Abstract:
A diaphragm pump includes a motor having a recess in an outer circumferential portion, a crank which rotates together with a motor output shaft, a driving member including a driving element which reciprocates in accordance with the crank rotation, and a diaphragm which forms a pump chamber which expands and contracts in accordance with the reciprocating driving element. The pump also includes a suction passage which draws a fluid into the pump chamber, a discharge passage which discharges the fluid, a suction valve formed in the suction passage to regulate a reverse flow of the fluid to the suction passage, a discharge valve formed in the discharge passage to regulate a reverse flow of the fluid to the pump chamber, and an elastically deformable cylindrical member which holds the diaphragm and includes a projection which engages with the recess of the motor.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a diaphragm pump for pressurizing or depressurizing a fluid with respect to, e.g., a sphygmomanometer or home appliance. 
         [0002]    As disclosed in Japanese Patent Laid-Open No. 2004-197571, a conventional diaphragm pump includes a motor mounted on the bottom portion of a mounter, a crank axially fixed to the output shaft of the motor, which protrudes into the mounter, a driving shaft having one end portion fixed in an inclined state to a portion of the crank, which is shifted from the output shaft, a driving member including a driving element which has a central portion pivotally supported by the other end portion of the driving shaft and swings as the driving shaft rotates, and a diaphragm having a diaphragm portion that is attached to the driving element of the driving member and forms a pump chamber. In this arrangement, the crank rotates when the motor is driven, and the driving shaft rotates while changing the inclining direction. Consequently, the driving element swings and causes the pump chamber to perform an expanding/contracting operation, thereby performing a pumping action. 
         [0003]    In the conventional diaphragm pump as described above, the motor is fixed by screws to the bottom portion of the mounter. Since the screws for fixing are necessary, the number of parts cannot be reduced. Also, it is difficult to automate the mounting work because the motor is mounted on the mounter by screw fastening. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the present invention to provide a diaphragm pump capable of reducing the number of parts. 
         [0005]    It is another object of the present invention to provide a diaphragm pump capable of readily introducing automatic assembly when mounting a motor. 
         [0006]    To achieve the above objects of the present invention, there is provided a diaphragm pump comprising a motor having a recess in an outer circumferential portion, a crank which rotates together with an output shaft of the motor, a driving member including a driving element which reciprocates in accordance with the rotation of the crank, a diaphragm which forms a pump chamber which expands and contracts in accordance with the reciprocal motion of the driving element of the driving member, a suction passage which draws a fluid into the pump chamber, a discharge passage which discharges the fluid from the pump chamber, a suction valve formed in the suction passage to regulate a reverse flow of the fluid from the pump chamber to the suction passage, a discharge valve formed in the discharge passage to regulate a reverse flow of the fluid from the discharge passage to the pump chamber, and an elastically deformable cylindrical member which holds the diaphragm and includes a projection which engages with the recess of the motor. 
         [0007]    In the present invention, a motor can be mounted on a mounter by fitting the motor in the mounter, and engaging a projection with a recess while elastically deforming the mounter. This obviates the need for screws for mounting the motor on the mounter. Also, the motor can be mounted on the mounter by almost linearly moving the motor along the axial direction of the mounter while the motor is fitted in the mounter. This facilitates introducing automatic assembly when mounting the motor. 
         [0008]    In addition, the projection engages with the recess when the ceiling portion of the motor abuts against an abutting surface after the motor is fitted in the mounter. This makes mounting of the motor reliable and easy, and also facilitates introducing automated assembly when mounting the motor. 
         [0009]    Furthermore, it is possible to use a recess formed simultaneously with the formation of an abutting portion for locking a permanent magnet when attaching the permanent magnet to a yoke. This obviates the need for a new work for forming the recess in the motor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a sectional view of a diaphragm pump according to the first embodiment of the present invention; 
           [0011]      FIG. 2  is an enlarged sectional view of a motor shown in  FIG. 1 ; 
           [0012]      FIG. 3A  is a perspective view of a mounter viewed from the bottom surface side in  FIG. 1 , and  FIG. 3B  is a bottom view of the mounter shown in  FIG. 1 ; 
           [0013]      FIG. 4  is a sectional view of a diaphragm pump according to the second embodiment of the present invention; 
           [0014]      FIG. 5  is a sectional view of a diaphragm pump according to the third embodiment of the present invention; 
           [0015]      FIG. 6  is a sectional view of a motor shown in  FIG. 5 ; 
           [0016]      FIG. 7  is a sectional view of a diaphragm holder shown in  FIG. 5 ; and 
           [0017]      FIG. 8  is a sectional view of a diaphragm pump according to the fourth embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The present invention will be explained in detail below with reference to the accompanying drawings. Note that “upper” and “lower” used to explain directions in this specification indicate directions in the drawings for the convenience of explanation, and do not necessarily match “upper” and “lower” when actually using a diaphragm pump according to the present invention. 
