DESC:ROTOR CORE FOR MOTOR
CROSS REFERENCE TO RELATED APPLICTIONS
The present application claims priority from Indian Provisional Patent Application No. 202321065126 filed on 28/09/2023, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
Generally, the present disclosure relates to an electric motor. Particularly, the present disclosure relates to a rotor core of the electric motor.
BACKGROUND
Recently, traction motors are increasingly being used due to adoption of electric vehicles. AC motors are one of the good options to serve as traction motor in electric vehicles due to their high performance and efficiency. Also, an electric motor is indispensable for converting electrical energy into mechanical energy, which leads to numerous applications across various sectors. The electric motor may enhance efficiency and productivity in industries by operating numerous machineries, automating tasks and providing precise control over machinery, crucial for manufacturing, robotics.
Generally, the motors are used in various high-power applications such as electric vehicles. It is to be understood that the motors used in the automobile application are highly power dense and have multiple mechanical components including a stator assembly, a rotor assembly, a casing. Due to presence of multiple mechanical components, each with their own sub-components, significantly increases the complexity of manufacturing and assembly processes. Furthermore, the rotor assembly of the motor comprises a rotor shaft, a rotor core, a permanent magnet and so on. Typically, each of the mechanical component of the rotor assembly are manufactured separately and then assembled together to form the mechanical assembly of the rotor. It is to be understood that the components are either permanently joined or mechanically engaged to form the rotor assembly. During operation, the rotor assembly operates at high rpm causing huge mechanical stress on the rotor assembly. Due to such mechanical stress, the components of the rotor assembly are prone to failures. For instance, the rotor shaft experiences high mechanical stress due to uneven torsional loads, vibrations and rotational forces. Due to these, the rotor shaft experiences stress imbalances. As a result, this imbalance may cause concentrated stress in certain areas of the rotor shaft causing the rotor shaft to break over time. Furthermore, a failure of the joint between the rotor core and the rotor shaft may cause the rotor core to slip on the rotor shaft.
Therefore, there is a need to develop an improved rotor core design that overcomes the one or more problems as set forth above.
SUMMARY
An object of the present disclosure is to provide a rotor core with locking mechanism to lock rotor core and rotor shaft.
In accordance with an aspect of present disclosure there is provided a rotor core constructed by stacking a plurality of electromagnetic sheets. The rotor core comprises a shaft hole configured to receive a rotor shaft, at least one groove in the shaft hole, and at least one protrusion extended along the length of the shaft hole.
The present disclosure provides a rotor core for electric motor. The rotor core as disclosed by the present disclosure is advantageous in terms of providing enhanced magnetic efficiency and structural integrity due to specific construction. The shaft hole of the rotor core as disclosed by present disclosure is beneficially comprising at least one groove, to secure at least one locking plate with the rotor core. Beneficially, the at least one locking plate secures the plurality of rotor magnets inside the rotor core preventing any movement of the plurality of rotor magnets during operation. The rotor core as disclosed by the present disclosure beneficially comprises at least one protrusion extended along the length of the shaft hole to securely lock the rotor shaft with the rotor core. Beneficially, the rotor core as disclosed by the present disclosure is advantageous in terms of better locking of the rotor shaft with the rotor core. Beneficially, the rotor core of the present disclosure is advantageous in terms of uniform torsional force distribution on the rotor shaft, thereby reducing stress concentrations and preventing the rotor shaft breakage during operation. Beneficially, the at least one protrusion of the rotor core and the at least one locking slit of the rotor shaft form a secure and reliable joint that prevents relative rotational movement between the rotor core and the rotor shaft.
Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
Figure 1 illustrates a front view of a rotor core of an electric motor, in accordance with an embodiment of the present disclosure.
Figure 2 illustrates an exploded view of a shaft and the rotor core of an electric motor, in accordance with an embodiment of the present disclosure.
Figure 3 illustrates an exploded view of a rotor assembly of an electric motor, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognise that other embodiments for carrying out or practising the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a rotor core and is not intended to represent the only forms that may be developed or utilised. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimised to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
As used herein, the terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings, and which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms “electric motor”, “motor”, “AC motor” are used interchangeably and refer to electric motors capable of being implemented in an industrial and automobile application for high torque operations. In general, the electric motor converts electrical energy into mechanical energy through the interaction of magnetic fields, typically involving a rotor and stator assembly. The electric motor may operate on various principles, including but not limited to induction, synchronous, or direct current (DC) mechanisms.
As used herein, the terms “rotor” and “rotor assembly” are used interchangeably and refer to the rotating part of the motor which converts electrical energy supplied to the stator into mechanical energy. The rotor assembly may contain permanent magnets and reluctance core that generate the magnetic field used to drive the rotor. The rotor assembly may generate magnetic torque, reluctance torque or a combination thereof.
