Patent Publication Number: US-7213774-B1

Title: Air brush

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an air brush, and more particularly, to an air brush where a disassembly operation of an air brush main body can be easily performed. 
   DESCRIPTION OF RELATED ART 
     FIG. 5  shows a conventional air brush. This air brush  100  is a trigger type air brush having an approximately long-cylindrical air brush main body  101  with a nozzle member  102  at its end. Further, a needle  103  is inserted reciprocably along the axial center inside the air brush main body  101 . 
   In the air brush  100 , compressed air is supplied to an air supply orifice  104  connected with an intermediate part of the air brush main body  101 . The compressed air is introduced via an air valve  105  to a ventilation path  112  in the air brush main body  101 , and blown out of the nozzle member  102 . Note that the air valve  105  is opened by depression of a valve stem  105   a.    
   The air brush  100  has a finger hooking lever  106  in the intermediate part of the air brush main body  101 . A slide cam  107  placed inside the air brush main body  101  is slid in a withdrawal direction and a needle chuck  108  in contact with the rear end of the slide cam  107  is withdrawn by triggering the finger hooking lever  106 . 
   The above needle chuck  108  is inserted through the axial center of a body ring  110  engaged in a rear end opening of the air brush main body  101 , and is supported slidably in the withdrawal direction. Further, a groove  108   a  for rotation stop expanded in an axial direction is formed around the outer periphery of the needle chuck  108 . An end of a stopper screw  115  screw-engaged from the outside of the rear part of the air brush main body  101  is engaged in the groove  108   a , thereby the needle chuck  108  is supported unrotatably but withdrawably toward the axial direction. 
   A spring case  112  is screw-engaged between the rear end of the air brush main body  101  and a tail case  111  so as to detachably connect the air brush main body  101  with the tail case  111 . Further, a coil spring  113  to always push the needle chuck  108  and the needle  103  in a frontward direction is elastically set inside the tail case  111 . A holder part of the needle chuck  108  projected from the rear end of the needle chuck  108  is a chuck member  114  screw-engaged with a chuck screw  116  to hold the needle  103 . Note that the chuck member  114  and the rear end of the needle  103  are covered with the above tail case  111 . 
   To use the air brush  100  having the above structure always in good condition, it is necessary to periodically perform maintenance such as disassembly of the air brush to clean the needle and the nozzle member and grease up of an air-tight portion. The disassembly work is very troublesome for an inexperienced user. 
   Upon maintenance, to disassemble the air brush  100 , first, the tail case  111  is removed, the chuck screw  116  of the chuck member  114  is turned and removed, then the needle  103  is pulled out carefully. When further disassembly is required, the spring case  112  is removed from the air brush main body  101 , and the needle chuck  108  and the coil spring  113  are removed. In this state, the body ring  110  appears inside the rear end opening of the air brush main body  101 . 
   However, to remove the body ring  110  screw-engaged inside the air brush main body  101 , it is necessary to remove the stopper screw  115  as a rotation stopper with a comparatively small driver, then insert an appropriately large minus driver from the rear end opening of the air brush main body  101  to remove the body ring  110  by moving the body ring  110  back while turning the body ring  110 . 
   Since this operation is troublesome for the user who is unaccustomed to the disassembly work, in many cases, such user gives up the disassembly when the spring case  112  has been removed. A very few users can remove the body ring  110  then remove the slide cam  107 , a valve rod  118  to open/close the air valve  105 , and a Teflon (registered trademark)-coated stopper  117  to keep a liquid sealed state of the needle  103 . Accordingly, many users use the air brush for a long period without maintenance of the inside of the air brush main body, and such use causes degradation of functions and hastens breakage. 
   Note that the existence of a document related to air brush main body disassembly structure in the air brush as described above is unknown. 
   SUMMARY OF THE INVENTION 
   The present invention has been made in consideration of the above-described conventional art, and provides an air brush having a structure which can be easily disassembled and assembled in a simple form, without use of any particular tool as in the case of the conventional air brushes. 
   Accordingly, as a first aspect of the invention, provided is an air brush, in which a needle to open and close a nozzle member is inserted reciprocably in an axial direction, along an axial center of an approximately long-cylindrical air brush main body having the nozzle member at its end, compressed air supplied via an air valve provided in an intermediate part of the air brush main body is blown out of the nozzle member, the air valve is opened and the compressed air is introduced into the nozzle member by operation of a finger hooking mechanism provided in the intermediate part of the air brush main body, and the needle is withdrawn in the axial direction to spray paint supplied to the nozzle member, with the compressed air, wherein a screw connection member is provided between the air brush main body and a tail case connected with a rear part of the air brush main body so as to detachably screw-connect both members, and a needle chuck to hold the needle inserted therein is inserted from a rear position to abut on the axial center of the screw connection member and supported unrotatably but withdrawably in the axial direction; a spring case is fitted around an outer periphery of the needle chuck and is screw-engaged in a rear opening of the screw connection member, and a coil spring is elastically set in the spring case to always push the needle chuck toward a frontward direction; and a needle stopper screw is screw-engaged with the needle chuck projected from the spring case in a rearward direction. 
