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Title:
ELECTRO-DYNAMIC VIBRATION GENERATING APPARATUS
Document Type and Number:
WIPO Patent Application WO/2019/097307
Kind Code:
A1
Abstract:
Present disclosure provides an apparatus for generating vibrations that can be used for Noise, Vibration, and Harshness (NVH) testing as well as for reproducing sound in loudspeakers. In an aspect, proposed apparatus includes a stator core having a pair of stator segments including a first stator segment and a second stator segment spaced apart to form an air gap, and an armature assembly including a flat armature segment and at least one drive coil mounted on the flat armature segment, wherein the armature assembly is placed in the air gap formed by the pair of stator segments and the armature assembly is capable of having translation along an axial direction, wherein the first stator segment and the second stator segment have geometrical shape formed by linear translation of their cross-section in a plane along the axial direction, and wherein direction of the linear translation is perpendicular to the axial direction.

Inventors:
GOEL, Rakesh (401/1, 32 Civil Lines,Roorkee, Uttrakhand 7, 247667, IN)
GOEL, Ankur (401/1, 32 Civil Lines,Roorkee, Uttrakhand 7, 247667, IN)
Application Number:
IB2018/050015
Publication Date:
May 23, 2019
Filing Date:
January 02, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
GOEL, Rakesh (401/1, 32 Civil Lines,Roorkee, Uttrakhand 7, 247667, IN)
GOEL, Ankur (401/1, 32 Civil Lines,Roorkee, Uttrakhand 7, 247667, IN)
International Classes:
H02K33/16; B06B1/04; H02K33/18
Foreign References:
FR2031901A51970-11-20
US9467035B22016-10-11
US20170054354A12017-02-23
DE102005052626A12007-05-16
TWI600256B2017-09-21
Attorney, Agent or Firm:
KHURANA & KHURANA, ADVOCATES & IP ATTORNEYS (E-13, UPSIDC Site-IV, Behind-Grand Venice,Kasna Road, Greater Noida, National Capital Region, Uttar Pradesh 0, 201310, IN)
Download PDF:
Claims:
We Claim:

1. A vibration generating apparatus comprising:

a stator core having a pair of stator segments comprising a first stator segment and a second stator segment spaced apart to form an air gap; and

an armature assembly comprising a flat armature segment and at least one drive coil mounted on the flat armature segment, wherein the armature assembly is placed in the air gap formed by the pair of stator segments and the armature assembly is capable of having translation along an axial direction;

wherein the first stator segment and the second stator segment have geometrical shape formed by linear translation of their cross-section in a plane along the axial direction, and wherein direction of the linear translation is perpendicular to the axial direction.

2. The apparatus of claim 1, wherein the armature assembly is supported by a top suspension and a bottom suspension operatively coupled with the stator core.

3. The apparatus of claim 1, wherein the air gap formed by the pair of stator segments comprises a plurality of eddy-current plates to reduce inductance of the drive coil..

4. The apparatus of claim 1, wherein the cross-section of the first stator segment and the second stator segment are formed by an E structure and an inverted E structure respectively.

5. The apparatus of claim 1, wherein the cross-section of the first stator segment and the second stator segment are formed by a C structure and an inverted C structure respectively.

6. The apparatus of claim 1, further comprising a translation mechanism to provide translation to the armature assembly along the axial direction.

7. The apparatus of claim 6, wherein the translation mechanism comprises at least two hinges coupled orthogonally with each other.

8. The apparatus of claim 1, wherein the pair of stator segments are made of Cold Rolled Grain Oriented (CRGO) Steel laminations.

9. The apparatus of claim 1 , wherein the pair of stator segments comprise at least one field coil to generate magnetic flux.

10. The apparatus of claim 1, wherein the pair of stator segments comprise a plurality of permanent magnets configured in a manner such that adjacent magnetic poles have opposite polarities to generate magnetic flux.

Description:
ELECTRO-DYNAMIC VIBRATION GENERATING APPARATUS

TECHNICAL FIELD

[0001] The present disclosure relates to the field of electro-dynamic vibrators. In particular, the present disclosure provides an apparatus for generating vibrations that can be utilized for vibration testing in Noise, Vibration, Harshness (NVH) tests. Further, the apparatus of the present disclosure can also be used in loudspeakers for reproducing sound.

BACKGROUND

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] Electro-dynamic vibrators (or electro-dynamic shakers) are used extensively in vibration testing on any object that can be subjected to vibration, such as automobile components. Further, electro-dynamic vibrators also find their application in loudspeakers for reproducing sound. Generally, in an electro-dynamic vibrator, interaction between magnetic field and current in a moving coil is used to convert electric oscillations at various frequencies into corresponding mechanical vibrations.

