DESC:SEGMENTED STATOR ASSEMBLY
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202221062147 filed on 01/11/2022, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to an electric motor. Particularly, the present disclosure relates to a segmented stator assembly of the electric motor.
BACKGROUND
Most traditional motor stators are monolithic structures, with integrated stator yoke and stator tooth. Since the integrated stator structure remains fixed during the coil winding process, the slot utilization ratio is also very low in such motors. Further, in aforesaid structures, there lies a high chance of insulation breakdown during the coil winding process because of smaller openings at stator slots. Moreover, a rigid stator structure of the stator assembly makes it more prone to mechanical failures, such as cracking or deformation. Furthermore, such stator structures are difficult to maintain. Moreover, such stator structures are prone to vibrations causing low operational smoothness and higher noise levels.
Furthermore, the cogging torque is a common undesirable phenomenon in electric motors. The cogging torque is generated due to the interaction between the magnetic flux generated by the permanent magnets of the rotor and the magnetic flux generated by the stator coils. As the rotor rotates, the permanent magnets of the rotor attract and align with the stator teeth, creating a torque. This torque varies depending on the relative position of the rotor and the stator, resulting in a jerky motion.
With the development of motor technology, the stators have evolved with different types of structures such as linear type and block type to improve the winding efficiency and winding quality. However, in certain existing block-type stator structures, the stator teeth are only buckled and hence secured structure is difficult to achieve. The management of the uncontrolled buckling behavior of stator teeth requires precise control mechanisms, that are complex and costlier to implement. Moreover, design modifications, such as slot-less motor design, higher slot count, skewing of magnets, or lamination stack have been introduced in the stator structure to reduce the cogging torque. However, the design modifications have mechanical constraints and are not suitable for all end applications of the motor. Furthermore, the existing design modifications are not effective beyond a certain extent in mitigating the cogging torque.
Therefore, there exists a need for an improved stator structure that overcomes one or more problems associated as set forth above.
SUMMARY
An object of the present disclosure is to provide a stator structure for a motor capable of providing a flexible movement of a stator tooth.
In accordance with the first aspect of the present disclosure, there is provided a stator assembly for a motor comprising a stator yoke and a plurality of stator teeth. The stator yoke comprises a plurality of yoke knuckle eyes along a length of radially inward surface of the stator yoke. Each of the stator tooth comprises a tooth knuckle fork on a radially outward end. Each of the yoke knuckle eye is hinged together with the tooth knuckle fork to form the stator assembly.
The present disclosure provides an improved stator assembly for a motor. The stator assembly, as disclosed in the present disclosure, is advantageous in terms of enabling a limited movement of the stator tooth at a radially inward end. Advantageously, such movement of the stator tooth enables ease in winding the stator assembly. Advantageously, the stator assembly, as disclosed by the present disclosure, enables a higher stator fill factor compared to conventional stator assemblies. Furthermore, the stator assembly, as disclosed by the present disclosure, is advantageous in terms of reducing cogging torque in the motor.
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:
FIG. 1 illustrates an exploded view of a stator assembly for a motor, in accordance with an embodiment of the present disclosure.
FIG. 2a illustrates a cross-sectional view of the stator assembly, in accordance with an embodiment of the present disclosure.
FIG. 2b illustrates a perspective view of the stator tooth along with a coil, 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 recognize that other embodiments for carrying out or practicing 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 stator assembly for a motor and is not intended to represent the only forms that may be developed or utilized. 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 minimized 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.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, or 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 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” and “motor” are used interchangeably and refer to an electromagnetic machine that converts electrical energy into mechanical motion or rotation. The motor typically comprises a housing or frame, a stator element, and a rotor element. The stator contains coils, and the rotor is positioned within the stator. When electrical energy is supplied to the coils in the stator, a magnetic field is generated in the stator that interacts with the rotor causing the rotor to rotate which in turn rotates the shaft delivering mechanical power to a load.
As used herein, the terms “stator” and “stator assembly” are used interchangeably and refer to the stationary part of the electric motor that generates a magnetic field for driving the rotating armature. The stator acts as a field magnet. The design of the stator is an important factor in deciding the performance of the motor such as efficiency, power output, and torque generated in the motor.
