Patent Publication Number: US-2003234299-A1

Title: Cartridge type coater

Description:
TECHNICAL FIELD  
       [0001] This invention relates to a cartridge type coating machine, employing a plural number of paint cartridges of different colors which are adapted to be interchangeably and replaceably set in position on the machine to permit color changes during a coating operation.  
       BACKGROUND ART  
       [0002] Generally, various types of coating machines have been and are resorted to for coating work pieces such as vehicle bodies or the like, including rotary atomizing head type coating machines, hydraulic atomization type coating machines and pneumatic atomization type coating machines. In this connection, there are strong demands for a coating machine which can reduce the amounts of paint and solvent to be discarded or consumed at the time of changing the paint color and which can cope with a large number of paint colors.  
       [0003] As a coating machine which can reduce the amounts of discarding paint and solvent consumption and which can cope with a large number of colors, there have been known cartridge type coating machines (e.g., as disclosed in Japanese Patent Laid-Open No. H11-262699 and Japanese Patent Laid-Open No. H8-229446). In the case of this cartridge type coating machine, arrangements are made to replaceably mount paint cartridges, which are filled with different colors, on a housing of the coating machine.  
       [0004] Further, in the case of the conventional cartridge type coating machine mentioned above, the machine includes a housing which is provided with a sprayer mount portion and a cartridge mount portion in its front and rear end portions, respectively, a rotary atomizing head type or hydraulic atomization type sprayer unit which is mounted on the sprayer mount portion of the housing to spray supplied paint toward a work piece, and paint cartridges which are filled with different paint colors and adapted to be replaceably mounted on the cartridge mount portion of the housing.  
       [0005] The paint cartridges are each constituted largely by a cylindrical container which is closed at the opposite ends and internally filled with paint, and a feed tube which is extended out axially from the container to spurt out paint in the cartridge container therethrough. Further, the cartridge mount portion of the housing is formed in the shape of a bottomed cavity which is open on the rear side. A paint cartridge is set on the cartridge mount portion by fitting engagement therewith of the cartridge container.  
       [0006] As a paint cartridge is set on the cartridge mount portion on the housing, a vacuum space is defined in the cartridge mount portion by an O-ring which is provided around the outer periphery of the cartridge container and brought into sliding contact with inner peripheral surfaces of the cartridge mount portion. Air in the vacuum space is sucked out through a suction passage to hold the paint cartridge fixedly on the cartridge mount portion by suction grip.  
       [0007] With a cartridge type coating machine which is arranged in the manner as described above, paint cartridges of different colors are selectively mounted on the cartridge mount portion during a coating operation. The paint in the cartridge container is spurted out toward the sprayer unit through the feed tube and then sprayed toward a work piece by the sprayer unit.  
       [0008] The paint cartridge on the coating machine is simply replaced by a cartridge of a next color at the time of changing the paint color, that is to say, the paint color can be changed without entailing wasteful paint discarding or solvent consumption.  
       [0009] Further, in the case of the above-described conventional cartridge type coating machine, as mentioned above, an O-ring which is provided around the outer periphery of the cartridge container is brought into sliding contact with inner peripheral surfaces of the cartridge mount portion to define a vacuum space therebetween. The paint cartridge is fixed on the cartridge mount portion by suction force which is produced by sucking air out of the vacuum space. However, since the  0 ring which is attached to the paint cartridge is simply held in sliding contact with the inner periphery of the cartridge mount portion, it is difficult to seal up the vacuum space completely by the O-ring. Therefore, it is inevitable that atmospheric air incessantly creeps into the vacuum space. This means that, in order to maintain the suction grip on the paint cartridge, a vacuum generator has to be constantly kept in operation to suck out air continuously from the vacuum space.  
       [0010] In case the vacuuming operation is stopped due to a damage or a trouble occurring to the vacuum generator or to suction air piping or hose, it becomes difficult to maintain the vacuum space under negative pressure, and the paint cartridge is likely to fall off the housing to compel stoppage of the coating line which would result in a detrimental drop of productivity.  
       [0011] Further, in the course of a coating operation, there may arise a need for stopping the coating line (or for putting the coating line at rest) for some reasons. On such an occasion, however, irrespective of the stoppage of the coating line, it is necessary to keep the vacuum generator in operation as long as the paint cartridge is mounted on the housing of the coating machine. This naturally invites increases in running cost.  
       [0012] Furthermore, as the container of a paint cartridge is mounted on or dismantled from the cartridge mount portion of the housing, the O-ring is brought into frictional contact with inner peripheral surfaces of the cartridge mount portion. Therefore, the O-ring which is repeatedly twisted by frictional contact is susceptible to damages and generally requires replacements at a higher frequency.  
       [0013] Besides, when the paint cartridge is mounted on or dismantled from the housing of the coating machine, the O-ring is twisted as mentioned above and as a result deformed and the container of the paint cartridge is deviated from the center axis of the cartridge mount portion. Thereby, the fore end of the feed tube which is extended forward from the container is also deviated from the center axis of the coating machine. As a consequence, part of paint which is supplied to the sprayer unit through the feed tube tend to overflow to the outside to lower the operational reliability of the coating machine.  
       DISCLOSURE OF THE INVENTION  
       [0014] In view of the above-mentioned problems with the prior art, it is an object of the present invention to provide a cartridge type coating machine which can hold a paint cartridge in a cartridge mount portion fixedly in a secure state without applying an external force, for example, without applying a suction force by the use of a vacuum generator or the like, permitting to improve productivity and reliability of the machine while cutting its running cost.  
       [0015] In accordance with the present invention, there is provided a cartridge type coating machine, which includes a housing with a sprayer unit mount portion and a cartridge mount portion respectively on front and rear sides thereof, a sprayer unit mounted on the sprayer unit mount portion of the housing to spray supplied paint toward a work piece, and a paint cartridge adapted to be replaceably set in the cartridge mount portion of the housing and filled with paint for supply to the sprayer unit.  
       [0016] In order to achieve the above-stated objective, the cartridge type coating machine according to the present invention is characterized by the provision of a magnetic holding mechanism provided between the cartridge mount portion of the housing and the paint cartridge to releasably and fixedly hold the paint cartridge in the cartridge mount portion of the housing by magnetic force.  
       [0017] With the arrangements just described, as a paint cartridge is mounted on the cartridge mount portion of the housing, it can be securely fixed to the cartridge mount portion by magnetic force of a permanent magnet or electromagnet without applying an external force, for example, by the use of a vacuum generator or the like.  
