Progressive cavity pump

Abstract

The cam is secured to the upper and lower ends of the shaft via a latching mechanism, wherein the latching mechanism comprises a first latch, wherein the first latching mechanism comprises a first latch, and a second latch is secured to the lower end of the shaft via a latching mechanism.

Description

Technical Field

[0001] The invention relates to a screw pump comprising a spindle housing in which a driving spindle and at least one driven spindle meshing with the driving spindle are accommodated in a spindle bore. Background Art

[0002] Progressive cavity pumps are used to transport fluids, such as fuel, supply fluid, or cooling fluid. This is accomplished via at least two intermeshing spindles housed in a spindle housing (i.e., a drive spindle coupled to a drive motor and a driven spindle). To this end, the spindle housing has intersecting spindle bores corresponding to the number of spindles. The spindle housing is typically housed in a pump housing or outer casing, through which the fluid to be transported is supplied and discharged.

[0003] The operating principle is based on the meshing of a drive spindle and an output spindle, and the axial displacement of the delivery volume due to spindle rotation. To this end, the drive spindle has a cylindrical spindle core and typically has two spindle profiles surrounding the spindle core. These spindle profiles form two circumferential profile recesses, into which the corresponding spindle profiles of the output spindle engage. In addition to this dual-spindle design, a screw with three spindles can also be designed. In this case, two output spindles are provided, which are arranged 180° apart from the central drive spindle and mesh with it.

[0004] As previously mentioned, the drive spindle must be coupled to the drive motor because it actively rotates, while the one or two driven spindles are merely driven along. To couple the drive spindle to the drive motor or its drive shaft, a coupling element is arranged on the end face of the drive spindle. This coupling element is rotationally fixedly connected to the drive spindle using a corresponding positive-locking geometry. This positive-locking connection provides a rotationally fixed connection in at least one direction of rotation. Depending on the design, a rotationally fixed connection can also be established in other directions of rotation, thus enabling a change in the drive direction and, therefore, the spindle's rotational direction.

[0005] For example, DE 43 08 755 A1 discloses such a screw pump. It describes a claw coupling for coupling the motor drive shaft to the drive spindle. Two intersecting grooves are milled into one axial end of the drive spindle, forming two opposing claws with a triangular cross-section. A disc-shaped coupling element has a circular cross-section and is equipped with two similarly triangular grooves, into which the triangular claws of the drive spindle engage. A slot is provided in the center of the coupling element for the end of the motor-side drive shaft to engage.

[0006] DE 10 2015 101 443 A1 discloses a screw pump in which the end of the main shaft, where the coupling element is to be arranged, has a planar surface. The main shaft outer profile also ends at this end face. Viewed radially, abutment surfaces at right angles to each other are formed by material removal at two opposing positions. The coupling element has a corresponding three-dimensional accommodation and a snap-in geometry, which is designed to provide axial snap-in portions that engage to a certain extent in two connected outer profile recesses and abut against the abutment surfaces formed in their area, so that, viewed in the circumferential direction, the coupling element abuts flatly on the drive main shaft, forming a rotationally fixed connection, while at the same time the coupling element rests axially on the planar end face.

[0007] Although this coupling, often also referred to as a claw coupling, has generally proven to be advantageous, there is still a need for a progressive cavity pump with an improved coupling. Summary of the Invention

[0008] In view of this, the subject matter of the present invention is to provide a screw pump having an improved coupling device.

[0009] In order to solve this problem, a screw pump is provided according to the present invention, comprising a spindle housing, a driving spindle and at least one driven spindle meshing with the driving spindle being accommodated in a spindle hole in the spindle housing, wherein the driving spindle has a cylindrical spindle core and at least two spindle outer profiles surrounding the spindle core, a disc-shaped coupling element is arranged in a recess axially defined by a flat bottom surface on the end side of the driving spindle, two outer profile recesses between the two spindle outer profiles are connected to the recess at an offset of 180°, the coupling element has a socket for the driving shaft of the driving motor, and In at least one rotational direction of the drive spindle, the drive spindle is rotationally fixedly coupled to the drive spindle by engaging with the shape of an axially protruding protrusion, the protrusion laterally limiting the recess and engaging with the lateral accommodation portion of the coupling element, wherein the bottom surface is limited by the spindle core in the outlet area of the two outer contour recesses, and the coupling element is rounded in the element area adjacent to the outlet area, corresponding to the shape of the spindle core, wherein the diameter of the coupling element in the area of the rounded element part is at most equivalent to the diameter of the spindle core, or is smaller than the diameter of the spindle core.