As used herein, the terms “stator yoke” and “yoke” are used interchangeably and refer to a component of the stator assembly that provides structural support for stator teeth and completes the magnetic circuit of the stator. The stator yoke generally forms the outermost portion of the stator assembly. The stator yoke is typically constructed from a magnetic material such as steel, laminated iron, and/or soft magnetic composite material and may enhance the motor's magnetic circuit, influencing its overall performance, efficiency, and electromagnetic characteristics.
As used herein, the terms “yoke knuckle eyes”, “knuckle eyes” and “yoke eyes” are used interchangeably and refer to design elements present on the stator yoke forming an eye of a knuckle joint. The yoke knuckle eyes comprise holes to accommodate a fastener. The yoke knuckle eyes may be spaced on a radially inward surface of the stator yoke according to the dimensions of the stator teeth. Optionally, the yoke knuckle eyes may be evenly spaced on the radially inward surface of the stator yoke. The yoke knuckle eyes are hinged with tooth knuckle forks to form a knuckle joint between the stator yoke and the stator teeth.
As used herein, the term “radially inward surface” of the rotor refers to the innermost or inner-circumferential area of the stator yoke facing the rotor.
As used herein, the terms “stator tooth”, and “plurality of stator teeth” are used interchangeably and refer to a stator slot wedge that holds the conductive windings in the slot for producing an electromagnetic field in the stator. The stator tooth directs the magnetic field toward the rotor assembly to rotate the rotor assembly.
As used herein, the term “tooth knuckle fork” refers to a design element present on the stator tooth having a fork-like structure with two ends. The two ends of the tooth knuckle fork accommodate the yoke knuckle eye therebetween and accommodate a fastener through the holes present on the tooth knuckle fork to form knuckle joint between the stator yoke and stator teeth forming the stator assembly. The tooth knuckle fork is present on a radially outward end of the stator tooth.
As used herein, the term “radially outward end” of the stator tooth refers to the outermost extremity of the stator tooth facing the stator yoke.
As used herein, the terms “fastener” or “plurality of fasteners” are used interchangeably and refer to a fastening means accommodated in the yoke knuckle eyes and tooth knuckle forks for hinging them together forming the knuckle joint. The fastener is configured to allow axial movement of the stator tooth with respect to the stator yoke. The fastener may include any suitable pin, rivet, screw, bolt, and so forth.
As used herein, the term “knuckle pins” refers to specialized fasteners used in forming knuckle joints. The knuckle pins pass through the holes in the yoke knuckle eyes and tooth knuckle forks to hinge them together forming the knuckle joint. Furthermore, the knuckle pins allow for axial movement of the stator tooth with respect to the stator yoke.
As used herein, the term “radially inward end” refers to the innermost extremity of the stator tooth facing the rotor.
As used herein, the term “magnetic wedges”, “securing wedges” and “wedges” are used interchangeably and refer to wedges made up of magnetically permeable material such as iron or mild steel. The magnetic wedges are designed to restrict the rotational movement of the radially inward end of the stator teeth beyond a certain threshold. The magnetic wedges are designed, shaped, and sized in conformation with side gaps in between the stator yoke and the stator teeth.
Figure 1, in accordance with an embodiment, describes a stator assembly 100 for a motor comprising a stator yoke 102 and a plurality of stator teeth 108. The stator yoke 102 comprises a plurality of yoke knuckle eyes 104 along a length of radially inward surface 106 of the stator yoke 102. Each of the stator tooth 108 comprises a tooth knuckle fork 110 on a radially outward end 112. Each of the yoke knuckle eye 104 is hinged together with the tooth knuckle fork 110 to form the stator assembly 100.
