A centrifugal pump and a pump housing

Abstract

A centrifugal pump for delivering fluid is proposed, the pump comprises a pump housing (2) provided with a rotor (3) for delivering fluid, and a stator (4), the stator, together with the rotor (3), forms an electromagnetic rotational drive for rotating the rotor (3) about an axial direction (A), the stator (4) is designed as a bearing and drive stator, the rotor (3) can be magnetically driven without contact with the stator and can also be magnetically levitated without contact with the stator (4), the rotor (3) is passively magnetically levitated in the axial direction (A) and also actively magnetically levitated in a radial plane perpendicular to the axial direction (A), the pump housing (2) comprises a bottom (27) and a cover (25), the rotor (3) is disposed between the bottom (27) and the cover (25) with respect to the axial direction (A) in the pump housing (2), and at least one indentation (9) is formed in the bottom (27) and / or It is provided in a cover (25), and the indentation (9) is designed to generate local turbulence. Additionally, a pump housing (2) for such a centrifugal pump (1) is proposed by the present invention.

Description

Technology Field

[0001] The present invention relates to a centrifugal pump and a pump housing for delivering fluid, according to the preamble of the independent patent claim of each category. Background Technology

[0002] Centrifugal pumps are known to include electromagnetic rotary drivers, which are designed and operated according to the principles of bearingless motors. In this regard, the term bearingless motor refers to an electromagnetic rotary driver in which the rotor is completely magnetically levitated relative to the stator and no separate magnetic bearings are provided. For this purpose, the stator is designed as a bearing and drive stator, which is both the stator of the electric driver and the stator of magnetic levitation. A rotating magnetic field can be generated by the electric windings of the stator, which on the one hand applies torque to the rotor (which causes the rotor to rotate) and on the other hand applies a shear force (which can be set as desired) to the rotor, so that the radial position of the rotor can be actively controlled or adjusted. Thus, the three degrees of freedom of the rotor—namely, the rotation and radial position (two degrees of freedom) of the rotor—can be actively adjusted. For the three additional degrees of freedom—namely, the axial position and the inclination with respect to the radial plane perpendicular to the desired axis of rotation (two degrees of freedom)—the rotor is passively magnetically levitated or stabilized by reluctance force, that is, it cannot be controlled. The characteristic is that there are no separate magnetic bearings and complete magnetic levitation of the rotor occurs, which is why it is given the name "bearingless motor."

[0003] Bearingless motors are well known to those skilled in the art and are used in many different applications. Some basic descriptions can be found, for example, in EP A 0 860 046 and EP-A-0 819 330.

[0004] Centrifugal pumps designed based on the principle of bearingless motors are used in various applications.

[0005] Because there are no mechanical bearings, centrifugal pumps with bearingless motors are particularly suitable for applications where very sensitive substances are delivered (e.g., blood pumps) or where very high requirements for purity are imposed (e.g., the pharmaceutical or biotechnology industries) or where abrasive or aggressive substances (which would destroy mechanical bearings very quickly) are delivered (e.g., pumps for slurries or acidic fluids used in the semiconductor industry).

[0006] An additional advantage of the bearingless motor principle is derived from the design of the rotor as an integral unit, which serves as both the rotor for electromagnetic actuators and centrifugal pumps. In addition to non-contact magnetic levitation, this offers the advantage of a very compact and space-saving configuration.

[0007] Additionally, the principle of the bearingless motor also enables the design of centrifugal pumps in which the rotor, housed within the pump housing, can be very easily separated from the stator. This is a significant advantage because the pump housing can therefore be designed, for instance, as a disposable component for single use. Today, such disposable applications are frequently replacing processes where all parts in contact with the fluid to be processed previously had to be purified and sterilized in complex ways, such as steam sterilization, due to very high purity requirements. In a disposable design, the part in contact with the fluid to be processed is used exactly once and is then replaced with a new, unused, disposable part for the next application.

[0008] In all applications where bearingless motors are successfully used in centrifugal pumps, it is in principle possible to design the bearingless motor as an internal rotor (i.e., having a rotor positioned inside and a stator positioned around it) or as an external rotor (i.e., having a stator positioned inside and a rotor positioned around it). However, for both designs, it has been shown that for certain applications, the passive magnetic stabilization of the rotor against axial displacement and inclination with respect to the radial plane may reach its limits or may even be no longer sufficient to ensure the safe and trouble-free operation of the centrifugal pump. The problem to be solved

[0009] Therefore, starting from these latest technologies, the object of the present invention is to propose a centrifugal pump having an electromagnetic rotary drive comprising a rotor that can be magnetically driven without contact and also magnetically levitated without contact, and in particular, has improved passive magnetic stabilization of the rotor with respect to axial displacement. Additionally, the object of the present invention is to propose a pump housing for such a centrifugal pump. means of solving the problem

[0010] The subject of the present invention for achieving this objective is characterized by the distinctive features of the independent claims of each category.

[0011] According to the present invention, a centrifugal pump for delivering fluid is proposed, wherein the centrifugal pump comprises a pump housing having a rotor for delivering fluid and a stator, wherein the stator, together with the rotor, forms an electromagnetic rotary drive for rotating the rotor about an axial direction, wherein the stator is designed as a bearing and a drive stator, wherein the rotor can be magnetically driven without contact with the stator and can also be magnetically levitated without contact with the stator, wherein the rotor is passively magnetically levitated in an axial direction and also actively magnetically levitated in a radial plane perpendicular to the axial direction, wherein the pump housing comprises a bottom and a cover, wherein the rotor is disposed between the bottom and the cover with respect to the axial direction in the pump housing, and at least one indentation is provided in the bottom and / or cover, wherein the indentation is designed to generate local turbulence.

[0012] The present invention is based on the discovery that flow conditions within a pump housing can be influenced by at least one indentation in the pump housing, such that the force acting on the rotor, particularly in the axial direction, can be reduced. Due to this reduction, the magnetic axial levitation of the rotor is alleviated, and as a result, the passive magnetic stabilization of the rotor is significantly improved. Furthermore, it has been shown that the passive magnetic stabilization of the rotor against tilting toward the radial plane (perpendicular to the axial direction) can be significantly improved by at least one indentation. By generating local turbulence, the flow behavior around the rotor changes in a desired manner, thereby reducing the force acting on the rotor, and particularly the force acting in the axial direction.

