SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a motor stator and motor has cancelled each alternate busbar, has realized each alternate interior lug connection, has reduced the preparation technology complexity, has reduced manufacturing cost, has reduced material cost, has improved machining efficiency.
To achieve the purpose, the utility model adopts the following technical proposal:
a motor stator, the stator core has a plurality of slots formed on the radial inner surface of the stator core and spaced apart at predetermined slot pitches in the circumferential direction of the stator core;
a stator winding including a plurality of phase windings mounted on a stator core;
the motor is characterized in that each phase winding comprises a plurality of U-shaped conductors which are sequentially connected in series along the circumferential direction of the stator core and form M layers in the radial direction of the stator core, wherein M is an odd number which is more than or equal to 3; the extending directions of two welding ends of the U-shaped conductor positioned on the first layer in the radial direction of the stator core in the phase winding are the same; the extending directions of two welding ends of partial U-shaped conductors positioned on the radial Mth layer of the stator core in the phase winding are the same, and the extending directions of two welding ends of other U-shaped conductors except the U-shaped conductor on the radial first layer of the stator core and the partial U-shaped conductor on the radial Mth layer of the stator core in the phase winding are opposite;
the welding ends of each phase winding, which are positioned at any layer in the radial direction of the stator core, have the same span extending along the circumferential direction of the stator core.
Furthermore, the two groove interiors of the U-shaped conductors positioned on the first radial layer of the stator core in each phase winding are positioned on the first radial layer of the stator core, the two groove interiors of the other U-shaped conductors except the U-shaped conductor positioned on the first radial layer of the stator core in each phase winding are positioned on two radially adjacent layers of the stator core, and the pitch of the U-shaped conductors positioned on the first radial layer of the stator core in each phase winding is not equal to the integral pitch.
Further, the pitch of the U-shaped conductors in each phase winding located on the first layer in the radial direction of the stator core is a long pitch, the pitch of a part of the U-shaped conductors in each phase winding located on the second layer and the third layer in the radial direction of the stator core is a long pitch, and the pitch of the other part of the U-shaped conductors in each phase winding located on the second layer and the third layer in the radial direction of the stator core is a short pitch.
Further, the pitch of the U-shaped conductors in each phase winding, which are positioned on the first layer of the stator core in the radial direction, is a long pitch, and the pitch of the U-shaped conductors in each phase winding, which are positioned on the second layer and the third layer of the stator core in the radial direction, is a whole pitch.
Further, the pitch of a part of U-shaped conductors in the fourth layer and the fifth layer in the radial direction of the stator core in each phase winding is a long pitch, and the pitch of another part of U-shaped conductors in the fourth layer and the fifth layer in the radial direction of the stator core in each phase winding is a short pitch.
Further, the pitch of the U-shaped conductors in the fourth layer and the fifth layer in the radial direction of the stator core in each phase winding is the whole pitch.
Further, the pitch of the U-shaped conductors in each phase winding, which are positioned on the first layer of the stator core in the radial direction, is a short pitch, and the pitch of the U-shaped conductors in each phase winding, which are positioned on the second layer and the third layer of the stator core in the radial direction, is a full pitch.
Further, the pitch of the U-shaped conductors in each phase winding located on the first layer in the radial direction of the stator core is a short pitch, the pitch of a part of the U-shaped conductors in each phase winding located on the second layer and the third layer in the radial direction of the stator core is a long pitch, and the pitch of the other part of the U-shaped conductors in each phase winding located on the second layer and the third layer in the radial direction of the stator core is a short pitch.
Further, the pitch of a part of U-shaped conductors in the fourth layer and the fifth layer in the radial direction of the stator core in each phase winding is a long pitch, and the pitch of another part of U-shaped conductors in the fourth layer and the fifth layer in the radial direction of the stator core in each phase winding is a short pitch.
Further, the pitch of the U-shaped conductors in the fourth layer and the fifth layer in the radial direction of the stator core in each phase winding is the whole pitch.
Furthermore, the welding ends corresponding to the inside of the slots of the partial U-shaped conductors positioned on the Mth radial layer of the stator core in each phase winding are positioned on the different radial layers of the stator core, and the welding ends corresponding to the inside of the slots of the other U-shaped conductors except the partial U-shaped conductors positioned on the Mth radial layer of the stator core in each phase winding are positioned on the same radial layer of the stator core.
