Fan

Abstract

The invention relates to a fan having a rotor (2) for generating a fluid flow and having a stator (3), which together with the rotor (2) forms an electromagnetic rotary drive for rotating the rotor (2) about an axial direction (A), the rotary drive being designed as an outer rotor, the rotor (2) comprising a magnetically active core (22) designed in an annular manner and an impeller (21) comprising a hub (23), the stator (3) is designed as a bearing and a drive stator, the rotor (2) can be magnetically driven by the stator without contact and can be magnetically suspended relative to the stator (3) without contact, and the rotor (2) is actively magnetically suspended in a radial plane perpendicular to the axial direction (A), the hub (23) of the impeller (21) completely encloses the magnetically active core (22) of the rotor (2), and the stator (3) is encapsulated in a stator housing (4) made of a low permeability material.

Description

[0001] This application is a divisional application. The invention name of the parent case is “Fan”. The application date is June 3, 2020, and the application number is 202010493770.X. Technical Field

[0002] The invention relates to a fan having a rotor for generating a fluid flow according to the preamble of the independent claim. Background Art

[0003] Fans are usually used to cool various equipment, or are also used to ventilate various buildings, systems or devices. Usually, the task of a fan is to generate a fluid flow, particularly an air flow, which then extracts heat from a specific location or provides heat, for example, as a heat transfer medium. Fluid flow or air flow can also be used to remove unwanted gas accumulation or replace them with fresh air. Examples of using fans are the cooling of electronic circuits or power supplies in computers, for example. Fans can also be integrated into pipes or duct systems to generate desired flows or maintain pressure levels there. In particular, in such applications, it is certainly desirable that fans have a compact design. However, they should provide high performance, which is why fans are often operated at extremely high speeds.

[0004] In many applications, it is also the case that the fan is operated in a dusty or otherwise polluted environment. In particular, dust or dirt deposits on the rotor bearings can lead to very high wear and a very short service life. In particular, also to solve this problem, fans are known in which the rotor is supported without contact, i.e., in particular without mechanical bearings. For example, in the case of these fans, the rotor is supported by magnetic or electromagnetic forces, for which at least one magnetic bearing is usually provided. In the case of magnetic bearings, a basic distinction is made between passive and active magnetic bearings. A passive magnetic bearing or stabilization cannot be controlled or adjusted. It is usually based on magnetic drag. Therefore, a passive magnetic bearing or stabilization is operated without an external energy supply. An active magnetic bearing is a bearing that can be controlled. In the case of an active magnetic bearing, the position of the body to be supported can be actively influenced or adjusted, for example by applying an electromagnetic field. For example, a fan with a contactless magnetically supported rotor is known from European patent specification EP-B-2064450. Therein, a fan is proposed, which comprises at least one passive radial magnetic bearing and an active (i.e. adjustable) axial magnetic bearing system.

[0005] On the other hand, fans without mechanical bearings are particularly suitable for conveying high-purity gases, since there is no risk of wear as might occur with mechanical bearings. Such high-purity gases can be used, for example, in laser technology.

[0006] Even though magnetic bearings for rotors in fans have proven their worth, there is still room for improvement, in particular with regard to making the fan design as compact as possible while maintaining high performance of the fan, or with regard to wear and service life of the fan. In particular in chemically aggressive environments, such as those found in the semiconductor industry, the fan is exposed, for example in ductwork, to aggressive substances, such as corrosive vapors or gases, particle-laden air flows containing solid particles or liquid droplets, such as photoresists or sulfur hexafluoride (SF6), which is used as an etching gas in semiconductor production. Such more aggressive environments often result in increased wear of the fan or an unsatisfactorily short service life. The present invention addresses these problems. Summary of the invention

[0007] The object of the present invention is therefore to propose a very compact and at the same time efficient fan which can be operated without mechanical bearings for the rotor and which is also suitable for use in more aggressive ambient conditions.

[0008] The object of the invention which meets this problem is characterized by the features of the independent claims.

[0009] According to the present invention, a fan is proposed, which has a rotor for generating a fluid flow and a stator, wherein the stator and the rotor together form an electromagnetic rotation drive for rotating the rotor around an axial direction, the rotation drive being designed as an external rotor, the rotor comprising a magnetically active core designed in an annular manner and an impeller, the impeller comprising a hub on which a plurality of blades for generating a fluid flow are arranged, the stator being designed as a bearing and a drive stator, the rotor being able to be magnetically driven by the stator without contact and being able to be magnetically suspended relative to the stator without contact, the rotor being actively magnetically suspended in a radial plane perpendicular to the axial direction, the hub of the impeller completely enclosing the magnetically active core of the rotor, and the stator being encapsulated in a stator housing made of a low magnetic permeability material.

[0010] Preferably, the fluid flow is air flow.

[0011] In order to achieve a very compact design of the fan, the electromagnetic rotary drive of the fan is designed according to the principle of a bearingless motor. At the same time, bearingless motors are sufficiently known to the person skilled in the art that a detailed description of their function is no longer necessary. The stator is designed as a bearing and drive stator, and the rotor can be driven magnetically (i.e. rotated) in the axial direction without contact in the operating state and can be magnetically suspended relative to the stator without contact. The axial direction is determined by the desired rotation axis of the rotor.

[0012] The term "bearingless motor" means that the rotor is magnetically suspended without contact, wherein no separate magnetic bearings are provided. The stator is both the stator of the electric drive and the stator of the magnetic bearing. The stator comprises windings, with which a rotating magnetic field can be generated, which exerts a torque on the rotor on the one hand, causing it to rotate, and on the other hand exerts a freely adjustable lateral force on the rotor, so that its radial position (i.e. its position in the radial plane) can be actively controlled or adjusted. Thus, at least three degrees of freedom of the rotor can be actively adjusted. With respect to its deflection in the axial direction, the rotor is passively magnetically stabilized by the magnetic drag force, i.e. it is uncontrollable. The rotor is also passively magnetically stabilized with respect to the remaining two degrees of freedom, i.e. tilted with respect to a radial plane perpendicular to the axial direction.

[0013] A fundamental aspect of the principle of a bearingless motor is that in the bearing and the drive stator, no distinction can be made between the bearing unit and the drive unit. From the prior art, for example, electromagnetic drive and bearing arrangements are known, in which the stator of the drive and the stator of the magnetic bearing are combined to form a structural unit. The stator comprises one or more bearing units as well as a drive unit, which can be arranged, for example, between two bearing units. Thus, such an arrangement shows a bearing unit that can be separated from a drive unit specifically for magnetic bearings. However, such arrangements should not be understood as bearingless motors in the sense of the present application, since they actually have a separate bearing unit that realizes the bearing of the rotor, which is separated from the drive function. In the case of a bearingless motor in the sense of the present application, it is not possible to separate the stator into a bearing unit and a drive unit. It is this feature that gives the bearingless motor its name.

[0014] Another essential aspect of the invention is that both the magnetically active core of the rotor and the stator are completely and preferably hermetically enclosed. In this way, the magnetically active core of the rotor and the stator and in particular, for example, the windings on the stator or the coil core of the stator are reliably protected, in particular also in chemically aggressive environments in which the fan comes into contact with, for example, corrosive gases, steam or other corrosive or acidic fluids. The magnetically active core of the rotor and the stator are also reliably protected from abrasive fluids such as slurries. By completely enclosing the magnetically active core and the stator, the fan has at least significantly reduced wear and a significantly longer service life even in an aggressive environment.

[0015] The magnetically active core of the rotor is completely enclosed in the hub of the impeller, which thus forms the housing of the rotor. The stator is encapsulated in a stator housing which is made of a low-permeability material, i.e. a material having only a low magnetic permeability (magnetic permeability). For example, such a low-permeability material may be a plastic. Within the framework of the present application, a low-permeability material is understood to be a material whose magnetic permeability number (relative magnetic permeability) deviates only slightly or not at all from 1 (the magnetic permeability number of a vacuum), as is commonly practiced. In any case, a low-permeability material has a magnetic permeability number of less than 1.1.

