Brushless motor and method for assembling the same

Abstract

The invention relates to a brushless motor 1, in particular as a drive for a pump for transporting a fluid, having at least one housing 2, at least one stator 3 and at least one rotor 4, in which the fluid can flow through the housing 2 at least in a gap 5 between the stator 3 and the rotor 4 in the housing 2, the stator 3 being formed in a fluid-tight stator space 6 and the rotor 4 being formed in a fluid-tight manner. A compact motor 1 that ensures high requirements for sealing against the surrounding medium is realized in that the stator space 6 is defined in the direction of the rotor 4 by at least two inner cylindrical parts 8 and in that at least one rotor bearing element 9 for mounting the rotor 4 is supported on the inner circumference 10 of the inner cylindrical part 8.

Description

[Technical field]

[0001] The invention relates to a brushless motor, in particular a brushless motor as a drive for at least one impeller for transporting a fluid. The motor comprises at least one housing, at least one stator and at least one rotor. The fluid can flow through the housing at least in the gap between the stator and the rotor. The housing has corresponding openings at the side ends for this purpose. The rotor is fluid-tight and the stator is arranged in the fluid-tight stator space. [Background technology]

[0002] Brushless motors, in particular brushless DC motors, are known in the state of the art in various configurations. Such motors, particularly small ones, are used in the food industry or in the medical technology sector, for example as drives for pumps for transporting fluids, such as fuels.

[0003] For example, German Utility Model No. 29921352 discloses an intravascular blood pump with an electric motor. At a first end of the electric motor, an impeller is arranged on the motor shaft to transport the fluid. The stator windings are embedded in a synthetic resin matrix. A vane-free rotor is attached to the rotor shaft and is prevented from coming into contact with the fluid by a seal.

[0004] DE 10 2010005963 A1 discloses a brushless electric motor as a rotary drive for a fuel pump. The rotor has a metallic casing that hermetically seals the rotor.

[0005] When using such motors in the medical technology sector in particular there are many challenges with regard to the compactness of the motor and its sealing against fluids.

[0006] There is an increasing demand for high performance and efficiency combined with a compact design, which motors known from the current state of the art are often unable to meet. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Utility Model No. 29921352 [Patent Document 2] DE 102010005963 A1 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention is specifically based on the object of providing a brushless motor that is compact while offering high performance, and that reliably meets the increasing demands for sealing against fluids. [Means for solving the problem]

[0009] The above-mentioned problem is solved by a motor according to the characterizing part of claim 1 in that the space for the stator is defined by at least one inner cylindrical part in the direction of the rotor and in that at least one rotor bearing element for mounting the rotor is supported on the inner circumference of the inner cylindrical part.

[0010] Preferably, the motor housing is configured such that a fluid, for example a perfusion fluid, can flow axially through it between the first and second lateral ends. The flow through the housing occurs substantially in a gap, particularly an annular gap, formed between the stator and the rotor. The gap between the stator and the rotor is radially defined by the inner cylinder over the entire length of the stator. Preferably, the inner cylinder is configured to define a full flow path radially in the housing, more particularly between the motor flange arranged at the first end and the perfusion connection arranged at the second end. The inner cylinder is part of the housing and defines the gap in the direction of the stator space surrounding the rotor. The inner cylinder surrounds the rotor space in which the rotor is rotatably arranged, more particularly mounted.

[0011] The stator surrounds the rotor, and the rotor can rotate about the motor axis A within the rotor space.

[0012] Preferably, the motor has control electronics and / or power electronics arranged at least partially within the housing. The control electronics and / or power electronics have at least one circuit board arranged, in particular enclosed, within the housing. Preferably, the circuit board can be communicated from within the housing to the outside by at least one, preferably at least two or at least three, connecting wires.

[0013] In particular, in order to ensure a compact construction of the motor, at least one rotor bearing element is provided for mounting the rotor, in particular in the inner tubular part. The rotor bearing element is arranged to be supported on the inner circumference of the inner tubular part. Preferably, at least two rotor bearing elements are provided for mounting the rotor, both rotor bearing elements being supported on the circumference of the inner tubular part. In particular, both rotor bearing elements are arranged inside the inner tubular part. The at least one rotor bearing element is configured, for example, as a ball bearing, a magnetic bearing, a ceramic bearing or a plain bearing. Preferably, the at least one rotor bearing element is lubricated by a fluid, in particular configured as a ceramic bearing. Preferably, both rotor bearing elements are configured identically.

