Abstract:
A method for filling a dual fluid cartridge assembly which automatically bleeds air from the cartridge to filling and without extra steps or a vacuum as in known filling methods. In particular, the process relates to providing a dual fluid cartridge assembly which includes vents that bleed air from the cartridges initially and automatically closes the vents as the piston seal moves away from the vent. By utilizing such a self-bleeding cartridge assembly, the cartridge can be filled by a fluid dispenser without the need for shims, a vacuum or bleed plugs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to International Patent Application No. PCT/US03/17997. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Technical Field  
           [0003]    The present invention relates to a filling process and more particularly to a filling process for automatically filling dual fluid cartridge assemblies.  
           [0004]    2. Description of the Prior Art  
           [0005]    Fluid cartridge assemblies are generally known in the art. Both single and multiple fluid cartridge assemblies are known. An example of a single fluid cartridge assembly is disclosed in commonly owned international patent application number PCT/US02/39041, filed on Dec. 6, 2002. Such a fluid cartridge assembly is used to dispense a single fluid.  
           [0006]    Dual fluid cartridge assemblies are also known. Examples of such dual fluid cartridge assemblies are disclosed in U.S. Pat. Nos. 4,220,261; 4,961,520; and 5,310,091. Such dual fluid cartridge assemblies are known to be used to dispense fluid materials, such as thermoset adhesives, which typically contain two fluids that need to remain separated and applied to a workpiece quickly after mixing.  
           [0007]    U.S. Pat. No. 5,310,091 discloses a dual fluid cartridge assembly configured with a front and rear chamber formed by an inner cartridge and an outer cartridge, respectively. Upper and lower piston seals are used to separate the fluids within the cartridges. Movement of the inner cartridge, for example, under the influence of a plunger of a conventional caulking gun, causes the inner cartridge to advance axially within the outer cartridge. The inner cartridge is in fluid communication with a hollow delivery tube which extends through a front chamber up to a cartridge outlet nozzle. Movement of the inner cartridge within the outer cartridge causes fluids in the inner cartridge and outer cartridge to be dispensed.  
           [0008]    A problem exists with filling such cartridges. In particular, it is normally necessary to bleed air from the cartridge to prevent air from being trapped within the cartridge during filling. Such trapped air is known to have a negative impact on the ability to control the volumetric ratio of the fluids dispensed. If air is trapped in the inner cartridge, for example, the initial movement of the piston seals and accompanying increase in pressure in the cartridge chamber will act will cause that air to be compressed rather than to force fluid out of the outlet of the cartridge. Therefore, as the pressure in the cartridge increases during the early phase of the dispensing cycle, a smaller amount of the fluid in the inner cartridge will be dispensed than is desired. As the pressure in the cartridge decreases later, the air still trapped in the inner cartridge will expand and cause a larger than desired amount of fluid to be dispensed from the inner cartridge during the later phase of the dispensing cycle. If a different amount of air is trapped in the outer cartridge, the air will compress and expand at different rates than that of the air in the inner cartridge chamber. The difference in these rates will cause variation in the ratio of the fluids dispensed from the two cartridge chambers. This variation may have a negative impact on the performance of the fluids to be mixed.  
           [0009]    To avoid this problem, various methods are known for removing air from the cartridge chambers after filling, during piston insertion. For example, shims or wires are known to be automatically inserted adjacent the piston seal prior to piston insertion and used as a method for bleeding air from the cartridge. The shims are removed after the pistons are inserted. This method is known to be used with relatively high viscosity fluids.  
           [0010]    Unfortunately, there are several problems associated with this method. First, the shims can become fouled by way of contact with a fluid, thus eliminating or reducing the effectiveness of the shims. Second, the shims and wires are prone to breaking and curling due to their relatively small cross sections. Third, such shims and wires must be replaced periodically. Fourth, burrs and sharp edges along the length of the shims are known to damage the piston seal and thus affect its performance. Lastly, the use of wires or shims requires extra steps and thus increases the cost of filling the cartridge assembly.  
           [0011]    Another known method for removing air from a cartridge before filling is use of a vacuum. Unfortunately, since it takes time to draw a vacuum, this approach increases the time required to fill the cartridge.  
