Electric motor

Abstract

The invention relates to a pump unit comprising at least one impeller (4) and an electric motor connected to the at least one impeller (4) and comprising a stator (12), a rotor (8) and an encapsulation shell (18) between the stator (12) and the rotor (8), where the encapsulation shell (18) is engaged on a first axial end thereof with a support structure (10), where the first axial end of the encapsulation shell (18) is connected to the support structure (10). At least one axial damping member (32) is arranged between the axial surface (26) of the encapsulation shell (18) and the support structure (10), and at least one radial damping member (34) is arranged between the outer circumferential surface of the encapsulation shell (18) and the support structure (10).

Description

Technical Field

[0001] The invention relates to a pump unit comprising at least one impeller and a wet-running electric motor. Background Art

[0002] A pump unit such as a centrifugal pump arrangement (e.g. a circulating pump) generally comprises at least one impeller driven by an electric drive motor. The electric drive motor is generally configured as a wet-running motor with a can between the stator and the rotor. The can separates the dry stator space from the wet rotor space. In a common configuration, bearings for the rotor shaft are arranged in the rotor can. In order to adequately support the rotor can, the rotor can may be engaged with a surrounding support structure.

[0003] The encapsulation between the rotor and stator has an effect on the magnetic field between the stator and the rotor, because the encapsulation requires a greater distance between the rotor and the stator. This has a negative impact on the efficiency of the motor. To increase efficiency, it is desirable to reduce the gap between the rotor and the stator, which requires the rotor encapsulation to have a minimum thickness. Summary of the invention

[0004] It is an object of the invention to allow an encapsulating housing with a reduced thickness. This object is achieved by a pump unit having the features defined in claim 1. Preferred embodiments are defined in the dependent claims, the following description and the drawings.

[0005] The pump unit according to the present invention comprises at least one impeller and an electric motor, which is connected to the at least one impeller to rotate the impeller. The motor comprises a stator and a rotor, wherein the rotor is preferably connected to the impeller via a rotor shaft. The electric motor is a wet-running electric motor, wherein the encapsulating shell is arranged between the stator and the rotor so that the rotor runs in the fluid, and the stator is arranged in the dry space of the motor. Such a pump unit (i.e., a centrifugal pump unit) is preferably configured as a circulating pump, which can be used in hydraulic systems such as heating systems and / or cooling systems.

[0006] To support the rotor can, the can engages with a support structure (ie a support structure around the can) at its first axial end. The support structure may be connected to or may be part of the stator and / or the surrounding motor housing.

[0007] According to the present invention, at least one axial damping component is arranged between the axial surface of the encapsulating shell and the support structure. In addition, at least one radial damping component is arranged between the outer circumferential surface of the encapsulating shell and the support structure. The axial damping component and the radial damping component allow the encapsulating shell to be supported in the axial direction and the radial direction via the damping component arranged therebetween. The damping component avoids the transmission of vibrations occurring in the rotor encapsulating shell to the surrounding support structure. Therefore, the stator and other components connected to the support structure (for example, an electronic device housing and electronic components) remain free from vibration. In particular, such vibrations may occur when the encapsulating shell has a low wall thickness. Therefore, the arrangement of the damping component in the axial support and radial support of the encapsulating shell allows the wall thickness of the rotor encapsulating shell to be further reduced without transmitting undesirable vibrations to other components of the pump unit and the entire surrounding pump structure. In particular, noise reduction can be achieved by arranging the axial damping component and the radial damping component between the encapsulating shell and the surrounding support structure.

[0008] According to a preferred embodiment of the present invention, at least one axial damping component and at least one radial damping component are integrally formed by a single damping element. Thus, the number of required components is minimized and the cost of producing the damping element can be reduced.

