Patent Publication Number: US-9885132-B2

Title: Compressed air supplying device of a sewing machine

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims the benefit of priority to Japanese Patent Application No. 2014-246770 filed on Dec. 5, 2014, the content of which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a compressed air supplying device of a sewing machine used in a looper threading device of an overlock sewing machine. 
     BACKGROUND ART 
     An overlock sewing machine is provided with a plurality of loopers, and since it is necessary to thread each of the loopers with respectively different looper threads, threading operations were troublesome. 
     Patent Literature 1 discloses a device for threading a thread to a hollow looper point using compressed air. 
     In the above conventional device, when compressed air is sent to a thread path, a lever is manually pushed down for pushing a piston of an air pump in. Then, operations of the lever are directly linked with movements of the piston, so that the changes in lever operations have a direct effect on the movements of the piston. Namely, the velocities for pushing the piston differ with the forces for pushing down the lever. Accordingly, the flow velocities of compressed air were different depending on operations, so that there are some cases in which threads are not be delivered up to the looper points. 
     PRIOR ART LITERATURE 
     Patent Literature 
     [Patent Literature 1] Japanese Patent Laid-Open Publication No. 1994-277383 
     SUMMARY OF THE INVENTION 
     One or more embodiments of the present invention provide a compressed air supplying device of a sewing machine capable of supplying compressed air stably irrespective of operation manners of users. 
     Embodiment (1) 
     One or more embodiments of the present invention provide a compressed air supplying device of a sewing machine comprising an air pump portion including a piston; a piston biasing portion for biasing force to the piston in the direction which the air pump exhausts air, and for driving the piston in the exhaust air direction, by applying biasing force; 
     an operating member for making the air pump portion to perform intake air; and an operating force transmitting mechanism transmitting operating force of the operating member to the piston for actuating the piston only in an intake air direction in which the air pump portion intakes air against the biasing force of the piston biasing portion by the operating force. 
     Embodiment (2) 
     One or more embodiments of the present invention provide a compressed air supplying device of a sewing machine wherein in the compressed air supplying device of a sewing machine according to Embodiment (1), the operating member is a lever-like member capable of performing reciprocating movements, and wherein the operating force transmitting mechanism constitutes a ratchet mechanism outputting only rotations in one direction from among rotations generated by reciprocating movements of the operating member. 
     Embodiment (3) 
     One or more embodiments of the present invention provide a compressed air supplying device of a sewing machine wherein the compressed air supplying device of a sewing machine according to Embodiment (2) comprises; driving arm portion being swingably connected to the piston, and a piston returning arm portion provided to be swingably and integrally with the driving arm portion and being rotationally moved by means of a cam portion provided at the operating force transmitting mechanism in a direction in which the piston moves in the intake air direction, wherein the piston biasing portion applies biasing force to the piston by means of the piston driving shaft portion and, wherein when the operating member is operated in a specified direction, the piston returning arm portion is moved by the cam portion to move the piston in the intake air direction up to a specified position, and when the specified position is exceeded, engagement between the cam portion and the piston returning arm portion ( 18 ) is released such that the piston is driven in the exhaust air direction by the biasing force of the piston biasing portion. 
     According to one or more embodiments of the present invention, the compressed air supplying device of a sewing machine is capable of supplying compressed air stably manner irrespective of operation manners of users. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  A view of a showing an embodiment of a compressed air supplying device of a sewing machine according to one or more embodiments of the present invention. 
         FIG. 2  An exploded perspective view of the compressed air supplying device. 
         FIG. 3  A sectional view of an intake air opening  32  at the time of intake. 
         FIG. 4  A sectional view of an exhaust air opening  31  at the time of intake air. 
         FIG. 5  A sectional view of the exhaust air opening  31  at the time of exhaust air. 
         FIG. 6  A sectional view of the intake air opening  32  at the time of exhaust air. 
         FIG. 7  A view showing a stopped state of a lever  20  in which threading operations are completed by abutting a bottom dead center of a movable range of the lever  20 . 
         FIG. 8  A sectional view showing engaging portions between tooth portions  20   b  and tooth portions  21   a  in the state of  FIG. 7  in developed form along a peripheral direction. 
         FIG. 9  A view showing a state for preparing driving of the lever  20  for performing threading operations. 
         FIG. 10  A sectional view showing an engaging portion between one tooth portion  20   b  and one tooth portion  21   a  in the state of  FIG. 9  in developed form along a peripheral direction. 