In order to achieve the above object, the present invention also provides a motor including the above motor stator.
The utility model has the advantages that: the same and opposite matching mode of the extending direction of the welding ends of the U-shaped conductor is adopted, the welding modes can be directly adopted to connect the welding ends, the use of a bus bar is cancelled, the simplification of the winding process of the stator winding is realized, the production efficiency is improved, and the production cost is reduced.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
It should be noted that the terms "first", "second", and the like in the description and claims of the present invention and the accompanying drawings are used for distinguishing different objects, and are not intended to limit a specific order. The embodiments of the present invention can be implemented individually, and can be implemented by combining each other between the embodiments, and the embodiments of the present invention are not limited to this.
The pitch in this application is the circumferential pitch between two slot inner portions 301 of one U-shaped conductor, or the pitch is the circumferential pitch between the weld end 303 corresponding to one slot inner portion 301 of one U-shaped conductor and the weld end 303 corresponding to one slot inner portion 301 of another U-shaped conductor.
As shown in fig. 1, an embodiment of the present invention provides a motor stator, including: a stator core 20 having a plurality of slots 21 formed on a radially inner surface thereof and spaced apart at predetermined slot pitches in a circumferential direction of the stator core;
referring to fig. 1 to 2, in the present embodiment, a stator winding 10 includes a plurality of phase windings mounted on a stator core 20 so as to be different from each other in electrical phase, and the motor stator is a motor stator in a hairpin motor; the stator winding 10 is three-phase (i.e., U-phase, V-phase, W-phase), and each phase slot of each pole is greater than or equal to 2; two slots 21 are provided for each pole of the rotor, 2 slots per phase per pole in this embodiment, the rotor having eight poles and this is true for each phase of the three-phase stator winding 10, the number of slots 21 provided in the stator core 20 being equal to 48 (i.e., 2X8X 3).
Further, in the present embodiment, the stator core 20 is defined by two adjacent slots 21, one tooth 22, and the stator core 20 is formed by laminating a plurality of annular magnetic steel plates, into which a plurality of insulating papers are inserted, at both end faces in the axial direction of the stator core, and it should be noted that other conventional metal plates may be used instead of the magnetic steel plates.
With reference to fig. 5 to 11, in the present embodiment, each phase winding (U-phase winding or V-phase winding or W-phase winding) includes a plurality of U-shaped conductors 100(200) connected in series in sequence along the circumferential direction of the stator core 20 and forming M layers in the radial direction of the stator core 20, and in the present embodiment, the phase winding (U-phase winding or V-phase winding or W-phase winding) forms M layers in the radial direction of the stator core; the above-mentioned M odd number layer may be three, five, seven or more layers.
As shown in fig. 3, 5 to 11, in the present embodiment, the extending directions of the two welding ends 303 of the U-shaped conductor 100 located at the first layer in the radial direction of the stator core 20 in the U-phase winding (V-phase winding or W-phase winding) are the same; 8U-shaped conductors 100 located in the first radial layer of the stator core 20 in each phase winding; the three-phase winding is provided with 24U-shaped conductors 100 positioned on the first radial layer of the stator core 20 and fully distributed in 48 slots on the first radial layer of the stator core; referring to fig. 3, the U-shaped conductor 100 located on the first radial layer of the stator core includes a welding end 303, an inside slot 301, a plug end 302, an inside slot 301 and a welding end 303 sequentially connected end to end, the two inside slot 301 are located in two slots of the stator core circumferentially spaced by a specified slot distance, the plug end 302 is located at one end of the stator core axially outside the slot and connected with the two inside slot 301, the two welding ends 303 are located outside the stator core and connected with the two inside slot 301 at one end far from the plug end 302, and the two welding ends 303 extend in the same direction. The extending directions of two welding ends 303 of the U-shaped conductors 100 of the U-phase winding (V-phase winding or W-phase winding) positioned on the Mth radial layer of the stator core 20 are the same, and 8U-shaped conductors 100 (or 8U-shaped conductors contain a connecting outgoing line) of the U-shaped winding positioned on the Mth radial layer of the stator core 20 are arranged in each phase winding; the three-phase winding is provided with 24U-shaped conductors 100 positioned on the radial Mth layer of the stator core 20, and every six U-shaped conductors 100 are sequentially positioned in six circumferentially adjacent slots of the stator core to form a group, namely 4 groups of 24 three-phase windings positioned on the radial Mth layer of the stator core 20 are uniformly arranged in 48 slots on the radial Mth layer of the stator core at intervals; referring