[0013] In principle, the present invention does not require a relief bore extending completely through the rotor in the axial direction for geometric barriers and pressure compensation to reduce or reduce the velocity of backflow from the pressure side to the suction side. Local turbulence and / or flow separation occurs due to at least one indentation, thereby reducing the force of the flow acting on the surface of the rotor surrounded by the flow. For example, the force acting on the rotor is also reduced due to the reduction in dynamic lift caused by flow separation due to the indentation.

[0014] According to a preferred embodiment, the rotor comprises an annular or disc-shaped magnetic effect core and an impeller having a plurality of vanes for delivering fluid. In this regard, the magnetic core interacts with the stator so that the impeller having vanes drives and levitates the rotor without contact while delivering fluid.

[0015] Preferably, the centrifugal pump is designed with a radial flow impeller. An inlet for fluid is provided in the cover of the pump housing, and the inlet is designed to allow fluid to flow into the pump housing in an axial direction. Furthermore, the pump housing includes an outlet for fluid, and this outlet is designed to allow fluid to flow out of the pump housing in a radial direction. This means that the impeller receives axial flow and delivers the fluid in a direction perpendicular to that axial direction. In another embodiment, the impeller may be designed as a semi-axial flow impeller.

[0016] Furthermore, it is desirable for the rotary drive of the centrifugal pump to be designed according to the principle of an internal rotor. For this purpose, the stator has a plurality of stator poles arranged, for example, in an annular shape, and the pump housing, in which the rotor is housed, is designed to be inserted into the stator between the stator poles so that the magnetic effect core of the rotor is surrounded by the stator poles.

[0017] In fact, it was found that it is advantageous for the rotor to have an outer diameter, and for each indentation to have a radial extension that is at least 1 / 50 of the outer diameter of the rotor.

[0018] Furthermore, it was found that the rotor has an outer diameter, and each indentation has a radial extension that is up to half the outer diameter of the rotor.

[0019] According to a more preferred method, the rotor has an outer diameter, and each indentation has a depth in the axial direction that is at least 1 / 150, preferably at least 1 / 100, of the outer diameter of the rotor.

[0020] In addition, the rotor has an outer diameter, and it is preferable that each indentation be at most 1 / 10 of the outer diameter of the rotor.

[0021] The desired reduction of forces and inclination moments acting on the rotor may be influenced by several factors that can be optimized for each application. These factors include, in particular, the number of indentations, their location, and their geometric dimensions, specifically the radial and axial extensions. If multiple indentations are provided on the cover and / or bottom, it is not necessary for all indentations to have the same dimensions. Furthermore, it is possible for the indentations to have different dimensions and / or geometric structures.

[0022] The specific shape of the indentation has a smaller impact. The indentation can be designed, for example, to have a square or rectangular profile. The indentation can be designed with pyramidal, conical, truncated, annular, or even free-form geometric structures. The indentation(s) only need to be designed so that the local surface texture is modified to cause the fluid flow to swirl at this point.

[0023] However, for manufacturing reasons, it is desirable for each indentation to have a circular profile perpendicular to the axial direction. For this purpose, for example, each indentation is designed as a blind hole, the diameter of which determines the radial extension of the indentation, and the length of the blind hole determines the axial depth of the indentation.

[0024] According to a preferred embodiment, at least one indentation is provided in both the cover and the bottom of the pump housing.

[0025] In a more preferable manner, each indentation is positioned in the radially outer edge region of the pump housing. In particular, this means that each indentation in the cover of the pump housing is closer to the radially outer edge of the cover than to the center of the cover, and each indentation in the bottom of the pump housing is closer to the radially outer edge of the bottom than to the center of the bottom.

[0026] Preferably, the pump housing is made of plastic or metal material.

[0027] It is also desirable for the impeller to be made of plastic or metal material.

[0028] In a more advantageous way, the rotor has a jacket that completely surrounds the rotor's magnetic effect core, so that the magnetic effect core does not come into contact with the fluid. The jacket is preferably made of plastic, but it may also be made of metal.

[0029] The pump housing, impeller, and jacket can be made of the same plastic or metal material, or different plastic or metal materials. Of course, a combination of plastic or metal materials is also possible; for example, the rotor jacket can be made of plastic and the pump housing of metal.

[0030] To further reduce the passive magnetic stabilization or levitation of the rotor for the three degrees of freedom (axial displacement and inclination with respect to the radial plane) and thereby further improve the stabilization of the rotor for these three degrees of freedom, additional measures are possible, which are non-exclusively listed as follows:

[0031] The rotor may have a cover plate covering the vanes of the impeller on the side facing the inlet, and an opening positioned at the center is provided in the cover plate, through which fluid can flow to the impeller.

[0032] The magnetic effect core of the rotor may have a central bore that extends axially through the magnetic effect core and an optional jacket completely.

[0033] The rotor may include a balancing hole or a plurality of balancing holes, and each balancing hole extends axially through the rotor's magnetic effect core and optional jacket completely. Each balancing hole is preferably positioned off-center, that is, not at the center of the rotor.

[0034] When multiple balancing holes are provided, the balancing holes are preferably arranged in a circular line around the center bore or around the center of the rotor. Preferably, a maximum of or exactly eight balancing holes are provided, and these holes are preferably arranged at equal intervals around the center bore of the rotor or around the center of the rotor.

[0035] Preferably, each balancing hole has a diameter smaller than the diameter of the center bore.

[0036] Multiple rear vanes may be provided on the axial end face of the rotor facing away from the inlet. In the operating state, these rear vanes are located on the opposite side of the bottom of the pump housing.

[0037] The rear vanes can be realized, for example, by providing a recess in the jacket of the rotor, so that each rear vane is formed between two adjacent recesses.