         FIG. 11  A view showing a state in which driving has further proceeded from the state of  FIG. 10 . 
         FIG. 12  A view showing a state in which driving of the lever  20  is possible for performing threading operations. 
         FIG. 13  A sectional view showing engaging portions between tooth portions  20   b  and tooth portions  21   a  in the state of  FIG. 12  in developed form along a peripheral direction. 
         FIG. 14  A view for explaining operations of the lever  20  and a piston  4 . 
         FIG. 15  A view for explaining operations of the lever  20  and the piston  4 . 
         FIG. 16  A view for explaining operations of the lever  20  and the piston  4 . 
         FIG. 17  A view for explaining operations of the lever  20  and the piston  4 . 
         FIG. 18  A view for explaining operations of the lever  20  and the piston  4 . 
         FIG. 19  A view for explaining operations of the lever  20  and the piston  4 . 
     
    
    
     DETAILED DESCRIPTION 
     An example for carrying out the present invention will now be explained with reference to the drawings and others. 
     Embodiment 
       FIG. 1  is a view of a showing an embodiment of a compressed air supplying device of a sewing machine according to the present invention. 
       FIG. 2  is an exploded perspective view of the compressed air supplying device. 
     Each of the drawings indicated hereinafter including  FIG. 1  and  FIG. 2  are schematically illustrated drawings, and sizes and shapes of respective portions are shown in suitably exaggerated form for ease of understanding. 
     Further, while explanations are made upon indicating specific numerical values, shapes and materials in the following explanations, they may be suitably changed. 
     Moreover, for ease of understanding and for convenience sake, explanations will be made by suitably using the directions of left, right, up and down as indicated by arrows in  FIG. 1 . However, these directions are not to limit the arrangement of the invention. 
     The compressed air supplying device according to the present embodiment is assembled in a sewing machine main body (not shown) or a unit base  1 . 
     An air pump unit (air pump portion)  2  is comprised of an air pump  3  and a piston  4 , wherein an outer peripheral surface  4   a  of the piston  4  fitting with an inner peripheral surface  3   a  of the air pump  3  is formed with a groove  4   b  into which an O ring  5  is fit. The air pump unit  2  generates compressed air through reciprocating movements of the piston  4  within the air pump  3 . 
     The O ring  5  prevents leakage of air from a sliding surface between the inner peripheral surface  3   a  of the air pump  3  and the outer peripheral surface of the piston  4  during reciprocating movements of the piston  4 . 
     The air pump  3  includes a through hole  3   d  on an upper end thereof and by inserting a bush  9 , it is held to be swingably with respect to an air pump mounting plate  11  by means of a screw  10 . 
     The air pump  3  includes an exhaust air opening  31  and an intake air opening  32 , wherein a check valve  7  accommodating a small ball  6  is screw-coupled to the exhaust air opening  31 . A check valve  8  similarly accommodating a small ball  6  is screw-coupled to the intake air opening  32 . 
     A tube  12  is arranged in that one end  12   a  is coupled to the check valve  7  while the other end  12   b  is coupled to an inlet of a thread delivering mechanism (not shown). Accordingly, compressed air generated by the air pump unit  2  is introduced through the tube  12  to the thread delivering mechanism. 
     The check valve  7  and the check valve  8  restrict intake air actions and exhaust air actions of the air pump  3 , and when the air pump  3  performs intake air and exhaust air in accordance with reciprocating movements of the piston  4 , the exhaust air is directed only towards the thread delivering mechanism side while intake air is not performed from the thread delivering mechanism side. 
       FIG. 3  is a sectional view of the intake air opening  32  at the time of intake air. 
     At the time of intake air, the small ball  6  inserted into the check valve  8  screw-fastened to the intake air opening  32  of the air pump  3  is sucked in a depth direction of the intake air opening  32  with the descending of the piston  4 , abuts a rib  32   a  and is stopped thereat. At this time, outside air passes through a clearance  32   b  and flows into the air pump  3 . 
       FIG. 4  is a sectional view of the exhaust air opening  31  at the time of intake air. 