           [0012]    Finally, some systems are known to employ bleed plugs which include a vent for allowing air to escape. With this type of system, the vent is plugged after all of the air has been expelled between the piston and fluid within the cartridge. Unfortunately, such systems require additional steps and components and thus increase the time and cost of filling such cartridges. Thus, there is a need for a cartridge filling method which allows the cartridges to be filled quickly and easily while bleeding air from the cartridges without the need for extra steps or the need for a vacuum.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention relates to a method for automatically filling a fluid cartridge assembly which automatically bleeds air from the cartridge prior to filling with less steps relative to known filling methods and without the need for a vacuum. The process relates to providing a self-bleeding dual fluid cartridge assembly which includes vents that bleed air from the cartridges initially and automatically closes the vents as the piston seal moves away from the vent. By utilizing such a self-bleeding cartridge assembly, the cartridge can be filled by an automatic fluid dispenser without the need for shims, a vacuum or bleed plugs. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0014]    These and other advantages of the present invention will be understood with reference to the following specification and attached drawing wherein:  
         [0015]    [0015]FIG. 1 is an elevational view of a conventional cartridge gun shown in partial cutaway illustrating a dual fluid cartridge assembly in accordance with the present invention.  
         [0016]    [0016]FIG. 2 is a front view of a dual fluid cartridge assembly in accordance with the present invention.  
         [0017]    [0017]FIG. 3 is a sectional view along a line  3 - 3  of FIG. 2, illustrating the dual fluid cartridge assembly in accordance with the present invention in a filled position.  
         [0018]    [0018]FIG. 4 is similar to FIG. 3 but illustrating the dual fluid cartridge assembly in an empty position.  
         [0019]    [0019]FIG. 5 is an enlarged detailed view illustrating the connection between an inner cartridge tube and a nose outlet in accordance with the present invention.  
         [0020]    [0020]FIG. 6 is a partial simplified view of the air vent path formed in the inner cartridge in accordance with the present invention.  
         [0021]    [0021]FIG. 7 is a right side view of an inner cartridge in accordance with the president invention illustrating a number of radial slots formed in a base portion of the inner cartridge.  
         [0022]    [0022]FIG. 8 is a sectional view along line  8 - 8  of FIG. 7 illustrating the inner cartridge in accordance with the present invention.  
         [0023]    [0023]FIG. 9 is a left side view of the inner cartridge in accordance with the present invention.  
         [0024]    [0024]FIG. 10 is a left side view of an outer cartridge in accordance with the present invention.  
         [0025]    [0025]FIG. 11 is a section view along line  11 - 11  of FIG. 10 of the outer cartridge in accordance with the present invention.  
         [0026]    [0026]FIG. 12 is an enlarged detailed view of the inner nose outlet portion of the inner cartridge in accordance with the present invention.  
         [0027]    [0027]FIG. 13 is an enlarged view of the outer nose outlet portion of the outer cartridge in accordance with the present invention.  
         [0028]    [0028]FIG. 14 is a sectional view of a piston seal and delivery tube in accordance with the present invention.  
         [0029]    [0029]FIG. 15 is an enlarged sectional view of the one end of the delivery tube in accordance with the present invention.  
         [0030]    [0030]FIG. 16 is a top view of an upper piston seal for use with the present invention.  
         [0031]    [0031]FIG. 17 is a sectional view along lines  17 - 17  of FIG. 16.  
         [0032]    [0032]FIG. 18 is a partial perspective view of the outer cartridge in accordance with the present invention illustrating slots for providing an air vent for the outer cartridge in accordance with another aspect of the present invention.  
         [0033]    [0033]FIG. 19 is a plan view of an open end of the outer cartridge illustrated in FIG. 18.  
         [0034]    [0034]FIG. 20 is an enlarged detailed view of a portion of the outer cartridge illustrating the vent slots.  
         [0035]    [0035]FIG. 21 is a side view of an automatic filling station for use in accordance with the present invention.  
         [0036]    [0036]FIG. 22 is similar to FIG. 21 but represents a front view. 
     
    
     DETAILED DESCRIPTION  
       [0037]    The present invention relates to a method for filling a dual fluid cartridge assembly which automatically fills and bleeds the cartridge assembly prior to filling without additional steps and without a vacuum. Unlike other known methods for filling dual fluid cartridge assemblies, the method in accordance with the present invention utilizes an automatic filling machine in conjunction with a self-bleeding dual fluid cartridge assembly that is configured with a vent to atmosphere which allows air in the inner cartridge to be automatically evacuated during the fill process in order to prevent any trapped air pockets within the fluid in the inner cartridge. A vent may also be optionally provided in order to vent trapped air from the chamber formed by the outer cartridge as well.  
         [0038]    The method in accordance with the present invention is adapted to be utilized with a dual fluid cartridge assembly as illustrated in FIGS. 2-20 and described below. An exemplary filling machine for automatically filling the dual fluid cartridge assembly is illustrated in FIGS. 21 and 22 and is also described below.  