The present disclosure provides an improved stator assembly 100 for a motor. The stator assembly 100 is advantageous in terms of enabling a limited movement of the stator tooth 108 at a radially inward end 116. Advantageously, such movement of the stator tooth 108 enables ease in winding the stator assembly 100. Beneficially, during the winding process, a slot opening formed by the adjacent stator teeth 108 may be widened to enable ease of winding. Advantageously, the stator assembly 100 enables a higher stator fill factor compared to conventional stator assemblies. Furthermore, the stator assembly 100 is advantageous in terms of reducing cogging torque in the motor. The stator assembly 100 is provided with movement of the stator tooth 108 at a radially inward end 116, thus, during the operation of the motor, the plurality of stator teeth 108 are able to exhibit oscillatory rotational movement due to the knuckle joint formed at junction of the stator tooth 108 stator yoke 102 resulting in reduction of the cogging torque as permanent magnets of rotor does not completely align with the stator tooth 108. Beneficially, the oscillatory rotational movement of the plurality of stator teeth 108 is controlled to prevent physical contact of adjacent stator tooth 108.
In an embodiment, the stator assembly 100 comprises a plurality of fasteners 114 configured to hinge each of the yoke knuckle eye 104 with the tooth knuckle fork 110. It is to be understood that the plurality of fasteners 114 are designed to facilitate the formation of knuckle joints and enable a relative movement of the tooth knuckle fork 110 with respect to the yoke knuckle eye 104. Beneficially, the plurality of fasteners 114 are made of a material suitable for handling mechanical stress. More beneficially, the plurality of fasteners 114 are designed to fit in the knuckle joint and stay in place even during the high vibrations in the knuckle joint formed by the yoke knuckle eye 104 with the tooth knuckle fork 110.
In an embodiment, each of the fastener 114 passes through the yoke knuckle eye 104 and the tooth knuckle fork 110 to hinge them together. It is to be understood that the yoke knuckle eye 104 and the tooth knuckle fork 110 comprise holes aligned with each other such that once the tooth knuckle fork 110 is accommodated over the yoke knuckle eye 104, the holes of the yoke knuckle eye 104 and the tooth knuckle fork 110 form a straight hollow cavity for accommodating the fastener 114. Beneficially, the fastener 114 is secured in the yoke knuckle eye 104 and the tooth knuckle fork 110. In a specific embodiment, the plurality of fasteners 114 are knuckle pins. Alternatively, the plurality of fasteners 114 are any suitable fastening means.
In an embodiment, each of the stator tooth 108 is rotationally moveable at a radially inward end 116 along an axis of the yoke knuckle eye 104. It is to be understood that the formed knuckle joint between the yoke knuckle eye 104 and the stator tooth 108 enables rotational movement of the stator tooth 108. Beneficially, such rotational movement facilitates the easier winding of the stator assembly 100, as the stator tooth 108 may be moved to widen the slot opening during the winding of the stator assembly 100.
In an embodiment, the stator assembly 100 comprises a plurality of magnetic wedges 118a,118b, inserted mutually opposite along each of the tooth knuckle fork 110. It is to be understood that magnetic wedges 118a,118b are provided along each physical contact of the stator tooth with the stator yoke to restrict rotational movement of the stator tooth 108 beyond a threshold degree. Beneficially, the plurality of magnetic wedges 118a,118b are inserted along the gap between the tooth knuckle fork 110 and stator yoke 102.
In an embodiment, the plurality of magnetic wedges 118a,118b are fixed on the radially inward surface 106 of the stator yoke 102. Beneficially, the plurality of magnetic wedges 118a,118b are fixed on the radially inward surface 106 of the stator yoke 102 using a suitable fixing means that securely fix the plurality of magnetic wedges 118a,118b and prevents dislocation of the plurality of magnetic wedges 118a,118b during the operation of the motor.
In an embodiment, the plurality of magnetic wedges 118a,118b are configured to restrict the rotational movement of each of the stator tooth 108 beyond a predefined degrees to avoid physical contact between the radially inward ends 116 of two adjacent stator teeth 108. Beneficially, the plurality of magnetic wedges 118a,118b are designed, shaped, and sized accordingly.
It is to be understood that during the operation of the motor, the combination of the knuckle joint formed between the yoke knuckle eye 104 and the tooth knuckle fork 110, and the plurality of magnetic wedges 118a,118b allows oscillating rotational movement of each of the stator tooth 108 at the radially inward end 116 along the axis of the yoke knuckle eye 104 that reduces alignment of the permanent magnets of the rotor with the stator tooth 108 resulting in reduction of cogging torque. Beneficially, the plurality of magnetic wedges 118a,118b ensures that the stator tooth 108 does not move beyond a certain limit, maintaining the structural and operational integrity of the motor.