to fig. 3, the partial U-shaped conductor 100 located on the mth radial layer of the stator core includes a weld end 303, an in-slot portion 301, an insert end 302, an in-slot portion 301, and a weld end 303 sequentially connected end to end, where the two in-slot portions 301 are located in two slots of the stator core circumferentially spaced by a specified slot pitch, the insert end 302 is located outside the axial slot of the stator core and is connected to the two in-slot portions 301, the two weld ends 303 are located outside the stator core and are connected to the two in-slot portions 301 at an end far from the insert end 302, and the two weld ends 303 extend in the same direction. The two welding ends 303 of the U-shaped conductors 200 in the U-phase winding (the V-phase winding or the W-phase winding) except the U-shaped conductors located at the first radial layer of the stator core and the other U-shaped conductors located at the Mth radial layer of the stator core extend in opposite directions; with reference to fig. 5 to 11, 16U-shaped conductors 200 located at the second and third radial layers of the stator core 20 are provided in each phase winding, and the three-phase winding has 48U-shaped conductors 200 located at the second and third radial layers of the stator core 20 and fully distributed in 48 slots of the second and third radial layers of the stator core; each phase winding comprises 8U-shaped conductors 200 positioned at the fifth layer and the fourth layer in the radial direction of the stator core (namely 8U-shaped conductors 200 positioned at the Mth layer in the radial direction of the stator core except for the partial U-shaped conductors 100), each three-phase winding comprises 24U-shaped conductors 200 positioned at the fourth layer and the fifth layer in the radial direction of the stator core 20, and each six U-shaped conductors 200 are sequentially positioned in six circumferentially adjacent slots of the stator core to form a group, namely, 24 groups of the three-phase windings are positioned at the fourth layer in the radial direction of the stator core 20, and 4 groups of the fifth layer are uniformly arranged at intervals in the fourth layer and the fifth layer in the radial direction of the stator core (namely, the three groups of the three-phase windings are positioned in iron core slots different from the partial U-shaped conductors 100 positioned at the fifth layer in the radial direction of the stator core); with reference to fig. 4, the U-shaped conductors 200 located at the fourth layer and the fifth layer in the radial direction of the stator core and the U-shaped conductors 200 located at the second layer and the third layer in the radial direction of the stator core sequentially include a welding terminal 303, an in-slot portion 301, a plug terminal 302, an in-slot portion 301 and a welding terminal 303, the two in-slot portions 301 are located in two slots of the stator core circumferentially spaced by a specified slot distance, the plug terminal 302 is located at one end outside the axial slot of the stator core and connected with the two in-slot portions 301, one end of the two welding terminals 303 located outside the stator core and far away from the plug terminal 302 is connected with the two in-slot portions 301, and the extending directions of the two welding terminals 303 are opposite;
the welding ends 303 of any layer in the radial direction of the stator core 20 in each phase of winding have the same span extending along the circumferential direction of the stator core; specifically, with reference to fig. 5 to 11, the extending directions of the welding ends 303 located at the first radial layer of the stator core are all leftward and the spans are all 3 slots consistently, the extending directions of the welding ends 303 located at the second radial layer of the stator core are all rightward and the spans are all 3 slots consistently, the extending directions of the welding ends 303 located at the third radial layer of the stator core are all leftward and the spans are all 3 slots consistently, the extending directions of the welding ends 303 located at the fourth radial layer of the stator core are all leftward and the spans are all 3 slots consistently, the extending directions of the welding ends 303 located at the fifth radial layer of the stator core are all leftward and the spans are all 3 slots consistently, that is, the extending spans of the welding ends 303 located at the first radial layer of the stator core in each phase of windings are the same, and the extending spans of the welding ends 303 located at the second radial layer of the stator core are the same, the extending spans of the welding ends 303 located at the radial third layer of the stator core are the same, the extending spans of the welding ends 303 located at the radial fourth layer of the stator core are the same, the extending spans of the welding ends 303 located at the radial fifth layer of the stator core are the same, and the extending spans of the welding ends 303 located at the radial virtual six layers of the stator core are the same. The same and opposite matching mode of the extending direction of the welding ends of the U-shaped conductor is adopted, the welding modes can be directly adopted to connect the welding ends, the use of a bus bar is cancelled, the simplification of the winding process of the stator winding is realized, the production efficiency is improved, and the production cost is reduced.