       [0018] In a preferred form of the present invention, the magnetic holding mechanism is constituted by permanent magnets attached to one of the cartridge mount portion of the housing and the paint cartridge and magnetic members attached to the other one of the cartridge mount portion and the paint cartridge.  
       [0019] With the arrangements just described, as a paint cartridge is mounted on the cartridge mount portion of the housing, the magnetic member which is attached to the paint cartridge, for example, is attracted to the permanent magnet on the side of the cartridge mount portion and as a result the paint cartridge is securely and fixedly held in the latter by the magnetic holding mechanism.  
       [0020] According to the present invention, preferably, the magnetic holding mechanism is constituted by a first permanent magnet attached to one of the cartridge mount portion of the housing and the paint cartridge, and a second permanent magnet attached to the other one of the cartridge mount portion and the paint cartridge in such a way as to confront the first permanent magnet through opposite magnetic poles.  
       [0021] With the arrangements just described, as a paint cartridge is mounted on the cartridge mount portion of the housing, the second permanent magnet which is attached on the paint cartridge, for example, is attracted to the first permanent magnet which is attached on the side of the cartridge mount portion, and as a result the paint cartridge is securely and fixedly held in the latter by the magnetic holding mechanism.  
       [0022] According to a further preferred form of the present invention, the magnetic holding mechanism is constituted by a first magnet group consisting of a plural number of permanent magnets and attached to one of the cartridge mount portion of the housing and the paint cartridge, the permanent magnets of the first magnet group being arranged in a row and alternately reversed in magnetic pole position, and a second magnet group consisting of a plural number of permanent magnets and attached to the other one of the cartridge mount portion of the housing and the paint cartridge, the permanent magnets of the second magnet group being arranged into a row in confronting relation with the first magnet group and reversed in magnetic pole position relative to said first magnet group.  
       [0023] With the arrangements just described, as a paint cartridge is mounted on the cartridge mount portion of the housing, the first and second magnet groups are attracted toward each other, and as a result the paint cartridge is securely fixed in the cartridge mount portion. Further, when the first and second magnet groups come closer to each other, homopolar repulsions and heteropolar attractions take place between permanent magnets of the first and second magnet groups. Therefore, at the time of mounting the paint cartridge on the housing, positional deviations between the cartridge mount portion and the paint cartridge, if any, can be corrected by the repulsive and attracting actions of the permanent magnets.  
       [0024] According to the present invention, preferably an ejection air supply passage is provided in the housing for supplying ejection air between the cartridge mount portion and the paint cartridge at the time of dismantling the latter from the cartridge mount portion of the housing.  
       [0025] With the arrangements just described, at the time of dismantling the paint cartridge from the cartridge mount portion of the housing, ejection air is supplied to a space between the cartridge mount portion and the paint cartridge through the ejection air supply passage. Whereupon, the paint cartridge is pushed outward by ejection air and can be easily dismantled or removed from the cartridge mount portion of the housing against the magnetic force of the magnetic holding mechanism.  
       [0026] According to a further preferred form of the present invention, the cartridge mount portion of the housing is formed in the shape of a bottomed cylindrical cavity, and the paint cartridge is provided with a cylindrical container filled with paint and a feed tube extended axially forward from a front end of the container, and the coating machine further comprises a seal member provided either on a bottom surface of the cartridge mount portion or on a front surface of the container, the seal member being brought into abutting engagement with either the front surface of the paint cartridge or the bottom surface of the cartridge mount portion to form an ejection air space therebetween when the paint cartridge is set in the cartridge mount portion of the housing.  
       [0027] With the arrangements just described, as soon as a paint cartridge is set on the cartridge mount portion of the housing, an ejection air space is formed and defined between the cartridge mount portion and the paint cartridge by the seal member. Therefore, upon supplying air to the ejection air space, the air pressure can be efficiently acted on the container of the paint cartridge, permitting to dismantle the paint cartridge extremely in a facilitated manner. Besides, the seal member is simply abutted against a bottom surface of the cartridge mount portion or a front surface of the cartridge container, so that there is little possibility of the seal member being subjected to twisted deformation or sliding abrasion at the time of loading or unloading a paint cartridge to or from the coating machine.  
       [0028] Further, according to the present invention, preferably a projection and a recess of complementary shapes are provided on confronting surfaces of the above-mentioned permanent magnet and the opposing magnetic member for fitting engagement with each other. Similarly, according to the present invention, a projection and a recess of complementary shapes are preferably provided on confronting surfaces of the above-mentioned first and second permanent magnets for fitting engagement with each other.  
       [0029] With the arrangements just described, as opposing permanent magnets or a permanent magnet and an opposing magnetic member are attracted toward each other, the projection and recess on their confronting surfaces are brought into fitting engagement with each other, contributing to locate the paint cartridge into a predetermined position within the cartridge mount portion of the housing.  
       [0030] According to a further preferred form of the present invention, the magnetic holding mechanism is constituted by an electromagnet provided on one of the cartridge mount portion of the housing and the paint cartridge, and a magnetic member provided on the other one of the cartridge mount portion and the paint cartridge.  
       [0031] With the arrangements, at the time of mounting a paint cartridge on the cartridge mount portion of the housing, power is supplied to energize the electromagnet which is provided, for example, on the side of the cartridge mount portion. Upon energizing the electromagnet, the magnetic member on the side of the paint cartridge is attracted by the electromagnet, and as a result the paint cartridge is securely fixed in the cartridge mount portion of the machine housing.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0032] In the accompanying drawings:  
     [0033]FIG. 1 is a vertical sectional view of a cartridge type coating machine according to a first embodiment of the present invention, showing together a paint cartridge which is loaded on the coating machine;  
     [0034]FIG. 2 is a vertical sectional view on an enlarged scale of the paint cartridge which is loaded in a cartridge mount portion within a housing shown in FIG. 1;  
     [0035]FIG. 3 is a right-hand side view of the cartridge mount portion of the housing, showing the bottom side of the cartridge mount portion as taken in the direction of arrows III-III of FIG. 2, with the paint cartridge removed for the convenience of illustration;  
     [0036]FIG. 4 is a vertical sectional view of one paint cartridge unit;  
     [0037]FIG. 5 is a left-hand side view of the paint cartridge as taken in the direction of arrows V-V of FIG. 2 to show the front side of the cartridge;  
     [0038]FIG. 6 is an enlarged perspective view of a permanent magnet and a magnetic member shown in FIG. 2;  
     [0039]FIG. 7 is a right-hand side view similar to FIG. 3, showing the bottom side of a cartridge mount portion of a housing according to a second embodiment of the invention together with first magnet groups;  
     [0040]FIG. 8 is a left-hand side view similar to FIG. 5, showing the front side of a paint cartridge according to the second embodiment together with second magnet groups;  
     [0041]FIG. 9 is a vertical sectional view similar to FIG. 2, showing on an enlarged scale a cartridge mount portion of a housing according to a third embodiment of the present invention together with a paint cartridge;  
     [0042]FIG. 10 is a vertical sectional view similar to FIG. 2, showing on an enlarged scale a cartridge mount portion of a housing according to a fourth embodiment of the invention together with a paint cartridge;  
     [0043]FIG. 11 is a schematic perspective view on an enlarged scale of a permanent magnet and a magnetic member shown in FIG. 10;  
     [0044]FIG. 12 is a vertical sectional view similar to FIG. 2, showing on an enlarged scale a cartridge mount portion of a housing according to a fifth embodiment of the present invention together with a paint cartridge;  
     [0045]FIG. 13 is a schematic perspective view on an enlarged scale of a permanent magnet and a magnetic member in a first modification according to the present invention; and  
     [0046]FIG. 14 is a schematic perspective view on an enlarged scale of a permanent magnet and a magnetic member in a second modification according to the present invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
     [0047] Hereafter, the cartridge type coating machine according to the present invention is described more particularly with reference to the accompanying drawings, by way of its preferred embodiments which are each in the form of a rotary atomizing head type coating machine.  