[0038] In addition, it is also possible to design the rear vane as a raised section. For this purpose, a structure similar to an impeller, for example, can be created and attached to the axial end face of the rotor, so that the rear vane is on the opposite side of the bottom of the pump housing. Of course, the rear vane can also be manufactured individually and attached to the axial end face of the rotor.

[0039] Preferably, each rear vane extends radially. Preferably, each rear vane starts at the radially outer edge of the axial end face of the rotor and extends radially inward from there. Each rear vane may extend to the center or center bore of the axial end face, or each rear vane has a radial length smaller than the radius of the axial end face, for example, half the size.

[0040] Preferably, the outlet is designed as an outlet connection. The outlet connection preferably extends perpendicular to the axial direction. The outlet connection has an inlet surface through which the fluid passes when entering the outlet connection, and an outlet surface through which the fluid passes when leaving the outlet connection. Preferably, the inlet surface is smaller than the outlet surface.

[0041] Preferably, the external shape of the outlet connection is designed to be cylindrical. In the case of a cylindrical design, the outlet connection has a central axis, and it is also preferable that the outlet connection be positioned along the axial direction such that the central axis is closer to the magnetic effect core of the rotor than to the cover of the pump housing.

[0042] Additionally, it is possible to design the inlet of the pump housing as an inlet connection, which preferably extends in the axial direction. The inlet connection preferably has an inlet surface through which fluid passes when entering the inlet connection, and an outlet surface through which fluid passes when leaving the inlet connection and flowing toward the impeller. Preferably, the inlet surface is larger than the outlet surface. Furthermore, it is preferable that the inlet connection has a flow cross-section perpendicular to the axial direction that is smaller than the inlet surface and also has a contracted region that is smaller than the outlet surface.

[0043] As another advantageous alternative, an annular or circular disc-shaped pressure plate is provided on the impeller, which is aligned perpendicular to the axial direction. The pressure plate is positioned axially between the magnetic effect core and the end of the impeller facing the cover of the pump housing, so that the pressure plate extends between the vanes of the impeller. If the rotor has a cover plate, the pressure plate is positioned axially between the magnetic effect core and the cover plate. The pressure plate extends between all the vanes.

[0044] With respect to the radial direction, the pressure plate is positioned centered with respect to the rotor and preferably extends radially at most to the radially outer end of the vane. However, the pressure plate may be designed radially such that the diameter of the pressure plate is significantly smaller than the diameter of the impeller.

[0045] If the rotor has a balancing hole or multiple balancing holes, the pressure plate is radially dimensioned to preferably cover at least all balancing holes.

[0046] For passive magnetic stabilization of the rotor, it is particularly advantageous for the diameter of the rotor's magnetic effect core to be greater than 2.6 times the height of the rotor's magnetic effect core, and the height is an extension in the axial direction. Therefore, when d is the diameter of the rotor's magnetic effect core and HR is the axial height of the magnetic effect core, it is advantageous to satisfy the condition d > 2.6*HR.

[0047] The measures listed above may be provided individually in each case, for example, or various measures may be combined, for example, all measures may be combined.

[0048] Additionally, a pump housing is provided according to the present invention, and a rotor for delivering fluid is provided within the pump housing, and the pump housing is designed for a centrifugal pump according to the present invention.

[0049] The pump housing according to the present invention can be designed as a disposable part, particularly for single use. The stator of the centrifugal pump according to the present invention is preferably designed as a reusable device for multiple uses.

[0050] Further advantageous measures and embodiments of the present invention are known from the dependent claims.

[0051] The present invention will be described in more detail below based on embodiments and with reference to the drawings. Brief explanation of the drawing

[0052] FIG. 1 is a schematic cross-sectional view of an embodiment of a centrifugal pump including an electromagnetic rotary drive, wherein the drive is designed as a bearingless motor. FIG. 2 is a schematic cross-sectional view of a first embodiment of a centrifugal pump according to the present invention. Figure 3 is an enlarged cross-sectional view of the indentation. FIG. 4 is a cross-sectional view of the cover of the embodiment of FIG. 2. Figure 5 is a plan view of the cover of Figure 4 seen from the bottom of the pump housing. FIG. 6 is a cross-sectional view of the housing portion of the first embodiment of FIG. 2. Figure 7 is a plan view of the housing portion of Figure 6 seen from the cover of the pump housing. FIG. 8 is a schematic cross-sectional view of a second embodiment of a centrifugal pump according to the present invention. FIG. 9 is a plan view of a rotor of a second embodiment viewed from the bottom of a pump housing. FIG. 10 is a schematic cross-sectional view of one variant of a rotor. Specific details for implementing the invention

[0053] First, with reference to FIG. 1, an embodiment of a centrifugal pump is described, which includes an electromagnetic rotary drive designed as a bearingless motor. Of course, this embodiment can be designed according to the present invention.

[0054] The centrifugal pump is generally denoted by reference number "1". The centrifugal pump (1) for delivering fluid comprises a pump housing (2) having an inlet (21) and an outlet (22) for the fluid to be delivered. A rotor (3) is disposed inside the pump housing (2), and together with a stator (4) disposed outside the pump housing (2), the rotor forms an electromagnetic rotary drive, and the rotor (3) can be driven to rotate about an axial direction (A) by this rotary drive.

[0055] The electromagnetic rotary drive is designed as an internal motor, that is, the rotor (3) is placed inside the stator (4), so that the stator (4) surrounds the rotor (3). The rotor (3) is magnetically levitated without contact with the stator (4). Additionally, the rotor (3) is magnetically driven without contact and can rotate around a desired rotation axis by the stator (4). The desired rotation axis is the axis along which the rotor (3) rotates in an operating state when the rotor (3) is in a non-slanted position centered with respect to the stator (4). The desired axis defines the axial direction (A). Typically, the desired rotation axis defining the axial direction (A0) coincides with the center axis of the stator (4).

[0056] Hereinafter, the radial direction refers to the direction perpendicular to the axis direction (A).

