longitudinal flanges include holes 50 for receiving bolts 51. The second shell 42 is similar to the first shell 40. It will not be described in detail. The first shell 40 is attached to the second shell 42 by screws 51 passing through the holes 50 and nuts. The stator jacket mounting fins 8, 10, 12, arranged on one side of the second radial plane P2, are positioned and secured by compression between the flange 46 of the first shell and the flange 46 of the second shell. The fixing fins 14, 16 arranged on the other side of the second median plane P2 are arranged and fixed by compression between the other rim 48 of the first shell and the other rim 48 of the second shell.

[0067] Preferably, at least two fixing fins aligned along a straight line D parallel to the longitudinal axis XX are arranged and fixed by compression between a rim 46 of the first shell and a rim 46 of the second shell.

[0068] Advantageously, the stator liner's mounting fins 8, 10, 12, 14, and 16 allow the stator liner to be attached to a housing formed of several interlocking shells. These mounting fins secure the stator liner to the housing and prevent it from rotating within the housing during rotor rotation.

[0069] The first shell 40 and the second shell 42 have an internal cavity 52. ​​When the first shell 40 is fixed to the second shell 42, the internal cavities 52 of each shell together form a helical shape.

[0070] The first shell 40 comprises a first axial end 54 intended to be fixed to a pump body and a second axial end 56 opposite the first axial end and intended to be fixed to a discharge conduit. The first axial end 54 and the second axial end 56 of the first shell 40 are provided with an external shoulder 58 formed in one piece with the sleeve 6.

[0071] The second hull 42 is identical to the first hull 40.

[0072] The collar 26 of the stator jacket is mounted to rest on one side against the external shoulder 58 of the first shell and the second shell, on the other side directly against a pump body or a discharge conduit so that the collar ensures the sealing of the stator with respect to the pump body and / or the discharge conduit to which it is attached.

[0073] With reference to Figures 6A and 6B, the stator 4 may include a pair of removable shims 60A, 60B arranged between the edges 46, 48 of the first shell and the tabs 8, 10, 12, 14, 16. The shims 60A, 60B of each pair have the same thickness. One shim from each pair is positioned on each side of the second radial plane P2.

[0074] These shims 60A and 60B have a rectangular parallelepiped shape. They are flat. They comprise a first longitudinal edge with notches 62, and a second longitudinal edge opposite the first. The notches are arranged around the holes 50. The second longitudinal edge has a thickness identification system 64 indicating the shim's thickness. This identification system is, for example, a tab of a specific color or another distinctive mark such as a notch. Shims 60A and 60B, for example, have a thickness of less than 1 millimeter. Preferably, shims 60A and 60B have a thickness of 0.6 millimeters.

[0075] Preferably, the stator 4 can include several pairs of shims stacked one on top of the other. Shims 60A, 60B are then referred to as the "first shims 60A, 60B". The first shims have a thickness E1 and can, for example, be removed from between the two shells when the stator jacket shows between 0 and 33% wear, thus ensuring increased crushing force on the sleeve 6 on the rotor, preferably in the plane P2.

[0076] Preferably, the stator 4 also includes a pair of removable second shims 66A, 66B. The second shims 66A, 66B are identical to the first shims 60A, 60B except that they have a second thickness E2 that differs from the first thickness E1.

[0077] The second shims 66A and 66B have a thickness E2. These shims can, for example, be removed from between the two shells when the stator liner is between 33% and 66% worn, ensuring that sleeve 6 is tightened according to the same principle as described above. The stator 4 can also include a pair of third shims with a third thickness E3 that differs from the second thickness E2 and the first thickness E1. These third shims can, for example, be removed from between the two shells when the stator liner is between 66% and 100% worn. Alternatively, the first shims 60A and 60B and the second shims 66A and 66B have identical thicknesses. In this case, adding or removing a pair of shims allows adjustment of the rotor tightening.

[0078] Alternatively, the third shims have the same thickness as the first and second shims.

[0079] Advantageously, using shims of varying thicknesses allows for precise control of the compression on the mounting fins and therefore the compression of sleeve 6 on the rotor. The stator's pumping efficiency is maintained for a longer period thanks to the wear compensation provided by the successive removal of the shim sets.