[0014] In particular, at least one rotor bearing element is mounted in the inner cylinder by a sliding fit, preferably both rotor bearing elements are mounted in the inner cylinder by a sliding fit, or at least one rotor bearing, preferably both rotor bearings, are connected to the inner cylinder, in particular by adhesive.

[0015] Very low friction in rotor bearings can be achieved by applying a very low preload force in one direction to the rotor, in particular by means of at least one wave spring washer, for example a preload force of less than 5 N, in particular less than 3 N.

[0016] Preferably, at least a part of the bearing cage, preferably the entire bearing cage, is made of a biocompatible plastic material, in particular polyetheretherketone (PEEK). Arranging the rotor bearing elements in the inner cylinder has the advantage that no additional installation space is required for the rotor bearing elements, which ensures a compact design.

[0017] Compared to the prior art, the invention has the advantage that the motor is compact and at the same time achieves high safety requirements, especially with regard to the fluid, in the inner cylinder. During operation, the fluid flows at least partially through the container, ensuring favorable heat dissipation and thus preventing, for example, high temperatures on the outside of the container. The motor is designed very efficiently to prevent overheating of the fluid.

[0018] According to a first embodiment of the motor, it has proven to be advantageous if the rotor bearing element or elements are configured and arranged in such a way that a fluid can flow around and / or through them. The rotor bearing element or elements are therefore arranged in such a way that a fluid can flow around and / or through them, which flows in the air gap between the stator and the rotor. It is particularly advantageous if the rotor bearing elements, for example in the form of ball bearings, are at least partially made of plastic. Preferably, the cage is made of plastic, in particular polyetheretherketone (PEEK). For example, the balls are made of ceramic and the bearing rings - the inner ring and / or the outer ring - are made of corrosion-resistant steel.

[0019] A further preferred configuration of the motor is that the tubular part is in one piece. Preferably, the tubular part extends as one piece from the motor flange at a first side end to a second side end opposite the motor. To ensure that the motor is biocompatible, particularly in medical applications, the tubular part shall be made of a biocompatible plastic. In particular, polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE) have been found to be suitable biocompatible plastics. The tubular part is also made of several parts, in particular two parts, and the parts of the tubular part are joined in a materially bonded, in particular fluid-tight manner, preferably glued or welded.

[0020] Preferably, the inner cylinder is configured to radially define a rotor space in the housing. Preferably, a motor flange is formed at the first side end and defines the rotor space in the axial direction, allowing fluid to exit the housing, in particular from the rotor space. Preferably, at the second side end, the rotor space is defined in the axial direction by a perfusion connection through which fluid can pass to enter the gap between the rotor and the stator. The second side end of the motor or housing is sealed by a potting compound, in particular a low pressure hardening potting compound.

[0021] The configuration of the inner cylinder influences the efficiency of the motor and the size of the motor. Thus, according to a further embodiment, the inner cylinder is specifically configured such that at least in the area between the rotor and the stator, in particular along the longitudinal direction of the stator, the wall thickness is between 0.075 mm and 1 mm. A wall thickness of between 0.1 mm and 0.5 mm is particularly preferred. Preferably, the inner cylinder has a constant wall thickness at least along the longitudinal direction of the stator windings. This low wall thickness creates assembly challenges, for which a method for assembling the motor described below is also claimed according to the invention.

[0022] The inner cylinder defines, inter alia, a rotor space. According to a further embodiment of the motor, at least one outer cylinder is provided outside the housing. The outer cylinder defines the housing, in particular the stator space, in the radial direction at its outer side. The housing is configured such that the inner cylinder defines the stator space in the direction of the rotor space inside. The outer cylinder also defines the housing in the radial direction over its entire circumference. A wall thickness of 0.05 mm to 1 mm, in particular 0.1 mm to 0.5 mm, has proven to be particularly advantageous for the outer cylinder. Preferably, the outer cylinder is made of corrosion-resistant steel.

[0023] According to a further embodiment, it has also proven to be advantageous if a motor flange is arranged at least at the first side end of the motor. Preferably, the motor flange supports an inner cylinder and an outer cylinder, whereby the stator space between the inner cylinder and the outer cylinder is formed as an annular space. Preferably, the motor flange is bonded or welded to the outer cylinder. It is particularly preferred to laser weld the outer cylinder and the motor flange. For example, the motor flange is made of the same material as the outer cylinder.

