Patent Publication Number: US-6698467-B2

Title: Container strengthening system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/329,168 filed Dec. 24, 2002 for CONTAINER STRENGTHENING SYSTEM of Robert H. Schultz et al., which is a continuation of U.S. patent application Ser. No. 09/812,640 filed Mar. 20, 2001 for CONTAINER STRENGEHING SYSTEM of Robert H. Schultz et al., now U.S. Pat. No. 6,378,571, both of which are hereby specifically incorporated by reference for all that is disclosed therein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to container strengthening systems, and, in particular, to liquefied gas injection systems used to strengthen containers. 
     BACKGROUND OF THE INVENTION 
     Carbonated beverages, such as soft drinks and beer, are commonly packaged in metallic containers such as aluminum cans. The carbonation within the beverage exerts pressure on the containers, thereby increasing the strength of the container walls. However, it is generally desirable to further strengthen the containers in order to decrease the likelihood of damage to the containers as well as minimize the necessary thickness of the container walls. 
     One method used for strengthening containers is to deposit a liquefied gas such as nitrogen onto the beverage immediately prior to sealing the container. After sealing, the evaporated liquefied gas creates pressure within the container and also displaces oxygen from the headspace, thereby helping to prevent spoilage of the beverage. Many devices used to accomplish this result simply lay the liquefied gas onto the surface of the beverage, rather than forcibly injecting the liquefied gas into the beverage. This may suffice for non-carbonated beverages as well as some carbonated beverages. However, with a carbonated beverage such as beer that tends to produce a frothy head upon filling the container, liquefied gas deposited within the container tends to roll off the frothy head of the beverage and out of the container. 
     One solution would be to forcibly inject a liquefied gas such as nitrogen into the beverage utilizing a high-performance, quick-responding solenoid. However, due to the extremely cold temperatures involved in utilizing liquefied gas, a solenoid-controlled injector system must be carefully designed to avoid atomization of the liquid, which may occur when the liquefied gas is not properly passed through various inlets and/or outlets within the system. Furthermore, the pressure within the system must be carefully controlled in order to deliver a consistent amount of liquid nitrogen to each container in a high-speed filling operation. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a system for strengthening containers in a high-speed filling operation. The system may include a solenoid-driven injector apparatus positioned at an angle to the containers being filled. The injector apparatus may comprise an intake line in fluid flow relation with the supply tank, and a chamber in fluid flow relation with the intake line. The injector apparatus may also comprise an injector valve located within the chamber which includes a needle stem, a valve seat within a valve body, and a substantially straight outflow line which leads to the containers being filled. An adjustment device may also be provided for adjusting the position of the valve seat relative to the needle stem. The injector apparatus may further comprise a solenoid operatively connected to the needle stem, and a biasing device biasing the needle stem toward the valve seat. A heater may also be provided adjacent to the outflow line. The injector apparatus has an open operating state whereby the needle stem is positioned away from the valve seat, allowing liquefied gas within the chamber to flow out of the outflow line and into one of the containers. The injector apparatus also has a closed operating state whereby the needle stem is seated within the valve seat, blocking the liquefied gas within the chamber from entering the outflow line. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Illustrative and presently preferred embodiments of the invention are illustrated in the drawings in which: 
     FIG. 1 is a front view of an exemplary container strengthening system of the present invention; 
     FIG. 2 is a top view of the container strengthening system of FIG. 1; 
     FIG. 3 is an enlarged, front view of a container and an injector apparatus of the container strengthening system of FIGS. 1 and 2; 
     FIG. 4 is a cross-sectional view of a supply tank of the container strengthening system of FIGS. 1 and 2; 
     FIG. 5 is a cross-sectional view of the injector apparatus of the container strengthening system of FIGS. 1 and 2; 
     FIG. 6 is another cross-sectional view of the injector apparatus of FIG. 5; 
     FIG. 7 is an enlarged view of a portion of the injector apparatus of FIG. 5; 
     FIG. 8 is a cross-sectional view of another embodiment of the injector apparatus in a “closed” operating state; 
     FIG. 9 is a cross-sectional view of another embodiment of the injector apparatus in an “open” operating state; 
     FIG. 10 is an enlarged view of a portion of the injector apparatus of FIG. 9; and 
     FIG. 11 is an enlarged view of another portion of the injector apparatus of FIG.  9 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2 illustrate the container strengthening system  10  of the present invention. The container strengthening system  10  is adapted to forcibly inject a liquefied gas  12  such as nitrogen into containers  14  such as, for example, metallic cans, in a high-speed filling operation. The containers  14  may contain a beverage such as beer which frequently develops a frothy head during filling of the containers  14 . The system  10  preferably injects the liquefied gas  12  into the containers  14  with an adequate force such that the liquefied gas  12  remains within the container  14  and does not roll off the frothy head of the beverage therein. 
