Abstract:
A casing body is formed with a vent hole. The casing body has an inner face formed with a plurality of grooves respectively communicated with the vent hole. A plurality of diaphragms are respectively inserted into the grooves to form a plurality of pump chambers. An actuator actuates the diaphragms to compress or decompress the pump chambers.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a pump provided with diaphragms, and more particularly, to a compact pump which is used for a sphygmomanometer or the like. 
     A related-art compact pump of this type is now described by reference to FIGS. 3 and 4. As shown in FIG. 3, a compact pump  1  used for a sphygmomanometer or the like is provided with two diaphragms  4  constituting pump chambers  3  within a case  2  which is of rectangular parallelepiped shape when viewed from the top. The diaphragms  4  are integrated, thereby constituting a diaphragm assembly  5 . 
     A substantially-cylindrical vent valve section  6  is provided in an upright position in the center of the diaphragm assembly  5 . The vent valve section  6  is press-inserted into an interior wall of a vent hole  8  drilled in the center of an upper case  7 . 
     Intake valves  9  are provided in positions on the upper case  7  which are located above and aligned with centers of the respective diaphragms  4 . Portions of the intake valves  9  facing the pump chambers  3  are formed into sealing sections  9   a . The intake valves  9  are passed through small holes  10  drilled in the upper case  7 . Stopper sections  9   b  which are larger in diameter than the small holes  10  are formed in the upper face of the upper case  7 . The sealing sections  9   a  are brought into pressing contact with a lower face of the upper case  7 . Several intake holes  11  are drilled in the vicinity of the peripheries of the small holes  10 , and the sealing sections  9   a  of the intake valves  9  seal the intake holes  11 . 
     A pivotable member  12  is pivotally joined to lower ends of the diaphragms  4 . The pivotable member  12  is constructed so as to pivot, by an eccentric shaft  13  which rotates. More specifically, an upper end of the eccentric shaft  13  is fitted into an insertion hole  14   a  formed in a boss section  14  formed so as to protrude downward from the center on a lower face of the pivotable member  12 . A lower end of the eccentric shaft  13  is loosely fitted into an eccentric hole  15   a  eccentrically formed in a rotor  15 . The rotor  15  is secured on an end of a rotary shaft  16  of a motor (not shown). 
     FIG. 4 is a bottom view of the upper case  7 . Formed in the bottom face of the upper case  7  are the vent hole  8  and vent grooves  17  for establishing communication with the pump chambers  3  provided in the diaphragms  4 . 
     The rotary drive shaft  16  of the motor rotates, whereupon the rotor  15  rotates. In turn, the eccentric shaft  13  loosely fitted into the eccentric hole  15   a  of rotor  15  is rotated, whereupon the pivotable member  12  undergoes pivotal movement, to thereby vertically actuate the lower ends of the diaphragms  4 . When the lower end of one of the diaphragms  4  is lowered by the pivotable member  12 , the inside of the diaphragm  4  assumes negative pressure, and the vent valve section  6  seals the vent hole  8 . Further, the sealing section  9   a  of the intake valve  9  is opened, thereby enabling inflow of air by way of the inlet hole  11 . 
     Next, when the lower end of one of the diaphragms  4  is actuated upward, the inside of the diaphragm  4  assumes high pressure. The sealing section  9   a  of the intake valve  9  brings the inlet hole  11  into a sealed state, releasing the space between the vent valve section  6  and the vent hole  8 . The air of the pump chamber  3  is discharged to the outside from the vent hole  8  by way of the vent groove  17 . 
     In the related-art compact pump, it is necessary to provide intake valves  9  which are individual members, to drill the small hole  10  and the intake holes  11 , and to take care of position matching of the sealing portion  9   a  of the intake valve  9  and the inlet holes  11 . Hence, the numbers of parts and assembling operations are accordingly increased, thereby total cost is also increased. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a pump provided with diaphragms, in which a decrease in the numbers of parts and assembling operations by use of a simple construction to thereby enable cost cutting. 
     In order to achieve the above object, according to the present invention, there is provided a pump, comprising: 
     a casing body formed with a vent hole, the casing body having an inner face formed with a plurality of grooves respectively communicated with the vent hole; 
     a plurality of diaphragms, respectively inserted into the grooves to form a plurality of pump chambers; and 
     an actuator, which actuates the diaphragms to compress or decompress the pump chambers. 
     Preferably, the actuator is formed with a plurality of intake holes, and each of the diaphragm is provided with an intake valve section communicated with an associated one of the intake holes. 
     Here, it is preferable that the intake valve section is a flap member formed by incising a part of each diaphragm. 
