Abstract:
This invention comprises a method of sealing a valve unit to a reservoir by vibrating to cause melting and reshaping. Also the invention comprises a valve unit  1  and reservoir  2  assembly including a valve unit  1  and at least part of the reservoir  2  having members defining a valve bore  5 , the valve bore  5  receiving the valve unit  1  wherein the valve unit  1  is meltedly attached to the members defining the valve bore  5.

Description:
[0001]     This invention relates to a sealing method for assembling a valve unit into a reservoir and a sealed valve unit and reservoir. The invention is directed particularly, though not necessarily solely, toward a portable lighter.  
       BACKGROUND OF THE INVENTION  
       [0002]     A valve unit and reservoir which can be used in a portable lighter needs to be low cost, low weight, mass producible and tough, and importantly must also be sealable when being joined together. In general for sealing between the reservoir and valve unit body parts, a gas tight seal is required so therefore an intimate or close fit is necessary. Structurally this close fit requirement is dependent on both macroscopic and microscopic differences between the parts. Macroscopic differences cover the differences in size and shape of the parts. The valve unit body should be slightly bigger than the reservoir to obtain a tight fit. Microscopic differences cover the surface imperfections such as scratches or roughness.  
         [0003]     Reservoirs such as portable reservoirs for liquified petroleum gas (LPG) are usually made from polymeric material. The vapour pressure of LPG employed in portable reservoirs is usually in the range of 1.5 to 5 bar at 21° C. This range depends on the composition of the LPG. This range of vapour pressure makes polymeric materials especially suitable due to their low cost, low weight and ease of manufacture.  
         [0004]     Generally polymeric materials are suitable as valve units and reservoirs. Plastic polymeric materials are especially suitable. Structurally these materials can be classified as purely crystalline through to purely glassy (that is amorphous) materials, with mixtures or blends therebetween.  
         [0005]     A crystalline structure has a regular pattern, whereas an amorphous structure has a non-regular pattern. Crystalline polymers have good strength characteristics, elasticity, high strain capacity and are able to withstand continuous high stresses in temperatures without relaxing and are stable. The mechanical properties of crystalline structures material enable the gas tight seal gained through radial compression to remain gas tight for the life of the material. The elastic properties and stability combine to give excellent hard wearing properties.  
         [0006]     Usually, when manufactured using crystalline materials for reservoirs for LPG containers, they are sealingly attached to a valve unit body by press fitted radial compression or by positive engagement. This sealing attachment is especially relevant for portable reservoirs for liquified petroleum gases, that is, LPG reservoirs which can be made of polymeric materials, for example, cigarette lighters. Press fitting is relatively simple to achieve and is gas tight. The sealing of a LPG reservoir to a valve body is also relevant to gas welders, gas torches, hair curlers or any articles where a reservoir is part of a structure. In a particular use, that is, a cigarette lighter, press fitting is often used to seal the gas reservoir to the valve body. This is shown in U.S. Pat. RE. 33,282. This discloses a liquid gas operated lighter, such as a pocket lighter, made of a crystalline polymer. This lighter has a valve member press fitted in a gas-sealed type manner into the upper wall of a liquid gas non-refillable reservoir or tank.  
         [0007]     An amorphous structure is generally unstable, brittle, slowly changing from a glassy to a crystalline structure. Amorphous structure materials are not stable and being brittle, are not as hard wearing as the crystalline materials. Re use and adjustment actions are liable to crack or break the parts and break the gas tight seal.  
         [0008]     The lighter of U.S. Pat. No. 4,289,478 is manufactured from an amorphous polymeric material and has a plastics gas tank and a burner mounted therein. A heat collecting tube is provided along with a wick therein. The burner includes a nozzle and a valve which joins the heat collecting tube. The nozzle is held in positive engagement by a screw cap which is screwed to the tank. The screw cap is made of amorphous plastic material.  
         [0009]     The crystalline material lighter of U.S. Pat. reference No. Re. 33,282, is expensive from a material and a design perspective, whereas the amorphous polymer of U.S. Pat. No. 4,289,478 though using less expensive amorphous materials, requires several additional components which still combine to make this option expensive and difficult to mold.  
         [0010]     Another method currently in use for sealing in a gas tight manner, is positive engagement method, for instance a screw type valve body and a corresponding screw type valve bore. This method is usually limited to hand assembly. Therefore positive engagement is expensive to assemble and produce.  
