Rotor for electronically commutated motor and motor

Abstract

The invention relates to a rotor (10) for an electronically commutated electric machine (100), comprising a rotor body (20) consisting of a plurality of rotor laminations (12) stacked one on top of the other and connected to one another, the rotor body (20) having a through-opening (14) for receiving a rotor shaft (16), the rotor body (20) has strip-shaped magnetic elements (22) which are arranged on the outer circumference of the rotor body (20) at a uniform angular distance around a longitudinal axis (18) of the through-opening (14) and which are each arranged in a groove-shaped receptacle (28) of the rotor body (20) in a form-fitting manner, the magnetic elements (22) being fastened in the receptacles (28) of the rotor body (20) by means of an adhesive connection.

Description

Technical Field

[0001] This invention relates to a rotor for an electronically commutated motor, particularly an electric motor, characterized in that its magnetic elements are advantageously secured to the outer circumference of its rotor body by adhesive bonding. Furthermore, the invention also relates to an electric motor having a rotor constructed according to the invention. Background Technology

[0002] Rotors for electronically commutated motors are known from the prior art in a variety of ways. Such rotors typically have a rotor body composed of a large number of stacked and interconnected rotor laminations. The rotor body has a through opening for accommodating the rotor shaft, and also has strip-shaped magnetic elements fastened to the outer circumference of the rotor body at uniform angular spacing around the longitudinal axis of the rotor shaft. When the rotor rotates about the longitudinal axis, centrifugal force is generated on the magnetic elements, thus requiring reliable fixation of the magnetic elements to the rotor body. Examples known from the prior art include clamping springs (JP-2009177944A) or embedding the magnetic elements in magnetic additive material (JP-2009273240A). Sleeves radially surrounding the magnetic elements on the rotor body are also known. However, such sleeves reduce motor efficiency by resulting in a larger radial distance between the magnetic elements and the stator windings. Furthermore, it is known by itself that the magnetic elements are fixed to the rotor body solely by means of adhesive. However, the problem lies in the fact that magnetic components are typically made of rare-earth materials, which have a negative coefficient of linear expansion, while the rotor laminations of the rotor body are made of steel, which has a positive coefficient of linear expansion. Combined with the typically large temperature range that these materials may withstand during motor operation (e.g., from -40°C to +140°C), relatively large length differences occur between the components in the connection area, resulting in high mechanical stresses that must be compensated for by the adhesive material. While highly elastic adhesives are known to be used for this purpose, their drawback is the inability to generate the high adhesive strength required for the motor to operate at high speeds and thus under the large centrifugal forces acting on the magnetic components. Therefore, in the prior art, the maximum rotor speed is limited when only highly elastic adhesives are used to fix the magnetic components. Summary of the Invention

[0003] The rotor for an electronically commutated motor according to the present invention, having the features of claim 1, has the following advantages: by eliminating the fixing elements that radially increase the rotor's structural size, it has a small distance from the stator windings of the stator, resulting in relatively high efficiency. Furthermore, it achieves simple manufacturing and potentially sufficiently high rotor speeds to obtain high power.

[0004] This invention is based on the concept of using so-called crash-klebstoffe adhesives (typically used in vehicle bodies) from entirely different application areas for bonding magnetic components to rotor bodies. The background is that such so-called crash-klebstoffe adhesives contain fillers, such as nanoscale elastomer particles, which typically ensure the adhesive possesses exceptionally high impact toughness within a base matrix composed of epoxy resin, as required in the vehicle body field, for example, in crash situations. Here, the fillers are responsible for the necessary energy absorption. In the proposed application, this potential energy absorption in the bonding of magnetic components is used to compensate for the thermomechanical stress generated in the adhesive under alternating temperature stress due to the difference in linear expansion coefficients between the magnetic component and the rotor body. On the other hand, the adhesive base material used ensures that sufficiently large adhesive forces can be generated, allowing the rotor to be used even at relatively high speeds.

