Claims:1. An electrical machine (100) comprising: a stator (205) fixedly attached to a housing member (101), a rotor (204) rotatably attached to a shaft member (403), said shaft member (403) being held by said housing member (101), said stator (205) comprises a plurality of teeth and one or more windings wound on said plurality of teeth, said rotor (204) comprises plurality of magnets disposed circumferentially along an inner circumference (303)of said rotor (204), said plurality of magnets are disposed adjoining said plurality of teeth of said stator (205), and a noise damping member (402) disposed circumferentially around said shaft member (403), wherein said noise damping member (402) is sandwiched between said stator (205) and said housing member (101).
2. An electrical machine (100) comprising: a stator (205) fixedly attached to a housing member (101), a rotor (204) rotatably attached to a shaft member (403), said shaft member (403) being held by said housing member (101), said stator (205) comprises a plurality of teeth and one or more windings wound on said plurality of teeth, said rotor (204) comprises an outer surface (204AA), said outer surface (204AA) comprising an outer cylindrical member (301) and an inner cylindrical member (302), and a plurality of magnets disposed circumferentially along an inner circumference (303) of said outer cylindrical member (301) of said rotor (204), said plurality of magnets are disposed adjoining said plurality of teeth of said stator (205), and said inner cylindrical member (302) mounted on said shaft member (403), wherein said outer surface (204AA) comprises one or more openings (201) disposed circumferentially along said outer surface (204AA).
3. The electrical machine (100) as claimed in claim 2, wherein said outer surface (204AA) of said rotor (204) comprises one or more first set of openings (202) provided circumferentially between said one or more openings (201).
4. The electrical machine (100) as claimed in claim 2, wherein said outer surface (204AA) of said rotor (204) comprises one or more second set of openings (203) provided circumferentially at radial distance lower than the radial distance of said one or more first set of openings (202), wherein said second set of openings (203) are capable of mounting a fan (401).
5. The electrical machine (100) as claimed in claim 1, wherein said noise damping member (402) comprises a plurality of openings.
6. The The electrical machine (100) as claimed in claim 1, wherein said noise damping member (402) is an elastic member.
7. The electrical machine (100) as claimed in claim 1, wherein said noise damping member (402) comprises one or more projections (501).
8. The electrical machine (100) as claimed in claim 1 or 7, wherein said one or more projections are capable of extending in a gap formed between said plurality of teeth of said stator (205).
9. The electrical machine (100) as claimed in claim 1, wherein said noise damping member (402) comprises one or more stepped surfaces (502) for allowing lateral routing of wires (601) extending out of said one or more windings.
10. An electrical machine (100) comprising: a stator (205) fixedly attached to a housing member (101), a rotor (204) rotatably attached to a shaft member (403), said shaft member (403) being held by said housing member (101), said stator (205) comprises a plurality of teeth and one or more windings wound on said plurality of teeth, said rotor (204) comprises an outer surface (204AA), said outer surface (204AA) comprising an outer cylindrical member (301) and an inner cylindrical member (302), and a plurality of magnets disposed circumferentially along an inner circumference (303) of said outer cylindrical member (301) of said rotor (204), said plurality of magnets are disposed adjoining said plurality of teeth of said stator (205), and said inner cylindrical member (302) mounted on said shaft member (403), wherein said outer surface (204AA) comprises one or more openings (201) disposed circumferentially along said outer surface (204AA), and a noise damping member (402) disposed circumferentially around said shaft member (403), wherein said noise damping member (402) is elastically sandwiched mounted between said stator (205) and said housing member (101).
11. A noise dampening member (402) comprising:
one or more projections (501) capable of engaging with the gaps of teeth of a stator (205);
and one or more stepped surfaces (502) for allowing routing of wires (601) extending out of one or more windings of teeth of the stator (205).
12. A method of noise dampening in an electrical machine (100) comprising steps of:
creating a plurality of openings (201) on a rotor (204);
creating a first set of openings (202) on said rotor (202);
creating a second set of openings (203) on said rotor (204); and
disposing a noise damping member (402) in between a stator (205) and any fixed surface. , Description:TECHNICAL FIELD
[0001] The present subject matter relates generally to an electrical machine of a vehicle. More particularly but not exclusively, the present subject matter relates to noise damping of the electrical machine of the vehicle.
