PATENT ABSTRACT
A reciprocating pump capable of reducing its overall size by suppressing the size of an entire drive unit. A plurality of piston parts move in the same direction and draw fluid into a plurality of pump chambers and discharge the fluid. The pump chambers are adjacent to each other. A motor has a drive shaft between the centers of piston parts located at both ends in the installation direction of the pump chambers and oriented in a direction substantially orthogonal to the installation direction of the pump chambers and substantially orthogonal to the moving direction of the piston parts. A plurality of cams are aligned adjacent each other in the axial direction on the motor drive shaft. The cams are linked to the piston parts so that the cams cause the reciprocal movement of the piston parts.

PATENT DESCRIPTION
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Japanese Patent Application No. 2014-209756, the disclosure of which is incorporated herein by reference in its entirety. 
       FIELD 
       [0002]    The present invention relates to a reciprocating pump configured to deliver fluid to a specific point by reciprocally moving a plurality of piston parts using a single driving source. 
       BACKGROUND 
       [0003]    The aforementioned reciprocating pump is configured to reciprocally move a plurality of piston parts using a single driving source so as to be advantageous in view of the cost. The backward movement of a piston part allows fluid to be drawn into a pump chamber through an inlet port, and the forward movement of the piston part allows the drawn fluid to be discharged through an outlet port. 
         [0004]    Specifically, two pump chambers which are provided in the left-right direction, left and right cams which are configured to reciprocally move piston parts provided respectively in the two pump chambers, and a drive unit configured to rotationally drive the left and right cams are provided. The cams are attached to a rotation shaft extending in the left-right direction and having both left and right ends rotatably supported via bearings so as to rotate integrally with the rotation shaft. Further, the drive unit includes a motor, a spur gear on the drive side which is externally fitted to a drive shaft of the motor so as to rotate integrally therewith, and a spur gear on the driven side which is attached to the rotation shaft between the left and right cams so as to be rotatable integrally therewith and mesh with the aforementioned spur gear to transmit a torque to the rotation axes of the cams (see, for example, Patent Literature 1). 
       CITATION LIST 
     Patent Literature 
       [0005]    Patent Literature 1: Japanese Patent No. 2552654 B2 (see FIG. 1) 
       SUMMARY 
     Technical Problem 
       [0006]    Patent Literature 1 above requires not only a space to provide the two cams in the left-right direction side-by-side but also a space to provide the bearings that support both left and right ends of the rotation shaft to which the two cams are attached. Further, the rotation shaft needs to be long in the left-right direction so that the spur gear on the driven side configured to transmit power to the rotation shaft can be provided. Therefore, the inconvenience of increasing the size of the entire drive unit in the left-right direction is caused, and thus there is room for improvement. 
         [0007]    In view of the aforementioned situation, the present invention aims to solve the problem by providing a reciprocating pump capable of suppressing the increase in size of the entire drive unit, so as to reduce the overall size. 
       Solution to Problem 
       [0008]    In order to solve the aforementioned problem, a reciprocating pump of the present invention includes: a plurality of pump chambers; piston parts provided respectively in the plurality of pump chambers and configured to draw fluid into the pump chambers and discharge the fluid outside the pump chambers by reciprocal movement; a plurality of rotatably driven cams provided corresponding to the number of piston parts and configured to cause the reciprocal movement of the piston parts; and a single motor configured to rotationally drive the plurality of cams, wherein the plurality of piston parts are configured to move in the same direction so as to draw the fluid into the plurality of pump chambers and discharge the fluid, the plurality of pump chambers are provided adjacent to each other, the motor has a drive shaft located between the centers of the piston parts that are located at both ends in the installation direction of the pump chambers so as to be oriented in a direction that is substantially orthogonal to the installation direction of the pump chambers and is substantially orthogonal to the moving direction of the piston parts, or so as to extend in the same direction as the installation direction of the pump chambers, the plurality of cams are aligned adjacent to each other in the axial direction on the drive shaft of the motor, and the plurality of cams are linked to the plurality of piston parts so that the plurality of cams respectively cause the reciprocal movement of the plurality of piston parts. 