[0004] Conventional electromagnetic vibrators include a stator providing static magnetic circuit and an armature assembly as a moving coil. The static magnetic circuit can be made from permanent magnets or by electromagnets. The armature assembly is positioned in an air gap formed by the stator. Further, the armature assembly is kept concentric with the stator with aid of a suitable suspension mechanism. The stator magnetic field produces radial flux lines in the air gap. An axial force is generated based on magnetic flux density, length of the drive coil and current in the drive coil. Therefore, the armature assembly moves or vibrates axially based on applied current in the drive coil.

[0005] For efficient application of an electromagnetic vibrator, a long axial translation is desired with negligible side movement. For such desired movement, a suitable suspension and guide mechanism is incorporated including any or a combination of leaf springs, rolling struts, multi-radial slotted springs, and the likes. However, such mechanisms are complicated, bulky and sometimes do not restrict side movement. Moreover, overall construction of an electro dynamic vibrator is intricate and requires precision machining as armature fundamental resonance frequency is limited due to the design of the armature assembly. Further, mass of the armature assembly is required to be kept to minimum so that translation of the armature assembly is limited by armature mass and drive coil construction.

[0006] As can be inferred from the above, existing mechanisms for producing electro dynamic vibrations are bulky and have complicated constructions. There is therefore a need to develop an apparatus for an electro-dynamic vibrator that can provide improved performance with simplified construction.

OBJECTS OF THE DISCLOSURE

[0007] A general object of the present disclosure is to provide a vibration generating apparatus.

[0008] Another object of the present disclosure is to provide a vibration generating apparatus with simplified construction of stator core and armature assembly.

[0009] A yet another object of the present disclosure is to provide a vibration generating apparatus having long stroke while reducing side movements of the armature assembly.

[00010] A yet another object of the present disclosure is to provide a vibration generating apparatus with lightweight armature assembly.

[00011] A yet another object of the present disclosure is to provide a vibration generating apparatus that reduces requirement of intricate machining.

[00012] A yet another object of the present disclosure is to provide a vibration generating apparatus with high resonance frequency of the armature assembly.

[00013] A yet another object of the present disclosure is to provide a vibration generating apparatus with improved heat transfer rate to provide better cooling.

[00014] These and other objects of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

SUMMARY

[00015] Embodiments of the present disclosure relate to the field of electro dynamic vibration systems. The present disclosure provides an apparatus for generating vibrations that can be utilized for used for NVH testing as well as for reproducing sound in loudspeakers.

[00016] An aspect of the present disclosure pertains to a vibration generating apparatus including: a stator core having a pair of stator segments including a first stator segment and a second stator segment spaced apart to form an air gap; and an armature assembly including a flat armature segment and at least one drive coil mounted on the flat armature segment, wherein the armature assembly is placed in the air gap formed by the pair of stator segments and the armature assembly is capable of having translation along an axial direction; wherein the first stator segment and the second stator segment have geometrical shape formed by linear translation of their cross-section in a plane along the axial direction, and wherein direction of the linear translation is perpendicular to the axial direction.

[00017] In an embodiment, the armature assembly can be supported by a top suspension and a bottom suspension operatively coupled with the stator core.

[00018] In an embodiment, the air gap formed by the pair of stator segments can include a plurality of eddy-current plates to reduce inductance of the drive coil.

[00019] In an embodiment, the cross-section of the first stator segment and the second stator segment can be formed by an E structure and an inverted E structure respectively.

[00020] In an embodiment, the cross-section of the first stator segment and the second stator segment can be formed by a C structure and an inverted C structure respectively.

[00021] In an embodiment, the apparatus can further include a translation mechanism to provide translation to the armature assembly along the axial direction.

[00022] In an embodiment, the translation mechanism can include at least two hinges coupled orthogonally with each other.

[00023] In an embodiment, the pair of stator segments can be made of Cold Rolled Grain Oriented (CRGO) Steel laminations.

[00024] In an embodiment, the pair of stator segments can include at least one field coil to generate magnetic flux.

[00025] In an embodiment, the pair of stator segments can include plurality of permanent magnets poles configured in a manner such that adjacent magnetic poles have opposite polarities to generate magnetic flux. BRIEF DESCRIPTION OF DRAWINGS

[00026] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[00027] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[00028] FIGs. 1A-B illustrate exemplary perspective view representations of a conventional electro-dynamic vibration generating apparatus.