Figure 2a, in accordance with an embodiment, describes a cross-sectional view of the stator assembly 100. The stator assembly 100 comprises the stator yoke 102 and the plurality of stator teeth 108. The stator yoke 102 comprises the plurality of yoke knuckle eyes 104 along the length of radially inward surface 106 of the stator yoke 102. Each of the stator tooth 108 comprises the tooth knuckle fork 110 on the radially outward end 112. Each of the yoke knuckle eye 104 is hinged together with the tooth knuckle fork 110 to form the stator assembly 100. Furthermore, the stator assembly 100 comprises a plurality of fasteners 114 configured to hinge each of the yoke knuckle eye 104 with the tooth knuckle fork 110. Furthermore, each of the fastener 114 passes through the yoke knuckle eye 104 and the tooth knuckle fork 110 to hinge them together. Preferably, the plurality of fasteners 114 are knuckle pins. Furthermore, each of the stator tooth 108 is rotationally moveable at a radially inward end 116 along an axis of the yoke knuckle eye 104. Furthermore, the stator assembly 100 comprises a plurality of magnetic wedges 118a,118b, inserted mutually opposite along each of the tooth knuckle fork 110. Furthermore, the plurality of magnetic wedges 118a,118b are fixed on the radially inward surface 106 of the stator yoke 102. Furthermore, the plurality of magnetic wedges 118a,118b are configured to restrict the rotational movement of each of the stator tooth 108 beyond a predefined degrees to avoid physical contact between the radially inward ends 116 of two adjacent stator teeth 108.
Figure 2b, in accordance with an embodiment, describes a stator tooth 108 along with a coil. The stator tooth 108 comprises a coil wound around the stator tooth 108. The coil generates a magnetic flux in the stator tooth 108 when a current passes through the coil. The generated magnetic flux is guided by the stator tooth 108 towards the rotor assembly to rotate the rotor. It is to be understood the coil may be wound around the stator tooth 108 with a bobbin. Alternatively, the coil may be wound around the stator tooth 108 without the bobbin using any other suitable form of insulation.
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 combinations 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”, and “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 stator assembly (100) for a motor, the stator assembly (100) comprises:
- a stator yoke (102) comprising a plurality of yoke knuckle eyes (104) along a length of radially inward surface (106) of the stator yoke (102); and
- a plurality of stator teeth (108), wherein each of the stator tooth (108) comprises a tooth knuckle fork (110) on a radially outward end (112);
wherein each of the yoke knuckle eye (104) is hinged together with the tooth knuckle fork (110) to form the stator assembly (100).
2. The stator assembly (100) as claimed in claim 1, wherein the stator assembly (100) comprises a plurality of fasteners (114) configured to hinge each of the yoke knuckle eye (104) with the tooth knuckle fork (110).
3. The stator assembly (100) as claimed in claim 2, wherein each of the fastener (114) passes through the yoke knuckle eye (104) and the tooth knuckle fork (110) to hinge them together.
4. The stator assembly (100) as claimed in claim 2, wherein the plurality of fasteners (114) are knuckle pins.
5. The stator assembly (100) as claimed in claim 1, wherein each of the stator tooth (108) is rotationally moveable at a radially inward end (116) along an axis of the yoke knuckle eye (104).
6. The stator assembly (100) as claimed in claim 1, wherein the stator assembly (100) comprises a plurality of magnetic wedges (118a,118b), inserted mutually opposite along each of the tooth knuckle fork (110).
7. The stator assembly (100) as claimed in claim 6, wherein the plurality of magnetic wedges (118a,118b) are fixed on the radially inward surface (106) of the stator yoke (102).
8. The stator assembly (100) as claimed in claim 6, wherein the plurality of magnetic wedges (118a,118b) are configured to restrict the rotational movement of each of the stator tooth (108) beyond a predefined degrees to avoid physical contact between the radially inward ends (116) of two adjacent stator teeth (108).