DESC:SYSTEM FOR MONITORING ROTOR TEMPERATURE
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202221075287 filed on 25/12/2022, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to a rotor assembly of an electric motor. Particularly, the present disclosure relates to a rotor assembly of an electric motor with temperature monitoring. Furthermore, the present disclosure relates to a system for monitoring the temperature of a rotor assembly.
BACKGROUND
The electric motors have been gaining traction in various applications including mobility. The electric motors convert the electric energy into mechanical energy to drive a load. The electric motors are versatile and are suitable for various applications as the electric motors are capable of utilizing energy from clean sources to deliver mechanical power output.
Generally, it is well-known that the electric motor consists of a stator and a rotor. The stator is a fixed portion of the motor, including an iron core that supports a current-flowing coil and a frame to which the iron core is attached. The rotor is a rotatable portion of the motor, including a permanent magnet and an iron core. The motor has different output and control performances as the characteristics of the permanent magnets embedded within the rotor are varied. However, the electric motors produce heat during operation due to various losses. The heat produced during the operation of the motor affects the performance of the motor.
It is well known that the magnetic flux of the permanent magnets decreases as temperature increases, thereby resulting in a decreased output of the motor. Thus, it is important to maintain an optimum temperature inside the motor for optimal performance of the motor.
Presently, a temperature sensor is attached to a stator coil to detect the temperature of a stator and the detected temperature of the stator is used to monitor the temperature of a motor. However, the temperature of the rotor plays a critical role in the performance of the rotor rather than the temperature of the stator. The existing methodologies of detecting temperature at the stator rather than the temperature are inadequate in determining accurate temperatures at the permanent magnets. Presently, it is difficult to measure accurate rotor temperature as it is difficult to attach a temperature sensor to the rotor assembly due to the rotation of the rotor assembly.
Therefore, there exists a need for an improved rotor design with temperature monitoring that overcomes one or more problems associated as set forth above.
SUMMARY
An object of the present disclosure is to provide a rotor assembly for an electric motor with temperature monitoring.
Another object of the present disclosure is to provide a system for monitoring the temperature of a rotor assembly.
In accordance with an aspect of the present disclosure, there is provided a rotor assembly for an electric motor. The rotor assembly comprises a rotor shaft, a rotor stack mounted on the rotor shaft, at least one temperature sensor mounted on the rotor stack, a pair of slip rings connected to the at least one temperature sensor, and a pair of carbon brushes connected to the slip rings. The at least one temperature sensor mounted on the rotor stack senses a rotor temperature and the sensed rotor temperature signal is transmitted via combination of the pair of slip rings and the carbon brushes during the operation of the rotor assembly.
The present disclosure provides a rotor assembly for an electric motor. Beneficially, the rotor assembly as disclosed by the present disclosure is advantageous in terms of accurately measuring the rotor temperature. Beneficially, the rotor assembly of the present disclosure is advantageous in terms of continuously monitoring the temperature of the rotor stack and the permanent magnets. Beneficially, the rotor assembly of the present disclosure is advantageous in terms of delivering optimal power output. Beneficially, the rotor assembly of the present disclosure is advantageous in terms of maximum utilization of the flux generated by the permanent magnets of the rotor assembly.
In accordance with second aspect of the present disclosure, there is provided a system for monitoring temperature of a rotor assembly. The system comprises at least one temperature sensor mounted on a rotor stack, a pair of slip rings connected to the at least one temperature sensor, and a pair of carbon brushes connected to the slip rings. The at least one temperature sensor mounted on the rotor stack senses a rotor temperature and the sensed rotor temperature signal is transmitted via combination of the pair of slip rings and the carbon brushes during the operation of the rotor assembly.
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 an exploded view of a rotor assembly for an electric motor, in accordance with an embodiment of the present disclosure.
Figure 2 illustrates a perspective view of the rotor assembly for 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 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 a rotor assembly for an electric 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”, “motor”, “surface permanent magnet motor”, “SPM motor”, “permanent magnet motor”, “permanent magnet synchronous reluctance motor” and “PMSRM” are used interchangeably and refer to type of electric motor in which the permanent magnets are attached to the surface of the rotor, in a radial or axial arrangement. The magnets generate a magnetic field that interacts with the magnetic flux generated by the stator windings to produce the rotational motion of the rotor. The permanent magnet motor has high efficiency, and compact design and is suitable for applications such as electric vehicles (EVs) and robotics.