     The container strengthening system  10  may comprise a supply tank  20  comprising a first intake line  22  in fluid flow relation with a source  30  of liquefied gas  12 . The source  30  of liquefied gas  12  may be, for example, a tank having a relief valve  32  (schematically illustrated by the designation “R”) to maintain the pressure of the liquefied gas  12  therein at an adequate level, e.g. 25 psi, to force the liquefied gas  12  through the first intake line  22  to the supply tank  20 . The source  30  of liquefied gas may alternatively be a bulk holding tank (not shown), whereby the liquefied gas  12  may be piped in through the first intake line  22  to the supply tank  20 . The liquefied gas  12  may be any non-oxidizing gas such as, for example, liquid nitrogen conventionally added to products such as non-carbonated beverages to increase the pressure within their containers  14  and also to displace oxygen from the headspace above the beverage in the containers  14 . The first intake line  22  may comprise a shutoff valve  26  (schematically illustrated by the designation “V”) which may open and close the line  22  to the source  30  of liquefied gas  12  as desired. 
     The supply tank  20  may further comprise a liquid level control valve  40  (FIG. 2, and described in more detail below with reference to FIG.  4 ). The liquid level control valve  40  is in fluid flow relation with the first intake line  22  and controls the level of liquefied gas  12  within the supply tank  20 . The supply tank  20  may further comprise a back pressure regulator  28  (schematically illustrated by the designation “P”) to carefully control the pressure within the tank  20  (which in turn maintains an appropriate pressure within the injector apparatus  80  described below), as is necessary to maintain proper dosing of the liquefied gas  12  into the containers  14 . Any conventional back pressure regulator  28  which is adapted for use with liquefied gas such as nitrogen may be utilized to control the pressure in the supply tank  20 , such as, for example, back pressure regulator #44-4761-24-501 manufactured by Tescom Corporation of Elk River, Minn. In order to supply adequate force with which to inject the liquefied gas  12  into the containers  14 , the pressure in the supply tank  20  is preferably maintained by the back pressure regulator  28  at between about 1 psi and 5 psi, and most preferably approximately 3 psi. A pressure in the supply tank  20  which is too low may cause the liquefied gas  12  injected into the containers  14  to roll off the frothy head of the beverage therein. However, a pressure in the supply tank  20  which is too high may simply cause the liquefied gas  12  being injected into the containers  14  to atomize into the atmosphere  38  (FIG. 3) above the containers  14 . 