         [0011]     Both of these prior art lighters which cover crystalline and amorphous materials have problems of high material costs and too many component parts to make. The corresponding methods of sealing are press fitting or radial compression for automatic manufacturing processing and also positive engagement or threading for manual operations. Also existing sealing methods as indicated above are limited to extremely precise surface finished materials wherein the surface defects of any of the two parts, that is, any scratches or roughness, for example, may lead to rejection of the finished product due to leakage of gas. Also none of the existing methods of sealing involve melting and reshaping to obtain a gas tight seal.  
       OBJECT OF THE INVENTION  
       [0012]     It is therefore an object of the present invention to provide an improved sealing method and valve and reservoir assembly which will obviate or minimise the foregoing disadvantages in a simple yet effective manner or which will at least provide the public with a useful choice.  
       STATEMENT OF THE INVENTION  
       [0013]     A method of sealing a valve unit and reservoir assembly, by carrying out the following steps: 
    (a) the valve unit is inserted at least partially into the reservoir;     (b) a melting creating action is applied to the valve unit and reservoir;     (c) at least portions of the valve unit and reservoir are melted such that the valve unit is sealed to the reservoir.    
 
         [0017]     The method of sealing as disclosed in the preceding paragraph wherein the melting creating action causes the melted portions to melt and reshape together to form a gas-tight seal.  
         [0018]     The method of sealing as disclosed in the preceding paragraph wherein at least part of the reservoir has members defining a bore.  
         [0019]     The method as in the preceding paragraph wherein the valve unit has a cross-sectional dimension larger than the cross-sectional dimension of the valve bore.  
         [0020]     The method of sealing as disclosed in the preceding paragraph wherein the melting creating action is created by applying a vibratory force onto the valve unit such that the valve unit is forced into a substantially abutting and reshaped relationship with the reservoir.  
         [0021]     The method of sealing as disclosed in the preceding paragraph wherein the melting and reshaping is caused by a high frequency vibration means.  
         [0022]     Accordingly in a second aspect the invention consists in a sealed assembly including a valve unit and at least part of a reservoir having members defining a valve bore, the valve bore receiving the valve unit wherein the valve unit is meltedly attached to the members defining the valve bore.  
         [0023]     Preferably the melting attachment causes the surfaces of the valve unit and reservoir to melt and reshape together to form a gas-tight seal.  
         [0024]     Preferably the reservoir includes a gas tank.  
         [0025]     Preferably the gas tank has a base portion having a recess wherein the recess has an aperture therein.  
         [0026]     Preferably a valve set is meltedly attached to the recess.  
         [0027]     Preferably the valve set includes a valve, flexible ring seal member and a spherical member wherein the spherical member moves to seal the aperture, in response to a gas refill nozzle such that gas can only enter during filling.  
         [0028]     Preferably the valve unit includes at least a valve member, a retainer member and nozzle wherein the valve member fitting within the retainer member, and the nozzle fitting within the valve member such that an end of the nozzle protrudes from the retainer member, and at least part of the valve member and retainer member being meltedly attached to the members defining the valve bore.  
         [0029]     Preferably the nozzle is interfitted with the retainer member by biasing means.  
         [0030]     Preferably the valve unit is manufactured from substantially amorphous polymeric materials.  
         [0031]     Preferably at least part of the reservoir is manufactured from substantially amorphous polymeric materials.  
         [0032]     Preferably the melting is provided by high frequency vibration means.  
         [0033]     Preferably the melting is provided by ultrasonic means.  
         [0034]     Alternatively the melting is provided by spin welding means.  
         [0035]     Alternatively the melting is provided by vibration welding means.  
         [0036]     Alternatively the melting is provided by hot plates.  
         [0037]     Alternatively the melting is provided by microwaves means.  
         [0038]     Preferably the melting is provided at, at least one melting location wherein the melting causes heating and fusing together of the valve unit and members defining the reservoir.  
         [0039]     Preferably the retainer member is meltedly attached to the members defining the valve bore.  
         [0040]     Preferably the valve member is meltedly attached to the members defining the valve bore.  
         [0041]     Preferably the valve member having an upper end and lower end in use, wherein a filter is attached to the lower end thereof.  
         [0042]     Preferably a cover is attached to the outer end of the filter.  
         [0043]     Preferably the nozzle has an upper end and lower end in use, wherein the nozzle has a resilient packing member at the lower end.  
         [0044]     Preferably a lighter has a sealing assembly as previously disclosed.  
         [0045]     Accordingly in another aspect the invention consists in a LPG tank assembly including a tank and valve, the tank in use having a lower portion having a valve recess therein such that the valve interfits with the recess, allowing gas refilling wherein the valve is meltedly attached to the valve recess and has re-shaped it.  