   The finger hooking mechanism has a trigger type or a push-button type structure. Any other existing mechanism can be used as long as the trigger, button or the like is operated with a hooked finger thereby the needle is moved in the axial direction to open the nozzle, and the valve opening is controlled in proportion to the nozzle opening. 
   Further, as a second aspect of the invention, in the above-described air brush, the finger hooking mechanism is a trigger type mechanism. The trigger type finger hooking mechanism has a trigger-type lever, a slide cam provided in the air brush main body slidably by the operation of the lever, and a spring to push the slide cam, and the like. The needle and the air valve are operated by triggering the lever. 
   Further, as a third aspect of the invention, in the above-described air brush, the finger hooking mechanism is a push-button type mechanism. The push-button type finger hooking mechanism has a push button on which a finger is hooked, an operation stick, an operation plate, and the like. The needle and the air valve are operated by depression of the button to pull the stick. 
   Further, as a fourth aspect of the invention, in the above-described air brush, the cross-sectional shape of a fit-insertion member of the needle chuck and an engagement hole of the screw connection member which the fit-insertion member fits and inserts is a regular polygonal shape. The structure to support the needle chuck unrotatably but slidably in a withdrawal direction can be simplified. Accordingly, disassembly and assembly operations can be easily performed. Further, since it is not necessary to form an engagement groove along the needle chuck and insert a stopper screw between members as in the case of the conventional air brushes, the number of parts can be reduced, and the labor of such work can be reduced. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other object, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a longitudinal cross-sectional view of an air brush according to an embodiment of the present invention; 
       FIG. 2  is an exploded perspective view of a screw connection member of the air brush; 
       FIG. 3  is a cross-sectional view cut along a line III—III in  FIG. 1 ; 
       FIG. 4  is a longitudinal cross-sectional view of the air brush having a push-button type finger hooking mechanism; and 
       FIG. 5  is a longitudinal cross-sectional view of a conventional air brush. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinbelow, a preferred embodiment of an air brush of the present invention will now be described in accordance with  FIGS. 1 to 3 .  FIG. 1  shows a longitudinal cross section of an air brush A of the present invention.  FIG. 2  shows an exploded view of a connection portion. 
   An air brush A has a trigger type finger hooking mechanism  60 . A nozzle member  2  as a part to blow compressed air and liquid paint is provided at an end of an approximately-cylindrical air brush main body  1 , and a needle  3  to arbitrarily open/close a nozzle  2   a  is inserted reciprocate-slidably along the axial center of the air brush main body  1 . 
   When the needle  3  is withdrawn by pulling the lever  6 , the liquid paint, supplied from a container  12  attached to a front part of the air brush main body  1 , is blown-sprayed, with the compressed air supplied through an air valve  5 , from the nozzle member  2 . 
   A connection cylinder  4  as a connection orifice of a compressed air supply hose is screw-connected with a joint member  51  integrally connected with an intermediate part of the air brush main body  1 , and the air valve  5  is provided inside the connection cylinder  4 . 
   The air valve  5  is opened by pushing a valve stem  5   a  integrally having a valve body  5   b  downward thereby moving the valve body  5   b  away from a valve seat  5   c . When the above air valve  5  is opened, the compressed air flows from a lower end orifice of the connection cylinder  4  as an air supply port toward the inside the air brush main body  1 , then passes through a ventilation path  11  provided inside the air brush main body  1  and is blown out of the nozzle member  2 . 
   Further, the valve stem  5   a  of the above air valve  5  is always pushed upward, i.e., toward the valve closing side, with a coil spring  5   d  elastically set on the lower surface side of the valve body  5   b . In this arrangement, the upper side end of the above valve stem  5   a  is always in a state where it is projected upward in the axial center in a fork member  5   e  integrally formed in a central lower part of the air brush main body  1  ( FIG. 1 ). 
   A valve rod  52 , maintaining an air tight state, is slidably fit-inserted inside the joint member  51  screw-connected with the connection cylinder  4 . The lower end of the valve rod  52  is in contact with the above valve stem  5   a , and the air valve  5  is opened by push-down of the valve rod  52 . A tail case  13  is removably screw-connected with the rear end opening of the air brush main body  1  via a screw connection member  8  to be described later such that the tail case covers an exposed portion from the rear end of the air brush main body  1  to the rear end of the needle  3 . 