         [0009]    Further, the reciprocating pump of the present invention may have a configuration such that the at least two pump chambers are provided side by side in the left-right direction, the same number of piston parts as the number of the pump chambers are configured to be movable in the front-rear direction that is orthogonal to the left-right direction, and the motor is arranged in the vertical orientation between the center of one of the at least two piston parts that is arranged on one end side in the left-right direction and the center of the other piston part arranged on the other end side in the left-right direction so that the drive shaft of the motor faces&lt;extends?&gt;downward. 
         [0010]    Further, the reciprocating pump of the present invention may have a configuration such that the respective piston parts have extending portions provided on their edges on the cam side and configured to extend toward the drive shaft side of the motor, and the extending portions are displaced from each other in the vertical direction so as to abut the cams corresponding to the respective piston parts. 
         [0011]    Further, the reciprocating pump of the present invention may have a configuration such that the at least two pump chambers are arranged at substantially the same height position. 
         [0012]    Further, the reciprocating pump of the present invention may have a configuration further including guide members configured to guide the reciprocal movement of the piston parts. 
         [0013]    Further, the reciprocating pump of the present invention may have a configuration further including: a pump head with which the at least two pump chambers are integrally formed; a body configured to house the drive shaft of the motor and the at least two cams; and a grand flange configured to connect the pump head to the body, wherein the body has an opening for maintenance formed on its sidewall on the pump head side, and the grand flange comprises an openable closing part configured to close the opening. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  is a side view of a reciprocating pump. 
           [0015]      FIG. 2  is a longitudinal sectional side view of the reciprocating pump. 
           [0016]      FIG. 3  is a front view of a pump head of the reciprocating pump. 
           [0017]      FIG. 4  is a cross sectional plan view of the reciprocating pump. 
           [0018]      FIG. 5  is a front view of a main part of a drive unit of the reciprocating pump from which the pump head is detached. 
           [0019]      FIG. 6A ,  FIG. 6B , and  FIG. 6C  are schematic front views of other three embodiments showing the relationship between cams and extending portions. 
           [0020]      FIG. 7  is a cross sectional plan view of another embodiment of the reciprocating pump. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0021]    Hereinafter, a reciprocating pump will be described based on the drawings. 
         [0022]      FIG. 1  shows a diaphragm pump as an example of the reciprocating pump. The diaphragm pump includes a body  2  including a power supply, a control unit, a drive unit  1 , and others, and a pump head  3  provided in front of the body  2 . The following description will be given on the assumption that, in the pump shown in  FIG. 1 , the left-right direction of the paper is the front-rear direction, the direction passing through the paper is the left-right direction, and the up-down direction of the paper is the vertical direction. 
         [0023]    As shown in  FIG. 1  to  FIG. 3 , a fluid inlet port  4  is formed at the center in the left-right direction in the lower part of the pump head  3 , and a fluid outlet port  5  is formed at the center in the left-right direction in the upper part of the pump head  3 . A hose (not shown) is connected to each of the inlet port  4  and the outlet port  5 . 
         [0024]    Further, as shown in  FIG. 3 , the pump head  3  includes an inlet flow path  6  configured to guide fluid from the inlet port  4 , a pair of left and right inlet-side check valves  7  and  8  through which the fluid in the inlet flow path  6  is drawn, a left pump chamber  9  and a right pump chamber  10  provided adjacent to each other in the left-right direction so as to draw the fluid through the inlet-side check valves  7  and  8  and discharge it, a pair of left and right outlet-side check valves  11  and  12  configured to respectively discharge the fluid in the two pump chambers  9  and  10 , and an outlet flow path  13  configured to guide the fluid discharged through the outlet-side check valves  11  and  12  to the outlet port  5 . 
         [0025]    Further, the pump head  3  is constituted by three members of a body  3 A with which the front portions of the two left and right pump chambers  9  and  10  are integrally formed, and an outlet part  3 B and an inlet part  3 C which are fixed to the top and the bottom of the body  3 A. The two pump chambers  9  and  10  can be formed more closely in the left-right direction by forming the two pump chambers  9  and  10  integrally with the body  3 A, and thus the size of the pump in the left-right direction can be reduced. Moreover, the dimension of the body  3 A in the vertical direction also can be reduced by arranging the two pump chambers  9  and  10  at the same height position, as compared with the arrangement in which the two pump chambers are displaced in the vertical direction. 