[0057] The rotor (3) includes a magnetic effect core (31), which is designed in the form of a circular disk, a circular cylinder, or an annular shape. The “magnetic effect core (31)” refers to a region of the rotor (3) that interacts with the stator (4) to generate torque and magnetic support force. Depending on the design, the magnetic effect core (31) includes one or more permanent magnets. Alternatively, it is possible to design the magnetic effect core (31) without permanent magnets, for example, as a magnetoresistance rotor. The magnetic effect core (31) is made at least partially of a ferromagnetic material, such as iron.

[0058] The magnetic effect core (31) is preferably provided with a jacket (35), which completely encloses the magnetic effect core (31), so that the magnetic effect core (31) does not come into contact with the fluid to be delivered. The jacket (35) is preferably made of plastic, but can also be made of a metal material.

[0059] The rotor (3) further comprises an impeller (32) having a plurality of vanes (33) for delivering fluid from the inlet (21) to the outlet (22). The impeller (32) is placed in the jacket (35). The impeller (32) having the vanes (33) is preferably made of plastic and can be designed, for example, integrally with the jacket (35). Of course, it is also possible to manufacture individual vanes (33) or the entire vane (33) in a separate manufacturing process and connect them to the jacket (35), for example, by a welding process. Of course, it is also possible to make the impeller out of a metal material.

[0060] The impeller (32) is preferably designed as a radial flow impeller, and the impeller receives fluid flow in the axial direction (A) and redirects the fluid in the radial direction.

[0061] A rotary drive having a stator (4) and a rotor (3) can be designed, for example, as a so-called temple motor.

[0062] The characteristic of the temple motor is that the stator (4) comprises a plurality of individual coil cores (41), for example, six coil cores (41), each core comprises a bar-shaped longitudinal leg (42), which extends from a first end to a second end in the axial direction (A), and all first ends (these ends are lower ends as shown in FIG. 1) are connected to each other by a reflux (45). Each coil core (41) further comprises a transverse leg (43), which is positioned at the second end of each longitudinal leg (42) and extends radially, that is, perpendicular to the axial direction (A) and thus perpendicular to each longitudinal leg (42). Each transverse leg (43) extends radially inward, that is, toward the rotor (3). Accordingly, each coil core (41) has an L-shaped design, each longitudinal leg (42) forms an L-shaped long leg that extends in the axial direction (A), and each transverse leg (43) extends perpendicularly to the longitudinal leg (42) in the radial direction toward the rotor (3) forms an L-shaped short leg.

[0063] Each radially inner end of the transverse leg (43) forms a stator pole (46). These stator poles (46) are arranged annularly around the pump housing (2) in which the rotor (3) is placed. The pump housing (2) is designed to be inserted into the stator (4), more precisely between the stator poles (46), so that the stator poles (46) surround the magnetic effect core (31) of the rotor (3). In the operating state, the stator poles (46) and the magnetic effect core (31) of the rotor (3) are located at the same height with respect to the axial direction (A), provided that the rotor (3) is not deflected from its desired position. In the operating state, the rotor (3) is thus magnetically levitated without contact between the stator poles (46).

[0064] Each of the reflux (45) and the coil core (41) is made of a soft magnetic material because it serves as a flux guide element to guide the magnetic flux. Suitable soft magnetic materials are, for example, ferromagnetic or ferrimagnetic materials, namely iron, nickel-iron, or silicon-iron.

[0065] The term "temple motor" was coined because the parallel vertical legs (42) of the coil core (41) that extend parallel to the axial direction (A) and surround the rotor (3) resemble the pillars of the temple.

[0066] The stator (4) further comprises a plurality of windings (6) for generating a rotating electromagnetic field, and with the electromagnetic field, the rotor (3) can be magnetically driven without contact and also magnetically levitated with respect to the stator (4). The windings (6) are designed, for example, with six individual coils, and in each case, one coil is provided to each longitudinal leg (42). Each coil is arranged around each longitudinal leg (42), so that the coil axis is parallel to the axial direction (A) in each case. For example, each longitudinal leg (42) supports exactly one coil (61). Of course, an embodiment in which each longitudinal leg (42) supports more than one coil is also possible.

[0067] The plane on which the rotor (3) is lifted in the operating state is also called the radial plane. The radial plane defines the xy plane of the Cartesian coordinate system in which the z-axis is in the axial direction (A).

[0068] In a preferred embodiment, the electromagnetic rotary drive designed as a temple motor is designed according to the principle of a bearingless motor. This means that during the operation of the centrifugal pump (1), the magnetic effect core (31) of the rotor (3) interacts with the stator pole (46) of the stator (4) according to the aforementioned bearingless motor principle, and the rotor (3) is magnetically driven without contact and is also magnetically levitated with respect to the stator (4) without contact.

[0069] The principle of a bearingless motor has been sufficiently well known to those skilled in the art, so a detailed explanation of its function is no longer necessary. The principle of a bearingless motor means that the rotor (3) is magnetically levitated, and the stator (4) is designed as a bearing and drive stator, and this stator is both an electric drive stator and a magnetic levitation stator. For this purpose, the stator (4) includes a winding (6), and both the driving function and the levitation function are realized through this winding. A rotating electromagnetic field can be generated by the winding (6), and on the one hand, the electromagnetic field can apply torque to the magnetic effect core (31) of the rotor (3), and by this torque, the rotor rotates around the axial direction (A), and on the other hand, the rotating electromagnetic field applies an arbitrarily settable shear force to the magnetic effect core (31) of the rotor (3), so that the radial position of the rotor, that is, the position within the radial plane, can be actively controlled or adjusted. In the case of a bearingless motor, in contrast to traditional magnetic bearings, the magnetic levitation and driving of the motor are realized by a rotating electromagnetic field, which applies torque and settable shear force to the magnetic effect core (31) of the rotor (3). The rotating electromagnetic field required for this can be generated by different coils, or the rotating electromagnetic field can be generated by the mathematical superposition of the required flux, and thus with the help of a single coil system (in this case, winding (6)). Therefore, in the case of a bearingless motor, it is not possible to divide the electromagnetic flux generated by the winding (6) of the stator (2) into an electromagnetic flux that provides only the driving of the rotor (3) and an electromagnetic flux that realizes only the magnetic levitation of the rotor (3).