         [0046]     To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0047]     One preferred form of the invention will now be described with reference to the accompanying drawings in which,  
         [0048]      FIG. 1  shows a cross section of part of a prior art lighter,  
         [0049]      FIG. 2  shows a cross section of part of a further prior art lighter,  
         [0050]      FIG. 3  is a cross section of a valve unit assembled with part of the reservoir at a first stage of insertion,  
         [0051]      FIG. 4  is a cross section of a valve unit assembled with part of the reservoir at a second stage of insertion,  
         [0052]      FIG. 5  is a cross section of a valve unit assembled with part of the reservoir at a third stage of insertion ie the valve unit being welded to the reservoir,  
         [0053]      FIG. 6  is a close up cross section of the lower end of the assembly showing the weld positions,  
         [0054]      FIG. 7  is a close up cross section of the base portion of a refillable lighter.  
         [0055]      FIG. 8  is a close up cross section of the base portion of a refillable lighter being refilled. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0056]     Referring to the drawings the closeable valve unit, as assembled, is shown in FIGS.  3  to  5 . As shown, a valve unit  1  interconnects with at least a portion of a reservoir  2 . The valve unit  1  includes a valve unit body having at least a valve member, a retainer member, and nozzle member for the gas flame.  
         [0057]     Reservoir  2 , in use, has an upper end  3  and a lower end  4 . The upper end  3  is at the same end that a nozzle member  12  for the portable lighter will be located. At the lower end  4  of reservoir  2  will be located the rest of the reservoir which will contain the fuel. The reservoir  2  has a bore  5  as shown in  FIG. 3 . The valve unit is located within the bore  5 . The valve unit  1  includes a retainer member  6 , which abuts the inner walls of the bore  5 . The retainer member  6  has an upper end  7  and a lower end  8 . The upper end  7  may be stepped to provide a stopping action of the penetration of the retainer member  6  and or valve unit during insertion into the reservoir. Abutting the inner walls of the retainer member  6  is a valve member having a valve body  9 . The valve body  9  has an upper end  10  and a lower end  11 . Within the valve body  9  is the nozzle member  12 . The nozzle member  12  has an upper end  13 , which corresponds to the upper end  3  of the reservoir  2 , and a lower end  14  which also corresponds to the lower end  4  of the reservoir  2 . The nozzle member  12  has a biasing means  15 , which can be a spring, to help it to remain in abutment with retainer member  6 .  
         [0058]     The valve body  9  also has, at its lower end  11 , a filter member  16 , which is in turn covered by a cover member  17 . The nozzle member  12  rests on the base of valve body  9  by a resilient packing member  18 . The packing member can be a rubber bung member.  
         [0059]     As shown in  FIGS. 3, 4  and  5  the valve unit  1  is sealed to the reservoir  2  by meltedly joining at specified positions on the reservoir  2 . The valve unit  1  and bore  5  have abutting surfaces which are melted causing localised reshaping of these surfaces to join to produce an almost perfect gas-tight seal. The figures show the valve unit  1  being placed within the bore  5  of reservoir  2 . The valve unit  1  is pushed into the bore  5 . The bore  5  is shaped to receive the valve unit  1 . The bore  5  may have, at its upper end  3 , a stepped portion  19  and at the lower end  4  there is at least a two stage reduction in the bore diameter portion. The two stage reduction can be made up of an inwardly angled portion  20  leading to a substantially vertical portion  21  which is substantially parallel to the inner wall  22  of the bore  5 .  
         [0060]     In the lower portion of the bore there are some meltedly joined areas  23  and burr areas  24 . Any other areas can be selected.  
         [0061]     The valve unit  1  and or reservoir  2  can be made from any material or blend that can be melted and sealingly joined. Any polymeric material or blend can be used. Substantially plastic polymeric materials or blends can be used and especially an amorphous or glassy polymeric material. Purely crystalline through to purely amorphous structures with or not with a blend, can also be used. In one form of the invention the reservoir  2  is made from polymeric material but the valve unit  1  may be formed from metallic materials and polymeric materials. Of course, normally it would be polymeric materials that melt but a gas tight seal can be obtained even when a metallic part is embraced or coated by molten polymeric material. Macroscopic differences, ie in shape or size can still be sealed as with microscopic differences such as scratches and roughness which may exist between the valve unit  1  and the bore  5 .  