         [0026]    Further, a grand flange  15  with which the rear portions of the two pump chambers  9  and  10  on the left and right sides are integrally formed is provided. The grand flange  15  is a coupling member connecting the pump head  3  to the body  2  housing the drive unit  1  (including a drive shaft  19 A of an electric motor  19 , two cams  18 A and  18 B, and the like, which will be described below). Further, provided are a flange  15 A located on the front side and connected by bolts B 1  to the rear edge of the body  3 A of the pump head  3 , a flange (closing part)  15 B located on the rear side and connected by bolts B 2  to a casing  14  constituting the body  2  that houses the drive unit  1 , so as to close a front opening  14 A for maintenance that is formed on a sidewall on the pump head side of the casing  14 , and a coupling part  15 C coupling these front and rear flanges  15 A and  15 B together. Accordingly, the front opening  14 A of the casing  14  is opened by detaching the grand flange  15  from the casing  14 , and the maintenance of the drive unit  1  in the casing  14  can be quickly performed through the opening  14 A. The coupling part  15 C of the grand flange  15  has a cylindrical shape so as to connect the pump head  3  to the casing  14 , and serves also as a support member configured to guide a shaft  21 , which will be described below, by allowing it to slide thereon. The casing  14  is fixed onto the top of a base member V that is substantially trapezoid in side view. 
         [0027]    The drive unit  1  includes piston parts  16  and  17  provided respectively in the two pump chambers  9  and  10  and configured to draw fluid into the pump chambers  9  and  10  by reciprocal movement and discharge it outside the pump chambers  9  and  10 , the cams (which herein are two eccentric cams)  18 A and  18 B provided corresponding to the number of the piston parts  16  and  17  and configured to be rotatably driven so as to reciprocally move the two piston parts  16  and  17 , and the single electric motor  19  configured to rotationally drive the two cams  18 A and  18 B. 
         [0028]    Each piston part  16  or  17  includes a diaphragm  20  provided as a piston in the pump chamber  9  or  10 , the shaft  21  or  22  projecting backward from the diaphragm  20  to cause the diaphragm  20  to pump, and an extending portion  23  provided on the edge on the cam side (rear edge) of the shaft  21  or  22  so as to abut the cam  18 A or  18 B. The diaphragm  20  is made of an elastically deformable material such as rubber, and the fluid can be drawn and discharged by the elastic deformation of the diaphragm  20 . 
         [0029]    In each diaphragm  20 , a disk part  24  made of metal is embedded by insert molding. A stem part  25  projecting from the rear edge of the disk part  24  toward the shaft  21  or  22  side is integrally formed with the disk part  24 . The stem part  25  is configured to have a smaller diameter than the shaft  21  or  22 , and the stem part  25  connects the diaphragm  20  to the shaft  21  or  22  by being screwed into a screw hole formed in the shaft  21  or  22 . Further, the stem part  25  passes through a disk member  26 , and the front end of the shaft  21  or  22  abuts the disk member  26  by screwing the stem part  25  into the screw hole formed in the shaft  21  or  22 . Thereby, the disk member  26  is pressed toward the diaphragm  20  side to be fixed. 
         [0030]    The cams  18 A and  18 B are integrally formed with a cam shaft  27  that is externally fitted to the drive shaft  19 A of the electric motor  19  so as to integrally rotate therewith, so that the cams  18 A and  18 B are adjacent to each other in the vertical direction. The cams  18 A and  18 B form cam faces so that, when the cam  18 A on one side is pressing the shaft  21  on one side toward the front side, the cam  18 B on the other side retracts from the shaft  22  on the other side toward the rear side. A pump with low pulsation can be constituted by forming the cam faces as above. Both the upper and lower ends of the cam shaft  27  are rotatably supported by bearings  29  provided at the top and bottom of the casing  14 . 
         [0031]    As shown in  FIG. 4 , the drive shaft  19 A of the electric motor  19  is oriented in the vertical direction between a center C 1  of the piston part  16  on one end side (left end) in the left-right direction of the two piston parts  16  and  17  and a center C 2  of the piston part  17  on the other end side (right end) in the left-right direction thereof. Here, the drive shaft  19 A is located at a center C 3  in the left-right direction between the center C 1  of the piston part  16  on one side and the center C 2  of the piston part  17  on the other side. Accordingly, the outline of the electric motor  19  does not project over the outline of the casing  14  in plan view. 