[0024] Preferably, the motor flange has a central recess that provides an opening for the rotor space to ensure fluid flow. The motor flange also has at least one central threaded portion. The motor can be attached to the threaded portion or the threaded portion serves as a connection to attach other components to the motor. Preferably, the motor flange is pierced by at least one motor shaft portion of the rotor. The motor shaft portion is configured to drive, for example, a shaft that is connectable to the motor shaft portion. For example, the motor shaft portion has a structure that is configured to interact with the connectable shaft, in particular by tightly meshing to transmit torque. At least in a running state of the motor, the motor shaft portion is rotatable.

[0025] According to a further embodiment of the motor, the inner cylinder has at least one flange portion at the first side end, in particular the flange portion is adapted to cover on its inside a central recess of the motor flange. Preferably the flange portion is pressed into the recess in the motor flange. Preferably the wall thickness in the area of ​​the flange portion is increased compared to the wall thickness in the area between the rotor and the stator, in particular at least doubled. Furthermore, the flange portion of the inner cylinder is also provided with at least one portion of reduced inner diameter, whereby at least one abutment edge for the rotor bearing element and / or the mounting ring is provided. The mounting ring is made, for example, of polyetheretherketone (PEEK).

[0026] Preferably, an annular extension is formed between the flange portion and the portion of the inner cylinder that extends between the rotor and the stator with a constant wall thickness, preferably extending towards the outer cylinder of the motor, for example the annular extension is arranged in close contact with the motor flange, in particular at the end face, the annular extension is used in particular for electrical insulation from the motor flange and for axial positioning of the coil and the yoke.

[0027] To the first end of the motor, the container, in particular the space for the stator, is sealed, for example, with at least one potting compound. In particular, at least one connecting wire and / or perfusion connection for the motor passes through the potting compound. Preferably, the perfusion connection is made of the same material as the outer casing. Preferably, the potting compound fills both the annular space between the outer casing and the inner casing and the end area of ​​the inner casing. A potting compound with low hardening pressure has proven to be particularly advantageous. For example, the outer casing extends from the second side end to the end of the container, while the inner casing, which is in the potting compound, remains at a certain distance to the end of the container.

[0028] The advantage of using a potting compound is that it dissipates heat and provides support and stability to the inner barrel.

[0029] According to a further embodiment of the motor, at least one centering flange is arranged at the second side end, whereby the inner and outer cylinders are arranged at a distance from each other. Preferably, the centering flange also serves as an element for confining the potting mix. Furthermore, preferably, the stator space, in particular the cavities present in the stator space, are potted with at least a second potting mix, preferably a low-pressure hardening potting mix, in particular up to the centering flange. Preferably, the centering flange has at least one penetration for injecting the potting mix.

[0030] The motor, and in particular the stator space, is therefore advantageously multiply sealed against the surrounding medium at a first side end by the motor flange and the potting compound of the stator space, and at a second side end by the external potting compound and the second potting compound of the stator space.

[0031] The perfusion connection in the second end region of the housing has at least one connection contour, for example for a hose, on the outside of the housing. The connection contour is formed, for example, as a mandrel-shaped profile. The perfusion connection passes the fluid, for example the fluid to be perfused, through the potting compound, in particular from the inner circumference of the inner barrel into the housing of the motor, so that the fluid can perfuse around the rotor and axially through the gap between the rotor and the stator. Preferably, the outer diameter of the perfusion connection in the region of the inner barrel is a diameter that matches the inner diameter of the inner barrel. Preferably, the perfusion connection has a sliding fit to the inner circumference of the inner barrel.

[0032] Preferably, in the region of the second lateral end of the motor, at least one, for example ring-shaped, circuit board with the control electronics and / or power electronics for the motor is arranged in the housing, in particular in the stator space, and is preferably held by a circuit board carrier extending in a ring shape around the outer periphery of the inner cylinder.

[0033] Preferably, the rotor is completely mounted in the inner cylinder. According to a further embodiment of the motor, it has also proven advantageous if the rotor has at least one rotor cylinder, which has a first shaft extension at a first side end and a second shaft extension at a second side end. Preferably, the rotor is mounted on the shaft extension of the rotor cylinder.

[0034] At least one permanent magnet, in particular a plurality of permanent magnets, of the rotor are arranged in the rotor casing, the at least one permanent magnet being arranged in the rotor casing between the first shaft extension and the second shaft extension, preferably configured as a completely cylindrical magnet, in particular a neodymium iron boron magnet.

[0035] For example, the rotor barrel is made of the same material as the motor barrel, and for example, the first shaft extension and the second shaft extension are also made of this material, and for example, the first shaft extension and / or the second shaft extension are welded to the rotor barrel, in particular by laser welding.