[0009] In a possible embodiment, at least one axial damping component is annular, and at least one radial damping component is tongue-shaped and extends from the inner circumference of the annular axial damping component. In a preferred embodiment, a plurality of tongue-shaped radial damping components are arranged on the inner circumference of the axial damping component. Preferably, a plurality of tongue-shaped radial damping components are spaced apart from each other in the circumferential direction so that a gap or free space is formed between adjacent radial damping components. Further preferably, a plurality of radial damping components are evenly distributed along the inner circumference of the axial damping component. The arrangement of a plurality of tongue-shaped damping components allows for easier installation with higher precision. The tongue-shaped configuration of the radial damping component allows the radial damping component to bend relative to the axial damping component. This allows an integral damping component to be formed by a flat damping element, and allows the radial damping components to be bent in a direction so that they can be arranged between the outer circumferential surface of the encapsulating shell and the surrounding support structure, thereby allowing force to be transmitted in a radial direction. Thus, the radial damping component extends substantially parallel to the longitudinal axis of the pump unit (i.e., the axis of rotation of the impeller). Preferably, the at least one axial damping member extends in a direction transversely or perpendicularly to the longitudinal axis.

[0010] According to another possible embodiment, at least one axial damping component and at least one radial damping component are formed from a flat material and are preferably cut from a flat material. As previously mentioned, at least one radial damping component is preferably bent in a direction transverse to the axial damping component. This allows a three-dimensional damping including an axial damping component and at least one radial damping component to be easily formed from a flat material. Cutting the flat material can be done by a cutting or stamping device. Instead of cutting the damping component from a flat material, the damping component can be formed in a different way, preferably integrally. This can be done by a molding and vulcanization process. Alternatively, the radial damping component and the axial damping component can be formed integrally by injection molding, 3D printing or other suitable methods. In order to cut material from a flat material, different cutting methods can be used, such as stamping or water jet cutting.

[0011] Preferably, at least one axial damping component and at least one radial damping component are made of an elastic material, preferably made of rubber or synthetic rubber, further preferably made of EPDM (ethylene propylene diene monomer rubber). This material can be provided as a flat pad or a rolled material. The flat material can be cut or punched into a desired shape, for example, cut or punched into an annular axial damping component having a radially extending tongue arranged on its inner circumference, wherein the tongue is then bent in an axial direction to form a radial damping component. The elastic material provides the desired damping characteristics. By adapting the elasticity, the material can be adapted to the vibration behavior of the encapsulating shell. In addition, this material can provide the required stiffness to allow the transmission of the forces occurring, in particular the forces from the bearing assembly arranged in the encapsulating shell.

[0012] For example, the surrounding support structure is connected to or is part of the motor housing. Alternatively, the support structure may be part of a stator assembly or stator arrangement of the pump unit, such as being connected to or formed by an iron component of the stator assembly. Such a support structure provides the required stiffness to support a bearing assembly arranged in the encapsulating shell and allows forces to be transferred from the impeller via the rotor, rotor bearings, rotor encapsulating shell and damping components to the support structure.

[0013] In another embodiment, the first axial end of the encapsulating shell may be a closed end. Thus, the encapsulating shell is cup-shaped. Such an encapsulating shell is tightly sealed toward the stator space. Preferably, a shaft bearing may be fixed in the encapsulating shell, preferably close to its first axial end. Such a bearing supports the free end of the rotor shaft, i.e., the end away from at least one impeller. Preferably, the bearing is a radial bearing that transmits forces in a radial direction. Preferably, the axial bearing is arranged close to the impeller. Furthermore, there may be a second radial bearing on the other side of the rotor, i.e., adjacent to the impeller.

[0014] In one example, the encapsulation shell can be made of steel, in particular stainless steel. Alternatively, the encapsulation shell can be made of a composite material (e.g., a fiber reinforced plastic material). In addition, this composite material can have a sealing layer or coating to provide tightness to prevent diffusion. Stainless steel or composite materials allow the production of a rotor encapsulation shell with minimized wall thickness. According to another preferred embodiment, the wall thickness of the encapsulation shell is less than 0.25 mm, more preferably less than 0.2 mm, for example 0.18 mm or thinner. In particular, this minimized wall thickness can be achieved in a stainless steel encapsulation shell.

