Claims:1 A coil assembly for an induction sealing head, the coil assembly comprising: a set of four planar spiral coil segments, each operatively coupled to one another and arranged in one line such that the center of each of the four planar spiral coil segment coincides with a conveyor axis associated with the sealing head, wherein the four planar spiral coil segments have different predefined dimensions based on dimension of one or more foils to seal one or more containers.

2. The coil assembly as claimed in claim 1, wherein the set of four planar spiral coil segments comprises a first square-shaped coil having a predefined inner cross-section area where no conductor is present, and a predefined outer cross-section area having a first predefined number of turns.

3. The coil assembly as claimed in claim 2, wherein the set of four planar spiral coil segments comprises a second circular-shaped coil operatively coupled to the first coil, wherein the second coil has a first predefined inner diameter where no conductor is present, and a first predefined outer diameter having a second predefined number of turns.

4. The coil assembly as claimed in claim 3, wherein the first square-shaped coil has the predefined inner cross-section area of 80 mm2, and 8 number of turns in the outer cross-section area, and wherein the second circular-shaped coil has the predefined inner diameter of 60 mm, and 7 number of turns in the outer diameter.

5. The coil assembly as claimed in claim 3, wherein the set of four planar spiral coil segments comprises:
a third circular-shaped coil operatively coupled to the second coil and having a third predefined diameter and a third predefined number of turns; and
a fourth circular-shaped coil operatively coupled to the third coil and having a fourth predefined diameter and a fourth predefined number of turns.

6. The coil assembly as claimed in claim 5, wherein the third coil has 7 number of turns, and the fourth coil has 5 number of turns.

7. The coils assembly as claimed in claim 1, wherein the coil assembly comprises a set of four flux concentrators made of ferrite configured on each of the four planar coil segments.

8. The coils assembly as claimed in claim 1, wherein the one or more foils are selected from a square-shaped foil, a rectangular-shaped foil, and a circular-shaped foil, having a foil size ranging from 18 to 145 mm.

9. An induction sealing head for sealing one or more containers, the sealing head comprising:
a housing comprising the coil assembly as claimed in claim 1; and
a power controller electrically coupled to the coil assembly, wherein the power controller is configured to supply electrical power having predefined electrical attributes to the coil assembly, which correspondingly energizes the set of four planar spiral coil segments to facilitate any or a combination of sealing of the one or more foils over the one or more containers, and removal of wax from the one or more sealed containers.

10. The sealing head as claimed in claim 9, wherein the absence of conductor in an inner cross-section area of each of the four planar spiral coil segments restricts formation of hot spots in the coil assembly and the one or more foils, and wherein the set of four planar spiral coil segments facilitates maximum utilization of coupling parameter (Kc) associated with the coil assembly.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates to the field of induction sealing systems, and more particularly the present disclosure relates to an efficient and improved coil assembly for an induction sealing head for energy-efficient sealing of a wide range of containers having different foil sizes and shapes.