[0036] A first shaft extension of the motor at a first side end protrudes at least partially into the rotor barrel and is preferably sealed on the inside with a bung, in particular made of polyetheretherketone (PEEK), to prevent the ingress of fluids. The first shaft extension also has a motor shaft section, in which the first bearing element is arranged, for example. In particular, the motor shaft section exits the housing through the motor flange, for example for driving a shaft which can be coupled to the motor shaft section. For example, a coupleable shaft is at least partially inserted into the motor shaft section in order to be coupled. In particular, the motor shaft section corresponds to a connection for transmitting torque. For example, the motor shaft section has an outer or inner shell, at least partially grooved, in particular an outer square and / or an inner square.

[0037] The second shaft extension at the second side end of the housing also penetrates at least partially into the rotor barrel and is preferably welded to the latter. At the end of the second shaft extension facing the second end section, the diameter is reduced to correspond to the inner diameter of the rotor bearing element arranged there. Preferably, the inner diameters of both rotor bearing elements are essentially identical. In addition, a spring washer, in particular a wave spring washer, is arranged on the second shaft extension and is preferably supported by the perfusion connection in order to axially support the rotor by means of a sliding fit. Preferably, the rotor is preloaded by the spring washer, in particular with a preload of less than or equal to 5 N, preferably less than or equal to 3 N. Preferably, the preload is applied in the direction of the first side end of the motor. Preferably, the rotor barrel is connected to the shaft extension in a fluid-tight manner.

[0038] According to a further embodiment of the motor, the first shaft extension is adapted to have at least one motor shaft portion at the first side end. The motor shaft portion is at least partially hollow, whereby a fluid can flow therethrough. The motor shaft portion has an axially extending recess. The motor shaft portion is for example formed in one piece with the first shaft extension. Alternatively, the motor shaft portion is adapted to be attached to the shaft extension. A first motor shaft portion, preferably without a recess, is arranged on the first shaft extension, and a second motor shaft portion, in particular an adapter, having a longitudinally extending recess, preferably an inner square, is also adapted to be attached to the first motor shaft portion.

[0039] In order to further increase the efficiency of the motor, according to a further embodiment, the stator has a yoke with a number of individual laminations arranged adjacent to each other. The yoke is arranged between the windings of the stator and the outer casing. The individual laminations are made, for example, of silicon iron or nickel sheet metal. Preferably, the individual laminations of the yoke have a thickness of 0.05 mm to 0.5 mm. It is also preferred that the thickness is 0.05 mm to 0.3 mm. It is particularly preferred that each of the individual laminations has a thickness of about 0.1 mm or 0.2 mm.

[0040] Moreover, it proves to be advantageous from the point of view of efficiency if the stator is provided with at least three or at least four pairs of coils. The coils are wound without iron, preferably according to the principle of cylindrical armature. Preferably, two pairs of coils, in particular pairs of coils arranged approximately opposite each other, are connected in series, so that, for example, in the case of six coils, there are only six winding taps. In particular, the coils are interconnected on a circuit board.

[0041] The dimensions of the gap between the inner cylinder and the rotor have a significant influence on the efficiency of the motor and on the losses of the fluid. It has therefore proved to be advantageous if, according to a further configuration of the motor, the gap between the rotor and the stator is provided to have a height of 0.12 mm to 1.5 mm over at least 50% of the rotor's length. For example, the gap between the rotor and the stator has the above-mentioned height over at least the entire length of the rotor cylinder. It is particularly preferred that the gap height is 0.25 mm to 1 mm, and even more preferred that the gap height is about 0.5 mm.

[0042] In addition, the efficiency of the motor according to a further embodiment can be influenced such that the ratio of the outer diameter of the inner cylinder to the outer diameter of the housing is between 0.3 and 0.7. A ratio of 0.5 is particularly preferred. Also, for example, the ratio of the outer diameter of the stator winding to the outer diameter of the yoke is between 0.6 and 0.9, in particular about 0.8.

[0043] The invention also relates to a method of assembling a motor, in particular according to one of the above embodiments, comprising at least - providing a motor flange having an outer cylinder portion arranged on the motor flange and an inner cylinder portion arranged on the motor flange for defining a housing of the motor, in particular a flange portion of the inner cylinder portion entering the motor flange; - at least partially filling the stator space between the inner and outer cylinders with a first potting mix; - placing the stator windings and the yoke in the stator space, in particular on the outer periphery of the inner cylinder, in particular in a first potting mix that has not yet solidified; - inserting a rotor together with rotor bearing elements into the rotor space formed by the inner cylinder, so that the motor shaft part of the rotor projects from the housing in the area of ​​the motor flange, - arranging a perfusion flange, in particular at least partially, in the inner barrel and at least one centering flange, in particular between the inner barrel and the outer barrel; - potting the container at a second side end with a second potting compound. Includes.