         [0032]    As shown in  FIG. 4  and  FIG. 5 , the extending portions  23  are composed of a substantially L-shaped first extending portion  231  constituted by a substantially square first body  231 A connected to a large-diameter disk part  21 A at the end on the cam side of the shaft  21  of the piston part  16  on one side and a substantially rectangular first horizontal part  231 B extending from the upper edge of the first body  231 A toward the side of the piston part on the other side, and a substantially L-shaped second extending portion  232  constituted by a substantially square second body  232 A connected to a large-diameter disk part  22 A at the end on the cam side of the shaft  21  of the piston part  17  on the other side and a substantially rectangular second horizontal part  232 B extending from the lower edge of the second body  232 A toward the first piston part side. Further, the arrangement is such that the first horizontal part  231 B of the first extending portion  231  and the second horizontal part  232 B of the second extending portion  232  are adjacent to each other in the vertical direction. Such an arrangement in which the first horizontal part  231 B of the first extending portion  231  and the second horizontal part  232 B of the second extending portion  232  are adjacent to each other in the vertical direction can reduce the space to arrange the two extending portions  231  and  232  in the vertical direction, and can reduce the size of the drive unit in the vertical direction to such an extent. Further, the first extending portion  231  and the second extending portion  232  are movably biased to the sides of the cams  18 A and  18 B by coil springs S. Accordingly, the first extending portion  231  and the second extending portion  232  are configured to constantly abut the circumferential surfaces of the cams  18 A and  18 B. 
         [0033]    Further, the dimensions in the vertical direction of the first horizontal part  231 B and the second horizontal part  232 B are substantially the same as the dimensions in the vertical direction of the vertically disposed cams  18 A and  18 B. Such setting of the dimensions can increase the portions where the first horizontal part  231 B and the second horizontal part  232 B contact with the vertically disposed cams  18 A and  18 B in the vertical direction. As a result, the shafts  21  and  22  can be smoothly moved. Further, the dimensions in the vertical direction of the first body  231 A and the second body  232 A can be configured to be slightly larger than the diameter dimensions of the large-diameter disk parts  21 A and  22 A at the ends on the cam side of the vertically disposed shafts  21  and  22 , and the dimensions in the vertical direction of the first horizontal part  231 B and the second horizontal part  232 B can be set to a substantially half (preferably, the half or less) of the dimensions in the vertical direction of the first body  231 A and the second body  232 A, so as to prevent (or reduce) the projection of the first horizontal part  231 B and the second horizontal part  232 B over the upper and lower edges of the first body  231 A and the second body  232 A in the vertical direction in side view. 
         [0034]    A guide member  28  configured to guide the reciprocal movement of each piston part  16  or  17  is provided. The guide member  28  is made of a rod member having a circular cross section and passes through the horizontal part  231 B or  232 B, and the distal end of the guide member  28  passing therethrough is fixed to the grand flange  15 . In particular, when the free end (part configured to move away from the shaft  21  or  22 ) of the horizontal part  231 B or  232 B is pressed by the cam  18 A or  18 B to move the piston part  16  or  17  forward, deflection and deformation of the shaft  21  or  22  can be prevented. Further, when the stem part  25  is screwed into the shaft  21  or  22  in order to set the diaphragm  20  into the shaft  21  or  22 , the rotation of the shaft  21  or  22  in conjunction with the rotation of the stem part  25  can be prevented by providing the guide member  28 . A head  28 A having a larger diameter than a stem portion  28 B is provided at the end of the guide member  28 , but may be omitted. 