With reference to fig. 5 to 11, in this embodiment, two slot interiors of the U-shaped conductor 100 located in the first radial layer of the stator core 20 in each phase winding are located in the first radial layer of the stator core, the first slot interior of the U-shaped conductor 100 located in the first radial layer of the stator core is located in the 2 nd slot (1 st slot) in the first radial layer of the stator core, the second slot interior is located in the 7 th slot (8 th slot) in the first radial layer of the stator core, and two slot interiors of the remaining U-shaped conductors 200(100) in each phase winding, except the U-shaped conductor 100 located in the first radial layer of the stator core, are located in two radially adjacent layers of the stator core; the first slot inside the U-shaped conductor 200 positioned at the second layer and the third layer in the radial direction of the stator core is positioned at the 1 st slot at the third layer in the radial direction of the stator core, the 7 th slot (8 th slot) at the second layer in the radial direction of the stator core is positioned inside the second slot, the 7 th slot at the fifth layer in the radial direction of the stator core is positioned inside the first slot inside the U-shaped conductor 200 positioned at the fourth layer and the fifth layer in the radial direction of the stator core, and the 14 th slot (13 th slot) at the fourth layer in the radial direction of the stator core is positioned inside the second slot; in the first slot inside of the U-shaped conductor 100 located at the fourth layer and the fifth layer in the radial direction of the stator core, the 8 th slot (7 th slot) inside of the U-shaped conductor 100 located at the fifth layer in the radial direction of the stator core, with reference to fig. 5 to 8, in the first to fourth embodiments, the pitch between the two slot inside 301 of the U-shaped conductor 100 located at the first layer in the radial direction of the stator core 20 in each phase winding is a short pitch 5 (the 2 nd slot and the 7 th slot located at the first layer in the radial direction of the stator core in the two slot inside of the U-shaped conductor 100 located at the first layer in the radial direction of the stator core 20); with reference to fig. 9 to 11, in the fifth to seventh embodiments, the pitch between the two slot interiors 301 of the U-shaped conductors 100 located in the first radial layer of the stator core in each phase winding is the long pitch 7 (the two slot interiors of the U-shaped conductors 100 located in the first radial layer of the stator core 20 are located in the 1 st slot and the 8 th slot in the first radial layer of the name core), that is, the pitch of the U-shaped conductors 100 located in the first radial layer of the stator core in each phase winding is not equal to the pitch.
With reference to fig. 9 to 11, in the fifth to seventh embodiments of the present invention, the pitch of the U-shaped conductor 100 located in the first layer in the radial direction of the stator core in each phase winding is the long pitch 7 (the first slot of the U-shaped conductor 100 located in the first layer in the radial direction of the stator core is located in the 1 st slot and the 8 th slot in the circumferential direction of the stator core);
further, with reference to fig. 10 to 11, in sixth to seventh embodiments, the pitch of half of the U-shaped conductors located in the second and third radial layers of the stator core is a long pitch (the inside of the slots of the U-shaped conductors located in the second and third radial layers of the stator core are located in the 1 st and 8 th circumferential slots of the stator core), and the pitch of the other half of the U-shaped conductors located in the second and third radial layers of the stator core is a short pitch (the inside of the slots of the U-shaped conductors located in the second and third radial layers of the stator core are located in the 2 nd and 7 th circumferential slots of the stator core); one U-shaped conductor of one part of U-shaped conductors of the second layer and the third layer in the radial direction of the stator core in the phase winding surrounds one U-shaped conductor of the other part of U-shaped conductors of the second layer and the third layer in the radial direction of the stator core.
Alternatively, referring to fig. 9, in the fifth embodiment, the pitches of the U-shaped conductors located at the second and third layers in the radial direction of the stator core are full pitches (the two slots of the U-shaped conductors 200 located at the second and third layers in the radial direction of the stator core are located at the 1 st and 7 th slots in the circumferential direction of the stator core).