[0005] Therefore, in the context of the above description, the rotor for an electronically commutated motor according to the present invention, having the features of claim 1, has a rotor body composed of a large number of rotor laminations stacked one on top of the other and interconnected. The rotor body has a through opening for receiving a rotor shaft, and strip-shaped magnetic elements arranged on the outer circumference of the rotor body at uniform angular spacing around the longitudinal axis of the through opening. These magnetic elements are respectively arranged in locally shaped fittings within slotted receptacles of the rotor body, wherein the magnetic elements are fastened to the receptacles of the rotor body by adhesive bonding, and wherein the adhesive bonding contains filler with a particle size in the nanometer range. Within the framework of the present invention, "filler" is understood to refer to materials that have greater elasticity than the adhesive base material.

[0006] Advantageous improvements to the rotor for an electronically commutated motor according to the invention are set forth in the dependent claims.

[0007] As explained above, it is particularly preferred to use so-called impact adhesive as the adhesive, which has an allowable temperature range between -40°C and +140°C.

[0008] Preferably, the adhesive has an epoxy resin base and is designed as a two-component adhesive for processing. Fillers are incorporated into the adhesive at a predetermined concentration or amount to achieve the desired mechanical properties.

[0009] Regarding the materials used in the rotor, the rotor laminations are made of steel, and the magnetic elements are made of NdFeB (neodymium iron boron) or FeN (iron nitride), which are rare earth elements.

[0010] Furthermore, it is preferable that the receiving portion for the magnetic element has a groove bottom and groove walls that rise vertically from the groove bottom, wherein the magnetic element extends from the receiving portion in a radial direction relative to the longitudinal axis. The groove walls of the receiving portion rising vertically from the groove bottom ensure high-precision positioning of the magnetic element relative to the rotor body in the circumferential direction and withstand circumferential forces. The groove bottom is particularly used to receive the adhesive and to set a predetermined radial distance from the longitudinal axis. For this purpose, the groove bottom can either be constructed to be flat over the entire area of ​​the magnetic element, or preferably has a recess in the central area for receiving the adhesive. The advantage of the latter variation is that the radial positioning of the magnetic element relative to the longitudinal axis can be precisely performed or set by the raised groove bottom regions provided on both sides of the recess.

[0011] As explained at the beginning, the rotor constructed according to the present invention eliminates the need for additional measures that increase the rotor's outer diameter, such as sleeves, which would otherwise be used for radial fixing of the magnetic elements. Therefore, the magnetic elements are provided with arched outer surfaces that radially restrict the rotor relative to the longitudinal axis. The arched outer surfaces thus allow for a constant and small gap between the rotor and the radially surrounding stator, achieving the highest possible efficiency.

[0012] Finally, the present invention also includes an electronically commutated motor, particularly an electric motor, having a rotor constructed according to the present invention.

[0013] Other advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the accompanying drawings. Attached Figure Description

[0014] Figure 1 A perspective view of a rotor equipped with four magnetic elements is shown, and Figure 2 Showing Figure 1 Detailed cross-sectional view of the slotted receiving area used for magnetic components. Detailed Implementation

[0015] The same or functionally identical elements in the accompanying drawings are labeled with the same reference numerals.

[0016] exist Figure 1 The image shows a rotor 10 for an electronically commutated motor 100 (not shown separately), particularly an electric motor. This motor could be used, for example, as a drive motor for electric vehicles. To achieve the highest possible power within a small structural size, the rotor 10 needs to be able to achieve the highest possible rotational speed.

[0017] The rotor 10 consists of a large number of rotor laminations 12 stacked vertically and interconnected in a manner and method known per se, which are formed by stamping. Each rotor lamination 12 has through openings 14 arranged coaxially with each other, which are used to accommodate a rotor shaft 16, shown only in sections. The rotor shaft 16 is secured in the through openings 14 against relative rotation.

[0018] The through opening 14 and the rotor shaft 16 share a common longitudinal axis 18 about which the rotor 10 can rotate. Rotor laminations 12 form the rotor body 20, which carries strip-shaped magnetic elements 22 on its outer circumference. Viewed along the longitudinal axis 18, the magnetic elements 22 preferably extend along the entire length of the rotor body 20. The magnetic elements 22, arranged at uniform angular spacing around the longitudinal axis 18, are particularly made of rare earth elements, especially NdFeB or FeN. On the side facing the rotor body 20, the magnetic elements 22 have a flat bottom surface 24, while on the side facing away from the longitudinal axis 18, they have an arched outer surface 26.