     The system  10  may further comprise an injector apparatus  80 , described in detail below relative to FIGS. 5-7, comprising a second intake line  82  in fluid flow relation with the supply tank  20 . As shown in FIGS. 1-2, the injector apparatus  80  may be positioned directly above a conventional conveyor  16  or the like carrying a row of containers  14  past the injector apparatus  80  in a horizontal direction  18  at a velocity “Vc”. In a high-speed filling operation, this velocity “Vc” may be, for example, 4000 inches/minute (utilizing standard beverage cans, this translates to approximately 1000 cans/minute). As best shown in FIG. 3, the injector apparatus  80  is preferably positioned at an angle “A” to each container  14 , thereby injecting liquefied gas  12  into the containers  14  in an angled, downward direction  19  at a velocity “Vg”. As shown in FIG. 3, the angle “A” is the angle between the central longitudinal axis “BB” of the injector apparatus  80  and the central longitudinal axis “CC” of a container  14 . This angle “A” may be determined by the velocity “Vc” of the containers  14  traveling past the injector  80 . Specifically, the velocity “Vc” of the containers  14  only has a horizontal component, while the velocity “Vg” of the liquefied gas  12  has both a horizontal component “Vgh” and a vertical component “Vgv”. Ideally, the injector apparatus  80  is angled so that the horizontal component “Vgh” of the velocity “Vg” of the liquefied gas  12  is equal to the velocity “Vc” of the containers  14 . The closer “Vgh” is to “Vc”, the less the possibility that the liquefied gas  12  will splash and roll off of the beverage&#39;s frothy head and out of the container  14 . In a high-speed filling operation whereby “Vc” is approximately 4000 inches/minute, this angle “A” is preferably between about 15 and 18 degrees, and most preferably approximately 18 degrees. In a relatively faster operation (e.g., 1500 cans/minute), the angle “A” is preferably relatively greater (e.g., approximately 30 degrees). 
     As shown in FIGS. 1-3, the system  10  may further comprise a sensor  34  which senses the presence of a container  14  below the injector apparatus  80 . The sensor  34  is operatively connected via line  36  to a solenoid driver  121  which is then connected via line  37  to the injector apparatus  80 , and specifically to the solenoid  120  of the injector apparatus  80  described in further detail below with reference to FIGS. 5 and 6. The sensor  34  may be of the type conventionally known in the art, such as sensor #9-251-03 manufactured by Sencon, Inc. of Bedford Park, Ill. Upon sensing the presence of a container  14 , the sensor  34  actuates the solenoid  120 , causing the liquefied gas to forcibly flow from the injector apparatus  80  into the container  14 . 
     As noted above and shown in FIG. 4, the liquid level control valve  40  is in fluid flow relation with the first intake line  22  and may be used to control the level of liquefied gas  12  within the supply tank  20 . The liquid level control valve  40  prevents liquefied gas  12  from entering the back pressure regulator  28  (shown schematically in FIGS.  1  and  2 ), thereby preventing freezing and failure of the back pressure regulator without the need for a separate heater adjacent to the back pressure regulator. As shown in FIG. 4, the liquid level control valve  40  may comprise a float  42  fixedly attached to a rod  44 . The rod  44  may be hingedly connected with a first pin  46  to a needle stem  48  which is adapted to be received by a valve seat  50 . The valve seat  50  may be an opening within a valve body  52  which is directly connected to the opening  24  of the first intake line  22 . The valve body  52  may comprise a flange  54  which acts as a linear guide for the needle stem  48 . The rod  44  may also be hingedly connected with a second pin  56  to the valve body  52 . As shown in FIG. 4, the float  42  is translatable in an arcuate direction  60 ,  62  along axis DD around axis EE which is defined by the second pin  56  connecting the rod  44  to the valve body  52 . As the level of liquefied gas  12  within the tank  20  increases causing the float  42  to rise in direction  60  along axis DD, the rod  44  pushes the needle stem  48  in a linear direction  64  toward the valve seat  50 . When the float  42  has risen to a predetermined maximum level within the supply tank  20 , the needle stem  48  completely blocks off the valve seat  50  so that no liquefied gas  12  may enter the first intake line  22 . The maximum level is determined by the location of the back pressure regulator  28 , which is preferably connected to (or close to) the top surface  21  (FIGS. 1 and 2) of the supply tank  20 . At levels close to the maximum, the needle stem  48  may only partially block the flow of liquefied gas  12  into the supply tank  20 . As the level of liquefied gas  12  within the tank  20  decreases, causing the float  42  to lower in direction  62  along axis DD, the rod  44  pulls the needle stem  48  in a linear direction  66  away from the valve seat  50 , allowing the liquefied gas  12  to flow from the first intake line  22  into the tank  20 . The liquid level control valve  40  may further comprise a baffle  68 , which may consist simply of the bottom portion of a Styrofoam cup, located in the proximity of the first intake line  22 . The baffle  68  interrupts the flow of liquefied gas  12  into the supply tank  20  to prevent atomization of the liquefied gas  12  in the atmosphere  70  above the liquefied gas  12  within the tank  20 . 