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] Induction heating process is used for sealing plastic and glass bottles in the packaging industry. The induction sealing process is increasingly used as a packaging solution for diverse products, including but not limited to, pharmaceutical, petroleum, food and beverage items, etc. Over the time, size of aluminum foils used for sealing containers has varied widely ranging from 18 to 145 mm, and are available in different shapes as well depending on the container. In the induction heat-based sealing process, a coil head (also known as a sealing head) acts as the heart of the process. When the coil head is in an energized condition, it acts as a facilitator of energy transfer to the foils. For small foils, sealing and wax removal together are simple. However, when the diameter of foil increases. the process starts behaving as under-actuated, making and assuring both activities difficult.
[0004] In continuous-duty induction sealing, the coil head is kept in an energized condition. The energized coil acts as a facilitator for energy transfer to each foil. When containers with foil travel underneath the coil head, the power is transferred to aluminum foil by induction principles. The same is used to seal plastic and glass containers. By transferring power to thin aluminum foil, the process serves two purposes. Firstly, sealing of container with the lip of foil, and secondly, the removal of wax from the complete top surface of the foil. Prior to sealing, the wax keeps the cardboard and the foil together. In the majority of controllers available in the market, the bonding of foil is ensured by induction effect whereas removal of wax was by thermal conduction. Wax removal by thermal conduction is a slow process. This type of wax removal is a hindrance of high-speed quality sealing.
[0005] IGBT-based power circuit 100 of a typical controller is shown in FIG. 1. The tank circuit is laid in a series configuration. A phased lock loop (PLL) is used to track the resonant frequency and the chopper was used for power control. PWM chopper plus PLL together ensured ZVZCS operation of the inverter where the high-frequency loss was negligible and conduction loss was reduced. Two waveforms under extreme loading conditions for the disclosed power circuit are shown in FIG. 2A and 2B. Inverter output at 70A coil current and corresponding gate signals, under a no-load condition, is shown in FIG. 2A, and for the loaded condition while sealing containers using 120 mm diameter is shown in FIG. 2B.
[0006] It would be obvious for a person skilled in the art that the quantum of power POUT transferred to foils depends on four parameters. . L1 is the inductance of coil head, iL is current through it, fs is the frequency of iL and the parameter Kc depends on coupling between the coil and foil(s). Req represents the total load resistance of foil(s) reflected the tank circuit. Expressions of Req and Leq are . Lfoil is foil inductance and Rfoil is its resistance, M is effective mutual inductance between coil and foil and . Expression of square wave inverter output voltage Vpri is . Rsr is the equivalent resistor of tank capacitor Cr, rac is ac resistance of coil and n is turns-ratio of transformer TR. The power output from the half-bridge ZVZCS inverter is . Major power loss Ptank takes place in the tank circuit, which may be expressed as . In a ZVZCS converter, like Ptank, the conduction loss is dominant, total power loss in the controller is more if coil current is increased.
[0007] In existing induction sealing techniques, initially, the coil was water-cooled. Now, with the availability of a wide range of litz-wire conductors, cap sealers are now air-cooled. Manufacturing of water-cooled coil in complex geometric configuration was difficult, meeting wide range sealing prospect by a single coil head was not possible. On the other hand, the current density of litz wire-based coil was much less, more turns were added to get equivalent sealing effectiveness.
[0008] The coil used in existing induction sealing techniques, was either circular spiral or rectangular as shown in FIGs 3A and 3B. However, here as well, wide range sealing was not possible. Initially, similar water-cooled geometries were made as shown in FIG. 3A. Further, the coil dimension became large as shown in FIG. 3B. However, to have a similar impact on power output ( ) on foil surface at less current, more turns were added in the coil, which correspondingly increased the value of inductance of the coil.
[0009] Typical flux density (B) distribution beneath the coils of FIGs. 3A and 3B are shown in FIG. 4. As shown, the B is more at the center along the conveyor axis, which gradually decreases outwardly. As a result, the impact of heating may be more on foils around the conveyor axis and less heating may be there at the periphery perpendicular to the conveyor axis. Further, there may be unequal heating, it could result undersealing in some zone, burning or overheating in some areas. Moreover, wax removal from the top surface may be a problem.
[0010] Initially, only limited pharma and oil industries were using induction sealing processes. The range of diameter of foils was small, in the range of 35 to 50 mm. Both coil assemblies of FIGs. 3A and 3B, were good enough to ensure sealing these bottles. Gradually, several other application areas moved towards induction cap sealing where the cap dimension and its arrangement or location, foil sizes, etc. started becoming wide and complex. Coil arrangements of FIGs 3A and 3B, were not sufficient for a wide range of quality sealing. As shown in FIGs. 5A to 5C, several sealing issues existed, particularly, while using large-diameter foils. In some applications, it was tackled by the mechanical rotation arrangement of the coil head. However, for each bottle size, the coil head needed to be rotated by a certain fixed angle. It needed frequent process adjustment. The process setting was cumbersome and energy inefficient.
[0011] Thus, the existing coil of FIGs. 3A and 3B had various issues such as proper sealing was not possible for containers using large size foils (greater than 75 mm diameter), overheating/burning was noticed on foil area around the conveyor axis, undersealing or less heating was noticed on foil areas at the periphery of the minor axis, and removal from the center of large foil was not successful, therefore, it required extensive quality inspection, and, for critical applications, it was costly.
[0012] Another induction heating-based sealing technology available in the art is the multi-axis multi-segmented coil that was developed by M/S. Electronics Devices Worldwide Private Limited (EDWPL). The multi-axis multi-segmented coil of EDWPL is useful for circular foils in the range of 20-120 mm diameter and was capable of solving issues related to a coil of FIGs 3A and 3B. However, the energy utilization of each coil segment in the disclosed multi-axis multi-segmented coil is not optimum, and tuning of the production process is required to be done mechanically. Besides, the disclosed multi-axis multi-segmented coil is not equally effective for rectangular foils.
[0013] FIG. 6 illustrates, the disclosed multi-axis multi-segmented coil 600 of EDWPL. The coil 600 of EDWPL consisted of four similar spiral coil segments placed in three different axes. Two segments of coils placed along the conveyor axis are primarily to ensure sealing circular foils till foil size of 120 mm as shown in FIG. 7. Other two segments are used mostly for removing the wax spatially and strengthening sealing on the minor axis periphery. The disclosed invention resolved sealing issues completely using foil size in the range 20-120 mm. The coil head 600 helped distribute power output on moving foil spatially. It further avoided over burning or undersealing and resulted in zero-defect sealing. There was a paradigm shift in this approach where sealing and wax removal, both were dominantly executed by induction effect, faster wax removal helped improve the sealing speed. The lateral benefits were too many. Compared to results obtained by coil heads of FIGs. 3A and 3B, disclosed invention 600 of EDWPL of FIG. 6 consumed less power, when compared with contemporary controllers, and increased productivity significantly.
[0014] One of the drawbacks associated with the disclosed invention 600 of EDWPL is that when the foils move on the conveyor axis, the utilization of each coil segment is not maximized. Here, the wide range sealing is executed by changing the value of KC, it changes on a number of process variables as shown in FIGs. 8A to 8C. The value of coil current is kept mostly constant across all applications. However, being an online process, the coil-head is always kept energized. Therefore, the power loss in no-load or light load conditions is the same as that for maximum load conditions as shown in Table 1.
TABLE-1: POWER LOSS OF THE CONTROLLER AT EXTREME LOADING CONDITIONS
No-load Full load
Coil current, A 100 100
Primary current, A 14.2 14.2
Loss in Q1+Q2, W 20 22.0
Loss in C2 + C3, W 0.3 0.3
Loss in TR, W 6 10
Loss in Q3, W 8 16
Loss in D1 16 6
Loss in L3 5.0 5.0
Power loss in coil head L1, W 100.0 100.0
Power loss in tank capacitor Cr, W 18.3 18.3
Total power loss, W 173.6 177.6