As used herein, “rotor” and “rotor assembly” are used interchangeably and refer to the rotating part of the electric motor that generates a magnetic field through permanent magnets, for interacting with the stator’s magnetic field for the generation of the torque on the rotor. The rotor serves as the structural support for the permanent magnets and provides a path for the magnetic flux to circulate within the rotor. The rotor core is often made of ferromagnetic materials like laminated iron or steel sheets. These materials have high magnetic permeability, which helps concentrate and direct the magnetic field. The physical dimensions of the rotor, including diameter and length, physical size determine the power output of the motor.
As used herein, the term “rotor stack” refers to the central component of the rotor that supports and houses the permanent magnets. The rotor core is typically made from a magnetic material, such as laminated iron or steel to concentrate and direct the magnetic flux generated by the magnets.
As used herein, the terms “permanent magnet” and “magnet” are used interchangeably and refer to pieces of permanent magnets held in the curved surface of the rotor’s core to generate constant magnetic flux in the rotor for interaction with the magnetic field of the stator. The magnets are typically made from materials with strong magnetic properties, such as neodymium-iron-boron (NdFeB) or samarium-cobalt (SmCo).
As used herein, the term “rotor shaft”, “shaft” and “shaft assembly” are used interchangeably and refer to a cylindrical rotating component for delivering mechanical output.
As used herein, the term “temperature sensor” refers to a device that detects and measures temperature. The temperature sensor senses the temperature and converts the sensed information into an electrical signal so the same can be transferred to other electronic devices. The temperature sensor may include at least one of: thermistors, resistance temperature detector, thermocouples, and infrared sensors.
As used herein, the term “slip ring” refers to an electromechanical device that enables the transmission of power and electrical signals from a stationary to a rotating structure or vice-versa within an electric motor.
As used herein, the term “carbon brushes” refers to carbon or graphite blocks that are held stationary and pressed against the metal rings, creating electrical contact. The carbon brushes comprise springs to maintain a consistent pressure between the brushes and slip rings, ensuring continuous contact.
As used herein, the term “connecting wires” refers to wires that transmit electrical signals from the temperature sensor to the slip ring.
As used herein, the term “insulating ring” refers to a ring of insulating material fixed between the adjacent slip rings to create electrical insulation between the adjacent slip rings.
As used herein, the term “slit” refers to a cut or vacant space on the surface of the rotor shaft. A similar slit is also present on the inner surface of the rotor stack.
As used herein, the term “rotor key” refers to a metal strip that is inserted inside the slit present on the rotor shaft and rotor stack to fix them together to prevent any circular slipping of the rotor stack on the rotor shaft.
As used herein, the term “circlip” refers to a fastener used to secure the rotor stack on the rotor shaft. The circlip prevents the axial movement of the rotor stack on the rotor shaft.
Figure 1, in accordance with an embodiment, describes an exploded view of a rotor assembly 100 for an electric motor. The rotor assembly 100 comprises a rotor shaft 102, a rotor stack 104 mounted on the rotor shaft 102, at least one temperature sensor 106 mounted on the rotor stack 104, a pair of slip rings 108 connected to the at least one temperature sensor 106, and a pair of carbon brushes 110 connected to the slip rings 108. The at least one temperature sensor 106 mounted on the rotor stack 104 senses a rotor temperature and the sensed rotor temperature signal is transmitted via combination of the pair of slip rings 108 and the carbon brushes 110 during the operation of the rotor assembly 100.
The present disclosure provides a rotor assembly 100 for an electric motor. Beneficially, the rotor assembly 100 is advantageous in terms of accurately measuring the rotor temperature. Beneficially, the rotor assembly 100 is advantageous in terms of continuously monitoring the temperature of the rotor stack 104 and the permanent magnets 114. Beneficially, the rotor assembly 100 is advantageous in terms of delivering optimal power output. Beneficially, the rotor assembly 100 is advantageous in terms of maximum utilization of the flux generated by the permanent magnets 114 of the rotor assembly 100.