         [0062]     The valve unit  1  and reservoir  2  are melted such that the unit  1  and reservoir  2  are joined between, at least, positions  23  and  24  as shown in  FIGS. 5 and 6 . Joining will occur along substantially the whole of or at least a substantial proportion of the length of the valve unit  1  or the bore  5 . Any suitably joining and or welding positions can be selected as long as the valve unit is sealed with the reservoir  2  such that there is no gas leakage. In the drawings both the retainer  6  and valve body  9  are shown meltedy joined or welded to the valve bore  5 . As the valve body  9  diameter is larger than the valve bore  5  diameter, then when the polymeric material of the valve body and valve bore is melted during insertion of the valve body  9  into the valve bore  5 , any excess material is displaced downwards to settle in the burr areas  24 . The upper end  7  of the retainer member  6  may be stepped to provide a stopping action for the penetration of the retainer member and or valve unit during insertion into the bore. After melting the components are joined by fusion e.g. welding. The melting can be applied by a high frequency vibration means.  
         [0063]     The method utilising melting to connect the parts can be achieved in the following manner. For example by welding. In order to avoid gas leakage, the valve body is preferably larger or has a wider diameter than the whole, or at least part, of the diameter of the valve bore  5 . The valve unit  1  can be then be forcibly downwardly inserted into the valve bore  5  by inducing high frequency downward vibration to the valve unit  1 . FIGS.  3  to  5 , show the steps in the insertion of the valve unit  1 . The high frequency vibration makes the lower end  11  of the valve unit  1  hit and abut the inner walls  22  of the bore  5  and also the inwardly angled portion  20 . The vibration will not break the amorphous polymeric structure, but will melt the plastics materials at specific locations (as selected) around the valve unit  1  and/or the valve bore  5  of the reservoir  2 . Because an amorphous polymer is being used for the reservoir  2  and valve unit  1 , and this has a relatively low viscosity, when it melts, it forms a seal between the reservoir  2  and valve unit  1  at welding areas  23  and burr areas  24 . The melted plastics material can downwardly travel and fill, and join by fusion to even very small gaps and apertures e.g. burrs  24  between the reservoir  2  and valve unit pieces, giving a high quality gas seal effect. Since no radial compressive force is required as in the press fit method of the prior art, we can use the inexpensive amorphous polymers for the production of both the valve unit  1  and reservoir  2  of the lighter.  
         [0064]     The valve unit can be sealingly joined to the valve bore  5  by downwardly inducing vibration or any other melting methods such as welding. The time and energy required to obtain complete penetration of the valve unit  1  into the valve bore  5  by melting is very short and the effect can be localised reshaping. This means that there is unlikely to be any problem in relation to distortion of the components or post shrinkage of any component(s).  
         [0065]      FIGS. 7 and 8  shows the lower portion only of a refillable lighter which can also be assembled using the same components disclosed and method disclosed by the present invention. The figures show at least a part of the reservoir i.e. a lower portion of a reservoir tank  25  containing pressurised gas  26 . In use the tank  25  fits underneath the said at least part of the reservoir  2  of  FIG. 3 .  FIG. 7  shows the tank  25  before refilling.  FIG. 8  shows the gas refilling operation. The base portion  27  comprises a portion  28  that protrudes into the gas tank  25  providing a recess. Within the recess a valve assembly  29  sits therein to provide an openable aperture  30  to allow the insertion of a refill nozzle  31 . The refill nozzle  31  can be attached to a gas source. The valve assembly  29  can be made up of a valve member  32 , which abuts an O ring member  33  which abuts a spherical member e.g. a ball  34  which sealingly closes the aperture  30 . Under non-refill conditions the downward gas pressure in the tank, keeps the ball pressed against the O ring to seal thereagainst. When the refill nozzle is inserted into the valve the ball is pushed upwards revealing a gap between the O-ring and the ball thereby allowing the ingress of gas into the tank  25 . The valve member  32  is sealed to the recess of the base portion by melting. Preferably the melting action is applied by the following means including vibration welding, high frequency vibration, hot plate welding, vibration welding and microwave welding. It is preferred that amorphous polymeric materials are used.  
         [0066]     It is also envisaged that this method is also applicable to other valve units besides ones for portable lighters. As this method combines the cheap amorphous material with a melting and reshaping sealing method. Other valves can include refill valves as for flow control valves.  
         [0067]     Throughout the description of this specification the word “comprise” and variations of that word, such as “comprising”, are not intended to exclude other additives, components, integers or steps.  
       ADVANTAGES OF THE INVENTION  
       [0068]     The reservoir sealing method has the following advantages: 
    1. Few parts are required when compared to the prior art.     2. The construction is inexpensive to manufacture.     3. The assembly time is very short.     4. Sealing rings are not necessary in some embodiments.     5. Threading or retaining elements are not necessary.     6. Surface defects not important.     7. Melting and reshaping of the sealed area to achieve very effective seal.