     [0048] Referring first to FIGS. 1 through 6, there is shown a first embodiment of the present invention. In these figures, indicated at  1  is a cartridge type coating machine (hereinafter simply referred to as “coating machine 1” for brevity) which is provided on a coating robot or a reciprocator (not shown), for example. The coating machine  1  is largely constituted by a housing  2 , feed tube passage holes  5  and  10 , sprayer unit  6 , and paint cartridges  20 .  
     [0049] The housing  2  of the coating machine  1  is formed of an engineering plastics material, for example, such as PTFE, PEEK, PEI, POM, PI, PET and so forth. The housing  2  is constituted by a neck portion  2 A to be detachably attached, for example, on a wrist portion (not shown) of a coating robot, and a head portion  2 B which is formed integrally at the fore end of the neck portion  2 A.  
     [0050] In this instance, a sprayer unit mount portion  3  in the form of a cylindrical cavity is provided on the front side of the head portion  2 B of the housing  2 , and a cartridge mount portion  4  similarly in the form of a cylindrical cavity is provided on the rear side of the head portion  2 B. Further, the cartridge mount portion  4  is in the form of a bottomed blind hole which is open only on the rear side, and, as shown particularly in FIGS. 2 and 3, provided with a plural number of magnet fitting grooves  4 B, for example, four magnet fitting grooves  4 B on its bottom surface  4 A at angularly spaced positions in the circumferential direction for mounting permanent magnets  33 , which will be described hereinafter.  
     [0051] Indicated at  5  is a feed tube passage hole which is provided on the side of the housing  2  to extend between and in communication with the sprayer unit mount portion  3  and the cartridge mount portion  4 . This feed tube passage hole  5  on the side of the housing is composed of a front feed tube passage portion  5 A of a small diameter, and a rear conically converging portion  5 B which diameter is gradually reduced in a conical shape toward the front feed tube passage portion  5 A. In this instance, the feed tube passage portion  5 A is formed in coaxial relation with a feed tube passage hole  10  on the side of the sprayer unit, which will be described hereinafter. Further, the conically converging portion  5 B is held in abutting engagement with a conical projection  22  of the paint cartridge  20 , which will be described hereinafter, to hold the latter in position in radial and axial directions.  
     [0052] Denoted at  6  is a sprayer unit for spraying paint toward a work piece. The sprayer unit  6  is mounted in the sprayer unit mount portion  3  on the head portion  2 B of the housing. In this instance, as shown in FIG. 1, the sprayer unit  6  is largely constituted by an air motor  7  with a motor case  7 A, rotational shaft  7 B, air turbine  7 C and air bearing  7 D, a rotary atomizing head  8  which is put in rotation by the air motor  7  for atomizing paint into finely divided particles by centrifugal atomization and spraying same toward a work piece, and a shaping air ring  9  which is located at the front end of the air motor  7  and provided with a multitude of shaping air outlet holes  9 A (only two of which are shown in the drawings).  
     [0053] Indicated at  10  is a feed tube passage hole which is provided on the side of the sprayer unit  6 . This feed tube passage hole  10  is extended axially through the rotational shaft  7 B of the air motor  7 . In this instance, the base end of the feed tube passage hole  10  on the side of the sprayer unit is opened into the feed tube passage portion  5 A of the feed tube passage hole  5  on the side of the housing, while its fore end is opened into the rotary atomizing head  8 . Further, the feed tube passage hole  10  on the side of the sprayer unit is formed in coaxial relation with the afore-mentioned feed tube passage portion  5 A. The feed tube  23  of the paint cartridge  20  is extractably fitted into these feed tube passage holes  5  and  10 .  
     [0054] Designated at  11  is a high voltage generator which is provided in the neck portion  2 A of the housing  2 . The high voltage generator  11  is constituted, for example, by a Cockcroft circuit which is adapted to elevate a source voltage from a power supply (not shown) to a high voltage, for example, to a level between −60 kv and −120 kv. The output side of the high voltage generator  11  is electrically connected, for example, to the air motor  7 . A high voltage is therefore applied to the rotary atomizing head  8  from the high voltage generator  11  through the rotational shaft  7 B of the air motor  7  to charge the paint directly.  
     [0055] Indicated at  12  are a plural number of air passages which are provided in the neck portion  2 A of the housing  2  and connected to a control air source (not shown). The air passages  12  includes a turbine air passage which supplies turbine air for controlling the air motor  7 , a bearing air passage, a brake air passage and a shaping air passage which supplies shaping air for shaping the paint spray pattern. In the case of the particular embodiment shown, only one air passage is shown to represent the various air passages as mentioned above.  
     [0056] Indicated at  13  is an extruding thinner passage which is provided on the side of the housing  2 . One end of this extruding thinner passage  13  is connected to an extruding thinner supply unit (not shown) which supplies extruding thinner toward the paint cartridge  20 . The other end of the extruding thinner passage  13  is opened into a female coupling portion (not shown) which is provided on the bottom surface  4 A of the cartridge mount portion  4 , for communication with an extruding thinner passage  27  on the side of the paint cartridge, which will be described hereinafter.  