As used herein, the terms “rotor shaft”, “motor shaft” and “shaft” are used interchangeably and refer to a power output mechanism of the motor, which transmits mechanical power to a load. The rotor shaft may be composed of various materials, including but not limited to steel, aluminium, or composite materials. The rotor shaft may incorporate design features to prevent misalignment during operation.
As used herein, the term "stator" and “stator assembly” as used herein, are used interchangeably and refers to the stationary component of an electric motor that houses the winding or permanent magnets and interacts with the rotor to create electromagnetic force or generate electrical power. The stator typically comprises a core made of laminated steel to reduce eddy current losses and may include slots or teeth to accommodate windings. The stator may also include insulation layers, cooling channels, and other structural features to enhance its mechanical robustness, thermal management, and electrical performance. While the stator is generally fixed in place, its design may allow for various mounting configurations and structural adaptations depending on the specific application of the motor.
As used herein, the terms “rotor core”, “rotor stack” and “stack” are used interchangeably and refers to the assembly of multiple laminated sheets or segments that collectively form the core structure of the rotor in an electric motor. The primary function of rotor core is to support the rotor magnets or windings and provide a path for magnetic flux to interact with the stator. Moreover, the rotor core facilitating the conversion of electrical energy into mechanical motion.
As used herein, the terms “at least one groove” and “groove” are used interchangeably and refer to the locking engagement inside a rotor core to engage the locking projection and facilitates the interlocking between the locking plate and the rotor core to secure the positions of rotor magnet.
As used herein, the terms “locking slit” and “at least one locking slit” are used interchangeably and refer to a narrow cut on the rotor shaft that engage with a complimentary design feature of the rotor core to interlock the rotor shaft and rotor core.
As used herein, the terms “protrusion” and “at least one protrusion” are used interchangeably and refer to a protruding (extending above surface) design feature of the rotor core extended along length of the shaft hole that engage with the locking slit of the rotor shaft to interlock the rotor shaft with the rotor core.
As used herein, the terms “rotor magnets”, “plurality of magnets”, and “magnets” are used interchangeably and refer to a permanent magnet present inside or on surface of the rotor core to generate magnetic field that interacts with the rotating magnetic field of the stator assembly resulting in rotational motion of the rotor.
As used herein, the terms “hollow cavities”, “plurality of hollow cavities” and “cavities” are used interchangeably and refer to hollow sections in the rotor core that are designed to accommodate the rotor magnets. The hollow cavities may be cut-through sections with both ends open. Alternatively, the hollow cavities may be closed at one end. It is to be understood that the plurality of the rotor magnets may be secured inside the hollow cavities by various means.
As used herein, the terms “locking plates” and “at least one locking plate” are used interchangeably and refer to disc like components of the rotor assembly that are placed on the ends of the rotor core to secure the plurality of the magnets inside the hollow cavities of the rotor core.
As used herein, the term “spacer spring” refers to a component of the rotor assembly that is designed to apply consistent axial force on the rotor stack, ensuring that the stack remains properly aligned and under the desired preload. Furthermore, the spacer spring compress or expand slightly, exerting force along the axis of the rotor assembly.
As used herein, the term “locking ring” refers to a component of the rotor assembly configured to secure the spacer spring on the rotor shaft. The locking ring may be a snap ring or may be a circlip.
As used herein, the term “shaft hole” refers to a cylindrical opening or bore within the rotor core, designed to accommodate the insertion of the rotor shaft inside the rotor core. The shaft hole is precisely machined to match the diameter of the shaft, ensuring a secure fit.
As used herein, the terms “locking projection” and “at least one locking projection” are used interchangeably and refer to a projection configured to secure the position of the locking plate on the rotor core. It is to be understood that the locking projection prevents slipping of the locking plate on the rotor core.
As used herein, the term “guiding slit” refers to a narrow, elongated cut or channel within the rotor core that serves as a pathway for alignment or positioning elements, such as keys, pins, or tabs. The guiding slit is formed by corresponding notch in plurality of electromagnetic sheets forming the rotor core.
As used herein, the term “guiding pin” refers to an alignment or positioning element used during the assembly of the core by stacking of the plurality of electromagnetic sheets. The guiding pin ensures proper alignment of the plurality of electromagnetic sheets with each other.
As used herein, the terms “rivet hole” and “plurality of rivet holes” are used interchangeably and refer to holes in the rotor core designed to accommodate a rivet to secure the stacked electromagnetic sheets forming the rotor core.
Figure 1, in accordance with an embodiment describes a rotor core 100 of an electric motor. The rotor core 100 is constructed by stacking multiple electromagnetic sheets. The rotor core 100 comprises a shaft hole 106 configured to receive a rotor shaft 202, at least one groove 108 in the shaft hole 106, and at least one protrusion 112 extended along the length of the shaft hole 106.