       First Embodiment 
       [0019]    First, the first embodiment of the present invention will be explained with reference to  FIGS. 1 to 3B . As shown in  FIG. 1 , a diaphragm pump  1  according to this embodiment includes a motor  2  as a driving source having a circular planar shape. As shown in  FIG. 2 , the motor  2  includes a motor housing  5  including a cap-like yoke  3  having an open lower end and a bottom plate  4  for closing the opening of the yoke  3 . A plurality of recesses  7  are formed in the circumferential direction in the outer circumferential surface of the upper portion of the cylinder of the yoke  3 , at the same time an abutting portion  3   a  is formed toward the inside of the yoke  3  by indenting. The plurality of recesses  7  are formed in the same position in the direction of an arrow A (in the direction of the height in the drawings). A permanent magnet  6  is attached to the inner circumferential surface of the yoke  3 . The permanent magnetic  6  is pressed in the yoke  3  from below, and attached to a predetermined position of the yoke  3  when the abutting portion  3   a  locks an upper end face  6   a.    
         [0020]    An output shaft  8  is rotatably supported by a bearing  9  fixed to an opening formed in the center of the ceiling of the yoke  3 , and a bearing  10  fixed to the center of the bottom plate  4 . A thrust receiver  4   a  for closing the bearing hole of the bearing  10  and locking a non-driving end  8   a  of the output shaft  8  is formed in the center of the bottom plate  4 , and a driving end portion  8   b  of the output shaft  8  projects upward from the bearing  9 . A rotor  12  facing the permanent magnet  6  at a predetermined distance is axially fixed to the central portion of the output shaft  8 , and a rectifier  13  is axially fixed below the rotor  12 . 
         [0021]    In  FIG. 1 , reference numeral  15  denotes a mounter formed by a resin into an almost closed-bottom cylindrical shape having an open upper end and including a bottom portion  15   a  and cylindrical portion  15   b.  A shaft hole  15   c  is formed in the center of the bottom portion  15   a.  As shown  FIG. 3A , the mounter  15  is integrated with a cylindrical motor holder  16  extended from the bottom portion  15   a  to the opposite side, having the same diameter as that of the cylindrical portion  15   b,  and having an open lower end. 
         [0022]    The inner diameter of the motor holder  16  is made slightly larger than the outer diameter of the motor  2 . On the inner circumferential surface of the motor holder  16 , a plurality of projections  16   a  with which the recesses  7  of the motor  2  described above engage are formed in the direction of the center (the radial direction) of the motor holder  16 . When the motor  2  is fitted in as will be described later, the motor holder  16  elastically deforms when the recesses  7  engage with the projections  16   a.    
         [0023]    A distance D (see  FIG. 3A ) between the projection  16   a  and a lower surface  15   d  as the abutting surface of the bottom portion  15   a  is set equal to a distance D (see  FIG. 2 ) between the recess  7  and a ceiling portion  3   b  of the yoke  3  of the motor  2 . As will be described later, therefore, when the motor  2  is fitted in the motor holder  16  and the ceiling portion  3   b  of the motor  2  abuts against the lower surface  15   d  of the bottom portion  15   a  of the mounter  15  (the ceiling surface of the motor holder  16 ), the recesses  7  of the motor  2  engage with the projections  16   a  of the motor holder  16 . 
         [0024]    As shown in  FIGS. 3A and 3B , three grooves  17  vertically extending at an equal angle (120°) in the circumferential direction are formed in the cylindrical portion  15   b  of the mounter  15  so as to extend to the motor holder  16 . Since the three grooves  17  divide the motor holder  16  into tree portions in the circumferential direction, the motor holder  16  readily elastically deforms when the recesses  7  engage with the projections  16   a.    