[0016] Due to the complete encapsulation of the magnetic cores of the stator and rotor, both the hub enclosing the magnetically active core of the rotor and the wall of the stator housing must be arranged in the magnetic air gap between the rotor and the stator. This requires a large distance between the magnetically interacting parts of the rotor and the stator with respect to the radial direction, i.e. the magnetic air gap in the magnetic circuit of the rotor and the stator is large. Surprisingly, despite this large magnetic air gap, a reliable and stable bearing of the rotor relative to the stator is possible.

[0017] Preferably, the impeller is made of a first plastic and the stator housing is made of a second plastic.The first and second plastics may be the same plastic, or the first and second plastics may be different plastics.

[0018] According to a preferred embodiment, the fan comprises a substantially tubular housing with a suction side and a pressure side, wherein the rotor and the stator housing are arranged in the housing, and wherein the stator housing is fixed in the housing by a plurality of struts. This allows the fan to be easily integrated into a duct or a duct system in order to generate there, for example, a desired flow or pressure. For this purpose, the housing of the fan can comprise a flange in each case both on the suction side and on the pressure side, by means of which the fan can be attached to the duct. The struts with which the stator housing is fixed can advantageously be designed as diffusers for the fan.

[0019] Another preferred measure is that the stator housing has a first housing part and a second housing part, the first housing part being arranged in the rotor and surrounded by the magnetic core of the rotor, and the second housing part having an outer diameter that is at least as large as the outer diameter of the magnetically active core of the rotor. This optimized shape of the stator housing allows additional components, such as power electronics for the electromagnetic rotary drive, to be arranged in the stator housing and thus protected by the stator housing.

[0020] Preferably, the fan comprises a check device for controlling or regulating the fan, which is arranged in the second housing part of the stator housing. This measure enables a particularly compact and space-saving design. The entire check device, which may include power electronics for generating an electromagnetic field, a regulating device for driving and supporting the rotor, and a sensor or evaluation unit (if necessary), is integrated or built into the stator housing. Thus, it is only necessary to supply energy to the fan and, if necessary, to provide a signal for, for example, starting or stopping the fan or determining the rotational speed. For this purpose, a power supply line can be provided for supplying electrical energy to the fan. The power supply line is preferably arranged inside one of the pillars used to fix the stator housing.

[0021] Furthermore, it is advantageous if a sensor is provided with which the pressure or flow rate of the fluid flow can be determined, wherein the sensor is signal-connected to the control device and the control device is designed to regulate or control the pressure or flow rate. In this way, for example, the fluid flow generated by the fan can be controlled or regulated. The sensor can be arranged on the suction side or on the pressure side. In particular, the sensor can also be fixed to the stator housing.

[0022] According to a preferred embodiment, the stator comprises a plurality of coil cores, each extending in radial direction, each carrying a concentrated winding for generating a rotating electromagnetic field. Particularly preferably, the stator has exactly six coil cores, each carrying a concentrated winding.

[0023] In a preferred embodiment, the magnetically active core of the rotor comprises an annular reflux and a plurality of permanent magnets, wherein the reflux is designed continuously and is made of a soft magnetic material, and each permanent magnet is designed with a sickle-shaped cross section and is fitted into the radial inside of the reflux. On the one hand, with this embodiment, very good torque and very good stiffness of the magnetic bearing can be achieved, and on the other hand, the cost of the permanent magnets is reduced because particularly little permanent magnetic material is required.

[0024] Another advantageous measure is to provide a heat-conducting element for heat dissipation in the stator housing, the heat-conducting element being designed so that it at least surrounds the inspection device. The heat-conducting element is preferably a metal heat-conducting element and is, for example, made of aluminum. The heat-conducting element can, for example, be cup-shaped so that it extends along the inner wall of the second housing part.

[0025] In order to support the magnetic bearing of the rotor, the rotor is preferably designed for hydrodynamic stabilization of the rotor to prevent tilting. Due to this hydrodynamic stabilization, the magnetic bearing is also advantageously damped with respect to the axial direction, thereby preventing oscillations of the axial bearing.

[0026] There are various measures for hydrodynamic stabilization, some of which are now presented in a non-exhaustive list: The hub of the impeller has a suction side end and a pressure side end, wherein the magnetically active core of the rotor is arranged closer to the pressure side end of the hub than to the suction side end relative to the axial direction. This means that the magnetically active core is not centered in the hub of the impeller relative to the axial direction, but is displaced in the direction of the pressure side.

[0027] The hub of the impeller can comprise an inlet region at its suction-side end, wherein the hub is designed to taper in the direction of the suction-side end.

[0028] The impeller may be designed in such a way that each blade has a leading edge, each leading edge extending perpendicularly to the axial direction.

[0029] The impeller may be designed in such a way that each blade has a trailing edge, each trailing edge opening into the hub at an angle different from 90° to the axial direction.

[0030] The impeller can be designed in such a way that each blade has a trailing edge, wherein at least one stabilizing ring is provided at the trailing edge, which stabilizing ring is arranged coaxially with the rotor.

[0031] The impeller may also be designed in such a way that each blade opens into the hub at a position between the suction-side end and the pressure-side end of the hub with respect to the axial direction.

[0032] Embodiments of the fan are possible in which only any one of the mentioned measures is implemented as well as embodiments in which any combination of the mentioned measures is implemented.

[0033] Further advantageous measures and embodiments of the invention are revealed in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention will be explained in more detail below with reference to examples and drawings. In the drawings (partially in section): Figure 1 is a perspective view of one embodiment of a fan according to the present invention; Figure 2 is along Figure 1 A cross section along the axial direction of the embodiment through the cross section line II-II; Figure 3 as Figure 2 , but in perspective; Figure 4 is along Figure 2 A cross section through the embodiment perpendicular to the axial direction of the cross section line IV-IV; Figure 5 as Figure 4 , but in perspective; Figure 6is a cross section in the axial direction through a magnetically active core of a rotor and a stator of a variation of the magnetically active core for a rotor in a perspective view; Figure 7 It is along Figure 6 The perspective view of the section line VII-VII in Figure 6 The magnetic action of the rotor core and the cross section of the stator perpendicular to the axial direction; Figure 8 as Figure 7 , but in the plane view for the cross-sectional surface; Fig. 9 as Figure 8 , but is used to clarify the size; Fig.10 as Fig. 9 , but is used to illustrate another dimension; Fig.11 as Figure 6 , but in the plane view for the cross-sectional surface; Fig.12 is a section in the axial direction through a first variant of the design for a stator housing with a heat-conducting element in a perspective view; Fig.13 as Fig.12 , but for a second variant of the design for the stator housing; Fig.14 as Fig.12 , but for a third variant of design for the stator housing; Fig.15 yes Fig.14 A perspective view of a heat-conducting element for a third variant of the design of the stator housing of this embodiment; Fig.16 is a schematic cross-sectional view of a rotor in which blades of an impeller are arranged in a fan housing in a section along an axial direction; Figures 17 to 21 In each case as Fig.16 , but for different variants of the design for a hydrodynamically stable rotor having a rotor; and Figure 22 to Figure 24 are schematic diagrams of different variants of embodiments of a fan according to the invention arranged in a duct. DETAILED DESCRIPTION

[0035] Figure 1 A perspective view of an embodiment of a fan according to the present invention is shown, which is generally indicated by reference numeral 1. For better understanding, Figure 2 and Figure 3 Still shows that according to Figure 1 Two cross-sectional views of this embodiment along the section line II-II, wherein Figure 2 shows a plan view for a cross-sectional surface, and Figure 3 The cross section is shown in perspective.

[0036] The fan 1 comprises a rotor 2 for generating a fluid flow (e.g. an air flow or a gas flow) and a stator 3, which together with the rotor 2 forms an electromagnetic rotary drive for rotating the rotor 2 about an axial direction A. The rotor 2 and the stator 3 form a rotary drive which is designed as an outer rotor, i.e. the rotor 2 surrounds the stator 3 in the operating state and rotates about the inner stator 3.