[0015] As a result, the energy utilization of the disclosed invention 600 of EDWPL needs improvement. Moreover, the coil used in FIG. 6 (used in the disclosed invention of EDWPL) is suitable only for circular foils and is not equally effective for rectangular foils.
[0016] For a particular controller with a fixed coil head, due to the application of load, the change in L1 or fs was not significant. In actual practice, the value of Pout is influenced either by changing the value of iL and or KC. For a particular sealing application, the coil current iL is kept constant. The effective resistance Req is related to coupling parameter Kc . For fixed iL, the instantaneous value of Pout depends on diameter dfoil of foil (see FIG. 8A), distance hfc between foil and coil (see FIG. 8B), and location of a moving foil relative to coil segment (see FIG. 8C). Each would influence the value of KC accordingly.
[0017] In the production of the existing coil of FIG. 6, the coil current is not varied. The coil is kept energized at rated current, no-load loss is significant (see Table 1). If the current is reduced, the impact of out-of-axis coil segments L1-2 and L1-3 on Pout would be insignificant. Therefore, to ensure both sealing and wax removal, the value of KC is varied (see FIG. 8A). For sealing with moderate to large diameter foils, the value of hfc is kept large. However, because the value of iL is kept at its rated value, irrespective of foil size, the power loss in the coil and power controller would be large. Secondly, the coil used in FIG. 6 has four circular segments placed on three different axes. Each segment is connected in series, the same current flows through each coil. However, foils move on the conveyor axis where the impact of electro-magnetic induction is maximum. Therefore, more power is drawn through the central segments L1-1 and L1-4. For small foils, the services of L1-2 and L1-3 are hardly utilized.
[0018] The coil 600 of FIG. 6 remains under-utilized where each coil would dissipate the same power loss. Therefore, the energy utilization of the coil was not attractive, so was the case for the power controller as well. For sealing of moderate to large size containers, to avoid burning prospect the value of dfc (greater than equal to 18 mm) is kept large. It causes large power loss in the power controller. It was practically found that the coil arrangement 600 of FIG. 6 may result in quality issues for a wider application range (i.e for sealing with 18 to 145 mm dia. foil). Besides, sealing of containers using large diameter (=125 mm) foils was not possible.
[0019] There is, therefore, a need to overcome the above drawback, limitations, and shortcomings associated with the existing coil and induction sealing techniques, and provide an alternate improved approach for energy-efficient sealing of a wide range of containers having different foil sizes and shapes ranging from 18 to 145 mm, utilize the maximum value of coupling parameter KC in all applications, avoid any hot spot in any coil segment, and optimally reduce the power loss in the power controller as well as in the induction sealing coil head.