         [0025]    In  FIG. 1 , reference numeral  20  denotes a crank formed into an almost columnar shape. The driving end portion  8   b  of the output shaft  8  of the motor  2  is fixed to the central portion of the crank  20 , so the crank  20  rotates together with the output shaft  8 . A driving shaft  21  includes a lower end portion attached in an inclined state to a portion off-centered from the portion of the crank  20  to which the driving end portion  8   b  is attached. 
         [0026]    Reference numeral  23  denotes a driving member having a non-through hole  23   a  in the center. Three driving elements  23   b  (two driving elements  23   b  are not shown) projecting in a direction perpendicular to the non-through hole  23   a  are formed integrally with the upper end portion of the driving member  23  at an equal angle (120°) in the circumferential direction in a plane. The driving elements  23   b  are slightly inclined downward at the same angle toward swinging end portions, and each swinging end portion has a diaphragm mounting hole  23   c.    
         [0027]    The driving member  23  is rotatably supported by the driving shaft  21  by inserting the upper portion of the driving shaft  21  into the non-through hole  23   a.  When the crank  20  is rotated by driving the motor  2 , the driving shaft  21  rotates while changing the inclining direction, and the swinging end portions of the three driving elements  23   b  sequentially vertically swing via the driving shaft  21 . 
         [0028]    Reference numeral  25  denotes a diaphragm holder formed into an inverse closed-bottom cylindrical shape. Three holding cylinders  25   a  formed into a cylindrical shape are formed integrally with the ceiling portion of the diaphragm holder  25  at an equal angle (120°) in the circumferential direction. 
         [0029]    Reference numeral  26  denotes a diaphragm formed into an almost disc shape by a flexible material such as rubber. Three thin-wall diaphragm portions  26   a  are formed at an equal angle (120°) in the circumferential direction. A piston portion  26   b  is formed integrally with the lower portion of each diaphragm portion  26   a,  and a small-diameter portion  26   c  is formed integrally with the lower end of the piston portion  26   b.    
         [0030]    Reference numeral  27  denotes a valve holder formed into an almost disc shape. A cylindrical portion  27   a  integrally stands on the outer periphery of the valve holder  27 , and three suction holes  27   b  (two suction holes  27   b  are not shown) as suction passages are formed in the inner periphery of the cylindrical portion  27   a  at an equal angle (120°) in the circumferential direction. An engaging projecting portion  27   c  integrally stands on the central portion of the valve holder  27 . Around the engaging projecting portion  27   c,  three discharge holes  27   d  (two discharge holes  27   d  are not shown) as discharge passages are formed at an equal angle (120°) in the circumferential direction, and a partition wall  27   e  concentrically stands integrally with the cylindrical portion  27   a.    
         [0031]    In  FIG. 1 , reference numeral  28  denotes an umbrella-shaped suction valve for opening and closing the suction hole  27   b.  The suction valve  28  regulates the reverse flow of a fluid from a pump chamber  32  (to be described later) to the suction hole  27   b.  Reference numeral  29  denotes a hat-shaped discharge valve that is attached to the engaging projecting portion  27   c  and opens and closes the discharge hole  27   d.  The discharge valve  29  regulates the reverse flow of a fluid from a discharge port  30   c  (to be described later) to the pump chamber  32 . 
         [0032]    Reference numeral  30  denotes a lid formed into an inverse closed-bottom cylindrical shape. A cylindrical portion  30   a  integrally projects downward from the outer periphery, and a partition wall  30   b  having a ring-like planar shape concentric with the cylindrical portion  30   a  integrally projects downward from the central portion. A discharge cylindrical portion  30   d  having the discharge port  30   c  integrally stands from the central portion of the ceiling portion of the lid  30 . A suction cylindrical portion  30   f  having a suction port  30   e  integrally stands on a portion of the periphery of the ceiling portion. 
         [0033]    Next, a method of assembling the diaphragm pump arranged as described above will be explained. Referring to  FIG. 1 , the suction valve  28  is attached to the valve holder  27 , the discharge valve  29  is attached to the engaging projecting portion  27   c,  and the lid  30  is overlaid on the valve holder  27  and closed by, e.g., welding, thereby forming a valve holder assembly  33 . In this state, the cylindrical portions  27   a  and  30   a  oppose each other, the partition walls  27   e  and  30   b  are in contact with each other, the suction hole  27   b  and suction port  30   e  communicate with each other, and the discharge hole  27   d  and discharge port  30   c  communicate with each other. 