[0015] According to another preferred embodiment, the support structure comprises an axial surface, which faces the encapsulating shell and is in contact with at least one axial damping component. This allows axial forces to be transferred from the encapsulating shell via the axial damping element to the axial surface of the support structure. Furthermore, the support structure preferably comprises an inner circumferential surface, which extends transversely to the axial surface and is in contact with at least one radial damping component. This allows forces to be transferred from the encapsulating shell (i.e., the outer circumferential wall of the encapsulating shell) in radial direction via the radial damping component to the inner circumferential surface of the support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In the following, the present invention is described by way of example with reference to the accompanying drawings. In these drawings:

[0017] Figure 1 shows a cross section of a pump unit according to the invention,

[0018] Figure 2 shows an enlarged portion of a cross section of a pump unit according to the invention, and

[0019] Figure 3 A plan view of the damping element is shown. DETAILED DESCRIPTION

[0020] Figure 1The pump device shown in is a centrifugal pump, which can be used as a circulation pump in a hydraulic system. Typically, the pump device comprises a pump housing 2, in which an impeller 4 is arranged. The impeller is connected to a rotor shaft 6 carrying a magnetic rotor 8 of an electric motor. The electric motor is arranged inside a motor housing 10, which is connected to the pump housing 2. Inside the motor housing 10, a stator 12 of the electric motor is arranged, which includes an iron core and the required coils.

[0021] The rotor shaft 6 is supported by two bearings 14 and 16, both of which are radial bearings. The bearing 16 also serves as an axial bearing. An encapsulation shell 18 is arranged between the rotor 8 and the stator 12, which separates the dry stator space accommodating the stator 12 from the wet rotor space accommodating the rotor 8. The bearing 14 is supported inside the cup-shaped encapsulation shell 18, close to the closed end 20 of the encapsulation shell 18. In order to transfer the forces acting on the encapsulation shell 18 (especially the forces generated from the bearing 14) and the pressure inside the encapsulation shell 18 to the surrounding support structure, the closed end 20 of the encapsulation shell 18 is engaged with the motor housing 10 as a support structure.

[0022] The encapsulating shell 18 has a circumferential wall 22 near its closed end 20, which faces the inner circumferential surface 24 of the motor housing 10. Figure 1 As shown, around the circumferential wall 22, the encapsulating shell 18 has a shoulder, which extends in a direction transverse to the rotation axis X of the impeller 4 and forms an axial support surface 26 of the encapsulating shell 18. This axial support surface 26 of the encapsulating shell 18 faces the inner axial surface 28 of the motor housing 10. A damping element 30 is arranged between the axial support surface 26 and the inner axial surface 28 and between the circumferential wall 22 and the inner circumferential surface 24. The damping element as an integral element comprises an axial damping component 32 arranged between the axial support surface 26 and the inner axial surface 28 and a plurality of radial damping components 34 arranged between the circumferential wall 22 and the inner circumferential wall 24.

[0023] Figure 2 An enlarged cross-sectional view of a damping element 30 according to the present invention is shown, with reference to Figure 2 And refer to Figure 3 The configuration and arrangement of the damping element 30 will be described in more detail. Figure 3 As can be seen in FIG. 1 , the damping element 30 is made, for example, of a flat damping element made of an elastic material pad. The damping element 30 is cut into a shape consisting of an annular axial damping component 32, wherein the radial damping components 34 are tongue-shaped and extend from the inner circumference 36 of the annular axial damping component 32. In this example, there are eight tongue-shaped radial damping components 34, which are evenly distributed on the inner circumference 36. The radial damping components 34 are spaced apart from each other, forming gaps or free spaces 38 between them. As shown in FIG. Figure 3As seen in the top view of FIG. 3 , the radial damping member 34 has a trapezoidal shape that narrows toward the radial inner end.