     Due to the extremely cold temperatures involved in utilizing liquefied gas such as nitrogen, various parts of the system  10  (FIGS. 1 and 2) are preferably insulated. For example, as shown in FIG. 4, the supply tank  20  and first intake line  22  may be covered with insulation  72 . As shown in FIG. 5, the second intake line  82 , as well as the entire injector apparatus  80 , may also be covered with insulation  72 . In all of the figures, the insulation has been removed from the injector apparatus  80  for clarity. 
     Referring now to FIGS. 5-7, the injector apparatus  80  may further comprise a chamber  84  in fluid flow relation with the supply tank  20 . As best shown in FIG. 5, the chamber  84  may comprise a first end  86  having a threaded portion  90  which may be secured to a threaded portion  83  of the second intake line  82 . The injector apparatus  80  may further comprise an injector valve  92  located within the chamber  84  near the second end  88  thereof. As best shown in FIG. 6, the injector valve  92  may comprise a needle stem  94  having a first end  96  and a second end  98 , a valve seat  110 , and a substantially straight outflow line  114 . The needle stem  94  may be comprised of a first needle portion  100  fixedly attached to a second needle portion  102 . The first needle portion  100  may comprise a pointed end  104  which is adapted to be received by the valve seat  110 . The valve seat  110  may have a substantially conical shape as shown in FIGS. 5-7 to best accommodate the pointed end  104  of the first needle portion  100 . The first needle portion  100  may be manufactured from a plastic material such as, for example, Teflon, which tends to be very durable in extremely cold temperatures. The second needle portion  102  may be manufactured from stainless steel or the like. As best shown in FIG. 7, the valve seat  110  may be an opening within a valve body  112  which is directly connected to the outflow line  114 . As noted above, the outflow line  114  is preferably substantially straight, since an outflow line that is bent, curved, or the like may cause the exiting liquefied gas  12  (FIGS. 5 and 6) to atomize in the atmosphere  38  (FIG. 3) above the containers  14 , rather than being deposited within the containers  14  as desired. 
     The injector apparatus  80  may comprise an “open” operating state as shown in FIGS. 5 and 6 whereby the needle stem  94  is positioned away from the valve seat  110 , allowing liquefied gas  12  to flow out the outflow line  114 . The injector apparatus  80  may also comprise a “closed” operating state as shown in FIG. 7 whereby the needle stem  94  is seated within the valve seat  110 , blocking the liquefied gas  12  (FIGS. 5 and 6) from entering the outflow line  114 . 
     As shown in FIGS. 5 and 6, the injector apparatus  80  may further comprise a solenoid  120  operatively connected to the sensor  34  (FIGS. 1-3) via a solenoid driver  121  (FIGS. 1-2) and to the needle stem  94 . The solenoid driver  121  may be of the type conventionally known in the art, such as driver #LST-22-DV manufactured by Sencon, Inc., of Bedford Park, Ill. As best shown in FIG. 6, the solenoid  120  may comprise a solenoid coil  122 , a coil housing  123 , an armature  124  preferably manufactured from stainless steel or iron, a housing  126  comprising an armature back stop  128 , and an armature forward stop  130 . The solenoid coil  122  may be a conventional, high-performance, quick-responding solenoid coil such as Skinner solenoid coil #L322 manufactured by Parker Hannifin Corporation of Cleveland, Ohio. The housings  123 ,  126  may be manufactured from stainless steel. 