[0070] According to the principle of a bearingless motor, at least three degrees of freedom of the rotor (3), namely position within the radial plane and rotation around the axial direction (A), can be actively controlled. Regarding axial deflection in the axial direction (A), the magnetic effect core (31) of the rotor (3) is passively magnetically stabilized by magnetic resistance, i.e., cannot be controlled. Regarding the remaining two degrees of freedom, namely inclination with respect to the radial plane perpendicular to the desired axis of rotation, the magnetic effect core (31) of the rotor (3) is also passively magnetically stabilized. This means that the rotor (3) is passively magnetically levitated or passively magnetically stabilized so as not to be tilted (total of three degrees of freedom) by the interaction between the magnetic effect core (31) and the stator pole (46) in the axial direction (A), and is also actively magnetically levitated within the radial plane (two degrees of freedom).

[0071] In the present invention, as a matter of common practice, active magnetic levitation refers to levitation that can be actively controlled or adjusted, for example, by a rotating electromagnetic field generated by a winding (6). Passive magnetic levitation or passive magnetic stabilization is one that cannot be controlled or adjusted. Passive magnetic levitation or stabilization is based, for example, on a magnetic resistance force, and when the rotor is deflected from its equilibrium position, for example, when the rotor is displaced in the axial direction (A) or tilted, the rotor (3) is returned to its equilibrium position by the magnetic resistance force.

[0072] The magnetic effect core (31) of the rotor (3) has a diameter (d), and the diameter (d) represents the outer diameter of the magnetic effect core (31). The magnetic effect core (31) has a height (HR), and this height (HR) is an extension in the axial direction (A). It is particularly advantageous for the passive magnetic stabilization of the rotor (3) to satisfy the geometric condition that the diameter (d) of the magnetic effect core (31) of the rotor (3) is greater than 2.6 times the height (HR) of the magnetic effect core (31) of the rotor (3), i.e., d > 2.6*HR.

[0073] FIG. 2 is a schematic cross-sectional view of one embodiment of a centrifugal pump (1) according to the present invention, which is designed according to the embodiment described with reference to FIG. 1. As is sufficient for understanding, in FIG. 2, the stator (4) is shown only as a stator pole (46). Here, too, the stator (4) and the rotor (3) are designed to interact according to the principle of a bearingless motor as described in relation to FIG. 1.

[0074] The pump housing (2) comprises a housing portion (26) and a cover (25), and the cover (25) is positioned over the housing portion (26) to close the pump housing (2). The housing portion (26) and the cover (25) are preferably made of plastic and are connected to each other rigidly or sealably, for example, by welding. In other embodiments, the housing portion (26) and / or the cover (26) are made of a metal material.

[0075] For better understanding, FIG. 4 shows an axial cross-sectional view (A) of the cover (25), and FIG. 5 is a plan view of the cover (25) seen from the housing part (26). Also, FIG. 6 shows an axial cross-sectional view of the housing part (26), and FIG. 7 shows a plan view of the housing part (26) seen from the cover (25).

[0076] The housing portion (26) includes a lower cylindrical portion (261) and an upper cylindrical portion (262), and these cylindrical portions are arranged coaxially with respect to each other in the front and back with respect to the axial direction (A), and the upper cylindrical portion (262) has a larger diameter than the lower cylindrical portion (261). The lower cylindrical portion (261) of the housing portion (26) includes a bottom (27), which, as shown, forms the lower end of the pump housing (2) and is also arranged perpendicular to the axial direction (A).

[0077] As shown, the cover (25) is seated on the upper end of the upper cylindrical portion (262) and is firmly connected thereto. An inlet (21) for fluid to be delivered is provided in the cover (25). The inlet (21) is designed as an inlet connection, and this inlet connection is preferably manufactured integrally with the cover (25). The inlet (21) designed as an inlet connection extends in the axial direction (A) so that fluid can flow into the pump housing (2) in the axial direction. The inlet connection (21) preferably has an inlet surface (211) through which fluid passes when entering the inlet connection (21), and an outlet surface (212) through which fluid passes when leaving the inlet connection (21) and flowing to the impeller (32). Preferably, the inlet surface (211) is larger than or equal to the outlet surface (212). An outlet (22) for fluid to be delivered is provided in the upper cylindrical portion (262). Here, the outlet (22) is designed as an outlet connection (22), which is preferably manufactured integrally with the housing (26). The outlet (22), designed as an outlet connection, extends parallel to the radial plane, that is, perpendicular to the inlet (21), so that fluid flows out of the pump housing (2) in the radial direction. The outlet connection (22) has an inlet surface (221) through which fluid passes when entering the outlet connection (22), and an outlet surface (222) through which fluid passes when leaving the outlet connection (22). As shown in FIG. 2, preferably, the inlet surface (221) is smaller than the outlet surface (222). The outlet connection (22) is preferably designed to be cylindrical in shape. Nevertheless, a tapered region may be provided in the wall of the outlet connection (22) in which the wall thickness changes so that the inlet surface (221) of the outlet connection becomes smaller than the outlet surface (222) of the outlet connection (21), and thus the inner diameter of the outlet connection (22) changes. Because of this, the flow cross-section for the fluid also changes, which means a plane perpendicular to the central axis (M) of the outlet connection (22) through which the fluid flows.Such embodiments are shown in more detail, for example, in FIG. 8.

[0078] For the cylindrical design of the outlet connection (22), it is preferable that the outlet connection (22) be positioned in the axial direction (A) such that the central axis (M) of the outlet connection (22) is closer to the magnetic effect core (31) of the rotor (3) than to the cover (25) of the pump housing (2). This means that the outlet connection (22) is not positioned in the center of the upper cylindrical part (262) of the housing part (26) in the axial direction (A), but is displaced in the direction of the bottom (27), that is, downward as indicated.