OBJECTS OF THE PRESENT DISCLOSURE
[0020] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0021] It is an object of the present disclosure to enable energy-efficient sealing of a wide range of containers having different foil sizes and shapes ranging from 18 to 145 mm.
[0022] It is an object of the present disclosure to provide an efficient and improved coil assembly for an induction sealing head that is capable of providing energy-efficient sealing of a wide range of containers having different foil sizes and shapes, as well as enabling removal of wax.
[0023] It is an object of the present disclosure to provide an induction sealing coil head or a coil assembly that utilizes each coil segment efficiently and optimally.
[0024] It is an object of the present disclosure to provide a coil assembly for induction sealing coil head that utilizes the maximum value of coupling parameter KC in all applications.
[0025] It is an object of the present disclosure to ensure sealing of different applications by setting the coil current to make the process adjustment easy.
[0026] It is an object of the present disclosure to provide a coil assembly for induction sealing coil head that restricts the formation of any hot spot in any of the coil segments of the coil assembly.
[0027] It is an object of the present disclosure to reduce the power loss in the power controller as well as in the induction sealing coil head.

SUMMARY
[0028] The present disclosure relates to an efficient and improved coil assembly for an induction sealing head (coil head) for energy-efficient sealing of a wide range of containers having different foil sizes and shapes.
[0029] An aspect of the present disclosure pertains to a coil assembly for an induction sealing head that is equipped to seal one or more containers. The coil assembly may comprise four planar spiral coil segments, each operatively coupled to one another and arranged in one line such that the center of each of the four planar spiral coil segments coincides with a conveyor axis associated with the sealing system, to ensure maximum utilization of each coil segments. As the center of each coil segment coincides with the conveyor axis, the flux of each coil gets maximally coupled with the moving foils beneath them, which makes the impact of Kc on the coil assembly significantly less.
[0030] In an aspect, the diameter of each coil segment may be different based on the dimension of the foil and container. The coil assembly may comprise a square-shaped large coil with a large void around its center, a circular large coil with a significantly large inner diameter, a moderate size circular coil with a small inner diameter, and a small size coil with a small inner diameter.
[0031] In an aspect, the first square-shaped large coil segment may have no coil turn up to 80 mm2. The functional of the first segment may be to perform major sealing responsibility using a wide range of foil diameters. The square-shaped coil increases the travel time of the peripheral foil area perpendicular to the travel axis of each large foil to boost strong and more uniform sealing. The coil may also avoid saturation of power controller plus overheating along the central line, as there is no conductor present till 80 mm2 inside. This may allow sealing of rectangular and/or square-shaped containers as well may boast for sealing much wider geometry of foils as well. In addition, the absence of any conductor till inner 80 mm2. reduces the impact of proximity effect on the first coil segment, and the prospect of hot spot is avoided.
[0032] In an aspect, the second circular large coil segment may majorly function like the first coil segment, where there is no coil turn till 30 mm diameter. The second coil segment may enable sealing activity, and may also assist in the removal of wax from the periphery of the foils. Further, the absence of any conductor till the inner 30 mm. reduces the impact of proximity effect on the second coil segment, and the prospect of hot spot is avoided.
[0033] In an aspect, the third moderate size circular coil segment, and the fourth small size coil segment may primarily affect the removal of wax at the center of large foils. They are also useful to boost the sealing aspect of small-sized foils where wax removal takes place mostly by thermal conduction. The prospect of hot spot is also less in the third and fourth coil segments because their diameter and number of turns are less.
[0034] Accordingly, the efficient and optimized configuration or arrangement of the coils segments in the proposed coil assembly or sealing coil head of the present invention may enable energy-efficient sealing of a wide range of containers having different foil sizes and shapes, ranging from 18 to 145 mm, with maximum utilization of coupling parameter (Kc) associated with the coil assembly and reduced losses in the corresponding power controller. Besides, the absence of a conductor in an inner cross-section area of each of the four coil segments restricts the formation of hot spots in the coil assembly as well as the foils.