The present disclosure provides a rotor core 100 for electric motor. The rotor core 100 as disclosed by the present disclosure is advantageous in terms of providing enhanced magnetic efficiency and structural integrity due to specific construction. The shaft hole 106 of the rotor core 100 as disclosed by present disclosure is beneficially comprising at least one groove 108, to secure at least one locking plate 320a, 320b (as shown in Fig. 3) with the rotor core 100. Beneficially, the at least one locking plate 320a, 320b secures the plurality of rotor magnets 322 (as shown in Fig. 3) inside the rotor core 100 preventing any movement of the plurality of rotor magnets 322 during operation. The rotor core 100 as disclosed by the present disclosure beneficially comprises at least one protrusion 112 extended along the length of the shaft hole 106 to securely lock the rotor shaft 202 (as shown in Fig. 2) with the rotor core 100. Beneficially, the rotor core 100 as disclosed by the present disclosure is advantageous in terms of improved locking of the rotor shaft 202 with the rotor core 100. Beneficially, the rotor core 100 of the present disclosure is advantageous in terms of uniform torsional force distribution on the rotor shaft 202, thereby reducing stress concentrations and preventing breakage of the rotor shaft 202 during operation. Beneficially, the at least one protrusion 112 of the rotor core 100 and the at least one locking slit 216 (as shown in Fig. 2) of the rotor shaft 202 form a secure and reliable joint that prevents relative rotational movement between the rotor core 100 and the rotor shaft 202.
The rotor core 100 is constructed by stacking a plurality of electromagnetic sheets. In an embodiment, the plurality of electromagnetic sheets are laminated. Beneficially, the lamination process involves bonding the sheets together, which serves to minimize eddy current losses by increasing the electrical resistance between each layer. Moreover, this reduction in eddy current losses directly contributes to improved energy efficiency and reduced heat generation within the motor.
In an embodiment, at least one groove 108 is located on a cylindrical surface area of the shaft hole 106 and configured to receive at least one locking projection 318 of at least one locking plate 320a, 320b (as shown in Figure 3). Beneficially, the at least one groove 108 ensuring the secure attachment of the locking plates 320a, 320b within the rotor core 100.
In an embodiment, the at least one locking plate 320a, 320b is configured to lock a plurality of rotor magnets 322 inside the rotor core 100. Beneficially, the at least one locking plate 320a, 320b prevents any axial movement of the plurality of rotor magnets 322 inside the rotor core 100.
In an embodiment, the rotor core 100 comprises a plurality of hollow cavities 104 configured to receive the plurality of rotor magnets 322. Beneficially, the hollow cavities 104 are specifically configured to receive and securely house a plurality of rotor magnets 322 and are strategically positioned in the rotor core 100. The placement of said hollow cavities 104 is designed to optimize the magnetic interaction between the rotor core 100 and the stator, thereby improving the overall efficiency and torque production of the motor.
In an embodiment, the at least one protrusion 112 is configured to lock the rotor shaft 202 with the rotor core 100. Furthermore, in an embodiment, the rotor shaft 202 comprises at least one locking slit 216 configured to receive the at least one protrusion 112 to lock the rotor shaft 202 with the rotor core 100. Beneficially, the at least one protrusion 112 extends along the length of the shaft hole 106 and engages with at the least one locking slit 216 on the rotor shaft 202 to provide a robust locking mechanism. The at least one protrusion 112 ensures that the rotor shaft 202 and rotor core 100 remain firmly connected during operation and preventing any relative rotational movement. It is to be understood that the rotor shaft 202 and rotor core 100 are connected along the length of the rotor core 100 (due to the at least one protrusion 112) leading to uniform torsional force distribution on the rotor shaft 202, thereby reducing stress concentrations and preventing breakage of the rotor shaft 202 during operation. It is to be understood that the at least one locking slit 216 is precisely machined on the rotor shaft 202 to fit with the at least one protrusion 112 of the rotor core 100.
In an embodiment, a guiding slit 110 configured to receive a guiding pin during the stacking of the plurality of electromagnetic sheets forming the rotor core 100. It is to be understood that as the plurality of electromagnetic sheets are stacked to form the rotor core 100, the guiding pin is inserted into the guiding slit 110, ensuring precise alignment and positioning of the electromagnetic sheets with each other. Beneficially, the guiding slit 110 facilitates accurate and stable stacking of the electromagnetic sheets, preventing misalignment or shifting of the electromagnetic sheets with each other during manufacturing of the rotor core 100.
