ROTOR ASSEMBLY FOR AN ELECTRIC MOTOR AND METHOD FOR MANUFACTURING A ROTOR ASSEMBLY

Abstract

The present disclosure relates to a rotor assembly for an electric motor, preferably an electric axial flux motor. The rotor assembly (100) comprises a first plate (102) positioned adjacent to a stator assembly (200) of the electric motor. The first plate (102) comprises a plurality of magnets (102a) arranged to form the first plate (102). A rotor plate (104) is attached to a first surface (102b) of the first plate (102), the rotor plate (104) being positioned opposite the stator assembly (200). A plurality of adhesive beads (106) are arranged between the first plate (102) and the rotor plate (104), configured to bond the rotor plate (104) to the first plate (102). The rotor plate (104) is provided with a plurality of holes (104a) arranged in a predefined pattern corresponding to the positions of the plurality of magnets (102a) of the first plate (102).Each hole is adapted to allow the ejection of the adhesive material from the plurality of adhesive beads (106) to facilitate the uniform distribution of the adhesive material on the first surface (102b) of the first plate (102).

Description

The present disclosure relates generally to the field of motor vehicles. In particular, but not exclusively, the present disclosure relates to an electric motor for a vehicle. Furthermore, embodiments of the present disclosure relate to a rotor assembly for an electric motor and, in particular, an electric axial flux motor for a vehicle. The global increase in the number of vehicles and the rising demand for high-performance vehicles have traditionally led to the use of larger internal combustion (IC) engines that burn hydrocarbon fuels such as gasoline and diesel. While this combustion process generates power, it also produces toxic exhaust fumes that contribute significantly to air pollution. To address environmental concerns, manufacturers are now focusing on electric vehicles (EVs), which use electric motors powered by batteries. These motors, which typically feature high torque with rotor and stator units, convert electrical energy into rotational energy to drive the vehicle's wheels via a power transmission unit. However, these drive motors are often large, space-consuming, and result in power losses and higher battery consumption. To address the space constraints and efficiency challenges in electric vehicles (EVs), manufacturers have researched and implemented various solutions. One such solution is the use of axial flux electric motors. These motors feature a stator and rotor mounted on the same axis, with the magnetic flux moving in an axial direction. This design requires less packaging space while still producing sufficient power. The rotor assembly in axial flux motors typically consists of a magnet cartridge and a rotor base plate bonded with adhesive. However, during assembly, the adhesive is often not distributed evenly, leading to air pockets between the magnet cartridge and the rotor base plate. Once the adhesive cures, the high compressive forces of the bonded ring can cause the adhesive to shatter into fragments. Furthermore, the air pockets reduce the adhesive's strength, potentially damaging or disintegrating the rotor assembly at high speeds, which can lead to accidents. Patent document CN109193989A (hereinafter referred to as the '989 publication) discloses a rotor suitable for a permanent magnet axial flux motor. The rotor comprises a rotor star arranged in the form of a circular plate with several magnet pole installation holes arranged circumferentially on the end face of the rotor star near the edge. These holes are for receiving permanent magnet poles. Additionally, pressure plates are provided on both sides of the corresponding permanent magnet poles, which are then welded to the end face of the rotor star to stabilize the permanent magnet poles. However, the '989 publication includes several additional components, such as pressure plates, which require more packaging space inside the motor, thus increasing the motor's size.Furthermore, the '989 publication does not resolve the problems related to adhesives used for attaching the magnet mounting unit to the rotor plate or rotor hub. The present disclosure aims to overcome one or more of the aforementioned limitations or any other limitations associated with the prior art. One or more shortcomings of conventional rotor assemblies are overcome, and additional advantages are provided by a rotor assembly for an electric motor, preferably for an electric axial flux motor, as claimed in the present disclosure. Additional features and advantages are realized by the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered part of the claimed disclosure. The present disclosure relates to a rotor assembly for an electric motor, preferably an electric axial flux motor. The electric motor can alternatively be defined as a traction motor, electric high-voltage motor, electric axial flux motor, etc. The rotor assembly can include a magnetic plate consisting of a plurality of magnets attached to one another to form a disk-shaped structure of the magnetic plate. The magnetic plate can alternatively also be referred to as a magnetic cassette. The magnetic plate can also be interchangeably defined below as the first plate. The rotor