Screw pump and components thereof

Abstract

The present disclosure relates to a screw pump (2) comprising: a housing (3) having an inlet (30), an outlet (31) and a flow chamber (32) between the inlet and the outlet; and at least two screws (4, 5, 6) housed in the flow cavity to force fluid to flow from the inlet through the flow cavity to the outlet, where each screw (4, 5, 6) comprises a release coupling structure (45, 52, 62) to limit rotation of the screw when the screw is removed from the molding tool.

Description

Technical Field

[0001] The present disclosure relates to the field of progressive cavity pumps and components thereof. More particularly, but not exclusively, the present disclosure also relates to a cooling circuit, for example for a vehicle, comprising a progressive cavity pump. Background Art

[0002] Known screw pumps include a housing and two, three or more screws housed in the housing, which are driven by a motor to force a fluid to flow through the pump. Summary of the invention

[0003] The present disclosure is directed to improving the known designs of progressive cavity pumps and their performance.

[0004] The present disclosure relates to a screw pump, which includes: a housing having an inlet, an outlet and a flow chamber between the inlet and the outlet; and at least two screws accommodated in the flow chamber to force a fluid to flow from the inlet through the flow chamber to the outlet, wherein at least one of the screws includes a central shaft made of a first material, and the screw is molded on the central shaft by a second material.

[0005] For clarity, the first material and the second material may be different materials or similar materials to each other.

[0006] The first material and the second material may be different. Advantageously, the first material is harder than the second material, for example, so that at least one screw strength is increased. The first material may include a metal (e.g., steel, such as stainless steel), or a hard polymer. The second material may include a polymer, wherein the first material may include a polymer that is harder than the polymer of the second material. Therefore, according to one aspect, the hardness of the second material may be less than the first material.

[0007] According to one aspect of the present disclosure, at least one of the screws includes a central shaft made of a first material, and the screw is molded on the central shaft from a second material having a lower hardness than the first material.

[0008] As a variant, the first material and the second material may be identical or similar.The first material and the second material may each comprise a polymer, for example a similar polymer.

[0009] The first material and the second material may include one or more polymers. At least one polymer may include polyphenylene sulfide (PPS). The polymer (e.g., PPS) may be filled with, for example, fibers (such as glass fibers). The polymer (e.g., PPS) may be lubricated. The first material and the second material may include the same polymer, such as PPS, which may be filled or added, or different for each of the first material and the second material.

[0010] The central shaft may include one or more anchoring features or elements or members.The one or more anchoring features may be embedded in the second material, for example to anchor the central shaft in the second material.

[0011] The or each anchoring feature may comprise a rib or spline, for example an axial rib or spline.The or each anchoring feature may extend along at least a portion of the central axis.

[0012] The one or more anchoring features may include at least two anchoring features or at least two groups of anchoring features that may be spaced apart along the length of the central axis.

[0013] The at least one increased strength screw may include a drive screw, and a central shaft of the drive screw may include a motor coupling structure, such as for receiving torque from a drive motor.

[0014] The housing may include an outer shell within which an insert defining the flow chamber is received.

[0015] The present disclosure also relates to a method of manufacturing a screw for a screw pump, the method comprising providing a central shaft made of a first material, and molding the screw on the central shaft using a second material.

[0016] For clarity, the first material and the second material may be different materials or similar materials to each other.

[0017] The first material and the second material may be different. The method may include inserting the central shaft into a mold and then molding the screw on the central shaft. Advantageously, the first material is harder than the second material, for example so that at least one screw has increased strength. The first material may include a metal or a hard polymer.

[0018] Thus, according to one aspect, the second material may have a lower hardness than the first material.

[0019] As a variation, the first material and the second material may be similar. The first material and the second material may include polymers. The method may include, for example, molding a central shaft using the first material and then molding the screw on the central shaft using the second material. The method may include a two-step molding process.

[0020] The present disclosure also relates to a screw pump, which includes: a housing having an inlet, an outlet and a flow chamber between the inlet and the outlet; and at least two screws accommodated in the flow chamber to force the fluid to flow from the inlet through the flow chamber to the outlet, wherein the housing includes an outer shell, and an insert defining the flow chamber is accommodated in the outer shell.