     In the exhaust air opening  31  at the time of intake air, the small ball  6  inserted into the check valve  7  screw-fastened to the exhaust air opening  31  is sucked in a depth direction of the exhaust air opening  31  with the descending of the piston  4  and is stopped at an exhaust air opening seat surface  31   a  to prevent inflow of outside air. The check valve  7  has the tube  12  coupled to its other end and communicates with the thread delivering mechanism by means of the tube  12 , so that the actions of sucking air from the thread delivering mechanism will not be generated when the piston  4  descends. Namely, the flow of air which pulls a thread inserted into the thread delivering mechanism back will not be generated at the time of intake air. 
       FIG. 5  is a sectional view of the exhaust air opening  31  at the time of exhaust air. 
     Next, at the time of exhaust air, the small ball  6  of the exhaust air opening  31  is pushed out in the direction of the check valve  7  with the ascending of the piston  4 , abuts a rib  7   a  of the check valve  7  and is stopped thereat. At this time, air within the air pump  3  passes through a clearance  7   b  and is exhausted to the exterior. As the check valve  7  communicates with the thread delivering mechanism by means of the tube  12 , the air within the air pump  3  flows into the thread delivering mechanism. 
       FIG. 6  is a sectional view of the intake air opening  32  at the time of exhaust air. 
     In the intake air opening  32  at the time of exhausting air, the small ball  6  of the intake air opening  32  is pushed out in the direction of the check valve  8  with the ascending of the piston  4  and is stopped at an intake air opening seat surface  8   a  of the check valve  8  to prevent outflow of the air within the air pump  3 . 
     In this manner, the outside air flows in only from the intake air opening  32  at the time of descending of the piston  4 , while the air within the air pump  3  is exhausted only from the exhaust air opening  31  at the time of ascending of the piston  4 . 
     Returning to  FIG. 1  and  FIG. 2 , a piston connecting plate  13  is mounted to a lower end of the piston  4  to be swingably with respect to the piston  4 . More specifically, a through hole  4   c  is provided at the lower end of the piston  4  wherein the bush  9  is inserted into the through hole  4   c  and the piston  4  is mounted to one end of the piston connecting plate  13  in a swingable manner by using a screw  10 . A receiving portion  13   a  is formed at the other end of the piston connecting plate  13 , and one end of a piston driving shaft  14  is fixed thereto by means of a screw  15 . With this arrangement, the piston connecting plate  13  is provided to rotate integrally with the piston driving shaft  14 , connects the piston  4  and the piston driving shaft  14 , and transmits rotation of the piston driving shaft  14  to the piston  4  as reciprocating movements of the piston  4 . 
     The piston driving shaft  14  is held at the sewing machine main body or the unit base  1  in a freely rotatable manner. The piston driving shaft  14  fixes the piston connecting plate  13 , a piston driving arm  16  and a piston returning arm  18  on the shaft. The piston driving shaft  14 , the piston connecting plate  13 , the piston driving arm  16  and the piston returning arm  18  are integrated as a piston driving shaft portion and are swingably with the center being the piston driving shaft  14 . 
     The piston driving arm  16  is fixed to an intermediate portion of the piston driving shaft  14 . A spring peg  16   a  is provided at one end of the piston driving arm  16  while a stopper driving surface  16   b  is formed at the other end thereof. One end of the piston receiving spring  17  engages with the spring peg  16   a , and the other end of the piston driving spring  17  is held at a suitable position of the sewing machine main body. With this arrangement, the piston driving shaft  14  is continuously biased in a counterclockwise direction (when seen from the right-side surface of the sewing machine). Accordingly, the piston  4  is continuously biased by the piston driving shaft  14  and the piston connecting plate  13  in the ascending direction, namely in the direction in which the air pump unit  2  performs exhaust air. 
     The piston driving spring (piston biasing portion)  17  is engaged with the spring peg  16   a  of the piston driving arm  16  and functions as a power source for pushing the piston  4  into the air pump  3 . 
     The piston driving arm  16  is fixed to the piston driving shaft  14  and rotates with the piston driving shaft  14  as the center. The piston driving shaft  16  engages with the piston driving spring  17  by including the spring peg  16   a  at one end thereof. And, its biasing force make to rotate the piston driving shaft  14 , so that movements of pushing the piston  4  perform. 
     The piston connecting plate  13  and the piston driving arm  16  have functions as a driving arm portion for transmitting the biasing force of the piston driving spring (piston biasing portion)  17  to the piston  4 . The piston connecting plate  13  and the piston driving arm  16  might be comprised by different parts as in the present embodiment, and it is also possible to integrate and comprise them as a single part. 