     [0057] Indicated at  14  is a pilot air passage which is provided on the side of the housing  2 . One end of this pilot air passage  14  is connected to a paint valve pilot air source (not shown) through pilot air piping. The other end of the pilot air passage  14  is opened into a male coupling portion (not shown) which is provided on the bottom surface  4 A of the cartridge mount portion  4 , for communication with a pilot air passage  30  on the side of the paint cartridge, which will be described hereinafter.  
     [0058] Denoted at  15  is an ejection air supply passage which is provided in the housing  2  and opened in the bottom surface  4 A of the cartridge mount portion  4 . This ejection air supply passage  15  is connected to an ejection air source through air piping (both of which are not shown in the drawings). Through the ejection air supply passage  15 , ejection air is supplied to an ejection air space  16  (shown in FIG. 2) which is defined between the cartridge mount portion  4  and the container  21  of the paint cartridge  20 , permitting to dismantle the latter from the cartridge mount portion  4 .  
     [0059] Indicated at  17  is a thinner valve which is provided in the head portion  2 B of the housing  2 . The thinner valve  17  is accommodated in a thinner valve receptacle cavity  18 . Normally, the extruding thinner passage  13  on the side of the housing is blocked by the thinner valve  17  to stop thinner supply to the extruding thinner chamber  26  of the paint cartridge  20 . On the other hand, when pilot air is supplied to the thinner valve  17  from the thinner valve pilot air source (not shown) through the pilot air passage  19 , the thinner valve puts the extruding thinner passage  13  into communication to permit thinner supply to the extruding thinner chamber  26 .  
     [0060] Indicated at  20   a ,  20   b  . . .  20   n  are paint cartridges which are filled with different colors, color a, color b, . . . color n, (hereinafter generally referred to as “paint cartridges 20”) for supply to the rotary atomizing head  8 .  
     [0061] Further, as shown in FIG. 4, the paint cartridges  20  are each largely constituted by a container  21  and a feed tube  23 .  
     [0062] Denoted at  21  is a container which constitutes a main  10  body of the paint cartridge  20 . The container  21  is formed in the shape of a cylindrical shell (cylinder) of a diameter slightly smaller than the inside diameter of the cartridge mount portion  4  of the housing. Front and rear ends of the container  21  are closed with front and rear surfaces  21 A and  21 B, respectively. As shown in FIG. 5, a plural number of magnetic member fitting grooves  21 C are formed in the front surface  21 A of the container  21 , for example, at four angularly spaced positions in the circumferential direction, to attach thereto magnetic members  34 , which will be described  20  hereinafter. Further, at a position close to the front end, an annular groove  21 D is formed around the outer periphery of the container  21  to receive therein an O-ring  31 , which will be described hereinafter. On the other hand, formed on the rear surface  21 B is a knob portion  21 E to be gripped by a gripper at the time of replacement of the paint cartridge  20 .  
     [0063] Designated at  22  is a conical projection which is projected axially forward from and at a center position of the front surface  21 A. The conical projection  22  which forms part of the container  21  is gradually reduced in diameter in the forward direction. As the cartridge container  21  is fitted into the cartridge mount portion  4  of the housing  2 , the conical projection  22  is brought into fitting engagement with the conically converging portion  5 B of the feed tube passage hole  5  thereby to set the container  21  in position in the axial and radial directions.  
     [0064] Further, indicated at  23  is a feed tube which is extended axially forward from a distal end of the conical projection  22  of the cartridge container  21 . A paint passage  23 A is formed coaxially through the feed tube  23 . The base end of the paint passage  23 A is connected to a paint chamber  25 , which will be described hereinafter, while its fore end is opened toward the rotary atomizing head  8 . On the other hand, when the paint cartridge  20  is set in the cartridge mount portion  4 , the feed tube  23  is passed into the feed tube passage holes  5  and  10  and its fore end is placed within the rotary atomizing head  8 .  
     [0065] In this instance, the feed tube  23  serves to receive a supply of paint from the paint chamber  25 , which will be described hereinafter, and convey same through the paint passage  23 A, letting the paints spurt from the fore end of the paint passage  23 A toward the rotary atomizing head  8 . Besides, at the time of replenishing paint into the paint chamber  25 , the feed tube  23  is utilized as a paint replenishing port.  
     [0066] Indicated at  24  is a piston which is axially slidably fitted in the cartridge container  21 . By the piston  24 , the internal space of the cartridge container  21  is divided into a paint chamber  25  which is in communication with the paint passage  23 A of the feed tube  23 , and an extruding thinner chamber  26  which accommodates thinner as an extruding liquid.  
     [0067] Denoted at  27  is an extruding thinner passage on the side of the paint cartridge. This extruding thinner passage  27  is extended axially through the casing of the cartridge container  21  along the outer peripheral side of the latter. In this instance, one end of the extruding thinner passage  27  on the side of the paint cartridge is opened into a male coupling portion (not shown) which is provided on the front surface  21 A of the cartridge container  21 , while the other end is communicated with the extruding thinner chamber  26 . As soon as the paint cartridge  20  is set in the housing  2 , with the extruding thinner passage  27  on the side of the cartridge connected with the extruding thinner passage  13  on the side of the housing, thinner can be supplied to the extruding thinner chamber  26 . As a result, the piston  24  in the cartridge container  21  is pushed toward the feed tube  23  to extrude the paint in the paint chamber  25  toward the rotary atomizing head  8 .  
     [0068] The thinner which is employed as an extruding liquid should be of an electrically insulating type or of a high electric resistance type in order to prevent leaks of the high voltage of the high voltage generator  11  through the thinner.  
     [0069] Indicated at  28  is a paint valve which is provided in the casing of the cartridge container  21 . The paint valve  28  is accommodated in a paint valve receptacle cavity  29 , and largely constituted by a piston  28 A which is slidably fitted in the paint valve receptacle cavity  29 , a valve member  28 B for opening and closing the paint passage  23 A of the feed tube  23 , and a valve spring  28 C for biasing the valve member  28 B in a closing direction through the piston  28 A. Consequently, the valve member  28 B is arranged to normally close the paint passage  23 A under the influence of the biasing force of the valve spring  28 C to suspend paint supply to the rotary atomizing head  8 . On the other hand, as soon as pilot air is supplied from a paint valve pilot air source (not shown) through the pilot air passage  14  on the side of the housing and a pilot air passage  30  on the side of the paint cartridge, the piston  28 A is displaced in an opening position against the action of the valve spring  28 C, bringing the paint passage  23 A into communication to permit paint supply to the rotary atomizing head  8 .  
