Abstract:
A paint cartridge includes a housing and a piston slidably disposed within a cavity in the housing to divide the cavity into a paint chamber and a solvent chamber. A valve assembly extends through an aperture in the piston to selectively put the paint chamber in fluid communication with the solvent chamber. A solvent inlet provides solvent to the solvent chamber to move the piston. Movement of the piston discharges paint from the paint chamber through the paint outlet.

Description:
BACKGROUND 
       [0001]    Current paint delivery systems capable of delivering multiple paint colors present a number of challenges with regard to waste and inefficiency during color changes. These systems are particularly inefficient in low volume applications. Even with improvements to existing systems, there can still be up to 40% wasted paint on non-recirculated paint supplies. In addition to wasted paint, large quantities of solvent are used to flush the pump for a color change. This is largely due to the distance between the paint supply and the applicator, which requires that the system be cleaned when changing paint colors. Thus, there is a need for a paint delivery system that allows for the delivery of multiple colors while minimizing wasted materials. 
       SUMMARY 
       [0002]    In a first exemplary embodiment, a paint cartridge includes a housing and a piston slidably disposed within a cavity in the housing to divide the cavity into a paint chamber and a solvent chamber. A valve assembly extends through an aperture in the piston to selectively put the paint chamber in fluid communication with the solvent chamber. A solvent inlet provides solvent to the solvent chamber to move the piston. Movement of the piston discharges paint from the paint chamber through the paint outlet. 
         [0003]    In a second exemplary embodiment, a paint cartridge has a housing with an internal cavity. A piston is slidably disposed within the internal cavity and divides the internal cavity into a paint chamber and a solvent chamber. A valve assembly selectively opens and closes fluid communication between the paint chamber and the solvent chamber. A solvent supply provides pressurized solvent to the solvent chamber to move the piston. 
         [0004]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0005]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0006]      FIG. 1  shows an isometric view of an exemplary embodiment of a paint robot; 
           [0007]      FIG. 2  shows an isometric view of a docking station of the paint robot of  FIG. 1 ; 
           [0008]      FIG. 3  shows a side cross-sectional view of the docking station of  FIG. 2 ; 
           [0009]      FIG. 4  shows an isometric view of a paint cartridge that is mountable to the docking station of  FIG. 2 ; 
           [0010]      FIG. 5  shows an isometric cross-sectional view of the paint cartridge of  FIG. 4 ; 
           [0011]      FIG. 6  shows a side cross-sectional view of the paint cartridge of  FIG. 4  with the paint cartridge full of paint; 
           [0012]      FIG. 7  shows a side cross-sectional view of the paint cartridge of  FIG. 4  with the paint discharged from the cartridge; 
           [0013]      FIG. 8  shows a side cross-sectional view of a piston assembly of the paint cartridge of  FIG. 4 ; 
           [0014]      FIG. 9  shows a partially exploded side cross-sectional view of the piston assembly of  FIG. 8 ; and 
           [0015]      FIG. 10  shows a partial side cross-sectional view of the paint cartridge of  FIG. 4  with the piston assembly engaging an end fitting of the paint cartridge. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]      FIG. 1  shows an exemplary embodiment of a paint robot  20  suitable for use in an industrial setting. The robot  20  includes a base  22  having a lower portion  24  mounted to the floor or another suitable mounting surface. An upper portion  26  of the base  22  is rotatably mounted to the lower portion  24  about a vertical axis so that the upper and lower portions  24  and  26  cooperate to form a turntable structure. An arm  28  is rotatably coupled to the upper portion  24  of the base  22  at a first end about a horizontal axis. 
         [0017]    A sprayer  30  is rotatably coupled to a second end of the arm  28  about a horizontal axis. A nozzle  32  is disposed at one end of the sprayer  30 , and a docking station  50  is mounted to the top of the sprayer. As will be described in greater detail, docking station  50  is configured to receive a paint cartridge. When mounted to the docking station  50 , the paint cartridge is in fluid connection with the nozzle  32  so that paint from the cartridge can be selectively discharged through the nozzle during operation. To utilize a different paint color or to replace a depleted paint cartridge, the paint cartridge  100  is removed from the docking station  50  and replaced with a cartridge having a different paint or a cartridge of the same color that is full of paint. A flexible conduit  34  extends from the base  22  to the nozzle  32  to house various electrical lines, pneumatic lines, solvent supply lines, etc., that control the position of the sprayer  30  and the discharge of paint from the nozzle  32 . 
         [0018]    It will be appreciated that the illustrated paint robot  20  is exemplary only and should not be considered limiting. In this regard, the presently disclosed paint system can be used with any number of suitable paint systems. 