plate includes structural elements that increase the strength of the rotor assembly. The rotor assembly further includes a rotor plate that is attached to the first plate by an adhesive. The rotor plate is provided with a plurality of holes, preferably countersunk through holes.The holes are provided to expel the adhesive during the application of pressure to either the first plate or the rotor plate, thus securing the first plate to the rotor plate. The multiple holes are defined at a predefined location and have a predefined size. The predefined size of the multiple holes is selected to be large enough to allow the expulsion of adhesive with a specific viscosity, yet small enough not to compromise the strength of the rotor plate. The extruded adhesive is then removed from the back of the rotor plate. The multiple holes, arranged in a specific pattern on the rotor plate, facilitate the even distribution of the adhesive. The rotor plate with multiple holes prevents air entrapment during the application of pressure.The rotor assembly provides visual confirmation of the even distribution of the adhesive between the rotor plate and the first plate, and provides additional adhesive strength and venting. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered part of the claimed disclosure. In a non-limiting embodiment of the present invention, a rotor assembly for an electric motor is disclosed. The assembly includes a first plate positioned adjacent to a stator assembly of the electric motor. The first plate comprises a plurality of magnets joined together to form the first plate. The assembly includes a rotor plate attached to a surface of the first plate, and the rotor plate is positioned opposite the stator assembly. The assembly includes a plurality of adhesive beads arranged between the first plate and the rotor plate. The plurality of adhesive beads are configured to attach the rotor plate to the first plate. The rotor plate is provided with a plurality of holes arranged in a predefined pattern.The plurality of holes corresponds to the plurality of magnets of the first plate, and each hole is adapted to allow the ejection of an adhesive material from the plurality of adhesive beads to facilitate the even distribution of the adhesive material on the surface of the first plate. In one embodiment, the arrangement of the plurality of holes in the predefined pattern is in the form of a plurality of concentric circles, the center of which coincides with a longitudinal axis XX of the rotor plate. In one embodiment, each hole of the plurality of holes is a depression with a first opening and a second opening on an inner surface or an outer surface of the rotor plate. In one embodiment, the diameter of the first opening is smaller than the diameter of the second opening. In one embodiment, the rotor plate is attached to the first plate by a pressing process in order to press the majority of adhesive beads and thereby form an adhesive layer of a predefined thickness, which is arranged between the first plate and the rotor plate. In one embodiment, the first plate comprises a potting material that is arranged between adjacent magnets of the plurality of magnets to facilitate the connection of the plurality of magnets to one another. In one embodiment, the assembly comprises a clamping ring positioned around an outer circumference of the first plate. The clamping ring is configured to exert a compressive force on the majority of magnets of the first plate. In one embodiment, the majority of magnets are arranged to form a disk-shaped structure of the first plate. In a further non-limiting embodiment of the present disclosure, a method for manufacturing a rotor assembly. The method comprises joining a plurality of magnets together with a potting material to form a first plate. The method comprises attaching a plurality of adhesive beads to a surface of the first plate and positioning the first plate adjacent to a rotor plate. The method comprises attaching the first plate to the rotor plate by a pressing operation to facilitate the pressing of the plurality of adhesive beads and thereby forming an adhesive layer of a predefined thickness located between the first plate and the rotor plate. The method comprises scraping off the adhesive material ejected through the plurality of holes from an outer surface of the rotor plate after the pressing operation. In a further non-limiting embodiment of the present disclosure, an electric motor is disclosed. The electric motor comprises a stator assembly and a rotor assembly. The stator assembly comprises a stator coil wound on a plurality of stator pins. The rotor assembly is positioned on both sides of the stator assembly. The rotor assembly comprises a first plate positioned adjacent to a stator assembly of the electric motor. The first plate comprises a plurality of magnets joined together to form the first plate. The assembly comprises a rotor plate attached to a surface of the first plate, and the rotor plate is positioned opposite the stator assembly. The assembly comprises a plurality of adhesive beads arranged between the first plate and the rotor plate. The plurality of adhesive beads are configured to attach the rotor plate to the first plate.The rotor plate is provided with a plurality of holes arranged in a predefined pattern. The