BACKGROUND
[0002] Typically, a vehicle has an electrical machine coupled to an engine. The electrical machine produces electrical energy from mechanical energy for charging batteries and operating other electrical systems when an engine is in operation. The electrical machine comprises primarily of two members: a stator, and a rotor. The rotor is a rotating part while the stator is a stationary part. The rotor is connected to a shaft whereas the stator is housed in a crankcase. The rotor is also fitted with a fan that rotates along with the rotor. The rotor contains a plurality of magnets and the stator contains stacks with slits and windings. The stacks in the stator are usually made up of ferromagnetic material. When the electrical machine is in operation, the rotor rotates along with the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The same numbers are used throughout the drawings to refer to similar features and components.
[0004] Figure 1 exemplarily illustrates a cross-sectional view of a conventional electrical machine in accordance with one or more implementation.
[0005] Figure 2 exemplarily illustrates a perspective view of the electrical machine in accordance with one or more implementation.
[0006] Figure 3 exemplarily illustrates a perspective view of a rotor in accordance with one or more implementation
[0007] Figure 4 exemplarily illustrates an exploded view of an electrical machine in accordance with one or more implementation
[0008] Figure 5 exemplarily illustrates a perspective view of a noise damping member in accordance with one or more implementation
[0009] Figure 6 exemplarily illustrates a side view of the electrical machine in accordance with one or more implementation
[00010] Figure 7-Figure 10 exemplarily illustrates statistical data of noise dampening at various conditions in accordance with one or more implementation
[00011] Figure 11 exemplarily illustrates a method flowchart of dampening noise in accordance with one or more implementation.
DETAILED DESCRIPTION
[00012] An electrical machine of a vehicle comprising of a stator and a rotor constitutes primarily of two materials, the stator made up of ferromagnetic material and the rotor having a plurality of magnets. The rotation of the rotor along with a shaft effectuates a fluctuating magnetic field in the stator enabling the electrical machine to run as a motor or a generator based on need. Moreover, the rotor and the stator experiences continuous vibration while the generator is in operation. Furthermore, with technological advancements, there is an increase in demand for power, which requires bigger electrical machines which means a bigger size of the stator and the rotor. The fluctuating magnetic field in the stator and the vibration of the rotor produces a humming noise.
[00013] It has been conceived conventionally that the stator is mounted on a metal plate to dampen the noise. However, such a method of preventing vibration of the stator adds more weight to the vehicle, and also includes the complexity of mounting the stator on the metal plate, which increases the size of the engine in the width direction of the vehicle.
[00014] In yet another known art with a conventional electric machine, the flow of air is restricted by placing shields at the sides of the stator such that the vibration of air molecules is restricted. However, such a system increases the number of child parts and adds to the overall weight of the vehicle.
[00015] In yet another known art with a conventional electrical machine, the stator is fitted with a piezoelectric actuator, to prevent the deformation caused by the fluctuating magnetic field on the stator and vibration of the rotor. However, such a method increases cost and requires additional power and control device for controlling the piezoelectric material.
[00016] It has also been conceived in a known art that to control the humming sound from the vibration of the rotor, the resonance frequency of the rotor has been shifted. But, shifting of resonance frequency works only wherein the operating frequency is fixed. But the engine of a vehicle may operate throughout a wide range of frequency. Thus, such a method of shifting resonance frequency may not work at all the time. Also, there are various mounting mechanisms of the rotor on the engine to prevent vibration. But, such a method involves a complex mounting mechanism and high cost.
[00017] Since the rotor has a plurality of magnets and the stator is made up of ferromagnetic material, during the rotation of the rotor with the shaft, the stator experiences magnetic field fluctuations. This fluctuating magnetic field applies a magnetostriction force on the stator. The magnetostriction force changes the shape and dimension of the stator, i.e the stator undergoes torsion and bending mode due to which the stator body gets deformed. The torsion and bending mode can also be produced by the vibration generated by the engine or magnetic interaction between the stator and the rotor. The torsion and bending mode causes vibration in the stator and other supporting structural members which in turn excites nearby air molecules and creates noise or a low pitched humming sound. This noise affects the sound quality of the vehicle and gives an unpleasant experience to a user.
[00018] Additionally, for other reasons not limited to magnetic interaction between the stator and the rotor, vibration from the engine and its associated parts are transmitted to the rotor, due to which the rotor outer face perpendicular to the axis of the rotor deforms. The deformed outer face excites the nearby air molecules which further adds to the humming noise produced by the stator. Besides, there is a challenge of limited space which restricts making any configuration modifications that can effectively diminish humming noise created by the deformities of the stator and the rotor.