BRIEF DESCRIPTION OF DRAWINGS
[0035] 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. The diagrams are for illustration only, which thus is not a limitation of the present disclosure.
[0036] 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.
[0037] FIG. 1 illustrates an exemplary schematic diagram of a power controller used in induction cap sealing.
[0038] FIGs. 2A and 2B illustrate exemplary output waveforms of the power controller of FIG. 1 in no-load, and loaded conditions, respectively.
[0039] FIGs. 3A and 3B illustrate an exemplary view of a typical planar circular spiral coil, and a planar rectangular coil, respectively.
[0040] FIG. 4 illustrates an exemplary depicting distribution of normalized flux density below different coil heads of FIGs. 3A and 3B.
[0041] FIGs. 5A to 5C illustrate exemplary view of containers sealed by coils coil heads of FIG. 3A and 3B.
[0042] FIG. 6 illustrates an exemplary view of the existing coil assembly developed by EDWPL.
[0043] FIG. 7 illustrates an exemplary view of the containers sealed by the coil assembly of FIG. 6.
[0044] FIGs. 8A to 8C illustrate the influence of process parameters such as foil diameter, height between foil and coil, and traveling of foil beneath the coil segments of FIG. 6, on the value of Kc.
[0045] FIG. 9 illustrates an exemplary view of the proposed sealing head with the coil assembly, in accordance with an embodiment of the present disclosure.
[0046] FIG. 10 illustrates an exemplary view of the proposed sealing head with ferrite flux concentrators, in accordance with an embodiment of the present disclosure.
[0047] FIGs. 11A to 11D illustrate an exemplary view of the first coil segment, second coil segment, third coil segment, and fourth coil segment associated with the sealing head or coil assembly of FIG. 9, in accordance with an embodiment of the present disclosure.
[0048] FIG. 12 illustrates an exemplary photographic view of a 2 KW power controller used with the proposed sealing head of FIG. 9.
[0049] FIG. 13A to 13D illustrates an exemplary photographic view of the proposed sealing head of FIG. 10.
[0050] FIG. 14 illustrates an exemplary photographic view of a wide range of containers being sealed by the proposed sealing head of FIGs. 9 and 10.
[0051] FIG. 15 illustrates an exemplary graph depicting a comparative statement on process performance (foil size vs production speed) between the proposed sealing head of FIG. 9 (new coil) and the existing sealing head of FIG. 6 (old coil).
[0052] FIG. 16 illustrates an exemplary graph depicting a comparative statement on process setting of foil diameter between the proposed sealing head of FIG. 9 and the existing sealing head of FIG. 6
[0053] FIG. 17 illustrates an exemplary graph depicting a comparative statement on coil current for maximum conveyor speed of >=14 m/min between the proposed sealing head of FIG. 9 and the existing sealing head of FIG. 6.
[0054] FIG. 18 illustrates an exemplary graph depicting a comparative statement of power loss in the power controller for different sealing applications between the proposed sealing head of FIG. 9 and the existing sealing head of FIG. 6.
[0055] FIG. 19 illustrates an exemplary graph depicting a comparative statement on power consumed at full production capacity for different foils for maximum conveyor speed of 14 m/min between the proposed sealing head of FIG. 9 and the existing sealing head of FIG. 6