         [0019]    Referring now to  FIGS. 2 and 3 , the docking station  50  will be described. The docking station  50  includes a base  52  sized and configured to receive a cartridge  100  therein. The base  52  includes a plurality of support members  54  extending across the base to support the cartridge  100 . A lid  56  is hingedly coupled to the base  52  by a plurality of hinges  58 . In the illustrated embodiment, the hinges  58  are spring loaded to bias the lid  56  toward an open position. To close the docking station  50 , the lid is rotated about the hinges  58  to a closed position and held in place with a latch  60 . 
         [0020]    Disposed at opposite ends of the docking station  50  are a supply fitting  62  and a discharge fitting  64 . As will be discussed in further detail, the supply fitting  62  engages one end of the cartridge  100  to provide pressurized solvent to the cartridge, and the discharge fitting  64  engages an opposite end of the cartridge such that paint exits the cartridge through the discharge fitting. In the illustrated embodiment, the supply fitting  62  is coupled to a pair of pneumatic clamping cylinders  66 . The clamping cylinders are secured to the base  52  of the docking station  50  and are positioned to selectively move the supply fitting  62  toward the discharge fitting  64 , so that the supply fitting and discharge fitting engage the cartridge to releasably secure the cartridge within the docking station  50 . 
         [0021]    The docking station  50  further includes a sensor  68 . In the illustrated embodiment, the sensor  68  extends longitudinally along the docking station  50  in proximity to the cartridge  100 . As will be described in further detail, the sensor  68  senses information regarding the amount of paint in the cylinder to allow for the system to manage the paint supply. 
         [0022]    As shown in  FIGS. 4 and 5 , the paint cartridge  100  includes a cylindrical housing  102  having a first end  104  and a second end  106 . A first end fitting  110  is secured to the opening of the first end  104  of the housing  102  by a press-fit installation, threaded engagement, or other suitable configuration. A connector  112  sized and configured to provide a fluid connection with the supply fitting  62  of the docking station  50  is coupled to the first end fitting  110  so that when the cartridge  100  is mounted to the docking station, the supply fitting  62  is in fluid communication with an interior portion of the housing  102 . 
         [0023]    A second end fitting  120  is removably secured to a second end  106  of the housing  102  by a locking mechanism  124 . A valve  132 , which is preferably a drip-proof valve, is coupled to the second end fitting  120  and is sized and configured to provide a fluid connection with the discharge fitting  64  of the docking station  50  so that when the cartridge  100  is mounted to the docking station, the discharge fitting  64  is in fluid communication with an interior portion of the housing  102 . 
         [0024]    The locking mechanism  124  includes a plurality of threaded rods  126  rotatably coupled to the outer surface of the housing  102 . More specifically, each threaded rod  126  rotates about a pin  128  secured to the housing  102  such that the threaded rod is rotatable between a locked position, in which the threaded rod is parallel to the centerline of the housing, and an unlocked position, in which the threaded rod extends outwardly from the housing. 
         [0025]    To secure the second end fitting  120  to the housing  102 , the second end fitting is positioned against the end of the housing, and the threaded rods  126  are rotated to the locked position. When in the locked position, each threaded rod extends through a corresponding slot  122  formed in the end fitting. A nut  130  is then threadedly coupled to each threaded rod  126  so that the second end fitting  120  is secured between the nut and the housing  102 . An O-ring  134  is disposed between the second end fitting  120  and the housing  102  to ensure a fluid-tight connection therebetween. 
         [0026]    As best shown in  FIGS. 5-7 , a piston assembly  150  is slidably disposed within the housing  102 . The piston assembly  150  divides the interior of the cartridge  100  into a solvent chamber  230  and a paint chamber  240 . As the piston assembly  150  slides within the housing  102 , the volume of the solvent chamber  230  and paint chamber  240  change, such that when the volume of the solvent chamber  230  increases, the volume of the paint chamber  240  decreases by a corresponding amount. Similarly, a decrease in the volume of the solvent chamber  230  is accompanied by a corresponding increase in the volume of the paint chamber  240 . 
         [0027]    When the cartridge  100  is filled with paint, as shown in  FIG. 6 , the piston assembly  150  is positioned proximal to the first end fitting  110  so that the paint chamber  240  is at or near its maximum volume and is full of paint  242 . To discharge the paint  242  from the cartridge  100 , pressurized solvent  232  is introduced into the solvent chamber  230  through connector  112 . The pressure on the solvent side of the piston assembly  150  drives the piston assembly toward the second end fitting  120 , decreasing the size of the paint chamber  240  and forcing paint  242  out of valve  132 . The pressurized paint is supplied to the nozzle  32 , which directs the paint to a desired surface. As the volume of the paint chamber  240  decreases, the volume of the solvent chamber  230  increases and remains filled with solvent  232 . 