[0021] The flow chamber can be defined by a tubular wall of the insert. The tubular wall can present or can have a substantially constant wall thickness. The tubular wall can have a plurality of cylindrical lobes, which can be shaped to approximate the outer profile of the meshing screw. The cylindrical lobes can include a central lobes, for example, the shape of which approximates the outer surface of the central drive screw. The cylindrical lobes can include outer lobes on each side of the central lobes, for example, the shape of which approximates the outer surface of the corresponding driven screw. The flow chamber can provide a minimum space between the screws while allowing them to rotate freely.

[0022] The housing may include a space between the outer shell and the insert. The interface between the outer shell and the insert may be designed to allow part of the circulating fluid to enter the space when in use. The space may be separate from the flow chamber and / or not be part of the flow chamber.

[0023] The insert may include one or more anti-rotation protrusions that may engage with the housing to inhibit relative rotation therebetween. The or each anti-rotation protrusion may extend axially from the insert. The or each anti-rotation protrusion may include an anti-rotation tab. The insert may include one or more anti-rotation protrusions extending from one or each end thereof. The insert may include a flange or clamp at one end, such as a circular flange or clamp. The flange or clamp may have a periphery shaped close to the inner surface of the shell, for example to position the insert within the housing.

[0024] The pump may include a flexible coupling structure. The flexible coupling structure may be connected to one of the screws to couple the screw to the drive motor. The flexible coupling structure may be connected to the motor coupling structure of the central shaft of the drive screw.

[0025] The present disclosure also relates to a screw pump, which includes: a housing having an inlet, an outlet and a flow chamber between the inlet and the outlet; at least two screws accommodated in the flow chamber to force the fluid to flow from the inlet through the flow chamber to the outlet; and a flexible coupling structure connected to one of the screws to couple the screw to a drive motor.

[0026] The flexible coupling structure may include a first side or first end, for example, having a first coupling feature to engage the shaft of the drive motor. The flexible coupling structure may include a second side or second end, for example, having a second coupling feature, which engages a mating feature of the screw to which it is connected.

[0027] The first coupling feature may be a groove, which may be diametric and / or may be designed to accommodate a protrusion on the drive motor or the shaft of the drive motor. The second coupling feature may be a protrusion, for example to engage in a mating feature of the drive screw. The protrusion may be rectangular. The second coupling feature may be rotationally offset, for example 90 degrees, relative to the first coupling feature.

[0028] The flexible coupling structure may comprise a polymer material which may be lubricated, for example in its bulk and / or by grease.

[0029] At least one screw may be non-self-locking. At least one screw may include one or more threads, each having a pitch and / or diameter and / or configuration that enables the screw to be ejected from the mold by applying an axial force to the screw, e.g. without applying a rotational force to the screw. At least one screw may include one or more threads, each having a helix angle that enables the screw to be ejected from the mold by applying an axial force to the screw, e.g. without applying a rotational force to the screw.

[0030] The helix angle may be at least 60°, for example at least 70°. At least one screw may be made of a polymer, for example polyphenylene sulfide (PPS). The polymer (for example PPS) may be filled with, for example, fibers (such as glass fibers). The polymer (for example PPS) may be lubricated.

[0031] The present disclosure also relates to a method of manufacturing a screw for a screw pump.

[0032] The present disclosure also relates to a method for manufacturing a screw for a screw pump, the method comprising molding the screw in a molding tool using a polymer material, and ejecting the screw from the mold by applying an axial force to the screw, wherein the material and thread of the screw are configured to allow the screw to rotate freely in the mold by the axial force.

[0033] Self-locking of the screw can be prevented by its construction, in particular the helix angle of the thread or each thread and / or the coefficient of friction between the thread or threads and the die surface.

[0034] The present disclosure also relates to a screw pump, which includes: a housing having an inlet, an outlet and a flow chamber between the inlet and the outlet; and at least two screws accommodated in the flow chamber to force the fluid to flow from the inlet through the flow chamber to the outlet, wherein at least one of the screws can be obtained by the above method.

[0035] As a variant, at least one screw may be self-locking. At least one screw may include one or more threads, each having a pitch and / or diameter and / or configuration that prevents the screw from being ejected from the mold by applying an axial force to the screw, for example without applying a rotational force to the screw. At least one screw may include one or more threads, each having a helix angle that prevents the screw from being ejected from the mold by applying an axial force to the screw, for example without applying a rotational force to the screw.

