Method of manufacture for a heater assembly for use with a liquid filled cartridge

Abstract

There is provided a method of manufacturing a heater assembly for an aerosol generating system, including providing a flexible wick; applying tension to the flexible wick; assembling a heating element around the flexible wick; and releasing the tension from the flexible wick.

Claims

1. A method of manufacturing a heater assembly for an aerosol-generating system, comprising: providing a flexible wick; applying tension to the flexible wick; assembling a heating element around the flexible wick; releasing the tension from the flexible wick; and cutting the flexible wick, wherein the flexible wick is cut before the releasing of the tension from the flexible wick.

2. The method of manufacturing a heater assembly according to claim 1, wherein the applying tension to the flexible wick comprises holding the flexible wick between two pairs of gripping elements.

3. The method of manufacturing a heater assembly according to claim 2, wherein the releasing of the tension from the flexible wick comprises releasing at least one of the two pairs of gripping elements.

4. The method of manufacturing a heater assembly according to claim 1, wherein the heater assembly comprises a liquid storage portion containing or configured to contain a liquid aerosol-forming substrate, and wherein the flexible wick is assembled to the liquid storage portion, or a part of the liquid storage portion, before the releasing of the tension from the flexible wick.

5. The method of manufacturing a heater assembly according to claim 4, wherein the liquid storage portion comprises a main portion and a cap portion, the method further comprising assembling the main portion and the cap portion together after the main portion has been filled with the liquid aerosol-forming substrate.

6. The method of manufacturing a heater assembly according to claim 5, further comprising assembling the flexible wick to the cap portion before the releasing of the tension from the flexible wick.

7. The method of manufacturing a heater assembly according to claim 5, wherein the cap portion comprises a plurality of pieces, the method further comprising joining the plurality of pieces together around the flexible wick.

8. The method of manufacturing a heater assembly according to claim 4, wherein the heater assembly further comprises one or more electrical contact elements that are connected to the heating element and configured to provide, in use, an electrical connection between the heating element and external circuitry, the method further comprising mounting the one or more electrical contact elements to the liquid storage portion before connecting the one or more electrical contact elements to the heating element.

9. The method of manufacturing a heater assembly according to claim 8, wherein the electrical contact elements are connected to the heating element before the releasing of the tension from the flexible wick.

10. The method of manufacturing a heater assembly according to claim 8, further comprising mounting the one or more electrical contact elements to a portion of the liquid storage portion, before the portion of the liquid storage portion is fixed relative to the flexible wick.

11. The method of manufacturing a heater assembly according to claim 1, wherein the heating element is a coil of electrically resistive wire.

12. The method of manufacturing a heater assembly according to claim 11, further comprising pressing or crimping the coil of electrically resistive wire against the flexible wick in a pressing or crimping operation.

13. The method of manufacturing a heater assembly according to claim 12, wherein the pressing or crimping operation is performed before the releasing of the tension from the flexible wick.

14. The method of manufacturing a heater assembly according to claim 1, wherein the heating element is assembled around the flexible wick by rotating the flexible wick.

15. A heater assembly manufactured in accordance with a method according to claim 1.

Description

(1) Embodiments of the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

(2) FIG. 1 is an exploded, perspective view of a heater assembly suitable for use in an aerosol-generating system;

(3) FIG. 2 is a schematic illustration of a first manufacturing process for assembling a heater assembly of the type shown in FIG. 1;

(4) FIG. 3 is a schematic illustration of a second assembly process for manufacturing a heater assembly of the type shown in FIG. 1;

(5) FIG. 4 is a schematic illustration of a third assembly process for manufacturing a heater assembly of the type shown in FIG. 1;

(6) FIG. 5 is a schematic illustration of a fourth assembly process for manufacturing a heater assembly of the type shown in FIG. 1;

(7) FIG. 6 illustrates an assembly line for handling the wick; and

(8) FIGS. 7A to 7F illustrate alternative arrangements for providing rigidity to a length of wick during an assembly process.

(9) FIG. 1 is an exploded view of a heater assembly. The heater assembly comprises a wick 100 and a heating element 200, in the form of a coil of electrically resistive filament, wrapped around the wick 100. The filament is formed from an electrically resistive metal or metal alloy. The wick 100 is fixed to a liquid storage portion which comprises a cap portion 300 and a main portion 310. FIG. 1 also shows a plug element 320 which is only required as a separate element to main portion 310 in some of the assembly methods which will be described. The heater assembly also includes electrical contact portions 400 to provide an electrical connection between the heating element 200 and external circuitry, including any power supply within the aerosol-generating device in which the heater assembly is to be used. The electrical contact portions 400 may be formed from any conductive material having low resistivity, e.g., gold plated metals and alloys, brass, and/or copper, and are shaped to fit within dedicated recesses in the cap portion 300.