         [0028]    As the cartridge  100  approaches a fully discharged state, as shown in  FIG. 7 , a portion of the piston assembly  150  contacts the second end fitting  120  to open one or more valve assemblies  170  located in the piston assembly. With the valve assemblies  170  open, the solvent chamber  230  is in fluid communication with the paint chamber  240 . The pressurized solvent  232  in the solvent chamber  230  passes through the open valve assemblies and out the discharge valve  132 , cleaning the paint chamber  240  in the process. 
         [0029]    Referring to  FIGS. 8-9 , the piston assembly  150  includes a piston  152 . The outer diameter of the piston  152  is smaller than the inner diameter of the housing  102  so that the piston slides freely within the housing along the central axis of the housing. A pair of annular recesses  154  extends around the perimeter of the piston  152 . A piston ring  156  is partially disposed within each recess  154 . The piston rings  156  are illustrated as O-rings, however, it will be appreciated that any suitable piston ring configuration, such as a piston ring from an internal combustion engine, can be utilized. The piston rings  156  provide a generally fluid-tight seal between the outer surface of the piston  152  and the inner surface of the housing  102 . 
         [0030]    A third circumferential recess  164  extends around the perimeter of the piston  152  between the piston rings  156 . A plurality of magnets  166  are positioned within the recess  164 . The magnets  166  are sized and configured to be fully disposed within the recess  164  and are detectable by the position sensor  68 . 
         [0031]    Referring to  FIG. 8 , the piston assembly  150  includes one or more valve assemblies  170  extending through the piston  152 . The valve assemblies  170  are preferably positioned such that the centerline  172  of each valve assembly forms an angle with the centerline  108  of the housing  102 . More specifically, each valve assembly  170  is further away from the centerline  108  of the housing  102  on the paint chamber  240  side of the piston assembly  150  than on the solvent chamber  230  side of the piston assembly. It will be appreciated that the illustrated angles are exemplary only and should not be considered limiting. In this regard, the orientation of the valve assemblies  170  can vary. Further, the type and number of valve assemblies  170  of a particular embodiment can vary. These and other valve assembly configurations are contemplated and should be considered within the scope of the present disclosure. 
         [0032]    As shown in  FIG. 9 , each valve assembly  170  includes a first retainer fitting  174  threadedly coupled to a second retainer fitting  176 . The first and second retainer fittings  174  and  176  extend into a passage  158  formed in the piston  152  from opposite sides of the passage. The passage  158  has a smaller diameter in the central portion than at the ends so that shoulders  160  and  162  are formed within the passage. When the first and second retainer fittings  174  and  176  are coupled to each other, they exert a clamping force on the shoulders  160  and  162  that secures the retainer fittings within the passage  158  and, therefore, to the piston  152 . 
         [0033]    When coupled together and mounted to the piston  152 , the first and second retainer fittings  174  and  176  cooperate to form a valve retainer  180  that maintains a valve  210  in sliding relation to the piston  152 . Still referring to  FIG. 9 , the valve  210  has an elongate body  212  with a first end  214  and a second end  216 . A flange  218  extends radially outward from the elongate body  212  between the first and second ends  214  and  216  of the body. An  0 -ring  220  is mounted to the body next to the side of the flange  218  closest to the second end  216  of the body. The valve  210  further includes a plurality of grooves  222  extending longitudinally along the second end  216  of the body. 
         [0034]    When the valve assembly  170  is mounted to the piston  152 , the valve  210  is slidably retained within the valve retainer  180 . The flange  218  and the O-ring  220  are positioned within a cavity  182  in the valve retainer  180 . The cavity  182  is positioned between a first passage  184  formed in the first retainer fitting  174  and a second passage  186  formed in the second retainer fitting  176 . The first end  214  of the valve  210  is slidingly restrained by the first passage  184 , and the second end  216  of the valve is slidingly restrained by the second passage  186  so that the valve is slidable along the centerline  172  of the valve assembly  170 . 
         [0035]    A plurality of apertures  188  are formed in the first retainer fitting  175  so that the cavity  182  of the valve retainer  180  is in fluid communication with the solvent chamber  230 . When the valve  210  is in an open position (described later), the cavity  182  and thus, the solvent chamber  230 , are in fluid communication with the grooves  222  in the valve. The grooves  222  in the valve  210  are themselves in fluid communication with the paint chamber  240  by way of a plurality of apertures  190  formed in the second retainer fitting  176 . 