[00019] Therefore, there exists a need to effectively diminish the humming sound from the electrical machine by a system that is simple, easy to manufacture, economically efficient, space-efficient, lightweight, compliant with the existing system configurations, and which can effectively overcome all other challenges as well as shortcomings of known prior arts.
[00020] An objective of the present invention is to provide an electrical machine which is simple, easy to manufacture, economical, space-efficient, lightweight and does not require significant change in the existing system configurations for diminishing the humming noise from the generator. The claimed subject matter applies to any type of vehicle, with required changes and without deviating from the scope of the invention.
[00021] As per an aspect of the present invention, the electrical machine disclosed comprises of the stator being fixedly attached to the housing member, the rotor is rotatably attached to the shaft member. The shaft member is held by said housing member. The stator comprises a plurality of teeth and one or more windings wound on said plurality of teeth. The rotor comprises a plurality of magnets disposed circumferentially along an inner circumference of said rotor. The plurality of magnets is disposed adjoining said plurality of teeth of said stator. A noise-damping member is disposed circumferentially around said shaft, wherein said noise damping member is sandwiched between said stator and said housing member.
[00022] As per yet another aspect of the present invention, the electrical machine comprising: the stator fixedly attached to a housing member, the rotor rotatably attached to a shaft member, said shaft member being held by said housing member. The stator comprises a plurality of teeth and one or more windings wound on said plurality of teeth. The rotor comprises an outer face, said outer face comprising an outer cylindrical member and an inner cylindrical member. A plurality of magnets are disposed circumferentially along an inner circumference of said outer cylindrical member of said rotor. The plurality of magnets are disposed adjoining said plurality of teeth of said stator and said inner cylindrical member mounted on said shaft member. The outer face comprises one or more openings disposed radially along said outer face.
[00023] As per yet another aspect of the present invention, the outer face of said rotor comprises one or more first set of openings provided radially between said one or more openings.
[00024] As per another aspect of the present invention, the outer face of said rotor comprises one or more second set of openings provided radially between said one or more first set of openings. The second set of openings are capable of mounting a fan.
[00025] As per another aspect of the present invention, said noise damping member comprises of a plurality of openings.
[00026] As per another aspect of the present invention, said noise damping member comprises of one or more projections.
[00027] As per another aspect of the present invention, said one or more projections are capable of extending in a gap formed between said plurality of teeth of said stator.
[00028] As per another aspect of the present invention, said noise-damping member comprises one or more stepped surfaces for allowing passage of wires extending out of said one or more windings.
[00029] As per yet another aspect of the present invention, the electrical machine disclosed herein comprises of the stator fixedly attached to a housing member, the rotor rotatably attached to a shaft member. The shaft member being held by said housing member. The stator comprises a plurality of teeth and one or more windings wound on said plurality of teeth. The rotor comprises an outer face, said outer face comprising an outer cylindrical member and an inner cylindrical member, and a plurality of magnets disposed circumferentially along an inner circumference of said outer cylindrical member of said rotor. The plurality of magnets are disposed adjoining said plurality of teeth of said stator, and said inner cylindrical member mounted on said shaft member, wherein said outer face comprises one or more openings disposed radially along said outer face. A noise-damping member is disposed circumferentially around said shaft, wherein said noise-damping member is sandwiched between said stator and said housing member.
[00030] The present invention provides the electrical machine which is simple, easy to manufacture, economical, space-efficient, lightweight, and does not require significant change in the existing system configurations for diminishing the humming noise from the generator.
[00031] The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00032] Fig.1 exemplarily illustrates exploded perspective view of an existing general assembly of an electrical machine comprising of a stator (102) and a rotor (103), coupled with a power source e.g. a battery or an engine. More specifically, the stator (102) is attached with a housing member (101) of the engine through fasteners, while a shaft member holds the rotor (103). The stator (102) has a plurality of teeth which further comprises a plurality of windings wounded around them. The windings are made up of ferromagnetic material. An inner circumference of the rotor (103) has the plurality of magnets disposed inside them. The plurality of magnets and the plurality of teeth of the stator (102) are adjoined with each other. When the engine starts operating the vibration from the engine is transmitted to the rotor (103). The vibration of the rotor (103) causes a out of plane deformation of an outer surface (204AA) of the rotor (103) which is perpendicular to the axis of the rotor (103). The deformed outer face (204AA) starts vibrating which further excites the nearby air molecules, due to which a continuous humming sound is generated from the vibration of the rotor (103). The amplitude of the noise is directly proportional to the number of air molecules excited.