[0036] The helix angle may be less than 60°. At least one screw may be made of a polymer, for example polyphenylene sulfide (PPS). The polymer (for example PPS) may be filled with, for example, fibers (such as glass fibers). The polymer (for example PPS) may be lubricated.

[0037] According to one aspect of the present disclosure, at least one screw includes a release coupling structure to limit rotation of the screw when the screw is removed from the molding tool.

[0038] According to one aspect of the present disclosure, each screw includes a release coupling structure to limit rotation of the screw when the screw is removed from the molding tool.

[0039] Of course, according to different variations of the present disclosure, at least one or each screw (such as the self-locking screw or each self-locking screw) may include a release coupling structure. When the screw is removed from the molding tool, the release coupling structure may be used to limit the rotation of the screw.

[0040] The present disclosure also relates to a screw pump, which includes: a housing having an inlet, an outlet and a flow chamber between the inlet and the outlet; and at least two screws accommodated in the flow chamber to force the fluid to flow from the inlet through the flow chamber to the outlet, wherein each screw includes a release coupling structure to limit the rotation of the screw when the screw is removed from the molding tool.

[0041] The insert may comprise at least one recess. The or each recess may be designed, for example, to accommodate one of the release coupling structures when the screw is accommodated in the flow chamber. One of the release coupling structures may be accommodated in the recess.

[0042] In each of the above aspects of the present disclosure, the screw may include three or more screws, or four or more screws. The screw may include at least one driving screw and at least one driven screw, such as at least two driven screws. Advantageously, the screw may include at least three driven screws, which may be distributed around the driving screw, such as evenly distributed.

[0043] The present disclosure also relates to a method of manufacturing a screw for a screw pump, the method comprising molding the screw in a molding tool using a polymer material, and ejecting the screw from the mold by applying torque to a screw release coupling structure while unscrewing the screw from the mold.

[0044] The release coupling structure of at least one of these screws may include at least one radial shoulder. The release coupling structure of at least one of these screws may include a circular or non-circular structure. The release coupling structure of at least one of these screws may include an annular or partially annular structure.

[0045] The present disclosure also relates to a cooling circuit for a vehicle, the cooling circuit comprising a progressive cavity pump as described above.

[0046] For the avoidance of doubt, all features described herein are also applicable to any aspect of the present disclosure.

[0047] As part of this application, it is expressly provided that the various aspects, aspects, examples and alternatives disclosed in the preceding paragraphs and / or in the following description and drawings (particularly their independent features) can be adopted individually or in any combination. In other words, all aspects and / or features of any aspect can be combined in any way unless these features are incompatible.

[0048] For the avoidance of doubt, the terms "may", "and / or", "for example" and any other similar terms used herein must be interpreted as not being limiting such that any feature described herein need not necessarily be present. Indeed, any combination of optional features is expressly contemplated without departing from the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Other features and advantages of the present disclosure will become apparent from the following detailed description which will be understood with reference to the accompanying drawings, in which:

[0050] Figure 1 A pump assembly according to one aspect of the present disclosure is shown;

[0051] Figure 2 yes Figure 1 An exploded view of the pump assembly in FIG.

[0052] Figure 3 Shown Figure 1 and Figure 2 a first side of a flow chamber insert of a pump assembly;

[0053] Figure 4 Shown Figure 3 a second side of the flow chamber insert;

[0054] Figure 5 Shown Figure 3 and Figure 4 an insert in which the insert is received in a shell of the housing, and the screw is received in the insert;

[0055] Figure 6 Shown Figure 1 and Figure 2 A flexible coupling structure of the assembly in the embodiment of the present invention, wherein the flexible coupling structure couples the drive screw to the drive motor;

[0056] Figure 7 Shown Figure 1 and Figure 2 a drive screw of a pump assembly in;

[0057] Figure 8 Shown Figure 7 The central axis of the drive screw;

[0058] Fig. 9 Shown Figure 1 and Figure 2 a first side of two driven screws of a pump assembly;

[0059] Fig.10 Shown Fig. 9 a second side of the driven screw in;

[0060] Fig.11 A pump assembly according to another aspect of the present disclosure is shown;

[0061] Fig.12 Shown Fig.11 a first side of a flow chamber insert of a pump assembly;

[0062] Fig.13 Shown Fig.12 a second side of the flow chamber insert;

[0063] Fig.14 Shown Fig.12 and Fig.13 an insert in which the insert is received in the housing of the casing and the screw is received in the insert;

[0064] Fig.15 Shown Fig.11 The screw assembly of the pump assembly shown in ; and

[0065] Fig.16 Shows a replacement Fig.15 The screw assembly can be used for Fig.11 Another screw assembly in the pump assembly. DETAILED DESCRIPTION

[0066] Refer to the attached Figures 1 to 16Different aspects of the disclosure are described in more detail.