[0037] The electromagnetic rotary drive is designed according to the principle of a bearingless motor and comprises a rotor 2 which can be driven magnetically without contact and is designed without coils, and a stator 3 which is designed as a bearing and drive stator, with which the rotor 2 can be driven magnetically without contact about a desired axis of rotation in the operating state and can be magnetically suspended without contact relative to the stator 3. The desired axis of rotation defines an axial direction A. The stator 3 is arranged on the inside relative to the rotor 2.

[0038] In the following, the desired rotation axis, which defines the axial direction A, refers to the rotation axis about which the rotor 2 rotates when the rotor 2 is in a centered and non-tilted position relative to the stator 3. The rotor 2 is then centered in a plane perpendicular to the central axis of the stator 3 and is not tilted relative to this plane. The desired rotation axis usually coincides with the central axis of the stator 3.

[0039] In the following, the direction perpendicular to the axial direction is also generally referred to as the radial direction. The radial plane refers to the plane perpendicular to the desired rotation axis or axial direction A, which is the magnetic center plane of the stator 3. The radial plane defines the xy plane of a Cartesian coordinate system, the z axis of which extends along the axial direction A.

[0040] For better understanding, Figure 4 and Figure 5 Each shows the Figure 1 The cross section of the embodiment shown, wherein the cross section is perpendicular to the axial direction A in a radial plane, i.e. in the magnetic center plane of the stator 3, as shown in FIG. Figure 2 Indicated by section line IV-IV. Figure 4 A plan view is shown for a cross-sectional plane, i.e. the magnetic center plane of the stator 3, while Figure 5 The cross section is shown in perspective.

[0041] The rotor 2 of the rotary drive is designed to be coil-free, i.e. no winding is arranged on the rotor 2. The rotor 2 comprises a magnetically active core 22 designed in an annular manner, and an impeller 21 comprising a hub 23 and a plurality of blades 24 arranged on the hub 23. The impeller 21 is designed as an axial impeller. The blades 24 generate a fluid flow in the operating state. The hub 23 and the blades 24 of the impeller 21 are composed of a first plastic. The rotor 2 is both the rotor 2 of the fan 1 with which the air flow is generated and the rotor 2 of the electromagnetic rotary drive with which the rotation of the impeller 21 is driven. This embodiment, also referred to as an integral rotor, enables a particularly compact design of the fan 1.

[0042] The magnetically active core 22 of the rotor 2 is designed in the form of an annular disk or a circular cylindrical ring, wherein in the axial direction A there is a height HR ( Fig.11 ) and has an inner radius IR( Fig. 9 ). The “magnetically active core 22” of the rotor 2 refers to the region of the rotor 2 which interacts magnetically with the stator 3 for generating torque and for generating magnetic bearing forces.

[0043] The magnetically active core 22 of the rotor 24 comprises an annular radial outer returner 222 and at least one permanent magnet 221, which can be designed, for example, as a permanent magnet ring. Of course, a plurality of permanent magnets 221 can also be provided, each of which is designed, for example, as an annular segment. In the embodiment described here - see in particular Figure 4 and Figure 5 -- A total of four permanent magnets 221 are provided, which together form a ring. Figure 4 and Figure 5 As indicated by the arrows without reference numerals in the figure, each permanent magnet 221 is magnetized in the radial or diametric direction. Adjacent permanent magnets 221 are each polarized in opposite directions, i.e., in each case, permanent magnets 221 polarized radially or diametrically inwardly and permanent magnets 221 polarized radially or diametrically outwardly are adjacent to each other. Here, the rotor 2 is thus four-pole, i.e., designed with a pole pair number of two.

[0044] Those ferromagnetic or ferrimagnetic materials which are magnetically hard, i.e. have a high coercive field strength, are generally referred to as permanent magnets. The coercive field strength is the magnetic field strength required to demagnetize a material. Within the framework of the present application, a permanent magnet is understood to be a material having a coercive field strength, more precisely a coercive field strength of the magnetic polarization, which corresponds to more than 10,000 A / m. All permanent magnets 221 of the magnetically active core of the rotor are preferably composed of a neodymium iron boron (NdFeB) or samarium cobalt (SmCo) alloy.

[0045] The magnetically active core 22 further comprises an annular returner 222 which is arranged radially on the outside around all the permanent magnets 221 . The returner 222 is made of a ferromagnetic material and serves to guide the magnetic flux. The returner 222 encloses all the permanent magnets 221 .

[0046] The magnetically active core 22 of the rotor 2 is arranged in the hub 23 of the impeller 21, so that the hub 23 of the impeller 21 completely encloses the magnetically active core 22 of the rotor 2 and the hub 23 forms a housing for the magnetically active core 22 of the rotor 2. For this purpose, for example, during the manufacturing process, the magnetically active core 22 can be encapsulated by molding with a first plastic material from which the hub 23 is made. However, it is also possible to provide a hub 23 with an annular groove into which the magnetically active core 22 is inserted. Subsequently, the annular groove is closed with a plastic cover of a suitable shape, which is then connected to the rest of the hub 23, for example, by a welding process. The magnetically active core 22 of the rotor 2 is then hermetically encapsulated.

[0047] The stator 3 includes a plurality of (six in this case) coil cores 31 arranged in a star shape. Each coil core 31 is designed in a bar shape and extends radially outward from a central pole piece 32 arranged in the center of the stator 3 and ends at a circular pole shoe 311 (see also Fig. 9 ), so that each coil core 31 has a substantially T-shaped appearance. The radially outer boundary surfaces of all pole shoes 311 are located on a circular cylinder coaxial with the longitudinal axis of the central pole piece 32.

[0048] The coil cores carry windings in order to generate the rotating electromagnetic fields necessary for the magnetic drive and magnetic bearing of the rotor 2. In the embodiment described here, for example, the windings are designed in such a way that in each case a concentrated winding is wound around each coil core 31 as a discrete coil 33. These coils 33 serve in the operating state to generate those rotating electromagnetic fields with which a torque acts on the rotor 2 and with which any adjustable transverse forces can be exerted on the rotor 2 in the radial direction, so that the radial position of the rotor 2, i.e. its position in a radial plane perpendicular to the axial direction A, can be actively controlled or adjusted.

[0049] The center pole piece 32 and the coil core 31 of the stator 3 and the returner 222 of the magnetically active core 22 of the rotor 2 are both made of soft magnetic materials because they are used as magnetic flux conducting elements for guiding magnetic flux. Suitable soft magnetic materials are, for example, ferromagnetic or ferrimagnetic materials, in particular iron, nickel-iron or silicon-iron. In particular, for the stator 3, it is preferred here to be a design as a stator sheet metal stack, in which the coil core 31 and the center pole piece 32 are made of sheet metal, that is, they are composed of several stacked thin elements. The returner 222 of the magnetically active core 22 of the rotor 2 can also be made of sheet metal. As an alternative to the sheet metal design, soft magnetic composite materials composed of electrically insulating and compressed metal particles can also be used for the rotor and / or stator. In particular, these soft magnetic composite materials (also described as SMC (soft magnetic composite)) can be composed of iron powder particles coated with an electrically insulating layer. These SMCs are then formed into the desired shape using a powder metallurgy process.

[0050] As already mentioned above, the electromagnetic rotary drive with rotor 2 and stator 3 is designed according to the principle of a bearingless motor, wherein the rotor 2 is magnetically driven without contact and is magnetically suspended relative to the stator 3 without contact, wherein no separate or separable magnetic bearing is provided for the rotor 2. The bearing function and the drive function are realized with the same stator 3, wherein it is not possible to separate the stator 3 into a bearing unit and a drive unit. The drive function and the bearing function cannot be separated from each other. The term "bearingless motor" has been established for such a rotary drive, since no separate magnetic bearing or magnetic bearing unit is provided for the rotor 2. These particularly efficient bearingless motors are characterized in particular by their extremely compact design, wherein the "contactless" concept is simultaneously realized.

