Patent Publication Number: US-7588196-B2

Title: Cartridge-type coating machine and cartridge thereof

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a cartridge-type coating machine to which a cartridge for storing paint therein is detachably attached, and relates to the cartridge thereof. 
   2. Background Art 
   A rotary atomizing head type coating machine is used widely for coating a target such as a car body. 
   Recently, coating is desired to be more inexpensive, and to deal with multicoloring for heightening a design quality. Therefore, the coating machine is required to reduce the amount of paint and solvent wasted at the time of changing colors, and to deal with a large number of colors. 
   To reduce the wasted paint and solvent and to increase colors, there is a conventional rotary atomizing head type coating machine provided with cartridges for storing respective paints of different colors, which are exchangeable to be selectively attached to the coating machine to correspond to a coated target such as a car body. 
   For example, as described in the Japanese Patent Laid Open Gazette Hei. 11-262699, this rotary atomizing head type coating machine comprises a housing. A front part of the housing is a coating device attachment part to which a coating device is attached. A rear part of the housing is a cartridge attachment part. The coating device includes an air motor having a rotary shaft, and a rotary atomizing head provided on the rotary shaft in front of the air motor. 
   A feed tube insertion hole, whose front end is opened to the rotary atomizing head and whose rear end is opened to the cartridge attachment part of the housing, is formed axially in the rotary shaft of the air motor constituting the coating device. 
   In the rotary atomizing head type coating machine, the cartridge is detachably attached to the housing. This cartridge comprises a bomb, in which paint is stored, and a feed tube extended axially outward from the bomb. The bomb is detachably attached into the cartridge attachment part of the housing, and the feed tube is inserted into the feed tube insertion hole. 
   Cartridges storing respective paints of different colors are prepared, so that one of the cartridges can be selectively attached to the coating machine so as to correspond to a color used for coating. 
   The cartridge is provided therein with a movable partition. A space in the bomb is divided by the partition into a paint storage chamber, communicated with the feed tube, and an pressure air storage chamber. The cartridge is also provided therein with a cartridge-side pressure air passage for supplying pressure air to the pressure air storage chamber. 
   Furthermore, the housing is provided therein with a housing-side pressure air passage communicated with the cartridge-side pressure air passage. 
   By charging pressure air into the pressure air storage chamber through the housing-side and cartridge-side pressure air passages, the movable partition is moved so as to pass paint in the paint storage chamber to the rotary atomizing head through the feed tube. 
   With regard to the rotary atomizing head type coating machine constructed as the above, a cartridge of a color used for coating is selected from the cartridges of respective colors, and the selected cartridge is attached to the cartridge attachment part of the housing. 
   Then, by optionally supplying air to the pressure air storage chamber of the cartridge, paint in the paint storage chamber of the cartridge is discharged through the feed tube to the rotary atomizing head. Accordingly, the rotary atomizing head sprays this paint toward a target. 
   By exchanging the cartridge for a cartridge of another color, coating color can be changed without wasting paint and solvent. 
   On the other hand, when the cartridge is removed for switching the coating colors after finishing the coating, there is little residual paint in the paint storage chamber. Accordingly, it is necessary to refill the cartridge with paint. 
   A paint filler for filling the cartridge with paint comprises quick joints extended from paint circulation pipings of respective colors. At the time of filling the paint storage chamber of the cartridge with paint by the paint filler, the cartridge is detached from the housing and returned to a disposition rack. Next, a paint feed opening provided in the cartridge separately from the feed tube is connected to the quick joint so that the cartridge is filled with paint through the quick joint. 
   However, with regard to the cartridge of the art described in the Japanese Patent Laid Open Gazette Hei. 11-262699, the bomb part, in which paint is stored, and the feed tube part, for guiding the paint in the bomb toward the rotary atomizing head, are formed integrally, and a piston for pressing out the paint from the bomb is disposed in the cartridge, whereby the whole cartridge becomes large and weight thereof increases. 
   When the empty cartridge is filled with paint, it is necessary to convey not only the paint storage part but the whole cartridge, whereby the handling of the cartridge is complicated and a conveying equipment becomes large. 
   Furthermore, the cartridges must be provided so as to correspond to the required number of cartridges of each color, and coating lines must be operated so as to correspond to the number of required colors. Accordingly, the number of the cartridges becomes large, and the cartridges, constructed integrally with the paint storage parts and mechanisms for pressing out paint, increase costs. 
   Moreover, even if any disorder occurs in only the bomb part or only the piston part, the whole cartridge becomes no longer usable. 
   BRIEF SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a cartridge which is simple, light and economic. 