In an embodiment, the rotor core 100 comprises a plurality of rivet holes 114 configured to receive a plurality of rivets (not shown in Figures) to secure the stacked electromagnetic sheets forming the rotor core 100. Beneficially, the plurality of rivets are used to secure the stacked electromagnetic sheets with each other to form the rotor core 100. During the assembly process, rivets are inserted into the rivet holes 114 and deformed to fasten the sheets together, creating a stable and rigid core structure. Beneficially, the plurality of rivets ensure that the electromagnetic sheets are firmly held in place and preventing any movement or displacement that could affect the motor’s performance. Moreover, the use of rivets provides a strong mechanical joint between the sheets, contributing to the durability and structural integrity of the rotor core 100.
Figure 2, in accordance with an embodiment describes a rotor assembly 200 comprises a rotor core 100 and a rotor shaft 202 to form a functional unit within an electric motor. The rotor core 100 further comprises a central shaft hole 106 designed to accommodate the rotor shaft 202 for ensuring a precise fit and alignment. The shaft hole 106 incorporates at least one groove 108 along its cylindrical surface, which is designed to receive locking projections 318 (as shown in Figure 3) from locking plates 320a, 320b (as shown in Figure 3), thereby securing rotor magnets 322 (as shown in Figure 3) within the rotor core 100. Additionally, the rotor core 100 includes a protrusion 112 that extends along the length of the shaft hole 106, providing a mechanical interlock with corresponding locking features on the rotor shaft 202 to prevent rotational movement. The rotor core 100 is also equipped with hollow cavities 104 to house the rotor magnets 322, a guiding slit 110 for precise assembly alignment, and rivet holes 114 to secure the stacked electromagnetic sheets. The rotor shaft 202 comprises at least one locking slit 216, which engages with the protrusion 112 on the rotor core 100, ensuring a stable and rigid connection between the rotor shaft 202 and the rotor core 100.
Figure 3, in accordance with an embodiment describes a rotor assembly 300 of an electric motor. The rotor assembly 300 comprises a rotor shaft 202, a rotor core 100 and at least one spacer spring 324. The rotor core 100 is mounted on the rotor shaft 202. The rotor core 100 comprises a shaft hole 106 designed to accommodate the rotor shaft 202 securely, a groove 108, a protrusion 112, a rivet holes 114, hollow cavities 104 to accommodate a rotor magnet 322. The protrusion 112 coupled to a locking slit 216 of the rotor shaft 202 enhances the mechanical interlock between the rotor core 100 and the rotor shaft 202. The at least one spacer spring 324 is mounted on the rotor shaft 202 along with the rotor core 100. The spacer spring 324 is configured to restrict axial movement of the rotor core 100 on the rotor shaft 202. Additionally, the rotor assembly 300 comprises a locking plate 320a, 320b, a rotor magnet 322, at least one locking ring 326 configured to lock the at least one spacer spring 324 on the rotor shaft 202. The locking plates 320a, 320b is configured to lock the plurality of rotor magnets 322 placed in a plurality of a hollow cavities 104 inside the rotor core 100. The locking plates 320a, 320b prevent any rotational movement by engaging a locking projection 318 with the groove 108.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combination of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non- exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
,CLAIMS:We Claim:
1. A rotor core (100) constructed by stacking a plurality of electromagnetic sheets, wherein the rotor core (100) comprises:
- a shaft hole (106) configured to receive a rotor shaft (202);
- at least one groove (108) in the shaft hole (106); and
- at least one protrusion (112) extended along the length of the shaft hole (106).
2. The rotor core (100) as claimed in claim 1, wherein the plurality of electromagnetic sheets are laminated.
3. The rotor core (100) as claimed in claim 1, wherein the at least one groove (108) is located on a cylindrical surface area of the shaft hole (106) and configured to receive at least one locking projection (318) of at least one locking plate (320a, 320b).
4. The rotor core (100) as claimed in claim 3, wherein the at least one locking plate (320a, 320b) is configured to lock a plurality of rotor magnets (322) inside the rotor core (100).
5. The rotor core (100) as claimed in claim 1, wherein the rotor core (100) comprises a plurality of hollow cavities (104) configured to receive the plurality of rotor magnets (322).
6. The rotor core (100) as claimed in claim 1, wherein the at least one protrusion (112) is configured to lock the rotor shaft (202) with the rotor core (100).
7. The rotor core (100) as claimed in claim 6, wherein the rotor shaft (202) comprises at least one locking slit (216) configured to receive the at least one protrusion (112) to lock the rotor shaft (202) with the rotor core (100).
8. The rotor core (100) as claimed in claim 1, wherein the rotor core (100) comprises a guiding slit (110) configured to receive a guiding pin during the stacking of the plurality of electromagnetic sheets forming the rotor core (100).
9. The rotor core (100) as claimed in claim 1, wherein the rotor core (100) comprises a plurality of rivet holes (114) configured to receive a plurality of rivets to secure the stacked electromagnetic sheets forming the rotor core (100).
10. A rotor assembly (200), wherein the rotor assembly (200) comprises at least one of:
- a rotor shaft (202), and
- a rotor core (100) as claimed in claim 1