       Dual Fluid Cartridge Assembly  
       [0039]    Referring first to FIGS. 2-20, a dual fluid cartridge assembly for use with the filling process in accordance with the present invention is illustrated. In accordance with an important aspect of the invention, the dual fluid cartridge assembly  30  is provided with a vent path to atmosphere which allows air in the inner cartridge and optionally the outer cartridge to be evacuated to atmosphere during filling of the inner and outer cartridges to prevent trapped air pockets therein. Such trapped air pockets are known to result in voids in the fluid in the inner and outer cartridges resulting in non-homogeneous mixing of the fluids thereby decreasing the performance of the fluids.  
         [0040]    [0040]FIG. 3 illustrates the dual fluid cartridge assembly  30  in a filled position, while FIG. 4 illustrates the dual fluid cartridge assembly  30  in an empty position. As shown the dual fluid cartridge assembly  30  includes an outer cartridge  32 , an inner cartridge  34 , an integral piston seal and delivery tube  36  having a lower seal  39 ; and an upper piston seal  38 .  
         [0041]    In accordance with an important aspect of the invention, a vent path to atmosphere is provided from the inner cartridge  34  when the inner cartridge  34  is in an empty position, as illustrated in FIG. 4. Filling of the inner cartridge  34  is done by way of a cartridge outlet nozzle  40 . The cartridge outlet nozzle  40  is formed as a tubular member with an axial separator wall  41 , which forms two side by side chambers for enabling filling of each of the fluids. In order to fill the inner cartridge  34 , fluid is applied through the cartridge outlet nozzle  40  through the piston tube  36  into a chamber forming the inner cartridge  34 , beginning when the inner cartridge  34  is in the position shown in FIG. 4 until the inner cartridge is full. Similarly, the outer cartridge  32  is also filled by way of the cartridge outlet nozzle  40 .  
         [0042]    Turning to FIGS. 6-9, the inner cartridge  34  includes a circular base plate  42  and a cylindrical sidewall  44 . A separator rod  46  projects upwardly from the base plate  42  and extends to a mouth  43  of the cylindrical sidewall  44  of the inner cartridge  34 . Slots, for example, radial slots, generally identified with the reference numeral  48 , are formed in the base plate  42  of the inner cartridge  34 . As best shown in FIG. 6, the slots  48  formed in the base plate  42  of the inner cartridge  34  extend partially up the sidewall  44  in an axial direction, as indicated by the reference numeral  50 . As best shown in FIGS. 4, 6 and  11 , the slots  48  and  50  allow trapped air in the inner cartridge  34  to escape up along the sidewall  44  of the inner cartridge  34  and bleed to the outside of the inner cartridge  34  by way of one or more notches  52 , formed at the mouth  43  of the inner cartridge  34 . Air escapes by way of clearance between the outside diameter of the inner cartridge  34  and the inside diameter of the outer cartridge. As the inner cartridge  34  moves away from the (stationary) lower seal  39  the vent path is closed.  
         [0043]    [0043]FIGS. 10-13 illustrate the outer cartridge  32 . As shown, the outer cartridge  32  is formed as a cylindrical member having a base plate  33  and a cylindrical sidewall  35  with a diameter slightly larger than the diameter of inner cartridge  34  to allow free axial movement of the inner cartridge  34  therewithin. The outer cartridge  32  is formed with the cartridge outlet  40  used for filling and dispensing the fluids from the inner cartridge  34  and outer cartridge  32 . As shown in FIGS. 3, 5 and  12 , the outer cartridge  32  includes an offset flange  56  for connection to the piston tube  36 . As shown best in FIG. 5, the connection between the offset flange  56 , the outer cartridge  32  and the piston seal and delivery tube  36  may be a snap connection. A delivery tube portion  37  of the piston seal and delivery tube  36  forms a conduit from the inner cartridge  34  to the nose portion  40 . Fluid in the outer cartridge  32  is dispensed into an offset opening  60 . Accordingly, the offset openings  58  and  60  formed along an inner wall  33  of the outer cartridge  32  together with the separator wall  41  (FIG. 2) allow the fluid from the inner cartridge  34  and the outer cartridge  32  to be discharged side by side out of the cartridge outlet nozzle  40 .  