In an embodiment, the rotor assembly 100 comprises connecting wires 112 to connect the at least one temperature sensor 106 and the pair of slip rings 108. Beneficially, the connecting wires 112 provide passage for the sensed rotor temperature signal between the at least one temperature sensor 106 and the pair of slip rings 108. It is to be understood that the sensed rotor temperature signal travels to the pair of slip rings 108 through the connecting wires.
In an embodiment, the rotor assembly 100 comprises a plurality of permanent magnets 114 mounted on the rotor stack 104. Beneficially, the plurality of permanent magnets 114 mounted on the rotor stack 104 generates a magnetic field that interacts with a field generated by the stator coils for the rotation of the rotor assembly 100.
In an embodiment, the rotor assembly 100 comprises an insulating ring 116 mounted on the rotor shaft 102 between the slip rings 108. Beneficially, the insulating ring 116 creates electrical insulation between the adjacent slip rings 108 mounted on the rotor shaft 102.
In an embodiment, the rotor shaft 102 and the rotor stack 104 comprise a slit 102a, and wherein a rotor key 104a is inserted inside the slit 102a to fix the rotor stack 104 on the rotor shaft 102. It is to be understood that rotor shaft 102 and the rotor stack 104 comprise a slit 102a are align with each other and the rotor key 104a is inserted inside the slit 102a to fix the rotor stack 104 on the rotor shaft 102. Beneficially, the rotor key 104a after inserted in the slit 102a prevents the slipping of the rotor stack 104 on the rotor shaft 102 during the operation of the rotor assembly 100.
In an embodiment, the rotor assembly 100 comprises at least one circlip 118 to lock the rotor stack 104 on the rotor shaft 102. Beneficially, the at least one circlip 118 prevents an axial movement of the rotor stack 104 on the rotor shaft 102 during the operation of the rotor assembly 100.
In an embodiment, the sensed rotor temperature signal is transmitted to the pair of slip rings 108 via the connecting wires 112 during the operation of the rotor assembly 100. It is to be understood that the sensed rotor temperature signal in the form of electrical signal travels through the connecting wires 112 to reach the pair of slip rings 108.
In an embodiment, the sensed rotor temperature signal is transmitted from the pair of slip rings 108 to the pair of carbon brushes 110 due to constant physical contact between the pair of slip rings 108 and the pair of carbon brushes 110 during the operation of the rotor assembly 100. It is to be understood that the sensed rotor temperature signal in the form of electrical signal travels through the pair of slip rings 108 and the pair of carbon brushes 110 during the operation of the rotor assembly 100.
In an embodiment, the sensed rotor temperature signal received from the pair of carbon brushes 110 is utilized to monitor the rotor temperature during the operation of the rotor assembly 100. Beneficially, the pair of carbon brushes 110 enable constant monitoring of the temperature of the rotor assembly 100 during the operation of the same.
Figure 2, in accordance with an embodiment, describes a perspective view of the rotor assembly 100. The rotor assembly 100 comprises a rotor shaft 102, a rotor stack 104 mounted on the rotor shaft 102, at least one temperature sensor 106 mounted on the rotor stack 104, a pair of slip rings 108 connected to the at least one temperature sensor 106, and a pair of carbon brushes 110 connected to the slip rings 108. The at least one temperature sensor 106 mounted on the rotor stack 104 senses a rotor temperature and the sensed rotor temperature signal is transmitted via combination of the pair of slip rings 108 and the carbon brushes 110 during the operation of the rotor assembly 100. Furthermore, the rotor assembly 100 comprises connecting wires 112 to connect the at least one temperature sensor 106 and the pair of slip rings 108. Furthermore, the rotor assembly 100 comprises a plurality of permanent magnets 114 mounted on the rotor stack 104. Furthermore, the rotor assembly 100 comprises an insulating ring 116 mounted on the rotor shaft 102 between the slip rings 108. Furthermore, the rotor shaft 102 and the rotor stack 104 comprise a slit 102a, and wherein a rotor key 104a is inserted inside the slit 102a to fix the rotor stack 104 on the rotor shaft 102. Furthermore, the rotor assembly 100 comprises the at least one circlip 118 to lock the rotor stack 104 on the rotor shaft 102. Furthermore, the sensed rotor temperature signal is transmitted to the pair of slip rings 108 via the connecting wires 112 during the operation of the rotor assembly 100. Furthermore, the sensed rotor temperature signal is transmitted from the pair of slip rings 108 to the pair of carbon brushes 110 due to constant physical contact between the pair of slip rings 108 and the pair of carbon brushes 110 during the operation of the rotor assembly 100. Furthermore, the sensed rotor temperature signal received from the pair of carbon brushes 110 is utilized to monitor the rotor temperature during the operation of the rotor assembly 100.