(10) A cover portion 500 is provided to extend over the heating element 200 and wick 100, and defines an aerosol-forming chamber in which liquid vaporised by the action of the heater 200 may condense to form an aerosol.

(11) One particular difficulty with assembling a heater assembly of this type is the positioning of a heating element 200 around a flexible wick 100. FIG. 2 is a schematic illustration of a first manufacturing method for assembling a heater assembly of the type shown in FIG. 1. In the method of FIG. 2 the heating element is first constructed by winding a filament around a rigid tubular support which dimensioned so that it can receive a wick within its interior. The rigid tubular support may be formed from any rigid material having a slippery surface that does not impede the wick material from sliding off the support, for example, a stainless steel tube with or without a polished surface. This first step of winding the filament 610 around the rigid tubular support 600 is illustrated as S1. In a second step, S2, a wick 100 is cut to the required length. The wick 100 is loaded inside a rotary transfer tube 620, which may include a funnel portion. Once the wick is loaded inside the transfer tube, the wick is pushed into the rigid tubular support 600. This is shown as step S3. Following step S3 the cap portion 300 and electrical contact elements 400 are positioned around the tubular support 600. This is shown as step S4. In this embodiment the cap 300 and electrical contact elements 400 are all assembled to one another. In the subsequent step S5 the electrical contact portions 400 are fixed to the opposite ends of the heating element 200 by welding or crimping. Following assembly of the electrical contact portions to the heater, the rigid support element is preferably removed but may be kept in place to facilitate handling of the cap and contact assembly. This is achieved by pushing the wick out of the tubular support element 600 at the same time as withdrawing the tubular support element from the heating element 600 and the cap portion. This is shown as step S6.

(12) Following this step, or simultaneously to this step, the main portion 310 of the liquid storage portion is filled with aerosol-forming substrate. This can be done using any conventional filling method. The sub-assembly of heater, wick and cap portion is then positioned relative to the main portion 310 of the liquid storage portion. This is shown as step S8. In step S9 the wick is inserted into the reservoir and the cap portion and main portion joined. The cap portion and main portion may be joined together using any suitable mechanism such as laser welding ultrasound technology, or mechanical locking. In a final step, S10, the cover portion 500 is loaded over the wick and fixed to the cap portion 300 using a mechanical locking engagement.

(13) FIG. 3 illustrates an alternative manufacturing method to that shown in FIG. 2. In the method of FIG. 3, a rigid tubular support is used in the same manner as shown in FIG. 2. However, in the method of FIG. 3, the cap portion 300 and the main portion 310 of the liquid storage portion are pre-assembled and a plug element 320 is used to seal the liquid storage portion after filling. In a first step, S11, the heating element is assembled around the tubular support element 600 in the same manner as in step 1 illustrated in FIG. 2. In a second step, S12, a cut length of wick 100 is fed into the tubular support element 600. A rotary transfer tube may be used in the same manner as illustrated in FIG. 2. In a third step, S13, a pre-assembled sub-assembly of the main portion 310, cap portion 300 and electrical contact elements 400 are positioned around the tubular support element 600 so that the wick extends into the interior of the main portion 310. In a fourth step, S14, the electrical contact portions 400 are welded or crimped to the respective ends of the heating element 200. In a fifth step, the rigid support element 600 is removed. At the same time the wick 100 is pushed so as to prevent the wick being removed with the rigid tubular support 600.

(14) In a sixth step, S16, the liquid storage portion is filled from its open rear end with the wick secured in position. In a seventh step, S17, the sealing plug 320 is placed over the open end of the main portion 310. In an eighth step, S18, the sealing plug is welded to the main portion 310 to ensure that the liquid storage portion does not leak. In a final step, S19, the cover portion 500 is fixed in position over the wick, in the same manner as described with reference to step S10 in FIG. 2.

(15) It should be clear that in both of the methods described with reference to FIGS. 2 and 3 there may be additional steps performed. For example, between step S3 and S4, the heating element 200 may be crimped around the rigid support 600.

(16) In both of the methods described with reference to FIGS. 2 and 3, the rigid support element 600 is dimensioned so that the wick is compressed when it is inside the rigid support element 600. When the rigid support element is removed from the wick, the wick will then expand to engage the heating element 200 and the cap portion 300.

(17) FIG. 4 illustrates a third manufacturing method for assembling a heater assembly of the type shown in FIG. 1. In first step, S20, the generally tubular wick 100 is loaded onto a rigid support fixture 700. The rigid support fixture 700 may be a stainless steel rod. In a second step, S21, a filament is wound around the wick 100 using a moving flyer assembly. The filament is fixed to a stationary point at one end. The flyer moves around the wick as well as moving parallel to the longitudinal axis of the wick to form a heating element in the shape of a coil 200. The filament 610 is tensioned during the winding of the coil using a tensioning device.