[00029] FIGs. 2A-B illustrate exemplary isometric view representations of a vibration generating apparatus in accordance with an embodiment of the present disclosure.

[00030] FIG. 3 illustrates an exemplary sectional view representation of a vibration generating apparatus including a stator core having an E structure in accordance with an embodiment of the present disclosure.

[00031] FIGs. 4A-B illustrate exemplary sectional view representations of an armature assembly of the vibration generating apparatus in accordance with an embodiment of the present disclosure.

[00032] FIGs. 5A-B illustrate exemplary perspective view representations of a vibration generating apparatus including a stator core having a C structure in accordance with an embodiment of the present disclosure.

[00033] FIGs. 6A-B illustrate exemplary representations of a translation mechanism in accordance with an embodiment of the present disclosure.

[00034] FIGs. 7A-B illustrate exemplary representations of the vibration generating apparatus including permanent magnets in the stator core in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION

[00035] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

[00036] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term“about”. Accordingly, in some embodiments, the numerical value set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical value should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and value setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[00037] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.

[00038] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims. [00039] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.

[00040] Unless the context requires otherwise, throughout the specification which follow, the word“comprise” and variations thereof, such as,“includes” and“comprising” are to be construed in an open, inclusive sense that is as“including, but not limited to.”

[00041] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[00042] As used in the description herein and throughout the claims that follow, the meaning of “a,”“an,” and“the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of“in” includes“in” and“on” unless the context clearly dictates otherwise.

[00043] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g.,“such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[00044] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments. Various terms as used herein. To the extent a term used in a claim is not defined, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing. [00045] Reference will now be made in detail to the exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

[00046] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment includes elements A, B, and C, and a second embodiment includes elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.

[00047] Embodiments of the present disclosure relate to the field of electro dynamic vibration systems. The present disclosure provides an apparatus for generating vibrations that can be utilized for used for NVH testing as well as for reproducing sound in loudspeakers.

[00048] An aspect of the present disclosure can pertain to a vibration generating apparatus including: a stator core having a pair of stator segments including a first stator segment and a second stator segment spaced apart to form an air gap; and an armature assembly including a flat armature segment and at least one drive coil mounted on the flat armature segment, wherein the armature assembly is placed in the air gap formed by the pair of stator segments and the armature assembly is capable of having translation along an axial direction; wherein the first stator segment and the second stator segment have geometrical shape formed by linear translation of their cross-section in a plane along the axial direction, and wherein direction of the linear translation is perpendicular to the axial direction.

[00049] In an embodiment, the armature assembly can be supported by a top suspension and a bottom suspension operatively coupled with the stator core.

[00050] In an embodiment, the air gap formed by the pair of stator segments can include a plurality of eddy-current plates to reduce inductance of the drive coil.

[00051] In an embodiment, the cross-section of the first stator segment and the second stator segment can be formed by an E structure and an inverted E structure respectively.

[00052] In an embodiment, the cross-section of the first stator segment and the second stator segment can be formed by a C structure and an inverted C structure respectively. [00053] In an embodiment, the apparatus can further include a translation mechanism to provide translation to the armature assembly along the axial direction.

[00054] In an embodiment, the translation mechanism can include at least two hinges coupled orthogonally with each other.

[00055] In an embodiment, the pair of stator segments can be made of Cold Rolled Grain Oriented (CRGO) Steel laminations.

[00056] In an embodiment, the pair of stator segments can include at least one field coil to generate magnetic flux.

[00057] In an embodiment, the pair of stator segments can include a plurality of permanent magnets configured in a manner such that adjacent magnetic poles have opposite polarities to generate magnetic flux.

[00058] FIGs. 1A-B illustrate exemplary perspective view representations of a conventional electro-dynamic vibration generating apparatus.

[00059] As illustrated in FIG. 1A, a conventional electro-dynamic vibration generating apparatus 100 incorporates a cylindrical structure in which a cylindrical armature assembly can be placed in an air gap such that the armature assembly is concentric with a stator core. FIG. 1B provides a sectional representation 150 of the conventional electro-dynamic vibration generating apparatus 100. In the conventional electro-dynamic vibration generating apparatus, a field coil 152 is placed in a stator core to generate magnetic flux that can pass through an air gap. Further, an armature assembly including an armature segment 154 mounted with a drive coil 156 can be placed inside the air gap. The interaction between magnetic flux and current in drive coil can produce a force that can cause to and fro translations of the armature assembly. A pneumatic mount 172 can be used to center the armature assembly. A top suspension 158 and a bottom suspension 160 are provided to support the armature assembly. Also, covers 162 and 164 are provided to protect the apparatus from physical damage. For cooling mechanism, forced air can be passed from inlets 166 and 168 and can be expelled from outlet 170.