         [0036]    As shown in  FIGS. 8 and 9 , the valve  210  is positioned within the valve retainer  180  so that the flange  218  is disposed within the cavity  182  of the valve assembly  170  so that the O-ring  220  is located between the flange  218  of the valve and the second retainer fitting  176 . A spring  224  is positioned within the cavity  182  to bias the flange  218  toward the second retainer fitting  176 . Under typical operating conditions, the spring  224  biases the valve  210  so that the O-ring  220  maintains contact with the second retainer fitting  176  to block fluid communication between the cavity  182  and the grooves  222  in the valve, i.e., to seal the cavity from the grooves  222 . In this manner, separation between the solvent chamber  230  and the paint chamber  240  is maintained. 
         [0037]    Referring now to  FIG. 10 , as the piston assembly  150  approaches the second end fitting  120 , the valves  210  contact an interior surface of the second end fitting. As the piston assembly  150  continues to move toward the second end fitting  120 , the second end fitting drives the valves  210  from the closed position shown in  FIG. 8  to the open position shown in  FIG. 10 . With the valves  210  open, the solvent chamber  230  is in fluid communication with the paint chamber  240 . The higher pressure on the solvent side of the piston assembly  150  forces the solvent through the valve assemblies  170  into the paint chamber  240 , so that the solvent cleans residual paint out of the paint chamber before being discharged through the discharge valve  132 . In this manner, the paint chamber  240  and the discharge valve  132  are flushed of any residual paint. 
         [0038]    When the cartridge  100  is “empty,” i.e., has no paint in it, the piston assembly  150  is positioned next to the second end fitting  120 , and the solvent chamber  230  and paint chamber  240  are both filled with solvent. In one exemplary method of filling the cartridge  100  with paint, the locking mechanism  124  is disengaged, and the second end fitting  120  is removed from the cartridge. A pneumatic press is utilized to move the piston assembly  150  to a desired position within the housing  102 , wherein the position of the piston assembly corresponds to a desired amount of paint to be loaded into the cartridge  100 . The housing is then filled with paint, and the second end fitting  120  is mounted to the cartridge  100  and secured in place with the locking mechanism  124 . 
         [0039]    Referring back to  FIGS. 1 and 2 , one contemplated embodiment of a paint system utilizes multiple cartridges  100  in a single robot  20 , wherein each cartridge contains a different paint. When paint of a particular color is needed, the cartridge  100  containing that color is mounted to the docking station  50 , and the robot  20  applies that color paint to the work piece. When a different paint is needed, the first cartridge  100  is removed from the docking station  50  and placed in a storage area, such as supply rack. A second cartridge having the needed color is then removed from the supply rack and mounted to the docking station  50 . Because solvent is used to pressurize the cartridge, only the lines between the cartridge and the nozzle need to be cleaned prior to utilizing a cartridge having a different color paint. In one contemplated embodiment, the supply rack is a rotating rack that positions a cartridge slot for removal or return of a paint cartridge. 
         [0040]    The previously described sensor  68  tracks the position of the piston assembly  150  by sensing the position of one or more of the magnets  166  positioned in the groove  164  of the piston  152 . The position of the piston assembly  150  is sent to a cpu and/or controller (not shown) that utilizes the information for various functions. For example, by determining the piston assembly  150  position, it can be verified that the paint cartridge is fully flushed of all paint before removal from the docking station  50 . The position of the piston assembly  150  can also be utilized to determine if the amount of paint in a canister  100  is sufficient to complete an upcoming paint job. In another contemplated embodiment, a sensor is included in the paint filling station and is used to help position the piston assembly and, therefore, paint capacity based on the requirements of an upcoming paint job. These and other embodiments for using the position of the piston assembly for various tasks are contemplated and should be considered within the scope of the present disclosure. 
         [0041]    In the illustrated embodiment, the magnets  166  are neodymium magnets, and the sensor  68  is a linear magnetorestrictive transducer. The sensor  68  sense the position of the magnets through the housing  102  of the paint cartridge  100 , which in the illustrated embodiment is made of stainless steel. It will be appreciated that the present disclosure is not limited to the neodymium magnets and a magneto restrictive transducer, but can include any suitable sensor system suitable of sensing the position of the piston assembly  150  within the cartridge  100 . It will be further appreciated that different sensor systems may be more suitable than others depending upon the material from which the housing  102  is made. 
         [0042]    It will be appreciated that the disclosed paint cartridge  100  is suitable for use in a number of applications, and the exemplary embodiments disclosed herein should not be considered limiting. In this regard, the disclosed paint cartridge can be used in conjunction with manual paint applicators or in systems applying a single paint color. These and other applications that could utilize a replaceable paint cartridge are contemplated and should be considered within the scope of the present disclosure. 
         [0043]    While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.