[0044] The above described sequence of attachment ensures that even very thin-walled inner cylinders can be easily attached.

[0045] In particular, any cavity remaining in the stator space after inserting the stator windings and yoke, in particular up to the centering flange, shall be filled with potting compound. Preferably, at least one spring washer, in particular a wave spring washer, is placed on the second shaft extension, and then the perfusion flange is placed. In particular, the rotor is preloaded through the perfusion flange towards the first side end, then the potting compound is injected, and the preload is released after the potting compound has hardened, so that the rotor remains preloaded between the perfusion flange and the first side end.

[0046] Further preferred embodiments of the invention are set out in the following figure description and the dependent subclaims. [Brief description of the drawings]

[0047] [Figure 1] 1 is a side cross-sectional view of one embodiment of a brushless motor according to the present invention; [Diagram 2] FIG. 2 is a schematic diagram of an example of the process according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] In the various figures of the drawing, identical parts are always provided with the same reference numbers.

[0049] With regard to the following description, the present invention is not limited to the exemplary embodiments and therefore not limited to all or some of the feature combinations described, but rather each individual partial feature of this / each exemplary embodiment is asserted to be essential to the subject matter of the present invention both independently of all other partial features described in connection therewith and also in combination with any feature of another exemplary embodiment.

[0050] FIG. 1 shows an exemplary embodiment of a brushless motor 1 in a side cross-sectional view. The motor 1 is configured in particular as a drive for a shaft that can be coupled with at least one impeller, for example for transporting a fluid. The motor 1 has at least one housing 2, a stator 3 and a rotor 4. The housing 2 is configured in such a way that the fluid can flow through the housing 2 in a gap 5 between the stator 3 and the rotor 4, in particular in an annular gap 5. For this purpose, the stator 3 is formed in a fluid-tight stator space 6. The rotor 4 is also fluid-tight and is arranged in a fluid-filled rotor space 7 during operation. The gap 5 has an essentially constant height over the extension of the stator 3.

[0051] The stator space 6 is defined in the direction of the rotor 4, in particular in the radial direction, by the inner cylinder 8. As a result, the inner cylinder 8 also defines the outer circumference of the rotor space 7. The rotor 4 is mounted with a rotor bearing element 9 and is arranged in the inner cylinder 8, i.e. in the rotor space 7. The rotor 4 can rotate around the motor axis A passing through the center of the housing 2. The rotor bearing element 9 is configured as a ball bearing with a cage made of polyetheretherketone (PEEK). The bearing outer ring of the rotor bearing element 9 is supported on the inside 10 of the inner cylinder 8. A sliding fit is formed between the rotor bearing element 9 and the inner cylinder 8. The fluid flowing in the air gap 5 between the rotor 4 and the stator 3 can flow through the rotor bearing element 9.

[0052] The inner cylinder 8 is made in one piece from polyetheretherketone (PEEK) and defines the rotor space 7 in the radial direction. The inner cylinder 8 defines the entire space in the housing 2 through which fluid can flow axially out of the housing 2. In the area in which the stator 3 extends, the inner cylinder 8 has a constant wall thickness, which is preferably about 0.5 mm. The stator space 6 is defined at the outer circumference of the housing 2 by an outer cylinder 11. Preferably, the outer cylinder 11 is made from corrosion-resistant steel and has a wall thickness of about 0.5 mm.

[0053] The inner cylinder 8 and the outer cylinder 11 are supported by a motor flange 13 at a first lateral end 12 of the motor 1. The outer cylinder 11 is partially pressed into the surface of the motor flange 13 and welded to the motor flange 13 by laser welding. The inner cylinder 8 has a flange portion 14 and extends into the motor flange 13 at the first lateral end 12 by the flange portion 14, preferably pressed into the motor flange 13. The flange portion 14 extends into a central recess 16 of the motor flange 13. The inner cylinder 8 extends to the end of the motor flange 13 and is flush with the motor flange 13.

[0054] In the axial direction along the motor axis A, the inner cylinder 8 is sealed at its end face to the motor flange 13 by an annular extension 15. On the other side of the annular extension 15, the stator 3 is formed in the stator space 6. The wall thickness of the inner cylinder 8 in the area of ​​the flange portion 14 is at least twice as thick as in the area of ​​the air gap 5 between the stator 3 and the rotor 4. In addition, the flange portion 14 has an area 17 with a reduced diameter in order to ensure a mounting edge 18 for the rotor bearing element 9 in the flange portion 14. The inside diameter of the area 17 corresponds to the inside diameter of the inner cylinder 8 in the area between the stator 3 and the rotor 4.