[0019] In the illustrated embodiment, the rotor body 20 is configured to house four magnetic elements 22, which are arranged 90° off from each other relative to the longitudinal axis 18. It is also conceivable that the rotor body 20 may carry a greater number of magnetic elements 22, such as six, eight, twelve, or even more.

[0020] The rotor body 20, or rotor laminations 12, constitutes a receiving portion 28 for accommodating a magnetic element 22. The slot-shaped receiving portion 28, extending along the longitudinal axis 18, has a slot bottom 30 and two slot walls 32 that laterally restrict the slot bottom 30 and rise vertically from it. The distance between the slot walls 32 is preferably only slightly greater than the width of the magnetic element 22. Preferably, a sliding fit is used when the magnetic element 22 is radially pushed into the receiving portion 28 to avoid mechanical damage or breakage of the magnetic element 22. In the installed state, the magnetic element 22 partially protrudes from the receiving portion 28. Furthermore, as... Figure 2 The only visible feature is that the groove bottom 30 has an additional recess 34 in the center or middle region. On both sides of the recess 34, the groove bottom 30 forms two raised portions, or support surfaces 36 for the magnetic element 22. The width b of the recess 34 is preferably between 50% and 95% of the width B of the groove bottom 30.

[0021] At least in recess 34, and preferably almost exclusively in recess 34, an adhesive 40 is arranged for radially fixing the magnetic element 22 to the rotor body 20. The adhesive 40 is specifically configured as a two-component epoxy resin-based adhesive and contains fillers with particle sizes in the nanometer range. The fillers are, in particular, elastomer particles. This adhesive 40 is also known as impact adhesive 42 and is commonly used in vehicle body manufacturing.

[0022] The rotor 10 described herein can be changed or modified in various ways without departing from the concept of the present invention.

Claims

1. A rotor (10) for an electronically commutated motor (100) having a rotor body (20) composed of a large number of rotor laminations (12) stacked vertically and interconnected, wherein, The rotor body (20) has a through opening (14) for accommodating a rotor shaft (16), and strip-shaped magnetic elements (22) arranged on the outer circumference of the rotor body (20) at uniform angular spacing around the longitudinal axis (18) of the through opening (14). The magnetic elements are respectively arranged in a slot-shaped receiving portion (28) of the rotor body (20) with local shape matching. The magnetic elements (22) are fixed in the receiving portion (28) of the rotor body (20) by adhesive connection, and the adhesive (40) of the adhesive connection contains filler with a particle size in the nanometer range.

2. The rotor according to claim 1, Its features are, The adhesive (40) is a collision adhesive (42) with a permissible temperature range between -40°C and 140°C.

3. The rotor according to claim 1 or 2, Its features are, The adhesive (40) is a two-component adhesive based on epoxy resin.

4. The rotor according to any one of claims 1 to 3, Its features are, The rotor laminations (12) are made of steel, and the magnetic elements (22) are made of NdFeB or FeN.

5. The rotor according to any one of claims 1 to 4, Its features are, The receiving portion (28) has a groove bottom (30) and a groove wall (32) that rises vertically from the groove bottom (30), and the magnetic element (22) extends from the receiving portion (28) in a radial direction relative to the longitudinal axis (18).

6. The rotor according to claim 5, Its features are, Additional recesses (34) for accommodating the adhesive (40) are formed in the region of the bottom of the groove (30), and on both sides of the recesses (34), the bottom of the groove (30) has support surfaces (36) for the magnetic element (22).

7. The rotor according to claim 6, Its features are, The width (b) of the recess (34) is between 50% and 95% of the width (B) of the groove bottom (30).

8. The rotor according to any one of claims 1 to 7, Its features are, The magnetic element (22) has an arched outer surface (26) that restricts the rotor (10) radially relative to the longitudinal axis (18).

9. An electronically commutated motor (100), particularly an electric motor, having a rotor (10) according to any one of claims 1 to 8.

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