     The armature  124  is attached to the needle stem  94  in a manner which causes the needle stem  94  to travel with the armature  124 . Specifically, the needle stem  94  may comprise a flange  132  which engages a first flange  134  in the armature  124 . When the sensor  34  (FIGS. 1-3) sends a signal to the solenoid  120 , the coil  122  is energized for a predetermined amount of time “t” which may be set on the solenoid driver  121  (FIGS. 1-2) and which correlates to the desired amount of liquefied gas  12  to be injected into a container  14 . In a high-speed filling operation, the predetermined amount of time “t” set on the solenoid driver  121  may be approximately 10-20 milliseconds. When the coil  122  is energized, a magnetic force is created, causing the armature  124  to travel in an upward direction  140  until a second flange  136  on the armature  124  reaches the back stop  128  in the housing  126 . Since the needle stem  94  is connected to the armature  124  as noted above, this upward action by the armature  124  pulls the needle stem  94  away from the valve seat  110  and allows liquefied gas  12  to flow out of the outflow line  114 . The injector apparatus  80  is then in the “open” operating state (FIGS.  5  and  6 ). A biasing device  138  such as a spring may be positioned adjacent to the second end  98  of the needle stem  94  to bias the first end  96  of the needle stem  94  toward the valve seat  110 . Thus, when the coil  122  is no longer energized (i.e., when a predetermined amount of liquefied gas  12  has exited the outflow line  114  into a container  14 ), the needle stem  94  is pushed by the biasing device  138  in a downward direction  142  toward the valve seat  110  such that the needle stem  94  blocks the outflow line  114  from receiving liquefied gas  12 . As the needle stem  94  moves downwardly  142 , the armature  124  is urged toward the forward stop  130 , and the injector apparatus  80  is then in the “closed” operating state (FIG.  7 ). 
     As shown in FIG. 6, the distance “D” between the forward stop  130  and the armature  124  when the armature  124  is adjacent to the back stop  128  defines the “stroke” of the armature  124 . A high performance, quick-responding solenoid typically has a very limited stroke which may be, for example, on the order of 0.08 inches. The stroke of the armature  124  is typically slightly (e.g., 0.005 to 0.01 inches) more than the stroke of the needle, i.e., the distance that the needle stem  94  travels in each direction  140 ,  142 . As best shown in FIG. 6, the injector apparatus  80  may further comprise an adjuster  146  which assists in mounting the solenoid  120  to the chamber  84 . A Teflon O-ring  148  may be provided between the adjuster  146  and the housing  126  to prevent leakage of the liquefied gas  12 . 
     As shown in FIGS. 6 and 7, the injector apparatus  80  may further comprise an adjustment device  150  operatively connected to the valve seat  110  (FIG. 6) for adjusting the position of the valve seat  110  relative to the needle stem  94 . Because a high-performance, quick-responding solenoid has a very limited stroke (“D” in FIG. 6) as described above, some allowance must be made for manufacturing tolerance buildup between the valve seat  110  and the pointed tip  104  of the needle stem  94 . The adjustment device  150  is provided in order to ensure that the needle stem  94  is seated properly within the valve seat  110  when the injector apparatus  80  is in the “closed” operating state, and that adequate clearance is provided between the needle stem  94  and the valve seat  110  in the “open” operating state, thus providing a proper dosage of liquefied gas  12  into the containers  14  and avoiding atomization of the exiting liquefied gas  12 . As shown in FIG. 7, the adjustment device  150  may comprise a threaded engagement device  152  which engages a threaded portion  154  of the valve body  112 . The threaded engagement device  152  and valve body  112  may be manufactured from stainless steel. The valve body  112  may be adjusted in an upward direction  140  or a downward direction  142  by turning the valve body  112  relative to the engagement device  152 . A housing  156  may be provided between the engagement device  152  and the chamber  84  (or, alternatively, the housing  156  and engagement device  152  may be a single component). The valve body  112  may also be provided with Teflon O-rings  158  between the valve body  112  and housing  156  to prevent leakage of the liquefied gas  12  (FIGS.  5 - 6 ). 