     [0070] Indicated at  31  is an O-ring which is fitted in the annular groove  21 D of the cartridge container  21  as a seal member. When the cartridge container  21  is set in the cartridge mount portion  4  of the housing  2 , the O-ring  31  is brought into sliding contact with the inner peripheral surfaces of the cartridge mount portion  4 . As a consequence, the O-ring  31  contributes to enhance the air-tightness of the ejection air space  16  which is defined between the cartridge mount portion  4  and the cartridge container  21 .  
     [0071] Denoted at  32  is a magnetic holding mechanism which is provided between the cartridge mount portion  4  and the paint cartridge  20 . This magnetic holding mechanism  32  serves to detachably fasten the paint cartridge  20  to the cartridge mount portion  4  by magnetic attraction. As shown in FIG. 6, the magnetic holding mechanism  32  is constituted by permanent magnets  33  and magnetic members  34 .  
     [0072] Indicated at  33  are a plural number of permanent magnets, for example, four permanent magnets which are attached on the bottom surface  4 A of the cartridge mount portion  4  of the housing  2 . In this instance, the permanent magnets  33  are each formed in a short cylindrical shape by the use of a magnetic material with a large magnetic coersive force, for example, by the use of metal magnet, ferrite magnet or the like. The permanent magnets  33  are fixedly set in the magnet fitting grooves  4 B on the bottom surface  4 A of the cartridge mount portion, and have the respective outer surfaces located substantially flush with the bottom surface  4 A.  
     [0073] Indicated at  34  are a plural number of magnetic members, for example, four magnetic members which are provided on the side of the container  21  of the paint cartridge  20 . In this instance, the magnetic members  34  are each formed in a short cylindrical shape by the use of a magnetic material which is small in coercive force and large in relative permeability, for example, by the use of a magnetic material such as silicon steel, permalloy or the like. Each one of the magnetic members  34  are fixedly set in the magnetic member fitting grooves  21 C in the front surface  21 A of the cartridge container  21  in such a way as to confront face to face with the permanent magnets  33 . The outer surfaces of the magnetic members  34  are located substantially flush with the front surface  21 A of the cartridge container  21 .  
     [0074] As the container  21  of the paint cartridge  20  is set in the cartridge mount portion  4  of the housing  2 , the magnetic members  34  on the side of the paint cartridge  20  are magnetically attracted to the permanent magnets  33  on the side of the housing  2 . Therefore, the paint cartridge  20  is fixedly gripped in the cartridge mount portion  4  by the magnetic holding mechanism  32 .  
     [0075] In order to dismantle the paint cartridge  20  which is fixedly held in the cartridge mount portion  4  of the housing  2  by the magnetic force of the magnetic holding mechanism  32 , ejection air is supplied to the ejection air space  16  through the ejection air supply passage  15 . Whereupon, the paint cartridge  20  is pushed out by the air pressure in the ejection air space  16 , permitting to dismantle the cartridge  20  against the magnetic force of the magnetic holding mechanism  32 .  
     [0076] In the case of the present embodiment, the magnetic holding mechanism  32  has the permanent magnets  33  on the side of the housing  2  and the magnetic members  34  on the side of the paint cartridge  20 . Of course, instead of this combination, there may be employed an arrangement in which the magnetic members  34  are located on the side of the housing  2  and the permanent magnets  33  are located on the side of the paint cartridge  20 . Alternatively, in addition to the permanent magnets  33  which are provided on the side of the housing  2 , other permanent magnets may be provided also on the side of the paint cartridge  20  with a different magnetic pole arrangement relative to the permanent magnets  33  on the side of the housing  2 . In any case, the paint cartridge  20  can be fixedly held in the housing  2  by magnetic attraction.  
     [0077] Having the arrangements as described above, the cartridge type coating machine  1  according to the present embodiment is used in the following manner, for example, in coating color a.  
     [0078] In the first place, a paint cartridge  20   a  which is filled with the color a is set in the cartridge mount portion  4  of the housing  2 . Then, the rotary atomizing head  8  is put in high speed rotation by the air motor  7 , while shaping air is spurted out from the shaping air ring  9 . In this state, the thinner valve  17  and paint valve  28  are opened, whereupon extruding thinner is supplied to the extruding thinner chamber  26  of the paint cartridge  20   a  through the extruding thinner passages  13  and  27 . As a result, the color a paint in the paint chamber  25  is pushed out by the piston  24  under the pressure of the extruding thinner, and spurted out toward the rotary atomizing head  8  through the paint passage  23 A of the feed tube  23 . The paint of color a which has been spurted into the rotary atomizing head  8  is atomized into finely divided paint particles by the latter, and sprayed toward a work piece in a spray pattern which is controlled by shaping air.  
     [0079] The paint cartridge  20  is loaded on and unloaded from the cartridge mount portion  4  of the housing  2  in the manner as described below.  
     [0080] Firstly, for loading the paint cartridge  20  on the cartridge mount portion  4 , the knob portion  21 E on the container  21  of the paint cartridge  20  is gripped by an arm (not shown) of a cartridge changer, and the paint cartridge  20  is put into the cartridge mount portion  4  from its front end with the feed tube  23 . As a consequence, the feed tube  23  is inserted into the feed tube passage holes  5  and  10 , and a front portion of the cartridge container  21  is fitted into the cartridge mount portion  4 . As the cartridge container  21  is pushed deeper into the cartridge mount portion  4 , it is fixed to the latter by magnetic force of the magnetic holding mechanism  32 , that is, by magnetic attraction of the magnetic members  34  on the front surface  21 A of cartridge container  21  toward the permanent magnets  33  which are provided on the bottom surface  4 A of the cartridge mount portion  4 .  
     [0081] Further, at the time when the paint cartridge  20  is set on the housing  2  by the magnetic holding mechanism  32 , the conical projection  22  is brought into abutting engagement with the conically converging portion  5 B of the feed tube passage hole  5  on the side of the housing to locate the feed tube  23  at the center of the rotary atomizing head  8 .  
     [0082] On the other hand, at the time of dismantling the paint cartridge  20  from the cartridge mount portion  4 , ejection air is supplied to the ejection air space  16  through the ejection air supply passage  15 . Whereupon, the air pressure in the ejection air space  16 , which is hermetically sealed by the O-ring  31 , is increased to push the paint cartridge  20  away from the bottom surface  4 A of the cartridge mount portion  4  against the force of magnetic attraction between the magnetic member  34  and the permanent magnet  33  of the magnetic holding mechanism  32 . In this state, the paint cartridge  20  can be easily dismantled from the cartridge mount portion  4  by gripping and extracting the knob portion  21 E of the container  21  with an arm of cartridge changer (not shown).  