[0051] Thus, a bearingless motor is an electromagnetic rotary drive in which the rotor 2 is magnetically suspended relative to the stator 3, wherein no separate magnetic bearing or magnetic bearing unit is provided. For this purpose, the stator 3 is designed as a bearing and drive stator, which is both the stator 3 of the electric drive and the stator 3 of the magnetic bearing. A rotating magnetic field can be generated by means of the coils 33 of the bearing and the drive stator 3, which on the one hand exert a torque on the rotor 2 that causes it to rotate, and on the other hand exert an arbitrarily adjustable transverse force on the rotor 2, so that its radial position (i.e. its position in the radial plane) can be actively controlled or adjusted. Bearingless motors are now well known to those skilled in the art, so that a detailed description of their function is no longer necessary.

[0052] Thus, three degrees of freedom of the rotor 2 can be actively controlled or adjusted, namely its position in the radial plane (two degrees of freedom) and its rotation about the axial direction A. With respect to its axial deflection in the direction of the desired axis of rotation, the rotor 2 is passively (i.e. uncontrollable) magnetically stabilized or suspended by magnetic resistance. The rotor 2 is also passively magnetically stabilized or suspended with respect to the remaining two degrees of freedom, i.e. tilting with respect to a radial plane perpendicular to the axial direction. Thus, the radial bearing of the rotor 2 corresponds to the functionality of an active radial magnetic bearing, and the axial bearing corresponds to the functionality of a passive axial magnetic bearing.

[0053] Compared with conventional magnetic bearings, the drive and magnetic bearing of the motor of the bearingless motor are realized via a rotating electromagnetic field. Generally, in a bearingless motor, the magnetic drive and bearing functions are generated by the superposition of two rotating magnetic fields, which are usually called drive and control fields. The two rotating fields generated by the windings or coils 33 of the stator 3 usually have a pole pair number that differs by one. For example, if the drive field has a pole pair number p, then the control field has a pole pair number p+1 or p-1. The drive field is used to generate a tangential force acting on the rotor 2 in the radial plane, thereby generating a torque that rotates the rotor 2 around the axial direction A. By superimposing the drive field with the control field, any adjustable lateral force can also be generated on the rotor 2 in the radial plane, using which the position of the rotor 2 in the radial plane can be adjusted. Therefore, it is impossible to divide the electromagnetic flux generated by the coils 33 of the stator 3 into an (electric) magnetic flux that only provides the drive of the rotor 2 and an (electric) magnetic flux that only realizes the magnetic bearing of the rotor 2.

[0054] On the one hand, in order to generate the drive field and the control field, two different winding systems can be used, i.e., one for generating the drive field and one for generating the control field. Then, the coils for generating the drive field are generally referred to as drive coils, while the coils for generating the control field are referred to as control coils. Then, the current applied to these coils is referred to as drive current or control current. On the other hand, it is also possible to generate the drive and bearing functions with only one single winding system, so that there is no distinction between the drive coils and the control coils. This can be achieved in such a way that the values ​​of the drive current and the control current determined in each case by the inspection device 5 are added or superimposed by calculation (i.e., for example, by software), and the resulting total current is applied to the corresponding coil 33. In this case, it is of course no longer possible to distinguish between the control coil and the drive coil. In the embodiment described here, the latter variant is implemented, i.e., there is no distinction between the drive coil and the control coil, but only one winding system is present, in which the sum of the drive current and the control current determined mathematically is applied to the six coils 33 of the winding system. However, it is of course also possible to design the fan 1 according to the invention to have two separate winding systems, i.e., to have a separate drive coil and a separate control coil.

[0055] For example, sensor technology for determining the position of the rotor, control, power supply and regulation of the rotary drive designed as a bearingless motor are known to the person skilled in the art and do not require any further explanation here.

[0056] In the fan 1 according to the invention, not only is the magnetically active core 22 of the rotor 2 completely enclosed by the hub 23 of the impeller 21, but the stator 3 is also encapsulated in a stator housing 4 made of a low magnetic permeability material. This low magnetic permeability material is preferably a second plastic.

[0057] Low permeability materials are materials that have only a low permeability (magnetic conductivity). Within the framework of the present application, low permeability materials are understood, as is common practice, to be those materials whose permeability number (relative permeability) deviates only slightly or not at all from 1 (the permeability number of a vacuum). In any case, low permeability materials have a permeability number of less than 1.1. Thus, low permeability materials have a much lower permeability than, for example, the ferromagnetic material of which the coil core 31 is made.

[0058] As already mentioned above, this low magnetic permeability material of the stator housing 4 is preferably a second plastic. Therefore, preferably, the impeller 21 of the rotor 2 is made of a first plastic, and the stator housing 4 is made of a second plastic. Of course, the first plastic and the second plastic can be the same plastic, and this is also preferred for many applications. On the other hand, the first plastic and the second plastic can also be different plastics.

[0059] For example, the first and / or second plastic can be one of the following plastics: polyethylene (PE), low-density polyethylene (LDPE), ultra-low-density polyethylene (ULDPE), ethylene-vinyl acetate (EVA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP), polyurethane (PU), polyvinylidene fluoride (PVDF), acrylonitrile-butadiene-styrene (ABS), polyacrylic, polycarbonate (PC) or silicone. For many applications, the materials polytetrafluoroethylene (PTFE) and perfluoroalkoxy polymer (PFA) (known under the trade name Teflon) are also suitable as the first and / or second plastic.

[0060] Preferably, one of these plastics is used as the first plastic to hermetically encapsulate the magnetically active core 22 of the rotor 2, and one of these plastics is used as the second plastic to hermetically encapsulate the stator 3. Since this is sufficient to understand, no distinction will be made between the first and second plastics hereinafter.

[0061] Since all the plastics mentioned have low magnetic permeability, i.e. they conduct magnetic flux poorly, the area of ​​the hub 23 and the stator housing 4 arranged in the radial direction between the magnetically active core 22 of the rotor 2 on the one hand and the pole shoes 311 of the coil core 31 of the stator 3 on the other hand is allocated to the magnetic air gap between the rotor 2 and the stator 3. The magnetic air gap between the rotor 2 and the stator 3 is therefore equal to the distance between the magnetically active core 22 of the rotor 2 and the pole shoes 311 of the coil core 31 of the stator 3 in the radial direction. The hermetic sealing of the magnetically active core 22 and the hermetic sealing of the stator 3 thus lead to a larger magnetic air gap than other bearingless motors. When the rotor 3 is centered, the width of the magnetic air gap is, for example, 4 mm or even larger. This means that, with a width of the magnetic air gap of 4 mm, the maximum diameter of the stator 3 measured from one pole shoe 311 to the opposite pole shoe 311 is 8 mm smaller than the inner diameter of the magnetically active core 22 of the rotor 2.

[0062] The fan 1 further comprises a housing 6 which is substantially tubular in shape and coaxially surrounds the impeller 21 of the rotor 2. The housing 6 has a suction side 61 ( Figure 2 , Figure 3 ), and a pressure side 62 through which the fan 1 discharges air. The rotor 2 and the stator 3 enclosed thereby and the entire stator housing 4 are arranged in a tubular housing 6 between the suction side 61 and the pressure side 62, wherein the stator housing 4 is preferably attached to the pressure side 62 of the housing 6 via a plurality of struts 7. Each strut 7 extends outwardly from the stator housing 4 in a radial direction to the inner wall of the tubular housing 6. All struts 7 can be designed as diffusers. Preferably, the struts 7 are made of the first plastic or the second plastic.

[0063] The housing 6 also has a suction side flange 63 on the suction side 61 and a pressure side flange 64 on the pressure side 62. By means of the flanges 63 and 64, the fan 1 can be integrated in a simple manner into a duct or duct system (see for example Fig. 22 ). In the embodiment described here, the two flanges 63, 64 are designed to be rectangular and in particular square, and in each corner of each flange 63, 64, a mounting hole 65 is provided in each case for respectively receiving fastening means, such as screws (not shown), so that the fan 1 can be attached to another element, for example to another flange, in a simple manner.