   To achieve the object, a cartridge-type coating machine comprises: a coating device disposed at a front part of a housing; and a cartridge for storing paint therein and detachably attached to a rear part of the housing. The paint in the cartridge is supplied to an atomizing head of the coating device by pressurizing the cartridge by liquid fluid. A storage chamber, in which the liquid fluid is stored, is formed by the housing and the cartridge. 
   Accordingly, the cartridge does not require another mechanism for pressing paint, whereby the cartridge can be reduced in weight, size and cost. A conveying equipment for the cartridge can also be miniaturized. 
   The cartridge comprises a paint unit, in which paint is stored, and a casing, to which the paint unit is attached. The storage chamber is a space surrounded by an inner wall of a cartridge storage chamber to which the cartridge is attached, a side wall of the paint unit of the cartridge, and frames of the casing disposed at both sides of the paint unit. The paint is supplied to the atomizing head by pressurizing the side wall of the paint unit by the liquid fluid. 
   Accordingly, the side wall of the paint unit is pressurized wholly equally by pressure solvent in the storage chamber, whereby paint is effectively and accurately pressed out. 
   The cartridge comprises a paint unit, in which paint is stored, and a casing, to which the paint unit is attached. The paint unit comprises a paint storage chamber formed by a paint storage tube serving as a side wall of the paint storage chamber, and plate members blocking both ends of the paint storage tube. The paint storage tube is formed of a flexible membrane body easily deformable by external pressure. 
   Accordingly, the paint unit is fixed at its front part to the casing and guided at its rear part, and then pressurized from the side, whereby the tube is difficult to be warped during its volume reduction. Accordingly, excessive bending of a surface of the tube following the reduction of the stored paint is restrained so that paint is supplied smoothly. 
   By reducing the bending degree of the paint storage tube, load applied on the paint storage tube can be reduced so as to improve durability of the paint storage tube. 
   Accordingly, the paint storage tube can be easily refilled with paint so as to improve its recyclability, thereby reducing the recycling cost of the paint unit. 
   The cartridge comprises a paint unit, in which paint is stored, and a casing, to which the paint unit is attached. The paint unit is detachably attached to the casing. 
   Accordingly, the only thing required for filling the empty paint unit with paint is to convey the light and handy empty paint unit to a place for filling of paint, whereby a conveying equipment can be miniaturized. 
   The liquid fluid is a non-polar solvent. 
   Accordingly, paint can be controlled easily, and high voltage at the time of electrostatic coating can be treated so as to reduce the possibility of a short-circuit. Accordingly, electrification of paint particles is not inhibited and the coating can be performed stably. The pressure solvent can also be used as a pressing means at the time of washing. 
   The cartridge is detachably attached to a cartridge storage chamber formed in a housing of the coating machine; and a space is formed between an inner wall of the cartridge storage chamber and the cartridge when the cartridge is attached to the housing of the coating machine. 
   Accordingly, the cartridge is pressurized wholly equally by pressure solvent charged into the space between the inner wall of the cartridge storage chamber and the cartridge, thereby ensuring effective and accurate pressing-out of paint. Therefore, the cartridge does not require another mechanism for pressing paint, whereby the cartridge can be reduced in weight, size and cost. A conveying equipment for the cartridge can also be miniaturized. 
   The cartridge comprises a paint unit, in which paint is stored, and a casing, to which the paint unit is attached. The paint unit comprises a paint storage chamber formed by a paint storage tube serving as a side wall of the paint storage chamber, and plate members blocking both ends of the paint storage tube. The paint storage tube is formed of a flexible membrane body easily deformable by external pressure. 
   Accordingly, the paint unit is fixed at its front part to the casing and guided at its rear part, and then pressurized from the side, whereby the tube is difficult to be warped during its volume reduction. Accordingly, excessive bending of a surface of the tube following the reduction of the stored paint is restrained so that paint is supplied smoothly. 
   By reducing the bending degree of the paint storage tube, load applied on the paint storage tube can be reduced so as to improve durability of the paint storage tube. 
   Accordingly, the paint storage tube can be easily refilled with paint so as to improve its recyclability, thereby reducing the recycling cost of the paint unit. 
   The cartridge comprises a paint unit, in which paint is stored, and the casing, to which the paint unit is attached. The paint unit is detachably attached to the casing. 
   Accordingly, the only thing required for filling the empty paint unit with paint is to convey the light and handy empty paint unit to a place for filling of paint, whereby a conveying equipment can be miniaturized. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES 
       FIG. 1  is a view of a coating robot  1  provided with a cartridge-type coating machine according to the present invention. 
       FIG. 2  is a sectional side view of the coating machine. 
       FIG. 3  is a diagram of a paint supply circuit in a state that a cartridge is not connected to a paint lead-in part. 