plurality of holes corresponds to the plurality of magnets on the first plate, and each hole is adapted to allow the dispensing of an adhesive material from the plurality of adhesive beads, thus facilitating the even distribution of the adhesive material on the surface of the first plate. It is understood that the aspects and embodiments of the disclosure described above can be used in any combination with one another. Several of the aspects and embodiments can be combined to form a further embodiment of the disclosure. The preceding summary serves only for illustration and is in no way intended to be limiting. In addition to the illustrative aspects and features described above, further aspects and features will become clear through reference to the drawings and the following detailed description. The novel features and properties of the disclosure are set forth in the appended claims. However, the disclosure itself, as well as a use, further objectives, and advantages thereof, are best understood by reference to the following detailed description of an embodiment, when read in conjunction with the accompanying drawings, where identical reference numerals represent identical elements, and in which: Fig. 1 illustrates a partial perspective view of an electric motor according to an embodiment of the present disclosure; Fig. 2 illustrates an exploded view of the electric motor from Fig. 1 according to an embodiment of the present disclosure; Fig. 3 illustrates a perspective view of a rotor assembly of the electric motor from Fig. 1 according to an embodiment of the present disclosure; Fig. 4 illustrates a perspective top view of a rotor plate of the rotor assembly of Fig. 5.3 illustrates an embodiment of the present disclosure; Fig. 5 illustrates a perspective view from below of the rotor plate of Fig. 4 illustrates an embodiment of the present disclosure; and Fig. 6 illustrates a perspective view of a first plate of the rotor assembly of Fig. 3 illustrates an embodiment of the present disclosure. The figures represent embodiments of the disclosure solely for illustrative purposes. A person skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein can be used without deviating from the objective of the disclosure described herein. While the embodiments described in the disclosure are subject to various modifications and alternative forms, specific embodiments are shown by way of example in the figures and are described below. However, it is not intended to limit the disclosure to the specific disclosed forms; on the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives that fall within the scope of the disclosure. It is noted that a person skilled in the art will be motivated by the present disclosure to modify the design of a rotor assembly for an electric motor, which may vary in different electric motor manufacturing units. Furthermore, the design of the rotor assembly, and in particular the rotor plate, may vary depending on the size of the electric motor in order to implement different operating modes. However, such modifications should be interpreted within the scope of the disclosure. Accordingly, the drawings show only those specific details that are important for understanding the embodiments of the present disclosure, so as not to obscure the disclosure with details that will be readily apparent to the average person skilled in the art who benefits from the present description. For the sake of simplicity, neither the complete vehicle nor the complete electric motor of the vehicle is shown in the drawings. The terms “includes,” “comprehensive,” or other variations thereof, used in the disclosure, are intended to cover non-exclusive inclusion, so that an assembly comprising a list of components may include not only those components but also other components not expressly listed or belonging to such assembly, process, system, or device. In other words, one or more elements in a system or device that is continued with “includes… one” does not, without further limitations, exclude the presence of other or additional elements in the system or device. Accordingly, the present disclosure relates to a rotor assembly for an electric motor, preferably for an axial flux electric motor, but is not limited to this type. The electric motor can be used to facilitate the propulsion of the vehicle. The electric motor utilizes the power or electrical energy transferred from a power storage unit of the vehicle, for example, a battery or high-voltage battery. The electric motor comprises a stator assembly, a rotor assembly, and a housing adapted to accommodate the stator and rotor assemblies. The stator assembly includes a stator coil wound around a plurality of stator pins. The housing provides protection for several components of the electric motor against foreign matter, such as dust, water, moisture, and the like.When the stator coil of the electric motor is supplied with electrical energy, the stator coil generates a magnetic flux in an axial direction to control the rotation of the rotor assembly. The rotor assembly can alternatively be defined as a rotor assembly, and the stator assembly can alternatively be defined as a stator unit. The vehicle referred to in this disclosure is, but is not limited to, an electric vehicle. The vehicle can also be a hybrid vehicle comprising both