         [0034]    Then, the motor  2  is fitted in the motor holder  16  of the mounter  15 , and pressed in so as to move in the axial direction (the direction of the arrow A) of the mounter  15 . When the ceiling portion  3   b  as the end face of the motor  2 , which opposes the driving end portion  8   b  is abutted against the lower surface  15   d  of the bottom portion  15   a  of the mounter  15  (the ceiling surface of the motor holder  16 ) while the motor holder  16  is elastically deformed, the recesses  7  of the motor  2  engage with the projections  16   a  of the motor holder  16 . With this engagement, the motor  2  is mounted on the bottom portion  15   a  of the mounter  15 , such that the driving end portion  8   b  of the output shaft  8  protrudes into the mounter  15  from the shaft hole  15   c.  Subsequently, the lower end portion of the driving shaft  21  is fixed to the crank  20 , and the crank  20  is axially fixed to the driving end portion  8   b  of the output shaft  8 . 
         [0035]    Thus, conventionally necessary screws are unnecessary to mount the motor  2  on the bottom portion  15   a  of the mounter  15 . Also, while the motor  2  is fitted in the motor holder  16  of the mounter  15 , the motor  2  can be mounted on the mounter  15  by almost linearly moving the motor  2  along the axial direction of the mounter  15 . This facilitates introducing automatic assembly when mounting the motor  2 . In addition, since the recesses  7  for forming the abutting portion  3   a  for locking the permanent magnetic  6  in a predetermined position when pressing the permanent magnet  6  in the yoke  3  are used, it is unnecessary to newly form the recesses  7  in the motor  2 . 
         [0036]    Furthermore, when attaching the motor  2  to the motor holder  16 , the projections  16   a  of the motor holder  16  engage with the recesses  7  of the motor  2  when the ceiling portion  3   b  of the motor  2  is abutted against the lower surface  15   d  of the bottom portion  15   a  of the mounter  15 . This improves the workability because it is possible to reliably and easily engage the projections  16   a  of the motor holder  16  with the recesses  7  of the motor  2 , and facilitates introducing automatic assembly when mounting the motor  2 . 
         [0037]    Then, the diaphragm  26  is placed on the diaphragm holder  25  by inserting the diaphragm portions  26   a  of the diaphragm  26  into the holding cylinders  25   a  of the diaphragm holder  25 , respectively. In this state, the driving member  23  and diaphragm  26  are assembled with the diaphragm holder  25  by inserting the small-diameter portion  26   c  of each piston portion  26   b  into the mounting hole  23   c  of each driving element  23   b  of the driving member  23 , thereby forming a diaphragm holder assembly  34 . 
         [0038]    A pump assembly  35  is formed by overlaying the valve holder assembly  33  on the diaphragm holder assembly  34 . In this state, the valve holder  27  and the diaphragm portions  26   a  of the diaphragm  26  form three pump chambers  32  (two pump chambers  32  are not shown), and the three sets of the discharge holes  27   d  and suction holes  27   b  of the valve holder  27  respectively correspond to the pump chambers  32 . After that, the pump assembly  35  is moved down from above the mounter  15  and placed on the mounter  15  while the upper portion of the driving shaft  21  is inserted into the non-through hole  23   a  of the driving member  23 . 
         [0039]    In this state, the pump assembly  35  and mounter  15  are integrated by springs (not shown) inserted into the grooves  17  of the mounter  15 , thereby integrally stacking the mounter  15 , diaphragm holder  25 , diaphragm  26 , valve holder  27 , and lid  30 , and forming the diaphragm pump  1 . Thus, the mounter  15  and diaphragm holder  25  are integrally connected. 
         [0040]    The pumping action of the diaphragm pump  1  arranged as described above will now be explained. When the crank  20  is rotated via the output shaft  8  by driving the motor  2 , the swinging end portions of the three driving elements  23   b  of the driving member  23  sequentially swing in the vertical direction. When the swinging end portion of the first driving element  23   b  moves down, the first pump chamber  32  expands via the piston portion  26   b,  so the internal air of the pump chamber  32  is set at a negative pressure. 
         [0041]    Accordingly, the suction valve  28  releases the closure of the suction hole  27   b,  thereby opening the suction hole  27   b.  In this state, air drawn in from the external atmosphere through the suction port  30   e  of the lid  30  flows into the first pump chamber  32 . 