   On the other hand, the lever  6  is attached to an immediately front position of the air valve  5  of the air brush main body  1 . The lever  6 , having a trigger type finger hooking part  6   a , branches into two parts expanding upward with release portions  61  on both right and left sides of the air brush main body  1  therebetween. An upper end of the lever  6  is pivotally supported with respect to a pivotal support member provided in an upper part of the air brush main body  1 , and pivoted about the pivotal support member in a direction in which the finger hooking part  6   a  is pulled. 
   The lever  6 , interlocked with a slide cam  62  provided inside the air brush main body  1 , moves the needle  3  frontward/rearward toward the axial direction. The slide cam  62  is frontward/rearward slidably provided inside a cylindrical internal space  14  formed inside the air brush main body  1 . The slide cam  62  has a hole  62   a  through which the needle  3  is inserted in its axial center, and has a flank surface  62   b  in contact with a side surface of the lever  6  and a cam surface  62   c  in contact with an edge of the lever  6 . Further, a comparatively large-diameter coil spring  15  is elastically provided between the slide cam  62  and the screw connection member  8 , to always elastically push the slide cam  62  and the lever  6  frontward. 
   Further, a tapered concave groove  62   d  is formed in a lower part of an outer peripheral surface of the slide came  62 , and the upper end of the valve rod  52  is in contact with the concave groove  62   d . In this arrangement, when the lever  6  is pulled, the slide cam  62  is slid rearward, then the valve rod  52  in contact with the concave groove  62   d  is gradually pushed, and the air valve  5  is opened in proportion to the amount of operation of the lever  6 . Further, a stopper  17  to keep a liquid sealed state is screw-engaged with a front part of the internal space  14  of the air brush main body  1 , and the needle  3  is inserted through the axial center. 
   The screw connection member  8  is a cylindrical member with a screw on its outer periphery. A front opening of the member is partitioned with a partition wall  8   a , and a hexagonal insertion hole  8   b  through which a needle chuck  9  is fit-inserted is formed in the axial center of the member. Further, a convex-shaped partition rib  8   c  is provided around a intermediate part of the outer periphery having the screw, and knurling is formed around the outer periphery of the partition rib  8   c  such that it is slightly projected from the outer periphery of the rear end of the air brush main body  1 . A spring case  7  is screw-engaged from a rear position in the rear end opening of the screw connection member  8 . 
   The needle chuck  9  is fit-inserted in the spring case  7 . The needle chuck  9  has a screw slotting at its rear end as a chuck member  9   a  to be screw-engaged with a needle stopper screw  10 . Further, the needle chuck  9  has a rib  9   b  formed around its outer periphery on the front part side, and has a fit-insertion member  9   c  having a regular hexagonal cross-sectional shape in a position front of the rib  9   b . In the needle chuck  9 , the fit-insertion member  9   c  is inserted through the hexagonal insertion hole  8   b  formed in the screw connection member  8  from a rear position to bring the rib into contact with the partition wall  8   a , thereby support the needle chuck unrotatably but slidably in a withdrawal direction utilizing the above fit-engagement relation ( FIG. 3 ). 
   The spring case  7  is a case member having a partition wall  7   a  in its rear end opening and a screw formed around its front side outer periphery for screw-connection in the rear end opening of the above screw connection member  8 . A hole  7   b  through which the needle chuck  9  is inserted is formed in the axial center of the partition wall  7   a  of the spring case  7 , such that in an attached state, the coil spring  16  fitted in the needle chuck  9  inserted through along the axial center can be elastically provided between the partition wall  7   a  and the rib  9   b  of the needle chuck  9 . In the attached state, the rear end of the needle  3  and the chuck member  9   a  of the needle chuck  9  are projected from the hole  7   b  at the rear end of the spring case  7 , and the needle stopper screw  10  is screw-engaged with the chuck member  9   a  to fasten the chuck member  9   a.    
   When the air brush A having the above structure is disassembled for maintenance or the like, the tail case  13  is turned and removed, and the needle stopper screw  10  of the exposed chuck member is removed. In this state, as the needle  3  can be pulled out in a rearward direction, the needle  3  is pulled out carefully. When the needle  3  has been pulled out, the screw-engagement of the spring case  7  is released, then is removed, with the coil spring  16 , in the rearward direction, and at the same time, the needle chuck  9  is pulled out. In this state, cleaning of the needle, checking of the needle chuck, checking and cleaning of the coil spring  16 , and the like, can be performed. 