[00033] Fig. 2 exemplarily illustrates exploded perspective view of an the electrical machine as per an embodiment of the present invention. The present invention discloses the electrical machine (200), having two major parts namely of the stator (102), and the rotor (103) with slits (201,202,203). The stator (205) has the plurality of teeth, which further comprises of a plurality of windings wounded around them. The rotor (204) is attached with the shaft of the engine. The outer face (204AA) of the rotor (204) has multiple slits (201,202,203) constituting of one or more than one openings (201), and a first set of openings (202) and a second set of opening (203). The rotor (204) with slits (201,202,203) is hereinafter referred as slitted rotor (204).
[00034] Fig.3 illustrates a perspective view of slitted rotor (204) as per the present invention. The rotor (204) comprises an outer cylindrical member (301), an inner cylindrical member (302). An inner circumference (304) of the outer cylindrical member (301) is configured with plurality of magnets (not shown) disposed such that the plurality of magnets and the plurality of teeth of the stator (205) are adjoining with each other. The inner cylindrical member (302) is mounted on a shaft member. The outer face (204AA) is configured with multiple slits constituting of one or more than one openings (201), and the one or more first set of opening (202) and the one or more second set of opening (203). The one or more openings (201) are configured circumferentially along the outer surface (204AA) of the rotor (204). The first set of opening (202) are provided circumferentially between the one or more openings (201), whereas the second set of opening (203) are provided circumferentially at a radial distance lower than the radial distance of first set of openings (202). The second set of openings (203) are capable of holding a fan. By providing the openings (201), and the first set of opening (202) on the outer face (204AA) of the rotor (204), the total surface area of the rotor (204) decreases. More specifically, by reducing the surface area of the rotor (204), the vibration caused to the rotor (204) due to various reasons not only limited to magnetic interaction between the stator (205) and the rotor (204) such as vibration transmitted through the engine operation and other associated parts, is reduced since the overall area of vibration is reduced. A small surface area will excite less nearby air molecules than a larger surface area. Hence, a smaller surfaced area rotor (204204) will produce less humming noise than a conventional rotor. By reducing the surface area of the rotor (204) no resonance frequency is shifted, thus said configuration could work in all engine frequencies. In addition, the slits on the outer surface (204AA) of the rotor (204) are configured in such a specific pattern that, the openings (201) and the first set of opening (202) allows quantitatively more amount of air to pass through, thus allowing to maintain lower temperature of the stator (205). The present configuration does not requires any additional changes in mounting, additional cost or weight for diminishing a humming noise caused due to the rotor (204) deformity. The slitted rotor provides advantage of both mechanical integrity and lesser surface area for noise generation. The feature that reduces surface area of the outer surface (204AA) is not limited to openings (201) and first set openings (202) or the second set of openings (203).
[00035] Fig.4 exemplarily illustrates an exploded perspective view of the electrical machine as per an embodiment of the present invention. The electrical machine (200) includes the stator (205), the rotor (204) with the openings (201), the first set of opening (202) and the second set of opening (203). A fan (401) disposed on the second set of opening (203) of the outer surface (204AA) of the rotor (204) and a noise damping member (402) disposed axially between the housing member (206) and the stator (205). As mentioned that in the conventional electrical machine when the rotor (204) rotates with the shaft (403) the stator (205) experiences the magnetostriction force due to fluctuating magnetic field because the rotor (204) contains plurality of magnets and the teeth of the stator (205) are made up of ferromagnetic material. The stator (205) experiences a torsion and bending mode due to magnetorstiction force and due to vibration of the engine and its associated parts. This causes a deformation on the stator 205 surface (which causes vibration in the stator (205) and other supporting structural members. The vibration furthers excites nearby air molecules and creates noise and contributes to the humming sound produced by the rotor (204) vibration. The present invention sandwiches a noise-damping member (402) axially between the stator (205) and the housing member (206). The noise damping member (402) is disposed cicrcumferentially round a shaft member (403). The noise damping member (402) provides a constant elastic tension force on the surface of the stator (205) and gets slightly elastically compressed when the stator (205) is abuttingly mounted, thereby restricting deformation or vibration of the stator (205) due to any kind of force or vibration. More specifically, said noise damping member (402) clasps the outer edge of the stator (205) where the stator (205) is prone to high vibration and deformation. Therefore, the amplitude of the noise generated by the vibration or deformity of the stator (205) is diminished significantly. The noise damping member can be placed between the stator (205) and any fixed surface such as metal plate or crankcase. The noise damping member (402) is such that it has a negligent weight, which can aptly fit in between the available space of the housing member (101) and the stator (205), thus not adding any significant change in the vehicle configuration and weight. Additionally, said noise damping member (402) simply clasps the stator (205) with existing mounting fasteners used to mount the stator to the housing member (101), hence does not require any additional mounting mechanism, therefore not adding to cost of manufacturing. The present invention does not necessitate any increase in size or space between the housing (101) and the stator (205).