[0067] Reference now Figure 1 and Figure 2 , shows a screw pump assembly 1, which includes a motor 10 coupled to a screw pump 2 through a flexible coupling structure 11. The screw pump 2 includes a housing 3, which has an inlet pipe 30, an outlet pipe 31 and a flow chamber 32 between the inlet 30 and the outlet 31. Three screws 4, 5, 6 are accommodated in the flow chamber 32 to force the fluid to flow from the inlet 30 through the flow chamber 32 to the outlet 31.

[0068] The housing 3 comprises a shell 33 in which an insert 34 defining a flow chamber 32 is accommodated. The shell 33 is in the shape of a hollow cylinder having a closed end 33a from which the inlet pipe 30 protrudes. The outlet pipe 31 protrudes radially from the shell 33 at a position close to the open end 33b. The screw pump 2 is reversible, and therefore, the inlet pipe 30 and the outlet pipe 31 can be reversed by rotating the screw pump 2 in the opposite direction. However, for simplicity, the axial pipe 30 protruding from the closed end 33a will be referred to as the inlet pipe 30 hereinafter, and the radial pipe 30 protruding from the open end 33b will be referred to as the outlet pipe 31 hereinafter.

[0069] like Figure 3 and Figure 4 As shown in FIG. 1 , the flow chamber 32 is defined by a tubular wall 35 of an insert 34 having a substantially constant wall thickness. The tubular wall 35 has three cylindrical lobes 35a, 35b, 35c that are shaped close to the outer contours of the three meshing screws 4, 5, 6. More specifically, the central lobe 35a is shaped close to the outer surface of the central drive screw 4, wherein the outer lobes 35b, 35c on each side of the central lobe 35a are each shaped close to the outer surface of the corresponding driven screw 5, 6. The flow chamber 32 provides a minimum space between the screws 4, 5, 6 while allowing these screws to rotate freely.

[0070] The insert 34 also includes a pair of anti-rotation tabs 36, 37 that protrude axially from each of its ends. The first pair of anti-rotation tabs 36 protrude from the upper and lower portions of the central lobe portion 35a at the first end of the insert 34. The second pair of anti-rotation tabs 37 protrude from the circular flange 38 at the second end of the insert 34, above and below the central lobe portion 35a. The circular flange 38 has a peripheral edge that is shaped close to the inner surface of the outer shell 33, which makes it possible to position the insert 34 within the shell 33 and form a space E therebetween, as shown in FIG. Figure 5 More clearly shown in .

[0071] The housing 3 also includes a pair of mounting discs 39a, 39b and a spacer interface 39c. The mounting discs 39a, 39b engage the anti-rotation tabs 36, 37 of the insert 34 and are attached within the housing 33 to capture the screws 4, 5, 6 and the insert 34 therebetween. The spacer interface 39c seals the screw pump 2 and isolates the flow chamber 32 from the motor 10, but the interface between the housing 33 and the insert 34 is designed to allow a portion of the circulating fluid to enter the space E when in use.

[0072] In some examples, the first mounting disk 39a can be part of or integrated with the spacer interface 39c. In some examples, the second mounting disk 39b can be part of or integrated with the insert 34. When the second mounting disk 39b is part of the insert 34, the anti-rotation tab 37 protruding from the circular flange 38 can be omitted.

[0073] Between the shell 33 and the insert 34 there is a space E filled with a circulating fluid which provides a damping effect resulting from the interaction between the screws 4, 5, 6. Furthermore, the skilled person will appreciate that the use of a separate insert 34 enables the flow chamber 32 to be manufactured with high precision. This also makes it easier to manufacture the insert 34 by injection molding, as it can be designed with a substantially constant wall thickness to optimize cycle time and part quality.

[0074] exist Figure 6 The flexible coupling structure 11 , shown more clearly in , is generally cylindrical and has a first coupling feature 12 at a first axial end thereof and a second coupling feature 13 at a second axial end thereof.