     The piston returning arm (piston returning arm portion)  18  is fixed to the piston driving shaft  14  and transmits movements of the lever  20  to the piston driving shaft  14 . By transmitting movements of the lever  20  to the piston driving shaft  14 , the piston returning arm  18  returns the piston  4  from the pushed in state to the intake air state. After the piston returning arm  18  is pushed up clockwise (when seen from the right-side surface), by a lead cam surface (cam portion)  21   b  of an intermediate arm  21  to be described later, is detached from the lead cam surface  21   b  to rotate counterclockwise (when seen from the right-side surface) at once. Accordingly, the piston returning arm  18  pushes the piston  4  in, thereby changes the air pump  3  into the exhaust air state. 
     A lever shaft  19  is held at the sewing machine main body or unit base  1  in a freely rotatable manner. The lever  20  is inserted into a right end of the lever shaft  19  while the intermediate arm  21  is inserted to the left side thereof in a freely rotatable manner, and an intermediate arm spring  22  is fitted to the left end of the lever shaft  19  so as to bias the intermediate arm  21  in the direction of the lever  20 . 
     The intermediate arm  21  is a member held at the lever shaft  19  in a freely rotatable manner for transmitting power from the lever  20  to the piston returning arm  18 . The intermediate arm  21  also rotates the piston returning arm  18  by means of the lead cam surface  21   b.    
     Moreover, the intermediate arm  21  is ratchet-coupled to the lever  20 . As the lever  20  is rotated counterclockwise when seen from the right-side surface of the sewing machine, the intermediate arm  21  rotates counterclockwise (when seen from the right side) fitting with the lever  20  at a first fitting phase. With this arrangement, the piston returning arm  18  is rotated in a returning direction. On the other hand, when the lever  20  is rotated clockwise (when seen from the right side), the intermediate arm  21  is displaced to the left side against the intermediate arm spring  22 . Next, when the lever  20  has rotated in a second fitting phase, the intermediate arm  21  returns to the right side by means of the biasing force of the intermediate arm spring  22 . 
     In ratchet-coupling of the lever  20  and the intermediate arm  21 , the intermediate arm spring  22  allows that the intermediate arm  21  displaces in lateral directions on the lever shaft  19  by means of biasing the intermediate arm  21  to the lever  20  side continuously. 
     The lever  20  is an operating member held at the right end of the lever shaft  19  in a freely rotatable manner for making the air pump unit  2  perform intake air by a user&#39;s operation. The lever  20  is ratchet-coupled to the intermediate arm  21  on the lever shaft  19 . The lever  20  also allow that the piston  4  change from intake air movement to exhaust air movement by performing a single reciprocating of clockwise and counterclockwise (when seen from the right side). 
     A lever stopper  1   a  is a pin for stably holding the lever  20  at a terminating position of counterclockwise operations (when seen from the right side), and at the time of the completion of exhaust air by means of operating the lever  20 . An arm portion hook  20   a  which integrally formed with the lever  20  comes into contact with the lever stopper  1   a.    
     A ratchet mechanism formed by the lever  20 , the intermediate arm  21  and the intermediate arm spring  22  allow to output only one direction of rotation from among rotations generated through reciprocating swinging of the lever  20 . An operating force transmitting mechanism is constituted by the lever  20 , the intermediate arm  21 , the intermediate arm spring  22 , the piston returning arm  18 , the piston driving shaft  14 , the piston driving arm  16  and the piston connecting plate  13 . The operating force transmitting mechanism transmits the operating force to piston  4  against the biasing force of the piston driving spring (piston biasing portion)  17  by means of operating force of the lever (operating portion)  20  so that the air pump unit (air pump portion)  2  allow to actuate the piston  4  only in the intake air direction. 
     Movements of the ratchet-coupled portion between the lever  20  and the intermediate arm  21  will be explained here. 
       FIG. 7  is a view showing a stopped state of the lever  20  in which threading operations are completed by abutting a bottom dead center of a movable range of the lever  20 . 
       FIG. 8  is a sectional view showing engaging portions between tooth portions  20   b  and tooth portions  21   a  in the state of  FIG. 7  in developed form along a peripheral direction. 