       FIG. 4  is a diagram of the paint supply circuit in a state that the cartridge is connected to the paint lead-in part. 
       FIG. 5  is a side view of entire construction of the cartridge. 
       FIG. 6  is a side view partially in section of a paint unit. 
       FIG. 7  is a side view partially in section of a casing. 
       FIGS. 8(   a ),  8 ( b ) and  8 ( c ) illustrate a process of attaching the paint unit to the casing. 
       FIG. 9  is a sectional side view of the held paint unit. 
       FIG. 10(   a ) illustrates the coating machine to which the cartridge is being attached,  FIG. 10(   b ) illustrates the coating machine spraying paint, and  FIG. 10(   c ) illustrates the coating machine from which the cartridge is being detached. 
       FIG. 11  is a sectional side view of a cartridge storage chamber storing the cartridge therein. 
       FIG. 12  is a schematic view of the cartridge pressurized by fluid pressure. 
       FIG. 13  is a side view of the paint unit during a contraction process. 
       FIG. 14  is a perspective view of the paint unit emptied of paint therein. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An embodiment of the present invention will be explained with reference to the accompanying drawings. 
   Coating Robot 
   Firstly, explanation will be given on a schematic construction of a coating robot  1  provided with a cartridge-type coating machine according to the present invention. 
     FIG. 1  illustrates a coating robot  1  provided with a cartridge-type coating machine according to the present invention. 
   The coating robot  1  comprises a pedestal  102 , a vertical arm  103  rotatably and swingably provided on the pedestal  102 , an arm  104  swingably provided on a tip of the vertical arm  103 , and an articulated part  105  provided at a tip of the arm  104 . A cartridge-type rotary atomizing coating machine  11  is constructed at a tip of the articulated part  105 . 
   The coating machine  11  is provided with an exchangeable cartridge  21  storing paint therein. An exchanger (not shown) automatically exchanges the cartridge  21  for another cartridge  21  conveyed from a storage place to the coating robot  1  by a conveyer (not shown). 
   To supply the replacing cartridge  21  to the coating robot  1 , for example, the cartridge  21  may be inserted into a pneumatic tube, which connects the storage place of cartridges  21  to the coating robot  1 , so as to be conveyed by air pressure. 
   Coating Machine 
   Next, explanation will be given on a schematic construction of the coating machine.  FIG. 2  is a sectional side view of the coating machine. 
   In the following explanation, one side of the coating machine  11  at which a rotary atomizing head  14  is disposed (the left side in  FIG. 2 ) is referred to as the front side thereof, and another side of the coating machine  11  at which the cartridge  21  is disposed (the right side in  FIG. 2 ) is referred to as the rear side thereof. 
   The cartridge-type coating machine  11  shown in  FIG. 2  comprises a housing  12 , the rotary atomizing head  14 , an air motor  3  driving the rotary atomizing head  14 , the paint-storing cartridge  21  attached to the housing  12 , a paint supply passage  20  for supplying paint from the cartridge  21  to the rotary atomizing head  14 , and a paint valve  13  disposed in the middle of the paint supply passage  20 . 
   A cartridge storage chamber  18  is formed at a rear part of the housing  12 , and the cartridge  21  is detachably attached into the cartridge storage chamber  18 . At a front part of the housing  12 , the rotary atomizing head  14 , the air motor  3  and the paint valve  13  are disposed so as to constitute a coating device for spraying paint supplied from the cartridge  21 . 
   To supply paint from the cartridge  21  to the rotary atomizing head  14 , pressure solvent is charged into a pressure solvent storage chamber  18   b  of the cartridge storage chamber  18  through a solvent passage  16  formed in the housing  12 , so that an outer surface of the cartridge  21  is pressurized by the charged pressure solvent. The inner paint storage space of the pressurized cartridge  21  is reduced so that paint is pressed out from the cartridge  21 , whereby the pressed paint is supplied to the rotary atomizing head  14  through the paint supply passage  20 . The supplied paint is sprayed from the rotary atomizing head  14  driven by the air motor  3 . 
   The paint valve  13  is controlled so as to select whether or not paint is supplied to the rotary atomizing head  14 , thereby selecting whether or not the paint is sprayed. 
   The pressure solvent storage chamber  18   b  is a space formed between a side wall of the cartridge storage chamber  18  and the cartridge  21 . 
   With regard to the coating machine  11 , non-polar solvent with high electrical resistance is used as the pressure solvent charged into the cartridge storage chamber  18 . By using the non-polar solvent, high voltage, which electrifies paint in the cartridge storage chamber  18  through the air motor  3  at the time of electrostatic coating, is prevented from being grounded through the pressure solvent. Accordingly, electrification of sprayed particles of paint is not inhibited and the coating can be performed stably. 