   To further disassemble the air brush, the screw connection member  8  is removed from the rear end of the air brush main body  1  while it is turned, and the coil spring  15  is removed from the rear part of the opened air brush main body  1 . In this state, to remove the slide cam  62 , first, the connection cylinder  4  holding the air valve is removed from the joint member  51  of the air brush main body  1 , and the valve rod  52  is moved downward. Then, the slide cam  62  can be pulled in the rearward direction. 
   In this manner, when the slide cam  62  has been removed from the air brush main body  1 , the internal space  14  in the main body is opened, and the valve rod  52  can be pulled out of a pull-out hole  18  formed in the upper part of the air brush main body  1 . Further, as the stopper  17  screw-engaged with the front end surface of the internal space  14  in the air brush main body  1  can appear, the engagement is released with a general driver inserted from the rear opening of the air brush main body  1 , thereby the stopper  17  can be easily removed. In the above disassembly process, almost all the maintenance work regarding the inside of the air brush main body  1  can be performed. The labor of disassembly operation can be much reduced. Further, as maintenance work can be freely performed on the fine parts, even a user unaccustomed to disassembly can use the air brush always in good condition. 
   Although an air brush A 2  shown in  FIG. 4  has a similar disassembly structure to that of the above-described air brush A, the air brush A 2  has a push-button type finger hooking mechanism  20 . 
   As in the case of the above air brush A, in the air brush A 2 , the air brush main body  1  and the tale case are detachably connected via the screw connection member  8 . The screw-connection member  8  is screw-engaged with the spring case  7  in the state where the needle chuck  9  is fit-inserted and the coil spring  16  is elastically set in the screw connection member  8 . Further, the needle stopper screw  10  is screw-engaged with the rear end of the needle chuck  9  projected from the spring case  7 , to hold the needle  3 . 
   On the other hand, a notched opening  21  is formed in the upper part of a central part of the air brush main body  1 , and an operation stick  22  is fit-inserted from the notched opening and is attached push-operably. The operation stick  22  is provided with an operation button  23  on which a finger is hooked at an upper end, and its lower end as a fit-insertion end is connected with the upper end of a push stick  25  via a pivot member  24 . The push stick  25  is in contact with the upper end of the valve stem  5   a  of the air valve  5 . Further, an operation plate  26  bent in an approximate S-shape is in tiltably contact with the rear of the operation stick  22 , and the needle  3  is inserted through an intermediate part of the operation plate  26 . The end of the needle chuck  9  is in contact with the rear surface of the operation plate  26 . 
   To blow the paint, the operation button  23  is depressed to blow the compressed air from the nozzle member  2 , then the operation stick  22 , with the operation button  23 , is pulled rearward, to be tilted rearward with the pivot member  24  as a support point by a necessary amount. In correspondence with the tilting of the operation stick  22 , the operation plate  13  is also tilted, and the needle chuck  9  holding the needle  3  is withdrawn. When the needle  3  is withdrawn, the paint is supplied by the amount in proportion to the amount of withdrawal to the nozzle  2   a , and is blown out and sprayed from the nozzle member  2 . 
   In the air brush A 2  having the above structure, as in the case of the previously-described air brush A, when the screw connection member  8  is removed, the internal space  14  in the air brush main body  1  is opened, then the operation stick  22  and the operation plate  26  are removed, and the removal of the stopper  17 , cleaning and grease-up of the insertion part of the push stick  25  can be freely performed. 
   Note that the needle chuck  9  of the air brush A and A 2  is unrotatable but withdrawable in the axial direction by a fit engagement relation between the fit-insertion member  9   c  having a regular hexagonal cross-sectional shape and the insertion hole  8   b  through which the fit-insertion member is fit-inserted. The cross-sectional shape of the fit-insertion member  9   c  and the insertion hole  8   b  is preferably a regular hexagonal shape in consideration of stability upon processing and sliding. However, the cross-sectional shape is not limited to this shape. Similar operation can be performed even when the cross-sectional shape is other regular polygonal shapes such as regular pentagonal shape or regular octagonal shape, or regular triangular shape or square shape. Further, it may be arranged such that the fit-insertion member of the needle chuck is spline-engaged or an existing guide mechanism is provided thereby the needle chuck is supported unrotatably but slidably in the axial direction. 
   Further, the shape of the tail case connected with the rear part of the air brush main body  1  may be arbitrarily changed. Further, an adjusting screw to regulate a needle withdrawal position may be provided at the rear end of the tail case. 
   Having described specific preferred embodiments of the invention with reference to the accompanying drawings, it will be appreciated that the present invention is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one of ordinary skill in the art without departing from the scope of the invention as defined by the appended claims.