[0079] The rotor (3) (including a magnetic effect core (31), a jacket (35), and an impeller (32)) is positioned between the bottom (27) and the cover (25) of the pump housing (2) in the pump housing (2), and the magnetic effect core (31) having an optional jacket (35) is positioned below the impeller (32) as shown. The magnetic effect core (31) including the jacket (35) is preferably designed to be cylindrical.

[0080] As can be seen in FIG. 1, the pump housing (2) is inserted into the stator (4), so that the upper cylindrical portion (262) is seated on the stator (4), and the lower cylindrical portion (261) of the pump housing (2) is placed on the stator (4), more precisely between the stator poles (46). The pump housing (2) can be secured to the stator (4), for example, by a screw (not shown).

[0081] The rotor (3) is designed and positioned so that, in the operating state, the magnetic effect core (31) of the rotor (3) is surrounded by the stator poles (46) and can also be centered between the stator poles (46) within a radial plane by an electromagnetic field generated by the winding (6) and driven to rotate about the axial direction (A). When the rotor (3) is centered about the axial direction (A) and not deflected, the magnetic effect core (31) is located at the center between the stator poles (46).

[0082] The rotor (3) has an outer diameter (D), which is the diameter (D) of the magnetic effect core (31) including the jacket (35). When the jacket (35) is provided, the outer diameter (D) of the rotor (3) is larger than the diameter (d) of the magnetic effect core (31) of the rotor (3) (Fig. 1).

[0083] The impeller (32) is preferably designed as a radial flow impeller (32), so that the vane (33) deflects the fluid flowing in the axial direction (A) through the inlet (21) radially and delivers it to the outlet (22).

[0084] According to the present invention, at least one indentation is provided in the bottom (27) and / or cover (25), and the indentation is designed to generate local turbulence. In the embodiment described herein, a total of eight indentations (9) are provided, four of which are placed in the cover (25) and four are placed in the bottom (27).

[0085] In other embodiments, the indentation (9) may also be provided only on the cover or only on the bottom. It will also be understood that the number of indentations (9) is one example. Only one indentation, or two or three indentations, or more than eight or significantly more than eight indentations, e.g. more than 50 indentations may be provided. In principle, there is no upper limit to the number of indentations (9). The number and arrangement of the indentations can each be suited to the use case, so that the desired reduction of the force acting on the rotor (3), particularly the hydrodynamic force, is achieved.

[0086] The indentation (9) or the indentations (9) geometrically influence the flow conditions inside the pump housing (2), the purpose of which is to reduce the force acting on the impeller (32) or rotor (3), particularly the force acting in the axial direction (A), and the moment attempting to tilt the rotor (3) toward the radial plane. Thus, the indentation (9) improves the stabilization of the rotor (3) for all degrees of freedom (here, three degrees of freedom) in which the rotor is passively magnetically levitated or stabilized. Thus, the indentation (9) placed in the bottom (27) or cover (25) alters the flow behavior so that the position of the rotor (3) can be set with less effort and movement.

[0087] The reduction in force, particularly hydrodynamic force, is based on the generation of flow turbulence or turbulence caused by the indentation (9), which represents a local change in the shape of the pump housing (2).

[0088] An embodiment according to the present invention having at least one indentation (9) can, in principle, be realized without geometric barriers that reduce flow velocity, without pressure-compensating bores passing through the rotor, and without narrow wedge-shaped fluid gaps that cause localized increases in pressure, as in traditional hydrodynamic bearings. Rather, the indentation (9) causes localized turbulence and flow separation, which reduces the force effect of laminar or turbulent flow on the surface of the rotor (3) exposed to the flow. This turbulence or flow separation reduces dynamic lift acting on the rotor (3) and the force acting on the rotor (3).

[0089] Of course, embodiments of the present invention are also possible in which, for example, a pressure-balancing bore passing through the rotor (3) is additionally provided. Such embodiments are further described with reference to the second embodiment.

[0090] Each indentation (9) may be designed as a dimple, depression, countersink, bore, etc., that locally diverts the flow. For example, the indentation (9) may be spherical or cylindrical. The indentation may have a square or rectangular profile. The indentation may be designed as a pyramidal, conical, truncated conical, or annular shape, or may have a free-form geometric structure. However, for manufacturing reasons, such a geometric structure is preferred for the indentation (9) that may be produced by a drilling or milling tool. For this reason, it is preferred to design the indentation (9) such that each indentation (9) has a circular profile perpendicular to the axial direction (A), that is, is designed as a spherical or cylindrical shape.

[0091] In FIG. 3, one of the indentations (9) is shown as an exemplary cross-sectional view, in which case the indentation is designed as a blind hole in the bottom (27) of the pump housing (2).

[0092] Typically, each indentation (9) has a radial extension (E), which represents the maximum width of the indentation (9) in the radial direction, and the indentation also has a depth (T), which represents the maximum extension of the indentation in the axial direction (A).

[0093] In the case of the blind hole design shown in Fig. 3, the extension (E) is the diameter (E) of the hole in the radial direction, and the depth (T) is the length of the hole in the axial direction (A).

[0094] In fact, it has been proven advantageous for the radial extension (E) for each indentation (9) to be at least 1 / 50 of the outer diameter (D) of the rotor (3), i.e., E is 0.02D or more. Additionally, for each indentation (9), it is advantageous for the radial extension (E) to be at most half of the outer diameter (D) of the rotor (3), i.e., E is 0.5D or less.

[0095] It has been proven advantageous that for each indentation (9) in the axial direction (A), the depth (T) in the axial direction (A) is at least 1 / 150 of the outer diameter (D) of the rotor (3), i.e., T is 0.015D or greater. It is particularly advantageous that the depth (T) in the axial direction (A) is at least 1 / 100 of the outer diameter (D) of the rotor (3), i.e., T is 0.01D or greater.

[0096] In addition, for each indentation (9) in the axial direction (A), it is preferable that the depth (T) in the axial direction (A) is at most 1 / 10 of the outer diameter (D) of the rotor (3), i.e., T is 0.1D or less.