   Simple solvent, such as hexane, carbon tetrachloride, benzene, cyclohexane, and toluene, and mixture of the simple solvents are available as the non-polar solvent suitable for use conditions and used paints. 
   Next, explanation will be given on each of parts of the coating machine  11 . 
   Housing 
   The housing  12  is formed of engineering plastic, such as PTFE, PEEK, PEI, POM, PI, PET or the like. 
   A high voltage cable  3   b  connected to a high voltage generator (not shown) is connected to the air motor  3  disposed at the front part of the housing  12  so that high voltage of about 30-100 kV is applied on the air motor  3  and the rotary atomizing head  14 . 
   The cartridge storage chamber  18  formed at the rear part of the housing  12  is formed to be a cylinder whose rear end is opened, and the cartridge  21  is attached/detached through this opening. A paint lead-in part  12   c  is formed at a bottom (front end) of the cartridge storage chamber  18 , and a tip of a nozzle  45  of the cartridge  21  is inserted into the paint lead-in part  12   c.    
   Rotary Atomizing Head 
   The rotary atomizing head  14  is screwed and connected to a tip side (front side) of a rotation shaft of the air motor  3 . The rotary atomizing head  14  is rotatively driven at high speed of about 10000-100000 rpm by the air motor  3 . When the rotary atomizing head  14  is rotated, paint supplied to the rotary atomizing head  14  is electrified with high voltage through the rotary atomizing head  14  and atomized centrifugally, whereby electrified paint particles are generated and sprayed. By electrostatic induction, the electrified paint particles fly along an electrostatic field formed between the rotary atomizing head  14  and a grounded target, and adheres to the target. 
   Numeral  2  designates a shaping air ring. The shaping air ring  2  is attached in front of the air motor  3  so as to fix the air motor  3 . At the outer peripheral side of the shaping air ring  2 , a number of shaping air spraying holes are bored circularly so that shaping air is sprayed toward a discharge edge of the rotary atomizing head  14 , thereby forming a pattern of the electrified paint particles discharged from the rotary atomizing head  14 . 
   Paint Valve 
   The paint valve  13  comprises a piston part  13   a , a valve body  13   b , a spring  13   c  and a valve seat part  15   b . The piston part  13   a  is longitudinally slidably inserted into a paint valve containing part  12   b  formed in the housing  12 . A basal end side of the valve body  13   b  of the paint valve  13  is attached to the piston part  13   a . The other side thereof is extended into a paint supply path  15   a  of a feed tube  15 , and has a tip part to engage with/disengage from the valve seat part  15   b  provided at a middle of the paint supply path  15   a . The spring  13   c  biases the valve body  13   b  through the piston part  13   a  to make it engage with the valve seat part  15   b.    
   The piston part  13   a  divides the paint valve containing part  12   b  into a spring chamber  112   b  containing the spring  13   c  and a pressurized chamber  112   a  to which pilot air enters, whereby the paint valve  13  is constructed as an air pilot control valve. 
   When pilot air is not supplied to the pressurized chamber  112   a  of the paint valve containing part  12   b , the valve body  13   b  of the paint valve  13  engages with the valve seat part  15   b  by biasing force of the spring  13   c  so as to block the paint supply path  15   a . In the state that the paint supply path  15   a  is blocked by the valve body  13   b , the supply of paint to the rotary atomizing head  14  is stopped. 
   On the other hand, when pilot air is supplied to the pressurized chamber  112   a  of the paint valve containing part  12   b , the valve body  13   b  of the paint valve  13  disengages from the valve seat part  15   b  against the spring  13   c , whereby paint in the cartridge  21  is supplied to the rotary atomizing head  14 . 
   Paint Supply Passage 
   The paint supply passage  20  of the coating machine  11  is provided for supplying paint stored in the cartridge  21  to the rotary atomizing head  14 . The paint supply passage  20  comprises: a paint supply path  120  formed in the housing  12 ; and the pa int supply path  15   a  in the feed tube  15 , which is fixedly connected to the housing  12  and extended at its tip side to the rotary atomizing head  14 . 
   The paint valve  13  is provided at the middle of the paint supply passage  20  and opens/closes the paint supply path  15   a  according to a desirable control command so as to select either supply or not of paint to the rotary atomizing head  14 . 
   The feed tube  15  is formed of a member separated from the housing  12 , and the valve seat part  15   b  for the paint valve  13  is formed in the feed tube  15 . 
   The paint supply path  120  is opened at a bottom of the cartridge storage chamber  18 , and the cylindrical paint lead-in part  12   c  is projected from this opening into the cartridge storage chamber  18 . An air passage  17  is opened at the bottom of the cartridge storage chamber  18 , and the pressure solvent passage  16  is opened at a side of the cartridge storage chamber  18 . 