[0080] The number of shims and the thickness of the shims mounted on the stator allows the clamping force on the elastomer to be adjusted.

[0081] During pump operation, the stator lining wears down. It loses material. After removing the shims, the mounting fins 8, 10, 12, 14, 16 are more compressed.

[0082] Thus, when the stator liner wears and its elastic material is consumed, removing the shims further compresses the retaining fins, causing the elastic material of the retaining fins to flow into the sleeve 6 to compensate for the loss of elastic material caused by wear. This allows the rotor clamping force to be maintained despite wear. The pump remains efficient for a longer period. The hydraulic efficiency of the progressive cavity pump is preserved over a longer time.

[0083] Furthermore, the number and thickness of the shims mounted on the stator allow for adjusting the rotor clamping force according to the temperature of the pumped fluid. Currently, whenever a customer wants to use their pump successively with fluids at very different temperatures, for example, a fluid at 20°C and a fluid at 50°C, rotors of different diameters are mounted in the stator casing. Changing the rotor requires disassembling the entire pump. It is easier to simply remove or add one or more shims, as this can be done simply by unscrewing bolts 51 and lifting the second casing.

[0084] Advantageously, the shims can be removed when the pumped fluid has a higher temperature or when the stator lining is worn. Advantageously, the shims also prevent the need to replace the rotor when the temperature of the pumped fluid changes significantly, such as by 50°C.

[0085] With reference to figure 7, the second shell 42 has a hole 68 oriented in a radial direction with respect to the longitudinal axis XX. This hole is intended to receive a sensor (for example, temperature or pressure) 70.

[0086] Advantageously, hole 68 is machined before the stator sleeve is mounted in the housing. When the stator sleeve is bonded and injection-molded against the inner surface of the housing, the hole for the temperature sensor can only be made after the stator sleeve has been fixed. This operation is lengthy, tedious, and risky because it is intrusive to the elastomer bonded inside the frame. Advantageously, when the stator sleeve is molded in one piece in the shape of a sleeve not fixed to the housing, as in the present invention, it is possible to make hole 68 before mounting the stator sleeve in the two shells 40 and 42.

[0087] Alternatively, the housing comprises more than two shells, for example four shells, each having the shape of a portion of a cylinder. The shells fixed to one another form a closed housing having the general shape of a cylinder.

[0088] Alternatively, the stator jacket has only two fixing fins on each side of the second radial plane P2.

[0089] Alternatively, the outer surface of the body 44 has only one first tab 38.

[0090] Advantageously, the stator 2 liner is not glued to the housing.

[0091] The invention also relates to a progressive cavity pump comprising a rotor 33 and a stator 4 shaped according to the characteristics mentioned above. Figure 8 illustrates a method for manufacturing the stator liner 2 described above. This method includes a step 72 of molding the stator liner 2 in one piece.

[0092] In step 76, the rotor 33 is fitted into the stator sleeve. Then, the stator sleeve 2 and the rotor 33 are placed in the first shell 40. This operation is carried out without glue.

[0093] In step 78, the second shell 42 is assembled and fixed to the first shell 40 using bolts. In step 80, the stator 4 is put into operation by rotating the rotor 33.

[0094] In step 82, the stator liner 2 is changed without any special tools. The stator liner 2 is detached from the first shell 40 and the second shell 42 by disassembling the first and second shells. For this purpose, the nuts screwed onto the screws 51 are unscrewed. The second shell 42 is separated from the first shell 40. Then, the stator liner 2 is detached from the rotor 33 solely by moving the stator liner 2 in a direction extending along the longitudinal axis XX. No other operation is necessary. In particular, it is not necessary to scrape off a liner that is stuck to the inner wall of the shells. The stator liner 2 cannot be detached from the rotor as a single unit in any other way.

Claims

DEMANDS 1. Stator (4) of a progressive cavity pump, the stator comprising: - a stator liner (2) molded in one piece, the stator liner comprising a sleeve (6) having a longitudinal axis (XX), an internal helical recess (18) intended to be fitted onto a rotor of the progressive cavity pump, and at least two fixing fins (8,10,12,14,16) extending outwards from the sleeve, - a housing (32) comprising at least a first shell (40) and a second shell (42), the first shell and the second shell each comprising a body (44) in the shape of a portion of a cylinder and at least two longitudinal flanges (46, 48) projecting outwards from the body, each fixing fin (8,10,12,14,16) of the stator jacket being intercalated and fixed by compression between an edge (46, 48) of the first shell and an edge (46, 48) of the second shell, the first shell (40) being assembled and fixed to the second shell (42).