[00060] FIGs. 2A-B illustrate exemplary isometric view representations of a vibration generating apparatus in accordance with an embodiment of the present disclosure.

[00061] In an aspect, as illustrated in FIG. 2A, the vibration generating apparatus of the present disclosure can include a stator core comprising a first segment 202 and a second segment 206 forming a pair of stator segments. The first segment 202 and the second segment 206 can be spaced apart to form an air gap. In an embodiment, the stator segments can be made of Cold Rolled Grain Oriented (CRGO) Steel laminations.

[00062] In an embodiment, the stator core can include a field coil 204 for generating magnetic flux that can pass through the air gap. Alternatively, in another embodiment, the magnetic flux in the air gap can be generated by incorporating a plurality of magnetic poles in the stator core in such a manner that the poles that are placed adjacent to each other are of opposite polarities.

[00063] In an aspect, an armature assembly 210 can be placed in the air gap formed by the pair of segments 202 and 206 of the air gap. The armature assembly 210 can include an armature segment having a flat structure. The armature assembly can be supported by a top suspension 206 and a bottom suspension 208 operatively coupled with the stator core. Further, the armature assembly can include drive coils mounted on the armature segment, such that when current is passed through the drive coil, the interaction of the current and the magnetic flux can produce a force that can cause to and fro translation of the armature assembly along an axial direction. FIG. 2B illustrates a flat armature segment placed in the air gap formed by the stator segments.

[00064] In an aspect, the first stator segment and the second stator segment can have a geometrical shape that can be formed by linear translation of their cross-section in a plane along the axial direction. The direction of the linear translation can be perpendicular to the axial direction. Said aspect provides a flat structure to the stator such that resultant attraction force is high due to flat faced magnetic flux which is converse to flux generated in the conventional apparatus as in the conventional apparatus a circular magnetic force pattern is produced that cancels each other producing less magnetic force of attraction in the air gap. Thus, to control said high magnetic force of attraction, a non magnetic support 212 can be configured with the stator core.

[00065] FIG. 3 illustrates an exemplary sectional view representation of a vibration generating apparatus including a stator core having an E structure in accordance with an embodiment of the present disclosure.

[00066] As illustrated in sectional view 300, in an embodiment, apparatus of the present disclosure can include a stator core including a first stator segment 302 and a second stator segment 316 forming a pair of segments with cross-section formed by an E structure and an inverted E structure respectively. Further, the stator core can include a field coil 304 to generate magnetic flux. The stator core can further be coupled with a top suspension 310 and a bottom suspension 308 to support an armature assembly 306 placed in an air gap formed by the pair of stator segments. The armature assembly can include a flat armature mounted with a drive coil 314 such that when a current is passed through the drive coil 314, a force is produced that can cause translation of the armature assembly.

[00067] In an embodiment, the air gap can include a plurality of eddy current plates 312. It would be appreciated by the one skilled in the art that eddy currents plates are essential to reduce inductance of the drive coil 314 mounted of the flat armature. To provide clarity, said embodiment can be explained by using an example, for example, a drive coil 314 of inductance of 1000 mH in free space can have an inductance of 100 mH in the presence of the eddy plates 312, which can accordingly increase the frequency response, thus, if the frequency response achieved as 200 Hz without plates, the frequency response can be achieved to be 2000 Hz in presence of the eddy plates 312. Thus, according to the present disclosure, thin eddy current plates 312 can be provided to achieve high frequency response.

[00068] FIGs. 4A-B illustrate exemplary sectional view representations of an armature assembly of the vibration generating apparatus in accordance with an embodiment of the present disclosure.

[00069] As illustrated, the armature assembly can include an armature segment mounted with thin drive coils 402 and 404. In an embodiment, current in the drive coils 402 and 404 can flow in such a manner that the current flowing in both drive coils 402 and 404 can flow in same direction at interface 406, such that the direction of current flowing through interface 406 is perpendicular to the direction of magnetic flux generated by the stator core. For example, the current can flow in clockwise direction in drive coil 402 and can flow in anti-clockwise direction in drive coil 404 such that the direction of current flowing through interface 406 is perpendicular to the direction of magnetic flux passing through the air gap.

[00070] FIGs. 5A-B illustrate exemplary perspective view representations of a vibration generating apparatus including a stator core having a C structure in accordance with an embodiment of the present disclosure.