In accordance with second aspect, the present disclosure describes a system for monitoring temperature of a rotor assembly 100. The system comprises at least one temperature sensor 106 mounted on a rotor stack 104, a pair of slip rings 108 connected to the at least one temperature sensor 106, a pair of carbon brushes 110 connected to the slip rings 108. The at least one temperature sensor 106 mounted on the rotor stack 104 senses a rotor temperature and the sensed rotor temperature signal is transmitted via combination of the pair of slip rings 108 and the carbon brushes 110 during the operation of the rotor assembly 100.
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 rotor assembly (100) for an electric motor, wherein the rotor assembly (100) comprises:
- a rotor shaft (102);
- a rotor stack (104) mounted on the rotor shaft (102);
- at least one temperature sensor (106) mounted on the rotor stack (104);
- a pair of slip rings (108), connected to the at least one temperature sensor (106); and
- a pair of carbon brushes (110), connected to the slip rings (108),
wherein the at least one temperature sensor (106) mounted on the rotor stack (104) senses a rotor temperature and the sensed rotor temperature signal is transmitted via combination of the pair of slip rings (108) and the carbon brushes (110) during the operation of the rotor assembly (100).
2. The rotor assembly (100) as claimed in claim 1, wherein the rotor assembly (100) comprises connecting wires (112) to connect the at least one temperature sensor (106) and the pair of slip rings (108).
3. The rotor assembly (100) as claimed in claim 1, wherein the rotor assembly (100) comprises a plurality of permanent magnets (114) mounted on the rotor stack (104).
4. The rotor assembly (100) as claimed in claim 1, wherein the rotor assembly (100) comprises an insulating ring (116) mounted on the rotor shaft (102) between the slip rings (108).
5. The rotor assembly (100) as claimed in claim 1, wherein the rotor shaft (102) and the rotor stack (104) comprise a slit (102a), and wherein a rotor key (104a) is inserted inside the slit (102a) to fix the rotor stack (104) on the rotor shaft (102).
6. The rotor assembly (100) as claimed in claim 1, wherein the rotor assembly (100) comprises at least one circlip (118) to lock the rotor stack (104) on the rotor shaft (102).
7. The rotor assembly (100) as claimed in claim 1, wherein the sensed rotor temperature signal is transmitted to the pair of slip rings (108) via the connecting wires (112) during the operation of the rotor assembly (100).
8. The rotor assembly (100) as claimed in claim 1, wherein the sensed rotor temperature signal is transmitted from the pair of slip rings (108) to the pair of carbon brushes (110) due to constant physical contact between the pair of slip rings (108) and the pair of carbon brushes (110) during the operation of the rotor assembly (100).
9. The rotor assembly (100) as claimed in claim 1, wherein the sensed rotor temperature signal received from the pair of carbon brushes (110) is utilized to monitor the rotor temperature during the operation of the rotor assembly (100).
10. A system for monitoring temperature of a rotor assembly (100), wherein the system comprises:
- at least one temperature sensor (106) mounted on a rotor stack (104);
- a pair of slip rings (108), connected to the at least one temperature sensor (106); and
- a pair of carbon brushes (110), connected to the slip rings (108),
wherein the at least one temperature sensor (106) mounted on the rotor stack (104) senses a rotor temperature and the sensed rotor temperature signal is transmitted via combination of the pair of slip rings (108) and the carbon brushes (110) during the operation of the rotor assembly (100).