[0064] The stator housing 4 comprises a first housing part 41 and a second housing part 42, which are arranged one above the other with respect to the axial direction A, the first housing part 41 being arranged on the suction side 61 of the housing 6, and the second housing part being arranged on the pressure side 62 of the housing 6. Each housing part 41, 42 has a cylindrical shape, and the outer diameter D2 ( Figure 2) is larger than the outer diameter D1 of the first housing portion 41. In general, the stator housing 4 encloses the space generated when L rotates around the long leg.

[0065] The outer diameter D1 of the first housing part 41 is smaller than the inner diameter of the central recess in the hub 23 of the rotor 2, so that the first housing part 41 can be inserted into the central recess. The stator 3 of the electric rotary drive is arranged in the first housing part 41 of the stator housing 4, so that when the stator housing 4 is inserted into the central recess in the hub 23 of the rotor 2, the stator 3 is surrounded by the magnetically active core 22 of the rotor 2. This results in the usual arrangement of the rotary drive of the outer rotor, in which the stator 3 is surrounded radially inwardly by the rotor 2 on the inside.

[0066] The outer diameter D2 of the second housing part 42 of the stator housing 4 is dimensioned so that it is at least as large as the outer diameter DM of the magnetically active core 22 of the rotor 2. In each case, the stator housing 4 is arranged on the second housing part 42 with its support 7 fixed in the housing 6 and extends from there in the radial direction to the inner wall of the housing 6. In the second housing part 42 of the stator housing 4, which is arranged below the rotor 2 according to the representation, a test device 5 is provided, with which the fan 1 is driven and regulated. The test device 5 includes power electronics, with which the current for the coil 33 is generated, and a regulating and control device, with which the drive of the rotor 2 and the radial position of the rotor 2 are regulated or controlled. In the same way, the test device 5 can include a flow circuit and / or a pressure control circuit, which can be activated after the connection of an optional pressure or flow sensor. The power electronics is preferably designed as a circuit board or a printed circuit board (PCB). In addition, the test device 5 can include different sensors and an evaluation unit for processing the signals provided by the sensors. Due to the fact that the entire inspection device 5 is also arranged in the stator housing 4, an extremely compact and space-saving design of the fan 1 is achieved. In addition, the inspection device 5 in the hermetically sealed stator housing 4 is also protected from chemically aggressive ambient conditions as well as dust and dirt.

[0067] Furthermore, a feed conductor 71 is provided for the cable 72, via which the inspection device 5 is supplied with energy. The cable 72 can also be used to transmit analog or digital signals to or from the inspection device 5. For this purpose, the cable 72 is connected, for example, to a voltage source and the communication interface 400 ( Fig. 22 The feed conductor 71 from the second housing part 42 of the stator housing 4 to the surroundings of the fan 1 is particularly preferably arranged in one of the struts 7 , or the feed conductor 71 serves as one of the struts 7 .

[0068] Since the magnetically active core 22 of the stator 3 and the rotor 2 as well as the inspection device 5 are thus hermetically encapsulated, the fan 1 is very suitable for use in problematic environments, such as those found in the semiconductor industry. In those environments, corrosive vapors, gases or even acidic substances may be present, which may significantly damage conventional fans after only a short operating period. However, the fan 1 is also particularly resistant to mechanical contamination of the environment, such as dust or solid particles. Due to the bearingless concept and the hermetic packaging of the magnetically active core 22 of the stator 3 and the rotor 2, the fan 1 is particularly suitable for use in high-purity environments or for conveying high-purity gases, such as those used in laser technology.

[0069] Figure 6-8 A preferred variant of the design of the magnetically active core 22 of the rotor 2 is shown. Since it is sufficient to understand, for a better overview, in Figure 6 , Figure 7 and Figure 8 Only the magnetically active core 22 of the rotor 2 and the stator 3 are shown. Figure 6 This variant is shown in a perspective cross-sectional view, wherein the section is taken along an axial direction A through the centre of a central pole piece 32 of the stator 3 . Figure 7 Along Figure 6 The perspective sectional view of the section line VII-VII in FIG. 2 shows this variant of the magnetically active core 22 of the rotor 2 . The section is taken perpendicularly to the axial direction A through the center of the stator 3 . Figure 8 Shown for Figure 7 Plan view of the cross-sectional surface.

[0070] In this also annular variant of the magnetically active core 22 for the rotor 2, an annular return 222 and a plurality of permanent magnets 221 (here four) are arranged radially on the outside. The return 222 is designed to be continuous and is made of a soft magnetic material. Each of the four permanent magnets 221 is designed in such a way that it has a sickle-shaped cross section perpendicular to the axial direction A and extends over the entire height HR ( Fig.11 ) The permanent magnets 221 are arranged equidistantly about the circumferential direction on the radial inner side of the returner 222 and are fitted into correspondingly shaped grooves in the radial inner side of the returner 222 .

[0071] Therefore, each permanent magnet 22 is bounded in the radial direction by two circular cylindrical segments, i.e., by the radial inner side of a circular cylindrical segment having the same radius and the same center as the radial inner boundary surface 223 of the magnetic action core 22 of the rotor 2, and by the radial outer side of a circular cylindrical segment whose center is displaced from the center of the radial inner boundary surface 223 of the magnetic action core 22 and whose radius is smaller than the radius of the radial inner boundary surface of the magnetic action core 22.

[0072] like Figure 6-Figure 8 As shown by the arrows without reference numerals in the figure, each permanent magnet is magnetized in the radial or diameter direction. The permanent magnets 221 are magnetized alternately in the radial or diameter direction of the outer side and in the radial or diameter direction of the inner side with respect to the circumferential direction of the rotor 2, so that the corresponding adjacent permanent magnets 221 are magnetized in opposite directions. The rotor 2 is therefore designed to have four magnetic poles, that is, to have a magnetic pole pair number of 2.

[0073] In order to make the fan 1 as powerful and efficient as possible, a high rotational speed of the rotor 2 is preferred, which is why the rotor 2 is preferably designed with four magnetic poles.

[0074] In particular, also with regard to a reliable contactless magnetic bearing of the rotor 2, it is particularly preferred that the annular disk-shaped magnetically active core 22 of the rotor 2 (regardless of its specific design) has an inner diameter of the height HR of the magnetically active core 22 in the axial direction A ( Fig.11 ) is at least 1.5 times and preferably twice as large as the height HR of the magnetic action core 22 when viewed in the radial direction. If the height HR when viewed in the radial direction varies on the magnetic action core 22, i.e. it is not constant, then at least at the radially inner boundary surface 223 of the magnetic action core 22, the following condition should be satisfied, i.e. the inner diameter of the magnetic action core 22 is at least 1.5 times and preferably twice as large as the height HR of the magnetic action core 22. This means that HR specifies the height of the magnetic action core 22 at its radially inner boundary surface 223.

[0075] Below, based on Figures 9 to 11 Some preferred geometries of the magnetically active core 22 of the rotor 2 and of the stator 3 are described, which are particularly advantageous for a contactless drive of the rotor 2 and a contactless magnetic bearing of the rotor 2 . Fig. 9 and Fig.10 In each case, the Figure 8 The same illustration, ie a section perpendicular to the axial direction A, but with some dimensions drawn in. Fig.11 Basically shows that Figure 6 The same illustration, ie a section along the axial direction A, but with some dimensions indicated.

[0076] MR designates the geometrical center of the annular magnetically active core 22 of the rotor 2 in a radial plane.

[0077] IR designates the inner radius of the magnetically active core 22. This means that IR designates half of the inner diameter of the magnetically active core 22.

[0078] HR designates the height of the magnetically active core 22 in the axial direction A at the radially inner boundary surface 223 of the magnetically active core 22 .

[0079] BM designates the maximum thickness of the permanent magnet 221 in the radial direction.

[0080] BR designates the thickness of the magnetically active core 22 in the radial direction.

[0081] MP designates the geometric center of the circular cylinder segment located in the radial plane, which forms the radially outer boundary of the permanent magnet 221 .

[0082] E designates the distance between the center MP and the center MR of the magnetically active core 22 of the rotor 2 .