Further, with reference to fig. 9 and 11, in fifth and seventh embodiments, the pitch of half of the U-shaped conductors located in the fourth and fifth layers in the radial direction of the stator core is a long pitch (the inside of the slot of the U-shaped conductor 200 located in the fourth and fifth layers in the radial direction of the stator core is located in the 1 st slot and the 8 th slot in the circumferential direction of the stator core), and the pitch of the other half of the U-shaped conductors located in the fourth and fifth layers in the radial direction of the stator core is a short pitch (the inside of the slot of the U-shaped conductor located in the fourth and fifth layers in the radial direction of the stator core is located in the 2 nd slot and the 7 th slot in the circumferential direction of the stator core); one U-shaped conductor of a part of U-shaped conductors in the fourth layer and the fifth layer of the stator core in the radial direction surrounds one U-shaped conductor of the other part of U-shaped conductors in the fourth layer and the fifth layer of the stator core in the radial direction.
Alternatively, referring to fig. 10, in a sixth embodiment, the pitch of the U-shaped conductors located at the fourth layer and the fifth layer in the radial direction of the stator core is the full pitch 6 (the U-shaped conductors located at the fourth layer and the fifth layer in the radial direction of the stator core are located at the 1 st slot and the 7 th slot in the circumferential direction of the stator core inside the slots).
With reference to fig. 5 to 8, in the first to fourth embodiments of the present invention, the pitch of the U-shaped conductor 100 located in the first radial layer of the stator core in each phase winding is the short pitch 5 (the inside of the slot of the U-shaped conductor 100 located in the first radial layer of the stator core is located in the 2 nd and 7 th circumferential slots of the stator core);
further, with reference to fig. 7 to 8, in the third to fourth embodiments, the pitch of half of the U-shaped conductors located in the second and third radial layers of the stator core is a long pitch (the inside of the U-shaped conductors located in the second and third radial layers of the stator core are located in the 1 st and 8 th circumferential slots of the stator core), and the pitch of the other half of the U-shaped conductors located in the second and third radial layers of the stator core is a short pitch (the inside of the U-shaped conductors located in the second and third radial layers of the stator core are located in the 2 nd and 7 th circumferential slots of the stator core); one U-shaped conductor of one part of U-shaped conductors of the second layer and the third layer in the radial direction of the stator core in the phase winding surrounds one U-shaped conductor of the other part of U-shaped conductors of the second layer and the third layer in the radial direction of the stator core.
Optionally, with reference to fig. 5 and 6, in the first and second embodiments, the pitches of the U-shaped conductors located in the second and third layers in the radial direction of the stator core are the full pitch (the U-shaped conductors located in the second and third layers in the radial direction of the stator core are located in the 1 st and 7 th slots in the circumferential direction of the stator core).
Further, with reference to fig. 6 and 8, in the second and fourth embodiments, the pitch of half of the U-shaped conductors located at the fourth and fifth radial layers of the stator core is a long pitch (the inside of the U-shaped conductor slots located at the fourth and fifth radial layers of the stator core are located at the 1 st and 8 th circumferential slots of the stator core), and the pitch of the other half of the U-shaped conductors located at the fourth and fifth radial layers of the stator core is a short pitch (the inside of the U-shaped conductor slots located at the fourth and fifth radial layers of the stator core are located at the 2 nd and 7 th circumferential slots of the stator core); the U-shaped conductor in the phase winding is long-pitch and surrounds the U-shaped conductor to be short-pitch; one U-shaped conductor of a part of U-shaped conductors in the fourth layer and the fifth layer of the stator core in the radial direction surrounds one U-shaped conductor of the other part of U-shaped conductors in the fourth layer and the fifth layer of the stator core in the radial direction.
Optionally, with reference to fig. 5 and 7, in the first and third embodiments, the pitches of the U-shaped conductors located at the fourth and fifth layers in the radial direction of the stator core are full pitches (the U-shaped conductors located at the fourth and fifth layers in the radial direction of the stator core are located at the 1 st and 7 th slots in the circumferential direction of the stator core).