an internal combustion (IC) engine and an electric motor for propelling the vehicle. The rotor assembly can also be defined as a "permanent magnet rotor" that is rotatably mounted in the housing via a bearing. In the presence of a magnetic flux, the rotor assembly rotates about a longitudinal axis (XX). The rotor assembly and the motor assembly are mounted along the same longitudinal axis (XX), and therefore the electric motor can be defined as an axial flux motor. The longitudinal axis (XX) can be defined as an axis that runs horizontally through the center of both the rotor assembly and the stator assembly. The rotor assembly can be configured to rotate in both directions, i.e., clockwise and counterclockwise, depending on the polarity of the electric current received by the stator coil of the stator assembly. The rotation of the rotor assembly in two directions facilitates the forward and reverse movement of the vehicle.The rotor assembly can be coupled with a power transmission unit of the vehicle, for example a gearbox or a gear drive, which is configured to facilitate the transfer of power from the electric motor to the drive wheels of the vehicle depending on the driving conditions of the vehicle. In one embodiment, the rotor assembly includes a first plate positioned adjacent to a stator assembly of the electric motor. The first plate comprises a plurality of magnets joined together to form the first plate. The assembly includes a rotor plate attached to a first surface of the first plate, and the rotor plate is positioned opposite the stator assembly. The assembly includes a plurality of adhesive beads arranged between the first plate and the rotor plate. The plurality of adhesive beads are configured to attach the rotor plate to the first plate. The rotor plate is provided with a plurality of holes arranged in a predefined pattern.The plurality of holes corresponds to the plurality of magnets of the first plate, and each hole is adapted to allow the ejection of an adhesive material from the plurality of adhesive beads to facilitate the uniform distribution of the adhesive material on the first surface of the first plate. In one embodiment, the plurality of holes are arranged in a predefined pattern in the form of a plurality of concentric circles whose centers coincide with a longitudinal axis XX of the rotor plate. Alternatively, the plurality of holes can be arranged in a different pattern to facilitate sufficient and necessary ejection of the adhesive material during the assembly of the components belonging to the rotor assembly. Each hole of the plurality of holes is countersunk with a first opening and a second opening on an inner surface and an outer surface, respectively, of the rotor plate. In one embodiment, the rotor plate is attached to the first plate by a pressing operation to press multiple beads of adhesive, thereby forming an adhesive layer of a predefined thickness located between the first plate and the rotor plate. The pressing operation can be performed using a hydraulic press, a pneumatic press, or similar equipment. The first plate includes a potting compound positioned between adjacent magnets of the multiple magnets to facilitate their connection. The assembly includes a clamping ring positioned around an outer circumference of the first plate. The clamping ring is configured to exert a compressive force on the multiple magnets of the first plate. In the following sections, the present disclosure is described with reference to Figs. 1, 2, 3, 4, 5 to 6. In the figures, the same element or elements having similar functions are indicated by the same reference numerals. With reference to Fig. 1, a perspective partial view of an electric motor (300) is shown. The electric motor (300) can be used as a drive motor for a vehicle (not shown in the Fig.), preferably an electric vehicle, but is not limited to this. The vehicle can be fitted with an electric motor (300) that uses electrical power or electrical energy supplied by a power storage unit (not shown in the Fig.), for example, a battery, to drive the vehicle. The vehicle can be described as a passenger car, commercial vehicle, heavy-duty vehicle, four-wheeler, or two-wheeler, but is not limited to these. The electric motor (300) is configured to supply a rotary motion to drive the wheels of the vehicle to facilitate driving the vehicle.The electric motor (300) is coupled to the drive wheels via a power transmission unit, allowing the power transmission unit to vary the power or rotational speed (RPM) of the drive wheels as needed or according to driving conditions. The electric motor (300) can be defined as a high-torque motor that generally generates high rotational power / motion under operating conditions. Alternatively, the electric motor (300) can be defined as an electric axial flux motor or electric machine configured to perform various operations, such as powering vehicles, lifting heavy components or parts in the assembly line of a vehicle manufacturing unit, and similar tasks. In one embodiment, the electric motor (300) comprises a rotor assembly (100) and a stator assembly (200). The rotor assembly (100) may alternatively be referred to as an "assembly," "rotor unit," or similar. The stator assembly (200) may alternatively be referred to as a "stator unit" or similar. The stator assembly (200) and the rotor assembly (100) are housed in a casing (not shown in the figures) to protect the components and subcomponents associated with the stator assembly (200) and the rotor assembly (100). The casing is configured to prevent the incorporation of foreign particles, such as dust, dirt, moisture, water, and the like, onto the components of the electric motor (300), such as the stator assembly, rotor assembly, and similar. The electric motor (300) may have at least two terminals (not shown in the figures).