     [0083] Thus, according to the first embodiment, the magnetic holding mechanism  32  which is provided between the housing  2  and the paint cartridge  20  is constituted by the permanent magnet  33  which is provided on the bottom surface  4 A of the cartridge mount portion  4  and the magnetic member  34  which is provided on the front surface  21 A of the container  21 . Upon fitting the container  21  into the cartridge mount portion  4 , the paint cartridge  20  is fixedly retained on the housing  2  by magnetic attraction between the permanent magnet  33  and the magnetic member  34 . It follows that even in the event of a trouble to a component which is operatively connected to the cartridge type coating machine  1 , the paint cartridge  20  can be fixedly retained on the housing  2  without applying an external force by the use of an external device like a vacuum generator, which has thus far been resorted to on such occasions.  
     [0084] As a consequence, the paint cartridge  20  is prevented from getting loose and falling off the housing  2 , precluding the undesirable situations which would require to stop the coating line and thus ensuring high productivity of coating operation. In addition, the use of the magnetic forces of the permanent magnets  33  contributes to lower the running cost and to enhance convenience in handling.  
     [0085] Further, since the ejection air supply passage  15  is opened in the bottom surface  4 A of the cartridge mount portion  4  of the housing  2 , the paint cartridge  20  can be easily dismantled from the cartridge mount portion  4  as soon as ejection air is supplied to the ejection air space  16  through the ejection air supply passage  15 . In other words, the paint cartridge  20  can be dismantled in an efficient manner.  
     [0086] Now, turning to FIGS. 7 and 8, there is shown a second embodiment of the present invention. This embodiment has features in that the magnetic holding mechanism is constituted by a first magnet group consisting of rows of a plural number of permanent magnets which are provided either on the side of the cartridge mount portion of the housing or on the side of the paint cartridge and alternately changed in magnetic pole position, and a second magnet group likewise consisting of rows of a plural number of permanent magnets which are provided on the other one of the cartridge mount portion of the housing and the paint cartridge and alternately changed in magnetic pole position inversely relative to confronting permanent magnets of the first magnet group. In the following description of the second embodiment, those component parts which are identical with the counterparts in the foregoing first embodiment are simply designated by the same or similar reference numerals to avoid repetitions of same explanations.  
     [0087] Indicated at  41  is a cartridge type coating machine according to the present embodiment, and at  42  a housing of the coating machine  41 . In this instance, a cartridge mount portion  43  in the form of a cylindrical cavity is formed on the rear side of a head portion  42 A of a housing  42 . Further, a plural number of magnet fitting grooves  43 B, for example, four magnet fitting grooves  43 B are provided in a bottom surface  43 A of the cartridge mount portion  43  at angularly spaced positions in the circumferential direction for attaching a first magnet group of permanent magnets  49 .  
     [0088] Designated at  44  (FIG. 8) is a paint cartridge according to the present embodiment, which is replaceably set in the cartridge mount portion  43  of the housing  42 . Similarly to the counterpart in the foregoing first embodiment, the paint cartridge  44  is largely constituted by a container or casing  45 , a conical projection  46  and a feed tube  47 . Further, the cartridge container  45  is formed in the shape of a hollow cylinder which is closed at the opposite ends, and provided with a plural number of magnet fitting grooves  45 B, for example, four magnet fitting grooves at angularly spaced positions on its front surface  45 A for attaching a second magnet group of the permanent magnets  50 , which will be described hereinafter.  
     [0089] Now, indicated at  48  is a magnetic holding mechanism according to the present embodiment, which is provided between the cartridge mount portion  43  of the housing  42  and the paint cartridge  44 . This magnetic holding mechanism  48  is provided also for detachably holding the paint cartridge  44  in the cartridge mount portion  43  of the housing  42  by magnetic attraction, and is largely constituted by first magnet groups  49  and second magnet group  50 , as described below.  
     [0090] More specifically, indicated at  49  is the first magnet groups including, for example, four sets of permanent magnets which are fixedly set in the magnet fitting grooves  43 B. Each one of the first magnet group  49  is composed of three permanent magnets  49 A of rectangular parallelopiped shape which are arranged in a row in the circumferential direction. In this instance, the magnetic poles (S &amp; N) of the permanent magnets  49 A are positioned inversely relative to the confronting magnets of the second magnet group  50 . Namely, in the case of the particular example shown, the poles of the permanent magnets  49 A are arranged in the order of N-S-N.  
     [0091] Indicated at  50  is a second magnet group consisting of rows of a plural number of permanent magnets, for example, four sets of permanent magnets  50 A which are fixedly set in magnet fitting grooves  45 B on the casing of the container  45  in confronting relation with the first magnet group  49 . Similarly to the first magnet group  49 , each set of the second magnet group  50  is constituted by three permanent magnets  50 A of rectangular parallelopiped shape which are arranged in a row in the circumferential direction. Further, the poles of the permanent magnets  50 A are arranged inversely relative to the confronting permanent magnets  49 A of the first magnet group  49 . Namely, in the case of the particular example shown, the magnetic poles of the permanent magnets  50 A are arranged in the order of S-N-S inversely to the order of magnetic poles in the first magnet group  49 .  
     [0092] Thus, according to the second embodiment with the above-described arrangements, as soon as the paint cartridge  44  is set on the cartridge mount portion  43  of the housing  42 , it can be fixedly held in position within the cartridge mount portion  43  by the magnetic holding mechanism  48 , that is, by magnetic attraction between the first magnet group  49  on the side of the housing  42  and the second magnet group  50  on the side of the paint cartridge  44 .  
     [0093] Besides, the magnetic poles of the permanent magnets  49 A of the first magnet group  49  are arranged in the order of N-S-N, inversely to the opposing permanent magnets  50 A of the second magnet group  50  which are arranged in the order of S-N-S. Therefore, as the second magnet groups  50  approaches the first magnet groups  49 , homopolar repulsions and heteropolar attractions take place between the permanent magnets  50 A on the side of the paint cartridge and the permanent magnets  49 A on the side of the housing. It follows that positional deviations between the first magnet group  49  and the second magnet group  50 , if any, can be automatically corrected to set and fix the paint cartridge  44  accurately in position relative to the housing  42 .  