[0024] When inserted into the motor housing 10, that is, between the motor housing 10 and the packaging shell 18, as shown Figure 3 The flat damping element 30 shown is bent into Figure 1 and Figure 2 . In particular, the radial damping component 34 is bent into an axial direction substantially parallel to the longitudinal axis X of the pump device. In this configuration, the axial damping component 32 is arranged between the axial support surface 26 and the inner axial surface 28, while the radial damping component 34 is arranged between the circumferential wall 22 of the encapsulating shell 18 and the inner circumferential surface 24 of the surrounding motor housing. With this configuration, the encapsulating shell is supported at its closed end 20 via the damping element 30 in the axial direction and in the radial direction, thereby avoiding the transmission of vibrations from the encapsulating shell 18 to the motor housing 10 and other connected components of the pump unit (e.g., electronic components).

[0025] Reference numerals

[0026] 2 Pump housing

[0027] 4 Impeller

[0028] 6 Rotor shaft

[0029] 8 rotors

[0030] 10Motor housing

[0031] 12 Stator

[0032] 14, 16 bearings

[0033] 18 package shell

[0034] 20 Closed end of package shell

[0035] 22 Circumferential wall of the package shell

[0036] 24 Inner circumferential surface

[0037] 26 Axial support surface

[0038] 28 Inner axial surface

[0039] 30 Damping element

[0040] 32Axial damping components

[0041] 34 Radial damping components

[0042] 36 inner circumference

[0043] 38 Free Space

[0044] X longitudinal axis / rotation axis

Claims

1. A pump unit comprising at least one impeller (4) and an electric motor, the electric motor being connected to the at least one impeller (4) and comprising a stator (12), a rotor (8) and an encapsulation casing (18) between the stator (12) and the rotor (8), wherein: The encapsulating shell (18) is engaged with the supporting structure (10) at its first axial end, Features at least one axial damping member (32) is arranged between an axial surface (26) of the encapsulating shell (18) and the support structure (10), and At least one radial damping component (34) is arranged between the outer circumferential surface of the encapsulating shell (18) and the support structure (10).

2. The pump unit according to claim 1, characterized in that The at least one axial damping component (32) and the at least one radial damping component (34) are integrally formed from a single damping element (30).

3. The pump unit according to claim 1 or 2, characterized in that The at least one axial damping component (32) is annular, and the at least one radial damping component (34) is tongue-shaped and extends from the inner circumference of the axial damping component (32), wherein, preferably, a plurality of tongue-shaped radial damping components (34) are arranged on the inner circumference of the axial damping component (32).

4. Pump unit according to one of claims 1 to 3, characterized in that The at least one axial damping component (32) and the at least one radial damping component (34) are formed from flat material and are preferably cut from flat material, wherein the at least one radial damping component (34) is bent in a direction transverse to the axial damping component (32).

5. Pump unit according to one of the preceding claims, characterized in that The at least one axial damping component (32) and the at least one radial damping component (34) are made of elastic material, preferably rubber or synthetic rubber, and further preferably ethylene propylene diene monomer rubber EPDM.

6. Pump unit according to one of the preceding claims, characterized in that The support structure (10) is connected to the motor housing (10) or is part of the motor housing (10).

7. Pump unit according to one of the preceding claims, characterized in that The first axial end of the encapsulating shell (18) is a closed end (20), wherein, preferably, a bearing is fixed in the encapsulating shell (18) close to the first axial end of the encapsulating shell.

8. Pump unit according to one of the preceding claims, characterized in that The packaging shell (18) is made of stainless steel or a composite material.

9. Pump unit according to one of the preceding claims, characterized in that The support structure (10) comprises an axial surface facing the encapsulating shell (18) and in contact with the at least one axial damping component (32), and the support structure (10) comprises an inner circumferential surface (24) extending transversely to the axial surface and in contact with the at least one radial damping component (34).

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