         [0035]    As described above, as compared with the configuration in which the two cams  18 A and  18 B are provided on the rotation shaft supported via bearings in the left-right direction, the arrangement in which the two pump chambers  9  and  10  are provided adjacent to each other, the drive shaft  19 A of the electric motor  19  is located between the centers of the piston parts  16  and  17  that are located at both ends in the installation direction of the pump chambers  9  and  10  so as to be oriented in a direction that is substantially orthogonal to the installation direction of the pump chambers  9  and  10  and is orthogonal to the moving direction of the piston parts  16  and  17 , and the two cams  18 A and  18 B are arranged adjacent to each other on the drive shaft  19 A of the electric motor  19  can eliminate the need for the space to provide the two cams  18 A and  18 B in the left-right direction and the space to provide the bearings, and also can eliminate the need for providing a gear on the driven side on the rotation shaft in order to interlock the drive shaft  19 A of the electric motor  19  with the rotation shaft, so that the increase of the dimension in the left-right direction of the drive unit  1  can be suppressed to such an extent. Further, the two cams  18 A and  18 B are arranged adjacent to each other on the drive shaft  19 A, and therefore the configuration of linking the two cams  18 A and  18 B respectively to the two piston parts  16  and  17  so as to reciprocally move the two piston parts  16  and  17  also can suppress the increase of the size in the vertical direction. Accordingly, the increase of the dimension in the vertical direction of the drive unit can be suppressed. 
         [0036]    Next, using the diaphragm pump configured as above, the operation of delivering fluid by drawing a certain amount of fluid each time will be described. 
         [0037]    First, the electric motor  19  is driven, and the driving force is transmitted to the drive shaft  19 A. The transmitted driving force causes the cam shaft  27  to rotate about the vertical axis so as to rotate the two cams  18 A and  18 B. The rotation of the cams  18 A and  18 B causes the reciprocal movement of the first and second piston parts  16  and  17 . 
         [0038]    The reciprocal movement of the piston parts  16  and  17  causes elastic deformation of the diaphragms  20  to draw and discharge the fluid. In  FIG. 4 , the piston part  17  on the right side (one side) moves to the backward movement side (the rear side) to draw fluid into the right pump chamber  10 . In response to this movement, the piston part  16  on the left side (the other side) moves to the forward movement side (the front side) to discharge fluid in the left pump chamber  9 . In this way, the operation of drawing fluid into one of the pump chambers  9  and  10  and discharging fluid that has been drawn in the other of the pump chambers  10  and  9  is repeated, so that a certain amount of fluid is drawn each time to deliver it. 
         [0039]    The present invention is not limited to the aforementioned embodiment, and various modifications can be made without departing from the gist of the present invention. 
         [0040]    In the aforementioned embodiment, the diaphragm is used as a piston, but a plunger may be used. In this case, the configuration can be such that one of the two pistons is a plunger and the other is a diaphragm, or both of them may be configured as plungers. 
         [0041]    Further, in the aforementioned embodiment, the case of using the two piston parts is shown, but a pump may be constituted by using three or more piston parts. 
         [0042]    Further, in the aforementioned embodiment, the pump chambers  9  and  10  are arranged in the left-right direction, but a plurality of pump chambers may be provided in the vertical direction. In the case of providing a plurality of pump chambers in the vertical direction, the electric motor is arranged so that the drive shaft of the electric motor is oriented in the left-right direction. 
         [0043]    Further, in the aforementioned embodiment, the electric motor  19  is arranged so that the drive shaft  19 A of the electric motor  19  faces downward, but the electric motor  19  may be arranged so that the drive shaft  19 A faces upward. 
         [0044]    Further, in the aforementioned embodiment, the two shafts  21  and  22  are arranged at the same height position, but the left shaft  21  may be arranged higher than the right shaft  22 , as shown in  FIG. 6A . In this case, the extending portions  23  abutting the vertically disposed cams  18 A and  18 B are composed of the first extending portion  231  constituted by a substantially square first body  231   a  connected to the large-diameter disk part  21 A at the end on the cam side of the shaft  21  on one side and a substantially rectangular first horizontal part  231   b  extending from the vertical center of the edge (the right edge in the figure) on the shaft  22  side on the other side of the first body  231   a  toward the shaft  22  side on the other side, and the second extending portion  232  constituted by a substantially square second body  232   a  connected to the large-diameter disk part  22 A at the end on the cam side of the shaft  22  on the other side and the substantially rectangular second horizontal part  232   b  extending from the vertical center of the edge (the left edge in the figure) on the shaft  21  side on one side of the second body  232   a  toward the shaft  21  side on one side. 