     [0094] Turning now to FIG. 9, there is shown a third embodiment of the present invention. In the case of this embodiment, the housing of the coating machine is provided with a cartridge mount portion which is also in the shape of a bottomed cylindrical cavity, and each one of paint cartridges is largely constituted by a cylindrical container for a supply of paint and a feed tube which is extended axially forward from the container. However, the present embodiment has features in that a seal member is provided either on a bottom surface of the cartridge mount portion or on an opposing front surface of the container in such a way as to define an ejection air space by abutting engagement with the bottom surface of the cartridge mount portion or the front surface of the container for introduction of ejection air. In the following description of the third embodiment, those component parts which are same as or equivalent with counterparts in the foregoing first embodiment are simply indicated by the same or similar reference numerals to avoid repetitions of same explanations.  
     [0095] Denoted at  61  is a cartridge type coating machine according to the present embodiment, and at  62  is a housing of the coating machine  61 . In this instance, the housing  62  is also provided with a cartridge mount portion  63  in the form of a cylindrical cavity on the rear side of its head portion  62 A. Further, a plural number of magnet fitting grooves  63 B are formed in a bottom surface  63 A of the cartridge mount portion  63  at angularly spaced positions in the circumferential direction for holding permanent magnets  33  therein. Furthermore, for fitting in an O-ring  68  which will be described hereinafter, an annular groove  63 C is formed in the bottom surface  63 A of the cartridge mount portion  63  at a position radially outward of the respective magnet fitting grooves  63 B and the ejection air supply passage  15 .  
     [0096] Indicated at  64  is a paint cartridge according to the present embodiment, to be replaceably set in the cartridge mount portion  63  of the housing  62 . This paint cartridge  64  is largely constituted by a container  65 , a conical projection  66  and a feed tube  67 .  
     [0097] In this instance, similarly to the container  21  in the foregoing first embodiment, the container  65  of this embodiment is formed in a cylindrical shape which is slightly smaller in diameter than the cartridge mount portion  63  and closed at the opposite ends. A plural number of magnetic member fitting grooves  65 B are formed in a front surface  65 A of the container at angularly spaced positions in the circumferential direction for fitting magnetic members  34  therein. However, the container  65  of this embodiment differs from the container  21  of the foregoing first embodiment in that the annular groove  21 D is abolished.  
     [0098] Indicated at  68  is an O-ring which is fitted in the annular groove  63 C on the bottom surface  63 A of the cartridge mount portion  63  to serve as a seal member. The O-ring  68  is hermetically engaged with the front surface  65 A of the container  65  when the paint cartridge  64  is loaded into the cartridge mount portion  63  of the housing, forming an ejection air space  69  between the bottom surface  63 A and the front surface  65 A of the container  65 .  
     [0099] In this instance, upon supplying ejection air through the ejection air supply passage  15 , the ejection air space  69  is expanded to separate the container  65  away from the bottom surface  63 A of the cartridge mount portion  63  against the magnetic force of the magnetic holding mechanism  32 , permitting to dismantle the paint cartridge  64  from the cartridge mount portion  63 .  
     [0100] Thus, according to the above-described third embodiment, the ejection air space  69  is defined by the O-ring  68  which is provided in the bottom surface  63 A of the cartridge mount portion  63 . Therefore, the O-ring  68  is simply brought into abutting engagement with the front surface  65 A of the container  65 , with less susceptibility to twisting deformation or sliding abrasion as compared with the conventional O-ring which is fitted around the outer periphery of the container. Thus, the arrangements of the present embodiment contribute to prolong the service life of the O-ring  68 .  
     [0101] Further, as mentioned above, there is little possibilities of the O-ring  68  being deformed by twisting when the paint cartridge  64  is loaded into or unloaded from the cartridge mount portion  63 . This means that the fore end of the feed tube  67  can be located at a center position in the rotary atomizing head  8 . Therefore, the feed tube can supply paint smoothly toward the rotary atomizing head  8  and in such a way as to enhance the operational reliability of the cartridge type coating machine  61 .  
     [0102] Turning now to FIGS. 10 and 11, there is shown a fourth embodiment of the present invention. This fourth embodiment has features in that projections and recesses of complementary shapes are provided on confronting surfaces of permanent magnets and magnetic members to be coupled with each other. In the following description of the fourth embodiment, those component parts which are identical with the counterparts in the foregoing first embodiment are simply designated by the same or similar reference numerals to avoid repetitions of the same explanations.  
     [0103] Indicated at  71  is a magnetic holding mechanism according to the present embodiment, which is provided between the cartridge mount portion  4  of the housing  2  and a paint cartridge  20 . This magnetic holding mechanism  71  serves to hold the paint cartridge  20  in the cartridge mount portion  4  by magnetic attraction, and largely constituted by permanent magnets  72  and magnetic members  73 , which will be described hereinafter.  
     [0104] Indicated at  72  are a plural number of permanent magnets which are fitted in magnet fitting grooves  4 B on the side of the cartridge mount portion  4 . As shown in FIG. 11, each one of the permanent magnets  72  is formed substantially in a short cylindrical shape. A convex projection  72 A is formed on the outer surfaces of the permanent magnets  72  which confront magnetic members  73  which are provided on the side of the paint cartridge as described below.  
     [0105] Indicated at  73  are a plural number of magnetic members which are set in magnetic member fitting grooves  21 C on the container  21 . Each one of the magnetic members  73  is formed substantially in a short cylindrical shape. Further, each one of the magnetic members  73  are formed with a concave recess  73 A on an outer surface which confronts one of the permanent magnets  72 .  
     [0106] In this instance, as the paint cartridge  20  is loaded into the cartridge mount portion  4 , the magnetic members  73  are attracted to the permanent magnets  72  to hold the paint cartridge  20  fixedly in the cartridge mount portion  4  by magnetic force. As the convex projection  72 A of the permanent magnets  72  and the concave recesses  73 A of the magnetic members  73  are formed of the gradually inclining surface, the positional deviations between the permanent magnets and the magnet members, if any, can be automatically corrected to set and fix the paint cartridge  20  accurately in position relative to the housing  2 .  
     [0107] Turning now to FIG. 12, there is shown a fifth embodiment of the present invention. This embodiment has features in that a magnetic holding mechanism is constituted by electromagnets which are provided either on the side of the cartridge mount portion of the housing or on the side of a paint cartridge and magnetic member which are provided opposingly either on the side of the paint cartridge or on the side of the cartridge mount portion of the housing. In the following description of the fifth embodiment, those component parts which are identical with the counterparts in the foregoing first embodiments are simply designated by the same or similar reference numerals to avoid repetitions of the same explanations.  