         [0042]    When the swinging end portion of the driving element  23   b  of the expanded first pump chamber  32  moves up after that, the first pump chamber  32  contracts, so the internal air pressure of the first pump chamber  32  rises. Therefore, the discharge valve  29  releases the closure of the discharge hole  27   d,  thereby opening the discharge hole  27   d.  Consequently, the air in the first pump chamber  32  is discharged from the discharge hole  27   d  through the discharge port  30   c,  and supplied to a pressurization target (not shown) connected to, e.g., an air tube (not shown). 
         [0043]    Then, when the crank  20  rotates via the output shaft  8  and the swinging end portion of the second driving element  23   b  moves down, the second pump chamber  32  expands, so the internal air of the pump chamber  32  is set at a negative pressure. Therefore, air drawn in from the external atmosphere through the suction port  30   e  of the lid  30  flows into the expanded second pump chamber  32 . 
         [0044]    When the swinging end portion of the driving element  23   b  of the expanded second pump chamber  32  moves up after that, the pump chamber  32  contracts, so the internal air pressure of the pump chamber  32  rises. Accordingly, the discharge valve  29  releases the closure of the discharge hole  27   d,  thereby opening the discharge hole  27   d.  Consequently, the internal air of the second pump chamber  32  is discharged from the discharge hole  27   d  through the discharge port  30   c,  and supplied to the pressurization target connected to the air tube or the like. 
         [0045]    Furthermore, when the crank  20  rotates via the output shaft  8  and the swinging end portion of the third driving element  23   b  moves down, the third pump chamber  32  expands, so the internal air of the pump chamber  32  is set at a negative pressure. Therefore, air drawn in from the external atmosphere through the suction port  30   e  of the lid  30  flows into the expanded third pump chamber  32 . 
         [0046]    When the swinging end portion of the driving element  23   b  of the expanded third pump chamber  32  moves up after that, the pump chamber  32  contracts, so the internal air pressure of the pump chamber  32  rises. Accordingly, the discharge valve  29  releases the closure of the discharge hole  27   d,  thereby opening the discharge hole  27   d.  As a consequence, the internal air of the third pump chamber  32  is discharged from the discharge hole  27  through the discharge port  30   c,  and supplied to the pressurization target connected to the air tube or the like. Since the three pump chambers  32  thus sequentially perform the expanding/contracting operation, air having little pulsatile flow is continuously supplied from the discharge port  30   c  to the pressurization target. 
       Second Embodiment 
       [0047]    The second embodiment of the present invention will be explained below with reference to  FIG. 4 . The second embodiment differs from the above-described first embodiment in that a mounter  15  has no bottom portion  15   a  and has a cylindrical shape having open upper and lower ends. When mounting a motor  2  on the mounter  15  in this arrangement, the motor  2  is fitted in the mounter  15  from below in the same manner as in the first embodiment. 
         [0048]    Then, the motor  2  is pressed in as it is moved in the direction of an arrow A. Consequently, recesses  7  of the motor  2  engage with projections  16   a  of the mounter  15  while the mounter  15  elastically deforms, thereby mounting the motor  2  on the mounter  15 . In the second embodiment, as in the first embodiment described above, no screws are necessary to mount the motor  2  on the mounter  15 , and the motor  2  can be mounted on the mounter  15  by only almost linearly moving the motor  2  in the direction of the arrow A. This facilitates introducing automated assembly when mounting the motor  2 . 
       Third Embodiment 
       [0049]    The third embodiment of the present invention will be explained below with reference to  FIGS. 5 to 7 . Note that an explanation of the same portions as in the first embodiment will be omitted. 
         [0050]    In  FIG. 5 , reference numeral  115  denotes a crank formed into an almost columnar shape. A driving end portion  108   b  of an output shaft  108  of a motor  102  is fixed to the central portion of the crank  115 , so the crank  115  rotates together with the output shaft  108 . A driving shaft  116  has a lower end portion attached in an inclined state to a portion off-centered from the portion of the crank  115  to which the driving end portion  108   b  is attached. 
         [0051]    Reference numeral  117  denotes a driving member having a non-through hole  117   a  in the center. Three driving elements  117   b  (two driving elements  117   b  are not shown) projecting in a direction perpendicular to the non-through hole  117   a  are formed integrally with the upper end portion of the driving member  117  at an equal angle (120°) in the circumferential direction in a plane. The driving elements  117   b  are slightly inclined downward at the same angle toward swinging end portions, and each swinging end portion has a diaphragm mounting hole  117   c.    