(18) In a third step, S22, the cap portion 300 and electrical contact portions 400 are assembled around the wick 100. The cap portion is formed from two halves. Each half has an electrical contact portion 400 pre-assembled to it. The two halves of the cap portion are brought together around the wick and joined together. In a fourth step, S23, the electrical contact portions 400 are welded to the respective ends of the heating element.

(19) In a fifth step, S24, which may be carried out in parallel with steps S20 to S23, the main portion 310 of the liquid storage portion is filled with aerosol-forming substrate. In a sixth step, S25, the sub-assembly of wick, heater, cap portion, and electrical contact portions is mounted to the main portion 310 with the wick extending into the liquid aerosol-forming substrate. In a seventh step, the supporting fixture 700 is removed from inside the wick. In an eighth step the cover portion 500, is assembled to the cap portion as previously described.

(20) FIG. 5 is a schematic illustration of a fourth alternative assembly method for a heater assembly of the type shown in FIG. 1. The method of FIG. 5 relies on keeping the wick under tension to provide wick rigidity.

(21) In a first step, S30, a length of wick 100 is fed between two pairs of grippers 800. In a second step, S31, the grippers 800 are clamped around the wick 100 and the wick then cut. In a third step, S32, the cap 300 and electrical contact element 400 are assembled around the wick. The cap portion 300 has only a single electrical contact element already in place. Once the cap portion has been assembled around the wick, the heater filament is crimped to the electrical contact element in step S33. The wick is also rotated at this point to wind the coil around itself. Following this step the second electrical contact element is loaded, in step S34, and is attached to the cap portion 300 and crimped to the heating element.

(22) In a sixth step, S35, the main portion 310 of the liquid storage portion is filled with aerosol-forming substrate. In a seventh step, S36, the sub-assembly of wick, heater and cap portion is mounted to the filled main portion. In this step, the bottom pair of grippers 800 is released from the wick 100 to allow the free end of the wick to be inserted into the liquid aerosol-forming substrate. Advantageously, the cap portion 300 is held during this step of the process.

(23) In an eighth step, the cap portion 300 is welded to the main portion 310 to provide a liquid tight liquid storage portion. In a final step, S38, the cover 500 is assembled over the wick 100, as previously described.

(24) The methods described may be implemented in production line by moving the wick and heating element through a sequence of processing stages, corresponding to the steps described. The production line may be arranged on a rotary stage or along a conveyor.

(25) One exemplary set up of a production line is illustrated in FIG. 6. In FIG. 6, rollers 900 and cutting blades 902 are provided. The initial position of rigid tubular support 600 is shown in step S39. Moving to step S40, support 600 is advanced and heating element 200 formed around support 600. Next in step S41, rollers 900 push wick 100 into the interior of support 600. In step S42, support 600 is retracted, leaving wick 100 surrounded by element 200. Cutting blades 902 then cut the assembled wick 100 with element 200 at a predetermined length in step S43.

(26) It will now be clear to one of ordinary skill in the art that the above discussed manufacturing method is exemplary and that methods and apparatuses known in the art may be used to achieve desired results using the type of rigid support without deviating from the scope and spirit of the embodiments discussed herein.

(27) For example, although a rigid support may be used as discussed herein, variations on the use of a rigid support may be used instead. FIGS. 7A-7F illustrate such variations. FIG. 7A illustrates a hollow canula 1000 held within a funnel 1001 where wick 100 is pushed through the canula. FIG. 7B illustrates the use of an inner wire 1002 that provides sufficient rigidity to the wick material to facilitate wrapping of heater element 200 around the circumference of wick 100. FIG. 7C illustrates another possible solution, where a rigid rod 1004 provides support to the wick material by squeezing a first portion 1006 of wick 100 against funnel 1001 to provide sufficient rigidity to a second portion 1008 where element 200 is formed around. FIG. 7D illustrates an assisting wire 1010 provided along side of wick 100. Assisting wire 1010 may be withdrawn or kept with the completed wick 100 and element 200 assembly. Assisting wire 1010 may be formed of a wire or alternatively a string formed of a woven or other fibre. FIG. 7E illustrates another means of providing rigidity to the wick 100 prior to wrapping with element 200. In FIG. 7E, liquid 1012 is flowed through funnel 1001 over the wick 100 and the force of the flowing liquid provides sufficient rigidity to the wick 100 to be wrapped with element 200. Liquid 1012 may be any suitable liquid including forced air, so long as the liquid has sufficient density and may be provided at a sufficient flow rate to make wick 100 sufficiently rigid to wrap it with element 200. FIG. 7F illustrates the use of a frozen wick 100 where the wetting and freezing of liquid in wick 100 provides sufficient rigidity to wrap wick 100 with element 200.

(28) The exemplary embodiments described above illustrate but are not limiting. In view of the above discussed exemplary embodiments, other embodiments consistent with the above exemplary embodiments will now be apparent to one of ordinary skill in the art.