         [0045]    Further, in the aforementioned embodiment, the first horizontal part  231 B and the second horizontal part  232 B are configured so as not to project over the upper and lower edges of the first body  231 A and the second body  232 A in the vertical direction in side view, but the first horizontal part  231   b  on one side (which is the left side in the figure, but may be the right side) may be configured to extend toward the second body  232   a  side on the other side, while projecting upwardly over the upper edge of the first body  231   a  in side view, as shown in  FIG. 6B . In  FIG. 6B , the case where the first horizontal part  231   b  projects upwardly over the upper edge of the first body  231   a,  but the first horizontal part  231   b  may be configured to project downwardly over the lower edge of the first body  231   a.    
         [0046]    Further, in the aforementioned embodiment, the drive shaft  19 A of the electric motor  19  is located between the centers of the piston parts  16  and  17  that are located at both ends in the installation direction of the pump chambers  9  and  10 , so as to be oriented in a direction that is substantially orthogonal to the installation direction of the pump chambers  9  and  10  and is substantially orthogonal to the moving direction of the piston parts  16  and  17 , but the drive shaft  19 A of the electric motor  19  may be arranged so as to extend in the same direction as the installation direction (the vertical direction in the figure) of the pump chambers, as shown in  FIG. 6C . With such a configuration, the extending portions  23  shown in  FIG. 5 ,  FIG. 6A , and  FIG. 6B  are configured as substantially square plate members  231  and  232  that are slightly larger than the large-diameter disk parts  21 A and  22 A at the ends on the cam side of the shafts  21  and  22 . Then, the cams  18 A and  18 B abut the center portions in the left-right direction of the plate members  231  and  232 , thereby stably pressing the shafts  21  and  22  without deflection. 
         [0047]    Further, in the aforementioned embodiment, a configuration in which the two pump chambers (hereinafter, referred to as the first pump chambers)  9  and  10  are provided in the left-right direction is shown, but an embodiment of providing four pump chambers  9 ,  10 ,  30 , and  31  in total by providing a plurality (herein two) of second (other) pump chambers  30  and  31  so as to face the left and right pump chambers  9  and  10  in the front-rear direction with the same number (herein two) of cams  18 A and  18 B interposed therebetween is also possible. In  FIG. 7 , characters indicating the front, rear, left, and right sides are shown in the figure for the ease of description. 
         [0048]    The second pump chamber  30  or  31  includes a second piston part  32  or  33  configured to be reciprocally moved by one of the plurality (two) of cams  18 A and  18 B. Fluid is drawn into the second pump chamber  30  or  31  and is discharged outside the second pump chamber  30  or  31 , by the reciprocal movement of the second piston part  32  or  33 . Each second piston part  30  or  31  includes a diaphragm  34  provided as a piston in the second pump chamber  30  or  31 , a shaft  35  or  36  projecting forward from the diaphragm  34  to cause the diaphragm  34  to pump, and an extending portion  37  provided at the end on the cam side (front end) of the shaft  35  or  36  so as to abut the cam  18 A or  18 B. 
         [0049]    The diaphragm  34  is made of an elastically deformable material such as rubber, and the fluid can be drawn and discharged by the elastic deformation of the diaphragm  34 . The extending portions  37  are composed of a substantially L-shaped first extending portion  371  constituted by a substantially square first body  371 A connected to a large-diameter disk part  35 A at the end on the cam side of the shaft  35  of the second piston part  32  on one side and a substantially rectangular first horizontal part  371 B extending from the lower edge of the first body  371 A toward the second piston part side on the other side, and a substantially L-shaped second extending portion  372  constituted by a substantially square second body  372 A connected to a large-diameter disk part  36 A at the end on the cam side of the shaft  36  of the second piston part  33  on the other side and a substantially rectangular second horizontal part  372 B extending from the upper edge of the second body  372 A toward the second piston part side on one side. Further, as described above, the arrangement is such that the first horizontal part  371 B of the first extending portion  371  and the second horizontal part  372 B of the second extending portion  372  are adjacent to each other in the vertical direction. Further, the first extending portion  371  and the second extending portion  372  are movably biased to the sides of the cams  18 A and  18 B by coil springs S. Accordingly, the first extending portion  371  and the second extending portion  372  are configured to constantly abut the circumferential surfaces of the cams  18 A and  18 B. In  FIG. 7 , two bodies  3 A 1  and  3 A 2  are provided on the front and rear ends of the reciprocating pump, two grand flanges  15  as described above (see  FIG. 4 ) are provided on the rear end of the body  3 A 1  and on the front end of the body  3 A 2 , and the open ends of the two grand flanges  15  are closed by a casing  38 . 