[00071] As illustrated in FIG. 5A, a triad 502 can be used to represent three axes for ease of explanation. X-axis is pointed towards thickness of stator core, Y-axis is pointed towards an axial direction of translation of the armature assembly, and Z-axis is pointing towards magnetic flux in the air gap. In an embodiment, the stator core can include a first stator segment 504, and a second stator segment 508 with cross-section formed by a C structure and an inverted C structure respectively. The field coil 506 can be configured with the stator core to generate magnetic flux. Further, as illustrated in FIG. 5B, the armature assembly can comprise a flat armature segment mounted with thin drive coil 552 that can be located centrally in the air gap.

[00072] In an embodiment, the apparatus can further include a translation mechanism 554 to aid in translation of the armature assembly in the axial direction, and prevent movement of the armature assembly in directions other than the axial direction. The translation mechanism can be any suitable mechanism that can provide a long stroke to and fro translation to the armature assembly. In an embodiment, the translation mechanism can be formed by an at least two hinges mounted orthogonally with each other such that rotation of at least one hinge along its pivot axis can result in translation of the armature only in the axial direction.

[00073] FIGs. 6A-B illustrate exemplary representations of a translation mechanism in accordance with an embodiment of the present disclosure.

[00074] In an aspect, as illustrated in FIG. 6A, the translation mechanism can include at least two hinges 602 and 604 coupled orthogonally with each other. Each hinge 602 and 604 can be coupled with the armature segment and the stator core to provide axial translation to the armature assembly and restrict movement of the armature assembly in other directions. As illustrated in FIG. 6B, the translation mechanism can be coupled with both ends of the armature assembly. FIG. 6B also illustrates various positions of the hinges of the translation mechanism represented by 652, 654 and 656.

[00075] FIGs. 7A-B illustrate exemplary representations of the vibration generating apparatus including permanent magnets in the stator core in accordance with an embodiment of the present disclosure.

[00076] In an aspect, the pair of stator segments can include a plurality of permanent magnets 702-712 to generate magnetic flux. The plurality of permanent magnets 702-712 can be configured in a manner such that adjacent poles have opposite polarities to generate magnetic flux. As illustrated, permanent magnets 702-712 can be mounted on face of E shaped segments of the stator core. To generate magnetic flux, the magnets pole 702 can have north polarity, 704 can have south polarity, 706 can have north polarity, 708 can have south polarity, 710 can have north polarity and 712 can have south polarity. [00077] It would be appreciated that, in conventional apparatus for generating electro dynamic vibrations, a solid rod based center core and cylinder based outer core is used to complete the magnetic circuit. Thus, the useful magnetic field in the air gap has radial flux lines. However, in the apparatus as disclosed in the present disclosure, the magnetic circuit can have linear flux lines in the air gap between the stator segments. The magnetic polarities in double E structure can be N-S, S-N, N-S and in double C structure the magnetic polarities can be N-S, S- N. Therefore, the apparatus of the present disclosure can provide effective area of useful magnetic flux.

[00078] In an exemplary implementation, 66% length of drive coil can be utilized with magnetic flux in the air gap. Further, the apparatus of the present disclosure can have better cooling as there can be efficient heat transfer from the drive coil to armature segment in all directions. The portion of the at least one drive coil oriented in the axial direction does not generate necessary force as it lies outside the magnetic flux area. The thickness of the at least one drive coil can be increased outside the magnetic flux area to reduce the length of the drive coil outside magnetic flux in order to reduce coil mass, coil resistance and coil inductance. In an aspect, the drive coils can be placed between thin flat eddy current plates of copper for inductance reduction.

[00079] It would be appreciated that structure of armature assembly as disclosed in the present disclosure is associated with high resonance frequency that allows the armature assembly to vibrate strongly in wide frequency range when the armature assembly is subjected to a necessary force derived by the current flowing in the drive coil and flux generated by the stator core.

[00080] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. [00081] While embodiments of the present invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the invention, as described in the claim.

ADVANTAGES OF THE DISCLOSURE

[00082] The present disclosure provides a vibration generating apparatus that can be utilized for reproducing sound.

[00083] The present disclosure provides a vibration generating apparatus with simplified construction of stator core and armature assembly.

[00084] The present disclosure provides a vibration generating apparatus having long stroke while reducing side movements of the armature assembly.

[00085] The present disclosure provides a vibration generating apparatus with lightweight armature assembly.

[00086] The present disclosure provides a vibration generating apparatus that reduces requirement of intricate machining.

[00087] The present disclosure provides a vibration generating apparatus with high resonance frequency of armature assembly.

[00088] The present disclosure provides a vibration generating apparatus with improved heat transfer rate to provide better cooling.