     The states of  FIG. 7  and  FIG. 8  show a bottom dead center of a movable range of the lever  20 . Figs also show that the arm portion hook  20   a  of the lever  20  upon completion of threading operations is held by means of coming into contact with lever stopper  1   a  of the unit base  1 . In this state, the tooth portions  20   b  of the lever  20  engage with the tooth portions  21   a  of the intermediate arm  21 , and the intermediate arm  21  is biased towards the lever  20  side by means of the intermediate arm spring  22 . 
       FIG. 9  is a view showing a state for preparing driving of the lever  20  for performing threading operations. 
       FIG. 10  is a sectional view showing an engaging portion between one tooth portion  20   b  and one tooth portion  21   a  in the state of  FIG. 9  in developed form along a peripheral direction. 
       FIG. 11  is a view showing a state in which driving has further proceeded from the state of  FIG. 10 . 
       FIG. 9  to  FIG. 11  show that the lever  20  is rotating in a direction of arrow C shown in  FIG. 1 .  FIG. 10  shows that a sloped surface of one tooth portion  20   b  of the lever  20  is climbing up a sloped surface of one tooth portion  21   a  of the intermediate portion  21 . In this state, the intermediate arm  21  is pushed by the lever  20 , so that it is pushed out to the left side against the intermediate arm spring  22 . When the lever  20  is further kept rotating in the direction of arrow C, it will be in the state shown in  FIG. 11 , so that the tooth portion  20   b  of the lever  20  finishes climbing of the tooth portion  21   a  of the intermediate arm  21  to engage the next tooth portion of the intermediate arm  21 . 
       FIG. 12  is a view showing a state in which driving of the lever  20  is possible for performing threading operations. 
       FIG. 13  is a sectional view showing engaging portions between tooth portions  20   b  and tooth portions  21   a  in the state of  FIG. 12  in developed form along a peripheral direction. 
       FIG. 12  and  FIG. 13  show the state that the lever  20  is possible for performing threading operations as the preparations are completed. In this state, one tooth portion  20   b  of the lever  20  meshes with a tooth of a next step of the tooth portions  21   a  of the intermediate arm  21  again, after that, the intermediate arm  21  repeatedly moves to the lever  20  side by the intermediate arm spring  22 , whence the lever  20  can be rotated in the direction of arrow D in  FIG. 1 . As the tooth portions  20   b  of the lever  20  and the tooth portions  21   a  of the intermediate arm  21  fit with each other and the lever  20  is rotated in the direction of arrow D, the intermediate arm  21  rotates in the counterclockwise direction (when seen from the right side of the sewing machine). 
     Next, behaviors of the piston  4  accompanying driving of the lever  20  for threading operations will be explained. 
       FIG. 14  to  FIG. 19  are views for explaining operations of the lever  20  and the piston  4 . In these drawings, it is assumed that movements proceed from the state of  FIG. 14  to that of  FIG. 19  in the order of the drawings. 
     At a point of time in which rotation of the lever  20  is started from the state of  FIG. 12  and  FIG. 13  in the direction of arrow D in  FIG. 1 , the tip of the piston returning arm  18  comes into contact with a minimum diameter portion of the lead cam surface  21   b  of the intermediate arm  21  as shown in  FIG. 14 . On the other hand, as the piston driving arm  16  is biased counterclockwise in the drawing by the piston driving spring  17 , the piston driving arm  16  stops by means of coming into contact with a piston driving arm stopper  23 . Exhaust air movement strokes of the piston  4  are restricted by the piston driving arm stopper  23 . 
     When movements shift from the state of  FIG. 14  to the state of  FIG. 15 , the lever  20  is rotated to push the tip of the piston returning arm  18  up to an intermediate diameter portion of the lead cam surface  21   b  of the intermediate arm  21  against the piston driving spring  17 . With this arrangement, as the piston  4  descends, the air pump  3  intakes air. 
     When movements shift from the state of  FIG. 15  to the state of  FIG. 16 , as the lever  20  is further rotated, the tip of the piston returning arm  18  reaches a maximum diameter portion of the lead cam surface  21   b  of the intermediate arm  21 . With this arrangement, as the piston  4  reaches a lowest point, the air pump  3  also reaches a maximum intake air state. 
     When movements shift from the state of  FIG. 16  to the state of  FIG. 17 , in the moment the lever  20  moves slightly from the state of  FIG. 16 , the tip of the piston return arm  18  drops from the lead cam surface  21   b  of the intermediate arm  21 , and falls to the minimum diameter portion of the next lead cam surface at once by the biasing force of the piston driving spring  17 . With this arrangement, as the piston  4  is also ascended at once, the air pump  3  exhausts air within the air pump  3  at a stroke. Namely, as compressed air flows into the thread delivering mechanism at once, it is possible to deliver the thread. 