         [0052]    The driving member  117  is rotatably supported by the driving shaft  116  by inserting the upper portion of the driving shaft  116  into the non-through hole  117   a.  When the crank  115  is rotated by driving the motor  102 , the driving shaft  116  rotates while changing the inclining direction, and the swinging end portions of the three driving elements  117   b  sequentially vertically swing via the driving shaft  116 . 
         [0053]    Reference numeral  120  denotes a diaphragm holder formed into an inverse closed-bottom cylindrical shape having an open lower end by using a resin. As shown in  FIG. 7 , three holding cylinders  120   a  (two holding cylinders  120   a  are not shown) formed into a cylindrical shape are formed integrally with the ceiling portion of the diaphragm holder  120  at an equal angle (120°) in the circumferential direction. The inner diameter of the cylindrical portion  120   b  of the diaphragm holder  120  is made slightly larger than the outer diameter of the motor  102 . 
         [0054]    On the inner circumferential surface of the lower portion of the cylindrical portion  120   b  of the diaphragm holder  120 , a plurality of projections  120   c  that engage with recesses  107  of the motor  102  described above project in the direction of the center (the radial direction) of the diameter of the cylindrical portion  120   b.  The diaphragm holder  120  elastically deforms when the motor  102  is fitted in and the recesses  7  engage with the projections  120   c.    
         [0055]    In  FIG. 5 , reference numeral  121  denotes a diaphragm formed into an almost disc shape by a flexible material such as rubber. Three thin-wall diaphragm portions  121   a  are formed at an equal angle (120°) in the circumferential direction. A piston portion  121   b  is formed integrally with the lower portion of the diaphragm portion  121   a  (two diaphragm portions  121   a  are not shown), and a small-diameter portion  121   c  is formed integrally with the lower end of the piston portion  121   b.    
         [0056]    Reference numeral  122  denotes a valve holder formed into an almost disc shape. A cylindrical portion  122   a  integrally stands on the outer periphery of the valve holder  122 , and three suction holes  122   b  (two suction holes  122   b  are not shown) as suction passages are formed in the inner periphery of the cylindrical portion  122   a  at an equal angle (120°) in the circumferential direction. An engaging projecting portion  122   c  integrally stands on the central portion of the valve holder  122 . Around the engaging projecting portion  122   c,  three discharge holes  122   d  (two discharge holes  122   d  are not shown) as discharge passages are formed at an equal angle (120°) in the circumferential direction, and a partition wall  122   e  concentrically stands integrally with the cylindrical portion  122   a.    
         [0057]    Reference numeral  123  denotes an umbrella-shaped suction valve that is attached to the valve holder  122  and opens and closes the suction hole  122   b.  The suction valve  123  regulates the reverse flow of a fluid from a pump chamber  126  (to be described later) to the suction hole  122   b.  Reference numeral  124  denotes a hat-shaped discharge valve that is attached to the engaging projecting portion  122   c  and opens and closes the discharge hole  122   d.  The discharge valve  124  regulates the reverse flow of a fluid from a discharge port  125   c  (to be described later) to the pump chamber  126 . 
         [0058]    Reference numeral  125  denotes a lid formed into an inverse closed-bottom cylindrical shape. A cylindrical portion  125   a  integrally projects downward from the outer periphery, and a partition wall  125   b  having a ring-like planar shape concentric with the cylindrical portion  125   a  integrally projects downward from the central portion. A discharge cylindrical portion  125   d  having the discharge port  125   c  integrally stands on the central portion of the ceiling portion of the lid  125 . A suction cylindrical portion  125   f  having a suction port  125   e  integrally stands on a portion of the periphery of the ceiling portion. 
         [0059]    Next, a method of assembling the diaphragm pump arranged as described above will be explained. Referring to  FIG. 5 , the suction valve  123  is attached to the valve holder  122 , the discharge valve  124  is attached to the engaging projecting portion  122   c,  and the lid  125  is overlaid on the valve holder  122  and closed by, e.g., welding, thereby forming a valve holder assembly  130 . In this state, the cylindrical portions  122   a  and  125   a  oppose each other, the partition walls  122   e  and  125   b  are in contact with each other, the suction hole  122   b  and suction port  125   e  communicate with each other, and the discharge hole  122   d  and discharge port  125   c  communicate with each other. 