     As best shown in FIG. 7, the injector apparatus  80  may further comprise a heater  160  positioned adjacent to the outflow line  114  to prevent ice buildup within or just outside of the outflow line  114 , e.g., on outer surface  116  of the valve body  112 . The heater  160  may comprise at least one heating element  162  housed within a cap  164  which may be manufactured from stainless steel. Insulation  166  may be provided between the cap  164  and the valve body  112 . An opening  168  may be provided in the cap  164  adjacent to the outflow line  114 . The heater  160  may be secured to the valve body  112  by any conventional means such as by utilizing bolts, screws, adhesive, etc. 
     An alternative embodiment of the injector apparatus  80  is shown in FIGS. 8-11. As best shown in FIGS. 8 and 9, the injector apparatus  80  may comprise a chamber  200  having a first end  202  and a second end  204 . The chamber  200  may be of the type found on injector Model No. LCI-2000 manufactured by VBS Industries of Campbell, Calif. The chamber  200  may be manufactured from a metal such as stainless steel or the like, and may have an inner core  206  of insulation. More specifically, the chamber  200  may comprise a metal (stainless steel or the like) inner wall  208  and a metal outer wall  210  with an inner core  206  of insulation therebetween. The chamber  200  may have an inner threaded portion  212  at the first end  202  thereof. At the inner threaded portion  212 , the chamber  200  may be secured to a housing  220  which has an outer threaded portion  222 . The threaded portions  212 ,  222 , along with a threaded locking nut  224 , provide an adjustment device  226  which, like the adjustment device  150  described above relative to FIG. 6, allows the position of the valve seat  242  (FIGS. 9 and 10) relative to the needle stem  234  to be adjusted (and then locked in with the locking nut  224 ) as desired. The adjustment device  226  will be described in more detail below relative to FIG.  11 . The injector apparatus  80  is shown in a “closed” operating state in FIG. 8 whereby the needle stem  234  is seated within the valve seat  242  (FIGS.  9  and  10 ), blocking the liquefied gas  228  (which may be the same as the liquefied gas  12 , FIGS. 1-6, described above) from entering the outflow line  244  (FIG.  10 ). The injector apparatus  80  is shown in an “open” operating state in FIG. 9 (as well as FIGS. 10-11) whereby the needle stem  234  is positioned away from the valve seat  242  (FIGS.  9  and  10 ), allowing liquefied gas  228  to flow out the outflow line  244 . 
     As shown in FIGS. 8 and 9, the injector apparatus  80  may further comprise a solenoid  230  including an armature  232 , which may be substantially the same as the solenoid  122  and armature  124 , respectively, described above relative to FIGS. 5-6. The needle stem  234  may comprise a first needle portion  236  and a second needle portion  238 , which may be attached to the armature  232 . A valve body  250  and a heater  260  may be attached to the chamber  200  at the second end  204  thereof. 
     As best shown in FIG. 10, the injector apparatus  80  may further comprise an injector valve  240  located within the chamber  200  near the second end  204  thereof. The injector valve  240  may comprise the needle stem  234  described above, as well as a valve seat  242  and a substantially straight outflow line  244  in a valve body  250 . The valve body  250  may be manufactured from a metal such as stainless steel. The first needle portion  236  of the needle stem  234  may be attached to the second needle portion  238  using a roll pin  246  or the like which extends through both the first needle portion  236  and the second needle portion  238 . The first needle portion  236  may be manufactured from a plastic material such as Teflon, while the second needle portion  238  may be manufactured from a metal such as stainless steel. The first needle portion  236  preferably has a tapered end portion  248  which is adapted to be received by the valve seat  242 . The tapered end portion  248  may have a rounded end  249  as shown in FIG.  10 . The degree of tapering of the tapered end portion  248  may be such that the angle “A1”, FIG. 10, between an axis parallel to the central longitudinal axis “FF” of the injector apparatus  80  and an imaginary line extending tangentially from the sidewall of the tapered end portion  248  of the needle stem  234  is preferably between about 3 and 12 degrees. The valve seat  242  preferably has a diameter “D1” which is larger than a diameter “D2” on the tapered end portion  248  (preferably near the rounded end) and smaller than a diameter “D3” on the first portion  236  of the needle stem  234 . This allows the tapered end portion  248  of the needle stem  234  to be securely seated within the valve seat  242  as shown in FIG.  8  and to provide a tight, substantially leak-free seal at the valve seat  242 . To further control leakage at the needle stem  234 /valve seat  242  interface, the valve body  250  preferably has a sharp (e.g., not rounded, beveled, etc.) circumferential edge  252  at the valve seat  242 . 