     In the above configurations, since the grooves into which the diaphragms are inserted form a part of the vent hole, it is not necessary to separately provide such a member as the intake valve member shown in FIG. 3, and to separately drill such holes as the intake hole and the vent groove shown in FIG. 4, thereby, enabling a decrease in the numbers of parts and assembly operations by use of a simple structure and in turn enabling cost cutting. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a longitudinal cross-sectional view of a pump according to an embodiment of the invention; 
     FIG. 2 is a bottom view of an upper case of the pump; 
     FIG. 3 is a longitudinal cross-sectional view of a related-art pump; and 
     FIG. 4 is a bottom view of an upper case of the related-art pump. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment of the invention will be described in detail by reference to FIGS. 1 and 2. As shown in FIG. 1, a compact pump  21  is equipped with two diaphragms  24  partly constituting pump chambers  23  within a case  22  which is of rectangular parallelepiped shape when viewed from the top. Provided below the diaphragms  24  is a pivotable member  25  which vertically actuates lower faces of the diaphragms  24 . The case  22  is constituted of three stages; that is, an upper case  26 , a middle case  27 , and a lower case  28 . Flanges  24   a  of the diaphragms  24  are sandwiched between the upper case  26  and the middle case  27 , whereby the diaphragms  24  are retained in the case  22 . 
     Shaft members  29  are provided at respective ends of the pivotable member  25  so as to protrude upward, and intake holes  29   a  are formed in the centers of the respective shaft members  29 . Hollow attachment members  30 ,  30  are provided so as to protrude in the centers on the lower faces of the respective diaphragms  24 . The shaft members  29  are hermetically fitted into the hollow attachment members  30 , whereby the diaphragms  24  are attached to the pivotable member  25 . 
     Portions of the bottom centers of the diaphragms  24  corresponding to the intake holes  29   a  are incised, whereby flap-like intake valve sections  31  are formed in a reclosable manner. A method of forming the intake valve sections  31  is not limited to the incision method but may be another method. 
     An eccentric rotary shaft  32 , which is pivoted by eccentric rotation of the pivotable member  25 , is passed through and fixed to the center of the pivotable member. A lower end of the rotary shaft  32  is loosely fitted into an eccentric hole  33   a  eccentrically drilled in a rotor  33 . The rotor  33  is secured to an upper end of the rotary shaft  34  of a motor (not shown). An upper end of the eccentric rotary shaft  32  is loosely fitted into an indentation  27   a  drilled in the center of the center case  27 . 
     As shown in FIG. 2, a vent hole  35  is formed in the center of the case  26 . Formed in the lower face of the upper case  26  are annular recessed grooves  36  for enabling insertion of upper ends of the diaphragms  24 . An outer periphery of the vent hole  35  is communicated with outer peripheries of the annular recessed grooves  36 , thereby forming air communication ports  37 . 
     The upper ends of the diaphragms  24  are brought into pressing contact with inner wall sections  36   a  of the annular recessed grooves  36 , thereby constituting vent valve sections  38 . 
     When the rotor  33  is rotated as a result of rotation of the rotary drive shaft  34 , the eccentric rotary shaft  32  rotates eccentrically. As a result, the pivotable member  25  is pivoted, thereby vertically actuating lower end sections of the diaphragms  24 . For instance, when the lower end of one of the diaphragms  24  is actuated downward, the inside of the diaphragm  24  assumes negative pressure. The vent valve section  38  is brought into intimate contact with the interior wall face  36   a  of the annular recessed groove  36 , thereby sealing the upper portion of the pump chamber  23 . On the other hand, the intake valve section  31  is opened, thereby enabling air inflow from the intake hole  29   a  to the inside of the diaphragm  24 . 
     When the lower end of the diaphragm  24  is actuated upward, the inside of the diaphragm  24  assumes high pressure. When the air intake valve section  31  closes the intake hole  29   a , while the vent valve section  38  departs from the corresponding wall interior wall face  36   a , thereby venting air. The vented air from the vent valve section  38  is discharged to the outside of the case  22  from the vent hole  35  by way of the annular recessed groove  36  and the air communication port  37 . 
     In this embodiment, since parts of the annular recessed grooves  36  into which the upper part of the diaphragms  24  are inserted to form the air communication port  37 , it is not necessary to separately provide such a member as the intake valve member  9  shown in FIG. 3, and to separately drill such holes as the intake hole  11  and the vent groove  17  shown in FIG. 4, thereby, enabling a decrease in the numbers of parts and assembly operations by use of a simple structure and in turn enabling cost cutting. 
     As a matter of course, the present invention is susceptible to various modifications within the scope of the invention, and the modifications fall within the scope of the invention.