[0097] Regarding the location of the indentation (9) or the indentations (9), the indentation (9) or the indentations (9) are positioned in the radially outer edge region of the bottom (27) and / or cover (25). As shown in FIGS. 2, 4, 5, and 6, in particular, this means that the indentation(s) (9) of the cover (25) of the pump housing (2) is located closer to the radially outer edge of the cover (25) than to the center of the cover (25), and also that the indentation(s) (9) in the circular bottom (27) of the pump housing (2) is located closer to the radially outer edge of the bottom (27) than to the center of the bottom (27).

[0098] In a preferred embodiment of the present invention, the impeller (32) and / or jacket (35) of the pump housing (2) and / or rotor (3) are made of plastic. Preferably, the impeller (32) and jacket (35) of the pump housing (2) and rotor (3) are made of plastic. The pump housing (2), impeller (3), and jacket (35) are all made of the same plastic or at least two different plastics.

[0099] The selection of a suitable plastic depends, of course, on each application. Suitable plastics are, for example, polyethylene (PE), polypropylene (PP), low-density polyethylene (LDPE), ultra-low-density polyethylene (ULDPE), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), acrylonitrile butadiene styrene (ABS), polyacrylic, and polycarbonate.

[0100] In another like-preferred embodiment of the present invention, the impeller (32) and / or jacket (35) of the pump housing (2) and / or rotor (3) is made of one metal material or several different metal materials. Examples of preferred metal materials are titanium or stainless steel.

[0101] FIG. 8 shows a schematic cross-sectional view of a second embodiment of a centrifugal pump (1) according to the present invention. For better understanding, FIG. 9 shows a plan view of the rotor of the second embodiment seen from the bottom of the pump housing. Also, the VIII-VIII cross-sectional line, which is formed when the cross-section shown in FIG. 8 is made, is shown in FIG. 9.

[0102] In the following, only the differences from the first embodiment described above will be discussed. In particular, reference numerals have the same meaning as already described in relation to the first embodiment. It will be understood that all prior descriptions apply to the second embodiment in the same or similar manner.

[0103] In the second embodiment, additional measures are made as per conditions, which, depending on the use case, can further improve the stabilization of the rotor (3) with respect to the axial direction (A) and the inclination toward the radial plane, i.e., the three degrees of freedom that are passively magnetically stabilized. It will be understood that all of these measures may be made, but not all of them need to be made. This means that an embodiment in which one or more of the measures described with reference to the second embodiment are combined with the first embodiment is also possible.

[0104] In the second embodiment of the centrifugal pump (1) according to the present invention shown in FIGS. 8 and 9, the inlet (21) of the pump housing (2), designated as an inlet connection, has a contracted region (213) in which the flow cross-section perpendicular to the axial direction (A) is smaller than the inlet surface (211) and also smaller than the outlet surface (212) of the inlet connection (21). Additionally, the inlet surface (211) of the inlet connection (21) is larger than its outlet surface (212).

[0105] When comparing each of the surfaces, the inlet surface (211) is larger than the outlet surface (212), and the outlet surface (212) is larger than the flow cross-section of the contraction area (213).

[0106] The outlet (22) of the pump housing (2) is designed to be similar to that described in the first embodiment, that is, the outlet connection (22) is positioned with respect to the axial direction (A) such that the inlet surface (221) of the outlet connection (22) is smaller than the outlet surface (222) of the outlet connection (22) and the central axis (M) is closer to the annular magnetic effect core (31) of the rotor (3) than to the cover (25) of the pump housing (2). Referring to the dotted line in the outlet (22), FIG. 8 shows how the interior of the outlet connection (22) is designed, so that the outlet surface (222) of the outlet connection (22) is larger than the inlet surface (221) of the outlet connection (21).

[0107] The size of the outlet surface (222) of the outlet connection (22) and the size of the inlet surface (211) of the inlet connection (21) (including each surrounding wall) are generally predetermined by a standard. Both the outer diameter of the inlet connection (21) at the inlet surface (211) and the outer diameter of the outlet connection (22) at the outlet surface (222) are dimensioned so that the centrifugal pump (1) can be connected to a conventional pipe or tube of the flow system.

[0108] Additionally, the rotor (3) is designed like an annular disc and has a cover plate (36) that covers the vanes (33) of the impeller (32) at the edge facing the inlet (21) or cover (25), and an opening (361) is provided in the cover plate (36) that is positioned in the center, through which fluid can flow to the impeller (32).

[0109] Optionally, the magnetic effect core (31) of the rotor (3) may have a center bore (37) that extends completely through the magnetic effect core (31) and the optional jacket (35) in the axial direction (A).

[0110] Alternatively or additionally, the rotor (3) may include a balancing hole (38) or a plurality of balancing holes (38), each balancing hole (38) extends in the axial direction (A) through the magnetic effect core (31) and optional jacket (35) of the rotor (3) completely. Each balancing hole (38) is preferably positioned off-center, that is, not positioned at the center of the rotor (3).

[0111] In the second embodiment, a plurality of balancing holes (38), namely eight balancing holes (38), are provided.

[0112] The balancing holes (38) are preferably arranged in a circular line, with the center of the circle at the center of the rotor (3). This means that when a center bore (37) is provided in the rotor (3), the balancing holes (38) are arranged in a circle around the center bore (37). Preferably, a maximum or exactly eight balancing holes (38) are provided, and these holes are preferably arranged at equal intervals around the center bore (37) of the rotor (3) or around the center of the rotor (3).

[0113] Each balancing hole (38) has a diameter in each case, and this diameter is smaller than the diameter of the center bore (37).

[0114] A plurality of rear vanes (39) are provided on the axial end face of the rotor (3) facing away from the cover (25) and opposite the bottom (27). In the operating state, these rear vanes (39) are on the opposite side of the bottom (27) of the pump housing (2). In a second embodiment, a total of eight rear vanes (39) are provided.

[0115] The rear vane (39) can be realized, for example, by providing a recess in the jacket (35) of the rotor (3), so that each rear vane (39) is formed between two adjacent recesses.