[0075] The first coupling feature 12 is a diametrical groove designed to receive a rectangular protrusion on the shaft of the drive motor 10. The second coupling feature 13 is a rectangular protrusion that is rotationally offset 90 degrees from the first coupling feature 12 to engage a mating feature of the drive screw 4.

[0076] In this example, the flexible coupling structure 11 is made of a lubricating polymer. The use of a flexible coupling structure between the drive motor 10 and the screw pump 2 enables small angular and axial misalignments to be accommodated while minimizing vibrations. Those skilled in the art will appreciate that this feature works together with the vibration damping effect of the space E between the housing 33 and the insert 34.

[0077] Drive screw 4 Figure 7 4 and comprises a central shaft 40 and a body 41 moulded onto the central shaft 40. In this example, the body 41 comprises two diametrically opposed threads 42 along its length.

[0078] The central shaft 40 includes an anchoring feature 43 built into the body 41 to anchor the central shaft 40 to the body 41. In this example, the anchoring feature 43 includes two sets of axial splines 44 extending along a portion of the central shaft 40. The two sets of axial splines 44 are spaced apart from each other along the length of the central shaft 40.

[0079] The central shaft 40 also includes a motor coupling structure 45 in the form of a diametric groove designed to receive the rectangular protrusion 13 of the flexible coupling structure 11, although it can directly receive the rectangular protrusion of the shaft of the drive motor 10. In this example, the central shaft 40 is made of stainless steel and the body 41 is made of a polymer material.

[0080] There are several advantages to using a polymer screw body 41 molded onto a stainless steel central shaft 40. The presence of the central shaft 40 reduces the thickness of the material required to form the body 41. Those skilled in the art will appreciate that this significantly reduces cycle time and reduces the likelihood of deformation of the molded body 41 as the material solidifies. In addition, the rigidity of the central shaft 40 also prevents the screw 4 from bending or deforming under load when the drive motor 10 applies torque to it.

[0081] Those skilled in the art will also appreciate that this feature works together with the vibration dampening effect of the flexible coupling structure 11 and the space E between the housing 33 and the insert 34 .

[0082] Fig. 9 and Fig.10 Driven screws 5 and 6 are shown. Each driven screw 5, 6 comprises a respective body 50, 60 having a pair of diametrically opposed threads 51, 61 along its length. Each driven screw 5, 6 also comprises a release coupling structure 52, 62 at one of its ends. Each release coupling structure 52, 62 is in the shape of a ring 53, 63 having a pair of notches 54, 64 aligned with adjacent ends of the threads 51, 61. The notches 54, 64 form radial shoulders 54a, 64a to which torque can be applied.

[0083] The diameter of the ring 53, 63 of each driven screw 5, 6 is greater than the diameter of the threads 51, 61, and a hole 55, 65 is defined between the ring 53, 63 and the base of the threads 51, 61. Therefore, a fluid passage is defined between the threads 51, 61 and through the release coupling structure 52, 62 along the entire length of each driven screw 5, 6. Each driven screw 5, 6 also includes an axial protrusion 56, 66 at the center of each end thereof.

[0084] In this example, the threads 51, 61 of the driven screws 5, 6 are self-locking, because if only an axial force is applied to the driven screws 5, 6 at the end of the molding cycle, their rotation is prevented while they are still in the mold cavity (not shown). Therefore, a torque must be applied to the driven screws 5, 6 to remove them from the mold. The release coupling structure 52, 62 allows this torque to be applied to the driven screws 5, 6.

[0085] In this example, the insert 34 includes annular steps 32a, 32b surrounding a portion of the flow chamber 32 defined by each outer lobe 35b, 35c. When the screw 4, 5, 6 is received in the flow chamber 32, these annular steps 32a, 32b serve as recesses for receiving the rings 53, 63.

[0086] It will also be understood that the screw threads 51, 61 may alternatively be designed to be non-self-locking. In this case, the release coupling structure 52, 62 may be omitted and the driven screws 5, 6 may be driven out at the end of the molding process by simply applying an axial force to the driven screws 5, 6.

[0087] For example, the threads may each have a pitch and / or diameter and / or configuration that enables the screw to be ejected from the die by applying an axial force to the screw without applying a rotational force to the screw. More specifically, the threads may each have a helix angle that enables the screw to be ejected from the die by applying an axial force to the screw without applying a rotational force to the screw.