         [0050]    As described above, in the four pump chambers  9 ,  10 ,  30 , and  31 , fluid in the two pump chambers  9  and  30  is discharged, and fluid is drawn into the other two pump chambers  10  and  31 . After this operation, fluid is drawn into the two pump chambers  9  and  30 , and the fluid in the other two pump chambers  10  and  31  is discharged. This configuration allows the fluid in the two pump chambers to be constantly and concurrently discharged by repeating these operations, but the timing of discharging may be changed. In  FIG. 7 , the configuration is such that fluid in the two pump chambers  9  and  30  located on the left side in the pump chambers that are opposed in the front-rear direction is discharged, and fluid is drawn into the other two pump chambers  10  and  31  located on the right side in the pump chambers that are opposed in the front-rear direction, but the configuration may be such that, in the four pump chambers  9 ,  10 ,  30 , and  31  located at the four corners of the reciprocating pump, fluid in the two pump chambers  9  and  31  located on one diagonal line is discharged, and fluid is drawn into the two pump chambers  10  and  30  located on the other diagonal line. Further, in  FIG. 7 , the four pump chambers  9 ,  10 ,  30 , and  31  are shown, but embodiments of providing six and eight pump chambers are also possible. In the case of using six pump chambers, the embodiment would be such that two pump chambers are further provided above or below the four pump chambers  9 ,  10 ,  30 , and  31  shown in  FIG. 7 , and one drive cam corresponding to the two pump chambers is provided in an extending portion obtained by extending the cam shaft  27  upwardly or downwardly. Further, in the case of using eight pump chambers, the embodiment would be such that four pump chambers having the same configuration are further provided above or below the four pump chambers  9 ,  10 ,  30 , and  31 , and two drive cams corresponding to the four pump chambers are provided in an extending portion obtained by extending the cam shaft  27 . 
       REFERENCE SIGNS LIST 
       [0051]      1 : Drive unit 
         [0052]      2 : Body 
         [0053]      3 : Pump head 
         [0054]      3 A,  3 A 1 ,  3 A 2 : Body 
         [0055]      3 B: Outlet part 
         [0056]      3 C: Inlet part 
         [0057]      4 : Inlet port 
         [0058]      5 : Outlet port 
         [0059]      6 : Inlet flow path 
         [0060]      7 ,  8 : Inlet-side check valve 
         [0061]      9 ,  10 ,  30 ,  31 : Pump chamber 
         [0062]      11 ,  12 : Outlet-side check valve 
         [0063]      13 : Outlet flow path 
         [0064]      14 : Casing 
         [0065]      14 A: Opening 
         [0066]      15 : Grand flange 
         [0067]      15 A,  15 B: Flange 
         [0068]      15 C: Coupling part 
         [0069]      16 ,  17 : Piston part 
         [0070]      18 A,  18 B: Cam 
         [0071]      19 : Electric motor 
         [0072]      19 A: Drive shaft 
         [0073]      20 ,  34 : Diaphragm 
         [0074]      21 ,  22 ,  35 ,  36 : Shaft 
         [0075]      23 ,  37 : Extending portion 
         [0076]      38 : Casing 
         [0077]      24 : Disk part 
         [0078]      25 : Stem part 
         [0079]      26 : Disk member 
         [0080]      27 : Cam shaft 
         [0081]      28 : Guide member 
         [0082]      28 A: Head 
         [0083]      28 B: Stem portion 
         [0084]      29 : Bearing 
         [0085]      231 ,  232 ,  371 ,  372 : Extending portion (plate member) 
         [0086]      231 A,  232 A,  371 A,  372 A: Body 
         [0087]      231 B,  232 B,  371 B,  372 B: Horizontal part 
         [0088]    B 1 , B 2 : Bolt 
         [0089]    C 1 , C 2 : Center 
         [0090]    C 3 : Center 
         [0091]    S: Coil spring 
         [0092]    V: Base member