(not shown) to electrically connect the stator assembly (200) of the electric motor (300) to a power storage unit of the vehicle. The stator assembly (200) comprises a stator coil (not shown in the figures) wound on a plurality of stator pins (202) arranged in a predefined structure. The predefined structure can be defined as a circular structure, as shown in Figures 1 and 2. When the stator coil of the stator assembly (200), wound on the stator pins (202), receives power, current, or an electrical energy supply, this results in the generation of a magnetic flux, which in turn controls the rotation of the rotor assembly (100). The electric motor (300) is provided with at least two rotor assemblies, as shown in Figure 1, arranged on both sides of the stator assembly (200). Alternatively, the stator assembly (200) can also be inserted between the two rotor assemblies (100). The rotor assembly (100) can be operated with a rotor shaft (shown in Figures 1 and 2).(not shown) are coupled, and the rotor shaft is thereby connected to a power transmission unit of the vehicle. The rotation of the rotor assembly (100) in the presence of the magnetic flux controls the rotation of the rotor shaft, which in turn facilitates the propulsion of the vehicle. The rotor assembly (100) and the stator assembly (200) are aligned along a longitudinal axis XX, as shown in Fig. 2, and thus form the electric motor (300), preferably an axial flux electric motor. In one embodiment, the rotor assembly (100) comprises a first plate (102) positioned adjacent to the stator assembly (200) of the electric motor (300), as shown in Fig. 2. The first plate (102) may alternatively be referred to as a "magnetic cassette," "magnetic disk," or similar, but this is not limited to such terms. Referring to Fig. 2 and Fig. 6, the first plate (102) comprises a plurality of magnets (102a) attached to one another and forming the first plate (102). The plurality of magnets (102a) can be defined with any predefined structure such that the first plate (102) forms a disk-shaped structure once the plurality of magnets are laterally attached to or connected to one another.The first plate (102) comprises a potting material (102c) arranged between adjacent magnets (102a) of the plurality of magnets (102a) to facilitate the connection of the plurality of magnets (102a) to one another, as shown in Fig. 6. The plurality of magnets (102a) can be defined as permanent magnets, natural magnets, and the like. The assembly (100) comprises a clamping ring (108) positioned around the outer circumference of the first plate (102), as shown in Fig. 2. The clamping ring (108) is configured to exert a compressive force on the plurality of magnets (102a) of the first plate (102). The clamping ring (108) is provided to prevent displacement of the plurality of magnets (102a) during rotation of the rotor assembly (100) at high revolutions per minute (rpm). The clamping ring (108) can be made of a high-strength material and tends to exert a pre-tensioning compressive force towards the center of the first plate (102).The majority of magnets (102a) are arranged to form a disk-shaped structure of the first plate (102). The first plate (102) can be defined as having a first surface (102b) and a second surface (not shown in the figure) facing the first surface (102b). The second surface can be defined as a surface facing the stator assembly (200), and the first surface (102b) as a surface facing the stator assembly (200). In an exemplary embodiment, the first plate (102) comprises eight magnets (102a) which are attached to one another by the potting material (102c), as shown in Fig. 6. The eight magnets (102a) are arranged such that, when attached to one another, they form the disk-shaped structure of the first plate (102). The first plate (102) is provided with a central hole for receiving the rotor shaft of the electric motor (300).In one embodiment, the assembly (100) comprises a rotor plate (104) attached to the first surface (102b) of the first plate (102). The rotor plate (104) is positioned opposite the stator assembly (200). Referring to Figures 4 and 5, the rotor plate (104) is also defined as having a disk-shaped structure that is larger than the first plate (102). In one embodiment, the rotor plate (104) is rigidly attached to the first plate (102) by means of fasteners. The rotor plate (104) is provided with a plurality of holes (104a) arranged in a predefined pattern, as shown in Figures 4 and 5. The plurality of holes (104a) corresponds to the plurality of magnets (102a) of the first plate (102), i.e., the number of holes (104a) is at least equal to the number of magnets (102a).The arrangement of the plurality of holes (104a) in the predefined pattern in the form of a plurality of concentric circles, the center of which