[0083] MS designates the geometrical center of the stator 3 or of the central pole piece 32 of the stator 3 in a radial plane.

[0084] AS designates the outer radius of the stator 3 , ie the radius of the circular cylinder on which the pole shoes 311 are arranged.

[0085] BP designates an opening angle of the pole shoe 311 of the coil core 31 of the stator 3. The opening angle BP is an angle enclosed by two connecting lines connecting the center MS and both ends of the pole shoe 311 when viewed in the circumferential direction (i.e., connecting lines from both ends of the short legs of the T of the substantially T-shaped coil core 31 to the center MS).

[0086] BS designates the width of the coil core 31 in a radial plane.

[0087] HS designates the height of the coil core 21 in the axial direction A. If the height HS of the coil core 21 changes in the radial direction, HS designates the height of the coil core 31 at the radially outer end, i.e. at the pole piece 311. In the embodiment described here, the height HS is constant when viewed in the radial direction, and the center pole piece 32 also has a height HS in the axial direction A.

[0088] The following relative sizes are preferred: The ratio of BM to BR is preferably 0.5-0.9, particularly preferably 0.7.

[0089] The ratio of E to IR is preferably 0.25-0.65, particularly preferably 0.45.

[0090] The ratio of BS to AS is preferably 0.25-0.45, particularly preferably 0.35.

[0091] The ratio of HR to HS is preferably 1.5-2.5, particularly preferably 2.0.

[0092] The opening angle BP of the pole piece 311 is preferably 30°-45°, and particularly preferably 40°.

[0093] Another preferred measure is to provide a heat conducting element 8 in the stator housing 4 in order to spread or dissipate the heat generated, for example, by the power electronics of the test device 5 and / or by the stator 3 through the flow of current in the best possible way. The heat conducting element 8 consists of a material with good thermal conductivity, for example a metallic material. Preferably, the heat conducting element 8 is made of aluminum. In the following, different variants of the heat conducting element 8 are explained, wherein the heat conducting element 8 is preferably always made of aluminum.

[0094] Fig.12 A first variant for the design of the stator housing 4 is shown in a perspective sectional view with a heat conducting element 8. The heat conducting element 8 is designed and arranged such that it at least surrounds the testing device 5 so that the heat generated, in particular by the power electronics, is dissipated as far as possible.

[0095] exist Fig.12 In the variant shown, the heat-conducting element 8 is designed as a sleeve, which extends completely along the inner cylindrical wall of the second housing part 42 of the stator housing 4, in which the inspection device 5 is arranged. The heat-conducting element 8 is directly in contact with the inner side of the cylindrical wall of the second housing part 42. The heat-conducting element 8 designed as a sleeve thus has an outer diameter W2 corresponding to the inner diameter of the cylindrical second housing part 42 of the stator housing 4. The heat-conducting element 8 has a rotationally symmetrical L-shaped profile, so that the annular area 421 is also lined with the heat-conducting element 8 on its inner side, which defines the end face of the second housing part 42 protruding beyond the first housing part 41 in the radial direction and is therefore arranged below the rotor 2 according to the representation. Due to this measure, the heat generated by the inspection device 5 is especially distributed over a large area on the wall of the second housing part 42. Due to this measure, sufficient heat can be dissipated from the stator housing 4 despite the poorly thermally conductive plastic that is preferably used to make the stator housing 4. The heat is distributed over as large an area as possible on the inner wall of the second housing part 42 and is introduced into the plastic. Furthermore, it is preferred that the heat is fed into a region of the stator housing 4 which is subject to particularly strong fluid dynamic flows in the operating state, through which the heat is reliably dissipated.

[0096] exist Fig.13 In the second variant of the design of the stator housing 4 shown, the stator 3 is also thermally coupled to a heat-conducting element 8. The heat-conducting element 8 comprises a cup 81 having a rotationally symmetrical U-shaped profile. The cup 81 extends completely along the inner cylindrical wall of the second housing part 42 of the stator housing 4 and rests thereon. Therefore, the cup 81 has an outer diameter W2, which corresponds to the inner diameter of the cylindrical second housing part 42 of the stator housing 4.

[0097] and Fig.12Unlike the first variant shown, in the second variant, the heat-conducting element 8 (more precisely the cup 81) is completely closed at the boundary between the first housing part 41 and the second housing part 42. In addition, the heat-conducting element 8 comprises a centrally arranged rod 82 extending in the axial direction A. According to the representation, the rod 82 extends from the cup 81 in the axial direction A, completely passes through the central pole piece 32 of the stator 3, and ends above the central pole piece 32 ( Fig.13 ). Due to this measure, the stator 3 is also thermally connected to the heat-conducting element 8, so that the heat generated in the stator 3 is also distributed over a large area via the stator housing 4 and in particular via the wall of the second housing part 42. The heat generated in the stator 3 is mainly based on the current flow in the coil 33, which is made of copper wire, for example (so-called copper losses), on the eddy currents induced in the coil core 31 and the center pole piece 32, which are made of iron, for example, and on the remagnetization losses (so-called hysteresis losses). Eddy current losses and hysteresis losses are together also called iron losses.

[0098] exist Fig.14 A third variant for the design of a stator housing 4 with a heat-conducting element 8 is shown in FIG. Fig.15 It also shows the Fig.14 A perspective view of the heat conducting element 8 is shown.

[0099] In the third variant, as in the second variant, the heat-conducting element 8 also comprises a cup 81 surrounding the inspection device 5 and a rod 82 extending from the cup 81 in the axial direction A through the interior of the central pole piece 32. In addition, a disc-shaped plate 83 is provided in the third variant, which is arranged at the end of the rod 82 facing away from the cup 81 and parallel to the radial plane. The plate 83 has a diameter W1, which corresponds to the inner diameter of the cylindrical first housing part 41. According to the expression ( Fig.14 ), the plate 83 is arranged above the coils 33 of the stator 3 and bears against the inner end face 411 which delimits the first housing part 41 on the suction side 61 in the axial direction A. In this third variant, the heat is therefore additionally spread over a large area on the inner end face 411 of the stator housing 4 and is introduced into the plastic of the stator housing 4. The inner end face 411 thus also serves as an additional surface into which the plate 83, which is of course also preferably made of aluminum, introduces heat, which is then carried away by the incoming fluid.

[0100] exist Fig.15 In the embodiment, another advantageous measure is also shown, which can of course also be implemented in the first variant ( Fig.12 ) or the second variant ( Fig.13). The heat conducting element 8 is in fact preferably provided with a plurality of slits 84, each of which extends in the direction of the heat flow of the heat, i.e. in the radial direction outwards. If the heat conducting element is preferably made of a metallic material (i.e. in particular aluminum), the eddy currents in the heat conducting element 8 and the associated eddy current losses can be at least very strongly reduced, while the heat dissipation of the heat through the slits 84 is only negligibly affected. Fig.15 In the third variant of the heat-conducting element 8 shown, slits 84 extending in the radial direction are provided both in the plate 83 and in the cup 82 .

[0101] Below, based on Figure 16-Figure 21 Some variants of the design of the impeller 21 of the rotor 2 are described. All these representations are schematic and simplified to a sufficient degree for understanding. The impeller 21 comprises an annular hub 23 arranged around the stator 3 enclosed in the stator housing 4, and a number of blades 24 firmly connected to the hub 23. The blades 24, preferably made of plastic, can be made integrally with the hub 23, or the blades 24 can be manufactured separately from the hub 23 and then firmly connected to the hub 23, for example by adhesive or by a welding process.

[0102] The hub 23 is preferably manufactured in two pieces so that first a first part of the hub 23 is manufactured, in which a recess is provided for the magnetically active core 22 of the rotor 2. The magnetically active core 22 is then inserted into this recess. Subsequently, the second part of the hub 23 designed as a cover is preferably firmly connected to the first part of the hub by a welding process, so that the magnetically active core 22 is encapsulated in the hub 23 in a gas-tight manner.