[0010] The screw pump according to the invention has a flow-optimized coupling or connection between the drive spindle and the coupling element. In particular, the geometry of the coupling element is selected so that it only slightly reduces, if at all, the delivery cross section at the outlet of the corresponding outer profile recessed on the end face of the spindle. The free delivery cross section is hardly affected by the coupling element, so that, viewed in the axial direction, the flow is hardly significantly affected, which improves the delivery performance.

[0011] To achieve this, a special coupling element is provided. It is disc-shaped and has two laterally open receptacles, each of which has an axially protruding projection on the end face of the drive spindle that snaps into the receptacle. This form-fitting engagement creates a rotationally fixed connection in one direction of rotation, and preferably in both directions. These axially protruding projections define a recess on the end face of the spindle, which has a flat bottom, into which the coupling element fits. The bottom of the recess is primarily formed by the spindle core of the drive spindle, since, as previously mentioned, two outer recesses are connected on this end face. Therefore, the rounded boundaries formed by the spindle core are arranged opposite each other. The coupling element is designed so that the element region adjacent to the outlet of the outer recess is also rounded, that is, it corresponds to the shape of the spindle core. The diameter of the coupling element in the region of these similarly oppositely arranged, rounded element portions is at most equal to or smaller than the diameter of the spindle core. In other words, due to the design of the coupling element's diameter relative to the spindle core diameter, the coupling element in the region of these element sections does not protrude into the free flow cross-section of the connected outer profile recesses, thereby necessarily reducing the free flow cross-section and thus obstructing the flow. Unlike screw pumps known in the prior art, whose coupling elements, due to their size or geometry, significantly protrude radially into the free flow cross-section, thereby significantly reducing the free flow cross-section, the coupling element of the screw pump of the present invention no longer forms a significant flow obstruction. As a result, the conveyed fluid flows axially past the coupling element with virtually no obstruction, which greatly facilitates pump operation.

[0012] In a refinement of the present invention, the coupling element has a cylindrical base portion from which four element projections project laterally, with two adjacent element projections delimiting a lateral receptacle. These element projections serve only to define or delimit the form-fitting geometry, i.e., the receptacles into which the axial projections on the spindle engage. Therefore, these element projections have only a transmission function, since they form a rotationally fixed coupling in the circumferential direction. Consequently, these element projections can also be designed to be narrow in a flow-optimized manner, without significantly reducing the flow cross section. The end face of the drive spindle can be machined using two cross-cuts, so that the defined engagement geometry is correspondingly arranged in the identically shaped receptacles of the protruding projections. As previously described, these projections laterally delimit the recesses and axially extend the outer contours of the two spindles. As a result, the flat bottom surface of the recess is slightly enlarged laterally, in addition to the surface portion formed by the spindle core. In this region, the element projections cover this enlarged area, viewed axially.

[0013] Advantageously, the receptacle of the coupling element extends into the base portion. The base portion is provided with a socket for the motor-side drive spindle, which may be implemented, for example, as a rectangular socket with an elongated cross-section. Since the ultimate purpose of the coupling element is to achieve a rotationally fixed connection between the motor-side drive shaft and the drive shaft by snapping it into the socket, and to achieve a rotationally fixed connection between the coupling element and the drive spindle, each receptacle can extend significantly into the cylindrical base portion. This, in turn, allows the protrusion of transmission components, such as those protruding from the base portion, to be correspondingly shortened.

[0014] The element projection itself is advantageously triangular in shape and tapers towards its free end, ie is very narrow and relatively short overall.

[0015] The thickness of each element projection decreases towards its free end, thereby minimizing the material of the coupling element.