         [0044]    [0044]FIGS. 14 and 15 illustrate the piston seal and delivery tube  36 . As mentioned above, the piston seal and delivery tube  36  includes an elongated tube  37  and a lower piston seal  39 . The lower piston seal  39  of the piston seal and delivery tube  36  may be formed, for example, with a circumferential slot  68  for receiving and an O-ring (not shown). The lower seal portion  39  seals the fluid in the inner cartridge  34  from the rest of the assembly  30 . As mentioned above, an extending end  70  of the piston tube  36  may be formed with a circumferential slot  72 , adjacent the extending end  70 . As mentioned above and as illustrated in FIG. 5, this circumferential slot  72  cooperates with a mating slot formed in the flange  56  (FIG. 5) to provide a snap connection between the piston tube  36  and the flange  56 .  
         [0045]    [0045]FIGS. 16 and 17 illustrate the upper seal  38 . The upper seal  38  seals the fluid in the outer cartridge  32 . As shown, the upper seal  38  may be provided with a circumferential slot  74  for receiving an O-ring (not shown). The seals  38  and  39  may alternatively be formed with equivalent configurations, such as radial extending lips or a combination of o-rings and radial extending lips.  
         [0046]    In accordance with another aspect of the invention, the cartridge assembly  30  is optionally configured with another vent path for venting air from the outer cartridge  32  to atmosphere to avoid trapping air in the outer cartridge  32 . In particular with reference to FIGS. 18 through 20, one or more vent slots  80  may optionally be formed on the interior of the cylindrical sidewall  35  of the outer cartridge  32 . These vent slots  80  extend from the base plate  32  (FIGS. 11 and 18) and extend in an axial direction, as shown in FIG. 18. The vent slots  80  may be disposed in a direction, for example, 180 degrees from the direction of the cartridge outlet offset, as generally shown in FIG. 18. Thus, when the upper seal  38  is in a position as shown in FIG. 4, the axial slots  80  provide a vent path around the upper seal  38  which allows air from the outer cartridge  32  to be vented by way of clearance between the outside diameter of the inner cartridge  34  and the inside diameter of the outer cartridge. As soon as the upper seal  38  is out of engagement with the axial slots  80 , the vent path for the outer cartridge  32  is closed.  
         [0047]    The fluids in the cartridge assembly  30  are dispensed by way of a conventional caulking gun  20 , as shown in FIG. 1, which includes a plunger  22 , a handle  24 , a trigger  26  and a nose piece  28 . In operation, as the plunger  22  advances in an axial direction toward the nose piece  28  of the caulking gun  20  (assuming a ratchet arm  32  is in the position shown in FIG. 1), the inner cartridge  34  moves in an axial direction toward the nose portion  40  (FIG. 3). As the inner cartridge  34  advances in an axial direction, fluid from the inner cartridge  34  is forced into the piston tube  36  and to the nose portion  40 . Initially, as shown in FIG. 3, the upper seal and the piston seal  39  are side by side when the cartridge assembly  30  is full. As the inner cartridge  34  advances to the left as shown in FIG. 4, the inner cartridge  34  pushes the upper seal  38  to the left, which forces fluid in the outer cartridge  32  to be dispensed out the cartridge outlet  40 . This axial movement of the inner cartridge within the outer cartridge results in dispensing of the fluids and application of the fluids to a work piece by way of a cartridge outlet and a nozzle, such as a static mixing nozzle, in a similar manner as disclosed in U.S. Pat. No. 5,310,091, hereby incorporated by reference.  
       Filling Method  
       [0048]    The inner cartridge  34  is filled with a fluid by way of the cartridge outlet nozzle  40 . In particular, a fill nozzle  114  (FIG. 22) is inserted in the cartridge outlet nozzle  40  and into the inlet opening  58  (FIG. 11). As discussed above, the inlet opening  58  is in fluid communication with the delivery tube portion  37  (FIG. 5) of the piston seal and delivery tube  36  (FIG. 4), which, in turn, is in fluid communication with the inner cartridge  34  (FIG. 3). When the inner cartridge  34  is in the position as shown in FIG. 4, fluid is filled through the delivery tube portion  37  (FIG. 5) toward the bottom or base portion  42  (FIG. 6) of the inner cartridge  34 . In the position shown in FIG. 4, the inner cartridge vent is open to atmosphere. In particular, in this position, as fluid fills the inner cartridge  34 , air is pushed into the slots  48  (FIG. 6) in the base portion  42  of the inner cartridge  34 . As the fluid continues to fill the inner cartridge  34 , air is pushed up through the axial slots  50  and bleeds through the notches  52  formed in the mouth  43  of the inner cartridge  34 , to atmosphere.  