       FIG. 18  shows that the lever  20  is rotated in the direction of arrow C in  FIG. 1  for the next threading operations, so that the tooth portions  20   b  of the lever  20  are engage with the next tooth portions  21   a  of the intermediate arm  21 . As the tip of the piston returning arm  18  come into contact with a rear surface  21   d  of the intermediate arm  21  to prevent rotation of the intermediate arm  21 , thereby clutch coupling between the lever  20  and the intermediate arm  21  is performed smoothly. This corresponds to the states of  FIG. 12  and  FIG. 13 . 
       FIG. 19  shows that rotation of the lever  20  is reversed from the state of  FIG. 18  to move slightly in the direction of arrow D in  FIG. 1 , thereby a tip  20   c  of the lever  20  comes into contact with the tip  21   c  of the intermediate arm  21 . On the other hand, the tip of the piston returning arm  18  come into contact with the minimum diameter portion of the lead cam surface  21   b  of the intermediate arm  21 . Namely, it means that the state go back to the state of  FIG. 14 , so that it has become possible to perform the next threading operations. 
     As explained above, according to the present embodiment, the compressed air supplying device make possible to drive the air pump unit at constant driving force by operating a manual lever without using a compressor or a motor or the like at low cost. Accordingly, the compressed air supplying device of the present embodiment become possible to supply compressed air stably irrespective of operation manners of users. 
     Moreover, the compressed air supplying device of the present embodiment can be comfortably used with no driving sounds caused by the use of an electric motor or the like. 
     Modified Embodiment 
     As the present invention is not limited to the above-described embodiment, various modifications and changes of the embodiment are included in the scope of the present invention. 
     The present embodiment has been explained by giving an example in which a ratchet mechanism is used for transmitting only operations in one direction of the lever  20  to the piston  4 . The present invention is not limited to this, and any mechanism can be used even if only operations in one direction of the operating member can be transmitted to the piston. For instance, it is possible to apply a mechanism of a known one-way clutch. 
     Further, the present embodiment has been explained by giving an example of a compressed air supplying device using the swingably-operated lever  20  as an operating member. The present invention is not limited to this, and it is, for instance, possible to use a rotationally-operated operating member in the compressed air supplying device. 
     Further, the present embodiment has been explained by giving an example of a compressed air supplying device using the manually-operated lever  20  as an operating member. The present invention is not limited to this, and it is, for instance, possible to apply an electric motor-operated operating member using a motor or solenoid or the like to the present invention. In a case of using electric motor-operated, the compressed air supplying device makes possible to supply stably compressed air by biasing the piston  4  in the exhaust air direction using spring force, with a simple structure. 
     In this respect, the present invention is not to be limited by the above-explained embodiments. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
           1  Unit base 
           1   a  Lever stopper 
           2  Air pump unit 
           3  Air pump 
           3   a  Inner peripheral surface 
           3   d  Through hole 
           4  Piston 
           4   a  Outer peripheral surface 
           4   b  Groove 
           4   c  Through hole 
           5  O ring 
           6  Small ball 
           7  Check valve 
           7   a  Rib 
           7   b  Clearance 
           8  Check valve 
           8   a  Intake air opening seat surface 
           9  Bush 
           10  Screw 
           11  Air pump mounting plate 
           12  Tube 
           12   a  One end 
           12   b  Other end 
           13  Piston connecting plate 
           13   a  Receiving portion 
           14  Piston driving shaft 
           15  Screw 
           16  Piston driving arm 
           16   a  Spring peg 
           16   b  Stopper receiving surface 
           17  Piston driving spring 
           18  Piston returning arm 
           19  Lever shaft 
           20  Lever 
           20   a  Arm portion hook 
           20   b  Tooth portion 
           20   c  Tip 
           21  Intermediate arm 
           21   a  Tooth portion 
           21   b  Lead cam surface 
           21   c  Tip 
           21   d  Rear surface 
           22  Intermediate arm spring 
           23  Piston driving arm stopper 
           31  Exhaust air opening 
           31   a  Exhaust air opening seat surface 
           32  Intake air opening 
           32   a  Rib 
           32   b  Clearance