[0055] In this exemplary embodiment, the first rotor bearing element 9 abuts against the mounting edge 18, which supports the first rotor bearing element 9 in the axial direction. At a second side end 20 of the motor 1 or housing 2, a centering flange 21 is arranged between the outer periphery of the inner cylinder 8 and the inner periphery of the outer cylinder 11. The centering flange 21 maintains the distance between the inner cylinder 8 and the outer cylinder 11. The centering flange 21 also defines the stator space 6 in the axial direction. The stator space 6 is completely filled, for example with a first potting compound 22.

[0056] At the second lateral end 20, the container 2 or the motor 1 is completely sealed with a second potting compound 23. The second potting compound 23 is flush with the outer casing 11. The inner casing 8 terminates with a certain margin in the potting compound 23. The potting compound 23 is penetrated by an electrical connection cable 24 of the motor 1 and a perfusion connection 25 arranged at the second lateral end 20. On the outside, the perfusion connection 25 has a connection contour 26, for example for a hose. On the inside, the perfusion connection 25 serves to inject the fluid flowing through the gap 5 and is firmly inserted into the inner circumference of the inner casing 8. The perfusion connection 25 is in complete contact with the inside 10 of the inner casing 8 and preferably forms a sliding fit with the inner casing 8. Preferably, the direction of the fluid flow is from the perfusion connection 25 towards the motor flange 13.

[0057] Axial along the motor axis A, a spring washer 27 is arranged between the rotor 4 and the perfusion connection 25 and preloads the rotor 4 axially towards the first side end 12. The rotor bearing elements 9 are axially movable within the constraints of the sliding fit and the spring force of the spring washer 27 and are tensioned against each other by the spring force.

[0058] The rotor 4 has a rotor barrel 28 attached at a first lateral end 12 to a first shaft extension 29 and at a second lateral end 20 to a second shaft extension 30. The rotor barrel 28 is connected in a fluid-tight manner to the shaft extensions 29, 30 by being welded, in particular laser welded, to the shaft extensions 29, 30. To balance the rotor 4, a substance can be applied to the first shaft extension 29 and / or the second shaft extension 30 or a substance can be removed.

[0059] A first shaft extension 29 at the first lateral end 12 of the motor 1 extends at least partially into the rotor barrel 28. The first shaft extension 29 further comprises a motor shaft portion 31 protruding from the housing 2 at the first lateral end 12, for example to interact with and drive a shaft (not shown). Preferably, the motor shaft portion 31 comprises an inner square (not shown). The motor shaft portion 31 is hollow.

[0060] For manufacturing reasons, the bore of the motor shaft portion 31 continues into the area of ​​the rotor casing 28 where it is closed by a sealing plug 33 which prevents fluid from entering the rotor 4. A permanent magnet 34 in the form of a complete cylindrical magnet is located within the rotor casing 28 between the first shaft extension 29 and the second shaft extension 30.

[0061] The second shaft extension 30 also extends at least partially into the rotor barrel 28. Towards the second side end 20, the second shaft extension 30 has a reduced diameter so that it can be preferably mounted in the second rotor bearing element 9.

[0062] The spring washer 27 exerts a spring force on the rotor 4 in the direction of the first side end 12 , which presses the rotor 4 against the mounting edge 18 via the rotor bearing element 9 at the first side end 12 .

[0063] The stator 3 has a yoke 35 having a number of individual laminations 35a extending side by side in the stator space 6. The stator 3 also has an ironless winding 36 having three pairs of coils. The winding 36 extends from the annular extension 15 at the first side end 12 to a circuit board carrier 37 at the second side end 20. The circuit board carrier 37 is ring-shaped and supports a circuit board 38, which is also ring-shaped. The circuit board 38 is used herein to electrically connect the coil pairs of the motor 1.

[0064] The air gap 5 between the rotor 4 and the stator 3 is dimensioned such that it has a height of about 0.5 mm, at least in the area in which the rotor barrel 28 extends. Such a height of the air gap 5 has proven to be particularly advantageous with regard to the efficiency of the motor 1.