         [0049]    After the inner cartridge  34  (FIG. 3) is filled, the outer cartridge  32  may be filled with a second fluid. The outer cartridge  32  is also filled by way of the fill nozzle  114  (FIG. 22)through the cartridge outlet nozzle  40  but through the opening  60  (FIG. 11). After the inner cartridge  34  and outer cartridge  32  are filled, a cap (not shown) may be used to close the cartridge outlet nozzle  40  of the cartridge assembly  30 . Filling of the outer cartridge  32  may begin once the delivery tube  37  is filled with fluid and the air has been exhausted from the inner cartridge  34 . Filling of the outer cartridge  32  must always lag filling of the inner cartridge  34  by a volume at least as large as the volume of the delivery tube  37  until the inner cartridge  34  has been filled completely, at which time the filling of the outer cartridge  32  can catch up. This is important to prevent air from getting sucked into the inner cartridge  34  if the filling of the inner cartridge  34  gets ahead of it. Second, the same vent groove method may be used to bleed air from the outer cartridge  32  as the method described for use in the inner cartridge  34 .  
         [0050]    An exemplary automatic filling machine is illustrated in FIGS. 21 and 22 and identified with the reference numeral  100 . The filling machine  100  may be, for example, a Model No. BH-DUAL CMP-632 X 9 by Adhesive Systems Technology Corporation of New Hope, Minn., as described in detail in their CMP Series Instruction Manual AST #60000049, hereby incorporated by reference. Other filling machines may also be used.  
         [0051]    [0051]FIG. 22 illustrates a side view while FIG. 21 illustrates a front view of the filling station  100 . FIG. 21 is shown with a dual fluid cartridge assembly  30  loaded into the filling station  100 .  
         [0052]    The filling machine  100  is adapted to be used with two (2) gravity fed reservoirs (not shown)—one for each fluid—and two (2) independent metering pumps (not shown). The metering pumps are coupled to a pair of metering valves  101  and  103  (FIG. 21) on the filling station  100  by way of flexible conduits (not shown).  
         [0053]    As best shown in FIG. 22, the filling station  100  includes a fixture  106  for carrying the dual fluid cartridge assembly  100 . The fixture  106  includes a lower plunger  108  for pushing the inner cartridge  34  to the EMPTY position as shown in FIG. 4 by way of an air cylinder  109  and holding the inner cartridge  34  in that position. This action holds the vent grooves ( 50 ) in communication with the lower seal  39  until all the air in the delivery tube  37  and inner cartridge  34  has been replaced by fluid.  
         [0054]    The fixture  106  also includes an upper horizontal member  110 . The horizontal member  110  includes an aperture  112  for receiving a fill nozzle  114 , mounted on a movable member  116 . Subsequently a button (not shown) is depressed by the operator to begin the cycle. Other embodiments contemplate a proximity sensor that senses the presence of the cartridge as a trigger to begin the filling cycle. After the cycle is initiated by depressing the button, an air cylinder  118  causes the vertical member  116  and the fill nozzle  114  to move downwardly and fully engage and seal the cartridge outlet nozzle  40  (FIG. 18). The fill nozzle  114  enables fluids to be pumped into the offset openings  58  and  60  (FIG. 11) of the dual fluid cartridge assembly  30 .  
         [0055]    In operation, the cartridge outlet nozzle  40  is manually registered and mated with the fill nozzle  114 . The air cylinder  118  pushes the movable member  116  and the fill nozzle  114  downwardly. The other air cylinder  109  pushes the plunger  108  upwardly which causes the inner cartridge  34  to move to the EMPTY position as shown in FIG. 4. The air cylinder  109  holds the inner cartridge  34  in the EMPTY position while the air is bled out of it, as discussed above. In particular, as the metering pump begin to pump fluid from the fluid reservoir, air is bled from the inner cartridge  34  as discussed above. Once a predetermined and adjustable volume of fluid has been pumped into the inner cartridge  34 , the air cylinder  109  releases the inner cartridge  34 . A continued inflow of fluid causes the inner cartridge  34  to move away from the EMPTY position, as illustrated in FIG. 4, and close the vent to atmosphere. Subsequently, fluids may be pumped individually or simultaneously into the inner cartridge  34  and the outer cartridge  32 . The metering pumps dispense a preset amount into each of the inner cartridge  34  and the outer cartridge  32 . After the inner cartridge  34  and outer cartridge  32  are filled, the vertical member  116 , under the influence of the air cylinder  118 , returns to the home position, as shown in FIG. 22, to enable the filled cartridge to be removed.  
         [0056]    Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described above.