DETAILED DESCRIPTION
[0056] 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.
[0057] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.
[0058] The embodiments of the present disclosure relate to an efficient and improved coil assembly for an induction sealing head for energy-efficient sealing of a wide range of containers having different foil sizes and shapes.
[0059] According to an aspect, the present disclosure elaborates upon a coil assembly for an induction sealing head that is equipped to seal one or more containers. The proposed coil assembly can include a set of four planar spiral coil segments, each operatively coupled to one another and arranged in one line such that the center of each of the four planar spiral coil segments coincides with a conveyor axis associated with the sealing head. The four planar spiral coil segments can have different predefined dimensions based on the dimension of one or more foils to seal one or more containers.
[0060] In an embodiment, the set of four planar spiral coil segments can include a first square-shaped coil having a predefined inner cross-section area where no conductor is present, and a predefined outer cross-section area having a first predefined number of turns.
[0061] In an embodiment, the set of four planar spiral coil segments can include a second circular-shaped coil operatively coupled to the first coil. The second coil can have a first predefined inner diameter where no conductor is present, and a first predefined outer diameter having a second predefined number of turns.
[0062] In an embodiment, the first square-shaped coil can have the predefined inner cross-section area of 80 mm2, and 8 turns in the outer cross-section area. The second circular-shaped coil can have the predefined inner diameter of 60 mm, and 7 turns in the outer diameter.
[0063] In an embodiment, the set of four planar spiral coil segments can include a third circular-shaped coil operatively coupled to the second coil and having a third predefined diameter and a third predefined number of turns, and a fourth circular-shaped coil operatively coupled to the third coil and having a fourth predefined diameter and a fourth predefined number of turns.
[0064] In an embodiment, the third coil can have 7 turns, and the fourth coil can have 5 turns.
[0065] In an embodiment, the coil assembly can include a set of four flux concentrators made of ferrite configured on each of the four planar coil segments.
[0066] In an embodiment, the one or more foils can be selected from a square-shaped foil, a rectangular-shaped coil, and a circular-shaped foil, having a foil size ranging from 18 to 145 mm.
[0067] According to another aspect, the present disclosure elaborates upon an induction sealing head for sealing one or more containers. The sealing head can include a housing accommodating the proposed coil assembly, and a power controller electrically coupled to the coil assembly. The power controller can be configured to supply electrical power having predefined electrical attributes to the coil assembly, which can correspondingly energize the set of four planar spiral coil segments to facilitate any or a combination of sealing of the one or more foils over the one or more containers, and removal of wax from the one or more sealed containers.
[0068] In an embodiment, the absence of a conductor in an inner cross-section area of each of the four planar spiral coil segments can restrict the formation of hot spots in the coil assembly and the one or more foils. Further, the set of four planar spiral coil segments can facilitate maximum utilization of coupling parameter (Kc) associated with the coil assembly.
[0069] Referring to FIG. 9 and 10, the proposed coil assembly 900 for the induction sealing coil head 1000 (also referred to as sealing head or coil head 1000, herein) is disclosed. The coil assembly 900 can include a set of four planar spiral coil segments 902 to 908 made of an electrically conductive material. Each of the coil segments 902 to 908 can be operatively coupled to one another and arranged in one line such that the center of each of the four planar spiral coil segments 902 to 908 coincides with a conveyor axis associated with the sealing head 1000. In an embodiment, the set of four planar spiral coil segments 902 to 908 can include a first square-shaped coil 902 (segment A), a second circular-shaped coil 904 (segment B), a third circular-shaped coil 906 (segment C), and a fourth circular-shaped coil 908 (segment D) coupled to one another in series, and arranged in one line along the conveyor axis. The four planar spiral coil segments 902 to 908 can have different predefined dimensions based on the dimension of foils to seal the containers.
[0070] In an exemplary embodiment, the foils can be selected from a square-shaped foil, a rectangular-shaped foil, and a circular-shaped foil, having a foil size ranging from 18 to 145 mm