   When the cartridge  21  is stored in the cartridge storage chamber  18 , an air storage chamber  18   c  and the pressure solvent storage chamber  18   b  are formed in the cartridge storage chamber  18 , and a tip of the nozzle  45  of the cartridge  21  is inserted into the cylindrical paint lead-in part  12   c  and kept liquid-tight therein. The air passage  17  is communicated to the air storage chamber  18   c , and the pressure solvent passage  16  is communicated to the pressure solvent storage chamber  18   b.    
   The nozzle  45  of the cartridge  21  is a circular cylinder for discharging paint from the cartridge  21 . An outside diameter of the nozzle  45  is slightly smaller than an inside diameter of the cylindrical paint lead-in part  12   c.    
   Accordingly, when the cartridge  21  is stored in the cartridge storage chamber  18 , the cylindrical paint lead-in part  12   c  can be certainly engaged with the nozzle  45  so that paint in the cartridge  21  can flow into the paint supply passage  20 . Therefore, by making pressure solvent flow from the pressure solvent passage  16  to the pressure solvent storage chamber  18   b  with desired pressure, the paint in the cartridge  21  is pressed and supplied to the rotary atomizing head  14  through the paint supply passage  20 . 
   A cleaning fluid passage  20   a  is connected to the paint supply passage  20  near the paint lead-in part  12   c . A passage  20   c  for supplying cleaning air and a passage  20   d  for supplying cleaning solvent are connected to the cleaning fluid passage  20   a  through a control valve  20   b.    
   Accordingly, cleaning fluid from a cleaning solvent source and a cleaning air source flows through the cleaning fluid passage  20   a , whereby paint remaining in the paint supply passage  20  and the rotary atomizing head  14  can be cleaned out. 
   Paint Supply Circuit 
   Next, explanation will be given on a paint supply circuit in the coating machine  11 . 
     FIG. 3  shows the paint supply circuit in the state that the nozzle  45  of the cartridge  21  is not connected to the paint lead-in part  12   c .  FIG. 4  shows the paint supply circuit in the state that the nozzle  45  is connected to the paint lead-in part  12   c.    
   A check valve is provided in the nozzle  45  of the cartridge  21 . The check valve prevents paint in the cartridge  21  from flowing through the nozzle  45  when the nozzle  45  is not engaged with the paint lead-in part  12   c  (that is, in the state shown in  FIG. 3 ), and permits paint in the cartridge  21  to flow to the paint supply passage  20  when the nozzle  45  is engaged with the paint lead-in part  12   c  (that is, in the state shown in  FIG. 4 ). Accordingly, when the cartridge  21  is stored in the cartridge storage chamber  18 , the paint lead-in part  12   c  is engaged with the nozzle  45 , whereby paint in the cartridge  21  can be supplied to the rotary atomizing head  14  through the paint valve  13 . 
   The paint valve  13  blocks/connects the paint supply passage  20  so as to control the supply or not of paint to the rotary atomizing head  14  from the cartridge  21 . 
   For supplying paint in the cartridge  21  to the rotary atomizing head  14 , pressure solvent is charged from a pressure solvent source into the pressure solvent storage chamber  18   b  through the pressure solvent passage  16  so as to push out the paint from the cartridge  21  to the paint supply passage  20 , thereby supplying the paint to the rotary atomizing head  14 . 
   At this time, a discharge amount of paint supplied to the rotary atomizing head  14  is controlled by adjusting the amount of the pressure solvent charged into the pressure solvent storage chamber  18   b  to a desirable value. 
   Next, explanation will be given on cleaning of the paint supply circuit. 
   As the above mentioned, the cleaning fluid passage  20   a  is connected to the paint supply passage  20  near the paint lead-in part  12   c , and the passage  20   c  for supplying cleaning air and the passage  20   d  for supplying cleaning solvent are connected to the cleaning fluid passage  20   a  through the control valve  20   b . For example, if the coating machine  11  requires change of coating color from a color A to a color B, the paint valve  13  is opened. 
   Next, by operating the control valve  20   b , one of the cleaning air passage  20   c  and the cleaning solvent passage  20   d  is alternately selected so as to supply its cleaning fluid (either the cleaning air or the cleaning solvent), whereby the paint of the color A adhering to the paint supply passage  20  and the rotary atomizing head  14  is removed. In this way, the cleaning of the paint supply passage  20  and the rotary atomizing head  14  is completed. 
   Subsequently, the cartridge  21  of the color A is detached from the cartridge storage chamber  18  and the cartridge  21  of the color B is attached thereto, whereby the changing of coating color is completed. 