[0088] By way of example only, when the threads are made of a polymer, such as glass-filled polyphenylene sulfide (PPS), the helix angle may be at least 60°, such as at least 70°.

[0089] Reference now Figures 11 to 15 , shows a screw pump assembly 101 according to a second example, which is similar to the first example, wherein similar features are marked with the same numerals increased by 100. The screw pump assembly 1 in this example differs from the screw pump assembly of the first example in that it includes three driven screws 105, 106, 107, and the driving screw has three threads 142, which is Fig.15 More clearly shown in.

[0090] Therefore, the tubular wall 135 has four cylindrical lobes 135a, 135b, 135c, 135d, and the shapes of these cylindrical lobes are close to the outer contours of the four meshing screws 104, 105, 106, 107. More specifically, the shape of the central lobes 135a is close to the outer surface of the central driving screw 104, wherein three outer lobes 135b, 135c, 135d are evenly distributed around the periphery of the central lobes 135a, and each outer lobes is close to the outer surface of the corresponding driven screw 105, 106, 107.

[0091] Fig.16 Shows that it can replace Fig.15 The screw assembly is used for Fig.11 Another screw assembly 205, 206, 207 in the pump assembly in FIG. The screws 205, 206, 207 are similar to the screws in the previous examples, wherein similar features are labeled by the same numerals increased by 100. The screw assemblies 205, 206, 207 in this example differ from the screw assemblies in the previous examples in that the helix angle is larger.

[0092] A person skilled in the art will appreciate that several variations of the above-described aspects may be envisaged without departing from the scope of the present disclosure.

[0093] Throughout the description part and claims of this specification, the words “comprise” and “comprising” and variations thereof mean “including but not limited to”, and are not intended to (and do not) exclude other parts, additives, components, integers or steps.

[0094] Any feature, whole, characteristic, compound, or group described in conjunction with a particular aspect, embodiment, or example of the present disclosure should be understood to be applicable to any other aspect, embodiment, or example described herein, unless inconsistent therewith. All features disclosed in this specification (including abstract and accompanying drawings) and / or all method steps or processes disclosed in this manner can be combined in any combination (except where at least some of such features and / or steps and / or steps are mutually exclusive combinations). The present disclosure is not limited to the details of all the aforementioned aspects. The present disclosure extends to any new features or any new combination of these features disclosed in this specification (including abstract and accompanying drawings), or to any new features or any new combination of these steps of any method or process disclosed in this manner.