coincides with a longitudinal axis XX of the rotor plate (104). The longitudinal axis XX can be defined as an axis that passes through the center of the rotor plate (104). The rotor assembly (100) and the stator assembly (200) are arranged axially such that the center of the rotor assembly (100) and the stator assembly (200) coincides with the longitudinal axis XX. The plurality of holes (104a) can be defined with a predefined structure. In one embodiment, each hole of the plurality of holes (104a) is a countersink, but not limited to countersinks. Each hole of the plurality of holes (104a) is defined by a first opening and a second opening on an inner surface (104b) and an outer surface (104c), respectively, of the rotor plate (104). The diameter of the first opening is smaller than the diameter of the second opening. The inner surface (104b) can be defined as a surface facing the first plate (102), and the outer surface (104c) can be defined as a surface opposite the inner surface (104b). The rotor plate (104) can also be provided with a central hole corresponding to the central hole of the first plate (102) to accommodate the rotor shaft of the electric motor (300). In one embodiment, the plurality of holes (104a) comprises at least three sets of holes, as shown in Figs. 4 and 5. Each set of holes comprises a plurality of holes corresponding to the plurality of magnets (102a). Each set of holes is arranged in the form of concentric circles such that the first set of holes may be defined near an inner diameter of the rotor plate (104), the second set of holes may be defined near an outer diameter of the rotor plate (104), and the third set of holes may be defined between the first and second sets of holes. Each hole of the plurality of holes (104a) is arranged in a radially outward direction and is positioned directly above the potting material (102c) of the first plate (102). In one embodiment, the rotor assembly (100) comprises a plurality of adhesive beads (106), as shown in Fig. 6. The plurality of adhesive beads (106) is arranged between the first plate (102) and the rotor plate (104). The plurality of adhesive beads (106) is configured to attach the rotor plate (104) to the first plate (102). The plurality of adhesive beads (106) is attached to the first surface (102b) of the first plate (102). The plurality of adhesive beads (106) is attached to the plurality of magnets (102a) of the first plate (102). The plurality of adhesive beads (106) can be defined with any predefined structure. The plurality of adhesive beads (106) can be made of an adhesive material with high adhesive strength to firmly attach the first plate (102) to the rotor plate (104). In one embodiment, each hole of the plurality of holes (104a) is adapted to allow the ejection of the adhesive material from the plurality of adhesive beads (106) to facilitate the uniform distribution of the adhesive material on the first surface (102b) of the first plate (102). The plurality of holes (104a) allows visual control of the uniform distribution of the adhesive material during the attachment of the first plate (102) to the rotor plate (104), as shown in Fig. 3. The rotor plate (104) is attached to the first plate (102) by a pressing operation to press the plurality of adhesive beads (106) and thereby form an adhesive layer (106a) of a predefined thickness, which is arranged between the first plate (102) and the rotor plate (104). In an exemplary embodiment, a method for manufacturing a rotor assembly is disclosed. The method comprises joining a plurality of magnets (102a) together with a potting material (102c) to form a first plate (102). The method includes a step of attaching a plurality of adhesive beads (106) to a first surface (102b) of the first plate (102) and positioning the first plate (102) next to a rotor plate (104). The method includes attaching the first plate (102) to the rotor plate (104) by a pressing operation to facilitate the pressing of the plurality of adhesive beads (106) and thereby forming an adhesive layer (106a) of a predefined thickness, which is arranged between the first plate (102) and the rotor plate (104).The process involves scraping off the adhesive material ejected through the plurality of holes (104a) from an outer surface (104c) of the rotor plate (104) after the pressing process. The pressing process can be carried out with any pressing machine, for example, hydraulic presses, pneumatic presses, or similar, but is not limited to them. In one embodiment of the present disclosure, the plurality of holes provided in a specific pattern on the rotor plate facilitates the uniform distribution of the adhesive. In one embodiment of the present disclosure, the rotor plate defined by a plurality of holes prevents air entrapment during the application of the pressure force. In one embodiment of the present disclosure, the rotor assembly provides visual confirmation of the uniform distribution of the adhesive between the rotor plate and the first plate and provides additional adhesive strength and venting. It is self-evident that a person skilled in the art can develop a rotor assembly for an electric motor with a similar configuration without deviating from the scope of this disclosure. Such modifications and variations can be made without deviating from the scope of this disclosure. It is therefore intended that this disclosure covers such modifications and variations, provided they fall within the scope of the appended claims and their equivalents. List of reference symbols: 100 Rotor assembly 102 First plate 102a Magnets 102b First surface 102c Potting compound 104 Rotor plate 104a Holes 104b Inner surface of rotor plate 104c Outer surface of rotor plate 106 Adhesive beads 106a Adhesive layer 108 Clamping ring 200 Stator assembly 202 Stator die 300 Electric motor QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature CN 109193989A