[0071] In an embodiment, the first square-shaped coil 902 can have a predefined inner cross-section area where no conductor is present, and a predefined outer cross-section area having a first predefined number of turns. The second circular-shaped coil 904 can be operatively coupled to the first coil 902. The second coil 904 can have a first predefined inner diameter where no conductor is present, and a first predefined outer diameter having a second predefined number of turns. The third circular-shaped coil 906 can be operatively coupled to the second coil 904 and can have a third predefined diameter and a third predefined number of turns. The fourth circular-shaped coil 908 can be operatively coupled to the third coil 906 and can have a fourth predefined diameter and a fourth predefined number of turns.
[0072] In an exemplary embodiment, the first square-shaped coil 902 can have the predefined inner cross-section area of 80 mm2, and 8 turns in the outer cross-section area. The second circular-shaped coil 904 can have a predefined inner diameter of 60 mm, and 7 turns in the outer diameter. In an embodiment, the third coil 906 can have 7 turns, and the fourth coil 908 can have 5 turns.
[0073] In an embodiment, the first coil 902 can be a square-shaped large coil with a large void around its center. The second coil 904 can be a circular large coil with a significantly large inner diameter. The third coil 906 can be a moderate size circular coil with a small inner diameter. The fourth coil 908 can be a small size coil with a small inner diameter.
[0074] Referring to FIG. 11A, in an embodiment, the first square-shaped large coil 902 can have no coil turn up to 80 mm2. The functional of the first coil 902 can be to perform major sealing responsibility using a wide range of foil diameters. The square-shaped coil 902 increases the travel time of the peripheral foil area perpendicular to the travel axis of each large foil to boost strong and more uniform sealing. The first coil 902 can also avoid saturation of power controller and overheating along the central line, as there is no conductor present till 80 mm2 inside. This can allow sealing of rectangular and/or square-shaped containers as well may boast for sealing much wider geometry of foils as well. In addition, the absence of any conductor till inner 80 mm2 in coil 902, reduces the impact of proximity effect on the first coil, and the prospect of hot spot is avoided.
[0075] Referring to FIG. 11B, in an embodiment, the second circular large coil 904 can majorly function like the first coil segment 902, where there is no coil turn till 30 mm diameter. The second coil 904 can enable sealing activity, and can also assist in the removal of wax from the periphery of the foils. Further, the absence of any conductor till inner 30 mm in the second coil 904. reduces the impact of proximity effect on the second coil 904, and the prospect of hot spot is avoided.
[0076] Referring to FIG. 11C and 11D, in an embodiment, the third moderate size circular coil 906, and the fourth small size coil 908 can primarily affect the removal of wax at the center of large foils. Coils 906 and 908 can also be useful to boost the sealing aspect of small-sized foils where wax removal takes place mostly by thermal conduction. The prospect of hot spot is also less in the third coil 906 and fourth coil 908 because their diameter and number of turns are less.
[0077] Referring to FIG. 10, 13A to 13D, the proposed coil head 1000 can also include a set of four flux concentrators 1002 to 1008 made of ferrite configured on each of the four planar coil segments 902 to 908. The flux concentrator 1002 to 1008 can be configured on top of the coil segments 902 to 908 to facilitate alteration of the magnetic field produced by the energized coil segments, which may help direct or intensify the magnetic flux towards the foils moving beneath the sealing head. As illustrated, the ferrite cores 1002 to 1008 can be configured over the coil segments and a set of clamping means 1010 to 1018 can be used to fix the ferrite cores 1002 to 1008 over the corresponding coil segments 902 to 908 of the coil head 1000. Further, in another embodiment, the sealing head 1000 can include a cooling fan 1018 configured with the coil segments 902 to 908 to control their cooling as required.
[0078] In an embodiment, the proposed sealing head 1000 can include a housing 910 that accommodates the proposed coil assembly 900. Housing 910 can be positioned at a predefined height above the conveyor associated with the induction sealing system. The position of the housing 910 or the coil head 1000 can be adjusted based on the height of the containers moving over the conveyor. Further, a power controller can be electrically coupled to the coil assembly, which can be configured to supply electrical power having predefined electrical attributes to the coil assembly 900 to correspondingly energize the set of four planar spiral coil segments 902 to 908. The energization of the coil assembly 900 by the power controller 100 can facilitate any or a combination of sealing of the foils over the containers, and removal of wax from the foils of sealed containers.