   Incidentally, at the time of the above-mentioned cleaning, the check valve provided in the nozzle  45  of the cartridge  21  of the color A prevents the cleaning fluid from flowing into the cartridge  21  of the color A. 
   Cartridge 
   Next, explanation will be given on the construction of the cartridge  21 . 
     FIG. 5  is a side view of entire construction of the cartridge,  FIG. 6  is a side view partially in section of a paint unit,  FIG. 7  is a side view partially in section of a casing,  FIGS. 8(   a ),  8 ( b ) and  8 ( c ) illustrate a process of attaching the paint unit to the casing, and  FIG. 9  is a sectional side view of the held paint unit. 
   As shown in  FIG. 5 , the cartridge  21  generally comprises the paint unit  41  storing paint and the casing  31  to which the paint unit  41  is detachably attached. 
   The cartridge  21 , in the state of being stored in the cartridge storage chamber  18 , constitutes a part of a paint supply system for supplying paint in the cartridge to the rotary atomizing head  14 . 
   Furthermore, the cartridge  21  also serves as a lid closing the opening of the cartridge storage chamber  18 . A rear frame  37  of the cartridge  21  prevents pressure solvent supplied into the pressure solvent storage chamber  18   b  of the cartridge storage chamber  18  from leaking out of the cartridge storage chamber  18 . Accordingly, it is not necessary to provide another separate lid in the housing  12  of the coating machine  11  for closing the opening of the cartridge storage chamber  18 , thereby simplifying the coating machine  11 . 
   Explanation will be given on the construction of the paint unit  41 . 
   The paint unit  41  functions as a paint storage tank for storing paint therein and, as shown in  FIG. 6 , comprises a front plate  42 , a rear plate  43 , a tube  44  and the nozzle  45 . The tube  44  is a flexible member which can be easily deformed by receiving an external force. The front plate  42  and the rear plate  43  are formed of members with high rigidity such as to stably attach the paint unit  41  to the casing  31 . 
   The front plate  42  and the rear plate  43 , serving as lids of the tube  44 , are liquid-tightly fitted to both ends of the tube  44 , whereby the front plate  42 , the rear plate  43  and the tube  44  constitute a paint storage chamber  41   a . The nozzle  45  is disposed at a center of the front plate  42  so as to permit supplying of paint  41   b  from the paint storage chamber  41   a  toward the coating machine  11 . 
   As shown in  FIGS. 3 and 4 , a check valve is disposed in the nozzle  45 . The check valve permits the paint  41   b  to flow toward the paint supply passage  20  of the coating machine  11  when the cartridge  21  is stored in the cartridge storage chamber  18 . 
   The tube  44  is a member constituting a side wall of the paint unit  41 , and also is a membrane body forming the pressure solvent storage chamber  18   b  together with a front frame  38  and the rear frame  37  of the casing  31 , when the cartridge  21  is stored in the cartridge storage chamber  18 . 
   When the pressure solvent is supplied into the pressure solvent storage chamber  18   b , the membrane body forming the tube  44  is easily deformable, and also solvent-resistant so as to resist against dissolution and degeneration by an organic solvent and penetration by solvent vapor. For example, in addition to a synthetic resin such as polyethylene and polypropylene, the tube  44  can be formed by metal foil, metal membrane body, or composite made by laminating resin and metal. 
   A member having bending modulus lower than 700 (kg/square centimeter) can be used as the flexible membrane body constituting the tube  44 . 
   For forming the tube  44 , any flexible member may serve as the tube  44  if it is easily deformed by the pressure of the pressure solvent. In addition to a member having elasticity (extendable and contractible) and a member having tensibility (extendable and not contractible), a member having little elasticity and tensibility, such as a laminate material made by laminating metal foil and resin foil, can be used. 
   With regard to the paint unit  41  constructed as the above, by pressurizing the tube  44  serving as the side wall thereof from the outside, the volume of the paint storage chamber  41   a  is reduced so that paint stored therein is pushed out through the nozzle  45 . 
   Next, explanation will be given on the construction of the casing  31 . 
   As shown in  FIG. 7 , the casing  31  comprises the front frame  38  and the rear frame  37 , which serve as opposite side frames positioned at both sides of the paint unit  41  when the paint unit  41  is attached to the casing  31 , and a stick-like connection frame  34  connecting the front frame  38  and the rear frame  37 . 
   The front frame  38  and the rear frame  37  are disk-like shaped along an inner wall of the cartridge storage chamber  18 . The front frame  38  and the rear frame  37  connected to each other through the connection frame  34  keeps a constant interval therebetween. 
   The casing  31  is substantially all-round opened (between the front frame  38  and the rear frame  37 ) so as to save the weight and secure an enough space into which the paint unit  41  is attached. 