[0065] 2 shows an exemplary embodiment of a schematic sequence of the method 100 according to the invention. To assemble the motor 1, first the outer cylinder 11 is attached and welded to the motor flange 13, and the inner cylinder 8 with the flange portion 14 is pressed into the recess 16. The motor flange 13 with the outer cylinder 11 is provided 101. The annular space created between the outer cylinder 11 and the inner cylinder 8 - the stator space 6 - is then filled 102 with a first potting mix 22. The stator windings 36 together with the yoke 35 are inserted 103 into the still liquid first potting mix 22. After the insertion of the centering flange 21, any cavities present in the stator space 6 are filled with the first potting mix 22, so that the first potting mix 22 reaches up to the centering flange 21. The first rotor bearing element 9 is then inserted 104 together with the pre-assembled rotor 4 into the rotor space 7 in the inner tubular portion 8 such that the first rotor bearing element 9 abuts the mounting edge 18. The rotor bearing element 9 is supported on the inside 10 of the inner tubular portion 8.

[0066] Then, the spring washer 27 is placed 105 in the inner cylinder 8 together with the perfusion connection 25, and a force is applied to the perfusion connection 25 in the direction of the first side end 12, thereby preloading the rotor 4 in the direction of the first side end 12. Finally, the second side end 20 is potted 106 with the second potting compound 23. The force on the perfusion connection 25 is maintained until the second potting compound 23 is completely cured. Preferably, the stator 3 and the rotor 4 including the bearing elements 9 are preassembled outside the clean room before the insertion of the centering flange 21 and the curing of the first potting compound 22. Preferably, the assembly of the rotor 4 in the stator 3, including the filling and curing of the second potting compound 23, is performed in the clean room.

[0067] The present invention is not limited to the embodiments shown and described, but includes all embodiments that have the same effect according to the spirit of the invention. It is expressly emphasized that the embodiments are not limited to all combinations of features, but rather each individual subfeature may have inventive significance in itself, independent of all other subfeatures. Moreover, the present invention is not yet limited to the combination of features defined in claim 1, but can be defined by any other combination of several features among all the individual features disclosed. This means that, in principle, virtually any individual feature of claim 1 can be omitted and replaced by at least one individual feature disclosed elsewhere in this application. [Explanation of symbols]

[0068] 1 motor, 2 container, 3 stator, 4 rotor, 5 air gap, 6 stator space, 7 rotor space, 8 inner cylinder, 9 rotor bearing element, 10 inside of inner cylinder 8, 11 outer cylinder, 12 first side end of motor 1, 13 motor flange, 14 flange part, 15 annular extension, 16 central recess, 17 area of ​​flange part 14, 18 mounting edge, 20 second side end of motor 1, 21 centering flange, 22 first potting compound, 23 second potting compound, 24 connecting cable, 25 perfusion connection, 26 connection contour, 27 spring washer, 28 rotor cylinder, 29 first shaft extension, 30 second shaft extension, 31 motor shaft part, 33 closure plug, 34 permanent magnet, 35 yoke, 35a individual laminations, 36 ironless windings, 37 circuit board carrier, 38 circuit board.

Claims

1. In particular, a brushless motor (1) as a drive for a pump for transporting a fluid, comprising at least one housing (2), at least one stator (3) and at least one rotor (4), in which the fluid can flow through the housing (2) in an air gap (5) between the stator (3) and the rotor (4) in the housing (2), the stator (3) being formed in a fluid-tight stator space (6) and the rotor (4) being formed in a fluid-tight manner; The stator space (6) is defined in the direction of the rotor (4) by at least one inner cylindrical portion (8), and at least one rotor bearing element (9) for mounting the rotor (4) is supported on the inner periphery (10) of the inner cylindrical portion (8). Characterized by Brushless motor (1).

2. A brushless motor (1) according to claim 1, The rotor bearing element (9) or elements (9) are constructed and arranged to allow the fluid to flow around and / or through them. Characterized by Brushless motor (1).

3. A brushless motor (1) according to claim 1, The inner tube (8) is formed in one piece and / or the inner tube (8) is made of a biocompatible plastic, in particular polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE). Characterized by Brushless motor (1).

4. A brushless motor (1) according to claim 1, At least one outer casing (11) is provided, which outer casing (11) defines on the outside the space (6) for the stator, in particular the housing (2), and preferably the outer casing (11) has at least a partial wall thickness of 0.05 to 0.1 mm, in particular 0.1 to 0.5 mm. Characterized by Brushless motor (1).

5. A brushless motor (1) according to claim 1, A motor flange (13) is arranged on at least one first side end (12) of the motor (1), and the motor flange (13) supports the inner cylinder (8) and the outer cylinder (11), and in particular the inner cylinder (8) is at least partially pressed, preferably compressed, into the motor flange (13). Characterized by Brushless motor (1).