[0079] In an implementation, for validation of the proposed coil assembly 900 and sealing head 1000, a 2.0 kW power controller was developed as shown in FIG. 12 having the circuitry as shown in FIG. 1. Sealing of wide range bottles as shown in FIG. 14 was validated and accomplished.
[0080] Fig. 15 shows the comparative performance of the wide range sealing capability of the proposed coil assembly 900 with that of the coil assembly 600 of FIG. 6. The proposed coil assembly 900 was able to cater to a much wider range of applications compared to the coil assembly 600 of FIG. 6. Besides, due to distributed nature of B (caused by the absence of any current-carrying conductor inside the large foils), the proposed coil assembly 900 was able to seal all applicable ranges where the distance between the coil and the foil is not varied much (only 2-5 mm). Moreover, as shown in FIG. 16, the reduced value of dfc in the proposed coil assembly 900 compared to the coil assembly 600 of FIG. 6, improved the value of KC.
[0081] The higher value of KC ensured sealing of containers at reduced current, particularly, for moderate to large size containers. To ensure quality sealing, the value of coil current needed for sealing using foils of different sizes is shown comparatively in FIG. 17. The power loss in the coil assembly 9000 was significantly reduced. Besides, the current needed gradually reduce as foil diameter increased in the present invention 900. However, for easy presentation, the calculated value of power loss in a power converter in three discrete current ranges is shown in Table 2.
TABLE 2: LOSS IN POWER CONTROLLER IN THREE DISCRETE CURRENT ZONES
Coil current 100 A Coil current 70 A Coil current 50 A
No-load Full load No-load Full load No-load Full load
Range of foil dia., mm 20-45 55-85 95-145
Primary current, A 14.3 10 7.14
Loss in Q1+Q2, W 20 22 13.0 14.5 7.1 8.2
Loss in C2 + C3, W 0.3 0.15 0.1
Loss in TR, W 6 10 3 7 1.5 5.5
Loss in Q3, W 7 17 4.9 7 3.5 5
Loss in D1 16 5 10.0 3.5 7.5 3.45
Loss in L3 5.0 5.0 2.5 2.5 1.25 1.25
Power loss in L1, W 100 49 25
Power loss in Cr, W 18.3 9.0 4.6
Total power loss, W 172.6 177.6 91.6 92.7 50.5 53.1
[0082] The power loss vs foil diameter comparison between the proposed coil assembly 900 and coil assembly 600 of FIG. 6 is shown in FIG. 18. And, finally, the power consumed in each application for respective rated capacity between the proposed coil assembly 900 and coil assembly 600 of FIG. 6 is shown in FIG. 19.
[0083] It is to be appreciated by a person skilled in the art that the efficient and optimized configuration or arrangement of the coils segments 902 to 908 in the coil assembly 900 or sealing coil head 1000 of the present invention has helped achieve energy-efficient sealing of a wide range of containers having different foil sizes and shapes, ranging from 18 to 145 mm, with maximum utilization of coupling parameter (Kc) associated with the coil assembly 900 and reduced losses in the corresponding power controller. Moreover, the absence of coil or conductor in an inner cross-section area of each of the four planar spiral coil segments 902 to 908 restricts the formation of hot spots in the coil assembly 900 as well as the foils.
[0084] Moreover, in interpreting the specification, 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. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
[0085] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0086] The proposed invention enables energy-efficient sealing of a wide range of containers having different foil sizes and shapes ranging from 18 to 145 mm.
[0087] The proposed invention provides an efficient and improved coil assembly for an induction sealing head which is capable of providing energy-efficient sealing of a wide range of containers having different foil sizes and shapes, as well as the removal of wax.
[0088] The proposed invention provides an induction sealing coil head or a coil assembly that utilizes each coil segment efficiently and optimally.
[0089] The proposed invention provides a coil assembly for induction sealing coil heads that utilize the maximum value of coupling parameter KC in all applications.
[0090] The proposed invention ensures sealing of different applications by setting the coil current to make the process adjustment easy.
[0091] The proposed invention provides a coil assembly for induction sealing coil head that restricts the formation of any hot spot in any of the coil segments of the coil assembly.
The proposed invention reduces the power loss in the power controller as well as in the induction sealing coil head.
[0092] The proposed invention reduces the power loss in the power
controller as well as in the induction sealing coil head.