[0103] As especially in Figure 3 As can be clearly seen in the diagram, the blades 24 of the impeller 21 are preferably each designed so that they are inclined with respect to the axial direction A. Figures 16 to 21 This inclination with respect to the axial direction A is not shown in these Figures 16 to 21 In the embodiment, the space swept by the blade 24 during the rotation about the axial direction A is represented in each case as a section along the axis of rotation (i.e. a section along the axial direction A), so that the blade 24 is directed to the axial direction A, i.e. to Figures 16 to 21 The inclination of the respective section planes in FIG. 2 is not represented. The representations correspond in each case to the vertical projection of the blade 24 onto the respective drawing plane.

[0104] also, Figure 16-Figure 21 In each case, the impeller 21 is shown in an operating state when the magnetically suspended rotor 2 is centered in a radial plane with respect to the stator 3, i.e. in the magnetic center plane of the stator 3. Figure 16-Figure 21Only the stator housing 4 is shown in FIG. The arrows without reference numerals in each case indicate the direction in which the fluid flow, ie in particular the air flow, flows. According to the representation, the suction side 61 is at the top and the pressure side 62 is at the bottom in each case. Figures 16 to 21 The geometric center plane RM is also referred to as the geometric center plane RM. The geometric center plane RM is a plane perpendicular to the axial direction A, which extends through the geometric center of the magnetically active core 22 of the rotor 2. If the rotor 2 is centered and not tilted with respect to the stator 3, the geometric center plane RM and the radial plane, i.e. the magnetic center plane of the stator 3, coincide.

[0105] Preferably, all blades 24 of the impeller 21 are designed identically.

[0106] Fig.16 A schematic cross-sectional view of a first variant of a rotor 2 with an impeller 21 is shown, which comprises a hub 23 and blades 24. Each blade 24 has a leading edge 241 facing the suction side 61 and a trailing edge 242 facing the pressure side 62. In this first variant, each blade 24 is designed and arranged symmetrically with respect to a center plane RM. The height of each blade 24 in the axial direction A decreases outwardly from the hub 23 in the radial direction. The leading edge 241 and the trailing edge 242 symmetrical with respect to the center plane RM can in each case be as Fig.16 Of course, the leading edge 241 and the trailing edge 242 may be designed as straight lines, i.e. without bending.

[0107] As already mentioned above, due to the complete encapsulation of the magnetic core 22 of the rotor 2 on the one hand and the stator 3 on the other hand, the magnetic air gap in the magnetic circuit between the rotor 2 and the stator 3 is relatively large compared to known rotary drives designed as bearingless motors. Therefore, it is particularly preferred that the rotor 2 with the impeller 21 is designed for hydrodynamic stabilization of the rotor 2 during operation. In particular, the rotor 2 should preferably be designed in such a way that the fluid flowing through the fan 1 (i.e., for example, flowing air) stabilizes the rotor 2 with respect to its position in the axial direction A and prevents tilting with respect to a radial plane. In doing so, it is achieved that the rotor 2 is stabilized by those degrees of freedom of the flowing fluid with respect to the passive magnetic suspension or stabilization of the rotor 2. The hydrodynamic stabilization thus supports the stabilization of the passive magnetic bearing or the rotor 2. Due to the hydrodynamic stabilization by the flowing fluid, the passive magnetic axial bearing of the rotor 2 is also damped in particular, so that vibrations of the rotor 2 in the axial direction A are suppressed or at least strongly damped.

[0108] In the following, based on different variants in a non-exhaustive list, it is explained how the rotor 2 can be designed for hydrodynamic stabilization measures. It should be understood that some of these measures can also be combined.

[0109] Fig.17A variant is shown in which the blades 24 have an asymmetrical design on the one hand and are displaced in the direction of the suction side 61 on the other hand. Each blade 24 is designed and arranged so that its center of gravity is clearly outside the center plane RM and between the suction side 61 and the center plane RM. The leading edge 241 extends from the hub 23 in a straight line (i.e. without curvature) in the radial direction to the outside, i.e. it extends perpendicularly to the axial direction A, wherein the leading edge 241 is aligned with the suction side end of the hub 23. The trailing edge 242 is aligned with the suction side end of the hub 23. Fig.16 The variant shown in FIG. 6 is bent in a similar manner in the radial direction, but is also displaced in the direction of the suction side 61 .

[0110] Fig.18 The variation shown is based on Fig.17 The variant shown is designed in a similar manner, however, in accordance with Fig.18 In a variant of , the blades 24 (more precisely their respective centers of gravity) are even further displaced in the direction of the suction side 61. Furthermore, each leading edge 241 is also curved in such a way that the radially inner end of the leading edge 241 is aligned with the suction side end of the hub 23 and the radially outer end of the leading edge 241 protrudes beyond the suction side end of the hub 23 in the direction of the suction side 61.

[0111] exist Fig.19 In the variant shown, the magnetically active core 22 of the rotor 2 is displaced in the direction of the pressure-side end of the hub 23. The magnetically active core 22 is therefore no longer centered in the hub 23 with respect to the axial direction A, but is arranged closer to the pressure-side end of the hub 23 than to the suction-side end of the hub 23. Each leading edge 241 extends from the hub 23 in a straight line (i.e. without curvature) in the radial direction to the outside, i.e. it extends perpendicularly to the axial direction A, wherein each leading edge 241 is aligned with the suction-side end of the hub 23. The trailing edge 242 is in each case aligned with the suction-side end of the hub 23. Fig.17 The variant shown in FIG. 1 is bent in a similar manner in the radial direction, but according to the representation ( Fig.19 ), the trailing edge 242 opens to the outer surface of the hub 23 above the pressure side end of the hub 23, that is, the trailing edge 242 does not extend to the pressure side end of the hub 23 with respect to the axial direction A. Of course, it is also possible to use Fig.19 The variant shown designs the trailing edge 242 as a straight line, ie not curved.

[0112] Fig. 20 The variant of the impeller 21 shown is Fig.19 The variant shown is designed in a similar manner. However, in Fig. 20In the variant shown, the hub 23 of the impeller 21 has an inlet region 231 at its suction side end, wherein the hub 23 is designed to taper in the direction of the suction side end. This means that in this inlet region 231, the hub 23 is designed to be conical or truncated conical, wherein the apex of the cone is located at the suction side. According to the representation, the inlet region 231 is arranged above the magnetically active core 22 with respect to the axial direction A.

[0113] Fig.21 The variation shown is based on Fig.16 The variant shown is designed in a similar manner. However, in Fig.21 In the variant shown, several concentrically arranged stabilization rings 243 are provided, each of which is arranged at the trailing edge 243 of all blades 24 and projects beyond the blades 24 on the pressure side with respect to the axial direction A. Each stabilization ring 243 is arranged coaxially with the rotor 2 and in each case extends over the trailing edge 242 of all blades 24. Fig.21 In the variation shown, three concentric stabilizing rings 243 are provided. Of course, only one stabilizing ring 243 may also be provided.

[0114] As mentioned above, Figures 16 to 21 The variants or measures described in can also be combined. Figures 17 to 20 In the variants, one or more stabilizing rings 243 can also be provided in each case. In all variants (see Figures 16 to 21 ) is if each trailing edge leads to the hub 23 at an angle different from 90° (and in particular less than 90°) to the axial direction A. This measure is particularly useful for trailing edges 242 curved in the radial direction (see Figures 16 to 21 ) and for a straight (ie not curved) such trailing edge (not shown) are possible.

[0115] In addition, or as an alternative to hydrodynamic stabilization, active damping can also be provided by the coils 33 or the electromagnetic fields generated by them. For this purpose, the rotating field generated by the coils 33 is oriented in such a way that it no longer causes any torque on the rotor 2, but weakens or strengthens the magnetic field generated by the permanent magnets 221. This means that the rotating field generated by the coils is adjusted in such a way that the current pointer points in the same or opposite direction as the flux pointer, so that there is no longer a 90° phase shift between the two pointers.

[0116] This method can also be used advantageously to decelerate the rotor particularly quickly. The kinetic energy present in the rotor 2 is destroyed by attempting to change the magnetization of the permanent magnets 221 in the rotor 2. This destruction of the kinetic energy of the rotor 2 results in a rapid deceleration of the rotation of the rotor 2.