[00036] Fig.5 exemplarily illustrates a perspective view of the noise-damping member (402). The noise damping member (402) is configured with one or more circumferential projections (501), and one or more circumferential stepped surface (502) on the lateral surface. The projections (501) are capable of extending in a gap formed between pluralities of teeth of said stator (205) thus get engaged with the pluralities of teeth of said stator (205). The stepped surface (502) allows the passage of wires extending out of windings of the teeth of the stator (205). The noise damping member (402) also comprises of plurality of opening or holes (not shown). The openings are made such that sufficient amount of air can pass through for maintaining temperature of the engine. The noise-damping member (402) can be made of any material having abrasion resistance, specific gravity, tear resistant such as rubber.
[00037] Fig.6 exemplarily illustrates a side cut section view of the electrical machine (100) assembly along with mounting member and drive shaft member e.g. crankshaft as per an embodiment of the present invention. The stepped surface (502) shown ing Fig 5 of the noise-damping member (402) allows the lateral passage and routing of the wires (601) from the teeth of the stator (205). The fan (401) being mounted on the top of the rotor (204), the rotor (204) with openings (201) and first set of openings (202), and the noise damping member (402) with openings, projections (501) and stepped surface (502) together assists in diminishing the humming noise significantly and also assists lowering temperature of the engine.
[00038] Fig.7-Fig.8 illustrates statistics of test results of multiple cases of the electrical machine (100) in the acceleration and deceleration condition. The statistics results are prepared on noise (dB) and engine RPM. As can be seen from Fig.7, in acceleration condition, the reduction in noise level is highest when the combination of all improvements proposed by the present invention i.e. noise damping member (402) and the rotor (204) with slits are configured together in an electrical machine (100), are implemented. While the noise reduction is, least when only the rotor (204) with the fan (401) is assembled in the electrical machine (100).
[00039] As can be seen from Fig.8, in declaration condition the noise is reduced maximum when the combination of all improvements proposed by the present invention i.e. noise damping member (402) and the rotor (204) with slits are configured together in an electrical machine (100
[00040] Fig.9-Fig.10 illustrates graphical difference in noise level in acceleration condition and deceleration condition respectively. As inferred form Fig.9 while the vehicle is acceleration, in conventional configuration, the noise level is highest (901). In the fan and the rotor (204) with slits configuration, the noise level is medium (902), whereas the noise level is least (903) when the noise damping member (402) and the rotor (204) with the fan (401) is configured in the electrical machine (100). Similarly, from Fig.10 it can be inferred that while the vehicle is in deceleration condition the noise level is highest (901). In the fan (401) and the rotor (204) with slits configuration the noise level is medium (902), whereas the noise level is least (903) when the noise damping member (402) and the rotor (204) with the fan (401) is configured in the electrical machine (100).
[00041] Fig.11 illustrates a flowchart of method of diminishing noise form an electrical machine (100). When the engine starts to operate, if noise is coming from the electrical machine (100), then method illustrated as per present invention diminish the noise significantly. The method involves the steps (1101-1105) of creating plurality of opening (201) on the rotor (204) outer surface (204AA); creating first set of openings (202) on the rotor (204) outer surface (204AA); and creating second set of openings (203) on the outer surface (204AA). In order to diminish the noise to a maximum level, the noise-damping member (402) is introduced between the stator (205) and fixed surface (1105), for example the housing member (101).
[00042] Many other improvements and modifications may be incorporated herein without deviating from the scope of the invention.

List of Reference numerals
100: Electrical machine
101: Housing member as per existing state of art
102: Stator as per existing state of art
103: Rotor as per existing state of art
104: Outer surface
200: Electrcial machine as per current invention
201: Openings
202: First set of openings
203: Second set of openings
204: Rotor as per current invention
204AA: outer surface of rotor
205: Stator as per current invention
206: Housing member as per current invention
301: Outer cylindrical member
302: Inner cylindrical member
303: Inner circumferance
401: Fan
402: Noise damping member
403: Shaft member
501: Projections
502: Stepped surface
601: Wires
901-903: Line of graph
1101-1105- Method flowchart