[0016] The socket itself is preferably quadrilateral. It can have a rectangular, or generally elongated, shape, with its longer axis extending between two rounded element parts and its shorter axis between two receptacles. This technical solution enables a very compact, low-profile design of the coupling element. This orientation of the rectangular socket allows the two approximately V-shaped receptacles of the coupling element to be drawn relatively far into the cylindrical base. These receptacles terminate just before the socket, which, as previously mentioned, ultimately allows for a shorter element projection on the coupling element side.

[0017] The coupling element itself can be made of plastic, ie can be a plastic part produced in an injection molding process, which has the desired mechanical and physical properties, for example in terms of hardness, heat resistance, etc. Alternatively, the coupling element can also be made of metal, for example aluminum or steel.

[0018] As previously mentioned, a screw pump typically also includes a drive motor or has such a drive motor attached to it. This drive motor is axially mounted on the housing, and its drive shaft must be axially aligned with the longitudinal axis of the drive spindle. This is because, as previously mentioned, the drive shaft engages a socket in a coupling element, which is centrally located on the longitudinal axis of the drive spindle. The operating principle of a screw pump is based on axial fluid transport, meaning that the fluid axially leaves the spindle assembly and flows through the coupling element. As previously mentioned, due to the geometry of this coupling element according to the present invention, this does not reduce the flow cross section or reduces it only to a negligible extent. The motor-side drive shaft typically also has a cylindrical cross-section, with the shaft end being provided with a corresponding plug-in geometry, i.e., a similarly square or rectangular latch pin. Since the transported fluid axially leaves the spindle assembly and, as previously mentioned, flows through the coupling element, it must then also flow through the drive shaft, at least in the region of coupling with the coupling element. To ensure that there are no flow obstructions in the transition region between the coupling element and the drive shaft, an advantageous refinement of the present invention provides a drive motor whose cylindrical drive shaft has a diameter that corresponds at most to the diameter of the cylindrical spindle core. This means that the diameter is also adjusted here to ensure that, viewed radially, the drive shaft cross section does not interfere with the flow cross section of the drive shaft and that the flow cross section is then somewhat reduced at the spindle-side outlet. This means that even in the transition region between the coupling element and the drive shaft, no step or flow obstruction relative to the spindle core diameter is formed, resulting in a virtually unimpeded axial outflow. This axial outflow occurs regardless of whether the screw pump is a dry or wet pump. In dry screw pumps, the volume delivered by the spindle assembly flows essentially directly to the pump outlet after exiting the spindle assembly, without having to circulate through the drive motor for cooling. In wet screw pumps, a portion of the delivered fluid enters the motor housing to cool components there and is then recirculated back to the pump housing or outer casing. The diameter of the drive shaft can also be smaller than the diameter of the spindle core of the drive spindle, and the diameter of the drive shaft can also correspond to the diameter of the cylindrical base part of the coupling element.

[0019] As previously mentioned, the screw pump can be a 2-spindle pump, having a single drive spindle and only one driven spindle positioned to the side of the drive spindle. Alternatively, the screw pump can be a 3-spindle pump, having a central drive spindle and two driven spindles positioned to the left and right of the drive spindle and meshing with the drive spindle.

[0020] In addition to the screw pump itself, the present invention also relates to its use for conveying a working fluid in a vehicle. The working fluid can be a fuel or other fluid, such as a cooling fluid, for example, for cooling a traction battery or a power battery, or other working fluids, such as windshield cleaning fluid. The screw pump can also be used in other land vehicles or aircraft, such as airplanes or drones, but the range of possible applications is not limited to this.

[0021] However, the screw pump is used in particular as a coolant pump, in particular for conveying a coolant for cooling the energy accumulator. The coolant can be any coolant. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] For more advantages and details of the present invention, please refer to the embodiments described below and the accompanying drawings.

[0023] Figure 1 A schematic cross-sectional view of a screw pump according to the invention having a driving spindle and two driven spindles is shown.

[0024] Figure 2 Exploded view of the drive spindle and the coupling element not inserted into the recess.

[0025] Figure 3 for Figure 2 The arrangement shown shows the relative diameters on the spindle core and base,

[0026] Figure 4 A top view of the end face of the drive spindle is shown, looking towards the recess accommodating the coupling element.