[0117] Another preferred measure is to provide a sensor 9, with which the pressure or flow of the fluid flow can be determined, wherein the sensor 9 is signal-connected to the inspection device 5. Preferably, the inspection device 5 is then designed to regulate or control the pressure or flow. The sensor 9 can be arranged on the suction side or the pressure side of the rotor 2.

[0118] based on Figure 22 to Figure 24 , various variants are now described in which a fan 1 is designed and arranged for regulating or controlling a fluid flow, such as an air flow. In the present application, it is mentioned by way of example that the fan 1 is integrated into a duct 100 and generates an adjustable or controllable fluid flow there. The duct 100 is arranged in a chamber 200. This may be a chamber 200 that requires chemical resistance, as may be the case in the semiconductor industry.

[0119] Fig. 22 A variant is shown in which a fan 1 is integrated into a duct 100 passing through a chamber 200. The fan is arranged between a first section 101 and a second section 102 of the duct 100. For this purpose, the suction side flange 63 of the fan 1 is firmly connected to the flange of the first section 101, while the pressure side flange 64 is firmly connected to the flange of the second section 102. The fluid flow generated by the fan 1 is indicated by arrows without reference numerals. The sensor 9 is designed as a pressure sensor or a flow sensor and is arranged on the suction side, i.e. upstream of the fan 1. The sensor 9 can, for example, be attached to the duct 100 or the fan 1. The sensor 9 is connected to an external logic unit 300, for example, via a signal line 91 or wirelessly. For example, the logic unit 300 is designed as a programmable logic controller (PLC). On the logic unit 300, the analog signal of the sensor 9 is fed to the inspection device 5, for example, via a cable 72. The inspection device 5 includes the necessary adjustment means to adjust or control the fluid flow in the duct 100 by the signal of the sensor 9. By means of these regulating devices, the fluid flow can be adjusted to a predetermined desired value.

[0120] The fan is also connected to a communication interface 400 via which the user can input or read out data. Of course, embodiments are also possible in which the sensor 9 is arranged on the pressure side, ie downstream of the fan, or in which the sensor 9 is arranged on both the suction side and the pressure side of the fan 1 .

[0121] for Fig.23 and Fig.24 The variants shown in the Fig. 22 In addition, Fig. 22 The instructions given in the same or similar manner also apply to Fig.23 and Fig.24 The variation shown in .

[0122] exist Fig.23In the variant shown, the sensor 9 is connected directly to the inspection device 5 in the stator housing 4 of the fan 1 , for example via a sensor cable 92. The sensor 9 may be attached directly to the fan 1 or to the duct 100. Fig.23 An embodiment is shown in which the sensor 9 is arranged on the pressure side of the fan 1. Of course, embodiments are also possible here in which the sensor 9 is arranged on the suction side of the fan 1 or in which the sensor 9 is provided on both the suction side and the pressure side of the fan 1. Even in the case of a direct signal connection between the sensor 9 and the checking device 5, the necessary evaluation devices for the sensor signals and the control or regulation devices for adjusting the fluid flow or regulating the fluid flow are directly integrated in the checking device 5.

[0123] exist Fig.24 In the variant shown, the sensor 9 is integrated directly in the fan 1. The sensor 9 can be attached to the housing 6 of the fan 1, for example, or Fig.24 The sensor 9 can be attached to the pressure side of the stator housing 4 (see Fig.24 ) or also attached to the suction side. Of course, here, embodiments in which the sensor 9 is arranged on both the suction side and the pressure side are also possible. The sensor 9 is signal-connected to the inspection device 5 arranged in the stator housing 4. In this variant, the necessary evaluation devices for the sensor signals and the control or regulation devices for adjusting the fluid flow or regulating the fluid flow are also directly integrated in the inspection device 5. In particular, in this variant, the fan 1 is provided with a fully integrated sensor 9, in particular a flow or pressure sensor 9, so that the fan 1 can adjust the air flow generated by it to a predeterminable desired value for the pressure or flow without additional components.

Claims

1. A fan having a rotor (2) for generating a fluid flow and having a stator (3), the stator (3) together with the rotor (2) forming an electromagnetic rotary drive for rotating the rotor (2) about an axial direction (A), the rotary drive being designed as an outer rotor, the rotor (2) comprising a magnetically active core (22) designed in an annular manner and an impeller (21), the impeller comprising a hub (23) on which a plurality of blades (24) for generating a fluid flow are arranged, the stator (3) being designed as a bearing and a driving stator, the rotor (2) being magnetically driven by the stator without contact and being magnetically suspended relative to the stator (3) without contact, and the rotor (2) being actively magnetically suspended in a radial plane perpendicular to the axial direction (A), characterized in that The hub (23) of the impeller (21) completely encloses the magnetically active core (22) of the rotor (2), and the stator (3) is enclosed in a stator housing (4) made of a low magnetic permeability material. 2 . The fan according to claim 1 , wherein the impeller ( 21 ) is made of a first plastic and the stator housing ( 4 ) is made of a second plastic.

3. A fan according to any one of the preceding claims, comprising a substantially tubular housing (6) having a suction side (61) and a pressure side (62), wherein: The rotor (2) and the stator housing (4) are arranged in the housing (6), wherein the stator housing (4) is fixed in the housing (6) by means of a plurality of struts (7).

4. A fan according to any one of the preceding claims, wherein the stator housing (4) has a first housing part (41) and a second housing part (42), the first housing part (41) being arranged inside the rotor (2) and surrounded by the magnetic core (22) of the rotor (2), and the second housing part (42) having an outer diameter (D2) at least as large as an outer diameter (DM) of the magnetically active core (22) of the rotor (2).

5. The fan according to claim 4, comprising a check device (5) for controlling or regulating the fan (1), the check device (5) being arranged in the second housing part (42) of the stator housing (4).

6. The fan according to claim 5 is provided with a sensor (9), by means of which the pressure or flow rate of the fluid flow can be determined, the sensor (9) signal is connected to the inspection device (5), and the inspection device (5) is designed to adjust or control the pressure or flow rate.

7. The fan according to any one of the preceding claims, the stator (3) comprising a plurality of coil cores (31), each coil core extending in a radial direction and each coil core (31) carrying a concentrated winding (33) for generating a rotating magnetic field.

8. According to the fan according to any one of the preceding claims, the magnetically active core (22) of the rotor (2) includes an annular return flow returner (222) and a plurality of permanent magnets (221), the return flow returner (222) being continuously designed and made of soft magnetic material, and each permanent magnet (221) being designed to have a sickle-shaped cross-section and being assembled into the radial inner side of the return flow returner (222).

9. The fan according to any one of claims 4 to 8, wherein a heat-conducting element (8) for heat dissipation is arranged in the stator housing (4), and the heat-conducting element (8) is designed to at least surround the inspection device (5).

10. The fan according to any of the preceding claims, the rotor (2) being designed for hydrodynamic stabilization against tilting of the rotor (2).

11. A fan according to any one of the preceding claims, wherein the hub (23) of the impeller (21) has a suction side end and a pressure side end, and the magnetic action core (22) of the rotor is arranged to be closer to the pressure side end than the suction side end of the hub (23) with respect to the axial direction.

12. The fan according to claim 11, the hub (23) of the impeller (21) comprising an inlet area (231) at a suction side end thereof, wherein the hub (23) is designed to taper in the direction of the suction side end.

13. A fan according to any one of the preceding claims, wherein Each blade (24) has a leading edge (241), each leading edge (241) extending perpendicularly to the axial direction (A).

14. A fan according to any one of the preceding claims, wherein Each blade (24) has a trailing edge (242), each trailing edge (242) leading to the hub at an angle different from 90° to the axial direction (8).

15. A fan according to any one of the preceding claims, wherein Each blade (24) has a trailing edge (242), and wherein at least one stabilization ring (243) is arranged at the trailing edge (242), the stabilization ring (243) being arranged coaxially with the rotor (2).

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