[0095] List of Reference Numerals

[0096] 1 Screw pump assembly

[0097] 10 Motor

[0098] 11 Flexible coupling structure

[0099] 12 First coupling feature

[0100] 13 Second coupling feature

[0101] 2 Progressing Cavity Pumps

[0102] 3 Housing

[0103] 30 Inlet pipe

[0104] 31 outlet pipe

[0105] 32 Flow chamber

[0106] 32a Circular Stairs

[0107] 32b Circular Stairs

[0108] 33 Shell

[0109] 33a Closed end of housing

[0110] 33b Open end of housing

[0111] 34 Inserts

[0112] 35 Tubular insert wall

[0113] 35a Cylindrical central lobed portion of tubular wall

[0114] 35b Cylindrical outer convex petal portion of tubular wall

[0115] 35c Cylindrical outer convex petal portion of tubular wall

[0116] 36 Anti-rotation tab

[0117] 37 Anti-rotation tab

[0118] 38 Round flange

[0119] 39a Installation disk

[0120] 39b Installation disk

[0121] 39c Spacer connector

[0122] 4 Drive screw

[0123] 40 Drive screw center shaft

[0124] 41 Drive screw body

[0125] 43 Anchorage Features

[0126] 44 Axial spline

[0127] 45 Motor coupling structure

[0128] 5 Driven screw

[0129] 50 Driven screw body

[0130] 51 driven screw thread

[0131] 52 Release coupling structure

[0132] 53 Release coupling ring

[0133] 54 Release coupling notch

[0134] 54a Radial shoulder

[0135] 55 holes

[0136] 56 Axial protrusion

[0137] 6 Driven screw

[0138] 60 Driven screw body

[0139] 61 driven screw thread

[0140] 62 Release coupling structure

[0141] 63 Release coupling ring

[0142] 64 Release coupling notch

[0143] 64a Radial shoulder

[0144] 65 holes

[0145] 66 Axial protrusion

[0146] E Space between insert and housing

[0147] 101 Screw Pump Assembly

[0148] 110 Motor

[0149] 102 Screw Pump

[0150] 103 Housing

[0151] 130 Inlet pipe

[0152] 131 outlet pipe

[0153] 132 Flow chamber

[0154] 133 Shell

[0155] 133a Closed end of housing

[0156] 133b Open end of housing

[0157] 134 Inserts

[0158] 135 Tubular insert wall

[0159] 135a Cylindrical central lobed portion of tubular wall

[0160] 135b Cylindrical outer convex petal portion of tubular wall

[0161] 135c Cylindrical outer convex petal portion of tubular wall

[0162] 135d Cylindrical outer convex petal portion of tubular wall

[0163] 136 Anti-rotation tab

[0164] 137 Anti-rotation tab

[0165] 138 Round flange

[0166] 104 Drive screw

[0167] 140 Drive screw center shaft

[0168] 141 Drive screw body

[0169] 145 Motor coupling structure

[0170] 105 driven screw

[0171] 150 Driven screw body

[0172] 151 driven screw thread

[0173] 156 Axial protrusion

[0174] 106 Driven screw

[0175] 160 Driven screw body

[0176] 161 driven screw thread

[0177] 166 Axial protrusion

[0178] 107 Driven screw

[0179] 176 Axial protrusion

[0180] 204 Drive screw

[0181] 240 Drive screw center shaft

[0182] 241 Drive screw body

[0183] 245 Motor coupling structure

[0184] 205 driven screw

[0185] 250 Driven screw body

[0186] 251 driven screw thread

[0187] 256 Axial protrusion

[0188] 206 driven screw

[0189] 260 Driven screw body

[0190] 261 driven screw thread

[0191] 266 Axial protrusion

[0192] 207 Driven screw

[0193] 276 Axial protrusion

Claims

1. A screw pump (2), comprising: A housing (3) having an inlet (30), an outlet (31) and a flow chamber (32) between the inlet and the outlet; as well as at least two screws (4, 5, 6) received in the flow chamber to force a fluid to flow from the inlet through the flow chamber to the outlet; Each screw (4, 5, 6) includes a release coupling structure (45, 52, 62) to limit the rotation of the screw when the screw is removed from the molding tool.

2. The screw pump according to claim 1, wherein: The release coupling structure (52, 62) of at least one of the screws (5, 6) comprises at least one radial shoulder (54a, 64a).

3. The screw pump according to claim 1 or claim 2, wherein: The release coupling structure (52, 62) of at least one of the screws (5, 6) comprises a non-circular structure.

4. A screw pump according to any one of the preceding claims, wherein: The release coupling structure (52, 62) of at least one of the screws comprises an annular or partly annular structure (53, 63).

5. A screw pump according to any one of the preceding claims, wherein: At least one of the screws (4) comprises a central shaft (40) made of a first material, and the screw is molded on the central shaft from a second material having a lower hardness than the first material.

6. A screw pump according to any one of the preceding claims, wherein: The housing comprises an outer shell (33) in which an insert (34) defining the flow chamber is accommodated.

7. The screw pump according to claim 6, wherein: The insert (34) includes at least one recess (32a, 32b) in which one of the release coupling structures (45, 52, 62) is received.

8. The screw pump according to claim 6 or claim 7, wherein: The flow chamber is defined by a tubular wall (35) of the insert, the tubular wall having a substantially constant wall thickness.

9. The screw pump according to any one of claims 6 to 8, wherein: The housing comprises a space (E) between the outer shell and the insert.

10. The screw pump according to any one of claims 6 to 9, wherein: The space is separate from the flow chamber and is not a part of the flow chamber.

11. The screw pump according to any one of claims 6 to 10, wherein: The interface structure between the housing and the insert is designed to allow a portion of the circulating fluid to enter the space when in use.

12. The screw pump according to any one of claims 6 to 11, wherein: The insert includes one or more anti-rotation projections (36, 37) that engage the housing to inhibit relative rotation therebetween.

13. A screw pump according to any one of the preceding claims, comprising a flexible coupling structure (11) connected to one of the screws (4) for coupling the screw to a drive motor.

14. A pump assembly (1), comprising a pump according to claim 13 and a drive motor (10), the drive motor being coupled to the flexible coupling structure to drive the screw to force the fluid to flow from the inlet through the flow chamber to the outlet.

Images