[0027] Figure 5 Show Figure 4 The arrangement shown is a top view with the coupling element inserted,

[0028] Figure 6 Show Figure 5 A perspective view of the arrangement shown,

[0029] Figure 7 An exploded view of a portion of a screw pump and a schematic diagram of the drive shaft of the drive motor, and

[0030] Figure 8 The cross-section view after installation Figure 7 Arrangement shown. DETAILED DESCRIPTION

[0031] Figure 1The screw pump 1 according to the invention is shown, comprising a housing 2 with an axially arranged inlet connection 3 and a radially arranged outlet connection 4. A spindle housing 5 is arranged in the housing 2 (also referred to as the pump housing). In the illustrated embodiment, three spindles are accommodated in the spindle housing: a central drive spindle 6 and two driven spindles 7 arranged on either side of the drive spindle 6, in corresponding intersecting spindle bores. The spindles 6, 7 each have a spindle profile that snaps into place (i.e., meshes with one another).

[0032] Furthermore, only a simplified diagram of the drive motor 8 is shown here, wherein the drive motor can be a dry-running or wet-running drive motor. The drive motor has a drive shaft 9, which is shown here only in a non-realistic manner, and is connected to the drive spindle 6 in a rotationally fixed manner via a coupling element 10. In other words, the drive spindle 6 is actively driven by the drive motor 8. Due to the engagement of the spindle outer profiles, the rotation of the drive spindle 6 also necessarily causes the two driven spindles 7 to rotate. The corresponding delivery volume is moved or displaced axially by the mutually meshing spindle outer profiles and the spindle rotation, thereby implementing fluid delivery in a known manner. The fluid is drawn in axially via the inlet connection 3, conveyed along the spindle assembly, and discharged at the motor-side end of the spindle assembly, from where it flows to the outlet connection 4 via the corresponding flow geometry.

[0033] Figure 2 An enlarged perspective view of the drive spindle 6 and the coupling element 10 is shown in exploded view. The drive spindle 6, made of metal or plastic, has a spindle core 11 with a cylindrical cross section, around which two spindle profiles 12 extend, forming corresponding profile recesses 13. At one axial end, the drive spindle 6 has a recess 14, which is axially delimited by a planar bottom surface 15 and laterally delimited by two projections 16, wherein the two projections 16 are formed approximately in the extension of the spindle profile 12 extending into the bottom surface 15. The projections 16 are machined by material removal and will be described below in conjunction with the Figure 4 This is explained in detail, so that the bottom surface 15 is formed as a whole, which is formed in sections by the spindle core 11 on the one hand, and is formed by the bottom parts connecting the protrusions 16 based on the machining of the protrusions on the other hand, which will be explained in detail below.

[0034] Coupling element 10, likewise made of metal or plastic, is disk-shaped, i.e., has a defined maximum thickness. It comprises a cylindrical base part 17 with two opposite, rounded element regions 18. Furthermore, in the illustrated example, base part 17 is provided with four laterally projecting element projections 19, which each define a V-shaped receiving portion 20 between them. In the assembled position when coupling element 10 is inserted into recess 14, projections 16 engage the V-shaped receiving portion.

[0035] like Figure 2 as well as Figure 3 As shown, the bottom surface 15 is formed and delimited at least in sections by the cylindrical spindle core 11. This rounded boundary resulting from the cylindrical shape of the spindle core 11 is formed at the outlet of the corresponding outer contour recess 13, since the outer contour recess is defined by the spindle core 11. The spindle core 11 has a core diameter D K ,exist Figure 3 Shown in.

[0036] As mentioned above, the coupling element 10 also has a disc-shaped cylindrical base portion 17 with a base portion diameter D B , also in Figure 3 Now the size or geometry of the coupling element 10 is designed so that the diameter of the base portion 17 is less than or equal to the diameter of the spindle core, so that D B ≤D K That is, in the assembled position, the base portion has a diameter D B The rounded element region 18 does not necessarily extend into the flow cross section or outlet cross section of the corresponding outer contour recess 13. Therefore, the coupling element 10 does not form a flow obstacle at least in the region of the rounded element portion 18.