6. A brushless motor (1) according to claim 1, The inner cylindrical portion (8) has a flange portion (14) at the first side end (12), and in particular the flange portion (14) extends at least partially within the motor flange (13). Characterized by Brushless motor (1).

7. A brushless motor (1) according to claim 1, The inner cylindrical portion (8) has at least one annular extension (15) at the first side end (12), and in particular, the annular extension (15) is in close contact with the motor flange (13), preferably at an end surface. Characterized by Brushless motor (1).

8. A brushless motor (1) according to claim 1, At least one centering flange (21) is arranged at the second side end (20), said centering flange (21) positions said inner cylindrical portion (8) and said outer cylindrical portion (11) at a distance from each other, and in particular said motor (1), preferably said stator space (6), is sealed at said second side end (20) by at least one potting compound (23). Characterized by Brushless motor (1).

9. A brushless motor (1) according to claim 1, The rotor (4) has at least one rotor barrel (28), the rotor barrel (28) having a first shaft extension (29) at the first side end (12) and a second shaft extension (30) at the second side end (20), preferably the rotor barrel (28) being connected to the shaft extensions (29, 30) in a fluid-tight manner, and in particular the rotor bearing element (9) rotatably mounting the rotor (4) to the shaft extensions (29, 30). Characterized by Brushless motor (1).

10. A brushless motor (1) according to claim 1, The rotor (4) has at least one permanent magnet (34), in particular a plurality of permanent magnets (34), preferably arranged in the rotor barrel (28) and / or configured as a complete cylindrical magnet. Characterized by Brushless motor (1).

11. A brushless motor (1) according to claim 1, The first shaft extension (29) has a motor shaft portion (31) at the first lateral end (12), and in particular the motor shaft portion (31) is at least partially hollow. Characterized by Brushless motor (1).

12. A brushless motor (1) according to claim 1, The stator (3) comprises a yoke (35) having a plurality of individual laminations (35a), in particular each of the individual laminations (35a) having a thickness of 0.05 mm to 0.5 mm, in particular 0.05 mm to 0.3 mm, preferably about 0.1 mm or 0.2 mm. Characterized by Brushless motor (1).

13. A brushless motor (1) according to claim 1, The stator (3) has at least three or at least four pairs of coils, preferably two of each pair of coils connected in series. Characterized by Brushless motor (1).

14. A brushless motor (1) according to claim 1, the ratio of the outer diameter of the inner cylinder (8) to the outer diameter of the container (2) is at least partially between 0.3 and 0.7, in particular about 0.5, and / or the ratio of the outer diameter of the winding (36) of the stator (3) to the outer diameter of the yoke (35) is between 0.6 and 0.9, in particular about 0.8; Characterized by Brushless motor (1).

15. A brushless motor (1) according to claim 1, At least one outer casing (11) is provided, said outer casing (11) defining said stator space (6) on the outside. Characterized by Brushless motor (1).

16. A brushless motor (1) according to claim 15, At least one centering flange (21) is disposed on the second side end (20), said centering flange (21) spacing said inner tubular portion (8) and said outer tubular portion (11) apart from each other. Characterized by Brushless motor (1).

17. A brushless motor (1) according to claim 15 or 16, The stator space (6) is sealed at the second side end (20) by at least one potting compound (23). Characterized by Brushless motor (1).

18. A method (100) for assembling a brushless motor (1), particularly as claimed in claim 1, comprising at least - providing the motor flange (13) with the outer cylindrical part (11) arranged on the motor flange (13) and the inner cylindrical part (8) arranged on the motor flange (13) for defining the housing (2) of the motor (1), in particular the flange part (14) of the inner cylindrical part (8) entering the motor flange (13); a method step (102) of at least partially filling the stator space (6) between the inner casing (8) and the outer casing (11) with a first potting compound (22); a method step (103) of placing the windings (35) and the yoke (36) of the stator in the stator space (6), in particular on the outer periphery of the inner tubular part (8), in particular in the first potting compound (22), which has not yet solidified; a method step (104) of inserting the rotor (4) together with the rotor bearing element (9) into the rotor space (7) formed by the inner cylindrical part (8) so that the motor shaft part (31) of the rotor (4) protrudes from the housing (2) in the area of ​​the motor flange (13); a method step (105) of arranging a perfusion flange (25), in particular at least partially within said inner tubular part (8), and at least one of said centering flanges (21), in particular between said inner tubular part (8) and said outer tubular part (11); a method step (106) of potting said container (2) at said second lateral end (20) with said second potting compound (23); A method (100) comprising:

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