   Diameters of the disk-like front frame  38  and rear frame  37  are slightly smaller than an inner diameter of the cartridge storage chamber  18 . Circular grooves  38   c  and  37   c  (shown in  FIG. 9 ) are engraved on outer peripheral surfaces of the frames  38  and  37 , and elastic circular seals  38   b  and  37   b  are fitted into the grooves. The seals  38   b  and  37   b  keep the liquid-tightness of the pressure solvent storage chamber  18   b , formed when the cartridge  21  is stored in the cartridge storage chamber  18 . 
   A circular hole is formed at a center of the front frame  38 . This hole permits the nozzle  45  of the paint unit  41  to be inserted into a nozzle holding part  39  when the paint unit  41  is attached to the casing  31 . 
   A cylindrical nozzle guard  32  is provided at a front side of the front frame  38 . The nozzle guard  32  prevents the nozzle  45  from being damaged by contacting with another member at the time of moving or conveying the cartridge  21 . 
   The casing  31 , constructed as the above, protects the tube  44  with a relatively low mechanical strength, and functions as a guide member for inserting and storing the cartridge  21  into the cartridge storage chamber  18 . The casing  31  also functions as a partition member between the pressure solvent storage chamber  18   b  and the air storage chamber  18   c . Namely, the pressure solvent storage chamber  18   b  is surrounded by the side wall of the cartridge storage chamber  18 , the front frame  38  and the rear frame  37  of the casing  31 , and the tube  44  of the paint unit  41 . The air storage chamber  18   c  is surrounded by the inner wall of the cartridge storage chamber  18  and the front frame  38  of the casing  31 . 
   Fixing hooks  33  are formed on the front frame  38 , and guide projections  33   b  are formed on the rear frame  37 . 
   By hooking the front plate  42  of the paint unit  41  onto the fixing hooks  33  of the front frame  38 , the paint unit  41  attached to the casing  31  is held. The rear plate  43  of the paint unit  41  attached to the casing  31  is positioned by the guide projections  33   b  of the rear frame  37 . Accordingly, the paint unit  41  can be fixed between the front frame  38  and the rear frame  37 . 
   Specifically, the attachment of the paint unit  41  to the casing  31  is performed as shown in  FIG. 8 . 
   Firstly, as shown in  FIG. 8(   a ), the paint unit  41 , in which paint of a color for coating is stored, and the casing  31  are prepared. Next, as shown in  FIG. 8(   b ), the nozzle  45  of the paint unit  41  is inserted into the front part of the casing  31 , and the front part of the paint unit  41  is hooked onto the fixing hooks  33  of the front frame  38  in the casing  31 , so that the paint unit  41  is held. 
   Subsequently, as shown in  FIG. 8(   c ), the rear part of the paint unit  41  is guided by the guide projections  33   b  of the rear frame  37 . 
   The attached paint unit  41  is substantially held and fixed by the fixing hooks  33  of the front frame  38 . The guide projections  33   b  of the rear frame  37  are provided not for limiting the longitudinal position of the rear plate  43 , but for guiding the rear plate  43  of the paint unit  41  so as to prevent it from slipping along the surface of the rear frame  37 . 
   The casing  31 , to which the paint unit  41  is attached, is substantially all-round opened between the front frame  38  and the rear frame  37 , whereby the paint unit  41  can be attached to the casing  31  easily, and the state of the attached paint unit  41  can be checked easily. 
   The paint unit  41 , substantially serving as a paint storage part in the cartridge  21 , is formed separately from the casing  31  and detachably attached to the casing  31 . Accordingly, the only thing required for filling the empty paint unit  41  with paint is to convey the light and handy empty paint unit  41  to a place for filling of paint, whereby a conveying equipment can be miniaturized. 
   With regard to the coating machine  11  constructed as the above, the pressure solvent storage chamber  18   b  for storing pressure solvent, which is liquid fluid for pressing paint, is constructed by the housing  12  and the cartridge  21 . Accordingly, the cartridge  21  does not require another mechanism for pressing paint, whereby the cartridge  21  can be reduced in weight, size, and cost. The conveying equipment for the cartridge  21  can also be miniaturized. 
   Especially, the pressure solvent storage chamber  18   b  is formed by the front frame  38  and the rear frame  37  of the casing  31 , the tube  44  serving as the side wall of the paint unit  41 , and the inner wall of the cartridge storage chamber  18  covering the tube  44 , so that the tube  44  is pressurized wholly equally by pressure solvent in the pressure solvent storage chamber  18   b , thereby ensuring effective and accurate pressing-out of paint. 