         [0060]    Then, the diaphragm holder  121  is placed on the diaphragm holder  120  by inserting each diaphragm portion  121   a  of the diaphragm  121  into the holding cylinder  120   a  of the diaphragm holder  120 . In this state, the driving member  117  and diaphragm  121  are assembled with the diaphragm holder  120  by inserting the small-diameter portion  121   c  of each piston portion  121   b  into the mounting hole  117   c  of each driving element  117   b  of the driving member  117 . 
         [0061]    Subsequently, the lower portion of the driving shaft  116  is fixed to the crank  115 , and the crank  115  is axially fixed to the driving end portion  108   b  of the output shaft  108  of the motor  102 . In this state, the motor  102  is fitted in the diaphragm holder  120  from below, and pressed in as it is moved in the axial direction (the direction of the arrow A) of the diaphragm holder  120 , thereby engaging the recesses  107  of the motor  102  with the projections  120   c  of the diaphragm holder  120  while elastically deforming the diaphragm holder  120 . With this engagement, the motor  102  is attached to the diaphragm holder  120  such that the crank  115  protrudes into the diaphragm holder  120 . At the same time, a diaphragm holder assembly  131  is formed by inserting the upper portion of the driving shaft  116  into the non-through hole  117   a  of the driving member  117 . 
         [0062]    A pump assembly  132  is formed by overlaying the valve holder assembly  130  on the diaphragm holder assembly  131 , and a diaphragm pump  101  is formed by stacking the diaphragm holder  120 , diaphragm  121 , valve holder  122 , and lid  125  and integrating them by using springs (not shown). In this state, the valve holder  122  and the diaphragm portions  121   a  of the diaphragm  121  form three pump chambers  126  (two pump chambers  126  are not shown), and the three discharge holes  122   d  and three suction holes  122   b  of the valve holder  122  respectively correspond to the three pump chambers  126 . 
         [0063]    Thus, conventionally necessary screws are unnecessary to attach the motor  102  to the diaphragm holder  120 , and a mounter for mounting the motor  102  is also unnecessary, so the number of parts reduces. In addition, while the motor  102  is fitted in the diaphragm holder  120 , the motor  102  can be attached to the diaphragm holder  120  by almost linearly moving the motor  102  along the axial direction of the diaphragm holder  120 . This facilitates introducing automatic assembly when assembling the motor  102 . Furthermore, since the recesses  107  for forming the abutting portion  103   a  for locking a permanent magnetic  106  when attaching the permanent magnet  106  to a yoke  103  are used, it is unnecessary to newly form recesses in the motor  102 . 
         [0064]    The pumping action of the diaphragm pump  101  arranged as described above will now be explained. When the crank  115  is rotated via the output shaft  108  by driving the motor  102 , the swinging end portions of the three driving elements  117   b  of the driving member  117  sequentially swing in the vertical direction. When the swinging end portion of the first driving element  117   b  moves down, the first pump chamber  126  expands via the piston portion  121   b,  so the internal air of the pump chamber  126  is set at a negative pressure. 
         [0065]    Accordingly, the suction valve  123  releases the closure of the suction hole  122   b,  thereby opening the suction hole  122   b.  In this state, air drawn in from the external atmosphere through the suction port  125   e  of the lid  125  flows into the first pump chamber  126 . 
         [0066]    When the swinging end portion of the driving element  117   b  of the expanded first pump chamber  126  moves up after that, the first pump chamber  126  contracts, so the internal air pressure of the first pump chamber  126  rises. Therefore, the discharge valve  124  releases the closure of the discharge hole  122   d,  thereby opening the discharge hole  122   d.  Consequently, the air in the first pump chamber  126  is discharged from the discharge hole  122   d  through the discharge port  125   c,  and supplied to a pressurization target (not shown) connected to, e.g., an air tube (not shown). 
         [0067]    Then, when the crank  115  rotates via the output shaft  108  and the swinging end portion of the second driving element  117   b  moves down, the second pump chamber  126  expands, so the internal air of the pump chamber  126  is set at a negative pressure. Therefore, air drawn in from the external atmosphere through the suction port  125   e  of the lid  125  flows into the expanded second pump chamber  126 . 