     As shown in FIG. 10, the valve body  250  may further comprise a stair-stepped portion  254  which is adapted to engage flanges  256  in the chamber  200 . The valve body  250  may also comprise a threaded portion  258  which is adapted to engage a threaded portion  259  of the chamber at the second end  204  thereof. Such a configuration provides a secure, leak-free engagement between the valve body  250  and the chamber  200  and reduces or eliminates the need for O-rings or the like (e.g., O-rings  158  described above with reference to FIG.  7 ). Unlike the injector apparatus  80  shown in FIGS. 5-7 which has an adjustment device  150  that is located adjacent to the valve seat  110  (FIG.  6 ), the adjustment device  226  in the injector apparatus  80  of the embodiment shown in FIGS. 8-11 is located at the opposite end (i.e., the first end  202 ) of the chamber  200  as noted above and described in further detail below. 
     As noted above, the injector apparatus  80  may further comprise a heater  260  which, like the heater  160  described above relative to FIG. 6, is positioned adjacent to the outflow line  244  (i.e., at least close enough for heat exchange to occur) to prevent ice buildup within or just outside of the outflow line  244 . As best shown in FIG. 10, the heater  260  may comprise a cap-like housing  262  which may be manufactured from a metal such as stainless steel and at least one heating element  264  within the housing  262 . An outflow opening  266  may be provided in the housing  262  adjacent to the outflow line  244  in the valve body  250 . As shown in FIG. 10, the outflow opening  266  may have a funnel-shaped upper portion  268  which is adapted to accommodate the lower portion  270  of the valve body  250 . The heater  260  may further comprise a vent opening  272  which is connected to the funnel-shaped upper portion  268  of the outflow opening  266 . A preferably dry gas such as air or, most preferably, nitrogen gas may be injected and circulated through the vent opening  272  in order to prevent moisture from collecting on the valve body  250  and surrounding area. The heater  260  may be secured to the chamber by any conventional means such as by utilizing bolts, screws, adhesive, or the like. Alternately, as shown in FIG. 10, the heater  260  may comprise one or more O-rings  274  for frictionally gripping the second end  204  of the chamber  200 . 
     Referring now to FIG. 11, the injector apparatus  80  may further comprise a bracket  280  for housing electrical components (not shown) and the like connected to the solenoid  230 . The solenoid  230  may comprise a solenoid coil  282  (which may be the same as the solenoid coil  122 , FIG. 6, described above), a coil housing  283 , an armature  232  preferably manufactured from a metal such as stainless steel or iron, a first insert  284  having an armature back stop  286  and a second insert  288  having an armature forward stop  290 . The inserts  284 ,  288  are preferably manufactured from a plastic such as Teflon, and may alternatively be a unitary part. Like the armature  124  (FIG. 6) discussed above, the armature  232  (FIG. 11) is attached to the needle stem  234  in a manner which causes the needle stem  234  to travel with the armature  232 . Specifically, the armature  232  may be attached to the needle stem  234  using a roll pin  292  or the like which extends through both the armature  232  and the needle stem  234 . When the coil  282  is energized, a magnetic force is created, causing the armature  232  to travel in an upward direction  294  until a flange  296  on the armature  232  reaches the armature back stop  286 . Since the needle stem  234  is connected to the armature  232  as noted above, this upward action by the armature  232  pulls the needle stem  234  away from the valve seat  242  (FIGS. 9 and 10) and allows liquefied gas  228  (FIGS. 8 and 9) to flow out of the outflow line  244 . The injector apparatus  80  is then in the “open” operating state as shown in FIGS. 9-11. When the coil  282  is no longer energized, (i.e., when a predetermined amount of liquefied gas  228  has exited the outflow line  244  into a container  14  (FIGS.  1 - 3 ), the armature  232  and needle stem  234  are pushed in a downward direction  295  by a biasing assembly  300 . The armature flange  296  is urged toward the armature forward stop  290 , and the needle stem  234  blocks the outflow line  244  from receiving liquefied gas  228 . The injector apparatus  80  is then in the “closed” operating state as shown in FIG.  8 . The “stroke” of the armature  232  is defined by the distance “D4” between the forward stop  290  and the armature flange  296  when the armature flange  296  is adjacent to the back stop  286  as shown in FIG. 11 (i.e., when the injector apparatus  80  is in the “open” operating state). The distance “D4” may be the same as the distance “D”, FIG. 6, discussed above relative to the armature  124 . 