[0005]

Claims

Rotor assembly (100) for an electric motor (300), wherein the rotor assembly (100) comprises: a first plate (102) positioned adjacent to a stator assembly (200) of the electric motor (300), the first plate (102) comprising a plurality of magnets (102a) arranged to form the first plate (102); a rotor plate (104) attached to a first surface (102b) of the first plate (102), the rotor plate (104) positioned opposite the stator assembly (200); a plurality of adhesive beads (106) arranged between the first plate (102) and the rotor plate (104), the adhesive beads (106) configured to bond the rotor plate (104) to the first plate (102);the rotor plate (104) is provided with a plurality of holes (104a) arranged in a predefined pattern corresponding to the positions of the plurality of magnets (102a) of the first plate (102), each hole being adapted to allow the ejection of the adhesive material from the plurality of adhesive beads (106) to facilitate the uniform distribution of the adhesive material on the first surface (102b) of the first plate (102). Rotor assembly (100) according to claim 1, wherein the plurality of holes (104a) are arranged in a predefined pattern of a plurality of concentric circles, the center of the circles coinciding with a longitudinal axis XX of the rotor plate (104). Rotor assembly (100) according to claim 2, wherein each hole of the plurality of holes (104a) is a depression with a first opening on an inner surface (104b) and a second opening on an outer surface (104c) of the rotor plate (104). Rotor assembly (100) according to claim 3, wherein a diameter of the first opening is smaller than a diameter of the second opening. Rotor assembly (100) according to claim 3, wherein the rotor plate (104) is attached to the first plate (102) by a pressing process to press the plurality of adhesive beads (106) and thereby form an adhesive layer (106a) of a predefined thickness which is arranged between the first plate (102) and the rotor plate (104). Rotor assembly (100) according to claim 1, wherein the first plate (102) comprises a potting material (102c) arranged between adjacent magnets (102a) of the plurality of magnets (102a) to facilitate the connection of the plurality of magnets (102a) to each other. Rotor assembly (100) according to claim 6, which further comprises a clamping ring (108) positioned around an outer circumference of the first plate (102), wherein the clamping ring (108) is configured to exert a pressure force on the plurality of magnets (102a) of the first plate (102). Rotor assembly (100) according to claim 7, wherein the plurality of magnets (102a) are arranged to form a disk-shaped structure of the first plate (102). Method for assembling a rotor assembly (100), comprising: joining a plurality of magnets (102a) together using a potting material (102c) to form a first plate (102); applying a plurality of adhesive beads (106) to a first surface (102b) of the first plate (102) and positioning the first plate (102) next to a rotor plate (104); securing the first plate (102) to the rotor plate (104) by a pressing operation to facilitate the pressing of the plurality of adhesive beads (106), thereby forming an adhesive layer (106a) of a predefined thickness arranged between the first plate (102) and the rotor plate (104); scraping off the adhesive material ejected through the plurality of holes (104a) from an outer surface (104c) of the rotor plate (104) after the pressing operation. Electric motor (300) comprising: a stator assembly (200) comprising a stator coil wound on a plurality of stator dies (202); a rotor assembly (100) positioned on both sides of the stator assembly (200), the rotor assembly (100) comprising: a first plate (102) positioned adjacent to a stator assembly (200) of the electric motor (300), the first plate (102) comprising a plurality of magnets (102a) joined together to form the first plate (102); a rotor plate (104) attached to a first surface (102b) of the first plate (102), the rotor plate (104) positioned opposite the stator assembly (200); a plurality of adhesive beads (106) arranged between the first plate (102) and the rotor plate (104), wherein the The majority of adhesive beads (106) are configured to attach the rotor plate (104) to the first plate (102);the rotor plate (104) is provided with a plurality of holes (104a) arranged in a predefined pattern, wherein the plurality of holes (104a) corresponds to the plurality of magnets (102a) of the first plate (102) and each hole is adapted to allow the ejection of an adhesive material of the plurality of adhesive beads (106) to facilitate the uniform distribution of the adhesive material on the first surface (102b) of the first plate (102).

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