[0116] Additionally, it is also possible to design the rear vane (39) as a raised portion. For this purpose, a structure similar to an impeller, for example, can be created, which is attached to the axial end surface of the rotor (3), so that the rear vane (39) is on the opposite side of the bottom (27) of the pump housing (2). Of course, the rear vane (38) can be manufactured individually and attached to the axial end surface of the rotor (3).

[0117] Preferably, the rear vane (39) starts at the radially outer edge of the axial end face of the rotor (3) and extends radially inward from there. Each rear vane (39) may extend to the center of the axial end face or to the center bore (37), or, as shown in FIG. 9, each rear vane (39) has a radial length smaller than the radius of the axial end face, for example, half the size. In another embodiment, the rear vane (39) may be designed in a curved shape.

[0118] In a second embodiment, an annular or circular disc-shaped pressure plate (321) is provided on the impeller (32), which is aligned perpendicular to the axial direction (A). The pressure plate (321) is positioned between the end of the impeller (32) facing the magnetic effect core and the cover (25) of the pump housing (2) with respect to the axial direction (A), for example, in the middle of the vanes (33) of the impeller (32). The pressure plate (321) extends between the vanes of the impeller (32). If the rotor (3) has a cover plate (36), the pressure plate (321) is positioned parallel to the cover plate (36) between the magnetic effect core (31) and the cover plate (36) with respect to the axial direction (A). The pressure plate (321) extends between all the vanes (33). Regarding the radial direction, the pressure plate (321) is centered with respect to the rotor (3) and extends radially to cover all balancing holes (38) at least along the axial distance. In the embodiment shown in FIG. 8, the diameter of the pressure plate (321) is significantly smaller than the diameter of the impeller (32), and this diameter is measured at the vane (33).

[0119] FIG. 10 shows a schematic cross-sectional view of a variation of the rotor (3), which differs from the rotor (3) shown in FIG. 8 in that the pressure plate (321) has a larger diameter. In the variation shown in FIG. 10, the pressure plate (321) extends radially to approximately the radially outer end of the vane (33) of the impeller (32).

Claims

Claim 1 A centrifugal pump for delivering fluid comprises a pump housing (2) provided with a rotor (3) for delivering fluid and a stator (4), wherein the stator, together with the rotor (3), forms an electromagnetic rotational drive for rotating the rotor (3) about an axial direction (A), wherein the stator (4) is designed as a bearing and a drive stator, wherein the rotor (3) can be magnetically driven without contact with the stator and can also be magnetically levitated without contact with the stator (4), wherein the rotor (3) is passively magnetically levitated in the axial direction (A) and also actively magnetically levitated within a radial plane perpendicular to the axial direction (A), wherein the pump housing (2) includes a bottom (27) and a cover (25), wherein the rotor (3) is disposed between the bottom (27) and the cover (25) with respect to the axial direction (A) in the pump housing (2), and a plurality of indentations (9) are formed on the inner side of the pump housing (2). A centrifugal pump provided in the bottom (27) and / or cover (25), wherein each of the plurality of indentations is positioned closer to the radially outer edge region of the pump housing (2) than to the center of the pump housing (2), and the plurality of indentations are configured to generate local turbulence and geometrically influence the flow conditions inside the pump housing (2) to reduce the force acting on the rotor. Claim 2 A centrifugal pump according to claim 1, wherein the rotor (3) comprises an annular or disc-shaped magnetic effect core (31) and an impeller (32) having a plurality of vanes (33) for delivering fluid. Claim 3 A centrifugal pump according to claim 1, wherein an inlet (21) for fluid is provided in the cover (25) of the pump housing (2), said inlet (21) is designed so that fluid can flow into the pump housing (2) in an axial direction (A), and the pump housing (2) includes an outlet (22) for fluid, said outlet (22) is designed so that fluid can flow out of the pump housing (2) in a radial direction. Claim 4 In claim 2, the stator (4) has a plurality of stator poles (46) arranged in an annular shape, and the pump housing (2), in which the rotor (3) is disposed, is designed so that the magnetic effect core (31) of the rotor (3) can be inserted into the stator (4) between the stator poles (46) so that the rotor (3) is surrounded by the stator poles (46), thus forming a centrifugal pump. Claim 5 A centrifugal pump according to claim 1, wherein the rotor (3) has an outer diameter (D), and the indentation (9) has a width (E) extending in the radial direction that is at least 1 / 50 of the outer diameter (D) of the rotor (3). Claim 6 A centrifugal pump according to claim 1, wherein the rotor (3) has an outer diameter (D), and the indentation (9) has a width (E) extending radially, which is at most half the outer diameter (D) of the rotor (3). Claim 7 A centrifugal pump according to claim 1, wherein the rotor (3) has an outer diameter (D), and the indentation (9) has a depth (T) in the axial direction (A) that is at least 1 / 150 of the outer diameter (D) of the rotor (3). Claim 8 A centrifugal pump according to claim 1, wherein the rotor (3) has an outer diameter (D), and the indentation (9) has a depth (T) in the axial direction (A) that is at most 1 / 10 of the outer diameter (D) of the rotor (3). Claim 9 In claim 1, the centrifugal pump, wherein the indentation (9) has a circular profile perpendicular to the axial direction (A). Claim 10 In claim 1, the centrifugal pump, wherein the indentation (9) is provided in both the cover (25) and the bottom (27) of the pump housing (2). Claim 11 In claim 1, the pump housing (2) is made of plastic, centrifugal pump. Claim 12 In claim 2, the centrifugal pump, wherein the impeller (32) is made of plastic. Claim 13 A centrifugal pump according to claim 1, wherein the rotor (3) includes a jacket (35) that completely surrounds the magnetic effect core (31) of the rotor, and the jacket is made of plastic. Claim 14 A pump housing, wherein a rotor (3) for delivering fluid is provided inside the pump housing, and the pump housing (2) is designed for a centrifugal pump (1), and the centrifugal pump is designed according to any one of claims 1 to 13. Claim 15 delete

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