   Next, explanation will be given on attachment/detachment between the cartridge storage chamber  18  and the cartridge  21 . 
     FIGS. 10(   a ),  10 ( b ) and  10 ( c ) illustrate attachment/detachment between the cartridge  21  and the coating machine  11  and the state of spraying paint from the coating machine  11 .  FIG. 10(   a ) shows a state of the coating machine  11  fittingly provided with the cartridge  21 , in which paint is stored, wherein the cartridge  21  is fittingly inserted into the opening of the cartridge storage chamber  18  formed at a rear part of the coating machine  11 .  FIG. 10(   b ) shows a state of the coating machine  11  during coating, wherein the paint in the cartridge  21  is supplied to the rotary atomizing head  14  and sprayed.  FIG. 10(   c ) shows a state of the coating machine  11  after the coating, from which the cartridge  21  emptied of the paint is detached. 
   An exchanger (not shown) and the like, which may be provided independently of the coating machine  11 , performs the attachment/detachment of the cartridge  21  to and from the coating machine  11 . 
   Accordingly, the attachment/detachment of the cartridge  21  is performed for the above-mentioned change of coating colors. 
   As the above mentioned, when the cartridge  21  is inserted into the cartridge storage chamber  18  and stored therein, the tip of the nozzle  45  is directed to the bottom of the cartridge storage chamber  18 . With regard to the air storage chamber  18   c  formed by the inner wall of the cartridge storage chamber  18  and the front frame  38  of the casing  31 , the deeper the cartridge  21  is inserted into the cartridge storage chamber  18 , the smaller the volume of the air storage chamber  18   c  becomes so that pressure therein tends to become high. 
   One of ends of the air passage  17  formed in the housing  12  of the coating machine  11  is opened toward the side of the cartridge storage chamber  18 , and the other end thereof is opened toward the outside of the housing  12 , whereby the air storage chamber  18   c  always is ventilated outward. 
   Accordingly, even if the volume of the air storage chamber  18   c  is reduced gradually and the pressure therein tends to become high, air in the air storage chamber  18   c  is discharged outward through the air passage  17  so that the pressure does not rise, whereby the cartridge  21  can be easily inserted into the fixed position in the cartridge storage chamber  18 . 
   When the cartridge  21  is detached from the cartridge storage chamber  18 , even if the volume of the air storage chamber  18   c  is increased gradually and the pressure therein tends to become negative, air is supplied from the outside of the housing  12  through the air passage  17 , whereby the cartridge  21  can be detached easily. 
   Next, explanation will be given on a contraction process of the paint unit  41 . 
     FIG. 12  is a schematic view of the cartridge pressurized by fluid pressure,  FIG. 13  is a side view of the paint unit during a contraction process, and  FIG. 14  is a perspective view of the paint unit emptied of paint therein. 
   As shown in  FIG. 12 , paint is supplied from the paint unit  41  to the rotary atomizing head  14  by charging pressure solvent into the pressure solvent storage chamber  18   b  through the pressure solvent passage  16  by a pump or the like so as to press out paint stored in the paint unit  41 . 
   As shown in  FIG. 13 , as the paint is pushed out from the paint unit  41 , a bending degree of the tube  44  becomes large. Accordingly, if the tube  44  is formed of a member having no elasticity or no tensibility, the rear plate  43  of the paint unit  41  slightly moves forward according to the increase of the bending degree of the tube  44 . In this regard, the rear plate  43  of the paint unit  41  is not retained by the guide projections  33   b , but is movable longitudinally. Accordingly, the tube  44  may be formed of a member having no elasticity or no tensibility. 
   Since the tube  44  is formed of a flexible member, paint stored therein can be pushed out substantially wholly, as shown in  FIG. 14 . 
   The tube  44  is fixed at its front part by the fixing hooks  33  and guided at its rear part by the guide projections  33   b , and then pressurized from the side, whereby the tube  44  is difficult to be warped. Accordingly, excessive bending of a surface of the tube  44  following the reduction of the stored paint is restrained so that paint is supplied smoothly. 
   The bending degree of the tube  44  pressing out paint by the pressure of the pressure solvent may be reduced so as to reduce load applied on the tube  44 , thereby improving durability of the tube  44 . Accordingly, the tube  44  can be easily refilled with paint so as to improve its recyclability, thereby reducing the recycling cost of the paint unit  41 . 
   When the cartridge  21 , having the paint unit  41  attached to the casing  31 , is detached from the coating machine  11 , the tube  44  is protected by the casing  31 , whereby the cartridge  21  can be easily handled. 
   Furthermore, the casing  31  has a number of openings so that the state of the tube  44  attached to the casing  31  can be recognized easily, whereby disorder of the tube  44 , such as breakage, can be detected easily.