2. Stator (4) according to claim 1, wherein the stator jacket (2) is detachable from said at least a first shell and a second shell by disassembly of said at least first shell and second shell, detachable from the rotor only by displacement of the stator jacket in a direction extending along the longitudinal axis (XX).

3. Stator (4) according to any one of claims 1 and 2, wherein the sleeve (6) has a longitudinal axis (XX), and wherein said at least two fixing fins (8,10,12,14,16) are contained in the same radial plane (P1), said at least two fixing fins (8,10,12,14,16) being aligned along a straight line (D) parallel to the longitudinal axis (XX), a gap (38) being interposed between said two fixing fins.

4. Stator (4) according to any one of claims 1 to 3, wherein the sleeve (6) has an outer surface (20) of helical shape, each helicoid having a pitch (P); and wherein each fixing fin (8,10,12,14,16) is located contiguous to a concave area (24) of the outer surface of the sleeve.

5. Stator (4) according to claim 4, wherein each fixing fin (8,10,12,14,16) has a length along the direction of the longitudinal axis between 20 and 80% of the pitch dimension (P) of the helicoid.

6. Stator (4) according to any one of claims 1 to 5, wherein the stator jacket (2) is molded in a material among an elastomeric material, a composite material, a silicone, a polyurethane, a polyetheretherketone, a polyphenylene sulfide, a polytetrafluoroethylene.

7. Stator (4) according to any one of claims 1 to 6, comprising at least one pair of removable first shims (60A, 60B) having a rectangular parallelepiped shape, each first shim (60A, 60B) being mounted between a rim (46, 48) of the first shell and a rim (46, 48) of the second shell, said first shims having a first thickness (E1).

8. Stator (4) according to claim 7, comprising at least one pair of removable second shims (66A, 66B) having a rectangular parallelepiped shape, said second shims (66A, 66B) being arranged between the edges (46, 48) of the first shell and the first set of shims (60A, 60B) of the second shell.

9. Stator (4) according to claim 7, comprising at least one pair of removable second shims (66A, 66B) having a rectangular parallelepiped shape, said second shims (66A, 66B) being arranged between the edges (46, 48) of the first shell and the edges (46,48) of the second shell, said second shims (66A, 66B) having a thickness (E2) different from the first thickness (E1).

10. Stator (4) according to claim 7, wherein the first thickness (E1) is less than 1 millimeter, and preferably equal to 0.6 millimeter.

11. Stator (4) according to any one of claims 4 to 10, wherein the sleeve (6) has an outer surface (20) of helical shape, and wherein the outer helical surface (20) of the sleeve comprises at least one first tab (28) having a substantially helical or circular shape, and wherein the at least one first shell (40) and / or a second shell (42) comprise at least one first groove (30) of a shape complementary to the at least one first tab (28), the at least one first tab (28) being housed in the at least one first groove (30).

12. Stator (4) according to any one of claims 4 to 11, wherein the outer surface (20) of the sleeve comprises at least a second tab (34) having an orientation substantially parallel to the longitudinal axis (XX), and wherein the at least one first shell (40) comprises at least a second groove (36) of complementary shape to the at least a second tongue (34), the at least a second tongue being housed in the at least a second groove.

13. Stator (4) according to any one of claims 1 to 12, wherein the first shell (40) has a hole (68) oriented in a radial direction with respect to the longitudinal axis (XX), said hole (68) being machined before mounting the stator in the housing.

14. Stator (4) according to any one of claims 1 to 13, wherein the first shell (40) and the second shell (42) each comprise at least one axial end (54, 56) provided with an external shoulder (58), and wherein the body (44) has at least one collar (26) bearing against the external shoulder (58) of the first shell (40) and the external shoulder (58) of the second shell (42).

15. Progressive cavity pump comprising a rotor (33) and a stator (4) shaped according to any one of claims 1 to 14.

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