     As best shown in FIG. 11, the biasing assembly  300  may comprise a first biasing device  302  such as a spring coaxially aligned with and nested inside a second biasing device  304  such as a larger-diameter spring. The needle stem  234  may have an extending portion  306  on which the biasing devices  302 ,  304  may be mounted to assist in supporting and maintaining the coaxially alignment of the biasing devices  302 ,  304 . The first biasing device  302  is designed to exert a downward  295  force on the needle stem  234 , while the second biasing device  304  is designed to exert a downward  295  force on the armature  232 . The injector apparatus  80  may further comprise an adjuster  310  which, like the adjuster  146  (FIG. 6) discussed above, assists in mounting the solenoid  230  to the chamber  200 . A Teflon O-ring  312  may be provided between the adjuster  310  and the first insert  284  to prevent leakage of the liquefied gas  228  (FIGS.  8  and  9 ). 
     As noted above, the injector apparatus  80  may further comprise an adjustment device  226  operatively connected to the valve seat  242  (FIGS. 9 and 10) for adjusting the position of the valve seat  242  relative to the needle stem  234 . Because a high-performance, quick-responding solenoid has a very limited stroke as described above, some allowance must be made for manufacturing tolerance buildup between the valve seat  242  and the tapered end portion  248  (FIG. 10) of the needle stem  234 . The adjustment device  226  is provided in order to ensure that the needle stem  234  is seated properly within the valve seat  242  when the injector apparatus  80  is in the “closed” operating state, and that adequate clearance is provided between the needle stem  234  and the valve seat  242  in the “open” operating state, thus providing a proper dosage of liquefied gas  228  into the containers  14  and avoiding atomization of the exiting liquefied gas  228 . As shown in FIG. 11, the adjustment device  226  may comprise a housing  220  with an outer threaded portion  222  which engages an inner threaded portion  212  of the chamber  200 . As noted above, the needle stem  234  is connected to the armature  232 , and the armature  232  is secured between the first insert  284  and second insert  288 . The inserts  284 ,  288 , are positioned within the housing  220 . Also, as shown in FIG.  10  and described above, the valve seat  242  is located within the valve body  250 , which is secured to the chamber  200 . Thus, by rotating the housing  220  relative to the chamber  200  (or rotating the chamber  200  relative to the housing  220 ), the position of the valve seat  242  (FIGS. 9 and 10) relative to the needle stem  234  may be adjusted. As shown in FIG. 11, a threaded locking nut  224  which engages the outer threaded portion  222  of the housing  220  may be used to selectively lock in the desired position of the housing  220  on the chamber  200 . The housing  220  and threaded locking nut  224  may both be manufactured from a metal such as stainless steel. A Teflon O-ring  314  may be provided between the housing  220  and chamber  200  to prevent leakage of the liquefied gas from the chamber  200 . 
     While illustrative and presently preferred embodiments of the invention have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed, and that the appended claims are intended to be construed to include such variations, except as limited by the prior art.