         [0068]    When the swinging end portion of the driving element  117   b  of the expanded second pump chamber  126  moves up after that, the pump chamber  126  contracts, so the internal air pressure of the pump chamber  126  rises. Accordingly, the discharge valve  124  releases the closure of the discharge hole  122   d,  thereby opening the discharge hole  122   d.  Consequently, the internal air of the second pump chamber  126  is discharged from the discharge hole  122   d  through the discharge port  125   c,  and supplied to the pressurization target connected to the air tube or the like. 
         [0069]    Furthermore, when the crank  115  rotates via the output shaft  108  and the swinging end portion of the third driving element  117   b  moves down, the third pump chamber  126  expands, so the internal air of the pump chamber  126  is set at a negative pressure. Therefore, air drawn in from the external atmosphere through the suction port  125   e  of the lid  125  flows into the expanded third pump chamber  126 . 
         [0070]    When the swinging end portion of the driving element  117   b  of the expanded third pump chamber  126  moves up after that, the pump chamber  126  contracts, so the internal air pressure of the pump chamber  126  rises. 
         [0071]    Accordingly, the discharge valve  124  releases the closure of the discharge hole  122   d,  thereby opening the discharge hole  122   d.  As a consequence, the internal air of the third pump chamber  126  is discharged from the discharge hole  122  through the discharge port  125   c,  and supplied to the pressurization target connected to the air tube or the like. Since the three pump chambers  126  thus sequentially perform the expanding/contracting operation, air having little pulsatile flow is continuously supplied from the discharge port  125   c  to the pressurization target. 
       Fourth Embodiment 
       [0072]    The fourth embodiment of the present invention will be explained below with reference to  FIG. 8 . The fourth embodiment differs from the third embodiment in that an abutting member  120   e  having a closed-bottom cylindrical shape integrally projects downward from the periphery of a ceiling portion  120   d  of a diaphragm holder  120 . The lower surface of a bottom portion  120   f  of the abutting member  120   e  functions as an abutting surface  120   g  against which a ceiling portion  103   b  of a motor  102  abuts, when the motor  102  is fitted in the diaphragm holder  120  from below and pushed as it is moved in the axial direction (the direction of an arrow A) of the diaphragm holder  120 , and recesses  107  of the motor  102  are engaged with projections  120   c  of the diaphragm holder  120  while the diaphragm holder  120  is elastically deformed. 
         [0073]    Accordingly, when the ceiling portion  103   b  of the motor  102  fitted in the diaphragm holder  120  from below abuts against the abutting surface  120   g,  projections  120   c  of the diaphragm holder  120  engage with the recesses  107  of the motor  102 . This improves the reliability and easiness of the work of attaching the motor  102  to the diaphragm holder  120 , and facilitates introducing automated assembly in the assembling work. 
         [0074]    Note that in each embodiment described above, a so-called, three-cylinder pump including three pump chambers is taken as an example. However, the present invention is of course applicable to a diaphragm pump including two or less cylinders or four or more cylinders. Also, the suction valve and discharge valve are separated from the diaphragm in each embodiment, but they may also be formed integrally with the diaphragm. Furthermore, although the motor holder and mounter are formed into a cylindrical shape in each embodiment, they may also have an elliptical cylindrical shape or square cylindrical shape in accordance with the planar shape of the motor. In short, any shape can be used as long as the motor can be fitted in the motor holder or mounter. 
         [0075]    In each embodiment, the recesses formed for forming the abutting portions for locking the permanent magnet when attaching the permanent magnet to the yoke are used as the recesses to be engaged with the projections of the mounter. However, the present invention is not limited to this, and it is of course possible to use other recesses formed in the yoke. 
         [0076]    In each embodiment, one end portion of the driving shaft is fixed to the crank, and the other end portion is pivotally supported in the blind hole of the driving member. However, the present invention is not limited to this. For example, it is also possible to pivotally support one end portion of the driving shaft by the crank, and fix the other end portion to the driving member. Alternatively, it is possible to fix the central portion of the driving shaft to the driving member, and pivotally support the upper and lower ends by the diaphragm holder and crank. Furthermore, the driving shaft itself may be integrated with the driving member. That is, various design changes are possible. In short, the pump need only include a driving member including a driving element that reciprocates in accordance with the rotation of the crank, and a diaphragm for forming a pump chamber that expands and contracts in accordance with the reciprocal motion of the driving element.