With reference to fig. 5 to 11, in the embodiment, the welding terminals 303 corresponding to the slot interiors 301 of the partial U-shaped conductors 100 located at the fifth layer in the radial direction of the stator core 20 in each phase winding are located at different layers in the radial direction of the stator core 20, the slot interiors 301 of the partial U-shaped conductors 100 located at the fifth layer in the radial direction of the stator core 20 are located at the fifth layer in the radial direction of the stator core (M is 5 in this embodiment), and the welding terminals 303 corresponding to the slot interiors 301 of the partial U-shaped conductors 100 located at the fifth layer in the radial direction of the stator core are located at virtual six layers in the radial direction of the stator core 20, that is, the welding terminals 303 corresponding to the slot interiors 301 (fifth layer) and the virtual six layers (virtual six layers) of the partial U-shaped conductors 100 located at the fifth layer in the radial direction of the stator core are located at different layers in the radial direction of the stator core 20; the welding ends of the inside 301 of the slots of the other U-shaped conductors 200 (and the U-shaped conductors 100 located in the first radial layer of the stator core) except for the partial U-shaped conductors located in the M radial layer of the stator core 20 in the phase winding are located in the same radial layer of the stator core 20 as the welding ends corresponding to the inside 301 of the slots, the welding ends of the inside of the slots of the U-shaped conductors 100 located in the first radial layer of the stator core and the welding ends corresponding to the inside of the slots are located in the same radial layer of the stator core, the welding ends of the inside of the slots of the U-shaped conductors 200 located in the third radial layer of the stator core and the welding ends corresponding to the inside of the slots are located in the same radial layer of the stator core, the welding ends of the inside of the slots of the U-shaped conductors 200 located in the fourth radial layer of the stator core and the welding ends corresponding to the inside of the slots are located in the same radial layer of the stator core, the welding end of the inside of the groove of the U-shaped conductor 200 positioned at the fifth layer in the radial direction of the stator core and the corresponding welding end of the inside of the groove are positioned at the same layer in the radial direction of the stator core.
Illustratively, as shown in fig. 12, the U-phase conductor lead end has a U-phase terminal, the V-phase conductor lead end has a V-phase terminal, the W-phase conductor lead end has a W-phase terminal, and the U-phase conductor lead end, the V-phase conductor lead end, and the W-phase conductor lead end use connectors to perform neutral point connection, that is, to complete the star connection of the phase windings of the odd-numbered motor in series, as shown in fig. 13, the U-phase conductor lead end is connected to the V-phase conductor lead end, the V-phase conductor lead end is connected to the W-phase conductor lead end, and the W-phase conductor lead end is connected to the U-phase conductor lead end, that is, to complete the delta connection of the phase windings of the odd-numbered motor in series.
The embodiment also provides a motor, which comprises a rotor and the motor stator, and the motor adopting the motor stator can reduce the production cost and improve the production efficiency.
The utility model discloses in every utmost point every looks slot number the stator slot number/motor pole number/looks number, the pole distance the stator slot number/motor pole number every utmost point every looks slot number the looks number, the quantity in groove is not limited only 48 grooves, can also be the groove of other quantity, for example: the number of slots of each phase of each pole is 2, the corresponding slot poles of the three-phase motor are matched with a 6-pole 36 slot, a 8-pole 48 slot, a 10-pole 60 slot, a 12-pole 72 slot, a 16-pole 96 slot and the like, and the pole distance is 6; the number of slots of each phase of each pole is 3, and the corresponding three-phase motor slot poles are matched with a 6-pole 54 slot, an 8-pole 72 slot, a 10-pole 90 slot, a 12-pole 108 slot, a 16-pole 144 slot and the like, which are not limited one by one.
The embodiment of the utility model provides a motor includes the motor stator in above-mentioned embodiment, consequently the embodiment of the utility model provides a motor also possesses the beneficial effect that the above-mentioned embodiment described, no longer gives unnecessary details here.
In the description of the embodiments of the present invention, unless otherwise explicitly specified or limited, the terms "connected" and "connected" should be interpreted broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; they may be mechanically or electrically connected, directly or indirectly through intervening media, or may be interconnected between two elements. The above-described meaning of what is specifically intended in the present invention can be understood in specific instances by those of ordinary skill in the art. Finally, it should be noted that the above description is only a preferred embodiment of the present invention and the technical principles applied.
It will be understood by those skilled in the art that the present invention is not limited to the embodiments illustrated herein, but is capable of various obvious changes, rearrangements and substitutions without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.