[0037] Figure 4 The end face of the drive spindle 6 is shown in a top view looking towards the recess 14 . The figure shows two outer contour recesses 13 communicating therewith and the spindle core which defines the rounded boundaries of the bottom face 15 in opposite edge sections 21 .

[0038] The end faces are machined by corresponding cross-grinding, which, on the one hand, results in an enlargement of the base surface 15 on the spindle core surface. On the other hand, this results in a specific form-fitting or snap-fitting geometry of the projections 16, which have two V-shaped abutment surfaces 22, with which they abut flatly against corresponding abutment surfaces of the coupling element 10 or are arranged closely spaced therefrom with a narrow gap. The coupling element 10 is shown in dashed lines.

[0039] The four lateral enlarged portions of the bottom surface 15 are formed by cross grinding to form a substantially X-shape, such as Figure 4 Clearly shown.

[0040] Now insert the coupling element 10 into this recess 14. Figure 5 and Figure 6 The corresponding top view ( Figure 5 ) and perspective drawing ( Figure 6 ). Diameter of base part D B Maximum equivalent core diameter D K , therefore, from Figure 5 and Figure 6 It can be clearly seen that the rounded portion 18 of the coupling element 10 does not extend into the flow cross section defined by the spindle core 11. The element projections 19 each define two V-shaped receptacles 20 open at the sides, which are delimited by two abutment surfaces 23. The receptacles 20 extend into the base part 17 and end just before reaching a socket 24, which has a quadrilateral or rectangular cross section and is intended to receive a correspondingly shaped latching pin of the drive shaft 9. Figure 5 and Figure 6 In the assembly position shown, the receiving portion 20 receives the two protrusions 16 in a substantially form-fitting or form-matching manner. Due to the abutment of the surfaces 22, 23 and the corresponding V-shaped engagement, a rotationally fixed connection is formed in both clockwise and counterclockwise rotation.

[0041] As already mentioned, the element projection 19 extends from the base part 17 and thus also forms an approximately X-shape here, corresponding to the X-like shape of the recess or bottom surface 15. Likewise, the element projection 19 ultimately does not extend into the outlet cross section of the corresponding outer contour recess 13 at the end face, so that the coupling element 10 does not or hardly forms a flow obstacle to the fluid flow. Figure 5 The projections 19 of the elements shown at the top right and bottom left extend slightly into the flow cross section, but their hindering effect is negligible.

[0042] like Figure 5 and Figure 6 As shown, the element projection 19 tapers towards its free end and its thickness also decreases towards the free end. Corresponding inclined surfaces or chamfers are formed, in particular on both sides, so that reverse assembly is also possible without any problems.

[0043] like Figure 5 As shown, the coupling element 10 lies almost completely flat on the bottom surface 15 when viewed in the axial direction, or covers the bottom surface 15 in the axial direction. Figure 5 The upper right component protrusion 19 and Figure 5 The element projection 19 shown at the bottom left slightly protrudes radially beyond the bottom surface 15 and into the flow cross section. However, this intrusion or cross-sectional coverage is so small that the flow-impeding effect is almost negligible.

[0044] Figure 7 The exploded view of the inner housing 5 shows that, in contrast to the three-spindle embodiment shown in the previous figures, the screw pump has only two spindles, namely a driving spindle 6 and only one driven spindle 7. This means that the coupling according to the invention can be used both for three-spindle screw pumps 1 and for two-spindle screw pumps 1.

[0045] exist Figure 7In the exploded view shown, a recess 14 of the same design as described above is formed at the axial end of the drive spindle 6, into which the same coupling element 10 is inserted. In addition, a schematic diagram of the drive shaft 9 of the drive motor is shown with an end-side pin 25, which engages in the socket 24 with a positive fit. Figure 8 In the illustrated assembly position, latch 25 engages receptacle 24, while coupling element 10 is simultaneously positioned in recess 14. Consequently, rotation of drive shaft 9, coupled by coupling element 10, necessarily rotates drive spindle 6 and, consequently, driven spindle 7, enabling the pump to deliver fluid. Due to the geometry of projection 16 and receptacle 20, and the corresponding V-shaped configuration formed by the corresponding abutment surfaces, drive shaft 9, and therefore drive spindle 6, can rotate both clockwise, i.e., in the delivery direction, and, if desired, counterclockwise, since a rotationally fixed coupling is provided in both directions of rotation.