     [0108] Indicated at  81  is a cartridge type coating machine according to the present embodiment, and at  82  is a housing of the coating machine  81 . In this instance, similarly to the housing  2  of the foregoing first embodiment, the housing  82  of this embodiment is provided with a cartridge mount portion  83  in the form of a cylindrical cavity on the rear side of its head portion  82 A. A plural number of electromagnets fitting grooves  83 B are formed in a bottom surface  83 A of the cartridge mount portion  83  at angularly spaced positions in the circumferential direction for fixing therein electromagnets  89  which will be described after. However, the housing  82  of this embodiment differs from the housing  2  of the first embodiment in that the ejection air supply passage  15  is abolished.  
     [0109] Designated at  84  is a paint cartridge according to the present embodiment. Similarly to the paint cartridge  20  of the first embodiment, the paint cartridge  84  is largely constituted by a container  85 , a conical projection  86  and a feed tube  87 . However, the paint cartridge  84  of this embodiment differs from the paint cartridge  20  of the first embodiment in that the annular groove  21 D for the O-ring  31  is abolished from the container  85 .  
     [0110] Indicated at  88  is a magnetic holding mechanism according to the present embodiment, which is provided between the cartridge mount portion  83  of the housing  82  and a paint cartridge  84 . The magnetic holding mechanism  88  functions to fixedly hold the paint cartridge  84  in the cartridge mount portion  83  by magnetic attraction. The magnetic holding mechanism  88  is constituted by the above-described magnetic members  34 , in combination with electromagnets  89  as described below.  
     [0111] Indicated at  89  are a plural number of electromagnets which are fixed in the electromagnets fitting grooves  83 B on the side of the cartridge mount portion  83 . For example, each one of the electromagnets  89  is an explosion-proof electromagnet having an iron core  89 A and a coil winding  89 B, both clad in a molded synthetic resin material. The coil winding  89 B is connected to a power source through wiring  89 C.  
     [0112] As soon as power is supplied through the wiring  89 C, each electromagnet  89  is energized to produce magnetic force. In this state, upon loading the container  85  of the paint cartridge into the cartridge mount portion  83 , the magnetic members  34  are attracted toward the electromagnets  89  to hold the paint cartridge  84  fixedly in the cartridge mount portion  83  by magnetic force. Upon cutting off power supply and de-energizing the electromagnets  89 , the paint cartridge  84  can be easily dismantled or unloaded from the cartridge mount portion  83 .  
     [0113] Thus, in the case of the fifth embodiment with the above-described arrangements with the electromagnets  89 , the paint cartridge  84  can be easily dismantled upon turning off power supply to and de-energizing the electromagnets  89 . Accordingly, in this case, it becomes possible to omit the ejection air supply passage for simplifying the construction of the coating machine.  
     [0114] In the foregoing first embodiment, the permanent magnets  33  and magnetic members  34  of the magnetic holding mechanism  32  are each shown as being in a short cylindrical shape. However, the present invention is not limited to this particular example. For example, as shown as a first modification in FIG. 13, a magnetic holding mechanism  91  can be constituted by permanent magnets  92  and magnetic members  93  of tubular shape. This modification can be similarly applied to other embodiments of the present invention.  
     [0115] Further, as shown as a second modification in FIG. 14, there may be employed a magnetic holding mechanism  101  consisting of tubular permanent magnets  102  and magnetic members  103 , each one of the permanent magnets having arcuate projections  102 A at radially opposite positions for fitting engagement with arcuate recesses or notches  103 A on the side of the magnetic member  103 .  
     [0116] Further, in the case of the above-described fourth embodiment, the spherical or convex projections  72 A are provided on the permanent magnets  72  for fitting engagement with concave recesses  73 A which are provided on the side of the magnetic members  73 . However, it is to be understood in this regard that the present invention is not limited to the particular example shown. For instance, conical projections may be provided either on the side of the magnets or on the side of the magnetic members for engagement with conical recesses or notches which are provided either on the side of the magnetic members or on the side of the magnets. If desired, the magnets and the confronting magnetic members may be engaged through projections and recesses of other shapes.  
     [0117] Further, according to the above-described first embodiment, the permanent magnets  33  and magnetic members  34  of the magnetic holding mechanism  32  are located at four angularly spaced positions in the circumferential direction. However, it is to be understood in this regard that the present invention is not limited to the particular example shown. For instance, the permanent magnets  33  and magnetic members  34  may be provided at two, three or more than five different positions which are angularly spaced in the circumferential direction.  
     [0118] Furthermore, in the foregoing embodiments, the paint passage  23 A in the feed tube  23  of the paint cartridge  20  is shown as having a function as an inlet passage for a wash fluid like thinner, in addition to functions as a paint supply passage to be used at the time of supplying paint from the paint cartridge  20  and a paint replenishing passage to be used at the time of replenishing paint into the paint cartridge  20 . However, the present invention is not limited to such arrangements. For example, like the paint cartridge which is described in Japanese Patent Laid-Open No. 2002-11396, a wash fluid passage may be provided in the container separately from the paint passage of the feed tube. In this case, on the part of a paint replenisher, a wash fluid passage is provided separately from a connector member which is arranged to permit paint flows into and out of the feed tube of the paint cartridge. At the time of washing a paint cartridge, a wash fluid is supplied to the paint cartridge from the wash fluid passage on the side of the paint replenisher through the wash fluid passage on the side of the cartridge.  
     [0119] Further, in the foregoing first embodiment, the cartridge mount portion  4  is formed in the shape of a flat cylindrical cavity with the bottom surface  4 A, and the permanent magnets  33  are attached to the bottom surface  4 A in confronting relation with the magnetic members  34  which are attached to the flat front surface  21 A of the container  21 . However, it is to be understood that the present invention is not limited to the particular arrangements shown. For instance, the bottom surface of the cartridge mount portion with the permanent magnets and the front surface of the container casing with the magnetic members may be formed complementarily in concave and convex shapes, respectively, if desired.  
     [0120] On the other hand, in the foregoing first embodiment, the cartridge type coating machine  1  is shown as being composed of the air motor  7  and the rotary atomizing head type sprayer unit  6  with the rotary atomizing head  8 . However, the present invention is not limited to this particular type of coating machine. For example, the present invention can be similarly applied to cartridge type coating machines with other sprayer units such as a hydraulic atomization type or pneumatic atomization type sprayer unit. The same applies to other embodiments of the invention.  
     [0121] Moreover, in the foregoing first embodiment, by way of example thinner is used as an extruding liquid for pushing paint out of the container  21  of the paint cartridge  20 . However, depending upon the type of paint and the method of high voltage application, water or other extruding liquid may be employed in place of thinner. The same applies to other embodiments of the invention.