[0046] In addition, if Figure 8 As shown, Figure 8 D A The diameter of the drive shaft 9 is smaller than the core diameter D of the main shaft core 11. K . Diameter D A corresponds approximately to the diameter D of the base portion of the coupling element 10 B . Figure 8 This is clearly shown. Thus, in the transition region between the coupling element 10 and the drive shaft 9, no additional diameter D A Larger than the base diameter D B That is, apart from the two short element protrusions 19 that only slightly extend into the flow cross section as described above, the axial discharge of the fluid from the main shaft assembly ultimately presents almost no flow obstacles. In addition, unlike the previously known coupling devices described at the beginning of this article, the fluid can flow completely freely.

[0047] This screw pump 1, whether a two-spindle or three-spindle pump, can be used to transport a variety of fluids. Preferably, it is used in the automotive sector as a fuel pump or as a supply pump for other working fluids, particularly as a supply pump for coolant used to cool the vehicle's energy accumulator. The energy accumulator is typically a large-capacity traction accumulator in an electric vehicle. Therefore, it is a coolant pump. Of course, other applications are also contemplated, such as a supply pump for washer fluid used in vehicle wipers and the like.

Claims

1. A screw pump, comprising a spindle housing (5), a driving spindle (6) and at least one driven spindle (7) meshing with the driving spindle, which are accommodated in a spindle hole in the spindle housing, wherein the driving spindle (6) has a cylindrical spindle core (11) and at least two spindle outer profiles (12) surrounding the spindle core (11), a disc-shaped coupling element (10) is arranged in a recess (14) axially defined by a flat bottom surface (15) on the end side of the driving spindle (6), two outer profile recesses (13) between the two spindle outer profiles (12) are connected to the recess at an offset of 180 degrees, and the coupling element has a drive for driving a motor (8). The coupling element (10) is provided with a socket (24) for a driving shaft (9), and is rotationally fixedly coupled to the driving spindle (6) in at least one rotational direction of the driving spindle (6) by engaging with a shape-matched axially protruding protrusion (16), the protrusion laterally defining the recess (14) and engaging with a lateral receiving portion (20) of the coupling element (10), the bottom surface (15) being defined by the spindle core (11) in the outlet region of the two outer contour recesses (13), and the coupling element (10) being rounded in an element region (18) adjacent to the outlet region, corresponding to the shape of the spindle core (11), wherein the diameter (D B ) in the area of the rounded element area (18) corresponds at most to the diameter (D K ), or smaller than the diameter (D K ).

2. The screw pump according to claim 1, characterized in that The coupling element (10) has a cylindrical base portion (17) from which four element projections (19) project, wherein two adjacent element projections (19) define a lateral receptacle (20).

3. The screw pump according to claim 2, characterized in that The receiving portion (20) extends into the base portion (17).

4. The screw pump according to claim 2 or 3, characterized in that The element protrusion (19) is triangular in shape and tapers toward its free end.

5. The screw pump according to claim 2, characterized in that The thickness of each element projection (19) decreases towards its free end.

6. The screw pump according to claim 2, characterized in that The socket (24) has a quadrilateral shape.

7. The screw pump according to claim 6, characterized in that The socket (24) has a rectangular shape, wherein the socket extends with its longer axis between two rounded element regions (18) and with its shorter axis between two receptacles (20).

8. The screw pump according to claim 1 or 2, characterized in that The coupling element (10) is made of plastic or metal.

9. The screw pump according to claim 1 or 2, characterized in that The drive motor (8), wherein the diameter (D A ) is equal to the maximum diameter of the cylindrical spindle core (11) (D K ).

10. The screw pump according to claim 1 or 2, characterized in that A central driving spindle (6) and two driven spindles (7) are arranged on both sides of the driving spindle.

11. Use of a screw pump (1) according to any one of the preceding claims for pumping a working fluid in a motor vehicle.

12. The use according to claim 11, characterized in that The screw pump (1) serves as a coolant pump.

13. The use according to claim 12, characterized in that The screw pump (1) is used to transport a coolant for cooling the energy accumulator.

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